“We’ve characterized, better than ever before, that it is a really critical area in the life history of these animals,” he said in an interview.
Tagging revealed that several species — including leatherback sea turtles, black-footed albatrosses and salmon sharks — followed similar routes from the western, central or south Pacific to reach the current’s rich resources.
While scientists tracked most animals for less than a year, they followed several tunas, sharks and turtles for longer: in the case of one salmon shark, well more than 31
Costa said the fact that these different creatures are following the same path helps account for why some of them, including leatherback turtles, get caught by fishing vessels that are targeting other species. In one instance, he noted, the same female elephant seal tagged in 1995 off the island of Ano Nuevo north of Santa Cruz “took the same exact path 11 years later” when researchers tagged her again.
“It’s not genetic; it’s some sort of learned behavior,” Costa said in an interview.
The scientists emphasized that the fact that many of these commutes largely take place within the exclusive economic zones of the United States, Canada and Mexico — the 200-mile stretch from shore that individual countries can govern — means that the three countries can adequately protect these areas.
In the case of sharks, Block said, researchers were able to determine that species with a common ancestor — salmon, white and mako sharks — preferred to spend time in slightly different temperatures. In Alaska, salmon sharks swim in water as cold as 42.8 degrees but can manage in temperatures as high as 53.6 degrees; great whites stick close to the California coast at 53.6 degrees but journey to Hawaiian waters as balmy as 69.8 degrees; and makos inhabit seas as warm as 80.6 degrees.
“We’ve dug inside the guilds down to the species level,” Block said.
The information revealed through electronic tagging, Ausubel said, should compel policymakers to protect these underwater animal meccas: “It’s a joy and a revelation, and it’s also a call to action.”