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  BBC 10 Sep 07
Whale 'success story' questioned

By Richard Black

Yahoo News 11 Sep 07
Gray whale numbers remain greatly reduced: study
By Will Dunham

Yahoo News 10 Sep 07
Gray whale recovery limited by Pacific ecosystem damage: study

Global warming and changes to the Pacific ecosystem could be limiting the recovery of the Pacific gray whale and suggest permanent damage done by overfishing, scientists said in a new study Monday.

Researchers from Stanford University and the University of Washington found evidence to show that the gray whales (Eschrichtius robustus), long believed a conservation success story with a fully recovered population after decades of over-fishing, are probably only one-quarter of original pre-whaling numbers.

Studying the gray whale genome, they discovered a much larger genetic variation than expected, allowing them to estimate that the whale's population in the Pacific was originally around 96,000, more than four times the current estimate of 22,000, they said.

That could reflect more fundamental damage done to the Pacific ecosystem when the gray whale was hunted to near-extinction, the researchers suggested in a report published Monday in the Proceedings of the National Academy of Sciences.

The scientists focused on the genetic mutation rate across ten sections of the gray whale genome to calculate backwards using computer-based genetic simulations to reach a range of 76,000 to 118,000 animals, or an average of 96,000, that they believe foraged the Pacific before the onset of mass whaling in the mid-19th century.

"Our survey uncovers too much variation for a population of 22,000. The overabundance of genetic variation suggests a much larger population in past centuries," said Stanford marine sciences professor Steve Palumbi.

What the estimate tells scientists is that, despite the success of a whaling ban in helping the gray whale population recover, other factors are limiting its growth.

One key factor, a summary of the research says, could be that climate change is limiting the food available to the whales in their key Bering Sea feeding grounds. That issue was raised in the past year with scientists reporting they had observed a significant number of excessively thin and starving whales.

But the study also suggests that the near-extinction of gray whales had a more complex effect on Pacific ecology, disrupting the food chain to the extent that it caps the ability of the whale population to further grow.

Elizabeth Alter, lead author of the new study, points out that the gray whale uniquely plows through the sea floor as it feeds, digging troughs to stir up food. That suspends huge amounts of sediment in the water that would have benefited other key species.

"A population of 96,000 gray whales would have re-suspended 12 times more sediment each year than the biggest river in the Arctic, the Yukon, and would have played a critical role in the ecology of the Bering Sea," Alter said.

She added that this could also have hurt seabird populations.

"The feeding plumes of gray whales are foraging grounds for Arctic seabirds. 96,000 gray whales would have helped feed over a million seabirds a year."

"These genetic results suggest gray whales have not fully recovered from whaling," Palumbi said. "They might be telling us that whales now face a new threat -- from changes to the oceans that are limiting their recovery."

BBC 10 Sep 07
Whale 'success story' questioned

By Richard Black Environment correspondent, BBC News website

A whale conservation success story, the recovery of the eastern Pacific gray whale, may not be quite what it seems.

Since the end of commercial whaling, numbers rose to about 20,000, thought to be the level they had been at before hunting began. But a new study using genetic methods, reported in the journal PNAS, suggests pre-hunting numbers were much higher.

The scientists say climate change may be altering the whales' supply of food significantly.

Earlier this year, researchers noted signs that grays were showing distinct signs of malnutrition when they arrived at their winter breeding grounds along Mexico's Baja peninsula.

They raised the idea that this might be connected with climate change. But the prevalent theory was that numbers had risen beyond the maximum level which the ecosystem could support.

The new research challenges that idea. "I think that when we see large-scale issues in the population, such as starving or malnourished whales, we should be looking to long-term climatic changes in their feeding grounds," said Liz Alter from Stanford University, US.

Stock take

A few hundred years ago, three separate populations of gray (or grey) whales lived in the oceans. The Atlantic stock is thought to have perished in the first frenzies of commercial hunting. Later, the eastern and western Pacific populations almost followed suit. The western stock, which lives along the eastern coast of Russia, is close to extinction once more, with development for oil and gas fields the prime cause. Numbers may be as low as 120.

