CALVERT CLIFFS NUCLEAR POWER PLANT

FINFISH SURVIVAL STUDY

FOR

BALTIMORE GAS AND ELECTRIC COMPANY

FINAL REPORT

Denise L. Brei 

Timothy A. Thoman

Report No. 86-19

Benedict Estuarine Research Laboratory

Benedict, MD 

Division of Environmental Research

Academy of Natural Sciences of Philadelphia 19th and the Parkway 

December 23, 1986
EXECUTIVE SUMMARY

survi val 

Cliffs Nuclear Power Plant June-August 1986 to compare survival

rates 

overall differences among screen types in 

finfish. 

size than did control screens. 

experimental 

However, the 

screen positions rather than screen 
TABLE OF CONTENTS

EXECUTIVE SUMMARY

......................................

INTRODUCTION

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

MATERIALS AND METHODS

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Finfish Survival Studies

.............................

Impingement Study

....................................

Statistical Analyses

.................................

RESULTS AND DISCUSSION

Finfish Survival Rates

...............................

Sizes of Impinged Finfishes

..........................

Numbers of Impinged Finfish and Blue Crabs

...........

SUMMARY

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

LITERATURE C 

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Page
INTRODUCTION

In the 

conducted studies to 

finfish impinged on three different types of traveling 

at Calvert Cliffs

Nuclear Power Plant 

prevent finfish, other estuarine organisms and debris too large

to pass through the 8 x 

being carried into the 

screens rotate, 

screens and into a trough that 

Bay.

FMC single-speed screens are currently used at 

experimental screen types, Beauderey screens and FMC dual-speed

screens were installed 

(BG&E) at Units 1 and 

ness at 

purpose of the study described here was to 

conversion to 

significantly 

operations.

MATERIALS AND METHODS

Finfish Survival Studies

Survival rates for 

screens and 

finfish impinged on the currently used FMC single-speed screens

(controls). The 

screen position 

position 1 

posi tion 
because finfish impingement at these positions tends to be most

similar to that at the positions where the experimental screens

were installed 

Because each type of 

only one position, this 

tween screen and position 

did not 

impinged at the positions used for 

and after those 

of the 

sampling of impinged animals at CCNPP for 

and survival rates of 

screen positions wi Mr. Hixson 

served that the outermost screen positions 

and unit 

individuals. Based on 

judicious to interpret a difference in survival 

impinged finfish or a lower impingement rate at 

screens than at 

types. 

impingement rates are 

control screens.

To 

diverted from the troughs to large concrete survival pools that

measured approximately 9. 

(Fig. 

the collections to begin approximately 100 sec after the screen

to be 

amount of time it took for 

the Unit 1 screens to the unit 1 survival pool. 

impinged animals were allowed to flow into the pool for 10 

the duration of each screen 

procedure was used because the time it took 

from the 

more variable screens were

manually rotated. Organisms from screens not sampled for 
study 

entire pool-filling procedure on days that Unit 2 

sampled. 

Uni t survi val 

experimental or control screen to be sampled 

rotation. At 

water and 

screen not 

than the 

screens, procedures used at Units 1 and 2 were 

At the end of 

into (Callinectes 

coelenterates and ctenophores were 

removed and identified to species and total lengths of all dead

finfish, up to a maximum of 25 

each species 5 cm.

We attempted to include all fish washed from the screen of

interest during 6-7 successive screen rotations in each 

However, the 

samples was often 

screens were placed in continuous rotation during some portion

of the day or 

of rotations. 

required continuous rotation of 

rotated 

crete samples from the screens of 

After the final screen rotation was included in 

sample, data on environmental parameters were 

oxygen (D. ) levels were measured with a Y. I. model 57 D.

meter. 

meter. C), water depth and 

also O. 

measured at middepth in the 

in Table 

Approximately 24 h after pools were 

and water 
except (Trinectes maculatus) were 

identified and classified as live, dead or 

equilibrium 

inabili ty 

water. 

(haphazardly chosen) individuals of any one species 

sured to cm. Trinectes maculatus was not

included in this study because previous research indicated that

impingement 

(Burton, 1976).

