Effects of Drag from Entanglement in Fishing Gear in Right Whales

Michael Moore, Woods Hole Oceanographic Instituton

Abstract

Entanglement in fishing gear is the leading detected and diagnosed cause of death in large
whales in the Northwest Atlantic. Entanglement may become protracted when individuals break free and carry a portion of the entangling gear, often for months to years. Emaciation is commonly documented in entanglement mortality. Drag induced energetic costs, coupled with potentially reduced mobility and foraging ability can significantly alter an individual’s energy balance. Sublethal entanglement trauma is close to ubiquitous in North Atlantic right whales. It therefore could be a major concern in terms of population level productivity. In this project we will: assess the energetic impact of specific North Atlantic right whale entanglements to determine the predictability of lethality or post-disentanglement survival; quantify the incremental energetic gains achieved by partial disentanglement; and compare measured vs. estimated drag from gear sets, to enable a predictive capacity to estimate drag for free-swimming entangled individuals at their time of detection. The above elements can come together throughout the project to help inform management in the context of potential impacts on large whales of different fisheries on the East Coast.