ML16004A190
| ML16004A190 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 03/07/2016 |
| From: | Michelle Moser Division of License Renewal |
| To: | |
| Michelle Moser 415-6509 | |
| References | |
| Download: ML16004A190 (90) | |
Text
ESSENTIAL FISH HABITAT ASSESSMENT
Essential Fish Habitat Assessment Seabrook Station, Unit 1 License Renewal Docket Number 50-443 U.S. Nuclear Regulatory Commission Rockville, Maryland
i TABLE OF CONTENTS D-1.1 Introduction................................................................................................................ D-1-1 D-1.2 Description of the Proposed Action............................................................................ D-1-1 D-1.2.1 Site Location and Description....................................................................... D-1-2 D-1.2.1.1 Cooling and Auxiliary Water Systems............................................ D-1-2 D-1.3 Essential Fish Habitat Species Near the Site and Potential Adverse Effects............. D-1-8 D-1.3.1 Essential Fish Habitat Species Identified for Analysis.................................. D-1-8 D-1.3.2 Potential Adverse Effects to Essential Fish Habitat.................................... D-1-10 D-1.3.2.1 Information Related to Potential Adverse Impact on All Essential Fish Habitat Species................................................... D-1-13 D-1.3.2.2 Combined Impacts (Monitoring Data).......................................... D-1-24 D-1.3.3 Adverse Effects on Essential Fish Habitat by Species............... D-1-32 D-1.3.3.1 American Plaice (Hippoglossoides platessoides) (Juvenile and Adult)................................................................................... D-1-32 D-1.3.3.2 Atlantic butterfish (Peprilus triacanthus) (All Life Stages)............ D-1-33 D-1.3.3.3 Atlantic cod (Gadus morhua) (All Life Stages)............................. D-1-36 D-1.3.3.4 Atlantic herring (Clupea harengus) (Juvenile and Adult)............. D-1-38 D-1.3.3.5 Atlantic mackerel (Scomber scombrus) (All Life Stages)............. D-1-40 D-1.3.3.6 Atlantic sea scallop (Placopecten magellanicus) (All Life Stages)....................................................................................... D-1-43 D-1.3.3.7 Atlantic Surfclam (Spisula solidissima) (Juveniles and Adults).... D-1-45 D-1.3.3.8Haddock (Melanogrammus aeglefinus) (Juvenile)....................... D-1-46 D-1.3.3.9 Monkfish/Goosefish (Lophius americanus) (All Life Stages)....... D-1-48 D-1.3.3.10Ocean pout (Macrozoarces americanus) (All Life Stages)......... D-1-50 D-1.3.3.11Pollock (Pollachius virens) (Juvenile)......................................... D-1-52 D-1.3.3.12Red hake (Urophycis chuss) (All Life Stages)........................... D-1-54 D-1.3.3.13Scup (Stenotomus chrysops) (Juvenile and Adult).................... D-1-56 D-1.3.3.14Summer flounder (Paralicthys dentatus) (Adult)........................ D-1-57 D-1.3.3.15Whiting/Silver hake (Merluccius bilinearis) (All life stages)........ D-1-59 D-1.3.3.16Windowpane flounder (Scopthalmus aquosus) (Juveniles and Adults) D-1-61 D-1.3.3.17Winter flounder (Pleuronectes americanus) (All Life Stages).... D-1-63 D-1.3.3.18Yellowtail flounder (Pleuronectes ferruginea) (Juveniles and Adults) D-1-65 D-1.3.3.19Essential Fish Habitat Species Not Likely to Regularly Occur Near Seabrook............................................................................ D-1-67 D-1.4 Cumulative Effects to Essential Fish Habitat........................................................... D-1-68 D-1.5 Essential Fish Habitat Conservation Measures....................................................... D-1-71 D-1.6 Conclusion............................................................................................................... D-1-74 D-1.7 References............................................................................................................... D-1-76
ii Figures Figure D-1-1. Location of Seabrook, 6-mi (10-km) region.................................................... D-1-3 Figure D-1-2. Location of Seabrook, 50-mi (80-km) region.................................................. D-1-4 Figure D-1-3. Seabrook site boundary and facility layout..................................................... D-1-5 Figure D-1-4. Intake shafts and caps at Seabrook............................................................... D-1-6 Figure D-1-5. Profile of intake tunnel and shafts at Seabrook.............................................. D-1-7 Figure D-1-6. Circulating water pumphouse at Seabrook..................................................... D-1-8 Figure D-1-7. Sampling Stations for Seabrook Station aquatic monitoring......................... D-1-25 Tables Table D-1-1. Species of fish with designated EFH in the vicinity of Seabrook..................... D-1-9 Table D-1-2. Relative commonness of EFH species in Seabrook monitoring, entrainment, and impingement studies.......................................................... D-1-11 Table D-1-3. Aquatic resource issues identified in the GEIS.............................................. D-1-13 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species.............................................................. D-1-15 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species..................................................... D-1-17 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species............................................................................................. D-1-19 Table D-1-7. Number of bivalve larvae entrained (x 109).................................................... D-1-21 Table D-1-8. Mean density (No./1,000m3) and upper and lower 95% confidence limits (CL) of the most common fish eggs and larvae from 1982-2009 monitoring data at Seabrook......................................................................... D-1-26 Table D-1-9. Geometric mean catch per unit effort (CPUE) (No. per 10-minute tow) and upper and lower 95% CL during preoperational and operational monitoring years for the most abundant species........................................... D-1-27 Table D-1-10. Geometric mean CPUE (No. per 24-hr surface and bottom gill net set) and coefficient of variation (CV) during preoperational (1976-1989) and operational monitoring years (1990-1996).................................................... D-1-28 Table D-1-11. Geometric mean CPUE (No. per seine haul) and upper and lower 95% CL during preoperational and operational monitoring years................. D-1-30 Table D-1-12. Kelp density (No. per 100 m2) and upper and lower 95% CL during preoperational and operational monitoring years.......................................... D-1-31 Table D-1-13. Summary of NRC conclusions Regarding the Effect on Habitat by Species and Life Stages................................................................................ D-1-74
iii ABBREVIATIONS, ACRONYMS, AND SYMBOLS ac acre ADAMS Agencywide Documents Access and Management System BACI before-after control-impact CFR U.S. Code of Federal Regulations cfs cubic feet per second CL confidence limit cm centimeter CO2 carbon dioxide CPUE catch per unit effort CV coefficient of variation CWA Clean Water Act DFO Fisheries and Oceans Canada EEP Estuary Enhancement Program EFH Essential Fish Habitat EPA U.S. Environmental Protection Agency ER Environmental Report FPLE Florida Power Light Energy Seabrook fps feet per second FR Federal Register ft foot FMP fishery management plan GEIS generic environmental impact statement gpm gallons per minute ha hectare in.
inch kg kilogram km kilometer lb pound m
meter m/s meters per second m3 cubic meters m3/day cubic meters per day m3/s cubic meters per second m3/yr cubic meters per year MAFMC Mid-Atlantic Fishery Management Council MARMAC Marine Resources Monitoring, Assessment, and Prediction MDS multi-dimensional scaling mgd million gallons per day mi mile
iv mm millimeter MSA Magnuson-Stevens Fishery and Conservation Management Act MSL mean sea level MT metric tons NAI Normandeau Associates, Inc.
NEFMC New England Fishery Management Council NEFSC Northeast Fishery Science Center NEPA U.S. National Environmental Policy Act of 1969 NextEra NextEra Energy Seabrook, LLC NPDES National Pollutant Discharge Elimination System NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric Administration NRC U.S. Nuclear Regulatory Commission PIC proposal for information collection ppt parts per thousand Seabrook Seabrook Station, Unit 1 SEIS supplemental environmental impact statement USGCRP U.S. Global Change Research Program
1 ESSENTIAL FISH HABITAT ASSESSMENT FOR THE PROPOSED LICENSE RENEWAL OF SEABROOK STATION Introduction In compliance with Section 305(b)(2) of the Magnuson-Stevens Fishery Conservation and Management Act (MSA), as amended by the Sustainable Fisheries Act of 1996 (Public Law 104-267), the U.S. Nuclear Regulatory Commission (NRC) prepared this Essential Fish Habitat (EFH) assessment for the proposed Federal action: NRCs decision whether or not to renew the operating license for Seabrook Station (Seabrook), Unit 1. Seabrook is located in Rockingham County, NH, on the shore of the Hampton-Seabrook Estuary and the Gulf of Maine.
Pursuant to the MSA, NRC staff requested, via letter dated July 16, 2010 (NRC 2010), that the National Marine Fisheries Service (NMFS) provide information on EFH near the Seabrook site.
In their response to NRC, NMFS (2010) indicated that marine waters off Seabrook and the Hampton-Seabrook Estuary have been designated as EFH for 23 Federally managed species and directed the NRC to prepare an EFH assessment as part of the EFH consultation process.
Accordingly, this EFH assessment does the following:
describes the proposed action, identifies relevant commercial, Federally managed species within the vicinity of the proposed site, assesses if the proposed action may adversely affect any designated EFH, and describes potential measures to avoid, minimize, or offset potential adverse impacts to EFH as a result of the proposed action.
Description of the Proposed Action The proposed Federal action is NRCs decision of whether or not to renew the operating license for Seabrook for an additional 20 years beyond the original 40-year term of operation.
NextEra Energy Seabrook, LLC (NextEra) initiated the proposed Federal action by submitting an application for license renewal of Seabrook, for which the existing license, NPF-86, expires on March 15, 2030. If NRC issues a renewed license for Seabrook, NextEra could continue to operate until the 20-year terms of the renewed license expire in 2050. If the operating license is not renewed, then the facility must shut down on or before the expiration date of the current operating license (March 15, 2030).
Pursuant to the NRCs environmental protection regulations in Title 10 of the U.S. Code of Federal Regulations (CFR) Part 51, which implement the U.S. National Environmental Policy Act of 1969 (NEPA), the NRC is publishing this supplemental environmental impact statement (SEIS) for Seabrook concurrent with this EFH Assessment. The SEIS is a site-specific supplement to the Generic Environmental Impact Statement [GEIS] for License Renewal of Nuclear Plants, NUREG-1437 (NRC 1996).
NextEra (2010) has proposed no major construction, refurbishment, or replacement activities associated with the proposed Federal action. During the proposed license renewal term, NextEra would continue to perform site maintenance activities as well as vegetation management on the transmission line right-of-ways that connect Seabrook to the electric grid.
2 D-1.2.1 Site Location and Description Seabrook is located in the Town of Seabrook, Rockingham County, NH, 2 mi (3.2 km) west of the Atlantic Ocean. Seabrook is approximately 2 mi (3.2 km) north of the Massachusetts state line, 15 mi (24 km) south of the Maine state line, and 10 mi (16 km) south of Portsmouth, NH.
Two metropolitan areas lie within 50 mi (80 km) of the site: Manchester, NH (31 mi (50 km) west-northwest) and Boston, MA (41 mi (66 km) south-southwest). Figure D-1-1 and Figure D-1-2 present the 6-mi (10-km) and 50-mi (80-km) area surrounding Seabrook, respectively.
The Seabrook site spans 889 acres (ac) (360 hectare (ha)) on a peninsula of land bordered by Browns River on the north, Hunts Island Creek on the south, and estuarine marshlands on the east. Two lots divide the site. The joint owners of Seabrook own Lot 1, which encompasses approximately 109 ac (44 ha). The majority of the operating facility is located on this mostly developed lot. Site structures include the Unit 1 containment building, primary auxiliary building, fuel storage building, waste processing building, control and diesel generator building, turbine building, administration and service building, ocean intake and discharge structures, circulating water pumphouse, and service water pumphouse (NextEra 2010). NextEra originally planned to construct two identical units at the Seabrook site but halted construction on Unit 2 prior to completion and uses the remaining Unit 2 buildings primarily for storage.
NextEra owns Lot 2, which is approximately 780 ac (316 ha). Lot 2 is mainly an open tidal marsh area with fabricated linear drainage ditches and tidal creeks, and it is available habitat for wildlife resources (NextEra 2010). The site boundary is also the exclusion area. Figure D-1-3 provides a general layout of the Seabrook site.
The Seabrook cooling water comes from an intake structure located 60 ft (18.3 m) below mean lower low water in the Gulf of Maine (see Section D-1.2.1.1). The seafloor in this area is relatively flat, with bedrock covered by sand, algae, or sessile invertebrates (NAI 2010). The immediate vicinity surrounding the Seabrook plant is the Hampton-Seabrook Estuary. No intake or discharge structures are located in the estuary. From construction until 1994, Seabrook discharged to an onsite settling basin into the Browns River.
The Gulf of Maine and Hampton-Seabrook Estuary are complex water bodies with many individual species performing different roles in the system, and, often, species perform several ecological roles throughout their lifecycles. Major assemblages of organisms within the marine and estuarine communities include plankton, fish, benthic invertebrates, and algae.
Section 2.2.6 in the SEIS describes these assemblages and typical habitat types in the nearshore of the Gulf of Maine and within Hampton-Seabrook Estuary.
D-1.2.1.1 Cooling and Auxiliary Water Systems Seabrook uses a once-through cooling system that withdraws water from the Gulf of Maine and discharges to the Gulf of Maine through a system of tunnels that have been drilled through ocean bedrock. Unless otherwise cited, the NRC staff drew information about Seabrooks cooling and auxiliary water systems from the National Pollution Discharge Elimination System (NPDES) Permit (EPA 2002a) and the applicants Environmental Report (ER) (NextEra 2010).
3 Figure D-1-1. Location of Seabrook, 6-mi (10-km) region Source: (NextEra 2010) 4 Figure D-1-2. Location of Seabrook, 50-mi (80-km) region Source: (NextEra 2010)
5 Figure D-1-3. Seabrook site boundary and facility layout Source: (NextEra 2010)
Water is drawn from the Gulf of Maine through three concrete intake structures that are located at the end of an intake tunnel in approximately 60 ft (18 3 m) of water depth. Each intake shaft 6
extends up from the intake tunnel to above the bedrock, and a velocity cap sits on top (Figure D-1-4). NextEra implemented this structural design to reduce the intake velocity, thereby minimizing fish entrapment. In 1999, NextEra modified the intakes with additional vertical bars to help prevent seals from getting trapped (NMFS 2002). The NPDES permit limits the intake velocity to 1.0 feet per second (fps) (0.3 meters per second (m/s)) (EPA 2002a).
Figure D-1-4. Intake shafts and caps at Seabrook Source: (ARCADIS et al. 2008)
Water flows from the intake structures through a 17,000-ft (5,182-m) intake tunnel that was drilled through the ocean bedrock. The beginning of the intake tunnel is 7,000 ft (2,134 m) from the Hampton beach shoreline. The tunnel descends at a 0.5 percent grade from the bottom of the intake shaft, which is 160 ft (49 m) below the Gulf of Maine, to 240 ft (73 m) below mean sea level (MSL) at Seabrook (Figure D-1-5). Concrete lines the 19-ft (5.8-m) diameter tunnel.
7 Figure D-1-5. Profile of intake tunnel and shafts at Seabrook Source: (ARCADIS et al. 2008)
An intake transition structure, which includes three circulating water pumps that transport the water, is located beneath Seabrook (Figure D-1-6). Butterfly valves, 11-ft (3.4-m) in diameter, direct the water flow from the transition structure to the circulating water pumphouse. The water then passes through three traveling screens with a 3/8-inch (0.95-cm) square mesh (NextEra 2010a). The traveling screens remove fish, invertebrates, seaweed, and other debris before the water is pumped to the main condensers and the service water system. The ocean debris is disposed as waste; therefore, none is discharged to the Gulf of Maine. The water passes to the condensers to remove heat that is rejected by the turbine cycle and auxiliary system. During normal operations, the circulating water system provides a continuous flow of approximately 390,000 gallons per minute (gpm) (869 cubic feet per second (cfs) or 24.6 cubic meters (m3) per second (m3/s)) to the main condenser and 21,000 gpm (47 cfs or 1.3 m3/s) to the service water system.
Water that has passed through Seabrook discharges to the Gulf of Maine through a 16,500-ft (5,029-m) long discharge tunnel, which has the same diameter, lining, depth, and percent grade as the intake tunnel. The end of the discharge tunnel is 5,000 ft (1,524 m) from the Seabrook beach shoreline. Eleven 70-ft (21-m) deep concrete shafts about 100 ft (30 m) apart discharge the effluent. Each shaft terminates in a pair of nozzles that are pointed up at an angle of about 22.5 degrees (NAI 2001). The nozzles are located 6.5 to 10 ft (2 to 3 m) above the seafloor in depths of approximately 49 to 59 ft (15 to 18 m) of water (NAI 2001). To increase the discharge velocity and more quickly diffuse the heated effluent, a double-nozzle fixture tops each shaft.
The NPDES permit limits this discharge flow to 720 million gallons per day (mgd) (2.7 million m3/day), and the monthly mean temperature rise may not exceed 5° F (2.6 ° C) at the surface of the receiving water (EPA 2002a).
Barnacles, mussels, and other subtidal fouling organisms can attach to concrete structures and potentially limit water flow through the tunnels. To minimize biofouling within the intake and discharge tunnels, NextEra uses a combination of physical scrubbing and a chlorination system (NextEra 2010a). Divers physically scrub the intake structures biannually to remove biofouling organismssuch as barnacles, mussels, or other organismsthat attach to hard surfaces to grow. During outages, the inside of the intake structures are physically scrubbed up until the point that chlorine is injected into the tunnels, approximately 6 ft (1.8 m) into the intake shaft. In addition, NextEra inspects the discharge diffusers during outages. The circulating water pumphouse, pipes, and condensers are dewatered, inspected, and cleaned as needed 8
(Seabrook 2008). NextEra injects chlorine and other water treatment chemicals in accordance with NPDES permit limits (EPA 2002a).
Figure D-1-6. Circulating water pumphouse at Seabrook Source: (ARCADIS et al. 2008)
As described above, the Gulf of Maine provides water for both the circulating water system and the service water system. Water flows from the intake structures to the service water pumphouse, which is separated from the circulating water system portion of the building by a seismic reinforced concrete wall. In the event that the regular supply of cooling water from the service water pumphouse is unavailable, NextEra would use a standby mechanical draft evaporative cooling tower (service water tower) and 7-day makeup water reservoir. This makeup water reservoir is from the Gulf of Maine and stored in the service water tower. If this makeup reservoir is unavailable, or additional water is required, NextEra would access emergency makeup water from the domestic water supply system or from the Browns River via a portable pump (FPLE 2008).
Sections 2.1.1 through 2.1.5 of the SEIS provide additional information regarding the reactor and containment systems, other systems at Seabrook, and plant operations. Sections 2.1.7 and 2.2.5 provide additional information on Seabrooks surface water use and a description of the NDPES permit.
Essential Fish Habitat Species Near the Site and Potential Adverse Effects D-1.3.1 Essential Fish Habitat Species Identified for Analysis The waters and substrate necessary for spawning, breeding, feeding, or growth to maturity are considered EFH (16 U.S.C. 1802(10)). The portion of the Gulf of Maine and Hampton-Seabrook Estuary adjacent to Seabrook, and its intake and discharge structures, contains designated EFH for several fish species and life stages.
9 In its Guide to Essential Fish Habitat Designations in the Northeastern United States, NMFS (2011a) identifies EFH by 10-minute squares of latitude and longitude as well as by major estuary, bay, or river for estuarine waters outside of the 10-minute square grid. The waters near Seabrook are within the Gulf of Maine EFH Designation that extends from Salisbury, MA, north to Rye, NH and includes Hampton Harbor, Hampton beach, and Seabrook beach. The 23 species with designated EFH in this area appear in Table D-1-1.
Table D-1-1. Species of fish with designated EFH in the vicinity of Seabrook Species Eggs Larvae Juveniles Adults American plaice (Hippoglossoides platessoides) x x
Atlantic butterfish (Peprilus triacanthus) x x
x x
Atlantic cod (Gadus morhua) x x
x x
Atlantic halibut (Hippoglossus hippoglossus) x x
x x
Atlantic herring (Clupea harengus) x x
Atlantic mackerel (Scomber scombrus) x x
x x
Atlantic sea scallop (Placopecten magellanicus) x x
x x
Bluefin tuna (Thunnus thynnus) x Haddock (Melanogrammus aeglefinus) x Longfin inshore squid (Loligo pealei) x x
Monkfish/Goosefish (Lophius americanus) x x
x x
Northern shortfin squid (Illex illecebrosus) x x
Ocean pout (Macrozoarces americanus) x x
x x
Pollock (Pollachius virens) x Redfish (Sebastes fasciatus) x x
x Red hake (Urophycis chuss) x x
x x
Scup (Stenotomus chrysops) x x
Summer flounder (Paralicthys dentatus) x Atlantic Surf clam (Spisula solidissima) x x
Whiting/Silver hake (Merluccius bilinearis) x x
x x
Windowpane flounder (Scopthalmus aquosus) x x
Winter flounder (Pleuronectes americanus) x x
x x
Yellowtail flounder (Pleuronectes ferruginea) x x
Source: (NMFS 2011b)
Seabrook has monitored fish and shellfish eggs, larvae, juveniles, and adults since the mid-1970s. In addition, Seabrook regularly records annual estimates of entrainment and impingement. Table D-1-2 presents a summary of the occurrence of EFH species within Seabrooks monitoring, entrainment, and impingement studies.
The NRC staff compared monitoring, entrainment, and impingement data with each of the EFH species listed in Table D-1-2. Seabrook regularly observed most EFH species within 10 monitoring, entrainment, or impingement studies. However, Atlantic halibut, redfish, bluefin tuna, northern shortfin squid, and longfin inshore squid were rarely or occasionally identified during monitoring studies and were not entrained or impinged from 1990 to 2009. These fives species are analyzed in Section D-1.3.3.19 of this assessment. All other EFH species are analyzed in detail in Sections D-1.3.3.1 through D-1.3.3.18 of this assessment.
D-1.3.2 Potential Adverse Effects to Essential Fish Habitat The provisions of the regulations implementing the MSA define an adverse effect to EFH as the following (50 CFR 600.810):
Adverse effect means any impact that reduces quality and/or quantity of EFH.
Adverse effects may include direct or indirect physical, chemical, or biological alterations of the waters or substrate and loss of, or injury to, benthic organisms, prey species and their habitat, and other ecosystem components, if such modifications reduce the quality and/or quantity of EFH. Adverse effects to EFH may result from actions occurring within EFH or outside of EFH and may include site-specific or habitat-wide impacts, including individual, cumulative, or synergistic consequences of actions.
For purposes of conducting NEPA reviews, the NRC staff published the GEIS (NRC 1996),
which identifies 13 impacts to aquatic resources as either Category 1 or Category 2.
Category 1 issues are generic in that they are similar at all nuclear plants and have one impact level (SMALL, MODERATE, or LARGE) for all nuclear plants. Mitigation measures for Category 1 issues are not likely to be sufficiently beneficial to warrant implementation.
Category 2 issues vary from site to site and must be evaluated on a site-specific basis.
Table D-1-3 lists the aquatic resource issues as identified in the GEIS.
The GEIS classifies all impact levels for aquatic resources as SMALL except impingement, entrainment, and heat shock. NRC defines SMALL as having environmental effects are not detectable or are so minor that they will neither destabilize nor noticeably alter any important attribute of the resource (10 CFR 51, App. B, Table B-1). The NRC staff believes that stressors with SMALL levels of impact for the purposes of implementing NEPA would likely not adversely affect EFH. Therefore, this EFH Assessment will focus on the potential adverse effects of impingement, entrainment, and heat shock on EFH. Impingement occurs when aquatic organisms are pinned against intake screens or other parts of the cooling water system intake structure. Entrainment occurs when aquatic organisms (usually eggs, larvae, and other small organisms) are drawn into the cooling water system and are subjected the thermal, physical, and chemical stress. Heat shock is acute thermal stress caused by exposure to a sudden elevation of water temperature that adversely affects the metabolism and behavior of fish and other aquatic organisms. In addition to heat shock, increased water temperatures at the discharge can also reduce the available habitat for fish species if the discharged water is higher than the environmental preferences of a particular species. This issue will be discussed together with heat shock.
11 Table D-1-2. Relative commonness of EFH species in Seabrook monitoring, entrainment, and impingement studies Species Eggs Larvae Juveniles and Adults Plankton monitoring Entrainment studies Plankton monitoring Entrainment studies Trawl monitoring Gill net monitoring Seine monitoring Impingement studies American plaice Common(a)
Occasional Common Occasional(b)
Occasional Rare(c)
Atlantic butterfish Occasional Rare Occasional Rare Rare Occasional Rare Rare Atlantic cod (e)
Common Common Common Rare Common Occasional Rare Rare Atlantic halibut Rare Atlantic herring Common Occasional Occasional Abundant Occasional Common Atlantic mackerel Abundant(d)
Abundant Abundant Rare Rare Common Rare Rare Atlantic sea scallop Rare Atlantic surf clam Rare Bluefin tuna Haddock (e)
Common Rare Occasional Rare Common Rare Rare Longfin inshore squid Monkfish/Goosefish Rare Rare Occasional Rare Occasional Rare Rare Northern shortfin squid Ocean pout Occasional Rare Common Rare Rare Pollock Common Rare Common Rare Common Common Occasional Common Redfish (e)
Occasional Red hake (e)
Common Common Common Occasional Abundant Occasional Common Common Scup Rare Occasional Rare Rare Summer flounder Rare Rare Rare Rare Whiting/Silver hake Common Common Common Occasional Common Common Rare Rare 12 Species Eggs Larvae Juveniles and Adults Plankton monitoring Entrainment studies Plankton monitoring Entrainment studies Trawl monitoring Gill net monitoring Seine monitoring Impingement studies Windowpane flounder Common Occasional Common Rare Common Rare Occasional Common Winter flounder Rare Common Occasional Common Occasional Common Common Yellowtail flounder (e)
Abundant Occasional Common Rare Abundant Rare Rare Common (a) Common: Occurring in >10% of samples but <10% of total catch; 5-10% of entrainment samples averaged over all years (b) Occasional: Occurring in <10%-1% of samples; 1-5% of entrainment samples averaged over all years (c) Rare: Occurring in <1% of samples; <1% of entrainment samples averaged over all years (d)Abundant: >10% of total catch or entrainment over all years (e) During monitoring surveys, NAI (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. In such cases, the estimate for the entire group of species appears in the table above. Groups of species include Atlantic cod/haddock/witch flounder, cunner/yellowtail founder, red hake/white hake/spotted hake, and golden redfish/deepwater redfish/and Acadian redfish. For egg entrainment estimates of these groups of species, NextEra (2010b) estimated single species entrainment rates by applying the ratio of larval species to the egg species groups Blank cells indicate the NAI (2010) did not identify the species within monitoring or entrainment studies.
Sources: (NAI 2010; NextEra 2010a)
13 Table D-1-3. Aquatic resource issues identified in the GEIS Issues Category Impact level For all plants Accumulation of contaminants in sediments or biota 1
SMALL Entrainment of phytoplankton & zooplankton 1
SMALL Cold shock 1
SMALL Thermal plume barrier to migrating fish 1
SMALL Distribution of aquatic organisms 1
SMALL Premature emergence of aquatic insects 1
SMALL Gas supersaturation (gas bubble disease) 1 SMALL Low dissolved oxygen in the discharge 1
SMALL Losses from parasitism, predation, & disease among organisms exposed to sublethal stresses 1
SMALL Stimulation of nuisance organisms 1
SMALL For plants with once-through heat-dissipation systems Impingement of fish & shellfish 2
SMALL, MODERATE, or LARGE Entrainment of fish & shellfish in early life stages 2
SMALL, MODERATE, or LARGE Heat shock 2
SMALL, MODERATE, or LARGE Source: (NRC 1996)
In addition to impingement, entrainment, and heat shock (or thermal impacts), the NRC staff will assess the impacts to EFH species food (forage species) and loss of habitat-forming species (such as sessile invertebrates and algae). Information on these areas that is relevant to all EFH species is in Section D-1.3.2.1. In addition, Section D-1.3.2.2 presents NextEra monitoring data of selected groups prior to and during operations at sampling sites near the intake and discharge structures (nearfield sampling sites) and at sampling sites 3 to 4 mi (5 to 8 km) away (farfield sampling sites). Monitoring data may indicate whether the combined impacts (or cumulative impacts) from Seabrook operation has resulted in the decline of forage species, habitat-forming species, or EFH species due to a decline in habitat quantity or quality. The NRC staffs conclusions and information specific to each EFH species is in Sections D-1.3.3.1 through D-1.3.3.19. Section D-1.4 provides an analysis of cumulative impacts to EFH species or their habitat resulting from the past, present, and reasonably foreseeable future projects in the vicinity of Seabrook.
D-1.3.2.1 Information Related to Potential Adverse Impact on All Essential Fish Habitat Species The section below provides information regarding potential adverse impacts to EFH that is relevant for the assessment of all 23 EFH species that may occur within the vicinity of Seabrook.
Entrainment and Impingement. Entrainment and impingement study results illustrate one type of operational impact on each species habitat. Because the intake water is EFH, the ratio of specimens from a species impinged or entrained at Seabrook to the total number of impinged or 14 entrained organisms provides some indication of how great the impact from the cooling system will be on the corresponding EFH. The NRC staff obtained data on fish entrainment and impingement from Seabrooks Annual Biological Monitoring Reports, which summarize entrainment data from 1990 to 2009 and impingement data from 1994 to 2009 (NAI 2010).
NextEra conducted entrainment studies four times per month (NAI 2010). For fish eggs and larvae prior to 1998, NextEra collected three replicate samples using 0.02-in. (0.505-mm) mesh nets. Since 1998, NextEra collected samples using 0.01-in. (0.333-mm) mesh sizes throughout a 24-hour period. NextEra estimated entrainment rates by multiplying the density of entrained eggs or larvae within a sample by the volume of water pumped through the plant within the sample period (FPLE 2008; NAI 2010). Entrainment rates for commonly entrained species, EFH species, and common forage species are presented in Table D-1-4 for egg entrainment and Table D-1-5 for larvae entrainment.
NextEra conducted impingement monitoring once or twice per week by cleaning traveling screens and sorting fish and other debris (NAI 2010). Prior to 1998, NextEra did not sort some collections, and impingement estimates are based on the volume of debris (NAI 2010).
Beginning in 1998, Seabrook staff sorted all collections and identified all impinged fish by species. Beginning in April 2002, NextEra collected two standardized 24-hour samples per week and multiplied by seven to estimate weekly impingement. Table D-1-6 shows impingement rates for commonly impinged species, EFH species, and common forage species.
NAI (2010) reported impingement estimates from 1994 to 2009. Prior to October 1994, NextEra determined that some small, impinged fish had been overlooked during separation procedures.
NextEra enhanced the Impingement Monitoring Program in the end of 1994 to remedy this issue (NextEra 2010a).
NextEra also conducted entrainment studies for bivalve larvae (NAI 2010). In these studies, NextEra collected three replicates per sampling date using a 0.003-in. (0.076-mm) mesh.
Table D-1-7 describes entrainment rates for bivalve larvae.
Thermal Impacts. Heat shock can injure or kill fish. In addition, aquatic species, including EFH species or prey of EFH species, may largely avoid effluents due to high velocities, elevated temperatures, and turbulence. Seabrooks discharge to the Gulf of Maine is permitted under its NPDES permit (EPA 2002a), issued April 1, 2002. The permit allows discharge of 720 mgd (2.7 million m3/day) on both an average monthly and maximum daily basis. The permit also limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. An EPA online database indicated that Seabrook has had no Clean Water Act (CWA) formal enforcement actions or violations related to discharge temperature in the last 5 years (EPA 2010). EPAs Regional Administrator determined that NextEras NPDES permit provides a Section 316(a) variance that satisfies thermal requirements and that will ensure the protection and propagation of a balanced indigenous community of fish, shellfish, and wildlife in and on Hampton Harbor and the near shore Atlantic Ocean (EPA 2002a).
15 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species Taxon(a) 1990(b) 1991(c) 1992(d) 1993(d) 1994(e) 1995(f) 1996 1997 1998 1999 2000 2001 American plaice 2.6 21.0 52.3 19.5 0.4 14.8 78.2 15.6 13.7 24.8 16.7 26.8 Atlantic cod 20.8 74.5 32.0 50.3 0.2 37.0 22.4 6.4 84.3 48.6 30.7 32.1 Atlantic mackerel 518.8 673.1 456.3 112.9 0.0 74.5 305.1 23.1 39.3 44.6 266.9 330.4 Butterfish 0
0 0
0 0
0 0.1 0
0
<0.1 0
0 Cunner 489.3 147.2 0
58.4 0
18.2 93.9 221.5 63.6 220.3 1,206.7 239.6 Fourbeard rockling 108.8 39.5 51.4 32.7 0.2 27.5 38.7 46.6 33.9 27.4 63.6 47.1 Haddock 0.0 0.0 7.4 0.0
<0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hake 50.1 2.6 0
1.6 0.6 29.3 213.2 71.8 7.5 6.2 295.2 4.4 Monkfish/Goosefish 0
0 0
0 0
0 0
0 0.9 0
0.9 0
Pollock 0
1.0 0.4 0.2 0.1 0.4 0.4 0.2 2.9 0.2
<0.1 0.3 Whiting/Silver hake 11.4 0.0 0.1 0.4 0.4 22.5 73.6 271.1 18.6 139.9 90.4 48.9 Windowpane 36.4 19.9 22.5 29.1 0.1 17.4 44.2 28.5 17.9 43.2 95.1 33.4 Winter flounder 0
0 0
0 0
0 0
0 0
0 0.3 0
Yellowtail flounder 1.2 569.2 198.6 0
0 0.6 17.9 0.5 1.9 33.8 2.8 8.4 Total (All Species) 1,247.7 1,551.3 822.6 315.6 4.8 255.9 926.4 692.7 286.7 593.9 2,104.4 775.1 (a) Normandeau Associates, Inc. (NAI) (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. Groups of species include Atlantic cod/haddock, cunner/yellowtail founder, and hake/fourbeard rockling. NextEra (2010a) estimated entrainment rates for each species by applying the ratio of larval species to the egg species groups.
(b) NextEra sampled three months, August-October.
(c) NextEra sampled eight months, January-July, December.
(d) NextEra sampled eight months, January-August.
(e) NextEra sampled seven months, January-March, September-December.
(f) NextEra sampled 12 months per year.
Source: (NAI 2010; NextEra 2010a) 16 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species (cont.)
Taxon 2002 2003 2004 2005 2006 2007 2008 2009 Average Percentage American plaice 22.4 37.8 33.4 11.7 5.3 35.8 48.0 36.7 25.9 2.9%
Atlantic cod 77.8 15.5 9.3 16.0 15.7 15.1 48.0 15.4 32.6 3.6%
Atlantic mackerel 56.7 26.4 70.1 37.7 475.6 153.6 82.4 83.5 191.5 21.3%
Butterfish 0
0 0
0.4 0
0 0
0
<0.1
<0.1%
Cunner 1,395.7 143.9 518.1 251.2 489.4 295.0 444.5 1,451.2 387.4 43.0%
Fourbeard rockling 61.4 44.1 38.2 68.8 36.6 78.2 61.7 123.8 51.5 5.7%
Haddock 0
0 0
0.7 0
0 0
0 0.4
<0.1%
Hake 79.7 5.2 5.7 2.8 8.1 15.6 21.7 92.1 45.7 5.1%
Monkfish/Goosefish 0
0 0.1 0.1 0.1 0
0 0
0.1
<0.1%
Pollock 0.6 1.0 0.9 1.0 4.1 8.5 5.0 0.2 1.4 0.2%
Whiting/Silver hake 341.4 235.6 19.8 30.7 9.4 60.8 50.9 196.2 81.1 9.0%
Windowpane 39.1 15.5 18.2 26.2 24.7 34.7 25.9 61.8 31.7 3.5%
Winter flounder 0
0.3 0
0 0
0.2 1.1
<0.1
<0.1
<0.1%
Yellowtail flounder 3.9 0
0.1 5.0 1.1 7.8 0
4.1 42.8 4.8%
Total (all species) 2,086.8 529.4 723.7 454.4 1,075.4 714.7 790.6 2,072.5 901.2 100%
(a) Normandeau Associates, Inc. (NAI) (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. Groups of species include Atlantic cod/haddock, cunner/yellowtail founder, and hake/fourbeard rockling. NextEra (2010a) estimated entrainment rates for each species by applying the ratio of larval species to the egg species groups.
(b) NextEra sampled 3 months, August-October.
(c) NextEra sampled 8 months, January-July, December.
(d) NextEra sampled 8 months, January-August.
(e) NextEra sampled 7 months, January-March, September-December.
(f) In 1995-2009, NextEra sampled 12 months per year.
Source: (NAI 2010; NextEra 2010a)
17 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species Taxon 1990(a) 1991(b) 1992(c) 1993(d) 1994(e) 1995 1996 1997 1998 1999 2000 2001 American plaice 0.4 1.0 0.8 0.7 0
7.9 8.1 7.0 2.9 4.9 1.6 8.7 American sand lance 0
37.3 18.1 12.0 8.3 9.5 14.0 10.1 10.7 7.8 1.0 5.3 Atlantic butterfish 0
0 0
0 0
0 0
0.1 0
0 0
0 Atlantic cod 0.7 1.5 0.4 0.1 0
2.3 0.3 0.7 2.2 1.0 0.4 2.5 Atlantic herring 0.7 0.5 4.9 9.6 0.1 11.2 4.3 2.1 9.5 8.6 0.2 15.2 Atlantic mackerel 0.2 4.7 0
0 0
0 0.1 0.4 0
0.1 0.3 0.1 Cunner 42.7
<0.1 0
4.7 0.1 4.4 9.2 203.8 8.4 4.7 111.0 13.6 Fourbeard rockling 37.9 0.5 0.1 2.2 0.0 3.9 11.7 22.4 13.1 21.0 8.2 19.6 Grubby 0
22.4 18.9 13.8 4.9 17.4 18.6 12.8 17.3 6.4 2.2 12.4 Haddock 0
0 0.1 0
0 0
0 0
0 0
0 0
Hake 4.8 0
0 0.1 0
0.7 12.3 1.7
<0.1 0.1 29.8 0
Monkfish/Goosefish 0.1 0
0 0
0 0
0 0
0 0
2 0
Ocean pout 0
0 0
0 0
0 0
0 0
0 0
0 Pollock 0.2 0
0.1 0
0 0
0 0
<0.1 0
0 0
Summer flounder 0
0 0
0 0
0 0
0
<0.1 0
0 0
Whiting/Silver hake 7.7 0
0 0.1 0
0.9 16.9 69.0 0.2 0.4 33.2 0.6 Windowpane 3.8
<0.1 0.1 0.1
<0.1 2.0 2.0 5.6 1.4 3.7 2.3 1.3 Winter flounder 3.2 9.0 6.2 2.9 0
8.0 10.3 2.2 4.7 7.4 14.3 14.3 Yellowtail flounder 0.1 0.3 0.1 0
0 0.1 1.6 0.5 0.3 0.8 0.3 0.5 Total (all species) 121.5 153.8 133.1 126.1 31.2 145.3 215.7 373.4 134.1 171.8 261.2 124.3 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) Unless otherwise denoted, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra did not conduct bivalve larvae entrainment studies.
(f) NextEra sampled the fourth week in April through the fourth week in October.
(g) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010) 18 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species (cont.)
Taxon 2002 2003 2004 2005(f) 2006(g) 2007 2008 2009 Average Percentage American plaice 11.3 9.1 2.6 1.4 0.6 2.6 3.5 11.5 4.3 1.6%
American sand lance 10.5 27.1 107.1 28.3 14.1 36.6 71.2 128.6 27.9 10.3%
Atlantic butterfish 0
0 0
0 0
0 0
0
<0.1
<0.1%
Atlantic cod 34.6 2.5 0.5 1.6 0.3 1.6 1.4 1.4 3.0 1.0%
Atlantic herring 11.7 15.3 8.8 9.7 12.8 11.5 28.2 27.7 9.6 3.6%
Atlantic mackerel 0.4 0
20.2 0.1 0.5 0
<0.1 25.7 2.6 1.0%
Cunner 391.1 22.5 451.2 2.5 8.8 97.7 86.2 105.7 78.4 29.1%
Fourbeard rockling 176.4 19.3 61.4 2.0 4.9 16.4 11.9 20.3 22.7 8.4%
Grubby 6.6 27.5 51.8 7.8 9.3 15.4 8.3 31.6 15.3 5.7%
Haddock 0
0 0
0.1 0
0 0
0
<0.1
<0.1%
Hake 0.3 0.1 1.0 0
0.2 0
0.2 4.0 2.8 1.0%
Monkfish/Goosefish 0
0 0.1 0
0 0
0
<0.1 0.1
<0.1%
Ocean pout 0
<0.1 0
0 0
0 0
0
<0.1
<0.1%
Pollock
<0.1 0.6 0.1 0.1 0.8 0.8 0.3 0.3 0.2 0.1%
Summer flounder 0
<0.1 0
0 0
<0.1 0
0
<0.1
<0.1%
Whiting/Silver hake 5.9 0.5 0.2 0
0.1 0
17.9 8.2 8.1 3.0%
Windowpane 6.5 0.5 0.4 0.5 0.5 2.6 11.4 1.9 2.3 0.9%
Winter flounder 4.5 20.0 34.8 4.9 7.2 15.8 0.1 15.2 9.2 3.4%
Yellowtail flounder 0.9 0
0.1
<0.1
<0.1 2.7 0
0.3 0.4 0.2%
Total (all species) 724.4 268.5 958.5 167.0 123.2 297.2 333.7 523.2 269.4 100%
(a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) Unless otherwise denoted, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra did not conduct bivalve larvae entrainment studies.
(f) NextEra sampled the fourth week in April through the fourth week in October.
(g) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010)
19 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species Species 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Alewife 0
8 1,753 2,797 14 16 4
35 1
9 212 87 American plaice 0
0 0
0 0
2 0
0 0
0 0
3 American sand lance 1,215 1,324 823 182 708 234 423 114 245 3,396 665 1,029 Atlantic butterfish 3
14 3
223 9
5 1
28 1,170 4
35 54 Atlantic herring 0
0 485 350 582 20 5
11 159 198 118 93 Atlantic mackerel 0
0 1
0 0
0 0
1 0
0 4
4 Atlantic menhaden 0
7 97 0
1 957 142 19 1,022 7
361 7,226 Atlantic silverside 5,348 1,621 1,119 210 834 1,335 31 282 1,410 20,507 877 2,717 Atlantic cod 58 119 94 69 38 66 29 30 199 3,091 467 454 Cunner 32 342 1,121 233 309 255 324 341 291 554 625 893 Grubby 2,678 2,415 1,457 430 3,269 3,953 1,174 549 1,089 2,523 676 531 Haddock 0
1 397 0
1 3
2 1
0 0
0 7
Hakes 2,822 2,188 156 122 4
68 113 523 1,813 166 35 11 Monkfish/Goosefish 3
13 0
0 7
17 15 59 18 10 0
8 Northern pipefish 188 579 1,200 243 268 748 370 714 936 2,716 1,413 1,724 Ocean pout 0
6 1
0 7
3 2
21 1
13 3
3 Pollock 1,681 899 1,835 379 536 11,392 534 405 719 499 80 218 Rainbow smelt 545 213 4,489 365 535 100 8
65 323 3,531 2,085 3,314 Red hake 1
16 1,478 371 903 1,120 112 155 52 271 892 821 Rock gunnel 494 1,298 1,122 459 2,929 2,308 1,514 2,251 2,066 6,274 4,137 1,752 Sea raven 78 125 1,015 223 137 132 206 271 166 217 129 221 Scup 0
14 9
0 3
1 0
3 11 11 0
21 Shorthorn sculpin 14 156 282 123 190 296 923 621 642 7,450 876 2,214 Snailfishes 180 165 1,013 351 856 2,356 690 334 616 451 185 442 Summer flounder 3
0 0
0 0
0 0
0 0
0 0
0 Threespine stickleback 67 155 320 174 773 506 10 280 34 1,549 130 307 Whiting/Silver hake 0
49 58 108 13 100 41 5
1,177 22 212 306 Windowpane 980 943 1,164 1,688 772 692 251 161 2,242 4,749 936 2,034 Winter flounder 1,435 1,171 3,231 468 1,143 3,642 102 777 897 10,491 783 1,875 Yellowtail flounder 0
1,149 4
23 11 97 0
8 5
0 0
0 Total (All taxa) 19,212 15,940 26,825 10,648 15,198 31,241 7,281 8,577 18,413 71,946 16,696 29,368 Source: (NAI 2010) 20 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species (cont.)