But the eastern Pacific gray has supposedly seen rude health. It was taken off the US endangered species list in 1994, with numbers each year hovering about 20-25,000, which historical records from the whaling industry and computer models of population indicated was around the historical level.

The new genetic analysis, which Liz Alter's group has published in Proceedings of the National Academy of Sciences (PNAS), challenges this view. By looking at variation in the animals' DNA, the team concludes there were once 76,000-118,000 grays in the Pacific.

Even if those numbers were split between the eastern and western stocks, this indicates that the population of the eastern gray today is well below the historical level.

The researchers themselves acknowledge that further analysis should be done to confirm their findings. In particular, they would like to have samples from the critically endangered western stock, but given its parlous health, this would clearly be a sensitive issue.

Confirmation could have implications for traditional, or subsistence, whaling. Aboriginal groups in Chukotka in the Russian northeast are permitted to hunt 124 eastern grays each year to provide meat for their communities.

The Makah tribe of Washington State near Seattle is allowed a further five. Its hunting is currently suspended pending a domestic US legal settlement, though one gray was killed just this weekend, apparently without permission of tribal elders.

If historical numbers were much higher, that would imply the grays are not as robust as believed, which could lower these hunting quotas still further.

Yahoo News 11 Sep 07
Gray whale numbers remain greatly reduced: study
By Will Dunham

The Pacific gray whale population, thought by some experts to have rebounded fully from the ravages of whaling, actually is back to a mere fraction of historic levels, scientists said on Monday.

Knowing that an examination of genetic variation within a species can help gauge past population numbers, the scientists used a U.S. government tissue collection to analyze DNA samples from 42 gray whales.

The genetic variation seen among these whales indicated a past population far bigger than the current 22,000, researchers at Stanford University and the University of Washington wrote in the Proceedings of the National Academy of Sciences.

They determined that before large-scale hunting of this species began in the 19th century, there were about 96,000 gray whales in the Pacific Ocean -- with as many as many as 118,000 and as few as 76,000. That would mean the current count is 19 percent to 29 percent of the pre-hunting population.

The gray whale is a large baleen whale -- a "filter feeder" that feasts on large amounts of small sea creatures -- that first swam the world's oceans perhaps 20 million years ago.

"The gray whale population is one of the few baleen whale populations thought to have recovered completely from whaling. In other words, it was thought that there are as many gray whales now as there ever were," Stanford marine biologist Liz Alter, one of the researchers, said in a telephone interview.

"But when we surveyed genetic diversity we found a much higher level of diversity than we would have expected given the size today, indicating that there once were many more gray whales in the Pacific Ocean than there are now," Alter added.


This marine giant was hunted to the brink of extinction, with the population bottoming out at perhaps a few thousand by the end of the 19th century and through the 1920s, the researchers said.

The gray whale disappeared from the Atlantic Ocean centuries ago, with some experts blaming whaling. The gray whale migrates along North America's Pacific Coast between arctic seas and the lagoons off of Mexico's Baja California.

It was given its name due to the gray patches and white mottling on its dark skin. They are about 46 feet long and weigh up to 40 tonnes. Gray whales feed off the sea bottom, scooping up mud and eating small crustaceans and tube worms found in sediments.

The gray whale was given partial protection in 1937 and full protection in 1947 by the International Whaling Commission, the American Cetacean Society said.

Once hunted in large numbers, gray whales now attract whale watchers along North America's Pacific coast.

The whales are still occasionally hunted. Five Washington state American Indian hunters may face prosecution from their Makah tribe after illegally shooting and killing a gray whale on Saturday with harpoons and a rifle often used to hunt elephants.

A number of gray whales have been spotted by scientists in recent years suffering from starvation. The researchers said their findings suggest the whales have less to eat due to changing climate conditions in their Arctic feeding grounds.

The researchers said other animals also may have been affected by the diminished numbers of the gray whale.

Fellow Stanford researcher Steve Palumbi said Arctic seabirds foraged on creatures dug up by the whales as they fed on the bottom. Palumbi said that 96,000 gray whales would have helped feed more than a million seabirds annually.

Related articles on Dolphins, whales and other cetaceans and large fishes.
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