LARKIN PREDATION MODEL OF LAKE TROUT (SALVELINUS-NAMAYCUSH) EXTINCTION WITH HARVESTING AND SEA LAMPREY (PETROMYZON-MARINUS) PREDATION - A QUALITATIVE-ANALYSIS

After invasion of the Great Lakes by the parasitic marine sea lamprey (Petromyzon marinus), lake trout (Salvelinus namaycush) populations cr ashed, but there remains some uncertainty concerning the relative impo rtance of sea lamprey predation and harvesting in destruction of the f isheries. Some investigators believe overharvest was important; others think that the sea lamprey alone was enough. Simple models of predati on assume monophagous predators and do not predict extinction of prey, but Larkin's modification of the Lotka-Volterra model results in exti nction under some circumstances. The dynamics of sea lamprey predation on lake trout were investigated using Larkin's model, and crude estim ates of the model parameters indicate that extinction is a likely outc ome with or without a fishery.