ANCHORAGE, Alaska » A Hono­lulu-based Coast Guard cutter is off the coast of Japan, pursuing prosecution of an unregistered fishing vessel suspected of catching 40 tons of fish with an illegal high-seas driftnet.

Adm. Robert J. Papp Jr., the Coast Guard commandant, on Monday announced that the 378-foot cutter Rush had been assigned to Alaska waters but had followed the fishing vessel across the Pacific to enforce commercial fishing law.

"I would call this fishing piracy that is going on," Papp said during a hearing in Kodiak by the U.S. Senate Homeland Security Appropriations Subcommittee.

"They put eight miles of net out there and collect everything that flows through it," he said, possibly picking up migratory stocks destined for Alaska waters.

Crew members from the Rush have boarded the vessel, Papp said. The Coast Guard is working with other departments on the case.

"We have something called the Maritime Operational Threat Response organization, which works across State and Justice and other departments — and we’ve come to a national objective of seizing this, what amounts to, we found out now, is a stateless vessel," he said.

The vessel carried Chinese citizens who were manning the vessel, Papp said, and might be passed to China for prosecution.

"As a fallback, we can bring it back to the United States for prosecution as well," he said.

U.S. Sen. Mary Lan­drieu, D-La., was chairwoman of the subcommittee hearing.

"I hope we’re filing charges — not just against the men operating the ship, but the buyers of these fish, and tracking it down to the networks that are funding these kinds of illegal operations," Lan­drieu said.

Paul Niemeier, who works in the International Fisheries Affairs Division of the National Oceanic and Atmospheric Administration, said Tuesday high-seas driftnets have been banned internationally since 1992.

"Driftnets don’t differentiate, don’t select very well what they catch," he said. If a fish can get its head through the mesh, it will get caught behind the gill flaps, Nie­meier said. Bigger species hit the net, twist and turn, and get tangled up.

"That’s the way a lot of the sharks and marine mammals and seabirds used to get caught, just twisting around in the net."

The problem has dramatically declined. Just five or six years ago, he said, there were more than 100 sightings of suspected illegal fishing boats. Last year there were two sightings. The Coast Guard seized one vessel, and the other escaped.