Federal officials Wednesday announced that within a few months they will increase protection of false killer whales in by environmental groups.

The National Oceanic and Atmospheric Administration’s new rules include changes in the kind of hooks and lines used on commercial Hawaii longline fishing boats, which will help to lessen the unintentional hooking of the species.

False killer whales, or Pseudorca crassidens, are members of the dolphin family.

The rules identify as an endangered species a distinct stock of insular false killer whales that usually dwell within 20 miles of the main Hawaiian Islands, the agency said.

Michael Tosatto, NOAA’s Pacific Islands administrator, said during a news conference in Hono­lulu that officials estimate there are only about 151 insular false killer whales remaining.

The agency said surveys conducted by several independent researchers indicate the population has been in decline for at least the past two decades.

Insular false killer whales share food, operate within the same family, and do not interact with other families, he said. They act differently than two other stocks in Hawaii.

Some 550 false killer whales frequently ranging within about 50 miles of islands are in the Northwestern Hawaiian Islands, and about 1,500 false killer whales are in open water more than 100 miles from Hawaii coasts, the agency said.

Longline vessels using mackerel to fish for tuna can unintentionally hook false killer whales in their catch.

The rules would require commercial longline fishing vessels to use 400-pound-test monofilament fishing line and weaker hooks that would let false killer whales escape with little injury.

The rules also call for fishermen to be trained and certified in methods for releasing false killer whales.

The Turtle Island Restoration Network and the Center for Biological Diversity, represented by Earthjustice, sued the National Marine Fisheries Service in June, saying it failed to complete a plan to protect false killer whales under the federal Marine Mammal Protection Act.

Brendan Cummings, senior counsel for the Center for Biological Diversity, said the plan is significantly weaker than the one the organization supported. "It’s a half a step forward when we should be a full step forward," Cummings said.

Tosatto said federal officials are willing to consider changes if there are problems.

The rules will take effect 30 to 90 days after the publication of them in the Federal Register, the agency said.

The agency is under a court order to issue the final plan by Nov. 30, and the rules are scheduled to be published Monday.

Earthjustice has said the National Marine Service’s own data showed for more than a decade that Hawaii-based longline fishing kills false killer whales in Hawaii at unsustainable rates.

Earlier this year, Earthjustice said the latest data, which the agency released in August, reveal that, each year, longline fishing kills an average of 13 false killer whales from the Hawaii pelagic stock found more than 22 nautical miles from the main Hawaiian Islands, nearly 50 percent more than what the agency has said that population can sustain.