Contaminant Analysis of Fillets from Great Lakes Coho Salmon, 1980

J. Great Lakes Res. 10(1):38-47 Internat. Assoc. Great Lakes Res., 1984

CONTAMINANT ANALYSIS OF FILLETS FROM GREAT LAKES COHO SALMON, 1980

James R. ClarkI, Dave DeVau)t2, and Robert J. Bowden U.S. Environmental Protection Agency Great Lakes National Program Office 536 South Clark Street Room 102 Chicago, Illinois 60605 and Joseph A. Weishaar U. S. Food and Drug Administration Department of Health and Human Services 240 Hennepin A venue Minneapolis, Minnesota 55401

ABSTRACT. Analyses ofcoho salmon from each of the Great Lakes by a single laboratory produced residue data on the accumulation of environmental contaminants which have been banned, severely restricted, or are currently permitted in the basin. Coho salmon from Lake Superior contained only trace amounts or low levels of most toxic substances quantified; Lake Erie fish were contaminated with low levels of a number of pesticides and industrial compounds; relatively higher residues were detected in coho from Lake Huron and Lake Michigan; and the highest concentrations for a number of compounds were found in fillets from coho from Lake Ontario. Contaminant concentrations in migratory coho salmon indicate open lake contaminant problems rather than point source or nearshore conditions. Tissue residues were less than USFDA action levels, used by many agencies in assessing the severity offish contaminant problems. Only mirex concentrations in fish collected from Lake Ontario exceeded a USFDA action level. The data reported in this study generally agree with recent findings from individual state contaminant monitoring programs. Problems with varying analytical and sampling techniques preclude direct comparisons with previously published data of other studies. ADDITIONAL INDEX WORDS: Toxic substances, pesticides, monitoring, public health.

(GLNPO 1981) was designed and implemented to provide interagency coordination and cooperation for gathering information on toxic substance problems in the Great Lakes. One element of the strategy addressed the potential public health concerns associated with contaminants in game fish through the collection and analysis of fall run coho salmon (Oncorhynchus kisutch). The purpose of this paper is to report the results of contaminant analyses of coho salmon fillets collected in 1980 from fish captured at 12 sites located throughout the Great Lakes basin and analyzed by a single laboratory. Coho salmon were chosen for contaminant monitoring because of their rapid growth rates and

INTRODUCTION Fish contaminant monitoring programs have been implemented by state and federal agencies throughout the Great Lakes basin with varying levels of intensity to address toxic substance problems. The Great Lakes Fish Monitoring Strategy lCurrent address: USEPA. Environmental Research Laboratory, Sabine Island, Gulf Breeze, FL 32561 2To whom correspondence should be addressed. "Although the research described in this article has been funded wholly or in part by the U.S. Environmental Protection Agency, it has not been subjected to the Agency's required peer and policy review and, therefore, does not necessarily reflect the views of the Agency and no official endorsement should be inferred."

38

CONTAMINANT ANALYSIS OF SALMON migratory behavior. As a top predator in the Great Lakes, coho salmon consume large quantities of forage fish, leading to rapid bioaccumulation of organochlorines and other toxic substances. Many of these chemicals are deposited in the abundant lipid reserves of the salmon. Because mature fish return to tributaries to spawn at the end of their 3year life cycle, numerous coho salmon of a uniform age group can be sampled relatively easily. This short life span provides an indication of recent contaminant accumulation as opposed to the extended picture given by more long lived species such as lake trout (Salvelinus namaycush). Contaminant concentrations are a public health concern due to the popularity of coho salmon as sport fish. Although public health concerns are the major emphasis in this element of the Great Lakes Fish Monitoring Strategy, an added benefit is the ability to compare residue concentrations over each of the Great Lakes for fish of the same species, age, and physiological condition which were analyzed by a

single laboratory using a consistent methodology. The lack of uniformity in these parameters and other factors have prevented valid comparisons between fish contaminant data sets from individual Great Lakes generated as part of independent agency programs. The data reported in this paper are primarily intended for potential characterization of residue concentrations for coho collected at each site relative to public health concerns. While lake-to-Iake comparisons are presented, other elements of the strategy were designed specifically to provide such comparisons through more detailed statistical techniques (GLNPO 1981). METHODS State agency personnel collected adult coho salmon as the fish began their fall, upstream migrations in 1980. When sufficient fish were available, 15 coho salmon were collected at 12 sites throughout the Great Lakes Basin (Fig. 1). In the field each fish was weighed, measured for standard length, and a single lateral, skin-on fillet excised using a procedure outlined in the Great Lakes Fish Monitoring Strategy (GLNPO 1981). Fillets were composited five per sample. The mean lengths and weights, with sample ranges, for fish yielding fillets to the composite samples are listed in Table 1. The fish samples were frozen and shipped to the

Pine Creek Wisconsin

S 1

St Joseph River Michigan .. M 4 Detroit River Trail Creek Michigan Indiana E 1 M3

39

..

