ML20079N005

1987 Biological Monitoring Rept

ML20079N005
Person / Time
Site:	Brunswick
Issue date:	12/31/1987
From:	Benedict C, Blue R, Booth G CAROLINA POWER & LIGHT CO.
To:
References
RTR-NUREG-1437 AR, NUDOCS 9111110041
Download: ML20079N005 (100)

Text

BRUNSWICK STEAM E" ECI'RIC PLANT 1987 Biological Monitoring Report n!

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'4 BIOLOGY UNIT ENVIRONMENTAL SERVICES SECTION CP&L Carolina Fower a Light Compt;ny t'

1437 C PDR

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BRUNSWICK STEAM ELECTRIC PLANT 1987 BIOLOGICAL MONITORING REPORT I

Prepared by:

C. Benedict Juvenile and Adult Impingement R. J. Blue Editor G. F. Booth Project Scientist D. S. Cooke River Larval fish A. B. Harris Statistics W. E. Herring

' dater Quality L. W. Pollard Marsh I

T. E. Thompson Nekten M. T. Tyndall Report Compiler, Entrainment.

Larval Impingement, Survival I

Biology Unit Environmental Services Section CAROLINA POWER & LIGHT COMPANY NEW HILL, NORTH CAROLINA March 1988 Reviewed and Approved by I

%~PrincipalScientist

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Biology Unit This report was prepared under my supervision and direction, and i accept full responsibility for its content.,

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I Manager Environmental ServicesSection I

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This copy of thlt report is not a controlled document es detailed in the Biology Unit gality Assurance & Petx:edures Manual.

Any changes made to the original of this r eport subsecuent to the date

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of issuance can be obtained frce:

I e n e,e,.

Environmental services Section g

Carolins Power & Light Ccapeny gi l

Sheeron Harris Energy A f nvironmental Center l

Route 1, Bos 327 New Hill, North Carolina 27567 l

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I Acknowicdgments The authors would like to thank many irdividuals who assisted in collecting, identifying, and processing samples which made this report possible.

Thanks are extended to Debbie Calhcun, Karalec Cates, Scott Cates Della Lanier, Preston McLendon, Tina Reece, and R. G. Sherfinski.

Steve Parrish assisted in field collections as captain of the Pisce.s end I

constructed and maintained field and laboratory equipmen'6.

Thanks also go to Jce Donaghy and Kay Conaway whs assis'.ed with the data analyses for this report and to members of the Word Processing Sub-unit at the Shearon Harris Energy & Environmental Center for assistance in I

typing this report.

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I Table of Cortents Page Acknowledgments.....................................................

i List of Tab1es......................................................

iii List of figures.....................................................

v Metric-English Conversion Tab 1e.....................................

vii l

Comon and Scientif ic Names Used in This Report.....................

viii Executive Summary...................................................

ix

1.0 INTRODUCTION

1-1 2.0 CAPE FE AR E STUARY POPULATION MONITORING......................

2-1 I

2.1 Introduction.................................................

2-1 2.2 Methods......................................................

2-2 2.2.1 Sample Co11ection............................................

2-2 I

2.2.2 Data Analysis................................................

2-3 2.3 Results and Discussion.......................................

2-5 2.3.1 Water Quality................................................

2-5 I

2.3.2 Dominant :,pecies.........................................

2-6 2.3.3 Seasonal Distribution........................................

2-7 2.3.4 Spatial Distribution.........................................

2-9 2.3.5 T i me - S e r i e s A n a l y s i s.........................................

2-12 River Larval fish............................................

2-12 Harsh........................................................

2-13 Alligator Creek..............................................

2-13 I

Rott's 8a1...!.............................................. 2-14

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Wsiden Creek.................................................

2-15 Baldhead Creek...............................................

2-15 I

Nekton.......................................................

2-16 2.4 S uma ry a nd Co nc l u s i o n s......................................

2-18 3.0 PLANT-R E LA T E D MON I TOR I NG PR 0G RAMS............................ 3-1 3.1 Introduction.................................................

3-1 3.2 Methods......................................................

3-2 3.3 Results and Discussion.......................................

3-3 I

3.3.1 Dominant Species.............................................

3-3 3.3.2 Seasonality and Abundance....................................

3-4 3.3.3 Entrainment Rates............................................

3-5 I

flow Rates...................................................

3-6 3.3.4 3.3.5 flow Minimization............................................

36 3.3.6 Divers ion St ructure E valua t ion...............................

3-7 3.3.7 Survival Estimates...........................................

3-10 l

3.4 Suma ry and Conc l u s i on s.....................................

3-12

4.0 REFERENCES

4-1 I

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L List of Tables L

lab _g Pagg

[

1.1 The 1987 Crunswick Steam [lectric Plant biolo monitoring prog. am summary...................g ical 1-3 2.1 Annual mean density and the percentage of the total mean density for the most abundant taxa collected I

in the river larval fish program f rom 1982 through 1987.....

2-20 2.2 Total catch and percent total of the ten most abundant species collected in the earsh study during 1987............

2-21 2.3 Total ber, percent total number, and anr.ual catch-I per-L.,,;-effort of the ten most abundant species collected in the nek ten s tudy during 1987...................

2-22 g

2.4 Annual catch-per-unit-etfort by creek system for 13 selected species in the marsh study during 1987.............

2-23 2.5 Annual catch-per-unit-effort by station of selected organisms collected in the nekton study during 1987.........

2-24 2.;

Hean standard length by location of selected species collected in the nekton study during 1987...................

2-25 2.7 Results of time-series analysis of river larval fish data by station group indicating trends in I

density frnm September 1977 through August 1987.............

2-26 2.8 Results of time-series analysis of marsh daca by creek indicating trends in abundance from 1981 through 1987.......

2-27 2.9 Results of time-series analysis of nekton data by station group indicating trends in abundance of selected species from 1979 through 1987..................

2-28 3.1 Mean density and percent total of fish, penacid shrimp, and portunid megalops entrained at the 85EP from September 1978 through August 1987.....................

3-14 3.2 Total larvae impinged at the 8SEP during 1987, ranked by percent...........................................

3-15 3.3 A summary of juvenile and adult impingement at the BSEP during 1987 with comparisons to previous years.........

3-16 3.0 Entrainment densities at the BSEP from September 1986 through August 1987.........................................

3-17 iii

I list of Tables (continued)

Page 3.5 Total number of selected species collected by trip in larval impingement at the BSEP during 1987..................

3-19 3.6 Entrainment rates at the BSEP from September 1986 through August 1987.........................................

3-21 (CPUE + 1) and standard deviation for trawl Memlog!fjuvenileandadultspot, croaker,and 37 catches a

Atlantic menhaden collected outside and inside the BSEP g

g fish d hersion structure curing 1987........................

3-?3

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3.8 Total number, percent total number, and catch-per-unit-effort of the five most abundant species cellected in the BSEP gill net ttudy from April

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1986 through April 1987.....................................

3-24 3.9 Mean loge (CPUE + 1) and standard deviation for the five most abur: dant species collected outside and inside the BSEP fish diversion structure during the gill net study f rom April 1986 through April 1987....................

3-25 3.10 Mean percent 96-hour unadjuu d survival values for E

selected finfish held during survivel studies at the 5

BSEP during 1987....................................

3-26 3.11 Survival percentag's for organisms colluted durir.g fast-screen rotation at the BSEP from 1984 through 198J....

.;- 27 Survival percentages for organisms collected during 3.12 slow-screen rotation at the BSEP from 1984 through 1987.....

3-28 3.13 Sursival percentages for control organisms collected-E for :urvival studies at the BSEP from 1984 through 1987.....

3-29 E

I 3.14 Percent survival and number of impingea larval organisms a

f returned alive to the Cape Fear Estuary during 1987,........

3-30 g

3.15 Percent survival of juvenile and adult organisms l

impinged at the BSEP during slow-and fast-screen rotation from 1984 through 1987.......................

3-31 3.16 Esf'tated survival of juvenile and adult organisms g

impinged at the BSEP during slow screen rotation 5

in 1987.....................................................

3-32 I

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List of Figures Figure Page 1.1 Location of fish diversion structure, fish return system, and return basin at the Brunswick Steam Electric Plant......

1-4 1,2 Brunswick Steam Electric Plant Biological monitoring program sampling locations for 1987............................

1-5 l

2.1 Bottom salinity for selected stations in the Cape fear Estuary from September 1986 through December 1987......

2-29 I

2.2 Mean daily freshwater flow by month and mean bottom salinity at midriver Station HG 25 in the Cape Fear River from January 1984 through December 1987...............

2-30 2.3 Bettom temperature for selected stations in the Cape fear Estuary from Septem'oer 1986 through December 1987...........

2-31 I

2.4 Results of time-series analysis of total larval organisms collected in Dutchman Creek and Walden Creek from 1979 through 1987................................................

2-32 2.5 Results of time-series analysis of larval spot collected in the lower and upper areas of the Cape Fear Estuar 1977 through 1987...................................y from 2-33 2.6 Results of time-scries analysis of l e val Atlantic menhaden collected in the lower area of the L se Fear Estuar Walden Creek from 1977 through 1987................y and 2-34 2.7 Results of time-series analysis for blue crab collected in Alligator Creek by the marsh trawl f rom 1981 through 1987...

2-35 2.8 Annual mean log catch-per-ur.it-effort for brown shrimp collected in Alligator Creek by the marsh trawl from I

1981 through 1987...........................................

2-35 2.9 Annual mein log catch-per-unit-effect for white shrimp I

collectedinAlligatorCreekbythemarthtrawlfrom1981 through 1987................................................

2-36 I

Results of time-series analysis for white mullet collected 2.10 in Mott's Bey by the marsh trawl from 1981 through 1987.....

2-36 a

2.11 Results of time-series analysis for blue crab collected 5

in M tt's Bay by the marsh trawl from 1981 through 1987.....

2-37 2.12 Results of time-series analysis for white shrimp collected in Walden Creek by the marsh trawl from 1981 through 1987................................................

2-37 I

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List of ficures (continuedl Pag 2.13 Results of time-series analysis for Atlantic menhaden collected in Walden Creek by the marsh trawl from 19 81 t h rou g h 19 8 7...........................................

2-38 2.14 Results of time-series analysis for blue crab collected in Walden Creek by the marsh trawl from 1981 through 1987................................................

2-38 2.15 Results of time-series analysis for bay anchovy collected E

in the lower river by the nekton trawl from 1979 R

through 1987...............

2-39 2.16 Results of time-series analysis for white shrimp collected by the nekton trawl in the lower river from 1979 through 1987 compared to annual mean catch at Alligator Creek l

f rom 19 81 t h rou g h 19 8 7.....................................

2-40 2.17 Results of time-series analysis for juvenile / adult croaker collected in the lower river and Snow's Cut by the nekten 5

trawl from 1979 through 1987................................

2 41 3

2.18 Results of time-series analysis fer juvenile / adult spot g

collected in the lower river and Snow's Cut by the g

nekton trawl f rom 1979 through 1987.........................

2-42 2,19 Annual mean catch for brown shrimp collected in the lower river by the nekton trawl from 1979 through 1987 compared tu the results of time-series analysis for catches at Snow's Cut f rom 19 81 t h roug h 198 7..................................

2-43 3.1 Brunswick Steam Electric Plant intake, discharge, diversion struction, and return systems with g

associated effects on fish..................................

3-33 g

3.2 Mean raonthly flow of water pumped at the BSEP from 1977 through 19 8 2, 19 86, a nd 19 8 7...........................

3-34 3.3 Results of time-series analysis showing year level terms for juvenile / adult spot collected outsioe and inside the a

fish diversion structure by the nekton trawl from 3

1979 through 1987...........................................

3-35 3.4 Results of time-series analysis showing year level l-terms for juvenile / adult croaker collected outside and inside the fish diversion structure by the nekton g

t rawl f rom 1979 t hrou g h 1987................................

3-35 3.5 Results of time-series analysis showing year level terms for juvenile / adult Atlantic menhaden collected by the E

nekten trawl outside the fish diversion structure compared g

to annual catches inside from 1979 through 1987.............

3-36 8

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I Metric-English Conversion Table i

Length I

1 micron (um) = 4.0 x 10-5 inch 1 millimeter (mm) = 1000 um = 0.04 inch I centimeter (cm) = 10 mm = 0.4 inch 1 meter (m) = 100 cm u 3.28 feet 1 kilometer (km) = 1000 m = 0.62 mile Area I

2 1 square meter (m ) = 10.76 square feet I hectare = 10,000 m2 = 2.47 acres Weight k

1 microgram (ag) = 10-3 mg or 10-6 g = 3.5 x 10-8 ounce 1 milligram (mg) = 3.5 x 10-5 ounce 1 gram (g) = 1000 mg = 0.035 ounce l

1 kilogram (kg) = 1000 g = 2.2 pounds 1 metric ton = 1000 kg = 1.1 tons 4

1 kg/ hectare = 0.89 pound / acre Volume I

1 milliliter (ml) = 0.034 fluid ounce

1. liter = 1000 ml = 0.26 gallon Temperature Degrees Celsius (*C) = 5/9 ('F - 32)

Energy 1 erg = 7.38 x 10-8 ft-lb

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I Common and Scientific Names Used in This Report I

At1 antic sherpnose shark Rhi:oprionadon terraenovae Atiantic menhaden Brevoortia tyrannus Anchovy Anchoc sop.

Striped anchovy A. hepsetus Bay anchovy A. mitchill!

Hummichog Fundulus hetcroclitus I

S11versides Atherinidae Atlantic silverside Menidia menidia B1uetish Pomatomus saltatrix Creva11e Jack Caranx hippos Permit Trachinotus falcatus Seatrout Cynoscion spp.

Spotted seatrout C. nebulosus Weakiish C. regalls Spot Leiostomus xanthurus "E

Croaker Micropogonias undulatus Star drum Stellifer lanceolatus i

Striped muilet Mugil cephalus White mullet M. curema Blennies Blennidae Gobies Gobiidae Secrobin Prionotus spp.

F1ounder i

Paralichthys spp.

Tonguefish Symphurus spp.

Blackcheek tonguefish S. tlagiusa l

Planehead ffiefish Monacanthus hispidus White shrimp Penaeus settferus Brown shrimp P. aztecus Pink shr' imp P. duoraruin Hardback shrimp Trachypeneus constrictus Grass shrimp Palaemonetes spp.