Species 2006 2007 2008 2009 Total Percent of Total Annual Average Alewife 255 244 41 0
5,476 1.6%
342 American plaice 0
0 7
0 12 0.0%
0.75 American sand lance 213 2,073 758 796 14,198 4.3%
887 Atlantic Butterfish 44 199 7
29 1,828 0.5%
114 Atlantic herring 189 260 27 490 2,987 0.9%
187 Atlantic mackerel 0
0 0
0 10 0.003%
1 Atlantic menhaden 94 160 67 39 10,199 3.1%
637 Atlantic silverside 788 639 247 525 38,490 11.5%
2,406 Atlantic cod 113 178 73 147 5,225 1.6%
327 Cunner 687 922 731 837 8,497 2.5%
531 Grubby 235 869 3,919 521 26,288 7.9%
1,643 Haddock 3
25 0
15 455 0.1%
28 Hakes 6
1,184 3,216 1,427 13,854 4.1%
866 Monkfish/Goosefish 0
11 0
0 161 0.0%
10 Northern pipefish 1,288 2,374 1,082 698 16,541 5.0%
1,034 Ocean pout 6
3 0
0 69 0.0%
4 Pollock 73 340 123 657 20,370 6.1%
1,273 Rainbow smelt 878 572 421 43 17,487 5.2%
1,093 Red hake 546 1,389 14 0
8,141 2.4%
509 Rock gunnel 3,782 3,174 937 701 35,198 10.5%
2,200 Sea raven 138 164 138 79 3,439 1.0%
215 Scup 4
8 13 15 113 0.0%
7 Shorthorn sculpin 1,258 465 1,515 266 17,291 5.2%
1,081 Snailfishes 330 76 233 85 8,363 2.5%
523 Summer flounder 4
0 0
0 7
0.0%
0 Threespine stickleback 139 193 80 118 4,835 1.4%
302 Whiting/Silver hake 31 21 204 325 2,672 0.8%
167 Windowpane 572 1,502 1,640 427 20,753 6.2%
1,297 Winter flounder 767 3,949 1,920 655 33,306 10.0%
2,082 Yellowtail flounder 10 11 3
0 1,321 0.4%
83 Total (All taxa) 12,955 22,472 17,935 9,304 334,011 100.0%
20,876 Source: (NAI 2010)
21 Table D-1-7. Number of bivalve larvae entrained (x 109)
Taxon 1990(a) 1991(b) 1992(c) 1993(d) 1995 1996 1997 1998 1999 2000 2001 2002 2003 Prickly jingle 1,691 250.8 6.9 3,923 8,906 23,522 2,883 3,827 36,495 7542 4,129 8,204 3,218.1 Bivalvia mussels 181.7 38.1 14.5 334.5 797.1 671.4 71.1 64.5 651.3 228.6 483 194.2 73.7 Rock borer 876.6 421.3 189.8 2,406 2,598 4,670 923.7 609.7 4,417 1,921 1,575 567.3 1,203.9 Northern horsemussel 909.7 160.2 0.3 1,284 546.4 5,145 614.7 241.7 2,376 2,521 251.6 776.4 240.8 Soft shell clam 8.1 0.6 0.2 22.5 4.3 33.2 53.7 11.4 45.7 23.9 26.4 60.2 5.1 Truncate softshell clam 249.2 6.5 1.1 2.1 27.6 123 0.8 8.3 66 34.9 26.3 1.9 13.8 Blue mussels 3,991 1,688 121.9 10,051 13,231 17,932 1745 1,493 22,374 10,255 9621 3,318 2,199 Atlantic Sea scallop 0.7 0.7 0.1 16.9 6.2 31 0.8 0.8 11.5 9.9 8.5 0.8 0
Solenidae clams 61.1 0
75.7 102.5 1092 241.9 49.5 20.9 773.2 150.4 922.9 150.8 85.5 Atlantic Surf clam 69 4.4 0
48.5 112.5 171.1 22.5 14.8 175.5 33.6 50.8 44.2 3.1 Shipworm 0.01 15.9 0
0 4.8 7.4 1.7 0.8 29.9 1.5 0.3 2.3 0.1 Total (all taxon) 8,039 2,586 410 18,190 27,327 52,547 6,366 6,293 67,415 22,721 17,095 13,320 7,043 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) In 1994, NextEra did not conduct bivalve larvae entrainment studies. Unless otherwise denoted for all other years,, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra sampled the fourth week in April through the fourth week in October.
(f) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010) 22 Table D-1-7. Number of bivalve larvae entrained (x 109) (cont.)
Taxon 2004 2005(e) 2006(f) 2007 2008 2009 Average Prickly jingle 2,595 1,217 3,966 3,950 18,452 27,733 8,553.2 Bivalvia mussles 89.6 40.4 73.9 46.2 411.8 74.3 238.94 Rock borer 1,024 352.9 604.6 650.7 3,137 2,548 1,615.5 Northern horsemussel 843.2 292.9 715.1 172.5 2,270 1421 1,093.8 Soft shell clam 15.1 9.2 11.1 4.7 45.8 31.8 21.737 Truncate softshell clam 5.2 2.3 0.6 3
6.4 4.8 30.726 Blue mussels 1,526 921.5 1,351 834.4 2,700 3,974 5,754 Atlantic Sea scallop 0.7 0.1 0
0.1 0.3 1.2 4.7526 Solenidae clams 113.4 57.9 65.2 156.1 85.1 162.4 229.83 Atlantic Surf clam 10 14.5 20 2.8 100.7 31.5 48.921 Shipworm 0.6 0.3 0.8 0
1.8 2.3 3.7111 Total (all taxon) 6,223 2,909 6,809 5,820 27,211 35,983 17,595 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) In 1994, NextEra did not conduct bivalve larvae entrainment studies. In all other years, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra sampled the fourth week in April through the fourth week in October.
(f) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010)
23 Padmanabhan and Hecker (1991) conducted a thermal plume modeling and field verification study. This study estimated a temperature rise of approximately 36 to 39° F (20 to 22° C) at the diffusers (Padmanabhan and Hecker 1991). Field and modeling data indicated that the water rose relatively straight to the surface and spread out within 10 to 16 ft (3 to 5 m) of the ocean surface. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Padmanabhan and Hecker (1991) did not observe significant increases in surface temperature 1,640 ft (500 m) to the northwest of the discharge structure.
NextEra has conducted monitoring of water temperature at bottom and surface waters near the discharge structure during operations (NAI 2001, 2010). NextEra monitored bottom water temperature at a site 656 ft (200 m) from the discharge and at a site 3 to 4 nautical mi (5 to 8 km) from the discharge from 1989 to 1999 (NAI 2001). NextEra observed a significant difference in the monthly mean bottom water temperature between the two sites. The mean difference was less than 0.9° F (0.5° C) (NAI 2001). As required by Seabrooks NPDES permit, NextEra conducts continuous surface water monitoring. The mean difference in temperature between a sampling station within 328 ft (100 m) of the discharge and a sampling station 1.5 mi (2.5 km) to the north has not exceed 5° F (2.8° C) since operations began, which is the limit identified in the NPDES permit (EPA 2002a; NAI 2001, 2010). For the majority of months between August 1990 and December 2009, the monthly mean increase in the surface water temperature was less than 3.6° F (2.0° C).
Based on Seabrooks water quality monitoring and Padmanabhan and Heckers (1991) study, the habitat most likely affected by the thermal plume would be the upper water column (10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge (less than 328 ft (100 m)). Fish may avoid this area, but the thermal plume would not likely block fish movement because fish could swim around the thermal plume. Pelagic fish species that may avoid this area are discussed, as appropriate, in the species analysis below (Sections D-1.3.3.1 through D-1.3.3.19). Benthic species, or species that primarily reside at the seafloor, may also avoid the immediate area surrounding the discharge structures due to higher temperature, velocities, and turbulence. This area should be considerably smaller than the area of increased temperature at the surface.
To examine the potential thermal impacts from plant operations on sessile species (and as an indicator of thermal impacts to other biological groups), NAI (2010) compared the abundance of cold water and warm water macroalgae species prior to and during operations at sites near the discharge structure (the nearfield site) and at sites approximately 3 to 4 nautical mi (5 to 8 km) from the intake and discharge structures (the farfield site). Benthic perennial algae are sensitive to changes in water temperature because they are immobile and live more than 2 years. Prior to operations, NAI (2010) collected six uncommon species not collected during operations, including the brown macroalgae Petalonia fascia, which is associated with cold-water habitat.
During operations, NAI (2010) collected some typically warm-water taxa for the first time (e.g., the red macroalgae Neosiphonia harveyi), collected other warm-water taxa less frequently, and collected some cold-water taxa more frequently. NAI (2010) observed 10 species that only occurred during operations, and NAI (2010) reported that these species were within their geographic ranges. NAI (2010) concluded that the changes in community composition among cold and warm water species were relatively small, although NAI (2010) did not report the results of any statistical tests to examine the significance in such changes.
The NRC staff concluded in the SEIS that thermal impacts from Seabrook operations were SMALL, and operations have not noticeably altered aquatic communities near Seabrook. This conclusion was based on the findings that the thermal plume would not block fish passage and 24 is within the limits of Seabrooks NPDES permit and that there were no clear patterns of emergent warm-water species or changes in the abundance of cold-water species.
Loss of Forage Species. Prey for the 23 EFH species includes phytoplankton, zooplankton (including fish and invertebrate eggs and larvae), juvenile and adult fish, and juvenile and adult invertebrates. Seabrook operations can adversely affect plankton prey if they are entrained in the cooling system or the thermal discharge significantly decreases the quality of the pelagic water habitat. Juvenile and adult fish prey could be affected by Seabrook operations if they are impinged in the cooling water system, if they avoid the area near the discharge because of the heated thermal effluent, or if bottom habitat (e.g., mussel beds or kelp forests) are adversely affected by Seabrook operations. Invertebrate prey could be affected by Seabrook operations if any of the following occurs:
They are entrained in the Seabrook cooling system.
They are mobile and impinged in the Seabrook cooling system.
They are mobile and avoid the area near the discharge structures due to the discharge of heated thermal effluent.
They are sessile, and growth is limited near the discharge structures due to the heated thermal effluent.
Loss of Habitat-Forming Species. In the Gulf of Maine, and the area in the vicinity of Seabrooks intake and discharge structures, rocky subtidal habitats are among the most productive habitats (Mann 1973; Ojeda and
Dearborn 1989). Algae,
mussels, oysters, and other sessile invertebrates attach to the bedrock on the seafloor and form the basis of a complex, multi-dimensional habitat for other fish and invertebrates to use for feeding and hiding from predators (Thompson 2010; Witman and Dayton 2001). Spawning fish, such as herring, shield eggs from currents and predators within rock crevices or sessile organisms attached to the bedrock (Thompson 2010). In soft sediment habitats, shellfish beds form the main biogenic habitats.
Kelp seaweeds, brown seaweeds with long blades, attach to hard substrates and can form the basis of undersea forests, commonly referred to as kelp beds. The long blades of kelpsuch as A. clathratum, L. digitata, and sea beltprovide the canopy layer of the undersea forest, while shorter foliose and filamentous algae, such as Irish moss, grow in between or at the bottom of kelp similar to the understory layer in a terrestrial forest (NAI 2010; Thompson 2010).
The multiple layers of seaweeds provide additional habitat complexity for other fish and invertebrates to find refuge from predators and harsh environmental conditions, such as strong currents or ultraviolet light (Thompson 2010). Seabrooks heated effluent may affect growth of algae and sessile invertebrates. These groups may be particularly sensitive to changes in water quality because they are sessile and cannot move to avoid the area, sufficient light must reach the algae for the plant to photosynthesize, and particulars in the water can clog the feeding structures of sessile invertebrates that filter seawater for food.
D-1.3.2.2 Combined Impacts (Monitoring Data)
This section presents NextEra monitoring data of selected groups prior to and during operations at sampling sites near the intake and discharge structures (nearfield sampling sites) and at sampling sites 3 to 4 mi (5 to 8 km) away (farfield sampling sites) (Figure D-1-7). Monitoring data may indicate if the combined impacts (or cumulative impacts) from Seabrook operation have resulted in the decline of a species or biological group due to a decline in habitat quantity or quality.
25 Figure D-1-7. Sampling Stations for Seabrook Station aquatic monitoring NAI (2010) used a before-after control-impact (BACI) design to test for potential impacts from operation of Seabrook. This monitoring design was used to test for the statistical significance of differences in community structure, species abundance, or species diversity between the pre-operational and operational period at the nearfield and farfield sites. Statistically significant 26 differences could result from entrainment, impingement, thermal impacts, loss of forage species, loss of habitat-forming species, or any combination of these effects of Seabrook operations.
Working with NAI and Public Service of New Hampshire staff, NextEra selected farfield sampling sites that would likely be outside the influence of Seabrook operations (NextEra 2010a). The farfield sampling stations were between 3 and 4 nautical mi (5 and 8 km) north of the intake and discharge structures. NextEra selected a northern farfield location because the primary currents run north to south. NextEra selected specific farfield sampling sites based on similarities with the nearfield sampling sites regarding depth, substrate type, algal composition, wave energy, and other relevant factors (NextEra 2010a).
Sections 2.2.6.3 and 4.5.5 of the SEIS describe the sampling methods, statistical methods, and monitoring results. Below is a brief summary of the monitoring results for phytoplankton, zooplankton, fish, invertebrates, and macroalgae.
Phytoplankton. NAI (1998) found no significant differences in phytoplankton abundance or chlorophyll a concentrations between the nearfield and farfield sites or between before and during plant operation. NAI (1998) observed minimal changes in species composition prior to and during operations. These results suggest that Seabrook operations have not adversely affected phytoplankton abundance near Seabrook.
Zooplankton. NAI (2010) did not find a significant difference in the density of holoplankton or meroplankton taxa prior to and during operations or between the nearfield and farfield sampling sites. The average density of all hyperbenthos species at the nearfield site was generally an order of magnitude larger than the abundances found at the farfield site both prior to and during operations (NAI 2010).
When examining total bivalve larvae density, NAI (2010) did not find a significant difference between sampling sites prior to and during operations. For fish eggs and larvae, NAI (2010) observed no significant difference between sampling sites, but the study reported a significant difference prior to and during operations in the density of fish eggs and larval species (Table D-1-8).
Table D-1-8. Mean density (No./1,000m3) and upper and lower 95% confidence limits (CL) of the most common fish eggs and larvae from 1982-2009 monitoring data at Seabrook Taxon Group 1(a)
Group 2 (a)
Lower 95%
CL Mean Upper 95%
CL Lower 95%
CL Mean Upper 95%
CL Eggs(b)
Atlantic mackerel 650 1,009 1,369 1,344 1,941 2,538 Cunner/Yellowtail flounder 2,764 5,003 7,243 6,577 7,239 8,081 Hakes 235 1,226 2,217 332 488 643 Hake/Fourbeard rockling 45 215 386 503 626 749 Atlantic cod/haddock 79 153 226 63 92 120 Windowpane 73 147 221 160 232 304 Fourbeard rockling 168 248 328 34 49 65 Silver hake 45 77 109 149 322 494 Larvae(c)
Cunner 143 425 707 828 1,386 1,945
27 Taxon Group 1(a)
Group 2 (a)
Lower 95%
CL Mean Upper 95%
CL Lower 95%
CL Mean Upper 95%
CL American sand lance 57 182 307 160 234 308 Atlantic mackerel 28 179 330 65 121 176 Fourbeard rockling 40 68 96 56 78 99 Atlantic herring 37 68 99 23 29 35 Rock gunnel 14 31 49 32 42 52 Winter flounder 18 44 70 8
11 14 Silver hake 14 23 32 35 67 100 Radiated shanny 15 26 36 3
27 50 Witch flounder 9
18 28 3
5 6
(a) NAI (2010) determined groups using a cluster analysis (numerical classification) and non-metric multi-dimensional scaling (MDS) of the annual means (log (x+1)) of each taxon at each station.
(b) Egg Group 1 years = 1983, 1984, 1986, 1987; Group 2 years = 1988-2008 (c) Larvae Group 2 years = 1982-1984, 1986-1989; Group 2 years = 1989-1991, 1993-2009 Source: (NAI 2010)
Because changes in community structure occurred at nearfield and farfield sampling sites, these results suggest that Seabrook operations have not adversely affected zooplankton near Seabrook.
Juvenile and Adult Fish. NextEra monitored the abundance of juvenile and adult fish prior to and during operations at nearfield and farfield sites using benthic trawls (Table D-1-9), gill nets (Table D-1-10), and seine pulls in the Hampton-Seabrook Estuary (Table D-1-10). For the majority of fish species, the abundance was higher prior to operations than during operations at both the nearfield and farfield sites. The abundance of a few fish species increased during operations at both nearfield and farfield sites.
Table D-1-9. Geometric mean catch per unit effort (CPUE) (No. per 10-minute tow) and upper and lower 95% CL during preoperational and operational monitoring years for the most abundant species Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95%
CL Mean Upper 95% CL Yellowtail flounder Nearfield (T2) 2.7 3.7 5.0 0.1 0.2 0.3 Farfield (T1) 15.7 20.6 26.9 1.8 2.4 3.1 Farfield (T3) 6.6 9.2 12.8 1.4 2.1 3.0 Longhorn sculpin Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.6 1.0 1.5 0.4 0.6 0.8 2.3 3.2 4.5 2.3 3.1 4.1 4.2 6.1 8.5 4.8 6.4 8.4 Winter flounder Nearfield (T2)
Farfield (T1)
Farfield (T3) 3.7 5.5 8.0 1.6 2.3 3.1 2.1 2.8 3.6 3.0 4.0 5.4 1.1 1.4 1.9 2.7 3.6 4.8 28 Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95%
CL Mean Upper 95% CL Hake Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.6 0.9 1.2 0.3 0.4 0.5 1.3 1.7 2.0 0.4 0.6 0.8 0.8 1.1 1.4 0.4 0.9 1.4 Atlantic cod Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.5 0.8 1.2 0.1 0.2 0.4 1.7 2.6 3.7 0.2 0.3 0.5 2.6 4.1 6.2 0.8 1.1 1.5 Raja sp.
Nearfield (T2) 0.4 0.6 0.7 0.4 0.7 0.9 Farfield (T1) 0.8 1.4 2.3 1.6 2.2 2.9 Farfield (T3) 2.0 2.6 3.2 2.6 3.5 4.7 Windowpane Nearfield (T2) 0.8 1.2 1.6 0.7 1.0 1.3 Farfield (T1) 1.1 1.6 2.3 1.4 1.8 2.2 Farfield (T3) 0.6 0.9 1.4 1.0 1.7 2.6 Rainbow smelt Nearfield (T2) 2.2 3.2 4.3 0.3 0.5 0.8 Farfield (T1) 1.6 2.3 3.1 0.4 0.6 0.9 Farfield (T3) 0.9 1.6 2.5 0.4 0.6 0.8 Ocean pout Nearfield (T2) 0.6 0.8 1.0 0.2 0.2 0.3 Farfield (T1) 0.6 0.7 1.0 0.1 0.1 0.2 Farfield (T3) 1.4 1.8 2.3 0.1 0.2 0.3 Silver hake Nearfield (T2) 0.0 0.1 0.1 0.0 0.0 0.1 Farfield (T1) 0.1 0.2 0.4 0.3 0.6 0.9 Farfield (T3) 0.1 0.2 0.3 0.1 0.3
0.6 Source
(NAI 2010)
Table D-1-10. Geometric mean CPUE (No. per 24-hr surface and bottom gill net set) and coefficient of variation (CV) during preoperational (1976-1989) and operational monitoring years (1990-1996)
Species Sample site Preoperational monitoring Operational monitoring Mean CV Mean CV Atlantic herring Nearfield (G2) 1.1 20 0.2 33 Farfield (G1) 1.0 18 0.3 22 Farfield (G3) 1.2 21 0.4 25 Atlantic mackerel Nearfield (G2)
Farfield (G1)
Farfield (G3) 0.2 15 0.3 29 0.2 16 0.3 17 0.3 16 0.3 15 Pollock Nearfield (G2)
Farfield (G1) 0.3 10 0.3 16 0.2 17 0.2 18
29 Species Sample site Preoperational monitoring Operational monitoring Mean CV Mean CV Farfield (G3) 0.3 13 0.2 13 Spiny dogfish Nearfield (G2)
Farfield (G1)
Farfield (G3)
<0.1 35 0.1 41
<0.1 45 0.1 69
<0.1 27 0.2 47 Silver hake Nearfield (G2)
Farfield (G1)
Farfield (G3) 0.2 35 0.1 60 0.2 34 0.1 40 0.3 31 0.1 31 Blueback herring Nearfield (G2) 0.3 18 0.2 26 Farfield (G1) 0.2 17 0.2 50 Farfield (G3) 0.3 24 0.2 32 Alewife Nearfield (G2) 0.1 14 0.1 21 Farfield (G1) 0.1 17 0.1 34 Farfield (G3) 0.1 21 0.1 35 Rainbow smelt Nearfield (G2) 0.1 21 0.1 29 Farfield (G1)
<0.1 26 0.1 40 Farfield (G3) 0.1 21 0.1 39 Atlantic cod Nearfield (G2)
<0.1 22
<0.1 63 Farfield (G1) 0.1 18
<0.1 53 Farfield (G3) 0.1 13
<0.1 63 Source: (NAI 1998)
NAI (2010) reported different trends at farfield and nearfield sites for winter flounder, silver hake, and rainbow smelt during trawling surveys (Table D-1-9). At the nearfield site (T2), the abundance of winter flounder significantly decreased over time from a mean CPUE of 5.5 prior to operations to 2.3 during operations. However, at both farfield sampling sites (T1 and T3), the mean CPUE increased from 2.8 and 1.4 prior to operations, respectively, to 4.0 and 3.6 during operations. This increase was statistically significant at one of the farfield sites (T3). Silver hake abundance also increased at farfield sampling sites and decreased at the nearfield sampling site. NAI (2010) did not report if these trends were statistically significant. Rainbow smelt abundance decreased at all sampling sites, but the decrease was significantly greater at the nearfield site compared to the farfield sites (NAI 2010).
NAI (2010) reported different trends at farfield and nearfield sites for American sand lance abundances during seine pulls in the Hampton-Seabrook Estuary (Table D-1-11). At the nearfield sampling station (S2), the abundance of American sand lance decreased over time from a mean CPUE of 0.2 prior to operations to 0.1 during operations. At both farfield sampling sites (S1 and S3), the mean CPUE increased from 0.1 prior to operations, to 0.2 and 0.6, respectively, during operations. NAI (2010) did not report if these trends were statistically significant.
30 Table D-1-11. Geometric mean CPUE (No. per seine haul) and upper and lower 95% CL during preoperational and operational monitoring years Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95% CL Mean Upper 95% CL Atlantic silverside Nearfield (S2) 5.1 6.8 9.1 2.4 3.1 4.1 Farfield (S1) 5.1 7.2 10.2 3.6 4.8 6.2 Farfield (S3) 4.0 6.7 10.7 2.1 2.9 3.9 Winter flounder Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.6 1.0 1.5 0.1 0.2 0.3 0.6 0.9 1.2 0.2 0.4 0.5 2.2 3.2 4.4 0.3 0.5 0.7 Killifishes Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.6 1.2 2.0 0.1 0.2 0.3 0.8 1.1 1.5 0.5 0.9 1.3
<0.1
<0.1 0.1 0.1
<0.1 0.1 Ninespine stickleback Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.3 0.8 1.6
<0.1 0.1 0.1 0.4 0.7 1.2 0.1 0.2 0.3 0.3 0.8 1.4 0.1 0.2 0.3 Rainbow smelt Nearfield (S2)
Farfield (S1)
Farfield (S3)
<0.1 0.2 0.3 0.1 0.1 0.2
<0.1 0.1 0.2
<0.1 0.1 0.2 0.3 0.7 1.2 0.1 0.2 0.4 American sand lance Nearfield (S2) 0.0 0.2 0.5 0.0 0.1 0.1 Farfield (S1)
<0.1 0.1 0.2 0.1 0.2 0.3 Farfield (S3)
<0.1 0.1 0.2 0.3 0.6 0.9 Pollock Nearfield (S2)
<0.1 0.2 0.3 0.0
<0.1
<0.1 Farfield (S1)
<0.1 0.1 0.2
<0.1
<0.1
<0.1 Farfield (S3) 0.1 0.4 0.8
<0.1 0.1 0.1 Blueback herring Nearfield (S2)
<0.1 0.1 0.1
<0.1 0.1 0.1 Farfield (S1) 0.1 0.2 0.3 0.1 0.3 0.4 Farfield (S3)
<0.1 0.1 0.3
<0.1
<0.1 0.1 Atlantic herring Nearfield (S2) 0.1 0.3 0.5
<0.1
<0.1 0.1 Farfield (S1) 0.0 0.1 0.5 0.1 0.2 0.3 Farfield (S3) 0.1 0.1 0.2
<0.1 0.1 0.2 Alewife Nearfield (S2) 0.0 0.1 0.2
<0.1
<0.1
<0.1 Farfield (S1)
<0.1 0.1 0.2 0.1 0.2 0.4 Farfield (S3)
<0.1 0.1 0.1 0.0 0.1
0.2 Source
(NAI 2010)
NextEra monitoring results suggest that Seabrook operations have not likely affected most fish species near Seabrook. However, the abundance of winter flounder and rainbow smelt has decreased to a greater and observable extent near Seabrooks intake and discharge structures compared to 3 to 4 mi (5 to 8 km) away. The local decrease suggests that, to the extent local
31 subpopulations exist within 3 to 4 mi (5 to 8 km) of Seabrook, they have been adversely affected through operation of Seabrooks cooling water system.
Invertebrates. NAI (2010) reported similar trends of total invertebrate density and species diversity at the nearfield and farfield sampling sites before and during operations. Likewise, NAI (2010) reported similar trends at the nearfield and farfield sampling sites prior to and during operations for mytilid (mussel) spat, rock crabs, Jonah crabs, northern horse mussels, sea stars, green sea urchin, lobsters, and soft shell clams.
Macroalgae. NAI (2010) observed significant changes in kelp density prior to and during operations (Table D-1-12). NAI (2010) reported significantly higher Laminaria digitata density prior to than during operations. In the shallow and the mid-depth subtidal, the decline at the nearfield sampling site was significantly greater than the decline at the farfield station. In the nearfield mid-depth sampling site (B19), NAI (2010) did not identify L. digitata in 2008 or 2009.
The density of Agarum clathratum, which competes with L. digitata, significantly increased over time in the mid-depth sampling stations, and density was significantly higher at the nearfield site (NAI 2010).
Table D-1-12. Kelp density (No. per 100 m2) and upper and lower 95% CL during preoperational and operational monitoring years Kelp Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95% CL Mean Upper 95% CL L. digitata Nearfield Shallow (B17) 140.6 213.9 287.3 5.3 15.2 25.2 Farfield Shallow (B35) 96.5 155.8 215.1 52.3 73.9 95.6 Nearfield Mid-depth (B19) 81.5 139.9 198.3 3.1 7.5 11.9 Farfield Mid-depth (B31) 401.6 500.2 598.7 106.0 157.7 209.5 Sea belt Nearfield Shallow (B17) 270.7 415.1 559.4 66.1 137.9 209.7 Farfield Shallow (B35) 210.9 325.7 440.5 247.8 326.0 404.2 Nearfield Mid-depth (B19) 2.0 59.1 116.3 1.5 10.1 18.7 Farfield Mid-depth (B31) 59.6 95.5 131.5 29.3 48.2 68.2 A. esculenta Nearfield Mid-depth (B19) 0.0 2.4 7.2 0.3 2.3 4.2 Farfield Mid-depth (B31) 19.9 75.2 130.5 20.3 40.0 59.6 A. clathratum Nearfield Mid-depth (B19) 613.5 786.6 959.6 792.2 955.2 1,118.1 Farfield Mid-depth (B31) 280.2 366.4 452.6 407.3 503.6 599.9 Source: (NAI 2010)
In the shallow subtidal, sea belt (Saccharina latissima) density was significantly lower during operations at the nearfield site, but there was no significant change at the farfield site (NAI 2010). In the mid-depth subtidal, sea belt density significantly decreased at both sampling sites (NAI 2010). In the mid-depth subtidal, Alaria esulenta significantly declined during operations at the farfield site and remained at a low density at the nearfield site prior to and during operations (NAI 2010). NAI (2010) did not identify A. esulenta at the nearfield sampling station over the past 4 years.
The decrease in L. digitata density was significantly greater at the nearfield sites, and sea belt density was lower during operations at the nearfield site but not at the farfield site in the shallow 32 subtidal. These results suggest that the local population of L. digitata and sea belt has been adversely affected through operation of Seabrooks cooling water system.
D-1.3.3 Adverse Effects on Essential Fish Habitat by Species D-1.3.3.1 American Plaice (Hippoglossoides platessoides) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated American plaice juvenile and adult EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed American plaice juveniles and adults or both in 110 percent of trawling samples from the 1970s through 2009 (Table D-1-2).
Species Description. American plaice are arctic-boreal pleuronectid flatfish (Johnson 1995).
American plaice inhabit both sides of the Atlantic Ocean. In the western Atlantic, American plaice are common from Newfoundland, Canada to Montauk Point, NY (Bigelow and Schroeder 1953; Johnson 2005). EFH for American plaice juveniles and adults includes bottom habitats with fine-grained, sandy, or gravel substrates in the Gulf of Maine (NMFS 2011c).
American plaice are relatively sedentary, and tagging studies have indicated that few migrate long distances. Fisheries and Oceans Canada (DFO) (1989, cited in Johnson 2005) recaptured the majority of tagged fish within 30 mi (48 km) of the tagging site after 7 to 8 years.
American plaice consume a wide-variety of prey and are opportunistic feeders, in that they will consume what is most available (Johnson 2005). Prior to settling on the ocean floor, juveniles feed on small crustaceanssuch as cumaceansand polychaetes (Bigelow and Schroeder 1953). Adults are primarily benthic but, at night, may migrate up into pelagic waters to prey on non-benthic species (DFO 1989, cited in Johnson 2005). During monitoring surveys, NAI (2010) did not observe American plaice in pelagic waters. Prey for adults include mostly echinoderms (e.g., sand dollars, sea urchins, and brittle stars) and crustaceans, cnidarians, and polychaetes (Johnson 2005). Redfish eat American plaice larvae, and goosefish, halibut, cod, and other bottom feeders prey on the adults (Johnson 2005).
Status of the Fishery. NMFS, the New England Fishery Management Council (NEFMC), and the Mid-Atlantic Fishery Management Council (MAFMC) currently manage the northeast multispecies fisheries management plan (FMP). The U.S. fishery for American plaice started to develop around 1975 in the Gulf of Maine, when other commercially desirable flatfish (e.g., yellowtail flounder, winter flounder, and summer flounder) began to decrease in abundance (Sullivan 1981, cited in Johnson 2005). American plaice populations in the western North Atlantic have declined dramatically since the early 1980s (Johnson 2005). Contributing factors to the decline are likely overfishing, changes in water temperature, and water pollution (Johnson 2005). American plaice is also bycatch for other fisheries. In New England, the mortality of American plaice bycatch was positively correlated with ondeck sorting time (Johnson 2005). In 2009, NEFMC considered American plaice overfished (NMFS 2010b).
Entrainment and Impingement at Seabrook. Although NMFS has not designated EFH for American plaice eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of American plaice eggs varied from 0.4 million in 1994 to 52.3 million in 1992 (NAI 2010). Annual average entrainment of American plaice eggs was 25.9 million per year (Table D-1-4). American plaice eggs comprised approximately 3 percent of the total fish eggs entrained at Seabrook.
Entrainment of American plaice larvae varied from 0 in 1994 to 11.5 million in 2009 (NAI 2010).
Annual average entrainment of American plaice larvae was 4.3 million per year (Table D-1-5).
American plaice larvae comprised approximately 1.5 percent of the total fish larvae entrained at Seabrook.
33 Impingement of American plaice varied from zero in several years to seven in 2008 (NAI 2010).
Annual average impingement was less than one fish per year (Table D-1-6). American plaice comprised less than 1 percent of all impinged fish at Seabrook.
Because entrainment and impingement were relatively low for American plaice compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult American plaice. American plaice are primarily benthic (Johnson 2005). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult American plaice are opportunistic feeds that primarily consume invertebrates, including green sea urchins (Strongylocentrotus droebachiensis) (Johnson 2005). NextEra monitoring data show relatively similar trends of benthic invertebrate abundance, density, and species diversityincluding the abundance of green sea urchinsprior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-Forming Species. American plaice inhabit soft bottom areas, including soft bottom areas that border bedrock (Johnson 2005). Keats (1991) hypothesized that American plaice inhabited areas boarded by bedrock because bedrock is the preferred habitat for green sea urchins, an important prey species for American plaice. Because preferred habitat for American plaice are soft bottom substrates, such as fine sand or gravel, the NRC concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of juvenile and adult American plaice prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for American plaice juveniles or adults for the following reasons:
Impingement and entrainment are relatively low.
The thermal plume rises quickly to the surface.
Invertebrate forage species are not likely adversely affected by Seabrook operations.
Preferred habitat does not include shellfish or kelp beds.
D-1.3.3.2 Atlantic butterfish (Peprilus triacanthus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic butterfish EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic butterfish eggs and larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in 1 to 10 percent of gill net samples, juveniles and adults in less than 34 1 percent of trawling samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Adult Atlantic butterfish are pelagic schooling fish that are ecologically important as a forage fish for many larger fishes, marine mammals, and birds. Atlantic butterfish inhabit the Atlantic coast from Newfoundland to Florida, but it is most abundant from the Gulf of Maine to Cape Hatteras (Cross et al. 1999; Overholtz 2006). Adult butterfish migrate seasonally. In the summer, they migrate inshore into bays, estuaries, and coastal waters of southern New England and the Gulf of Maine. In winter, they migrate to the edge of the continental shelf in the Mid-Atlantic Bight (Cross et al. 1999). Adults generally stay within 200 mi (322 km) of the shore.
Butterfish reach sexual maturity between ages 1 to 2 years and rarely live more than 3 years (Overholtz 2006). Adults are 5.9 to 9.1 in. (15 to 23 cm) long on average and can reach a weight of up to 1.1 lb (0.5 kg). Females are broadcast spawners and spawn in large bays and estuaries from June through August. Females generally release eggs at night in the upper part of the water column in water of 59° F (15° C) or more. Eggs are pelagic and buoyant (Cross et al. 1999). Butterfish eggs and larvae are found in water with depths ranging from the shore to 6,000 ft (1,828 m) and at temperatures between 53.6 and 73.4° F (12 and 23° C) for eggs and between 39.2 and 82.4° F (4 and 28° C) for larvae (Cross et al. 1999). Juvenile and adult butterfish are found in waters from 33 to 1,200 ft (10 to 366 m) deep and at temperatures ranging from 37 to 82° F (3 to 28° C) (Cross et al. 1999). In summer, juvenile and adult butterfish can be found over the entire continental shelf, including sheltered bays and estuaries, to a depth of 656 ft (200 m) over substrates of sand, rock, or mud (Cross et al. 1999).
Butterfish prey mainly on urochordates and mollusks, with minor food sources including squid; crustaceans, such as amphipods and shrimp; annelid worms; and small fishes (Bigelow and Schroeder 2002; Cross et al. 1999). In turn, many speciesincluding haddock, silver hake, goosefish, bluefish, swordfish (Xiphias gladuis), sharks, and longfin inshore squideat adult butterfish (Cross et al. 1999).
Status of the Fishery. The Atlantic butterfish has been commercially fished since the late 1800s (Cross et al. 1999). By the mid-1900s, fishing fleets from Japan, Poland, the USSR, and other countries began to target the butterfish and caused a drastic increase in landings (Cross et al. 1999; Overholtz 2006). Landings peaked in 1973 at 75.6 million lb (34,300 metric tons (MT))
(Overholtz 2006). U.S. commercial landings averaged 7.1 million lb (3,200 MT) from 19652002 but have steadily decreased since 1985 (Overholtz 2006). In 2009, NOAA reported a cumulative landing of 0.95 million lb (430 MT), and, as of November 27, 2010, the reported landings for 2010 were 1.2 million lb (550 MT) (NOAA 2009, 2010). Butterfish are also caught as bycatch in other fisheries. Bycatch landings averaged 9.3 million lb (4,200 MT) per year from 1996 through 2002 (Overholtz 2006).
The MAFMC manages the Atlantic butterfish under an FMP that includes the Atlantic mackerel, squid, and butterfish. The Atlantic butterfish fishery is capped by an annual coast-wide quota.
A directed fishery for butterfish is open from January through August; however, most butterfish are harvested as bycatch in squid fisheries (NOAA 2010a). In 2009, NEFMC reported butterfish to be overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of Atlantic butterfish eggs varied from 0 in several years to 400,000 in 2005 (NAI 2010). Annual average entrainment of Atlantic butterfish eggs was 25,500 per year from 1990 through 2009 (Table D-1-4). Entrainment of Atlantic butterfish larvae varied from 0 in several years to 1.19 million in 2007 (NAI 2010). Annual average entrainment of Atlantic butterfish larvae was 90,000 per year from 1990 through 2009
35 (Table D-1-5). Atlantic butterfish eggs and larvae comprised less than 0.05 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic butterfish varied from 1 in 2000 to 1,170 in 2002 (NAI 2010). Annual average impingement was 114 fish per year from 1994 through 2009 (Table D-1-6). Atlantic butterfish comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic butterfish compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for all life stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Impacts. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to butterfish eggs, larvae, juveniles, or adults. As described above, the habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m)) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F (2.8° C) in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Butterfish are most common near Seabrook from August through November, when the surface temperature near Seabrook ranges from 46.4 to 65.8° F (8 to 18.8° C) (NAI 2001). Butterfish eggs and larvae are found in water at temperatures between 53.6 and 73.4° F (12 and 23° C) for eggs and between 39.2 and 82.4° F (4 and 28° C) for larvae (Cross et al. 1999). Juvenile and adult butterfish are found in waters at temperatures ranging from 37 to 82° F (3 to 28° C) (Cross et al. 1999). With a temperature rise of 3 to 5° F (1.7 to 2.8° C) at the surface near Seabrook, the thermal plume near the surface from August through November would be within the range of temperature that butterfish eggs, larvae, juveniles, and adults typically inhabit. Therefore, the NRC staff concludes that the increased temperatures of Seabrooks effluent are not likely to adversely affect EFH for all stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic butterfish primarily prey on invertebrates (Bigelow and Schroeder 2002; Cross et al. 1999). NextEra monitoring data show relatively similar trends of benthic invertebrate density and species diversity prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. All life stages of Atlantic butterfish are primarily pelagic (Cross et al. 1999), suggesting that they rarely use benthic habitats such as shellfish and kelp beds.
Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for all life stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic butterfish eggs, larvae, juveniles, or adults prior to and during operations (NAI 2010).
Conclusion Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for all life stages of Atlantic butterfish for the following reasons:
36 Impingement and entrainment are relatively low for Atlantic butterfish.
The increased temperature within the thermal plume at the surface would be with the range of temperatures that Atlantic butterfish inhabit.
Invertebrate forage species are not likely to be adversely affected by Seabrook operations.
Their preferred habitat does not include shellfish or kelp beds.
D-1.3.3.3 Atlantic cod (Gadus morhua) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic cod EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic cod eggs and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, juveniles and adults in 1 to 10 percent of gill net samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Atlantic cod are demersal and highly targeted commercially. Atlantic cod inhabit the northwestern Atlantic Ocean, from Greenland to Cape Hatteras, NC. In the U.S., the highest densities of Atlantic cod are on Georges Bank and the western Gulf of Maine, in waters between 33 and 492 ft (10 and 150 m) with rough bottoms and at temperatures between 32 and 50° F (0 and 10° C) (Lough 2004). Offshore New England, juvenile and adult Atlantic cod move seasonally in response to temperature changes, whereby Atlantic cod typically move into coastal waters during the fall and deeper waters during spring. At the extremes of their range, including Labrador and south of the Chesapeake, Atlantic cod migrate annually (Lough 2004).
In Gulf of Maine, Atlantic cod reach sexual maturity at 2.1 to 2.9 years at lengths between 13 and 17 in. (32 and 44 cm) (Lough 2004). Females spawn during winter and early spring in bottom waters generally between 41 and 44.6° F (5 and 7° C). A large female may produce as many as 3 to 9 million eggs (Lough 2004). Eggs and larvae for the first 3 months are pelagic (Lough 2004). Once larvae reach 1.6 to 2.4 in. (4 to 6 cm), they begin to descend towards the seafloor. As Atlantic cod develop into juveniles and adults, they are able to withstand deeper, colder, and more saline water, and they become more widely distributed (Lough 2004).
Complex substrate and vegetation provides refuge from predators for juvenile cod (Lough 2004).
Forage species tend to vary by life stage and location (Lough 2004). Juveniles and younger adults tend to consume pelagic and benthic invertebrates, while adult cod feed on both crustaceans and other fish, including cancer crabs, brittle stars, American sand lance, Atlantic herring, and American plaice (Johnson 2005; Lough 2004; Witman and Sebens 1992). Atlantic herring and Atlantic mackerel can be important predators of Atlantic cod larvae (Lough 2004).
Silver hake, sculpin, larger cod, and other fish consume juvenile Atlantic cod (Edwards and Bowman 1979, cited in Lough 2004). Winter skate, silver hake, sea raven, longfin inshore squid, Atlantic halibut, fourspot flounder, and large adult cod consume smaller adult cod (Lough 2004).
Status of the Fishery. Atlantic cod has been a highly targeted species since the 1700s. As a likely result of harvesting older and larger fish or due to intense exploitation in stock biomass, the size and age at maturity for Atlantic cod has declined in recent decades (Lough 2004).
Currently, Atlantic cod is managed as two stocks within U.S. waters: (1) the Gulf of Maine and (2) Georges Bank and southward (Mayo 1995). In 2009, NEFMC reported Atlantic cod to be subject to overfishing (NMFS 2010b).
37 Entrainment and Impingement. Entrainment of Atlantic cod eggs varied from 0.2 million in 1994 to 77.8 million in 2002 (NextEra 2010a). Annual average entrainment of Atlantic cod eggs was 32.6 million per year from 1990 through 2009 (Table D-1-4). Atlantic cod eggs comprised 3.6 percent of the total fish eggs entrained at Seabrook from 1990 through 2009. Entrainment of Atlantic cod larvae varied from 0 in 1994 to 34.6 million in 2002 (NAI 2010). Annual average entrainment of Atlantic cod larvae was 2.8 million per year from 1990 through 2009 (Table D-1-5). Atlantic cod larvae comprised approximately 1 percent of the total fish larvae entrained at Seabrook from 19902009.
Impingement of Atlantic cod varied from 29 in 2000 to 3,091 in 2003 (NAI 2010). Annual average impingement was 327 fish per year from 1994 through 2009 (Table D-1-6). Atlantic cod comprised less than 2 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic cod compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic cod during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic cod eggs, juveniles, or adults. Seabrooks thermal discharge may reduce available habitat to Atlantic cod larvae.
Atlantic cod eggs and larvae are pelagic (Lough 2004). NEFSC MARMAP ichthyoplankton surveys collected most eggs at temperatures ranging from 39 to 57° F (4 to 14° C), but collected eggs as high as 72° F (22° C) (Lough 2004). NEFSC MARMAP ichthyoplankton surveys collected most larvae from 39 to 52° F (4 to 11° C), but collected larvae as high as 66° F (19° C)
(Lough 2004). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface could exceed the typical range of temperatures that Atlantic cod larvae inhabit.
The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Juvenile and adult Atlantic cod are primarily benthic (Lough 2004), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface and the temperature range of the thermal plume near the surface would be within the typical range for Atlantic cod eggs, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic cod eggs, juveniles, or adults during the remainder of the facilitys operating license or during the proposed license renewal term. Because the thermal plume could exceed the typical range of temperatures that larvae inhabit, the NRC staff concludes that the heated thermal effluent may have minimal adverse effects on Atlantic cod larvae.
Loss of Forage Species. Juveniles and younger adults consume pelagic and benthic invertebrates, while adult cod feed on both crustaceans and other fish (Lough 2004). In the Gulf of Maine, Bowman (1975, cited in Lough 2004) found Atlantic herring to be a primary prey item for Atlantic cod. Link and Garrison (2002) determined that preferred prey in the Gulf of Maine include American sand lance, cancer crabs, and Atlantic herring. NextEra monitoring data show relatively similar trends in the abundance and density of benthic invertebrates (including cancer crabs) and most fish species prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010). Atlantic herring, a primary prey item for Atlantic cod in the Gulf of Maine, was the fifth most commonly entrained larval species, comprising 3.6 percent of all entrained larvae (NAI 2010) (Table D-1-5). Atlantic herring comprised less than 1 percent of all impinged fish (NAI 2010) (Table D-1-6). American 38 sand lance, a preferred prey item for Atlantic cod, was the second most commonly entrained larval species, comprising 10 percent of all entrained larvae (NAI 2010) (Table D-1-5).
American sand lance was the 10th most commonly impinged fish species, comprising 4.3 percent of all impinged fish (NAI 2010) (Table D-1-6).
Because some of the primary and preferred forage fishsuch as Atlantic herring and American sand lanceare regularly entrained and impinged at Seabrook, operations at Seabrook may have a minimal adverse effect on prey abundance for Atlantic cod. Effects would likely be minimal since Atlantic cod consume a variety of species, many of which are not regularly entrained or impinged at Seabrook.
Loss of Habitat-forming Species. Complex substrate and vegetation provide refuge from predators for juvenile cod (Lough 2004). Therefore, juvenile cod likely use macroalgae and shellfish beds near Seabrook. Monitoring studies suggest that Seabrook operations have adversely affected the density of several kelp species near Seabrook. Therefore, Seabrook operations may have a minimal adverse effect on juvenile Atlantic cod habitat. Effects would likely be minimal since juvenile Atlantic cod inhabit a variety of substrates and vegetation to find refuge from predators.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of eggs, larvae, juvenile and adult Atlantic cod prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away. Ichthyoplankton studies indicated that the density of Atlantic cod larvae decreased significantly at both nearfield and farfield sampling sites (NAI 2010) (Table D-1-8). Monitoring data from trawl studies and gill net studies indicate that the abundance of juvenile and adult Atlantic cod also significantly decreased at both nearfield and farfield sampling sites (Tables D-1-9 and D-1-10). The decreased abundance at both nearfield and farfield sampling sites suggest that Seabrook operations have not adversely affected EFH for Atlantic cod within 3 to 4 mi (5 to 8 km) of Seabrook.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for Atlantic cod larvae, juveniles, and adults, because Seabrooks cooling system regularly entrains and impinges preferred forage fish for Atlantic cod, the thermal plume could exceed the typical range of temperatures that larvae inhabit, and because juveniles may use algal habitats that have declined near Seabrook since operations began. Impacts would likely be minimal since Atlantic cod are not commonly entrained or impinged in the Seabrook cooling system, the thermal plume rises quickly to the surface, invertebrate forage species are not likely adversely affected by Seabrook operations, and monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
D-1.3.3.4 Atlantic herring (Clupea harengus) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult Atlantic herring EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic herring in 1 to 10 percent of trawling samples, greater than 10 percent of gill net samples, and in 1 to 10 percent of seine pull samples (Table D-1-2).
Species Description. Adult Atlantic herring are pelagic, schooling fish that inhabit both the eastern and western Atlantic Ocean (Stevenson and Scott 2005). Juveniles migrate nearshore to further offshore seasonally, whereas adult Atlantic herring migrate north-south along the U.S.
and Canadian coasts for feeding, spawning, and overwintering.
39 Larvae develop into juveniles in the spring, at approximately 1.6 to 2.2 in. (40 to 55 mm) length (Stevenson and Scott 2005). Schooling behavior begins once Atlantic herring develop into juveniles (Gallego and Heath 1994). NOAAs Northeast Fishery Science Center (NEFSC) captured juveniles in waters from 35 to 54° F (2 to 12° C) in the spring and from 41 to 63° F (5 to 17° C) in the fall, during bottom trawl surveys from the Gulf of Maine to Cape Hatteras (Stevenson and Scott 2005). Adults occurred in waters from 35 to 55° F (2 to 13° C) in the spring and from 39 to 61° F (4 to 16° C) in the fall (Stevenson and Scott 2005).
Juvenile and adult Atlantic herring are opportunistic feeders and prey on zooplankton. The most common prey items for juveniles include copepods, decapods larvae, barnacle larvae, cladocerans, and molluscan larvae (Sherman and Perkins 1971, cited in Stevenson and Scott 2005). Common prey items for adults include euphausiids, chaetognaths, and copepods (Bigelow and Schroeder 1953; Maurer and Bowman 1975, cited in Stevenson and Scott 2005).
