A dead juvenile finback whale was found floating in the ocean between the Vineyard and Noman’s Land last Friday.
David Damroth, a Chilmark resident, said he spotted the whale from a hill above Squibnocket Beach. He later took his boat out on the water and got a closer look at the animal, which was largely intact, he said. The only marks he saw were from scavenging seagulls.
The New England Aquarium was also alerted. Tony LaCasse, public relations director for the aquarium, said that though the most common human-related causes of death for whales in this area are vessel strikes or entanglement in marine gear, there were no obvious signs of either on the juvenile male.
It is hard to determine the cause of death for the whale, Mr. LaCasse said, but it likely had an underlying medical condition. He said this is especially common with younger whales, though this time of year most whale deaths are human-related.
Whale carcasses are classified using code levels one through four, one being freshly dead and four very decomposed. This whale was deemed a code three, Mr. LaCasse said, and the whale was quite bloated from gasses that have built up inside the body. It is hard to say how long the whale had been dead, but he estimated at least a few days.
Mr. LaCasse estimated that the whale is a yearling, likely born in the winter of 2012 or a little before. He said it might be about two years old.
The aquarium will let “nature take its course” for the whale and let it float. The Coast Guard usually keeps track of floating whale carcasses and provides the information to mariners so they are aware of the potential hazard, Mr. LaCasse said.
If it remains floating in the water, after two or three weeks the animal will start falling apart, he said. In some cases it will sink, especially if the body cavity is ruptured.
The head of the whale, which is the largest and heaviest part of the body, often comes off first.
Once the whale floats to deeper water, sharks might eat the carcass. Mr. Damroth said that on Friday, there were no sharks in the area.
In fact, Mr. LaCasse said, through most of the 20th century — prior to the rebound of the seal population — the primary source of food for white sharks in Massachusetts waters were dead floating whales.
In other areas, he said, the sharks prefer to eat a big sea lion or seal. But with the seal population depleted in New England, he said, the sharks would feed on the dead whales.
Further, he said, when a large whale dies and sinks into the ocean, it creates “an oasis of nutrients on the ocean bottom.” For years afterward, the carcass creates an area of high biological activity. Even when the whale becomes a skeleton, it is used as a homestead for some organisms.
Finback whales, sometimes called fin whales, are the second longest whales in the ocean, dwarfed only by blue whales, which are the longest animal on earth. Mr. LaCasse said finbacks are “the greyhounds of the sea” because of their relative speed. They can grow to be 80 feet long. At birth they are 21 feet long and weigh two tons.
The whales reach sexual maturity at age nine or 10, he said, and usually reach adult size a few years before that. They typically eat small schooling fish like herring or capelin, and also squid.
Finback whales are endangered but have a stable population, Mr. LaCasse said. Most recent estimates indicate there are between 2,700 and 6,000 in U.S. waters.