Cape Cod sees rare large gathering of right whales

Jason Szep, Reuters 27 Mar 09;

BOSTON (Reuters) - Nearly a quarter of the world's population of North Atlantic right whales, one of the most endangered species on earth, have gathered off Cape Cod in Massachusetts in a rare feeding frenzy, scientists say.

The nearly 80 right whales are the largest number seen in Cape Cod Bay for this time of year, said scientists who attributed the spectacle to an unusually large presence of zooplankton -- a marine species that is favorite whale food.

The number is about six times greater than last year and represents about 24 percent of the estimated 325 right whales left in the world, said officials at the Provincetown Center for Coastal Studies, which is conducting aerial surveys of the whales, and the National Marine Fisheries Science Center.

In March, right whales typically feed on a winter type of zooplankton that forms in waters as far north as Canada and floats with the currents into Cape Cod. This year, the tiny zooplankton species are especially rich.

"It's a pretty special sight in a tiny embankment so close to land," said Dr. Charles Mayo, a senior scientist at the center in Provincetown on the tip of Cape Cod.

The sight of the whales thrashing off the sandy beaches of Provincetown follows an increase in right whale calf births in waters from coastal South Carolina to Florida, said Dr. Richard Merrick, an oceanographer at the National Oceanic and Atmospheric Administration's fisheries service.

That has swollen the right whale population by a rate of 1.8 percent a year over the past decade, added Merrick, who works at NOAA's National Marine Fisheries Science Center in Woods Hole on Cape Cod.

It is unclear how many North Atlantic right whales are dying each year. They roam a huge expanse from the Gulf of Mexico to Norway, and it's next to impossible to find and track all the carcasses as they die, said Merrick.

Right whales got their name from 18th- and 19th-century whale hunters who considered them the "right" ones to kill because they are rich in oil and baleen, move slowly, stay close to shore and float when they die.

Up to 59 feet long and weighing up to 100 tons (91 tons), they have been protected since a 1937 worldwide ban on hunting right whales. But ship strikes and fishing gear entanglements have ravaged the species in recent decades.

For the past two years, unusually large numbers have gathered in Cape Cod Bay, where they typically feed from January to mid-May. There were sightings of 148 last year and 161 in 2007 -- twice the yearly average from 1998 to 2006.

"I'd expect that we'll beat both those years," said Mayo.

Last April, about 70 to 100 right whales gathered in Cape waters but that was later in the season to feed on a spring variety of zooplankton known as Calanus finmarchicus.

It's far rarer, Mayo said, to have such a large number feeding on the winter variety, known as pseudo Calanus.

"We're in a pivotal time in this season," said Mayo. "The concentration of plankton in the upper levels of the water has now begun to drop from its highs in February and early March. That is normal. And we're anticipating the influx of Calanus, a very rich plankton source.

"If that happens, you can imagine what that means in terms of numbers of whales," he added.