Adults also prey upon fish eggs and larvae, including larval Atlantic cod, herring, sand lance, and silversides (Munroe 2002; Stevenson and Scott 2005).
Atlantic herring are an important component of the Gulf of Maine food web and are preyed upon throughout their life cycle (Stevenson and Scott 2005). Predators include a variety of fish (such as Atlantic cod, silver hake, thorny skate, bluefish, goosefish, weakfish, summer flounder, white hake, Atlantic halibut, red hake, and northern shortfin squid), marine mammals, and sea birds (Stevenson and Scott 2005).
Status of the Fishery. In U.S. waters, NEFMC manage Atlantic herring as a single stock (Stevenson and Scott 2005). In 2009, NEFMC did not consider Atlantic herring overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for Atlantic herring eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. NAI (2010) did not observe entrainment of Atlantic herring eggs from 1990 through 2009. Entrainment of Atlantic herring larvae varied from 0.1 million in 1994 to 28.2 million in 2008 (NAI 2010). Annual average entrainment of Atlantic herring larvae was 9.6 million per year from 1990 through 2009 (Table D-1-5). Atlantic herring larvae comprised approximately 3.6 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic herring varied from 0 in 1994/1995 to 582 in 1998 (NAI 2010). Annual average impingement was 187 fish per year from 1994 through 2009 (Table D-1-6). Atlantic herring comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic herring compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for juvenile and adult Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. Seabrooks thermal discharges may reduce available habitat to juvenile and adult Atlantic herring. The habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Adult and juvenile Atlantic herring are most common near Seabrook from April through May, when the surface temperature near Seabrook ranges from 41 to 51° F (5 to 10.7° C) and from October through December, when the surface temperature ranges from 42 to 57.7° F (5.6 to 14.3° C) (NAI 2001). NEFSC trawl surveys captured juveniles in waters up to 54° F (12° C) in the spring and 63° F (17° C) in the fall and 40 adults up to 55° F (13° C) in the spring and up to 61° F (16° C) in the fall (Stevenson and Scott 2005). With a temperature rise of 3 to 5° F (1.7 to 2.8 ° C), the thermal plume near the surface could slightly exceed the typical range of temperature that Atlantic herring juveniles and adults inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Therefore, the NRC staff concludes that the increased temperatures at Seabrook may have a minimal adverse effect on EFH for adult and juvenile Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult Atlantic herring are opportunistic feeders and prey on a wide variety of zooplankton. Adults prey upon fish eggs and larvae, including larval Atlantic cod, herring, sand lance, and silversides (Munroe 2002; Stevenson and Scott 2005).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the zooplankton (NAI 2010). American sand lance larvae, a common prey item for Atlantic herring, were the second most commonly entrained larval species, comprising 10 percent of all entrained larvae (NAI 2010) (Table D-1-5). Other common larval prey, such as Atlantic herring and Atlantic cod larvae, comprised approximately 1 percent or less of the total fish larvae entrained at Seabrook. The NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for adult and juvenile Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the fact that Atlantic herring prey upon a wide variety of fish larvae, and monitoring studies suggest that zooplankton abundance has not been adversely affected by Seabrook operations.
Loss of Habitat-forming Species. Adult and juvenile Atlantic herring are primarily pelagic (Stevenson and Scott 2005), suggesting that they rarely use benthic habitats such as kelp and shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of juvenile and adult Atlantic herring prior to and during operations at sampling sites in Hampton-Seabrook Estuary near a previous discharge location and at sites further away. Monitoring data indicate that the abundance of juvenile and adult Atlantic herring decreased at both nearfield and farfield sampling sites (Table D-1-11). Because NAI (2010) observed similar trends at all sampling sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for adult and juvenile Atlantic herring.
Conclusion. Because of the observations above, and because the thermal plume could increase the temperature near the surface to above the temperature range that Atlantic herring typically inhabit, the NRC staff concludes that Seabrook operations may have a minimal adverse effect on EFH for adult and juvenile Atlantic herring.
D-1.3.3.5 Atlantic mackerel (Scomber scombrus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic mackerel EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic mackerel eggs and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in less than 1 percent of trawling samples, juveniles and adults in greater than 10 percent of gill net samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
41 Species Description. Atlantic mackerel are pelagic, schooling fish that inhabit the western Atlantic Ocean from the Gulf of St. Lawrence to North Carolina (Studholme et al. 1999). Adults are highly mobile.
In reviewing multiple studies, Studholme et al. (1999) indicated that the age of maturation varies from 1.7 to 3 years of age, depending on the location, size of the year class, and size of the adult stock. In the Gulf of Maine, females spawn from mid-April through June as they migrate from the south (Berrien 1982, cited in Studholme et al. 1999). The Gulf of Maine is not one of the more important spawning grounds (Sette 1950, cited in Studholme et al. 1999). Eggs are pelagic and float in the upper 33 to 49 ft (10 to 15 m) of surface waters (Studholme et al. 1999).
NEFSC collected eggs near the surface at temperatures ranging from 41 to 73° F (5 to 23° C) and larvae from 43 to 72° F (6 to 22° C) as part of the Marine Resources Monitoring, Assessment, and Prediction (MARMAP) offshore ichthyoplankton survey.
Juveniles exhibit schooling behavior at about 1.2 to 2 in. (30 to 50 mm) (Sette 1943, cited in Studholme et al. 1999). NEFSC captured juveniles from 39 to 72° F (4 to 22° C) and adults from 39 to 61° F (4 to 16° C) during 1963 through 1997 bottom trawl surveys. Overholtz and Anderson (1976, cited in Studholme et al. 1999) conducted field studies that indicated that adult Atlantic mackerel are intolerant of temperatures greater than 61° F (16° C).
Atlantic mackerel are opportunistic and filter feed or ingest prey. Larvae feed on copepod nauplii, copepods, and fish larvae (Studholme et al. 1999). Both juveniles and adults prey on a variety of crustaceans, although adults consume a wider variety of prey sizes and items, including fish. Peterson and Ausubel (1984) determined that fish greater than 0.2 in. (5 mm) feed on copepodites of Acartia and Temora, and fish greater than 0.24 in. (6 mm) feed on adult copepods.
Atlantic mackerel is prey to a wide variety of fish, sharks, squid, whales, dolphins, seals, porpoises. Common fish predators include other mackerel, dogfish, tunas, bonito, striped bass, Atlantic cod, swordfish, silver hake, red hake, bluefish, pollock, white hake, goosefish, and weakfish (Studholme et al. 1999).
Status of the Fishery. In U.S. waters, MAFMC and NMFS manage Atlantic mackerel as a single stock (Studholme et al. 1999). In 2009, MAFMC did not consider Atlantic mackerel overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of Atlantic mackerel eggs varied from 0 in 1994 to 673.1 million in 1991 (NAI 2010). Annual average entrainment of Atlantic mackerel eggs was 191.5 million per year from 1990 through 2009 (Table D-1-4). Atlantic mackerel eggs comprised approximately 21.3 percent of the total fish eggs entrained at Seabrook from 1990 through 2009. Entrainment of Atlantic mackerel larvae varied from 0 in several years to 25.7 million in 2009 (NAI 2010). Annual average entrainment of Atlantic mackerel larvae was 2.6 million per year from 1990 through 2009 (Table D-1-5). Atlantic mackerel larvae comprised approximately 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic mackerel varied from 0 in several years to 4 in 2004 through 2005 (NAI 2010). Annual average impingement was less than three fish per year from 1994 through 2009 (Table D-1-6). Atlantic mackerel comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Entrainment of Atlantic mackerel larvae and impingement of Atlantic mackerel is small compared to other species impinged at Seabrook. However, Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook. Therefore, the NRC staff concludes that entrainment of Atlantic mackerel eggs may have minimal adverse effects on EFH for Atlantic mackerel during the remainder of the facilitys 42 operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for Atlantic mackerel eggs.
Thermal Effects. Seabrooks thermal discharges may reduce available habitat to adult Atlantic mackerel. The habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Atlantic mackerel are most common near Seabrook from June through November, when the surface temperature near Seabrook ranges from 46 to 66° F (8 to 18.8° C) (NAI 2001). During ichthyoplankton and trawling surveys, NEFSC captured eggs, larvae, and juveniles in waters up to 72° F (22° C) and adults in waters up to 61° F (16° C) (Studholme et al. 1999). With a temperature rise of 3 to 5° F (1.7 to 2.8° C),
the thermal plume near the surface could exceed the typical temperature range that adult Atlantic mackerel inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Therefore, the NRC staff concludes that the increased temperatures at Seabrook may have a minimal adverse effect on EFH for adult Atlantic mackerel during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic mackerel are opportunistic feeders and prey includes plankton, small crustaceans (including copepods), and some fish for larger Atlantic mackerel (Studholme et al. 1999). NextEras monitoring studies show similar trends prior to and during operations at nearfield and farfield sampling sites for changes in abundance, density, and species composition for phytoplankton, zooplankton (including copepods and fish larvae),
invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic mackerel during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Adult and juvenile Atlantic herring are primarily pelagic (Studholme et al. 1999), which suggests that they rarely use benthic habitats such as kelp and shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of Atlantic mackerel eggs, larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the density of eggs and abundance of juveniles and adults increased or remained the same at both nearfield and farfield sampling sites (Tables D-1-8 and D-1-10).
Larval density decreased at both nearfield and farfield sampling sites (Table D-1-8). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for Atlantic mackerel.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for Atlantic mackerel eggs and adults for the following reasons:
The thermal plume could increase the temperature near the surface to above the temperature range that adult Atlantic mackerel typically inhabit.
43 Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook.
The NRC staff concludes that Seabrook operations are not likely to adversely affect Atlantic mackerel larvae and juvenile for the following reasons:
These life stages are not commonly entrained or impinged in the Seabrook cooling system.
The thermal plume would not exceed the typical temperature range that juveniles inhabit.
Forage species are not likely adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
D-1.3.3.6 Atlantic sea scallop (Placopecten magellanicus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic sea scallop EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed a relatively low density of Atlantic sea scallop larvae in zooplankton tows (geometric mean density was approximately three to four scallops per 1,000 m3 prior to 2001 and less than one scallop per 1,000 m3 after 2001). Seabrook monitoring does not include juvenile and adult Atlantic sea scallops. Seabrook observations near the intake and discharge structures suggest that sea scallops are not common in this area (NAI 2001).
Species Description. Atlantic sea scallops are bivalve mollusks that occur along the Canadian and U.S. coasts from the Gulf of St. Lawrence south to Cape Hatteras, NC (Hart and Chute 2004).
Sea scallops produce gametes within the first or second year and are among the most fecund of bivalves (Langton et al. 1987). Spawning in Maine occurs from September through October.
Eggs remain demersal until they develop into larvae. The first two larval stages are pelagic and drift with water currents (Hart and Chute 2004). Larvae settle on the sea floor as spat and remain there throughout adult life. Spat that land on sedentary branching plants, animals, or on any other hard surface may have a higher survival rate than those that land in sandy bottom habitats subject to burial (Larsen and Lee 1978).
Juvenile scallops move from the original substrate on which they have settled and attach to shells or bottom debris (Dow and Baird 1960, cited in Hart and Chute 2004). Juveniles also swim to avoid predators and other natural or human-induced disturbances. Tagging studies suggest that adults remain sedentary once an aggregation has formed (Hart and Chute 2004).
Sea scallops are filter feeders. Food particles filtered from water include phytoplankton, microzooplankton (such as ciliated protozoa), and particles of detritus, especially during periods of low phytoplankton concentrations (Shumway et al. 1987). Both fish and invertebrates prey upon Atlantic sea scallops (Hart and Chute 2004).
Status of the Fishery. The Atlantic sea scallop is one of the most economically important species in the northeast U.S. (Hart and Chute 2004). NEFMC manages the sea scallop fishery under the Sea Scallop Management Plan. In 2009, NEFMC did not consider the sea scallop fishery overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not monitor entrainment of invertebrate eggs from 1990 through 2009. Entrainment of Atlantic sea scallop larvae varied from 0 in 2003 and 2006 to 31 million in 1996 (Table D-1-7) (NAI 2010). Annual average entrainment of Atlantic 44 sea scallop larvae was 4.8 million per year from 1990 through 2009 (NAI 2010). Atlantic sea scallop larvae comprised less than 1 percent of the total invertebrate larvae entrained at Seabrook from 1990 through 2009.
Because adult Atlantic sea scallops are sessile benthic organisms, impingement is not likely, and NextEra did not monitor impingement of Atlantic sea scallops.
Because entrainment was relatively low for Atlantic sea scallops compared to other invertebrate species at Seabrook, and because impingement is not likely, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic sea scallop. Atlantic sea scallops are primarily benthic (Chute and Hart 2004), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic sea scallops are filter feeders, and prey includes phytoplankton, microzooplankton (such as ciliated protozoa), and particles of detritus.
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for plankton (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Survival of newly settled Atlantic sea scallop appears to be higher in complex habitats that include sedentary branching animals, plants, and other hard surfaces (Larsen and Lee 1978). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but NextEra observed relatively similar trends for the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook but Atlantic sea scallops use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on habitat for newly settled Atlantic sea scallops.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic sea scallop eggs, larvae, juveniles, or adults prior to and during operations. However, NextEra monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Conclusion. Because spat appear to have higher survival rates in complex habitats, such as kelp forests, and because Seabrook monitoring data suggests that operations have adversely affected the density of several species of kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile sea scallops. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for eggs, larvae, and adult sea scallops for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
45 Forage species are not likely to be adversely affected.
Monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away.
D-1.3.3.7 Atlantic Surfclam (Spisula solidissima) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult Atlantic surf clam EFH in the vicinity of Seabrook (NMFS 2011b). Seabrook monitoring does not include juvenile and adult Atlantic surf clams (NAI 2010). NAI (2010) observed surface larvae near Seabrook and the geometric mean density was approximately 350 to 590 clams per 1,000 m3 prior to 2001 and 120 clams per 1,000 m3 after 2001.
Species Description. Atlantic surfclams are bivalve mollusks that inhabit sandy habitats from the southern Gulf of St. Lawrence to Cape Hatteras, NC (Merrill and Ropes 1969 in Cargnelli et al. 1999a). Clams feed by sucking in plankton, such as diatoms and ciliates, through their siphons (Cargnelli et al. 1999a). Predators include invertebrates (e.g., naticid snails, sea stars (Asterias forbesi), lady crabs (Ovalipes ocellatus), Jonah crabs (Cancer borealis), horseshoe crabs (Limulus polyphemus)) and fish (e.g., haddock and Atlantic cod) (see review in Cargnelli et al. 1999a).
Status of the Fishery. MAFMC manages the Atlantic surfclam under the Atlantic surfclam and ocean quahog FMP. In 2009, MAFMC did not consider the Atlantic surfclam fishery overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not monitor entrainment of invertebrate eggs from 1990 through 2009. Entrainment of Atlantic surf clam larvae varied from 0 in 1992 and 2006 to 175.5 million in 1999 (NAI 2010). Annual average entrainment of Atlantic surf clam larvae was 48.9 million per year from 1990 through 2009 (Table D-1-7). Atlantic surf clam larvae comprised less than 1 percent of the total invertebrate larvae entrained at Seabrook from 1990 through 2009.
Because adult Atlantic surf clams are sessile benthic organisms, impingement is not likely, and NextEra did not monitor impingement of Atlantic surf clams.
Because entrainment was relatively low for Atlantic surf clams compared to other invertebrate species at Seabrook, and because impingement is not likely, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic surf clams during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic surfclams. Juvenile and adult Atlantic surfclams are benthic (Cargnelli et al. 1999a), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic surfclam during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic surfclams feed on plankton, such as diatoms and ciliates.
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for plankton (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect 46 Atlantic surfclam EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Preferred habitat includes sandy bottom areas. Surfclams are not dependent on kelp forests. Therefore, the NRC staff concludes that loss of kelp at Seabrook is not likely to adversely affect EFH for juvenile and adult Atlantic surfclams during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic surfclams prior to and during operations. However, NextEra monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect juvenile and adult Atlantic surfclams for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
Forage species are not likely to be adversely affected.
Monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away.
D-1.3.3.8 Haddock (Melanogrammus aeglefinus) (Juvenile)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile haddock EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed haddock in greater than 10 percent of trawling samples and less than 1 percent of gill net samples (Table D-1-2).
Species Description. Haddock are demersal gadids that inhabit both sides of the North Atlantic Ocean (Brodziak 2005). In the northwest Atlantic, haddock can be found from Cape May, NJ to the Strait of Belle Isle, Newfoundland (Klein-MacPhee 2002). In the U.S., two stocks of haddock occurone in the Gulf of Maine and one in Georges Bank (Brodziak 2005).
Larvae metamorphose into juveniles once they reach 0.8 to 1.2 in. (2 to 3 cm) (Fahay 1983).
For the first 3 to 5 months, small juveniles live and feed in the upper part of the water column.
Juveniles visit the seafloor in search of prey and remain on the ocean bottom once suitable habitat is located (Brodziak 2005; Klein-MacPhee 2002). Preferred benthic habitat includes include gravel, pebbles, clay, and smooth hard sand (Klein-MacPhee 2002), which is more abundant in Georges Bank than in the Gulf of Maine (Broziak 2005).
While inhabiting the upper part of the water column, small juveniles feed on phytoplankton, small crustaceans (primarily copepods and euphausiids), and invertebrate eggs (Brodziak 2005; Kane 1984). Benthic prey for larger juveniles include polychaetes, echinoderms, small decapods, and small fishes (Bowman et al. 1987; Broziak 2005).
Status of the Fishery. By the early 1990s, haddock experienced several decades of declining spawning biomass and recruitment (Brodziak 2005). Some considered the stock to be near collapse (Brodziak 2005). Since 1994, fishery management measures have helped to reduce fishing mortality (Brodziak 2005). NEFMC currently manages haddock under the northeast multispecies FMP. In 2009, NEFMC considered haddock overfished (NMFS 2010b).
47 Entrainment and Impingement. Although NMFS has not designated EFH for haddock eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles. Entrainment of haddock eggs varied from 0 in several years to 7.4 million in 1992 (NAI 2010). Annual average entrainment of haddock eggs was 0.4 million per year from 1990 through 2009 (Table D-1-4). Entrainment of 100,000 haddock larvae occurred in 1992 and 2005. NAI (2010) did not observe entrainment of haddock larvae in any other year from 1990 through 2009 (Table D-1-5). Haddock eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of haddock varied from 0 in several years to 397 in 1996 (NAI 2010). Annual average impingement was 28 fish per year from 1994 through 2009 (Table D-1-6). Haddock comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for haddock compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile haddock. Young juvenile haddock remain pelagic for 3 to 5 months, at which point they travel to the seafloor in search of food and remain within this benthic habitat.
A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile haddock feed on a variety of organisms, including phytoplankton, copepods, euphausiids, invertebrate eggs, polychaetes, echinoderms, small decapods, and small fishes (Bowman et al. 1987; Broziak 2005; Kane 1984). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of phytoplankton, zooplankton (including copepods), invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for juvenile haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile haddock do not use kelp habitats (Broziak 2005).
Therefore, loss of kelp due to Seabrook operations are not likely to adversely affect EFH for juvenile haddock.
Combined Impacts (Monitoring Data). Seabrook monitoring data does not provide data specific to the abundance of juvenile haddock prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect juvenile haddock or its habitat for the following reasons:
Impingement and entrainment are relatively low for haddock.
The thermal plume rises quickly to surface waters Forage species are not likely to be adversely affected by Seabrook operations.
Preferred habitat does not include kelp or shellfish beds.
48 D-1.3.3.9 Monkfish/Goosefish (Lophius americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult goosefish EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed goosefish eggs in less than 1 percent of ichthyoplankton tows, goosefish larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in 1 to 10 percent of trawling samples, and juveniles and adults in less than 1 percent of gill net samples (Table D-1-2).
Species Description. Goosefish are large, slow-growing benthic fish (Steimle et al. 1999a). In the Gulf of Maine, goosefish larger than 7.9 in. (20 cm) move offshore in the winter and spring to avoid cold coastal conditions, whereas smaller goosefish migrate offshore in the fall (Hartley 1995, cited in Steimle et al. 1999a).
Adults mature at approximately 4 years for males and 5 years for females (Almeida et al. 1995).
Spawning occurs from May through June in the Gulf of Maine (Hartley 1995, cited in Steimle et al. 1999a). Females shed relatively large eggs (0.6 to 0.7 in. (1.6 to 1.8 mm)) within buoyant, ribbon-like, non-adhesive, mucoid veils or rafts (Martin and Drewry 1978, cited in Steimle et al. 1999a). Egg veils float on the surface (Steimle et al. 1999a). Larvae are also pelagic.
Juveniles settle to the bottom of the ocean and remain demersal as adults. Young juveniles often hide from predators within algae covered rocks. Adults prefer open sandy bottoms where they can partially bury themselves and then ambush prey (Steimle et al. 1999a).
Prey varies depending on life stage. Larval prey includes zooplankton, such as copepods, crustacean larvae, and chaetognaths (Bigelow and Schroeder 1953). Small juveniles eat pelagic fish but switch to invertebrates, especially crustaceans, once settling on the seafloor (Steimle et al. 1999a). Larger juveniles and adults consume more fish than invertebrates (Armstrong et al. 1996). NEFSC analyzed the stomach contents of goosefish and primary prey included crustaceans, squid, and fish. Common fish prey include spiny dogfish (Squalus acanthias), skates (Raja spp.), eels, sand lance, herring, Atlantic menhaden (Brevoortia tyrannus), smelt (Osmeridae), mackerel (Scomber spp.), weakfish (Cynoscion regalis), cunner, tautog (Tautoga onitis), black sea bass (Centropristis striata),
butterfish, pufferfish, sculpins, sea raven (Hemitripterus americanus), searobins (Prionotus spp.), silver hake (Merluccius bilinearis), Atlantic tomcod (Microgadus tomcod), cod, haddock, hake (Urophycis spp.), witch and other flounders, and other goosefish (Bigelow and Schroeder 1953; Steimle et al. 1999a).
Status of the Fishery. In U.S. waters, NEFMC manages goosefish under the northeast multispecies FMP. In 2009, NMFS (2010b) reported that goosefish was not overfished.
Entrainment and Impingement. Entrainment of goosefish eggs varied from 0 in most years to 0.9 million in 1998 and 2000 (NAI 2010). Annual average entrainment of goosefish eggs was 0.1 million per year from 1990 through 2009 (Table D-1-4). Entrainment of goosefish larvae varied from 0 in most years to 2 million in 2000 (NAI 2010). Annual average entrainment of goosefish larvae was 0.1 million per year from 1990 through 2009 (Table D-1-5). Goosefish eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of goosefish varied from 0 in several years to 59 in 2001 (NAI 2010). Annual average impingement was 10 fish per year from 1994 through 2009 (Table D-1-6). Goosefish comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for goosefish compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
49 Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult goosefish. Seabrooks thermal discharge may slightly reduce available habitat to goosefish eggs and larvae.
Goosefish eggs and larvae are pelagic (Steimle et al. 1999a). Scott and Scott (1988, cited in Steimle et al. 1999a) reported 63 to 64° F (17 to 18° C) as the upper temperature limit for normal egg hatching. NEFSC MARMAP ichthyoplankton surveys collected most larvae from 52 to 59° F (11 to 15° C), but as high as 68 ° F (20° C) (Steimle et al. 1999a). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface could exceed the typical range of temperatures that goosefish eggs and larvae inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991).
Adult and juvenile goosefish are primarily benthic, meaning that they spend most of the time residing near the seafloor (Steimle et al. 1999a). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
Because the thermal plume could exceed the typical range of temperatures that larvae inhabit, the NRC staff concludes that the heated thermal effluent may have minimal adverse effects on Atlantic cod larvae. Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Goosefish feed on a variety of organisms, including zooplankton, invertebrates, and several fish species (Bigelow and Schroeder 1953; Steimle et al. 1999a).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton, invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Newly settled juveniles may hide within algae covered rocks (Steimle et al. 1999a). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began (NAI 2010).
Therefore, Seabrook operations may have minimal adverse effects on juvenile goosefish habitat. Effects would likely be minimal because juvenile goosefish would likely inhabit algae (other than kelp) that have not declined near Seabrook (NAI 2001).
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the density or abundance of goosefish eggs, larvae, juveniles, or adults prior to and during operations (NAI 2010).
Conclusion. Because the thermal plume could exceed the typical range of temperatures that eggs and larvae inhabit, and because juveniles may use algal habitats that have declined near Seabrook since operations began, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for goosefish eggs, larvae, and juveniles near Seabrook. Based on the above analysis, Seabrook is not likely to affect goosefish adults or its habitat because entrainment and impingement are relatively low compared to other species at Seabrook, the thermal plume rises quickly to surface waters, and forage species are not likely to be adversely affected.
50 D-1.3.3.10 Ocean pout (Macrozoarces americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult ocean pout EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed ocean pout larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, and juveniles and adults in less than 1 percent of gill net samples (Table D-1-2).
Species Description. Ocean pout inhabit the Atlantic continental shelf of North America and are common off the coast of southern New England (Chang 1990). Ocean pout are benthic and use both open and rough habitats (Steimle et al. 1999b).
In the fall, ocean pout spawn in rock crevices, man-made artifacts, or other protected areas where they lay eggs in nests (Steimle et al. 1999b). Eggs remain demersal, and nests are guarded by one or both parents (Bigelow and Schroeder 1953). Once hatched, larvae generally remain near or at the bottom of the seafloor (Bigelow and Schroeder 1953). Juveniles and adults are also demersal. Bigelow and Schroeder (1953) reported that juveniles occur in shallow coastal waters around rocks and attached algae and in rivers with saline bottom waters in the Gulf of Maine. Juveniles may also use scallop or quahog shells for cover. Adults use a variety of habitats including rocky crevices, soft bottom habitats, gravel covered areas, and shellfish beds (Steimle et al. 1999b).
Ocean pout prey on benthic organisms in soft sandy bottom habitats either by sorting mouthfuls of sediments for infaunal species (MacDonald 1983) or by ambushing prey (Auster et al. 1995).
Sedberry (1983, cited in Steimle et al. 1999b) found that juveniles feed on gammarid amphipods and polychaetes. Adults prey on a variety of benthic invertebrates, such as polychaetes, mollusks, crustaceans, and echinoderms (see review in Steimle et al. 1999b). Langton and Watling (1990 in Steimle et al. 1999b) reported that ocean pout primarily eat bivalve mollusks off the coast of southern Maine. Ocean pout and American plaice may compete for prey in the Gulf of Maine (MacDonald and Green 1986). Predators of juvenile ocean pout include squid, spiny dogfish, sea raven, cod, barndoor skate (Raja laevis), harbor seals, and cormorants (Steimle et al. 1999).
Status of the Fishery. NEFMC currently manages ocean pout as two stocks, one in northern Gulf of Maine and one south of this area (Wigley 1998). In 2009, NEFMC reported that ocean pout was not overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not observe entrainment of ocean pout eggs from 1990 through 2009 (Table D-1-4). Seabrook entrained less than 10,000 ocean pout larvae in 2003 (NAI 2010). NAI (2010) did not observe entrainment of ocean pout larvae during any other year from 1990 through 2009 (Table D-1-5).
Impingement of ocean pout varied from 0 in several years to 21 in 2001 (NAI 2010). Annual average impingement was four fish per year from 1994 through 2009 (Table D-1-6). Ocean pout comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for ocean pout compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to eggs, larvae, juvenile, or adult ocean pout. Ocean pout are primarily benthic (Steimle et al. 1999b), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased
51 temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for all life stages of ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Ocean pout feed on a variety of invertebrates, including gammarid amphipods, polychaetes, mollusks, echinoderms, and other crustaceans (Langton and Watling 1990, cited in Steimle et al. 1999b; Steimle et al. 1999b). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton and benthic invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juveniles may use habitats with algae, and both juveniles and adults may use shellfish beds (Bigelow and Schroeder 1953; Steimle et al. 1999b). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but juvenile ocean pout use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile ocean pout and its habitat.
Because Seabrook operations have not adversely affected the density or species diversity of benthic invertebrates, including shellfish beds, Seabrook operations are not likely to adversely affect adult ocean pout habitat.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of ocean pout eggs, larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Icthoplankton trawls did not capture ocean pout eggs and captured larvae in less than 10 percent of all samples (Table D-1-2). Monitoring data indicate that the abundance of juveniles and adult increased or remained the same at both nearfield and farfield sampling sites (Table D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for ocean pout.
Conclusion. Because juveniles may use algal habitats and other complex habitats, and because the density of several kelp species has declined near Seabrook since operations began, NRC staff concludes that Seabrook may have minimal adverse effects on juvenile ocean pout and its habitat near Seabrook. Based on the above analysis, Seabrook is not likely to affect EFH for ocean pout eggs, larvae, or adults for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Monitoring data indicate that the abundance trends for ocean pout were similar at nearfield and farfield sties.
52 D-1.3.3.11 Pollock (Pollachius virens) (Juvenile)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile pollock EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed pollock in greater than 10 percent of trawling samples, in greater than 10 percent of gill net samples, and in 1 to 10 percent of seine pull samples (Table D-1-2) (NAI 2010).
Species Description. Pollock are gadoids that occur on both sides of the North Atlantic (Cargnelli et al. 1999). Within the western Atlantic, pollock are relatively common within the Gulf of Maine (Cargnelli et al. 1999).
Juveniles migrate to and from offshore waters to nearshore habitats, such as the rocky subtidal and intertidal, until they remain offshore as adults (Cargnelli et al. 1999). Juveniles use a wide variety of habitats, including sand, mud, or rocky bottom and vegetation (Hardy 1978, cited in Cargnelli et al. 1999). NEFSC trawl surveys captured juveniles at temperatures ranging from 34 to 64° F (1 to 18° C).
Juveniles consume crustaceans, such as euphausiids and mollusks, and fish (Bowman and Michaels 1984). Ojeda and
Dearborn (1991) determined that fish,
such as young Atlantic herring, dominated the diet of subtidal juveniles in the Gulf of Maine.
Status of the Fishery. NEFMC manages pollock as a single unit under the northeast multispecies FMP. In 2009, NEFMC determined that pollock was not overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for pollock eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles. Entrainment of pollock eggs varied from 0 in 1990 to 8.5 million in 2007 (NAI 2010). Annual average entrainment of pollock eggs was 1.4 million per year from 1990 through 2009 (Table D-1-4).
Entrainment of pollock larvae varied from 0 in most years to 0.8 million in 2007 (NAI 2010).
Annual average entrainment of pollock larvae was 0.2 million per year from 1990 through 2009 (Table D-1-5). Pollock eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of pollock varied from 72 in 2006 to 11,392 in 1999 (NAI 2010). Annual average impingement was 1,273 fish per year from 1994 through 2009 (Table D-1-6). Pollock was the sixth most commonly impinged fish species and comprised 6.1 percent of all impinged fish at Seabrook from 1994 through 2009.
Entrainment of pollock is small compared to other species entrained at Seabrook. However, pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Therefore, the NRC staff concludes that impingement may have minimal adverse effects on EFH for pollock during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captures in the Seabrook cooling system would be a very small proportion of available habitat for pollock juveniles and adults.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile pollock. Juvenile pollock use primarily benthic habitats in the nearshore, such as rocky subtidal or intertidal area, although some may also travel throughout the water column (Cargnelli et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
From May through June and October through December, when pollock density was highest in Seabrook monitoring studies, the surface temperature reached 57.7° F (14.3° C) near Seabrook (NAI 2010). NEFSC trawl surveys captured juveniles at temperatures ranging from 34 to 64° F (1 to 18° C). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the
53 surface would be within the typical range of temperatures that juvenile pollock inhabit. The NRC staff concludes that the increased temperatures at Seabrook are not likely to adversely affect EFH for juvenile pollock during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the findings that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for juvenile pollock.
Loss of Forage Species. Juveniles consume crustaceans, such as euphausiids and mollusks, and fish, such as Atlantic herring (Bowman and Michaels 1984; Ojeda and Dearborn 1991).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance and density of zooplankton, benthic invertebrates, and most fish species (NAI 2010). Entrainment and impingement were relatively low for Atlantic herring, primary fish prey for juvenile pollock, compared to other species at Seabrook. Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect pollock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juveniles use a wide variety of habitats, including sand, mud, or rocky bottom and vegetation (Hardy 1978, cited in Cargnelli et al. 1999). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but NextEra observed similar trends for the density of benthic invertebrates at the nearfield and farfield sampling sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but juvenile pollock use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile pollock habitat.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of juvenile pollock prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away and within Hampton-Seabrook Estuary (NAI 2010). Monitoring data indicate that the abundance of juvenile pollock decreased or remained the same at both nearfield and farfield sampling sites (Tables D-1-10 and D-1-11). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for juvenile pollock.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for juvenile pollock because juveniles may use algal habitats that have declined near Seabrook since operations began, and pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Impacts would likely be minimal for the following reasons:
Pollock are not commonly entrained in the Seabrook cooling system.
The thermal plume rises quickly to the surface.
The temperature range within the thermal plume at the surface would be within the typical range for juvenile pollock.
Forage species are not likely adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
54 D-1.3.3.12 Red hake (Urophycis chuss) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult red hake EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Urophycis spp. (mostly red and white (U. tenuis) hake and to a lesser extent spotted hake (U. regia)) egg and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in 1 to 10 percent of gill net samples, and in more than 10 percent of seine pull samples (Table D-1-2).
Species Description. Red hake are demersal fish that occur along the U.S. and Canadian costs from North Carolina to Southern Newfoundland (Sosebee 1998). Red hake migrate seasonally to various depths to inhabit waters with relatively consistent temperaturesthey migrate to waters deeper than 328 ft (100 m) in the fall and waters less than 328 ft (100 m) in warmer months (Steimle et al. 1999c).
Southern Gulf of Maine is not a common spawning ground for red hake (Steimle et al. 1999c).
Eggs are buoyant and float near the surface (Steimle et al. 1999c). Larvae are also pelagic and inhabit the upper water column. NEFSC MARMAP ichthyoplankton surveys collected larvae at temperatures ranging from 46 to 73° F (8 to 23° C) (Steimle et al. 1999c). Surveys indicate that larvae are more abundant in the Middle Atlantic Bight than the Gulf of Maine (Steimle et al. 1999c). Juveniles remain pelagic for approximately 2 months before they settle to the sea floor. Bottom trawl surveys captured juveniles in waters up to 72° F (22° C) (Steimle et al. 1999c). Benthic habitat structure for sheltersuch as sea scallop shells, Atlantic surf clams, seabed depressions, or other structureis important habitat for juveniles (Steiner et al. 1982).
Adult red hake commonly inhabit areas with soft sediments bottoms that contain shellfish beds or depressions as well as natural and artificial reefs (Steimle et al. 1999c).
Prey varies by life stage. Larvae consume mainly copepods and other microcrustaceans (Steimle et al. 1999c). Juvenile red hake consume small benthic and pelagic crustaceans, such as larval and small decapod shrimp and crabs, mysids, euphausiids, and amphipods (Steimle et al. 1999c). Similar to juveniles, adults consume crustaceans but also prey on a variety of demersal and pelagic fish and squid.
Status of the Fishery. NEFMC manages the red hake fishery under the northeast multispecies FMP. In 2009, NEFMC did not consider the red hake fishery overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of red, white, and spotted hake at Seabrook was recorded under a single category for Urophycis spp. (NAI 2010). Entrainment of hake eggs varied from 0.6 million in 1994 to 213.2 million in 1996 (NextEra 2010a). Annual average entrainment of hake eggs was 45.7 million per year from 1990 through 2009 (Table D-1-4).
Hake was the fourth most commonly entrained taxa, comprising 5.1 percent of all entrained fish eggs at Seabrook from 1990 through 2009.
Entrainment of hake larvae varied from 0 in most years to 29.8 million in 2000 (NAI 2010).
Annual average entrainment of hake larvae was 2.8 million per year from 1990 through 2009 (Table D-1-5). Hake larvae comprised 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of red hake varied from 1 in 1994 to 1,478 in 1996 (NAI 2010). Annual average impingement was 509 fish per year from 1994 through 2009 (Table D-1-6). For hakes, which included red hake, white hake, and spotted hake, impingement varied from 4 in 1998 to 3,216 in 2008 (NAI 2010). Annual average impingement was 866 fish per year from 1994 through 2009 (Table D-1-6). The red hake and hake categories comprised 6.5 percent of all impinged fish at Seabrook from 1994 through 2009.
55 Because entrainment and impingement of hake were relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all life stages of red hake.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to red hake. Larvae and young juveniles inhabit pelagic waters up to 72 to 73° F (22 to 23° C) (Steimle et al. 1999c). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface would be within the typical range of temperatures that larvae and young juveniles inhabit. Older juvenile and adult red hake are benthic (Steimle et al. 1999c). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). The NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
This conclusion is based on the fact that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for larvae and young juvenile red hake.
Loss of Forage Species. Red hake consume a variety of prey items, including copepods, shrimp, crabs, euphausiids, amphipods, and other crustaceans, and a variety of demersal and pelagic fish and squid (Steimle et al. 1999c). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult red hake commonly use shellfish bed for shelter, as well as other natural and artificial structures. Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of hake eggs, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). This category included Urophycis spp. (mostly red and white hake) and to a lesser extent spotted hake (NAI 2010).
Monitoring data indicate that the abundance of hake eggs, juveniles, and adults decreased at both nearfield and farfield sampling sites (Tables D-1-8 and D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for hake.
Conclusion. Based on the above analysis, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for red hake eggs, larvae, juvenile, and adults during the remainder of the facilitys operating license or during the proposed license renewal term because entrainment and impingement of hake were relatively common at Seabrook. Impacts would likely be minimal for the following reasons:
Thermal plume rises quickly to surface waters and is within the typical range of surface temperatures for larvae and young juveniles.
56 Forage species and shellfish beds are not likely to be adversely affected.
Monitoring data show similar trends in the abundance of red hake at nearfield and farfield sties prior to and during operations.
D-1.3.3.13 Scup (Stenotomus chrysops) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult scup EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed scup in 1 to 10 percent of trawling samples and less than 1 percent of gill net samples (Table D-1-2).
Species Description. Scup are demersal fish that primarily occur primarily along the U.S. coast from Massachusetts to South Carolina, and have been observed as far north as the Bay of Fundy (Steimle et al. 1999d). Scup migrate south of New Jersey during the winter.
During the summer and early fall, juveniles and adults inhabit larger estuaries and coastal areas. Baird (1873, cited in Steimle et al. 1999d) reported habitat for juveniles to include sand, silty-sand, shell, mud, mussel beds, and eelgrass (Zosteria marina). Adults exhibit schooling behavior and also use a variety of habitats, including open sandy bottom and structured habitats such as mussel beds, reefs, or rough bottom (Steimle et al. 1999d).
Juveniles prey on small crustaceans, such as amphipods, polychaetes, and copepods (Steimle et al. 1999d). Adults consume a variety of prey, including small zooplankton, polychaetes, mollusks, other crustaceans, small squid, vegetable detritus, insect larvae, hydroids, sand dollars, and small fish (Bigelow and Schroeder 1953; Steimle et al. 1999d). Predators of scup include a variety of fish and sharks, such as bluefish (Pomatomus saltatrix), Atlantic halibut, cod, striped bass (Morone saxitilus), weakfish, goosefish, silver hake, and other coastal fish predators (see review in Steimle et al. 1999d).
Status of the Fishery. MAFMC manages the scup fishery under the summer flounder, scup, and black sea bass FMP. In 2009, MAFMC did not consider the scup fishery overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for scup eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults.
NAI (2010) did not observe scup eggs or larvae in entrainment studies from 1990 through 2009.
Impingement of scup varied from 0 in multiple years to 21 in 2005 (NAI 2010). Annual average impingement was seven fish per year from 1994 through 2009 (Table D-1-6). Scup comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because NAI (2010) did not observe scup entrainment, and because impingement is small compared to other species entrained at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult scup. Juvenile and adult scup are primarily benthic (Steimle et al. 1999d). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Scup consume a variety of prey including zooplankton, amphipods, polychaetes, copepods, mollusks, other crustaceans, small squid, vegetable detritus, insect larvae, hydroids, sand dollars, and small fish (Bigelow and Schroeder 1953; Steimle et
57 al. 1999d). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton, benthic invertebrates, and most fish species (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult scup use a variety of habitats, including open areas and areas with structure such as mussel beds and eelgrass (Zosteria marina)
(Steimle et al. 1999d). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because scup inhabit a wide variety of habitats and kelp are not a primary or preferred habitat, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of juvenile or adult scup prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for juvenile or adult scup for the following reasons:
Impingement and entrainment are relatively low for scup.
The thermal plume quickly rises to the surface.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Scup use a wide variety of habitats other than kelp.
D-1.3.3.14 Summer flounder (Paralicthys dentatus) (Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated adult summer flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed summer flounder in less than 1 percent of trawling samples (Table D-1-2).
Species Description. Summer flounder are benthic fish that occurs from Nova Scotia to Florida (Packer et al. 1999). Adult summer flounder migrate seasonally, whereby summer flounder normally inhabit shallow coastal and estuarine waters during summer and remain offshore during the fall and winter (Lux and Nichy 1981, cited in Packer et al. 1999; Packer et al. 1999).
Adults prefer sandy habitats. Lascara (1981, cited in Packer et al. 1999) showed that adults remain along the vegetative perimeter of eelgrass patches and capture prey that move from within the grass. Adult summer flounder are opportunistic feeders and prey upon a variety of fish and crustaceans (Bigelow and Schroeder 1953; Packer et al. 1999). Common prey items include windowpane, winter flounder, northern pipefish, Atlantic menhaden, bay anchovy, red hake, silver hake, scup, Atlantic silverside, American sand lance, bluefish, weakfish, mummichog, rock crabs, squids, shrimps, small bivalve and gastropod mollusks, small crustaceans, marine worms, and sand dollars (Packer et al. 1999). Predators of summer flounder include large sharks, rays, and goosefish.
Status of the Fishery. MAFMC manages the summer flounder fishery under the summer flounder, scup, and black sea bass FMP. In 2009, MAFMC did not consider the summer flounder fishery overfished (NMFS 2010b).
58 Entrainment and Impingement. Although NMFS has not designated EFH for summer flounder eggs and larvae, entrainment and impingement can adversely affect recruitment of adults.
NAI (2010) did not observe summer flounder eggs in entrainment studies from 1990 through 2009. NAI (2010) observed entrainment of less than 100,000 summer flounder larvae during 3 years from 1990 through 2009 (Table D-1-5). NAI (2010) observed three impinged fish in 1994 and four impinged fish in 2006 (Table D-1-6).
Because entrainment and impingement of summer flounder were relatively rare at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to adult summer flounder. Summer flounder are primarily benthic (Packer et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Adult summer flounder are opportunistic feeders and prey upon a variety of fish and crustaceans (Bigelow and Schroeder 1953; Packer et al. 1999). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of benthic invertebrates and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect summer flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Adult summer flounder use open sandy areas and patches of eelgrass for feeding (Packer et al. 1999). Near the intake and discharge structures, it is reasonable to assume that patches of kelp may play a similar ecological role as eelgrass for summer flounder to ambush predators. Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations because operations began (NAI 2010). Because summer flounder use patches of vegetation to ambush predators, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook may have minimal adverse effects on EFH for adult summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since adult summer flounder inhabit a variety of habitats and vegetation other than kelp.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of adult summer flounder prior to and during operations (NAI 2010).
Conclusion. Because summer flounder may use algal habitats that have declined near Seabrook since operations began, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for summer flounder near Seabrook. Impacts would likely be minimal because impingement and entrainment are relatively rare for summer flounder, the thermal plume quickly rises to the surface, and forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
59 D-1.3.3.15 Whiting/Silver hake (Merluccius bilinearis) (All life stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult silver hake EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed silver hake egg and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in greater than 10 percent of gill net samples, and in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Silver hake are schooling gadids (Lock and Packer 2004). Two stocks occur in the western Atlantic Oceanone stock ranges from the Gulf of Maine to northern Georges Bank and the other stock ranges from southern Georges Bank to Cape Hatteras.
Coastal Gulf of Maine is a major spawning area for silver hake. Brodziak (2001) reported peak spawning from July through August in the northern stock of silver hake. Eggs and newly hatched larvae are pelagic (Lock and Packer 2004). After 3 to 5 months, larvae descend towards benthic habitats (Jeffrey and Taggart 2000). NEFSC MARMAP ichthyoplankton surveys captured eggs at temperatures ranging from 41 to 73° F (5 to 23 ° C) and larvae from 41 to 66° F (5 to 19° C) (Lock and Packer 2004).
Juvenile and adult silver hake make seasonal migrations, moving offshore as water temperatures decline in the fall and returning to shallow waters in spring and summer to spawn.
Juvenile and adult silver hake are primarily benthic but will move up into the water column for feeding (Koeller et al. 1989; Lock and Packer 2004). Lock and Packer (2004) consider silver hake use and preference of various bottom habitats a future research need. NEFSC bottom trawl surveys captured juveniles at temperatures ranging from 36 to 70° F (2 to 21° C) and adults from 36 to 63° F (2 to 17° C) (Lock and Packer 2004).
Silver hake are an important predator species due to their dominant biomass and high prey consumption (Bowman 1984; Garrison and Link 2000). Silver hake diet varies with life stage, size, sex, season, migration, spawning, and age. Larvae prey on plankton such as copepod larvae and younger copepodites (Lock and Packer 2004). Juveniles generally consume euphausiids, shrimp, amphipods, and decapods (Bowman 1984). Adults and older juveniles mainly prey on schooling fish, such as young herring, mackerel, menhaden, alewives, sand lance, or silversides, although crustaceans and squids are also consumed (Bowman 1984; Garrison and Link 2000; Lock and Packer 2004). Predators include offshore, silver, white, red, and spotted hakes and to a lesser extent demersal gadids, pelagic fish species, and squids (Lock and Packer 2004).
Status of the Fishery. NEFMC manages the silver hake fishery. In 2009, NEFMC did not consider the silver hake fishery overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of silver hake eggs varied from 0.6 million in 1991 to 341.4 million in 2002 (NAI 2010). Annual average entrainment of silver hake eggs was 81.1 million per year from 1990 through 2009 (Table D-1-4). Silver hake was the third most commonly entrained egg species, comprising 9 percent of all entrained fish eggs at Seabrook from 1990 through 2009.
