ML20079M996

1986 Biological Monitoring Rept

ML20079M996
Person / Time
Site:	Brunswick
Issue date:	12/31/1986
From:	Benedict C, Booth G, Cates K CAROLINA POWER & LIGHT CO.
To:
References
RTR-NUREG-1437 AR, NUDOCS 9111110034
Download: ML20079M996 (106)

Text

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Brunswick Steam Electric Plant g

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f-1 1986 BIOLOGICAL l

MONITORING REPORT I

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IE BIOLOGY UNIT ENVIRONMENTAL SERVICES SECTION i

Cp&L Carolina Power & Light Company l

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I BRUNSWICK STEAM ELECTif1C PLANT 1986 BIOLOGICAL MONIT0 RING REPORT Prepared Dy:

C. Benedict Juvenile and Adult Impingement G. F. Booth Project Scientist K. N. Cates Entr ainment, Larval Impingement D. S. Cooke River Larval Fish W. E. Herring Water Quality K. A. NacPherson Editor I

L. W. Pollard Marsh T. E. Thompson Nekton H. T. Tyndall Surviv.t1 Studies I

W. J. Warren-Hicks Statif, tics Biology Unit Environmental Services Section CAROLINA POWER & LIGHT COMPANY NEW HILL, NORTH CAROLINA March 1987 Reviewed and Approved by:

M ( ). M M Principal' Scientist Biology Unit I_

This report was prepared under my suptrvision and direction, and I accept full responsibility for its content.

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Hanager

_I Environmental Services Section l

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I This copy of this report is not a controlled doctoont as datalled in Environmental Services section Procedures. Any changes made to the original of this report subsequent to the date of laswance can be obtained from:

Manager Environmental Services Section Carolina Power & Light Company g

Shearon Harris Energy & Environmental Center 3

Route I, Son 327 New HiI1, North Carolina 27562 g

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.I Acknowledgmend Many thanks are extended to Debbie

Calhoun, Scott

Cates, Della Lanier, Preston McLendon, Tina Reece, and R. G. Sherfinski who with-out 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 Pisces and constructed and maintained I

field and laboratory equipment.

Thanks also go to members of the Data Management & Control Unit and Word Processing Subunit at the Shearon Harris Energy & Environmental Center.

A very special thank you is extended to Susan E. Holth who typed the drafts associated with the preparatien of this report.

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Table of Contents lL Pace Acknow1edgmentr.....................................................

i List of Tah1es.....................................................

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i list of Figures....................................................

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

viil Executive Summary..................................................

ix 1.0 INTR 000CTION...............................................

1-1 2.0 WATER QUALITY..............................................

2-1 E

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

2-1 5

2.2 Methods....................................................

2-1 2.3 Results and Discussion.....................................

2-2 l

3.0 RIVER LARVAL FISH..........................................

3-1 3.1 Introduction...............................................

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

3-1 1

3.2.1 Sample Co11ection..........................................

3-1 3.2.2 Data Analysis..............................................

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

3-2 3.3.1 Dominant Species...........................................

3-2 1

3.3.2 Time-Series Analysis.......................................

3-4 3.4 Summary and Conclusions....................................

3-5 1

4.0 MARSH......................................................

4-1 4.1 Introduction...............................................

4-1 4.2 Methods....................................................

4-1 1

4.2.1 Station Description........................................

4-1 4.2.2 S amp l i n g Me t h od s...........................................

4-2 4.2.3 Data Analysis..............................................

4-2 4.3 Results and Discussion.....................................

4-3 4.3.1 Dominant Species...........................................

4-3 4.3.2 Seasonal Distribution......................................

4-3 4.3.3 Spatial 0istributicn.......................................

4-4 4.3.4 Time-Series Analysis.......................................

4-6 Alligator Creek............................................

4-6 Mott's Bay.................................................

4-6 Walden Creek...............................................

47 Baldhead Creek..........,..................................

4-7 4.4 Summary and Conclusions....................................

4-7 5.0 NEXT0N.....................................................

5-1 0.1 I n t rod u c t i e n...............................................

5-1 5.2 Methods....................................................

5-1 5.3 Resulss and Discussion.....................................

5-3 ii

Table of Contents (continued)

Pace

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5.3.1 Total Organisms............................................

5-3 5.3.2 Spatial Distribution.......................................

5-3 E

5.3.3 Time-Series Analysis........................-..............

5-4 5

5.3.4 Diversion Structure Evaluation.............................

5-6 5.4 S uma ry and Co nc l u s i o n s....................................

5-8 6.0 E N T RA I N M E N T................................................

6-1 6.1-Introduction...............................................

5-1 6.2 Methods'....................................................

6-1 6.3 Results and Discussion.....................................

6-2 6.3.1 Dominant Species,..........................................

6-2 6.3.2 Seasonality and Abundance..................................

6-2 6.3.3 Number Entrained...........................................

6-3 6.3.4 Special Study.................

6-3 6.3.5 Flow Minimization..........................................

6-4 g

6.3.6 Time-Series Analysis.......................................

6-4 3

6.4 S umary and C o nc l u s i o n s....................................

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7.0 SURVIVAL STUDIES...........................................

7-1 7.1 Introduction...............................................

7-1 7.2 Methods....................................................

7-1 7.2.1 Collection.................................................

7-1 7.2.2 Stocking and Monitoring....................................

7-2 7.2.3 Definitions and Calculations...............................

7-3 7.3 Results and Discussion.....................................

7-3 g

7.3.1 Total Organisms............................................

7-3 3

7.3.2 Species Accounts...........................................

7-4 Selected Finfish...........................................

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Selected She11(ish.........................................

7-5 Miscellaneous Species......................................

7-6 7.3.3 Three-Year Estimates.......................................

7-7 7.4 Suma ry and Conc l u s i o n s....................................

7-7 8.0 IMPINGEMENT (Larva 1).......................................

8-1 8.1 Introduction...............................................

8-1 g

8.2 Methods....................................................

8-1 g

- 8.3 Results and Discussion.....................................

8-2 8.3.1 Dominant Species...........................................

8-2 8.3.2 Seasonality and Abundance..................................

8-3 8.3.3 Survival Estimates.........................................

8-3 8.4 Suma ry and Co nc l u s i on s....................................

8-4 9.0 IMPINGEMENT (Juvenile and Adult)...........................

9-1 9.1 Introduction...............................................

9-1 9.2 Methods....................................................-

9-1 a

9.3 Results and Discussion.....................................

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9.3.1 Species Ccmposition........................................

9-1 9.3.2 Flow Rates.................................................

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?.3.3 Length-Frequency Distributions.............................

9-2 9.3.4 Survival Estimates.........................................

9-3 9.4 Suma ry and Conc l u s i o n s....................................

9-4

10.0 REFERENCES

10-1 iii

List of Tabfe?

Table Page 1.1 1986 Brunswick Steam Electric Plant biological monitor-ing program summary........................................

1-3 3.1 Annual mean density and the percentage of the total mean density for the most abundant taxa collected in the river larval fish program, 1981 through 1986........

3-6 3.2 Rest M of time-series analysis for river larval fish m a by station group indicating trends in density from 1977 through 1986.............................

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4.1 Total catch and percent total of the ten most abundant species collected in the marsh study during 1986...........

4-9 4.2 Annual catch-pertunit-effort by creek system for 13 I

selected species it,the marsh study during 1986............

4-9 4.3 Remits of time-series analysis of marsh data by creek indicating treads in abundancc from 1981 througn 1986......

4-10 5.1 Total number, percent total number, and annual catch-I per-unit-effort of the sen most abundant species collected in the nekton study during 1986..................

5-9 5.2 Annual catch-per-unit-effort by station of sclected crganisms cc11ected in the nekten study during 1986........

5-10 5.3 Mean standard length by location of selected species collected in the nekten study during 1986.................

5-11 5.4 Results of time-series analysis of nekton data by I

station group indicating long-term trends in relative abundance of selected species..............................

5-12 6.1 Hean density and percent total of fish, penaeid I

shrimp, and portunid crabs entrained at the BSEP, September 1978 through August 1986.........................

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6.2 Entrainment densities at the BSEP, September 1985 through August 1986........................................

6-8 6.3 Entrainment rates at the BSEP, September 1985 I

through August 1986........................................

6-10 6.4 Reduct%n 'n entrainment by number and mean density for most abundant species for four special study pc.riods....................................................

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List of Tables (continued)

Page 6.5 Results of time-series analysis of entrainment data El indicating trends in density from September 1980 E l through August 1986........................................

6-12 i

7.1 Mean percent 96-hour unadjusted survival values for selected finfish held during survival studies at the

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BSEP during 1986...........................................

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-l 7.2 Mean percent 96-hour unadjusted survival values for selected shellfish held during survival studies at the BSEP during 1986...........................................

7-10 7.3 Mean percent 96-hour unadjusted survival values for miscellaneous species held during survival studies at the BSEP during 1986.......................................

7-11 7.4 Survival percentages for organisms collected during a

fast-screen rotation at the BSEP from 1984 g

through 1986...............................................

7-12 7.5 Survival percentages for organisms collected during slow-screen rotation at the BSEP from 1984 through 1986...............................................

7-13 7.6 Survival percentages for control organisms collected h

for survival studies at the BSEP from 1984 through 1986....

7-14 8.1 Ranking by percent of total impinged larvae collected l

at the BSEP during 1986....................................

8-5 8.2 Total number of selected species col'ected by trip in E

larval impingement at the BSEP during 1986.................

8-6 5

8.3 Percent survival and number of impinged larval 3

organisms returr *d alive to the Cape Fear Estuary 3

during 1986................................................

8-8 9.1 A summary of juvenile and adult impingement at the Brunswick ". team Electric Plant during 1986 with comparisons to previous years..............................

9-5 9.2 Percent survival of juvenile and adult organisms impinged at the Brunswick Steam Electric Plant during slow-and fast-screen rotation, 1984 through 1986....................

9-6 9.3 Estimated survival of juvenile and adult organisms impinged at the Brunswick Steam Electric Plant durin slow-screen rotation in 1986.....................-...g 9-7 I

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u List of Figurci

.Fioure Pace i

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

1-4 1.2 River larval fish, entrainment, impingement, and water quality sampling locations in the Cape fear Estuary during 1986................................................

1-5 1.3 Marsh sampling areas and nekten sampling locations in the Cape Fear Estuary during 1986.......................

1-7 2.1 Bottom temperature for selected stations in the Cape Fear Estuary from September 1985 through December I

1986.......................................................

2-4 2.2 Bottom salinity for selected stations in the Cape Fear Estuary from September 1985 through December 1986.....

2-5 2.3 Mean daily freshwater flow by month and mean bottom I

salinity at midriver Station Hg 25 in the Cape Fear River, January 1984 through December 1986..................

2-6 3.1 Results of time-series analysis of total organisms I

collected in Dutchman Creek and Walden Creek, 1977 through 1986...............................................

3-8 I

3.2 Results of time-series analysis of spot collected in the lower and upper areas of the Cape Fear Estuary, 1977 through 1986..........................................

3-9 3.3 Results of time-series analysis of flounder collected I

in the lower and apper areas of the Cape Fear Estuary, 1977 through 1986..........................................

3-10 5.1 Results of time-series analysis for juvenile / adult spot collectt., 'n the intake canal by the nekton trawl from 1979 through 1986.....................................

5-13 5.2 Results of time-series analysis for juvenile / adult croaker collected in the intaFe canal by the nekton trawl from 1979 through 1986...............................

5-13 5.3 Results of time-series analysis for juvenile / adult Atlantic menhaden collected in the intake canal by the nekten trawl from 1979 through 1986....................

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List of Fiqures (continued)

Pace 5.4 Cumulative length-frequency analysis of spot collected l

by the nekten trawl inside and outside the fish diversion structure during 1986......................................

5-14 9.1 Mean monthly flow of water pumped at the Brunswick Steam l

Electric Plant, 1977 through 1982, 1984 through 1985, ad 1986.......................................................

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I Metric-EnglishConver'si'onTable length 1 micron (um) = 4.0 x 10-5 inch 1 millimeter fam) = 1000 um = 0.04 inch 1 centimeter (cm) = 10 mm = 0.39 inch 5-1 meter (m) = 100 cm = 3.28 feet 1 kilometer (km) = 1000 m = 0.62 mile I

Area I

2 1 square meter (m ) = 10.76 square feet 1 hectare = 10,000 m2 = 2.47 acres Weight 1 milligram (mg) = 3.5 x 10-5 ounci 1 gram (g) = 1000 mg = 0.035 ounce 1 kilogram (kg) = 1000 g 2.2 pounds Volume 1 milliliter (ml) = 0.034 fluid ounce 1 liter = 1000 ml = 0.26 gallan 1 cubic meter per second (cms) = 35.3 cubic feet per second Temperature Degrees Celsius ('C) = 5/9 ('F - 32) lI

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Executive Summary

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This report contains the results of biological monitoring conducted in the Cape fear Estuary near Carolina Power & Light Company's Rrunswick

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Steam Electric Plant during 1986.

Comparisons are made between results from 1986 and previous years.

Data collected during 1986 oh the various life stages of fish and 1

shellfish populations in the estuary continued to indicate that population trends and distributions were related to environmental variables, notably a decrease in freshwater flow.

The river larval fish study indicated that the overall abundances of summer species were higher than in the past, while overall abundances of winter species were lower; however, densities upriver for croaker increased indicating that migrating croaker were suc-cessfully transported an area beyond the influence of the plant.

Samples of the successive life stages in the tidal creeks indicated in 1986 as in 1985 that the spatial distributions of most species were re-i lated to riverine discharge which resulted in shif ts in populations from the lower to middle estuary.

These population shif ts over the last two yee.rs were generally responsible for several noticeable changes in trends in abundance over the past six years.

Large populations of selected species in Walden Creek and the upper estuary indicate that migrating organisms successfully immigrated to and resided in the middle and upper estuarine nursery areas.

Tne trends in abundance and the distributions of juvenile and adult fish in the estuary were also associated with the flow conditions.

AdditionaT studies indicated that plant intake modifications remained effective in reducing losses due to impingement and entrainment.

The diversion structure excludeo large organisms from the intake canal causing impingement to be reduced from prediversion years.

This is important in that these large individuals, having survived life stages with high natu-ral mortality rates, are or will soon be members of the reproducing popu-lations.

The number of total organisms impinged was high due to the installation of fine-mesh screens but the number of organisms entrained ix

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was much lower.

Laboratory survival studies indicated that substantial numbers of impinged organisms were returned. to the estuary alive which further reduced the impact of the plant.

Finally, the flow-minimization scheme, which was fully implemented in July 1983, continued to be effec-tive in reducing entrainment and impingement.

Data collected in 1986, as well as in previous years, indicate that g

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

Environmental conditions have been and continue to be the dominant force influencing the populations of organisms in the Cape Fear Estuary.

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1.0 INTRODUCTION

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

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

One stipulation of the permit was that biological moni-toring be conducted that would provide sufficient information to allow for a continuing assessment of the impact of the plant on the Cape Fear I

Estuary (CFE) witn particular emphasis on the marine fisheries. With some modification, this biological monitoring requirement was a continuation of research that had been conducted en the CFE by various investigsters since 19/6 and, as a result, some programs in this report will discuss trends l

from 1976 to 1986.

The program was modified in 1986 in an effort to optimize efficiency and analysis efforts while maintaining statistical credence and data con-tinuity.

A statistical technique known as power analysis was used to-I gether with analysis of variance and variance components analysis in this effort.

The power of a statistical test is the probability of obtaining

" significance" when testing a given hypothesis.

In linear models applied to factorial designs, there are many types of hypotheses including main effects and interactions.

Each hypothesis leads to a different F-test.

The power of a particular F-test (the probability that a particular F-statistic will exceed its critical value) is determined by the specific values for the groups' population means, their common within group vari-ance, and their sample sizes (Lohr and O'Brien 1985; 0'Brien and Lohr I

1985).

The power analysis used in the review of the BSEP biological sampling programs looked at station, depth, and similar comparisons.

In the ana-lysis, historical bSEP data was used to provide variance estimates.

A variance components analysis was run to determine the major sources of variation to aid in reaximizing the efficiency of the sampling design.

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I In general, this current report dra'wl from the 1985 report (CP&L 1986) and provides for a comparison to data contained in that report.

A summary of the 1386 biological program is presented in Table 1.1.

l Another stipulation of the permit was the installation of plant in-take modifications to reduce entrainment and impingement of estuarine organisms.

A permanent fish diversion structure was built across the mouth of the intake canal in November 1982 to prevent large fish and shellfish from entering the canal and from possible impingement at the g

plant (Figure 1.1).

The effectiveness of the structure is discussed in 5

the nekton and impingement sections of this report.

In addition, fine-mesh (1-m) screens were installed on two of the four intake traveling screen assemblies on each unit in June 1983 to reduce entrainment.

The l

effectiveness of this modification is addressed in the entrainment and larval impingement sections of this report.

In addition to these modifi-cations, the NPDES permit also required a reduction in the volume of cool-ing water used by the plant.

This reduction is discussed in the entrain-ment section.

The study periods evaluated in this report differ by program.

The entrainment and river larval fish programs report on data collected from September 1985 through Aucust 1986 to correspond to periods of larval recruitment.

The nekton, high marsh, survival, and impingement programs report on data collected from January through December 1986.

The sampling locations for the river larval fish, water quality, l

impingement, and entrainment programs are shown in Figure 1.2, while Fig-ure 1.3 shows the high marsh and nekton sampling locations.

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

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I Table 1.1 1986 Brunswick Steam Electric P1Ynt biological monitoring pro-

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gram summary.

