Drag from fishing gear entangling North Atlantic right whales

• Published in: Marine Mammal Science
• Main Authors: van der Hoop, Julie M., Corkeron, Peter, Kenney, John, Landry, Scott, Morin, David, Smith, Jamison, Moore, Michael J.
• Other Authors: Natural Sciences and Engineering Research Council of Canada
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Eubalaena glacialis; North Atlantic
• Online Access: http://dx.doi.org/10.1111/mms.12292; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmms.12292; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12292

Abstract Lethal and sublethal fishing gear entanglement is pervasive in North Atlantic right whales ( Eubalaena glacialis ). Entanglement can lead to direct injury and is likely to incur substantial energetic costs. This study (1) evaluates drag characteristics of entangled right whales, (2) contextualizes gear drag measurements for individual whales, and (3) quantifies the benefits of partial disentanglement. A load cell measured drag forces on 15 sets of fishing gear removed from entangled right whales, a towed satellite telemetry buoy, and 200 m of polypropylene line as it was shortened to 25 m, as they were towed behind a vessel at ~0.77, 1.3, and 2.1 m/s (~1.5, 2.5, and 4 knots) and ~0, 3, and 6 m depth. Mean drag ranges from 8.5 N to 315 N, and can be predicted from the dry weight or length of the gear. Combining gear drag measurements with theoretical estimates of drag on whales' bodies suggests that on average, entanglement increases drag and propulsive power by 1.47 fold. Reducing trailing line length by 75% can reduce parasitic gear drag by 85%, reinforcing current disentanglement response practices. These drag measurements can be incorporated into disentanglement response, serious injury determination, and evaluation of sublethal effects on population dynamics.