SAN FRANCISCO — The federal government banned commercial fishing for swordfish in a large swath of the Pacific Ocean on Thursday in a move to protect endangered sea turtles who were being killed or injured by the hooks.

The new rules, released by the National Marine Fisheries Service, prohibit longline fishing for swordfish in the Pacific between the West Coast and Hawaii. The ban, scheduled to take effect April 12, will affect about two dozen fishing boats based in California, Oregon, and Washington.

Recreational fishing is not affected.

"It's an important step in protecting endangered sea turtles from going extinct," said Todd Steiner, director of the Turtle Island Restoration Network, which lobbied for the ban. "It won't save the sea turtles by itself, but when the U.S. takes proper action, it's in a better moral position to get other countries to also take action."

The United States makes up only about 5 percent of the global swordfish fishing fleet, Steiner said. Japan, Korea, and Taiwan all have large fleets.

Longline fishers use lines up to 50 miles long that carry thousands of baited hooks to catch swordfish.

Sea turtles, sharks, dolphins, and seabirds also get caught on the hooks. Federal officials have estimated that long-lining kills 61 threatened loggerhead sea turtles and 15 endangered leatherback sea turtles each year. Biologists say the leatherback could become extinct in 10 to 30 years if current trends continue.

The fisheries service issued the ban after its scientists determined that continued swordfish fishing would jeopardize the survival of the sea turtles, said Tim Price, the agency's assistant regional administrator for protected resources.

In August, the 9th U.S. Circuit Court of Appeals ruled that the fisheries service had violated the Endangered Species Act by allowing longline fishers to continue operating along the West Coast.

The fishers have said a ban on swordfish fishing would threaten their livelihood.

The rules bar longline fishers from bringing in their catch to West Coast ports. A 2001 federal ruling bars them from operating in Hawaii.