Program Frequency Locations Water quality Once per week 11, 15, 19, 24, 25, 29, 35, 38, 42

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River larval fish Twice per calendar month 11, 18, 24, 25, 34 Marsh Seine Once every three weeks 12, 16, 22, 25, 31, 32 I

Trawl Once every three weeks 11, 15, 17, 21, 24, 27-28, 31-32, 42-43, 51 l

Nekten Once every three weeks 1, 2, 4-8, 10-12, 16 Entrainment Four times per calendar Discharge weir month Survival studies As needed Fish return flume and intake canal Impingement I

Juvenile and adult Twice per calendar month Fish return fiume Larval Four times per calendar Fish return fiume month I

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- Cape Fear Estuary during 1986.

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Figure 1.3 (continued) 1-8 E

H 2.0 WATER QUALITY L

2.1 Introd0ction r-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 in the abundances of species in a given area.

The yearly abundance of some estuarine organisms is also greatly affected by water temperatures (Schwartz et al.1979).

The water quality program was initiated in 1982 to supplement water temperature and salinity data for the river larval fish, marsh, and nekton programs in an attempt to better determine the effects of temperature and freshwater inflow.

The estuary is subject to highly variable inflows of freshwater from the Cape Fear River drainage basin.

The two-layered flow regime, typical of coastal plain estuaries, i: usually present in the portion of the estuary above Sunny Point (Figures 1.2 and 1.3).

Net nontidal drift 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 are constantly g

B being modified.

The portion of the estuary seaward of Sunny Point, in which the plant is located, is typical of a well-mixed marine system (Carpenter and Yonts 1979). Complex water circulation patterns, vigorous tidal action, and high-c.xchange ratios with the ocean result in this reach of the estuary acting as in extension of the nearby coastal zone.

2.2 Methods The same nine water quality stations have been sampled weekly since 1982 (Figure 1.2).

Water quality data were also collected every three weeks during the marsh and nekten programs (Figure 1.3).

Surface samples were dipped from the surf ace with a bucket, and bot-tom samples were collected with a Kemmerer water sampler.

Temperature was measured in degrees Celsius (*C) and salinity was measured in parts per thousand (ppt).

2-1

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I Bottom salinity and temperature valu~es were plotted for stations charscteristic of the various salinity regimes in both the CFR channel and

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creek systems.

The downriver station (Hg 15) is located near the mouth of tne river, the midriver station (Hg 25) is in the vicinity of Sunny Point, and the upriver station (Hg 38) is approximately eight miles north of the plant.

In Baldhead, Walden, and Alligator creeks, one station from the approximate midreaches of each creek was plotted for comparison.

2.3' Results and Discussion River channel and creek stations exhibited typical seasonal vari-ations in temperature during the year.

A maximum bottom temperature of

)

32.2*C was observed in early August, and a minimum bottom temperature of 2.8'C was noted on January 7 (Figure 2.1).

Both extremes were recorded in Baldhead Creek.

In the Cape fear Estuary, salinity typically declines during the winter months and increases from early spring through late summer (CP&L 1986).

This trend is a result of higher freshwater inflows (river dis-charge) during the winter and a reduction of. those f lows during the summer.

Decreases in salinity have been observed during late summer-early fall, a period typically exhibiting high salinity values.

These decreases in salinity can be attributed to the periodic occurrence of tropical dis-g turbances passing through the Cape Fear region.

However, these distur-E bances are normally short in duration and salinity quickly increases to previous levels.

In November 1985, the typical decline in salinity values was ob-served.

This decline, which lasted into early spring, coincided with the increase in freshwater inflow also noted during that time period (USGS river discharge data).

In August 1986, a slight decrease in salinity was l

observed in the river (Figure 2.2).

This decrease was much more pro-nounced in the creek systems, which are affected to a greater extent by local runoff.

In November 1986, salinity again began to decline as a result of the seasonal increases in river discharge.

Over the past three years, an overall decrease in freshwater inflow has been observed (Figure 2.3).

While the normal season-to-season l

2-2 l

I fluctuations were present, the total yea'rfy inf1w into the estuary has decreased since 1984.

These decreases resulted in higher salinity during 1985 as : opposed to 1984, while salinity in 1986 remained as high or higher than in 1985.

I Daily average inflow Year (cubic meters /second)

I 1984 369 1985 183 1986 95 The distribution of organisms in the estuary is largely influenced by changes in the temperature and salinity regime.

The effects of these changes are discussed in more detail in the following sections.

I I

I I

'I I

'I

..I I

1 2-3 l

I l,

River l

6 40' o

'$$h.k 4

i, 10' O

O',

l Oct Jon Apr Jul Oct Jan 3:

1985 1986 E

- Downriver l

coa Midriver

+++ Upriver I

Creek I

G40' g

E l

Y L

o-10' E

M 0, 2

Oct Jan Apr Jul Oct Jon l

1985 1986

• -** 8cidhead Creek oceWolden Creek

+++ Alligator Creek Figure 2.1 Bottom temperature for selected stations in the Cape Fear Estuary from a

September 1985 through December 1986.

E 2-4

I g

'l River 40' b,. -

s c

g

&30' n

J Yh, d

20 g

1510'

\\1 il p m

+

g 0'.

Oct Jcn Apr Jul Oct Jan g

1985 1986

• -** Downriver I'

00o Midriver

+++ Upriver Creek I

40' I

C e30'

~

a e.uq a

l N20' la.o\\

\\

p' 'n g

J 10'f,o f.ag..o%'*'i g R.u y.

.E

/

D.

0 I

04

'*'+***+ ".

Oct Jcn Apr Jul Oct Jon

.I 1985 1986 I.

m Baldhead Creek ocoWalden Creek

+++ Alligator Creek Figure 2.2 Bottom salinity for selected stations in the Cape Fear Estuary from g

September 1985 through December 1986.

2-5 I

M M

4

M go_5 4 ^ 2" M

u 0

5 0

5 0

5 0

2 2

1 1

~

^

nq.

h M

g J

u o

ta r

,E t

h c

yt

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i4 t

M n8 5=I-a1 i

9 l

s lu y

i J

6 mra M

o 8

u t

n t

9 o a

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1 J,

A n r a

M e

e v.

n m i )a Rt o

d a

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n ad a ee M

t hFg c

t r

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oph a

y a c rEEr=

mCs t

i in h

i yed M

l t

u 5

n b h r

.I la J

8 o

wt e

,a S

9 M

o nv i i 7-n r

r 1

5 p

r2S M

i A

e G

G t

27

~. 3 = E r:_Z a! S wI U n

hn(

w o

s o6 o

J ei8 m

rt l

f a9 u

F i-yt 1

Sr t

l c

i a re i

O deb ni m m

,I v

re ad c lu 4

eie J

8 MmD i

1' 9

m 1

JF

I r'

r 1

f y

p

\\'

\\

A 3

3, 2

e m

n r

g o.

ug J

0 0

0 0

0 0

0 0

0 0

F i

0 0

0 0

0 0

0 0

0 9

8 7

6 5

4 3

2 7Eo yS5'6U 8g g

1

~

g g

~a g

g

I 13% of all larvae collected.

These three ' genera are late spring and early summer estuarine spawners.

Their increased densities in 1986 may have been due, in part, to the low river flow during spawning (see Sec-tion 2.0).

This would have reduced the number of these species flushed from the estuary.

Croaker Micropogonias undulatus, spot Lelostomus xanthurus, and weakfisb I

Cynoscion regalls accounted for about 8% of all larvas collected. While the overall density cf croaker and spot in the estuary declined from previous years (Table 3.1), densities of croaker in the upriver stations (34 + 41) have increased and spot densities have not changed significantly l

(Table 3.2).

This may indicate that croaker and spot moved further up-river as a result of the low-flow conditions.

Weakfish densities in-creased in 1986.

Penaeus spp. postlarvae, brown shrimp Penaeus aztecus, pink shrimp P.

duorcrum, and white shrimp P. settferous accounted for about 2% of the total larval density in 1986.

Overall, Penaeus spp. postlarval densities were not substantially different from previous years.

Brown shrimp postlarvae usually enter the estuary from mid-February through mid-May followed by pink and white shrimp from late May through October (Copeland et al.

1979).

The mean monthly density of Penaeus spp, for the upriver stations 3

3 was about 40/1000m in April and aboct 75/1000m in August.

This indi-cated a large number of pink and white shrimp larvae in the upriver area which is supported by the large number of juvenile white shrimp collected I

in Alligator Creek during 1986 in the nekton and marsh sampling programs (Sections 4.0 and 5.0).

(

Portunid crab megalops Callinectes spp. accounted for about 1.5% of 3

the total larval density in 1986.

The annual mean density of 45/1000m is a substantial decrease from previous years (Table 3.1).

Fluctuations of l.

over 50% annually are ccmmon in catches of blue crab and can result from such variables as temperature and salinity patterns during recruitment (Leming and Johnson 1985).

Changes in salinity patterns due to low river I

flow during 1986 may have been responsible for some of the decline in portunid megalops.

There was also a decrease in the commercial catch of 3-3

I blue crab Collinectes sapidus from the CFR Yn 1985 (CP&L 1986) which may indicato a reduced spawning population that would have produced the 1986 megalops.

l Other species collected included Atlantic menhaden Brevoortia tyrannus, flounder Para!!chthys spp., and mullet Mugil cephalus and M. curema.

3.3.2 Time-SeriesAnalysis(Ten-yearTrends)

Studies of the transport of fish eggi. and larvae from the ocean to estuaries ha\\e been reviewed by Norcross and Shaw (1984).

They concluded that some of the f rs which cause fluctuations in abundance between years are spawning L.ess, transport mechanisms (wind and current), and water temperature and salinity.

Fluctuations in abundanc.e of larvae be-tween years are a natural and expected occurrence.

Long-term trends are therefore more useful in population evaluations.

The purpose of the time-series analysis was to identify temporal and spatial trends of larvae in the CFE during the past ten years.

Table 3.2 summarizes the results of the time-series analysis for selected species and total organisms at each station group:

Dutchman Creek (Station 11),

l Walden Creek (Station 24), the lower river (!tations 18 + 25 + 37), and the upper river (Stations 34 + 41).

The seasonal occurrence for sele ted species in 1986 was similar to previous reports (Copeland et al. 1979; CP&L 1982):

Spot late December through early May Croaker Early October through 14.te Arcil Portunid megalops late August through mid-December l

Flounder Late December through late March Hullet late December through late March Atlantic menhaden Late february through mid-May Penaeus spp. postlarvae

- brown Mid-February through mid-May

- pink and white Late May through early October Anchovy Late April through late October Weakfish Early May through mid-October Gobiosoma spp.

Early May through late October 3-4 E.

I 3.0 RIVER LARVAL FISH l

3.1 Introduction Sartpling continued to monitor the abundance, species composition, spatial distribution, and temporal distribution of larval and postlarval fish and shellfish in the C/E in 1986.

Data from 1986 were compared with I

data from previous years to quantify any significant changes in the num-bers of those organkms which utilized the CFE and which were susceptible to being " cropped

the operation of BSEP.

Population trends in Walden Creek were of particular interest 'ue to its proximity to the intake canal.

3.2 Methods 3.2.1 Sample Collection I

Simultanecus replicate samples were collected'at night from the sur-face and bottem at each of the seven stations (Figure 1.2).

A 1-m diam-eter 505-)m mesh net and a flowmeter were attached to each of the rectangular frames (Hodson et al. 1981).

These statior.s and gear have not changed since 1981.

I The variance component analysis, analysis of variance, and power analysis described in Section 1.0 indicated that only one surface and one I

bottom sample collected from each station twice per month was needed for madng compari'>ns of the abundance of larval /postlarval organisms. Nearly the same ability to detect differences could be obtained with this sam-pling regime as was obtained in previous years.

Therefore, only one of the two replicate surface and one of the two replicate bottom samples collected at each station per trip was analyzed.

The samples to be ana-lyzed were randomly selected.

I I

3-1

3.2.2 Data Analysis l

3 Larval densities (organisms /1000m ) were computed by expanding the volume of water filtered through the net and the corresponding number of organisms retained.

Application of the loge (density + 1) transformation g

to individual samples was used to normalize the data, a

for analyses, the 19861arval fish year began in September 1985 and continued through August 1986.

Data were subjected to time-series analy-sis to determine the periods of occurrence nf particular species and to detect any significant changes in abundance over the past ten years.

The data consisted of 12 observations each year where each observation was the mean of surf ace and bottom samples analyzed for a particular month.

Spa-tial differences were analyzed by averaging data from Stations 18, 25, and g

37 for the lower estuary and comparing these results to data averaged from E

Stations 34 and 41 in the upper estuary.

Station 24 (Walden Creek) data were compared to Station 11 (Dutchman Creek) data to detect possible changes in the utilization of Walden Creek due to its proximity to the intake of the BSEP.

The time-series model development is described in CP&L(1985a).

3.3 Results and Discussion a

S 3.3.1 Dominant Species Five families of fish Engraulidae, Atherinidae, Sciacnidae, Blennii-dae, and Gobiidae; ne family of shrimp Penaeidae; and one family of creb Portunidae have accounted for over 90% of the larval densities collected from the CFR in.the past.

In 1986 the most abundant taxa were similar to those of the previous five years (Table 3.1).

Bay ar hovy Anchoa mitchl!!!

and striped anchovy A. hepsetus densities increased and accounted for about 71% of all larvae collected in 1986.

From September 1979 through August 1982, bay anchovy constituted 95% of the anchovy collected (CP&L 1983).

Though the species were combined and listed as anchovy for this analysis, bay anchovy is still assumed to be the most abundant.

Gobies Gobiosoma spp. and Microgobius spp. densities also increased and accounted for about I

3-2 E-

I

~'

The time-series analpis also indicate's whether the abundance of a particular species increased or decreased significantly over time.

Results indicate that the st'undance of larval organisms has not changed significantly in Walden Crea, while recruitment of total larval organisms to Dutchman Creek has declined significantly (Table 3.2).

Although sta-tistical analysis indicates a significant decrease in Dutchman Creek, figure 3.1 shows that the decline gradually occurred during the past eight I

years.

Atlantic menhaden densities have declined in the river while in-creasing slightly in Walden Creek.

i Significant increases in the abundance of anchovy, croaker, Cobiosoma spp., weakfish, and Penceus spp. in the upper river stations shews that larvae are able to move past the int'ke of the plant and establish resi-dence in the upper estuary.

Spot lai se (Figure 3.2) decreased in all but the upper river stations of the estuary.

Flounder larvae (Figure 3.3) decreased in abundance at all station groups.

One explanation is that I

these larvae were able to move f arther up river than tht, upper mo-t sam-pling station due to reduced flow.

I 3.4 Summary and Conclusions The species composition and seasonal occurrence of larvae and post-l larvae in the CFE have not changed substantially during the past ten years.

Trends in the abundance of sore species (anchovy, croaker, mullet.

weakfish, and Penaeus spp.) have increased, while other species (flounder I

and spot) have decreased.

Studies have shown that some of the f actors responsible for year-to-yea, fluctuations include spawning success, trans-port mechanisms (wind and current), and water temperature and salinity.

There are probably many other f actors which contribute to the level of success of recruitment each year which have yet to be identified.

In 1986 the abundance of summer-spawned specier generally increased and winter species generally decreased.

This may be due, in part, to reduced fresh-water flow during the year which allowed the estuarine spawners to be retained in the estuary and other species to move f arther up the estuary I

than usual.

No reductions in the abundance of total larvae in Walden Creek or the upriver areas have occurred due to the operation of the BSEP.

I 3-5 I

3 Table 3.1 Annual mean density (organisms /1000 m ) and the percentage of the total mean density for the most abundant taxa collected in the river larval fish program,1981 through 1986 (based on ranking for the 1986 larval year).

1981 1982 1983 1984 1985 1966 Mean Mean Meais Hean Mean Mean Taxa density %

density %

density %

density %

density %

density %

Anchovy 585 34.4 722 35.8 614 41.6 578 47.5 1019 52.9 2196 71.0 2^.5 198 9.8 86 5.8 82 6.7 102 5.2 383 12.4 Gobiosoma spp.

434 2

Croaker 208 12.2 479 23.8 367 24.9 210 17.2 255 13.0 174 5.6 Penaeus spp.

52 3.1 54 2.7 75 5.1 63 5.2 88 4.5 66 2.1 Portuntd megalops 143 8.4 259 12.9 114 7.7 104 8.5 190 9.7 45 1.5 Spot 84 4.9 123 6.1 71 4.8 63 5.2 99 5.0 37 1.2 Weakfish 13 0.8 15 0.7 9

0.6 4

0.3 13 0.7 30 1.0 m

~

5 Microgobius spp.

5 0.3 5

0.2 5

0.3 7

0.6 6

0.3 23 0.7 Atlantic menhaden 43 2.5 13 0.6 19 1.3 20 1.6 13 0.7 10 0.3, 1

Other taxa 132 7.9 147 7.4 115 7.9 87 7.2 159 6.0 131 4.2 Total organisms 1699 100.0 2015 100.0 1475 100.0 1218 100.0 1964 100.0 3095 1C.6 s

EM M

M M

M E

M ME E

E E

E E

E E

E E

E

Table 3.2 Results of time-series analysis'for river larval fish data by station group indicating trends in density from 1977 through 1986.

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

2 2

Taxon

+/-

R2

+/-

R

+/-

R

.j.

g Anchovy

++**

0.98

+***

0.99

++++ 0.99

+***

0.98 I

Croaker

+***

0.97

+***

0.98 NS 0.99

+*

0.96 0.97 Flounder 0.98 0.97

• • • 0.98 0.98 NS 0.98

++*

0.99

+-**

0.97 Cobiosoma spp.

0.94 Atlantic menhaden NS 0.94

+*

0.96

• • • 0.96 Mullet

+**

0.96

+***

0.95 NS 0.96 NS 0.87 Weakfish NS 0.97

+***

0.98 NS 0.95

+***

0.97 0.99 0.99

• • • 0.99 NS 0.98 Spot Penaeus spp.

