Factors influencing dieldrin and DDT residues in carp from the Des Moines River, Iowa, 1977-80.

Concentrations of dieldrin and DDT in muscle tissue and fat of carp, Cyprinus carpio, from the Des Moines River, Iowa, differed significantly with month of collection, fish age, and sampling location. Pesticide levels expressed on the basis of wet weight of flesh often differed from those expressed on a fat basis. Fish from reservoirs tended to have higher levels of dieldrin, but not of DDT, than did fish from riverine locations.