Bioenergetics of acclimation to permethrin (NRDC-143) by rainbow trout

Metabolic rates associated with sustained, prolonged and critical swimming speeds were examined in 10 g trout exposed to 5% 96 hr LC50 (0.75 microgram X l-1) and 10% 96 hr LC50 (1.50 micrograms X l-1) at 12 degrees C. Permethrin did not influence the metabolic cost for swimming at sustained and prolonged speeds. Basal metabolic rate increased on initial exposure to permethrin reaching maximum values after 7 days and declined to the control level after 13 days in 5% and after 32 days in 10% 96 hr LC50. Critical swimming speeds were adversely affected in a manner reflective of the effects of permethrin on basal metabolic rate. Elevation in basal metabolic rate in fish exposed to permethrin was a result of increased energy requirements due to physiological stress, detoxication and tissue repair.