Large Whale Entanglements

Large Whale Entanglements

Entanglement of large baleen whales, including the right (Eubalaena glacialis), fin (Balaenoptera physalus), sei (Balaenoptera borealis), Bryde’s (Balaenoptera brydei), minke (Balaenoptera acutorostrata), and humpback (Megaptera novaeangliae) in fixed fishing gear (e.g. pot and gillnet) is a frequent occurrence along the east coast of the United States and Canada.

For right and humpback whales, which have detailed photo-identification histories, the records indicate that 78% of the right whale and 66% of the humpback population have evidence of at least one entanglement interaction, with many animals experiencing multiple entanglement events. Entanglement also appears to affect calves and juveniles more frequently than adults, although we are not sure why.
“Although most of these animals are able to free themselves from the entangling gear, serious injuries and deaths caused by entanglement occur in numbers that exceed what is sustainable to their populations.

Dynamics of Large Whale Entanglements in Fixed Fishing Gear

Mitigating bycatch in large whales differs from approaches with other animals because scientists cannot evaluate potential new gear modifications through at-sea trials. Typically, in these trials, catch rates of non-target species are compared between existing fishing techniques and new fishing devices or methods (e.g. comparing harbor porpoise bycatch in gillnets with and without pingers). In the case of the North Atlantic right whale, the species is so endangered, and the entangling events are so rarely observed, that it is not possible to measure the efficacy of new fishing gear using comparative trials.

Instead, scientists, fisheries engineers, and fishermen must link the biology and behavior of whales with the characteristics of a fishery, and infer entanglement likelihood using less tangible methods, such as estimating the level of overlap between whales and fishing gear, monitoring entanglement interaction levels over time, and making educated assumptions about how whales may respond when they first interact with fishing gear. The Consortium is working to 1) identify the characteristics of fishing gear that cause severe and fatal entanglement risk to whales and 2) provide a stronger scientific basis for evaluating the impact of existing, proposed, and future potential fishing methods to whales.”

Large Whale Entanglements

For More Information: The Consortium for Wildlife Bycatch Reduction