WASHINGTON (Reuters) - 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.
HUNTED TO THE BRINK OF EXTINCTION
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.
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