ML20079M986
| ML20079M986 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 12/31/1985 |
| From: | Benedict C, Booth G, Cates K CAROLINA POWER & LIGHT CO. |
| To: | |
| References | |
| RTR-NUREG-1437 AR, NUDOCS 9111110031 | |
| Download: ML20079M986 (104) | |
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' Brunswick Steam Electric Plant lI g, 1985 BIOLOGICAL MONITORING REPORT I
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BIOLOGY UNIT ENVIRONMENTAL SE RVICES SECTION CP&L Carolina Power & Light Company 111 P ti! D31 1437 C PDR
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BRUNSWICK STEAM ELECTRIC PLANT 1985 BIOLOGICAL MONITORING REPORT Prepared by:
C. Benedict - Juvenile and Adult Impingement G. f. Booth - Project Scientist K. N. Cates Entrainment, Larval Impingement I
D. S. Cooke -
Larval fish W. E. Herring - Water QJality K. A. MacPherson Editor I
L. W. Pollard - High Marsh M. E. Shephard -
Statistics T. E. Thompson Nekton I
H. T. Tyndall -
Survival Studies W. Warren-Hicks -
Statistics I Biology Unit Environmental Services Section i CAROLINA POWER & LIGHT COMPANY NEW HILL, NORTH CAROLINA March 1986 I
Reviewed and Approved by:
if O . Ut1AO Principal Scientist Biology Unit l' This report was prepared under my supervision and direction, and I accept full responsibility for its content.
I MkAAG Manager /"
Environmental ServicesSection I
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This copy of this report is not a controlled document as detailed in Environmental Services Section Procedures, Any changes meio to the original of this report subsequent to the date of issuance can be obtained fr(es Ranagsr invironmental Services Section Carolina Power & Light Ccapany Shearon llarris Energy & Environmental Center Route 1, Ibn 327 New Hill, North Carolina 27562 5
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'I Acknowledgments Many thanks are extended to the individuals including Debbie Calhoun, Scott Cates, Della Lanier, Preston McLendon, Tina Reece, and R. G.
Sherfinski who, without their assistance in collecting, identifying, and
! processing of samples, this report would not have been possible. Steve Parrish assisted in field collections as boat captain of the Pisec.5 and constructed and maintained field and lai oratory equipment.
I Thanks alst go to members of the Data Management & Control Unit, Bio-logy Unit, and Word Processing Subunit at the Shearon Harris Energy r.
Environmental Center. A very special thank you is extended to Anne L.
Lineback who typed the draf ts associated with the preparation of this report.
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Table of Contents r
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ACknoWIedgments .................................................. 1 list of Tables .................................................. v List of figures .................................................. vili Metric-English Conversion Table................................... x Executiva Summary................................................. xi 1.0 INTR 000CT10N...................................... ....... 1-1 2.0 w m R ou4u n............................................. 24 2.1 Introduction.............................................. 2-1 l 2.2 2.3 Methods ..................................................
Results and Discussion....................................
2-1 2-2 3.0 RIVER LARVAL f!SH......................................... 3-1 1 3.1 Introduction.............................................. 3-1 3.2 Methods .................................................. 3-1 g 3.2.1 Sample Collection......................................... 3-1 l 3.2.2 Data Analysis............................................. 3-1 3.3 Results and Discussion.................................... 3-2 3.3.1 Dominant Species.......................................... 3-2 l 3.3.2 3.4 Time-Series Analysis......................................
Summary and Conclusions...................................
3-2 3-3 4.0 HIGH MARSH................................................ 4-1 1 4.1 Introduction.............................................. 4-1 4.2 Methods .................................................. 4-1 4.2.1 Station Description....................................... 4-1 1 4.2.2 Sampling Methods.......................................... 4-1 4.2.3 Data Analysis............................................. 4-2 4.3 Results and Discussion.................................... 4-2 4.3.1 Catch by Gear Type........................................ 4-2 1 4.3.2 Spatial Distribution...................................... 4-3 '
4.3.3 Seasonal Distribution..................................... 4-4 4.3.4 Time-Series Analysis...................................... 4-5 I
l Baldhead Creek............................................
Walden Creek..............................................
4-5 4-5 Mott's Bay................................................ 4-6 Alligator Creek........................................... 4-6 4.3.5 Return Basin Evaluation................................... 4-7 4.4 St.mma ry a nd Co nc l u s i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7 5.0 NEKTON .................................................. 5-1 5.1 Introduction.............................................. 5-1 5.2 Methods .................................................. 5-1 ii
I Table of Contents (continued) g; Pale ;
5.3 Results and 01scussion.................................... 5-2 ;
5.3.1 Total Organisms........................................... 5-2 5.3.2 Spatial Distribution...................................... 5-3 5.3.3 5.3.4 Time-Series Analysis......................................
Diversion Structure Evaluation............................
5-3 5-4 l 5.4 Summary and Conclusions................................... 5-6 6.0 ENTRAINMENT............................................... 6-1 6.1 Introduction.............................................. 6-1 6.2 Methods .................................................. 6-1 E 6.3 Results and Discussion.................................... 6-2 g 6.3.1 Dominant Species.......................................... 6-2 6.3.2 Seasona l i ty and Abu ndance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-2 6.3.3 6.3.4 Number Entraincd..........................................
Flow Minimizacion.........................................
6-3 6-3 l 6.3.5 Time-Series Analysis...................................... 6-4 6.4 Summary and Conclusions................................... 6-4 7.0 SURVIVAL STUDIES.......................................... 7-1 7.1 Introduction.............................................. 7-1 3 7.2 Methods .................................................. 7-1 3 7.2.1 Collection................................................ 7-1 7.2.2 Stocking and Monitoring................................... 7-1 7.2.3 Definitions, Calculations, and Data Analysis.............. 72 7.3 Results and Discussion.................................... 7-3 7.3.1 Total Organisms........................................... 73
- 7. ': . 2 Species Accounts.......................................... 7-3 l Croaker .................................................. 7-3 m Spot .................................................. 7-4 P e n a e i ri S h r i r..p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-5 g Blue Crab................................................. 7-5 g Striped Mu11et............................................ 7-6 Flounder.................................................. 7-6 Bay Anchovy............................................... 7-6 Miscellaneous Species..................................... 7-6 7.3.3 Two-Year Averages. ....................................... 7-7 7.4 Summary and Conclusions................................... 7-7 8.0 IMPINGEMENT (Larva 1)...................................... 8-1 8.1 Introduction.............................................. 8-1 g 8.2 Methods .................................................. 8-1 g 8.3 Aesults and Discussion.................................... 8-2 8.3.1 Dominant Species.......................................... 8-2 8.3.2 Seasonality and Abundance.......................... ...... B-2 8.3.3 Survival Estimates........................................ 8-3 8.4 Sunnary and Conc l u s i ons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-3 9.0 IMPlNGEMENT (Juvenile and Adult).......................... 9-1 l 9.1 Introduction.............................................. 9-1 9.2 Methods .................................................. 9-1 l 9.3 Results and Discussion.................................... 9-2 1
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l a TableofContents_(,continuedl 1
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9.3.1 9.3.2 Species Composition.......................................
Flow Rates................................................
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i 9.3.3 Length-Frequency Distributions............................ 9-2 l j 9.3.4 S u r y I v a l E s t i .aa t e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3 ;
9.4 Summa ry a nd Co nc l u s i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9-3 l
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10.0 REFERENCES
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List of Tables l Table 1.1 USEP 1985 biological monitoring program summary...........
Pagg 1-3 3.1 Annual mean density end the percentage of the total mean density for the ten most abundant taxa collected in the river larval fish program, 1980 through 1985....... 3-5 3.2 Results of time-series analysis for river larval fish data by station group indiceting trends in density from 1977 throligh 1905............................ 3 r-4.1 Total catch and percent total of the ten most abundant species collected in the high marsh study during 1985..... 4-9 4.2 Annual catch-per-unit-effort by creek system for 12 selected species in the high marsh study during 1985...... 4-9 4.3 Results of time-series analysis of high marsh data by creek indicating trends in abundance from 1981 through 1985.............................................. 4-10 5.1 Total number, percent total number, and annual catch-I per-unit-effort of the ten most abundant species collected in the nekton study during 1985................. 5-7 5.2 Annuhl catch per-unit-effort by station of the dominant I neaanisms collected in the nekton study during
. d5............................ ......................... 5-8 5.3 Results of time-series analysis of nekton lower river data indicating trends in abundance from 1979 through 1985.............................................. 5-9
- 5.4 Results of analysis of variance and Duncan s multiple range test for selected species utilized in the eval-l uation of the BSEP fish diversion structure for the 1
l years 1979 thrcugh 1985................................... 5-10 5.5 Date-by-stationinteractionforthemeanlog$nd I (CPUE + 1) of juvenile / adult spot, croaker, Atlantic menhaden collected in the intake canal c'uring the preoperational and postoperational I
periods of the fish diversion structure, 1979 throuoh 1965.............................................. 5-11 l v I
I List of Tables (continued)
Page 6.1 Mean density and percent total of fish, penacid shrimp, and portunld crabs entrained, September 1978 through August 1985.................................. 6- 6 6.2 Entrainment densities at the BSEP from September 1984 through August 1985.................................. 6-7 6.3 Entrainment rates at the BSEP from September 1984 through August 1985....................................... 6-9 6.4 Results of time. series analysis of entralr. ment data indicatirg trends in density from September 1980 through August 1985....................................... 6-11 7.1 Mean standard lengths of organisms examined during 96-hour survival studies at the BSEP during 1985. . . . ... . . . 7-8 7.2 Mean percent 96-hour unadjusted survival values for croaker held during survival studies at the BSEP during 1985...................................................... 7-9 7.3 Results of analysis of variance for spot and croaker by screen speed collected during survival studies at the BSEP during 1985................................... 7-9 7.4 Mean percent 96-hour unadjusted survival values for spot held during survival studies at the CSEP during 1985...... 7-10 7.5 Mean percent 96-hour unadjusted su: vival values for selected shellfish held during survival studies at the BSEP during 1985.......................................... 7-10 7.6 Mean percent 96-hour unadjusted survival for miscel-laneous specict held during survival studies at the 8SEP duiing 1985.......................................... 7-11 7,7 Survival perct.ntages for organisms collected during E fast-screen rotation at the BSEP during 1984 5 and 1985.................................................. 7-12 7.8 Survival percentages for organisms collected during slow-screen rotation at the BSEP during 1984 and 1985..... 7-13 l
7.9 Survival percentages for control organisms collected for survival studies at the BSEP during 1984 and 1985..... 7-14 8.1 Ranking by percent U +otal larval impingement collect-ed at the BSEP during 1985................................ 8-5 vi l
ListofTables(continuedj P_gg ;
8.? Total number of selected species collected by trip in i
- larval imping.~ ment at the BSEP during 1985................ 3-6 l g 8. 'i Overall percent survival and number of impinged larval u organisms returned alive to the Cape fear Estuary......... 8-7 E 9.1 A summary of juvenile and adult impingement at the
- i. E BSEP during 1985 with comparisons to previous years....... 9-5 9.2 Estimated survival of juvenile and adult organisms impinged duiing 1985...................................... 9-6 T
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D list of figures L
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( l.1 Location of fish diversion structure, sluiceways, and return basin at the BSEP...............,.............. 1-4
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1.2 River larval fish and water quality samplirq locat:ans in the Cape Fear Estuary during 1985...,.................. 1-5 1 1.3 High marsn sampling areas and nekton sempling locat it.,ns in the Cape ftar Estuary during 1985...................... 1-7 2.1 Bottom salinity for selected stations in the Cape fear Estuary from September 1984 thrnugh December 1985.... 2-3 2.2 Bottem temperature for selected stations in the Cape fear Estuary f mm September 1984 through December 1985...................................................... 2-4 3.1 Results of time-series av. lysis of dobiosoma spp.
collected in the lower and upper areas of the Cape fear Estuary, 1977 through 1985........................... 3-/
3.2 Results of time-series analysis of total organisms collected in the lower and upper are35 of the Cape Fear Estuary, 1977 through 1985...................... 3-8 d.1 Cumulative length-frequency analysis of Spot collected by trawl in upper Walden Creek and the return basin in the high marsh study during 1985.......................... 4-11 4.2 Cumulative length-frequency analysis of crooker 1 collected by trawl in upper Walden Creek and the return basin in the high marsh study during 1985................. 4-11 4.3 Cumulative lengtn-frequency analysis of brown shrimp collected by trawl in upper Walden Creek and the return basin ir the high marsh study during 1985................. 4 12 5.1 Results of time-series analysis for juvenile / adult spot collected in the intake canal by the nekton trawl f r om 19 81 t h r o u g h 19 8 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12 5.2 Results of time-series analysis for juvenile / adult croaker collected in the intake canal by the nekton trawl from 1981 through 1985.............................. 5-12 5.3 Results of time-series vialysis for juvenile / adult Atlantic menhaden collected in the intake canal by the nek ton trawl f rom 1981 tnrough 1985. . . . . . . . . . . . . . . . . . . 5-13 viii
List of F1,qufes (continued) em 5.4 Cumulative length-frequency analysis of spot collected by the nekton trawl inside and outside the fish diversion structure during 1985..................................... 5-14 5.5 Cumulative length-frequency analysis of creaker col- I 1ected by the nekton trawl inside and outside the fish diversion structure during 1985........................... 5-14 9.1 Mean monthly flow of water entrained at the BSEP.
1977 through 1982, 1984, and 1985.......................... 9-7 I
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Metric-English Conversion Table LeJ5jth 1 micron (um) = 4.0 x 10'b inch I mi111 meter (mm) = 1000 um = 0.04 inch I 1 centimeter (cm) = 10 mm = 0.39 inch 1 treter (m) = 100 cm 3.28 feet I kilometer (km) = 1000 m = 0,62 mile Area I 1 square meter (m2 ) = 10.76 square feet I hectare = 10,000 m2 = 2.47 acres Wejsht, 1 milligram (mg) = 3.5 x 10-5 ounce 1 gram (g) = 1000 mg = 0.035 ounce 1 kilogram (kg) = 1000 g = 2.2 pounds volume I 1 milliliter (ml) = 0.034 fluid ounce 1 liter = 1000 ml = 0.26 gallon 1 cubic meter per second (cms) = 35.3 cubic feet per second Temperature Degrees Celsius ('C) = 5/9 ("F - 32)
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txecutive Summary
) This report contains the results of biological monitoring conducted 8
in the Cape fear Estuary (CfE) and at the Brunswick Steam Electric Plant (OSLP) during 1985. Comparisons are made between 1985 results and pre-vious years.
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Samples of various life stages of fish and shellfish populations in the estuary continued to indicate that trends and distributions were re-lated to environmental variables. The river larval fish study indicated
- that the seasonality and distribution of larval and postlarval organisms e did not 135tantially change f rom previous years, while the abur ance s of these organisms increased. Samples of the successive life t; ages in the tidal creeks indicated that a shif t in abundance of the dominant species toward the upper estuary occurred during 1985 as a result of low fresh-
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water flow and the subsequent increased salinity. The trends and distri-L butions of juvenile and adult fish in the estuar' were also associated with the flow conditions as well as the cyclic nature of populations
[ utilizing the estuary.
I Additional studies it dicated that intake modifications remained effective in reducing lossts due to impingement and entrainment. The I diversion structure excluded larger estuarine organisms from the intake canal and from possible impingement. This is important in that these larger individuals are or will soon t9 members of the reproducirq populations. The number of total organisms impinged was high due to the installation of fine-mesh screens but the number of organisms entrained was much lower. As a result, fewer nrganisms were lost from the estuary. Survival studies indicated that subs *antial numbers of Impinged organisms were returned to the ettuary alive which further reduced the impact of the BSEP. Finally, the flow-minimization scheme, which was fully implemented in July 1983, continued to be ef fective in reducing entrainment and impingement.
