Chlorinated Hydrocarbon Insecticide Residues in Winter Flounder, Pseudopleuronectes americanus, from the Weweantic River Estuary, Massachusetts

Residues of DDT, heptachlor, and dieldrin were found in tissues of winter flounder, Pseudopleuronectes americanus (Walbaum), from the Weweantic River estuary, Massachusetts during 1966–67. In nonmigratory juveniles, seasonal accumulation patterns were demonstrated for DDT, heptachlor, and two related breakdown products, DDE and heptachlor epoxide. Peak concentrations of the parent compounds were more closely associated with high runoff conditions than any specific application in the estuarine drainage. Dieldrin was present uniformly throughout the year.Migratory adult flounder, present only between October and May, contained heptachlor and heptachlor epoxide levels similar to juveniles, but significantly less DDE. Adult female flounder sequentially concentrated DDT, DDE, and heptachlor epoxide in their ripening ovaries as the spawning season approached