I Swimming crab Portunidae Blue crabs Callinectes spp.

E Callinectes sapidus B1ue crab Brfef squid Lolliguncula brevis B

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l EXECUTIVE

SUMMARY

I This report contains the results of biological monitoring conducted during 1987 in the Cape fear Estuary near Carolina Power & Light Company's Brunswick Steam Electric Plant.

Comparisons were made of results from 1987 to previous years with long-term trends discussed.

Data collected during 1987 on the various life stages of fish and shellfish populations in the estuary continued to indicate that population trends and distributions were related to environmental factors, notably fluctuations in freshwater flow.

The river larval fish study indicated that the densities of total larval organisms in Walden Creek and in the river have not changed significantly during the past ten years.

Popula-tions of juvenile organisms in the nursery areas that were dominant in the 1

= g past continued to be dominant in 1987.

The spatial distribution of these 3

organisms was determined by salinity preferences of individual species.

Estuarine salinity was depressed by high freshwater flow during the winter and spring of 1987, resulting in shifts in abundances of some species from the upper estuary to the lower estuary.

Even though freshwater flow was high during the winter and spring of 1987, catches for some species col-lected in the nekton program were highest in areas of the estuary upriver or adjacent to the plant indicating operation of the Brunswick Steam Elec-tric Plant did not limit movement to these areas.

Results also indicated that plant intake modifications remained ef-fective in reducing losses due to impingement and entrainment, lhe diver-sion structure excluded most large organisms from the intake canal causing a reduction in the impingement of large individuals.

The protection of these individuals was important because they had survived life stages with high mortality rates and were the reproducing members of their respective populations.

The number of total organisms impinged was high due to fine-mesh screen installation and higher flows than in recent years.

However, I

survival studies indicated substantial numbers of these impinged organisms were returned to the estuary alive further reducing any impact from the plant.

The number of organisms entrained in 1987 was lower than previous

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years as a result of the use of fine-mesh screens.

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I Data collected in 1987, as in previous years, continued to indicate g

the operation of the Brunswick Steam Electric Plant has not affected the abundance, seasonality, or distribution of organis-- in the estuary.

Environmental factors have been and continue to be 6ne domiiiant force influencing the organisms in the Cape fear Estuary.

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1.0 INTRODUCTION

In January 1981, Carolina Power & Light Company (CP&L) was issued a permit to discharge cooling water from the Brunswick Steam Electric Plant (BSEP) into the Atlantic Ocean under the National Pollutant Dis-charge Elimination System (NPDES).

Water used for cooling is drawn from the Cape Fear River (CFR).

As a stipulation of the NPDES permit, biolog-ical monitoring was conducted to provide sufficient information for a i

continuing assessment of power plant impact on the Cape Fear Estuary (CFE) with particular emphasis on the marine fisheries.

With some modification, this biological monitoring requirement was a continuation of research conducted on the CFE by various investigators since 1976 (CP&L 1985a).

Therefore, several sections in this report include a discussicn of trends from 1976 through 1987, a,g This report compares 1987 data with data f rom previous years (CP&L

,W 1980, 1982, 1983, 1984, 1985 a, 1985 b, 1986, 1987 ).

A summary of the 1987 biological program is presented in Table 1.1.

l Another NPDES permit stipulation was installation of plant intake modifications to reduce entrainment and imp ingen.eni, of estuarine organ-isms.

A permanent fish diversion structure was constructed across the mouth of the intake canal in November 1982 to reduce impingement by preventing large fish and shellfish from entering the canal (Fig-ure 1.1).

Fine-mesh (1-mm) screens were installed on two of the four I

intake traveling screen assemblies on each unit in June 1983 to reduce entrainment.

In t.ddition to these modifications, the NPDES permit also required a reduction in the volume of cooling water used by the plant.

The results of these modifications have been discussed extensively in other CP&L reports (Hogarth and Nichols 1981; CP&L 1985b) and were taken into consideraticn during the NPDES permit renewal in 1987.

I The North Carolina Division of Environmental Management renewed the plant's NPDES oermit in April 1987.

Previous stipulations were maintained in the new permit with regard to biological monitoring and to the fish diversion structure.

However, one significant change required a third I

1-1

I fine-mesh screen on each unit, thereby causing intake cooling water to continuously flow through fine-mesh screening.

Associated with this change was an increase in the permitted maximum allowable flow.

From December through March, an increase to 922 cubic feet per second (cfs)

(26.1 cubic meters per second (cmsj) per unit is allowed, while during the B

period from April through November, 1105 cf s (31.1 cms) per unit is B

allowed.

During July, August, and September, the flow of one unit may be increased to 1230 cfs (34.8 cms) resulting in use of a fourth intake pump without fine-mesh screens.

The periods for which data are reported vary by program.

The entrainment and river larval fish programs data were collected from September 1986 through August 1987 to correspond to periods of larval recruitment.

The marsh, nekton, survival, and impingement programs data g

were collected from January through December 1987, while the water quality P.

program data were collected from September 1986 through December 1987.

l This report divides the biological monitoring program into two sec-l tions.

The first section presents results from programs that address questions : elating to the fisheries populations of the CFE as well as associated water quality variables.

The second section provides results from plant-related programs involving entrainment, impingement, survival, and an intake canal gill net study.

55 Sampling locations for the monitoring programs are shown in Fig-ure 1.2.

Because several stations were sampled in each creek in the marsh program, the entire creek is designated as a sampling area.

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I Table 1.1 The 1987 Brunswick Steam Electric Plant biological monitoring program swanary.

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Program Frequency __

Locations Water quality Once per week 11, 15, 19, 24, 25, 29, I

35, 38, 42 River larval fish Twice per calendar 11, 18, 24, 25, 34, 37 month 41 I

Marsh Seine Ofce every three waeks 12., 16, 22, 25, 31, 32 Trawl Once every three weeks 11, 15, 17, 21, e4, 27, i

28, 31, 32, 42, 43, 51 Nekton g

5 Trawl Once every three weeks 1, 2, 4-8, 10-12, 16 Gill net Once every four weeks 4,5,6 Entrainment four times per calendar Discharge weir month Survival studies As needed Fish return fiume and intake canal I

Impingement Juvenile and adult Twice per calendar Fish return flume month Larval four times per calendar Fish return flume month I

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Figure 1.2 Brunswick Steam Electric Plant biological monitoring program sampling locations for 1987.

1-5

t 2.0 CAPE FEAR ESTUARY POPULATION MONITORING l'

2.1 Introduction It has been estimated that as much as 93% of the East Coast's com-mercial_ fish, shellfish, and sport fish spend at least a portion of their I

lives in estuarles (McHugh 1967).

Because of the importance of estuaries in the life histories of these fishes, the fisheries population of the CFE was examined us t og several monitoring programs in 1987 to determine if operation of the BSEP had an adverse effect on these populations.

The river larval fish program was designed to document immigration of larvae to the estuary, the rrsrsh program documented successful recruitment of postlarvae to nursery areas, and the nekton program documented changes in populations of late juveniles in the CFE.

The associated hydrographic variables that tend to control many of these movements were regularly monitored in the water quality program.

These estuarine monitoring programs specifically exauined:

1.

Freshwater flow, temperature, and salinity fluctuations.

2.

Species composition.

3.

3easonal distributions.

4.

Spatial distributions, f

5.

Relative yearly abundances.

6.

Long-term trends in populations.

Data from 1987 were compared with data from previous years to quan-tify any significant changes in the numbers of organisms utilizing the CFE I

that were susceptible to " cropping" by operation of the BSEP.

Population i

trends in Walden Creek were of particular interest because of its proxim-ity to the intake canal.

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2.2 Methods 2.P.1 Sample Collection Nine water quality stations have veen sampled weekly since 1982.

I Surface and bottom temperatures ard salinities were mea;ured in degrees Celsius ('C) and in parts per thousand (ppt), respectively.

i Simultaneous replicate larval fish samples were collected at night from the surface and bottom at each of seven stations (Figure 1.2).

One of the two replicate surface and bottom samples from each station was g

processed (CP&L 1987).

A 1-n diameter, 505-um mash net and a flowmeter were attached to each of four rectangular frames (Hodson et al. 1981).

Five stations were located in the CFR channel and one eacn in Dutchman and g

Walden Creeks.

These stations and gears have not changed since 1981 (CP&L p

1982).

I The sampling gears (trawl and seine), sampling metheds, and labora-tory procedures for the marsh program were identical to those used in previce years (CP&L 1982, 1983, 1984, 1985 a, 1986, 1987 ).

Sampling loca-tions were identical to those of 1986 (Figure 1.2; CPLL 1987).

Discussior.s of seasonal and spatial distributions and trends are based on data gathered by the gea, considered the most effective for each species, g

B A 6.4-m semiballoon otter trawl was used in the nekton ragram to sample eleven stations extending from the freshwater drainage canal west of Southport to Alligator Creek near Wilmington (Figure 1.2).

Detailed descriptions of sampling stations and methodologies are in CP&L (1984).

The salinity regime of the estuary is divided into different zones and is typified by the creek systems sampled.

The lower most creek system is Baldhead Creek located in the polyhaline (high-salinity) zone of the estuary adjacuat to the mouth of the CFR (Figure 1.2).

Walden Creek is located in the lower meschaline (medium-salinity) zone of the estuary near the BSEP intake canal.

Mott's Bay is an oligchaline (low-salinity) to meschaline (medium-salinity) area well upriver from the BSEP.

Alligator I

2-2

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Creek is the upper most creek system studied and is located in the head of the estuary where the salinity is usually fresh to oligohaline.

I 2.2.2 Data Analysis I

Bottom salinity and temperature values were plotted for stations characteristic of the various salinity regimes in the CFR channel and I.

creek systen.s.

The downriver station (Hg 15) was located near the mouth of the river, the midriver station (Hg 25) was in the vicinity of Sunny Point, and the upriver station (Hg 38) was approximately 17 kilometers north of the plant.

One station from tne middle of Baldhead, Walden, and l

Alligator Creeks was plotted for comparison (Figure 1.2).

Biological data were collected and evaluated by several criteria:

sample, space, and time.

The data were summeo over one or more of these criteria and a mean calculated to represent the distribution of values.

I Since the distribution of numbers at any level tends to be skewed toward the lower range of values, the loge (X + 1) transferrration of the indi-vidual sample was uscd to help normalize the data.

This procedure was applied to all data before time-series analysis was performed.

The year-l 1evel terms in the time-series model serve as indications of yearly abun-dance af ter adjusting for environmental effects which impose selective periodicities on the distribution of organisms.

Statistical testing for the presence or absence of significant periodicity within and among years I.

provided an evaluation of model fit and a testable means for biological or environmental interpretation.

Time-series analysis was performed on larval fish, marsh, and nekton data.

Significance of the upward or down-ward trends was determined at-the P ; 0.05 level.

Further' description of the time-series model development was presented in CP&L (1985a).

!I For analysis purposes, a larval fish year began in September and l

continued through the following August.

Data were analyzed for 1977 I

through 1987 for those stations. that continued to be sampled during this period.

The data consisted of 12 observations each year where each obser-I vation was the mean of the transformed density (logg [ density + 1]) of the I

surface and bottom samples analyzed each month.

Densities of larval

,I l

I

I organisms were computed by multiplying the number of collected organisms by 1000 and then dividing by the volume of water filtered-Spatial differences in larval den]ities were determined by comparing data from - Station 11 (Dutchman Creek) to Station 24 (Walden Creek).

Dutchman Creek is downriver and away from the direct influence of the plant.

Walden Creek is located just upriver and is bisected by the intake canal (Figure 1.2).

Because of its close proximity to the intake canal, the Walden Creet Station was the most likely to be affected by plant operation, while the Dutchman Creek Station was used as a control area.

Comparisons were also made tetween lower and upper estuary densities.

This was done by averaging the data from Stations 18 + 25 + 37 in the lower river and comparing taem to the average of Stations 34 + 41 in the upper river.

Time-series analysis was performed on marsh and nekton data collected in each program from 1981 through 1987. Data were also analyzed from 1979 through 1987 for the lower river stations of the nekton program. The data consisted of 17 observations each year where each of the observations was the mean of the transformed catch-per-unit-effort (logg (CPUE + ll) of all the samples collected in each study area during each trip.

Occasionally the time-series analysis could not be used due to no catches of a partic-ular species in some years or when significant periodicities were present 3

E which may have affected the outcome of statistical analysis.

In these situations., the mean log, (CPUE + 1) was used to compare populations. The E

asterisk on these plots indicates the mean, while the box and bar E

represent one standard deviation and the range, respectively.

Spatial differences were determined by comparing mean CPUE between the different creeks or areas sampled.

Recruitment periods of organisms to the marshes were determined by examining the CPUE and length-frequency distributions of each species by creek.

Shrimp below 20 mm and blue crabs below 10 mm were identified to genus and family, respectively, due to difficulties in accurately identi-g fying organisms of this size to lower taxonomic levels.

E I

2-4 l

l The nekten program analyzed selected species by either young-of-year (YOY) or Juvenile / Adult (J/A) size classes determined by examining the length-frequency distributions of the species (Lagler 1952; Everhart and Youngs 1981; Ambrose 1983).

No classifications (YOY or J/A) were made for bay anchovy, blue crabs, and shrimp, 2.3 Results and Discussion 2.3.1 Water Quality Salinity in the CFE typically exhibits a decline during the winter months and an increase from early spring through late summer.

This trend is a result of high freshwater flow during the winter and a reduction of that flow during the summer.

Short-term decreases in salinity are ob-served during the late summer and early fall, typically a period of high salinity.

These decreases are the result of tropical disturbances (resulting in increased rainfall) passing over the Cape fear watershed i

during this time of year.

However, these disturbances are normally short g

5 in duration and salinity quickly increases to previous levels.

4 A decline in salinity was observed in November 1986 (Figure 2.1).

This decline continued through the spring before salinity began to rise as a result of decreasing freshwater flow (Figure 2.2).

A slight decrease in salinity was observed in September 1987, probably as a result of local rainfall because the effect on the shallow creek stations was more pronounced than that on the river stations.

Theie was a decrease in freshwater flow from 1984 through 1986; how-ever, during 1987 a substantial increase occurred during the winter and spritig effectively depressing the salinities during that period.