Evidence accumulated in 1985, as well as previous years, indicates that the operation of the BSEP has not af fected the abundance, season-ality, or distributions of organisms in the estuary. Environmental condi-tions have been and continue. to be the dominant force influencing the populations of organisms in the CfE.
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1.0 INIRODUCTION l
In January 1981 Carolina Power & Light Company (CP&L) was issued a
[ permit to discharge cooling water f rom the Brunswick Steam Electric Plant (BSEP) into the Atlantic Ocean under the National Pollutant Discharge
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Climination System (NPOES). Water used for cooling is drawn from the Cape fear River (CFR). One stipulation of the permit was that biological moni-toring be continued that would provide sufficient information to allow for a continuing assessment of the impact of the BSEP on the Cape fear Estuary I (CFL) with particular emphasis on the marine fisheries. With some modifi-cation, this biological monitoring requirement was a continuation of re-search that had been conducted on the CFL by various investigators since 1976 ar.d. as a resuit, some programs in this report will discuss trends from 1970 to 1985. In general, this report draws from the Interpretive Report (CP&L 1985b) and the 1984 Biolcgical Monitoring Report (CP&L 1985a) and provides for a comparison to data reported in these two reports. A summary of the 1985 biological program is presented in lable 1.1.
I Another stipulation of the permit was the construction of two intake modifications to reduce entrainment and impingement of estuarine organ-isms. A permanent fish diversion structure was built across the mouth of the intake canal in November 1982 to prevent larger fish and shellfish from entering the canal and from possible impingement at the plant (Figure 1.1). The effectiveness of the structure is discussed in the nekton and impingement sections of this report. In addition, fine-mesh (1-mm) screens were installed on two of the four intake traveling screen assemblies on both units in July 1983 to reduce entreinment. Inc effec-tiveness of this modification is addressed in the entrainment and larval impingement sections of this report, in addition to these modifications, the NPDES permit also required a reduction in the volume of cooling water used by the plant. This reduction is discussed in the entrainment section.
The study periods evaluated in this report dif fer by program. Tne entrainment and river larval fish programs report on data collected f rom September 1984 through August 1985 to correspond to periods of larval 1-1
I recruitment, while the nekton, high marsh, survival, and impingement programs report en data collected from January through December 1985.
The stations sampled by each program are shown in Figures 1.2 and 1.3. Figure 1.2 shows the sampling locations for the river larval fish, water quality, and entrainment programs, while figure 1.3 shows the high marsh and nekton sampling locations. Because several stations were sam-g pied in each creek by the high marsh program, the entire creek is design- E ated as a sampling area. A more detailed illustration of specific sam-pling locations within these areas can be found in the 1981 annudi report (CP&L 1982).
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I Table 1.1 BSEP 1985 biological monitoring program summary.
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Program frequency Locations I Nekton Once every three weeks I, 2, 4-8, 10-16 High marsh Seine Once every three weeks 12, 16, 22, 25, 31, 32 Trawl Once every three weeks 11-17, 21-29, 31-32, l 41-44, 51
, River larval fish Once per calendar month 11, 18, 24, 25, 34 ,
l (Jun-Aug) and once every 37, 41 twoweeks(Jan-May, Sep-Dec)
Impingement Juvenile and adult once every week Fish return sluiceway >
Larval Once every two weeks Fish return sluiceway Entrainment Once every week Discharge wtir Survival studies As needed Fish return sluiceway and intake canal Water quality once every week 11, 15, 19, 24, 25, 29, 35, 38, 42 l3 I
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Iigure 1.3 (continued) l l-8
I 2.0 WATER QUALITY 2.1 Introduction Salinity is a major f actor influencing the spatial distribution of estuarine species (Weinstein et al. 1980). Fluctuations in salinity caused by freshwater inflow and variations in tidal stages produce changes I in the abundance of species in an area. In 1982 the water quality program was initiated to supplement water temperature and salinity data for the river larval fish, high marsh, and nekton programs in aa attempt to better determine periods of freshwater inflow. '
, I The estuary is subject to highly variable and relatively large in-flows of freshwater from the Cape fear drainage basin. The two-layered flow regime, typical of coastal plain estuaries, is usually present in the portion of the estuary above Sunny Point (Figure 1.2). Net nontidal drift I results in a net upstream flow of more saline water in the lower layer and a net seaward flow of less saline water in the upper layer. These flows result in a salinity gradient whose position and shape is co6stantly being modified. The portion of the estuary seaward of Sunny Point, in which tha BSEP is located, is typical of a marine, well-mixed system (Carpenter and Yonts 1979). Complex water circulation patterns, vigorous tidal action, and high-exchange ratios with the ocean result in this reach of the estuary acting as an extensit of the nearby coastal zone.
2.2 Methods The same nine water quality stations which were sampled weekly in 1984 were again sampled in 1985 (CP&L 1985). Water quality data were also collected every three weeks from the high marsh and nekton programs (Figures 1.2 and 1.3).
I Surf ace samples were dipped from the surf ace with a bucket, and bot-tom samples were collected with a 2-liter Kenmerer water sampler. Temper-I ature was measured in degrees Celsius C) and salinity was measured in 5 parts per thousand (ppt).
2-1
Bottom salinity and temperature values were plotted for three sta-tions in the CFR channel which are representative of the various salinity regimes and for three stations which are characteristic of three creek systems: Baldhead, Walden, and Alligator creeks (figures 2.1 and 2.2).
2.3 Results and Discussion In the Cape fear Estuary, salinity typically exhibits a decilne dur.
ing the winter months and an increase from early spring through late sum.
mer. This trend is a direct result of high freshwater inflow during the winter and low freshwater inflow during the summer. For the period Sep-tcmber 1984 through December 1985, three deviations to this pattern were observed.
In September 1984. Hurricane Diana passed over the CFE dumping over 40 cm of precipitation and causing a decline in salinity values hcth in the river channel and creek systems. During Aegust 1985, two large in-fluxes of freshwater caused salinity to decline sharply during a period of g normally high salinity (figure 2.1). Overall, salinity was generally u higher in 1985 than in 1984 River channel and creek stdtions exhibited seasonal variations in temperature during the year. A maximum bottom temperature of 32.5'C was obset ved in early September 1985 in Baldhead Creek, and a minimum bottom temperature of 1.3'C was recorded during January 1985 in upper Walden Creek (Figure 2.2).
The distribution of organisms in the estuary is largely influenced by changes in the temperature and salinity profile. The effects of these changes are discussed in more detail, where appropriate, in the following sections.
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- Soldhead Creek 3 000 Walden Creek IE ++o Alligotor Creek Fiqure 2,1 Bottom salinity for selected stations in the Cape Fear Estuary from September 1984 through December 1985.
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-Baldhead Creek ecoWalden Creek g o+o Alligator Creek E F!sure 2,2 Bottom temperature for selected stations in the Cape Fear Estuary from September 1984 through December 1985, 2- 4 -
I 3.0 RIVER LARVAL FISH I 3.1 Introduction I Sampling continued in 1985 to monitor the abundance, species composi-I tion, spatial distribution, and temporal distribution of larval and post-larval fish and shellfish in the Cape fear Estuary. Data from 1985 were I compared with data from previous years to detect and quantify any signifi-m changes in the numbers of those organisms which utilized the CFE and
, n were saceptible to being " cropped" by the operation of the BSEP.
!] Fopulatior trends in Walden Creek were of particular interest due to its proximity to the intake canal.
I 3.2 Methods '
3.2.1 Sample Collection I The sampling stations (7), gear, and sampling frequency used in this study have remained unchanged since 1901 (Figur 1.2). Simultaneous replicate 1ples nre nllected at night from the surface and bottom at each :tation with 1-m diar.:eter $05-um mesh nets mounted in rectangular frames (Hodson et al. 1981).
3.2.2 Data Analysis I Larval densities were computed by expanding the volume of water fil-tered by the net and the corresponding number of organisms to obtain a number of organisms /1000 m3 .
Application of the loge (density + 1) trans-format 1on to individual samples helped to normalize tae base data.
l For the purpose of analysis, the 1985 larval fish year began in Sep-tember 1984 and continued through August 1985. Data were subjected to time-serics analysis to uetermine the periods of occurrence of particular species and to detect whether or not any species had exhibited a stat 15-I tical change in abundance over the past nine years. The data consisted of 12 observations each year where each observation was the mean of all 3-1
I surface and bottom samples collected during a month. Spatial differences
- were analyzed by averaging data from Station 11 for the lower estuary and comparing these results to data averaged from "tations 34 and 41 in the upper estuary. The time-series neodel development is described in CP&L (1985a). l 3.3 Results and Discussion 3.3.1 Dom'nant Species The larvel taxa collected in the greatest densities in 1985 were sim-ilar to the species composition collected during each of the past five years. In decreasing order of abundance during 1985, they were anchgvy Anchoa spp.; croaker Micropogonias undulatus; portunid megalops; goby Gobio-soma spp.; spot Leiostomus xanthurus; shrimp Penaeus spp postlarvae, brown shrimp P. aztecus, pink shrimp P. duorarum, and white shrimp P. setiferus; swimming crabs Portunidae; silversides Atherinidae; blennys Blenniidae; and hardback shrimp Trachypenaeus constrictus. These ten taxa have accounted for more than 90% of the total density during the past six years (Table 3.1). Other recreationally and commercially important species col- g lected included Atlant ic menhaden Srevoortia tyrannus, seatrout Cynoscion E nebulosus and C. regalls, flounder Parallchthys spp., and mullet Mugil cephalus E
and M. curema. F'tuctuations of mean density between years are due -g primarily to spawning success, transport mechanisms (wind and currents),
water temperature and salinity, and other natural factors which affect the abundance of larval and postlarval organisms (Norcross and Shaw 1984).
3.3.2 Time-Series onalysis '
The seasonal occurrence for the selected species in 1985 were similar to previous reports (Copeland et al.1979; CP&L 1981:,1983,1984,1985a).
I I
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f I Spot Croaker late December through early May Early October through late April y8 g
Portunid megalops I flounder late August through mid-December late December through late March S]m t Mullet late December through late March 38?
Atlantic menhaden late February through mid-May 5 Shrimp postlarvae I - brown
- pink and white Mid-February through mid-May Late May through early October "u
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=
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Anchevy late April through late October U$
Seatrout Early May through mid-October pg I
m Gobiosoma spp. Early May through late October "g D2
.a 1 Table 3.2 summarizes results of time-series analysis for selects g's I species at each station group. Although there have been year-to-ye, am EC U
fluctuations in densities, no declining trends were observed for at W larval species except Gobiosoma spp. in Dutchman Creek (Station 11). ,
the same time, Gobiosoma spp. densities increased significantly in t 5~
upper estuary (Figure 3.1). Time-series analysis indicates an overall i 3%
creasing trend in the density of total organisms during the past ni g' years in all areas except Dutchman e, .ek where there was no significa "E change (F igure 3.2). This increase was primarily due to increasas in a g
chovy and Gobiosoma spp. in the Upper estuary stations and Gobionetlus sp I throughout the estuary, including Dutchman Creek. Croaker densities ha h],;{
{
not changed significantly in the river channel stations t,ut have increas significantly in both Wu.Jen and Dutchman creeks.
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3.4 Summary and Conclusions "09
{~y vyu e u I The speciet, composition and seasonal occurrence of larvae and cos larvae in the CFE have not significantly changed during- the past ni
]S S"E years. With the exception of Gobiosoma spp. in Dutchman Creek, there ha I been no-significant declines of larvae and postlarvae in the CFE. The fjf
<E' has been a significant increase of larvae in the river and Walden Cret
]
While tnere has not been any significant change in the total density .
larvae in Dutchman Creek, densities of croaker, Goblonellus spp., i S Penceus spp. have increased.
3-3
. I
I Table 3.2 Results of time-series analysis for river larval fis Reducti statior, group indicating trends in density from 19) and operatio 1385.
the increasi CreekovertI Station Groups Dutchman Creek Walden Creek Lower River Ut
~
11 24 18 + 25 + 37 -
Taxon +/- R T~ +/- R 2
+/- R 2 4 Anchovy NS 0.97 NS 0.97 +*** 0.98 +$
Croaker +*** 0.92 +*** 0.95 NS 0.97 Flounder NS 0.90 NS 0.87 NS 0.89 CoNosoma spp. .* 0.94 NS 0.93 NS 0.95 -
Gobionellus spp. +*** 0.93 +*** 0.91 +*** 0.86 v' Atlantic menhaden NS 0.80 NS 0.81 NS 0.80 Mullet NS 0.82 +* 0.84 NS 0.6/
Seatrout NS 0.87 +* 0.86 NS 0.87 Spot NS 0.96 NS 0.97 NS 0.96
+** 0.94 NS 0.94 +** 0.91 +'
Penocus spp.
Total organisms NS 0.99 +*** 0.99 +*** 0.99 +'
NS P > 0.05
- 0.01 < P 5 0.05
- ' O.001 < P $ 0.01
- P $ 0.001
(+) = Indicates increase
(-) = Indicates decrease R2 = emount of variation explained by the time-series mode 3-6
I Spot Late December through early May g
Croaker Early October through late April Portunid megalops late August through mid-December I Flounder Late December through late March Mullet late December through late March Atlantic menhaden Late February through mid-May Shrimp postlarvae
- brown Mid-February through mid-May
- piak and white Late May through early October Anchovy late April through late October Seatrout Early May through aid-October Goblosoma spp. Early May through late October Table 3.2 summarizes results of time-series analysis for selected species at each station group. Although there have been year-to-year
^
fluctuations in densities, no declining trends were observed for any larval species except Gobiosoma spp. in Dutchman Creek (Station 11). At the same time, Gobiosoma spp, densities increased significantly in the upper estuary (Figure 3.1). Time-series analysis indicates an overall in-creasing trend in the density of total organisms during the past nine years in all areas except Dutchman Creek where there was no significant change (Figure 3.2). This increase was primarily due to increases in an-chovy and Gobiosoma spp. in the upper estuary stations and Gobinnallus spp.
throughout the estuary, including Dutchman Creek. Croaker densities have not changed significantly in the river channel ststions but have increased significantly in both Walden and Dutchman creeks.
3.4 Summary and Conclusions The species composittor, and seasonal occurrence of larvae and post-larvae in the CFE have not significantly changed during the past nine years. With the exception of Gobiosoma spp in Dutchman Creek, there have been no significant declines of larvae and postlarvae in the CFE. There has been a significant increase of larvae in the river and Walden Creek.
, While there has not been any significant change in the total density of larvae in Dutchman Creek, densities of croaker, Gobionellus spp., and Penaeus spp. have increased.
3-3 I
I Reductions of pooulations in Walden Creek, due to the construction and sparation of the BSEP, have not occurred. This was demonstrated by tne increasing density of total larval and postlarval organisms in Walden Creek over the pust nine years.
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Table 3.1 Annual mean density (organisms /10003 0 ) and the percentage of the total mean density for the ten most abundant taxe collected in the river larval fish program, 1980 through 1985 (based on ranking for the 1955 larval year).
