Organochlorine insecticides in rainbow trout from three North Island lakes

Abstract

From 12 rainbow trout (Salmo gairdneri Richardson) taken from each of three lakes (Rerewhakaaitu, Opouri and Okataina) in the Rotorua district, N.Z., samples of liver, skeletal muscle and, from mature fish, the gonads were examined for organochlorine insecticides. Lindane, heptachlor and heptachlor epoxide were not detected in any of the samples. Traces of dieldrin were detected only in trout taken from Rerewhakaaitu Lake. In all fish examined, pp'-HDT, pp'JDOD and pp'-DDE were detected in all three tissues. The highest concentrations were found in some of the ovaries of fish from Rerewhakaaitu Lake, the catchment area of which had been extensively topdressed with DDT. Although most of the catchment area of Lake Okataina had never been topdressed with DDT, fish from this lake contained small amounts of DDT and its metabolites.

DDT in some New Zealand marine and freshwater fauna

“…Solly and Shanks (1969) found total DDT residues of 0.45-0.92 ppm in the edible flesh of 1-5 year old rainbow trout (Salmo gairdneri) taken in 1964 from three North Island lakes; no lindane, heptachlor or its epoxide, and traces only of dieldrin ( <0.05 ppm) were found. A further survey of residues in rainbow trout taken from five lakes in 1966 showed that immature, male, and female fish all carried residues of total DDT in their flesh in the range of 0.02-1.12ppm (Hopkins, Solly, and Ritchie 1969).…”