WASHINGTON – Nearly 300 species of fish, mussels and other sea critters hitchhiked across the Pacific Ocean on debris from the 2011 Japanese tsunami, washing ashore alive in the United States, researchers reported Thursday.
It is the largest and longest marine migration ever documented, outside experts and the researchers said. The scientists and colleagues combed the beaches of Washington, Oregon, California, British Columbia, Alaska and Hawaii and tracked the species to their Japanese origins. Their arrival could be a problem if the critters take root, pushing out native species, the study authors said in Thursday's journal Science.
“It's a bit of what we call ecological roulette,” said lead author James Carlton, a marine sciences professor at Williams College in Williamstown, Massachusetts.
It will be years before scientists know whether the 289 Japanese species thrive in their new home. Researchers roughly estimated a million creatures traveled 4,800 miles.
Invasive species – plants and animals thriving in areas where they don't naturally live – are a major problem worldwide. Marine invasions in the past have hurt native farmed shellfish, eroded the local ecosystem, caused economic losses and spread disease-carrying species, said Bella Galil, a marine biologist with the Steinhardt Museum of Natural History in Tel Aviv, Israel, who wasn't part of the study.
A magnitude 9 earthquake off the coast of Japan triggered a tsunami on March 11, 2011, that swept boats, docks and other man-made materials into the Pacific. The debris drifted east with an armada of creatures, some giving birth to new generations while at sea.
The researchers collected and analyzed the debris that reached the West Coast and Hawaii over the last five years, with new pieces arriving Wednesday in Washington. The debris flowed across the North Pacific current, as other objects do from time to time, before it moved north with the Alaska current or south with the California current. Most hit Oregon and Washington.
The researchers note another huge factor in this flotilla: plastics.
Decades ago, most of the debris would have been wood and that would have degraded over the long ocean trip, but now most of the debris – buoys, boats, crates and pallets – are made of plastic and that survives, Carlton said. And so the hitchhikers survive, too.
“It was the plastic debris that allowed new species to survive far longer than we ever thought they would,” Carlton said.