Thursday, November 05, 2009

Cautious optimism about right whales, during annual migration to Bay of Fundy

by Larry Lack, www.theworkingwaterfront.com

"The waters where the coasts of Maine and New Brunswick meet, where the St. Croix River widens into Passamaquoddy Bay and joins the Bay of Fundy, are key to the survival of hundreds, perhaps thousands, of North Atlantic whales.

These waters are the summer feeding grounds for several species of whales, including North Atlantic right whales, which are critically endangered. A small increase in right whale births last winter may justify some cautious optimism about whether right whales can escape extinction.

Right whales, along with finbacks, humpbacks and minkes from all over the northwest Atlantic depend on the these nutrient-rich waters to bulk up as they prepare for the long migration to southern United States waters and the Caribbean Sea.

During the summer and fall months in and near the Bay of Fundy, right whales gorge on up to a ton or more of plankton every day. This annual banquet provides them with a large part of their yearly nutritional needs and must sustain them beyond their migration into the winter months, which they spend in the relatively nutrient-poor warm southern waters where they were born and where some of them mate and give birth each year.

Late in August a large group of at least 40 North Atlantic right whales was observed for several days feeding near the small island group known as The Wolves just off the route of the ferry that links New Brunswick's Grand Manan Island with the mainland port of Black's Harbour (see "A close encounter with right whales").

Increased inshore sightings of right whales, which usually feed in deeper waters offshore caused a stir among whale researchers. Boatloads of whale watchers from Eastport and St. Andrews, N.B. were able to get a close look at these rare whales. There were also close encounters with humpbacks, which also spent more time inshore.

This summer and well into autumn The Wolves and another inshore feeding area, Head Harbour Passage, between Deer Island and Campobello Island in Canada, were also home to especially large numbers of the finback and minke whales, which are more commonly seen there.

Laurie Murison, who directs the Grand Manan Whale and Seabird Research Station, says whales near the mouth of Fundy change locations almost entirely in response to where they're finding herring and krill, and also copepods and other plankton, miniscule to microscopic creatures that congregate here in vast shoals.

In Fundy's waters, moved about by wind, tides, currents and temperature changes, the huge clouds of copepods that are the favorite food of right whales, can contain as many as 100,000 animals per square meter of seawater. The lower Bay of Fundy and the nearby Gulf of Maine are among the world's richest sources of these tiny crustaceans.

Because they swim slowly (their top speed is only about four miles an hour; some other kinds of whales can swim more than five times that fast), are rich in oil and whalebone and float when they are dead, right whales were considered the "right" whales to hunt and kill. When the League of Nations outlawed killing them in 1935 their population had been reduced to a few hundred; in 2001 only 300 of them were thought to exist. Right whale reproduction is a slow process. Female rights don't start producing young until they are at least 10 years old. After that they bear a single calf once every three years at most.

Whale experts have calculated that for the species to recover, 20 to 24 right whale calves must be born each year. In 1999 just five right calves were born, and in 2000 only a single calf was born that year. And these six calves were all born to females from the Gulf of St. Lawrence right whale population; none was from the herd that feeds in the Bay of Fundy.

In 2001, 32 right whale calves were born that year, well distributed between the two main populations. But births in subsequent years dropped close to or below the recovery level until this year, when Northern rights, which give birth off Florida and Georgia, produced 39 calves, the most since record keeping began in 1979. As a result, researchers have raised the estimate of their current population to 400.

But even if this rate of births continues, it would take Northern rights well over a century to rebuild their population to a safe survival level similar to the current population of Southern right whales, which is thought to number between 7,000 and 10,000.

Optimism about right whale recovery is tempered when conditions in the habitats of Northern and Southern rights are compared. Southern right whales, which feed in the Antarctic, live in waters that see very little ship traffic compared with the very busy (and highly polluted) shipping lanes along the U.S. east coast that Northern rights traverse twice annually. Because their slow speed makes it hard for them to avoid ships moving toward them, right whales are extremely vulnerable to ship strikes, which account for more right whale deaths than any other cause. Another major cause of Northern right whale deaths is fishing gear entanglements. An estimated 65 to 75 per cent of Northern right whales have entanglement scars."

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