A North Atlantic right whale was found dead off the coast of Martha's Vineyard, in a blow to efforts to protect the critically endangered species.
The female whale was found on Joseph Sylvia State Beach, Massachusetts, on Sunday, according to the National Oceanic and Atmospheric Administration (NOAA).
Her tail was tangled up in thick rope, some of which was found to be deeply embedded in its skin.
The cause of death has not yet been found. Law enforcement officials are examining the rope, and authorized officials are planning to carry out an autopsy, NOAA said.
"While we don't know the cause of death yet, we know that entanglements can lead to long-term suffering and death," said Sarah Sharp, an animal rescue veterinarian with the International Fund for Animal Welfare.
The individual is thought to have been a juvenile because of its size.
This loss is concerning for the endangered population, Gib Brogan, a campaign director at Oceana, an international conservation group, told The New York Times.
"It's devastating to hear about another loss to North Atlantic right whales," he said.
"This death is even more troubling when it is a female calf that could have gone on to have many calves of her own for decades to come," he said.
While beachings are not uncommon, the death of a North Atlantic right whale prompts alarm bells.
North Atlantic right whales are endangered animals, which means they are at risk of extinction. They were heavily over hunted by whalers in the 1800s, and have struggled to recover.
The population, which has been on the endangered list since 1970, now only has around 360 individuals. Of those, fewer than 70 are females of reproductive age.
It is the latest in a string of deaths, sicknesses, and injuries affecting the whales off the coast of Canada and the United States.
NOAA declared an Unusual Mortality Event (UME) for the area in 2017. The primary threats to the species at the moment are " entanglement in fishing gear and vessel strikes," NOAA said, warning that about a third of deaths likely go unreported.
The UME now affects more than 20 percent of the population, "which is a significant impact on an endangered species where deaths are outpacing births."
This individual was the 37th documented mortality in this UME.
This article was originally published by Business Insider.
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