Lake trout Salvelinus namaycush of the 1979–1990 year-classes (Lake Superior strain) were marked and stocked as fingerlings or yearlings in U.S. waters of Lake Ontario and recaptured during annual surveys with trawls and gill nets. Catches (as proportions of fish stocked) of age-2 fish by trawls and age-3 fish by gill nets were used as indices of survival. Mean survival indices of stocked fish declined over 50% from the 1980 to the 1990 year-class for fish stocked as yearlings and declined more than 90% for those stocked as fingerlings. Survival indices for fish stocked as yearlings were negatively and significantly correlated with abundance indices of large (≥550 mm total length) lake trout caught in gill nets in the year of stocking. This relation was not significant for fish stocked as fingerlings. Mean weight at stocking more than doubled for yearlings and increased by about one-third for fingerlings during this study. The increase in size at stocking may have offset what would otherwise have been a more drastic increase in mortality due to predation.
