The purpose of this research was first, to develop sea lamprey (Petromyzon marinus) wounding rate models for lake trout (Salvelinus namaycush) from each of the lakes within 1836 Treaty-ceded waters, and second, to explain how and why the length distributions of lake trout attacked by sea lamprey have differed spatially and over time. Despite substantial control efforts, the negative impacts of parasitic sea lamprey predation on native lake trout remain an important fisheries concern in the Great Lakes. In Chapter 1, I estimate wounding rates as a logistic function of lake trout length. A model comparison framework was used to develop unique wounding rate models for each of Lakes Huron, Michigan, and Superior. Models that assumed a negative binomial wound distribution and allowed for spatial and temporal effects in the shaping parameters were selected for each lake. Large spatial differences and temporal trends in sea lamprey size-selectivity were found. Chapter 2 attempts to explain spatial and temporal patterns in sea lamprey size-selectivity in a foraging theory context. Foraging theory predicts that in the scarcity of larger, more desirable prey, a predator will shift its feeding behavior by incorporating smaller, less desirable prey types. Wounding rate model parameter estimates were related to large lake trout abundance estimates to look for patterns consistent with foraging theory. Large lake trout abundance was a poor predictor of sea lamprey size-selectivity, but future research suggestions to examine the influence of alternative hosts and lake trout strain are described.
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