the Los Angeles County sewer system which flows 

 via sewer outfalls into the marine environment of 

 southern California. From this unanticipated 

 source of iDDT pollution, high levels of IDDT 

 developed throughout the southern California 

 marine environment from mollusks (Young et al. 

 1976), crustaceans (Burnett 1971), and fishes 

 (McDermott-Ehrlich et al. 1978) to marine birds 

 (Anderson et al. 1975) and cetaceans (Le Boeuf 

 and Bonnell 1971). Henderson et al. (1969, 1971) 

 found organochlorine residues in freshwater 

 fishes throughout the United States. Some species 

 of freshwater fishes, especially those from the 

 Great Lakes, contained levels of chlorinated hy- 

 drocarbons that exceeded the U.S. Food and Drug 

 Administration guidelines (Reinert 1970; Veith 

 1975). In recent years, the use of chlorinated hy- 

 drocarbons has been drastically curtailed, but 

 concern remains about the continuing occurrence 

 of these toxic compounds in the marine environ- 

 ment. 



Fishes and shellfishes are excellent organisms 

 for monitoring chlorinated hydrocarbons. 

 Shellfishes have been used as indicators of short- 

 term pollution (Butler 1973; Goldberg et al. 1978) 

 because they accumulate and depurate these sub- 

 stances readily. Fishes, on the other hand, reflect 

 long-term exposure since they lose chlorinated 

 hydrocarbons slowly, if at all (Lieb et al. 1974). 

 Butler and Schutzmann (1978) have reported on 

 pesticides and PCB in yearling estuarine fishes of 

 the United States. Outside of their study, how- 

 ever, few data on fishes for human consumption 

 from the western Atlantic Ocean have been pub- 

 lished except on fishes from Canadian waters 

 (Sims et al. 1977). The study reported here was 

 undertaken to obtain information about levels of 

 SDDT, PCB, dieldrin, and endrin in fillets from 

 fishes caught in the northwestern Atlantic Ocean 

 and northern Gulf of Mexico. Six marine species of 

 both commercial and sport value have been 

 examined. 



FISHERY BULLETIN: VOL. 78. NO. 1 



METHODS 



Samples of gag, Mycteroperca microlepis; black 

 grouper, M. bonaci; red grouper, Epinephelus 

 morio; red snapper, Lutjanus campechanus; king 

 mackerel, S comber omor us cavalla; and Spanish 

 mackerel, S. maculatus, were collected from the 

 northwestern Atlantic Ocean and northern Gulf of 

 Mexico, from Beaufort, N.C., south to the Florida 

 Keys, and west to Aransas Pass, Tex. Sampling 

 occurred between October 1973 and October 1975, 

 but mainly in 1975. Specimens were frozen and 

 held at -18° C. They were thawed for filleting, 

 grinding, compositing, and refrozen until 

 analysis. In the aggregate, 70 samples each con- 

 taining 10 fish of the same species and of similar 

 size were obtained. Each sample was a composite 

 of equal weights of ground skinless fillets from the 

 10 individual fish. At most sites, two or three sam- 

 ples from different size fish were selected. The 

 collection sites, size, and lipid content of the 

 specimens are listed in Table 1. 



Extracts were prepared by the procedures of 

 Reinert (1970). Samples for SDDT and PCB 

 analysis were extracted with propanol-2/benzene 

 (1:1), and the extracted materials transferred to 

 hexane by repeated codistillation of the 

 propanol-2, benzene, and water with hexane. One 

 aliquot of the hexane extract was evaporated to 

 minimum weight for determination of the lipid 

 content. Another aliquot was cleaned up on 

 Florisil.^ PCB were separated from TDE, DDT, 

 and most of the DDE on activated silica gel 

 (Snyder and Reinert 1971), which also separates 

 the interfering hydrocarbons, phenanthrene, 

 fluoranthrene, and pyrene from the PCB (Zitko 

 1978). At least 90% of the PCB was contained in 

 the pentane fraction, which also contained part of 



^Mention of specific products or companies in this paper does 

 not imply endorsement by the National Marine Fisheries Ser- 

 vice, NOAA. 



Table l. — Collection sites, size, and lipid content of fishes from the northwest Atlantic Ocean and Gulf of 



Mexico. 



Species 



Gag 



Black grouper 

 Red grouper 

 Red snapper 

 King mackerel 

 Spanish mackerel 



' 1 - Beaufort, N.C.; 2  Savannah, Ga.; 3 - Florida, East Coast; 4 - Florida Keys; 5 - Tampa/St. Petersburg, Fla.; 6 - Panama City, Fla.; 

 7 - Mobile, Ala.; 8 - Pascagoula, Miss.; 9 - Aransas Pass, Tex. 

 ^Number of composites, each consisting of 10 fish. 

 ^Range of means of individual composites. 



52 



