Metro

There’s been a ‘concerning’ spike in whale deaths this month

Jennifer Goebel/NOAA
A dead minke whale washed up in Rye, N.H., on Monday.

At least four whales, including one that washed up in New Hampshire on Monday, have been reported dead around the Northeast since Sept. 9, adding to the unusual mortality event that researchers say is affecting several whale species.

“We’re definitely seeing more whale mortalities than we have in the past and it’s definitely concerning,” Jennifer Goebel, a spokeswoman for NOAA Fisheries, said.

A juvenile humpback whale was found washed up in Cohasset on Sept. 9. Officials from NOAA, the Environmental Protection Agency, and the Coast Guard decided to have it towed off shore on Friday, Goebel said.

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A “very significant” percentage of the whales that have died in the ongoing unusual mortality event are juveniles, Tony LaCasse, spokesman for the New England Aquarium, said.

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A dead minke whale was reported floating off the coast of Gloucester on Wednesday, and it was seen Saturday near Minots Ledge off the South Shore, likely due to strong currents and prevailing winds, LaCasse said.

Another dead minke whale was seen floating belly-up off the coast of Sea Bright, N.J., on Sunday. That whale was first seen off the coast of nearby Sandy Hook, N.J., on Saturday, Goebel, said.

A dead whale was also reported near Thacher Island in Cape Ann over the weekend, according to a Coast Guard spokesman, but it is unclear if that whale is different from the ones NOAA has confirmed.

On Monday morning, a dead minke whale washed up in Rye, N.H. The nearby Seacoast Science Center dispatched its Marine Mammal Rescue Team to evaluate the carcass and to try to find clues as to how it died, officials said.

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A team from the New England Aquarium will likely help out with the upcoming necropsy, LaCasse said.

The cause of the whales’ deaths is still unknown, and it could take weeks to find out what killed them. The minke whale that washed up in Rye may have been entangled in some gear, but researchers will not know whether that killed whale until they complete the evaluation, Goebel said.

The whale deaths, which occurred within days of each other, come in the midst of three ongoing unusual mortality events affecting minke whales, humpback whales, and North Atlantic right whales, which are all prevalent around the waters of the Northeast, Goebel said. These unusual mortality events have been affecting local whale populations for at least a year, and it’s worrying researchers.

There has been approximately one report of a dead whale off the coast of Massachusetts every week since early August, which is a greater rate of reports than usual, LaCasse said.

Since January 2017, states along the East Coast have reported more minke whale deaths than is normal. Massachusetts was the state with the most reported dead minke whales since then, having 13 of the 43 total dead minke whales that have been seen along the coast, according to data from NOAA Fisheries.

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How the unusual mortality events began and why they are persisting are still unknown, and it could take years for researchers to fully understand their causes and impact. But the fact that they have been officially declared means that researchers, like those from NOAA, can invest more resources into investigating them, Goebel said.

Andres Picon can be reached at andres.picon@globe.com. Follow him on Twitter @andpicon.