| Abstract: | The effects of permethrin on native and caged fish when aerially applied directly to forest streams at dosages between 8.8 and 70 g ha?1 were studied between 1976 and 1981. None of the applications caused mortality of caged or native fish in streams. Trout and salmon diets were altered by the treatments due to effects on fish food organisms. The duration of the effects varied from several months to over a year with increasing dosage. Reductions in salmonid growth rates and reductions in fish densities in treated areas, presumably due to emigration, were documented following severe impacts on aquatic invertebrates in salmon nursery streams. Growth rates and population densities both recovered within four months after treatment. |