Sampling was days per 

through August 

screens were not in 

uously rotated. A 

Beauderey screens, 20 

samples from FMC 

trol screens 

Impingement study

Numbers and kinds of 

(Callinectes sapidus) impinged on experimental and FMC singlespeed 

directly from the 

August 27-cm stretch-mesh

collecting net was placed in the 

10-min rotation of each of the six 

Raw data 

took to lift the net out of the trough and empty 

into 

often 

rotates 10 min out of 

during the 

and adj 

number of finfish and blue crabs impinged on 

hour. 
speed screens at a unit were combined and used as the 

against which experimental screens at that unit were 

Sampling frequency was based on 6-day cycles separated by

2- or 3-day intervals. On h collections

were made at each of the two generating 

not in 

uni t. 

screen 

rotation.

The unit to be 

initial 6-day 

6-day periods 

began at 

second 

second 

sampling periods were scheduled as followed: 

tions began at 

first, 

ti vely . 

first had begun. 

in two 6-day 

from Beauderey screens, 33 samples from unit 1 control 

28 samples from FMC dual-speed screens and 35 samples from unit

2 control 

rates at experimental and control 

statistical Analyses

Survival

separately for

rates of 

each species at each

La.

P =

Ln.

finfishes were calculated

screen as

where a. = the number of live 

the total 

error of p 
total of ~30 

from that screen. 

e. p = n

where C is the

Pi = n : N = : n = C

(Snedecor and Cochran, 1967).

To 

screens 

tion 

Z = log i + ~

n. - 

where di = the number of dead 

transformed data were weighted for sample size as

f(la. 2 -2pLa .1 1 n. +p2 Ln. 2 

number of samples and

weight = 1/V

i + 1) (ni + 2) V =

i (di + 1) (ni - di + 1)

Data were analyzed using the SAS GLM 

1982). 

species were 

where

species.

T-tests and 

numbers and sizes of impinged 

used compare

RESULTS AND DISCUSSION

Finfish Survival Rates

Twenty-nine species of 

families were collected in the 

3) . 

all 

4a-d). 

per sample are poor 
ever. 

midwater species (e. g., bay anchovy (Anchoa mitchilli), Atlan- tic (Brevoortia blueback herring (Alosa

aestivalis)) and highest for 

g., 

toadfish (Opsanus tau) and flatfishes).

Data from Units l and 2 control screens were combined for

statistical 

comparisons of 

screens. 

were collected to 

impinged on 

screens. fish, (Leiostomus and 

(Prionotus carol Seven species were 

dant to 

dual-speed 

oyster spot, 

(Pseudopleuronectes skilletfish (Gobiesox

strumosus) northern 

(Sgmphurus plagiusa). Species included in statistical analyses

were those with at least 

four 

parison.

There were 

among finfish impinged on the three types of 

tested in this 

statistically significant 

when impinged on 

trols 

screens than on controls 

arcsin 

Rohlf, 1969).
Sizes of Impinged Finfishes

Mean lengths of 

survival study from each screen 

Sizes of fish 

pared in Table 7 for 

individuals in both the experimental screen of interest and the

combined controls. 

Beauderey screens was larger than that on controls for 7 of the

10 species 

(Cgnoscion regalis), spot, 

(Peprilus alepidotus), and blackcheek tonguefish. Thus 

individuals of 

impinged on 

presented by larger 

in 

difference in size of skilletfish or northern searobin impinged

at Beauderey and control 

No general differences in 

between those 

impinged on control 

lengths of 

cantly greater in fish impinged on control 

of 

were significantly greater for fish 

speed screens. 

screens for lengths of the other fish 

Numbers of Impinged Finfish and Blue Crabs

Numbers of 

screens at each unit were compared for the 

species at each unit and 

and b). 

control screens for three of the 

Uni t 
and for all 

for which impingements were not significantly different between

screen types followed the same ln 

screens. 

column and benthic species.

More blue crabs were impinged by Beauderey screens than by

unit 1 controls 

on FMC 

significant (Table 

As discussed in the 

determine . experimental

screens than at 

or screen position.

SUMMARY

1 ) survi val 

June-August 

numbers of impinged 

There were no overall 

survival rates of 

comparisons only 2 

between experimental and control 

Beauderey screens 

than did 

fish is 

Beauderey screens may be 

impinged by 

screens 

similar average 

More fish were impinged by both 

by FMC 

impingement rates may be 

than screen types. 

the positions that The Academy of 

conducted at CCNPP

rates, 

2 )

3 )

4 )
ogists believed had the 

effort to 

sizes for analyses of survival 

LITERATURE CITED

Burton, 

and quantitative survival crabs. 2-1 to 11. 2-49 in semi-annual environmental monitoring report for Calvert Cliffs Nuclear Power

Plant, March 

Baltimore, Maryland.