Entrainment of silver hake larvae varied from 0 in several years to 69 million in 1997 (NAI 2010).
Annual average entrainment of silver hake larvae was 8.1 million per year from 1990 through 2009 (Table D-1-5). Silver hake larvae was the ninth most commonly entrained larval species, comprising 3 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of silver hake varied from 0 in 1994 to 1,177 in 2002 (NAI 2010). Annual average impingement was 167 fish per year from 1994 through 2009 (Table D-1-6). Silver hake comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
60 Because entrainment of silver hake was relatively common at Seabrook, the NRC staff concludes that entrainment may have minimal adverse effects on EFH for silver hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Effects would likely be minimal since the amount of water (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for silver hake eggs and larvae.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to silver hake. NEFSC MARMAP ichthyoplankton surveys captured eggs at temperatures ranging from 41 to 73° F (5 to 23° C) and larvae from 41 to 66° F (5 to 19° C)
(Lock and Packer 2004). Juveniles and adults are primarily benthic but may move into the water column for feeding (Lock and Packer 2004). NEFSC bottom trawl surveys captured juveniles at temperatures ranging from 36 to 70° F (2 to 21° C) and adults from 36 to 63° F (2 to 17° C) (Lock and Packer 2004). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface would be within the typical range of temperatures that eggs and juveniles inhabit. However, the thermal plume may exceed the typical range of temperatures that larvae and adults inhabit. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). The NRC staff concludes that the heated thermal effluent from Seabrook is not likely to adversely affect EFH for eggs and juveniles during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the fact that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for eggs and juvenile silver hake. Because the thermal plume could exceed the typical range of temperatures that larvae and adults inhabit, the NRC staff concludes that the heated thermal effluent may adversely affect EFH for silver hake larvae and adults.
Loss of Forage Species. Silver hake consume a variety of prey, including copepod larvae, copepodites, euphausiids, shrimp, amphipods, decapods, and other crustaceans and schooling fish (e.g., young herring, mackerel, menhaden, alewives, sand lance, and silversides) and squids (Bowman 1984; Garrison and Link 2000; Lock and Packer 2004). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect silver hake EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Lock and Packer (2004) consider silver hake use and preference of various bottom habitats a future research need. A recent literature search by NRC staff did not indicate that silver hake prefer or heavily rely on shellfish beds or algae covered areas.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of silver hake eggs, larvae juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of silver hake eggs and larvae increased at both nearfield and farfield sampling sites (Table D-1-8). Gill net surveys indicate that abundance of silver hake within the water column decreased at both nearfield and farfield sites (Table D-1-10). Trawling surveys indicate that silver hake abundance near the sea floor decreased at the nearfield site but increased at the farfield sites (Table D-1-9). NAI (2010) did not report the statistical significance of this relationship. Because adult and juvenile silver hake decreased at nearfield
61 trawling sites but increased at farfield trawling sites, these monitoring results suggest that Seabrook operation may adversely affect bottom habitat for adult and juvenile silver hake.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may adversely affect EFH for silver hake eggs, larvae, juveniles, and adults for the following reasons:
Entrainment of silver hake eggs was relatively common at Seabrook.
The thermal plume could exceed the typical range of temperatures that larvae and adults inhabit.
Adult and juvenile silver hake decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
D-1.3.3.16 Windowpane flounder (Scopthalmus aquosus) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult windowpane flounder EFH near Seabrook (NMFS 2011b). NAI (2010) observed windowpane flounder in greater than 10 percent of trawling samples, less than 1 percent of gill net samples, and 1 to 10 percent of seine pull samples (Table D-1-2).
Species Description. Windowpane flounder inhabit estuaries, coastal waters, and oceans over the continental shelf along the Atlantic coast from the Gulf of Saint Lawrence to Florida. This species is most abundant from Georges Bank to Chesapeake Bay (Chang et al. 1999). North of Cape Cod Bay, windowpane flounder inhabit nearshore waters, and distribution patterns within estuaries is not well documented (Chang et al. 1999).
Windowpane flounder spawn in estuaries. Juveniles migrate from estuaries to coastal waters during autumn, and they overwinter offshore in deeper waters. Adults remain offshore throughout the year but inhabit nearshore waters in spring and autumn (Chang et al. 1999).
Langton et al. (1994) reported that adult windowpane occur primarily on sandy or muddy substrates in the Gulf of Maine.
Juvenile and adult windowpane flounder have similar food sources, including small crustaceans (especially shrimp) and fish larvae of hakes and tomcod. Predators include spiny dogfish, thorny skate (Amblyraja radiata), goosefish, Atlantic cod, black sea bass (Centropristis striata),
weakfish (Cynoscion regalis), and summer flounder (Chang et al. 1999).
Status of the Fishery. The NEFMC manages windowpane flounder under the northeast multispecies FMP. Windowpane flounder have never been widely directly targeted as a commercial species but have been harvested in mixed-species fisheries since the 1900s. In the 1950s, landings were estimated to be as high as 2.04 million lb (924 MT) per year (Hendrickson 2006). Landings ranged from 1.1 to 2.0 million lb (500 to 900 MT) per year from 1975 through 1981, increased to a record high of 4.6 million lb (2,100 MT) in 1985, and they have since steadily declined (Hendrickson 2006). The windowpane stock structure has never been formally quantified, and windowpane bycatch and discards from other fisheries are unknown and may account for a significant portion of annual windowpane catch. Currently, NEFMC consider the New England and Mid-Atlantic stock overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for windowpane eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of windowpane eggs varied from 0.1 million in 1994 to 61.8 million in 2009 (NAI 2010). Annual average entrainment of windowpane eggs was 31.7 million per year from 1990 through 2009 (Table D-1-4). Windowpane was the eighth most commonly entrained egg species, comprising 3.5 percent of all entrained fish eggs at Seabrook.
62 Entrainment of windowpane larvae varied from 0.05 in 1991 to 6.5 million in 2002 (NAI 2010).
Annual average entrainment of windowpane larvae was 2.3 million per year from 1990 through 2009 (Table D-1-5). Windowpane larvae comprised less than 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of windowpane varied from 161 in 2001 to 4,749 in 2003 (NAI 2010). Annual average impingement was 1,297 fish per year from 1994 through 2009 (Table D-1-6).
Windowpane was the fifth most commonly impinged fish species, comprising 6.2 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of windowpane eggs and impingement of juveniles and adults was relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for windowpane during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all stages of windowpane.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult windowpane. Juvenile and adult windowpane are primarily benthic (Chang et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile or adult windowpane during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult windowpane flounder prey on small crustaceans (especially shrimp) and fish larvae of hakes and tomcod. NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton and invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for windowpane flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult windowpane flounder do not appear to use shellfish bed or algae for habitat. Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect windowpane EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of windowpane juveniles and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Trawling surveys indicate that windowpane flounder decreased at the nearfield site but increased at the farfield sites (Table D-1-9). However, the confidence intervals overlapped, suggesting that this relationship would not be statistically significant. NAI (2010) did not report whether or not the relationship was statistically significant. These monitoring results suggest that Seabrook operation is not likely to adversely affect EFH of adult and juvenile windowpane.
Conclusion. Because entrainment of windowpane eggs and impingement of juveniles and adults were relatively common at Seabrook, the NRC staff concludes that Seabrook operation may have minimal adverse effects on EFH for windowpane during the remainder of the facilitys operating license or during the proposed license renewal term. Impact would be minimal because the thermal plume quickly rises to the surface, forage species and shellfish beds are
63 not likely to be adversely affected by Seabrook operations, and monitoring data shows similar trends at nearfield and farfield sites.
D-1.3.3.17 Winter flounder (Pleuronectes americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult winter flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed winter flounder larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in 1 to 10 percent of gill net samples, and in more than 10 percent of seine pull samples (Table D-1-2).
Species Description. There are three stocks of winter flounder in the Atlanticthe Gulf of Maine, southern New England and the Middle Atlantic, and Georges Bank (Pereira et al. 1999).
In New England, winter flounder are common in inshore and nearshore waters (Pereira et al. 1999). Adult winter flounder are a small-mouthed, right-eyed flounder that grow to 23 in.
(58 cm) in total length and live up to 15 years (Pereira et al. 1999).
Adult winter flounder migrate inshore to bays and estuaries in the fall and early winter to spawn and may remain inshore year-round in areas where temperatures are 59° F (15° C) or lower and enough food is available (Pereira et al. 1999). Studies vary widely on the age of maturity of winter flounder. Generally, sexual maturity is dependent on size rather than age, and southern individuals reach spawning size more rapidly than northern fish. North of Cape Cod, OBrien et al. (1993) determined that the median age of maturity was 11.7 in. (29.7 cm) for females and 10.9 in. (27.6 cm) for males. In the Hampton-Seabrook area, winter flounder spawn in coastal waters from February through April. Females spawn at depths of 7 to 60 ft (2 to 79 m) over sandy substrates in inshore coves and inlets at salinities of 31 to 32.5 parts per thousand (ppt)
(Buckley 1989; Pereira et al. 1999). Eggs are demersal, stick to the substrate (such as gravel or algal fronds), and are most often found at salinities between 10 and 30 ppt (Buckley 1989; Crawford and Cary 1985). Larvae initially are planktonic but become increasingly benthic as they develop (Pereira et al. 1999). Juveniles and adults are completely benthic. Able et al.
(1989, cited in Pereira et al. 1999) reported that juveniles use macroalgae. Juveniles move seaward as they grow, remaining in estuaries for the first year (Buckley 1989; Grimes et al. 1989). Adult winter flounder tolerate salinities of 5 to 35 ppt and prefer waters temperatures of 32 to 77° F (0 to 25° C).
Winter flounder larvae feed on small invertebrates, invertebrate eggs, and phytoplankton (Buckley 1989; Pereira et al. 1999). Adults feed on benthic invertebrates such as polychaetes, cnidarians, mollusks, and hydrozoans. Adults and juveniles are an important food source for predatory fish such as the striped bass (Morone saxatilis), bluefish, goosefish, spiny dogfish, and other flounders, and birds such as the great cormorant (Phalacrocorax carbo), great blue heron (Ardea herodias), and osprey (Pandion haliaetus) (Buckley 1989).
Status of the Fishery. Winter flounder are highly abundant in estuarine and coastal waters and, therefore, are one of the most important species for commercial and recreational fisheries on the Atlantic coast (Buckley 1989). Winter flounder are, generally, commercially harvested using otter trawl, but the species is also a popular recreational fish. Commercial landings of winter flounder peaked in the 1980s throughout its range and declined through the early 2000s (Brown and Gabriel 1998; Pereira et al. 1999). Commercial landings reached a record low in 2005 at 2.98 million lb (1,350 MT) but have increased slightly since, with landings at 3.58 million lb (1,622 MT) in 2007 (NEFSC 2008).
The NEFMC manages the winter flounder in Federal waters under the northeast multispecies FMP. As of 2009, the NEFMC reported that the Gulf of Maine winter flounder stock is overfished (NOAA 2010).
64 Entrainment and Impingement. Entrainment of winter flounder eggs varied from 0 in most years to 1.05 million in 2008 (NAI 2010). Annual average entrainment of winter flounder eggs was 96,500 per year from 1990 through 2009 (Table D-1-4). Winter flounder eggs comprised less than 1 percent of the total fish eggs entrained at Seabrook from 1990 through 2009.
Entrainment of winter flounder larvae varied from 0 in 1994 to 34.8 million in 2004 (NAI 2010).
Annual average entrainment of winter flounder larvae was 9.2 million per year from 1990 through 2009 (Table D-1-5). Winter flounder larvae was the eighth most commonly entrained species, comprising 3.4 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of winter flounder varied from 102 in 2000 to 10,491 in 2003 (NAI 2010). Annual average impingement was 2,082 fish per year from 1994 through 2009 (Table D-1-6). Winter flounder was the third most commonly impinged fish species, comprising 10 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of winter flounder larvae and impingement of juveniles and adults were relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for winter flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all stages of winter flounder.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to eggs, larvae, juvenile, or adult winter flounder. Winter flounder are primarily benthic (Pereira et al. 1999.) A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for winter flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Winter flounder feed on phytoplankton, small invertebrates, invertebrate eggs, and benthic invertebrates such as polychaetes, cnidarians, mollusks, and hydrozoans. NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton and invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect winter flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Window flounder eggs may be deposited on macroalgae (Crawford and Carey 1985), but spawning occurs in estuaries and NAI (2010) did not observe winter flounder eggs in monitoring studies near Seabrook, likely due to its offshore location.
Able et al. (1989 in Pereira et al. 1999) reported that juveniles use macroalgae habitat, along with other types of habitats. Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began (NAI 2010). Because juvenile winter flounder may utilize macroalgae habitat, along with other types of aquatic vegetation, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook may have minimal adverse effects on juvenile winter flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of winter flounder larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and
65 discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of larvae decreased at both nearfield and farfield sampling sites (Table D-1-8). Trawling data for juveniles and adults indicated different trends at the nearfield and farfield sites (NAI 2010). At the nearfield site, the abundance of winter flounder significantly decreased over time from a mean CPUE of 5.5 prior to operations to 2.3 during operations (Table D-1-9). However, at both farfield sampling sites, the mean CPUE increased from 2.8 and 1.4 prior to operations, respectively, to 4.0 and 3.6 during operations. This increase was statistically significant at one of the farfield sites. Based on monitoring data, NRC concludes that Seabrook operation has adversely affected EFH for winter flounder because the abundance of winter flounder has decreased to a greater and observable extent near Seabrooks intake and discharge structures compared to 3 to 4 mi (5 to 8 km) away.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may adversely affect EFH for winter flounder larvae, juveniles, and adults for the following reasons:
Entrainment of winter flounder larvae and impingement of juveniles and adults were relatively common at Seabrook.
Juveniles may use algal habitats that have declined near Seabrook since operations began.
Ault and juvenile winter flounder abundance decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
D-1.3.3.18 Yellowtail flounder (Pleuronectes ferruginea) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult yellowtail flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed yellowtail flounder in greater than 10 percent of trawling samples, in less than 1 percent of gill net samples, and in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Yellowtail flounder occur along the U.S. and Canadian coasts from the Gulf of St. Lawrence, Labrador, and Newfoundland to the Chesapeake Bay (Bigelow and Schroeder 1953; Johnson et al. 1999). Juveniles and adults are asymmetrical benthic flatfish (Johnson et al. 1999). Preferred habitat includes areas covered in sand or sand-mud sediments where demersal prey inhabits (Bowering and Brodie 1991; Johnson et al. 1999).
Juvenile yellowtail flounder consume primarily polychaetes while adult yellowtail flounder consume primarily crustaceans, such as amphipods and sand dollars (Echinarachius parma)
(Johnson et al. 1999). Predators include spiny dogfish, winter skate, Atlantic cod, Atlantic halibut, fourspot flounder, goosefish, little skate, smooth skate, silver hake, bluefish, and sea raven (Johnson et al. 1999).
Status of the Fishery. Yellowtail first became commercial desirable in the 1930s and is currently a highly targeted fish (Johnson et al. 1999). In 2009, NEFMC considered yellowtail overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for yellowtail flounder eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of yellowtail flounder eggs varied from 0 in multiple years to 569.2 million in 1991 (NextEra 2010a). Annual average entrainment of yellowtail flounder eggs was 42.8 million per year from 1990 through 2009 (Table D-1-4). Yellowtail flounder eggs was the sixth most commonly entrained fish egg species, comprising 4.8 percent of the total fish eggs entrained at Seabrook from 1990 through 2009.
66 Entrainment of yellowtail flounder larvae varied from 0 in 1994 to 2.7 million in 2007 (NAI 2010).
Annual average entrainment of winter flounder larvae was 0.4 million per year from 1990 through 2009 (Table D-1-5). Yellowtail flounder larvae comprised less than 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of yellowtail flounder varied from 0 in several years to 1,149 in 1995 (NAI 2010).
Annual average impingement was 83 fish per year from 1994 through 2009 (Table D-1-6).
Yellowtail flounder comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of yellowtail flounder eggs was relatively common at Seabrook, the NRC staff concludes that entrainment may have minimal adverse effects on EFH for yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of weather (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for yellowtail flounder eggs.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult yellowtail flounder. Juvenile and adult yellowtail flounder are benthic flatfish (Johnson et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile yellowtail flounder consume primarily polychaetes while adult yellowtail flounder consume primarily crustaceans, such as amphipods and sand dollars (Johnson et al. 1999). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect yellowtail flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult yellowtail flounder do not commonly use kelp or shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect yellowtail flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of yellowtail flounder juveniles and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of juveniles and adults decreased at both nearfield and farfield sampling sites (Table D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for juvenile or adult yellowtail.
Conclusion. Because entrainment of yellowtail flounder eggs was relatively common at Seabrook, Seabrook operation may have minimal adverse effects on EFH for juvenile and adult yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Impacts would be minimal for the following reasons:
67 Impingement and entrainment are relatively low for yellowtail flounder.
The thermal plume quickly rises to the surface.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield sites.
D-1.3.3.19 Essential Fish Habitat Species Not Likely to Regularly Occur Near Seabrook The NMFS has designated EFH for eggs, larvae, juvenile and adult Atlantic halibut; adult bluefin tuna; larvae, juvenile, and adult redfish; and juvenile and adult longfin inshore squid and northern shortfin squid in the vicinity of Seabrook (NMFS 2011b). NAI (2010) never, rarely, or occasionally observed Atlantic halibut, bluefin tuna, redfish, northern shortfin squid, and longfin inshore squid during monitoring, entrainment, and impingement studies from the 1970s through 2009. For example, NAI (2010) rarely identified Atlantic halibut in trawling surveys and did not report Atlantic halibut in any other monitoring surveys or any impingement or entrainment studies. NAI (2010) occasionally identified redfish in trawling surveys and did not report redfish in other monitoring surveys or any impingement or entrainment studies. Bluefin tuna were not reported in any monitoring, entrainment, or impingement studies. Seabrook did not explicitly include longfin inshore squid and northern shortfin squid in its entrainment and impingement studies. However, field technicians did not recall any time that squid have been impinged at Seabrook (NRC 2011). Longfin inshore squid lay eggs on the seafloor and larvae are often found near the surface, whereas the intake structure is located in deeper water (Jacobson 1995). Northern shortfin squid eggs and larvae are pelagic, but primarily occur within the Gulf Stream (Hendrickson and Holmes 2004).
Bluefin tuna, longfin inshore squid, and northern shortfin squid are pelagic and, therefore, could encounter the thermal plume when passing by Seabrook. Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). NEFSC trawl data indicate that northern shortfin squid inhabit waters up to as 66° F (19° C), and longfin inshore squid inhabit waters up to as 79° F (26° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C),
the thermal plume near the surface could exceed the typical temperature range for northern shortfin squid but would be within the typical temperature range for longfin inshore squid.
Bluefin tuna have never been captured in any of NextEras monitoring study; therefore, the relatively small size of the thermal plume is not likely to adversely affect large amounts of EFH for bluefin tuna if any happen to pass by Seabrook. The thermal plume is not likely to adversely affect EFH for Atlantic halibut or redfish because both of these species are pelagic and the thermal plume rises quickly to the surface.
Bluefin tuna, longfin inshore squid, and northern shortfin squid are pelagic and, therefore, not likely to regularly inhabit benthic habitats such as kelp forest or shellfish beds. Redfish and Atlantic halibut may use kelp near Seabrook, along with other habitats that provide structure.
Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling sites since operations began (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but Atlantic halibut and redfish rarely or occasionally use habitat near Seabrook, the NRC staff concludes that Seabrook operations may have minimal adverse effects on Atlantic halibut and redfish.
Forage species for Atlantic halibut, bluefin tuna, redfish, longfin inshore squid, and northern shortfin squid are not likely to be adversely affected near Seabrook. Typical prey includes copepods, euphausiids, crabs, polychaetes, shrimp, and fish. NextEras monitoring studies 68 show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic halibut, bluefin tuna, redfish, longfin inshore squid, or northern shortfin squid during the remainder of the facilitys operating license or during the proposed license renewal term.
Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for northern shortfin squid because the thermal plume near the surface could exceed the typical temperature range for northern shortfin squid. Seabrook operations may have minimal adverse effects on EFH for redfish and Atlantic halibut because both species may use kelp beds near Seabrook. Seabrook operations are not likely to affect EFH for longfin inshore squid or bluefin tuna.
Cumulative Effects to Essential Fish Habitat This section addresses the direct and indirect effects of license renewal on EFH when added to the aggregate effects of other past, present, and reasonably foreseeable future actions. The geographic area considered in the cumulative aquatic resources analysis includes the vicinity of Seabrook, the offshore intake and discharge structures, the Hampton-Seabrook Estuary, and the rivers that drain into the Hampton-Seabrook Estuary.
Section 2.2.6.2 of the SEIS summarizes the condition of the Gulf of Maine and the Hampton-Seabrook Estuary and the history and factors that led to its current condition. The direct and indirect impacts from fishing are some of the most influential human activities on the Gulf of Maine ecosystem (Sosebee et al. 2006). Fishing has caused wide-scale changes in fish populations and food web dynamics within the Gulf of Maine (Sosebee et al. 2006; Steneck et al. 1994). In the Hampton-Seabrook Estuary, wetland habitat and water flow has been affected by human uses such as those listed below (Eberhardt and Burdick 2009):
harvesting salt marsh hay (Spartina patens) as feed for livestock in the 1700 and 1800s, digging ditches in an attempt to control mosquito populations in the early 1900s, and building roads, jetties, commercial buildings, and residential areas in the 1900s and 2000s.
The increased urbanization in the past 100 years has caused increased runoff and levels of pollutants within the Hampton-Seabrook Estuary (NHDES 2004). In the rivers connected to Hampton-Seabrook Estuary, dams block fish migrations and have resulted in the precipitous decline of anadromous fish that move to freshwater to spawn and to marine waters to grow and feed (Eberhardt and Burdick 2009).
Many natural and anthropogenic activities can influence the current and future EFH in the area surrounding Seabrook. Potential biological stressors include continued entrainment, impingement, and potential heat shock from Seabrook (if the license renewal is granted), and fishing mortality, climate change, energy development, and urbanization, as described below.
Fishing. Fishing has been a major influence on the population levels of commercially sought fish species in the Gulf of Maine (Sosebee et al. 2006). The Hampton-Seabrook Estuary and the Gulf of Maine support significant commercial and recreational fisheries for many of the fish and invertebrate species also affected by Seabrook operations. EPA (2002b) determined that 69 percent of all entrained and impinged fish species at Seabrook are commercially or recreationally fished. From 1990 through 2000, Atlantic cod comprised 33 percent of the catch in New Hampshire and 25 percent of the revenue. Other commercially important and EFH
69 species in New Hampshire include spiny dogfish shark, pollock, Atlantic herring, bluefin tuna, American plaice, white hake, yellowtail flounder, and shrimp. Recreationally fished species include American lobster, striped bass, summer flounder, Atlantic cod, scup, and bluefish (EPA 2002b). Federal, regional, and State agencies manage many of these fisheries, although the biomass of many fish stocks have not rebounded to pre-1960s levels (Sosebee 2006).
Indirect impacts from fishing include habitat alteration as well as indirect effects that propagate throughout the food web.
For these reasons, the NRC staff concludes that fishing pressure has the potential to continue to influence the aquatic ecosystem, especially food webs, and may continue to contribute to cumulative impacts on EFH.
Climate Change. The potential cumulative effects of climate change on the Gulf of Maine and Hampton-Seabrook Estuary could result in a variety of changes that would affect EFH. The environmental factors of significance identified by the U.S. Global Change Research Program (USGCRP) (2014) include temperature increases, coastal flooding, and sea level rise. From 1982 to 2006, sea surface temperatures in coastal waters of the Northeast warmed almost twice the global rate (USGCRP 2014). In the Gulf of Maine, sea surface temperature in 1999, 2002, and 2006 were the 4th, 5th, and 6th warmest years, respectively, on the record (Drinkwater et al. 2009). Projections from coarse-scale climate models coupled with finer-scale models suggest that spring sea surface temperatures in the Gulf of Maine may increase by about 2.2 °C (3.9 °F) in the 2080s under the high emission scenario (Frumhoff et al. 2007; NMFS 2011e).
Warming sea temperatures may influence the abundance and distribution of species, as well as earlier spawning times. Since 1968, species in the New England coastal waters have shifted their geographic distribution northward by up to 200 miles (USGCRP 2014). The USGCRP (2014) projects that lobster populations will decline and continue to shift northward in response to warming sea temperatures. Atlantic cod, which were subject to intense fishing pressure and other biological stressors, are likely to be adversely affected by the warmer temperatures since this species inhabits cold waters (USGCRP 2014). USGCRP (2009) projects that the Georges Bank Atlantic cod fishery is likely to be diminished by 2100. NMFS (2009) analyzed fish abundance data from 1968-2007 and determined that the range of several species of fish are moving northward or deeper, likely in response to warming sea temperatures.
Warmer temperatures can also lead to earlier spawning since spawning time is often correlated with a distinct temperature range. Seabrook monitoring studies showed a shift in blue mussel spawning times (NAI 2010). From 1996-2002, and select years from 2002-2009, the greatest blue mussel larval density occurred in mid-April, whereas the greatest blue mussel larval density occurred in late April in the 1970s, 1980s, and early 1990s. Furthermore, rising sea temperatures have been linked to marine-life diseases (USGCRP 2014). Increased disease outbreaks due to increase water temperatures can lead to increased mortality of marine life, which can then further change habitat and species relationships than ultimately affect the ecosystem.
Increased water temperatures from climate change may overlap with the impacts from Seabrooks cooling water system. For example, in the area near the discharge, the combined impacts of the thermal discharge and increase water temperature from climate change could push temperatures above the thermal thresholds of cold-water species (NMFS 2011e).
While there is great uncertainty, sea levels are expected to rise between 0.5 and 1 ft (0.15 to 0.3 m) by 2050 and by 1 to 4 ft (0.3 to 1.2 m) by the end of this century; sea level rise along the Northeast coast is expected to exceed the global rate due to local land subsidence and projected to rise 1.3 to 1.7 ft ( 0.4 to 0.5 m) by 2050 (USGCRP 2014). Sea level rise could result in dramatic effects to nearshore communities and EFH, including the reduction or 70 redistribution of kelp, eelgrass, and wetland communities. Aquatic vegetation is particularly susceptible to sea level rise because it is immobile and cannot move to shallower areas. In addition, most species grow within a relatively small range of water depth in order to receive sufficient light to photosynthesize.
The ocean absorbs nearly one-third of the carbon dioxide (CO2) released into the atmosphere (NMFS 2011d). As atmospheric CO2 increases, there is a concurrent increase in CO2 levels in the ocean (NMFS 2011d). Ocean acidification is the process by which CO2 is absorbed by the ocean, forming carbonic and carbolic acids that increase the acidity of ocean water. More acidic water can lead to a decrease in calcification (or a softening) of shells for bivalves (e.g., Atlantic sea scallops and Atlantic surf clams), decreases in growth, and increases in mortality in marine species (Nye 2010, USGCRP 2014). Ocean acidification is projected to continue due to the interaction between ocean water and atmospheric carbon dioxide concentrations (USGCRP 2014).
The extent and magnitude of climate change impacts to the aquatic resources of the Gulf of Maine and the Hampton-Seabrook Estuary are an important component of the cumulative assessment analyses and could be substantial.
Energy Development. As part of a technical workshop held by NOAA, Johnson et al. (2008) categorized the largest non-fishing impacts to coastal fishery habitats. Johnson et al. (2008) determined that the largest known and potential future impacts to marine habitats are primarily from the development of energy infrastructure, including petroleum exploration, production, and transportation; liquefied natural gas development; offshore wind development; and cables and pipelines in aquatic ecosystems.
Petroleum explorations and offshore wind development can result in habitat conversion and a loss of benthic habitat as developers dig, blast, or fill biologically productive areas. Petroleum and liquefied natural gas development can adversely affect water quality if there are oil spills or discharges of other contaminants during exploration-or transportation-related activities.
Underwater cables and pipelines may block fish and other aquatic organisms from migrating to various habitats (Johnson et al. 2008). Thus, energy development may contribute to future cumulative impacts in a variety of ways.
Urbanization. The area surrounding the Hampton-Seabrook Estuary experienced increased residential and commercial development in the 1900s, as the seaside town became a popular tourist destination (Eberhardt and Burdick 2009). At the beginning of the 21st century, moderate commercial and residential development surrounded the Hampton-Seabrook Estuary (NHNHB 2009). The town of Hamptons Master Plan calls for continued growth in the area to sustain its attractiveness for tourists (Hampton 2001).
Increased urbanization has led, and will likely continue to lead, to additional stressors on the Hampton-Seabrook Estuary. Runoff from developed and agricultural areas has increased the concentration of nutrients, bacteria, and other pollutants to the estuary. Sections of the Hampton-Seabrook Estuary are listed on New Hampshires 303(d) list as being impaired due to high concentrations of bacteria (NHDES 2004). NHDES (2004) also lists the estuary as impaired for fish and shellfish consumption due to polychlorinated biphenyl, dioxin, and mercury concentrations in fish tissue and lobster tomalley. Other activities that may affect marine aquatic resources in Hampton-Seabrook Estuary include periodic maintenance dredging, continued urbanization and development, and construction of new overwater or near-water structures (e.g., docks), and shoreline stabilization measures (e.g., sheet pile walls, rip-rap, or other hard structures).
71 Future threats to salt marshes in the Hampton-Seabrook Estuary include developmental activities that further hydrological alterations from filling wetlands or other physical changes that alter the flow of tidal waters (Johnson et al. 2008; NHNHB 2009). Increased nutrients and pollutants in storm runoff are also current threats to the health of this ecosystem (NHNHB 2009). The NRC staff concludes that the direct and indirect impacts from future urbanization are likely to contribute to cumulative impacts in the Hampton-Seabrook Estuary.
Conclusion. The direct impacts to fish populations, from fishing pressure and alterations of aquatic habitat within the Hampton-Seabrook watershed from past activities, have had a significant effect on aquatic resources in the geographic area near Seabrook. These aquatic ecosystems have been adversely affected, as evidenced by the low population numbers for several commercially sought fisheries, the change in food web dynamics, habitat alterations, and the blockage of fish passage within the Hampton-Seabrook watershed. The cumulative stress from the activities described above, spread across the geographic area of interest, depends on many factors that NRC staff cannot quantify but are likely to adversely affect EFH when all stresses on the aquatic communities are assessed cumulatively. Therefore, the NRC staff concludes that the cumulative impacts from the proposed license renewal and other past, present, and reasonably foreseeable projects may adversely affect the EFH of most species, especially Atlantic cod due to climate change.
Essential Fish Habitat Conservation Measures NextEra prepared a proposal for information collection (PIC) as a first step to comply with EPAs 2004 proposed Phase II rule of Section 316(b) of CWA (NAI and ARCADIS 2008). In this document, NextEra identified three types of mitigation that are now in place and reduce entrainment and impingement (NAI and ARCADIS 2008). First, the location of the intake structures is offshore in an area of reduced biological activity as compared to an inshore location. Second, the design of the intake structures includes velocity caps, which fish tend to avoid due to the changes in horizontal flow of water created by the velocity cap. Third, less water is pumped from the Gulf of Maine to Seabrook due to the offshore location, which provides cooler water than an inshore location (NAI and ARCADIS 2008).
The Seabrook intake structures also have behavioral and structural deterrents to minimize impingement and entrainment. For example, the intake structure design includes velocity caps, which fish tend to avoid due to the changes in horizontal flow of water created by the velocity cap. In addition, NextEra installed a seal deterrent system by adding vertical bars on intake structures to prevent seals from getting trapped and drowning (NextEra 2010c).
Additional Mitigation Measures Additional intake technologies that might mitigate cooling water intake effects and other efforts that could mitigate impacts to aquatic resources are described in the following sections. The first three potential mitigation measures, including wedgewire screens, grey water, and variable frequency drives were included in NextEras assessment of additional potential mitigation options when responding to EPA in support of its Phase II 316(b) Program (ARCADIS 2008).
The other potential mitigation measures were suggested in comments on the draft SEIS. In addition, in their comments on the draft SEIS, EPA, NMFS, and New Hampshire Department of Environmental Services (NHDES) recommended that NRC staff evaluate the environmental impacts of a cooling system alternative. In response to these comments, NRC evaluated a closed-cycle cooling system alternative in Chapter 8. Therefore, closed-cycle cooling is not addressed further in this chapter.
Wedgewire Screens 72 In some cases, the use of wedgewire screens has shown potential for decreasing entrainment and impingement at once-through power plants. Wedgewire screens may reduce entrainment and impingement by physical exclusion and exploiting hydrodynamic patterns (EPA 2004). Fish and other aquatic resources are physically excluded from the intake if the screens mesh is smaller than the size of the organism. Hydrodynamic exclusion occurs because the screens cylindrical configuration helps to create a low through-slot velocity that is quickly dissipated. In this situation, organisms can escape the flow field by swimming faster than the through-slot velocity and as the ambient currents assist organisms in bypassing the intake. Factors influencing the use and effectiveness of this technology include the screen size, the location, the configuration of the system relative to the intake, the intake flow rates, the presence and magnitude of a sweeping current that can move organisms past the screen into safe water, and the size of the organism present near the intake.
NextEra considered wedgewire screens to potentially reduce impingement and entrainment at Seabrook (ARCADIS 2008). The proposed screens would be located at offshore intakes, which would require modification of the velocity caps currently installed. Three screens would be installed on each of the three velocity caps for a total of nine screens. The screens would have 0.25 in (6.4 mm) openings. With this configuration, the anticipated through screen velocity would be 0.5 feet per second (fps). In addition to the screens and velocity cap modifications, NextEra would need to install an air burst system for cleaning the screens (ARCADIS 2008). All construction activities would occur underwater at approximately 60 ft (18 m) depth.
EPA (2004) describes three conditions for wedgewire screens to be effective: 1) the screen size is small enough to physically exclude organisms, 2) the through screen velocity is low, typically 0.5 fps or less, and 3) there is sufficient ambient currents to aid organisms in bypassing the intake structure and to remove other debris from the screen face. ARCADIS (2008) determined that the second condition could be meet at Seabrook. The third condition may not be met because the ambient currents near the intakes do not always parallel the longitudinal axis of the screens (ARCADIS 2008). The first condition cannot be met at Seabrook because the possibility of significant biofouling prevents the use of a screen size small enough (1 m [0.04 in]) to physically exclude eggs and larvae (ARCADIS 2008). At the deep underwater location of the Seabrook intakes (60 ft (18 m) depth), ARCADIS (2008) anticipated heavy biofouling that would not likely be completely cleared by the use of an air burst system. To prevent biofouling on wedgewire screens at a facility in Boston Harbor, the screens are manually cleaned once a month by physically removing the screens and pressure washing them out of the water. At Seabrook, manual cleaning would require divers, which would be costly and timely (ARCADIS 2008). In addition to organisms growing on the screens, kelp could also block the screens, which has the potential to quickly cover the screens causing a rapid loss of cooling water and the air burst system may not be effective in removing the kelp from the screen (ARCADIS 2008). This situation could cause an operational risk.
In conclusion, ARCADIS (2008) determined that wedgewire screens are not a suitable intake technology because of the significant increase in operational risk of failure and potential maintenance efforts.
Grey Water The use of grey water, or treated wastewater, would reduce impacts from impingement and entrainment because the grey water would be used in place of withdrawing water from the Gulf of Maine. No impingement or entrainment would be associated with the use of grey water because the cooling water would come from water pollution control plants (WPCPs).
NextEra considered using grey water to reduce impingement and entrainment at Seabrook (ARCADIS 2008). The three WPCP within 15 mi (24 km) of Seabrook include the Seabrook
73 WPCP, and Portsmouth WPCP, and the Hampton WPCP (ARCADIS 2008). ARCADIS (2008) estimated that these three WPCPs could provide approximately 5 to 6 mgd, which is less than 1 percent of Seabrooks daily cooling water requirements (682 mgd).
ARCADIS (2008) estimated that the reduction in impingement and entrainment would be approximately less than 1 percent. In addition, a variety of environmental impacts would result from construction and operation of pipelines to transport the grey water from the WPCPs to Seabrook. These impacts would likely be greatest in wetlands and salt marsh areas, which provide high quality habitat for terrestrial and aquatic resources. Given the location of Seabrook and the WPCPs, wetlands and salt marshes would be difficult to avoid. In addition, NextEra would need to acquire ROWs, which could be on or adjacent to private land, recreational areas, or high quality terrestrial and aquatic habitats.
NextEra concluded that the use of grey water was not a suitable option for reducing impingement and entrainment because the reduction in impingement and entrainment would be essentially imperceptible (ARCADIS 2008). Further, the permitting, engineering, and construction of the pipelines would be difficult and would result in a variety of environmental impacts, as described above.
Variable Frequency Drives Variable frequency drives (VFDs) can reduce impingement and entrainment by reducing the amount of water withdrawn for cooling water. VFDs on the circulating water pump motors reduce the pump speed, which in turn reduces the pump flow. Harish et al. (2010) created a theoretical model that demonstrated that VFD would reduce withdrawal rates, but the discharge temperature would increase. This research suggests that VFDs may decrease impingement and entrainment because less water and organisms would be pulled through the cooling system, although VFDs may increase thermal impacts because the discharge would be released at a higher temperature.
NextEra considered VFDs to reduce the withdrawal requirements at Seabrook (ARCADIS 2008). ARCADIS (2008) determined that a VFD could be installed on each of the three circulating water pump motors. Each VFD enclosure would be over 20 ft (6.1 m) long and, therefore, installed on the outside of the turbine building (ARCADIS 2008).
ARCADIS (2008) determined that the three VFDs would reduce the minimum flow achievable to 250,000 gpm (360 mgd). This would result in an approximate 8 to 30 percent decrease in cooling water withdrawal, depending on the season and water temperature. The greatest reductions would occur in the winter and spring when the water is coolest. ARCADIS (2008) estimated that the use of VFDs would reduce entrainment by 4 percent. However, the use of VFDs would also increase the discharge temperature from 39 °F (3.9 °C) to 45 °F (7.2 °C),
thereby increasing potential thermal impacts and exceeding the limits of Seabrook's NPDES discharge.
NextEra concluded that installing and operating three VFDs is feasible in terms of operation.
However, it would require Seabrook to obtain a new NPDES permit that would increase the allowable temperature of the discharge water.
Other Potential Mitigation In its comments on the draft SEIS, NMFS suggested that NextEra conduct additional studies to understand the causative agent for the decline in macroaglae near Seabrook. For example, various studies could be conducted to better understand whether the decline was due to Seabrooks thermal discharge or other activities. Similarly, NMFS suggested that NextEra 74 conduct studies that test whether changes in benthic fish communities near the Seabrook discharge (NMFS 2011e):
are the result of thermal effects from the discharge plume, such as avoidance of the thermal plume by juvenile and adult life stages or from mortality reduced fitness of egg and larval stages that may settle to the bottom in this area, or a result of eggs and larvae that are lost to the general area from impingement and entrainment in the cooling water system.
In its comments on the draft SEIS, NHFGD identified two potential mitigation projects that would mitigate potential impacts to winter flounder and rainbow smelt, which are important commercial and recreational fish. As described in Appendix A, NHFGD suggested that NextEra fund projects that would reduce the point and nonpoint sources of nitrogen loading in the Great Bay Estuary System watershed to potentially improve habitat for juvenile winter flounder and rainbow smelt. NHFGD also suggested that NextEra could compensate businesses that rely on winter flounder catch for income.
Conclusion Table D-1-13 summarizes NRC conclusions on the effect of Seabrook operation on habitat for the 23 EFH species that may occur within the vicinity of Seabrook.
Table D-1-13. Summary of NRC conclusions Regarding the Effect on Habitat by Species and Life Stages Species Eggs Larvae Juveniles Adults Rational for adverse impact American plaice NL(a)
NL Atlantic butterfish NL NL NL NL Atlantic cod NL MIN(b)
MIN MIN Some of the primary and preferred forage fish, such as Atlantic herring and American sand lance, are regularly entrained and impinged at Seabrook; the thermal plume near the surface could slightly exceed the typical range of temperatures that Atlantic cod inhabit; juvenile cod likely use kelp beds near Seabrook.
Atlantic halibut NL NL MIN MIN Atlantic halibut may use algal habitats that have declined near Seabrook since operations began.
Atlantic herring MIN MIN The thermal plume near the surface could slightly exceed the typical range of temperatures that Atlantic herring juveniles and adults inhabit.
Atlantic mackerel MIN NL NL MIN Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook. The thermal plume near the surface could exceed the typical temperature range that adult Atlantic mackerel inhabit.
Atlantic sea scallop NL NL MIN NL Newly settled Atlantic sea scallops may use algal habitats that have declined near Seabrook since operations began.
Atlantic surf clam NL NL Bluefin tuna NL Haddock NL
75 Species Eggs Larvae Juveniles Adults Rational for adverse impact Longfin inshore squid NL NL Monkfish/Goosefish MIN MIN MIN NL The thermal plume near the surface could slightly exceed the typical range of temperatures that goosefish eggs and larvae inhabit; juveniles may use algal habitats that have declined near Seabrook since operations began.
Northern shortfin squid MIN MIN The thermal plume near the surface could exceed the typical temperature range for northern shortfin squid.
Ocean pout NL NL MIN NL Juveniles may use algal habitats that have declined near Seabrook since operations began.
Pollock MIN Pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Juveniles may use algal habitats that have declined near Seabrook since operations began.
Redfish NL MIN MIN Redfish may use algal habitats that have declined near Seabrook since operations began.
Red hake MIN MIN MIN MIN The hake (which includes red, white, and spotted hake) comprised 6.2 percent of all entrained fish eggs and 6.5 percent of all impinged fish at Seabrook.
Scup NL NL Summer flounder MIN Summer flounder may use algal habitats that have declined near Seabrook since operations began.
Whiting/Silver hake ADV(c) ADV ADV ADV Silver hake was the third most commonly entrained egg species, comprising 9 percent of all entrained fish eggs at Seabrook. The thermal plume could exceed the typical range of temperatures that larvae and adults inhabit, and adult and juveniles decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
Windowpane flounder MIN MIN Windowpane comprised 3.5 percent of all entrained eggs and 6.2 percent of all impinged fish at Seabrook Winter flounder NL ADV ADV ADV Winter flounder was the third most commonly impinged fish species, comprising 10 percent of all impinged fish. Winter flounder larvae was the eighth most commonly entrained species, comprising 3.4 percent of the total fish larvae entrained. Winter flounder may use algal habitats that have declined near Seabrook since operations began. Adult and juvenile winter flounder abundance decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
Yellowtail flounder MIN MIN Yellowtail flounder eggs was the sixth most commonly entrained fish egg species, comprising 4.8 percent of the total fish eggs entrained at Seabrook.
(a) NL= Seabrook operation is not likely to affect EFH.
(b) MIN= Seabrook operation may have minimal adverse effects on EFH.
76 Species Eggs Larvae Juveniles Adults Rational for adverse impact (c) ADV= Seabrook operation may adversely affect EFH.
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ESSENTIAL FISH HABITAT ASSESSMENT
Essential Fish Habitat Assessment Seabrook Station, Unit 1 License Renewal Docket Number 50-443 U.S. Nuclear Regulatory Commission Rockville, Maryland
i TABLE OF CONTENTS D-1.1 Introduction................................................................................................................ D-1-1 D-1.2 Description of the Proposed Action............................................................................ D-1-1 D-1.2.1 Site Location and Description....................................................................... D-1-2 D-1.2.1.1 Cooling and Auxiliary Water Systems............................................ D-1-2 D-1.3 Essential Fish Habitat Species Near the Site and Potential Adverse Effects............. D-1-8 D-1.3.1 Essential Fish Habitat Species Identified for Analysis.................................. D-1-8 D-1.3.2 Potential Adverse Effects to Essential Fish Habitat.................................... D-1-10 D-1.3.2.1 Information Related to Potential Adverse Impact on All Essential Fish Habitat Species................................................... D-1-13 D-1.3.2.2 Combined Impacts (Monitoring Data).......................................... D-1-24 D-1.3.3 Adverse Effects on Essential Fish Habitat by Species............... D-1-32 D-1.3.3.1 American Plaice (Hippoglossoides platessoides) (Juvenile and Adult)................................................................................... D-1-32 D-1.3.3.2 Atlantic butterfish (Peprilus triacanthus) (All Life Stages)............ D-1-33 D-1.3.3.3 Atlantic cod (Gadus morhua) (All Life Stages)............................. D-1-36 D-1.3.3.4 Atlantic herring (Clupea harengus) (Juvenile and Adult)............. D-1-38 D-1.3.3.5 Atlantic mackerel (Scomber scombrus) (All Life Stages)............. D-1-40 D-1.3.3.6 Atlantic sea scallop (Placopecten magellanicus) (All Life Stages)....................................................................................... D-1-43 D-1.3.3.7 Atlantic Surfclam (Spisula solidissima) (Juveniles and Adults).... D-1-45 D-1.3.3.8Haddock (Melanogrammus aeglefinus) (Juvenile)....................... D-1-46 D-1.3.3.9 Monkfish/Goosefish (Lophius americanus) (All Life Stages)....... D-1-48 D-1.3.3.10Ocean pout (Macrozoarces americanus) (All Life Stages)......... D-1-50 D-1.3.3.11Pollock (Pollachius virens) (Juvenile)......................................... D-1-52 D-1.3.3.12Red hake (Urophycis chuss) (All Life Stages)........................... D-1-54 D-1.3.3.13Scup (Stenotomus chrysops) (Juvenile and Adult).................... D-1-56 D-1.3.3.14Summer flounder (Paralicthys dentatus) (Adult)........................ D-1-57 D-1.3.3.15Whiting/Silver hake (Merluccius bilinearis) (All life stages)........ D-1-59 D-1.3.3.16Windowpane flounder (Scopthalmus aquosus) (Juveniles and Adults) D-1-61 D-1.3.3.17Winter flounder (Pleuronectes americanus) (All Life Stages).... D-1-63 D-1.3.3.18Yellowtail flounder (Pleuronectes ferruginea) (Juveniles and Adults) D-1-65 D-1.3.3.19Essential Fish Habitat Species Not Likely to Regularly Occur Near Seabrook............................................................................ D-1-67 D-1.4 Cumulative Effects to Essential Fish Habitat........................................................... D-1-68 D-1.5 Essential Fish Habitat Conservation Measures....................................................... D-1-71 D-1.6 Conclusion............................................................................................................... D-1-74 D-1.7 References............................................................................................................... D-1-76
ii Figures Figure D-1-1. Location of Seabrook, 6-mi (10-km) region.................................................... D-1-3 Figure D-1-2. Location of Seabrook, 50-mi (80-km) region.................................................. D-1-4 Figure D-1-3. Seabrook site boundary and facility layout..................................................... D-1-5 Figure D-1-4. Intake shafts and caps at Seabrook............................................................... D-1-6 Figure D-1-5. Profile of intake tunnel and shafts at Seabrook.............................................. D-1-7 Figure D-1-6. Circulating water pumphouse at Seabrook..................................................... D-1-8 Figure D-1-7. Sampling Stations for Seabrook Station aquatic monitoring......................... D-1-25 Tables Table D-1-1. Species of fish with designated EFH in the vicinity of Seabrook..................... D-1-9 Table D-1-2. Relative commonness of EFH species in Seabrook monitoring, entrainment, and impingement studies.......................................................... D-1-11 Table D-1-3. Aquatic resource issues identified in the GEIS.............................................. D-1-13 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species.............................................................. D-1-15 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species..................................................... D-1-17 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species............................................................................................. D-1-19 Table D-1-7. Number of bivalve larvae entrained (x 109).................................................... D-1-21 Table D-1-8. Mean density (No./1,000m3) and upper and lower 95% confidence limits (CL) of the most common fish eggs and larvae from 1982-2009 monitoring data at Seabrook......................................................................... D-1-26 Table D-1-9. Geometric mean catch per unit effort (CPUE) (No. per 10-minute tow) and upper and lower 95% CL during preoperational and operational monitoring years for the most abundant species........................................... D-1-27 Table D-1-10. Geometric mean CPUE (No. per 24-hr surface and bottom gill net set) and coefficient of variation (CV) during preoperational (1976-1989) and operational monitoring years (1990-1996).................................................... D-1-28 Table D-1-11. Geometric mean CPUE (No. per seine haul) and upper and lower 95% CL during preoperational and operational monitoring years................. D-1-30 Table D-1-12. Kelp density (No. per 100 m2) and upper and lower 95% CL during preoperational and operational monitoring years.......................................... D-1-31 Table D-1-13. Summary of NRC conclusions Regarding the Effect on Habitat by Species and Life Stages................................................................................ D-1-74
iii ABBREVIATIONS, ACRONYMS, AND SYMBOLS ac acre ADAMS Agencywide Documents Access and Management System BACI before-after control-impact CFR U.S. Code of Federal Regulations cfs cubic feet per second CL confidence limit cm centimeter CO2 carbon dioxide CPUE catch per unit effort CV coefficient of variation CWA Clean Water Act DFO Fisheries and Oceans Canada EEP Estuary Enhancement Program EFH Essential Fish Habitat EPA U.S. Environmental Protection Agency ER Environmental Report FPLE Florida Power Light Energy Seabrook fps feet per second FR Federal Register ft foot FMP fishery management plan GEIS generic environmental impact statement gpm gallons per minute ha hectare in.
inch kg kilogram km kilometer lb pound m
meter m/s meters per second m3 cubic meters m3/day cubic meters per day m3/s cubic meters per second m3/yr cubic meters per year MAFMC Mid-Atlantic Fishery Management Council MARMAC Marine Resources Monitoring, Assessment, and Prediction MDS multi-dimensional scaling mgd million gallons per day mi mile
iv mm millimeter MSA Magnuson-Stevens Fishery and Conservation Management Act MSL mean sea level MT metric tons NAI Normandeau Associates, Inc.