1980 1981 1982 1983 1984 1985 Mean Mean Mean Mean Mean Mean Taxa density % density % density % density % density % density %
Anchovy 1937 63.6 585 34.5 722 35.3 614 41.6 578 47.5 1032 52.7 Croaker 232 7.6 208 12.3 479 23.8 367 24.9 210 17.2 256 13.1 Portunid megalops 176 5.8 143 8.4 259 12.8 I?4 7.8 104 8.5 190 9.7 Gobiosomo spp. 359 11.8 434 25.6 198 9.8 8t 5.8 82 6.8 101 5.2 Spot 76 2.5 84 4.9 123 6.1 71 4.8 63 5.2 99 5.1 1 Shrimp postlarvae 122 4.0 52 3.1 54 2.7 75 5.1 63 5.2 88 4.5 Portunidae 11 0.4 8 0.5 12 0.6 7 0.4 7 0.6 33 1.7 Silverside 11 0.4 27 1.6 15 0.8 6 0.4 11 0.9 23 1.2 Blenny 10 0.3 17 1.0 8 0.1 9 0.6 7 0.6 19 1.0 Hardback shrimp 13 0.4 10 0.6 8 0.4 14 0.9 8 0.7 17 0.9 r
Other taxa 99 3.2 131 7.5 137 6.8 112 7./ 85 6.8 102 4.9 Total organisms 3046 100.6 1699 100.0 2015 100.0 1475 100.0 1218 100.0 1957 100.0
Table 3.2 Results of time-series analysis for river larval fish data by station group indicating trer.ds in density from 1977 through 1985.
Station Groups Outchman Creek Walden Creek Lower River Upper River 11 24 18 + 25 + 37 3' + 41 Taxon +/- 2 7, p2 +/-
2 I R R +/-_ _ R Anchovy NS 0.97 NS 0.97 +*** 0,98 +*** 0.96 Croaker +*** 0.92 +*** 0.95 NS 0.97 NS 0.94 Flounder NS 0.90 NS 0.87 NS 0.89 NS 0.84 '
Gobiosoma spp.
- 0.94 NS 0.93 NS 0.95 +** 0.86 Goblonellus spp. +*** 0.93 +*** 0.91 +*** 0.86 +*'* 0.80 Atlantic menhaden NS 0.80 NS 0.81 NS 0.80 NS 0.78 Mullet NS 0.82 +* 0.84 NS 0.67 NS 0.62 Seatrout NS 0.87 +* 0.86 NS 0.87 NS 0.85 Spot NS 0.96 NS 0.97 NS 0.96 NS 0.92 Penceus spp. +** 0.94 NS 0.94 ++* 0.91 +*** 0.84 Total organisms NS 0.99 +*** 0.99 ++** 0.99 +*** 0.98 NS P > 0.05 g
- 0.01 < P $ 0.05
- 0.001 < P 5 0.01
- P < 0.001 l
(+) = Indicates increase n
(-) = indicates decrease R2 = amount of variation explained by the time-series model 3-6
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t U ,,,1 7 7 7 7 8 8 8 6 8 6 8 6 7 8 9 0 1 2 3 4 5 6 Yaar
- OBSERVED -- PREDICTED .~ YEAR LEVEL LOWER ESTUARY (Station 11: Dutchman Creek) i l
n-S' 56' i \
dl I
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= '
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- a ;\ ,
gi j f i i
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7 7 7 7 8 5 S S S S 8 6 7 8 9 0 1 2 3 4 5 6 Year
- OBSERVED --- PREDICTED ** YEAR LEVEL UPPER ESTUARY (Stations 34 and 41)
Figure 3,1 Results of time-series analysis of Goblosoma spp. collected in lower and upper areas of the Cape Fear Estuary,1977 through 1985.
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7 7 7 7 8 8 8 8 8 8 8 W 6 7 8 9 0 1 2 3 4 5 6 Year
- OBSERVED --- PRED!CTED .* YEAR LEVEL LOWER ESTUARY (Station 11: Dutchman Creek)
E-I.
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7 7 7 ' o a a e a a a 6 7 8 9 0 1 Year 2 3 4 5 6
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- OBSER'vED --- PREDICTED m YEAP LEVEL UPPER ESTUARY (Stations 34 and 41)
Figure 3.2 Results of timeseries analysis of total organisms collected in lower and upper areas of the Capa Fear Estuaty,1977 through 1985.
I <
3- 8
1 I ;
4.0 HIGH MAR 5d 4.1 Introduction The marshes of the CFE provide nursery areas for many fish and shell-fish. It has been estimated that as much as 93% of the East Coast's com-I mercial fish, shellfish, and sport fish spend at least a portion of their lives in estuaries (McHugh 1967). Biological monitoring of the fish and shellfish in the marshes of the CFE is important to determine if the BSEP's removal of estuarine water for cooling purposes has any adverse effect on their populations and distributions. Tht:refore, the scai,onal and spatial distributions of, and any aonormal trends in, populations of selected fish and shellfish were investigated. Trends from 1981 through 1985 are discussed in this section.
4.2 Methods 4.2.1 Station Description
.I Baldhead, a polyhline creek (16-30 ppt salinity), is located adja-cent to the mouth of the CFR (Figure 1.3). Walden Creek is located adja-cent to the BSEP intake canal and is considered to be meschaline (8-16 ppt). Mott's Bay is an oligohaline-meschaline (0.5-16 ppt) area located upriver from the BSEP. Alligator Creek is a fresh-oligohaline creek (0-8 ppt) located in the upper estuary west of Wilmington. Baldhead Creek, Walden Creek, and Mott's Bay were sampled using a trawl and a seine, while a trawl only was used in Alligator Creek. One trawl station was sampled in the fish return basin in 1985. More detailed descriptions of the high marsh stations are presented in CP&L (1982,1985a).
. 4.2.2 Sampling Methods I The 1985 sampling gear, sampling methods, and laboratory procedures y were identical to those used in previous years (CP&L 1982, 1983, 1984, 1985a). Discussions of seasonal and spatial distributions and trends are based on data gathered by the gear type considered the most effective for
'I each soecies.
4-1 i
I 4.2.3 Data Analysis Recruitment sizes and- periods were determined for each species by examining length-frequency distributions for each creek. Oc asionally the number of individuals collected in a given creek system 'fas low, thus mak-ing reliable recruitment size and period estimates impractical. m The blue crabs Callinectes sapidus, which dominated the catch, and C.
similis were grouped for time-series analysis. Lowcr identification cutoff limits we.re enforced at 20 mm for each of the penacid shrimp species and ,
at 10 mm for blue crabs. Shrimp and blue crabs below these size limits were identified to genus and family, respectively, due to difficulties in identifying these size organisms to species.
Data collected in the high mar 3h study from 1981 through 1985 were- -
subjected to a time-series analysis. Catch-per-unit-effort (CPUE) data (by creek) were transformed to natural logs (CPUE + 1) before analysis.
Significance of the upward or downward trends was determined at the P $ 0.05 level. l A Kolmogorov-Smirnov two-sample test was used to determine if the cumulative length-frenency distributions of organisms in the return basin differed significantly- (P $ 0.05) from that in an adjacent creek. More g detailed explanations of the statistical analyses are presented in CP&L E (198Sa).
I 4.3 Kesults and Discussion 4.3.1 Catch by Gear Type A total of 119,484 fish representing 87 species and 110,326 inverte-brates represer. ting 12 species was collected in 1985. A total of 391 trawl samples yielded 85,297 fish (CPUE of 218) and 71,423 invertebrates (CPUE of 183), whilu 102 seine samples yielded 34,187 fish (CPUE of 335) and 38,903 inverteorates (CPUE of 381). Spot Leinstomus xanthurus was the most abundant organism collected by trawls in 1985 with a CPUE of 147 and I
4-2 I
I comprised 36.8% of the total caten (Table 4.1). Spot was followea in abundance by grass shrimp Polaemonetes spp. (CPUE of 140), brown shri:np Penaeus aztecus (CPUE of 30), bay anchovy Anchoa mitchilli (CPUE of 28), and Atlantic menhaden Brevoortia tyrannus (CPUE of 19). Previous studies by Hodson (1979), Huish and Geaghan (1979), Weinstein (1979), and CP&L (1982, I- 1983, 1984, 1985a) also indicated that catchan were generally dominated by these same spe 4es.
Grass shrimp was the most abundant species collected by seines (CPUE of 343) and comprised 47.9% of the total catch. Grass shrimp was followed in abundance by spot (CPUE of 110), Atlantic menhaden (CPUE of 61), white mullet Afugi,1 curema (CPUE of 47), mummichog Fundulus heteroclitus (CPUE of 31), and Atlantic siherside Afenidia menidia (CPUE of 30). The dominant species collected with seines wire similar to those obtained by Weinstein (1979) and CP&L (1982,1983,1984, 1985a) using seines in selected tidal creeks.
I .
4.3.2 Spatial Distribution The dis +.ribution of most aquatic organisms in the estuary is deter-mined by salinity (Copeland and Hodson 1977; Weinstein et al. 1980; CP&L 1985a). Therefore, the selection of a particular area (creek system) by the migrating organisms within the estuary is primarily influenced by the _
salinity regime of that area.
I The CPUE by creek was used to dete mine the creek systems that sup-ported the greatest abundance of each selected species in 1985 (Table 4.2). Baldhead Creek, which is generally a polyhaline system, yielded the highest catch of Atlantic silverside. In the past, catches of white mullet, a polyhaline species, were also highest in Baldhead Creek.
This changed in 1985, however, because of one trip in Mott's Bay which yielded over 2000 young-of-year in one sample. The highest catches of white mullet on previous and subsequent trips occurred in Baldhead Creek.
I Walden Creek, which is generally a meschaline system, had substan-tially higher CPUEs for brown shrimp, mummichog, and striped mullet Afugil 4-3
cephalus than any other creek system. The CPUEs for blue crab Callinectes scpidus was only slightly higher in Walden Creek than in Mott's Bay. Six species were most abundant in Walden Creek in 1984 as compared to four in 1985. This could be the result of an increase in salinity due to high freshwater flow in 1984 and low freshwater flow in 1985 (United States Geological Survey data) which allowed migrating organisms to move past Walden Creek and into the upper estuary.
Mott's Bay is an oligohaline-meschaline area located in the upper estuary well past the influence of the BSEP. Collections in this area produced substantially higher catches of bay anchovy, croaker Micropogonias undulatus, and pink shrimp Penaeus duora.um; while spot, Atlantic menhaden, and white mullet were only slightly higher. Generally, many of these species are more abundant in the lower estuary. Que to low freshwater flow during the first half of 1985, t. .! F "~ity increased in the upper estuary. This allowed many of the r haline species to migrate further into the estuary and utilize the N . s Bay area. In 1984 only three species were most abundant in Mott's Bay as compared to six in 1985.
Alligator Creek is a fresh-oligohaline creek wnich is located close enough to tha head of the estuary to prevent any large salinity in-creases. The idrgest concentration of flounder Paralichthys spp, was in Alligator Creek which was cor:sistent with previous studies (Weinstein et 3 al. 1980; CP&L 1984, 1985a). The abundance of spot was slightly lower in
- Alligator Creek than in Mott's Bay. However, the number of spot collected *
! in Alligator Creek in 1985 was much greater than in 1984, probably as a result of low freshwater flow and increased salinity which may have in-creased suitable habitat in this area (Copeland et al. 1979; CP&L 1985a).
l 4.3.3 Seasonal Distribution l
The seasonal distribution of many .'estua-ine species is associated with recruitment of the individual species to the gear type (i.e., species obtain sufficient size to be collected by the given gear type). The maxi-mum abundance and the minimum size of most species are related to peak recruitment. After recruitment ends, an increase in size and u decrease 4-4 l
l l
In number usually becomes apparent. During the several months residence l l- and growth period, most species decline in numbers in the marsh due to emigration and natural mortality. The seasonal and size distribution of j the selected species collected in 1985 followed these patterns.
The recruitment of spot, Atlantic menhaden, croaker, striped mullet, i flounder, and blue crab peaked in the late winter and early spring. White l mullet, Atlantic silverside, brown shrimp, mummichog, and bay anchovy l l spawned later in the year and recruitment peaked in late spring and summer. Two selected species, white (Penaeus setiferus) and pink shrimp, I di! played peak recruitment in the fall. These seasonal distributions were similar to the distributions of previous years (Weinstein et al. 1980; CP&L 1984, 1985a).
3 4.3.4 Time-Series Analysis Baldhead Creek No significant change in abundance of the selected species occurred ,
in Baldhead Creek from 1981 through 1985 (Table 4.3). Most species de-creased slightly in 1985 from previous yecrs, possibly due to the low freshwater flow conditions which resulted in higher salinity in Baldhead Creek (CP&L 1982,1983,1984,1985a). In 1983 and 1984, abu- ance of most species was higher due to the high freshwater flow conditions (CP&L 1984, 1985a).
1 Walden Creek l The abundance of croaker, flounder, 3nd brown shrimp in Walden Creek increased significantly from 1981 through 1985 (Table 4.3). Croaker and flounder are more oligohaline-oriented as postlarvae which explains the increase in abundance in 1983 and 1984 (high freshwater flow) and the l small decrease in abundance in 1985 (low freshwater flow). The high freshwater flow conditions in 1983 and 1984 allowed large numbers of these species to utilize Walden Creek as a suitable habitat producing an overall increasing five-year trend. Brown shrimp have increased steadily from I
4-5
~
1981 through 1985 resulting in a significant increase in abundance, while Atlantic menhaden, blue crab, spot, pink shrimp, striped mullet, and white mullet showed no significant increasing or decreasing trend over the study -
period.
Mott's Bay No significant change in abundance of the selected species occurred in Mott's Bay from 1981 through 1985 (Table 4.3). There were, however, small fluctuations in abundance in 1985 as compared to 1984. These changes which appeared to be related to flow conditions were not substan tial enough to produce significant trends.
A_]ligatorCreek The abundance of flounder end brown shrimp in Alligator Creek sig-nificantly increased over the study period (Table 4.3). The number of flounder decreased slightly from 1984 to 1985 (Table 4.2; CP&L 1985a).
This small decrease in 1985 was probably related to a decreased freshwater flow from the Cape Fear drainage basin. Salinity increases with decreased flow, probably allowing the flounder to immigrate further up the estu-ary. The increase ' in abundance over the five-year period probably re-sulted from high-flow conditions in 1983 and 1984 limiting flounder to areas such as Alligator Creek. The increase in abundarice of brown shrimp l
in Alligator Creek probably resulted from tne low freshwater flow increas-ing salinity anj suitable habitat for residence there in 1985. This increase in abundance resulted in the significant trend over the study period.
Blue crab significantly decreased in abundance from 1981 through 1985 (Table 4.3). This decrease clso appeared to be related to the high fresh-i water flow in 1983 and 1984. During these years the number of blue crab collected decreased until 1985 when a small increase was noticed. The increase in abundance in 1985, however, was not large enough to prevent an overall five-year decreasing trend. The remaining selected species (Atlantic menhaden, spot, croaker, and pink shrimp) did not significantly change in abundance.
4-6 g
I 4.3.5 Return Basin Evaluation The return bar,in has historically been heavily populated with estua-rine fish and invertebrates. The estuarine organisms enter the basin by natural immigration from the estuary and from the BSEP fish ret' urn system (figure 1.1.) . The CPUEs of spot, brown shrimp, Atlantic menhaden, blue crab, and pink shrimp were higher in the return basin than the mean CPUE I of any creek system (Table 4.2). The CPUEs were greater for bay anchovy, croaker, and flounder in the return basin than in the adjacent Walden Creek. The seasonal distributions of mos' populations in the return basin were similar to those in the estuary.
I Cumulative length-frequency distributions were tested with a Kolmogorov-Smirnov two-sample test to determine length differences between the retern basin and upper Walden Creek for spot, croaker, and brown Generally, larger ir.dividuals were collected in the upper Walotn I shrimp.
