December 9, 2015 — Entanglement in fishing gear is the leading cause of death for North Atlantic right whales—one of the most endangered of all the large whale species. Their migratory routes take them through some of the busiest commercial fishing areas along the East Coast of the United States and into Canada.

Entangled whales can tow fishing gear for tens to hundreds of miles over months or even years, before either being freed, shedding the gear on their own, or succumbing to their injuries.

In a paper published online Dec. 9, 2015, in Marine Mammal Science, a research team led by the Woods Hole Oceanographic Institution (WHOI), has for the first time quantified the amount of drag on entangled whales that is created by towing fishing gear, such as rope, buoys, and lobster and crab traps. The study provides important data for teams evaluating the risks and benefits of whale disentanglements.

“We know that entanglement can change a whale’s diving and swimming behavior and depletes their energy,” said Julie van der Hoop, lead author of the paper and a PhD Candidate in the MIT-WHOI Joint Program in Oceanography, “but the big thing we have never really known is what it must be like for animals to tow the gear. Is it like wearing an empty backpack or is that backpack overloaded with heavy books? Does removing part of the gear improve chances of survival? These are some of the questions that we were looking to answer with this research.”

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