Though gray whales are known for their annual migration between Alaska and Baja, California, locals can expect to see their spouts at any time of the year.
A new study from Oregon State University’s Marine Mammal Institute shows many of the cetaceans once thought to be part of a resident population travel long distances. But during the three-year study, 18 of the 33 whales scientists tracked hung out at Point St. George, said Barbara Lagerquist, a senior faculty research assistant with the institute.
“Eighteen whales had sort of extended residencies around Point St. George and the California-Oregon border ranging just over a month. The longest one was 142 days,” she said. “It’s pretty phenomenal. Obviously it’s a really important area. A large proportion of the whales in this study, 23 of 35, were tagged there and that’s because that’s where we were finding lots of animals.”
Out of the larger eastern North Pacific gray whale population, estimated at 20,000, about 200 make up the Pacific Coast Feeding Group. This is the group most people see amongst the kelp beds and rocks close to shore, Lagerquist said.
Lagerquist said she and her colleagues wanted to get a handle on the movements of these 200 whales and find out what areas they frequent the most to make sure they are protected. They also wanted to find out if they truly stick around the Pacific Northwest, she said.
Another motivation for the study was to show that satellite tagging whales and tracking them long term was safe and successful, Lagerquist said. Scientists’ goal was to get permission to tag members of the critically endangered western Pacific gray whale population found off the coast of Russia. Back in 2009 and 2010 the estimated population of western Pacific gray whales was 130 to 180 individuals, Lagerquist said.
For the Pacific Coast Feeding Group, scientists discovered their range extends from Northern California to Yakutat and Icy Bay, Alaska, Lagerquist said. Most, though not all, travel to Baja in the winter to breed, she said.
There’s no particular reproductive class or age range or sex that makes up the Pacific Coast Feeding Group, Lagerquist said. Scientists tagged about 18 males and 17 females out of 35 total. They have also seen calves and juveniles, she said.
“What we think is going on, what the genetic research shows, is that there is a significant difference in the mitochondrial DNA you see in this group compared to the eastern North Pacific group,” Lagerquist said, adding that the Pacific Coast Feeding Group does breed with the overall eastern North Pacific population in Baja. “Mitochondrial DNA is passed down from mothers to offspring. What that tells us is it’s likely females are migrating here with their offspring, teaching their offspring this is where they feed and the offspring are continuing to do that year after year.”
But Point St. George appears to be especially important for the Pacific Coast Feeding Group. Lagerquist said not only were they seeing a lot more animals there than any other area the study focused on, they saw socializing such as pectoral rubbing and breeding or pre-breeding behavior.
One male gray whale, tagged off Newport, Oregon, traveled to the Crescent City area and stayed for the entire winter, Lagerquist said. Instead of journeying further north or joining the migration south, this male moved between Central Oregon and Northern California for 383 days, she said.
A biopsy sample showed the animal was a male, Lagerquist said.
“We also know it was an animal that was first identified in 2000 by the people who contribute to the photo ID catalog for this population,” she said. “And it was tagged in 2009 at a minimum of 9 years of age. He was most likely older than that because he wasn’t identified as a calf in 2000.”
Lagerquist’s colleague, Marine Mammal Institute Director Bruce Mate noted the foraging area, timing and size of the hotspot areas the whales feed in are variable. The Point St. George area seems to be a popular area for whales because of the California current and an upwelling of nutrients caused by northwest winds, he said.
Gray whales are bottom feeders, often laying on their side and sucking up amphipods, Mate said. Whales also prey on mysids, small shrimp-like animals that swarm in the water column, he said.
“This is the first time we’ve really been able to put together sort of the size and variability of their foraging area and we’re really pleased about it,” he said. “If we had some benefactor come forward we would go back and do some targeted look at the individuals year after year and see if we can find out more about how variable that is.”
Lagerquist said scientists also identified the southern coast of Washington and the central coast of Oregon as hotspots for gray whales.
“Some of the photo identification research going on for many years shows there does seem to be a progression south through the range over the season,” she said. “In spring and early summer some of these animals are farther north and there’s a progression south as the season goes on. We tagged in the fall and tagged a lot of whales in Northern California. That area is pretty important, but it doesn’t mean it’s not really important for the whole population.”
Reach Jessica Cejnar at firstname.lastname@example.org .