+***

0.97

+*

0.98

+*** 0.96

+***

0.96 Portunid megalops NS 0.98 NS 0.98

+*

0.98 NS 0.97 0.98 NS 0.96

+*

0.99 NS 0.96 Total organisms NS P > 0.05 0.01 < P $ 0.05 0.001 < P $ 0.01 P $ 0.001 Increasing trend

+

Decreasing trend 2

R icount of variation explained by the time-series model I

I 3-7

g 11' 10'

/

9 y

5 S'

., k b

bl d 6' 8

a 4' 2@3 2'

1' O',

iii>

78 79 80 81 82 83 84 85 86 87 Yeor

- OBSERVED

--- PREDICTED

~~ YEAR LML DUTCHMAN CREEK (STATION 11) 10' 9'

0' 0

k 7

,d.

'w g6 i,,

k5 o

E O4'

=3-1 l

22' 1'

O'r,

,,,,,,,,-r1 1

1 ii>>>'

78 M

80 81 82 63 84 85 86 87 Year

- OBSERVED

.-~ PREDICTEm

~. YEAR LEVEL E

WALDEN CREEK (STATION 24)

W Figure 3.1 Results of time series analysis of total organisms collected in Dutchman Creek and Walden Creek,1979 through 1986.

3-8 g

I 6

f 5

j j

)

I 4

I i

N

('

4 E

I 3

8 I

a

e 2'

g b

be

\\;

m.l L

M C

A 0<,,

1 v,

I 7

7 7

7 8

8 8

8 8

8 8

8 6

8 9

0 1

2 3

4 5

6 7

Year

- OBSERVED

--- PREDICTED

• • • YEAR LEWL LOWER ESTUARY, STATIONS 18,25,37)

I 6'

f 5

\\

i k

I x

l 5

4' 1

E 8

I 9-e 3 g

0a i

I 2

2' O

}

3

~.

~-

3 O.

, b,,

,, ' [',,,

, ', Y,,

, 9, ",.

I 7

7 7

7 8

8 8

8 8

8 8

8 6

7 8

9 0

1 2

3 4

5 6

7 Year

- OBSERVED

--- PREDICTED

~~ YEAR LEVEL l

UPPER ESn!ARY (STATIONS 34,41)

Figure 3.2 Results of time series analysis of spot collected in the lower and upper areas of the Cape Tear Estuary,1977 through 1986.

3-9 l

l l

=.

Il 4

7 3<

N E

h i

f I

2-A 8a a

h1 f

5 2:

a

..s, t e L J

' m

' 4,,......'N'"mle t

0 g

7 7

7 7

8 8

8 8

8 8

8 8

g 6

7 8

9 0

1 2

3 4

5 6

7 Year

- OBSERVED

--- PREDICTED

~. YEAR LEVEL E

LOWER ESTUARY (STATIONS 18, 25, 37) 5 I

4 -

I

~i 3

8

~.

I m

/

E UC 2' 5

/

I w

3 1

• s

)

s i

O'.,

L 7

7 7

7 8

8 8

8 8

8 8

8 l

6 7

8 9

0 1

2' 3

4 5

6 7

g Year

- OBSERVED

--- PREDICTED

.** YEAR LEVEL UPPER ESTUARY (STATIONS 34,41)

I Figure 3.3 Results of time series analysis of flounder collected in the lower and upper areas of the Cape Fear Estuary,1977 through 1986.

3 10

1 I

4.0 MARSH l

4.1 Introduction The marshes of the CFE provide nursery areas for many species of fish I

and shellfish.

It has been estimated that as much as 93% of the East Coast's commercial fish, shellfish, and sport fish spend at least a por-tion of their lives in estuaries (McHugh 1967).

Biological monitoring of the fish and shellfish populations in the marshes of the CFE was conducted to determine if the Brunswick Steam Electric Plant's use of estuarine water for cooling purposes has any adverse effect on their populations and distributicns.

Therefore, the seasonal distributions, spatial distribu-tions, and long-term trends in populations of selected fish and shellfish were investigated.

I The marsh study was modified in 1986 to improve the efficiency of the monitoring program.

Through variance component analysis, analysis of variance, and power analysis (see Section 1.0), it was determined that ll sampling of several trawl stations could be discontinued without sacrific-ing the quality of data.

I 4.2 Methods I

4.2.1 Station Description Baldhead Creek is located in the polyhaline (high-salinity) zone of the estuary adjacent to the mouth of the CFR (Figure 1.3).

Three of the seven trawl stations used in previous years were sampled in 1986.

The stations retained were located in the headwaters, in the midreaches, and near the mouth of the-creek.

Walden Cretk is situated in the downriver portion of the meschaline (medium-talinity) zone of the estuary near the plant's intake canal.

Four of the original nine trawl stations were re-I tained in 1986.

These stations were located in the headwaters, in the midreaches, near the mouth, and in Gum Log Branch adjacent to the return basin.

Mott's Bay is an oligohaline-meschaline (low-to-medium salinityi area well upriver from the plant.

No changes were made to the two tr.wl 41 I

h.

--&v y-9a-rri

I stations which were located on each side 'o'f' tha bay.

Alligator Creek is in the fresh oligohaline (low-salinity) zone cf the upper estuary near Wilmington.

Two of the original four trawl stations, one each in the upper and lower portions of the creek, were sampled in 1986.

As in the past, two seine stations were sampled in each of the creek systems except Alligator Creek.

One trawl station in the fish return g

basin wa$ also sampled.

Detailed descriptions of the marsh stations are a

presented in CPR (1982,198Sa).

I 4.2.2 Sampling Methods The 1986 sampling gears (trawl and seine), sampling methods, and laboratory procedures were identical to those used in previous years (CPt.L1982,1983,1984,198Sa,1986).

Discussions of seasonal and spatial distributions and trends are based on data gathered by the gear considered the most effective for each specits.

4;2.3 Data Analysis Recruitment periods were determined by examining the catch-per-unit-effort (CPUE) and mean lengths of each species by creek.

Lower identifi-cation cutoff limits were enforced at 20 mm for each of the penaeid shrimp 8

5 species and at 10 mm for blue crabs callinectes spp.

Shrimp and blue crabs below these size limits were identified to genus and family, respectively, due to difficulties in identifying these :ize organisms to lower taxonomic levels.

I Data collected from 1981 through 1986 were subjected to time-series l

analysis.

Data were transformed to loge (CPUE - 1) before analysis.

Due to large year-to-year variability, the top three to four periodicities in each year were fitted to 'he model.

This achieved the best fit and met t

the assumptions of independent and random errors. Significance of the upward or downward trends was determined at the P $ 0.05 level.

I 4-2 5

I

~

l 4.3 Results and Discussion 4.3.1 Dominant Species Ten species comprised 96.2% of the total trawl catch (Table 4.1).

Spot Lefostomus ranthurus was the numerically dominant organism collected, representing 48.5% of the total catch.

Spot was followed in abundance by grass shrimp Palaemonetes spp. (25.2%), bay anchovy Anchoa mitchfill (6.7%),

and brown shrimp Penaeus aztecus (6.4%).

The remaining 80 species made up 13.2% of the total catch.

With the exception of white shrimp Penaeus setiferus, the ten most abundant species collected in 1986.ere the same as those collected in 1985 (CP&L 1986).

Hodson (1979), Huish and Genghan (1979)

Weinstein (1979), and CP&L (1983,1984, 1985a) also reported that catches I

in the CFE over several years were generally dominated by these species.

Ten species comprised 96.1% of the total seine catch (Table 4.1).

As in previous years, grass shrimp was numerically dominant making up 64.9%

l of the total catch.

Grass shrimp was followed in abundance by spot (12.2%), mummichog fundulus heterociftus (4.4%), and Atlantic silverside MenIdla menidia (4.3%).

The remaining 66 species comprised 14.2% of the total catch.

The ten dominant species in 1986 were the same as in 1985 with the exception of white shrimp (C9&L 1986).

The dominant species collected with seines were similar to those collected in previous studies by Weinstein (1979) and CP&L (1983, 1984, 1985a).

4.3.2 Seasonal Distribution I

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

Increases in number and de-creases in mean size are related to the recruitment of most species.

I Generally, af ter recruitment ceases an increase in mean size and a de-crease in number becomes apparent.

During the several month residence and growth period, mos' species decline in number in the marshes due to emi-gration and natural mortality.

The seasonal and size distributions of selected species collected in 1986 followed these patterns.

4-3 I

1 I

The recruitment of Atlantic menhaden Wevoortia tyrannus, spot, striped mullet Alug!! cephalus, and southern flounder Paralichthys lethostigma peaked in the late winter and early spring.

The 1986 recruitment of croaker g

Afteropogonf as undulatus ard blue crab Collinectes sapidus began in the f all of 1985 and peaked during the following,3 ring.

Brown shrimp recruitment peaked in the spring, while the recruitment of white mullet Afugfl curema, bay anchovy, mummichog, Atlantic silverside, pink shrimp Pcnocu.s duorarum, and white shrimp peaked during the sumer.

These recruitment periods were similar to those observed in previous years (Weinstein et al.1980; CP&L 1984, 1985a. 1986).

l 4.3.3 Spatial Distribution l

The distribution of most es+uarine species is dependent upon many variables inherent to estuaries.

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

g footi availability (Lasker 1973), predation (Weinstein et al.1980; Wein-E stein and Walters 1981), salinity (Gunter 1961), and freshwater inflow (Rogers et al.1984).

Of these variables, salinity and freshwater inflow l

are probably the nost important in determining the utilization of a par-ticular area (creek system) in the CFE by migrating organisms.

l The CPUE by creek was used to determine the creek system that sup-ported the greatest abundance of each selected species in 1986 (Table 4.2).

Baldhead Creek is usucily a polyhaline system which ould g

support large populations of polyhaline species such as Atlantic silver.

E side, white mullet, and pink shrimp (Weinstein 1979). Atlantic silverside was most abundant in Baldhead Creek; however, white mullet and pink shrimp were more numerous in other portions of the estuary.

This is, possibly a result of higher salinities which made available more estuarine area in l

the suitable salinity range (Figure 2.2; Deegan and Day 1984).

Walden Creek, which is usual meschaline, supported the largest number of white mullet, a species considered tc be associated with more saline wate;' than that usually found in Walden Creek.

During recruitment of white mullet, however, the salinity in Walden Creek was higher than I

4-4 I'

usual, thus expanding suitable habitat arO supporting large numbers of this species (figure 2.2; Deegan and Day 1984).

Atlantic menhaden, mummichog, spot, striped mullet, and brewn shrico, typically asscciated with meschaline Zones, were most abundant in Walden Creek (Weinstein 1979).

Blue crab, which is usually related to oligohaline and meschaline I

zones, was about equally abundant in Walden and Alligator creeks.

Mott's Bay is generally oligohaline to meschaline depending upon the magnitude of riverine discharge.

Bay anchovy and pink shrimp.ere most abundant in Mott's Bay.

Juvenile bay anchovy are usually more abundant in the oligohaline and freschaline zones of estuarits (Jones et al.1978).

It was unusual to find large populatiens of pink shrimp in this part of the estuarine system.

These large numbers in Mott's Bay were probably the I

result of high salinities expanding suitable habitat.

Low riverine dis-charge in 1986 during the recruitment of pink shrimp increased the up.

stream movement of saline water effectively increasing the salinity regime I

in the middle to upper estuary.

Similar results were reported in 1985 when riverine discharge was also low (CPt.L 1986).

Alligator Creek is situated in the upper estuary and is usually fresh to oligohaline.

Croaker, southern flounder, and white shrimp, which are usually associated with low salinity, were most abundant in Alligator Creek.

Blue crab CPUE was similar in Alligator and Walden creeks.

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

The CPUE of brown shrimp and blue crab aas higher in the return basin than in any creek system.

Comparisons between the return basin and individual stations in Walden Creek indicated that the population abundances and the seasonal distributions of most species were similar to those of the upstream station.

These results indicate that the return basin was being utilized by transient organisms in the same manner as other upstream nursery habitats.

These results were simi-3 lar to those obtained by CPt.L (1985a).

N I

4-5 I

4.3.4 Time-Series Analysis Alligator Creek The abundance of spot and croaker in Alligator Creek increased sig-nificantly from W81 through 1986 (Table 4.3).

Combinations of low riverine discharge and higher estuarine salinities over tl.e past two years may have allowed these species to immigrate to the upper estuary in large numbers (Figure 2.3; CFLL 1985a, 1986).

No significirt change in the number of flounder occurred from 1981 through 1986; however, the abundance of flounder was high throughout the study period with a marked increase in 1985 (CP&t. 1986).

The catch of blue crab and Atlantic menhaden decreased significantly over the study period.

The decrease in the abundance of blue crab may be caused by changes in suitable habitats in this part of the estuary as a result of variations in riverine discharge and salinity within the estuary.

The abundance of Atlantic menhaden in the marshes and the river channel (Table 3.1) decreased substantia 11'y over most of the l

estuary in 1986, possibly due to poor larval recruitment to the estuary.

Time-series analysis could not be performed on brown, pink, and white shrimp data because no shrimp were collected in Alligator Creek in 1984 Catch data-indicate, however, that the abundance of each species of shrimp increased substantially in 1986.

Mott's Bay Fluctuations in catches of selected species occurred during the study period, but most species (spot, croaker, flounder, brown shrimp, pink shrimp, and blue crab) did not change significantly (Table 4.3).

Signifi-l cant decreases in the abundance of Atlantic menhaden, striped mullet, and white mullet did occur however.

The decrease in Atlantic menhaden, as in Alligator Creek, was probably related to poor larval recruitment during 1986 (Section 3.0).

The number of striped mullet collected in 1986 was g

s' Dar to that collected in 1985 but the higher catches during 1981 5

dused a decreasing trend.

The decreasing trend for white mullet probably resulted from the high abundance in Mott's Bay in 1981.

No white shrimp I

4-6 E

were collected in flott's Bay in 1984 whilh prevented the use of time-series analysis.

Catch data, however, indicate low catches with small fluctuations during the study period.

Walden Creek I

The abundance of flounder, brown shrimp, and white shrimp increased significantly in Walden Creek from 1981 through 1986 (Table 4.3).

High numbers of flounder collected in Walden Creek in 1983 and 1984 when river-l ine dischatge was high attributed to the significant increase (Figure 2.3 CP&L 1985a).

The significant increase in brown shrimp reflects the steady increase in catch from 1982 through 1986.

The' increasing trend for white shrimp was probably the result of high catches in 1986 preceded by several years of low catenes.

No significant change in the abundance of croaker, I

striped mu).et, white mullet, pink shrimp, or blue crab occurred during the study.

Atlantic taenhaden and spot decreased significantly from 1981 through 1986.

Decreases in riverine discharge probably influenced the spatial distribution of spot in the estuary by expanding the suitable habitat to the upper portions of the estuary (Figure 2.3).

Poor larval recruitment during 1986 probably caused the significant decreasing trend in the abundance of Atlantic menhaden in Walden Creek.

Baldhead Creek The abundance of spot, croaker, and brown shrimp in Baldhead Creek increased significantly during the study (fable 4.3).

Years with high riverine discharge resulted in high catches of these species in Baldhead l

Creek and the increasing trend (Figure 2.3; CP&L 1984,1985a).

The catch of these species was low in 1985 and 1986, possibly because these tran-sient species migrated further up the estuary.

The remaining selected species did not increase or decrease significantly from 1981 through 1986.

4.4 Sumary and Conclusions Species which have historically dominated atches in the marshes of the CFE were also dominant in 1986.

The spatial distributions of most 4-7 I

I species was related to riverine discharge'Tnd the salinity regimes within l,

the estuary.

The recruitment and distributions Of the selected species to Walden Creek and to the upper estuary indicate that migrating populations successfully immigrated to and resided in middle and upper estuarine nursery areas.

The seasonal distributions of the selected species were also associ-ated with the recruitment of the individual species.

These periods of recruitment in 1986 were similar to those in past years.

I The trends in abundance in each creek system wert associated with riverine discharge and salinity regimes.

Shif ts in populations of most species from one part of the estuary to another., as suitable habitats shifted, generally resulted in noticeable trends.

The return basin supported large numbers of many estuarine species.

The relative abundances and seasonal distributions of most selected species in the return basin were similar to those in upper Walden Creek.

These similarities indicate that the basin was being utilized as nursery l

habitat by many estuarine species.

The assoi:iation between trends in abundance and environmental vari-ables, as well as large nurttry populations in the vicinity of and up-en stream of the plant's intake canal, indicates that populations in the CTE are dependent upon natural phenomena and are not being adversely impacted by the Brunswick Steam Electric Plant.

I I

I 4-8 5m

Table 4.1 Total catch and percent total F the ten most abundant species collected in the marsh study during 1986.

Trawl Seine Species Catch Species catch Spot 48,833 48.5 Grass shrimp 56,388 64.9 Grass shrimp 25,382 25.2 Spot 10,L80 12.2 Bay anchovy 6,724 6.7 Mummichog 3,869 4.4 Brown shrimp 6,415

6. 4 Atlantic silverside 3,733 4.3 Croaker 3,514 3.5 White mullet 2,383 2.7 I

White shrimp 2,122 2.1 Brown shrimp 2,D9 2.5 Southern flounder 1,272 1.3 Stripeo mullet 1,344 1.6 Blue crab 1,199 1.2 Atlantic menhaden 1,249 1.4 Pink shrimp 750 0.7 Bay anchovy 1,003 1.2 I

Atlantic menhaden 581 0.6 White shrimp 791 0.9 Other species 3,803 3.8 Other species 3,388 3.9 I

Total 100,595 100.0 Total 86,937 100.0 Number of efforts 204 103 Table 4.2 Annual catch-per-unit-effort (CPUE) by creek system for 13 I

selected species in the marsh study during 1986.

