Management of low-productivity fisheries: Collapse and recovery of Alberta's walleye (Sander vitreus) fisheries

Collapses of low-productivity, northern fisheries following increases in fishing effort are axiomatic to fishermen, but quantitative evidence is rare because of the large temporal and spatial scales usually required to demonstrate such changes. In Alberta, an unusual combination of persistently high fishing effort, relative to low biological productivity, has resulted in documented declines and collapses of important recreational, commercial, and First Nations subsistence fisheries for walleye Sander vitreus (Mitchill). Minor changes to traditional sport fishing regulations (e.g., bag and size limits, and season restrictions) failed both to prevent recruitment overfishing and to allow the recovery of collapsed fisheries. I quantified three proximate, depensatory mechanisms for these failures: inverse relationship of illegal harvest to catch rate, perceived hyperstability in reported fishing quality, and the loss of cultivation effects by walleye on forage fishes. After extensive public consultation, major restrictions were implemented on the recreational harvest, which allowed the recovery of growth-overfished populations. Paradoxically, these recoveries demonstrated the inability of traditional regulations to sustain fisheries under conditions of high fishing effort and low biological productivity. Alberta's case history demonstrates the narrow range of conditions under which traditional regulations are effective in maintaining northern fisheries and illustrates the need for direct harvest controls. In order to overcome strong social constraints to management, stock assessment biologists must provide decision-makers with the full perspective of potential fishery status. This may be achieved by adopting a new model for managing low-productivity fisheries, incorporating both direct and indirect harvest controls.