Report Gives Snake River Salmon 6 to 32 Yearsby Lisa Stiffler
Seattle Post-Intelligencer - April 25, 2001
Extinction coming soonest to weakest of the populations, Trout Unlimited says
The clock is ticking for Snake River spring and summer chinook salmon. The weakest populations of a run that historically numbered 1.5 million could essentially be extinct in six years, according to a study being released today by the conservation group Trout Unlimited.
The study examined seven populations of salmon that migrate up the Columbia and Snake rivers to spawn in Eastern Washington and Idaho. Depending on their destination, the fish travel nearly 1,000 miles and must get past eight hydroelectric dams to reach their spawning streams.
The report's co-author, Gretchen Oosterhout, predicts that unless habitat conditions change, the weaker salmon populations could become extinct as early as 2007. The stronger ones, she believes, would be doomed by 2033, with 2016 as an average year of demise. "We're in a declining trend," agreed Charlie Petrosky, a fishery biologist with the Idaho Department of Fish and Game.
But scientists don't agree on the prognosis for the fish. They say populations are difficult to predict and they disagree over which factors are important -- and even how to define extinction.
Today's report is the second study of its kind funded by Trout Unlimited since 1999. The latest conclusions are more pessimistic. They incorporate additional data and account for natural variability of salmon runs.
Mike Schiewe, director of the fish ecology division of the National Marine Fisheries Service's Northwest Fisheries Science Center, disagreed even with the more hopeful 1999 model. The risk to Snake River spring and summer chinook is not as dire as portrayed, he said.
The Trout Unlimited report predicts "functional extinction," defined as 100 or fewer salmon returning to spawn over a period of five years. Analyses by the NMFS, by contrast, define extinction as one or no salmon returning to spawn over five years.
That's too extreme, Oosterhout said, arguing that 100 fish is already conservative.
Extinction happens "before the last animal dies," said Oosterhout, who owns Decision Matrix, Inc., an Oregon-based company that does analysis and risk assessment. "Policy-makers need to know at what point the salmon are doomed."Since the 1950s, the Snake River salmon populations have fluctuated sharply, but over the years, the peaks have gotten get lower and the valleys dipped closer to zero.
In the late 1950s and in the 1960s, the number of returning wild Snake River spring and summer chinook fluctuated between 6,000 and 7,000, although one year it spiked to nearly 14,000. By the 1980s, the population was down to around 2,000 salmon. In 1995, there was a dismal return of 193 fish. But the numbers have increased, with nearly 1,600 wild and hatchery fish returning last year.
Scientists are largely attributing the recent increase to improved ocean conditions. It is unclear if the favorable conditions will continue.
But it is certain that the energy shortage and drought will reduce salmon numbers.
This summer, power producers will not be required to spill water over the dams if river levels drop, Schiewe said, because of the pressing demand for electricity. That will harm returning adults struggling through shallow passages. And fish that normally had a free ride out to sea on quickly flowing water will spend more time and effort migrating downstream.
"It's a double whammy," Schiewe said.
As in the past, some fish will be barged out to the ocean, but transporting them has an unmeasured, lethal effect.
Oosterhout hopes policy-makers appreciate the Snake River salmon's desperate straits and take appropriate action. To those critical of her analysis, which has not been published in a peer-reviewed scientific journal, Oosterhout says population graphs sliding toward zero tell the story.
"You didn't need a model at this point to see what state we're in."
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