The number of False Killer Whales in Hawaiian waters is declining rapidly, experts say by 9 percent each year.
It isn't an ocean predator, instead mankind that is threatening to kill off the species.
"The unsustainable level of fishing related injury and mortality just can't go on," said David Henkin, the attorney for Earthjustice, a conservationist group.
Conservationists say longline fishermen are responsible for the population hitting an all-time low of roughly 170 animals.
To prevent the mammal's extinction, a team of experts known as the False Killer Whale Take Reduction Team established guidelines.
Henkin filed a lawsuit Monday against the National Marine Fisheries Service claiming it failed to implement the plan last year.
"The agency is just dragging its feet saying well we need to tweak here and do that there, meanwhile the whales are out on the high seas and being killed and that's got to stop," said Henkin.
The regulations include managing how far offshore a fisherman can cast a line. It also mandates the type of fishing hooks used. Researchers say the whales are often injured or even killed after swallowing a fish that ingested a hook.
"What the false killer whales are doing is they take most of the fish off the line and they leave the head so if the head is what's hooked then you is going to reduce the rate of getting hooked," said Dr. Robin Baird of the Cascadia Research.
Lastly, fishermen would have to use weaker hooks, in case a whale is caught. It gives the animal a better chance of freeing itself.
"It's time to finally get the plan out because while the plan is in draft form it's not doing the whales any good," Henkin said.
A spokeswoman for the National Oceanic and Atmospheric Administration, which oversees the fisheries services, says the agency got the lawsuit Monday afternoon and still needs to review it before commenting on the case.