Survival from Sea Lamprey (Petromyzon marinus) Predation by Two Strains of Lake Trout (Salvelinus namaycush)
We tested the hypothesis that the better survival of the Seneca Lake strain of lake trout (Salvelinus namaycush) in Lake Ontario resulted from their greater resistance than other stocked strains to sea lamprey (Petromyzon marinus) predation. No significant difference was found in the survival of Marquette and Seneca Lake strains of Lake trout subjected to single sea lamprey attacks in the laboratory. Of 85 Marquette strain lake trout, 44% died as a direct result of sea lamprey predation, 20% died of undetermined causes, and 36% survived; for 90 lake trout of the Seneca Lake strain, the respective percentages were 39, 21, and 40. The location of sea lamprey attachment on the lake trout was not a factor in mortality, which was significantly higher at water temperatures of 15.6–17.8 °C than at 0.6–15.6 °C. Our study suggested that the seemingly greater survival rate of Seneca Lake fish in Lake Ontario probably resulted from differences in behavior or environmental preferences that decreased their exposure to sea lamprey attacks.