Cox, D. 

London , England.

Chapman and Hall,

SAS s guide: sti tute, statistics. SAS InSnedecor, G. W. and 6th ed. 

Sokal, R. 

and Co., San Francisco 

W. H. Freeman
rL.JL 

m m r;"L "I' J I. , 6112..J L2J L2J a2J all cr'--- - :~"'r

. I

I-'

I-'

Un i t 

SurvivalPool

--t j I"" C ~-.t..- C 

. (

1",

i; 

Figure 1.

Power Plant

Unit 2 Screens

w/Position Numbers

Unit 

w/I'osit ion 

Embayment

Chesapeake Bay

Unit I

Survival

Pool

Diagram of CCNPP.

rotating screens 

shown.

Approximate relative locations of

survi val 
Table 1. Dates on which survival pools were filled for 1986 the finfish survival

study and the mean number 

sample. Prior to 

ples from the desired screens at Unit 

Sample Dates

Beauderey Screens

Unit 1 controls

(FMC single- speed

screens)

FMC dual- speed

screens

Uni t 2 

(FMC single- speed

screens)

June June June 12 June 10

July July July July

Augus t Augus t Augus t Augus t

X (SE) number

of rotations

per sample:

3(0. 4(0. 6(0. 0(0.
Table 2. Dissolved oxygen , salinity and temperature of water in survival

pools. F = , E = data taken

approximately 24 h late!, on the day the pool was emptied. 

data are presented as 

Screen Dissolved Oxygen (mg' L - 1 Salinity (ppt) Water Temperature

Beauderey 7 . 6:tO . 2 5 . 6iO . 7 14. 2iO. 13. 25 . 6iO . 9 24. 5iO.

FMC dual- speed nO. nO. 14. 2iO. 13 . 9iO . 3 26. 4iO. 24. 7iO.

Uni t 1 control 7 . 6iO . 3 5. 9iO. 14. 2iO. 14. 25 . BiO . 4 24. 2iO . 4

Unit 2 control aO. 4 . 3iO . 14. 3iO . 3 13. 5iO. 3 25 . 9iO . 5 24. 3iO . 
Table 3. Finfish species collected from experimental and control screens

for the 1986 finfish survival study at CCNPP. Hogchokers Trinectes maculatus were also impinged but were not included in

the study.

FAMILY SCIENTIFIC NAME COMMON NAME

Anguillidae Anguilla rostrata American eel

Clupeidae Alosa aestivalis

Alosa pseudoharengus

Brevoortia tgrannus

blueback herring

alewife

Atlantic menhaden

Engraulidae Anchoa mitchilli bay anchovy

Ophidiidae Ophidion marginatum striped cusk- eel

Batrachoididae Opsanus tau oyster toadfish

Gobiesocidae Gobiesox strumosus skilletfish

Gadidae Urophgcis regia spotted hake

Cyprinodontidae Cgprinodon variegatus sheepshead minnow

Poeciliidae Gambusia affinis mosquito fish

Atherinidae Menidia menidia Atlantic silverside

Syngna thidae Sgngnathus fuscus northern pipefish

Triglidae Prionotus carolinus northern sea 

Percichthyidae Morone saxatilis striped bass

Sciaenidae Menticirrhus americanus

Cgnoscion regal is

Cgnoscion nebulosus

Leiostomus xanthurus

southern kingfish

weakfish

spotted seatrout

spot

Bothidae Paralichthgs dentatus

Scophthalmus aquosus

summer flounder

windowpane

Pleuronectidae Pseudopleuronectes americanus winter flounder

Soleidae Trinectes maculatus hogchoker

Cynoglossidae Sgmphurus plagiusa blackcheek tonguefish

Tetraodontidae Sphoeroides maculatus northern puffer

Blenniidae Chasmodes bosquianus

Hgpsoblennius hentzi

striped blenny

feather blenny

Gobiidae Gobiosoma bosci naked goby

Stromateidae Peprilus alepidotus harvestfish
Table 4a. Survival rates of finfishes impinged in 1986 on Beauderey screens

at CCNPP Unit 

number of

number of indi vidua 1 

samples on in samples

which per- included in

Percent survival cent survival calculation of

Species SEi, is based*'" percent survival

Alosa aestivalis 1. 0

Anchoa mitchilli

Anguilla rostrata 1.0

Brevoortia tgrannus 1. 9

Chasmodes bosquianus 100. 1.0

cynoscion regal is 31.6

Gambusia affinis 100.

