Exotic Japanese fish hitchhiked 5,000 miles on tsunami to California, scientists say

Barred knifejaw previously only seen off Japan, Korea and China

An exotic Japanese fish spotted by divers off the coast of California probably crossed the Pacific Ocean by hitching a ride on debris from the 2011 tsunami, scientists believe.

The barred knifejaw, a black and white striped fish, has been seen several times in Monterey Bay, just south of San Francisco, since 2014.

But the species is unheard of in the waters surrounding the coasts of the United States and is native to Japan, Korea and China, more than 5,200 miles away.

Scientists believe the only way the fish could have completed the epic journey across the Pacific is by being carried across by debris washed out to sea by the devastating 2011 Japanese tsunami.

Barred knifejaw like to live in seaweed forests and fields of rubbish and debris often become havens for marine wildlife including the distinctive fish species because they imitate the conditions of kelp forests.

As the slow-moving ocean currents in the Pacific slowly dragged detritus from Japan west across the ocean towards America, fish like the barred knifejaw are thought to have moved with it.

“These currents circle around and around and then just depending on local conditions the water may move on shore,” Jonathan Geller, a scientist at California’s Moss Landing Marine Laboratories, told CNN.

Dr Geller has researched the impact of the 2011 tsunami on marine wildlife and has documented 289 Japanese coastal species which reached the shores of Hawaii and North America over a six year period.

“This fish stands out because it looks quite alien in our water and it’s definitely a species we haven’t seen here before this event,” Dr Geller said.

“Divers or people visiting the beach may not notice anything that looks unusual to the untrained eye.

“But in fact, some of these creatures could have been part of this tsunami invasion event.”

Nicholas Ta, a divemaster at a nearby diving centre and marine ecologist who spotted one of the barred knifejaw, said it was immediately obvious swimming among the local kelp beds.

“It can’t be mistaken for any local fish,” he said. “Other fish are kind of camouflaged and they kind of match the environment around them.”

The barred knifejaw sighted by local divers are thought to be several different individuals, but the Japanese interlopers are not believed to be breeding.

The waters off California are about five degrees cooler than the fish is used to, which usually prevents them from reproducing.

Rick Starr, another researcher from Moss Landing Marine Laboratories, told CNN this meant the barred knifejaw were unlikely to disrupt the ecosystem in Monterey Bay, which is one of the largest marine protected areas in the US and home to a world-famous aquarium.