Analysis of North Atlantic Right Whale Swimming Behavior during Bottom Foraging Events to Assess Entanglement Risk

The western North Atlantic right whale, Eubalaena glacialis, is critically endangered throughout its range. With approximately 300 individuals remaining, this population suffers significant impacts from entanglement in commercial fishing gear that are impeding the species ability to recover from historic hunting pressures. The purpose of this study was to evaluate the circumstances surrounding serious entanglements. Data collected from foraging right whales tagged in 2001 and 2002 were analyzed to identify behavior(s) that may increase the risk of entanglement in certain types of gear at certain depths. Results suggest that foraging right whales display risky behaviors that may increase their chances of becoming entangled, including swimming at depths where floating loops of line from bottom-fixed gear extend into the water column, and increased rolling behavior through vertical line during the ascent and descent portions of the dive cycle. This work could contribute to current conservation efforts on behalf of the whale by informing the design of more 'whale-friendly' fishing gear, as well as help managers determine more effective mitigation strategies to reduce the risk that fishing gear poses to right whales.