NEFMC New England Fishery Management Council NEFSC Northeast Fishery Science Center NEPA U.S. National Environmental Policy Act of 1969 NextEra NextEra Energy Seabrook, LLC NPDES National Pollutant Discharge Elimination System NMFS National Marine Fisheries Service NOAA National Oceanic and Atmospheric Administration NRC U.S. Nuclear Regulatory Commission PIC proposal for information collection ppt parts per thousand Seabrook Seabrook Station, Unit 1 SEIS supplemental environmental impact statement USGCRP U.S. Global Change Research Program
1 ESSENTIAL FISH HABITAT ASSESSMENT FOR THE PROPOSED LICENSE RENEWAL OF SEABROOK STATION Introduction In compliance with Section 305(b)(2) of the Magnuson-Stevens Fishery Conservation and Management Act (MSA), as amended by the Sustainable Fisheries Act of 1996 (Public Law 104-267), the U.S. Nuclear Regulatory Commission (NRC) prepared this Essential Fish Habitat (EFH) assessment for the proposed Federal action: NRCs decision whether or not to renew the operating license for Seabrook Station (Seabrook), Unit 1. Seabrook is located in Rockingham County, NH, on the shore of the Hampton-Seabrook Estuary and the Gulf of Maine.
Pursuant to the MSA, NRC staff requested, via letter dated July 16, 2010 (NRC 2010), that the National Marine Fisheries Service (NMFS) provide information on EFH near the Seabrook site.
In their response to NRC, NMFS (2010) indicated that marine waters off Seabrook and the Hampton-Seabrook Estuary have been designated as EFH for 23 Federally managed species and directed the NRC to prepare an EFH assessment as part of the EFH consultation process.
Accordingly, this EFH assessment does the following:
describes the proposed action, identifies relevant commercial, Federally managed species within the vicinity of the proposed site, assesses if the proposed action may adversely affect any designated EFH, and describes potential measures to avoid, minimize, or offset potential adverse impacts to EFH as a result of the proposed action.
Description of the Proposed Action The proposed Federal action is NRCs decision of whether or not to renew the operating license for Seabrook for an additional 20 years beyond the original 40-year term of operation.
NextEra Energy Seabrook, LLC (NextEra) initiated the proposed Federal action by submitting an application for license renewal of Seabrook, for which the existing license, NPF-86, expires on March 15, 2030. If NRC issues a renewed license for Seabrook, NextEra could continue to operate until the 20-year terms of the renewed license expire in 2050. If the operating license is not renewed, then the facility must shut down on or before the expiration date of the current operating license (March 15, 2030).
Pursuant to the NRCs environmental protection regulations in Title 10 of the U.S. Code of Federal Regulations (CFR) Part 51, which implement the U.S. National Environmental Policy Act of 1969 (NEPA), the NRC is publishing this supplemental environmental impact statement (SEIS) for Seabrook concurrent with this EFH Assessment. The SEIS is a site-specific supplement to the Generic Environmental Impact Statement [GEIS] for License Renewal of Nuclear Plants, NUREG-1437 (NRC 1996).
NextEra (2010) has proposed no major construction, refurbishment, or replacement activities associated with the proposed Federal action. During the proposed license renewal term, NextEra would continue to perform site maintenance activities as well as vegetation management on the transmission line right-of-ways that connect Seabrook to the electric grid.
2 D-1.2.1 Site Location and Description Seabrook is located in the Town of Seabrook, Rockingham County, NH, 2 mi (3.2 km) west of the Atlantic Ocean. Seabrook is approximately 2 mi (3.2 km) north of the Massachusetts state line, 15 mi (24 km) south of the Maine state line, and 10 mi (16 km) south of Portsmouth, NH.
Two metropolitan areas lie within 50 mi (80 km) of the site: Manchester, NH (31 mi (50 km) west-northwest) and Boston, MA (41 mi (66 km) south-southwest). Figure D-1-1 and Figure D-1-2 present the 6-mi (10-km) and 50-mi (80-km) area surrounding Seabrook, respectively.
The Seabrook site spans 889 acres (ac) (360 hectare (ha)) on a peninsula of land bordered by Browns River on the north, Hunts Island Creek on the south, and estuarine marshlands on the east. Two lots divide the site. The joint owners of Seabrook own Lot 1, which encompasses approximately 109 ac (44 ha). The majority of the operating facility is located on this mostly developed lot. Site structures include the Unit 1 containment building, primary auxiliary building, fuel storage building, waste processing building, control and diesel generator building, turbine building, administration and service building, ocean intake and discharge structures, circulating water pumphouse, and service water pumphouse (NextEra 2010). NextEra originally planned to construct two identical units at the Seabrook site but halted construction on Unit 2 prior to completion and uses the remaining Unit 2 buildings primarily for storage.
NextEra owns Lot 2, which is approximately 780 ac (316 ha). Lot 2 is mainly an open tidal marsh area with fabricated linear drainage ditches and tidal creeks, and it is available habitat for wildlife resources (NextEra 2010). The site boundary is also the exclusion area. Figure D-1-3 provides a general layout of the Seabrook site.
The Seabrook cooling water comes from an intake structure located 60 ft (18.3 m) below mean lower low water in the Gulf of Maine (see Section D-1.2.1.1). The seafloor in this area is relatively flat, with bedrock covered by sand, algae, or sessile invertebrates (NAI 2010). The immediate vicinity surrounding the Seabrook plant is the Hampton-Seabrook Estuary. No intake or discharge structures are located in the estuary. From construction until 1994, Seabrook discharged to an onsite settling basin into the Browns River.
The Gulf of Maine and Hampton-Seabrook Estuary are complex water bodies with many individual species performing different roles in the system, and, often, species perform several ecological roles throughout their lifecycles. Major assemblages of organisms within the marine and estuarine communities include plankton, fish, benthic invertebrates, and algae.
Section 2.2.6 in the SEIS describes these assemblages and typical habitat types in the nearshore of the Gulf of Maine and within Hampton-Seabrook Estuary.
D-1.2.1.1 Cooling and Auxiliary Water Systems Seabrook uses a once-through cooling system that withdraws water from the Gulf of Maine and discharges to the Gulf of Maine through a system of tunnels that have been drilled through ocean bedrock. Unless otherwise cited, the NRC staff drew information about Seabrooks cooling and auxiliary water systems from the National Pollution Discharge Elimination System (NPDES) Permit (EPA 2002a) and the applicants Environmental Report (ER) (NextEra 2010).
3 Figure D-1-1. Location of Seabrook, 6-mi (10-km) region Source: (NextEra 2010) 4 Figure D-1-2. Location of Seabrook, 50-mi (80-km) region Source: (NextEra 2010)
5 Figure D-1-3. Seabrook site boundary and facility layout Source: (NextEra 2010)
Water is drawn from the Gulf of Maine through three concrete intake structures that are located at the end of an intake tunnel in approximately 60 ft (18 3 m) of water depth. Each intake shaft 6
extends up from the intake tunnel to above the bedrock, and a velocity cap sits on top (Figure D-1-4). NextEra implemented this structural design to reduce the intake velocity, thereby minimizing fish entrapment. In 1999, NextEra modified the intakes with additional vertical bars to help prevent seals from getting trapped (NMFS 2002). The NPDES permit limits the intake velocity to 1.0 feet per second (fps) (0.3 meters per second (m/s)) (EPA 2002a).
Figure D-1-4. Intake shafts and caps at Seabrook Source: (ARCADIS et al. 2008)
Water flows from the intake structures through a 17,000-ft (5,182-m) intake tunnel that was drilled through the ocean bedrock. The beginning of the intake tunnel is 7,000 ft (2,134 m) from the Hampton beach shoreline. The tunnel descends at a 0.5 percent grade from the bottom of the intake shaft, which is 160 ft (49 m) below the Gulf of Maine, to 240 ft (73 m) below mean sea level (MSL) at Seabrook (Figure D-1-5). Concrete lines the 19-ft (5.8-m) diameter tunnel.
7 Figure D-1-5. Profile of intake tunnel and shafts at Seabrook Source: (ARCADIS et al. 2008)
An intake transition structure, which includes three circulating water pumps that transport the water, is located beneath Seabrook (Figure D-1-6). Butterfly valves, 11-ft (3.4-m) in diameter, direct the water flow from the transition structure to the circulating water pumphouse. The water then passes through three traveling screens with a 3/8-inch (0.95-cm) square mesh (NextEra 2010a). The traveling screens remove fish, invertebrates, seaweed, and other debris before the water is pumped to the main condensers and the service water system. The ocean debris is disposed as waste; therefore, none is discharged to the Gulf of Maine. The water passes to the condensers to remove heat that is rejected by the turbine cycle and auxiliary system. During normal operations, the circulating water system provides a continuous flow of approximately 390,000 gallons per minute (gpm) (869 cubic feet per second (cfs) or 24.6 cubic meters (m3) per second (m3/s)) to the main condenser and 21,000 gpm (47 cfs or 1.3 m3/s) to the service water system.
Water that has passed through Seabrook discharges to the Gulf of Maine through a 16,500-ft (5,029-m) long discharge tunnel, which has the same diameter, lining, depth, and percent grade as the intake tunnel. The end of the discharge tunnel is 5,000 ft (1,524 m) from the Seabrook beach shoreline. Eleven 70-ft (21-m) deep concrete shafts about 100 ft (30 m) apart discharge the effluent. Each shaft terminates in a pair of nozzles that are pointed up at an angle of about 22.5 degrees (NAI 2001). The nozzles are located 6.5 to 10 ft (2 to 3 m) above the seafloor in depths of approximately 49 to 59 ft (15 to 18 m) of water (NAI 2001). To increase the discharge velocity and more quickly diffuse the heated effluent, a double-nozzle fixture tops each shaft.
The NPDES permit limits this discharge flow to 720 million gallons per day (mgd) (2.7 million m3/day), and the monthly mean temperature rise may not exceed 5° F (2.6 ° C) at the surface of the receiving water (EPA 2002a).
Barnacles, mussels, and other subtidal fouling organisms can attach to concrete structures and potentially limit water flow through the tunnels. To minimize biofouling within the intake and discharge tunnels, NextEra uses a combination of physical scrubbing and a chlorination system (NextEra 2010a). Divers physically scrub the intake structures biannually to remove biofouling organismssuch as barnacles, mussels, or other organismsthat attach to hard surfaces to grow. During outages, the inside of the intake structures are physically scrubbed up until the point that chlorine is injected into the tunnels, approximately 6 ft (1.8 m) into the intake shaft. In addition, NextEra inspects the discharge diffusers during outages. The circulating water pumphouse, pipes, and condensers are dewatered, inspected, and cleaned as needed 8
(Seabrook 2008). NextEra injects chlorine and other water treatment chemicals in accordance with NPDES permit limits (EPA 2002a).
Figure D-1-6. Circulating water pumphouse at Seabrook Source: (ARCADIS et al. 2008)
As described above, the Gulf of Maine provides water for both the circulating water system and the service water system. Water flows from the intake structures to the service water pumphouse, which is separated from the circulating water system portion of the building by a seismic reinforced concrete wall. In the event that the regular supply of cooling water from the service water pumphouse is unavailable, NextEra would use a standby mechanical draft evaporative cooling tower (service water tower) and 7-day makeup water reservoir. This makeup water reservoir is from the Gulf of Maine and stored in the service water tower. If this makeup reservoir is unavailable, or additional water is required, NextEra would access emergency makeup water from the domestic water supply system or from the Browns River via a portable pump (FPLE 2008).
Sections 2.1.1 through 2.1.5 of the SEIS provide additional information regarding the reactor and containment systems, other systems at Seabrook, and plant operations. Sections 2.1.7 and 2.2.5 provide additional information on Seabrooks surface water use and a description of the NDPES permit.
Essential Fish Habitat Species Near the Site and Potential Adverse Effects D-1.3.1 Essential Fish Habitat Species Identified for Analysis The waters and substrate necessary for spawning, breeding, feeding, or growth to maturity are considered EFH (16 U.S.C. 1802(10)). The portion of the Gulf of Maine and Hampton-Seabrook Estuary adjacent to Seabrook, and its intake and discharge structures, contains designated EFH for several fish species and life stages.
9 In its Guide to Essential Fish Habitat Designations in the Northeastern United States, NMFS (2011a) identifies EFH by 10-minute squares of latitude and longitude as well as by major estuary, bay, or river for estuarine waters outside of the 10-minute square grid. The waters near Seabrook are within the Gulf of Maine EFH Designation that extends from Salisbury, MA, north to Rye, NH and includes Hampton Harbor, Hampton beach, and Seabrook beach. The 23 species with designated EFH in this area appear in Table D-1-1.
Table D-1-1. Species of fish with designated EFH in the vicinity of Seabrook Species Eggs Larvae Juveniles Adults American plaice (Hippoglossoides platessoides) x x
Atlantic butterfish (Peprilus triacanthus) x x
x x
Atlantic cod (Gadus morhua) x x
x x
Atlantic halibut (Hippoglossus hippoglossus) x x
x x
Atlantic herring (Clupea harengus) x x
Atlantic mackerel (Scomber scombrus) x x
x x
Atlantic sea scallop (Placopecten magellanicus) x x
x x
Bluefin tuna (Thunnus thynnus) x Haddock (Melanogrammus aeglefinus) x Longfin inshore squid (Loligo pealei) x x
Monkfish/Goosefish (Lophius americanus) x x
x x
Northern shortfin squid (Illex illecebrosus) x x
Ocean pout (Macrozoarces americanus) x x
x x
Pollock (Pollachius virens) x Redfish (Sebastes fasciatus) x x
x Red hake (Urophycis chuss) x x
x x
Scup (Stenotomus chrysops) x x
Summer flounder (Paralicthys dentatus) x Atlantic Surf clam (Spisula solidissima) x x
Whiting/Silver hake (Merluccius bilinearis) x x
x x
Windowpane flounder (Scopthalmus aquosus) x x
Winter flounder (Pleuronectes americanus) x x
x x
Yellowtail flounder (Pleuronectes ferruginea) x x
Source: (NMFS 2011b)
Seabrook has monitored fish and shellfish eggs, larvae, juveniles, and adults since the mid-1970s. In addition, Seabrook regularly records annual estimates of entrainment and impingement. Table D-1-2 presents a summary of the occurrence of EFH species within Seabrooks monitoring, entrainment, and impingement studies.
The NRC staff compared monitoring, entrainment, and impingement data with each of the EFH species listed in Table D-1-2. Seabrook regularly observed most EFH species within 10 monitoring, entrainment, or impingement studies. However, Atlantic halibut, redfish, bluefin tuna, northern shortfin squid, and longfin inshore squid were rarely or occasionally identified during monitoring studies and were not entrained or impinged from 1990 to 2009. These fives species are analyzed in Section D-1.3.3.19 of this assessment. All other EFH species are analyzed in detail in Sections D-1.3.3.1 through D-1.3.3.18 of this assessment.
D-1.3.2 Potential Adverse Effects to Essential Fish Habitat The provisions of the regulations implementing the MSA define an adverse effect to EFH as the following (50 CFR 600.810):
Adverse effect means any impact that reduces quality and/or quantity of EFH.
Adverse effects may include direct or indirect physical, chemical, or biological alterations of the waters or substrate and loss of, or injury to, benthic organisms, prey species and their habitat, and other ecosystem components, if such modifications reduce the quality and/or quantity of EFH. Adverse effects to EFH may result from actions occurring within EFH or outside of EFH and may include site-specific or habitat-wide impacts, including individual, cumulative, or synergistic consequences of actions.
For purposes of conducting NEPA reviews, the NRC staff published the GEIS (NRC 1996),
which identifies 13 impacts to aquatic resources as either Category 1 or Category 2.
Category 1 issues are generic in that they are similar at all nuclear plants and have one impact level (SMALL, MODERATE, or LARGE) for all nuclear plants. Mitigation measures for Category 1 issues are not likely to be sufficiently beneficial to warrant implementation.
Category 2 issues vary from site to site and must be evaluated on a site-specific basis.
Table D-1-3 lists the aquatic resource issues as identified in the GEIS.
The GEIS classifies all impact levels for aquatic resources as SMALL except impingement, entrainment, and heat shock. NRC defines SMALL as having environmental effects are not detectable or are so minor that they will neither destabilize nor noticeably alter any important attribute of the resource (10 CFR 51, App. B, Table B-1). The NRC staff believes that stressors with SMALL levels of impact for the purposes of implementing NEPA would likely not adversely affect EFH. Therefore, this EFH Assessment will focus on the potential adverse effects of impingement, entrainment, and heat shock on EFH. Impingement occurs when aquatic organisms are pinned against intake screens or other parts of the cooling water system intake structure. Entrainment occurs when aquatic organisms (usually eggs, larvae, and other small organisms) are drawn into the cooling water system and are subjected the thermal, physical, and chemical stress. Heat shock is acute thermal stress caused by exposure to a sudden elevation of water temperature that adversely affects the metabolism and behavior of fish and other aquatic organisms. In addition to heat shock, increased water temperatures at the discharge can also reduce the available habitat for fish species if the discharged water is higher than the environmental preferences of a particular species. This issue will be discussed together with heat shock.
11 Table D-1-2. Relative commonness of EFH species in Seabrook monitoring, entrainment, and impingement studies Species Eggs Larvae Juveniles and Adults Plankton monitoring Entrainment studies Plankton monitoring Entrainment studies Trawl monitoring Gill net monitoring Seine monitoring Impingement studies American plaice Common(a)
Occasional Common Occasional(b)
Occasional Rare(c)
Atlantic butterfish Occasional Rare Occasional Rare Rare Occasional Rare Rare Atlantic cod (e)
Common Common Common Rare Common Occasional Rare Rare Atlantic halibut Rare Atlantic herring Common Occasional Occasional Abundant Occasional Common Atlantic mackerel Abundant(d)
Abundant Abundant Rare Rare Common Rare Rare Atlantic sea scallop Rare Atlantic surf clam Rare Bluefin tuna Haddock (e)
Common Rare Occasional Rare Common Rare Rare Longfin inshore squid Monkfish/Goosefish Rare Rare Occasional Rare Occasional Rare Rare Northern shortfin squid Ocean pout Occasional Rare Common Rare Rare Pollock Common Rare Common Rare Common Common Occasional Common Redfish (e)
Occasional Red hake (e)
Common Common Common Occasional Abundant Occasional Common Common Scup Rare Occasional Rare Rare Summer flounder Rare Rare Rare Rare Whiting/Silver hake Common Common Common Occasional Common Common Rare Rare 12 Species Eggs Larvae Juveniles and Adults Plankton monitoring Entrainment studies Plankton monitoring Entrainment studies Trawl monitoring Gill net monitoring Seine monitoring Impingement studies Windowpane flounder Common Occasional Common Rare Common Rare Occasional Common Winter flounder Rare Common Occasional Common Occasional Common Common Yellowtail flounder (e)
Abundant Occasional Common Rare Abundant Rare Rare Common (a) Common: Occurring in >10% of samples but <10% of total catch; 5-10% of entrainment samples averaged over all years (b) Occasional: Occurring in <10%-1% of samples; 1-5% of entrainment samples averaged over all years (c) Rare: Occurring in <1% of samples; <1% of entrainment samples averaged over all years (d)Abundant: >10% of total catch or entrainment over all years (e) During monitoring surveys, NAI (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. In such cases, the estimate for the entire group of species appears in the table above. Groups of species include Atlantic cod/haddock/witch flounder, cunner/yellowtail founder, red hake/white hake/spotted hake, and golden redfish/deepwater redfish/and Acadian redfish. For egg entrainment estimates of these groups of species, NextEra (2010b) estimated single species entrainment rates by applying the ratio of larval species to the egg species groups Blank cells indicate the NAI (2010) did not identify the species within monitoring or entrainment studies.
Sources: (NAI 2010; NextEra 2010a)
13 Table D-1-3. Aquatic resource issues identified in the GEIS Issues Category Impact level For all plants Accumulation of contaminants in sediments or biota 1
SMALL Entrainment of phytoplankton & zooplankton 1
SMALL Cold shock 1
SMALL Thermal plume barrier to migrating fish 1
SMALL Distribution of aquatic organisms 1
SMALL Premature emergence of aquatic insects 1
SMALL Gas supersaturation (gas bubble disease) 1 SMALL Low dissolved oxygen in the discharge 1
SMALL Losses from parasitism, predation, & disease among organisms exposed to sublethal stresses 1
SMALL Stimulation of nuisance organisms 1
SMALL For plants with once-through heat-dissipation systems Impingement of fish & shellfish 2
SMALL, MODERATE, or LARGE Entrainment of fish & shellfish in early life stages 2
SMALL, MODERATE, or LARGE Heat shock 2
SMALL, MODERATE, or LARGE Source: (NRC 1996)
In addition to impingement, entrainment, and heat shock (or thermal impacts), the NRC staff will assess the impacts to EFH species food (forage species) and loss of habitat-forming species (such as sessile invertebrates and algae). Information on these areas that is relevant to all EFH species is in Section D-1.3.2.1. In addition, Section D-1.3.2.2 presents NextEra monitoring data of selected groups prior to and during operations at sampling sites near the intake and discharge structures (nearfield sampling sites) and at sampling sites 3 to 4 mi (5 to 8 km) away (farfield sampling sites). Monitoring data may indicate whether the combined impacts (or cumulative impacts) from Seabrook operation has resulted in the decline of forage species, habitat-forming species, or EFH species due to a decline in habitat quantity or quality. The NRC staffs conclusions and information specific to each EFH species is in Sections D-1.3.3.1 through D-1.3.3.19. Section D-1.4 provides an analysis of cumulative impacts to EFH species or their habitat resulting from the past, present, and reasonably foreseeable future projects in the vicinity of Seabrook.
D-1.3.2.1 Information Related to Potential Adverse Impact on All Essential Fish Habitat Species The section below provides information regarding potential adverse impacts to EFH that is relevant for the assessment of all 23 EFH species that may occur within the vicinity of Seabrook.
Entrainment and Impingement. Entrainment and impingement study results illustrate one type of operational impact on each species habitat. Because the intake water is EFH, the ratio of specimens from a species impinged or entrained at Seabrook to the total number of impinged or 14 entrained organisms provides some indication of how great the impact from the cooling system will be on the corresponding EFH. The NRC staff obtained data on fish entrainment and impingement from Seabrooks Annual Biological Monitoring Reports, which summarize entrainment data from 1990 to 2009 and impingement data from 1994 to 2009 (NAI 2010).
NextEra conducted entrainment studies four times per month (NAI 2010). For fish eggs and larvae prior to 1998, NextEra collected three replicate samples using 0.02-in. (0.505-mm) mesh nets. Since 1998, NextEra collected samples using 0.01-in. (0.333-mm) mesh sizes throughout a 24-hour period. NextEra estimated entrainment rates by multiplying the density of entrained eggs or larvae within a sample by the volume of water pumped through the plant within the sample period (FPLE 2008; NAI 2010). Entrainment rates for commonly entrained species, EFH species, and common forage species are presented in Table D-1-4 for egg entrainment and Table D-1-5 for larvae entrainment.
NextEra conducted impingement monitoring once or twice per week by cleaning traveling screens and sorting fish and other debris (NAI 2010). Prior to 1998, NextEra did not sort some collections, and impingement estimates are based on the volume of debris (NAI 2010).
Beginning in 1998, Seabrook staff sorted all collections and identified all impinged fish by species. Beginning in April 2002, NextEra collected two standardized 24-hour samples per week and multiplied by seven to estimate weekly impingement. Table D-1-6 shows impingement rates for commonly impinged species, EFH species, and common forage species.
NAI (2010) reported impingement estimates from 1994 to 2009. Prior to October 1994, NextEra determined that some small, impinged fish had been overlooked during separation procedures.
NextEra enhanced the Impingement Monitoring Program in the end of 1994 to remedy this issue (NextEra 2010a).
NextEra also conducted entrainment studies for bivalve larvae (NAI 2010). In these studies, NextEra collected three replicates per sampling date using a 0.003-in. (0.076-mm) mesh.
Table D-1-7 describes entrainment rates for bivalve larvae.
Thermal Impacts. Heat shock can injure or kill fish. In addition, aquatic species, including EFH species or prey of EFH species, may largely avoid effluents due to high velocities, elevated temperatures, and turbulence. Seabrooks discharge to the Gulf of Maine is permitted under its NPDES permit (EPA 2002a), issued April 1, 2002. The permit allows discharge of 720 mgd (2.7 million m3/day) on both an average monthly and maximum daily basis. The permit also limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. An EPA online database indicated that Seabrook has had no Clean Water Act (CWA) formal enforcement actions or violations related to discharge temperature in the last 5 years (EPA 2010). EPAs Regional Administrator determined that NextEras NPDES permit provides a Section 316(a) variance that satisfies thermal requirements and that will ensure the protection and propagation of a balanced indigenous community of fish, shellfish, and wildlife in and on Hampton Harbor and the near shore Atlantic Ocean (EPA 2002a).
15 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species Taxon(a) 1990(b) 1991(c) 1992(d) 1993(d) 1994(e) 1995(f) 1996 1997 1998 1999 2000 2001 American plaice 2.6 21.0 52.3 19.5 0.4 14.8 78.2 15.6 13.7 24.8 16.7 26.8 Atlantic cod 20.8 74.5 32.0 50.3 0.2 37.0 22.4 6.4 84.3 48.6 30.7 32.1 Atlantic mackerel 518.8 673.1 456.3 112.9 0.0 74.5 305.1 23.1 39.3 44.6 266.9 330.4 Butterfish 0
0 0
0 0
0 0.1 0
0
<0.1 0
0 Cunner 489.3 147.2 0
58.4 0
18.2 93.9 221.5 63.6 220.3 1,206.7 239.6 Fourbeard rockling 108.8 39.5 51.4 32.7 0.2 27.5 38.7 46.6 33.9 27.4 63.6 47.1 Haddock 0.0 0.0 7.4 0.0
<0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Hake 50.1 2.6 0
1.6 0.6 29.3 213.2 71.8 7.5 6.2 295.2 4.4 Monkfish/Goosefish 0
0 0
0 0
0 0
0 0.9 0
0.9 0
Pollock 0
1.0 0.4 0.2 0.1 0.4 0.4 0.2 2.9 0.2
<0.1 0.3 Whiting/Silver hake 11.4 0.0 0.1 0.4 0.4 22.5 73.6 271.1 18.6 139.9 90.4 48.9 Windowpane 36.4 19.9 22.5 29.1 0.1 17.4 44.2 28.5 17.9 43.2 95.1 33.4 Winter flounder 0
0 0
0 0
0 0
0 0
0 0.3 0
Yellowtail flounder 1.2 569.2 198.6 0
0 0.6 17.9 0.5 1.9 33.8 2.8 8.4 Total (All Species) 1,247.7 1,551.3 822.6 315.6 4.8 255.9 926.4 692.7 286.7 593.9 2,104.4 775.1 (a) Normandeau Associates, Inc. (NAI) (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. Groups of species include Atlantic cod/haddock, cunner/yellowtail founder, and hake/fourbeard rockling. NextEra (2010a) estimated entrainment rates for each species by applying the ratio of larval species to the egg species groups.
(b) NextEra sampled three months, August-October.
(c) NextEra sampled eight months, January-July, December.
(d) NextEra sampled eight months, January-August.
(e) NextEra sampled seven months, January-March, September-December.
(f) NextEra sampled 12 months per year.
Source: (NAI 2010; NextEra 2010a) 16 Table D-1-4. Number of fish eggs entrained (in millions) for most common egg taxa entrained and for EFH species (cont.)
Taxon 2002 2003 2004 2005 2006 2007 2008 2009 Average Percentage American plaice 22.4 37.8 33.4 11.7 5.3 35.8 48.0 36.7 25.9 2.9%
Atlantic cod 77.8 15.5 9.3 16.0 15.7 15.1 48.0 15.4 32.6 3.6%
Atlantic mackerel 56.7 26.4 70.1 37.7 475.6 153.6 82.4 83.5 191.5 21.3%
Butterfish 0
0 0
0.4 0
0 0
0
<0.1
<0.1%
Cunner 1,395.7 143.9 518.1 251.2 489.4 295.0 444.5 1,451.2 387.4 43.0%
Fourbeard rockling 61.4 44.1 38.2 68.8 36.6 78.2 61.7 123.8 51.5 5.7%
Haddock 0
0 0
0.7 0
0 0
0 0.4
<0.1%
Hake 79.7 5.2 5.7 2.8 8.1 15.6 21.7 92.1 45.7 5.1%
Monkfish/Goosefish 0
0 0.1 0.1 0.1 0
0 0
0.1
<0.1%
Pollock 0.6 1.0 0.9 1.0 4.1 8.5 5.0 0.2 1.4 0.2%
Whiting/Silver hake 341.4 235.6 19.8 30.7 9.4 60.8 50.9 196.2 81.1 9.0%
Windowpane 39.1 15.5 18.2 26.2 24.7 34.7 25.9 61.8 31.7 3.5%
Winter flounder 0
0.3 0
0 0
0.2 1.1
<0.1
<0.1
<0.1%
Yellowtail flounder 3.9 0
0.1 5.0 1.1 7.8 0
4.1 42.8 4.8%
Total (all species) 2,086.8 529.4 723.7 454.4 1,075.4 714.7 790.6 2,072.5 901.2 100%
(a) Normandeau Associates, Inc. (NAI) (2010) combined certain groups of species if eggs were morphologically similar and spawning periods overlapped during the sampling period. Groups of species include Atlantic cod/haddock, cunner/yellowtail founder, and hake/fourbeard rockling. NextEra (2010a) estimated entrainment rates for each species by applying the ratio of larval species to the egg species groups.
(b) NextEra sampled 3 months, August-October.
(c) NextEra sampled 8 months, January-July, December.
(d) NextEra sampled 8 months, January-August.
(e) NextEra sampled 7 months, January-March, September-December.
(f) In 1995-2009, NextEra sampled 12 months per year.
Source: (NAI 2010; NextEra 2010a)
17 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species Taxon 1990(a) 1991(b) 1992(c) 1993(d) 1994(e) 1995 1996 1997 1998 1999 2000 2001 American plaice 0.4 1.0 0.8 0.7 0
7.9 8.1 7.0 2.9 4.9 1.6 8.7 American sand lance 0
37.3 18.1 12.0 8.3 9.5 14.0 10.1 10.7 7.8 1.0 5.3 Atlantic butterfish 0
0 0
0 0
0 0
0.1 0
0 0
0 Atlantic cod 0.7 1.5 0.4 0.1 0
2.3 0.3 0.7 2.2 1.0 0.4 2.5 Atlantic herring 0.7 0.5 4.9 9.6 0.1 11.2 4.3 2.1 9.5 8.6 0.2 15.2 Atlantic mackerel 0.2 4.7 0
0 0
0 0.1 0.4 0
0.1 0.3 0.1 Cunner 42.7
<0.1 0
4.7 0.1 4.4 9.2 203.8 8.4 4.7 111.0 13.6 Fourbeard rockling 37.9 0.5 0.1 2.2 0.0 3.9 11.7 22.4 13.1 21.0 8.2 19.6 Grubby 0
22.4 18.9 13.8 4.9 17.4 18.6 12.8 17.3 6.4 2.2 12.4 Haddock 0
0 0.1 0
0 0
0 0
0 0
0 0
Hake 4.8 0
0 0.1 0
0.7 12.3 1.7
<0.1 0.1 29.8 0
Monkfish/Goosefish 0.1 0
0 0
0 0
0 0
0 0
2 0
Ocean pout 0
0 0
0 0
0 0
0 0
0 0
0 Pollock 0.2 0
0.1 0
0 0
0 0
<0.1 0
0 0
Summer flounder 0
0 0
0 0
0 0
0
<0.1 0
0 0
Whiting/Silver hake 7.7 0
0 0.1 0
0.9 16.9 69.0 0.2 0.4 33.2 0.6 Windowpane 3.8
<0.1 0.1 0.1
<0.1 2.0 2.0 5.6 1.4 3.7 2.3 1.3 Winter flounder 3.2 9.0 6.2 2.9 0
8.0 10.3 2.2 4.7 7.4 14.3 14.3 Yellowtail flounder 0.1 0.3 0.1 0
0 0.1 1.6 0.5 0.3 0.8 0.3 0.5 Total (all species) 121.5 153.8 133.1 126.1 31.2 145.3 215.7 373.4 134.1 171.8 261.2 124.3 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) Unless otherwise denoted, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra did not conduct bivalve larvae entrainment studies.
(f) NextEra sampled the fourth week in April through the fourth week in October.
(g) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010) 18 Table D-1-5. Number of fish larvae entrained (in millions) for the most common larval taxa entrained and for EFH species (cont.)
Taxon 2002 2003 2004 2005(f) 2006(g) 2007 2008 2009 Average Percentage American plaice 11.3 9.1 2.6 1.4 0.6 2.6 3.5 11.5 4.3 1.6%
American sand lance 10.5 27.1 107.1 28.3 14.1 36.6 71.2 128.6 27.9 10.3%
Atlantic butterfish 0
0 0
0 0
0 0
0
<0.1
<0.1%
Atlantic cod 34.6 2.5 0.5 1.6 0.3 1.6 1.4 1.4 3.0 1.0%
Atlantic herring 11.7 15.3 8.8 9.7 12.8 11.5 28.2 27.7 9.6 3.6%
Atlantic mackerel 0.4 0
20.2 0.1 0.5 0
<0.1 25.7 2.6 1.0%
Cunner 391.1 22.5 451.2 2.5 8.8 97.7 86.2 105.7 78.4 29.1%
Fourbeard rockling 176.4 19.3 61.4 2.0 4.9 16.4 11.9 20.3 22.7 8.4%
Grubby 6.6 27.5 51.8 7.8 9.3 15.4 8.3 31.6 15.3 5.7%
Haddock 0
0 0
0.1 0
0 0
0
<0.1
<0.1%
Hake 0.3 0.1 1.0 0
0.2 0
0.2 4.0 2.8 1.0%
Monkfish/Goosefish 0
0 0.1 0
0 0
0
<0.1 0.1
<0.1%
Ocean pout 0
<0.1 0
0 0
0 0
0
<0.1
<0.1%
Pollock
<0.1 0.6 0.1 0.1 0.8 0.8 0.3 0.3 0.2 0.1%
Summer flounder 0
<0.1 0
0 0
<0.1 0
0
<0.1
<0.1%
Whiting/Silver hake 5.9 0.5 0.2 0
0.1 0
17.9 8.2 8.1 3.0%
Windowpane 6.5 0.5 0.4 0.5 0.5 2.6 11.4 1.9 2.3 0.9%
Winter flounder 4.5 20.0 34.8 4.9 7.2 15.8 0.1 15.2 9.2 3.4%
Yellowtail flounder 0.9 0
0.1
<0.1
<0.1 2.7 0
0.3 0.4 0.2%
Total (all species) 724.4 268.5 958.5 167.0 123.2 297.2 333.7 523.2 269.4 100%
(a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) Unless otherwise denoted, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra did not conduct bivalve larvae entrainment studies.
(f) NextEra sampled the fourth week in April through the fourth week in October.
(g) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010)
19 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species Species 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Alewife 0
8 1,753 2,797 14 16 4
35 1
9 212 87 American plaice 0
0 0
0 0
2 0
0 0
0 0
3 American sand lance 1,215 1,324 823 182 708 234 423 114 245 3,396 665 1,029 Atlantic butterfish 3
14 3
223 9
5 1
28 1,170 4
35 54 Atlantic herring 0
0 485 350 582 20 5
11 159 198 118 93 Atlantic mackerel 0
0 1
0 0
0 0
1 0
0 4
4 Atlantic menhaden 0
7 97 0
1 957 142 19 1,022 7
361 7,226 Atlantic silverside 5,348 1,621 1,119 210 834 1,335 31 282 1,410 20,507 877 2,717 Atlantic cod 58 119 94 69 38 66 29 30 199 3,091 467 454 Cunner 32 342 1,121 233 309 255 324 341 291 554 625 893 Grubby 2,678 2,415 1,457 430 3,269 3,953 1,174 549 1,089 2,523 676 531 Haddock 0
1 397 0
1 3
2 1
0 0
0 7
Hakes 2,822 2,188 156 122 4
68 113 523 1,813 166 35 11 Monkfish/Goosefish 3
13 0
0 7
17 15 59 18 10 0
8 Northern pipefish 188 579 1,200 243 268 748 370 714 936 2,716 1,413 1,724 Ocean pout 0
6 1
0 7
3 2
21 1
13 3
3 Pollock 1,681 899 1,835 379 536 11,392 534 405 719 499 80 218 Rainbow smelt 545 213 4,489 365 535 100 8
65 323 3,531 2,085 3,314 Red hake 1
16 1,478 371 903 1,120 112 155 52 271 892 821 Rock gunnel 494 1,298 1,122 459 2,929 2,308 1,514 2,251 2,066 6,274 4,137 1,752 Sea raven 78 125 1,015 223 137 132 206 271 166 217 129 221 Scup 0
14 9
0 3
1 0
3 11 11 0
21 Shorthorn sculpin 14 156 282 123 190 296 923 621 642 7,450 876 2,214 Snailfishes 180 165 1,013 351 856 2,356 690 334 616 451 185 442 Summer flounder 3
0 0
0 0
0 0
0 0
0 0
0 Threespine stickleback 67 155 320 174 773 506 10 280 34 1,549 130 307 Whiting/Silver hake 0
49 58 108 13 100 41 5
1,177 22 212 306 Windowpane 980 943 1,164 1,688 772 692 251 161 2,242 4,749 936 2,034 Winter flounder 1,435 1,171 3,231 468 1,143 3,642 102 777 897 10,491 783 1,875 Yellowtail flounder 0
1,149 4
23 11 97 0
8 5
0 0
0 Total (All taxa) 19,212 15,940 26,825 10,648 15,198 31,241 7,281 8,577 18,413 71,946 16,696 29,368 Source: (NAI 2010) 20 Table D-1-6. Number of impinged fish for the most common taxa impinged and for EFH species (cont.)
Species 2006 2007 2008 2009 Total Percent of Total Annual Average Alewife 255 244 41 0
5,476 1.6%
342 American plaice 0
0 7
0 12 0.0%
0.75 American sand lance 213 2,073 758 796 14,198 4.3%
887 Atlantic Butterfish 44 199 7
29 1,828 0.5%
114 Atlantic herring 189 260 27 490 2,987 0.9%
187 Atlantic mackerel 0
0 0
0 10 0.003%
1 Atlantic menhaden 94 160 67 39 10,199 3.1%
637 Atlantic silverside 788 639 247 525 38,490 11.5%
2,406 Atlantic cod 113 178 73 147 5,225 1.6%
327 Cunner 687 922 731 837 8,497 2.5%
531 Grubby 235 869 3,919 521 26,288 7.9%
1,643 Haddock 3
25 0
15 455 0.1%
28 Hakes 6
1,184 3,216 1,427 13,854 4.1%
866 Monkfish/Goosefish 0
11 0
0 161 0.0%
10 Northern pipefish 1,288 2,374 1,082 698 16,541 5.0%
1,034 Ocean pout 6
3 0
0 69 0.0%
4 Pollock 73 340 123 657 20,370 6.1%
1,273 Rainbow smelt 878 572 421 43 17,487 5.2%
1,093 Red hake 546 1,389 14 0
8,141 2.4%
509 Rock gunnel 3,782 3,174 937 701 35,198 10.5%
2,200 Sea raven 138 164 138 79 3,439 1.0%
215 Scup 4
8 13 15 113 0.0%
7 Shorthorn sculpin 1,258 465 1,515 266 17,291 5.2%
1,081 Snailfishes 330 76 233 85 8,363 2.5%
523 Summer flounder 4
0 0
0 7
0.0%
0 Threespine stickleback 139 193 80 118 4,835 1.4%
302 Whiting/Silver hake 31 21 204 325 2,672 0.8%
167 Windowpane 572 1,502 1,640 427 20,753 6.2%
1,297 Winter flounder 767 3,949 1,920 655 33,306 10.0%
2,082 Yellowtail flounder 10 11 3
0 1,321 0.4%
83 Total (All taxa) 12,955 22,472 17,935 9,304 334,011 100.0%
20,876 Source: (NAI 2010)
21 Table D-1-7. Number of bivalve larvae entrained (x 109)
Taxon 1990(a) 1991(b) 1992(c) 1993(d) 1995 1996 1997 1998 1999 2000 2001 2002 2003 Prickly jingle 1,691 250.8 6.9 3,923 8,906 23,522 2,883 3,827 36,495 7542 4,129 8,204 3,218.1 Bivalvia mussels 181.7 38.1 14.5 334.5 797.1 671.4 71.1 64.5 651.3 228.6 483 194.2 73.7 Rock borer 876.6 421.3 189.8 2,406 2,598 4,670 923.7 609.7 4,417 1,921 1,575 567.3 1,203.9 Northern horsemussel 909.7 160.2 0.3 1,284 546.4 5,145 614.7 241.7 2,376 2,521 251.6 776.4 240.8 Soft shell clam 8.1 0.6 0.2 22.5 4.3 33.2 53.7 11.4 45.7 23.9 26.4 60.2 5.1 Truncate softshell clam 249.2 6.5 1.1 2.1 27.6 123 0.8 8.3 66 34.9 26.3 1.9 13.8 Blue mussels 3,991 1,688 121.9 10,051 13,231 17,932 1745 1,493 22,374 10,255 9621 3,318 2,199 Atlantic Sea scallop 0.7 0.7 0.1 16.9 6.2 31 0.8 0.8 11.5 9.9 8.5 0.8 0
Solenidae clams 61.1 0
75.7 102.5 1092 241.9 49.5 20.9 773.2 150.4 922.9 150.8 85.5 Atlantic Surf clam 69 4.4 0
48.5 112.5 171.1 22.5 14.8 175.5 33.6 50.8 44.2 3.1 Shipworm 0.01 15.9 0
0 4.8 7.4 1.7 0.8 29.9 1.5 0.3 2.3 0.1 Total (all taxon) 8,039 2,586 410 18,190 27,327 52,547 6,366 6,293 67,415 22,721 17,095 13,320 7,043 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) In 1994, NextEra did not conduct bivalve larvae entrainment studies. Unless otherwise denoted for all other years,, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra sampled the fourth week in April through the fourth week in October.
(f) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010) 22 Table D-1-7. Number of bivalve larvae entrained (x 109) (cont.)
Taxon 2004 2005(e) 2006(f) 2007 2008 2009 Average Prickly jingle 2,595 1,217 3,966 3,950 18,452 27,733 8,553.2 Bivalvia mussles 89.6 40.4 73.9 46.2 411.8 74.3 238.94 Rock borer 1,024 352.9 604.6 650.7 3,137 2,548 1,615.5 Northern horsemussel 843.2 292.9 715.1 172.5 2,270 1421 1,093.8 Soft shell clam 15.1 9.2 11.1 4.7 45.8 31.8 21.737 Truncate softshell clam 5.2 2.3 0.6 3
6.4 4.8 30.726 Blue mussels 1,526 921.5 1,351 834.4 2,700 3,974 5,754 Atlantic Sea scallop 0.7 0.1 0
0.1 0.3 1.2 4.7526 Solenidae clams 113.4 57.9 65.2 156.1 85.1 162.4 229.83 Atlantic Surf clam 10 14.5 20 2.8 100.7 31.5 48.921 Shipworm 0.6 0.3 0.8 0
1.8 2.3 3.7111 Total (all taxon) 6,223 2,909 6,809 5,820 27,211 35,983 17,595 (a) NextEra sampled June-October.
