Only about 150 or 170 of the dolphins, known as false killer whales, live in waters up to 87 miles off Hawaii’s coasts. A study published by the National Marine Fisheries Service in August said the small population is at high risk of suffering from inbreeding. It’s also at risk of being inadvertently snagged by fishing lines.

The agency plans to post its recommendation in the Federal Register on Wednesday.

Michael Jasny, a senior policy analyst for the Natural Resources Defense Council, which last year petitioned the government to list the population, said the animal needs help.

“When you have a population that’s as small as this one, as range-limited as this one, and on such a dangerous trajectory as this one, action is desperately needed,” Jasny said. “This is precisely the kind of situation that the Endangered Species Act was designed for.”

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.

The species is found in tropical and temperate waters worldwide including off Maryland, Japan, Australia and Scotland.

A few hundred live in waters farther from Hawaii’s shores, but this pelagic population is separate from the group that lives closer in.

Earlier this year a federal advisory group recommended that longline fishermen catching ahi, mahimahi and other fish use a different kind of hook to minimize the chances they will severe injure or kill the dolphins when they accidentally get snagged on their lines.

The government formed the advisory group in response to data showing the Hawaii-based longline fleet is accidentally killing or seriously injuring an average of 7.4 false killer whales each year.

This exceeds the 2.5 per year that the population can lose without hurting its ability to sustain itself.

The group also recommended that fleet captains undergo training on how to release any mistakenly caught false killer whales in a way that minimizes the risk of harm.

The dolphins tend to get caught by in longlines because they eat the fish that fishermen have snagged for human consumption: yellowfin tuna, mahimahi and ono.

The National Marine Fisheries Service plans to host a public meeting on its recommendation Jan. 20 in Honolulu and accept public comment on the issue through Feb. 15.