To return Puget Sound's resident orcas to health, the federal government needs to rebuild salmon stocks, continue cleaning contaminated shorelines and make sure that whale-watching boats don't disturb too many of the Sound's signature whales.

That's the assessment of a team of government scientists who released a plan yesterday meant to boost populations of so-called "southern resident" orcas that swim in and out of Puget Sound each year before disappearing to unknown parts of the Pacific in winter.

The plan comes two years after the Puget Sound orca population plummeted so perilously that the National Marine Fisheries Service (NMFS) agreed to draft the strategy.

But even NMFS officials yesterday acknowledged the new plan mostly just requires the government to continue doing what it has been doing: cleaning up Puget Sound and restoring salmon, the whales' primary food source.

Since a low of 84 orcas in 2003, the southern resident population has rebounded to 91. But environmentalists still have gotten the whales listed for protection under the Endangered Species Act, expected to take effect in December. Biologist maintain the southern residents can be sustained most safely if the population reaches about 120.

Fred Felleman, of the environmental group Ocean Advocates, said he was pleased NMFS has suggested that more be done to prevent oil spills and learn where whales go in winter.

But the agency missed an opportunity earlier this year when it declined to list a decimated stock of Puget Sound herring for protection as an endangered species, Felleman said. Orcas also feed on herring.

Craig Welch: 206-464-2093 or cwelch@seattletimes.com