(b) NextEra sampled the last week in April through the first week in August.
(c) NextEra sampled the third week in April through the third week in June.
(d) In 1994, NextEra did not conduct bivalve larvae entrainment studies. In all other years, NextEra sampled the third week in April through the fourth week in October.
(e) NextEra sampled the fourth week in April through the fourth week in October.
(f) NextEra sampled the fourth week in April through the fourth week in September.
Source: (NAI 2010)
23 Padmanabhan and Hecker (1991) conducted a thermal plume modeling and field verification study. This study estimated a temperature rise of approximately 36 to 39° F (20 to 22° C) at the diffusers (Padmanabhan and Hecker 1991). Field and modeling data indicated that the water rose relatively straight to the surface and spread out within 10 to 16 ft (3 to 5 m) of the ocean surface. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Padmanabhan and Hecker (1991) did not observe significant increases in surface temperature 1,640 ft (500 m) to the northwest of the discharge structure.
NextEra has conducted monitoring of water temperature at bottom and surface waters near the discharge structure during operations (NAI 2001, 2010). NextEra monitored bottom water temperature at a site 656 ft (200 m) from the discharge and at a site 3 to 4 nautical mi (5 to 8 km) from the discharge from 1989 to 1999 (NAI 2001). NextEra observed a significant difference in the monthly mean bottom water temperature between the two sites. The mean difference was less than 0.9° F (0.5° C) (NAI 2001). As required by Seabrooks NPDES permit, NextEra conducts continuous surface water monitoring. The mean difference in temperature between a sampling station within 328 ft (100 m) of the discharge and a sampling station 1.5 mi (2.5 km) to the north has not exceed 5° F (2.8° C) since operations began, which is the limit identified in the NPDES permit (EPA 2002a; NAI 2001, 2010). For the majority of months between August 1990 and December 2009, the monthly mean increase in the surface water temperature was less than 3.6° F (2.0° C).
Based on Seabrooks water quality monitoring and Padmanabhan and Heckers (1991) study, the habitat most likely affected by the thermal plume would be the upper water column (10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge (less than 328 ft (100 m)). Fish may avoid this area, but the thermal plume would not likely block fish movement because fish could swim around the thermal plume. Pelagic fish species that may avoid this area are discussed, as appropriate, in the species analysis below (Sections D-1.3.3.1 through D-1.3.3.19). Benthic species, or species that primarily reside at the seafloor, may also avoid the immediate area surrounding the discharge structures due to higher temperature, velocities, and turbulence. This area should be considerably smaller than the area of increased temperature at the surface.
To examine the potential thermal impacts from plant operations on sessile species (and as an indicator of thermal impacts to other biological groups), NAI (2010) compared the abundance of cold water and warm water macroalgae species prior to and during operations at sites near the discharge structure (the nearfield site) and at sites approximately 3 to 4 nautical mi (5 to 8 km) from the intake and discharge structures (the farfield site). Benthic perennial algae are sensitive to changes in water temperature because they are immobile and live more than 2 years. Prior to operations, NAI (2010) collected six uncommon species not collected during operations, including the brown macroalgae Petalonia fascia, which is associated with cold-water habitat.
During operations, NAI (2010) collected some typically warm-water taxa for the first time (e.g., the red macroalgae Neosiphonia harveyi), collected other warm-water taxa less frequently, and collected some cold-water taxa more frequently. NAI (2010) observed 10 species that only occurred during operations, and NAI (2010) reported that these species were within their geographic ranges. NAI (2010) concluded that the changes in community composition among cold and warm water species were relatively small, although NAI (2010) did not report the results of any statistical tests to examine the significance in such changes.
The NRC staff concluded in the SEIS that thermal impacts from Seabrook operations were SMALL, and operations have not noticeably altered aquatic communities near Seabrook. This conclusion was based on the findings that the thermal plume would not block fish passage and 24 is within the limits of Seabrooks NPDES permit and that there were no clear patterns of emergent warm-water species or changes in the abundance of cold-water species.
Loss of Forage Species. Prey for the 23 EFH species includes phytoplankton, zooplankton (including fish and invertebrate eggs and larvae), juvenile and adult fish, and juvenile and adult invertebrates. Seabrook operations can adversely affect plankton prey if they are entrained in the cooling system or the thermal discharge significantly decreases the quality of the pelagic water habitat. Juvenile and adult fish prey could be affected by Seabrook operations if they are impinged in the cooling water system, if they avoid the area near the discharge because of the heated thermal effluent, or if bottom habitat (e.g., mussel beds or kelp forests) are adversely affected by Seabrook operations. Invertebrate prey could be affected by Seabrook operations if any of the following occurs:
They are entrained in the Seabrook cooling system.
They are mobile and impinged in the Seabrook cooling system.
They are mobile and avoid the area near the discharge structures due to the discharge of heated thermal effluent.
They are sessile, and growth is limited near the discharge structures due to the heated thermal effluent.
Loss of Habitat-Forming Species. In the Gulf of Maine, and the area in the vicinity of Seabrooks intake and discharge structures, rocky subtidal habitats are among the most productive habitats (Mann 1973; Ojeda and
Dearborn 1989). Algae,
mussels, oysters, and other sessile invertebrates attach to the bedrock on the seafloor and form the basis of a complex, multi-dimensional habitat for other fish and invertebrates to use for feeding and hiding from predators (Thompson 2010; Witman and Dayton 2001). Spawning fish, such as herring, shield eggs from currents and predators within rock crevices or sessile organisms attached to the bedrock (Thompson 2010). In soft sediment habitats, shellfish beds form the main biogenic habitats.
Kelp seaweeds, brown seaweeds with long blades, attach to hard substrates and can form the basis of undersea forests, commonly referred to as kelp beds. The long blades of kelpsuch as A. clathratum, L. digitata, and sea beltprovide the canopy layer of the undersea forest, while shorter foliose and filamentous algae, such as Irish moss, grow in between or at the bottom of kelp similar to the understory layer in a terrestrial forest (NAI 2010; Thompson 2010).
The multiple layers of seaweeds provide additional habitat complexity for other fish and invertebrates to find refuge from predators and harsh environmental conditions, such as strong currents or ultraviolet light (Thompson 2010). Seabrooks heated effluent may affect growth of algae and sessile invertebrates. These groups may be particularly sensitive to changes in water quality because they are sessile and cannot move to avoid the area, sufficient light must reach the algae for the plant to photosynthesize, and particulars in the water can clog the feeding structures of sessile invertebrates that filter seawater for food.
D-1.3.2.2 Combined Impacts (Monitoring Data)
This section presents NextEra monitoring data of selected groups prior to and during operations at sampling sites near the intake and discharge structures (nearfield sampling sites) and at sampling sites 3 to 4 mi (5 to 8 km) away (farfield sampling sites) (Figure D-1-7). Monitoring data may indicate if the combined impacts (or cumulative impacts) from Seabrook operation have resulted in the decline of a species or biological group due to a decline in habitat quantity or quality.
25 Figure D-1-7. Sampling Stations for Seabrook Station aquatic monitoring NAI (2010) used a before-after control-impact (BACI) design to test for potential impacts from operation of Seabrook. This monitoring design was used to test for the statistical significance of differences in community structure, species abundance, or species diversity between the pre-operational and operational period at the nearfield and farfield sites. Statistically significant 26 differences could result from entrainment, impingement, thermal impacts, loss of forage species, loss of habitat-forming species, or any combination of these effects of Seabrook operations.
Working with NAI and Public Service of New Hampshire staff, NextEra selected farfield sampling sites that would likely be outside the influence of Seabrook operations (NextEra 2010a). The farfield sampling stations were between 3 and 4 nautical mi (5 and 8 km) north of the intake and discharge structures. NextEra selected a northern farfield location because the primary currents run north to south. NextEra selected specific farfield sampling sites based on similarities with the nearfield sampling sites regarding depth, substrate type, algal composition, wave energy, and other relevant factors (NextEra 2010a).
Sections 2.2.6.3 and 4.5.5 of the SEIS describe the sampling methods, statistical methods, and monitoring results. Below is a brief summary of the monitoring results for phytoplankton, zooplankton, fish, invertebrates, and macroalgae.
Phytoplankton. NAI (1998) found no significant differences in phytoplankton abundance or chlorophyll a concentrations between the nearfield and farfield sites or between before and during plant operation. NAI (1998) observed minimal changes in species composition prior to and during operations. These results suggest that Seabrook operations have not adversely affected phytoplankton abundance near Seabrook.
Zooplankton. NAI (2010) did not find a significant difference in the density of holoplankton or meroplankton taxa prior to and during operations or between the nearfield and farfield sampling sites. The average density of all hyperbenthos species at the nearfield site was generally an order of magnitude larger than the abundances found at the farfield site both prior to and during operations (NAI 2010).
When examining total bivalve larvae density, NAI (2010) did not find a significant difference between sampling sites prior to and during operations. For fish eggs and larvae, NAI (2010) observed no significant difference between sampling sites, but the study reported a significant difference prior to and during operations in the density of fish eggs and larval species (Table D-1-8).
Table D-1-8. Mean density (No./1,000m3) and upper and lower 95% confidence limits (CL) of the most common fish eggs and larvae from 1982-2009 monitoring data at Seabrook Taxon Group 1(a)
Group 2 (a)
Lower 95%
CL Mean Upper 95%
CL Lower 95%
CL Mean Upper 95%
CL Eggs(b)
Atlantic mackerel 650 1,009 1,369 1,344 1,941 2,538 Cunner/Yellowtail flounder 2,764 5,003 7,243 6,577 7,239 8,081 Hakes 235 1,226 2,217 332 488 643 Hake/Fourbeard rockling 45 215 386 503 626 749 Atlantic cod/haddock 79 153 226 63 92 120 Windowpane 73 147 221 160 232 304 Fourbeard rockling 168 248 328 34 49 65 Silver hake 45 77 109 149 322 494 Larvae(c)
Cunner 143 425 707 828 1,386 1,945
27 Taxon Group 1(a)
Group 2 (a)
Lower 95%
CL Mean Upper 95%
CL Lower 95%
CL Mean Upper 95%
CL American sand lance 57 182 307 160 234 308 Atlantic mackerel 28 179 330 65 121 176 Fourbeard rockling 40 68 96 56 78 99 Atlantic herring 37 68 99 23 29 35 Rock gunnel 14 31 49 32 42 52 Winter flounder 18 44 70 8
11 14 Silver hake 14 23 32 35 67 100 Radiated shanny 15 26 36 3
27 50 Witch flounder 9
18 28 3
5 6
(a) NAI (2010) determined groups using a cluster analysis (numerical classification) and non-metric multi-dimensional scaling (MDS) of the annual means (log (x+1)) of each taxon at each station.
(b) Egg Group 1 years = 1983, 1984, 1986, 1987; Group 2 years = 1988-2008 (c) Larvae Group 2 years = 1982-1984, 1986-1989; Group 2 years = 1989-1991, 1993-2009 Source: (NAI 2010)
Because changes in community structure occurred at nearfield and farfield sampling sites, these results suggest that Seabrook operations have not adversely affected zooplankton near Seabrook.
Juvenile and Adult Fish. NextEra monitored the abundance of juvenile and adult fish prior to and during operations at nearfield and farfield sites using benthic trawls (Table D-1-9), gill nets (Table D-1-10), and seine pulls in the Hampton-Seabrook Estuary (Table D-1-10). For the majority of fish species, the abundance was higher prior to operations than during operations at both the nearfield and farfield sites. The abundance of a few fish species increased during operations at both nearfield and farfield sites.
Table D-1-9. Geometric mean catch per unit effort (CPUE) (No. per 10-minute tow) and upper and lower 95% CL during preoperational and operational monitoring years for the most abundant species Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95%
CL Mean Upper 95% CL Yellowtail flounder Nearfield (T2) 2.7 3.7 5.0 0.1 0.2 0.3 Farfield (T1) 15.7 20.6 26.9 1.8 2.4 3.1 Farfield (T3) 6.6 9.2 12.8 1.4 2.1 3.0 Longhorn sculpin Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.6 1.0 1.5 0.4 0.6 0.8 2.3 3.2 4.5 2.3 3.1 4.1 4.2 6.1 8.5 4.8 6.4 8.4 Winter flounder Nearfield (T2)
Farfield (T1)
Farfield (T3) 3.7 5.5 8.0 1.6 2.3 3.1 2.1 2.8 3.6 3.0 4.0 5.4 1.1 1.4 1.9 2.7 3.6 4.8 28 Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95%
CL Mean Upper 95% CL Hake Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.6 0.9 1.2 0.3 0.4 0.5 1.3 1.7 2.0 0.4 0.6 0.8 0.8 1.1 1.4 0.4 0.9 1.4 Atlantic cod Nearfield (T2)
Farfield (T1)
Farfield (T3) 0.5 0.8 1.2 0.1 0.2 0.4 1.7 2.6 3.7 0.2 0.3 0.5 2.6 4.1 6.2 0.8 1.1 1.5 Raja sp.
Nearfield (T2) 0.4 0.6 0.7 0.4 0.7 0.9 Farfield (T1) 0.8 1.4 2.3 1.6 2.2 2.9 Farfield (T3) 2.0 2.6 3.2 2.6 3.5 4.7 Windowpane Nearfield (T2) 0.8 1.2 1.6 0.7 1.0 1.3 Farfield (T1) 1.1 1.6 2.3 1.4 1.8 2.2 Farfield (T3) 0.6 0.9 1.4 1.0 1.7 2.6 Rainbow smelt Nearfield (T2) 2.2 3.2 4.3 0.3 0.5 0.8 Farfield (T1) 1.6 2.3 3.1 0.4 0.6 0.9 Farfield (T3) 0.9 1.6 2.5 0.4 0.6 0.8 Ocean pout Nearfield (T2) 0.6 0.8 1.0 0.2 0.2 0.3 Farfield (T1) 0.6 0.7 1.0 0.1 0.1 0.2 Farfield (T3) 1.4 1.8 2.3 0.1 0.2 0.3 Silver hake Nearfield (T2) 0.0 0.1 0.1 0.0 0.0 0.1 Farfield (T1) 0.1 0.2 0.4 0.3 0.6 0.9 Farfield (T3) 0.1 0.2 0.3 0.1 0.3
0.6 Source
(NAI 2010)
Table D-1-10. Geometric mean CPUE (No. per 24-hr surface and bottom gill net set) and coefficient of variation (CV) during preoperational (1976-1989) and operational monitoring years (1990-1996)
Species Sample site Preoperational monitoring Operational monitoring Mean CV Mean CV Atlantic herring Nearfield (G2) 1.1 20 0.2 33 Farfield (G1) 1.0 18 0.3 22 Farfield (G3) 1.2 21 0.4 25 Atlantic mackerel Nearfield (G2)
Farfield (G1)
Farfield (G3) 0.2 15 0.3 29 0.2 16 0.3 17 0.3 16 0.3 15 Pollock Nearfield (G2)
Farfield (G1) 0.3 10 0.3 16 0.2 17 0.2 18
29 Species Sample site Preoperational monitoring Operational monitoring Mean CV Mean CV Farfield (G3) 0.3 13 0.2 13 Spiny dogfish Nearfield (G2)
Farfield (G1)
Farfield (G3)
<0.1 35 0.1 41
<0.1 45 0.1 69
<0.1 27 0.2 47 Silver hake Nearfield (G2)
Farfield (G1)
Farfield (G3) 0.2 35 0.1 60 0.2 34 0.1 40 0.3 31 0.1 31 Blueback herring Nearfield (G2) 0.3 18 0.2 26 Farfield (G1) 0.2 17 0.2 50 Farfield (G3) 0.3 24 0.2 32 Alewife Nearfield (G2) 0.1 14 0.1 21 Farfield (G1) 0.1 17 0.1 34 Farfield (G3) 0.1 21 0.1 35 Rainbow smelt Nearfield (G2) 0.1 21 0.1 29 Farfield (G1)
<0.1 26 0.1 40 Farfield (G3) 0.1 21 0.1 39 Atlantic cod Nearfield (G2)
<0.1 22
<0.1 63 Farfield (G1) 0.1 18
<0.1 53 Farfield (G3) 0.1 13
<0.1 63 Source: (NAI 1998)
NAI (2010) reported different trends at farfield and nearfield sites for winter flounder, silver hake, and rainbow smelt during trawling surveys (Table D-1-9). At the nearfield site (T2), the abundance of winter flounder significantly decreased over time from a mean CPUE of 5.5 prior to operations to 2.3 during operations. However, at both farfield sampling sites (T1 and T3), the mean CPUE increased from 2.8 and 1.4 prior to operations, respectively, to 4.0 and 3.6 during operations. This increase was statistically significant at one of the farfield sites (T3). Silver hake abundance also increased at farfield sampling sites and decreased at the nearfield sampling site. NAI (2010) did not report if these trends were statistically significant. Rainbow smelt abundance decreased at all sampling sites, but the decrease was significantly greater at the nearfield site compared to the farfield sites (NAI 2010).
NAI (2010) reported different trends at farfield and nearfield sites for American sand lance abundances during seine pulls in the Hampton-Seabrook Estuary (Table D-1-11). At the nearfield sampling station (S2), the abundance of American sand lance decreased over time from a mean CPUE of 0.2 prior to operations to 0.1 during operations. At both farfield sampling sites (S1 and S3), the mean CPUE increased from 0.1 prior to operations, to 0.2 and 0.6, respectively, during operations. NAI (2010) did not report if these trends were statistically significant.
30 Table D-1-11. Geometric mean CPUE (No. per seine haul) and upper and lower 95% CL during preoperational and operational monitoring years Species Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95% CL Mean Upper 95% CL Atlantic silverside Nearfield (S2) 5.1 6.8 9.1 2.4 3.1 4.1 Farfield (S1) 5.1 7.2 10.2 3.6 4.8 6.2 Farfield (S3) 4.0 6.7 10.7 2.1 2.9 3.9 Winter flounder Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.6 1.0 1.5 0.1 0.2 0.3 0.6 0.9 1.2 0.2 0.4 0.5 2.2 3.2 4.4 0.3 0.5 0.7 Killifishes Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.6 1.2 2.0 0.1 0.2 0.3 0.8 1.1 1.5 0.5 0.9 1.3
<0.1
<0.1 0.1 0.1
<0.1 0.1 Ninespine stickleback Nearfield (S2)
Farfield (S1)
Farfield (S3) 0.3 0.8 1.6
<0.1 0.1 0.1 0.4 0.7 1.2 0.1 0.2 0.3 0.3 0.8 1.4 0.1 0.2 0.3 Rainbow smelt Nearfield (S2)
Farfield (S1)
Farfield (S3)
<0.1 0.2 0.3 0.1 0.1 0.2
<0.1 0.1 0.2
<0.1 0.1 0.2 0.3 0.7 1.2 0.1 0.2 0.4 American sand lance Nearfield (S2) 0.0 0.2 0.5 0.0 0.1 0.1 Farfield (S1)
<0.1 0.1 0.2 0.1 0.2 0.3 Farfield (S3)
<0.1 0.1 0.2 0.3 0.6 0.9 Pollock Nearfield (S2)
<0.1 0.2 0.3 0.0
<0.1
<0.1 Farfield (S1)
<0.1 0.1 0.2
<0.1
<0.1
<0.1 Farfield (S3) 0.1 0.4 0.8
<0.1 0.1 0.1 Blueback herring Nearfield (S2)
<0.1 0.1 0.1
<0.1 0.1 0.1 Farfield (S1) 0.1 0.2 0.3 0.1 0.3 0.4 Farfield (S3)
<0.1 0.1 0.3
<0.1
<0.1 0.1 Atlantic herring Nearfield (S2) 0.1 0.3 0.5
<0.1
<0.1 0.1 Farfield (S1) 0.0 0.1 0.5 0.1 0.2 0.3 Farfield (S3) 0.1 0.1 0.2
<0.1 0.1 0.2 Alewife Nearfield (S2) 0.0 0.1 0.2
<0.1
<0.1
<0.1 Farfield (S1)
<0.1 0.1 0.2 0.1 0.2 0.4 Farfield (S3)
<0.1 0.1 0.1 0.0 0.1
0.2 Source
(NAI 2010)
NextEra monitoring results suggest that Seabrook operations have not likely affected most fish species near Seabrook. However, the abundance of winter flounder and rainbow smelt has decreased to a greater and observable extent near Seabrooks intake and discharge structures compared to 3 to 4 mi (5 to 8 km) away. The local decrease suggests that, to the extent local
31 subpopulations exist within 3 to 4 mi (5 to 8 km) of Seabrook, they have been adversely affected through operation of Seabrooks cooling water system.
Invertebrates. NAI (2010) reported similar trends of total invertebrate density and species diversity at the nearfield and farfield sampling sites before and during operations. Likewise, NAI (2010) reported similar trends at the nearfield and farfield sampling sites prior to and during operations for mytilid (mussel) spat, rock crabs, Jonah crabs, northern horse mussels, sea stars, green sea urchin, lobsters, and soft shell clams.
Macroalgae. NAI (2010) observed significant changes in kelp density prior to and during operations (Table D-1-12). NAI (2010) reported significantly higher Laminaria digitata density prior to than during operations. In the shallow and the mid-depth subtidal, the decline at the nearfield sampling site was significantly greater than the decline at the farfield station. In the nearfield mid-depth sampling site (B19), NAI (2010) did not identify L. digitata in 2008 or 2009.
The density of Agarum clathratum, which competes with L. digitata, significantly increased over time in the mid-depth sampling stations, and density was significantly higher at the nearfield site (NAI 2010).
Table D-1-12. Kelp density (No. per 100 m2) and upper and lower 95% CL during preoperational and operational monitoring years Kelp Sample site Preoperational monitoring Operational monitoring Lower 95% CL Mean Upper 95% CL Lower 95% CL Mean Upper 95% CL L. digitata Nearfield Shallow (B17) 140.6 213.9 287.3 5.3 15.2 25.2 Farfield Shallow (B35) 96.5 155.8 215.1 52.3 73.9 95.6 Nearfield Mid-depth (B19) 81.5 139.9 198.3 3.1 7.5 11.9 Farfield Mid-depth (B31) 401.6 500.2 598.7 106.0 157.7 209.5 Sea belt Nearfield Shallow (B17) 270.7 415.1 559.4 66.1 137.9 209.7 Farfield Shallow (B35) 210.9 325.7 440.5 247.8 326.0 404.2 Nearfield Mid-depth (B19) 2.0 59.1 116.3 1.5 10.1 18.7 Farfield Mid-depth (B31) 59.6 95.5 131.5 29.3 48.2 68.2 A. esculenta Nearfield Mid-depth (B19) 0.0 2.4 7.2 0.3 2.3 4.2 Farfield Mid-depth (B31) 19.9 75.2 130.5 20.3 40.0 59.6 A. clathratum Nearfield Mid-depth (B19) 613.5 786.6 959.6 792.2 955.2 1,118.1 Farfield Mid-depth (B31) 280.2 366.4 452.6 407.3 503.6 599.9 Source: (NAI 2010)
In the shallow subtidal, sea belt (Saccharina latissima) density was significantly lower during operations at the nearfield site, but there was no significant change at the farfield site (NAI 2010). In the mid-depth subtidal, sea belt density significantly decreased at both sampling sites (NAI 2010). In the mid-depth subtidal, Alaria esulenta significantly declined during operations at the farfield site and remained at a low density at the nearfield site prior to and during operations (NAI 2010). NAI (2010) did not identify A. esulenta at the nearfield sampling station over the past 4 years.
The decrease in L. digitata density was significantly greater at the nearfield sites, and sea belt density was lower during operations at the nearfield site but not at the farfield site in the shallow 32 subtidal. These results suggest that the local population of L. digitata and sea belt has been adversely affected through operation of Seabrooks cooling water system.
D-1.3.3 Adverse Effects on Essential Fish Habitat by Species D-1.3.3.1 American Plaice (Hippoglossoides platessoides) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated American plaice juvenile and adult EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed American plaice juveniles and adults or both in 110 percent of trawling samples from the 1970s through 2009 (Table D-1-2).
Species Description. American plaice are arctic-boreal pleuronectid flatfish (Johnson 1995).
American plaice inhabit both sides of the Atlantic Ocean. In the western Atlantic, American plaice are common from Newfoundland, Canada to Montauk Point, NY (Bigelow and Schroeder 1953; Johnson 2005). EFH for American plaice juveniles and adults includes bottom habitats with fine-grained, sandy, or gravel substrates in the Gulf of Maine (NMFS 2011c).
American plaice are relatively sedentary, and tagging studies have indicated that few migrate long distances. Fisheries and Oceans Canada (DFO) (1989, cited in Johnson 2005) recaptured the majority of tagged fish within 30 mi (48 km) of the tagging site after 7 to 8 years.
American plaice consume a wide-variety of prey and are opportunistic feeders, in that they will consume what is most available (Johnson 2005). Prior to settling on the ocean floor, juveniles feed on small crustaceanssuch as cumaceansand polychaetes (Bigelow and Schroeder 1953). Adults are primarily benthic but, at night, may migrate up into pelagic waters to prey on non-benthic species (DFO 1989, cited in Johnson 2005). During monitoring surveys, NAI (2010) did not observe American plaice in pelagic waters. Prey for adults include mostly echinoderms (e.g., sand dollars, sea urchins, and brittle stars) and crustaceans, cnidarians, and polychaetes (Johnson 2005). Redfish eat American plaice larvae, and goosefish, halibut, cod, and other bottom feeders prey on the adults (Johnson 2005).
Status of the Fishery. NMFS, the New England Fishery Management Council (NEFMC), and the Mid-Atlantic Fishery Management Council (MAFMC) currently manage the northeast multispecies fisheries management plan (FMP). The U.S. fishery for American plaice started to develop around 1975 in the Gulf of Maine, when other commercially desirable flatfish (e.g., yellowtail flounder, winter flounder, and summer flounder) began to decrease in abundance (Sullivan 1981, cited in Johnson 2005). American plaice populations in the western North Atlantic have declined dramatically since the early 1980s (Johnson 2005). Contributing factors to the decline are likely overfishing, changes in water temperature, and water pollution (Johnson 2005). American plaice is also bycatch for other fisheries. In New England, the mortality of American plaice bycatch was positively correlated with ondeck sorting time (Johnson 2005). In 2009, NEFMC considered American plaice overfished (NMFS 2010b).
Entrainment and Impingement at Seabrook. Although NMFS has not designated EFH for American plaice eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of American plaice eggs varied from 0.4 million in 1994 to 52.3 million in 1992 (NAI 2010). Annual average entrainment of American plaice eggs was 25.9 million per year (Table D-1-4). American plaice eggs comprised approximately 3 percent of the total fish eggs entrained at Seabrook.
Entrainment of American plaice larvae varied from 0 in 1994 to 11.5 million in 2009 (NAI 2010).
Annual average entrainment of American plaice larvae was 4.3 million per year (Table D-1-5).
American plaice larvae comprised approximately 1.5 percent of the total fish larvae entrained at Seabrook.
33 Impingement of American plaice varied from zero in several years to seven in 2008 (NAI 2010).
Annual average impingement was less than one fish per year (Table D-1-6). American plaice comprised less than 1 percent of all impinged fish at Seabrook.
Because entrainment and impingement were relatively low for American plaice compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult American plaice. American plaice are primarily benthic (Johnson 2005). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult American plaice are opportunistic feeds that primarily consume invertebrates, including green sea urchins (Strongylocentrotus droebachiensis) (Johnson 2005). NextEra monitoring data show relatively similar trends of benthic invertebrate abundance, density, and species diversityincluding the abundance of green sea urchinsprior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-Forming Species. American plaice inhabit soft bottom areas, including soft bottom areas that border bedrock (Johnson 2005). Keats (1991) hypothesized that American plaice inhabited areas boarded by bedrock because bedrock is the preferred habitat for green sea urchins, an important prey species for American plaice. Because preferred habitat for American plaice are soft bottom substrates, such as fine sand or gravel, the NRC concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for juvenile and adult American plaice during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of juvenile and adult American plaice prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for American plaice juveniles or adults for the following reasons:
Impingement and entrainment are relatively low.
The thermal plume rises quickly to the surface.
Invertebrate forage species are not likely adversely affected by Seabrook operations.
Preferred habitat does not include shellfish or kelp beds.
D-1.3.3.2 Atlantic butterfish (Peprilus triacanthus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic butterfish EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic butterfish eggs and larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in 1 to 10 percent of gill net samples, juveniles and adults in less than 34 1 percent of trawling samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Adult Atlantic butterfish are pelagic schooling fish that are ecologically important as a forage fish for many larger fishes, marine mammals, and birds. Atlantic butterfish inhabit the Atlantic coast from Newfoundland to Florida, but it is most abundant from the Gulf of Maine to Cape Hatteras (Cross et al. 1999; Overholtz 2006). Adult butterfish migrate seasonally. In the summer, they migrate inshore into bays, estuaries, and coastal waters of southern New England and the Gulf of Maine. In winter, they migrate to the edge of the continental shelf in the Mid-Atlantic Bight (Cross et al. 1999). Adults generally stay within 200 mi (322 km) of the shore.
Butterfish reach sexual maturity between ages 1 to 2 years and rarely live more than 3 years (Overholtz 2006). Adults are 5.9 to 9.1 in. (15 to 23 cm) long on average and can reach a weight of up to 1.1 lb (0.5 kg). Females are broadcast spawners and spawn in large bays and estuaries from June through August. Females generally release eggs at night in the upper part of the water column in water of 59° F (15° C) or more. Eggs are pelagic and buoyant (Cross et al. 1999). Butterfish eggs and larvae are found in water with depths ranging from the shore to 6,000 ft (1,828 m) and at temperatures between 53.6 and 73.4° F (12 and 23° C) for eggs and between 39.2 and 82.4° F (4 and 28° C) for larvae (Cross et al. 1999). Juvenile and adult butterfish are found in waters from 33 to 1,200 ft (10 to 366 m) deep and at temperatures ranging from 37 to 82° F (3 to 28° C) (Cross et al. 1999). In summer, juvenile and adult butterfish can be found over the entire continental shelf, including sheltered bays and estuaries, to a depth of 656 ft (200 m) over substrates of sand, rock, or mud (Cross et al. 1999).
Butterfish prey mainly on urochordates and mollusks, with minor food sources including squid; crustaceans, such as amphipods and shrimp; annelid worms; and small fishes (Bigelow and Schroeder 2002; Cross et al. 1999). In turn, many speciesincluding haddock, silver hake, goosefish, bluefish, swordfish (Xiphias gladuis), sharks, and longfin inshore squideat adult butterfish (Cross et al. 1999).
Status of the Fishery. The Atlantic butterfish has been commercially fished since the late 1800s (Cross et al. 1999). By the mid-1900s, fishing fleets from Japan, Poland, the USSR, and other countries began to target the butterfish and caused a drastic increase in landings (Cross et al. 1999; Overholtz 2006). Landings peaked in 1973 at 75.6 million lb (34,300 metric tons (MT))
(Overholtz 2006). U.S. commercial landings averaged 7.1 million lb (3,200 MT) from 19652002 but have steadily decreased since 1985 (Overholtz 2006). In 2009, NOAA reported a cumulative landing of 0.95 million lb (430 MT), and, as of November 27, 2010, the reported landings for 2010 were 1.2 million lb (550 MT) (NOAA 2009, 2010). Butterfish are also caught as bycatch in other fisheries. Bycatch landings averaged 9.3 million lb (4,200 MT) per year from 1996 through 2002 (Overholtz 2006).
The MAFMC manages the Atlantic butterfish under an FMP that includes the Atlantic mackerel, squid, and butterfish. The Atlantic butterfish fishery is capped by an annual coast-wide quota.
A directed fishery for butterfish is open from January through August; however, most butterfish are harvested as bycatch in squid fisheries (NOAA 2010a). In 2009, NEFMC reported butterfish to be overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of Atlantic butterfish eggs varied from 0 in several years to 400,000 in 2005 (NAI 2010). Annual average entrainment of Atlantic butterfish eggs was 25,500 per year from 1990 through 2009 (Table D-1-4). Entrainment of Atlantic butterfish larvae varied from 0 in several years to 1.19 million in 2007 (NAI 2010). Annual average entrainment of Atlantic butterfish larvae was 90,000 per year from 1990 through 2009
35 (Table D-1-5). Atlantic butterfish eggs and larvae comprised less than 0.05 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic butterfish varied from 1 in 2000 to 1,170 in 2002 (NAI 2010). Annual average impingement was 114 fish per year from 1994 through 2009 (Table D-1-6). Atlantic butterfish comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic butterfish compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for all life stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Impacts. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to butterfish eggs, larvae, juveniles, or adults. As described above, the habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m)) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F (2.8° C) in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Butterfish are most common near Seabrook from August through November, when the surface temperature near Seabrook ranges from 46.4 to 65.8° F (8 to 18.8° C) (NAI 2001). Butterfish eggs and larvae are found in water at temperatures between 53.6 and 73.4° F (12 and 23° C) for eggs and between 39.2 and 82.4° F (4 and 28° C) for larvae (Cross et al. 1999). Juvenile and adult butterfish are found in waters at temperatures ranging from 37 to 82° F (3 to 28° C) (Cross et al. 1999). With a temperature rise of 3 to 5° F (1.7 to 2.8° C) at the surface near Seabrook, the thermal plume near the surface from August through November would be within the range of temperature that butterfish eggs, larvae, juveniles, and adults typically inhabit. Therefore, the NRC staff concludes that the increased temperatures of Seabrooks effluent are not likely to adversely affect EFH for all stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic butterfish primarily prey on invertebrates (Bigelow and Schroeder 2002; Cross et al. 1999). NextEra monitoring data show relatively similar trends of benthic invertebrate density and species diversity prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. All life stages of Atlantic butterfish are primarily pelagic (Cross et al. 1999), suggesting that they rarely use benthic habitats such as shellfish and kelp beds.
Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for all life stages of Atlantic butterfish during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic butterfish eggs, larvae, juveniles, or adults prior to and during operations (NAI 2010).
Conclusion Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for all life stages of Atlantic butterfish for the following reasons:
36 Impingement and entrainment are relatively low for Atlantic butterfish.
The increased temperature within the thermal plume at the surface would be with the range of temperatures that Atlantic butterfish inhabit.
Invertebrate forage species are not likely to be adversely affected by Seabrook operations.
Their preferred habitat does not include shellfish or kelp beds.
D-1.3.3.3 Atlantic cod (Gadus morhua) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic cod EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic cod eggs and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, juveniles and adults in 1 to 10 percent of gill net samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Atlantic cod are demersal and highly targeted commercially. Atlantic cod inhabit the northwestern Atlantic Ocean, from Greenland to Cape Hatteras, NC. In the U.S., the highest densities of Atlantic cod are on Georges Bank and the western Gulf of Maine, in waters between 33 and 492 ft (10 and 150 m) with rough bottoms and at temperatures between 32 and 50° F (0 and 10° C) (Lough 2004). Offshore New England, juvenile and adult Atlantic cod move seasonally in response to temperature changes, whereby Atlantic cod typically move into coastal waters during the fall and deeper waters during spring. At the extremes of their range, including Labrador and south of the Chesapeake, Atlantic cod migrate annually (Lough 2004).
In Gulf of Maine, Atlantic cod reach sexual maturity at 2.1 to 2.9 years at lengths between 13 and 17 in. (32 and 44 cm) (Lough 2004). Females spawn during winter and early spring in bottom waters generally between 41 and 44.6° F (5 and 7° C). A large female may produce as many as 3 to 9 million eggs (Lough 2004). Eggs and larvae for the first 3 months are pelagic (Lough 2004). Once larvae reach 1.6 to 2.4 in. (4 to 6 cm), they begin to descend towards the seafloor. As Atlantic cod develop into juveniles and adults, they are able to withstand deeper, colder, and more saline water, and they become more widely distributed (Lough 2004).
Complex substrate and vegetation provides refuge from predators for juvenile cod (Lough 2004).
Forage species tend to vary by life stage and location (Lough 2004). Juveniles and younger adults tend to consume pelagic and benthic invertebrates, while adult cod feed on both crustaceans and other fish, including cancer crabs, brittle stars, American sand lance, Atlantic herring, and American plaice (Johnson 2005; Lough 2004; Witman and Sebens 1992). Atlantic herring and Atlantic mackerel can be important predators of Atlantic cod larvae (Lough 2004).
Silver hake, sculpin, larger cod, and other fish consume juvenile Atlantic cod (Edwards and Bowman 1979, cited in Lough 2004). Winter skate, silver hake, sea raven, longfin inshore squid, Atlantic halibut, fourspot flounder, and large adult cod consume smaller adult cod (Lough 2004).
Status of the Fishery. Atlantic cod has been a highly targeted species since the 1700s. As a likely result of harvesting older and larger fish or due to intense exploitation in stock biomass, the size and age at maturity for Atlantic cod has declined in recent decades (Lough 2004).
Currently, Atlantic cod is managed as two stocks within U.S. waters: (1) the Gulf of Maine and (2) Georges Bank and southward (Mayo 1995). In 2009, NEFMC reported Atlantic cod to be subject to overfishing (NMFS 2010b).
37 Entrainment and Impingement. Entrainment of Atlantic cod eggs varied from 0.2 million in 1994 to 77.8 million in 2002 (NextEra 2010a). Annual average entrainment of Atlantic cod eggs was 32.6 million per year from 1990 through 2009 (Table D-1-4). Atlantic cod eggs comprised 3.6 percent of the total fish eggs entrained at Seabrook from 1990 through 2009. Entrainment of Atlantic cod larvae varied from 0 in 1994 to 34.6 million in 2002 (NAI 2010). Annual average entrainment of Atlantic cod larvae was 2.8 million per year from 1990 through 2009 (Table D-1-5). Atlantic cod larvae comprised approximately 1 percent of the total fish larvae entrained at Seabrook from 19902009.
Impingement of Atlantic cod varied from 29 in 2000 to 3,091 in 2003 (NAI 2010). Annual average impingement was 327 fish per year from 1994 through 2009 (Table D-1-6). Atlantic cod comprised less than 2 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic cod compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic cod during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic cod eggs, juveniles, or adults. Seabrooks thermal discharge may reduce available habitat to Atlantic cod larvae.
Atlantic cod eggs and larvae are pelagic (Lough 2004). NEFSC MARMAP ichthyoplankton surveys collected most eggs at temperatures ranging from 39 to 57° F (4 to 14° C), but collected eggs as high as 72° F (22° C) (Lough 2004). NEFSC MARMAP ichthyoplankton surveys collected most larvae from 39 to 52° F (4 to 11° C), but collected larvae as high as 66° F (19° C)
(Lough 2004). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface could exceed the typical range of temperatures that Atlantic cod larvae inhabit.
The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Juvenile and adult Atlantic cod are primarily benthic (Lough 2004), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface and the temperature range of the thermal plume near the surface would be within the typical range for Atlantic cod eggs, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic cod eggs, juveniles, or adults during the remainder of the facilitys operating license or during the proposed license renewal term. Because the thermal plume could exceed the typical range of temperatures that larvae inhabit, the NRC staff concludes that the heated thermal effluent may have minimal adverse effects on Atlantic cod larvae.
Loss of Forage Species. Juveniles and younger adults consume pelagic and benthic invertebrates, while adult cod feed on both crustaceans and other fish (Lough 2004). In the Gulf of Maine, Bowman (1975, cited in Lough 2004) found Atlantic herring to be a primary prey item for Atlantic cod. Link and Garrison (2002) determined that preferred prey in the Gulf of Maine include American sand lance, cancer crabs, and Atlantic herring. NextEra monitoring data show relatively similar trends in the abundance and density of benthic invertebrates (including cancer crabs) and most fish species prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010). Atlantic herring, a primary prey item for Atlantic cod in the Gulf of Maine, was the fifth most commonly entrained larval species, comprising 3.6 percent of all entrained larvae (NAI 2010) (Table D-1-5). Atlantic herring comprised less than 1 percent of all impinged fish (NAI 2010) (Table D-1-6). American 38 sand lance, a preferred prey item for Atlantic cod, was the second most commonly entrained larval species, comprising 10 percent of all entrained larvae (NAI 2010) (Table D-1-5).
American sand lance was the 10th most commonly impinged fish species, comprising 4.3 percent of all impinged fish (NAI 2010) (Table D-1-6).
Because some of the primary and preferred forage fishsuch as Atlantic herring and American sand lanceare regularly entrained and impinged at Seabrook, operations at Seabrook may have a minimal adverse effect on prey abundance for Atlantic cod. Effects would likely be minimal since Atlantic cod consume a variety of species, many of which are not regularly entrained or impinged at Seabrook.
Loss of Habitat-forming Species. Complex substrate and vegetation provide refuge from predators for juvenile cod (Lough 2004). Therefore, juvenile cod likely use macroalgae and shellfish beds near Seabrook. Monitoring studies suggest that Seabrook operations have adversely affected the density of several kelp species near Seabrook. Therefore, Seabrook operations may have a minimal adverse effect on juvenile Atlantic cod habitat. Effects would likely be minimal since juvenile Atlantic cod inhabit a variety of substrates and vegetation to find refuge from predators.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of eggs, larvae, juvenile and adult Atlantic cod prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away. Ichthyoplankton studies indicated that the density of Atlantic cod larvae decreased significantly at both nearfield and farfield sampling sites (NAI 2010) (Table D-1-8). Monitoring data from trawl studies and gill net studies indicate that the abundance of juvenile and adult Atlantic cod also significantly decreased at both nearfield and farfield sampling sites (Tables D-1-9 and D-1-10). The decreased abundance at both nearfield and farfield sampling sites suggest that Seabrook operations have not adversely affected EFH for Atlantic cod within 3 to 4 mi (5 to 8 km) of Seabrook.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for Atlantic cod larvae, juveniles, and adults, because Seabrooks cooling system regularly entrains and impinges preferred forage fish for Atlantic cod, the thermal plume could exceed the typical range of temperatures that larvae inhabit, and because juveniles may use algal habitats that have declined near Seabrook since operations began. Impacts would likely be minimal since Atlantic cod are not commonly entrained or impinged in the Seabrook cooling system, the thermal plume rises quickly to the surface, invertebrate forage species are not likely adversely affected by Seabrook operations, and monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
D-1.3.3.4 Atlantic herring (Clupea harengus) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult Atlantic herring EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic herring in 1 to 10 percent of trawling samples, greater than 10 percent of gill net samples, and in 1 to 10 percent of seine pull samples (Table D-1-2).
Species Description. Adult Atlantic herring are pelagic, schooling fish that inhabit both the eastern and western Atlantic Ocean (Stevenson and Scott 2005). Juveniles migrate nearshore to further offshore seasonally, whereas adult Atlantic herring migrate north-south along the U.S.
and Canadian coasts for feeding, spawning, and overwintering.
39 Larvae develop into juveniles in the spring, at approximately 1.6 to 2.2 in. (40 to 55 mm) length (Stevenson and Scott 2005). Schooling behavior begins once Atlantic herring develop into juveniles (Gallego and Heath 1994). NOAAs Northeast Fishery Science Center (NEFSC) captured juveniles in waters from 35 to 54° F (2 to 12° C) in the spring and from 41 to 63° F (5 to 17° C) in the fall, during bottom trawl surveys from the Gulf of Maine to Cape Hatteras (Stevenson and Scott 2005). Adults occurred in waters from 35 to 55° F (2 to 13° C) in the spring and from 39 to 61° F (4 to 16° C) in the fall (Stevenson and Scott 2005).
Juvenile and adult Atlantic herring are opportunistic feeders and prey on zooplankton. The most common prey items for juveniles include copepods, decapods larvae, barnacle larvae, cladocerans, and molluscan larvae (Sherman and Perkins 1971, cited in Stevenson and Scott 2005). Common prey items for adults include euphausiids, chaetognaths, and copepods (Bigelow and Schroeder 1953; Maurer and Bowman 1975, cited in Stevenson and Scott 2005).
Adults also prey upon fish eggs and larvae, including larval Atlantic cod, herring, sand lance, and silversides (Munroe 2002; Stevenson and Scott 2005).
Atlantic herring are an important component of the Gulf of Maine food web and are preyed upon throughout their life cycle (Stevenson and Scott 2005). Predators include a variety of fish (such as Atlantic cod, silver hake, thorny skate, bluefish, goosefish, weakfish, summer flounder, white hake, Atlantic halibut, red hake, and northern shortfin squid), marine mammals, and sea birds (Stevenson and Scott 2005).
Status of the Fishery. In U.S. waters, NEFMC manage Atlantic herring as a single stock (Stevenson and Scott 2005). In 2009, NEFMC did not consider Atlantic herring overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for Atlantic herring eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. NAI (2010) did not observe entrainment of Atlantic herring eggs from 1990 through 2009. Entrainment of Atlantic herring larvae varied from 0.1 million in 1994 to 28.2 million in 2008 (NAI 2010). Annual average entrainment of Atlantic herring larvae was 9.6 million per year from 1990 through 2009 (Table D-1-5). Atlantic herring larvae comprised approximately 3.6 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic herring varied from 0 in 1994/1995 to 582 in 1998 (NAI 2010). Annual average impingement was 187 fish per year from 1994 through 2009 (Table D-1-6). Atlantic herring comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for Atlantic herring compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for juvenile and adult Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. Seabrooks thermal discharges may reduce available habitat to juvenile and adult Atlantic herring. The habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Adult and juvenile Atlantic herring are most common near Seabrook from April through May, when the surface temperature near Seabrook ranges from 41 to 51° F (5 to 10.7° C) and from October through December, when the surface temperature ranges from 42 to 57.7° F (5.6 to 14.3° C) (NAI 2001). NEFSC trawl surveys captured juveniles in waters up to 54° F (12° C) in the spring and 63° F (17° C) in the fall and 40 adults up to 55° F (13° C) in the spring and up to 61° F (16° C) in the fall (Stevenson and Scott 2005). With a temperature rise of 3 to 5° F (1.7 to 2.8 ° C), the thermal plume near the surface could slightly exceed the typical range of temperature that Atlantic herring juveniles and adults inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Therefore, the NRC staff concludes that the increased temperatures at Seabrook may have a minimal adverse effect on EFH for adult and juvenile Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult Atlantic herring are opportunistic feeders and prey on a wide variety of zooplankton. Adults prey upon fish eggs and larvae, including larval Atlantic cod, herring, sand lance, and silversides (Munroe 2002; Stevenson and Scott 2005).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the zooplankton (NAI 2010). American sand lance larvae, a common prey item for Atlantic herring, were the second most commonly entrained larval species, comprising 10 percent of all entrained larvae (NAI 2010) (Table D-1-5). Other common larval prey, such as Atlantic herring and Atlantic cod larvae, comprised approximately 1 percent or less of the total fish larvae entrained at Seabrook. The NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for adult and juvenile Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the fact that Atlantic herring prey upon a wide variety of fish larvae, and monitoring studies suggest that zooplankton abundance has not been adversely affected by Seabrook operations.
