A jump in humpback whale deaths along the East Coast since the beginning of 2016 is stumping scientists and has prompted federal officials to pursue an investigation into the possible cause.

Since January 2016, there have been 41 humpback whale deaths reported along the East Coast between Maine and North Carolina, representatives with National Oceanic and Atmospheric Administration said Thursday during a press conference call. Most of those deaths have been reported between North Carolina and Massachusetts, they said.

“Any time we have a significant concentration of dead animals, it is concerning,” Deborah Fauquier, veterinary medical officer for the agency’s Fisheries Office of Protected Resources, said Thursday.

She added that, in the same time frame there have been confirmed deaths along the East Coast for 11 minke whales, three right whales, one sei whale and two finback whales — quantities that are not considered unusual for those species, all of which are protected by the Marine Mammal Protection Act. Prior to 2016, the average number of deaths for humpback whales along the East Coast was 14 per year.

The high number of humpback whale deaths has been categorized as an ‘unusual mortality event’ by NOAA’s fisheries service, leading the agency to open an official investigation into what is killing the whales.

The deaths come at a time when, overall, the numbers of humpback whales in the western North Atlantic ocean have been on the rise. Their estimated population along the East Coast has increased from fewer than 2,000 four decades ago to between 10,000 and 13,500 today, which last fall resulted in the population segment being de-listed from the federal Endangered Species Act.

Out of the 41 dead humpbacks, scientists have conducted necropsies on 20 of them. Out of those, 10 were determined to have been killed by ship strikes — an unusually high number, given that the average number of ship-related deaths each year for humpbacks on the East Coast is fewer than two.

In the other 10 that were examined, scientists found some evidence of low biotoxin exposures, which is considered typical. There was no clear indication about why these whales died, but investigators still are waiting to get test results from samples that were taken from the animals, which can take months or even years to complete, they said.

“That can change,” Greg Silber, standing coordinator for NOAA’s Office of Protected Resources, said of the lack of a common factor.

Silber added that investigators have not identified any other factors such as man-made underwater noises or changes in feeding habits brought on by warming ocean temperatures that may have played a role in the deaths.

Of the 41 dead humpback whales, only one was entangled in fishing gear, and that whale also had signs of having been struck by a ship, according to Mendy Garron, stranding coordinator for the agency’s Greater Atlantic Region office in Gloucester, Mass.

In addition to the 41 deaths reported in the U.S., there have been additional humpback whale deaths in Canada since early 2016, but the number of dead whales found in Canadian waters in that time was unavailable Thursday afternoon. One dead humpback whale washed up on the west coast of Nova Scotia in the Bay of Fundy last December in the same area where thousands of smaller sea creatures also perished for reasons that have not been determined.

As part of their investigation, NOAA officials have asked the public to report any dead or stranded whales they findby calling 866-755-6622.

Avatar photo

Bill Trotter

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....