Fishing Gear Can be Fatal to Whales

In a new study conducted by WHOI scientists, a “patient monitoring” device was attached to a whale that was entangled in fishing line. As a result of being tangled in the line, the whale’s ability to eat and migrate was directly affected, resulting in a slow death for the animal.

For this research, scientists used a Dtag (a suction-cupped device about the size of a cellphone) and attached it to a two-year old female North Atlantic right whale named Eg 3911. The Dtag was developed by the Woods Hole Oceanographic Institution (WHOI) and recorded Eg 3911’s movements before, during, and after at-sea disentanglement operations.

Eg 3911 was found in 2010 in Florida where she was tangled up in fishing line that was wrapped around her mouth and pectoral fins, and trailed around 100 feet past her tail. Once the researchers removed the lines from her, she was able to swim much faster and could dive twice as deep.

Unfortunately, she was tangled up in line again, but the Dtag was able to track her movements. “Together, the effects of added buoyancy, added drag, and reduced swimming speed due to towing accessory gear pose many threats to entangled whales,” the scientists wrote in their study. Buoyant gear may overwhelm animals’ ability to descend to depths to forage on preferred prey. Increased drag can reduce swimming speeds, delaying whales’ timely arrival to feeding or breeding grounds. “Most significant, however, is the energy drain associated with added drag.”

On Feb. 1, 2011, Eg 3911 was found dead at sea. “She didn’t make it,” van der Hoop said. “We showed up on the beach that night. I remember walking out there and seeing this huge whale, or what I thought was huge. She was only 10 meters long. She was only two years old. And all these people who had been involved in her life at some point, were there to learn from her what entanglement had caused.”

A necropsy was performed on Eg 3911 after she was towed ashore. Chronic entanglement was shown to be the cause of death.