Loss of Habitat-forming Species. Adult and juvenile Atlantic herring are primarily pelagic (Stevenson and Scott 2005), suggesting that they rarely use benthic habitats such as kelp and shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of juvenile and adult Atlantic herring prior to and during operations at sampling sites in Hampton-Seabrook Estuary near a previous discharge location and at sites further away. Monitoring data indicate that the abundance of juvenile and adult Atlantic herring decreased at both nearfield and farfield sampling sites (Table D-1-11). Because NAI (2010) observed similar trends at all sampling sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for adult and juvenile Atlantic herring.
Conclusion. Because of the observations above, and because the thermal plume could increase the temperature near the surface to above the temperature range that Atlantic herring typically inhabit, the NRC staff concludes that Seabrook operations may have a minimal adverse effect on EFH for adult and juvenile Atlantic herring.
D-1.3.3.5 Atlantic mackerel (Scomber scombrus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic mackerel EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Atlantic mackerel eggs and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in less than 1 percent of trawling samples, juveniles and adults in greater than 10 percent of gill net samples, and juveniles and adults in less than 1 percent of seine pull samples (Table D-1-2).
41 Species Description. Atlantic mackerel are pelagic, schooling fish that inhabit the western Atlantic Ocean from the Gulf of St. Lawrence to North Carolina (Studholme et al. 1999). Adults are highly mobile.
In reviewing multiple studies, Studholme et al. (1999) indicated that the age of maturation varies from 1.7 to 3 years of age, depending on the location, size of the year class, and size of the adult stock. In the Gulf of Maine, females spawn from mid-April through June as they migrate from the south (Berrien 1982, cited in Studholme et al. 1999). The Gulf of Maine is not one of the more important spawning grounds (Sette 1950, cited in Studholme et al. 1999). Eggs are pelagic and float in the upper 33 to 49 ft (10 to 15 m) of surface waters (Studholme et al. 1999).
NEFSC collected eggs near the surface at temperatures ranging from 41 to 73° F (5 to 23° C) and larvae from 43 to 72° F (6 to 22° C) as part of the Marine Resources Monitoring, Assessment, and Prediction (MARMAP) offshore ichthyoplankton survey.
Juveniles exhibit schooling behavior at about 1.2 to 2 in. (30 to 50 mm) (Sette 1943, cited in Studholme et al. 1999). NEFSC captured juveniles from 39 to 72° F (4 to 22° C) and adults from 39 to 61° F (4 to 16° C) during 1963 through 1997 bottom trawl surveys. Overholtz and Anderson (1976, cited in Studholme et al. 1999) conducted field studies that indicated that adult Atlantic mackerel are intolerant of temperatures greater than 61° F (16° C).
Atlantic mackerel are opportunistic and filter feed or ingest prey. Larvae feed on copepod nauplii, copepods, and fish larvae (Studholme et al. 1999). Both juveniles and adults prey on a variety of crustaceans, although adults consume a wider variety of prey sizes and items, including fish. Peterson and Ausubel (1984) determined that fish greater than 0.2 in. (5 mm) feed on copepodites of Acartia and Temora, and fish greater than 0.24 in. (6 mm) feed on adult copepods.
Atlantic mackerel is prey to a wide variety of fish, sharks, squid, whales, dolphins, seals, porpoises. Common fish predators include other mackerel, dogfish, tunas, bonito, striped bass, Atlantic cod, swordfish, silver hake, red hake, bluefish, pollock, white hake, goosefish, and weakfish (Studholme et al. 1999).
Status of the Fishery. In U.S. waters, MAFMC and NMFS manage Atlantic mackerel as a single stock (Studholme et al. 1999). In 2009, MAFMC did not consider Atlantic mackerel overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of Atlantic mackerel eggs varied from 0 in 1994 to 673.1 million in 1991 (NAI 2010). Annual average entrainment of Atlantic mackerel eggs was 191.5 million per year from 1990 through 2009 (Table D-1-4). Atlantic mackerel eggs comprised approximately 21.3 percent of the total fish eggs entrained at Seabrook from 1990 through 2009. Entrainment of Atlantic mackerel larvae varied from 0 in several years to 25.7 million in 2009 (NAI 2010). Annual average entrainment of Atlantic mackerel larvae was 2.6 million per year from 1990 through 2009 (Table D-1-5). Atlantic mackerel larvae comprised approximately 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of Atlantic mackerel varied from 0 in several years to 4 in 2004 through 2005 (NAI 2010). Annual average impingement was less than three fish per year from 1994 through 2009 (Table D-1-6). Atlantic mackerel comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Entrainment of Atlantic mackerel larvae and impingement of Atlantic mackerel is small compared to other species impinged at Seabrook. However, Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook. Therefore, the NRC staff concludes that entrainment of Atlantic mackerel eggs may have minimal adverse effects on EFH for Atlantic mackerel during the remainder of the facilitys 42 operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for Atlantic mackerel eggs.
Thermal Effects. Seabrooks thermal discharges may reduce available habitat to adult Atlantic mackerel. The habitat most likely affected by the thermal plume would be the upper water column (within 10 to 16 ft (3 to 5 m) of the ocean surface) in the immediate vicinity of the discharge. At the surface, Padmanabhan and Hecker (1991) observed a temperature rise of 3° F (1.7° C) or more in a 32-ac (12.9-ha) area surrounding the discharge. Seabrooks NPDES permit limits the rise in monthly mean temperature to 5° F in the near field jet mixing region, or within waters less than 3.3 ft (1 m) from the surface. Atlantic mackerel are most common near Seabrook from June through November, when the surface temperature near Seabrook ranges from 46 to 66° F (8 to 18.8° C) (NAI 2001). During ichthyoplankton and trawling surveys, NEFSC captured eggs, larvae, and juveniles in waters up to 72° F (22° C) and adults in waters up to 61° F (16° C) (Studholme et al. 1999). With a temperature rise of 3 to 5° F (1.7 to 2.8° C),
the thermal plume near the surface could exceed the typical temperature range that adult Atlantic mackerel inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991). Therefore, the NRC staff concludes that the increased temperatures at Seabrook may have a minimal adverse effect on EFH for adult Atlantic mackerel during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic mackerel are opportunistic feeders and prey includes plankton, small crustaceans (including copepods), and some fish for larger Atlantic mackerel (Studholme et al. 1999). NextEras monitoring studies show similar trends prior to and during operations at nearfield and farfield sampling sites for changes in abundance, density, and species composition for phytoplankton, zooplankton (including copepods and fish larvae),
invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic mackerel during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Adult and juvenile Atlantic herring are primarily pelagic (Studholme et al. 1999), which suggests that they rarely use benthic habitats such as kelp and shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species is not likely to adversely affect EFH for Atlantic herring during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of Atlantic mackerel eggs, larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the density of eggs and abundance of juveniles and adults increased or remained the same at both nearfield and farfield sampling sites (Tables D-1-8 and D-1-10).
Larval density decreased at both nearfield and farfield sampling sites (Table D-1-8). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for Atlantic mackerel.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for Atlantic mackerel eggs and adults for the following reasons:
The thermal plume could increase the temperature near the surface to above the temperature range that adult Atlantic mackerel typically inhabit.
43 Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook.
The NRC staff concludes that Seabrook operations are not likely to adversely affect Atlantic mackerel larvae and juvenile for the following reasons:
These life stages are not commonly entrained or impinged in the Seabrook cooling system.
The thermal plume would not exceed the typical temperature range that juveniles inhabit.
Forage species are not likely adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
D-1.3.3.6 Atlantic sea scallop (Placopecten magellanicus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult Atlantic sea scallop EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed a relatively low density of Atlantic sea scallop larvae in zooplankton tows (geometric mean density was approximately three to four scallops per 1,000 m3 prior to 2001 and less than one scallop per 1,000 m3 after 2001). Seabrook monitoring does not include juvenile and adult Atlantic sea scallops. Seabrook observations near the intake and discharge structures suggest that sea scallops are not common in this area (NAI 2001).
Species Description. Atlantic sea scallops are bivalve mollusks that occur along the Canadian and U.S. coasts from the Gulf of St. Lawrence south to Cape Hatteras, NC (Hart and Chute 2004).
Sea scallops produce gametes within the first or second year and are among the most fecund of bivalves (Langton et al. 1987). Spawning in Maine occurs from September through October.
Eggs remain demersal until they develop into larvae. The first two larval stages are pelagic and drift with water currents (Hart and Chute 2004). Larvae settle on the sea floor as spat and remain there throughout adult life. Spat that land on sedentary branching plants, animals, or on any other hard surface may have a higher survival rate than those that land in sandy bottom habitats subject to burial (Larsen and Lee 1978).
Juvenile scallops move from the original substrate on which they have settled and attach to shells or bottom debris (Dow and Baird 1960, cited in Hart and Chute 2004). Juveniles also swim to avoid predators and other natural or human-induced disturbances. Tagging studies suggest that adults remain sedentary once an aggregation has formed (Hart and Chute 2004).
Sea scallops are filter feeders. Food particles filtered from water include phytoplankton, microzooplankton (such as ciliated protozoa), and particles of detritus, especially during periods of low phytoplankton concentrations (Shumway et al. 1987). Both fish and invertebrates prey upon Atlantic sea scallops (Hart and Chute 2004).
Status of the Fishery. The Atlantic sea scallop is one of the most economically important species in the northeast U.S. (Hart and Chute 2004). NEFMC manages the sea scallop fishery under the Sea Scallop Management Plan. In 2009, NEFMC did not consider the sea scallop fishery overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not monitor entrainment of invertebrate eggs from 1990 through 2009. Entrainment of Atlantic sea scallop larvae varied from 0 in 2003 and 2006 to 31 million in 1996 (Table D-1-7) (NAI 2010). Annual average entrainment of Atlantic 44 sea scallop larvae was 4.8 million per year from 1990 through 2009 (NAI 2010). Atlantic sea scallop larvae comprised less than 1 percent of the total invertebrate larvae entrained at Seabrook from 1990 through 2009.
Because adult Atlantic sea scallops are sessile benthic organisms, impingement is not likely, and NextEra did not monitor impingement of Atlantic sea scallops.
Because entrainment was relatively low for Atlantic sea scallops compared to other invertebrate species at Seabrook, and because impingement is not likely, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic sea scallop. Atlantic sea scallops are primarily benthic (Chute and Hart 2004), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic sea scallops are filter feeders, and prey includes phytoplankton, microzooplankton (such as ciliated protozoa), and particles of detritus.
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for plankton (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic sea scallops during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Survival of newly settled Atlantic sea scallop appears to be higher in complex habitats that include sedentary branching animals, plants, and other hard surfaces (Larsen and Lee 1978). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but NextEra observed relatively similar trends for the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook but Atlantic sea scallops use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on habitat for newly settled Atlantic sea scallops.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic sea scallop eggs, larvae, juveniles, or adults prior to and during operations. However, NextEra monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Conclusion. Because spat appear to have higher survival rates in complex habitats, such as kelp forests, and because Seabrook monitoring data suggests that operations have adversely affected the density of several species of kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile sea scallops. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for eggs, larvae, and adult sea scallops for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
45 Forage species are not likely to be adversely affected.
Monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away.
D-1.3.3.7 Atlantic Surfclam (Spisula solidissima) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult Atlantic surf clam EFH in the vicinity of Seabrook (NMFS 2011b). Seabrook monitoring does not include juvenile and adult Atlantic surf clams (NAI 2010). NAI (2010) observed surface larvae near Seabrook and the geometric mean density was approximately 350 to 590 clams per 1,000 m3 prior to 2001 and 120 clams per 1,000 m3 after 2001.
Species Description. Atlantic surfclams are bivalve mollusks that inhabit sandy habitats from the southern Gulf of St. Lawrence to Cape Hatteras, NC (Merrill and Ropes 1969 in Cargnelli et al. 1999a). Clams feed by sucking in plankton, such as diatoms and ciliates, through their siphons (Cargnelli et al. 1999a). Predators include invertebrates (e.g., naticid snails, sea stars (Asterias forbesi), lady crabs (Ovalipes ocellatus), Jonah crabs (Cancer borealis), horseshoe crabs (Limulus polyphemus)) and fish (e.g., haddock and Atlantic cod) (see review in Cargnelli et al. 1999a).
Status of the Fishery. MAFMC manages the Atlantic surfclam under the Atlantic surfclam and ocean quahog FMP. In 2009, MAFMC did not consider the Atlantic surfclam fishery overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not monitor entrainment of invertebrate eggs from 1990 through 2009. Entrainment of Atlantic surf clam larvae varied from 0 in 1992 and 2006 to 175.5 million in 1999 (NAI 2010). Annual average entrainment of Atlantic surf clam larvae was 48.9 million per year from 1990 through 2009 (Table D-1-7). Atlantic surf clam larvae comprised less than 1 percent of the total invertebrate larvae entrained at Seabrook from 1990 through 2009.
Because adult Atlantic surf clams are sessile benthic organisms, impingement is not likely, and NextEra did not monitor impingement of Atlantic surf clams.
Because entrainment was relatively low for Atlantic surf clams compared to other invertebrate species at Seabrook, and because impingement is not likely, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for Atlantic surf clams during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to Atlantic surfclams. Juvenile and adult Atlantic surfclams are benthic (Cargnelli et al. 1999a), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for Atlantic surfclam during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Atlantic surfclams feed on plankton, such as diatoms and ciliates.
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for plankton (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect 46 Atlantic surfclam EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Preferred habitat includes sandy bottom areas. Surfclams are not dependent on kelp forests. Therefore, the NRC staff concludes that loss of kelp at Seabrook is not likely to adversely affect EFH for juvenile and adult Atlantic surfclams during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of Atlantic surfclams prior to and during operations. However, NextEra monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect juvenile and adult Atlantic surfclams for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
Forage species are not likely to be adversely affected.
Monitoring data show relatively similar trends of benthic invertebrate density prior to and during operations at sampling sites near the intake and discharge structures and 3 to 4 mi (5 to 8 km) away.
D-1.3.3.8 Haddock (Melanogrammus aeglefinus) (Juvenile)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile haddock EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed haddock in greater than 10 percent of trawling samples and less than 1 percent of gill net samples (Table D-1-2).
Species Description. Haddock are demersal gadids that inhabit both sides of the North Atlantic Ocean (Brodziak 2005). In the northwest Atlantic, haddock can be found from Cape May, NJ to the Strait of Belle Isle, Newfoundland (Klein-MacPhee 2002). In the U.S., two stocks of haddock occurone in the Gulf of Maine and one in Georges Bank (Brodziak 2005).
Larvae metamorphose into juveniles once they reach 0.8 to 1.2 in. (2 to 3 cm) (Fahay 1983).
For the first 3 to 5 months, small juveniles live and feed in the upper part of the water column.
Juveniles visit the seafloor in search of prey and remain on the ocean bottom once suitable habitat is located (Brodziak 2005; Klein-MacPhee 2002). Preferred benthic habitat includes include gravel, pebbles, clay, and smooth hard sand (Klein-MacPhee 2002), which is more abundant in Georges Bank than in the Gulf of Maine (Broziak 2005).
While inhabiting the upper part of the water column, small juveniles feed on phytoplankton, small crustaceans (primarily copepods and euphausiids), and invertebrate eggs (Brodziak 2005; Kane 1984). Benthic prey for larger juveniles include polychaetes, echinoderms, small decapods, and small fishes (Bowman et al. 1987; Broziak 2005).
Status of the Fishery. By the early 1990s, haddock experienced several decades of declining spawning biomass and recruitment (Brodziak 2005). Some considered the stock to be near collapse (Brodziak 2005). Since 1994, fishery management measures have helped to reduce fishing mortality (Brodziak 2005). NEFMC currently manages haddock under the northeast multispecies FMP. In 2009, NEFMC considered haddock overfished (NMFS 2010b).
47 Entrainment and Impingement. Although NMFS has not designated EFH for haddock eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles. Entrainment of haddock eggs varied from 0 in several years to 7.4 million in 1992 (NAI 2010). Annual average entrainment of haddock eggs was 0.4 million per year from 1990 through 2009 (Table D-1-4). Entrainment of 100,000 haddock larvae occurred in 1992 and 2005. NAI (2010) did not observe entrainment of haddock larvae in any other year from 1990 through 2009 (Table D-1-5). Haddock eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of haddock varied from 0 in several years to 397 in 1996 (NAI 2010). Annual average impingement was 28 fish per year from 1994 through 2009 (Table D-1-6). Haddock comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for haddock compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile haddock. Young juvenile haddock remain pelagic for 3 to 5 months, at which point they travel to the seafloor in search of food and remain within this benthic habitat.
A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile haddock feed on a variety of organisms, including phytoplankton, copepods, euphausiids, invertebrate eggs, polychaetes, echinoderms, small decapods, and small fishes (Bowman et al. 1987; Broziak 2005; Kane 1984). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of phytoplankton, zooplankton (including copepods), invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for juvenile haddock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile haddock do not use kelp habitats (Broziak 2005).
Therefore, loss of kelp due to Seabrook operations are not likely to adversely affect EFH for juvenile haddock.
Combined Impacts (Monitoring Data). Seabrook monitoring data does not provide data specific to the abundance of juvenile haddock prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect juvenile haddock or its habitat for the following reasons:
Impingement and entrainment are relatively low for haddock.
The thermal plume rises quickly to surface waters Forage species are not likely to be adversely affected by Seabrook operations.
Preferred habitat does not include kelp or shellfish beds.
48 D-1.3.3.9 Monkfish/Goosefish (Lophius americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult goosefish EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed goosefish eggs in less than 1 percent of ichthyoplankton tows, goosefish larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in 1 to 10 percent of trawling samples, and juveniles and adults in less than 1 percent of gill net samples (Table D-1-2).
Species Description. Goosefish are large, slow-growing benthic fish (Steimle et al. 1999a). In the Gulf of Maine, goosefish larger than 7.9 in. (20 cm) move offshore in the winter and spring to avoid cold coastal conditions, whereas smaller goosefish migrate offshore in the fall (Hartley 1995, cited in Steimle et al. 1999a).
Adults mature at approximately 4 years for males and 5 years for females (Almeida et al. 1995).
Spawning occurs from May through June in the Gulf of Maine (Hartley 1995, cited in Steimle et al. 1999a). Females shed relatively large eggs (0.6 to 0.7 in. (1.6 to 1.8 mm)) within buoyant, ribbon-like, non-adhesive, mucoid veils or rafts (Martin and Drewry 1978, cited in Steimle et al. 1999a). Egg veils float on the surface (Steimle et al. 1999a). Larvae are also pelagic.
Juveniles settle to the bottom of the ocean and remain demersal as adults. Young juveniles often hide from predators within algae covered rocks. Adults prefer open sandy bottoms where they can partially bury themselves and then ambush prey (Steimle et al. 1999a).
Prey varies depending on life stage. Larval prey includes zooplankton, such as copepods, crustacean larvae, and chaetognaths (Bigelow and Schroeder 1953). Small juveniles eat pelagic fish but switch to invertebrates, especially crustaceans, once settling on the seafloor (Steimle et al. 1999a). Larger juveniles and adults consume more fish than invertebrates (Armstrong et al. 1996). NEFSC analyzed the stomach contents of goosefish and primary prey included crustaceans, squid, and fish. Common fish prey include spiny dogfish (Squalus acanthias), skates (Raja spp.), eels, sand lance, herring, Atlantic menhaden (Brevoortia tyrannus), smelt (Osmeridae), mackerel (Scomber spp.), weakfish (Cynoscion regalis), cunner, tautog (Tautoga onitis), black sea bass (Centropristis striata),
butterfish, pufferfish, sculpins, sea raven (Hemitripterus americanus), searobins (Prionotus spp.), silver hake (Merluccius bilinearis), Atlantic tomcod (Microgadus tomcod), cod, haddock, hake (Urophycis spp.), witch and other flounders, and other goosefish (Bigelow and Schroeder 1953; Steimle et al. 1999a).
Status of the Fishery. In U.S. waters, NEFMC manages goosefish under the northeast multispecies FMP. In 2009, NMFS (2010b) reported that goosefish was not overfished.
Entrainment and Impingement. Entrainment of goosefish eggs varied from 0 in most years to 0.9 million in 1998 and 2000 (NAI 2010). Annual average entrainment of goosefish eggs was 0.1 million per year from 1990 through 2009 (Table D-1-4). Entrainment of goosefish larvae varied from 0 in most years to 2 million in 2000 (NAI 2010). Annual average entrainment of goosefish larvae was 0.1 million per year from 1990 through 2009 (Table D-1-5). Goosefish eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of goosefish varied from 0 in several years to 59 in 2001 (NAI 2010). Annual average impingement was 10 fish per year from 1994 through 2009 (Table D-1-6). Goosefish comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for goosefish compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
49 Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult goosefish. Seabrooks thermal discharge may slightly reduce available habitat to goosefish eggs and larvae.
Goosefish eggs and larvae are pelagic (Steimle et al. 1999a). Scott and Scott (1988, cited in Steimle et al. 1999a) reported 63 to 64° F (17 to 18° C) as the upper temperature limit for normal egg hatching. NEFSC MARMAP ichthyoplankton surveys collected most larvae from 52 to 59° F (11 to 15° C), but as high as 68 ° F (20° C) (Steimle et al. 1999a). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface could exceed the typical range of temperatures that goosefish eggs and larvae inhabit. The habitat affected at the surface would likely be 32 ac (12.9 ha) or less (Padmanabhan and Hecker 1991).
Adult and juvenile goosefish are primarily benthic, meaning that they spend most of the time residing near the seafloor (Steimle et al. 1999a). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
Because the thermal plume could exceed the typical range of temperatures that larvae inhabit, the NRC staff concludes that the heated thermal effluent may have minimal adverse effects on Atlantic cod larvae. Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Goosefish feed on a variety of organisms, including zooplankton, invertebrates, and several fish species (Bigelow and Schroeder 1953; Steimle et al. 1999a).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton, invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for goosefish during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Newly settled juveniles may hide within algae covered rocks (Steimle et al. 1999a). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began (NAI 2010).
Therefore, Seabrook operations may have minimal adverse effects on juvenile goosefish habitat. Effects would likely be minimal because juvenile goosefish would likely inhabit algae (other than kelp) that have not declined near Seabrook (NAI 2001).
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the density or abundance of goosefish eggs, larvae, juveniles, or adults prior to and during operations (NAI 2010).
Conclusion. Because the thermal plume could exceed the typical range of temperatures that eggs and larvae inhabit, and because juveniles may use algal habitats that have declined near Seabrook since operations began, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for goosefish eggs, larvae, and juveniles near Seabrook. Based on the above analysis, Seabrook is not likely to affect goosefish adults or its habitat because entrainment and impingement are relatively low compared to other species at Seabrook, the thermal plume rises quickly to surface waters, and forage species are not likely to be adversely affected.
50 D-1.3.3.10 Ocean pout (Macrozoarces americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult ocean pout EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed ocean pout larvae in 1 to 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, and juveniles and adults in less than 1 percent of gill net samples (Table D-1-2).
Species Description. Ocean pout inhabit the Atlantic continental shelf of North America and are common off the coast of southern New England (Chang 1990). Ocean pout are benthic and use both open and rough habitats (Steimle et al. 1999b).
In the fall, ocean pout spawn in rock crevices, man-made artifacts, or other protected areas where they lay eggs in nests (Steimle et al. 1999b). Eggs remain demersal, and nests are guarded by one or both parents (Bigelow and Schroeder 1953). Once hatched, larvae generally remain near or at the bottom of the seafloor (Bigelow and Schroeder 1953). Juveniles and adults are also demersal. Bigelow and Schroeder (1953) reported that juveniles occur in shallow coastal waters around rocks and attached algae and in rivers with saline bottom waters in the Gulf of Maine. Juveniles may also use scallop or quahog shells for cover. Adults use a variety of habitats including rocky crevices, soft bottom habitats, gravel covered areas, and shellfish beds (Steimle et al. 1999b).
Ocean pout prey on benthic organisms in soft sandy bottom habitats either by sorting mouthfuls of sediments for infaunal species (MacDonald 1983) or by ambushing prey (Auster et al. 1995).
Sedberry (1983, cited in Steimle et al. 1999b) found that juveniles feed on gammarid amphipods and polychaetes. Adults prey on a variety of benthic invertebrates, such as polychaetes, mollusks, crustaceans, and echinoderms (see review in Steimle et al. 1999b). Langton and Watling (1990 in Steimle et al. 1999b) reported that ocean pout primarily eat bivalve mollusks off the coast of southern Maine. Ocean pout and American plaice may compete for prey in the Gulf of Maine (MacDonald and Green 1986). Predators of juvenile ocean pout include squid, spiny dogfish, sea raven, cod, barndoor skate (Raja laevis), harbor seals, and cormorants (Steimle et al. 1999).
Status of the Fishery. NEFMC currently manages ocean pout as two stocks, one in northern Gulf of Maine and one south of this area (Wigley 1998). In 2009, NEFMC reported that ocean pout was not overfished (NMFS 2010b).
Entrainment and Impingement. NAI (2010) did not observe entrainment of ocean pout eggs from 1990 through 2009 (Table D-1-4). Seabrook entrained less than 10,000 ocean pout larvae in 2003 (NAI 2010). NAI (2010) did not observe entrainment of ocean pout larvae during any other year from 1990 through 2009 (Table D-1-5).
Impingement of ocean pout varied from 0 in several years to 21 in 2001 (NAI 2010). Annual average impingement was four fish per year from 1994 through 2009 (Table D-1-6). Ocean pout comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment and impingement were relatively low for ocean pout compared to other species at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to eggs, larvae, juvenile, or adult ocean pout. Ocean pout are primarily benthic (Steimle et al. 1999b), meaning that they spend most of the time residing near the seafloor. A relatively small area near the discharge structure in deep water experiences increased
51 temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for all life stages of ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Ocean pout feed on a variety of invertebrates, including gammarid amphipods, polychaetes, mollusks, echinoderms, and other crustaceans (Langton and Watling 1990, cited in Steimle et al. 1999b; Steimle et al. 1999b). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton and benthic invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for ocean pout during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juveniles may use habitats with algae, and both juveniles and adults may use shellfish beds (Bigelow and Schroeder 1953; Steimle et al. 1999b). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but juvenile ocean pout use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile ocean pout and its habitat.
Because Seabrook operations have not adversely affected the density or species diversity of benthic invertebrates, including shellfish beds, Seabrook operations are not likely to adversely affect adult ocean pout habitat.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of ocean pout eggs, larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Icthoplankton trawls did not capture ocean pout eggs and captured larvae in less than 10 percent of all samples (Table D-1-2). Monitoring data indicate that the abundance of juveniles and adult increased or remained the same at both nearfield and farfield sampling sites (Table D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for ocean pout.
Conclusion. Because juveniles may use algal habitats and other complex habitats, and because the density of several kelp species has declined near Seabrook since operations began, NRC staff concludes that Seabrook may have minimal adverse effects on juvenile ocean pout and its habitat near Seabrook. Based on the above analysis, Seabrook is not likely to affect EFH for ocean pout eggs, larvae, or adults for the following reasons:
Entrainment and impingement are relatively low compared to other species at Seabrook.
The thermal plume rises quickly to surface waters.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Monitoring data indicate that the abundance trends for ocean pout were similar at nearfield and farfield sties.
52 D-1.3.3.11 Pollock (Pollachius virens) (Juvenile)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile pollock EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed pollock in greater than 10 percent of trawling samples, in greater than 10 percent of gill net samples, and in 1 to 10 percent of seine pull samples (Table D-1-2) (NAI 2010).
Species Description. Pollock are gadoids that occur on both sides of the North Atlantic (Cargnelli et al. 1999). Within the western Atlantic, pollock are relatively common within the Gulf of Maine (Cargnelli et al. 1999).
Juveniles migrate to and from offshore waters to nearshore habitats, such as the rocky subtidal and intertidal, until they remain offshore as adults (Cargnelli et al. 1999). Juveniles use a wide variety of habitats, including sand, mud, or rocky bottom and vegetation (Hardy 1978, cited in Cargnelli et al. 1999). NEFSC trawl surveys captured juveniles at temperatures ranging from 34 to 64° F (1 to 18° C).
Juveniles consume crustaceans, such as euphausiids and mollusks, and fish (Bowman and Michaels 1984). Ojeda and
Dearborn (1991) determined that fish,
such as young Atlantic herring, dominated the diet of subtidal juveniles in the Gulf of Maine.
Status of the Fishery. NEFMC manages pollock as a single unit under the northeast multispecies FMP. In 2009, NEFMC determined that pollock was not overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for pollock eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles. Entrainment of pollock eggs varied from 0 in 1990 to 8.5 million in 2007 (NAI 2010). Annual average entrainment of pollock eggs was 1.4 million per year from 1990 through 2009 (Table D-1-4).
Entrainment of pollock larvae varied from 0 in most years to 0.8 million in 2007 (NAI 2010).
Annual average entrainment of pollock larvae was 0.2 million per year from 1990 through 2009 (Table D-1-5). Pollock eggs and larvae comprised less than 1 percent of the total fish eggs and larvae entrained at Seabrook from 1990 through 2009.
Impingement of pollock varied from 72 in 2006 to 11,392 in 1999 (NAI 2010). Annual average impingement was 1,273 fish per year from 1994 through 2009 (Table D-1-6). Pollock was the sixth most commonly impinged fish species and comprised 6.1 percent of all impinged fish at Seabrook from 1994 through 2009.
Entrainment of pollock is small compared to other species entrained at Seabrook. However, pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Therefore, the NRC staff concludes that impingement may have minimal adverse effects on EFH for pollock during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captures in the Seabrook cooling system would be a very small proportion of available habitat for pollock juveniles and adults.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile pollock. Juvenile pollock use primarily benthic habitats in the nearshore, such as rocky subtidal or intertidal area, although some may also travel throughout the water column (Cargnelli et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
From May through June and October through December, when pollock density was highest in Seabrook monitoring studies, the surface temperature reached 57.7° F (14.3° C) near Seabrook (NAI 2010). NEFSC trawl surveys captured juveniles at temperatures ranging from 34 to 64° F (1 to 18° C). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the
53 surface would be within the typical range of temperatures that juvenile pollock inhabit. The NRC staff concludes that the increased temperatures at Seabrook are not likely to adversely affect EFH for juvenile pollock during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the findings that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for juvenile pollock.
Loss of Forage Species. Juveniles consume crustaceans, such as euphausiids and mollusks, and fish, such as Atlantic herring (Bowman and Michaels 1984; Ojeda and Dearborn 1991).
NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance and density of zooplankton, benthic invertebrates, and most fish species (NAI 2010). Entrainment and impingement were relatively low for Atlantic herring, primary fish prey for juvenile pollock, compared to other species at Seabrook. Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect pollock during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juveniles use a wide variety of habitats, including sand, mud, or rocky bottom and vegetation (Hardy 1978, cited in Cargnelli et al. 1999). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but NextEra observed similar trends for the density of benthic invertebrates at the nearfield and farfield sampling sites prior to and during operations (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but juvenile pollock use complex habitats other than kelp, the NRC staff concludes that Seabrook operations may have minimal adverse effects on juvenile pollock habitat.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of juvenile pollock prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away and within Hampton-Seabrook Estuary (NAI 2010). Monitoring data indicate that the abundance of juvenile pollock decreased or remained the same at both nearfield and farfield sampling sites (Tables D-1-10 and D-1-11). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for juvenile pollock.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for juvenile pollock because juveniles may use algal habitats that have declined near Seabrook since operations began, and pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Impacts would likely be minimal for the following reasons:
Pollock are not commonly entrained in the Seabrook cooling system.
The thermal plume rises quickly to the surface.
The temperature range within the thermal plume at the surface would be within the typical range for juvenile pollock.
Forage species are not likely adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield stations prior to and during operations.
54 D-1.3.3.12 Red hake (Urophycis chuss) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult red hake EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed Urophycis spp. (mostly red and white (U. tenuis) hake and to a lesser extent spotted hake (U. regia)) egg and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in 1 to 10 percent of gill net samples, and in more than 10 percent of seine pull samples (Table D-1-2).
Species Description. Red hake are demersal fish that occur along the U.S. and Canadian costs from North Carolina to Southern Newfoundland (Sosebee 1998). Red hake migrate seasonally to various depths to inhabit waters with relatively consistent temperaturesthey migrate to waters deeper than 328 ft (100 m) in the fall and waters less than 328 ft (100 m) in warmer months (Steimle et al. 1999c).
Southern Gulf of Maine is not a common spawning ground for red hake (Steimle et al. 1999c).
Eggs are buoyant and float near the surface (Steimle et al. 1999c). Larvae are also pelagic and inhabit the upper water column. NEFSC MARMAP ichthyoplankton surveys collected larvae at temperatures ranging from 46 to 73° F (8 to 23° C) (Steimle et al. 1999c). Surveys indicate that larvae are more abundant in the Middle Atlantic Bight than the Gulf of Maine (Steimle et al. 1999c). Juveniles remain pelagic for approximately 2 months before they settle to the sea floor. Bottom trawl surveys captured juveniles in waters up to 72° F (22° C) (Steimle et al. 1999c). Benthic habitat structure for sheltersuch as sea scallop shells, Atlantic surf clams, seabed depressions, or other structureis important habitat for juveniles (Steiner et al. 1982).
Adult red hake commonly inhabit areas with soft sediments bottoms that contain shellfish beds or depressions as well as natural and artificial reefs (Steimle et al. 1999c).
Prey varies by life stage. Larvae consume mainly copepods and other microcrustaceans (Steimle et al. 1999c). Juvenile red hake consume small benthic and pelagic crustaceans, such as larval and small decapod shrimp and crabs, mysids, euphausiids, and amphipods (Steimle et al. 1999c). Similar to juveniles, adults consume crustaceans but also prey on a variety of demersal and pelagic fish and squid.
Status of the Fishery. NEFMC manages the red hake fishery under the northeast multispecies FMP. In 2009, NEFMC did not consider the red hake fishery overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of red, white, and spotted hake at Seabrook was recorded under a single category for Urophycis spp. (NAI 2010). Entrainment of hake eggs varied from 0.6 million in 1994 to 213.2 million in 1996 (NextEra 2010a). Annual average entrainment of hake eggs was 45.7 million per year from 1990 through 2009 (Table D-1-4).
Hake was the fourth most commonly entrained taxa, comprising 5.1 percent of all entrained fish eggs at Seabrook from 1990 through 2009.
Entrainment of hake larvae varied from 0 in most years to 29.8 million in 2000 (NAI 2010).
Annual average entrainment of hake larvae was 2.8 million per year from 1990 through 2009 (Table D-1-5). Hake larvae comprised 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of red hake varied from 1 in 1994 to 1,478 in 1996 (NAI 2010). Annual average impingement was 509 fish per year from 1994 through 2009 (Table D-1-6). For hakes, which included red hake, white hake, and spotted hake, impingement varied from 4 in 1998 to 3,216 in 2008 (NAI 2010). Annual average impingement was 866 fish per year from 1994 through 2009 (Table D-1-6). The red hake and hake categories comprised 6.5 percent of all impinged fish at Seabrook from 1994 through 2009.
55 Because entrainment and impingement of hake were relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all life stages of red hake.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to red hake. Larvae and young juveniles inhabit pelagic waters up to 72 to 73° F (22 to 23° C) (Steimle et al. 1999c). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface would be within the typical range of temperatures that larvae and young juveniles inhabit. Older juvenile and adult red hake are benthic (Steimle et al. 1999c). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). The NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
This conclusion is based on the fact that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for larvae and young juvenile red hake.
Loss of Forage Species. Red hake consume a variety of prey items, including copepods, shrimp, crabs, euphausiids, amphipods, and other crustaceans, and a variety of demersal and pelagic fish and squid (Steimle et al. 1999c). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult red hake commonly use shellfish bed for shelter, as well as other natural and artificial structures. Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect EFH for red hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of hake eggs, juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). This category included Urophycis spp. (mostly red and white hake) and to a lesser extent spotted hake (NAI 2010).
Monitoring data indicate that the abundance of hake eggs, juveniles, and adults decreased at both nearfield and farfield sampling sites (Tables D-1-8 and D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for hake.
Conclusion. Based on the above analysis, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for red hake eggs, larvae, juvenile, and adults during the remainder of the facilitys operating license or during the proposed license renewal term because entrainment and impingement of hake were relatively common at Seabrook. Impacts would likely be minimal for the following reasons:
Thermal plume rises quickly to surface waters and is within the typical range of surface temperatures for larvae and young juveniles.
56 Forage species and shellfish beds are not likely to be adversely affected.
Monitoring data show similar trends in the abundance of red hake at nearfield and farfield sties prior to and during operations.
D-1.3.3.13 Scup (Stenotomus chrysops) (Juvenile and Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult scup EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed scup in 1 to 10 percent of trawling samples and less than 1 percent of gill net samples (Table D-1-2).
Species Description. Scup are demersal fish that primarily occur primarily along the U.S. coast from Massachusetts to South Carolina, and have been observed as far north as the Bay of Fundy (Steimle et al. 1999d). Scup migrate south of New Jersey during the winter.
During the summer and early fall, juveniles and adults inhabit larger estuaries and coastal areas. Baird (1873, cited in Steimle et al. 1999d) reported habitat for juveniles to include sand, silty-sand, shell, mud, mussel beds, and eelgrass (Zosteria marina). Adults exhibit schooling behavior and also use a variety of habitats, including open sandy bottom and structured habitats such as mussel beds, reefs, or rough bottom (Steimle et al. 1999d).
Juveniles prey on small crustaceans, such as amphipods, polychaetes, and copepods (Steimle et al. 1999d). Adults consume a variety of prey, including small zooplankton, polychaetes, mollusks, other crustaceans, small squid, vegetable detritus, insect larvae, hydroids, sand dollars, and small fish (Bigelow and Schroeder 1953; Steimle et al. 1999d). Predators of scup include a variety of fish and sharks, such as bluefish (Pomatomus saltatrix), Atlantic halibut, cod, striped bass (Morone saxitilus), weakfish, goosefish, silver hake, and other coastal fish predators (see review in Steimle et al. 1999d).
Status of the Fishery. MAFMC manages the scup fishery under the summer flounder, scup, and black sea bass FMP. In 2009, MAFMC did not consider the scup fishery overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for scup eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults.
NAI (2010) did not observe scup eggs or larvae in entrainment studies from 1990 through 2009.
Impingement of scup varied from 0 in multiple years to 21 in 2005 (NAI 2010). Annual average impingement was seven fish per year from 1994 through 2009 (Table D-1-6). Scup comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because NAI (2010) did not observe scup entrainment, and because impingement is small compared to other species entrained at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult scup. Juvenile and adult scup are primarily benthic (Steimle et al. 1999d). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Scup consume a variety of prey including zooplankton, amphipods, polychaetes, copepods, mollusks, other crustaceans, small squid, vegetable detritus, insect larvae, hydroids, sand dollars, and small fish (Bigelow and Schroeder 1953; Steimle et
57 al. 1999d). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton, benthic invertebrates, and most fish species (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult scup use a variety of habitats, including open areas and areas with structure such as mussel beds and eelgrass (Zosteria marina)
(Steimle et al. 1999d). Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began, but Seabrook observed similar trends in the density of benthic invertebrates at the nearfield and farfield sites prior to and during operations (NAI 2010). Because scup inhabit a wide variety of habitats and kelp are not a primary or preferred habitat, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect EFH for scup during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of juvenile or adult scup prior to and during operations (NAI 2010).
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations are not likely to adversely affect EFH for juvenile or adult scup for the following reasons:
Impingement and entrainment are relatively low for scup.
The thermal plume quickly rises to the surface.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Scup use a wide variety of habitats other than kelp.
D-1.3.3.14 Summer flounder (Paralicthys dentatus) (Adult)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated adult summer flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed summer flounder in less than 1 percent of trawling samples (Table D-1-2).
Species Description. Summer flounder are benthic fish that occurs from Nova Scotia to Florida (Packer et al. 1999). Adult summer flounder migrate seasonally, whereby summer flounder normally inhabit shallow coastal and estuarine waters during summer and remain offshore during the fall and winter (Lux and Nichy 1981, cited in Packer et al. 1999; Packer et al. 1999).
Adults prefer sandy habitats. Lascara (1981, cited in Packer et al. 1999) showed that adults remain along the vegetative perimeter of eelgrass patches and capture prey that move from within the grass. Adult summer flounder are opportunistic feeders and prey upon a variety of fish and crustaceans (Bigelow and Schroeder 1953; Packer et al. 1999). Common prey items include windowpane, winter flounder, northern pipefish, Atlantic menhaden, bay anchovy, red hake, silver hake, scup, Atlantic silverside, American sand lance, bluefish, weakfish, mummichog, rock crabs, squids, shrimps, small bivalve and gastropod mollusks, small crustaceans, marine worms, and sand dollars (Packer et al. 1999). Predators of summer flounder include large sharks, rays, and goosefish.
Status of the Fishery. MAFMC manages the summer flounder fishery under the summer flounder, scup, and black sea bass FMP. In 2009, MAFMC did not consider the summer flounder fishery overfished (NMFS 2010b).
58 Entrainment and Impingement. Although NMFS has not designated EFH for summer flounder eggs and larvae, entrainment and impingement can adversely affect recruitment of adults.
NAI (2010) did not observe summer flounder eggs in entrainment studies from 1990 through 2009. NAI (2010) observed entrainment of less than 100,000 summer flounder larvae during 3 years from 1990 through 2009 (Table D-1-5). NAI (2010) observed three impinged fish in 1994 and four impinged fish in 2006 (Table D-1-6).
Because entrainment and impingement of summer flounder were relatively rare at Seabrook, the NRC staff concludes that entrainment and impingement are not likely to adversely affect EFH for summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to adult summer flounder. Summer flounder are primarily benthic (Packer et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Adult summer flounder are opportunistic feeders and prey upon a variety of fish and crustaceans (Bigelow and Schroeder 1953; Packer et al. 1999). NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of benthic invertebrates and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect summer flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Adult summer flounder use open sandy areas and patches of eelgrass for feeding (Packer et al. 1999). Near the intake and discharge structures, it is reasonable to assume that patches of kelp may play a similar ecological role as eelgrass for summer flounder to ambush predators. Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations because operations began (NAI 2010). Because summer flounder use patches of vegetation to ambush predators, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook may have minimal adverse effects on EFH for adult summer flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since adult summer flounder inhabit a variety of habitats and vegetation other than kelp.
Combined Impacts (Monitoring Data). Seabrook monitoring data do not provide data specific to the abundance of adult summer flounder prior to and during operations (NAI 2010).
Conclusion. Because summer flounder may use algal habitats that have declined near Seabrook since operations began, the NRC staff concludes that Seabrook may have minimal adverse effects on EFH for summer flounder near Seabrook. Impacts would likely be minimal because impingement and entrainment are relatively rare for summer flounder, the thermal plume quickly rises to the surface, and forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
59 D-1.3.3.15 Whiting/Silver hake (Merluccius bilinearis) (All life stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult silver hake EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed silver hake egg and larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in greater than 10 percent of gill net samples, and in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Silver hake are schooling gadids (Lock and Packer 2004). Two stocks occur in the western Atlantic Oceanone stock ranges from the Gulf of Maine to northern Georges Bank and the other stock ranges from southern Georges Bank to Cape Hatteras.
Coastal Gulf of Maine is a major spawning area for silver hake. Brodziak (2001) reported peak spawning from July through August in the northern stock of silver hake. Eggs and newly hatched larvae are pelagic (Lock and Packer 2004). After 3 to 5 months, larvae descend towards benthic habitats (Jeffrey and Taggart 2000). NEFSC MARMAP ichthyoplankton surveys captured eggs at temperatures ranging from 41 to 73° F (5 to 23 ° C) and larvae from 41 to 66° F (5 to 19° C) (Lock and Packer 2004).
Juvenile and adult silver hake make seasonal migrations, moving offshore as water temperatures decline in the fall and returning to shallow waters in spring and summer to spawn.
Juvenile and adult silver hake are primarily benthic but will move up into the water column for feeding (Koeller et al. 1989; Lock and Packer 2004). Lock and Packer (2004) consider silver hake use and preference of various bottom habitats a future research need. NEFSC bottom trawl surveys captured juveniles at temperatures ranging from 36 to 70° F (2 to 21° C) and adults from 36 to 63° F (2 to 17° C) (Lock and Packer 2004).
Silver hake are an important predator species due to their dominant biomass and high prey consumption (Bowman 1984; Garrison and Link 2000). Silver hake diet varies with life stage, size, sex, season, migration, spawning, and age. Larvae prey on plankton such as copepod larvae and younger copepodites (Lock and Packer 2004). Juveniles generally consume euphausiids, shrimp, amphipods, and decapods (Bowman 1984). Adults and older juveniles mainly prey on schooling fish, such as young herring, mackerel, menhaden, alewives, sand lance, or silversides, although crustaceans and squids are also consumed (Bowman 1984; Garrison and Link 2000; Lock and Packer 2004). Predators include offshore, silver, white, red, and spotted hakes and to a lesser extent demersal gadids, pelagic fish species, and squids (Lock and Packer 2004).
Status of the Fishery. NEFMC manages the silver hake fishery. In 2009, NEFMC did not consider the silver hake fishery overfished (NMFS 2010b).
Entrainment and Impingement. Entrainment of silver hake eggs varied from 0.6 million in 1991 to 341.4 million in 2002 (NAI 2010). Annual average entrainment of silver hake eggs was 81.1 million per year from 1990 through 2009 (Table D-1-4). Silver hake was the third most commonly entrained egg species, comprising 9 percent of all entrained fish eggs at Seabrook from 1990 through 2009.
Entrainment of silver hake larvae varied from 0 in several years to 69 million in 1997 (NAI 2010).
Annual average entrainment of silver hake larvae was 8.1 million per year from 1990 through 2009 (Table D-1-5). Silver hake larvae was the ninth most commonly entrained larval species, comprising 3 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of silver hake varied from 0 in 1994 to 1,177 in 2002 (NAI 2010). Annual average impingement was 167 fish per year from 1994 through 2009 (Table D-1-6). Silver hake comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
60 Because entrainment of silver hake was relatively common at Seabrook, the NRC staff concludes that entrainment may have minimal adverse effects on EFH for silver hake during the remainder of the facilitys operating license or during the proposed license renewal term.
