Biologists, long stumped at figuring out how old whales are, lucked out when a 50-ton bowhead caught off Alaska came with a telltale clue: fragments of a harpoon lodged in a shoulder bone.
The weapon was used more than a century ago by whalers from New Bedford, enabling researchers to estimate that the whale was at least 115 years old and providing more evidence for their long-held belief that the bowhead whale is one of the longest living mammals on earth, surviving for up to 150 years.
"It's pretty rare that you get the chance to date the age of a whale," said John Bockstoce, the whaling historian at the New Bedford Whaling Museum who analyzed the fragments.
"We're all finding it very interesting," he said yesterday.
A biologist in Alaska spotted the pieces of the projectile as they were being pulled from the whale's blubber by Eskimos who had killed the animal last month.
He sent them to Bockstoce, who identified them as parts of an exploding lance made in New Bedford in the late 1800s, when the city was the world's whaling capital. Hunters would spear the animal with the weapon, which would detonate once inside.
Hunters used a similar modern device to kill the whale.
Anthropologists have analyzed hunting devices found in whales before, said Scott Kraus, vice president for research at the New England Aquarium in Boston.
It was often difficult, however, to determine when the weapon was fired.
"What you don't know is if some Yankee whaler had a harpoon made in 1830, traded it to an Inuit, and the Inuit or his offspring used it 40 years later," Kraus said.
But because the bomb lance was patented and stocks were used up quickly, Bockstoce and his colleagues identified a narrow window in which they believe the whale was shot, sometime between 1885 and 1895.
Biologists in Alaska will now try to verify the estimate by examining the whale's eye lens. Whales' eyes generally become cloudy as they age.
Found only in Arctic waters, the bowhead was in danger of being hunted to extinction at the turn of the century, but bounced back after demand for whalebone corsets plummeted, Bockstoce said. Today, only Alaska's indigenous tribes hunt bowheads.
After it is analyzed, the fragment will be displayed at the Inupiat Heritage Center in Barrow, Alaska.
Material from the Associated Press was used in this report.