Belchead Walden Mott's liigatei Retur1 Species Creek Creek,

Bay Creek Basii E

Atlantic menhaden 7

1 1

1 5

Bay anchov/

8 20 87 56 5

Mummicrog 13 100 1

Atlantic silyerside 76 27 6

I Spot 161 379 126 155 312 Croaker 2

3 31 59 10 Striped mullet 5

32 1

I White mullet 26 44 1

Southern flounder

<1

<1

<1 34 4

Brown shrimp 18 41 20 12 81 I

Hnk shrimp 2

5 6

2 4

White shrimp 1

14 1

33 1

Blue crab 5

7 4

7 8

ISeine _ sampi2s were not collected in Alligator Creek or the return basin I

I.

4-9

Table 4.3 Results of time-series analysis of marsh data by creek indicating trends in abundance from 1981 through 1986.

Alligator Creek Hott's Bay Waldea Creek 8aldhead Creek 2

2 2

2 Species Trend R

Trend R

Trend R

Trend R

Atlantic menhaden 0.79 0.82 0.93 NS 0.80 Spot

+*

0.84 NS.

0.90 0.94

+*

0.90 Croaker

+*

0.79 NS 0.82 NS 0.86

+*

0.67 Striped mullet NA 0.73 NS 0.81 NS 0.72 White mullet NA 0.80 HS 0.E13 NS 0.90 Flounder NS 0.97 NS 0.81 4*

0.8t' NS 0.80 Brown shrimp 10 NS 0.83

+***

0.96

+*

0.98 Pink shrimp ID NS 0.39 NS 0.90 NS 0.90 h

White shrimp ID ID

+*

0.97 NS 0.67 Blue crab 0.79 NS 0.75 NS 0.80 NS 0.78 MS P > 0.05 0.01 < P $ 0.05 0.001 < P 2 0.01 P 1 0.001 Increasing trend

+

Decreasing trend 10 Insufficient data NA Analysis is not appilcable because seine hauls were not made 2

R Amount of variation explained by the time-series model gg g

g g

m M

M MB M

M M

M M

E E

E

~

5.0 NEKTON S.1 introduction Various species of comercial fish and shellfish spend a portion of their first year in the CFE before migrating to the ocean as juvenile and i

adult members of the nekten community.

The objective of the nekton pro-gram was to determine if operation of the 8SEP had an adverse effect on populations of estuarine nekton by monitoring the species composition.

l spatial distribution, and relative yearly abundances of these nektonic organisms utilizing the CFE.

Catches at selected stations were also used to investigate the effectiveness of the fish diversion structure.

5.2 Methods Three changes were made to the nekton program in 1986 based on the variance components analysis, analysis of variance, 'and power analysis described in Section 1.0, Stations 13, 14, and 15 were discontinued leav-l ing 11 stations that extended from the freshwater drainage canal, approxi-mately 3.4 km west of Southport, to Alligator Creek, approximately 3.1 km west of Wilmington (Figure 1.3).

Secondly, replicate sampling was also discontinued so that each station was trawled once per trip instead of twice with the 6.4-m semiballoon otter trawl. The third change was to discontinue recording total weight for each taxon collected.

Detailed descriptions of sampling stations and methodology can be found in CP&L (1984).

Time-series analysis was employed to examine long-term trends in yearly abundance of selected species (CP&L 1985a).

Due to large year-to-year variability, the top four periodicities by year were fitted to the model.

This achieved the best fit and met the assumptions of independent and random errors.

Atlantic menhaden Brevoortia tyrannus, spot Lefostomus zanthurus, croaker Micropogonias undulatus, and weakfish Cynoscion regalis were placed into either the young-of-year (YOY) or juvenile / adult (J/A) size classes by examining their respective length-frequency distributions 5-1 I

m I

(Lagler 1952; Everhart and Youngs 1981; Ambrose 1983).

No size classifi-cation was made for bay anchovy Anchoa mitchfill, blue crabs Collinectes spp., and penaeid shrimp Penaeus spp.

The time-series analys's was per-formed on data from four areas in the estuary.

The lower river consisted of Stations 1, 4, 7, and 6 combined for 1979 through 1986.

Snow's Cut (Station 10), the upper river (Station 11), and Alligator Creek (Station

12) comprised the remaining three areas. The analysis for Snow's Cut, the g

upper river, and Alligator Creek was performed only for the years 1981 m

through 1986 since these stations were not sampled in 1979 and 1980.

Stations 2 and 16 were not included in any time. series analysis because of the lack of long-term data for these stations.

Selection of these areas was based upon the principle component analysis (CPt.L 1985a).

l An evaluation of the effectiveness of the fish diversion structure was based on catches at Stations 5 and 6 (inside the structure) compared to catches at Station 4 (outside the structure).

An analysis of variance was performed on the mean catch-per-unit-effort (CPUE) of J/A spot, croak-er, and Atlantic menhaden to examine spatial variability among Stations 4, 5, and 6 for the years 1979 through 1986.

Catches were divided into the preoperational and postoperhtional periods.

A significant station-by-date interaction would indicate a change in the abundance pattern inside to l

outside the fish diversion structure over time.

A time-serics analysis was performed on the cambined catches at stations inside the fish diver-E E

sion structure (5 and 6) from 1979 through 1986 to determine if there was a significant trend in catch.

A Kolmogorov-Smirnov two-sample test of cumulative length-frequency distributions of spot was employed to investi-gate size differences of spct inside and outside of the fish dhersion structure.

This analysis was not performed on the catches of J/A croaker and Atlantic menhaden due to the low numbers collected during 1086.

I A loge (CPUE+1) transformation was used in all analyses.

Signifi-cance was determined at the 0.05 level.

I 5-2 I

1 1

t l

5.3 Results and Discussion

~'

5.3.1 Total Organisms I

A total of 44,170 organisms representing 81 taxa was collected during 1986 (Table 5.1).

Bay anchovy, brown shrimp Penaeus aztecus, spot, white shrimp P. settferus, and croaker comprised 90.4% of the total catch.

Brief squid Lo!!Iguncula brevis, grass shrimp Palaernonetes spp., Atlantic menhaden, silver perch Bairdlella chrysoura, and blue crab Callinectes sapIdus comprised an additional 6.7% of the total catch.

These species have historically been among the dominant nekton species collected in the CFE (Birkhead et al. 1979; Schwartz et al. 1979; CPt.L 1980, 1982, 1983, 1984, 1985a, 1985b, 1986). The CPUE of white shrimp increased from 0.5 in 1985 to 9.2 in 1986.

I Schwartz et al. (1979) reported that white shrimp were among the more numerous invertebrates collected from 1974 though 1978.

Other or-ganisms which exhibited increases in CPUE from 1985 included bay anchovy, Atlantic menhaden, and silver perch.

Brown shrimp, spot, croaker, grass shrimp, and blue crab catches were lower than those in 1985.

5.3.2 Spatial Distribution I

';)y anchovy were collected throughout the estuary with a peak catch cccurEng in the lower river.

The highest catch of blue crab also occur-I rid iIt the lower river (Table 5.2).

Brown shrimp, white shrimp, and YOY spot were most abundant in Alligator Creek.

Juvenile / adult spot, croaker, and Atlantic menhaden were most abundant in Snow's Cut.

Young-of-year croaker were more abundant'in Snow's Cut and Alligator Creek.

The great-l est abundance of pink shrimp occurred in the lower river.

All species except for bay anchovy, blue crab, and pink shrimp were more abundant in either Snow's Cut, the upper river, or Alligator Creek.

These distribu-tions were likely the result of decreased freshwater inflow in 1986 during I

each species' respective recruitment period (Figure 2.3) (Copeland et al.

1979; Weinstein et al. 1979, 1980; Rogers et al. 1984).

Organisms were distributed by size in the CFE with smaller individ-uals being collected further up the estuary (Table 5.3).

There is a 5-3

I direct relat'onship between decreasing siYe' of organisms and decreasing salinity within the estuary and this relationship seems to be physiologic-ally related (Gunter 1961; Milgarese et al. 1982).

As organisms grow, their ability tn osmoregulate in low salinity (or freshwater) decreases and a movement down the estuary occurs.

5.3.3 Time-Series Analysis All species analyzed, except for the bay anchovy, exhibited signifi-cant decreases in abundance in the icwer river.

Four of these organisms exhibited trends in :ther areas of the estuary that were nonsignificant indicating that no major changes in overall abundance had occurred at these areas.

The brown shrimp catch exhibited a nonsignificant trend in the upper river.

The time-series analysis for this species at Alligator Creek could not be performed since none were collected in 1984 The fol-lowing shows that th' brown shrimp catch appears to have increased at this station from the bws of 1981 through 1984:

Year 1981 1982 1983 1984 1985 198,6 l

log,(CPUE+1) 0.43 0.30 0.64 0.00 1,62 1,46 e

This trend was most likely a result of reduced freshwater inflow during g

1985 and 1986 (Figure 2.3).

The yearly catch of white shrimp showed a similar trend at Alligator Creek going from zero in 1981 to 1.3 in 1986.

WFite shrimp, J/A croaker, and blue crabs exhibited nonsignificant trends at Snow's Cut or the upper river since 1981.

Species which exhibited decreasing trends in catch at all areas of the estuary analyzed include YOY and J/A spot YOY croaker, J/A Atlantic l

menhaden, pink shrimp, and YOY weakfish (Table 5.4).

These trends are l

likely the result of a combination of factors.

First, species distribu-tions are affected by changing environmental variables such as freshwater inflow and salinity (Birkhead et al.1979; Copeland et al.1979; Weinstein l

et al.1979,1080; Rogers et al. 1984).

Decreased freshwater inflow dur-

.ing 1985 and 1986 caused shif ts in some species' distributions to areas 5-4 g

I further up the estuary (Table 5.2; CP&L 1983).

These shifts in distribu-tions me.y have resulted in fewer individuals of some species being caught in the lower river.

Evidence for this is the yearly catches of YOY weak-fish and J/A menhaden in Alligator Creek.

Since none were collected there I

during one or more years, the time-series analysis could not be used.

However, the following table suggests that the yearly catches [mean loge (CPUE+1))ofbothspecieshaveincreasedfrom1981 levels:

Year 1981 1982 1983 1984 1985 1986 YOY weakfish 0.07 0.08 0.28 0.0 0.20 0.22 J/A menhaden 0.13 0.05 0.0 0.0 0.14 0.21 I

The following table i?lustrates that the annual log CPUE of J/A spot in g

the lower river and Snow's Cut has varied inversely with the average annual daily freshwater inflow since 1979.

The only exception was the lack of an increase in the CPUE of J/A spot in the lower river during l

1986.

This may have been a result of a shif t in the distribution of J/A spot to Snow's Cut due to the extremely low freshwatar inflow that year (Section5.3.2).

I Year

!.ocation 1979 1980 1981 1982 1983 1984 1985 1986 Lower river 0.63 1.28 1.53 1.34 1.34 0.35 0.49 0.26 Snow's Cut no data no data 1.29 1.06 1.09 0.05 0.31 0.63 l

Average daily freshwater inflow (CMS) 373 233

~43 287 337 '369 182 95 I

A second factor which may have influenced annual catches of

~

some I-species is changes in habitat at particular sampling stations.

All spe-cies collected in the nekten program, except for bay anchovy, have been closely associated with the deeper channel stations (CP&L 1985a).

Depth profiles indicated that Station 4, which was originally about 6.1 m deep, had silted in to a depth of about 2.4-3.0 m.

This may have negative 1, 5-5

I affected the abundance of some species such"as J/A spot, croaker, Atlantic l

menhaden, and pink shrimp which have historically been abundant at this station.

Additionally, this station was dredged to a depth of approxi-mately 5.5-6.1 m during December 1986.

Dredging activity may also have had a negative effect on the catches at this station during that month.

Copeland et al. (1974) noticed a decrease in the abundance of near-shore nekton during 1971 and attributed this decline to dredging activity.

5.3.4 Diversion Structure Evaluation I

Results of the analysis of variance indicated that a significant station-by-date interaction occurred for J/A spot.

This suggests that a l

difference in the spatial distribution of J/A spot had occurred over time due to the presence of the fish diversion structure.

The follewing table presents the mean loge (CPUE+1) of J/A spot collected at the intake canal stations during the preoperational and postoperational periods of the fish I

diversion structure:

u Station Outside inside Diversion structure status 4

5 6

l Preoperational 1.41 1.70 1.26 Postoperational 0.83 0.44 0.37 m

The catch was greater at Station 5 inside the intake canal than outside during the preoperational period.

The catch was greater outside during g

the postoperational period.

This result is even more evident considering E

the shift in distribution which occurred for J/A spot during 1986 (Table 5.2).

The annual catch at Station 4 wss extremely low during 1986 which had the effect of lowering the overall* mean postoperational catch.

Although this occurred, the station-by-date interaction was still signifi-I cant.

The station-by-dcte interaction was not significant for the catches of J/A croaker over time, although the following table suggests that a

reduction occurred:

I 5-6 E.

I

' ~ ~

Station Outsides Inside Diversion structure status 4

5 6

Preoperational 0.47 0.78 0.37 Postoperational 0.50 0.65 0.13 The postoperational catch increased slightly outside but decreased at both I

stations inside.

Failure of the catches at Station 5 to decrease below those of Station 4 was probably due to a large number of f ailed diversion l

screens in 1985 and the presence of some resident individuals insido the intake canal (CN L 1986).

I A significant station-by-date interaction did not occur for the catches of J/A Atlantic menhaden; however, catches have been significantly greater outside for the entire study period.

This was due to the presence of the temporary and permanent fish diversion structures (CP&L 1982, 1984, I

1985a,1986).

Further evidence that the fish diversion structure has decreased the relative abundance of larger fish in the intake canal is provided by the time-series analysis of J/A spot, croaker, and Atlantic menhaden catches inside the intake canal (Figures 5.1 through 5.3). A significant decreas-ing trend in catch occurred for spot and Atlantic menhaden from 1979 through 1986.

A nonsignificant trend in catch occurred for J/A croaker but this was the result of a low catch during 1979 (Figure 5.2) caused by I<

the presence of the temporary fish diversion structure.

Evidence for this is that a reduction in the density of croaker impinged during the early part of 1979 occurred when compared to previous years (CP&L 1982).

Since 1981, a general downward trend in year level catch for J/A croaker has occurred except for 1985 (Figure 5.2).

The increase in 1985 was probably due to a combination of a large number of failed diversion screens and the presence of some resident individuals in the intake canal (CP&L 1986).

Analysis of the cumulative length-frequency distributions of spot I

inside and outside of the fish diversion structure indicated that a greater proportion of larger spot were collected outside the fish

'~'

.l

l I

diversion structure (Figure 5.4).

ApproxMtely 32% of th :st outside the fish diversion structure were greater than 32 m.

Only 8% of the spot collected inside were greater than 32 m indicating that the fish diver-sion structure inhibited movement of larger fish into the intake canal.

5.4 Sum 6ry and Conclusions The dominant species collected in the nekten program during 1986 were similar to that collected since 1979.

Species composition has also been similar to that reported by other researchers for the CFE prior to 1979.

The spatial and size distributions of the dominant species collected I

during 1986 were probably related to environmental variables such as a

freshwater inflow.

Smaller individuals were more abundant upriver indi-cating that the plant did not limit upstream movement of organisms.

Bay anchovy exhibited increasing trends in abundance in all arcas of the CFE exr.ept Snow's Cut.

Brown shrimp, white shrimp, J/A croaker, and blue crab exhibited no significant change in abundance in at least one g

area of the estuary.

The yearly catches of brown shrimp and white shrimp 3

have increased at Alligator Creek.

Results of the time-series analysis indicated decreasing trends in abundance at all locations sampled for YOY spot, J/A spot. YOY croaker, J/A Atlantic menhaden, pink shrimp, and YOY weakfish.

These decreasing trends were probably the result of a combina-g tion of naturai f actors t,uch as changing environmental or habitat condi-E tions and the cyclic nature of some populations.

Evidence for this is that most of these organisms were more abundant at either Snow's Cut, the upper river, or Alligator Creek indicating that the operation of the plant did r'.; limit movement to these areas.

Although the time-series analysis g

could not be performed for YOY weakfish or J/A Atlantic menhaden catches a

in Alligator Creek, yearly catches of these two species have increased in l

this area since 1981.

Operation of the BSEP has not adversely affected populations of nek-tonic organisms residing in the CFE.

Changes that occurred were due to I

natural variation and not associcted with operation of the plant.

Fur.

ther, the fish diversion structure has been successful at inhibiting move-ment of large organisms into the intake canal.

I 5-8 I1

I Table 5.1 Totalnumber,percenttotalnumb"dr,andannualcatch-per-unit-effort (CPUE) of the ten most abundant species collected in the nekton study during 1986.

I i

I Percent Total of Species numt er total CPUE Bay anchovy 33,171 75,c 177.4 Brown shrimp 2,374 5.4 12.7 Spot 1,800 4.1 9.6 I

White shrimp 1,728 3.9 9.2 Croaker 843 1.9 4.5 Brief squid 806 1.8 4.3 I

Grass shrimp 766 1.7 4.1 Atlantic menhaden 694 1.6 3.7 Silver perch 397 0.9 2.1 Blue crab 306 0.7 1.6 Total I

(Tenmostabundant) 42,885 97.1 229.2 Other crganisms 1,285 2.9 7.0 Total organisms 44,170 100.0 236.2 I

I g

I I

5-9 I

Table 5.2 Annual catch-per-unit-effort (CPUE) oy station of selected organisms collected in the nekton study during 1986.