Flows decreased during the summer and fall allowing salinities to return to high levels expected for that time of year.

The CFE exhibited typicci seasonal variations in temperature during the -year (Figure - 2.3).

A maximum bottom temperature of 31.5'C was ob-tained in Baldhead Creek during July and a minimum bottom temperature of I-4.0*C was noted in January at Station 29 in the river channel.

2-5 l-

I 2.3.2 Dominant Species Six taxa of fish (Anchoa spp.,

croaker, weakfish, Bienniidae, Gobiosoma spp., and Goblonellus spp.), one genus of shrirrp (Penaeus spp.),

and one family of crab (Portunidae) 6ccounted for 96% of the larvae col-1ected from the CFE in 1987 (Table 2.1).

The overall density of organisms was the second highest in the past six years but was down from densities reported for 1986 due primarily to lower anchovy densities.

I The most abundant taxa in 1987 aere similar to those of the previous five years (Table 2.1).

Bay and striped anchovy (Anchoa spp.) densities g

decreased but still accounted for about 51% of all larvae collected in 1987.

Croaker, spot, and shrimp densities increased in 1987 from 1986 and accounted for about 23% of all larvae collected.

Portunid crab megaloos (primarily blue crab) accounted for about 8%

of the total larval density in 1987.

The annual mean density of 3

170/1000m was a substantial increase from 1986 (Table 2.1).

Fluctuations of over 50% annually are common in catches of blue crab and can result from variable temperature and salinity patterns during recruitment (Leming l

andJohnson1985).

a Postlarval penaeid shrimp (brown, pink, and white) represented about 5

5% of the total larval density in 1987.

Festlarval shrimp densities were the highest recorded in the past six years due to high densities during late summer and f all.

Brown shrimp postlarvae usually enter the estuary from February through May, followed by pink and white shrimp from May through October (Copeland et al. 1979).

Therefore, the high densities were due mostly to rccruitment of pink and white shrimp.

Ten species comprised 95.5% of the total marsh trawl catch (Table 2.2).

Spot was the numerically dominant organism collected, repre-senting 52.1% of the total catch.

Grass shrimp, croaker, and Atlantic g

menhaden comprised about 25%, while the remaining 70 species made up 22.4%

3 of the trawl catch.

With the exception of murraichog, the ten most I

2-6 5_

I abundant species collected in 1987 were the same as those collected in 1986 (CP&L 1987).

Hodson (1979); Huish and Geaghan (1979); Weinstein (1979); and CP&L (1983,1984,1985a) also reported that catches in the CFE in past years were dominated by these species.

I Ten species comprised 96.4%

of the total marsh seine catch I

(Table 2.2).

As in previous years, grass shrimp were numerically dominant making up 42.8% of the total catch, wnile spot, Atlantic menhaden, and mummichog comprised another 44.6%.

The remaining 61 species ccmprised I

12.6% of the total seine catch.

The ten dominant species in 1987 were the same as in 1986 (CP&L 1987) and were similar to those collected in orevious studies by Weinstein (1979) and CP&L (1983, 1984, 1985a).

Bay anchovy, croaker, spot, and white shrin;p comprised 92.3% of the total 1987 nekten catch (Table 2.3).

These species have been among the dominant nekten species collected in the CFE since the late 1970s (Birkhead et al.1979; Schwartz et al.1979; Huish and Geaghan 1979; CP&L

g 1987).

Another 79 taxa accounted for the remaining 7.8% of the total.

,5 Notable increases in CPUE from 1986 occurred for bay anchovy, croaker, spot, and star drum (CP&L 1987).

A threefold decrease in the CPUE of brown shrimp occurred from 1986 (CP&L 1987).

This decrease may have been related to the high freshwater flow from February through April when post-l larval brown shrimp were migrating into the CFE (Figure 2.2).

2.3.3 Seasonal Distribution The seasonal I

distribution of many estuarine species is associated with recruitment of the individual species.

Increases in number and decreases in mean size are related to the recruitment of most species.

Generally, after recruitment ceases, an increase in mean size and a decrease in number occurs.

During the several month residence and growth l

period, most species decline in number due to emigration and natural mor-tality.

The seasonal and size distributions of selected species collected in 1987 followed these patterns.

1I 2-7

I Seasonal trends of selected species of larvac in the CFE during the l

past ten years at each station group were identified.

The seasonal occur-rences of selected larval organisms were:

Spot December through May Croaker October through April Portunid megalops August through December Flounder December through March Striped mullet December through March Atlantic menhaden February through May Penaeid postlarval shrimp

- brown February through May

- pink and white May through October Anchovy April through October Weakfish May through October Gobiosoma spp.

May through October I

Abundance of newly recruited Atlantic menhaden, spot, striped mullet, and flounder in the marshes peaked in the late winter and early spring.

The 1987 recruitment of croaker to the marshes began in the fall of 1986 and peaked the following spring.

Blue crab megalops recruitment to the estuary was during the f all of 1986 and 1987.

Young-of-year blue crab increased in numbers during the spring and fall of 1987 following the respective megalopal recruitments.

Brown shrimp and mummichog YOY peaked in the spring, while the abundance of YOY white mullet, bay anchovy, g

Atiantic silverside, pink shrimp, and white shrimp reached their maximum W

numbers in the summar and early fall.

These periods of maximum abundance were. similar to those observed by other investigators in previous years and concurs with the 1987 larval fish data (Weinstein et al. 1980; Kneib 1984; CP&L 1984, 1985a, 1987).

f The seasonal-distributions of selected organisms collected by the nekton trawl were similar to those reported in previous years (Schwartz et al. 1979 CP&L 1987).

The periods of abundance for the selected species g

and size classes were as follows:

E I

2-8 h

I Bay anchovy May, June, and October Blue crab March through May and September, J

October Croaker

- young-of-year february through July and October, November I

- Juvenile / Adult March through July Spot

- young-of-year March through July and December

- Juvenile / Adult January through June Atlantic menhaden

- Juveni'ie/ Adult January theough April Brown shrimp May through August Weakfish June through October White shrimp August through December Pink shrimp August through December 2.3.4 Spatial Distribution

.I The distribution of most estuarine species is dependent upon trany variables inherent to estuaries.

Among these variables are temperature-(Joseph 1973), turbidity (Blaber and 81aber 1980; Miller et al. 1984),

food availability _ (Lasker 1975),

predation (Weinstein et al.

1980; Weinstein and Walters 1981), salinity (Cunter 1961), and freshwater flow (Rogers et al.1984).

Of these variables, salinity and freshwater - flow are probably the most important in determining the utilization of a par-ticular area in the CFE by migrating organisms.

I The 1987 year-level terms of the larval recruitment densities from Dutchman Creek. Walden Creek, the lower river, and upper river stations were compared to determine spatial distribution of larvae in the estu-ary.

Densities of most larval species were greater in the creeks than in the river channel.

For total density in 1987, the year-level term for Dutchman Creek was 6.95 and for Walden Creek was 6.94.

The year-level term was 6.55 for the lower river stations and 6.29 for the upper river stations.

I 2-9

I The species-areas association was similar to what was reported using a principle. component analysis in 1984 (CP&L 1985a).

Densities of Atlantic menhaden and croaker larvae were high in the upper river areat, while other species were found in the high-salinity areas downriver.

The occurrence of high densities ef croaker and Atlantic menhaden upriver indicates that these ocean-spawned species were able to enter the estuary, move past the intake area, and establish residence above the influence of the BSEP.

Catch-per-unit-effort data by creek from the marsh program were used to determine the cres ( system that supported the greatest abundance of g

each selected f 6e'ies in 1987 (Table 2.4).

Baldhead Creek is usually a polyhaline system whic would support large populations of species such as Atlantic silverside, hite mullet, and pink shrimp (Winstein 197E).

Atlantic silverside and white mullet were most abundant in Baldhead Creek; however, pink shrimp were most numerous in the upper estuary.

The large number of pink shrimp in the upper estuary may have resulted from unusually high salinities (low freshwater flow) in this area which made availabic more estuarine nroa in the suitable salinity range during the late summer and early fall recruitment (Figure 2.2; Deegan and Day 1984).

Walden Creek supported larger numbers of mummichog, spot, striped mullet, brown shrimp, white shrimp, and blue crab than the other natural 5

creek systems.

These species are typically associated with oligohaline E

and meschaline water which occurred in Walden Creek during their respec-tive recruitment periods in 1987 (Weinstein 1979).

Mott's Bay is generally oligohaline to meschaline, depending upon the magnitude of freshwater flow.

Atlantic menhaden, bay anchovy, and pink shrimp populations were largest in Mott's Bay.

Juvenile Atlantic menFaden and bay anchovy are usually more abundant in the oligchaline ano meschaline zones of the estuary (Jones et al. 1978).

Large populations of pink shrimp in this part of the estuarine system are unusual (Weinstein 1979).

These large numbers in Mott's Bay were probably the result of high salinities during the late summer and early f all expanding suitable habi-tat.

In the summer and fall of 1987 low freshwater flow during the I

2-10

I recruitment of pink shrimp increased the upstream movement of saline water, effectively increasing the salinity regime in the middle tc uoper estuary.

Similar results were reported in 1985 and 1986 when freshwater flow was also low (CP&L 1986,1987).

I Alligator Creek is situated in the head of the estuary and is usually i

fresh to oligohaline.

Croaker and southern flounder, usually found in I_

areas of low salinity, were most abundant in Alligater Creek.

The return basin, located at the head of a tidal creek, was populated with estuarine organisms by natural immigration to the estuary and by the BSEP fish return system.

As in 1986, the CPUE of brown shrimp and blue crab were higher in the return basin than in any natural creek system (CP&L 1987).

Comparisons between the retern basin and individual stations in Walden Creek indicated population abundances ar.d seasonal distributions of most I

species were similar to tnose of the middle and upstream sla-tions.

These results indicate the return basin was still being utilized by transient organisms in the same manner as other upstream nursery habi-I tats and are similar to those obtained i t. previous years (CP&L 1984, 1985a,1986,1987).

Five of the commercially important or dominant species collected by the nekton trawl were most abundant in the lower river (Table 2.5).

As in previous years, the largest population of bay anchovy occurred at Sta-tion 1 (CP&L 1987).

Both size classes of spot and blue crab were most abundant at Station 4.

Brown shrimp md pink shrimp were collected in large numbers at Station 7.

Atlantic menhaden, weakfish, and both size I

classes of croaker were most abundant at Snow's Cut.

More white shrimp were caught at Alligator Creek than at any other station.

These distributions are natural and are probably a result of fresh-water flow.

The segregation vf different species along a downriver to upriver gradient was similar to that occurring during 1984 when freshwater flow conditions during winter and spring were high (Figure 2.2; CP&L 1985a, 1985b).

This segregation is similar to what other researchers have reported (Merriner 1973; Schwartz et al. 1979, Weinstein et al. 1980).

In I

L-11 l

I addi' ion, all of the selected species were most abundant at deep creek or l

channel stations, consistent with results from previous years.

Individuals collected in the upper river and Alligator Creek were smaller than those collected in the lower river and Snow's Cut (Table 2.6).

This relationship was previously reportad by others (Gunter 1961; Milgarese et al. 1982).

This indicated that larvae are able to migrate past the BSEP intake canal and use upriver nursery areas.

Larger white shrimp were collected in the upper river sinca this species is asso-ciated with lower salinities.

2.3.3 Time-Series Analysi:

River Larval Fish Studies of fish eggs and larval transport from the ocean to estuaries g

were reviewed by Norcross and Shaw (1984).

They concluded that some of g

the factors causing fluctuations in the mean density between years are spawning success, transport mechanisms (wind and water current), and water temperature and salinity.

Fluctuations in the mean density of larvae among years is a natural and expected occurrence.

Therefore, long-term trends are more useful in population evaluations than year-to-year compar-isons.

Time-series analysis was used to evaluate whether the annual abun-3

-dance of a particular species increased or decreased significantly over I

time.

The'R2 value indicates how well the model explains the variability in the data.

The results of the time-series analysis show that the density of total larval organisms in Walden Creek, the lower river, and the upper river stations have not changed significantly during the past ten years.

These are the areas closest to or upstream of the influence of the BSEP intake canal.

During the same time period, the total density of organisms in Dutchman Creek, an area below the influence of the plant, has declined significantly (Table 2.7).

This decline in densities in Dutchman Creek is attributable primarily to declines in Cabiosoma spp, and

c. pot densities.

It should be noted that the year-level term for both species were up in 1987:

2-12 5_

I I

Dutchman Creek Year-level Terms I

79 80 81 82 83 84 85 86 87 Spot 1.87 1.87 1.52 2.02 2.01 1.93 1.46 1.22 1.56 Gobiosoma spp.

3.29 2.64 3.40 2.59 2.45 2.68 2.28 2.73 2.91 I

Time-series plots of total organism d 2ty in Dutchman and Walden Creeks (Figure 2.4) show that the seasonal occurrence of species was very similar in both creeks from 1979 through 1987 Time-series analysis end plots for spot and Atlantic menhaden (figures 2.5 and 2.6) show the same pattern.

Even though the seasonal occurrence of larval species has been very consistent, there have been fluctuations in the densities from year to year.

Significant increases in the densities of larval croaker, Gob!osoma spp.,

mullet, and shrimp have occurred in Walden Creek (Table 2.7).

Anchovy, Gcblosoma spp., and shrimp have also increased I

significantly in the lower 2nd upper river stations.

These trends probahly reflect natural occurrences and distributions of-larval organisus in the CFE.

The effects of spawning, ocean currents, predation, freshwater f W, and many oW.r factors affect the success of a spe:ies to produce sufficient offspring for future populations.

The data inticate that the operation of the BSEP is not having a significant effect or these factors.

I Marsh Alligator Creek 4 decrease in 1987 catch of spot and croaker probably occurred L

because of high freshwater flow during their winter and spring recruitment (Table 2.4).

The abundance of postlarval and juvenile spot and croaker increased significantly from 1981 through 1987 (Table 2.8).

This trend may be attributed to the large number of spot and croaker caught in 1985 and 1986 when relatively low freshwater flow during recruitment allowed l

l salinities in the upper estuary to increase to levels preferred by these l

2-13 I

species (Figure 2.2).

