The achievement, officials said, was made possible by newly developed miniature tagging and tracking technologies that can follow small salmon over vast distances.
"It may have been one of humankind's first ponderings: the fish that got away -- where they come from, where they go and what happens to them in between," said Jim Bolger, executive director of the Pacific Ocean Shelf Tracking Project, part of the International Census of Marine Life and based at Canada's Vancouver Aquarium Marine Science Center.
"Until now it has been difficult to follow small animals in vast oceans and it has only been possible to infer their movements using very indirect methods," he said. "Thanks to new sound-emitting tags about the size of an almond, combined with an extensive coastal network of underwater detectors from Alaska to California, several mysteries of fish migration and survival may soon start to unravel."
A paper in the journal PLoS Biology describes one of the first applications of the technology -- comparing the survival of young salmon in dammed and un-dammed rivers.