Station Lower Snow's Upper Alligator river Cut river Creek Species 1

2 4

7 8

ID -

11 16 12 Bay anchovy 492.4 152.4 394.1 183.8 191.8 44.4 220.2 92.3 15.9 Brown shrimp 5.0 0.0 1.7 1.1 1.1 1.1 5.8 1.2 54.3 l

Spot YGY 1.9 0.2 6.9 0.6 0.3 1.9 5.6 2.2 18.9 J/A 1.4 0.1 0.4 0.9 0.3

?.1 0.1 0.3 0.1 White shrimp 7.1 0.0 2.9 0.2 2.7 10.2 0.3 0.9 58.1 5

Croaker YOY 2.9 0.0 0.2 0.2 0.0 17.7 3.4 2.3 9.3 j

J/A 0.1 0.0 0.2 0.1 0.2 2.5 0.1 0.2 0.2 Atlantic menhaden J/A 0.5 0.0 0.3 0.4 0.0 33.9 2.6 0.5 1.1 Blue crab 0.5 0.2 3.7 0.7 1.5 2.1 2.0 1.0 2.5 Pink shrimp 2.1 0.1 1.3 1.5 0.6 1.2 0.4 0.2 0.9 Weakfish I

YOY 1.1 0.1 0.1 0.0 0.1 1.6 1.0 0.1 0.5 YOY = Young-of-year J/A = Juvenile / adult lm m

M M

M M

M M

M 6

m M

M M

M M

M M

I I

Table 5.3 Mean standard length (mm) isy location of selected species col-1ected in the nektan study during 1986.

I Species Lower river Snow's Cut Upper river A111oator Creek Bay anchevy 44 52 45 37 Brown shricip 80 93 77 53 Spot 76 97 37 42 Croaker 63 81 58 44 I

Atlantic menhaden 77 95 82 77 Blue crab 65 83 51 52 Pink shrimp 75 108 55 38 I

Weakfish 86 80 32 44 I

Lower river

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

= Station 10 Upper river

= Stations 11 and 16 combined Alligator Creek = Station 12 I

I I

I I

I I

I 5-11 I

~

Table 5.4 Results of time-series analysis.of nekton data by station group B

indicating long-term trends in relative abundance of selected g

species.

I Stajiengroup Lower rivert Snow's CutI Upper riverI AlligatorI Creek 1+4+7+8 10 11 12 2

2

+/-

R

.j, q2

1. f.

q2 Species

+/-

R l

Bay anchovy

+***

.87 NS

.83

+***

.89

+***

.83 Brown shrimp

.95

.81 NS

.88 ID Spot-m YOY

.91

• • • .83

.90

.90 g

J/A

.92

• • • .93

.91 10 White shrimp

.93 NS

.85

.87 ID Croaker YOY

.96

.87

.93

.92 J/A

.94 NS

.89

.91

'D Atlantic menhaden g

3 J/A

.92

.88

.78 ID Blue crabs

.87

• • • .88 NS

.82

.90 g

Pink shrimp

.91

• • • .90

.88 ID E

Weakfish YOY

.93

• • • .87

.86 ID NS P > C.05 5

0.01 < P 5 0.05 E

0.001 < P < 0.01 P $ 0.001

+=

Increasing Decreasing

=

ID =

Insufficient data YOY = Young-of-year J/A = Juvenile / adult R2=

Amount of variation explained by the model i

Results encompass the years 1979-1986 S

Results encompass the years 1981-1986 I

5-12 I

I I

4 6'

m 7

01 version I

w 5' 8 ** * " *P

o 4

I b

}( 3'A )...-4 1..k b

' I 2

3

?

l'

'f O h,,,,,,,,,,,,,,,... l.

l 79 80 81 82 83 84 85 86 87 Year l

- OBSERVED

- PREDICTED

-.= YEAR LEVEL I Figure 5.1 Re1ults of time-series analysis forjuvenile/ adult spot collected in the intake canal (Stations 5 and 6) by the nekton trawl from 1979 through 1986.

I 4'

. ONersion I

q Structure Completed w

E 3'

s t

" 2' l-l 8

{

5 n

,i m,

1-t

~

• }

',~

)

l i+-4 i.i 79 80 81 82 83 84 85 86 87 Year OBSERVED

---

PREDICTED

=== YEAR LEVEL Figure 5.2 Results of time. series analysis forjuvenile! adult croaker collected in the intake canal (Stations 5 and 6) by the nekton trawl from 1979 through 1986.

I 5-13 I

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79 80 81 82 83 84 85 86 87 Year

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- YEAR LEVEL Figure 5.3 Results of time-series analysis forjuvenile/ adult Atlantic menhaden collected in the intake canal (Stations 5 and 6) by the nekton trawl from 1979 through 1986.

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20 40 66 80 100 120 140 160 180 LENGTH (mm)

I Figure 5.4 Cumulative length-frequency analysis of spot collected by the nekton trawl inside n

(Stations 5 and 6) and outside (Station 4) the fish diversion structure during 1986.

g I

5-14

6.0 ENTRAINMENT l

6.1 Introductici)

Studies to determine the species composition, seasonality, and abun-dance of entrained larval and postlarval fish, penaeid shrimp, and portunid crabs at the BSEP have been conducted by CP&L as part of its I

long-term monitoring program since September 1978.

To determine reduc-tions in entrainment due to fine-mesh screens, a special study was con-ducted in April whereby samples were collected simultaneously f rom the 9.4-and 1-mm mesh screens.

in addition, the results of studies conducted l.

since July 1983 were used to determine the effectiveness of flow minimi-zation and fine-mesh screens in reducing entrainment.

I 6.2 Methods I

The collection gear and sampling methods have remained unchanged since 1982 (CP&L 1983).

The variance components analysis, analysis of variance, and power analysis (Section 1.0) indicated that a similar ability to detect significant changes in species abundance and composition could be obtained by analyzing only one of the two replicate samples collected.

Therefore, in 1986 one replicate was randomly selected and processed.

The remaining replicate was retained to ensure against loss of data.

I The special study samples were collected according to approved en-trainment sampling procedures with additional samples collected at 0600 and 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />.

Both replicates were processed.

These data were added to data collected during three previous studies to obtain percent reductions in entrainment numbers and densities (CP&L 1985a).

The density of organisms entrained was calculated the same as river larval fish densities (Section 3.2.2).

The densities of all samples col-I lected per sampling date were averaged to obtain a mean number per 1000m3 per day.

For the t he-series analysis, sample densities were transformed to loge (density + 1).

These transformed densities were then used to compute an average monthly density which was used in the analysis.

6-1

Three species of postlarval penacid sWimp were coikcted in entrain-l' ment, but because of the difficulty in accurately identiying them to species, they :were combined and reported as Penaeus spp. postlarvae.

However, those that occurred from late winter to spring were brown shrimp Penaeus aztecus and those that occurred from late spring to fall were a mixture of pink and white shrimp P. duorcrum and P. settferus, respectively (Cepeland et al. 1979).

I 6.3 Results and Discussion I

6.3.1 Dominant Species In 1986 the dominant organism entrained was Gobiosoma spp. which comprised 32.5% of the mean density of all organisms entrained.

Anchoa spp. ($ 12 m) (22.4%) was second most abundant and Atherinidae (12.4%)

was third.

Other entrained species, in decreasing order of abundance, were spot Leiostomus xanthurus, croaker Micropogonias undulatus, Penaeus spp.

postlarvae, bay anchovy Anchoa mitchfili, portunid megalops, Blenniidae, and Microgobius spp. (Table 6.1).

6.3.2 Seasonality and Abundance The seasonality or periods of abundance, as reported by density and Is number of organisms entrained, for the selected species analyzed were similar to those seen in previous years and correspcnded to the season-ality found in the river larval fish program (Section 3.3; Tables 6.2 and 6.3).

Since the installation of fine-mdsh 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 entrained, may not correspond to peaks observed in the river larval fish program.

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

In mid-September,- portunid megalops and pink and white shrimp had peak densities of about 343 and 310, respectively.

Croaker had a peak I

6-2 I

E. '

density of approximately 493 in early Dece5ber.

In late January, mullet

~

Mugil cephalus and M. curema had a peak density of approximately 17.

Peak densities of. 22, 62, and 623 were observed for flounder Paralichthys spp.,

brown shrimp, and spot, respectively, in early Ma~rch.

Atlantic menhaden Brevoortia tyrannus peaked at 118 in late March.

Anchovy Anchoa mitchfill and A. hepetus peaked at about 3048 in early May and seatrout Cynoscion regolfs and C. nebulosus at almost 31 in mid-May. Gobiosoma spp. had a peak I

abundance of approximately 2851 in early June (Table 6.2).

6.3.3 Number Entrained Entrainment rates were computed by multiplying the mean density per day by the mean flow per day.

The mean daily flow of cooling water 63 through the BSEP ranged from 1.4 x 10 m in mid-October to 5.1 x 10 m63 during July.

4 The daily rate of total organisms entrained ranged from 1.5 x 10 in 7

late December to approximately 2.4 x 10 in mid-May.

Portunid megalops 5

were entrained at a maximum rate of about 9.6 x 10 and pink and white 5

shrimp of about 8.7 x 10 --both in mid-September.

The maximum entrainment 6

rate of approximacely 1.1 x 10 for croaker occurred in early November.

4 In late January, mullet had a maximum rate of about 3.8 x 10.

During early March, spot and flounder had peak rates of approximately 9.2 x 105 4

and 2.0 x 10, respectively, while Atlantic menhaden peaked at about 1.8 x 5

10 in late March.

In early May, anchovy had a maximum entrainment rate 6

5 4

of 9.6 x 10 and peaks of 1.4 x 10 -and 9.7 x 10 occurred in mid-May for brown shrimp and seatrout, respectively.

Gobiosoma spp. had a maximum 6

rate of 10.6 x 10 in early June (Table 6.3).

6.3.4 Special Study for the four study periods combined, a t,tal of 659 organisms was collected through the 1-mm mesh screens for c mean density of 262.

A

, I total of 1968 organisms was collected through the 9.4-mm mesh screens for a mean density of 641.

These figures epresent a 66% reduction in numoer and a 59% reduction in mean density due to fine-mesh screens.

For the e.a 4

most abundant species collected, anchov'y' densities were reduced 60%,

croaker densities 88%, CobloncHus spp. densities 73%, portunid megalops densities 52%, spot densities 49%, and Penaeus spp. postlarvae densities 85%(Table 6.4) 6.3.5 Flow Minimization In June 1981, plant operations enacted a partial flow-minimization regime, whereby the amount of water withdrawn from the astuary for cooling purposes was reduced (CP&L 1985a).

In July 1983, a more drastic flow-reduction schedule was employed.

This schedule called for a maximum flow of 915 cubic feet per second (cfs) (25.9 cubic meters per second [ cms])

l during three-pumo 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 (approxime.tely the end of April),

three-pump operation was allowed--below that (approximately the end of November) only two-pump operation was used.

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

I To determine reductions in entrainment due to flow minimization, -a comparison using observed entrainment numbers was made between historical 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 the time periods encompassing two-pump operation and a maximum allowable flow of 605 cfs, the percent reduction was about 46% (CP&L 1985a).

I 6.3.6 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 dens-ities of selected species.

The data analyzed were collected from September 1980 through August 1986. This time period included three years I

6-4

.I

of - operation without fine-mesh screens and three years with fine-mesh screens.

Species selected had seasonalities coinciding with the November to April time period--the approximate period of two-pump operation when both traveling screens were equipped with fine mesh.

I The results show significant decreasing trends in densities of bay anchovy, portunid megalops, spot, croaker, and Penaeus spp. postlarvae (Table 6.5).

In comparison, the results of time-series analyses performed on the lower river stations in the river larval fish program show no sig-nificant trend in densities for croaker and a significant increasing trend for anchovy, Penaeus spp. postlarvae, and portunid megalops.

This indi-cates that fine-mesh screens were effective in significantly reducing the

~

entrainment densities of these species. Although the time-series analysis I

was performed on the combined species of anchovies for the river larval fish program, bay anchovy is by far the more dominant (Section3.3).

Therefore, the significant trend in the lower river is compared to bay anchovy in entrainment.

Spot showed a significant decreasing trend in densities in the lower river and in entrainment.

The decrease in the lower river is attributed to higher salinities (low freshwater inflow) during their oeriod of recruitment to the estuary (Figure 2.3) which ex-tended their habitat further upriver.

The decrease in entrainment can be attributed to both fine-mesh screens and a smaller population Liailable to be entrained.

6.4 Summary and Conclusions In 1986 studies were conducted to determine the species composition, seasonality, and abundance of entrained larval and postlarval fish, penaeid shrimp, and portunid crabs.

The results were also used to deter-mine the effectiveness of flow minimization and fine-mesh screens on-reducing entrainment.

The dominant organism entrained, as in previous years, was Gobiosoma spp. The seasonalities of all species reported remained the same.

E 6-5 l

i

I The special s' udy drigned to determin? reductions in entrainment due

~

t to fine-mesh screens showed a 66% reduction in number and a 59% reduction

~

in.'mean density of total organisms.

Estimates of the historical mean number entrained per day, based on observed values, were used to determine the reduction in entrainment due to flow minimization.

The percent reduction ranged from 28% to 46%, de-g pending on which flow-reduction regime was in effect.

m Results of the time-series analysis on the yearly mean densities of selected species entrained from September 1980 through August 1986 showed l

significant decreasing trends in densities of entrained bay anchovy, portunid megalops, spot, croaker, and Penaeus spp. postlarvae.

I I

I 9

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M Table 6.1 Mean density and percent total of fish, penaeld shrimp, and portunid crabs entrained at the 8SEP, September 1978 through August 1986..

September 1978'-

September 1983 -

September 1985 -

August 1983 August 1986 August 1986 Species Density Percent Density Percent Density Perce3 Gobiosoma spp.

373 22.0 289 30.5 308 32.5 Anchoa spp.

Atherinidae 191 11.3 141 14.9 212 22.4 61 3.6 139 14.6 117 12.4 Spot 164 9.7 69 7.3 57 6.0 Croaker 170 10.0 71 7.5 44 4.6 Penaeus spp. postlarvae 145 8.6 33 3.5 42 4.4 Bay. anchovy 177 10.5 57 6.0 37 3.9 Portunid megalops 235 13.9 36 3.8 24 2.6 e

81enniidae 13 0.8 21 2.3 24 2.5 4

Microgobius spp.

17 1.0 15 1.6 19 2.0 Other taxa 146 8.6 76 8.0 61 6.7 Total 1692 100.0 947 100.0 945 100.0

,1

l Table 6.2 Entrainment densities (nean per day) at the BSEP September 1985 through August 1986.

l Sample Total Atlantic Por %nid Gobiosoma dele organisms Croaker Flounder menhaden Hullet Shr isap Spc Anchovy megalops spp.

Seatrout l

04 Sep 85 168.45 0.00 0.00 0.00 0.00 34.37 0.00 51.30 25.07 18.86 3.12 11 Sep 85 510.13 0.00 0.00 0.00 0.00 47.15 0.00 249.66 17.59 f,6.89 0.00 18 Sep 85 1,022.68 8.98 0.00 0.00 0.00 309.89 0.00 80.75 342.89 129.61 0.00 25 Sep 85 216.02 3.36 0.00 0.00 0.00 24.11 0.00 90.%

17.57 17.65 0.00 02 Oct 85 108.61 0.00 0.00 0.00 0.00 39.15 0.00 15.66 24.08 15.15 0.00 09 Oct 85 103.27 4.59 0.00 0.00 0.00 21.41 0.00 12.82 37.44 6.36 0.00 16 Oct 85 239.71 13.31 0.00 0.00 0.00 43.97 0.00 20.55 126.04 9.73 0.00 23 Oct 85 124.94 53.32 0.00 0.00 0.00 34.27 0.00 20.11 11.73 5.50 0.00 06 Nov 85 565.06 286.85 0.00 0.00 0.00 41.28 0.00 42.36 179.35 0.00 0.00 13 Nov 85 169.7I 127.63 0.00 0.00 0.00 0.00 0.00 21.94 16.93 0.00 0.00 20 Nov 85 131.77 103.65 0.00 0.00 0.00 4.37 0.00 14.40 9.34 0.00 0.00 cn 26 % 85 382.03 348.95 0.00 0.00 0.00 3.50 0.00 19.60 0.00 0.00 0.00 03 Dec 85 208.80 195.39 0.00 0.00 0.00 0.00 0.00 9.00 0.00 0.00 0.00 1I Dec 85 545.07 492.51 0.00 0.00 0.00 0.00 0.00 32.93 0.00 0.00 0.00 18 Dec 85 230.05 195.50 4.57 5.00 0.00 0.00 0.00 20.14 0.00 0.00 0.03 26 Dec 85 10.47 5.88 0.00 0.00 4.59 0.00 0.00 0.00 0.00 0.00 0.00,

07 Jan 86 51.53 5.05 0.00 0.00 0.00 0.00 0.00 16.08 0.00 0.00 0.00,1 14 Jan 86 70.63 17.77 8.43 0.00 0.00 0.00 24.77 4.06 0.00 0.00 0.00 21 Jan 86 36.00 7.24 0.00 0.00 0.00 0.00 8.22 8.80 0.00 0.00 0.00 28 Jan 86 183.77 65.35 0.00 0.00 16,90 0.00 62.33 5.71 0.00 0.00 0.00 04 F eb 86 69.88 4.65 0.00 0.00 0.00 0.00 46.76 9.13 0.00 0.00 0.00 11 Feb 86 583.19 44.23 0.00 0.00 14.75 0.00 464.15 4.92 0.00 0.00 0.00 18 Feb 86 373.02 5.62 0.00 0.00 5.62 0.00 297.21 0.00 0.00 0.00 0.00 25 Feb 86 320.81 14.64 5.85 0.00 0.00 26.48 237.36 0.00 0.00 0.00 0.00 04 Mar 86 665.68 67.57 12.48 10.31 3.17 28.57 495.39 0.00 0.00 0.00 0.00 11 Mar 86 815.01 8.68 22.13 17.93 4.63 62.33 623.98 0.00 0.00 0.00 0.00 18 Mar 86 224.65 9.22 0.00 74.88 0.00 13.27 123.03 0.00 0.00 0.00 0.00 25 Mar 86 470.49 17.42 0.00 118.19 0.00 61.08 246.08 0.00 0.00 0.00 0.00 08 Apr *6 290.47 0.00 0.00 0.00 0.00 36.26 87.25 0.00 0.00 0.00 0.00 16 Apr 86 318.02 0.00 0.00 0.00 3.23 22.33 3.23 0.00 12.80 0.00 0.00 gg g

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4 Table 6.4 Reduction in entrainment by number"a'nd mean density (nurnber/1000m )

3 for most abundant species for four special study periods.