Although the abundances. of Atlantic menhaden and flounder varied from 1981 through 1987, the trend showed no significant change over the entire period. The abundances of blue crab have decreased over the study period regardless of increases which occurred in 1985 and

^

1986 (Figure 2.7).

This decrease is reflected in a reduction in commer-cial yields experienced in the CFE (Katy West, pers comm., N.C. Division of Marine Fisheries).

The recruitment of blue crab megalops, however, has rema N d the same or has increased throughout the estuary (Table 2.7) indic6 ting that megalops do migrate past the BSEP to the upper ettuary and that some other f actors are limiting the juvenile blue crab population sizes.

T1me-series analysis could not be performed on brown, pink, and white shrimp data because none were collected in Alligator Creek during 1984.

However, there were large numbers of brown shrimp in 1985 and 1986 when freshwater flow during the spring recruitment was low (Figure 2.8).

g The population decreased in 1987 as frethwater flows increased during E

recruitment.

White shrimp were most abundant in 1986 and 1987 indicating successful recruitment to the upper estuary (Figure 2.9).

As expected, the abundance of pink shrimp remained small since this species usually inhabits more saline areas (Weinstein 1979).

Mott's Bay Fluctuations in population sizes of the selected species were evident 3

in Mott's Pay during the study. The fluctuations in abundance of Atlantic E

menhaden, spot, croaker, striped mullet, flounder, brown shrimp, and pink shrimp in Mott's Bay were usually caused by changes in freshwater flow and salinity during their respective recruitment periods.

However, these changes in flow and salinity conditions have not resulted in any signifi-cant tre.nds since 1981 (Table 2.8).

White mullet and blue crab decreased in abundance during the study period.

White mullet usually inhabit areas higher in salinity than Mott's Bay.

However, upper meschaline and polyhaline conditions occurred in Mott's Bay during the summer recruitment period of white mullet in 1981 and 1985 resulting in high catches.

Pela-tively low catches during the remaining years, hov ver, probably produced the decreasing trend (Figure 2.10).

The abundance of juvenile blue crab was relatively stable from 1994 through 1986 but declined sharply in 1987 (Figure 2.11).

2-14 I

Walden Creek I

Flounder, brown shrimp, and white shrimp populations in Walden Creek have increased significantly since 1921 (Table 2.8).

White shrimp abun-dances in Walden Creek have increased over the past two years (up from a seven-ye e low in 1985) (Figure 2.12).

Although the number of brown I

shrimp decreased in 4987, the decrease was not enough to prevent an over-all increasing trend.

The high freshwater flows during the winter and spring recruitment of flounder in 1983,1984, and 1987 caused lower salin-ities and therefore extended suitable habitat to the lower portions of the l

estuary allowing flounder to utilize Walden Creek as a nursery during these years.

The population trends of spot, croaker, striped mullet, white mullet, and pink shrimp have not changed significantly over the study period.

Atlantic menhaden and Dlue crab populatiens had significant reductions during the study (Figures 2.13 and 2.14).

Although the I

Atlantic menhaden population was larger in 1987 than in the previous three years, a seven-year decreasing trend occurred.

The decrease of postlarvae and juveniles in the marsh was probably due to decreased larval recruit-ment to the estuary (Table 2.7).

The decreased recruitment of larvae may have been due to many factors as discussed by Norcross and Shaw (1984).

Blue crab popu.ations have decreased in numbers since 1983, even through megalops recruitment has remained constant or has increased.

This indi-cates that some other variables are limiting the population size of juve-nile blue crab.

Baldhead Creek Spot, croaker, and striped mullet data showed increasing trends in abundance during the study period (Table 2.8), perhaps as a result of high freshwater flows.during the winter and spring recruitment periods in 1983, 1984, and 1987 which decreased available habitat for these species up-river.

White shrimp exhibited a significant increase in abundance during I

1987, although freshwater flows during the late summer and early fall recruitment periods were not unusually high.

These increased populations were apparently not associated with high freshwater flows but other I

2-15 I

I factors--such as spawning success, wind direction and velocity during migration, and the size of the brood stock--may have been responsible (Norcross and Shaw 1984).

Atlantic menhaden, flounder, pink shrimp, and blue crab abundances did not change significantly.

Time-series analysis could not be performed on brown shrimp and white mullet data from Baldhead Creek due to significant periodicities which may affect the statistical test.

Annual mean loge (CPUE + 1) values indicate the populations of brown shrimp and white mullet were smaller in 1987 than in 1986.

The popillation of white mullet in 1987 was the smallest reported since 1981, while the brown shrimp population appeared to be smaller than in four of the seven study years.

Nekton Significant increases in the abundance of bay anchovy have occurred at all locations in the estuary during the past nine years (Table 2.9).

The steady increase in annual abundance in the lower river was typical of that seen elsewhere (Figure 2.15).

I Annual catches of white shrimp at Snow's Cut also exhibited a sig-nificant increasing trend in abundance (Table 2.9).

A nonsignificant trend in catch occurred over the study period for the lower river sta-tions.

A significant decreasing trend occurred in the upper river. White g

shrimp were not collected in Alligator Creek during 1981, so the time-E ceries analysis could not be performed; however, annual mean loge (CPUE +

1) values suggest that white shrimp have increased at this station (Fig -

ure 2.16).

I Significant decreasing trends in abundance occurred for all other species in all areas during the study period (Table 2.9).

Declines in the commercial landings of croaker have occurred statewide since 1980 (Ross et al. 1987) and decreases in the CFE may be a reflection of these trends.

The abundances of croaker and spot were up in 1987 from 1986 levels in the lower river (Figures 2.17 and 2.18).

I I

ll 2-16

I A decreasir., trend in the abundance of bronn shrimp occurred at Snow's Cut.

The time-series analysis on lower river data could not be performed due to significant periodicities, but the annual mean log g (CPUE + 1) values suggest a decrease in the abunda.ute of bronn shrimp in the icwer river during 1987 (figure 2.19).

The low abundances in 1983, 1984, and 1987 may have been the result of relatively high f reshwater flow adversely affecting postlarval recruitment to the lower river curing I

february through May.

Lcw aburiance in the lower river during 1985 and 1986 tray have been the result of shif ting distributions Es evidenced by high catches at Snow's Cut during 1985 and at Alligator Creek during 1986, both possibly as a result of low freshwater flow (CF&L 1987).

Juvenile / Adult Atlantic menhaden exhibited a decline in abundence in the lower river, Snow's Cut, and the upper river (Table 2.9).

The anal-ysis was not performed fnr catches at Alligator Creek since catches have historically been low at this station.

The decline in abundance did not appear to be related to changes in temperature, salinity, or freshwater flow conditions, These declines may r e. e c t a response to commercial fishing pressure.

Ahrenholz et al. (T,87) suggest Atlantic menhaden has experienced overfishing which has resulted in decreased brood stocks along the entire iast Coast.

Blue crabs have also exhibited a decline since the beginning of the study period (Table 2.9).

Commercial h, "nas of blue crab in the CFE have decreased from 1,667,000 kg in 1982 '. 314,00 kg in 1986, while the I

i number of licensed crab pots in New Hanover and i*unswick Counties have increased through 1985 (Katy West, pers. comm., N.C. Division Marine fis5-I eries).

Although the nekton catch of blue crabs has declined, the density of blue crab megalops have not declined (Table 2.7).

This indicates that other factors are responsible for this decline.

Declines in the abundances of pink shrimp may be a result of changing freshwater flow and salinity patterns.

Pink shrimp abundance remained at low levels in the lower river through 1987 (Table 2.9).

I 2-17 I

I Young-of-year weakfish have exhibited an overall decline throughout the study (Table 2.9).

The seasonal occurrence of YOY weakfish in the CTE corresponds to the opening of the lower river and Snow's Cut to the brown shrimp fishery each year (late June or eat ly Juli).

Herriner (1973) sug-gested the by-catch of juvenile weakfish in the shrimp trawl fishery could have detrimental effects on the abundance of this species, particularly since shrimping in the bays and sounds of North Carolina has increased.

Commercial landings of weakfish from other portions of the state have declined since 1980 (Ross et al.1987).

Trends in the nekton catches for the CFE may also reflect this general trend occurring statewide.

?.4 Summary and.enclusions The species ccmposition and seasonal occurrence of larvae and post-larvae, early juvenile residents, and large nektonic organisms in the Cape fear Estuary have not changed substantially during the past seven years.

Trends in the abundance of larval anchovy, croaker, mullet, weekfish, and postlarval shrimp during the past ten years have increased, while abun-dances of Atlantic menhaden and spot have decreased, possibly reflecting fluctuations in natural occurrences and distribution of larvae in the Cape fear Estuary.

Populations of juvenile organisms, which have historically be'.n dominant in the nurseries of the Cape fear Estuary, remained stable in 1987.

The marsh trawl and seine sampics were dominated by spot and 3

grass shrimp.

E The spatial distribution of the fish and shellfish populations in the Cape fear Estuary were determined by the r.alinity preferences of the indi-vidual species.

These populations were distributed along the downstream l,

to upstream sclinity gradient characteristic of the estuary.

Estuarine salinity was depressed by high freshwater flow in the spring of 1987.

As a result, some species recruited during the spring that are usually abun-dant in the upper estuary became abundant in the lower portions.

Population trends in each creek system also appeared to be associated g

with freshvater flow during their iespective recruitment periods.

Changes B

in population sizes and shif ts from one part of the estuary to another were common as suitable habitats shif ted.

2-18 E

m The return basin supported large numbers of mcny estuarine species.

The relative abundances and seasonal distributions of most selected

~

species in the return basin were sirtlar to those in upper and middle Walder. Creek, indicating the basin was b2ing utilized as a nursery habi-tat.

Consistent with results from previous years, all species collected in I

the nekton program in 1987 were abundant in deep creeks or channel sta-tions.

Catches of white shrimp, Atlantic menhaden, and weakfish were high in areas of the estuary above or adjacant to the plant indicating cpera-tion of the BSEP did not limit movement to these areas.

The decreases in brown shrimp in Alligator Creek during 19a7 was probably the result of high freshwater flow during the brown shrimp recruitment period.

I Adult bay anchovy increased in all areas of the Cape fear Estuary, while white shrimp increased in Snow's Cut.

The abundances of croaker and I

spot were up in the lower river during 1987; however, decreasing trends were still seen over the study period.

Decreasing trends for these species and others, such as weakfish, are reflected in statewide declining trends of these species with some evidence that Atlantic menhaden were overfished in the late 1970s and early 1980s.

Studies hAve shown that some of the factors responsible for year-to-year fluctuations of larvae include spawning success, transport mechanisms (wind and current), and water temperature and salinity, No reductions in I

the abundance of total larvae in Walden Creek or the upper estuarine areas have occurred.

The association between trends in abundance and environmental vari-ables, as well as large nursery populations in the vicinity of and up-stream of the BSEP intake canal, indicates that populations in the Cape l

Fear Estuary are dependent upon natural phenomena and are not being ad-versely impacted by the BSEP.

Populations of nektonic organisms utilizing I

the Cape fear Estuary also appear unaf fected by the BSEP.

Changes that occurred were prcoably due to natural variations in populations and not associated with operation of the BSEP.

2-19

3 Table 2.1 Annual mean density (organisms /1000 m ) and the percentage of the total mean density for the most abundant taxa collected in the river larval fish program from 1982 through 1987 (based on ranking for the 1987 larval year).

1982 1983 1984 1985 1936 1987 Mean Mean hean Mean Mean Mean Taxa density %

density %

density %

density %

density %

density %

Anct.ovy 722 35.8 614 41.6 5?)

47.5 1039 52.9 2196 70.9 1127 51.1 Croaker 479 23.8 367 24.9 210 17.2 255 13.0 174 5.6 352 16.0 Gobiosoma spp.

198 9.8 86 5.8 82 6.8 102 5.2 383 12.4 269 12.2 Portunid megalops 259 12.8 114 7.8 104 8.5 190 9.7 45 1.5 170 7.7 Shrimp postlarvae 54 2.7 75 5.1 63 5.2 88 4.5 66 2.1 109 4.9 y

Spot 123 6.1 71 4.8 63 5.2 99 5.0 37 1.2 50 2.3

'd 81enniidae 8

0.4 9

0.6 7

0.6 19 1.0 25 0.8 17 0.8 Microgobius spp.

5 0.2 5

0.4 7

0.6 6

0.3 23 0.7 12 0.6 Cobionellus spp.

6 0.3 1

0.1 10 0.8 9

0.4 4

0.1 10 0.4 Weakfish 15 0.7 9

0.6 4

0.4 13 0.7 30 1.0 9

0.4 Other taxa 149 7.4 122 8.3 68 7.2 143 7.3 115 3.7 79 3.6 Total organisms 2018 100.0 1473 100.0 1216 100.0 1963 100.0 3098 100.0 2204 100.0 g

g 3

m m

33 M

M M

M M

M M

M M

M

I I

Table 2.2 Total catch and percent total of the ten most abundant species collected in the marsh study during 1987.

Trawl Seine Species Catch 5

Species Catch Spot 47,919 52.1 Grass shrimp 33,941 42.8 Grass shrimp 12,637 13.7 Spot 22,536 28.4 Croaker 5.540 6.0 Attantic menhaden 8,640 10.9 I

Atlantic menhaden 5,337 5.8 Mummichog 4,184 5.3 White shrimp 4,937 5.4 White shrir.p 1,862 2.3

- g m

Bay anchovy 4,933 5.4 Bay anchovy 1,731 2.2 Brown shrimp 2,529 2.8 Striped mullet 1,342 1.7 Southern flouncer 1,842 2.0 White mullet 814 1.0 Blue crab 1,193 1.3 4tlantic silverside 777 1.0 Mumichog 968 1.0 Brown shrimp 610 0.8 Other species 4.116 4.5 Other species 2.840 3.6 I

Total 91,951 100.0 Total 79,277 100.0 Number of efforts 204 102 I

I I

I I

4 I

2-21 I

I Table 2.3 Total number, percent total number, and annual catch-per-unit-E' effort (CPUE) of the ten most abundant species collected in the a

nekton study during 1987.

