The federal government is moving to protect a rare dolphin species from getting accidentally snagged off Hawaii’s shores.

New rules proposed by the National Marine Fisheries Service would require the state’s longline fishing fleet to use a certain type of hook while fishing for ahi, mahimahi and ono. The plan aims to protect a dolphin species called false killer whales.

The agency recently published the proposed rules in the Federal Register and is accepting public comment on the ideas through mid-October.

The government wants the new restrictions because studies have shown the fleet has been accidentally killing or seriously injuring an average of 7.4 false killer whales each year. This exceeds the 2.5 per year that the fishery could kill or seriously harm without affecting the population’s ability to survive.

The main problem is that the dolphins like to eat the same fish the longline fishermen are trying to catch, and the ocean mammals dine on fish hooked on the fishing lines.

"We think that’s when a lot of the accidental hookings happen," said Nancy Young, a National Marine Fisheries Service expert on the issue. "We don’t know if they’re visually and acoustically cuing on the gear. But somehow they’re finding the boats, and they’re finding the gear in the water, and they’re taking a lot of bigeye off the lines."

Longline fishing vessels string a line in the ocean, ranging from a mile to 50 miles long, to catch fish. They run smaller lines with baited hooks off the central line and wait for bait to attract fish.

Almost all of the new rules proposed by the agency were developed by a task force comprising scientists, fishermen, conservationists and civil servants who met several times last year to think of ways the fishery could reduce the number of false killer whales caught accidentally.

The team suggested that the fishery be required to use circle hooks instead of the Japanese-style tuna hooks — shaped more like the letter "J" — many in the fleet had been using. The task force and the agency both believe false killer whales would be less likely to get caught on the circle hooks, which are weaker than the Japanese-style hooks. They also believe false killer whales that do get caught will have an easier time wiggling free of the circle hooks.

Many longline fishermen have already started using these circle hooks, as they’ve been following some of the task force’s recommendations even before the federal government has formally adopted them.

Another proposed rule would close an area south of the main Hawaiian Islands to the longline fishery once a given number of false killer whales have been killed or injured in a given year. The next year, the agency would lower the allowable number of serious interactions in the zone.

This area is being targeted for additional regulation because it’s where many false killer whales have been getting accidentally snagged.

The species is found in tropical and temperate waters worldwide, but the two populations near Hawaii are small. Scientists estimate about 120 live in waters up to 60 miles off Hawaii’s coasts. A few hundred more live close to Hawaii in waters farther out.

False killer whales can grow as long as 16 feet and weigh more than 1 ton, and are usually black or dark gray. They don’t look like killer whales, despite their name.

» National Marine Fisheries Service Pacific Islands Regional Office: www.fpir.noaa.gov