Accumulation of DDT by channel catfish (Ictalurus punctatus) held in cages in the Huntsville Spring Branch/Indian Creek complex

Catfish fingerllngs (Ictalurus punctatus) were used to determine if direct contact with residues of DDTR (DDT and its metabolites) in the sediments of Huntsville Spring Branch/Indian Creek in Alabama were responsible for DDTR concentrations in the fillets. Fish were stocked in cages where sediment levels of DDTR averaged 404, 178, and 36 ppm. Analyses indicated no significant differences in DDTR concentrations in fish fillets between contact and no-contact conditions. Significant differences were found in averaged fillet concentrations of DDTR among all sites. Concentrations of dissolved DDT in water (for filtered samples) were approximately 1.0 ppb for all sites. The diet of the fish contained 67% invertebrates (mainly Chironomidae) with high DDTR residues and significant differences were found between Sites A and C, and B and C. Since diet was a possible source of DDTR contamination and dissolved DDTR concentrations in the water did not vary among Sites A, B, and C, it is hypothesized that diet was the more significant factor in the mean concentrations of DDTR found in the fish fillets from these sites. More definitive studies are needed for confirmation.