Salmon study under fire for minimizing effect of dams
A new study says river dams make no difference to salmon survival, but a number of scientists — including several co-authors of the study — are questioning the results and cautioning about what conclusions can really be drawn.
Seattle Times environment reporter
It's a startling finding with potentially big political implications: Young salmon running the gantlet of dams on the Snake and Columbia rivers fared just as well as salmon on an undammed river.
The dams, after all, are widely considered a chief culprit in the decline of endangered salmon in the West's biggest river. Hundreds of millions of dollars have been spent trying to make dams more fish-friendly, and environmentalists have poured out their wrath about the concrete walls.
The online scientific journal PLoS Biology, which released the study today, jumped on the apparent contradiction with a news release trumpeting that "Dams make no damn difference to salmon survival."
But even before the digital ink is dry, a number of scientists — including several co-authors of the study — are questioning the results and cautioning about what conclusions can really be drawn. There have even been charges that it's little more than a promotion for fish-tracking technology in which the lead author has a financial stake.
"There's a huge mass of scientific literature that documents the impacts of dams. It's just huge," said Michele DeHart, manager of the Fish Passage Center, a government-funded agency that tracks and studies Columbia River fish. "It's like saying, 'Gosh, I just did this comparison and smoking does not cause cancer.' Would you change your mind?"
The study's lead author defends the report, saying it suggests that dams might not play such a big role today in the fate of endangered Columbia River salmon, and that conditions in the ocean are more important. But he warned against overstating what the study proves.
"We're not saying that the dams have never had an effect," said David Welch, the lead author and founder of Kintama Research, a British Columbia company that helps develop technology to track salmon using sound waves. "What we all have to ask ourselves is, if survival is up to the level of a river that doesn't have dams, then what's causing survival problems?"
After Welch learned of the "no damn difference" headline, PLoS Biology rescinded its news release this afternoon and issued a new one without the headline.
The study has already become a political football tossed around by groups that have fought over the dams for years.
"I think it really does beg the question for those special interests that keep calling for removal of the federal dams," said Terry Flores, executive director of Northwest RiverPartners, a coalition of electric utilities and industries.
Environmental groups shot back that looking at the two rivers is like comparing apples and oranges.
"Even the Bush administration has acknowledged that Columbia-Snake river dams are a major mortality factor for Columbia Basin salmon," said Michael Garrity of American Rivers.
Welch's study compares survival of young, ocean-bound salmon and steelhead, called smolts, in the heavily-dammed Columbia and Snake rivers, versus the undammed Fraser River in British Columbia.
Using fish outfitted with transceivers, scientists tracked how quickly the fish made it to the ocean and how many survived the trip. They found the Fraser River fish, on average, fared roughly the same as the Columbia River fish — approximately 25 percent survived. When the longer trip for the Columbia River fish was accounted for, those fish actually did better, Welch said.
That surprised even him.
"Everybody thought we would have lower survival in the Columbia,"he said. "And in fact we haven't."
But several of his co-authors warned that the similar survival rates don't mean anything about the effect of dams.
If both rivers have serious problems for salmon, that doesn't mean either one is doing well, said co-author Carl Schreck, head of the Oregon Cooperative Fish and Wildlife Research Unit at Oregon State University. The study also could have missed fish that die in the ocean from the stress of passing through the dams.
He and colleague Shaun Clements said they stayed involved in the study partly to make sure the findings weren't overstated.
For example, "a focus on the dams having been solved. We don't believe that's the case," Schreck said.
Ed Bowles, a biologist and head of fisheries for the Oregon Department of Fish and Wildlife, said the smolt survival rates for the Fraser River found in the study were low enough to raise questions about the accuracy of the study or the health of the river.
"It basically says these fish are headed for extinction very quickly. That doesn't make sense," he said.
Bowles said a more useful comparison would be how similar fish — such as spring chinook — do when they spawn in the same river, some above dams and others below dams. A 2007 study found fish passing through more Columbia and Snake river dams had overall survival rates one-third to one-quarter those of fish going through fewer dams.
DeHart said she saw little in the study of substance beyond the finding of similar survival rates.
"The rest is just an advertisement for David Welch's POST acoustic tag study," she said.
Welch is president of Kintama, a company he founded in 2000 that helps design and manage networks of receivers that can pick up signals from tagged salmon even a long distance away — known as the Pacific Ocean Shelf Tracking project. The technology enables scientists to track the movement of salmon and other animals in the ocean and undammed rivers, something nearly impossible to do with earlier technology.
Welch said the new study does prove the value of the technology and that its expanded use could help answer further questions, like what's happening to fish in the Fraser River. But he said they were simply reporting the results, not trying to skew them.
"What we're starting to see ... is that what all of us had as comfortable assumptions in the past aren't necessarily true when we start doing the measurements," he said.
Welch said the paper does include warnings that the Fraser could have problems, and that Columbia River dams in earlier decades did take a big toll. But he said management of those dams has improved significantly in recent years.
John Ferguson, who oversees fish ecology research at the federal Northwest Fisheries Science Center, said the results provide some encouragement that efforts to make dams more fish-friendly are working.
"The fact that the Fraser and Columbia are comparable kind of makes sense," said Ferguson, who specializes in how to get young salmon safely through dams. "It's not because the Columbia River is so bad now. It's because it's way better than it was."
Warren Cornwall: 206-464-2311 or email@example.com
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