CORVALLIS, Ore., April 15 (UPI) -- The record for longest mammal migration now belongs to a gray whale named Varvara. The 9-year-old female swam 13,987 miles from Russia to Mexico and back, all in less than six months.
The whale's migration was tracked in an effort to better understand a unique population of gray whales who prefer the northwestern Pacific waters along the coast of Russia. Most biologists are more familiar with the groups of gray whales that hug the coast of California, and scientists believed the two groups rarely, if ever, intermingled.
The length and path of Varvara's epic journey has some biologists rethinking the two whale populations and their migrations.
Tagged by researchers at Oregon State University's Marine Mammal Institute, Varvara set records with just the first half of her journey. Her trip from her preferred feeding grounds in the Arctic waters of the northwest Pacific (near Russia's Sakhalin Island) to the breeding waters off the coast of Mexico's Cabo San Lucas was already the longest transoceanic voyage by some 2,000 miles. Her return trip only added to the cushion. During that initial leg, Varvara enjoyed the company of two other whales -- Flex, a 13-year-old male, and Agent, a 6-year-old female.
What's unique about Varvara's journey is not simply the length, but the nature of her trek -- across open ocean. Most whales stick to the coasts. It's believed young whales learn their sense of direction from their mothers, their memory bolstered by coastal landmarks and the information sonar waves bounced off coastal formations provides.
Accordingly, scientists assumed the little-understood gray whale population of the western Pacific traveled in a loop from the Arctic to the South China Sea. But Varvara forewent coastal landmarks, crossing the Bering Sea without any concrete nautical reference points.
The details of Varavara's journey raise questions about the distinction drawn between eastern and western populations of gray whales in the Pacific.
"The ability of the whales to navigate across open water over tremendously long distances is impressive and suggests that some western gray whales might actually be eastern grays," lead researcher Bruce Mate, director of the Marine Mammal Institute, said in a press release. "But that doesn't mean that there may not be some true western gray whales remaining. If so, then the number of true western gray whales is even smaller than we previously thought."
During the study, Varvara was even observed swimming close to packs of eastern whales off the coast of Oregon.
"The fact that endangered western gray whales have such a long range and interact with eastern gray whales was a surprise and leaves a lot of questions up in the air," Mate said. "Past studies have indicated genetic differentiation between the species, but this suggests we may need to take a closer look."
Varvara's unique journey is detailed in the latest issue of the journal Biology Letters.