Effects would likely be minimal since the amount of water (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for silver hake eggs and larvae.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to silver hake. NEFSC MARMAP ichthyoplankton surveys captured eggs at temperatures ranging from 41 to 73° F (5 to 23° C) and larvae from 41 to 66° F (5 to 19° C)
(Lock and Packer 2004). Juveniles and adults are primarily benthic but may move into the water column for feeding (Lock and Packer 2004). NEFSC bottom trawl surveys captured juveniles at temperatures ranging from 36 to 70° F (2 to 21° C) and adults from 36 to 63° F (2 to 17° C) (Lock and Packer 2004). Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C), the thermal plume near the surface would be within the typical range of temperatures that eggs and juveniles inhabit. However, the thermal plume may exceed the typical range of temperatures that larvae and adults inhabit. A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). The NRC staff concludes that the heated thermal effluent from Seabrook is not likely to adversely affect EFH for eggs and juveniles during the remainder of the facilitys operating license or during the proposed license renewal term. This conclusion is based on the fact that the buoyant thermal plume at the discharge points quickly rises toward the surface, and the temperature range within the thermal plume at the surface would be within the typical range for eggs and juvenile silver hake. Because the thermal plume could exceed the typical range of temperatures that larvae and adults inhabit, the NRC staff concludes that the heated thermal effluent may adversely affect EFH for silver hake larvae and adults.
Loss of Forage Species. Silver hake consume a variety of prey, including copepod larvae, copepodites, euphausiids, shrimp, amphipods, decapods, and other crustaceans and schooling fish (e.g., young herring, mackerel, menhaden, alewives, sand lance, and silversides) and squids (Bowman 1984; Garrison and Link 2000; Lock and Packer 2004). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect silver hake EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Lock and Packer (2004) consider silver hake use and preference of various bottom habitats a future research need. A recent literature search by NRC staff did not indicate that silver hake prefer or heavily rely on shellfish beds or algae covered areas.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of silver hake eggs, larvae juveniles, and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of silver hake eggs and larvae increased at both nearfield and farfield sampling sites (Table D-1-8). Gill net surveys indicate that abundance of silver hake within the water column decreased at both nearfield and farfield sites (Table D-1-10). Trawling surveys indicate that silver hake abundance near the sea floor decreased at the nearfield site but increased at the farfield sites (Table D-1-9). NAI (2010) did not report the statistical significance of this relationship. Because adult and juvenile silver hake decreased at nearfield
61 trawling sites but increased at farfield trawling sites, these monitoring results suggest that Seabrook operation may adversely affect bottom habitat for adult and juvenile silver hake.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may adversely affect EFH for silver hake eggs, larvae, juveniles, and adults for the following reasons:
Entrainment of silver hake eggs was relatively common at Seabrook.
The thermal plume could exceed the typical range of temperatures that larvae and adults inhabit.
Adult and juvenile silver hake decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
D-1.3.3.16 Windowpane flounder (Scopthalmus aquosus) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult windowpane flounder EFH near Seabrook (NMFS 2011b). NAI (2010) observed windowpane flounder in greater than 10 percent of trawling samples, less than 1 percent of gill net samples, and 1 to 10 percent of seine pull samples (Table D-1-2).
Species Description. Windowpane flounder inhabit estuaries, coastal waters, and oceans over the continental shelf along the Atlantic coast from the Gulf of Saint Lawrence to Florida. This species is most abundant from Georges Bank to Chesapeake Bay (Chang et al. 1999). North of Cape Cod Bay, windowpane flounder inhabit nearshore waters, and distribution patterns within estuaries is not well documented (Chang et al. 1999).
Windowpane flounder spawn in estuaries. Juveniles migrate from estuaries to coastal waters during autumn, and they overwinter offshore in deeper waters. Adults remain offshore throughout the year but inhabit nearshore waters in spring and autumn (Chang et al. 1999).
Langton et al. (1994) reported that adult windowpane occur primarily on sandy or muddy substrates in the Gulf of Maine.
Juvenile and adult windowpane flounder have similar food sources, including small crustaceans (especially shrimp) and fish larvae of hakes and tomcod. Predators include spiny dogfish, thorny skate (Amblyraja radiata), goosefish, Atlantic cod, black sea bass (Centropristis striata),
weakfish (Cynoscion regalis), and summer flounder (Chang et al. 1999).
Status of the Fishery. The NEFMC manages windowpane flounder under the northeast multispecies FMP. Windowpane flounder have never been widely directly targeted as a commercial species but have been harvested in mixed-species fisheries since the 1900s. In the 1950s, landings were estimated to be as high as 2.04 million lb (924 MT) per year (Hendrickson 2006). Landings ranged from 1.1 to 2.0 million lb (500 to 900 MT) per year from 1975 through 1981, increased to a record high of 4.6 million lb (2,100 MT) in 1985, and they have since steadily declined (Hendrickson 2006). The windowpane stock structure has never been formally quantified, and windowpane bycatch and discards from other fisheries are unknown and may account for a significant portion of annual windowpane catch. Currently, NEFMC consider the New England and Mid-Atlantic stock overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for windowpane eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of windowpane eggs varied from 0.1 million in 1994 to 61.8 million in 2009 (NAI 2010). Annual average entrainment of windowpane eggs was 31.7 million per year from 1990 through 2009 (Table D-1-4). Windowpane was the eighth most commonly entrained egg species, comprising 3.5 percent of all entrained fish eggs at Seabrook.
62 Entrainment of windowpane larvae varied from 0.05 in 1991 to 6.5 million in 2002 (NAI 2010).
Annual average entrainment of windowpane larvae was 2.3 million per year from 1990 through 2009 (Table D-1-5). Windowpane larvae comprised less than 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of windowpane varied from 161 in 2001 to 4,749 in 2003 (NAI 2010). Annual average impingement was 1,297 fish per year from 1994 through 2009 (Table D-1-6).
Windowpane was the fifth most commonly impinged fish species, comprising 6.2 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of windowpane eggs and impingement of juveniles and adults was relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for windowpane during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all stages of windowpane.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult windowpane. Juvenile and adult windowpane are primarily benthic (Chang et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for juvenile or adult windowpane during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile and adult windowpane flounder prey on small crustaceans (especially shrimp) and fish larvae of hakes and tomcod. NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton and invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for windowpane flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult windowpane flounder do not appear to use shellfish bed or algae for habitat. Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect windowpane EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of windowpane juveniles and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Trawling surveys indicate that windowpane flounder decreased at the nearfield site but increased at the farfield sites (Table D-1-9). However, the confidence intervals overlapped, suggesting that this relationship would not be statistically significant. NAI (2010) did not report whether or not the relationship was statistically significant. These monitoring results suggest that Seabrook operation is not likely to adversely affect EFH of adult and juvenile windowpane.
Conclusion. Because entrainment of windowpane eggs and impingement of juveniles and adults were relatively common at Seabrook, the NRC staff concludes that Seabrook operation may have minimal adverse effects on EFH for windowpane during the remainder of the facilitys operating license or during the proposed license renewal term. Impact would be minimal because the thermal plume quickly rises to the surface, forage species and shellfish beds are
63 not likely to be adversely affected by Seabrook operations, and monitoring data shows similar trends at nearfield and farfield sites.
D-1.3.3.17 Winter flounder (Pleuronectes americanus) (All Life Stages)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated eggs, larvae, juvenile, and adult winter flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed winter flounder larvae in greater than 10 percent of ichthyoplankton tows, juveniles and adults in greater than 10 percent of trawling samples, in 1 to 10 percent of gill net samples, and in more than 10 percent of seine pull samples (Table D-1-2).
Species Description. There are three stocks of winter flounder in the Atlanticthe Gulf of Maine, southern New England and the Middle Atlantic, and Georges Bank (Pereira et al. 1999).
In New England, winter flounder are common in inshore and nearshore waters (Pereira et al. 1999). Adult winter flounder are a small-mouthed, right-eyed flounder that grow to 23 in.
(58 cm) in total length and live up to 15 years (Pereira et al. 1999).
Adult winter flounder migrate inshore to bays and estuaries in the fall and early winter to spawn and may remain inshore year-round in areas where temperatures are 59° F (15° C) or lower and enough food is available (Pereira et al. 1999). Studies vary widely on the age of maturity of winter flounder. Generally, sexual maturity is dependent on size rather than age, and southern individuals reach spawning size more rapidly than northern fish. North of Cape Cod, OBrien et al. (1993) determined that the median age of maturity was 11.7 in. (29.7 cm) for females and 10.9 in. (27.6 cm) for males. In the Hampton-Seabrook area, winter flounder spawn in coastal waters from February through April. Females spawn at depths of 7 to 60 ft (2 to 79 m) over sandy substrates in inshore coves and inlets at salinities of 31 to 32.5 parts per thousand (ppt)
(Buckley 1989; Pereira et al. 1999). Eggs are demersal, stick to the substrate (such as gravel or algal fronds), and are most often found at salinities between 10 and 30 ppt (Buckley 1989; Crawford and Cary 1985). Larvae initially are planktonic but become increasingly benthic as they develop (Pereira et al. 1999). Juveniles and adults are completely benthic. Able et al.
(1989, cited in Pereira et al. 1999) reported that juveniles use macroalgae. Juveniles move seaward as they grow, remaining in estuaries for the first year (Buckley 1989; Grimes et al. 1989). Adult winter flounder tolerate salinities of 5 to 35 ppt and prefer waters temperatures of 32 to 77° F (0 to 25° C).
Winter flounder larvae feed on small invertebrates, invertebrate eggs, and phytoplankton (Buckley 1989; Pereira et al. 1999). Adults feed on benthic invertebrates such as polychaetes, cnidarians, mollusks, and hydrozoans. Adults and juveniles are an important food source for predatory fish such as the striped bass (Morone saxatilis), bluefish, goosefish, spiny dogfish, and other flounders, and birds such as the great cormorant (Phalacrocorax carbo), great blue heron (Ardea herodias), and osprey (Pandion haliaetus) (Buckley 1989).
Status of the Fishery. Winter flounder are highly abundant in estuarine and coastal waters and, therefore, are one of the most important species for commercial and recreational fisheries on the Atlantic coast (Buckley 1989). Winter flounder are, generally, commercially harvested using otter trawl, but the species is also a popular recreational fish. Commercial landings of winter flounder peaked in the 1980s throughout its range and declined through the early 2000s (Brown and Gabriel 1998; Pereira et al. 1999). Commercial landings reached a record low in 2005 at 2.98 million lb (1,350 MT) but have increased slightly since, with landings at 3.58 million lb (1,622 MT) in 2007 (NEFSC 2008).
The NEFMC manages the winter flounder in Federal waters under the northeast multispecies FMP. As of 2009, the NEFMC reported that the Gulf of Maine winter flounder stock is overfished (NOAA 2010).
64 Entrainment and Impingement. Entrainment of winter flounder eggs varied from 0 in most years to 1.05 million in 2008 (NAI 2010). Annual average entrainment of winter flounder eggs was 96,500 per year from 1990 through 2009 (Table D-1-4). Winter flounder eggs comprised less than 1 percent of the total fish eggs entrained at Seabrook from 1990 through 2009.
Entrainment of winter flounder larvae varied from 0 in 1994 to 34.8 million in 2004 (NAI 2010).
Annual average entrainment of winter flounder larvae was 9.2 million per year from 1990 through 2009 (Table D-1-5). Winter flounder larvae was the eighth most commonly entrained species, comprising 3.4 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of winter flounder varied from 102 in 2000 to 10,491 in 2003 (NAI 2010). Annual average impingement was 2,082 fish per year from 1994 through 2009 (Table D-1-6). Winter flounder was the third most commonly impinged fish species, comprising 10 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of winter flounder larvae and impingement of juveniles and adults were relatively common at Seabrook, the NRC staff concludes that entrainment and impingement may have minimal adverse effects on EFH for winter flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of water (or habitat) captured in the Seabrook cooling system would be a very small proportion of available habitat for all stages of winter flounder.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to eggs, larvae, juvenile, or adult winter flounder. Winter flounder are primarily benthic (Pereira et al. 1999.) A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991). Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for winter flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Winter flounder feed on phytoplankton, small invertebrates, invertebrate eggs, and benthic invertebrates such as polychaetes, cnidarians, mollusks, and hydrozoans. NextEras monitoring studies show relatively similar trends prior to and during operations at nearfield and farfield sampling sites for the abundance, density, and species composition of zooplankton and invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect winter flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Window flounder eggs may be deposited on macroalgae (Crawford and Carey 1985), but spawning occurs in estuaries and NAI (2010) did not observe winter flounder eggs in monitoring studies near Seabrook, likely due to its offshore location.
Able et al. (1989 in Pereira et al. 1999) reported that juveniles use macroalgae habitat, along with other types of habitats. Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling stations since operations began (NAI 2010). Because juvenile winter flounder may utilize macroalgae habitat, along with other types of aquatic vegetation, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook may have minimal adverse effects on juvenile winter flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of winter flounder larvae, juveniles, and adults prior to and during operations at sampling sites near the intake and
65 discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of larvae decreased at both nearfield and farfield sampling sites (Table D-1-8). Trawling data for juveniles and adults indicated different trends at the nearfield and farfield sites (NAI 2010). At the nearfield site, the abundance of winter flounder significantly decreased over time from a mean CPUE of 5.5 prior to operations to 2.3 during operations (Table D-1-9). However, at both farfield sampling sites, the mean CPUE increased from 2.8 and 1.4 prior to operations, respectively, to 4.0 and 3.6 during operations. This increase was statistically significant at one of the farfield sites. Based on monitoring data, NRC concludes that Seabrook operation has adversely affected EFH for winter flounder because the abundance of winter flounder has decreased to a greater and observable extent near Seabrooks intake and discharge structures compared to 3 to 4 mi (5 to 8 km) away.
Conclusion. Based on the above analysis, the NRC staff concludes that Seabrook operations may adversely affect EFH for winter flounder larvae, juveniles, and adults for the following reasons:
Entrainment of winter flounder larvae and impingement of juveniles and adults were relatively common at Seabrook.
Juveniles may use algal habitats that have declined near Seabrook since operations began.
Ault and juvenile winter flounder abundance decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
D-1.3.3.18 Yellowtail flounder (Pleuronectes ferruginea) (Juveniles and Adults)
Designated EFH in the Vicinity of Seabrook. The NMFS has designated juvenile and adult yellowtail flounder EFH in the vicinity of Seabrook (NMFS 2011b). NAI (2010) observed yellowtail flounder in greater than 10 percent of trawling samples, in less than 1 percent of gill net samples, and in less than 1 percent of seine pull samples (Table D-1-2).
Species Description. Yellowtail flounder occur along the U.S. and Canadian coasts from the Gulf of St. Lawrence, Labrador, and Newfoundland to the Chesapeake Bay (Bigelow and Schroeder 1953; Johnson et al. 1999). Juveniles and adults are asymmetrical benthic flatfish (Johnson et al. 1999). Preferred habitat includes areas covered in sand or sand-mud sediments where demersal prey inhabits (Bowering and Brodie 1991; Johnson et al. 1999).
Juvenile yellowtail flounder consume primarily polychaetes while adult yellowtail flounder consume primarily crustaceans, such as amphipods and sand dollars (Echinarachius parma)
(Johnson et al. 1999). Predators include spiny dogfish, winter skate, Atlantic cod, Atlantic halibut, fourspot flounder, goosefish, little skate, smooth skate, silver hake, bluefish, and sea raven (Johnson et al. 1999).
Status of the Fishery. Yellowtail first became commercial desirable in the 1930s and is currently a highly targeted fish (Johnson et al. 1999). In 2009, NEFMC considered yellowtail overfished (NMFS 2010b).
Entrainment and Impingement. Although NMFS has not designated EFH for yellowtail flounder eggs and larvae, entrainment and impingement can adversely affect recruitment of juveniles and adults. Entrainment of yellowtail flounder eggs varied from 0 in multiple years to 569.2 million in 1991 (NextEra 2010a). Annual average entrainment of yellowtail flounder eggs was 42.8 million per year from 1990 through 2009 (Table D-1-4). Yellowtail flounder eggs was the sixth most commonly entrained fish egg species, comprising 4.8 percent of the total fish eggs entrained at Seabrook from 1990 through 2009.
66 Entrainment of yellowtail flounder larvae varied from 0 in 1994 to 2.7 million in 2007 (NAI 2010).
Annual average entrainment of winter flounder larvae was 0.4 million per year from 1990 through 2009 (Table D-1-5). Yellowtail flounder larvae comprised less than 1 percent of the total fish larvae entrained at Seabrook from 1990 through 2009.
Impingement of yellowtail flounder varied from 0 in several years to 1,149 in 1995 (NAI 2010).
Annual average impingement was 83 fish per year from 1994 through 2009 (Table D-1-6).
Yellowtail flounder comprised less than 1 percent of all impinged fish at Seabrook from 1994 through 2009.
Because entrainment of yellowtail flounder eggs was relatively common at Seabrook, the NRC staff concludes that entrainment may have minimal adverse effects on EFH for yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Effects would likely be minimal since the amount of weather (or habitat) entrained in the Seabrook cooling system would be a very small proportion of available habitat for yellowtail flounder eggs.
Thermal Effects. The NRC staff does not expect Seabrooks thermal discharges to reduce available habitat to juvenile or adult yellowtail flounder. Juvenile and adult yellowtail flounder are benthic flatfish (Johnson et al. 1999). A relatively small area near the discharge structure in deep water experiences increased temperatures (NAI 2001; Padmanabhan and Hecker 1991).
Because the buoyant thermal plume at the discharge points quickly rises toward the surface, the NRC staff concludes that the heated effluent from Seabrook is not likely to adversely affect EFH for yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Forage Species. Juvenile yellowtail flounder consume primarily polychaetes while adult yellowtail flounder consume primarily crustaceans, such as amphipods and sand dollars (Johnson et al. 1999). NextEras monitoring studies show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for invertebrates (NAI 2010). Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect yellowtail flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Loss of Habitat-forming Species. Juvenile and adult yellowtail flounder do not commonly use kelp or shellfish beds. Therefore, the NRC staff concludes that the potential loss of habitat-forming species at Seabrook is not likely to adversely affect yellowtail flounder EFH during the remainder of the facilitys operating license or during the proposed license renewal term.
Combined Impacts (Monitoring Data). NextEra monitored the abundance of yellowtail flounder juveniles and adults prior to and during operations at sampling sites near the intake and discharge structures and at sites 3 to 4 mi (5 to 8 km) away (NAI 2010). Monitoring data indicate that the abundance of juveniles and adults decreased at both nearfield and farfield sampling sites (Table D-1-9). Because NAI (2010) found similar trends at both the nearfield and farfield sites, these monitoring results suggest that Seabrook operations have not adversely affected EFH for juvenile or adult yellowtail.
Conclusion. Because entrainment of yellowtail flounder eggs was relatively common at Seabrook, Seabrook operation may have minimal adverse effects on EFH for juvenile and adult yellowtail flounder during the remainder of the facilitys operating license or during the proposed license renewal term. Impacts would be minimal for the following reasons:
67 Impingement and entrainment are relatively low for yellowtail flounder.
The thermal plume quickly rises to the surface.
Forage species and shellfish beds are not likely to be adversely affected by Seabrook operations.
Monitoring data show similar trends at nearfield and farfield sites.
D-1.3.3.19 Essential Fish Habitat Species Not Likely to Regularly Occur Near Seabrook The NMFS has designated EFH for eggs, larvae, juvenile and adult Atlantic halibut; adult bluefin tuna; larvae, juvenile, and adult redfish; and juvenile and adult longfin inshore squid and northern shortfin squid in the vicinity of Seabrook (NMFS 2011b). NAI (2010) never, rarely, or occasionally observed Atlantic halibut, bluefin tuna, redfish, northern shortfin squid, and longfin inshore squid during monitoring, entrainment, and impingement studies from the 1970s through 2009. For example, NAI (2010) rarely identified Atlantic halibut in trawling surveys and did not report Atlantic halibut in any other monitoring surveys or any impingement or entrainment studies. NAI (2010) occasionally identified redfish in trawling surveys and did not report redfish in other monitoring surveys or any impingement or entrainment studies. Bluefin tuna were not reported in any monitoring, entrainment, or impingement studies. Seabrook did not explicitly include longfin inshore squid and northern shortfin squid in its entrainment and impingement studies. However, field technicians did not recall any time that squid have been impinged at Seabrook (NRC 2011). Longfin inshore squid lay eggs on the seafloor and larvae are often found near the surface, whereas the intake structure is located in deeper water (Jacobson 1995). Northern shortfin squid eggs and larvae are pelagic, but primarily occur within the Gulf Stream (Hendrickson and Holmes 2004).
Bluefin tuna, longfin inshore squid, and northern shortfin squid are pelagic and, therefore, could encounter the thermal plume when passing by Seabrook. Surface waters near the thermal plume typically range as high as 65.8° F (18.8° C) (NAI 2001). NEFSC trawl data indicate that northern shortfin squid inhabit waters up to as 66° F (19° C), and longfin inshore squid inhabit waters up to as 79° F (26° C) (NAI 2001). With a temperature rise of 3 to 5° F (1.7 to 2.8° C),
the thermal plume near the surface could exceed the typical temperature range for northern shortfin squid but would be within the typical temperature range for longfin inshore squid.
Bluefin tuna have never been captured in any of NextEras monitoring study; therefore, the relatively small size of the thermal plume is not likely to adversely affect large amounts of EFH for bluefin tuna if any happen to pass by Seabrook. The thermal plume is not likely to adversely affect EFH for Atlantic halibut or redfish because both of these species are pelagic and the thermal plume rises quickly to the surface.
Bluefin tuna, longfin inshore squid, and northern shortfin squid are pelagic and, therefore, not likely to regularly inhabit benthic habitats such as kelp forest or shellfish beds. Redfish and Atlantic halibut may use kelp near Seabrook, along with other habitats that provide structure.
Seabrook monitoring data indicate that the density of several species of kelp has decreased at nearfield sampling sites since operations began (NAI 2010). Because the density of kelp is lower since operations began at Seabrook, but Atlantic halibut and redfish rarely or occasionally use habitat near Seabrook, the NRC staff concludes that Seabrook operations may have minimal adverse effects on Atlantic halibut and redfish.
Forage species for Atlantic halibut, bluefin tuna, redfish, longfin inshore squid, and northern shortfin squid are not likely to be adversely affected near Seabrook. Typical prey includes copepods, euphausiids, crabs, polychaetes, shrimp, and fish. NextEras monitoring studies 68 show relatively similar trends in abundance prior to and during operations at nearfield and farfield sampling sites for zooplankton, benthic invertebrates, and most fish species (NAI 2010).
Therefore, the NRC staff concludes that the potential loss of forage species at Seabrook is not likely to adversely affect EFH for Atlantic halibut, bluefin tuna, redfish, longfin inshore squid, or northern shortfin squid during the remainder of the facilitys operating license or during the proposed license renewal term.
Based on the above analysis, the NRC staff concludes that Seabrook operations may have minimal adverse effects on EFH for northern shortfin squid because the thermal plume near the surface could exceed the typical temperature range for northern shortfin squid. Seabrook operations may have minimal adverse effects on EFH for redfish and Atlantic halibut because both species may use kelp beds near Seabrook. Seabrook operations are not likely to affect EFH for longfin inshore squid or bluefin tuna.
Cumulative Effects to Essential Fish Habitat This section addresses the direct and indirect effects of license renewal on EFH when added to the aggregate effects of other past, present, and reasonably foreseeable future actions. The geographic area considered in the cumulative aquatic resources analysis includes the vicinity of Seabrook, the offshore intake and discharge structures, the Hampton-Seabrook Estuary, and the rivers that drain into the Hampton-Seabrook Estuary.
Section 2.2.6.2 of the SEIS summarizes the condition of the Gulf of Maine and the Hampton-Seabrook Estuary and the history and factors that led to its current condition. The direct and indirect impacts from fishing are some of the most influential human activities on the Gulf of Maine ecosystem (Sosebee et al. 2006). Fishing has caused wide-scale changes in fish populations and food web dynamics within the Gulf of Maine (Sosebee et al. 2006; Steneck et al. 1994). In the Hampton-Seabrook Estuary, wetland habitat and water flow has been affected by human uses such as those listed below (Eberhardt and Burdick 2009):
harvesting salt marsh hay (Spartina patens) as feed for livestock in the 1700 and 1800s, digging ditches in an attempt to control mosquito populations in the early 1900s, and building roads, jetties, commercial buildings, and residential areas in the 1900s and 2000s.
The increased urbanization in the past 100 years has caused increased runoff and levels of pollutants within the Hampton-Seabrook Estuary (NHDES 2004). In the rivers connected to Hampton-Seabrook Estuary, dams block fish migrations and have resulted in the precipitous decline of anadromous fish that move to freshwater to spawn and to marine waters to grow and feed (Eberhardt and Burdick 2009).
Many natural and anthropogenic activities can influence the current and future EFH in the area surrounding Seabrook. Potential biological stressors include continued entrainment, impingement, and potential heat shock from Seabrook (if the license renewal is granted), and fishing mortality, climate change, energy development, and urbanization, as described below.
Fishing. Fishing has been a major influence on the population levels of commercially sought fish species in the Gulf of Maine (Sosebee et al. 2006). The Hampton-Seabrook Estuary and the Gulf of Maine support significant commercial and recreational fisheries for many of the fish and invertebrate species also affected by Seabrook operations. EPA (2002b) determined that 69 percent of all entrained and impinged fish species at Seabrook are commercially or recreationally fished. From 1990 through 2000, Atlantic cod comprised 33 percent of the catch in New Hampshire and 25 percent of the revenue. Other commercially important and EFH
69 species in New Hampshire include spiny dogfish shark, pollock, Atlantic herring, bluefin tuna, American plaice, white hake, yellowtail flounder, and shrimp. Recreationally fished species include American lobster, striped bass, summer flounder, Atlantic cod, scup, and bluefish (EPA 2002b). Federal, regional, and State agencies manage many of these fisheries, although the biomass of many fish stocks have not rebounded to pre-1960s levels (Sosebee 2006).
Indirect impacts from fishing include habitat alteration as well as indirect effects that propagate throughout the food web.
For these reasons, the NRC staff concludes that fishing pressure has the potential to continue to influence the aquatic ecosystem, especially food webs, and may continue to contribute to cumulative impacts on EFH.
Climate Change. The potential cumulative effects of climate change on the Gulf of Maine and Hampton-Seabrook Estuary could result in a variety of changes that would affect EFH. The environmental factors of significance identified by the U.S. Global Change Research Program (USGCRP) (2014) include temperature increases, coastal flooding, and sea level rise. From 1982 to 2006, sea surface temperatures in coastal waters of the Northeast warmed almost twice the global rate (USGCRP 2014). In the Gulf of Maine, sea surface temperature in 1999, 2002, and 2006 were the 4th, 5th, and 6th warmest years, respectively, on the record (Drinkwater et al. 2009). Projections from coarse-scale climate models coupled with finer-scale models suggest that spring sea surface temperatures in the Gulf of Maine may increase by about 2.2 °C (3.9 °F) in the 2080s under the high emission scenario (Frumhoff et al. 2007; NMFS 2011e).
Warming sea temperatures may influence the abundance and distribution of species, as well as earlier spawning times. Since 1968, species in the New England coastal waters have shifted their geographic distribution northward by up to 200 miles (USGCRP 2014). The USGCRP (2014) projects that lobster populations will decline and continue to shift northward in response to warming sea temperatures. Atlantic cod, which were subject to intense fishing pressure and other biological stressors, are likely to be adversely affected by the warmer temperatures since this species inhabits cold waters (USGCRP 2014). USGCRP (2009) projects that the Georges Bank Atlantic cod fishery is likely to be diminished by 2100. NMFS (2009) analyzed fish abundance data from 1968-2007 and determined that the range of several species of fish are moving northward or deeper, likely in response to warming sea temperatures.
Warmer temperatures can also lead to earlier spawning since spawning time is often correlated with a distinct temperature range. Seabrook monitoring studies showed a shift in blue mussel spawning times (NAI 2010). From 1996-2002, and select years from 2002-2009, the greatest blue mussel larval density occurred in mid-April, whereas the greatest blue mussel larval density occurred in late April in the 1970s, 1980s, and early 1990s. Furthermore, rising sea temperatures have been linked to marine-life diseases (USGCRP 2014). Increased disease outbreaks due to increase water temperatures can lead to increased mortality of marine life, which can then further change habitat and species relationships than ultimately affect the ecosystem.
Increased water temperatures from climate change may overlap with the impacts from Seabrooks cooling water system. For example, in the area near the discharge, the combined impacts of the thermal discharge and increase water temperature from climate change could push temperatures above the thermal thresholds of cold-water species (NMFS 2011e).
While there is great uncertainty, sea levels are expected to rise between 0.5 and 1 ft (0.15 to 0.3 m) by 2050 and by 1 to 4 ft (0.3 to 1.2 m) by the end of this century; sea level rise along the Northeast coast is expected to exceed the global rate due to local land subsidence and projected to rise 1.3 to 1.7 ft ( 0.4 to 0.5 m) by 2050 (USGCRP 2014). Sea level rise could result in dramatic effects to nearshore communities and EFH, including the reduction or 70 redistribution of kelp, eelgrass, and wetland communities. Aquatic vegetation is particularly susceptible to sea level rise because it is immobile and cannot move to shallower areas. In addition, most species grow within a relatively small range of water depth in order to receive sufficient light to photosynthesize.
The ocean absorbs nearly one-third of the carbon dioxide (CO2) released into the atmosphere (NMFS 2011d). As atmospheric CO2 increases, there is a concurrent increase in CO2 levels in the ocean (NMFS 2011d). Ocean acidification is the process by which CO2 is absorbed by the ocean, forming carbonic and carbolic acids that increase the acidity of ocean water. More acidic water can lead to a decrease in calcification (or a softening) of shells for bivalves (e.g., Atlantic sea scallops and Atlantic surf clams), decreases in growth, and increases in mortality in marine species (Nye 2010, USGCRP 2014). Ocean acidification is projected to continue due to the interaction between ocean water and atmospheric carbon dioxide concentrations (USGCRP 2014).
The extent and magnitude of climate change impacts to the aquatic resources of the Gulf of Maine and the Hampton-Seabrook Estuary are an important component of the cumulative assessment analyses and could be substantial.
Energy Development. As part of a technical workshop held by NOAA, Johnson et al. (2008) categorized the largest non-fishing impacts to coastal fishery habitats. Johnson et al. (2008) determined that the largest known and potential future impacts to marine habitats are primarily from the development of energy infrastructure, including petroleum exploration, production, and transportation; liquefied natural gas development; offshore wind development; and cables and pipelines in aquatic ecosystems.
Petroleum explorations and offshore wind development can result in habitat conversion and a loss of benthic habitat as developers dig, blast, or fill biologically productive areas. Petroleum and liquefied natural gas development can adversely affect water quality if there are oil spills or discharges of other contaminants during exploration-or transportation-related activities.
Underwater cables and pipelines may block fish and other aquatic organisms from migrating to various habitats (Johnson et al. 2008). Thus, energy development may contribute to future cumulative impacts in a variety of ways.
Urbanization. The area surrounding the Hampton-Seabrook Estuary experienced increased residential and commercial development in the 1900s, as the seaside town became a popular tourist destination (Eberhardt and Burdick 2009). At the beginning of the 21st century, moderate commercial and residential development surrounded the Hampton-Seabrook Estuary (NHNHB 2009). The town of Hamptons Master Plan calls for continued growth in the area to sustain its attractiveness for tourists (Hampton 2001).
Increased urbanization has led, and will likely continue to lead, to additional stressors on the Hampton-Seabrook Estuary. Runoff from developed and agricultural areas has increased the concentration of nutrients, bacteria, and other pollutants to the estuary. Sections of the Hampton-Seabrook Estuary are listed on New Hampshires 303(d) list as being impaired due to high concentrations of bacteria (NHDES 2004). NHDES (2004) also lists the estuary as impaired for fish and shellfish consumption due to polychlorinated biphenyl, dioxin, and mercury concentrations in fish tissue and lobster tomalley. Other activities that may affect marine aquatic resources in Hampton-Seabrook Estuary include periodic maintenance dredging, continued urbanization and development, and construction of new overwater or near-water structures (e.g., docks), and shoreline stabilization measures (e.g., sheet pile walls, rip-rap, or other hard structures).
71 Future threats to salt marshes in the Hampton-Seabrook Estuary include developmental activities that further hydrological alterations from filling wetlands or other physical changes that alter the flow of tidal waters (Johnson et al. 2008; NHNHB 2009). Increased nutrients and pollutants in storm runoff are also current threats to the health of this ecosystem (NHNHB 2009). The NRC staff concludes that the direct and indirect impacts from future urbanization are likely to contribute to cumulative impacts in the Hampton-Seabrook Estuary.
Conclusion. The direct impacts to fish populations, from fishing pressure and alterations of aquatic habitat within the Hampton-Seabrook watershed from past activities, have had a significant effect on aquatic resources in the geographic area near Seabrook. These aquatic ecosystems have been adversely affected, as evidenced by the low population numbers for several commercially sought fisheries, the change in food web dynamics, habitat alterations, and the blockage of fish passage within the Hampton-Seabrook watershed. The cumulative stress from the activities described above, spread across the geographic area of interest, depends on many factors that NRC staff cannot quantify but are likely to adversely affect EFH when all stresses on the aquatic communities are assessed cumulatively. Therefore, the NRC staff concludes that the cumulative impacts from the proposed license renewal and other past, present, and reasonably foreseeable projects may adversely affect the EFH of most species, especially Atlantic cod due to climate change.
Essential Fish Habitat Conservation Measures NextEra prepared a proposal for information collection (PIC) as a first step to comply with EPAs 2004 proposed Phase II rule of Section 316(b) of CWA (NAI and ARCADIS 2008). In this document, NextEra identified three types of mitigation that are now in place and reduce entrainment and impingement (NAI and ARCADIS 2008). First, the location of the intake structures is offshore in an area of reduced biological activity as compared to an inshore location. Second, the design of the intake structures includes velocity caps, which fish tend to avoid due to the changes in horizontal flow of water created by the velocity cap. Third, less water is pumped from the Gulf of Maine to Seabrook due to the offshore location, which provides cooler water than an inshore location (NAI and ARCADIS 2008).
The Seabrook intake structures also have behavioral and structural deterrents to minimize impingement and entrainment. For example, the intake structure design includes velocity caps, which fish tend to avoid due to the changes in horizontal flow of water created by the velocity cap. In addition, NextEra installed a seal deterrent system by adding vertical bars on intake structures to prevent seals from getting trapped and drowning (NextEra 2010c).
Additional Mitigation Measures Additional intake technologies that might mitigate cooling water intake effects and other efforts that could mitigate impacts to aquatic resources are described in the following sections. The first three potential mitigation measures, including wedgewire screens, grey water, and variable frequency drives were included in NextEras assessment of additional potential mitigation options when responding to EPA in support of its Phase II 316(b) Program (ARCADIS 2008).
The other potential mitigation measures were suggested in comments on the draft SEIS. In addition, in their comments on the draft SEIS, EPA, NMFS, and New Hampshire Department of Environmental Services (NHDES) recommended that NRC staff evaluate the environmental impacts of a cooling system alternative. In response to these comments, NRC evaluated a closed-cycle cooling system alternative in Chapter 8. Therefore, closed-cycle cooling is not addressed further in this chapter.
Wedgewire Screens 72 In some cases, the use of wedgewire screens has shown potential for decreasing entrainment and impingement at once-through power plants. Wedgewire screens may reduce entrainment and impingement by physical exclusion and exploiting hydrodynamic patterns (EPA 2004). Fish and other aquatic resources are physically excluded from the intake if the screens mesh is smaller than the size of the organism. Hydrodynamic exclusion occurs because the screens cylindrical configuration helps to create a low through-slot velocity that is quickly dissipated. In this situation, organisms can escape the flow field by swimming faster than the through-slot velocity and as the ambient currents assist organisms in bypassing the intake. Factors influencing the use and effectiveness of this technology include the screen size, the location, the configuration of the system relative to the intake, the intake flow rates, the presence and magnitude of a sweeping current that can move organisms past the screen into safe water, and the size of the organism present near the intake.
NextEra considered wedgewire screens to potentially reduce impingement and entrainment at Seabrook (ARCADIS 2008). The proposed screens would be located at offshore intakes, which would require modification of the velocity caps currently installed. Three screens would be installed on each of the three velocity caps for a total of nine screens. The screens would have 0.25 in (6.4 mm) openings. With this configuration, the anticipated through screen velocity would be 0.5 feet per second (fps). In addition to the screens and velocity cap modifications, NextEra would need to install an air burst system for cleaning the screens (ARCADIS 2008). All construction activities would occur underwater at approximately 60 ft (18 m) depth.
EPA (2004) describes three conditions for wedgewire screens to be effective: 1) the screen size is small enough to physically exclude organisms, 2) the through screen velocity is low, typically 0.5 fps or less, and 3) there is sufficient ambient currents to aid organisms in bypassing the intake structure and to remove other debris from the screen face. ARCADIS (2008) determined that the second condition could be meet at Seabrook. The third condition may not be met because the ambient currents near the intakes do not always parallel the longitudinal axis of the screens (ARCADIS 2008). The first condition cannot be met at Seabrook because the possibility of significant biofouling prevents the use of a screen size small enough (1 m [0.04 in]) to physically exclude eggs and larvae (ARCADIS 2008). At the deep underwater location of the Seabrook intakes (60 ft (18 m) depth), ARCADIS (2008) anticipated heavy biofouling that would not likely be completely cleared by the use of an air burst system. To prevent biofouling on wedgewire screens at a facility in Boston Harbor, the screens are manually cleaned once a month by physically removing the screens and pressure washing them out of the water. At Seabrook, manual cleaning would require divers, which would be costly and timely (ARCADIS 2008). In addition to organisms growing on the screens, kelp could also block the screens, which has the potential to quickly cover the screens causing a rapid loss of cooling water and the air burst system may not be effective in removing the kelp from the screen (ARCADIS 2008). This situation could cause an operational risk.
In conclusion, ARCADIS (2008) determined that wedgewire screens are not a suitable intake technology because of the significant increase in operational risk of failure and potential maintenance efforts.
Grey Water The use of grey water, or treated wastewater, would reduce impacts from impingement and entrainment because the grey water would be used in place of withdrawing water from the Gulf of Maine. No impingement or entrainment would be associated with the use of grey water because the cooling water would come from water pollution control plants (WPCPs).
NextEra considered using grey water to reduce impingement and entrainment at Seabrook (ARCADIS 2008). The three WPCP within 15 mi (24 km) of Seabrook include the Seabrook
73 WPCP, and Portsmouth WPCP, and the Hampton WPCP (ARCADIS 2008). ARCADIS (2008) estimated that these three WPCPs could provide approximately 5 to 6 mgd, which is less than 1 percent of Seabrooks daily cooling water requirements (682 mgd).
ARCADIS (2008) estimated that the reduction in impingement and entrainment would be approximately less than 1 percent. In addition, a variety of environmental impacts would result from construction and operation of pipelines to transport the grey water from the WPCPs to Seabrook. These impacts would likely be greatest in wetlands and salt marsh areas, which provide high quality habitat for terrestrial and aquatic resources. Given the location of Seabrook and the WPCPs, wetlands and salt marshes would be difficult to avoid. In addition, NextEra would need to acquire ROWs, which could be on or adjacent to private land, recreational areas, or high quality terrestrial and aquatic habitats.
NextEra concluded that the use of grey water was not a suitable option for reducing impingement and entrainment because the reduction in impingement and entrainment would be essentially imperceptible (ARCADIS 2008). Further, the permitting, engineering, and construction of the pipelines would be difficult and would result in a variety of environmental impacts, as described above.
Variable Frequency Drives Variable frequency drives (VFDs) can reduce impingement and entrainment by reducing the amount of water withdrawn for cooling water. VFDs on the circulating water pump motors reduce the pump speed, which in turn reduces the pump flow. Harish et al. (2010) created a theoretical model that demonstrated that VFD would reduce withdrawal rates, but the discharge temperature would increase. This research suggests that VFDs may decrease impingement and entrainment because less water and organisms would be pulled through the cooling system, although VFDs may increase thermal impacts because the discharge would be released at a higher temperature.
NextEra considered VFDs to reduce the withdrawal requirements at Seabrook (ARCADIS 2008). ARCADIS (2008) determined that a VFD could be installed on each of the three circulating water pump motors. Each VFD enclosure would be over 20 ft (6.1 m) long and, therefore, installed on the outside of the turbine building (ARCADIS 2008).
ARCADIS (2008) determined that the three VFDs would reduce the minimum flow achievable to 250,000 gpm (360 mgd). This would result in an approximate 8 to 30 percent decrease in cooling water withdrawal, depending on the season and water temperature. The greatest reductions would occur in the winter and spring when the water is coolest. ARCADIS (2008) estimated that the use of VFDs would reduce entrainment by 4 percent. However, the use of VFDs would also increase the discharge temperature from 39 °F (3.9 °C) to 45 °F (7.2 °C),
thereby increasing potential thermal impacts and exceeding the limits of Seabrook's NPDES discharge.
NextEra concluded that installing and operating three VFDs is feasible in terms of operation.
However, it would require Seabrook to obtain a new NPDES permit that would increase the allowable temperature of the discharge water.
Other Potential Mitigation In its comments on the draft SEIS, NMFS suggested that NextEra conduct additional studies to understand the causative agent for the decline in macroaglae near Seabrook. For example, various studies could be conducted to better understand whether the decline was due to Seabrooks thermal discharge or other activities. Similarly, NMFS suggested that NextEra 74 conduct studies that test whether changes in benthic fish communities near the Seabrook discharge (NMFS 2011e):
are the result of thermal effects from the discharge plume, such as avoidance of the thermal plume by juvenile and adult life stages or from mortality reduced fitness of egg and larval stages that may settle to the bottom in this area, or a result of eggs and larvae that are lost to the general area from impingement and entrainment in the cooling water system.
In its comments on the draft SEIS, NHFGD identified two potential mitigation projects that would mitigate potential impacts to winter flounder and rainbow smelt, which are important commercial and recreational fish. As described in Appendix A, NHFGD suggested that NextEra fund projects that would reduce the point and nonpoint sources of nitrogen loading in the Great Bay Estuary System watershed to potentially improve habitat for juvenile winter flounder and rainbow smelt. NHFGD also suggested that NextEra could compensate businesses that rely on winter flounder catch for income.
Conclusion Table D-1-13 summarizes NRC conclusions on the effect of Seabrook operation on habitat for the 23 EFH species that may occur within the vicinity of Seabrook.
Table D-1-13. Summary of NRC conclusions Regarding the Effect on Habitat by Species and Life Stages Species Eggs Larvae Juveniles Adults Rational for adverse impact American plaice NL(a)
NL Atlantic butterfish NL NL NL NL Atlantic cod NL MIN(b)
MIN MIN Some of the primary and preferred forage fish, such as Atlantic herring and American sand lance, are regularly entrained and impinged at Seabrook; the thermal plume near the surface could slightly exceed the typical range of temperatures that Atlantic cod inhabit; juvenile cod likely use kelp beds near Seabrook.
Atlantic halibut NL NL MIN MIN Atlantic halibut may use algal habitats that have declined near Seabrook since operations began.
Atlantic herring MIN MIN The thermal plume near the surface could slightly exceed the typical range of temperatures that Atlantic herring juveniles and adults inhabit.
Atlantic mackerel MIN NL NL MIN Atlantic mackerel is the second most entrained egg species, comprising 21.3 percent of the total fish eggs entrained at Seabrook. The thermal plume near the surface could exceed the typical temperature range that adult Atlantic mackerel inhabit.
Atlantic sea scallop NL NL MIN NL Newly settled Atlantic sea scallops may use algal habitats that have declined near Seabrook since operations began.
Atlantic surf clam NL NL Bluefin tuna NL Haddock NL
75 Species Eggs Larvae Juveniles Adults Rational for adverse impact Longfin inshore squid NL NL Monkfish/Goosefish MIN MIN MIN NL The thermal plume near the surface could slightly exceed the typical range of temperatures that goosefish eggs and larvae inhabit; juveniles may use algal habitats that have declined near Seabrook since operations began.
Northern shortfin squid MIN MIN The thermal plume near the surface could exceed the typical temperature range for northern shortfin squid.
Ocean pout NL NL MIN NL Juveniles may use algal habitats that have declined near Seabrook since operations began.
Pollock MIN Pollock is the sixth most impinged fish species, comprising 6.1 percent of the total fish impinged at Seabrook. Juveniles may use algal habitats that have declined near Seabrook since operations began.
Redfish NL MIN MIN Redfish may use algal habitats that have declined near Seabrook since operations began.
Red hake MIN MIN MIN MIN The hake (which includes red, white, and spotted hake) comprised 6.2 percent of all entrained fish eggs and 6.5 percent of all impinged fish at Seabrook.
Scup NL NL Summer flounder MIN Summer flounder may use algal habitats that have declined near Seabrook since operations began.
Whiting/Silver hake ADV(c) ADV ADV ADV Silver hake was the third most commonly entrained egg species, comprising 9 percent of all entrained fish eggs at Seabrook. The thermal plume could exceed the typical range of temperatures that larvae and adults inhabit, and adult and juveniles decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
Windowpane flounder MIN MIN Windowpane comprised 3.5 percent of all entrained eggs and 6.2 percent of all impinged fish at Seabrook Winter flounder NL ADV ADV ADV Winter flounder was the third most commonly impinged fish species, comprising 10 percent of all impinged fish. Winter flounder larvae was the eighth most commonly entrained species, comprising 3.4 percent of the total fish larvae entrained. Winter flounder may use algal habitats that have declined near Seabrook since operations began. Adult and juvenile winter flounder abundance decreased at nearfield trawling sites but increased at farfield trawling sites in NextEra monitoring studies.
Yellowtail flounder MIN MIN Yellowtail flounder eggs was the sixth most commonly entrained fish egg species, comprising 4.8 percent of the total fish eggs entrained at Seabrook.
(a) NL= Seabrook operation is not likely to affect EFH.
(b) MIN= Seabrook operation may have minimal adverse effects on EFH.
76 Species Eggs Larvae Juveniles Adults Rational for adverse impact (c) ADV= Seabrook operation may adversely affect EFH.
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