E

~

j(E EPI

o

lP-

.YHuron River Ohio E2

FIG. 1. Tributary locations for 1980 coho salmon collections.

rout Run Trib Pennsylvania

E4 Chargrin River Ohio E3

40

CLARK et a/.

TABLE 1. Data from coho salmon yielding fillets for contaminant analyses. Collection Site and Date

Sample #

# Fish Composited

Age

Mean Length

(Range)

Mean Weight

(Range)

Lake Superior Pine Creek (S I)" Ashland, WI 17/09/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

492 mm 534 mm 561 mm

(368-533) (523-549) (551-587)

1.14kg 1.36kg 1.75kg

(Not taken) (Not taken) (Not taken)

Lake Michigan Sheboygan River (M I) Sheboygan, WI 16/12/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

606 mm 654 mm 671 mm

(560-630) (630-650) (655-685)

1.88kg 2.46kg 3.01kg

(1.65-2.00) (2.00-3.00) (2.85-3.20)

Kellogg Creek (M2) Waukegan, IL 14-23/10/81

I 2 3

5 5 5

3 yr 3 yr 3 yr

660 mm 695 mm 673 mm

(605-725) (655-725) (610-750)

3.38kg 3.49kg 3.67kg

(2.68-5.35) (2.50-5.35) (2.65-5.90)

Trail Creek (M3) Michigan City, IN 30/9-14/10-80

I 2 3

5 5 5

3 yr 3 yr 3 yr

629mm 690mm 710mm

(490-714) (663-719) (632-749)

2.74kg 3.49kg 4.15kg

(1.50-4.27) (2.59-4.31) (2.45-5.31)

St. Joseph River (M4) Berrien Sprs., MI 15/10/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

680mm 715 mm 740mm

(691-720) (688-731) (711-767)

2.84kg 3.47kg 4.18kg

(2.39-3.28) (3.31-3.56) (3.80-4.43)

Platte River (M5) Beulah, MI 24/9/80

I 2 3

4 4 3

3 yr 3 yr 3 yr

640mm 672mm 714 mm

(633-648) (653-690) (669-800)

2.73kg 2.88kg 4. 13kg

(2.58-2.81) (2.84-2.98) (3.25-5.71)

Lake Huron Tawas River (HI) Tawas City, MI 3/10/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

701 mm 727mm 729mm

(649-726) (710-749) (698-755)

3.53kg 4.17kg 4.44kg

(2.46-3.94) (3.97-4.26) (4.22-4.69)

Lake Erie Detroit River (EI) Detroit, MI 22/10/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

636 mm 651 mm 676 mm

(606-664) (628-675) (628-724)

2.27kg 2.62kg 3.23kg

(1.86-2.52) (2.52-3.39) (2.95-3.39)

Huron River (E2) Huron,OH 16/10-11/12/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

626 mm 658 mm 620mm

(585-690) (597-737) (597-648)

2.62kg 2.87kg 3.lOkg

(2.00-3.50) (2.27-3.63) (2.72-4.08)

Chagrin River (E3) Eastlake, OH 8/10/80

I 2 3

5 5 5

3 yr 3 yr 3 yr

604mm 627 mm 599 mm

(546-660) (584-647) (546-647)

2.76kg 3.04kg 3.13kg

(1.81-3.85) (2.72-3.40) (2.98-3.40)

Trib to Trout Run (E4) Erie Co., PA 30/9/80

I 2 3

5 5 5

2 yr 2 yr 3 yr

390 mm 457 mm 606 mm

(353-445) (445-470) (590-630)

0.60kg 1.00kg 2.14kg

(0.40-0.85) (0.88-1.08) (1.90-2.35)

I 2 3

5 5 5

3 yr 3 yr 3 yr

731 mm 789 mm 800 mm

(688-755) (781-800) (786-820)

3.88kg 4.89kg 5.28kg

(3.44-4.42) (4.73-5.02) (5.04-5.54)

Lake Ontario Spring Brook (01) Pulaski, NY 6/11/80

"Code in parenthesis refers to site designation in Figure I.

