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Scientists, as part of the Tagging of Pacific Predators Program, followed more than 4,000 marine animals for more than a decade across the oceans to get a unique geographic snapshot of life under the surface.
Researchers found that the California current, which drives the water along the coast, draws together predators as diverse as blue whales, bluefin tuna and sea turtles every year. The cool current teems with marine organisms, which in turn lure predators. Other predators migrate there to mate.
"Now we're learning that our North American shores have what's equivalent to Yellowstone," a natural area filled with all kinds of predators, says Stanford University professor Barbara Block, one of the lead authors of the Nature paper.
Researchers also found the North Pacific Transition Zone, an area between Hawaii and the Aleutian Islands, to be another region frequented by top predators.
The program is part of the larger Census of Marine Life, a 10-year study that documented hundreds of thousands of ocean organisms, discovering more than 6,000 new species. Financed by about $20 million from the federal government and nonprofit foundations, the tagging program focused on following predators, including albatross, sharks and seals, in the Pacific Ocean.
Program researchers, who were from multiple universities, including Oregon State University, studied 23 predators by physically tagging animals and mapping the results. They followed migration patterns for many of the species.
"It is the most in-depth undertaking of its type that's ever been done anywhere, ever," says Bruce Mate, director of the Marine Mammal Institute at Oregon State, who followed the whales as part of the study.
Andrew Trites, director of the Marine Mammal Research Unit at the University of British Columbia, agrees. Trites wasn't part of the study, but he says the tagging program's collaboration between researchers studying different species combined with cutting-edge tracking technology showed a new picture of the Pacific.
"I was one of the ones that was in awe when the results came in," Trites says.
But physically tagging all 4,000 animals in different areas of the Pacific wasn't easy, Mate says.
"It wasn't just one kind of tag, it was a half-dozen different kind of tags at least, and everyone of those tags has its idiosyncrasies," says Randy Kochevar of Stanford, one of the principal investigators with the tagging program.
Then, more than 75 researchers coordinated and compiled large volumes of data, all the while dealing with rapidly changing technology over the 10-year period.
While one part of the findings identified areas such as the California current, where there is significant overlap between predators, the study also gave an opportunity for researchers to observe "a lot of individual details that really are kind of eye-popping about lifestyle," Mate says.
He says his group was able to watch blue whales breed 500 miles off Costa Rica, another discovery in its own right.
Oregon State's Mate predicts this is not the end of what's to be discovered in the sea. He believes others will use the same tracking techniques to map more of the ocean's creatures.
The study also sets the framework for smarter conservation by identifying top predator hot spots and the routes that connect those hot spots, likely requiring an international endeavor, Stanford's Block says.
"We have the opportunity in our lifetime to ensure that these ocean areas that are rich with predators remain intact and the ecosystem remains resilient," she says.
But the University of British Columbia's Trites reckons that it will be difficult to find the political will and the necessary finances for protection of the hot spots.
"The solutions are there, but they're going to come at a cost," he says. "Are we willing to pay that today?"
-- Mihir Zaveri