Management procedures define the set of actions that will be used to guide effective fisheries management. Common procedures include collecting data, conducting a population assessment, and defining a set of harvest control rules to formulate a harvest policy. The objectives of my dissertation research were structured to address some of the key questions associated with each of these procedures in the management of Lake Erie walleye (Sander vitreus); thereby providing science-based support to some of the more critical decisions concerning rational walleye management. Walleye are intensely managed in Lake Erie because of the economic, social, and cultural value of the fishery to the North American Great Lakes region and because it is an ecologically important species (apex predator) in Lake Erie. I begin by introducing the walleye fishery, providing the essential context from within which it is currently managed (chapter 1), before explicitly evaluating each research objective. The first research objective (chapter 2) was to investigate if accommodation for spatial structure at scales relevant to walleye movement patterns, at the expense of model complexity, improved the annual population assessment procedure. There was strong statistical evidence that incorporating spatially referenced vulnerability and catchability parameters improved model fit, and the change altered estimates of stock size and fishing mortality. The second research objective (chapter 3) was to improve a data collection procedure - research survey indices of walleye abundance - by statistically accounting for factors inherent in survey data that confound the ability to detect true trends in population abundance. Models recognized several factors (e.g., net set type, secchi depth, sampling week, and the presence of hypoxia) affecting the direction and magnitude of predicted abundance trends, though a different combination of factors were identified for Canadian and United States surveys. The third objective (chapter 4) was to directly aid decision-makers by quantitatively comparing the performance of alterative walleye harvest policies under three different data collection and population assessment schemes while explicitly incorporating uncertainty in the management process (i.e., to conduct a management strategy evaluation). Because uncertainty leads to risk, quantitatively accounting for uncertainty gives managers a measure of how risky a particular management decision may be and provides a risk assessment framework in which to compare tradeoffs among alternative management procedures. Results indicate that harvest policy performance and the ensuing tradeoffs between conflicting objectives were conditional on the choice of a data collection and assessment scheme. For the explicit policies evaluated, annual age-structured procedures outperformed other procedural schemes (i.e., triennial age-structured and annual survey index) and provided the overall best balance between harvest and risk-related tradeoffs. However, the extra effort associated with implementing annual SCA management procedures only provided a modest improvement in policy performance over triennial SCA management procedures.
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