SWIMMING PERFORMANCE OF RAINBOW-TROUT FOLLOWING EXPOSURE AND RECOVERYFROM THE PYRETHROID S-DELTAMETHRIN

Oxygen consumption and swimming performance of rainbow trout exposed t o sublethal concentrations (10-50 mu 1/20 L) of pyrethroid (S-deltamet hrin) pesticide was studied in a Brett-type respirometer during recove ry. Results showed wide variations reflecting the varied responses of different individual fish to the test regime. In nest cases values of oxygen consumption for the controls were higher at each swimming speed and this became significantly reduced following treatment with pestic ide. Oxygen consumption soon after the treatment gave the highest valu es but these fish were unable to sustain swimming speeds as high as th e controls or following recovery. The comparisons of swimming performa nce before and after treatments with deltamethrin have shown a signifi cant effect an locomotory ability of rainbow trout which at the end of strong exposure (e.g. 50 min of 40 mu 1/20 L) are almost incapable of swimming.