Puget Sound steelhead, a fish prized by anglers and found in streams reaching far into the surrounding mountains, will now be protected...

Puget Sound steelhead, a fish prized by anglers and found in streams reaching far into the surrounding mountains, will now be protected under the Endangered Species Act, the National Marine Fisheries Service announced today.

The listing, which declares the fish as “threatened,” or at risk of going to the brink of extinction, covers naturally spawned steelhead from river basins of Puget Sound, Hood Canal, and the eastern end of the Strait of Juan de Fuca.

The steelhead now join Puget Sound Chinook salmon, resident orcas, and Hood Canal chum salmon as being federally protected. Bull trout that swim in freshwater streams feeding into the Sound are also protected.

While the protections for steelhead will largely overlap work already happening for chinook, the listing will likely extend such efforts deeper into the mountains. Chinook stay in large rivers, while steelhead move into smaller, high-elevation streams.

Biologists for the fisheries service say the decline in the steelhead population has been widespread, likely because of degraded habitat, man-made barriers, unfavorable ocean conditions and harmful hatchery practices.

The steelhead in today’s listing include more than 50 stocks of summer- and winter-run fish. The Skagit and Snohomish rivers support the largest populations. The protection doesn’t extend to rainbow trout, though the two fish are related. A steelhead is basically a rainbow trout that migrates to the ocean and returns. Occasionally, steelhead offspring can be rainbow trout, and vice versa.

National Oceanic and Atmospheric Administration spokesman Brian Gorman said the steelhead listing is likely to redouble efforts to improve the water quality of Puget Sound.

Rob Masonis of the environmenta group American Rivers said today’s announcement emphasizes that work to revive the Sound must also focus beyond saltwater.

“Rivers must be a central focus of that effort, because so many species depend on healthy rivers for their survival,” he said.

Warren Cornwall: 206-464-2311 or wcornwall@seattletimes.com

Associated Press contributed to this report