DAO 96:175-185 (2011)  -  doi:10.3354/dao02385

Lethal entanglement in baleen whales

Rachel M. Cassoff1,7, Kathleen M. Moore2, William A. McLellan3, Susan G. Barco4, David S. Rotstein5, Michael J. Moore6,*

1University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania 19104, USA
2International Fund for Animal Welfare, Yarmouthport, Massachusetts 02675, USA
3Biology and Marine Biology, University of North Carolina, Wilmington, North Carolina 28403, USA
4Virginia Aquarium & Marine Science Center Stranding Response Program, Virginia Beach, Virginia 23451, USA
5Smithsonian Museum Support Center, Osteoprep Laboratory, 4210 Silver Hill Road, Suitland, Maryland 20746, USA
6Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
7Present address: Duke University Marine Laboratory, Beaufort, North Carolina 28516, USA
*Corresponding author. Email:

ABSTRACT: Understanding the scenarios whereby fishing gear entanglement of large whales induces mortality is important for the development of mitigation strategies. Here we present a series of 21 cases involving 4 species of baleen whales in the NW Atlantic, describing the available sighting history, necropsy observations, and subsequent data analyses that enabled the compilation of the manners in which entanglement can be lethal. The single acute cause of entanglement mortality identified was drowning from entanglement involving multiple body parts, with the animal’s inability to surface. More protracted causes of death included impaired foraging during entanglement, resulting in starvation after many months; systemic infection arising from open, unresolved entanglement wounds; and hemorrhage or debilitation due to severe gear-related damage to tissues. Serious gear-induced injury can include laceration of large vessels, occlusion of the nares, embedding of line in growing bone, and massive periosteal proliferation of new bone in an attempt to wall off constricting, encircling lines. These data show that baleen whale entanglement is not only a major issue for the conservation of some baleen whale populations, but is also a major concern for the welfare of each affected individual.

KEY WORDS: Baleen whales · Entanglement · Mortality · Cetacean · Strandings · Fishing gear · Necropsy · Northwestern Atlantic

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Cite this article as: Cassoff RM, Moore KM, McLellan WA, Barco SG, Rotstein DS, Moore MJ (2011) Lethal entanglement in baleen whales. Dis Aquat Org 96:175-185

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