I Percent Total of Species number total QUE Bay anchovy 44,268 56.8 236.7 Crcaker 14.420 18.4 77.1 Spot 11.550 14.8 61.8 g

White shrimp 1,809 2.3 9.C u

Brief squid 784 1.0 4.2 l

Star drum 757 1.0 4.0 Grass shrimp 749 1.0 4.0 Brown :hrimp 746 1.0 4.0 Atlantic menhaden 522 0.7 2.8 Spotted hake 313 0.4 1.7 Subtotal 75,918 97.3 405.9 Other organisms 2,078 2.7 11.1 I

Total all organisms 77,996 100.0 417.0 5

E I

l I

I I

I I

I 2-22

.I_

I Table 2.4 Annual catch-per-unit-effort (CPUE) by creek system for 13 selected species in the marsh study during 1987.

I-Baldhead Walden Mott's A111gagor Return I

Creek Basini Species Creek Creek Bay Atlantic trenhaden 1

28 83 14 4

I Bay anchovy 10 8

63 44 16 Mumichcg 13 109

<1 Atlantic silverside 20 1

2 Spot 123 424 221 39 232 l

Croaker 2

5 45 97 15 Striped mullet 15 18 7

White mullet 14 7

3 Southern flounder

<1 4

4 36 12 Brown shrimp 5

24 3

<1 30 I

Pink shrimp 2

2 7

<1 4

White shrimp 5

50 1

36 4

Blue crab 4

6 2

5 17 I

TSeine samp'es were not collected in Alligator Creek or the return basin.

I I

I I

I I

2-23

t Table 2.5 Annual catch-per-unit-effort (CPUE) by station of selected organisms collected in the nekton study during 1987.

Station Lower

-Snow's Upper Alligator river Cut river Creek Species 1

2 4

7 8

10 11 16 12 Bay anchovy 612.1 47.3 285.3 108.8 85.2 114.2 186.2 48.5 10.9 Croaker YOY 22.5 34.5 141.0 5.4 0.1 156.6' 44.6 9.1 57.8 J/A 0.3 0.3 2.0 0.1 0.1 2.5 0.0 0.0 0.0 Spot YOY 10.8 6.6 94.6 29.9 4.4 33.9 20.9 2.0 6.7 J/A 0.9 4.2 87.9 0.3 0.1 11.1 0.2 0.1 0.0 White shrimp 11.8 0.1 8.7 1.1 0.2 3.4 3.8 0.4 38.3 Brown shrimp 2.7 0.0 2.4 6.7 0.6 2.2 0.5 0.2 0.9 Atlantic mer.haden J/A 0.2 0.1 6.2 0.9 0.0 9.2 0.4 0.0 0.0 Blue crab 0.4 0.6 3.6 1.2 0.3 1.4 0.9 0.4 1.7 Pink shrimp 0.7 0.1 1.4 8.3 0.5 2.5 0.1 0.0 0.4 Weakfish YOY 0.3 0.0 0.2 0.1 0.2 2.4 0.0 0.0 0.0 YOY = Young-of-year J/A = Juvenile / adult M

M M

M M

M M

M M

M M

M M

M M

M M

I Table 2.6 Hean standard length (m) by location of selected species col-1ected in the nekton study during 1987.

I Species Lo=er river Snow's Cut Upper river Alligator Creek Bay anchovy 43 46 33 37 Croaker 57 65 27 29 l

Spot 71 75 33 46 White shrimp 91 100 104 52 Brown shrimp

.80 08 65 44 Atlantic menhaden 94 93 50 43 Blue crab 69 68 57 44 I

Pink shrimp 57 66 38 39 I

Lower river

= Stations 1, 2. 4, 7, and 8 combined Snow's Cut

= Station 10 Upper river

= Stations 11 and 16 combined g

Alligator Creek = Station 12 I

I I

I

I 2-25 l

Table 2.7 Results of time-series analysis of river larval fish data by station group indicating trends in density from September 1977 through August 1987.

Station groups Dutchman Creek Walden Creek Lower river Upper river 11 24 18 + 25 + 37 34 + 41 2

2 2

2 Taxon

+/-

R

+/-

R

+/-

R

+/-

R Anchovy NS 0.98 NS 0.99

+***

0.99

+***

0.98 Croaker

+**

0.97

+***

0.98 NS 0.99 NS 0.97 Gobiosoma spp.

0.98

+***

0.98

+***

0.99

+***

0.97 Atlantic menhaden 0.93 NS 0.97 0.95 0.94 Mullet NS 0.94

+***

0.95 0.89 NS 0.87 eg Weakfish NS 0.97 NS 0.98 NS 0.95

+**

0.97 Spot 0.99 0.99 0.99 NS 0.98 Penaeus spp.

+***

0.98

+**

0.98

+***

0.96

+***

0.96 Portunid megalops NS 0.98 NS 0.98

+**

0.98 NS 0.97 Total organisms 0.98 NS 0.96 NS 0.98 NS 0.06 NS P > 0.05 0.01 < P $ 0.05 0.001 < P $ 0.01 P $ 0.601 Increasing trend

+

Decreasing trend Z

R Amount of variation explained by the time-series model l

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4

Table 2.9 Results of time-series analysis of nekta data by station group indicating trends in abundance of selected species from 1979 through 1987.

Station Groups Lower RiverI Snow's Cuts Upper Rivers I

Alligator 1+4+7+8 10 11 12 2

2 2

2 Species

+/-

R

+/-

R

+/

R

+/-

R Bay anchovy 0.79

+**

0.71

+**

0. 7' 4***

0.77 Croaker YOY 0.92 0.80 0.85 0.82 J/A 0.91 0.84 ID ID Spot YOY O.84 0.74 0.81 0.85 o

'h J/A 0.88 0.86 0.86 ID White shrimp NS 0.85

++

0.77 0.74 ID Brown shrimp ID 0.71 ID ID Atlantic menhaden J/A 0.87 0.80 0.67 ID Blue crabs 0.83 0.76 0.81 0.84 Pink shrimp 0.86 0.78 0.77 ID Weakfish YOY ID 0.78 ID ID NS P > 0.05 ID insufficient data for analysis or poor model fit 0.01 < P< 0.05 YOY Young-of-Year 0.001 < P < 0.01 JfA Juvenile / Adult

• • • P < 0.001 R

A=ount of variation explained by the time-series model Increasing trend Results encompass the years 1979 through 1986

+

i Decreasing trend 1

Results encompass the years 1981 through 1986 IM M

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Figure 2.3 Dottom temperature for selected stations in the Cape Fear Estuar*v from September 1986 through December 1987, I

g

2. x

I u:

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Dutchman Creek (A significant decreasing trend) l Figure 2.4 Results of time series analysis of totallarval organisms collected in Dutchman Creek and Walden Creek from 1979 through 1987.

I 2-32

.. -. - ~. - -. -.

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L.ower River Area (A significant decreasing trend)

Figure 2.5 Results of time series analysis oflarval spot collected in the lower and upper areas of the Cape Fear Estuary from 1977 through 1987.

I l

2 33

. _.. _. _ _ _ ~ _ - _ _.. -. _. _ _.. _ _ _. _ _ _ _

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SC E1 92 23 94 55 86 57 is ece I.

Lower Piver Area (A significant decreasing trend)

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Walden Creek (No significant trend) l Figure 2.6 Results of time series analysis oflarval Atlantic menhaden colluted in the i

lower area of the Cape Fear Estuary and Walden Creek from 1977 through 1987.

I 2a34

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31 52 23 54 65 56 57 68

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- - - e : r t e s. e.

Figure 2.7 Results of time serics analysis for blue crab collected in Alligator Creek by the marsh trawl from 1981 through 1987.

I 71 I

d

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I 31 32 53 54 E5 e6 57 Ye:r I

Figure 2.8 Annual mean lege catch per unit effort for brown shrimp colluted in Alligator Creek by the marsh trawl from 1981 through 1987.

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_a 31 52 53 S4 SS 56 37 ece 4

Figure 2.9 Annual mean loge catch.per. uni! effort for white shrimp collected in Alligator Cretk by the marsh trawl from 1981 through 1987.

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ec:: ec

--- Ye:r les el l

I figure 2.10 Results of time series analysis for white mullet collected in Mott's Bay by the marsh trawl from 1981 through 1987.

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--- vocr evei Figure 2.11 Results of time series analysis for blue crab collected in Mott's Bay by the marsh trawl from 1981 through 1987.

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--- Ye ar 'es ei I

Figure 2.12 Results of time series analysis for w hite shrimp collected in Walden Creek by the marsh trawl from 1981 through 1987.

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I 2-37

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Figure 2.13 Results of time series analysis for Atlantic menhaden collected in Walden Creek by the marsh trewl from 1981 through 1987.

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Figure 2.14 Results of time series analysis for blue crab collected in Walden Creek by the l

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marsh trawl from 1981 through 1987.

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2-38 I.

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Figure 2.15 Results of time series analysis for bay anchovy collected in the lower river (Stations 1,4,7,8) by the nekton trawl from 1979 through 1987.

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Figure 2.16 Results of time series analysis for white shrimp collected by the nekton trawl in the lower river from 1979 through 1987 compared to annual mean catch at Alligator Creek from 1981 through 1987.

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Figure 2.17 Results of time series analysis for juvenile 1 adult croaker collected in the lower river and Snow's Cut by the nekton trawl from 1979 through 1987 (Snow's Cut was not sampled prior to 1981).

l 2-41

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river and Snow's Cut by the nekton trawl frorn 1979 thniugh 1987 (Snow's l

Cut was not s.ampled prior to 1981).

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I Figure 2.19 Annual mean catch for brown shrimp collected in the lower river by the nekton trawl from 1979 through 1987 compared to the results of time series analysis for catches at Snow 's Cut from 1981 through 1987.

I I

2-43

3.0 PLANT RELATED MONITORING PROGRAMS 3.1 Introduction Organisms in the CFE near the BSEP may be af fected by plant opera-tions in one of three ways:

initially, if the organisms are large encugh to be excluded by 9.4.mm mesh screening on the diversion structure, they I

are prevented from entering the intake canal (Figure 3.1)1 if they are small enough to enter the intake " anal, they may be impinged on the plant I

intake screens where they dre returned to the CFE via a fiume and return basin; if they are too small to be impinged, they may be entrained by the plant.

During the entrainment program, the species competition, seasonal-ities, and abundances of larval and postlarval organisms were documented over the past 10 years, while the Juvenile / Adult (J/A) impingement program documented species compositior, along with numbers, weights, and length-frequency d'.stributions of organisms impinged over the past 14 years.

I During the past five years, the impingement program and the nckton intake canal stations provided evidence of the effectiveness of the fish diversion structure.

The larval impingemen, program, which was begun in 1034 af ter completion of the return system, has provided estimates of the total number of larvae and postlarvae impinged and has evaluated the degree c

.scess of the fine-mesh screens in preventing organisms from being entrained.

Survival studies were initiated in 1994 te determine the degree to which the fine. mesh screens and return fluna were ef fective in returning the impinged organisms to the CFE alive.

These prograns I-continued to focus on these particular questions in 1987.

These program > were continued in 1987 with no changes from 1986.

A gill net study was also conducted during 1986 and 1987 to help determine the effectiveness of the diversion structure at excluding large fish not efficiently collected with the nekton trawl.

I I

3-1

I 3.2 Methods The collection gear and sampiing methods for entrainment and impinge ~

ment have remair.ed unchanged since 1984 (CPt.L 1985a).

The J/A impingement program inc.luded fish and shrimp 3 41 "n, portunid crab 3 25 mm, and eels 1 01 mm.

Individuals smaller than these cutoffs were 1

and pipefish included in the larval impingement prg ram.

I The densities of larval organisms entrained were salculated as in the river larval fish program.

The densities calculated for all organisms from samples collected per sampling date were averaged to obtain a mean 3

number per 1000 m of water pumped through the plant.

To obtain monthly estimates of impingement, the total number of hours in a month was divided by the number of hours sampled during that month.

This expansion factor was then multiplied by the number (for larval impingement) or by the mimber and weight (for J/A impingement) of all the organisms collected during that month.

The 12 monthly totals were then combined to obtain the annual estimate.

Densities for J/A organisms impinged were calculated using number per million cubic meters of water pumpea through the plant allowing for year-to-year comparisons regardless of the plant's water usage.

Survival studies were conducted during 1987 to collect data for tar-3E geted species. Methods werc identical to those reported in CP&L (1985a).

Two different mesh gill nets were deployed for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> at three intake canal nekton stations (4

5, and 6) every four weeks from April 1986 through April 1987 for the special gill net study.

One net consisted of 83.0-n stretch-mesh monofilament and the other was 68.7-mm stretch-mesh monofilament.

Both nets were 91.4 m long and approximately 3.9 m deep.

In evaluating the effectiveness of the fish diversion structure, nekton trawl catches at nekten Stations 5 and 6 (inside the structure) were compared to catches at Station 4 (outside the structure). A time-series analysis was performed on the combined trawl catches at stations I

3-2 j

B'

I inside the fish diversion structure from 1979 through 1987.

Spatial dis-tribution of species wcs determined by examining data from the nekton trawi and gill net at 9 3.3 Results and Discussion 3.3.1 Dominant Species Goblosoma spp. was the dominant organism entrained in 1987 and I

comprised 31.9% of the mean density of all organisms entrained.

Anchoa spp. ($ 12 mm) (15.2%) was second mt st abundant and croaker (12.9%) was third.

Other entrained taxa--in decreasing order of abundance--were spot, portunid megalops, postlarval shrimp, bay anchovy, Atherinidae, Microgobius spp., and Blenniidae (Tale 3.1).

The dominaut taxa in larval impingement were po;tlarval shrimp, spot, croaker, Anchoa spp., and portunid megalops (Table 3.2)

Each comprised between 12.1% and 16.3% of the total larval impingement catch.

The same I

seven species have dominated the larval impingement since 1984.

Ten taxa accounted for 92.7% of the total organisms impinged in 1987.

The r lative abundance of Anchoa spp. in larval impingement was high in 1986 but decreased in 1987 to levels of previous years (Table 3.2; CP&L 1937).

The densities of Anchoa spp. entrained were also reduced in 1987 (Table 3.1) probably as a result of low densities in the lower river (as documer,ted by the river larval fish program).