CONTAMINANT ANALYSIS OF SALMON USFDA laboratory in Minneapolis, Minnesota, for analysis. The samples were then stored at -20 D C for up to 3 weeks until assayed. The five fish fillets in each sample were ground into a uniform tissue homogenate. An aliquot of this homogenate was weighed and analyzed for contaminant residues according to the USFDA Pesticide Analytical Manual (USFDA 1980). Contaminants were extracted from the fish tissue in petroleum ether and fats separated from the sample using petroleum ether lacetonitrile partitioning. The sample preparations were then added to a Florisil column. Three solutions of increasing polarity were put through the column, providing distinct preparations for analysis with interferences limited to interactions of individual and multipeak contaminants. Mirex and 8-monohydromirex (photomirex) determination involved the triple extraction of fish tissue in petroleum ether with separation of fats using an unactivated Forisil column. The mirex and 8-monohydromirex were partially separated from the other contaminants using an activated Forisil column. Additional cleanup was by a nitration process followed by an alumina column after Norstrom et al. (1980). Organochlorines were quantified on a HewlettPackard gas-liquid chromatograph using a nickel63 electron capture detector. Organophosphates were determined on a Tracor 560 gas-liquid chromatograph with a flame photometric detector. Total mercury was determined through flameless atomic absorption spectrophotometry. Analytical grade standards and pesticide grade solvents were used in the analyses. Analytical detection limits for organic compounds were 0.005 p,g/g, although residue levels below 0.01 p,g/g, were not quantified but reported as "trace." A series of chlorinated chemicals resembling toxaphene were quantified at 0.25 p,g/g or greater using a toxaphene standard. Total mercury was quantified at 0.05 p,g/g or greater concentrations. All fish tissue levels were computed on a p,gl g wet weight basis and not corrected for extraction or recovery efficiency. Means, standard deviations, and Pearson product moment correlation coefficients were computed using the University of Chicago computer package, IDA. RESULTS Laboratory analyses identified 30 pesticides and industrial chemicals in the 36 coho salmon samples

41

analyzed (Table 2). These include compounds currently in use in the Great Lakes basin and substances whose uses have been banned, such as PCB and DDT, or severely restricted, such as chlordane. Diazinon and chlorpyrifos were the only organophosphate pesticides detected. Although none of the PCB residues approached the USFDA action level of 5 p,gl g, PCBs were the most prominent contaminant found (Table 2). Total PCB concentrations were highest in coho from Lake Ontario, an average of 2.90 p,g/g, while only traces were detected in Lake Superior fish. Coho samples from Lake Erie averaged 1.07 p,gl g PCBs, while those from Lake Michigan and Lake Huron averaged 1.93 and 1.95 p,g/g, respectively. The data show remarkable homogeneity in mean PCB concentration when samples within a lake basin (Le., Lake Michigan or Lake Erie) are compared. Aroclor 1254 accounted for 64% of the four aroclors quantified. A residue of Aroclor 1242, identified using chromatographs of appropriate standards, was found only in fish samples from tributaries along the western shore of Lake Michigan. These sites are near two harbors (Sheboygan, Wisconsin, and Waukegan, Illinois), where Aroclor 1242 has been a contributing pollutant. The relative amounts of Aroclor 1260, 1254, and 1248 in the other coho samples are similar to those previously reported for other Great Lakes fish (Veith et al. 1981, Schmitt et al. 1981). Total DDT values ranged between 0.36 and 1.03 p,g/g for coho from Lakes Michigan, Huron, and Ontario (Table 2). Lake Erie fish contained between 0.13 and 0.22 p,g/g DDTs, while less than 0.05 p,g/g total DDT was found in Lake Superior fish. All of these values are considerably below the 5.0 p,g/g USFDA action level for the commercial sale of fish. The p,p-DDE isomer accounted for over 85% of the DDT residues. Ratios of p,p-DDE to p,p-DDT varied among the sample sites throughout the basin, ranging from 7.4 to 22.6 in Lake Michigan coho and 3.5 to infinity in Lake Erie fish where no p,p-DDT was detected. A series of chlorinated camphenes with a retention time similar to toxaphene was detected in the coho salmon samples and is reported as "apparent toxaphene." It was quantified using toxaphene standards, although several of the gas chromatographic peaks of the standard were consistently absent in the sample chromatograms. "Apparent toxaphene" concentrations in Lake Michigan and Lake Huron coho salmon were similar, ranging from 0.8 to 1. 7 p,g/g (Table 2). Lake Superior coho

~

l>J

TABLE 2. Contaminant concentrations (jlg/g) from three samples of coho salmon fillets collected at 12 Great Lakes tributaries in the fall of 1980a ,b,c. Five fillets were composited per sample. Lake Superior SI Pine Creek, WI