Gobiesox strumosus 100.

Gobiosoma bosci 100. 1.0

Leiostomus xanthurus 45. 20. 122. 51. 7

Menidia menidia 1.5

Opsanus tau 97. 1.4

Paralichthgs dentatus 44. 1. 8

Peprilus alepidotus 18. 41.0 12.

Prionotus carolinus 51.0 1. 3 277. 249.

Pseudopleuronectes americanus 78. 11. 11.

Scophthalmus aquosus 100. 1. 0

Sphoeroides maculatus 87. 1. 3

Sgmphurus plagiusa 47. 15. 12.

Syngnathus fuscus 33. 1.5

Urophgcis regia 11.

Unknown 1.0

*Standard errors for survival rates are calculated for all species represented

by a total of at least 30 individuals and found in at least 3 

**The survival rate of a species is calculated using all samples that included

at least one individual of that species.
Table 4b. Survival rates of finfishes impinged in 1986 on FMC dual- speed

screens at CCNPP Unit 

number of

number of individuals

samples on in samples

which per- included in

Percent survival cent survival calculation of

Species is based percent survival

Alosa pseudoharengus 1.0

Anchoa mitchilli 89. 84.

Brevoortia tgrannus 1.6

Chasmodes bosquianus 89.

Cgnoscion' regalis 21.4 1.5

Gambusia affinis 100.

Gobiesox strumosus 98. 23. 13.

Gobiosoma bosd 93.

Leiostomus xanthurus 91. 0 22.

Menidia menidia 12.

Morone saxatilis 100. 1.0

Ophidion marginatum 100. 1.0

Opsanus tau 96. 1.0 25.

Paralichthgs dentatus 89.

Peprilus alepidotus 36. 1.4

Prionotus carolinus 38. 1.9

Pseudopleuronectes americanus 47. 11.2

Scophthalmus aquosus 1.0

Sphoeroides maculatus 66. 1.5

Symphurus plagiusa 65. 12.

Sgngnathus fuscus 22. 1.5

Urophgcis regius 75. 1.6
Table 4c. Survival rates of finfishes impinged in 1986 on Unit 1 control

screens at CCNPP.

munber of

number of individuals

samples on in samples

which per- included in

Percent survival cent survival calculation of

Species is based percent survival

Alosa aestivalis 17. 58. 53.

Anchoa mitchilli 18. 65. 36.

Brevoortia tgrannus 12. 16. 10.

Chasmodes bosquianus 66.

cgnoscion nebulosus 100. 1.0

Cgnoscion regalis 26.

Gambusia affinis 100.

Gobiesox strumosus 100. 1.2

Gobiosoma bosci 100. 1. 7

Hgpsoblennius hentzi 1. 0

Leiostomus xanthurus 61.1 99. 27.

Menidia menidia 10.

Menticirrhus americanus 1. 0

Ophidion marginatum 1. 0

Opsanus tau 96. 1.5

Paralichthgs dentatus 35. 1. 9

Peprilus alepidotus 10.

Prionotus carolinus 44. 23.

Pseudopleuronectes americanus 46. 11.6

Scophthalmus aquosus 40. 1. 7

Sphoeroides maculatus 87. 1.1

Sgmphurus plagiusa 45. 11.1

Sgngnathus fuscus 44. 1. 8

Urophgcis regia 35. 1.1
Table 4d. Survival rates of finfish impinged in 1986 on Unit 2 control screens

at CCNPP.

number of

number of individuals

samples on in samples

which per- included in

Percent survival cent survival calculation of

Species is based percent survival

Anchoa mitchilli 1.3

Anguilla rostrata 100. 1.0

Brevoortia tgrannus 1.3

Chasmodes bosquianus 100. 1.0

cgnoscion nebulosus 1.0

Cgnoscion regalis 13. 11.

Cgprinodon variegatus 100. 1.0

Gobiesox strumosus 91. 7 1.1

Gobiosoma bosci 91. 7 1.5

Leiostomus xanthurus 82.

