They're less slimy, and certainly less smelly, than a fish carcass would be. But the dry, brown pellets that biologists distributed Tuesday in a backwater channel of Dry Creek may prove to be the vitamin that once-prolific North Coast salmon streams need.

The goal is to simulate the nutritional boost that used to come from the decaying remains of adult fish, a critical natural supplement for coho and Chinook salmon, steelhead trout and other wildlife.

The approach has shown promise in the Columbia River watershed over the past few years. It produced benefits last year in several tributaries of Sonoma County's Austin Creek.

"This could be a piece in the missing puzzle of recovery," said Bob Coey, a biologist with the National Marine Fisheries Service.

The agency was among several — including the U.S. Army Corps of Engineers, the Sonoma County Water Agency and the Russian River Wild Steelhead Society — that participated Tuesday in seeding a restored area of Dry Creek just south of the Warm Springs Dam with about 125 pounds of the salmon-meal pellets.

About two dozen Geyserville Middle School students also took part in honor of Earth Day, lobbing the pellets into a man-made channel designed to slow the current and enhance the survival of juvenile salmon.

"I didn't realize there was that much of a problem," said one student, Benjamin Paine, 13.

The pellets, which resemble hardened chunks of sausage, are manufactured in Sonoma County by AquaDine, a Healdsburg fish-food company.

Made from bits of salmon tissue left over from commercial seafood processing, they are formulated for seeding creeks and rivers that once hosted abundant spawning runs.

Over thousands of years, those wild runs left behind carcasses rich in nutrients derived from the ocean, where adult salmon and steelhead spend most of their days. Juvenile fish relied on those nutrients to support their food chain, including insects and other invertebrates.

Dams, development and other human uses largely broke that cycle over the past 70 years, landing all three fish — the coho and Chinook, or "king," salmon and steelhead — on the federal Endangered Species list.

Attempts to restore the fishery at times included hauling salmon carcasses from local hatcheries miles upstream to replicate the nutritional cycle.

It was unpleasant work, Coey said. The carcasses also aren't available in sufficient quantities given the efficiency of the hatcheries, he said.

Other seeding experiments over the past two decades have tried other nutritional supplements, including dog food and fertilizers, biologists said. Pellets made from salmon tissue made their debut in the Pacific Northwest about 10 years ago.

Tony Myers, executive director of the Lower Columbia Regional Fisheries Enhancement Group in Vancouver, Wash., cautioned that cost and limits on availability of fish meal means the pellets need to be used selectively. And their results are contingent on overall watershed health and other factors that influence seasonal runs.

Early tests in Washington's Wind River resulted in young fish that were six to eight times fatter than those raised in areas that weren't seeded with the pellets, Myers said.

The recontoured stretch of Dry Creek is an ideal place to experiment, given the need to "jump-start" the ecosystem and entice bugs and other critters to take up occupancy there, said Army Corps fish biologist Peter LaCivita.

Dozens of salmon fry barely more than an inch-long were swimming in the area Tuesday.

"Where we'd like to see it go is it becomes a management tool," Coey said of the seeding. "We could even get it to the point where it's required mitigation in certain areas."

You can reach Staff Writer Mary Callahan at 521-5249 or mary.callahan@pressdemocrat.com.