Lake Michigan M2 Kellogg Cr., IL

MI Sheboygan R., WI

M3 Trail Cr., IN

M4 St. Joe R., MI

M5 Platte R., MI

Contaminant Arochlor 1260 Arochlor 1254 Arochlor 1248 Arochlor 1242 Total PCBs

T T ND ND T

T T ND ND T

T T ND ND T

0.20 0.79 ND 0.52 1.51

0.31 1.23 ND 0.81 2.35

0.24 0.96 ND 0.63 1.83

0.24 0.96 0.26 ND 1.46

0.27 1.07 0.29 ND 1.63

0.19 0.75 ND 1.37 2.31

0.28 1.11 0.30 ND 1.69

0.39 1.55 0.42 ND 2.36

0.32 1.30 0.35 ND 1.97

0.28 1.12 0.31 ND 1.71

0.32 1.29 0.35 ND 1.96

0.41 1.63 0.44 ND 2.48

0.25 1.01 0.27 ND 1.53

0.26 1.02 0.28 ND 1.56

0.43 1.70 0.46 ND 2.59

p,p-DDE p,p-DDD p,p-DDT Total DDTs

0.02 ND T 0.02

0.03 ND T 0.03

0.04 ND T 0.04

0.37 0.03 0.05 0.45

0.56 0.04 0.06 -0.66

0.43 0.04 0.05 0.52

0.59 0.04 0.03 0.66

0.61 0.05 0.04 0.70

0.44 0.03 0.04 0.51

0.45 T 0.04 0.49

0.98 T 0.05 1.03

0.57 T 0.05 0.62

0.41 0.04 0.02 0.47

0.58 0.04 0.04 0.66

0.60 0.05 0.06 0.71

0.37 0.04 0.04 0.45

0.37 0.03 0.03 0.43

0.68 0.05 0.03 0.76

"Apparent Toxaphene" Mirex Dieldrin Endrin cis-Chlordane trans-Chlordane cis-Nonachlor trans-Nonachlor

0.6 ND T T T T ND T

T ND T T T T ND T

0.4 ND T T T T ND 0.01

1.2 ND 0.05 T 0.05 0.02 0.02 0.06

1.7 ND 0.06 T 0.05 0.02 0.03 0.10

1.4 ND 0.06 T 0.05 0.02 0.03 0.07

0.8 ND 0.06 T 0.05 0.03 0.04 0.07

1.0 ND 0.05 T 0.04 0.04 0.04 0.08

0.8 ND 0.05 T 0.05 0.04 0.03 0.06

1.4 ND 0.08 0.01 0.06 0.04 ND 0.05

1.4 ND 0.03 T 0.06 0.04 ND 0.05

1.7 ND 0.10 0.01 0.07 0.05 ND 0.06

1.0 ND 0.03 T 0.05 0.03 0.03 0.07

1.4 ND 0.05 T 0.05 0.03 0.03 0.09

1.6 ND 0.07 T 0.06 0.03 0.04 0.09

1.4 ND 0.07 T 0.05 0.03 0.03 0.07

1.0 ND 0.05 T 0.04 0.02 0.03 0.06

1.6 ND 0.11 T 0.06 0.03 0.04 0.09

Mercury

0.10

0.11

0.15

0.11

0.14

0.13

0.13

0.12

0.12

0.07

0.11

0.07

0.13

0.20

0.19

0.10

0.11

0.16

Hexachlorobenzene Octachlor epoxide Heptachlor Heptachlor epoxide alpha-BHC Lindane (gamma-BHC) Dacthal Pentachlorophenyl methyl ether Hexachlorobutadiene 1,2,3,4-Tetrachlorobenzene Heptachloronorbornadiene Chlorpyrifos Diazinon Trifluralin 8, Monohydromirex (photomirex)