Numoer Mean density Percent Percent Species

9. 4- =1 1-mm reduction 9.4-mm 1-m reduction Anchovy 92 32 65%

30 12 60%

Croaker 705 71 90%

237 28 88%

g Coblone!!us spp.

92 24 74%

30 0

73%

W Portunid megalops 332 163 51%

118 57 52%

Spot 172 fl 04%

53 27 49%

l Penaeus spp. postlarvae 135 15 84%

41 6

85%

i Total organisms 1968 659 66%

641 262 59%

J 1

I Table 6.5 Results of time-series analytis of entrainment data indicating trends in dentity from September 1980 through August 1986.

2 Species

+/-

R Bay anchovy 0.98 5

Portunid megalops 0.99 g

Spot 0.95 Croaker 0.99 Penaeus spp. postlarvae 0.98 g

• • • P 5 0.001 Increasing trend

+

Decreasing trend 2

R Amount of variation explained by the model I

6-12 g

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l 7.0 SURVIVAL STUDIES 7.1 Introduction I

Survival studies continued to determine the percentage of organisms impinged on the traveling screens that were returned to the CFE alive in 1986.

These studies examined survival by species and size class during two intake traveling screen rotation speeds.

Emphasis during 1986 was directed towards those species-and size classes that were either not examined or exhibited fluctuations in survival during 1984 and 1985.

7.2 Methods 7.2.1 Collection Impinged organisms were washed from the traveling screens into a return fiume.

Collections were made at the end of t'he 1200-m-long flume where it empties into a 3.2-hectare return basin (Figure 1.1).

Postlarval and smaller juveniles were collected with a larval table similar to one used by McGroddy and Wyman (1977) and described in CP&L (1985a).

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 flume.

I The collecting gears and methodologies for control organisms were unchanged from 1985.

Postlarval and small juvenile organisms were col-I lected with a 1-m diameter, 1-mm mesh net with an oversized " plankton bucket" t.ttached.

Larger juvenile and adult organisms were collected with l

either a 3.2-m two-seem trawl or a 6.4-m semiballoon bottom trawl.

Con-trol organisms were collected from tne intake canal without regard for tidal _or lunar stages.

For further discussion of gears and methodologies, refer to CP&L (1985a).

1 I

7-1

I 7.2.2 Stocking and Monitoring l

Stocking and monitoring of organisms remained unchanged from 1985.

l Targeted organisms were sorted by species and size class.

The live organ -

isms were stocked in tanks and the 96-hour holding period initiated.

All dead organisms were counted and up to 50 were measured.

The stocked organisms were ocnitored hourly, and all dead organisms were removed and

~

g meisured.

Temperature and salinity were checked periodically throughout a

the study.

After 96' hours, the tanks were drained and all live and dead organisms were counted and measured.

All organisms were measured to the nearest millimeter (m).

Finfish were measured in standard length (SL),

penacid shrimp in total length (TL), and blue cratas in carapace width (CW).

The taxonomic level for identification often depended on the size class of the organisms.

When identification to a lower level might pro-duce additional stress on the organism, identification was only made to the family or generic level.

This included penaeid shrimp juveniles from one date during October.

Also, all postlarval penaeids. Paralichthys, and Gobionellus collected were only identified to the generic level.

The continuously rotating intake traveling screens were operated at one of two different rotation speeds depending on operating conditions of E

B the plant.

The slower rotation was approximately 75 cm/ minute, while the faster rotation was between 187 and 200 cm/ minute.

Whenever possible, organisms were collected from both screen speeds during the same date to evaluate any differences in survival due to screen speed.

This was some-times impossible due to either a shortage of tank space, plant operating conditions, or time constraints.

An effort was made to fill in the largest gap in the data for that particular species, size class, and l

screen speed whenever this occurred.

l I

I I

l 7-2 g

T

~'

7.2.3 Def'nitions and Calculations Those organisms that -ied befcre reaching the laboratory accounted for initial mortality, while latent mortality consisted of those organisms that died after stocking.

Total mortality is the summation of both.

The percent total mortality and the percent survival were calculated using the following formulae:

I Percent total mortality =

Initial mortality + latene mortality x 100 Number of organisms collected Percent survival = 100 - Percent total mortality Occasionally more live organisms were collected than could be stocked.

In those cases, the latent mortality percentages were applied to all live organisms prior to the calculation of parcent total martality.

I In assessing any stress-related effects on postlarval and juvenile I

orpnisms, special handling methods and/or acclimation perioos are usually required (Hoss et al. 1974).

Collection, handling, holding, and/or g

natural mortality often result in a reduced survival prior to and during B

experimental evaluations.

Control organisms were collected and held as a measure of this reduced survival and to indicate the hardiness of the particular organisms evaluated.

The survival percentages obtained frem those centrols are presented along with the experimental percentages, but no adjustments were made to the results of the experimental organisms for any mortality observed among the control organisms.

7.3 Results and Discussion 7.3.1 Total Organisms Twelve survival studies were conducted during 1986 resulting in the examination of 15 different taxa (Tables 7.1, 7.2, and 7.3).

Included among those 15 taxa were members of the drum, mullet, herring, flounder, shrimp, crab, anchovy, jack, and goby families.

E 7-3

I 7.3.2 Species Accounts Selected Finfish The survival of five commercially important finfish was examined during 1986.

They were spot Leiostomus xanthurus, croaker Micropogonias undulatus, striped mullet Mugil cephalus, Atlantic menhaden Brevoortia tyrannus, and flounder Paralichthys spp. (Table 7.1).

Several size classes of these organisms were not examined in previous years; therefore, 1986 data provided additional information needed to accurately estimate the overall survival of these selected species impinged at the BSEP.

I Spot with mean standard lengths ranging between 15 and 45 mm were held en four dates (Table 7.1).

Survival increased as mean length increased.

Survival also increased when the impingement duration decreased (the faster screen rotation reduced the time impinged on the screens).

Survival ranged from zero to 19.4% during slow-screen rotation and 13.4% to 60.4% during f ast-screen rotation.

The control organisms g

also displayed the same trend of increased survival with increased size.

E suggesting that the collecting and holding of spot contributed to a degree of the mortality according to size class examined.

The survival of croaker was determined for fish with mean lengths of 14 and 24 mm (Table 7.1).

The smaller size class, collected during the slow-screen rotation, had a survival of approximately 19%.

The results of control croaker for this size class indicated a mean survival near 74%.

The 24-mm size class, collected during f ast-screen rotation, displayed g

survival over 86%.

The hardiness of this size class of croaker was evi-5 dent when 100% of the controls survived.

4 Striped mullet had poor survival (4.9%) during the one trip that they were collected (Table 7.1).

Results from last year indicated approxi-mately 70% of the striped mullet survived (CP&L 1986).

These mullet (23-mm mean length) were collected during slow-screen rotation.

No con-trol striped mullet were collected; therefore, no indication as to the condition of this mullet population prior to impingement was available.

7-4 g

I

~

Young Atlantic menhaden collected during March ranged in size between 19 and 31 mm and did not show any survival from either screen speed (Table 7.2). However, controls also showed low survival (17.1%) which indicated the fragility of this species.

Flounder were collected only during fast-screen rotation on one date (Table 7.1).

The survival of these flounder (52-mm mean length) was approximately 71%.

The 94% survival of the controls emphasized the hardiness of this size class of ficunder.

Consequently, little mortality was attributed to the handling and holding of these organisms.

Selected Shellfish The survival of Penaeus spp. postlarvae

(< 20 mm), brown shrimp Penaeus aztec Is, pink shrimp P. duorarum, white shrimp P. settferus, and Penaeus spp. juveniles was examined.

Survival determination of blue crabs Callinectes spp, was also conducted on one date (Table 7.2).

v Postlarval shrimp averaged 11 and 12 mm for the two dates they were collected (Table 7.2).

The first trial indicated survival was approxi-mately 82% for both screen speeds.

Control survival for this date was I

about 77% and indicated that much of the mortality observed was attributed to handling and holding the organisms.

A high initial mortality was observed during this date.

On the second date, experimental survival was near 95%.

These organisms were collected during f ast-screen rotation.

Survival of control organisms also improved to over 98% which suggested little mortality was induced by handling and holding.

Freshwater flow in the river was substantially higher during the first date; consequently, the salinity changed from 12 ppt in March to 21 ppt in April (Section 2).

The lower salinity may have stressed the postlarval shrimp and I

resulted in the lower survival.

Brown shrimp survival was determined for two size classes held on two separate dates--both of which involved f ast-screen rotation (Table 7.2).

The survival of 43-mm brown shrimp was about 97%, while survival of the larger size class (76-mm mean length) was approximately 94%,

Survival of I

7-5 I

controls for both size classes was lower tIIan for the cxperimentals which

~

suggested the impingement process contributed little erest on the organ-isms.

Pink shrimp were collected once during the f ast-screen rotation.

They averaged 113 mm and exhibited survival over 97% (Table 7.2).

The survival of control pink shrimp, as for brown shrimp, was lower than tiie experimental shrimp which again suggested little mortality due to the impingement and return process.

White shrimp, the dominant fall species, was held during three dates h

in September with two trials involving fast-screen rotation and one involving slow-screen rotation (Table 7.2).

The smallest size class (77-mm mean length) was collected during f ast-screen rotation and showed survival near 97%.

The next size class (104-mm mean length) displayed survival of 854.

Survival of the largest size class (114-m mean length) collected during slow-screen rotation was about 91%.

Control results indicated varying degrees of survival ranging between 80% and 100%.

During October, both juvenile pink and brown shrimp were abundant in the impingement samples.

Difficulty in positive identification without added stress resulted in these shrimp being held together and identified only to the generic level (Table 7.2).

Results of these juvenile Penaeus spp. (66-mm mean length) indicated survival was approximately 91% during fast-screen rotation.

Controls showed no mortality.

The juvenile blue crabs held averaged 22 mm and had 100% survival on E

fast-screen rotation (Table 7.2).

Survival of control blue crabs was also ur high at 95%.

Therefore, no mortality could be related to impingement of blue crabs.

Miscellaneous Species The miscellaneous species examined included bay anchovy Anchoa mitchilli, goby Gobionellus spp., permit Trachinotus falcatus, and crevalle jack Caranx hippos (Table 7.3).

All were collected during f ast-screen 7-6 5

'I i

Table 7.3 Mean percent 96-hour unadjuste3 survival values for miscel-

~

laneous species held during survival studies at the BSEP during 1986.

jj Mean percent survival N

Size (SL)

Experimenta13 Contr_o1 Species Date Range (mm)

Mean (mm) Slow Fast Bay anchovy January 6 27-54 37 1.1 75.4 March 3 32-54 43 4.9 77.4 I

Gobionellus spp.

April 7 8-18 14 15.6 Permit October 13 11-15 13 84.7 Crevalle jack October 13 11-30 24 36.1 1

I J

• Indicates relative speed of screen rotation.

I

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7-11

Table 7.4 Survival percentages for organisms collected during fast-screen rotation at the BSEP from 1984 through 1986.

Number Percent Initial Latent Total Taxa Trials Collected Stocked mortalityi mortalityS E

survival

-Croaker 23 3832 1802 36.9 47.8 32.9 Spot 12 1852 826 19.7 62.6 30.1 Penaeus spp. Juveniles 7

302 257 1.7 5.8 92.6 Penaeus spp. postlarvae 4

482 241 3.3 6.6 90.3 Brown shrimp 6

239 12 3.3 12.0 85.1 White shrimp 2

86 79 0.0 8.9 91.1 Pink shrimp 1

36 35 2.8 0.0 97.2 Hardback shrimp 1

33 29 12.1 10.3 78.8 Blue crabs 6

213 121 1.9 5.0 93.2 Blue crab megalops 2

159 71 1.9 11.3 87.0 7

Bay anchovy 4

394 215 40.1 97.7 1.4 C

Weakfish 4

282 191 29.4 82.2 12.6 Searobin 4

132 124 2.3 8.1 89.8 Striped mullet 3

113 96 15.0 15.6 71.7 Blackcheek tonguefish 3

110 95 5.5 15.8 79.6 Flounder 2

98 84 9.2 2.4 88.7 j

Goby 2

477 0

100.0 0.0 iAtlantic menhaden 2

212 90 13.7 94.4 4.8 cobio.ne11os spp.

I 117 64 45.3 71.9 15.4 Permit 1

27 26 3.7 11.5 85.2

'Crevalle jack 1

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

SNumber of organisms that died after being stocked in tanks + number stocked.

5100 - l(t) (Number collected) + ( ) (Number stocked) + ( ) (Other live organisms collected but not stocked)) + number collected.

SM M

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E

I Table 7.1 Mean percent 96-hour unadjuste'd' survival values for selected finfish held during survival studies at the BSEP during 1986.

Mean percent survival Size (SL)

Experimentaf Control Species Date Range (mm)

Mean (mm). Slow fast Spot February 3 11-18 15 C.0 13.4 52.7 February 17 13-23 IF

.1 14.3 78.0 March 3 14-26 2.

19.4 37.8 85.3 May 19 25-60 4;

60.4 85.3 I

Croaker January 6 9-25 14 18.9 73.9 February 3 M 33 24 86.3 100.0 Striped I

~

mullet Marcl 17 1?-29 23 4.9 Atlantic menhaden March 17 19-31 26 0.0 0.0 17.1 I

Flounder May 19 38-68 52 71.4 94.4 I

I Indicates relative speed of screen rotation.

I I

I I

I 7-9

Table 7.2 Mean percent 96-hour unadjusthiP survival values for selected shellfish held during survival studies at the BSEP during 1986.

~

tean percent survival j

Size (SL)

Experimenta1I Control Species Date Range (mm)

Mean (mm)

Slow fast Penaeus spp. March 17 9-15 12 82.8 82.7 76.9 postlarvae April 7 8-13 11 95.0 98.3 I

Brown shriap May 19 31-58 43 97.4 71.6 g

June 2 47-95 77 93.8 89.7 Pink shrimp June 2 92-133 113 97.2 76.5 White shrimp September 8 52-131 104 85.0 90.2 September 15 41-126 77 97.2 80.6 September 29 46-146 115 91.3 100.0 Penaeus spp.

juveniles October 13 28-93 66 91.5 100.0 m

I Blue crab June 2 13-42 22 100.0 95.0 I

% ndicates relative speed of screen rotation.

I I

I I

1 7-10 I

I rotation with an additional date during slow-screen rotation for~ the bay anchovy.

Controls were only collected. for the Day anchovy due to low densities of the other species in the intake canal.

I.

Limited survival was seen for the 37-mm bay anchovies collected during slow-screen rotation (Table 7.3).

Only 1% uf this si:e class survived.

Similarly, approximately 5% of the 42-m bay anchovies that were impinged during fast-screen rotation survived.

Control results indi-cated that 23% to 25% of this mortality was associated with the bandling and holding of this fragile species (survival ranged between 75% and 77%).

I The survival of Cobionellus spp. was examined only once during f ast-screen rotation (Table 7.3).

These 14-mm fish displayed survival slightly under 16%.

Two other miscellaneous species, the permit and crevalle jack, I

displayed approximately 85% and 36% survival, respectively.

7.3.3 Three-Year Estimates Survival values for all species were determined from data collected over the last tPee years (Tables 7.4, 7.5, and 7.6).

Consistently over 80% of the shellfish impinged survived regardless of the screen speed from which they were collected.

These included blue crabs, the three com-mercially important penaeid shrimp

species, and all life stages I

examined.

Croaker and spot survival was approximately 30% during fast-screen rotation and approximately 16% and 11%, respectively, during slow-screen rotation.

Bay anchovy, goby, and Atlantic menhaden showed little if any survival from either screen speed.

Overall, values remained unchanged from the estimates obtained from the 1984 and 1985 data (CP&L 1986).

I 7.4 Summary and Conclusions The survival of specific size classes for 15 taxa was determined during 1988 Species and size classes missing from previous years were added in 1986.

Results of 44-mm spot indicated survival was approximately 60%, while the 24-mm croaker exhibited survival over 86%.

The 1986 I

7-7 I

I resultson'twofragilespeciesindicatediulvivaiwaspossibit. Cobfonellus spp.,

which had not previously been examined, displayed almest 15%

survival, while the bay anchovy indicated that between 1% and 5% survival was possible.

Two other species were examined in 1986.

These were the permit and crevalle jack which exhibited approximata survival of 85% and 36%, respectively.

Penacid shrimp survival was determined for all three indivilual species in 1986, where in the past they were occasionally com-bined.

Sur.*1 val for the individual species was as high as the combined taxa.

Survival percentages from the past three years substantiated those percentages reported in 1986 which used data from the first two years.

Shellfish show high survival regardless of species and life stage, whereas finfish survival is species and size class-specific.

l l

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l M

M M

M M

M M

M M

m M

M-M M

W M

M M

M 1

I Table 7.5 Survival percentages for organisms collected during slow-screen rotation at the BSEP from 1984 through 1986.

