ANCHORAGE — A research team using satellite tracking technology is causing marine mammal biologists to re-examine what’s known of highly endangered western Pacific gray whales.
For the second time in two years, scientists have tracked western gray whales — considered a separate population from California gray whales — from summer feeding grounds off Russia to the North America coast, challenging the assumption that western whales spent winters in the south China Sea.
A 9-year-old female as of last week had crossed the North Pacific to U.S. waters and swam south all the way to Tijuana, Mexico, apparently heading for breeding and calving rounds in lagoons of Baja California.
She’s the third western Pacific gray whale tagged by the research team that has crossed the North Pacific, leading biologists to question whether they’re part of an endangered, separate population that shares a feeding area or an extension of the California gray whale population.
“I don’t think there’s any question that there used to be a western gray whale population that went down the Asian Coast,” said Bruce Mate, director of Oregon State University’s Marine Mammal Institute. “I don’t think that there never were western gray whales. The question is whether western gray whales of that sort still exist or not.”
Mate is part of an international research team that includes the National Marine Fisheries Service, the A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Sciences, the Kronotsky State Nature Biosphere Reserve and the Kamchatka Branch of the Pacific Institute of Geography.
Western Pacific gray were hunted and by the 1970s were thought to be extinct until a population was spotted off Sahkalin Island. Just 130 animals remain. They face threats from shipping, offshore petroleum development and by fishing nets set off Japan.
In contrast, California gray whales, also called eastern Pacific gray whales, are a recovery success story. Their numbers were decimated by whalers but are now estimated at 18,000. They were taken off the endangered species list in 1994.
California gray whales feed in the Bering, Chukchi and Beaufort seas off Alaska in summer. They migrate down the West Coast to breed, mostly in bays of Baja California.
U.S. and Russia scientists in September 2010 attached a satellite tag to a single whale, a 13-year-old male they named Flex. Two months later, he began a journey that researchers tracked through Alaska waters to central Oregon.
Scientists believe the satellite tag fell off about Feb. 4 after Flex had traveled 5,335 miles over 124 days.
Researchers in September set up again in Russia and attached tags to six whales. Four tags quit working before whales left Sakhalin Island, but in late November, young, tagged females named Varvara and Agent were tracked crossing the Sea of Okhotsk. A week later, traveling separately, they swam around the Kamchatka Peninsula and headed east across the Bering Sea toward Alaska.
Both crossed the Aleutian Islands into the Gulf of Alaska in late December. Agent’s tag quit transmitting during the first week of January as she was two-thirds of the way across the gulf.
A tag continues to send signals from 9-year-old Varvara, the Russian version of Barbara. She reached British Columbia and the Pacific Northwest during the first week of January and swam steadily south, averaging 100-125 miles per day past Washington, Oregon and California. The whale last week traveled from Cape Mendocino in northern California to the border between San Diego and Tijuana — more than 6,000 miles in two months, equal to a quarter of the way around the world without stopping, Mate said.
Not all scientists believe western gray whales are a separate, distinct species. Valentin Ilyashenko of the Severtsov Institute and the Russian representative to the International Whaling Commission proposed in 2009 that gray whales found in Russian waters were part of an eastern population restoring its former historical range, according to information provided by Oregon State University.
It’s possible, Mate said, that western gray whales always shared a foraging areas with eastern Pacific gray whales, and the animals tagged by researchers happened to be a portion of the population of the eastern group.
“There may be western (whales) there, which statistically would have to suggest right now that they’re in the minority, in which case they’re even more endangered that people thought,” Mate said. “The other possibility is that there are no more western gray whales left and we’re just looking at the westerly-most foraging area for the eastern north Pacific population. All three of those possibilities exist.”
The tracking project also may change concepts of gray whales’ navigating skills.
“Most of the animals that migrate up and down the West Coast of North America seem to be doing so very, very near shore and it has given scientists sort of the impression that they are very poor navigators, moving only with the sound of their shore on their right to get from Mexico to Alaska, and vice versa,” he said.
The western whales, each taking their own routes, show that they’re competent open water navigators, Mate said.
“These routes, we think probably depict how they went from Mexico to Sahkalin Island as a calf. What we’re really, really hoping for is that Varvara’s tag is going to last long enough to not only get her to her breeding area in Mexico, but also back to Russia so we can see if she goes back over the same path she came to North America.”
Satellite tags on gray whales can last a year but average 123 days, a length already exceeded. If the tag keeps transmitting and Varvara returns by the same path, Mate said, it will be the first confirmation that the animals follow know a route rather than navigating by another means.
“It’s a small sample size, but when you don’t have any sample at all, even a single paired observation like that becomes the basis for a new paradigm until we see otherwise with more animals,” he said.
The International Whaling Commission and International Union for Conservation of Nature contracted with the research groups using money from Exxon Neftegas Ltd. and Sakhalin Energy Investment Company Ltd.
Trek of tagged western Pacific gray whales: http://bit.ly/nvC1JO