I The number of postlarval shrimp impinged in 1987 increased nearly 40%

8 7

over the number impinged in 1986 (1.1-x 10 compared to 6.9 x 10 ) because increased flows during August 1987 (a result of the new flow regime) coincided with the peak period of abundance for pink and white shrimp.

Even though substantially more postlarval shrimp were impinged as a result of this increased flow, survival estimates indicate that between 80.3% and 90.3% of these postlarvae were returned to the estuary alive (Sac-tion 3.3.7).

I 3-3

I Bey andovy dominated J/A impingement during 1987 accounting for 75%

l of the 3,573,000 organisms collected (Table 3.3).

Bay anchovy was fol-lowed in abundance by brown shrimp, white shrimp, blue crab, star drum, and Atlantic silverside.

These si-species accounted for almost 90% of total catch.

Total weight of all organisms coiletted was nearly 11,000 kg.

The density by number of J/A organisms impinged in 1987 was 42.1% less than in 1986, and the density by weight was 39.4% less in 1987 than in 1986.

When the 1987 density was compared to prediversion years (1977 through 1982) densities, decreases of 74.1% by number and 86.0% by weight were observed. (Table 3.3).

l Length frequencies of bay anchovy, Atlantic menhaden, spot, and croaker collected during 1987 in the J/A impingement program remained essentially unchanged from 1984 (CP&L 1985a) and indicate smaller organ-isms were impinged as a result of the fish diversion structure.

Atlar. tic menhaden, a previously abundant species (1977 through 1982),

was not among the ten most abundant organisms impinged during 1987 (CP&L 1982, 1983).

A declining trend in the abundance of Atlantic menhaden was also noted in the marsh (Table 2.8) and nekton programs (Table 2.9).

However, the fish diversion structure contributed substantially.,, reduced impingement by excluding most large individuals intluding the schooling Atlantic menhaden from the intake canal (CP&L 1985a 1985b).

35

,u Abundance 3.3.2 Sease-I The seasonality for relected entrained species was similar to previous years and usually corresponded to the seasonalities found in river larval fish data.

However, since fine-mesh screen installation and flow-minimization implementation (July 1983), peak abundance periods of entrained species may not correspond to peaks observed in the river larval fish program.

Peaks in entrainment can be induced by operation of nonfine-mesh screens or an increase in the flow of cooling water as deter-mined by plant operational needs.

3-4 I

i I

As expected, entrainment densities of portunid megalops and pink and white shrimp peaked in early September (Table 3.4).

A peak density i s f

observed for spot in early March, while Atlantic menhaden, bronn shrimp, and croaker peaked in late April.

Anchovies and Gobiosoma spp. peaked in early June.

I The typical winter and summer periods of abundance observed in the entrainment and river larval fish programs were also observed in larv61 impingement (Table 3.5).

Atlantic menhaden, spot, croaker, mullet, I

flounder, and brown shrimp--all ocean-spawned specdes--were most abundant during the winter and spring months.

The period of abundance for portunid megalops occurred during the late summer and fall.

Ocean-spawned species such as spotted seatrout, weakfish, pink and white shrimp, and the estuarine-spawned individuals--such as anchovy, Cobionellus spp.,

and Gobiosoma spp.--were most abundant during the summer (Table 3.5).

I-3.3.3 Entrainment Rates Entrainment rates were computed by multiplying the mean density per day by the mean flow through the plant per day.

The mean daily flow of 5

3 cooling water through the BSEP ranged from 9.2 x 10 m in early April to 6 3 5.4 x 10 m during much of July and August.

I 4

The-daily rate of total organisms entrained ranged from 5.3 x 10 in 7

mid-November to approximately 3.1 x 10 in early June.

Anchosy and Gobiosoma spp. represented the highest density and peaked in early June 7

7 with rates of 1.5 x 10 and 1.4 x 10, respectively (Table 3.6).

Portunid megalops were entrained at the maximum rate in early-September, while pink and white shrimp were entrained in peak numbers during mid-August.

The maximum entrainment rate for Atlantic menhaden occurred in January.

ot wert entrained at a maximum rate in early February, and during late nl croaker and brown shrimp entrainment rates peaked.

I I

3-5

I l

3.3.4 Flow Rates The volume of water entrained by the plant also affects the number and weight of organisms impinged and entrained.

The 1987 flow rates were greater than in 1986 but were below the 1977 through 1982 mean (CP&L g

1986).

Mean monthly intake flow rates in 1987 ranged from 4.5 x B

7 3 0

3 10 m / month in April to 1.7 x 10 m / month in August.

The mean monthly 0 3 flow for 1987 was 1.1 x 10 m / month (Figure 3.2).

The increased flow in 1987 was the result of two generating units which operated for most of the year and because increased flow rates were allowed as a result of the new flow rept :.

3.3.5 Flow Minimization A partial flow-minimization regime began in June 1981, whereby tne amount of water withdrawn from the estuary for coolina purposes was reduced (CP&L 1985a).

A more severe flow-reduction schedule was employed in Juiy 1983.

ihis schedule called for a maximum flow of 915 cubic fee per second (cfs) (25.9 cubic meters per second [ cms)) during three-pump operation and a maximum allo.iable flow of 605 cfs (17.1 cms) during two-pump operation.

The delineation between two-pump and three-pump operation was dependent upon intake water temperature.

At water temperatures of 65'F (18.3*C) and above (approximately the end of April), three-pump g

operation was allowed--below that (approximately the end of November) only E

two-pump operation was used.

A further restriction required that the two traveling screens on each unit equipped with fine-mesh screens be operated at all times.

I These flows and screen requirement regimes were followed throughout 1986 and remained intact until the new NPDES permit became effective in April 1987.

The new permit allowed for a r.aximum allowable flow of 922 cfs (26.1 cms) during throttled three-pump operation from December th.ough March and 1105 cfs (31.3 cms) during unthrottled three-pump operation from April through November.

One stipulation was all traveling screens operating on each unit during these flow regimes be equipped with fine mesh.

However, during the periods of peak summer water temperatures I

3-6

I (July, August, and September), a fourth pump with nonfine-mesh screen may be used to reach a maximum flow of 1230 cfs (34.8 cms) for one unit.

I The mean density and percent total of fish, penaeid shrimp, and portunid megalops entrained at tne BSEP from September 1978 through August 1987 are presented in Table 3.1.

The total mean density frem 3

September 1978 through August 1983 was 1692/1000 u.

From September 1983 I

3 through August 1987, the total nean density was 920/1000 m or 46% less than the density for the period whe1 fine-mesh screens were not being used.

A comparison of September 1983 through August 1986 with September 1986 through August 1987 showed an 16% reduction in mean density.

These two periods correspond to periods when only two fine-mesh screens nre in service compared to when three fine-mesh screens were in service.

3.3.6 Diversion Structure Evaluation The trawi catches of J/A spot, croaker, and Atlantic menhaden were higher during their respective periods of abundance outside the fish I

diversion structure than inside during 1987 (Table 3.7).

This distribu-tional pattern indicates that the fish diversion structure continued to be effective in reducing the abundance of large fish inside the intake canal.

Prior to completion of the fish diversion structure, catches of these species were approximately the same or higher inside the intake canal (Huish and Geaghan-1979; Schwartz et al.1979; CP&L 1982,1983).

l Results of the time-series analysis indicated a

significant decreasing trend in the abundance of J/A spot outside and inside the fish I

diversion structure.

The slope of the regression line for catches inside

(-5.07 x 10'4) the fish diversion structure was approximately three times what occurred outside (-1.64 x 10~4), indicating a reduction of abundance inside the fish diversion structure relative to any changes which occurred outside.

Catches of J/A spot were higher or approximately the same inside the fish diversion structure prior to the fish diver sion structure's completion during November 1982 (Figure 3.3).

Af ter that date, catches 3-7 4

L I

were higher outside the fish diversion structure except during 1986 when l

catches outside were at an all-time low.

A large number of damaged diver-sion screens occurred during peak abundance (January through June) of J/A spot.

One hundred and thirty damaged screens occurred in April and seventy-eight occurred in June of 1986.

(Screen damage generally occurred 2

in the corner of a screen resulting in 0.3 m of area lef t open per damaged screen.

On a midtide, this corresponded to 0.08% of the total diversion screen area lef t open per incident.)

Few damaged screens were found in 19 7 (maximum was 35 during July); and tP abundance of J/A spot decreased inside the fish diversion structur-though the annual abundance outside the fish diversion struc,

+

.ched that of 1981 (the highest catch for this species over the ens,e study period).

Nonsignificant trends in the catch of J/A croaker occurred both in-side and outside during the study period.

Abundances of this species were higher outside the fish diversion structure af ter its completion except for 1985 and 1986 (Figure 3.4).

Damaged diversion screens probably contributed to the nigh abundances that occurred during 1985 and 1986 (CP&L1986).

The time-series analysis could not be performed for the catches of Atlantic menhaden because none were collected inside the fish diversion structure with the nekton trawl during 1987.

Plots of mean loge (CPUE +

3 E

1) indicated that catches have been higher outside the fish diversion structure for the entire study period (Figure 3.5).

This distributional pattern ras a result of intensive effort to maintain the integrity of the fish diversion structure, especially during the period of seasonal occur-rence of J/A Atlantic menhaden, s

During the intake canal gill net study, Atlantic menhadeny spot, sharpnose shark, croaker, and bluefish comprised 97.4% of the total catch for both size nets combined (Table 3.8).

This species composition was similar to other studies using similar gear types (Huish and Geaghan 1979; Schwartz et al. 1979; CP&L 1980, 1982).

I 3-8 E

, I Atlantic menhaden were collected large numbers by both gill net sizes; however, the 68.7-mm stretth-r.

,h net collected spot, sharpnose shark, and croaker more efi u.ively than the 83.0-mm stretch-mesh net (Table 3.8).

Bluefish were c011ected in small numbers with both gears.

.14b mesh size selectivity described by These results were Marais (1985).

Lem c

tch larger fish.

Factors such as body shape, spines, "

Meptibility to capture.

l Catches of

.i se ish were higher outside the fish diversion strt.cta

.ieir respective periods of abun-dance (Table 3.f t

Al patterns were the reverse of that reported by Huis c

4 frr 1975 and 1976 indicating that the fish diversion sorac.

e 4

2 abundance of these species inside the intake canal.

Catches of Atlaritic men:.

.a. spot, and creaker were higher at one or both stations inside the fish diversion structure than outside.

The higher number of spot and croaker collected inside the fish diversion I

structure may represent the presence of resident individuals rather than failure of the fish diversion structure as evidenced by considerably larger spot and croaker collected inside the fish diversion structure than collected outside.

Forty-two percent of the spot collected outsVe were l_

larger than 177 mm; however, sixty-five percent of the spot collected inside were larger than this size.

Similarly, the average length of croaker collected outside was 213 mm and 45% of the croaker collected outside were larger than this size.

Ninety percent of the croaker col-lected inside the fish diversion structure were larger than 213 mm.

The higher Atlantic menhaden catches inside the fish diversion struc-ture were probably a function of a large number of damaged diversion screens which occurred during the spring and summer of 1986. A Spearman's rank order correlation coefficient (Ott 1984) of 0.94 was obtained for the relationship between monthly Atlantic menhaden catch and number of damaged ccreens per month indicating a strong relationship between the two var -

d a m s.

3-9

I 3.3.7 Survival Estimates Survival was determined for selected size classes of Atlantic g

menhaden, spot,

croaker, striped mullet, and flounder during 1987 5

(Table 3.10).

Survival values were determined for both screen rotation speeds (75 cm/ minute for slow and 187 to 200 cm/ minute for f ast) (CP&L 1985a,1986,1987).

I Previously small Atlantic menhaden (- 30-mm mean length) exhiL..ed no survival off of the traveling screens (CP&L 1987).

However in 1987, survival of Atlantic menhaden collected during f ast-screen rotation was documented indicating some individuals of this fragile species may survive impingement (Table 3.10).

Spot, croaker, striped mullet, and flounder examined during 1987 substantiated survival percentages reported in previous years (CP&L) 1985, 1996,1987). - Small spot (17-to 20-mm mean length) averaged approximately 30% survival when collected from fast-rotating screens (three times higher than the percentage observed from slow-rotating screens).

Survival of smail croeker (10-mm mean length) was also higher when collected from fast-rotating screens than from slow-rotating screens (68% survival compared to 25%).

The large croaker (56-mm mean length) collected from slow-rotating screens exhibited a lower survival value than had previously g

been reported (CP&L 1985a,1986,1987)

Survival of small striped mullet E

(23-mm mean length) in 1987 was substantially higher when collected from f ast-rotating screens (73% compared to 8%).

Flounder (15-mm mean length) exhibited excellent survival during 1987 (100%).

The survival values from four years of studies were similar to values reported from three years of study (CP&L 1987).

Organisms that exhibited good survival (> 70%) from f ast-rotating screens include all species and size classes of shrimp, crabs, striped mullet, flounder, searobin, tongue-g fish, and permit (Table 3.11).

Species that exhibited fair survival 3

(25%-70%)

included spot, croaker, and crevalle jack.

Species that displayed poor survival

(<

25%) included bay anchovy, weakfish, and Atlantic menhaden as well as Gobiosoma spp, and Gobionellus spp.

3-10

.I

I Survival ' values obtained from slow-rotating screens for four years were good for all shrimp and crab size classes except for the hardback shrimp which exhibited f air survival (Table 3.12).

Approximately 70% of the planehecd filefish examined survived.

Poor survival was observed in silversides and striped mullet.

Striped mullet previously exhibited good survival from f ast-rotating screens and poor survival frum slow-rotating screens (CP&L 1987).

As suggested in previous reports, the additional I

time spent out of the water during slow-rotating screens contributes to the low survival of particular species (CP&L 1985a).

Occasionally during survival studies, chlorine was detected in the water in the return fiume and the service water bays (CP&L 1985a).

When this occurred, survival studies were suspended until the chlorination system was secured.

Modificatic.s to correct this problem are currently in progress at the BSEP.

I Organisms collected and held as controls displayed high survival (Table 3.13).

With the exception of these fracile species (i.e., Atlantic menhaden, weakfish, and bay anchovy), all species collected and held exhibited control survival greater than 75%.