T ND ND ND T ND ND

T ND ND ND T ND ND

T ND ND ND T ND ND

T T ND T T ND T

T T ND T T ND T

T T ND T T ND T

ND 0.01 T T T ND T

ND 0.01 T T T ND T

ND 0.01 T T T ND T

0.01 0.01 T T T T T

0.01 0.02 T T T T 0.02

0.01 0.01 T T 0.01 T T

T 0.01 ND ND T ND ND

T 0.02 ND ND T ND ND

T 0.02 ND ND T ND ND

T T ND T T ND T

T T ND T T ND T

T 0.03 ND T T ND T

ND ND ND ND ND ND ND

ND ND ND ND ND ND ND

ND ND ND ND ND ND ND

T ND ND ND ND .ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND T

T ND ND ND ND T ND

T ND ND ND ND ND ND

T ND ND ND ND T ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

T ND ND ND ND ND ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

n

t""I

> ~ ==

... ~

l::l

:--

TABLE 2. Continued Lake Ontario

Lake Huron

01 Spring Brook, NY

HI Tawas R., MI

Lake Erie E2 Huron R., OH

EI Detroit R., MI

E3 Chagrin, R., OH

E4 Trout Run Trib., PA

Contaminant Arochlor 1260 Arochlor 1254 Arochlor 1248 Arochlor 1242 Total PCBs

0.43 1.72 0.47 ND 2.62

0.56 2.26 0.61 ND 2.43

0.60 2.39 0.65 ND 3.64

0.31 1.24 0.34 ND 1.89

0.33 1.31 0.36 ND 2.00

0.32 1.28 0.35 ND 1.95

0.20 0.81 0.22 ND 1.23

0.19 0.77 0.21 ND 1.17

0.15 0.60 0.16 ND 0.91

0.15 0.59 0.16 ND 0.90

0.12 0.48 0.13 ND 0.73

0.23 0.90 0.25 ND 1.38

0.17 0.70 0.19 ND 1.06

0.17 0.69 0.19 ND 1.05

0.18 0.72 0.20 ND 1.10

0.13 0.50 0.14 ND 0.77

0.16 0.65 0.18 ND 0.99

0.19 0.77 0.21 ND 1.17

p,p-ODE p,p-OOO p,p-DOT TotalOOTs

0.49 0.07 T 0.56

0.80 0.10 0.04 0.94

0.73 0.11 0.05 0.89

0.33 0.03 -T 0.36

0.39 0.03 0.03 0.45

0.37 0.02 0.02 0.41

0.10 0.10 0.02 0.22

0.08 0.09 0.02 0.19

0.07 0.08 0.02 0.17

0.07 0.06 T 0.13

0.07 0.07 T 0.14

0.07 0.07 T 0.14

0.08 0.10 T 0.18

0.07 0.08 T 0.15

0.07 0.08 T 0.15

0.10 0.06 ND 0.16

0.09 0.06 ND 0.15

0.10 0.07 ND 0.17

"Apparent Toxaphene" Mirex Oieldrin Endrin cis-Chlordane trans-Chlordane cis-Nonachlor trans-Nonachlor

0.5 0.10 0.02 T 0.04 0.02 0.03 0.04

0.8 0.16 0.03 T 0.05 0.02 0.04 0.06

1.0 0.16 0.03 T 0.05 0.03 0.04 0.06

1.4 NO 0.04 T 0.03 0.01 0.02 0.05

1.6 ND 0.04 T 0.04 0.01 0.03 0.06

1.4 ND 0.03 T 0.03 0.01 0.02 0.05

0.4 ND 0.02 T 0.02 0.04 NO 0.03

0.4 ND 0.03 T 0.01 0.03 NO 0.02

0.3 ND 0.02 T 0.01 0.02 ND 0.02

T NO 0.03 T 0.03 0.02 ND 0.03

T NO 0.03 T 0.02 0.01 ND 0.02

T ND 0.04 T 0.02 T NO 0.03

T ND 0.05 T 0.03 0.01 T 0.03

T ND 0.04 T 0.03 0.01 T 0.03

T ND 0.04 T 0.03 0.01 T 0.03

NO ND 0.05 T 0.02 0.01 NO 0.02

NO ND 0.04 T 0.02 0.01 NO 0.02

ND NO 0.09 0.01 0.02 0.01 ND 0.02

Mercury

0.30

0.28

0.30

0.21

0.25

0.24

0.14

0.14

0.14

0.14

0.13

0.14

0.12

0.12

0.12

0.08

0.09

0.15

Hexachlorobenzene Octachlor epoxide Heptachlor Heptachlor epoxide alpha-BHC Lindane (gamma-BHe) Oacthal Pentachlorophenyl methyl ether Hexachlorobutadiene 1,2,3,4-Tetrachlorobenzene Heptachloronorbornadiene Chlorpyrifos Diazinon Trifluralin 8, Monohydromirex (photomirex)

0.01 0.01 NO NO T NO NO

0.02 0.02 NO NO T ND ND

0.02 0.02 NO NO T NO ND

T 0.01 NO NO 0.01 T ND

T 0.01 NO NO 0.01 T NO

T 0.01 NO NO 0.01 T ND

0.01 T ND T 0.01 NO T

0.01 T NO T 0.01 NO T

0.01 T NO T 0.01 NO T

0.01 T ND T T T T

T T ND NO T T T

0.01 T NO T T T T

0.01 T NO NO 0.01 T 0.02

0.01 T NO NO 0.01 T 0.01

0.01 T NO ND 0.01 T 0.01

0.01 NO NO T T ND 0.04

0.01 NO NO T T ND 0.03

0.01 NO NO T T ND T

T NO NO NO NO NO NO

T NO NO NO NO NO NO

T NO NO NO ND ND ND

T NO NO ND ND ND ND

T ND ND NO NO NO ND

T ND ND NO NO NO ND

ND 0.01 NO NO NO NO NO

NO T ND ND ND NO NO

NO T ND NO ND NO NO

T ND ND NO ND ND NO

T NO NO NO NO ND NO

T NO ND ND NO NO NO

T T 0.03 T T T NO

T ND NO ND T T ND

T T T NO T T NO

T ND ND ND ND ND NO

T NO NO ND ND ND NO

T ND NO NO ND T ND

0.08

0.09

0.06

NO

NO

ND

NO

ND

NO

ND

NO

ND

ND

ND

ND

ND

NO

ND

~

0 Z

~

:: Z

> Z

""3

> Z > ~

00 00

0

Io'!j

00

> t"'"

::0 Z

adetection limits 0.005 p.g/g except for "apparent toxaphene" which was 0.25 p.g/g and mercury at 0.05 p.g/g. bNDN = none detected. cT = compound present but below 0.01 p.g/g or below mg/g for "apparent toxaphene".

"'"

(,H

CLARK et al.

