The incredible journey of Flex the Whale

Every summer at Sakhalin Island in Russia’s far east, the gray whales arrive. One of the smallest populations of whales in the world, they come in pairs and small groups from May to early June, and spend the summer feeding in the shallow coastal waters. When the icy Russian winter returns, the whales leave.

Like migrating birds, scientists assumed they went south in the winter, along the Asian coast to the South China Sea.  

But in 2010, one 13-year-old whale made an incredible journey, trekking vast ocean distances and changing marine scientists’ understanding of the entire gray whale population.

The voyage demonstrated that the small group of around 170 western gray whales arriving at Sakhalin each summer is in fact connected to the larger eastern gray whale population. Until then scientists had believed they existed separately, as the world’s largest ocean, the Pacific Ocean, lies between them.

The western gray whale is listed as critically endangered by the International Union for Conservation of Nature (IUCN). To collect data that would help them understand and safeguard the population, including where the whales live and how far they travel, a team of scientists from Russia and the United States, with support from the IUCN and the International Whaling Commission, successfully tagged one of the western grey whales with a satellite tracking device in October 2010.  

Within a few days, the young male whale, nicknamed Flex because of the way he flexed his body into an “s” shape as a calf, left the island. But to their surprise, Flex didn’t swim south; he went north.

“It was like being in on a secret. We couldn’t believe what we were seeing,” says Stephanie Lock, who manages Sakhalin Energy’s environment programme. Shell is a shareholder in Sakhalin Energy, one of the world’s largest integrated oil and gas projects, off the northeast coast of the island.

Flex first swam to eastern Russia’s Kamchatka Peninsula. Then – in a move that again surprised the team – he headed out into open water and crossed the Bering Sea towards Alaska. Dodging icebergs and predatory killer whales, Flex made it to Alaska, travelled down the western coast of Canada, and on down the US coast. As the whales aren’t known to migrate alone, the scientists believe others must have voyaged alongside him.

The longest migration

“I have studied whales for my entire career. This changed everything we knew about this species,” says Dr Randall Reeves, a marine mammal specialist based in Canada.  “We thought gray whales hugged the coastline. We didn’t know they could navigate those distances in open water.”

Eventually, the tag dropped off as he headed south along the US West Coast. For the scientists this was enough: Flex was clearly headed to a known breeding area near Mexico.

It took Flex just over 56 days to travel a total of 7661 kilometres, swimming at an average speed of 5.7 kilometres an hour.

 “These whales face enormous challenges on their journey, which is the longest migration of any mammal on earth,” says Anete Berzina, manager of the western gray whale project at the IUCN. “The more information we have on them the better we can protect them. After all, as the largest mammals in our seas, healthy whales indicate healthy oceans.”