Creek areas than in the return basin. Spot, croaker, and brown shrimp appeared to use the return basin as a nursery as indicated by the large cumulative percent of smaller individuals in the basin (Figures 4.1, 4.2, and 4.3). Usually, the smaller individuals of a creek population occupy the headweters of the creek and migrate downstream as they mature. Analy-sis indicates that the return basin, which is located at the head of a small tributary creek, was indeed being utilized is a nursery by fish and f shrimp. Organisms that utilize the return basin either imn.igrate from the adjacent Walden Creek or are introduced alive via the fish return system. These species reside there when young and emigrate to the lower portions of Walden Creek as they mature. '
4.4 Summary and Conclusions The spatial distributions of most species were related to ti.e salinity of the particular areas in which they were collected. The center of abundance of the dominant species moved toward the upper estuary in 1985 as a result of low freshwater f'ow and increased salinity. As in the past, the seasonal distributions of the selected species were associated with the recruitment perioJs of the individual species. Spot, Atlantic I
4-7 1
I menhaden, croaker, striped mullet, flounder, and blue crabs were most abundant in late winter and early spring. White mullet, Atlantic silver-side, brown shrimp, mumichog, and bay anchovy were most abundant in late spring and summer. White and pink shrimp displayed peak recruitment in the fall.
The abundance of flounder arid brown shrimp significantly increased in Alligator c. reek from 1981 through 1985, while blue crab significantly decreased. The abundance of croaker, flounder, and brown shrimp in Walden Creek significantly incNased. No significant change was indicated for the remaining species.
The return bashi continued to be heavily utilized as a nursery area in 1985. Organisms resided in the basin as postlarvae and emigrated as they matured.
Dominant species exhibited seasonal distributions that were con-sistent with previous years. The association of any significant trends and spatial. distributions with freshwater flow indicates that the popula-tions of commercial and/or recreational species in the marshes of the Cape fear Estuary are dependent on natural phenom 2na and are not being impacted by the BSEF.
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4-8 I_
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Table 4.1 Total catch dnd percent total of the ten most abundant species collected in the high marsh study during 1985.
I Trawl Seine Specie _s Catch % Species Catch T
~
Spot 57,607 36.8 Grass shrimp 35,023 a7.9 Grass shrimp 54,624 34.8 Spot 11,270 15.4 Brown shrimp 11,624 7.4 Atlantic menhaden 6,212 8.5 Bay anchovy 10,915 7.0 White mullet 4,784 6.5 Atlantic menhaden 7,460 4.8 Mummichog 3,183 4.4 I Croaker Blue crab Pink shrimp 2,886 1,932 1,754 1.8 1.2 Atlantic silverside Bay anchovy Brown shrimp 3,011 2,904 4.1 4.0 1.1 2,482 3.4 I Flounder Hogchoker Other 1,177 944 5.797 0.8 0.6 3.7 Striped mullet Brown shrimp Other 940 648 2,633 1.3 0.9 3.6 I Total 156,720 100.0 Total 73,090 100.0 No of efforts 391 No. of efforts 102 I Table 4.2 Annual catch-per-unit-e' fort (CPUE) by creek system for 12 selected species in the high marsh study during 1985.
I Baldhead Walden Mott's Alligator Return Species Creek Creek Bay Creek Basin Spot 55 173 187 183 342 Brown shrimp 5 48 24 5 154 Bay anchovy- 8 14 135 44 17 Atlantic menhaden 2 26 28 7 104 White mullet GZ 13 66 i i I Mummichog Atlantic silverside Croaker 17 77 75 3 8 1 i i
i i
0 3 40 11 17
. Blue crab 3 6 5 3 21 Pink shrimp 2 5 8 1 28 Flounder 0 1 1 14 6 Striped mullet 6 18 3 i i i
iSeine samples were not collected in Alligator Creek or the return basin.
I 4-9 I-
Table 4.3 Results of time-series analysis of high marsh data by creek indicating trends in abundance from 1981 through 1985.
Alligator Creek Mott's Bay Walden Creek Baldhead Creek 2 2 2 Species Trend R Trend R Trend R Trend R2 Spot NS 0.77 NS 0.79 NS 0.90 NS 0.84 Brown shrimp +* 0.70 NS 0.70 +* 0.87 NS 0.82 Atlantic menhaden NS 0.74 NS 0.62 NS 0.89 NS 0.77 Croaker NS 0.50 NS 0.56 +** 0.74 ID Blue crab -* 0.59 NS 0.52 NS 0.50 NS 0.52 Striped mullet NA NS 0.43 NS 0.68 NS 0.36 Flounder +* 0.85 NS 0.72 +*** 0.79 ID
[ Pink shrimp NS 0.80 NS 0.72 NS 0.76 NS 0.68 White mullet NA' NS 0.64 NS 0.73 NS 0.86 NS P > 0.05 0.01 < P < 0.05
- 0.001 < P < 0.01
- P < 0.001 decreasing trend e increasing trend ID insufficient data NA analysis is not applicable because seine hauls were not made 2
R amount of variation explained by the time-series model M - . M M M WE M -
M M M M M M M
I.
lI .
I 100' =- ' " - -
80' /
? l c!' 60 /'
$O 40' /
/
3 ",0 '
I U E
d 0;
/
. , r-
/
0 20 40 60 80 100 120 140 160 150 Length (mm)
- 51 --- 2 4 - 2 7 Figure 4.1 Cumulative length-frequency analysis of spot collected by trawlin I upper Walden Creek (Stations 24 27) and the return basin (Station 51) in the high marsh study during 1985.
I I '
100' E 80' /
f Q b.oO o,.
,_,_, r '
l 9 e .
3o 40' l l [ 20'
/
l 3 u. ,.
I 0 20 40 60 80 100 120 140 160 150 Lengtn (mm)
- 51 -- 24-27 Figure 4.2 Cumulative length-frequency analysis of croaker collected by trawl '
la upper Walden Creek (Stations 24-27) and the return basin (Station 51)
I in the high marsi, study during 1985.
I g .1.
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~
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100' , --
- /
80' ,'
s 60' '
./
e i 3 40' /
2 /
y 20' ,-
- s ,'
0;- , , , , , , , ,
0 20 40 60 80 100 120 140 160 18C Length (mm)
- 51 -- 24-27 E B
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I Figure 4.3 Cu:nulative lengtlefrequency Snalysis of brown shrimp collected by trawl in upper Walden Creek (Stations 24 27) and the return basin (Station 51)in the high marsh study during 1985.
I 4-12
, = -- -
I 5.0 NEKTON 5.1 Introduction Various species of fish and shellfish spend a portion of their fit - t year in the CFE before migrating to the ocean as juvenile and adult mem-bers of the nekton community. Operation of the BSEP and subsequent I removal of estuarine water for cooling purposes results in the potential impingement of these nektonic organisms. A percentage of the organisms that were impinged were returned to the estuary alive via the fish return system. The objective of the nekton program was to determine if operation of the BSEP had an adverse effect on these populations of estuarine nekton. To accomplish this objective, the nekton program monitored changes in the species composition, spatial distribution, and relative yearly abundances of the n+ .onic organisms utilizing the CFE. Selected stations were also utilized to investigate the effectiveness of the fish I diversion structure.
5.2 Methods Fourteen stations in the CFE were sampled with a 6.4-m semiballoon otter trawl. These stations extended from the freshsater drainage canal, approximately 3.4 km west of Southport, to Alligator Creek, approximately 0.6 km east of the Brunswick River (Figure 1.3). Detailed descriptions of sampling stations and methodology can be found in CP&L (1994).
I Time-series analysis was employed to examine long-term trends in yearly abundance of selected species (CP&L 1985a). Bay anchovy Anchoa mitchilli, Atlantic menhaden Drevoortia tyrannus, spot f.eiostomus xanthurus, croaker Micropogonias undulatus, and weakfish Cynoscion regalis were placed into either the young-of-year (Y0Y) or juvenile / adult (J/A) size classes by examination of their respective length-frequency distributions (Lagler 1952; Everhart and Youngs 1981; Ambrose 1983). Size classes for blue crab Callinectes spp. and pendeid shrimp Penceus spp. were combined, respec-I tively. The time-series analysis was performed on the lower river (Sta-tions 1, 4, 7, and 8 combined) from 1979 through 1985.
5-1
I An evaluation of the etfectiveness of the fish diversion structure (completed during Novcmber 1982) was based on catches at Stations 5, 5, and 13 (inside the structure) as compared to the catches at Station 4 (outside the structure). An analysis of variance was performed to examine spatial variability among Stations 4, 5, and 6 for the years 1979 through 1985. A date effect was defined as the period before the fish diversion structure was operational (preoperational) and the period af ter its com-pletion (postoperational). A significant station-by-date interaction would indicate a change in the abundance pattern insid? to outside the fish diversion structure over time. A time-series analysis was performed on the combined catches at stations inside the fish diversion structure (5, 6, and 13) from 1981 through 1985 to determine if there was a significant trend in catch. A Kolmogelov-Smirnov two-sample test of l
cumulative length-frequency distributtuns was employed to investigate size differences of the fish inside and outside of the fish divarsion structure. Selected spec Qs used for thL fish diversion structure evaluation were J/A Atlantic menhaden, spot, and croaker (CP&L 1984, 1985a).
A log g (CPUE+1) transformation was used in all analyses. Signifi-cance war determined at the 0.05 level.
5.3 Results and Discussion E E
5.3.1- Total Organisms Bay anchovy, spot, grass shrimp Palaemonetes spp. , and brown si. +p Penaeus aztecus comprised 89.8% of the total catch (Table 5.1). Croa'a- -
brief squid Lolliguncula brevis, and blue crab Callinectes sapidus ranked next in abundance and comprised 6.4% of the total catch. These species have historically been the dominant nekton species collected in the CFE (8 irk-head et al. 1979; Schwartz et al. 1979; CP&L 1982, 1983, 1984, 1985a).
The catch of bay anchovy, grass shrimp, brown shrimp, and brief squid increased from 1984 to 1985, while the spot catch remained approximately the same. Croaker, pink shrimp Penaeus duorarum, weakfish, blue crab, and Atlantic menhaden catches decreased from 1984 (CP&L 1985a).
5-2
I
'I 5.3.2 Spatial Distribution I The bay anchovy was collected estuary-wide but peak catches occurred at the lower river stations (Table 5.2). Spot and Atlantic menhaden were also most abundant at the lower river stations. Croaker, pink shrimp, and weakfish were most abundant in the Snow's Cut area (Stations 10 and 14).
I The greatest abundance of brown shrimp occurred at Snow's Cut and Alliga-tor Creek (Station 12). Blue crab were distributed over the entire estu-ary. Except for brown shrimp and Atlantic menhaden, these distributions were similar to these of previous years (Schwartz et al.1979; CP&L 1980, 1982, 1983, 1984, and 1985a). The distribution of brown shrimp exhibited a shift from the lower and middle estuarine areas to the middle and upper estuarine areas. This shif t was most likely due to reduced freshwater flow during the spring recruitment period. Data supplied by the United States Geological Survey indicate reduced flows in 1985 from the two pre-I vious years. The apparent shif t in abundance of Atlantic menhaden f rom the middle estuarine areas was the result of an extremely low catch in the Snow's Cut area during 1985 which influenced the overall annual Atlantic menhaden catch, in previous years the catches in this area were rela-l :ively large (CP&L 1982, 1983, 1984, and 1985a).
In addition to brown shrimp, seve other species, including blue -
crab, YOY bay anchovy, YOY spot, and YOY croaker, were abundant in the I upoer estuary.
organisms to this area.
Operation of the BSEP did not inhibit movement of these 5.3.3 Time-Series Analysis Resuits of the time-series analysis at the lower river stations (1, 4, 7,, and 8) indicate that four groups of organisms exhibited nonsignifi-cant or increasing trends in abundance since 1979 (Table 5.3). These were the YOY and J/A bay anchovy, J/A croaker, and J/A Atlantic menhaden.
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5-3 I
I!
Organisms that exhibited a decreasing trend in catch since 1979 were YOY and J/A spot, YOY croaker, brown shrimp, blue crab, weakfish, pink shrimp, and white shrimp Penaeus sotiferus.
This trend for J/A spot was the result of relatively higher catches during 1981 through 1983 and lower catches during 1984 end 1985 (CP&L 1985a). These fluctuations are typical of those which occur in natural populations (Birkhead et al. 1979).
Decreases in the catch of brown shrimp at the lower river stations may have been related to variations in river flow and salinity during this species' recruitment period. Brown shrimp were more abundant upriver during 1985 (Section 5.3.2) and an actual increase in catch occurred dur-ing 1985 when all stations are considered (Table 5.1; CP&L 1985a). l The catch of YOY spot and croaker decreased in 1985 at the lower river stations. River flow during the winter-spring recruitment period l
for these two species was lower than in 1983 and 1984. This may have affected the distribution of these two species within the CFE thereby influencing the catch at the lower river stations. Copeland et al. (1979) concluded that var'ations in salinity due to changes in river flow af-fected the distribution and abundance of postlarval spot and croaker in E
the CFE. g July through September has historically been the period of highest abundance for weakfish, pink shrimp, and white shrimp collected with the nekton trawl (CP&L 1980, 1982, 1983, 1984, 1985a). The decreased catch in 1985 was probably due to lowered salinity during August (Figure 2.1).
5.3.4 Diversion Structure Evaluation Rasults of the analysis of variance indicated that a significant statien-by-date interaction occurred for J/A spot inferring a difference i in the spatial distr ibution of J/A spot over time due to the presence of the fish diversion structure (Table 5.4), During the preoperational peri-od, the catch was greater inside the f a dieersion structure, while the 5-4
I catch was greater outside during the postoperational period (Table 5.5).
The data indicates that the presence of the fish diversion structure had an effect on J/A croaker though the station-by-date interaction was not significant (P = 0.09). The catches increased at Station 4 but decreased at Stations 5 and 6 during the postoperational period, thus demonstrating the effectiveness of the fish diversion structure at inhibiting movement of J/A croaker into the intake canal. A significant station-by-date interaction did not occur for J/A Atlantic menhaden (Table 5.5). The catch outside of the fish diversion structure was significantly greater I for the entire study period. Past reports reveal that the temporary fish diversion structure remained effective during the period of abundance of J/A Atlantic menhaden for the years 1979 through 1981 (CP&L 1980, 1982, 1983). The temporary and permanent fish diversion s+.ructures have been successf ul at excluding J/A Atlantic menhaden from inside the intake canal for the entire time period under analysis.
I The time-series analysis indicated a significant decreasing trend in I the catch of J/A spot, croaker, and Atlantic menhaden inside the intake canal for the years 1979 through 190 (Figures 5.1 through 5.3). An in-crease in the catch of spot and croaker du ri n') 1985 was probably the result of two factors. First, the bottom screen panels of the fish diversion structure were damaged during January and again in the April to May period. This allowed movement of some J/A spot and croaker into the intake canal. Second, the 1985 spot and croaker catch may also have been affected by the presence of resident individuals recruited during the spring of 1984.
I Results of tha Kolmogorov-Smirnov two-sample test indicated a signif-icant difference '=.ueen the cumulative length-frequency distribution of spot inside and outside the fish diversion structure. The fish diversion structure excluded most spot greater than 30 mm, and spot outside the structure were larger than those inside (Figure 5.4).
fhe fish diversion structure was effective in excluding croaker greater than 45 mm (Figure 5.5). The i;wo cumulative length-frequency dis-tributions were significantly different and there was a greater percentage 5-5
I of larger croaker outsid3 the fish diversion structure up to approximately 90 m. The larger percentage of croaker greatt.r than 100 mm present ,
inside the intake canal may represent a resident population or fish that moved inside the fish diversion strdcture whc1 . r :a were damaged.
I
~
The cumulative length frequency distrh . o r., of Atlantic menhaden inside and outside of the intake canal were not significantly dif ferent.
tow numbers collected (38 outside vs 26 inside) most likely contributed to this result.
5.4 Nmmary and Conclusions The dominant species collected in the nekton program during 1985 were similar to what has been collet ted since 1979. Changes in spatial dis-tribution and abundcace did occur for soc.e species and were the result of cycles in abundance of many species and environmental variatior.s, such as fluctuations in salinity due to changing freshwater flow.
