A young North Atlantic right whale was found dead off the coast of Barnstable Thursday morning, a troubling sign for a species that is near extinction but still congregating in Cape Cod Bay in record numbers, specialists said.
The female was found midmorning Thursday by a federal research vessel, according to Charles “Stormy” Mayo, director of right whale habitat studies at the Center for Coastal Studies in Provincetown.
The Coast Guard towed the animal to Sesuit Harbor in Dennis, and veterinarians will perform a necropsy Friday.
The cause of death is not known, but Mayo said there were no external signs of a ship strike. It’s possible it was hit by a boat and died of internal injuries, he said.
Only three right whale calves have been identified this year, Mayo said, with a fourth possible calf spotted off Cape Cod Wednesday.
“Unfortunately, we gained one yesterday and we’ve lost one today,” he said.
An endangered species, North Atlantic right whales have long experienced a declining birth rate and population, Mayo said.
The population now numbers just above 500, but a “remarkable concentration” of 163 whales, or more than 25 percent of the species, was spotted in Cape Cod Bay Wednesday, Mayo said.
“She could have produced 20 calves in her lifetime, so not only did we lose a whale, but we lost a whale that is really central to the species,” said Mayo.
Aerial surveys conducted by the center show the whales have been making their way north after the end of their mating season near the Florida-Georgia line.
The average number of calves over the last 20 years has been 17 per year, according to Tony LaCasse, a spokesman for the New England Aquarium.
“The North Atlantic right whale is the most endangered large whale species in the Atlantic . . . and probably one of the two or three most endangered whales in the world,” LaCasse said. “[If] this is a right whale calf that has just done a thousand-mile swim . . . that’s probably a relatively healthy animal.”
Mayo said the whale found Thursday would be a “very big calf” if it is indeed one of the newborns. The animals are distinguishable by their external marks, and his team hasn’t been able to match the animal to the calfs previously identified.
A calf was found dead off the coast of Cape Cod last May with several gashes from a propeller, according to LaCasse.
The abundance of whales in Cape Cod Bay last week led officials from the National Oceanic and Atmospheric Administration to enact speed limits for boats within 12 nautical miles of Boston.