Three dead whales washed ashore between Plymouth and Provincetown in under a week

Three dead whales — two humpbacks and one minke — have washed ashore on the coastline between Plymouth and Wellfleet in just under a week, prompting independent investigations and misinformation about what has caused the deaths.

Researchers say they don’t know why three whales died in such a short time period, but the deaths are unrelated.

“Those red flags are going up to some degree to say ‘What is going on?’ because this is a change or diversion from previous years, but it may just be a continuation of the existing unusual mortality event, and that these whales are in Cape Cod Bay more now than in prior years,” said Sarah Sharp, a veterinarian who conducts post-mortem exams for the International Fund for Animal Welfare (IFAW).

There’s no indication offshore wind development played a role in any of these whales’ deaths, she added, and urged the public to be cautious of misinformation.

“It’s devastating to deal with these things, it’s devastating to try and understand why [whales] are dying, so that you can try and help them. But when you have people wanting to attribute them to other causes of death because it serves a political need for them, it’s really heartbreaking,” said Regina Asmutis-Silvia, executive director of Whale and Dolphin Conservation (WDC). “These animals aren’t even going to get the help that they need because there’s an agenda out there that doesn’t meet the actual data.”

More information sought on Plymouth humpback

Researchers from WDC, a South Shore-based group, are still waiting for the post-mortem results of a humpback that washed up in Plymouth early last week.

They found the young male on a beach off Center Hill Road with an entanglement around its flipper.

“We don't know if the entanglement is the cause of death,” said stranding specialist Caroline Genther. “We can't know that until we get a closer look and hopefully are able to do that necropsy.“

The WDC team was able to move the whale to the Bourne landfill for the necropsy (the animal version of an autopsy) several days after it washed up.

That whale was the fifth to be found on beaches between Plymouth and Weymouth in just six months; one of the whales was pregnant.

‘It's a pattern that we're seeing’

While the minke whale found in Wellfleet on Thursday likely died from infectious disease, Sharp said, the humpback found in Brewster on Saturday was likely killed in a head-on collision with a boat.

IFAW researchers conducted a necropsy on the two-year-old, 26,000-pound female humpback on Monday.

“It does look like there's potentially some evidence of of blunt trauma to her head,” Sharp said. “And so that certainly could have caused an acute death for this poor young female.”

Sharp said the whale, known to researchers as “Firebolt,” survived at least one other boat collision and an entanglement in her short life.

“It's a pattern that we're seeing in all of these whales that are that are unfortunately dying in our waters,” she said.

Humpbacks have been experiencing an elevated mortality period since 2016, with boat collisions and entanglements accounting for most deaths.