44

were slightly contaminated with this residue ( 0.25 to 0.6 /lg/g), while Lake Ontario fish contained between 0.5 and 1.0 /lg/g. When present, only low levels of "apparent toxaphene" were found in fish from Lake Erie. Mirex and photomirex were found only in coho salmon from Lake Ontario. Mirex levels in the composite fillets from the Spring Brook site were between 0.10 and 0.16 /lg/g, exceeding the USFDA guideline of 0.1 /lgl g. Photomirex (8-monohydromirex) was also detected in these samples at concentrations between 0.06 and 0.09 /lg/g. The pesticides dieldrin, endrin, chlordane, nonachlor, and BHC were detected at low levels in the coho salmon samples from throughout the Great Lakes basin (Table 2). Low levels or traces of hexachlorobenzene, octachlor epoxide, heptachlor or heptachlor epoxide, and dacthal were also detected in most of the fish samples. Traces of a derivation or impurity of pentachlorophenol, pentachlorophenyl methyl ether, were detected in all samples, except those from Lake Superior and the Detroit River. Lindane, hexachlorobutadiene, tetrachlorobenzene, heptachloronorbornadiene, and chlorpyrifos were encountered in trace amounts in fish samples from the Chagrin River and individually at a few other sites. Diazinon was detected in samples from Trail Creek, Indiana, and trace amounts of trifluralin were found in one sample from Kellogg Creek, Illinois. The highest levels of total mercury occurred in fish from Lake Ontario, with a mean of 0.29 /lg/g (Table 2). Coho from Lake Huron had a mean mercury concentration of 0.23 /lgl g. Total mercury concentrations in fish from the other Great Lakes sites ranged from 0.07 and 0.20 /lg/g. None of the mercury values approached the USFDA guideline level of 1.0 /lg/g. DISCUSSION

These data represent some of the first environmental samples where presently employed pesticides such as dacthal, chlorpyrifos, diazinon, and trifluralin have been reported in fish of the Great Lakes basin. Low levels of dieldrin, endrin, chlordane, nonachlor, heptachlor or heptachlor epoxide, octachlor epoxide, and BHC in coho salmon reflect a combination of each pesticide's environmental persistence, bioaccumulative potential, and exposure concentration in the Great Lakes basin. The continued presence of PCBs, DDTs, mercury, and mirex illustrates the persistence of some toxic

substances after regulatory measures have been enacted to control their production and use. Mirex levels previously have been reported to exceed USFDA action levels in Lake Ontario salmonids and other game fish (Armstrong and Sloan 1980). The coho salmon fillets we analyzed from the Lake Ontario tributary equalled or exceeded the USFDA mirex action level of 0.1 /lgl g (Table 1). Although PCB levels did not exceed the 5.0 /lg/g FDA action level, a composite of five fillets from Lake Ontario reached 3.64 /lg/g. Therefore, it is conceivable that some of the individual fillets may have exceeded the action level but were diluted out by less contaminated fillets in the sample. None of the PCB, DDT, "apparent toxaphene," mercury, dieldrin, or endrin concentrations approached USFDA action levels. Most of the states in the Great Lakes basin have public health advisories on consumption of Great Lakes fish due to organochlorine or mercury contamination. Although almost all contaminant residue concentrations in these coho salmon samples were below USFDA action levels for individual contaminants, their collective presence contributes to the total body burden of organochlorines in the fish and the fish consuming public.· Other toxic substances listed in Table 2 pose additional concern, althrough no criteria have been set establishing acceptable levels of these compounds for the fish consuming public. Further study is necessary to critically evaluate the potential for public health and environmental problems associated with these compounds. The concentrations of contaminants found in this study agree with values recently reported by individual state agency monitoring programs. Michigan, Indiana, and Wisconsin have reported recent mean PCB levels in coho salmon ranging from near 1 /lg/g to over 4 /lg/g, when analyzing fillet or whole fish preparations from Lake Michigan (Lauer 1980, Sheffy and St. Amant 1980, Rohrer et al. 1982). A 1980 Michigan Department of Natural Resources (MDNR) intensive study of salmon contaminant levels, using fillets collected and prepared similar to those analyzed in this study, reported similar PCB and DDT concentrations (Rohrer et al. 1982). However, the uniformity of PCB concentrations in coho collected at several Lake Michigan tributaries seen in Table 2 was not evident in the MDNR study. They and others have reported relatively higher residue concentrations in fish from the southern end of Lake Michigan (Veith 1975, Rohrer et al. 1982), implying some