Percent survival for impinged larval and postlarval fish and shrimp (size classes 5 40 mm) and blue crabs (size classes 5 24 mm) were esti-mated for the period 1984 through 1987 Results from both rotating screen speeds were used for the estimates and are presented in Table 3.14 The annual impingement rate for selected species and total number of organisms impinged are presented in Table 3.14.

Survival percentages were applied to determine the number of organisms returned alive.

Fast and slow survival estimates were calculated for selected species from larval impingement and are presented in Table 3.14 The 16 taxa tested for sur-vival represent 70% of the total larval impingement catch.

Of these, 2.4 x 108 would have been returned alive to the estuary if the screens had been on fast rotation.

If the screens had been on slow rotatien, 1.9 x 8

10 would have been returned alive.

This corresponds to 52% and 41% of the total larval organisms tested returned alive to the estuary for I

3-11

l fast-and slow-screen rotation, respectively.

If bay anchovy are 8

excluded, the organisms tested for survival represent 4.0 x 10 or 61% of the total impingement.

If the intake screens had been on f ast rotation, 8

2.4 x 10 or 60% of the total organisms impinged would have been returned 8

alive to the estuary, while 1.9 x 10 or 48% of the organisms would have been returned alive assuming slow rotation.

Slow-screen rotation is the normal mode of operation and usually produces the lower survival.

During certain times of the year however (i.e., August, September, and October), the screens are of ten run on f ast rotation.

This of ten coincides with high densities of postlarval shrimp

nd portunid megalops in the intake canal.

During survival studies, 12 frequently impinged J/A species were also tested (Table 3.15).

The percent survival of a species during slow-3creen and fast-screen rotation is a mean of all data for the J/A size class of that species collected f rom 1984 through 1987 for these screen speeds.

Values obtained during fast-screen rotation were slightly higher in most Cases.

Juvenile / Adult shrimp and blue crabs impingement survival was ap-proximately 90%.

Spot and croaker survival was 57% and 53%, respectively, while bay anchovy showed poor survival at about 1%.

The application of g

E survival data to J/A impingement data show that if the screens had been operated on slow-screen rotation approximately 13.8% of the 1987 total number impinged and 50.8% of the total weight impinged would have been returned to the estuary alive.

When survival estimates were calculated excluding bay anchovy, the survival for the remaining organisms was ap-proximately 52% oy number and 64% by weight (Table ?.16),

3.4 Summary and Conclusions Seasonality of organisms and the dominant species collected in the 1987 entrainment program were similar to 1986.

Cobiosoma spp. accounted g

for over 30% of all organisms collected.

5 I1 l

3-12 I

I impingement catches of larvae were dominated by postlarval shrimp, spot, croaker, Anchoa spp., and portur.id megalops.

Approximately 70% of

~

the total larval organisms impinged were tested for survival.

Survival studies indicated 41%-52% of these organisms were returned to the estuary alive.

The diversion structure continued to be effective in reducing the I

number of Juvenile / Adult organisms impinged.

It was also of fective in reducing the abundances of Juvenile / Adult spot, croaker, and Atlantic menhaden in the intake canal.

The gill net study also indicated contin-uous maintenance of the diversion structure subsequently reduced the abun-dances of these species inside the intake canal during 1987.

The 1987 Juvenile / Adult impingement catch consisad of 3.5 million organisms weighing just under 11,000 kg.

Bay anchosy and brown shrimp were the most abundant species impinged.

In 1987, impingement per million I

cubic meters of water pumped decreased 42% in number and decreased 39% in weight when compared to the 1986 Catch.

The 1987 reduction in number and weight was 74% and 86%, respectively, over the 1977 through 1982 mean showing the continued effectiveness of the fish diversion structure.

Sur-vival studies documented a reduction in losses through Juvenile / Adult im-pingement.

The fish return system allowed approximately 14% by number and 51% by weight of all Juvenile / Adult organisms impinged to be returned to

-the estuary alive.

Excluding bay anchovy, approximately $2% by numoer and I

64% by weight of all organisms were returned to the estuary alive during 1987.

Overall, fewer organisms were affected by the operation of the BSEP than in past years.

The diversion structure has excluded large organisms, while fewer larval organisms were entrained.

Even though more larvae were impinged than in previous years aue to the operation of more fine-mesh screens, a large percentage of these organisms were returned to the Cape Fear Estuary alive.

I I

3-13

! I l

3 Table 3.1 Mean density (number /1000 m ) and percent total of fish, penacid shrimp, and portunid megalops entrained at thr. BSEP from September 1978 through August 1987.

September 1978 -

September 1983 -

September 1983 -

September 1986 -

August 1983 August 1986

___ August 1987 Aaqust 1987 Density Percent Density Percent Species Density Percent Density Percent Gobiosome spo.

373 22.0 289 30.5 283 30.7 247 31.9 Anchoo spp.

191 11.3 141 14.9 137 14.9 118 15.2 Croaker 170 10.0 71 7.5 76 8.2 100 12.9 Spot 164 9.7 69 7.3 71 7.7 82 10.6 Portunid megalops 235 13.9 36 3.8 38 4.1 45 5.8 Shrimp postlervae 145 8.6 33 3.5 35 3.8 43 5.6 Bay anchovy 177 10.5 57 6.0 53 5.8 36 4.6 m

b Atherinidae 61 3.6 139 14.6 120 13.0 19 2.4 Aficrogobius spp.

17 10 15 1.6 14 1.5 11 1.4 Bienniidae 13 0.8 21 2.3 19 2.1 S

1.1 Other taxa 146 8.6 16 8.0 74 8.2 65 8.5 lotal 1692 100.0 947 100.0 920 100.0 775 100.0 M

M M

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I I

Table 3.2 Total larvae impinged at the BSEP during 1987, ranked by per-cent.

I Species Percent of total I

Shrimp postlarvae 16.3 spot 14.5 I

Croaker 13.9 Anchoa spp.

13.4 Portunid megalops 12.1 Bay anchovy 9.5 Gobiosoma spp.

8.6 Striped anchovy 2.4 Cobionettus spp.

1.0 bilcrogobius spp.

1.0 Other taxa 7.3 I

_ _ Total 100.0 I

I I

I I

I I

I

/

3-15

mass-4 Table 3.3 A summary of juvenile _and adult impingement at the BSEP during 1987 with comparisons to previous years.

)

Number per million Weight (kg) per ~

l Percent Total cubic meters of Tetal million cubic meters i

Species of catch number water pumped weight (kg) of water pumped Bay anchovy 75.3 2,689,859 1,949.2 2,301 1.7 Brown shrimp 6.3 225,659 163.5 1,733 1.3 White shrimp 2.5 88,973 64.5 444 0.3 Blue crab 2.4 86,215 62.5 3,421 2.5 l

Star drum 1.7 60,877 44.1 138 0.1 Atlantic silverside 1.6 57,669 41.8 129 0.1 SpoL 1.3 46,987 34.1 309 0.2 5

Blackcheek tonguefish 1.1 40,559 29.4 132 0.1 Atlantic croaker 1.1 37,668 27.3 232 0.2 Pink shrimp 0.9 33,E61 24.I 82 0.1 Additional taxa (82) 5.8 205,487 148.8 2,064 1.4 198/ lotals 100.0 3,573,214 2,589.3 10,985 8.0 1986 Totals 5,001,933 4,471.8 14,785 13.2

-42.1

-39.4 Percent change (1987 vs. 1986) 1977-1982 annual mean 14,267,926 10,000.3 83,523 57.1 Percent change (1987

-74.1

-86.0 vs. 1977-1982)

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I Table 3.4 (continued)

Sample Total Atlantic Gobiax>ma Portunid date organisms Croaker menhaden Shrimp Spot Anchovy spp.

megalops 10 Mar 87 568.68 41.15 3.94 0.00 477.78 4.17 0.00 0.00 17 Mar 87 960.40 320.99 3.61 0.00 575.17 3.61 0.00 0.00 24 Mar 87 559.06 262.09 11.36 11.36 193.76 0.00 0.00 0.00 07 Apr 87 222.57 95.46 5.73 12.38 79.31 0.00 0.00 0.00 14 Apr 87 446.46 98.99 12.31 11.80 122.95 12.93 0.00 0.00 21 Apr 87 759.82 518.05 15.45 11.19 110.17 0.00 0.00 3.73 28 Apr 87 1,042.19 805.58 8.78 48.09 72.68 5.94 0.00 0.00 05 May 87 541.81 317.67 0.00 5.93 40.25 11.29 0.00 0.00 12 May 87 263.13 81.65 0.00 2.68 16.38 10.93 36.25 5.55 19 May 87 1,090.85 20.85 0.00 0.00 2.60 140.63 522.55 2.71 w

d; 26 May 87 829.42 19.19 0.00 5.25 0.00 107.16 515.04 0.00 02 Jun 87 7,769.45 0.00 0.00 10.00 0.00 3,701.16 3,476.99 2.74 09 Jun 87 1,426.21 0.00 0.00 13.77 0.00 763.51 379.38 0.00 16 Jun 87 944.78 0.00 0.00 49.22 0.00 390.18 397.67 19.15 23 Jun 87 979.28 0.00 2.60 118.62 2.75 496.62 241.93 0.00 07 Jul 87 2,191.90 0.00 0.00 75.81 2.71 383.36 1,419.28 11.63 14 Jul 87 398.42 0.00 0.00 31.10 0.00 133.44 188.75 0.00 21 Jul 87 2,659.77 0.00 0.00 50.75 0.00 718.12 1,761.54 18.77 28 Jul 87 328.58 0.00 0.00 26.73 0.00 248.84 248.74 0.00 04 Aug 87 1,428.51 0.09 0.00 55.23 0.00 124.94 1,122.03 0.00 11 Aug 87 601.15 0.00 0.00 88.11 0.00 109.91 332.28 16.71 18 Aug 87 1,515.99 0.00 0.00 274.46 0.00 215.54 786.17 16.08 25 Aug 87 384.28 0.00 0.00 190.34 0.00 61.67 86.69 0.00 isa uun man mun mum num aus uns aus sus amm sum uma uma mas uns uma aus

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Table 3.5 Total number of selected species collected by trip in larval impingement at the BSEP during 1987.

Sarnple Atfantic Pen 6eus Grdsio-Gobio-Portunio Total date Anthowy menhaden-Seatrout Spot Croaker Mullet Flounder

spp, nellus spp, some spp.

megalops organisms 08 Jan 87 872 4

0 337 1,751 6

36 4

15 10 7

3,248 13 Jan 87' 2,332 15 0

490 3,821 24 12 0

8 4

4 6,902 26 Jan 87 1.014 52 0

1,147 1,898 45 58 4

9 0

0 1,494 27 Jan 87 3,400 23 0

1,559 5,214 118 7

0 1

0 0

10,472 03 f eb 87 491 23 0

13,447 5,374 BR 165 0

4 8

0 19,828 10 feb 87 4,164 74 0

8,753 12,720 333 98 0

54 8

0 2/,426 17 f eb 87 489 94 3

10,240 5,131 1,325 368 0

28 0

0 19,320 24 f eb 87 751 68 0

10,722 3,711 274 106 4

45 0

0 16.057 03 Mar 87 7?

155' O

6,981 4,324 210 287 0

63 0

0 12,930 10 Mar 87 245 171 0

9,945 706 150 12 0

89 0

0 11,592 w

17 Mar 87 86 70 0

13,766 4,423 44 130 1

593 0

0 19,848 24 M4r 87

$ '> 2 180 0

6,145 10,157 58 78 294 586 4

0 18,397 07 Mar 87 293 112 0

626 954 2

16 83 84 0

6 2,215 14 Apr 87 129 102 0

1.442 2,027 5

21 252 95 5

63 4,310 21 Apr 87 154 197 0

3,034 4,823 0

8 269 257 0

47 9,836 28 Apr 87 206 54 0

712 3,955 4

15 795 263 0

42 6,4e9 05 May 87 188 15 0

615 3,669 0

15 324 162 0

8 5,T87

!? May 87 58 4

2 til 1,370 2

0 118 137 6

183 2,313 i

19 May 87 1,106 0

0 76 368 0

0 157 81 104 333 2,661 26 May 87 1,263 0

54 24 526 0

4 99 40 331 12 2,942 02 Jun 87-20.456 0

221 8

67 0

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1,023 8

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720 4

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42 0

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28 0

0 0

0 1,564 79 6,400 58 23,093 28 Jul 67 12,292 0

40 0

0 0

0 3,766 43 7,508 387 24,980

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I Table 3.7 Mean log, (CPUE+1) and standard deviation for trawl catches of juvenile and adult spot, croaker, and Atlantic menhaden col-lected outside (Station 4) and inside (Stations 5 and 6) the I

BSEP fish diversion structure during 1987.

l Species Station 4 Station 5 Station 6 Spot 4.53 1 1.54 0.98 1 1.38 0.18 3 0.41 Croaker 1.23 1 0.76 0.68 i 0.57 0.35 1 0.53 Atlantic menhaden 2.93 1 0.31 0.0 0.0 I

I I

I I

I I

I I

I I

I 3-23

Table 3.8 Total number, percent total number, and catch-per-unit effort (CPUE) of the five most abundant species collected in the BSEP gill net study from April 1986 through April 1987.

68.7-mm mesh 83.0-un mesis 80th gears Percent Percent Percent Total of Total of Total of i

CPUE number total Taxa number total +

CPUE number total Atlantic menhaden 4798 84.2 5.7 2819 85.5 2.9 7617 84.7 Spot 276 4.8 0.3 7

0.2 0.0 283 3.1 Sharpnose shark 261 4.6 0.3 131 4.0 0.1 392 4.4 Croaker 194 3.4 0.2 118 3.6 0.1 312 3.5 Bluefish 63 1.1 0.1 90 2.7 0.1 153 1.7 Y

,a lotal for five most abundant 5592 98.2 6.1 3165 96.0 3.2 8757 97.4 Other taxa 104 1.8 0.1 132 4.0 0.1 236 2.6 Total number 5696 100.0 6.2 3297 100.0 3.3 8993 100.0 IDifferences in percent of total number and CPUE are due to rounding.

M m

M m

M M

.M M

M M

M M

M M

M M

M G

\\

l Table 3.9 Mean loge (CPUE+1) and standard deviation for the five most abundant species collected outside and inside the BSEP fish diversion structure during the gill net study from April 1986 I

through April 1987.

