Swimming performance of rainbow trout following exposure and recovery from the pyrethroid S-deltamethrin

Oxygen consumption and swimming performance of rainbow trout exposed to sublethal concentrations (10-50 microliters/20 L) of pyrethroid (S-deltamethrin) pesticide was studied in a Brett-type respirometer during recovery. Results showed wide variations reflecting the varied responses of different individual fish to the test regime. In most cases values of oxygen consumption for the controls were higher at each swimming speed and this became significantly reduced following treatment with pesticide. Oxygen consumption soon after the treatment gave the highest values but these fish were unable to sustain swimming speeds as high as the controls or following recovery. The comparisons of swimming performance before and after treatments with deltamethrin have shown a significant effect on locomotory ability of rainbow trout which at the end of strong exposure (e.g. 50 min of 40 microliters/20 L) are almost incapable of swimming.