OJO DE LIEBRE LAGOON, Mexico — When scientists fired a cigar-sized satellite tag into the blubber of a western gray whale off Russia's Sakhalin Island in September, they expected to track her along Asia's Pacific shoreline down to the South China Sea.

OJO DE LIEBRE LAGOON, Mexico — When scientists fired a cigar-sized satellite tag into the blubber of a western gray whale off Russia's Sakhalin Island in September, they expected to track her along Asia's Pacific shoreline down to the South China Sea.

To their surprise, the young female turned up off of Mexico's Baja Peninsula.

The sudden travel bug that infected Varvara, the 9-year-old female now meandering in waters near Baja's Magdalena Bay, has deepened a mystery that has scientists the world over pondering what is happening to a tiny population of critically endangered western gray whales. Only 130 of the whales remain, feeding off of Sakhalin Island, not far from two offshore oil platforms.

In recent years, however, gray whales have been spotted far from their known migratory routes. One turned up in the Mediterranean off Israel, and a pair was seen in the Arctic's Laptev Sea.

Varvara's movements are sending a frisson through whaling circles.

"It's a scientific event — a big one," said Randall Reeves, a marine mammal expert who is a member of the global Western Gray Whale Advisory Panel, which met in Geneva earlier this week.

Varvara's movements have "demolished conventional wisdom," he said. "It's always been believed that gray whales are coastal migrating mammals."

To get to Mexico, Reeves said, Varvara had to cross the Okhotsk Sea off the Siberian coast, navigate up Russia's Kamchatka Peninsula, strike out across the huge and deep Bering Sea far from any coast, and into Alaskan waters. Once there, the whale would have migrated to Baja along the North American shoreline.

"For all scientists interested in animal migration, we are following this pretty closely," Reeves said.

Gray whales once swam in both the North Pacific and North Atlantic oceans. Under intense whaling pressure — whale oil was then what petroleum is to the world today — they had disappeared from the North Atlantic by the early 1700s. Two centuries later, the Pacific population also grew endangered.

Good environmental practices helped rescue California gray whales, also called eastern Pacific gray whales, and they've returned to a healthy population of 18,000 to 20,000. They spend summers suctioning for small crustaceans in a shallow area of the Bering Sea and winters breeding near Baja.

But the western gray whale — which varies genetically from the California whale — remains besieged, migrating each year from Sakhalin Island south along coasts to unknown Asian breeding grounds.

A joint team of U.S. and Russian scientists began researching the Sakhalin population in 1995 and started to tag them in 2010 to learn their migration routes.

"Because their numbers are so low — 130 individuals is the estimate — it would be really important to find out where they are breeding to offer protection," said Bruce Mate, director of Oregon State University's Marine Mammal Institute and a member of the bi-national team.

The shallow feeding grounds off Sakhalin Island are threatened by gas and oil exploration. A third offshore platform is planned and will entail seismic testing.

"It's a very dangerous place to be a whale," said Stephen R. Palumbi, a marine ecologist at Stanford University. "If a whale population is stuck there, it's like being stuck in a very bad inner-city neighborhood."

That's why the discovery of Varvara off the coast of Baja has given whale experts new hope. Instead of facing doom in a poor habitat, the whales may be seeking ways to survive.

The first evidence that western gray whales were migrating from Sakhalin to North America came in 2010, when scientists tagged a 13-year-old male they dubbed Flex. He was off the coast of Oregon when his tag's transmitter failed.

Varvara's journey of more than 7,000 miles this year suggests that Flex's migration was not an anomaly, and that western gray whales have far better navigation skills than previously understood.