Estimating Drag Forces and Energetics of Free-Swimming Entangled Whales

Simon Thorrold, Julie van der Hoop, Patrick Miller, and Mark Grosenbaugh, Biology Department

Abstract

Large whales swimming entangled in fishing gear are often subject to emaciation by reduced mobility and foraging ability, and the increased energetic demand imposed by towing accessory gear. While chronic impacts of entanglement include systemic infection and debilitation due to severe tissue damage, many protracted entanglements become terminal due to starvation and emaciation due to the inability to cope with a negative energy budget. Disentanglement responses are often coordinated in order to remove entangling gear from an individual when an entanglement is first observed. Currently, it is unknown what types of behavioral or energetic effects this has for a free-swimming entangled animal. We propose to tag entangled North Atlantic right whales with non-invasive suction-cup biologging tags before, during, and after disentanglement to determine (1) the effect of entanglement on dive behaviors and their potential impact on foraging or swimming efficiency, (2) the additional drag forces and (3) energetic cost associated with entanglement. The proposed research will allow for predictions of the energetic consequences of different types of entanglements to this highly endangered species.