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Saturday, June 16, 2001 - Page updated at 12:00 AM

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Vanishing steelhead a mystery

Seattle Times Eastside bureau

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Each year in early June, a rite of spring concludes in Northwest rivers: the spawning of wild winter steelhead. In the past two years, however, the sea-going rainbow trout so prized by fishermen for its elusiveness and fight has pulled a disappearing act around Puget Sound that has left state biologists befuddled, and a little worried.

Fish returns are still being tallied, but the number of wild winter steelhead that spawned in the Sound's creeks and rivers the past two springs is "probably the worst ever," said Bob Leland, state steelhead manager for the Washington Department of Fish and Wildlife.

On world-famous steelhead river systems such as the Skagit, concerned officials imposed unprecedented fishing bans last winter, after predictions that only 40 percent of the basin's goal of 6,000 wild fish would return to spawn.

On the Cedar River, which spills into Lake Washington, just 50 fish are thought to have returned this spring.

"It just doesn't make any sense," said Steve Foley, the state anadromous fish biologist for Lake Washington and the Green River.

Logging, development and destruction of habitat have hurt steelhead numbers in the past, but it has been difficult to find a single culprit for the latest dip, biologists said. Many suspect North Pacific Ocean temperatures, which rose in the mid-'90s and may have brought new predators north and pushed cold-water-loving steelhead into a smaller feeding area.

Although biologists do not believe the fish face a crisis in Puget Sound, they say several steelhead runs in British Columbia are close to extinction. Today all but one of 25 steelhead rivers and streams between Victoria and the Campbell River are closed to fishing.

"We're down to 5 and 10 percent of the returns that we saw 10 and 20 years ago," said Bob Hooton, a steelhead specialist with the Ministry of Water, Land and Air Protection.

The life cycle

Steelhead are a complicated marvel. Hatched from eggs in freshwater streams in June and July, winter steelhead fry remain in fresh water for two years before heading to sea as smolts. They mature in the North Pacific for up to three years before returning to their place of birth.

Puget Sound's most-common wild steelhead runs are these "winter" fish that return from mid-March to early June. About 15 percent of steelhead return to spawn again the next year. The fish have been known to return to spawn as many as six times.

Some rivers have runs of hatchery steelhead, bred to return at different times of year from the wild fish, and some rivers have wild summer runs of steelhead.

Even vigorous steelhead runs tend to be small - few thousand of the speckled, chrome-bellied fish in a river, compared with healthy runs of tens of thousands of crimson salmon. After surveys in the mid-1990s, the federal National Marine Fisheries Service concluded that Puget Sound runs did not warrant protection.

Given the fish's relative health, scientists were surprised by the dramatic drop in numbers over the past two years. On the Skagit and Sauk rivers, the number of wild winter steelhead that reached spawning grounds last spring was the lowest since 1979. Estimates for this year for the rivers are even lower. Similar lows on rivers such as the Snohomish and Stillaguamish also jarred scientists last year.

The reason may be a warmer ocean in the mid-1990s caused by global warming, the El Niño disruption, a natural 10-year flux in ocean temperatures known as the Pacific Decadal Oscillation - or some combination of the three, say scientists.

Further muddying the picture are the mixed signals from other rivers.

Not all runs are in trouble

Olympic Peninsula rivers such as the Quileute continue to have enough wild steelhead to support fishing, and even the run in the nearby Green River, while lower, is still considered healthy.

The rambling nature of the region's steelhead only deepens the mystery.Washington steelhead will ride ocean currents 30 miles a day, heading as far as the International Dateline before looping back thousands of miles, said Curt Kraemer, a state biologist for the Snohomish and Stillaguamish river basins.

"It's not unlike getting on a carousel and going around and around," Kraemer said. Some runs may "get on a different horse" as the carousel of currents spins, he said. Depending on when they went to sea, Puget Sound winter steelhead may have encountered warm-water predators such as hake and mackerel, while coastal steelhead may have dodged such dangers, he said.

"It's at the point that we're concerned about it, but we're not talking about extinction," Kraemer said of the declines.

Seattle area runs up, down

No steelhead run in Western Washington has proven more confounding than the one in Seattle's back yard.

In the early 1980s, biologists estimate that as many as 2,600 wild winter steelhead were returning to the Lake Washington system and the Cedar River. The river and its watershed provide two-thirds of the drinking water for 1.25 million people.

The number of winter steelhead dropped through the next decade, until just 70 wild fish spawned in the spring of 1994. The main culprits were thought to be sea lions who stationed themselves outside the Ballard Locks and ate the returning fish.

By 1997, the wild winter steelhead run seemed on the rebound. Several sea lions had been shipped to Sea World in 1996. The river had been closed to fishing. And in 1994, Seattle Public Utilities and the state had started monitoring steelhead nests, called redds, to ensure that enough water was kept in the river to keep them underwater during the eggs' incubation.

Then, last spring, just 48 steelhead arrived in the river, said Foley, the state biologist who monitors the Cedar. This year's numbers were supposed to be better, since about 600 fish spawned four years ago, and their progeny should now be returning. Instead, Foley said recently, he expects about 50 fish.

"I'm just scratching my head," Foley said. "In general, marine survival is lower, but it's not this bad."

Ocean temperatures have been cooling over the past two years, perhaps signaling the return of more favorable conditions for wild steelhead in British Columbia and Puget Sound, according to B.C.'s Hooton. In the meantime, the recent downturn has caused some disagreement about how Washington state has managed steelhead.

One critic is Frank Urabeck, a steelhead advocate with the conservation group Trout Unlimited.

"Most biologists will say that if you have less than 100 fish coming back you're in trouble," Urabeck said, citing factors such as inbreeding. "We may have to do some extraordinary things" to keep it going, he said of the run. The state should consider bolstering the Cedar River population by capturing wild fish and raising their brood in a hatchery before releasing them, Urabeck said.

The state has declined to introduce hatchery fish to the Cedar or to mix fish from different rivers to date, said Foley, because biologists want to give the run a chance to rebound naturally.

A new group, the Wild Steelhead Coalition, formed last fall in response to the fishing closures on rivers and is now lobbying for a statewide policy that would keep fishing season open, but require wild steelhead to be released, everywhere. The proposal for a statewide catch-and-release policy has infuriated other fishermen, however, especially on coast rivers where runs appear less fragile.

Officials do not seem likely to take that step yet. Much is still unknown about the resilience of the mysterious fish.

"Just about the time you start figuring them out," said Rand Little, a senior fish biologist with Seattle Public Utilities, "they make a liar out of you."

Chris Solomon can be reached at 206-515-5646 or csolomon@seattletimes.com.

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