Interdisciplinary assessment of the skate fishery in the Gulf of Alaska

Abstract

Skates are common bottom-dwelling fishes and valuable non-target species in Gulf of Alaska fisheries. Although there is little demand for skates in the United States, markets in Europe and Asia are fueling desires for additional fishing opportunities on skates in Alaska. Management agencies, however, have been hesitant to allow increased harvests due to the lack of information on the ecology and population dynamics of skates, and the bioeconomics of skate fisheries. Specifically focusing on the two most commonly landedskate species in the Gulf of Alaska (GOA), the big skate (Beringraja binoculata) and the longnose skate (Raja rhina), I conducted an interdisciplinary project to address these knowledge gaps. First, I advanced our understanding of the movement patterns and habitat use of skates by satellite tagging big skates in the GOA. The results show that big skates can, and likely frequently do, travel long distances, cross management boundaries within the GOA, and spend more time in deeper waters than previously thought. Second, I used the insights from the movement study to develop the first stock assessment models for skates in the GOA. This represents an important improvement in modeling, laying the groundwork for the North Pacific Fishery Management Council to move from Tier 5 (more data limited) to Tier 3 (less data limited) harvest control rules, which should lead to increased confidence with which the total allowable catch (TAC) for skates is set. Finally, I used the sustainable harvest estimates from the stock assessment models to develop a model that examined the impacts of management decisions on the profitability of skate fishing. My research provides essential information about these understudied fishes, helping to improve the sustainability and profitability of skate harvests. Incorporation of best available science regarding skate ecology, population dynamics, and bioeconomics into fishery management fosters more responsible development of skate fisheries, sustainable fishery revenues, and employment, and reduces the risk of overfishing, stock collapse, and prolonged fishery closures. It is my hope that fishery management agencies and the fishing industry make use of the new information and insights presented in this dissertation to work collaboratively towards the responsible development of skate fisheries.