Evaluating alternatives to reduce whale entanglements in commercial Dungeness Crab fishing gear

Abstract

Since 2014, the U.S. West Coast has experienced a sudden increase in reported whale entanglements with commercial fishing gear. The increase has been particularly acute in reported entanglements between Humpback whales (Megaptera novaeangliae) and commercial Dungeness crab gear. The current rate of entanglements is alarming and could trigger consequences for the responsible fisheries under the Marine Mammal Protection Act (MMPA) and Endangered Species Act (ESA); it seems likely that some change in the social-ecological status quo will be necessary to avoid significant harm to either the fishing community or the whale population. Here, we compare management alternatives to reduce entanglements, thereby reducing conflicts between whales and fishermen, scoring these alternatives according to estimated cost to fishermen, likely technical effectiveness, and anticipated reaction of fishermen in response to the change. We analyze these alternatives quantitatively using a Multi-Criterion Decision Analysis, and provide the analytical code as a decision-aid tool for managers and policy makers to use when contemplating changes to the West Coast commercial Dungeness fishery. We find a small number of high-ranking policy options; most prominently among these are Galvanic Timed Releases, which minimize the time that crab-pot lines are in the water and thus reduce the likelihood of entanglement. In addition, we include in an appendix a detailed list of regulations affecting the commercial Dungeness fishery, thereby providing both a substantive and procedural roadmap for reducing fishery-whale conflict.