4S

CONTAMINANT ANALYSIS OF SALMON

p,g/g to 0.18 p,g/g for mirex. PCB concentrations in coho salmon sampled from Spring Brook between November 1981 and April 1982 averaged 2.31 p,g/g (NYDEC 1982). These values are consistent with the data in Table 2. Limited mercury data were also in general agreement. The relative concentrations of contaminants in a popular sport fish common to all of the Great Lakes are important when considering potential contaminant exposure levels for the fish consuming public. The mean concentrations of the most prominent contaminants quantified from the coho salmon fillets are presented as lake-wide averages in Table 3. These data demonstrate that fillets of coho salmon from Lake Ontario are more heavily burdened with PCBs, DDTs, and mirex than samples from other lakes. Residues of "apparent toxaphene" are highest in coho fillets from Lake Huron and Lake Michigan. Human exposure to mercury would be highest when fish from Lake Ontario or Lake Huron are consumed. The concentrations of each contaminant were significantly and positively correlated with the average weight of the fish comprising the sample (Table 4). Because each of these contaminants occurs in a lipid soluble form, it is not surprising that each was significantly correlated to another, except for "apparent toxaphene" and mercury. More detailed comparisons among the data were not attempted because of the limited and unequal number of sam-

limits on the movements of open lake fish in Lake Michigan. Contaminant data on coho salmon from Lake Huron and Lake Erie for 1979 and 1980 also agreed with the PCB and DDT concentrations reported in Table 2. MDNR found mean PCB residues of 2.70 p,g/g and 1.20 p,g/g in coho from the Tawas River and the Detroit River, respectively (Rohrer et al. 1982). Residues of DDT, dieldrin, and mercury at these sites also corresponded very closely to those found in this study. Coho contaminant data released by the Ohio Department of Natural Resources (ODNR) showed 1979 PCB levels of 1.35 p,g/g and 0.90 p,g/g for fish caught in Lake Erie off Vermilion and Lorain, Ohio, respectively (ODNR 1980). Coho salmon collected in the New York waters of Lake Erie averaged 1.24 p,g/g in 1977 (Armstrong and Sloan 1980). The homogeneity in the contaminant concentrations reported for Lake Erie in Table 2 and the data from other monitoring programs reflect the ability of coho salmon to integrate whole lake exposure levels. Contaminant residue concentrations for Lake Ontario coho from the New York Department of Environmental Conservation fish monitoring program for 1976 through 1979 vary extensively with the site, season sampled, and the size of fish collected (Armstrong and Sloan 1980; NYDEC 1978, 1979). Values ranged from 1.5 p,g/g to 4.5 p,g/g for PCBs, 0.11 p,g/g to 1.23 p,g/g for DDTs, and 0.02

TABLE 3. Mean and standard deviation for weights (kg) of fish yielding fillets for contaminant analyses and the concentration of major contaminants (p,g/g) for coho salmon samples pooled on a lake-wide basis. Only data from 3-year-old fish are included (Ref. Tables 1,2). Lake Superior N=3

Lake Michigan N= 15

Lake Huron N=3

Lake Erie N=1O

Lake Ontario N=3

1.42 (0.309)

3.21 (0.659)

4.05 (0.467)

2.78 (0.378)

4.68 (0.723)

PCBs

Trace levels only

1.93 (0.392)

1.95 (0.055)

1.07 (0.187)

2.90 (0.651)

DOTs

0.03 (0.010)

0.61 (0.160)

0.41 (0.044)

0.17 (0.032)

0.80 (0.206)

"Apparent Toxaphene"

0.38 (0.238)

1.29 (0.308)

1.53 (0.115)

0.19 (0.134)

0.77 (0.252)

Mercury

0.12 (0.026)

0.13 (0.037)

0.23 (0.021)

0.13 (0.011)

0.29 (0.012)

NO

NO

NO

NO

0.14 (0.035)

Fish Weight Contaminant

Mirex

CLARK et al.

46

TABLE 4. Correlation coefficients for mean fish weight and concentrations of major contaminants for coho salmon fillets from 3-year-old fish collected in the fall of 1980. N = 44. PCBs

DDTs

"Apparent Toxaphene"

Mercury

0.69** 0.35** 0.67**

0.13 0.43*

0.64**

0.83**

DDTs "Apparent Toxaphene" 0.59** 0.61** Mercury 0.81** Fish Weight *significant at P < 0.05. **significant at P < 0.01.

pIes from each lake and the inability to correct concomitantly for differences in size and lipid content. The relatively low contaminant levels for coho salmon from Lake Superior reflect the low levels of contaminant inputs from the watershed. Also, the colder water temperatures may reduce the potential rate of contaminant uptake for elements in the food chain. This is reflected in the smaller size of the Lake Superior fish. However, the high levels of "apparent toxaphene" in Lake Superior coho are not explained by this reasoning and may be related to a higher loading rate. The very high level of productivity and sedimentation in Lake Erie tends to bind up contaminants and take them out of the system before they find their way into the top carnivore fishes. Lakes Huron, Michigan, and Ontario, with their more intermediate levels of productivity and sedimentation and high levels of contaminant inputs, appear to have more significant fish contaminant problems. Comparisons of the relative concentrations of the contaminants found in this study of coho samples from various sites throughout the Great Lakes basin must be tempered by the fact that neither size nor lipid content can be held constant when attempting to obtain replicate samples. Each lake presents a different environment for growth, yielding fish of different physiological condition and size at the end of their life span. Although each fish in our collection was the same age (except for the 2-year-old fish from the Pennsylvania site), the size of the fish we analyzed varied between lakes and sites. Contaminant levels are known to be higher in larger fish or those with greater lipid content. Lipid content was not determined for these samples, since the tissue concentrations available for human consumption were of primary interest in the design of the program. The ability to make

