RESPONSE OF A BROOK TROUT (SALVELINUS-FONTINALIS) POPULATION TO A REDUCTION IN STREAM BENTHOS FOLLOWING AN INSECTICIDE TREATMENT

Treatment with permethrin resulted in massive invertebrate drift and significant reductions of benthos, but did not produce trout mortality or evidence of unusual behaviour. Growth rates of 0+ and 1+ age-classes were significantly lower following the insecticide application than those of trout from the same age-classes of pretreatment years but unusually high summer temperatures were at least partially, if not entirely, responsible for this. Growth rates returned to or exceeded pretreatment levels by the overwinter period of the treatment year. -from Author