Menidia menidia 1. 0

Ophidion marginatum 50. 1.0

Opsanus tau 94. 1. 7 18.

Paralichthgs dentatus 75. 1.3

Peprilus alepidotus 1. 0

Prionotus carolinus 35. 18. 11.

Pseudopleuronectes americanus 90. 16. 10.

Sgmphurus plagiusa 56. 11.8

Sgngnathus fuscus 75. 1.0

Urophgcis regia 100.
Table 5. Statistical comparisons of survival rates of finfish impinged in 1986

on a) Beauderey and control screens and b) FMC dual- speed and control

screens. Only 

species of interest are included in means or statistical comparisons. Mean 

vival calculated for all samples containing )4 individuals of that

species.

Species

X percent survival

(number of samples)

Beauderey combined

screens controls p)F

8(7) 0(8) 427

41.2(9) 70. 4(18) 017

100. 0(7) 95. 4(19) 542

44 . 4 (6) 48. 5(14) 1. 65 216

Brevoortia tgrannus

Leiostomus xanthurus

Opsanus tau

prionotus carolinus

X percent survival

(number of samples)

FMC dual- speed combined

Species screens controls p)F

Anchoa mitchilli 0(8) 8(16) 008

Gobiesox strumosus 97. 4(7) 100. 0(11) 119

Leiostomus xanthurus 84 . 5 (9) 70. 4(18) 060

Opsanus tau 97. 3(14) 95. 4(19) 133

prionotus carolinus 45 . 9 (9 ) 48 . 5 (14) 808

Pseudopleuronectes americanus 53. 2(4) 65 . 1 (7) 435

Sgmphurus plagiusa 80. 7 (9) 56. 2(10) 507
Table 6a-d, Total lengths of finfish collected for the finfish survival study at CCNPP , June-August 1986.

(n = number of fish measured in each category.

Beauderey Screens

Total Length 

Live Individuals Dead Individuals LOE Individuals

Species

Alosa aestivalisAnchoa mitchilliAnguilla rostrata 33, 10.

Brevoortia tgrannus 16. 17.

Chasmodes bosquianus

Cgnoscion regalis 11. 7 1.5

Gambusia affinisGobiesox strumosus

Gobiosoma bosci 1.0

Leiostomus xanthurus 121 10. 181 11, 1. 0

Menidia menidia 1.0Opsanus tau 12.

Paralichthgs dentatus 11, 22.

Peprilus alepidotusprionotus carolinus 11. 11. 11.5

Pseudopleuronectes americanus 1.4Scophthalmus aquosusSphoeroides maculatus 13. 1.2

Sgmphurus plagiusa 11. 11. 4

Sgngnathus fuscus 16. 17. 1.5Urophgcis regia 12. 15.

Unknown Fish 18.
Table 6a-d (continued). Total lengths of finfish collected for the finfish survival study at 

number of fish measured in each category.

en =

FMC Dual-Speed Screens

Total Length (cm)

Live Individuals Dead Individuals LOE Individuals

Species

Alosa pseudoharengusAnchoa mitchilliBrevoortia tgrannus 16. 1. 7

Chasmodes bosquianus 1.3

Cgnoscion regalisGambusia affinis

f-I

Gobiesox strumosus 100

Gobiosoma bosci

Leiostomus xanthurus 11.2 163 11.

Menidia menidiaMorone saxatilis 17.Ophidion marginatum 15.

Opsanus tau 10.

paralichthgs dentatus 19. 1.0 223 25.

Peprilus alepidotusPrionotus carolinus 11. 6 11. 7 13. 1.0Pseudopleuronectes americanus 20.Scophthalmus aquosusSphoeroides maculatus 11. 11.3 1. 3Sgmphurus plagiusa 11. 9 11.2 11.5Sgngnathus fuscus 20. 16. 1.3Urophgcis regia 16. 1.1 16.
Table 6a-d. (continued). Total 

(n = number of fish measured in each category.

Unit 1 Control Screens

Total Length 

Live Individuals Dead Individuals LOE Individuals

Species

Alosa aestivalis

Anchoa mitchilli 234

Brevoortia tgrannus 16. 15. 135

Chasmodes bosquianusCgnoscion nebulosusCgnoscion regalisGambusia affinisGobiesox strumosus

Gobiosoma bosci

Hgpsoblennius hentzi Leiostomus xanthurus 319 230 1.0

Menidia menidia 10.