Operation of the BSEP has not adversely affected populations of nek-tonic organisms residing in the CFE. CP'nges in trends in distribution and relative abundance from year to year of these nektonic organis.zs was not associated with operation of the BSEP. Further, the fish diversion 5
structure has been successful at excluding large organisms from the intake g canal.
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5-6 -l
, -,.~ r_ _ . , .
E I
Table 5.1 Total number, percent total nuPber, and annuc1 catch-per-unit-effort (CP'IE) of the ten most abundant s) .; collected in the nekton study during 1985.
Percent Total of Species number total CPUE Bay anchovy 71,573 52.0 150.4 Spot 30,373 22.1 63.8
[- Grass shrimp 12,911 9.4 27.1 Brown shrimp G.666 6.3 18.2 I 11.2 Croaker 5.337 3 . .,
Brief squid 2,057 1.5 4.3 l Connon blue crab 1,389 1.0 2.9 i Pink shrimp 866 0.6 1.8 Weakfish 779 0.6 1.6 l Atlantic menhaden 666 0.5 1.4 I Total (ten most abundant) 134,617 97.9 282.7 Other organisms 2,982 2.1 6.4 Total organisms 137,599 100.0 289.1 I
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Table 5.2 Annual catch-per-unit-effort (C"UE) by station of the dominant organisms collected in the nekton study during 1985.
Station Downriver Uprher Species 1 2 4 7 8 10 14 11 15 16 12 Bay anchovy YOY 351.0 74.5 194.5 54.9 29.3 44.4 90.7 81.7 30.0 33.2 9.9 J/A 76.1 56.4 54.1 5.0 24.5 20.7 7.5 25.9 23.4 14.2 1.0 Spot Y9Y 42.4 0.6 70.3 0.5 9.8 3.8 5.3 9.4 2.2 5.7 4.8 J/A 3.2 17.1 8.0 4.5 9.7 1.2 7.4 0.4 0.1 0.7 0.1 Brown shrimp 3.3 0.0 3.4 3.0 0.5 14.2 42.5 5.1 0.7 10.1 40.1 c,
6, Crocker ;
YOY 2.3 1.0 7.8 0.6 0.2 11.3 27.2 8.9 1.4 4.S 3.9 J/A 1.6 2.1 S.5 1.6 0.2 13.6 19.5 1.8 0.4 0.7 U.O Common blue crab 0.8 3.4 5.4 2.5 2.7 2.3 4.7 2.2 1.2 2.2 2.4 r
Pink shrimp 0.9 0.2 1.8 1.5 0.8 4.5 3.4 0.3 0.0 0.3 1.1 Weakfish 1.3 0.0 0.9 0.0 0.0 4. 5 6.2 0.7 0.0 0.5 0.8 Atlantic menhaden 6.3 1.4 0.8 0.5 0.c 0.2 0.4 0.3 0.0 1.7 0.3 i I
J/A = Juvenile / adult YOY = Young-of-year i M M M M M M M M M M M M M M M M M M M
. . . _ - _. ._. - . - - _ - - .- - . - . - .- -.-. - . . . ~ . - - - . - - . . - .
I 1 l Tabic 5.3 Results of ti.ne. series analysis of nekton lower river data indicating trends in at:undance from 1979 through 1985.
Species Trend R 2
Bay anchovy J/A +* 0.84 YOY +*** 0.76 Spot J/A **
0.79 YOY
- 0.64 Brown shrimp ***
O.86 Croaker J/A NS 0.82
- YOY 0.87 i
Blue crab ***
0.59 Pink shrimp *** 0.76 Weakfish ***
0.78 Atlantic menhaden J/A NS 0.77 White shrimp ***
0.78 L
NS P > d.05 0.01 < P 5 0.05 0.001 < P $ 0.01
- P < 0.001 I J/A = Juvenile / adult Y0Y = Young-of-year
- = decreasing trend
+ = increasing trend R2 = amount of variation explained by the model lI 5-9 I:
. _ _ _ _ . - , ~ . - - . - - - - - - ,
I Table 5.4 Results of analysis of variance and Duncan's multiple range test for selected species utilized in the evaluation of the DSEP fish diversion structure for the years 1979 through 1985.
Duncan's multiple g Species Source F-value range test g Spot Station 3.17*
(juvenile / adult) Date Station-by-date 81.16'**
4.39* lI)
Croaker Station 17.75*** 5 4 6 l (Juvenile / adult) Date 2.56 HS u Station-by-date 2.37 NS
. Atlantic menhaden Station 8.15*** 4 5.6 Date 21.49*** Pre F5ii
~ '
(juvenile / adult) Station-by-date 0.51 NS Station 4 is outside the fisl. diversion structure Stations 5 and 6 are inside the 'ish diversion structure Pre = preoperational Post = postoperational Underscores indicate similarity and values decrease from left to right.
NS P > 0.05 5 .
- l 0.01 < P $ 0.05 l 0.001 < P 5 0.01 -
P 1 0.001 I
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5-10 I_
._m-__- _.__-______-
I Table 5.5 Date-by-station interaction for the mean log (CPUE+1) of juve-nile / adult spot, crooker, and Atlantic meniiaden collected in the intake canal during the preoperational and postoperational periods of tiie fish diversion structure, 1979 through 1985. ,
I Station Species. Date 4 5 6~
Spot Preoperational 1.411.70 1.26 (juvenile / adult) Postoperational 0.940.43 0.42 Croaker Preoperational 0.470.78 0.37 (juvenile /aduit) Postoperational 0.560.62 0.14 Atlantic menhaden Preoperational 0.990.78 0.55 (juvenile / adult) Postoperational 0.6?O.21 0.17 I Station 1 is outside the fish diversion structure l Stations 5 and 6 are inside the fish diversion structure I
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5-11
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_,..,....o, Structut Completed I
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o g3 a , i I l ., . *' , l \ ,1 l
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81 82 S3 84 65 SF Yeor
- OBSERVED -- PREDICTED +~ YEAR LEVEL Figure 5.1 Results of time series analysis for juvenile / adult spot collected in the intake canal (Stations 5,6, and 13) by the nekton trawl from 1981 through 1985, I
-4'
$ - Fish Diver:6on
, Structure Completed ,
? f S .5 v
h l h \' / s < s j 1- - i d' *
,,t s ,
I ' \'Js3J(4f? t,/A u, r , , , 7 , , , , , ., , , ,,, 51 $2 83 54 55 66 Year OBSERVED -- FREDlCTED .n YEAR LEVEL Figure 5.2 Results of time-series analysis forjuvenile/ adult croaker collected in the intake canal (Stations 5,6, and 13) by the nekton trawl from 1981 through 1985. I, 5-12 l er- - - . . - , . . , - ,,, , , _ , . . . _ _ . ~ y .. .__.m. _,_____m _ ____,.__,.,m_
I I I 5' a n - n.n oi..,i,on g n svuw. cow.<.a t I w4 D a. I O v
$3:
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l h ~ I I I I I I I i l I i I I i i i l i i i i 1 81 82 83 84 85 S6 l Year
- OB$fRVED --- FREDICIED I m YEAR LEVEL I
Figure 5,3 Results of time-series analysis forjuvenil / adult Atlantic menhaden collected in the intake canal (Stations 5,6, and 13) by the nekton trawl from 1981 through 1985. I 5-13 _ . _ _ _ . _ _ - _ _ . _ um m=i
100' .... ~- -------- y - --- I E 80 j E' u e ; E 60' ! I2 40' l l
@ 20' 0' -
0 20 40 60 80 100 120 1 10 160 50 Length (mm) <
-4 --- 5,6,13 l
Figure 5.4 Cumulative length-frequency analysis of spot collected by the nekton trawlinside (Stations 5,6, an<113) and outside (Station 4) the fish a diversion structure during 1985, g 100' _ g ..... - ---- 5 80' u u .s
/M
E 60' -9 - e f~~ s
$ 40' /
2 i l g 20' ,e ' E d .- ,- i. ,, , , .,. - g
> 20 40 60 50 100 120 140 160 180 E Length (mm)
-- 5,6,13 I
I Figure 5,5 Cinnulative length-frequency analysis or croaker collected by the nekton trr viinside (Stations 5,6, and 13) and outside (Station 4) ihe fish diversion structure during 1985, I 5-14 4
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l l 6.0 ENTRAlhMENT 6.1 Introduction Studies to determine the species composition, seasonality, and abun-I dance of entrained larval and postlarval fish, penaeid shrimp, and portun-id crabs ct the BSEP have been conducted by CP&L as part of its long-term monitoring program since September 1978. Prior to that, entrainment stud-les were condacted by North Carolina State University (NCSU) from May 1974 through August 1978. In addition, the results of studies conducted since July 1983 were used to determine the effectiveness of flow minimization and fine-mesh screens on reducing entrainment. 6.2 Methods The collection gear, sampling methods, and sample processing have re-mained unchanged since 1982 (CP&L 1983). ror analysis purposes, a larval fish year began in September and continued through August of the following I calendar year. The 1985 larval year repo-ts data collect 1d from September 1984 through August 1985. I The density of organisms entrained was calculated the same way as river larval fish densities (Section 3.2.1). The densities of all samples collected per sampling date were avtraged to obtain a mean number per 1000 3 m per day. For the time-series analysis, sample densities were trans-formed to loge (density + 1). These transformed densities were then used to compute an average monthly density which was used in the analysis. Three species of postlarval penaeld shrimp were collected in entrain-ment, but because of the difficulty in accurately identifying them to species, they were combined and reported as Penaeus spp, postlarvae. How-ever, those that occurred from late winter to spring were brown shrimp Penaeus aztecus and those that occurred from late spring to f all were a ( g mixture of pink and white shrimp (P. duorarum and P. setiferus, respective-a ly) (Copeland et al. 1979). 6-1 I _ _ _ _ . -- E
6.3 Results and Discussiun 6.3.1 Dominant Species In 1985 the dominant organism entrained was Gobiosoma spp. which com-prised 33% of the mean density of all organisms entrained. Atherinidae (21%) was second mort abundant end Anchon spp. (12%) was third. The other entrained species, in decreasing order of abundance, were bay anchovy Anchoa mitchlllt, croaker AfIcropogonias ur.ctulatus, spot Lelostomus xanthurus, portunid megalops Fenaeus spp. postlarvae, Blenniidae, and naked goby Gobiosoma bosci (Table 6.1). 6.3.2 Seasonality and Abundence The seasonality or periods of abundar.ce for the selected species i analy.ed was similar to those seen in previous years and corresponded to the seasonality found in the river larval fish program (Section 3.0; Tables 6.2 ar.d 6.3). Since the installation of fine-mesh screens and the initiation of a strict flow minimization regime in July 1983, the peaks of abundance in entrainment, as reported by density and number of organisms g entrained, may not correspond to pecks observed in the river larval fish 5 program. Peaks in entrainrient can be induced by operation of nonfine-mesh screens or an increase in flow of cooling wate- as determined by plant E g operational needs. Croaker had a peak density of approximately 1040 in early December, I flounder Paralichthys spp, had a peak density of 11 in early Occember. At-lantic menhaden Brevoortia tyrannus peaked at 151 in early April, mullet Afugil ecpolus and f.f. curema at approximately 40 in early January, spot at g almost 624 in mid-Mart 5, anchovy Anchoa spp. ($ 12 mm) A. hepsetus and A. m mitchilli at about 1597 in early June, Gobionellus spp, at 65 in early December, Gobiosoma spp. at aoout 4115 in mid-June, and seatrout Cynoscion nebulosus and C. regalls at almost 28 in early June. Pink and white shrir:p combined had a peak abundance of 412 in early August and brown shrimp peaked at about 71 in late March (Table 6.2). I 6-2 g')
1 1
I 6.3.3 Number Entrained Entrainment rates were computed by multiplying the mean density per day by the mean flew per day. The mean daily flow of cooling water through the DSEP ranged from 1.5 x 106 m 3 in early November to 3.7 x 10 6 I m3 during October (Table 6.3). I The daily rate of total fish entrained ranged f rom 2.1 x 10 4 7 in early May to 3.6 x 10 in aiid-November. Croaker were entrained at a maximum 6 rate of about 3.1 x 10 in early December, flour. der at 3.3 x 10 4 in early December, menhaden at 3.6 x 105 in early April, mullet at approximately 6 1.2 x 10 5 in early January, spot at 1.5 x 10 in mid-March, anchovy at al-most 3.6 x 10 6 in early June, Coblonelius spp. at approximately 2.0 x 10 5 in early October, Cobiosoma spp. at 9.2 x 106 in mid-June, and seatrout at 6.2 x 10 4 in early June. Pink and white shrimp canbined had a maximum en-trainment rate of 9.2 x 10 5 in early August and b own shrimp of 2.1 x 10 5 I in late March (Table 6.3). 6.3.4 Flow Minimization in June 1981, plant operations eracted a pe uial flow minimization regime whereby the amount of water withdrawn from the estuary for cooling purposes was reduced (CP&L 1985a). In July 1983, a mare drastic flow-reduction schedule was employed. This schedule called for a maximum flow of 915 cuoic feet per second (cfs) (25.9 cubic meters per second (cmsl) during three-pump operation and a maximum allowable flow of 605 cfs (17.1 cms) during two-pump operation. The delineation between two-pump and three-pump operation was dependent on intake water temperature. At water temperatures 65'F (18.3*C) and above (approximately the end of April), three-purrp operation was allowed--below that (approximately the end of November) only two-pump operation was used. A further restriction re-quired that the two traveling screens on each unit equipped with fine mesh must be opera +ed at all times. To determine reductions in entrainment due to flow minimization, a comparison using observed entrainment numbers was made between historical I 6-3 I
. - . .~~~ . - __
flows (pre-January 1981; Hogarth and Nichols 1981) and the observed flows. There was an approximate 28% reduction in the mean total number of organisms entrained for the time periods encompassing three-pump operation and a maximum flow of 915 cfs. For tne time periods encompassing twn-pump operation and a maximum allowable flow of 605 cfs, the percent reduction was about 46% (CP&L 1985a). 6.3.5 Time. Series Analysis To determine the effectiveness of fine-mesh screens in reducing en-trainment, a time-series analysis was performed on the monthly mean densi-ties of selected species. The data analyzed was collected from September 1980 through August 1985. This time period included three years of opera-tion pr1or to fine-mesh screen installetion and two years of operation with fine-mesh screens. Species selected had seasonalities coinciding with the Nove,aber to April time period--the approxirate period of two-Dump operation when both traveling screens were equipped with fine mesh. The results show significantly decreasing trends in densities of bay anchovy, portunid megalops, spot, croaker, and Penceus spp. pcstlarvae (Table 6.4). In comparison, the results of time-series analyses performed on the lower river stations in the river larval fish program shcw no sig-nificant trend in densities for spot and croaker and a significantly increasing trend for Penaeus spp. postlarvae (Table 3.2). This ir.dicates that fine-mesh screens are ef?ective in significantly reducing the en-trainment densities of these organisms. 6.4 Summary and Conclusions In 1985, studies were conducted to determine the species composition, seasonality, and abundance of entrained larval and postlarval fish. penacid shrimp,-and portunid crabs. The results were also used to deter-mine the ef fectiveness of flow minimization and fine-mesh sci eens on re-ducing entrainment. 6-4 g
I l The dominant organism entrained in 1985 was GobIosoma spp. sonalities of all species repo*ted remained the sane as in previous years. The sea-I Estimates of the historical mean numbet entrained per day, based on observed values, were used to determine the reduction in entrninment due I to f .. minimization. The percent reduction ranged from 28% to 46%, de-pending on which flow reduction regime was in effect. To determine reduction in density of organisms entrained, a time- < series analysis was performed on the yearly mean densities of selected species entrained fron Septembt" 1980 through August 1985. T..e results showed significantly decreasing trends in densities of bay anchovy, portun: . megalops, spot, croaker, and i enaeus spp. postlarvae. S I I I I I I I , I I I I 6-5
