After years of advocacy, about 17,500 square miles of ocean around the main Hawaiian isles will be designated as protected critical habitat for Hawaii’s endangered false killer whales.

The new rule by the National Oceanic and Atmospheric Administration’s National Marine Fisheries Service, was published Tuesday in the Federal Register and goes into effect Aug. 23.

The Center for Biological Diversity, an Arizona-based nonprofit, has been pushing for protection of the whales, which are actually members of the dolphin family.

“It’s a very good day for the false killer whales,” said Brett Hartl, the center’s government affairs director. “Getting critical habitat is a very important step, and a very useful tool to help get a species on the path to recovery. This is progress, and now we need to keep moving forward, and make sure we do what needs to be done to protect the false killer whale and its habitat from harm.”

Only about 150 false killer whales, or Pseudorca crassidens, remain in waters around the main Hawaiian isles today.

The protected habitat for false killer whales includes ocean waters from Niihau to Hawaii island, at depths of 45 to 3,200 meters.

This habitat must offer the false killer whales adequate space for movement within the ocean shelf and slope around the main Hawaiian isles, along with enough prey species and water free of harmful pollutants and chronic noise.

A total of 14 areas were excluded — including 13 requested by the U.S. Navy and one by the Bureau of Ocean Energy Management. The Navy requested that part of the Alenuihaha Channel, an area north of Molokai, and the Kahoolawe Training Minefield, along with other areas, be excluded. The bureau’s request includes two sites — one off of Oahu’s south shore and Kaena point — for off shore energy projects.

“What they’ve done is probably not exactly what we hoped for,” said Hartl, when asked about the exclusions, “but I think at the end of the day, the critical habitat that the false killer whale receives is a huge step in the right direction.”