Menticirrhus americanus 32.Ophidion marginatum 18.

Opsanus tau 11. 109

Paralichthgs dentatus 17, 23.

Peprilus alepidotusPrionotus carolinus 11. 101 11.4 132 13.

Pseudopleuronectes americanus 1.4

Scophthalmus aquosusSphoeroides maculatus 14. 1.1

Sgmphurus plagiusa 11. 7 10.Sgngnathus fuscus 17. 16. Urophgcis regia 15. 16.
Table 6a-d. (continued). Total 

(n = number of fish measured in each category.

Unit 2 Control Screens

Total Length 

Live Individuals Dead Individuals LOE Individuals

Species

Anchoa mitchilliAnguilla rostrataBrevoortia tgrannus 16,

Chasmodes bosquianuscgnoscion nebulosusCgnoscion regalis

Cyprinodon variegatus

Gobiesox strumosus

Gobiosoma bosci

Leiostomus xanthurusMenidia menidia 10.

Ophidion marginatum 18. 17.Opsanus tau 113

Paralichthgs dentatus 18. 19.

Peprilus alepidotusPrionotus carolinus 10. 11.

Pseudopleuronectes americanusSgmphurus plagiusa 10. 10.

Sgngnathus fuscus 15. 15. Urophgcis regia 17.
Results of t-tests comparing sizes of finfish impinged in 1986 

experimental and control screens at 

C = control screens , D = FMC dual- speed screens.

Table 7a-b.

Beauderey Screens vs. Controls

Species p::.t

Screen type impinging individuals

with largest average size

Anchoa mitchilli

Brevoortia tyrannus

Cynoscion regalis

Gobiesox strumosus

Leiostomus xanthurus

Opsanus tau

Peprilus alepidotus

Prionotus carolinus

Pseudopleuronectes americanus

Symphurus plagiusa

001*

001

003*

538

025

022*

008

201

O. 047i~

008

FMC Dual-Speed Screens vs. Controls

Species p::.t

Screen type impinging individuals

with largest average size

Anchoa mitchilli

Brevoortia tyrannus

Cynoscion regalis

Gobiesox strumosus

Gobiosoma bosci

Leiostomus xanthurus

Opsanus tau

Paralichthys dentatus

Peprilus alepidotus

Prionotus carolinus

Pseudopleuronectes americanus

Sgmphurus plagiusa

756

330

OlP'

389

570

001

345

658

732

012

O. 048*

001

*Approximate t-tests were used where variances were significantly heterogeneous

(SAS Institute , 1982).
Table 8. Number of finfish and blue crabs impinged per hour in 1986 on experimental and control screens at

CCNPP. a) Unit I , b) Unit 2. 05)

Beauderey vs. Unit 1 Control Screens

Species

X ! 1 SE number of individuals impinged per hour

Beauderey screens t or approximate t p)t

Anchoa mitchi11iLeiostomus xanthurus

Opsanus tau

Prionotus caro1inus

Trinectes macu1atus

All finfishCa11inectes sapidus

8!1.6

18 . 4!3 . 6

5. 9!1. 7

14. 0!4.

98. 4!54 . 2

151. 3!55, 3

39 . 0!4 . 6

1. 6!O, 5

7 . 1!2 . 01.5!O,

10. l!6 . 17. 5!6.

39 . 1!10. 126. 4:t4 . 1

45t

73t

44t

53t

1. 48t

00t

019

009019600 fiS

0 . 140 fiS

054043

FMC Dual- speed vs, Unit 2 Control Screens

Species

X :t 1 SE 

FMC dual- speed screens t or approximate t p)t

Anchoa mi tchi 11 i

Leiostomus xanthurus

Opsanus tau

Prionotus caro1inus

Trinectes maculatus

All finfish

Ca11inectes sapidus

4 . 1:t1. 5

5 . 8:t1. 

3 . o:to . 9

7 . 9!2 . 2

15 . 8!3 . 8

41.4!6.25 . 6:t3 . 3

0 . 8!0 . 3

nO.nO.

1. no . 

8. 6!2 . 9

15. n3.

19. 6:t3.

11t

46t

75t

1.53

35t

1.17

044033020010

0 . 132 ns

002

246 ns

*Approximate t-tests were used where variances were significantly heterogeneous (SAS Institute , 1982).