Catalogs of Whale Tails Prove Revealing

March 7, 2001 -- Some people can never forget a face … and some scientists can never forget a tail.

Judy Allen, for example, has studied pages and pages of individual whale tail images for more than 20 years.

"Sometimes a tail is quite striking. It can be a black marking or a serrated edge," says Allen, who is associate director of Allied Whale, a marine mammal research group based at College of the Atlantic in Bar Harbor, Maine. "Look around your town and you can recognize people by their faces. It's a similar type of recognition."

Just as law enforcement agencies keep data bases of human fingerprints, scientists have maintained deep databases of whale tail images. And while police use fingerprints to track criminals, scientists have analyzed their databases to learn key elements of whale behavior. The whale catalogs may also eventually lead to one long-sought bit of knowledge: exactly how long particular whales can live.

20 Years of Whale Tails

Sean Todd, director of Allied Whale, says the program has amassed more than 10,000 images of about 6,000 individual whales in the North Atlantic since the late 1970s. Recent studies estimate a total of between 10,000 and 11,000 humpback whales now inhabit the ocean.

Less comprehensive are the catalogs of humpback whales in the Antarctic where long, severe winters and very rough waters can make tracking whales treacherous work. Researchers with Allied Whale have only recently begun gathering images of whale tails in Antarctic waters. In fact, Todd and Allen just returned from a cruise in the Antarctic sponsored by the Abercrombie and Kent Global Foundation where they collected 10 new images of humpback whale tails. The Antarctic whale tail catalog now lists about 1,000 individuals.

Todd explains it takes about a three-person crew to capture a whale tail image. One person steers the boat, another takes notes while a third snaps photographs.

"We follow the animal until it goes into a terminal dive," says Todd, explaining that a whale conducts a terminal dive after its lungs have filled with oxygen and it's ready to return to the deep. To make the deep dive, it raises its tail high in the air and plunges straight down.

The back side of the humpback whale's tail is revealed during the dive and so are its unique pigmentation, scars and edges.

The catalog of humpback tail images is also supplemented by volunteers around the world who send in their own images to add to the collection.

Aging Whales Revealed

So far the humpback whale catalog, which Todd says is probably the most comprehensive of its kind, has enabled researchers to track whales from youth to maturity and discover that humpbacks reach sexual maturity at 4 or 5 years of age and calve every two years. They've also learned populations of the animal appear to winter together in the Caribbean, but then split into about five separate feeding groups during summer months.

Todd adds that since a whaling moratorium has been in place in the North Atlantic for nearly 15 years, scientists also hope learn how long the animals can live. Current research suggests the massive mammals, which weigh up to 40 tons, can live up to 50 years. But it's possible they may live longer.

Photographic catalogs of another species of whale — the right whale — have revealed there is least one very old female now roaming in the North Atlantic.

Right whales, whose numbers have dipped dangerously low to about 300 in the North Atlantic, are identified by markings on their heads. A photograph culled from a New York City newspaper in 1935 showed the distinctive, scarred head of a female right whale. An image taken from a female right whale this year revealed the exact same markings.

"It has to be the same whale and we know she's at least 70 years old," says Amy Knowlton, a research scientist and right whale expert at New England Aquarium. "From the scars we were able to cinch that match."

Allen hopes someday whale catalogs may track hundreds of such elderly whales — and generations of their offspring.

"We now have a 20-year picture of humpback whales," she says. "But these are long-living animals and we just need to keep following them year after year to get the full picture."