1 Number Percent i

Initial Latent Total T4xa Trials Collected Stocked morta11tyi mortality 5 surviva15 Croaker 20 3058 1403 47.4 69.5 16.0 Spot 15 2728 1167 37.2 82.3 11.1 renaeus spp. Juveniles 2

100 91 9.0 14.3 78,0 cenaeus spp. postlarvae 3

. 612 181 6.9 13.8 80.3 Brown shrin:p 5

350 336 2.9 6.5 90 8 l

White shrimp 1

44 30 2.3 6.7 91.2

. Hardback shrimp 3

452 151 44.9 16.6 46.0 Blue crabs 3

71

~1 2.8 3.3 94.0 Blue crab megalops 2

203 135 3.0 11.1 86.3 7

Bay anchovy 2

955 141 81.8 98.6 0.3 C

Striped mullet 1

165 6

63.0 86.9 4.8 Goby 1

203 0

100.0 0.0 Silv "'de 1

59 0

100.0 0.0 P l. r.

,d fflefIsh 1

33 31 6.1 25.8 69.7 Atiantic menhaden 1

108 60 20.4 100.0 0.0

,1 INumb *e d aeganisms that were dead in collection gear + nu:rber collected.

SNumber of organisms that cled af ter being stocked in tanks + number stocked.

5100 - [(*) (number collected) + (5) (number stocked) + (5) (other live organts:ns collected but not stocked)] + romber collected.

i

Table 7.6 Survival percentages for control organisms collected for survival studies at the BSEP from 1984.

through 1986.

Number Percent Initial Latent Total i

Taxa Trials Collected Stocked mortality morta11tyS survival 5 Croaker,

28 4234 1919 5.8 7.6 87.1 Spot 19 2918 1430 4.3 11.6 84.6 renaeus spp. Juveniles 9

658 429 2.3 4.4 93.4 renaeus postlarvae 4

392 232 3.6 7.3 89.4 Brown shrimp 11 1171 531 2.6 18.3 79.6 Whitc shrimp

?

182 113 2.2 7.1 90.9 Pir,k shrimp a

34 34 0.0 23.5 76.5 Hardback shrimp 3

1032 156 4.6 6.4 89.3 y

Blue crabs 10 434 197 1.6 6.6 91.9 Blue crab megalops 4

362 231 7.2 7.4 86.0 Bay anchovy 5

356 258 8.1 20.2 13.3 Weakfish 3

155 116 3.2 40.5 54.1 Searobin 4

104 97 1.9 1.0

'7.1 Striped Mullet 2

58 58 0.0 1.7 98.3 Blackcheek tonguefIsh 4

475 146 0.2 2.1 98.4 flounder 2

39 38 2.6 2.6 94.9 1

AtiantIc menhaden 1

35 29 17.I 79.3 17.1 I Number of organisms that were dead in collection gear + number collected.

INumber of organisms that died af ter being stocked in tanks + number stocked.)

5100 - l(t) (numer collected) + (1) (number stocked) + (5) (other live organisms collected but not stocked)] + number collected.

gg g

m m

m W

m M

M M

M M

M M

M M

M M

M

8.0

!MP!NGEMENT (Larval) 8.1 Introduction With the initiation of fine-mesh screen operation, many of the larval and postlarval fish, penacid shrimp, and portunid crabs that previously would have been entrained were instead impinged and returned to the CFE.

I The larval impingement program began in January 1984 to provide an esti-mate of the total number of larvae and postlarvae being impinged.

Survi-val percentages applied to these estimated numbers gave an assessment of the success of fine-mesh screens and the fish return system for returning l

larval organisms to the estuary alive.

8.2 Methods I

During 1986 the sampling gear and collection method for larval im-pingement remained the same as in previous years (CPt.L 1986).

The vari-ance component analysis, analysis of variance, and power analysis (Section 1.0) determined that two 5-minute samples (one daytime and one nighttime) collected weekly (four times per month) could adequately detect any sig-nificant changes in the species composition and estimate of the total larvae and postlarvae being impinged.

However, replicates were collected to ensure against loss of data.

I Due to the large number of organisms collected, many of 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 minimum and maximum lengths were recorded for each species (CPf,L 1983).

I Incidental. collection of organisms large enough to be considered juveniles er adults required the enforcement of length limits.

Only fish and shrimp $ 40 m were identified with the exception of eels, pipefish.

I and leptocephali which were kept only if they were $ 100 mm.

The portunid crab cutoff limit was 5 24 mm.

8-1

I The seasonalities of brown shrimp Pc'n'a'cus aztecus and pink and white shrimp (P. duorarum and P. settferus, respectively) were determined the same as described in Section 6.2.

8.3 Results and Discussion g

8.3.1 Dominant Species 8

A total of 5.8 x 10 organisms representing 83 taxa was impinged during 1986.

Anchoa spp. ($ 12 m) were the dominant taxa comprising 31.6% of the total catch.

Other impinged species, in decreasing order of abundance, were spot Lefostomuz nnthurus (13.2%), Penaeus spp. postlarvae (11.9%), portunid megalops (10.8%), bay anchovy Anchoa mitchflif (9.7%),-

Cobiosoma spp. (9.3%), croaker Micropogonics undulatus (2.9%), and striped g

.nchovy Anchoa hepsetus (1.9%). Hardback shrimp Trachypeneus constrictus and Microgobius spp. each accounted for approximately 1%.

These ten taxa accounted for 93.6% of the total catch in 1986 (Table 8.1).

The seven most abundant species have remained the same since 1984.

However, two distinct shif ts in relative _ abundance (as expressed by per-cent of total larval impingement) occurred in 1986. Croaker, historically the most abundant species (approximately 23%; CP&L 1985a,1986) accounted ror only about 3% in 1986 (Table 8.1).

This same drop in abundance was also seen in entrainment (Section 6.3).

Croaker abundances in the river haa shifted from the lower to upper river probably due to higher salini-ties extending their habitat (Section 3.3).

Anchoa spp. ($ 12m) relative abundance was more than triple that of the previous two years (Table 8.1: CP&L 1985a, 1986).

Their densities also increased dramatically in entrainment and the lower river (Section 6.3; unpublished data).

This would indicate Gal dithough their period of abundance coincides with the operation of two 1-inm mesh and one 9.4-mm mesh intake screens, the fine-mesh screens wer e at least partially effective in removing this species.

I 8-2 g

I 8.3.2 Seasonality and Abundance I

The typical winter and summer periods of abundance observed in the entrainment and river larval fish programs (Sections 3.3.2 and 6.3.2) were also observed in larval impingement.

The winter period consisted of Atlantic menhaden Brevoortia tyrannus, spot, croaker, mullet Mugil cephalus and M. curema, flounder Parolichthys spp., and brown shrimp--all ocean-spawned species.

The period of abundance for portunid megalops, an early life stage of the blue crab Callinectes spp., occurred during the late summer and f all months and was considered a winter species.

The summer period consisted of ocean-spawned species such as seatrout Cynosefon I

nebulosus and C. regalls and pink and white shrimp and of estuarine-spawned species such as anchovy Anchoa hepsetus and A. mftchflli, Coblonellus spp.,

and Cobiosoma spp. (Table 8.2).

I 8.3.3 Survival Estimates in most cases, survival studies were conducted with organisms col-1ected from two different intake screen rotation. speeds.

To obtain an overall percent survival of impinged larval and postlarval fish and penaeid shrimp returned to the estuary, all survival tests cor. ducted since 1984 from f ast-screen rotation for size classes whose mean length as

$ 40 mm were used.

For blue crabs the size class used had a mean length I

j 24 mm.

The same was done for corresponding size classes from 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 com-bined and are presented as the total number impinged in Table 8.3.

In 1986 an estimated 1.7 x 107 croaker were impinged.

If they had been impinged on slow-rotating screens, 2.4 x 106 would have been returned to the estuary alive.

If they had been impinged on fast-rotating screens, 5.6 x 106 would have been returned alive.

Total spot impingement was 7.6 7

x 10.

If th9se had been impinged during slow rotation, 6.8 x 106 would 8-3 I

-w m-m u.

-p

..-,,,.,,_wm

I have returned to the estuary alive.

If they had been impin;'d during fast I

rotation, 2.2 x 10 would have survived. Similar fast / slow surv'ival esti-mates were calculated for the other species tested and are presented in Table 8.3.

The 17 taxa tested for survival represent 52% of the total larval impingement catch (for purposes or analysis Prionotus sFA. and big-head searobins Prionotus tribulus were combined under the taxa Prionotus 8

spp.).

Of these, 1.5 x 10 would have been returned alive to the estuary if the screens had been on fast rotation.

This corresponds ta 50% of the total larval organisms impinged being returned alive to the estuary.

If bay anchovy are excluded, the organisms tested for survival represent 2.4 x 100 or 41% of the total impingement.

If the intake screens had been on 8

l f ast rotation, 1.5 x 10 or 62% would have been returned alive to the estuary.

8.4 Summary and Conclusions The larval impingement program provided an estimate of the total 8

larvae and postlarvae being impinged by the 8SEP.

A total of 5.8 x 10 organisms representing 83 taxa was impinged during 1986 with Anchoa spp.

dominating the catch.

The seasonalities of stelected species were much the same as those observed in the entrainment and river larval fish programs.

The 17 taxa tested for survival represented 52% of the total larval g

8 impingemert catch.

During fast-screen rotation, 1.5 x 10 of these orga-nistas would have been returned alive to the ertuary which corresponds to 50% of the total larval organisms impinged being returned alive to the estuary.

When bay anchovy are excluded, then 62% or 1.5 x 108 organisms would have been returned alive to the estuary provided the intake screens had been on fast rotation.

I I

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.g 8-4

~

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Table 8.1 Ranking by percent of total impinged larvae at the BSEP during 1986.

Species Percent of total Anchoa $pp.

31.6 Spot 13.2 Penaeus spp. postlarvae 11.9 Portunid megalops 10.8 l

Bay anchovy 9.7 Cobfosoma spp.

9.3 g

Croaker 2.9 Striped anchovy 1.9 Hardback shrimp 1.2 I

Microgobius spp.

1.1 Other taxa 6.4 Total 100.0 I

I E

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lI 8-5 t

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Table 8.2 Total number of selected species collected by trip in larval in:pingement at BSEP during 1986.

Sampling Portunid Total Dates Anchovy Menhaden Sestrout Spot Croeker Mullet F ic_ : der Penaeus spp, Cobioscaa spp, moge l<ys orgen;sms OF Jan 86 12,510 0

0 138 220 55 0

0 4

0 83,303 04 Jan 86 379 0

0 210 594 59 129 0

0 0

1,459 i

)

21 Jan 66 350 9

0 147 85

. 134 4

0 0

0 945 28 Jan 86 979 4

0 723 500 8tA 39 0

0 0

2,820 04 F eb 86 93 3

0 527 139 4

17 0

1 1

915 Il Feb 86 168 II O

25,225 I,495 53 62 80 4

4 25,937 18 Feb E6 68 26 0

5,843 184 11 34 Ta O

8 7,015 25 r b 86 72 4

0 5,656 667 0

124 770 0

4 F,809 e

05 Mr 86 112 136 0

14,108 554 245

'302 264 0

0 16,351 Il Mar 86 205 1,099 0

13,636 403 94 CSF 389 0

35 17.627 cn 18 Mar 86 15 436 0

1,902 134 10 3

986 4

46 3,710 25 Mar 36 259 1,964 0

2,685 241 16 4p)4 0

8 9,9y0 08 Apr 86 62 23 0

318 8

57 1

e95 3

109

• .971 16 Apr 86 26 14 0

184 32 13 5

Aft 9.

2 40

,143 22 Apr 86 7

2 0

82 18 3

0 220 0

76 595 29 Apr 86 412 45 0

90 36 3

12 235 4

14 5,222 06 May S6 728 4

0 17 0

t3 0

230 39 34 1,616 13 May 8e 6,534 0

4 0

32 2o O

68 sii 76 e,8i0 20 May 86 2,862 O

82 0

4 6

0-130 238 59 4,156 27 May 66 12,629 0

38 0

4 0

0 487 I,939 4

16,384 03 Jun 45 137,672 0

314 0

0 0

0 177 17,500 12 160,949 IO Jun 86 8,855 0

24 -

0 0

0 0

4,065 2,307 415 t7,35t I? Jun 86 5,725 0

64 0

0 0

0 737 6,930 112 15,157 24 Jun 86 9,244 0

36 0

0 0

0 15,443 7,820 535 35,966

M M

M M

M M

M M

M M

M M

M M

M E

E E

E Table 8.2 (continued) l Sampling Portunid Totel Dates Anchovy Menhaden Sestrout spot Croaker Mullet Flounder Penaeus spp, Cobiosoma spp, megelops orgaalses 08 Jul 86 693 0

35 0

0 0

0 1,529 2,363 125 5,964 15 Jul 86 7,828 0

125 0

0 0

0 338 3,947 14,434 22 Jul 86 3,488 2

23 0

0 2

0 333 MI 79 4,942 29 Jul 86 2,428 0

62 O

O O

O 4,181 2,340 265 11,146

{

05 Aug 86 668 0

8 0

0 2

0 73 44 6

963 1

12 Ak2 86 1,117 0

24 0

0 4

0 390 540 20 2,545 19 Aug 86 238 0

12 0

0 0

0 974 90 1,037 2,692 I

26 Aug 86 2,001 O

O O

O O

O 3,432 85 2.227 8,057 l

02 Sep 86 2,351 O

13 0

0 0

0 957 253 20.555 24,905 i

09 Sep 86 803 0

8 0

0.

0 0

7,805 777 3,351 13,536 16 Sep 86 107 0

0 0

0 0

0 1,240 64 5,038 6,684 4

23 Sep 86 254 0

0 0

14 0

0 li,040 328 1,633 4,813 07 Oct 86 58 0

0 0

4 0

0 1,037 313 1,119 3.023 14 Oct 86 SI 0

0 0

7 0

0 534 15 2,802 3,553 21 Oct 86 6

0 0

0 60 0

0 1,627 IS 2,737 4.595

,1 28 Oct 86 29 0

0 0

47 0

0 203 37 748 1,218 04 Nov 86 80 0

0 0

424 4

0 1,712 119 7,829 it,535 11 Nov 86 16 0

0 0

308 0

0 491 0

1,350 2,352 18 Nov 86 43 0

0 0

1,648 0

0 1,490 7

2,116 5,624 25 Nov 86 64 0

0 0

782 O

O 620 4

381 2,0G4 02 Dec 86 364 0

0 28 1,577 0

4 732 99 1,029 4,720 09 Dec 86 679 0

0 0

734 0

4 150 9

100 1,988 16 Dec 86 652 1

0 8

703 2

0 167 6

646 2,387 23 Dec 86 3,409 7

0 21 3,679 7

7 51 3

43 7,436 l

Table 8.3 Percent survival and number of impinged larval organisms returned alive to the Cape Fear Estuary during 1986.

Percent survival Number returned alive Fast-Slow-Fast-Slow-Total screen screen screen screen Species number impinged rotation rotation rotation rotation 7

6 6

l Croaker 1.7 x 10 32.9 14.0 5.6 x 10 2.4 x 10 7

7 6

Spot 7.6 x 10 29.1 8.9 2.2 x 10 6.8 x 10 7

6 5

Bay anchovy 5.6 x 10 0.7 0.3 3.9 x 10 1.7 x 10 l

7 7

7 Penaeus spp. postlarvac 6.9 x 10 90.3 80.3 6.2 x 10 5.5 x 10 6

6

{

Flounder 1.4 x 10 90.0 1.3 x 10 4

5 5

Striped mullet 9.9 x 10 67.7 4.8 6.7 x 10 4.8 x 10 7

I 7

Portunid megalops 6.2 x 10 87.0 86.3 5.4 x 10 5.4 x 10 0

4 Weakfish 4.3 x 10 12.6 5.4 x 10 5

4 Prionotus spp.

1.0 x 10 89.8 9.0 x 10 6

6 6

Hardback shrimp 6.8 x 10 78.8 48.4 5.4 x 10 3.3 x 10 4

4 4

m d,

Pink and white shrimp 2.2 x 10 95.8 75.0 2.1 x 10 1.6 x 10 5

5 5

Blue crab 3.3 x 10 91.7 95.1 3.0 x 10 3.1 x 10 6

5 Gobionelius spp.

3.6 x 10 15.4 5.5 x 10 4

4 Permit 1.3 x 10 85.2 1.1 x 10 3

3 Crevalle jack 8.7 x 10 35.9 3.1 x 10 J

6 Atlantic menhaden 4.3 x 10 0

0 0

0 0

Anchoa spp.

1.8 x 10 8

Other organisms (65 taxa) 1.0 x 10 0

Total organisms 5.8 x 10 Total organisms tested 3.0 x 100 (52%)I 1.5 x 100 (50%)5 Total organisms tested (exclujing bay anchovy) 2.4 x 108 (43g)1 1.5 x 108 (62%)E iPercent of totc1 organisms impinged that were tested.

IParcent of total organisms impinged that were tested excluding bay anchovy.

5 ercent of f returned alive.

P EPercent of 1 ; eturned alive.

1 i

33 M

m M

m M

M M

M M

M M

M M

M M

M M

M l

L- _

a. _ > ~

y 4

I

~

l 9.0 IMP!NGEMENT (Juvenile and Adult) g 9.1 Introduction I

Impingement studies have been conducted at the Brunswick Steam Elec-tric Plant since January 1974 when water was first pumped through the plant.

Objectives of the study were to determine the numbers, weights, species composition, and length frequencies of organisms impinged.

The 1986 juvenile and adult (J/A) impingement study was conducted I

with the fish diversion structure in operation.

The fish diversion struc-ture prevented larger organisms from entering the intake canal except when screen panels failed as a result of biofouling and/or debris buildup.

9.2 Methods Samples were collected for one 24-hour period twice per month during 19 0.

The samples were taken by placing a steel-framed collection basket with 9.4-m plastic webbing in each fiume.

Control valves were opened so I

screen wash water flowed freely in both flunes.

As a basket filled with organisms or debris, another basket was set in the flume to guarantee continuous filtration of the screen wash water while the full basket was emptied.

Samples were taken to the laboratory where organisms were sorted, identified, counted, measured, and weighed.

Up to 50 individuals per size group of 13 selected species were measured 'f rom each sample (CP&L1985a).

