PORTLAND, Ore. » The wreckage of a fishing boat that appears to be debris from the 2011 Japanese tsunami was carrying some unexpected passengers — fish from Japanese waters — when it was spotted off the Oregon coast.

Scientists say 21 yellowtail jacks and one Asian striped knifejaw hitched a cross-Pacific ride in the bow of the boat found last week.

Fish washed up in debris can bring parasites and diseases to native species, but biologists say the latest fish pose little threat. Still, they have been quarantined at the Oregon Coast Aquarium and will be available for public viewing.

It’s not the first time that dislocated fish were found in Northwest waters.

Last month, a striped knifejaw turned up in a fisherman’s crab trap off the Oregon Coast. And in 2013, biologists found five striped knifejaws alive in a water-filled bait box on a 20-foot-long Japanese boat washed up in southwest Washington.

Except for one fish that the aquarium in Seaside agreed to quarantine and exhibit, the rest of those fish were euthanized to minimize the risk of introducing invasive species to Washington.

The latest fish find was made by a recreational fisherman in a 30-foot section of what officials believe was once a 50-foot commercial fishing boat.

The wreckage was discovered about three miles off the coast near Ona Beach, towed to a boatyard in Newport and later moved to a landfill.

When it was still offshore, the boat was inspected by biologists who consulted with the state Fish and Wildlife Department, deciding the fish posed little threat to the Oregon coast ecosystem.

"They are probably not dangerous. They are a warm water fish, so they are not going to spawn in the cold waters of the North Pacific," said John Chapman, an aquatic invasive species expert at Oregon State University.

Still, scientists are not taking any chances and won’t be releasing the fish back into the ocean, Chapman said.

During the four years since the tsunami, scientists have found about 300 marine species that have drifted to the Oregon shore inside or attached to debris, Chapman said.

Finding live fish in tsunami debris is significant, Chapman said, because scientists previously predicted that live organisms would not drift across the ocean on floating objects.

The fact that they do means they may be bringing parasites and diseases that could affect native species on the West Coast — something scientists must monitor closely.

"We don’t want things to be introduced that are beyond our control," Chapman said. "Those kinds of parasites and diseases can wipe things out."

Already, biologists found that the blue mussel, a common organism on tsunami debris, carries parasites. Thus far, there is no evidence these parasites have become established in native oysters, clams and other species, but the danger exists.

"We didn’t know how little we knew about this," said Chapman. "We expected that after four years there wouldn’t be any debris coming across the ocean. But we were surprised."