After an endangered North Atlantic Right whale washed up dead on the shores off Chatham last week, researchers have been working to determine its cause of death. The whale is the second dead right whale recorded this year.
The young right whale most likely became entangled in fishing gear and drowned about a week and a half ago, before coming to rest on Monomoy Island. On a warm day this week, close to high tide, a small team of researchers headed out to conduct a necropsy, or an animal autopsy. Brian Sharp of the International Fund for Animal Welfare’s marine mammal rescue team steered a small motor boat with two other team members on board.
"So right now we’re heading out of Stage Harbor in Chatham, we’re going out to re-examine a dead right whale that washed ashore Thursday of last week," Sharp said. "It was first spotted Monday of last week east of Martha’s Vineyard."
This is the second necropsy the team performed, after a larger group examined the body a few days before. As dunes and beach houses went by, Sharp directed the boat toward where the whale’s carcass was last seen. This particular death is of a male right whale, about 30 feet long. The team worried that because of how small it appeared, it could have been a juvenile or calf, no older than two years.
When the animal was first found, its tail fin, or fluke, was missing, which made getting an accurate length difficult. As Sharp drove up to the shore of the island, he hoped the whale hadn’t been taken back out to sea by the tide. The team was looking to collect some of the end vertebrae of the whale to give them a better sense of its original length, and therefore its age.
The boat docked as close to shore as it could, and the team hiked the rest of the way through shallow water. As we approached the whale, a heavy, sour smelled filled the air, though no one on the team seemed to be put off.
"So this is what’s left of the whale," Sharp said. "You can see we opened the animal up [in the earlier necropsy]. It was presented ventrally, stomach up, so what we did was made incisions down the center line, and cut back all the blubber and muscle."
They inspected the whale’s head as well, part of which was also missing, and Sarah Sharp, the team veterinarian and the wife of Brian Sharp, cut a sample from the whale's lower jaw.
"Basically, she’s doing a cut down," Brian Sharp explained. "She’s cutting through the soft tissue, so we can look at the portions that are remaining of the head."
Sharp used a long knife that doesn’t look too different from a kitchen knife. The skin was tough and yellowed.
"It’s really leathery and dried from the sun which makes cutting through a little more challenging," she said.
She also noted linear markings and depressions on its right fin that indicated it most likely became entangled in fishing gear, was unable to come up for air, and drowned.
"So we know it’s a young male right whale, his blubber was fairly thin, poor body condition," she said. It was also noted however that because of how thin the animal was, its internal organs were well-preserved, making it ideal to take samples from. The team takes back a portion of the whale's spine, some of its stomach contents, and a slice of its liver.
In 2017, 17 right whale deaths were recorded, and just five calf births. This year, there were no births. The results of today’s examination suggested that this particular whale was indeed, one of the five calves born last year.
"It’s heavy right now. Each whale is just emotionally heavy," Sharp said. "A young animal, hasn’t reached maturity, not contributing to that population at all, is really upsetting."
There are only about 400 North Atlantic right whales left in the wild today, and if yearly death tolls continue, the population will be on track to be extinct within the next twenty years. Sharp hoped that the team’s work and data from this necropsy can give some clues as to how researchers can better help conservation efforts.
"With every dead right whale, it’s basically our responsibility to try to figure out what happened to these animals and understand how we can better protect them," she said.