FISHERY BULLETIN: VOL. 78. NO. 1 



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Florida Keys contained the greatest amounts of 

 both substances, indicating that contamination 

 from agricultural and domestic effluents was 

 greatest in south Florida, an area of intense ag- 

 riculture and relatively dense population as well. 

 Fish caught in the vicinity of Beaufort and Mobile 

 contained slightly less !iDDT and PCB. Fish from 

 the other sites contained lower levels of chlori- 

 nated hydrocarbons, which were not distinguish- 

 able by site, except that only DDE was quanti- 

 fiable in the one sample from Pascagoula, Miss. 

 The Mississippi River, which receives the runoff 

 from 40% of the land mass of the conterminous 

 United States, including the corn belt and the 

 cotton belt, did not seem to be the main source of 

 either SDDT or PCB. 



Low levels of dieldrin and endrin, two highly 

 toxic organochlorine pesticides, were found in the 

 fish included in this study. The highest concentra- 

 tion of either compound was 0.026 ppm. The diel- 

 drin and endrin content of only the three species 

 with the highest levels of SDDT and PCB were 

 determined. Nonetheless, dieldrin and endrin 

 were quantifiable only in about one-third of the 

 samples. Two of 18 red snapper, 7 of 18 king mack- 

 erel, and 6 of 10 Spanish mackerel samples con- 

 tained quantifiable amounts of both compounds. 

 The mean levels for Spanish mackerel, the species 

 with the highest mean concentrations, were 0.007 

 ppm dieldrin and 0.008 ppm endrin (Table 5). King 

 mackerel from Aransas Pass contained the high- 

 est concentration of dieldrin, 0.026 ppm; Spanish 

 mackerel from Panama City, Fla., the highest 

 concentration of endrin, also 0.026 ppm. The diel- 

 drin and endrin concentrations in the three 

 species followed the same distribution patterns 

 with relation to species and lipid content as was 

 observed for SDDT and PCB. Butler (see footnote 

 4) found no dieldrin in the muscle of small Spanish 

 mackerel from the Savannah River estuary. 



CONCLUSIONS 



Residues of SDDT, PCB, dieldrin, and endrin, 

 although generally low, were found in all species 

 and all locations except Pascagoula, Miss., where 

 only DDE was quantifiable. The highest levels of 

 SDDT and PCB, and the only ones to reach 1 ppm, 

 were in one composite sample of king mackerel 

 from the Florida Keys, 0.996 ppm SDDT and 1.8 

 ppm PCB. The highest level of dieldrin, 0.026 ppm, 

 was in king mackerel from Aransas Pass, Tex., 

 and of endrin, also 0.026 ppm, in Spanish mack- 



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