Friday, February 13, 2009

Why are whales "missing"?

It would be an ideal world if we knew where each right whale was located everyday, however, the reality is that most whales are not seen and it takes a tremendous effort from a few groups that spend hours on the water or in the air trying to find and identify individual right whales. In the winter most effort is concentrated in the calving area from the Carolinas south to Florida, although some work is done in the Gulf of Maine through aerial surveys and limited boat surveys. Winter conditions can be daunting in the Gulf of Maine with strong winds and cold temperatures. Wind is also a problem in the calving area during the winter and can limit the number of aerial surveys. In late winter, right whales are seen off Cape Cod and aerial and boat surveys are conducted. Right whales may remain in this area into July. Anyone without a permit, whale watchers, pleasure crafts, etc., are not allowed within 500 yards of right whales from Maine to Florida so much of the information about right whales along the eastern coast of the U.S. comes from dedicated research teams.

From July through to October, research boat surveys and whale watchers contribute photographs to the right whale catalogue in Canadian waters, primarily in the Bay of Fundy off Grand Manan Island and occasionally off the Scotia Shelf (off Nova Scotia) and in the Gulf of St. Lawrence.

This leaves many places and many times where and when right whales could be but would go undetected. In fact, underwater sonobuoys (underwater microphones) can pick up the presence of right whales calling when people looking for right whales do not find them. This, of course, can be because of the amount of time right whales spend submerged when diving, weather conditions and the fact that visual surveys are limited to daylight hours.

Therefore, some of our symbolically adoptable whales may go several years without being seen. One of the longer gaps is with Catspaw, who went unphotographed for 12 years, seen in 1988 and not again until 2000. Kleenex was not seen between 2004 and 2009, Slash has not been seen since 2006.

And then we have sightings that are unusual. On April 29, 2005, Calvin and her first calf Hobbes, swam through the Cape Cod Canal from Buzzards Bay as she brought her calf up the coast from North Carolina. This short cut was built for shipping but has become a short cut for some whales as well. Only eight right whales, according to Philip Hamilton of the New England Aquarium, have been recorded using the Canal, the first in 1957 and the latest December 5, 2008, when the canal was closed to shipping until the right whale was clear of the canal.

When trying to follow generations of right whale families , it is easier to keep track of subsequent generations of females and their calves, than the progeny of male calves. The latter can only be done through genetics. Small skin samples are obtained with a biopsy dart and are analyzed at Trent University in Peterborough, ON.

It is sometimes further complicated by whether or not calves are adequately photo-documented in their first year when they are with their mothers. Slash and her calves have been a challenge to document because she is very leery of vessels and actively avoids them. This is understandable considering her history. At some point she was run over and the vessel's propellers cut through her tail, leaving it badly scarred and missing part of the flukes. Often it is known that Slash is in an area because her flukes are seen as she is diving. They have a unique shape and the long white scar stands out but getting close to her is usually not possible. Many of her calves are also males.

We will have a busy summer in the Bay of Fundy as the calf count as of February 10 stood at 31, tying the number born in 2001. Since 1980, that was the largest number of calves known to be born. It is suspected that this year will top that number since there are a few more weeks left in the calving season.

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