Stranded Humpbacks Part Of 'Unusual Mortality Event'

By: Alan Pollock

Topics: Marine Mammals

Experts examine a humpback whale on the shore of Monomoy Island last week. IFAW PHOTO

CHATHAM Two young humpback whales that died on Monomoy Island last week are being tracked as part of what researchers call an “unusual mortality event” that includes five dead humpbacks in Massachusetts and 46 around the region in the past two years.

On Monday, June 19, the International Fund for Animal Welfare (IFAW) was alerted to a dead humpback on the island, and notified the U.S. Fish and Wildlife Service, which confirmed the report. Poor weather kept the team from reaching the whale until Thursday, and because the animal was on the edge of the beach in heavy surf, investigators could not perform a full necropsy.

While they were at the scene of the first stranding, IFAW officials received a call from the Atlantic White Shark Conservancy, which was conducting research and observed a second humpback on the beach. The marine mammal team located the whale and found it to be alive but in very poor condition. After a thorough health assessment by a veterinarian, the team decided to euthanize the animal. A full necropsy showed no recent signs of entanglement, vessel strike or other major wounds, though the whale had a large amount of crassicauda, parasites that can cause kidney damage and death in young whales. The results of tissue and blood analysis are pending.

The National Oceanographic and Atmospheric Administration is tracking the deaths of 46 humpbacks between Maine and North Carolina since January 2016. Necropsies have been performed on about half of those animals, and 10 of the whales had evidence of blunt force trauma or propeller wounds that would indicate that the animal had been struck by a boat or ship prior to its death.