Table 6.1 Mean density and percent total of fish, penaeid shrimp, and portunid crabs entrained, September 1978 through August 1985. Septernber 1978 - September 1983 - September 1984 - August 1983 August 1985 August 1985 Species Density Percent Density Percent Density Percent Gobiosoma spp. 373 22.0 283 30.0 426 33.1 Atherinidae 61 3.6 143 15.1 270 21.0 Anchoa sr 191 11.3 124 13.2 159 12.4 Bay anch. 177 10.5 61 6.5 73 6.2 Croaker 170 10.0 77 8.2 56 4.4 Spot 164 9.7 72 7.6 50 3.9 m i Portunid megalops 235 13.9 39 4.1 45 3.5 Penceus spp. postlarvae 145 8.6 31 3.3 40 3.1 Blenniidae 13 0.8 21 2.2 32 2.5 Naked goby 4 0.2 15 1.6 26 2.0 Other taxa 159 9.4 76 8.2 101 7.9 Total 1692 100.0 942 100.0 128'1 100.0 i M M M M M M N M M M
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lI l Table 0.4 Results of time-series analysis of entrainment data indicating trends in density from September 1980 through August 1985. Species
+/_ R2 I Bay anchc.y 0.90 l Portunid megalops ***
0.93 Spot ** 0.97 Croaker
- 0.92 Penaeus spp. postlarvae ***
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i 7.0 SURVIVAL S100105 4 7.1 Introduction Survival studies were initiated in early 1984 to determine i. hat per-4 centage of organisms impinged on the traveling screens and transported down the fish return sluiceway are returned to the Cf E alive. Specift-cally, these studies examined survival by species and size class during two intake traveling screen rotation speeds. Emphasis during 1985 was directed towards those species and size classes that were neither examined nor exhibited fluctuating survival percentages during 19.84. 7.2 Methods 7.2.1 Collection impinged organisms were washed from the traveling screens into the fiberglass return sluiceway, Collections were made at the end of the 1.4-km sluiceway where it empties into the 3.2-nectare return basin (figurc 1.1). A larval table similar to one used by McGroddy and Wyman (1977) and described in CP&L (1985a) was utilized for the collection of the smallest size classes. The larger juvenile and adult organisms were collected with a 9.5-mm bar-mesh net fitted on a frame that conformed to the shape of the sluiceway. I The gear and sampling methods for collection of control organisms were unchanged from the last half of 1964, for collection of the smallest size classes, a 1-m diameter 1-mm mesh net with an oversized " plankton bucket" was used. I Tne smaller juveniles were collected with either a 3.2-m two-seam trawl or a 6.4-m semiballoon otter trawl. for further discussion of gears and methodologies, refer to CP&L (1985a). 7.2.2 .itocking and Monitoring The stncking and monitoring of organisms remained unchanged for 1985. Targeted organisms were sorted by species and size class and the 7-1
live and dead organisms sort.ed and counted. Live organisms were then stocked in tanks and the 96-hour holding period initiated. Organisms were g monitored hourly and any dead organisms were removed and measured. Water g quality phrameters (temperature and salinity) were periodically checked. Af ter 96 hours, the tanks were drained and all live and dead organisms were counted and measured. 7.2.3 Definitions, Calculations, and Data Analysis Those organisms that died before reaching the laboratory accounted for initial mortality, while latent mortality consisted of those organisms g that died after stocking. Total mortality was the summation of both, for E reporting purposes, a percent total mortality and, consequently, the percent survival were calculated using the following formulae: Initial mortality + latent mortality Percent total mortality = x 100 Number of organisms collected Percent survival = 100 - Percent total mortality Occasionally more live organisms were collected than could be stocked. In these cases, the latent mortality percentages were applied to all live organisms prior to calculation of percent total mortality. The intake traveling screens rotate approximately 75 cm per minute on slow-screen retation and 2.5 to 4 times faster during fast-screen l rotation. When collections for a particular species were made during both screen speeds, an analysis of variance (ANOVA) was performed to examine the effect of screen speed on survival. The general linear models procedure of the Statistical Analysis System was used to examine date, screen speed, and their interaction as f actors. Species analyzed were croaker Aficropogonias undulatus and spot Lelostomus xanthurus. For al1 statistical analysis, a sigaificance level of 0.05 was used. Prior to any analysis, an arc sine square root transformation was made to achieve uniform variance of the percentage data. I 7-2
I 7.3 Results and Discussion , in assessing any stress-related effects on larval and postlarval organisms, special handling methods and/or acclimation periods are usually required (Hoss et al. 1974, 197/). Collection, handling, holding and/or natural mertality of ten result in a reduced survival prior to and during experimental testing. As a measure of this reduced survival, control organisms were collected and held. The survival percentages obtained from those controls are presented along with the experimental percentages. No adjustments were made to experimental data for control mortality, even though the latter was not plant-induced. 7.3.1 Total Organisms Twenty survival studies were conducted during 1985 resulting in the g collection of over 10,000 organisms comprising 13 different taxa (Table 7.1). Nine of the taxa were contidered commercially and/or re-creationally important while three others had been documented as important forage fish (i.e., bay anchovy Anchon init chfill, goby Gobildae, and silverside Atherinidae) (Schwartz et al. 1980: Darnell 1961). Included among those nine taxa were members of the drum Sclaenidae, mullet Mugilidae, flounder Bothidae, shrimp Penacidae and crab Portunidae families. 7.3.2 Spesies Accounts Croaker Survival of croaker was examined on nine different dates (Table 7.1). Over 2000 experimental croaker were collected during 1985 with an additional 782 collected from the intake canal for use as controls. On all dates the mean standard length ranged between 12 and 14 mm, except on January 7 when a group with a mean length of 29 mm was held in addition to a group at 13 mm (Table 7.2). Percent survival for the smaller size class during f ast-screen rotation ranged f rom 22.2% on April 15 to 60.3% cn December 9. Overall, the results during fast-screen rotation for the
,a g
I i smaller size class indicated a consistent survival of approximately 42%. The larger size class collected during f ast-screen rotation displayed g survival at approximately 51%. 3 Analysis of variance indicated a significantly lower percent survival during slow-screen rotation than during fast-screen rotation (Table 7.3). On those dates when organisms were collected during slow-screen rotation, survival ranged between a low of 12.4% on January 7 to a high of 36.0% on November 18. Croaker collected as controls exhibited a high average survival of approximately 83%, even though on January 23 survival of control croaker was only 38.6%. A possible explanation was low ambient water temperature causing physical stress prior to collection of both experimental and control croaker. One week earlier water temperature in nearby Walden Creek had dropped to 1.3'C (Section 2.0). l Spot Over 2500 spot were collected on eight different dates during 1985 (Table 7.1). Alraost 1200 spot were collected during f ast-screen rotation and exhibited an overall survival of 24.6%. Survival ranged from a low of 13.3% on February 1 with 16-mm fish to a high of 41.2% on March 18 with fish averaging 20 mm in length. Almost 1300 small spot were collected during slow screen rotation from five dates. Survival ranged from a low of 0.7% on March 4 to a high of 12.6% two weeks later (Table 7.4). Analysis of variance again indicated a significantly lower survival percentage for the srnaller sizes (14 20 mm) during slow-screen rotation as compared to those collected during fast-screen rotation (Table 7.3). . l.arger juvenile spot (68 mm) were collected on only one date and only during slow-screen rotation. This iarger size class exhibited a survival near 77%. I 7-4 1
I The overall average control survival for spot was approximately 80%. However, this percent is reduced since the unusually low temper-atures on January 23 possibly reduced survival for control as well as for experimental spot collected on that date. I Penacid Shrimp I Postlarval penacid shrimp (12 mm) collected during the spring exhibited high stryival regardless of screen speed (Table 7.5). I fast-screen rotation. Penaeus spp. postlarvae averaged over 90% sur vival During compared to 80% survival for those collected during slow-screen rotation. Brown shrimp Penaeus aztecus (87 mm) were collected during the summer months (June through August) and, like the postlarvae, exhibited high survival. A total of 159 brown shrimp were collected from three different daces 1 of these. 152 survived the 96-hour holding period. Overall, survival was 92% during fast-screen rotation and 96% during slow-screen rotation (Table 7.5). Due to the difficulty of identifying young penacid shrimp (48 mm) to I species without additional handling, pink Per.aeus duorarum and white shrimp P. setiferus were combined during stocking and analyzed as one group. Percent survival from the one collection date as approximately 76% for experimental organisms (Table 7.5). Another member of the penacid family extmined was the hardback shrimp Trachypeneus constrictus. Collected on three dates, these shrimp exhibited survival of 78.8% during fast-screen rotation compared to 59.3% during slow-screen rotation (Table 7.5). These shrimp ranged from 8 to 45 mm in I total length. Control organisms for the four taxa never exhibited a survival under 80%. Blue Crab I Callinectes sapidus and C. simills were combined as Callinectes spp. during stocking and' for analysis. Juventie stages (15 mm) of there
I commercially important species were held on three dates during September and October and exhibited survival values of 95.5, 90.9, and 95.0% (Table 7.5). Because collections were made during both screen speeds and values were similar, it was obvious that the impingement process had little, if any, effect on juvenile blue crab. Control data for blue crab ranged f roro 89.0% to 96.9% (Tab
- 7.5).
Striped Mullet The survival of two dif ferent age classes of striped mullet Alugil cephalus was examined. Mean survival of postlarval mullet (25 mm) g collected during f ast-screen rotation was 67.6%, while control mullet of 5 this size exhibited excellent survival over 95.0%. Survival of juvenile / adult striped mullet (150 mm) was 92.0% for experimental and 100% for controls (Table 7.6). Flounder Results from the only survival study conducted on flounder Paralichthys spp. indicated that postlarvac survived the impingement process extremely well, Collected during fast-screen rotation, 13-mm flounder exhibited over 90% survival. Control flounder exhibited 95% survival (Table 7.6). $. y - Bay Anchovy Bay anchovy was collected on only one date and only during f ast-screen rotation. Limited survival was documented at 5.6%. This was, however, an improvement over 1984 when no bay anchovy survived the 96-hour g period. m Miscellaneous Species Silverside, goby, and planchead filefish Afonocanthus hispidus were also collected and examined for survival during 1985. The members from the goby 'and silverside famil es had no survival, which probably resulted 7-6 T
I from the small sizes that were collected (mean length of 6 and 8 mm , respectively). Survival of the small filefish (mean length of 16 mm) was l approximately 70%. (Table 7.6). No controls were collected for these three species 7.3.3 Two-Year Averages I Since the initiation of the survival study program in 1984, the percent survival of 18 taxa has been estimated. All organisms collected over the two years have been used in the calculations (Tables 7.7, 7.8, and 7.9). The two-year average of most species has basically remained unchanged from 1984. However, the hardback shrimp and the bay anchovy have shown noticeable increases in survival. Survival of the hardback shrimp increased from 22.0% during slow-screen rotation in 1984 to a two-year mean of 45.1%. Bay anchovy did show minimal survival on one date However, this only slightly increased the two-I over the past two years. year average when total anchovy collections were used in the calculations. 7.4 Summary and Conclusion The survival of over 10,000 organisms of 13 taxa was examined during 1985. Croaker and spot survival was significantly higher during f ast-screen rotation with survival values near 43% and 25%, respectively. Survival values during slow-screan rotation were 23% and 16%. The commer-cially important shellfish species (i.e., penaeid shrimp and blue crab) consistently exhibited survival between 85% and 95% regardless of screen speed. Striped mullet and flounder displayed high survival, while the bay I- anchovy showed limited survival. Small goby and silverside showed no survival during 1985. The two-year average percent survival for most species was essentially unchanged from the percentages reported in 1984. The percent survival of the hardback shrimp increased substantially from the 1984 estimate, while the two-year average for bay anchovy documented low surviu l . I 7-7 I
Table 7.1 Hean standard lengins (mm) of organisms e=amined during G6-hour survivat studies at t he BSE P dur i ng 1983. Penaeus Pi nk./.n i t e Hardoeck Striped Bay Pf enehead Blue Bro.n spp. shrimp shrimo mullet Goby anchovy F' cer Silverside titefish Date Croaker Spot crab shrimp postiervae 07 Jan 85 13-29{ l 17 Jan 85 88 176 23 Jan 85 14 14 I 23 04 Feb 85 13 16 18 Feb 85 14 17 13 04 Mar 85 12 18 18 tier 85 12 20 01 Apr 85 19 12 19 12 r 15 Asr 85 13 8 ! 29 Apr 85 6 28 May 85 6 10 Jun 85 c'c 118 24 Jun 85 08 Jul 85 128 19 Aug 85 136 48 26 16 Sep 85 13 16 27 10 Sep 85 16 16 23 14 Oct 85 18 Nov 85 13 56 09 Dec 85 12 Totat number 1 3 2 1 3 2 2 1 1 1 of trials 10 8 3 { T o s i te c l asses wer e ! : Id on thit date. seu mun as ar; sus sin ums num suas imm uma sur mas aus num um num I amm
-m
I Table 7.2 Mean percent 96-hour unadjusted wrvival values for croaker held during survival studies at the BSEP during 1985. Mean percent survival Size (SL) Eroerimentali Date Range (mmF~~Mean(mm) %w fast Control I 07 Jan 85 8-17 13 12.4 56.3 87.3 t - 20.63 29 - 51.1 100.0 23 Jan di 9-22 14 - 38.1 30.6 04 Feb 85 10-20 13 - 33.2 87.6 18 Feb 85 P-19 14 - 37.7 84.4 I 04 Mar 85 18 Mar 85 15 Apr 85 9-17 9-11 9-18 12 12 12 15.9 52.8 24.3 22.2 98.9 88.6 100.0
.m 18 N>sv 85 9-20 13 36.0 54.4 73.8 g 09 Dec 85 3-23 12 26.3 60.3 91.2 Indicatesrelativescreenspeedrotation, I
k Table 7.3 Results of analysis of variance for spot ind croaker by screen speed collected during survival studies at the t,SEP during I 1985. ecies Scace F-Value PR > F , Croaker Date 1.08 0.1803 Screen Speed 47.1; 0.0001 I-- Date
- Screen Speed 1.28 0.3352 Soot Date 14.51 0.0013 Sci c'.:n Speed 204.53 ^ 0001 i Date
- Screan S,ead 2.69 1171 P
pll r 2 .
I-Table 7.4 Mean cercent 96-hour unadjusted survival values for spot held during survival studies at the BSEP during 1985.
