Reduction in swimming performance in juvenile rainbow trout (Oncorhynchus mykiss) following sublethal exposure to pyrethroid insecticides

While the lethal toxicity of pyrethroid insecticides to fish is well documented, their sublethal physio-behavioral effects remain poorly characterized. Known pyrethroid-associated changes to insect neuromuscular function may translate into similar effects in fish, thereby altering swimming ability and affecting foraging, predator avoidance, and migration. Three experiments were conducted using critical (U-crit) and burst (U-max) swimming speeds to assess the sublethal effects of the pyrethroids permethrin and deltamethrin in juvenile rainbow trout (Oncorhynchus mykiss). Fish were exposed to deltamethrin (100, 200, or 300 ng/L) or permethrin (1, 2, or 3 mu g/L) in water for 4 d, and assessed for swimming performance. Deltamethrin (200 and 300 ng/L) reduced U-crit, but not U-max, while both swim performance measurements were unaffected by permethrin. Subsequent experiments used only U-crit to assess deltamethrin exposure. In a time course experiment, deltamethrin (300 ng/L) reduced U-crit after 1 and 4 d of exposure, but after 7 d of exposure U-crit was fully recovered. Finally, deltamethrin (1, 2, or 3 mu g/L) reduced U-crit after I h bath exposures similar to recommended protocols for deltamethrin based sea-lice treatment in aquaculture. The real-world implications of the revealed pyrethroid-associated swimming ability reductions in salmon may be important in areas close to aquaculture facilities. (C) 2013 Published by Elsevier Inc.