Marked fingerlings of kokaneeOncorhynchus nerkathat were sterilized by treatment with 17#x221D;-methyltestosterone and released into an oligo#x2013;mesotrophic coastal montane lake (Salsbury Lake, British Columbia) showed greater longevity than untreated control groups. Some hormone-treated kokanees survived to age 7, 2 years beyond the apparent maximum lifespan of untreated fish. The proportion of hormone-treated fish among recovered fish that were older than age 3 was significantly greater than the proportion ofhormone-treated fish stocked, but this difference lessened with increasing hormone dosage, Despite increased longevity, the ultimate size of hormone-treated kokanees did not increase beyond that of untreated fish in this lake.
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