I-Station Species 4 (cutside) 5 (inside) 6 (inside)

Atlantic menhaden 68.7-mm mesh 0.63 3 0.33 1.36 1 1.51 0.71 1 1.12 83.0-m mesh 0.47 1 0.36 0.94 2 1.22 0.43 1 0.56 i

l Spot 0.08 1 0.07 0.31 1 0.23 0.54 1 0.53 Sharpnose sharki 0.96 1 0.14 0.34 1 0.09 0.74 ! 0.17 Croaker

• 0.15 1 0.12 0.23 1 0.23 0.11 3 0.08 Bluefish I

68.7-mm mesh 0.22 1 0.08 0.02 1 0.02 0.09 1 0.12 83.0-mm mesh 0.28 1 0.18 0.02 1 0.03 0.04 1 0.04

1. esults are compiled from the data collected with the 68.7-mm mesh R

I nets only since these species were more effectively collected by this gear type.

I I

lI lI I

I I

3-25

I s

Table 3.10 Mean percent 96-hour unadjusted survival values for selected 3

finfish held during survival studies at the BSEP during 1987.

E Hean percent survival Size (SL)

Experiment _all Control Species Date Ran::e (mm)

Mean (mm)

Slow Fast Spot February 9 14-22 17 5.8 37.7 91.6 February 16 14-22 18 23.4 92.3 March 2 15-24 20 14.1 79.7 Croaker February 9 10-19 13 24.7 77.8 February 16 10-15 12 67.7 88.1 July 6 44-70 56 12.5 34.6 93.3 Atlantic March 16 28-41 32 17.9 menhaden April 6 23-39 29 0.0 1.5 68.6 Striped March 2 19-28 23 8.2 94.,

g mullet March 16 18-28 23 73.0 80.5 g

Flounder March 16 1.3-18 15 100.0 97.9

% ndicates relative speed of screen rotation.

I I

I E

E I

I I

I I

I, 3-26 8

M M

M M

M M

M M

M M

M M

M M

E E

E E

E Table 3.11 Survival percentages for organisms collected during fast-screen rotation at the BSEP from 1984 through 1987.

Number Percent Initial Latent Total Taxa Trials Collected Stocked mortalityI mortalityS survivalE Croaker 25 3,941 1,891 36.1 47.4 33.6 Spot 14 2,276 945 19.8 62.2 30.3 Shrimp juveniles 7

302 257 1.7 5.8 92.6 Shrimp postlarvae 4

482 241 3.3 6.6 90.3 Brown shrimp 6

239 225 3.3 12.0 85.1 White shrimp 2

86 79 0.0 8.9 91.1 Pink shrimp 1

36 35 2.8 0.0 97.2 liardback shrimp 1

33 29 12.1 10.3 78.8 Blue crabs 6

213 121 1.9 5.0 93.2 Blue crab megalops 2

159 71 1.9 11.3 87.0

,5 Bay ancoovy 4

394 215 40.1 97.7 i.4 Weakfish 4

282 191 29.4 82.2 12.6 Searobin 4

132 124 2.3 8.1 89.8 St riped nullet 4

160 141 11.9 18.4 71.9 Blickcheek tonguefish 3

110 95 5.5 15.8 79.6 Flounder 3

139 125 6.5 1.6 92.0 Goby 2

477 0

100.0 0.0 Atlantic menhaden 4

354 186 14.1 94.1 5.1 Cobinnellus spp.

I 117 64 45.3 71.9 15.4 Permit 1

27 26 3.7 11.5 85.2 Crevalle jack 1

39 36 7.7 61.1 35.9 INumber of organisms that were found dead in collection gear + number collected.

SNumber of orgar. isms that died af ter being stocked in tanks + number stocked.

5100 - l(t) (number collected) + (T) (number stocked) + (S) (other live organismi collected but not stocked)l + nunber collected.

Table 3.12 Survival percentages for organisms collected during slow-screen rotation at the BSEP from 1984 through 1987.

Number Percent initial Latent Total E

i mortalityI survival laxa Trials Collected Stocked mortality Croaker 22 3,179 1,493 45.9 70.0 16.3 Spot 17 3,100 1,287 36.1 82.8 11.0 Shrimp juveniles 2

100 91 9.0 14.3 78.0 Shrimp postlarvae 3

612 181 6.9 13.8 80.3

)

Brown shrimp 5

350 336 2.9 6.5 90.8 White shrimp 1

4 r.

30 2.3 6.7 91.2 ilardback shrimp 3

452 151 44.9 16.6 46.0 Blue crabs 3

71 61 2.8 3.3 94.0

[

Blue crab megalops 2

203 135 3.0 11.1 86.3 Bay anchovy 2

955 141 81.8 98.6 0.3 Striped trollet 2

346 121 54.6 84.3 7.1 Goby 1

203 0

100.0 0.0 Silverside 1

59 C

100.0 0.0 Planehead filefish 1

33 31 6.1 25.8 69.7 Atlantic menhaden 2

222 123 32.9 100.0 0.0 INumber of organisms that were found dead in collection gear + number collected.

SHumber of organisms that dicd after being stocked in tanks + number stocked.

5100 - l(t) (number collected) + (1) (number stocked) + (S) (other live organisms collected but not stocked)) + number collected.

Im M

M M

M M

M ME M

M M

M M

M M

W W

M M

m m

m m

M M

M m

m m

m m

M W

W M

m' W

M Table 3.13 Survival percentages for control organisms collected for survival studies at the BSEP from 1984 through 1987.

Number Percent Initial Latent Total i

mortalityS survivals Taxa Trials Collected Stocked mortality Croaker 31 4,481 2,069 5.5 8.0 86.9 Spot 22 3,893 1,602 3.3 11.6 85.5 Shrimp juveniles 9

658 429 2.3 4.4 93.4 Shrimp postlarvae 4

392 232 3.6 7.3 89.4 Brown shrimp 11 1,171 531 2.6 18.3 79.6 White shrimp 3

182 113 2.2 7.1 90.9 Pink shrimp 1

34 34 0.0 23.5

/6.5 liardback shrimp 3

1,032 156 4.6 6.4 89.3 Y

Blue crabs 10 434 197 1.6 6.6 91.9 E

Blue crab megalops 4

362 231 7.2 7.4 86.0 Bay anchovy 5

356 258 8.1 20.2 73.3 Weakfish 3

155 116 3.2 40.5

-;4.1 Searobin 4

104 97 1.9 1.0 97.1 Striped mullet 4

193 170 2.1 6.5 91.7 Blackcheek tonguefish 4

475 146 0.2

'1 98.4 flounder 3

315 98 1.0 2.0 97.0 Atlantic menhaden 2

57 50 12.3 56.0 38.6 INumber of organisms that were found dead in collection gear + number ;ollected.

SNumber of organisms that died af ter being stocked in tanks

-r number stocked.

100 - l(t) (number collected) 4 (S) (number stocked). (S) (other live organisms collected but not E

stocked)l + number collected.

Table 3.14 Percent survival and e. umber of impinged larval organisms returned alive to the Cape Fear Estuary during 1987.

Percent survival Nu=ber returnd alive Fast-Slow-Fast-

$10w-Total screen screen screen screen 5cecies number impinged rotation rotation rotation rotation 7

7 7

Croaker 9.2 x 10 33.7 14.4 3.1 x 10 1.3 x 1G 7

7 Spot 9.6 x 10 29.4 9.0 2.8 x 10 8.6xIC')

7 5

Bay anchovy 6.3 x 10 0.7 0.3 4.4 x 10 1.9 x 10 Shrimp postlarvae 1.1 x in 90.3 S0.3 9.9 x 10 8.8 x 10' 6

6 Flounder 1.6 x 10 93.2 1.5 x 10 5

6 6

Striped mullet 2.9 x 10 69.8 7.1 2.0 x 10 2.1 x 10 7

7 7

Portunid megalops 8.1 x 10 87.6 86.3 7.0 x 10

'.0 x 10 i

6 5

Weakfish 2.8 x 10 12.6 3.5 x 10 0

5 Searobin 2.1 x 10 89.8 1.9 x 10 6

6 6

liardback shrimp 6.4 x 10 78.8 48.4 5.0 x 10 3,; y 19 4

4 4

Pink.md white shrimp 8.0 x 10 95.8 75.0 7.7 x 10 6.0 x 10 5

5 6

Blue crabs 5.2 x 10 91.7 95.1 2.0 x 10 2.1 x 10 w

cotsoncitus spp.

6.5 x 10 15.4 1.0 x 10 6

6 Pe rmit 1.3 x 10 85.2 1.1 x 10 4

3 Crevalle jack 2.1 x 10 35.9 7.5 x 10 6

4 Atlantic w?nha@n 1.6 x 10 3.2 0.0 5.1 x 10 0

I Anchou spp.

8.9 x 10 0

Other organisms (;5 taxa) 1.1 x 10 8

Total organisms 6.6 x 10 Total organisms tested 4.6 x 100 (70%)I 2.4 x 108 (52%)5 1.9 x 106 (41%)E Total crganisms tested

_ (excluding bay anchovy) 4.0 x 108 (61%}S 2.4 x 103 (60%)E 1.9 x 100 (48%)E I Percent of total organisms impinged that were tested.

SPercent ef total organisms impinged that were tested excluding bay anchovy.

bPercent of i returned alive.

EPercent of S returned alive.

. ~.

I Table 3.15 Percent survival of juvenile and adult crganisms impinged at BSEP during slow-and f ast-screen rotation from 1984 through

1987, I

i I

Slow-screen rotation fast-screen rotation fercent Numver f'erc ent fIumber i

Species survival of tpsts survival of tests Blue crabs 92.1 2

96.2 3

Shrimp spp.

86.5 5

93.7 20 5-(pinkandwhite) 92.0 2

Striped r'ui et Brown shrinip 90.7 8

90.4 10 83.1 6

Blackcheek tonguefish Flounder

/1.1 1

Spot 57.1 4

60.4 2

Croaker 53.1 6

45.1 8

Weakfish 35.0 2

Atlantic menhaden 15.6 1

Bay anchovy 1.1 2

4.9 2

I I

g I

I I

3-31

I Table 3.16 Estimated survival of juvenile and adult organisms impinged at g'

the BSEP during slo,<-screen rotation in 1987.

g Impfnged Estimated survival Species Number Weight (kg)

_Eumber Weight (Egl Blue crabs 114,225 3,504 105,201 3,227 Brown shrimp 225,659 1,733 204,673 1,572 Shrimp spp.

(pink and white) 122,234 526 105,732 455 I

Spot 46,987 309 26,830 176 g

Creaker 37,668 232 20,002 123 Bay anchovy 2,689,859 2,301 29,588 25 Other, species (86 taxa) 336,582 2,380 Total 3,573,214 10.985 492,026 5.578 Percent survival 13.8 50.8 l

Excluding bay anchovy 883,355 6684 462,438 5,553

_ercent survival 52.3 63.9 P

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(tarvas entrained -

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100% mortality)

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f **tw;e INTAKE CANAL -

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Hgure 3.1 Brunswkk Steam Dettric Plant intake, discharge, diversaun structure, and return systents with associated effects on fish.

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Figure 3.2 Mean monthly flow of water pumped at I1SEP from 1977 through 1982, l

1986, and 1987.

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---.,,-,-,-v,-w--,-w----.

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- r.sice e-++ 0 ts ic e Figure 3.3 Results of time series analysis showing year level tenns for juvenile / adult spot collected outside and inside the fish diversion structure by the nekton

< p$

L trawl from 1979 through 1987.

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.---...< 3:: e e-e--e 0./ s M e Figure 3.4 Results of time series analysis showing year levtl terms for juvenile / adult crooker collected outside and inside the fish diversion structure by the nekton I

trawl from 1979 through 1987.

3-35

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OUTSIDE I

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Ye:r INSIDE Figure 3.5 Results of time series analysis showing year level terms for.luvenile/ adult Atlantic menhaden collected outsidt and inside the fish diversion structure by the nekton trawl from 1979 through 1987, I

3. se

.4-

..-,__,--..w+_,_-.,_._._-.__,_.-_v,__

I

4.0 REFERENCES

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1987.

Population and fishery characteristics of Atlantic menhaden, Brevoortia tyrarmus.

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Ambrose, J.,

Jr.

1983.

Age determination.

Pages 301-324 In L.

A.

Nielson and O.

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Johr;on (eds.).

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S.,

B. J. Copeland, and R.

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Carolina State University Raleigh, NC.

Blaber, S.

J., and T. G. Blaber.

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Factors affecting the distribu-I tion of juvenile estuarine and inshore fish.

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CP&L.

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1979 monitoring program.

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Carolina Power & Light Company, New Hill, NC 1982.

Brunswick Steam Electric Plant annual biological moni-l torTag report, 1981.

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1984.

Brunswick Steam Electric Mant 1983 biological moni-toring repcrt.

Carolina Power & Light Company, New Hill, NC.

1985a.

Brunswick Steam Electric Plant 1984 biological moni-toring report.

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I 1985b.

Brunswick Steam Electric Plant, Cape fear Studies, Interpretive Report.

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I Copeland, B.

J., R. G. Hodson, ar.d R. J. Monrce.

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Larvae and post-larvae in the Cape fear River estuary, North Carolina, during opera-tion of the Brunswick Electric Plant, 1974-1978.

North Carolina

' State University, Raleigh, NC.

Deegan, L.

A.,

and J.

W.

Day, Jr.

1984.

Estuarine fishery habitat requirements.

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Hart, N. Davis, I

and S.

Friday (eds.).

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'~'

I

I

Everhart, H.

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and W.

D.

Youngs.

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Principles of fishery science.

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1979.

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Hodson, R.

G.,

C.

R. Bennett, and R. J. Monroe.

1981.

!chthyoplankton samplers for simultaneous replicate sampics at surf ace and bottom.

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T., and K. L. Nichols.

1981.

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Analysis of a nursery ground.

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A. L. Pacheco (ed.).

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juvenile stages of fish in Atlantic Coast estuaries.

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g E

Lagler, K. F.

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_R

I McHugh, J.

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Hart, N.

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of fish eggs and larvae:

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Weinstein, M. P.

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Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape fear River, North Carolina, fish. Bull, 77:339-357.

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Multiple deter-minants of community structure in shallow marsh habitats, Cape fear Estuary, NC.

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I 4-3