~' '
Mean percent survival Size (SL) Experimentali g
~
Date Range (mm) Mean(mmJ Slow fast Control_ E 17 Jan 85 74-124 88 76.8 - 100.0 3 23 Jan 85 11-19 14 - 14.3 47.2 3 04 Feb 85 11-19 16 - 13.3 86.1 18 Feb 85 12-20 17 2.2 26.0 40.1 04 Mar 85 18 Mar 85 01 Aor 85 14-23 14-28 15 24 18 20 19 0.7 12.6 2.7 41.2 34.3 94.2 83.0 95.3 l 15 Apr 85 12-27 19 3.0 18.5 82.6 Indicatesrelativescreenspeedrotation. I Table 7.5 Mean percent 96-hour unadjusted .urcival values for selected shellfish held during survival ..Jdies at the BSEP during 1985. Mean percent survival Size (TL) Experimentali Species Date Range (mm) Mean (mm) 31ow fast Control l_ Penaeus spp. 01 Apr 85 10-13 12 60.0 89.9 84.0 postlarvae 15 Apr 85 9-14 12 100.0 91.8 94.4 E. drowrc 24 Jun 85 81 117 93.9 - 85.0 shriTr 08 Jul 85 88 . ' 128 97.4 97.1 80.0 g 19 Aug 85 97-168 133 - 87.4 84.2 3 Pink and a white 16 Sep 85 21-91 48 75.9 - 95.0 E shrimp Hardback 16 Sep 85 18-37 26 47.7 - - shrimp 30 Sep 85 13 45 27 - 78.8 87.5 14 Oct 85 8-44 23 70.9 - 92.2 Blue crab 16 Sep 85 8-35 13 95.5 - 89.0 30 Sep 85 6-37 16 - 90.9 89.4 14 Oct 85 6-36 16 95.0 96.9 I indicatesrelativescreenspeedrotation. I I 7-10 l
I I-Table 7.6 Mean percent 96-hour unadjusted survival for miscellaneous species held during survival studies at the BSEP during 1985. I Mean percent survival I She (SL) Experim!ntall Species Date kanye (idii) Mean (mm) Slow fast ~ Control I Striped 23 Jan 85 66-270 150 - 92.0 100.0 mullet 04 Feb 85 20-30 25 - 67.6 95.0 flounder 04 Mar 85 10-15 13 - 90.1 95.8 I Silverside 29 Apr 85 6-!) 8 0.0 - - I Goby 28 May 85 5-9 6 0.0 0.0 - 10 Jun 85 4-10 - 0.0 - I P'.anchead 14 Oct 85 13-25 16 69.9 - - filefish Bay arichovy 09 Dec 85 21-52 36 5.6 93.2 I i frdicates relative screen speed rotation. I I I I I I 7-11
l. i Table 7.7 Survival percentages for organisms collected during fast-screen rotation at the BSiP curing 1984 and 1935.. I Nunber Percent- i Initis's Latert Tots! t Tama Trials Collected Stocked nort a l i t y f morta:ity i survivalT Croaker 22 3785 1756' 37.3 48.0 32.1 Spot S 1349 620 19.0 61.8 28.5 Pink and white shrimp 6 264 219 1.9 5.5 93.4 l Brown shrimp 4 153 145 4.4 17.2 79.7 i Penaeus spp. postlarvae 2 188 4.3 5.8 90.0 l Hareback shrimp 1 33 12.1 10.3 78.8 l Blue crao 5 191 10u 2.1 6.0 93.1 i l Blee crab megalops 2 159 71 1.9 11.3 87.4 i Weektish 4 282 191 29.4 82.2 13.0 Searobin 4 132 124 2.3 8.1 89.8 ! 88ackcheek tongue 8ish 3 110 95 5.5 15.8 79.8 Bay anchowy 3 311 155 50.2 98.7 0.6 y striped mutset 2 99 89 10.1 14.6 76.8
/, Ftounder i 91 78 8.8 1.3 90.1 N Gooy 2 477 0 100.0 0.0 0.0 fNumberoforoanismsthat were found dead in collection gear i nuecer collected i $Numoer of organisms that died after being stocked in tat.ks i number stocked
$100-It}) (Number collectea) + (i) (Number stocked ) . ($) t ot t:er sive organisms collected out not stocked)) ! number collected ,
P i i I 1 t W K W W W W W W W W W W M M M M M 'M
E E E E E E E E M M W E E AN E
~
Teole 7.8 Survival percentages to- organisms cot lected during sic.-screen rotation at the BSEP curing 1984 sad 1985. Nue. der Percent initlaf La+cnt Totef Trials Collected Stockeo mortalityf sortality survival I Tema j Croaxer 19 2950 1334 48.0 cr.3 a lo.9 Spot 12 2139 986 37.3 59.0 tc.2 Pink anc white shriep 2 iCO 91 9.0 14.3 78.0 5 350 336 2.9 6.6 94.9 l Bro =, shrirm Penaeus spp. potriarvae 2 131 119 9.2 15.1 "7.1 Hsraback snrimp 3 452 151 44.9 16.6 45.1 3 71 61 2.8 3.3 94.0 Blue craos 2 203 135 3.0 11.1 id .h Blue cran mega' ops B y e,cho y 1 596 39 90.1 100.0 0.0 W 1 203 0 100.0 0.0 0.G Goo ~ 1 59 C 100.0 0.0 0.0 Silverside 1 33 31 6.1 25.8 69.7 Planehead filetish f%eceroforganismsthat=ere los a ce63 la col.ection gea r i nuerce cotlectec. Noter ci orgar ises that d i er* :- t ier Deing stocked in fa"ds 2 nun cer stocked.
+ 1: 1 (numoer stochec) - 1:1 ( c>t rer live organises collectec est not stoc-eo t ! r..coer coffected.
TIOC-f(f) (neader cc lecte3) i 1
s,.i - l l
/
Taste 7.9 Surviva percentages for control organisms collected for survivat studies at the BSEP during 1984 ar.a 1985 l 1 Number Percent Init!al Latent Totat Triats Collected Stocked mortalityf mortality I survival i rais a 1841 5.7 7.1 89.1 Crcoker 25 4137 2334 1072 4.4 10.5 89.5 l Spov 13 600 386- 2.5 4.9 92.3 P i r.K and' white shrimt 8 830 15 1.3 21.7 79.6
~3rown shesep 8 115 112 2.6 8.0 69.5 P_enaeus posttarvae 2 56 4.6 6.4 90.1 O*raback sneirnp 3 1032 l 93.7 8 371 158 1.6 5 .1 Giue crab 231 7./ 7.4 84.3 Blue crab megalops 4 362 t N 116 3.2 40.5 54.1 155 l b WeskIish' 3 l 304 97 1.9 1.0 97.0 Searonin 4 475 146 0.2 2.0 99.2 Di ec kcheek tonguefish 4 140 124 11.4 22.6 68.6 ib y onctiovy 3 58 0.0 1.7 99.3 st r i ped rau l t e t 2 58 24 4.6 0.0 95.2 Ftounder 1 21 Number of organisms that =ere found dead in collection gear i fiumber collected I Number of organisms that died after be!ng stocked !a tank. ! number stocked.
100 - [(f ) (number cOf f ec ted ) + ($ ) (r umber stocked ) + ti) (Otner five organiSes co:18*CtcJ but net s t G<.h ed ) ) i number rollected, mEB e m 'm W 'M M WW m m m W m a m m m met m m
I I 8.0 1MP!!!GEMENT (Larval) 0.1 Introduction With the initiation of fine-mesh screen operation, many of the larval and postlarval organisms that previously would have been entrained were impinged and returned to the Cf E. Ihe larval impingement program was be-gun in January 1984 to provide an estimate of the total number of larvae and postlarvae being impinged. Survival percentages apulled to these es-I timated numbers cave an assessment of the success of f ine-mesh screens and the fish , return system for returning larval organisms to the estuary alive. 8.2 Methsds To collect the impinged larval and postlarval organisms, a 505-t.m mesh plunkton net, 1 m in diameter, was placed in the fish return sluice-I way such that the entire water column was filtered. Five. minute samples were collected biweekly on mid and slack tides over one 24-hour period. Due to the large number of organisms collected, mtny t ~ the samples were subsampled by retaining at least 25% of the total sample weight for processing. Samples were processed in the same manner as entrainment samples, except only rainimum and maximum lengths were recorded for each species (CP&L 1983). Incidental collection of organisms large enough to be considered ju-veniles or adults recuired the enforcement of length limits. Cnly fish and shrimp $ 40 mm were identified with the except' ion of cels, pipefish, I and leptocephali which were kept only if they were $ 100 mm. The portunid
<:rab ' t.tof f limit was ( 24 mm.
fhe seasonalities of brown shrimp Pennens aztecus and pink and white shrimp (P. duornrum and P. sotiferus, respectively) were determined th same way as describ?d in Section 6.2. 8-1
Il 8.3 Results and Discussion 8.3.1 Dominant Species 8 A total of 5.2 x 10 organisms representing 97 taxa was impinged dor. ing 1985. Croaker hficropogonias undulatus and spot Leiostomus xanthurus were the dominant species comprising 23.4% and 21.9%, respectively, of the total catch. Other impinged species, in decreasing order of abundance, were Penaeus spp. postlarvac (11.7%), A;1choa spp. ($ 12 mm) (8.8%), Gobiosoma spp. (8.8%), portunid megalops (8.7%), and bay anchovy Anchoa mitchilli (7.0%) . Atlantic menhaden firevoortia tyrannus and hardback shrimp Trachypeneus constrictus each accounted for 1.2% and naked goby Gobiosoma bosci accounted for 0.9% (Table 8.1). Excluding hardback shrimp and naked goby, these species accounted for 93.7% of the total catch n 1985 and 95.7% in 1984. Percent of total catch for Penaeus spp, postlarvae and Gobiosoma spp. increased in 1985 as ccitpared to 1984. Percent of total catch in 1985 for portunid megalops,- Anchoa spp., and menhaden decreased from 1984 (CP&L 1985a). l 8.3.2 Seasonality and Abundance The typical winter and summer periods of abundance observed in the 5 entrainment and river larval fish programs (Sections 3.3.2 and 6.3.2) were 5 also observed in larval impingement. The winter period consisted of men-haden, spot, croaker, mulle:t Afugil cephalus and A!. curema, flounder Paro-lict.thys spp., Lnd brown shrimp--all ocean-spawned species. Portunid mega-lops is an early life stage of the blue crab Ca!!inectes spp. The period of abundance for portunid megalops occurred during the late summer and fall months and was considered a winter species. The summer period con-sisted of ocean-spa'wned species such as seatrout Cynoscica nebulosus arid C. regalis and pink and white shrimp and of estuarine-spawned species such as anchovy Anchoa spp. , A. hepsetus and A. mitchilli, Goblonellus spp. , and Co-blosoma spp. (Table 8.2). I 8-2 I
s 8.3.3 Survival Estimates In most cases, survival studies were conducted with organisms col-r lected from two dif ferent intake screen rotation speeds. To obtain an L overall percent survival of impinged larval and postlarval fish and
- penaeid shrimp returned to the estuary, all survival tests conducted in 1984 and 1985 from fest-screen rotation for size classes whose mean length I was $ 40 mm were used. For blue crabs the size class used had a mean length 3 24 mm. The same was done for corresponding size classes f rom slow screen rotations. These percentages are presented in Table 8.3.
A monthly estimate of total number impinged for selected species was calculated by expanding the known number collected for the hours sampled by the total hours in that month. These monthly estimates were then con-bined and are presented as the total number impinged in Table 8.3. In 1985 cn estimated 1.2 x 10 8 croaker were impinged. T.f they had been impinged on slow-rotating screens,1.6 x 10 7would have been returned to the estuary alive. If they had been impinged on fast-rotating scret_ns, 7 3.8 x 10 would have been returned alive. Total spot impingemerJ vas 1.1 x 108. If these had been impinged during slow rotation, 9.8 x 10 would 6 have returned to the estuary alive. If they had Men impinged during f ast rotation, 3.4 x 107 would have survived. Similar fast / slow survival esti-mates were calculated for the other species tested and are presented in Table 8.3. The 12 taxa tested for survival represent 73% of the total i larval impingement catcn. Of these, 45% would have been returned alive to the estuary if the screens had been on f ast rotation. This corresponds to 33% of the total larval organisms impir',ed being returned alive to the estuary, 8.4 Summary and Conclusions The larval impingement program initiated in 1984 was continued in 1985 to provide an estimate of the total larvae and postlarvae being im-pinged by the BSEP. A total of 5.2 x 10 organisms 8 representing 97 taxa 8-3
I was impinged with croaker and spot dominating the catch. The seasonali-ties of those commercially and/or recreationally important species were much the same as those observed in the entrainment and river larval fish programs. The 12 taxa tested for survival represented 73% of the total larval impingeme..t catch. During f ast-screen rotation, 45% of these organisms would have been returned alive to the estuary which corresponds to 33% of the total larval organisms impinged being returned alive to the estuary. ' I I e I I I a 8 : I I I I I 8-4 I I_
I Table 8.1 Ranking by percent of total larval impingement collected at the BSEP during 1985. Species Percent of total Croaker 23.4 Spot 21.9 Penaeus spp, postlarvac 11.7 Anchoa spp. 8.8 GoNosorna spp. 8.8 Portunid megalops 8.7 Bay anchovy 7.0 Atlantic menhaden 1.2
.I Hardback shrimp 1.2 Naked goby 0.9 Other taxh 6.4 Total 100.0 l
I-I I I I I I I 8-5 I
l Taole 8,2 Total number of selected species collected by trip in larval Impingement at the BSEP during 1985. Pcoseus Goblenelius Gobiosoma Portunid t spp. Sample Total Atlantic spp. megalops Croaker Mollet flounder postlarvae spp. date organisms Anchovy menhaden Seatroet Spot 142 907 237 8 2,636 23,774 863 109 0 1,885 15,946 228 07 J'an 65 32 0 0 61,003 1187 249 0 23 Jan 85 79,875 1,038 80 0 15.385 0 933 130 0 0 0 06 f eb 85 41,808 I,594 357 0 21,817 16,4 6 7,584 167 210 0 0 0 0 18 f eb 85 29,578 121 104 0 21,209 166 4 44 2542 0 63,223 34,760 228 1417 7' " 04 Mar 85 106,017 1,010 2,872 l 70 460 47 362 0 18 Idar 85 120,358 913 3013 0 55,274 9,381 20 6,733 17/> 4 303 01 Apr 85 62,051 IT 6390 0 41,167 6,784 19 0 2,488 15! 4 160 15 Apr 85 P,985 84 1293 0 3,540 581 5 90 81 7 l 0 4 138 3 3 0 423 29 Apr 85 17,013 11,289 33 0 0 0 572 326 3,232 13 May 85 27,423 19,154 0 59 65 1,083 95 27,764 81 25,ve3 0 861 8 3 0 0 28 May 05 60,544 .315 0 4 0 4,625 79 36,043 10 Jan 85 83,342 34,727 0 464 0 1.316 36 !!,578 49 20,876 0 23 0 8 0 0 24 Jun 85 35,300 4 08 Jul 85 23,124 5,887 0 139 0 0 0 0 3,175 95 It,704 72 0 2,009 21 704 247 4,536 762 0 12 0 6 0 22 Jul 85 10,489 37 154 4,259 2,287 0 63 0 0 0 0 05 Aug 85 17,706 150 341 0 0 0 0 2,418 0 19 Atg 8) 3,300 250 0 2 0 0 7,456 63 1,916 3,540 03 Sep 85 25,453 10,305 0 119 a 80 0 0 22,938 733 6,296 74,857 16 Sep 85 132,899 13,101 0 54 0 112 0 1,427 17 72 1,203 4,511 584 0 14 0 3 0 30 Sep 85 918 2,005 0 1,450 0 0 1,181 197 14 Oct 85 13,001 3,147 0 3 7,133 22 0 2,592 178 114 20,194 I,581 0 0 0 7,161 28 Oct 85 124 4,224 0 0 14,769 0 0 2.508 328 11 tA>v 85 26,555 3,578 0 4,835 0 26 1,666 314 12 25 Nov 85 26,764 1,512 0 0 0 !7,239 4 199 222 17 247 29,640 1,898 5 0 0 26,764 16 09 Dec 85 ?! O 182 10 0 3,311 87 13 24 23 Dec 85 9,464 5,247 1 l I em nas as aus um ses aus em num num sur aus aus em um m se uma mas
.rs ;
w' m unus sumum w i 3- ~v u Table 8.3 Overall percent ' survival and number of impinged larval organisms returned alive to the Cape Fear Estuary. Overall percent survival Number returned alive Fast- Slow- Fast- Slow-Total screen screen screen screen number iepinged rotation rotation rotation rotation Species 1.2 x 10 88 31.9 13.7 3.8 x 10 77 1.6 x 10 76 Croaker 9.8 x 10 Spot 1.1 x 10 30.9 8.9 3.4 x 10 Bay anchovy 3.7 x 10 77 0.7 0 2.6 x 10 57 0 Panoeus spp. posti arvac 6.1 x 10 6 90.2 77.1 5.5 x 10 6 4.7 x 10 7 Flounder 1.5 x 10 90.0 - 1.4 x 10 6 _ 1.6 x 10 67 67.7 - 1.1 x 10 _ Mullet Portunid megalops 4.5 x 10 5 87.0 86.3 3.9 x 10 #7 3.9 x 10 7 Weakfish 4.2 x 10 5 12.6 - 5.3 x 10 5 - Prionotus spp. 1.8 x 10 6 89.8 - 1.6 x 10 - - 6.0 x 10 5 78.8 48.4 4.7 x 10 64 2.9 Hardback shiimp 7.5 xx 10"4 Pink and white shrimp 1.0 x 10 95.8 75.0 9.6 x 10 5 10
?'