Monthly estimates and expansion f actor calculations were 1dentical to those described in CP&L (1983).

Fish and shrimp 3 41 mm, I

portunid crab 3 25 m, and eel and pipefish 3101 mm were included in the J/A impingement catch.

9.3 Results and Discussion 9.3.1 Species Composition l

Juvenile and adult impingement during 1986 totaled 5,001,933 organ-isms representing 95 taxa and weighing 14,785 kg.

Bay anchovy Anchoa mitchfill was the most abundant species collected totaling 76.5% of the I

9-1

I catch.

Br6xn shrimp Penaeus cztecus (4. AQ, blue crab Callinectes sapidus (3.6%),.<hite shrimp Penaeus settfacus (1.9%), pink shrimp Penaeus duorcrum (1.7%), and letser blue ces Callinectes simills (1.6%) were second through sixth in abundance, ru pect'vely.

The.emaining 89 taxa accounted for 10.3% of tne total catch.

Dent.ities (number and weight per million cubic meters of water pumped) we-e calculated so year-to-year imoingement could be compared regardless of the plant's water usage.

Tne density of organ-isms impinged oy number in 1986 was 28.4% less than in 1985.

The density by weignt was 16.5% less in 1986 than in 1985.

When :ompared to the den-sity for prediversion years (1977 through 1982), a decrease of 55.3% b) l number and 77.0% by weight was observed (Table 9.1).

Three previously (1977 through 1982) abundant species were not among the te, moss abundant organisms impinged during 1986 (CP&L 1982,1983).

Spot Lelostomus xanthurus was 11th (0.8%), cro2ker Micrcpogonias undulatus was 12th (0.7%), and Atlantic menhaden Brevoortta tyrannus was 20th (0.2%)

in the total catch.

The fish diversion structure excluded larger indi-g viduals of these species from the intake canal and therefore impingement was reduced from prediversion reportings (Section 5.0).

9.3.2 Flow Rctes I

The volume of water entrained at the plant can affect the number and weight of urganisms impinged.

The 1986 flow rates were higher than the 1984 and 1985 flow rates but were below the 1977 through 1982 mean (CPLL 1985a).

Mean monthly intake flow rates in 1986 ranged from 7

3 4.2 x 10 m /mor.th in February to 1.4 x 108 3

m / month in July.

The mean monthly flow for 1986 was 9.3 x 107 3

m / month (Figure 9.1).

The flow in-crease in 1986 was the result of both generating units operating for most of the year, especially during the summer months when higher flows were

pemitted, 9.3.3 Length-Frequency Distributions l

Length-frequency data were used to examine the size distribution of oay anchovy, spot, and croaker.

All three species exhibited similac lengtn-frequency distributions as reported in CP&L (1985a).

Of the spot 9-2 5

I and croaker caught, most were young-of-ye&~r size classes (modal length =

45-70 mm) and may have entered the intake canal as postlarvae through the fish diversion screens.

Spot and croaker length-f requency distributions further documented the reduction in size of juvenile and adult individuals I

impingement due to their exclusion by the fish diversion structure.

in Adult bay anchovy entered the intake canal through the fish diversion screens cs a result of their mall size.

Bay anchovy exhibited length-frequency distributions (modal length = 40-50 mm) similar to prediversion structure reportings (CP&L 1982).

Length-frequency distributions for l

Atlantic menhaden were not used because very few individuals were impinged in a given sample period.

9.3.4 Survival Estimates I

Survival studies have tested 14 frequently impinged species (Table 9.2).

The percent survival of a species is a mean of all data for the J/A size class of that species collected from 1984 through 1986.

Survival data was cullected either during slow-or f ast-se Mn rotation.

l Generally, survival percentages sre very similar between slow-and f ast-screen speeds (Table 9.2).

Slow-screer, rotation is the normal operating condition at the plant and all discussion will pe.*tain to the slow rota-tion.

Juvenile and adult shrimp and crab impingement survival is approxi-mately 90%.

Spot and croaker survival is somewhat less, 57% and 73%,

respectively, while bay anchovy showad very poor survival at aoout 1%.

The application of survival data to J/A impingement data shows that if the I

screens had been operated on slow <creen speed, appr W mately 13.8% of the 1986 total number impinged and 54.1% of the weight impinged would have been returncd to the estuary alive.

The low perc:ntage of total number returned alive resulted from the low survival percentage of bay anchovy i

combined with the high numbers impinged.

.When survival estimates are l

calculated excluding bey anchovy, the survival for the remaining organisms is approximately 55.1% by number and 66.0% by weight (Table 9.3).

' I

' I 9-3

9.4 Summary and Conclusions The 1986 J/A impingement catch consisted of five million organisms weighing just under 15,000 kg.

Bay anchovy (76%) was the most abundant species and brown shrimp (4%) was the second most abundant species im-pinged.

Impingement per million cubic meters of water pumped decreased by 28% in number and 16% by weight when compared to the 1985 catch.

The 1986 reduction by number and weight was 55% and 77%, respectively, over the 1977 through 1982 mean.

'his showed the continued effectiveness of the fish diversion structure.

The diversion structure excluded many J/A Atlantic menhaden, spot, and croaker; but bay anchovy were not excluded by the structure and thus dominated the 1986 J/A impingemeat catch.

g Length-frtquency analysis generally showed spot and croaker length distributiens were reduced by the presence of the diversion structure.

Bay anchovy was not excluded from the intake canal by the diversion struc-ture and their length-frequency distributions did not change from previous yerds.

Survival studies cocumented a reduction in the impingement loss.

The fish return system allowed approximately 14% by number and 54% by weight of all organisms impinged to be returned to the ettuary alive.

Excluding bay anchovy, approximately 55% of all organisms by number were returned to the estuary alive during 1986.

I I

I I

I I

I 9-4

.I.

M M

M M

M M

M M

M M

M M

M M

M M

M M

Table 9.1 A su:amary of juvenile and adult impingement at the Br_nswick Steam Electric Plant during 1986 with comparisons to previous years.

Number per mill.on Weight (kg) per Percent Total cubic meters of Total million cubic meters Species of catch number water pumped weight (kg) of water pumped Bay anchovy 76.5 3.625,576 3,420.1 2,720 2.4 Brown shrimp 4.4 221,642 198.2 2,264 2.0 Blu2 crab 3.6 178,866 159.9 4,611 4.1 White shrimp 1.9 97,204 86.9 404 0.4 Pink shrimp 1.7 87.186 78.0 275 0.2 Lesser blue crab 1.6 81,327 72.7 478 0.4 Blackcheek tonguefIsh 1.1 54,006 48.3 270 0.2 Striped anchovy 1.0 47,745 42.7 122 0.1 Brief squid 0.9 46,321 41.4 263 0.2

?

Atlantic silverside 0.8 38.446 34.4 70 0.1

S additional taxa 6.5 323,614 289.2 3.308 3.1 1984 Totas orge.. isms 100.0 5,001.933 4,471.8 14,785 13.2 1985

'a1 organisms -

5,967.474 6.248.2 15,098 15.8 t

Percent change (1986 to 1985)

- 28.4

- 16.5 1977-19F nual eesn 14.267.926 10,000.3 83.523 57.3 Percent che_uge !!986 La 1977-1982)

- 55.3

- 77.0 t

+

I i

B Table 9.2 Percent survival of juvenile and1dult organisms impitiged at the l

Brunswick Steam Electric Plant during slow-anJ fast-screen rots-tion, 1984 through 1986.

I Slow-screen rotation Fast-screen rotation g

Percent Number ~

Percent Number 3

Species survival of tests

,urv ival of tests Callinectes spp.

92.1 2

96.I 3

(comon 6nd lesser)

Penaeus spp.

86.5 5

93.1 20 (pink and white)

Striped mullet 9J.0 2

Brown shrimp 90.7 8

90.4 10 l

Blackcheek tonguefish 83.1 6

Parallchthys spp.

71.1 1

(southern f. sumer)

Spot 57.1 4

60.4 2

Croaker 73.4 4

48.6 6

Weakfish 35.0 2

Atlantic menhaden 15,6 1

Bay anchovy 1.1 2

4.9 2

I I

I I

I I

9-6 g

I I

Table 9c3 Estimated survival of juvenile an3' adult organisms impinged at the Grunswick Steam Electric Plant during slow-screen rotation in 1986.

Imoinged Estimated survival I

Species Number Weight (kg)

Sumher Weight (kg)

Cc!!!nectes spp.

260,193 5,088 239,638 4,686 g

(corrrnon and lesser)

Brown shrimp 221,642 2,264 201.029 2,051 Penaeus spp.

(pir.k and white) 184,390 679 159.497 587

. Croaker 35,819 666 26,291 489 Spot 37,947 258 21,668 147 8ay anchovy 3,825.576 2.720 42,091 30 Other species (87 taxa) 436,366

_ 3,110 Total 5,001,933 14,785 690,204 7,992 l

Percent survival 13.8 51.1 Excluding bay anchovy 1.176,357 12,065 648,123 7,962 Percent survival 55.1 66.0 I

I I

I I

I 9-7

i g

I 160' I

140' I

n 120' o

l j' k - ~

l 2100' e'

N, u

N

'j B0

A o'

'* N E

., o. _ ~ e c _ -

o N

5 s

j 60' v'

g

=

i 40' I

20' I

0' I

i i

l i

l I

i l

i l

i e

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month

- 1986 (mean,= 93.2) eoc 1984-1985 (mean. 77.4) l m 1977-1982 (mean - 120.4)

I i

I Figure 9.1 Mean monthly flow of water pumped at the Ilrunswick Steam Electric Plant,1977 through 1982,1984 through 1985, and 1986.

I l

n.

1

-l

I

~

~

l 10.0 RETCRENCES l

Ambrose, J., Jr.

1983.

Age determiriation.

Pages 301 to 324 in L. A.

I Nielson and D.

L.

Johnson (eds).

Fisheries techniques.

American Fisheries Society, Blacksburg, VA.

Birkhead W. S., B. J. Copeland, and R. G. Hodson.

1979.

Ecological I

monitoring in the lower Cape fear River estuary, 1971-1976.

North Carolina State University, Raleigh, NC.

I

Blaber, S.

J.,

and T. G.

Blaber.

1980.

Factors affect:ng the dis-tribution of juvenile estucrine and inshore fish, J. Fish. Biol.

17:143-162.

CP&L. 1980, 1979 monitoring program.

BSEP Capc Fear Studies Supplement 1.

Carolina Power & Light Company, New Hill, NC.

1982. Brunswick Steam Electric Plant annual biological monitor.

ing report, 1981.

Carolina Power & Light Company, New Hill, NC.

I 1983. Brunswick Steam Electric Plant anneal biological monitor.

ing report, 1982.

Carolina Power & Light Compeny, New Hill, NC.

I 1984. Brunswick Steam Electric Plant 1983 biological monitoring report.

Carolina Power & Light Company, New Hill, NC.

1983a. Brunswick Steam Electric Plant 1984 biological monitor-I ing report. Carolina Power & Light Company, New Hill, NC.

1985b. Brunswick Steam Electric Plant, Cape fear Studies, Interpretive report. Carolina Power & Light Company, New Hill, NC.

1986. Brunswick Steam Electric Plant 1985 biological monitoring report.

Carolina Power and t.ight Company, New Hill, NC.

Carpenter. J. H., and W. L. Yents.

1979.

Oye tracer and current meter studies, Cape fear Estuary, North Carolina, 1976, 1977, and 1978.

l BSEP Cape Fear Studies.

Report to Carolina Power & Light Company.

Hiami, FL.

I Copeland, B. J., W. S. Birkhead, and R. G. Hodson.

1974.

Ecological monitoring in the area of the Brunswick Nuclear Power Plant, 1971-1973.

Report 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 opere-I tion of the Brunswick Electric Ple'.t. 1974-1978.

North Carolina State University, Raleigh, NC.

I

Deegan, L. A., and J. W.

Day, Jr.

1984 Estuarine fishery habitat requirements, Dages 315 to 336 in B. J. Copeland, K. Hart, N. Davis, and S. Friday (eds.).

Re,;urch for Managing the Nation's Estuaries:

Proceedings of a Conference.

Raleigh, NC.

I 10-1

I y

Everhart H.

W., and W. D. Youngs.

1981.

Principles cf fishery scier.ce.

2nd ed. Cornell University Press, Ithaca, NY.

Gunter, G.

1961.

Some relations of f aunal distributions to salinity in estuarine waters.

Ecology 37:616-619.

Hodson, R. G.

1979.

Utilization of marsh hdbitats as primary nursery areas by young fish and shrimp, Cape Fear Estuary, North Carolina.

BSEP Cape fear Studies, Volume VI!!.

North Carolina State University, g

Raleigh, NC.

g Hodson, R.

G., C. R. Bennett, and R. J. Monroe..

1981.

Ichthyopienkton samplers for simultaneous replicate samples at surface and bottom.

Estuaries 4: 176184 Hogarth, W. T., and K. L. Nichols.

1981.

Brunswick Steam Eler.tric Plant E

intake modifications to reduce entrainment and imp i nor..ne nt losses.

E Carolina Power & Light Company, New 11111, NC.

l hoss, D. E., W. F. Hettler, Jr., and L. C. Cotton, 1974.

Effects of therms 1 shock on larval fish:

Ecological implications with respect to entrainment in power plant cooling systems.

Pages 357 to 371 in J. H.

S. Blaxter (ed.).

The early life history of fish.

Springer Verlag, Berlin, West Germany.

Huish, M. T., and J. P. Geaghan.

1979.

A study of adult and juvenile 3

fishes of the lower Cape Fear River naar the Brunswick Steam Electric 5

Plant, 1975-1976.

North C,rolina State University, Raleigh, NC.

l Jones, P.

W., F. D. Martin, and J. D. Hardy, Jr.

1978.

Development of fishes of the mid-Atlantic Bight, Volume !.

U.S. Fish and Wildlife Service. Washington, OC.

Joseph, E. B.

1973.

Analysis of a nursery ground.

Pages 118 to 121 in I

A. L. Pacheco (ed.).

Proceedings of a workshop on egg, lat val, and juvenile stages of fish in Atlantic Coast estuaries.

Highlands, NJ.

Lagler, K. F.

1952.

Freshwater fishery biology.

Wm. C. Br'*h CC.

'ub-lishers, Dubuque, IA.

I Lasker, R.

1975.

Field criteric for survival of anchovy w /4e?

The relation betwetn inshore chlorophv11 maximum 1 dyers and w.cessful first feeding. Fish. Bull. 73:453-462.

Leming, T.

D.,

and D. R. Johnson.,

1985.

Application o' circulation models to larval dispersment and recruitment.

Mar. Tech. Soc.

J.

m 19:34-41.

3 Lohr. V.

I., and R. G. O'Brien.

1985.

Power analysis for univariate linear aodels:

The SAS system makes it easy.

Pages 847 to 852 in 1984 proceedings of the ninth annual SAS users group international conference. Hollywood Beach, FL.

10-2 g,

m J

I

~

I-McGroddy, P.

M.,

and R. L. Wyman.

1977; m Ef ficiency of nets and a new device for sampling living fish larvae.

J.

Fish. Pcs. Board Can.

34:571-574 McHugh, J. L.

1967.

Estuarire nekten.

Pages 581 to 620 In G. H.

Lauff (ed.).

Estuaries.

American Association fer the Advancement of Science. Washington, DC.

Milgarese, J. V., C. W. McMillian, and M. H. Shealy, Jr.

1982.

Seasoral abundance of Atlantic croaker (Mleropogonias undulatus) in relation to bottom salinity and temperature in South Carolina estuaries.

Estuaries 5:216-203.

I Miller, J.

M., S. W. Ross, and S. P. Epperly.

1984 Habitat choices in estuarine fishes:

Do they have any7 Pages 337 to 352 in B.

J.

Copeland, K. Hart, N. Davis, S. Friday (eds.).

Research for Managing the Nation's Estuaries:

Proceedings of a Conference.

Raleigh, NC.

Norcross, L. B., and R. F. Shaw.

1984 Oceanic and estuarine transport of fish eggs and larvae:

A review.

Trans. Am. Fish. Soc. 113:153-165.

O'Brien, R.

G.,

and V.

I.

Lohr.

1985.

Power analysis for linear 5

models:

The time has come.

Pages 840 to 846 in.1984 proceedings of a

the ninth annual SAS users group international conference.

Hollywood Beach, FL.

f Rogers, S. E., T. E. Targett, and S. B. van Sant.

1984.

Fish-nursery use in Georgia salt-marsh estuaries:

The influence of springtime freshwater conditiuns.

Trans. Am. Fish Soc. 113-595-606.

Schwartz, F.

J.,

P.

Perschbacher, L.

Davidson, K.

Sandoy, J.

Tate, M. McAdams, C. Simpson, J. Duncan, and D. Mason.

1979.

An ecological Jtudy of fishes and invertebrate macrof auna utilizing the Cape Fear I

River estuary, Carolina Beach Inlet, and adjacent Atlantic Ocean, 1918.

BSEP Cape fear Studies, Volume XV.

Institute of Marine Sciences, University of North Carolina, Morehead 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.

Weinstein, M. P., S. L. Weiss, and M. F. Walters.

1980.

Multiple deter-minants of community structure in shallow marsh habitats, Cape Fear I

Estuary, NC.

Mar. Biol. 58:227-243.

Weinstein, M. P., and M. F. Walters.

1981.

Growth, survival and pro-I duction in young-of-year population of Lefostomus zanthurus Lacepede residing in tidal creeks.

Estuaries 4: 185-197.

=

Weinstein, M.

P.,

S. L. Weiss, R.

G.

Hodson, and L.

R.

Gerry, 1979.

Retention of three taxa of postlarval fishes in an intensively flushed tidal estuary, Cape fear River, North Carolina.

Fish Bull.

78: 419-436.

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