Do abiotic influences affect estimates of walleye populations in Lake Erie?

The estimate of the walleye population in Lake Erie is driven by catch-at-age harvest models. Additionally, randomly stratified fall gill net surveys are used to predict recruitment and serve as an independent (i.e. non-harvest) estimate of stock size. The gill net surveys span the west and central basins and include a broad range of habitats and depth strata. Our objectives are threefold. First, we will use logistic regression to model the probability of walleye occurrence and generalized linear models to predict walleye abundance based on abiotic parameters. Preliminary results suggest that walleye abundance is related to temperature, photoperiod, water clarity, and prey availability. We will then develop a spatial habitat suitability model for the Lake. Secondly, based on information derived from this model and the migratory nature of walleye, we will determine if we can improve our current sampling regimen. Thirdly, we will compare the catch-at-age estimate between the harvest model and the independent survey.