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 crashed, but there remains some uncertainty concerning the relative importance of sea lamprey predation and harvesting in destruction of the fisheries. Some investigators believe overharvest was important; others think that the sea lamprey alone was enough. Simple models of predation assume monophagous predators and do not predict extinction of prey, but Larkin's modification of the Lotka-Volterra model results in extinction under some circumstances. The dynamics of sea lamprey predation on lake trout were investigated using Larkin's model, and crude estimates of the model parameters indicate that extinction is a likely outcome with or without a fishery.