Scientists Seek Clues to Dying Steelhead

Steelhead, which are similar to rainbow trout but spend much of their lives in the ocean and return to rivers to spawn, have such complex life cycles that unraveling the mystery of their decline is difficult.

BUCKLEY, Wash. — It was simple surgery, done in four minutes from a makeshift operating room floating on the Puyallup River.

Biologist Andrew Berger sliced open a young steelhead and tucked a vitamin-sized transmitter into the folds of its belly.

As a colleague pumped water into the fish's gasping mouth, Berger quickly stitched the wound closed so the 8-inch smolt could continue its journey out to sea.

Berger and other biologists with the Puyallup Tribe of Indians hope the delicate operation on this and dozens of other young fish will yield answers to some pressing questions: Where, exactly, do steelhead go when they leave the rivers that flow to Puget Sound? And why are so many dying?

Steelhead populations around Puget Sound have plummeted dramatically enough that the federal government has proposed listing them for protection under the Endangered Species Act.

Steelhead, which are similar to rainbow trout but spend much of their lives in the ocean and return to rivers to spawn, have such complex life cycles that unraveling the mystery of their decline is difficult.

Wildlife managers suspect the problem may have as much to do with time they spend in Puget Sound or the Pacific Ocean as it does with the health of rivers.

"The ocean is like this black box," said Brodie Antipa, a hatchery manager for the state Department of Fish and Wildlife. "We just don't know what's going on out there. Is it global warming? Is it pollution? Predators?"

Young Puget Sound steelhead will be tracked by receivers placed at intervals along Puget Sound and up the British Columbia coast.

"It used to be that you count your fish when they go out, wait a few years and count them when they got back, and that's all you knew," said Jim Myers with the federal government's Northwest Fisheries Science Center in Seattle.

Scientists in British Columbia have already used receivers to track dozens of fish by computer. They've seen up to 40 percent of them die within a few weeks of leaving Canadian rivers.

"If we could figure out if that's happening here, we'd be way ahead of the game," Myers said.

Even if fish make it to open ocean past the range of the receivers, it may help biologists rule out problems in Puget Sound.

"It won't tell us exactly what's killing them, only whether they are making it from point A to point B," Antipa said.

In some river systems, such as the Puyallup, steelhead declines have become perilous, with spawning steelhead dropping from thousands to hundreds in a half-dozen years. Steelhead spawning nests in one Puyallup tributary numbered about 400 a few years ago. Last year biologists found 32.

This spring, the tribe and state began capturing wild adult steelhead from a fish trap on the White River, a tributary of the Puyallup, and hauling them to a hatchery to rear more young. "People have started to hit panic mode," said Russ Ladley, resource director for the Puyallup Tribe.

The decline in steelhead is happening even in rivers where runs of some salmon, such as wild coho, are returning at the highest levels scientists have seen since record-keeping began more than a half-century ago. Steelhead runs on Olympic Coast rivers appear strong, but pristine river systems in British Columbia are seeing declines.

It's hard to predict how long young steelhead will stay in fresh water before jetting out to the ocean, or how long they will remain in the ocean before returning home to spawn. The entire cycle may take as little as three years, or as many as seven if it happens at all.

Some steelhead can spawn rainbow trout, and vice versa, though scientists aren't sure what triggers the transition.

Steelhead have been known to travel great distances: Some fish that can be traced to Puget Sound have been found a few hundred miles off Japan. In the ocean, steelhead typically stay within 100 feet of the surface, while many salmon species live deeper.

Even when runs are healthy, there are typically far fewer steelhead than salmon in the rivers -- as few as one for every 100 chinook. Yet while steelhead often struggle when competing with other salmon species, strong runs of both coexisted through most of the 20th century.

Source: Associated Press

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