" 3.8 x 10 57 91.7 95.1 3.5 x 10 3.6 x 10 5 Blue crab 4.6 x 10 6 - -
Anchoa sop. 6.2 x 10 _ _ Atlantic menhaden _ 8.8 x 10 7 Other organisms (83 taxa) - - Total or ganisms 5.2 x 10 8 Total organisms tested 3.8 x 108 (73%)i 1.7 x 108 (45%)S Total organisms tested (excluding bay anchovy) 3.4 x 108 (65%)I 1.7 x 108 (50%)5 f ercent P of total organisms impinged that were tested. l i Percent of total organisms impinged that were tested excluding by anchovy. S Percent of a that were returned alive. E Percent cf b that ware returned alive. i - __m..m . .
I 9.0 1MPINGEMENT (Juvenile and Adult) 9.1 Introductio. Impingemeat studies have been conducted at the BSEP since January 19, 1974, when water was first pumped through the plant. Objectives of the
! study were to determina the numbers, weights, species composition, and
'ength frequency of organisms impinged.
i i The 1985 juvenile and adult (J/A) impingement study was conducted with the fish diversion 'tructure in operation. The fish diversion struc-ture prevented larger organisms from eatering the intake canal except when
! screen panels failed as a result of biofouling and/or debri,s buildup.
During the f ailure and repair or the screens, the structure was open al-
! lowing organisms to enter the intake canal. Except for these short periods, most J/A fish and shellfish were excluded from possible impinge-ment during 1985.
I 9.2 Methods Samples were collected for one 24-hour period each week during 1985. [ The samples were taken by placing a steel-framed collection basket in each sluiceway. The baskets were fitted with a 9.4-mm plastic webbing. Con-trol valves were opened so screen wash water flowed freely in both sluice-ways. f,s a basket filled with Jrganisms and debris, a third basket was set in the sluiceway to guarantee continuous filtration of the screen wash water while the basket was emptied. Samples were taken to the laboratory I for the sorting, identification, enumeration, measurement, and weighing of
. organisms. bp to 50 individuals per size group of the 13 selected species were measured from each sample (CP&L 1985a). Monthly estimates and expca-sion factor calculations were identical to those described in CP&L l (1983). Fish 3 41 mm, shrimp 3 41 mm, portunid trab 3 25 mm, and eel and pipefish 3 101 mm were included in the J/A impingement catcn.
I I 9-1
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I 9.3 Results and Discussion 9.3.1 Species Composition l Juvenile and adult impingement during 1985 totaled 5,967,474 orga-nisms representing 106 taxa and weighing 15,098 kg. Bay anchovy Anchoa mitchilli was the most abundant species totaling 82.7% by number of the catch. 8lue crab Callinectes sapidus (2.9%), croaker Af!cropogonias undulatus (2.1%), brown shrimp Penaeus aztecus (2.0%), spot Leiostomus xanthurus (1.7%), and A",lantic silverside Afendia mendia (1.5%) were second through sixth in abundance, respectively. The remaiiing 100 taxa accounted for 7.1% of the total catch. The 1985 densities were 8.9% greater in number and 15.5% less in weight than the 1984 densities. The 1985 densities were , 37.5% less in number and 72.4% less in weight than the prefish diversion structure (1977-1982) mean annual densities (Tab.e 9.1). 9.3.2 Flow Rates The 1985 flow rates were similar to 1984 flow rates and were substan-tially below the 1977 through 1982 mean (CP&L 1985a). Mean monthly intake flow rates in 1985 ranged from 53.9 x 10 63 / month 0 3 3 in December to 97.3 x 10 m / month in November. The mean monthly flow for 1985 was 79.6 x 10 6 l m3 / month (Figure 9.1). Thc reduction in flows in 1985 is the result of I B plant outages and flow minimization. Tt s reduction and the operation of l the diversion structure contributed to the reduction in the total numbers impinged. 9.3.3 Length-Frequency Distributions Length-frequency data was used to examine the size distribution of certain species from the impingement catch. Atlantic menhaden Brevoortia tyrannus, My anchovy. spot, and croaker we; e caught in adequate numbers to , analyze. All four species exhibited similar length-frequency distribu- , tions as reported in CP&L (1985a). The Atlantic menhaden, spot, and croaker length-frequency distributions further documented the reduction in size of juvenile and adult individuals in impingement due to their 9-2 g 5._. l
exclusion by the fish diversion structure. Adult bay anchovy, due to l their small she, gained access to the intake canal chrough the fish diversion screens and thus exhibited a length-frequency distribution similar to prefish diversion structure reportings (CP&L 1982). 9.3.4 Survival Estimates I The J/A survival studies have tested 11 frequently imoinged species (Section 7.0). The percent survival is a mean of all experiments for the I J/A size class. When survivai study results were applied to the J/A im-pingement catch, 5890 kg of organisms were returned to the estuary alive during 1985. When the survival estimates are subtracted from the J/A impingement, only 522 kg of spot, 421 kg of croaker,167 kg of blue crab, and 240 kg of all penaeid shrimp Penaeus spp. were not returned alive to the estuary. The application of the survival study results to the im-pingement catch re. duces the loss from impingement by 10.7% in number and by 39.0% in weight of the 1985 J/A impingement catch. The catch, excluding bay anchovy, was reduced 48.6% by number and 56.4% by weight I when survival study results were applied (Table 9.2). Observations of organism. in the sluiceway showed many individuals of additional species initially survived the fish return system. Inose additional species have yet to be tested, thus the reduced percentages are a minimum and future studies may show additional survival. 9.4 Summary and Canclusions The 1985 J/A impingement catch consisted of nearly six million org&. nisms weighing iust over 15,000 kg. Bay anchovy (8'%) was the most abun-dant species and blue crab (3%) was *ne second most abundant species. Impinge' ant per million cubic meters of water entrained ivreased by 9% in e number and decreased by 16% in weight when compared to the 1984 catch. The 1985 reduction by number and weight was 38% and 72%, respectively, over the 1977-1982 mean. This showed the continued effectiveness of the fish diversion structure. The structure excluded most of the J/A Atlantic menhaden, spot, and croaker, while bay anchovy was not excluded by the structure and thus dominated the 1985 J/A impingement catch. e.: y
a ., .. . , _ . . . . . . , . _ . . . - - .. . . . - - - - - . .._ _. - . _ . _. l I ! Length frequency analysis generally showed similar distribution of organisms as reported in 1984. Survival studies documented a reduction in the impingerrant loss. The fish return system allowed approximately 11% by number and 39% by weight of all organisms impinged to be returned to the estuary alive. Approxi-mately half of all organisms, excluding bay anchovy, were returned to the l estuary alive during 1985. E L I l l l l 5 I B a I I E I I 9-4
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M M Table 9.1 A summary of juvenile and adult impingement at the B'SEP during 1985 with comparisons to previous years. l l Number per Weight (kg) per million cubic Total million cubic Species Percent of catch Total number meter entrained weight (kg) meter entrained Bay anchovy 82.7 4,933,685 5,165.8 4,889 5.1 Blue crab 2.9 174,709 182.9 . 2,256 2.4 Croaker 2.1 124,535 130.4 788 0.8 Brown shrimp 2.0 117,555 123.1 1,656 1.7 Spot 1.7 101,773 106.6 1,217 1.3 Atlantic silverside 1.5 90,681 95.0 302 0.3
? Atlantic menhaden 1.0 60,747 63.6 853 0.9 w
Blackcheek tonguefish 1.0 58,003 60.7 237 0.2 Pink shrimp 0.8 47,879 50.1 122 0.1 l Rough silverside 0.8 47,105 49.3 99 0.1 96 additional taxa 3.5 210,802 220.7 2,679 2.9 i Total organisms 100.0 5,967,474 6,248.2 15.098 15.8 I 1984 5,128,617 5,692.9 16,890 18.7 ) Percent change + 8.9 - 15.5 1977-1982 annual mean 14,267,926 10,000.3 83,523 57.3 Percent change - 37.5 - 72.4 i I J
Table 9.2 Estimated su: tal of juvenile and adult organisms impinged during 1985. Estimated Estimated Percert Number of Number Weight (kg) number weight (kg) Species surv ^ivt survival test impinged ' impinged survived survived' Blue crab 92.6 8 174,709 2,256 161,781 2089 Striped mullet 92.0 1 10,287 639 9,464 588 Penaeus spp. 90.2 G 54,707 258 49,346 233 (pink and white)- Brown shrimp 87.0 9 117,555 1,656 102,273 1441 Blackcheek tonguefish 83.1 3 58,003 237 48,200 197 e Hardback shrimp 57.3 3 9,657 9 5,533 5 Spot 57.1 2 101,773 1,217 59,112 69 5 Croaker 46.6 6 124,535 788 58,033 367 Weakfish 36.2 2 1,907 15 690 5 itlantic menhaden 15.6 1 60,747 853 9,477 133 Bay anchovy 2.8 2 4,933,685 4,889 138,143 137 Other species (94 taxa) - - 319,909 2,281 - - Total 5,967,474 15,098 641,052 5890 Percent survival 10.7 39.0 Excluding bay anchovy 1,033,789 10,209 502,909 5753 Percent survival _ 48.6 56.4 W m W W W W F W W W' W W m W m m M M M
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10,0 REFERENCES Ambrose, J., Jr. 1983. Age detarinination. Pages 301-324 in L. A. Niel-son and D. L. Johnson (eds). Fisheries techniques. American Fisheries Society, Blacksburg, VA. k Birkhead, W. S.,B. J. Copeland, and R. G. Hodson, 1979. Ecological monitoring in the lower Cape Fear River estuary, 1971-1976. North Carolina State University, Raleigh, NC. CP&L. 1980. 1979 monitoring program. BSEP Cape Fear studies, Supplement I. Carolina Power & Light Company, New Hill, NC. 1982. Brunswick Steam Electric Plant annual biological monitor-I ing report, 1981. Carolina Power & Light Company, New Hill, NC. 1983. Brunswick Steam Electric Plant annual biological monitor-I ing report, 1982. Carolina Power & Light Company, New Hill, N:; 1984. Brunswick Steam Electric Plant 1983 biological monitoring report. Carolina Power & Light Company, New Hill, NC. 1.985a. Brunswick Steam Electric Plant 1984 biological monitor-ing report. C6 slina Power & Light Company, New Hill, NC. 1985b. Brunswick Steam Electric Plant, Cape Fear Studies, Interpretive report. Carolina Power & Light Company, New Hill, NC. Carpenter, J. H. , and W. L. Yonts. 1979. Dye tracer and current meter studies, Cape Fear Estuary, North Carolina, 1976, 1977, and 1978. BSEP Cape Fear studies. Report to Carolina Power & L' ;ht Company. Miami, FL. Copeland, B. J., and R. G. Hodson, 1977. Larvae and postlarvae in the Cape Fear Estuary, North Carolina, 1976-1977. Report No. 77-5 to Carolina Power & Light Company. North Carolina State University, Raleigh, NC. Copeland, B. J. , R. G. Hodson, and R. J. Monroe,1979. Larvae and post-larvae in the Cape Fear River estuary, North Carolina, during opera-tion of the Brunswick Electric Plant, 1974-1378. North Carolina State University, Raleigh, NC. Darnell, R. M. 1961. Trophic spectrum of an estuarine community, based on studies of Lake Pontchartrain, Louisiana. Ecology 42: 553-568. Everhart, H. W., and W. D. Youngs. 1981. Principles of fishery science 2nd ed. Cornell University Press, Ithaca, NY. Hodson, R. G. 1979. Utilization of marsh habitats as primary nursery areas by young fish and shrimp, Cape Fear Estuary, North Carolina. BSEP Cape Fear Studies, Volume VIII. North Carolina State University, Raleigh, NC. 10-1
I Hodson, R. G. , C. R. Benn ,tt. and R. J. Monroe. 1981. Ichthyoplankton W samplers for simultaneous replicate samples at surf ace and bottom. Estuaries 4(3):176-184. Hogarth, W. T., and K. L. Nichols. 1981. Brunswick Steam Electric Plant intake modifications to reduce entrainment and impingement losses. Carolina Power & Light Company, New Hill, NC. Hoss, D. E. , W. F. Hettler, Jr., and L. C. Coston. 1974. Effects of thermal shock on larval fish: Ecological implications with respect to g entrainment in power plant cooling systems. Pages 357-371 in J. H. S. 3 Blaxter (ed.). The early life history of fish. Springer Verlag, Berlin, West Germany. Hoss, D. E., L. E. Clements, and D. R. Colby, iW 7. Synergittic effects of exposure to temperature and chlorine on servival of young-of-the-year estuarine fishes. Pages 345-355 in F. J. Vernberg, A. Calabrese, F. P. Thurberg, and W. B. Vernberg (eds.). Physiological responses of marine biota to pollutants. Academic Press, New York. Huish, M. T. , and J. P. Geaghan. 1979. A study of adult and juvenile fishes of the lower Cape Fear River near the Bru swick Steam Electric Plant, 1975-1976. North Carolina State Uni mrsity Raleigh, NC. Lagler, K. F. 1952. Freshwater fishery biology. Wm. C. Brown Co. Pub-lishers, Dubuque, IA. McGroddy, P. M., and R. L. Wyman. 1977. Efficiency of nets and a new device for sampling livino fish larvae. J. Fish. Res. Board Can. 34:571-574. McHugh, J. L. 1967. Estuarine nekton. Pages 581-620 in G. H. Lauff (ed). Estuaries. American Association for the Advancement of Science, Washington, DC g Norcross, L. B. , and R. F. Shaw. 1984 Oceanic and estuarine transport of fish eggs and iarvae: A review. Am. Fish. Soc. 113:153-165. Scnwartz, F. J., P. Perschbacher, L. Davidson, K. Sandoy, J. Tate, M. McAdams, C. Simpson, J. Duncan, and D. Mason. 1979. An ecological g study of fishes and invertebrate macrof auna utilizing the Cape Fear 3 River estuary, Carolina Beach Inlet, and adjacent Atlantic Ocean, 1978. BSEP Cape Fear Studies, Volume XV. Institute of Marine Sciences, University of North Carolina, Morehet.d City, NC. Schwartz, F. J., J. Morgan, K. Sandoy, M. McAdams, and D. Mason. 1980, 1 Foed cnalyses of selected fishes captured in Cape Fear Estt.ary and 5 adjacent Atlantic Ocean, North Carolina, 1973-1018. Institute of E Marine Sciences, University of North Carolina, Morm f ad City, NC. Weinstein, M. P. 1979. Shallow marsh habitats as primary nurseries for fishes and shellfish, Cape Fear River, North Carolina. Fish. Bull. 77:339-357. I 10-2
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- I
) Weinstein, M. P., S. L. Weiss, and M. f. Walters. 1980. Multiple deter-f minants of community structure in shallow marsh habitats, Cape Fear i Estuary, NC. Mar. Biol. 58:227-243. i i t !I il ll 4 l l l I /E
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