site-to-site comparisons adds considerable utility to the data set, thus lipid analyses will be included in subsequent studies. No assessment of trends in contaminant concentrations through time for coho throughout the Great Lakes has been attempted since the aggregate data set from the literature would not be amenable to statistical analyses. The lack of consistency of fish size, collection dates and sites, and analytical methods among the data sets and throughout the years will add variability, which could overshadow any statistical trends in residue concentration within a lake. However, the contemporary residue levels are generally less than those reported in the 1960s and early 1970s (IJC 1978). Each lake presents an individual environment yielding fish of distinctive size and fat content. The data describe the potential for human exposure to a variety of contaminants, which varies from lake to lake. Continued monitoring and research in fish contaminant problems is necessary to determine potential exposure for the fish consuming public. SUMMARY

Organochlorine compounds continue to be detected in open lake fish of the Great Lakes, although use of many of the contaminants has been banned or severely restricted. Other currently employed pesticides are finding their way into the Great Lakes and can be quantified or detected in coho salmon fillets. Current USFDA action levels suggest only mirex levels in coho from Lake Ontario pose a current public health problem. Although strict trend analyses are not appropriate for comparing these data with those provided by previous studies, the results do indicate that contaminant residue levels are comparable among contemporary studies and appear to be less than historical levels for PCBs, DDTs, and mercury. Continued monitoring is necessary to chronicle the occurrence and distribution of new toxic chemicals and the trends in contaminant levels in Great Lakes coho salmon. REFERENCES

Armstrong, R. W., and Sloan, R. J. 1980. Trends in levels ofseveral known chemical contaminants in fish from New York State waters. New York State

Department of Environmental Conservation. Albany, New York, June 1980. Great Lakes National Program Office (GLNPO). 1981. A strategy for fish contaminant monitoring in the Great Lakes. USEPA, GLNPO, Chicago, Illinois.

CONTAMINANT ANALYSIS OF SALMON

47

International Joint Commission (IJC). 1978. Great Lakes water quality status report, appendix E. Great Lakes Water Quality Board. Windsor, Ontario, Canada. Lauer, T. 1980. Results of cooperative fish contaminant

Rohrer, T. K., Forney, J. C., and Hartig, J. H. 1982. Organochlorine and heavy metal residues in standard fillets of coho and chinook salmon of the Great Lakes 1980. J. Great Lakes Res. 8:623-634. Sheffy, T. B., and St. Amant, J. R. 1980. Toxic sub-

monitoring program between the Indiana State Board ofHealth and the Indiana Department ofNatural Resources. ISBH, Indianapolis, Indiana. New York Department of Environmental Conservation. 1978. Monthly reports on toxic substances impacting fish and wildlife. Report 12, March 20, 1978. NYDEC, Albany, New York. _ _ _ _ . 1979. Quarterly reports on toxic substances impacting fish and wildlife. Volume 3, report 1, June 20, 1979, NYDEC, Albany, New York. _ _ _ _ . 1982. Toxic substances in fish and wildlife. November 1, 1981 to April 30, 1982. Volume 5, No. 1, NYDEC Technical Reports, Albany, New York. Norstrom, R. J., Won, H. T., Holdrin, M. O. H., Calway, P. G., and Naftel, C. D. 1980. Gas liquid chromatographic determination of mirex and photomirex in the presence of polychlorinated biphenyls. J. Assoc. Of Anal. Chem. 63:53-59. Ohio Department of Natural Resources (ODNR). 1980. 1979 status of PCBs in Lake Erie fishes. ODNR Communication, Columbus, Ohio.

stances survey ofLakes Michigan, Superior, and tributary streams; first annual report. Wisconsin Department of Natural Resources, Madison, Wisconsin. September, 1980. Schmitt, C. J., Ludke, J. L., and Walsh, D. F. 1981. Organochlorine residues in fish: National Pesticide Monitoring Program, 1970-1974. Pestic. Monit J. 14: 136-206. U.S. Food and Drug Administration (USFDA). 1980. Pesticide Analytical Manual. Volume 1. US Department of Health and Human Services, Washington, D.C. Veith, G. C. 1975. Baseline concentrations of polychlorinated biphenyls and DDT in Lake Michigan fish, 1971. Pestie. Monit. J. 9:21-29. _ _ _ _ , Kuehl, D. W., Leonard, E. N., Welch, K., and Pratt, G. 1981. Polychlorinated biphenyls and other organic chemical residues in fish from major watersheds near the Great Lakes, 1978. Pestic. Monit. J. 5:1-8.