Organochlorine residues in fish of Lake Texoma, October 1979.

Fillets from 99 fish, representing 11 species and three areas within Lake Texoma, were examined for residues of common organochlorines. Statistical analyses were conducted to determine the relationship of residues in fish fillets to trophic level and to geographical location of the sample. Most species contained PCBs at levels up to 100 ng/g and p,p'-DDE as high as 127 ng/g. p,p'-TDE and o,p'-DDT were not found in carnivores, but were present in herbivores and detritivores in amounts up to 36 ng p,p'-TDE/g and 17 ng o,p'-DDT/g. Heptachlor also was not found in carnivores, but was present as high as 37 ng/g in the other two classes. Chlordane ranged to 24 ng/g and was detected in all trophic levels. Dieldrin and p,p'-DDT were present in detritivores and carnivores up to 144 ng dieldrin/g and 410 ng p,p'-DDT/g. Neither substance was found in herbivores. Mirex, endrin, and heptachlor epoxide were present only at low levels. Statistically significant differences (P = 0.05) were found between trophic levels for seven of the eleven organochlorine compounds. No correlation (P = 0.05) was found between fillet concentrations of any parameter and geographical location of the sample.