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What If Columbia and Snake River Dams Were Helping Salmon?

Of course no one believes that pushing salmon smolts through a turbine is helping them. But as billions of dollars generated by the dams are invested in structural improvements, fish production, habitat improvements, and control of natural predators, the possibility emerges that all these efforts have generated a river system that, on balance, is more survivable for fish than a natural river system.

Last week, Northwest Fishletter obtained an internal memorandum from the National Marine Fisheries Service summarizing recent studies addressing that question. The memorandum presents estimates of smolt survival in the Columbia and Snake Rivers as compared with the unregulated, unimpounded Fraser River in British Columbia, and the regulated but unimpounded Sacramento River in California.

    · Juvenile survival through the Columbia and Snake Rivers was recently measured at 56% for chinook and 39.2% for steelhead.

    · Juvenile survival through the Fraser River was recently measured at 24% for chinook and 30% for steelhead.

    · Juvenile survival through the Sacramento River was recently measured at 2% for chinook and 5% for steelhead.

So on first appearances, survival down the Columbia and Snake Rivers is higher than in other, roughly comparable rivers without any dams that smolts must pass. This is not really a surprising result for those who follow science rather than public opinion. A leading treatise, Pacific Salmon Life Histories, reported several years ago that roughly 70% of fish die while migrating downstream in all rivers. One interesting feature in this data is that steelhead survival is higher up and down the West Coast except on the Columbia, which may be related to ongoing efforts to spill water at dams; earlier this year excessive spill was poisoning up to 66% of late-migrating juvenile steelhead. Steelhead, being a game fish by statute, seems to get short shrift in a system that seems to be run by commercial harvest interests.

One can certainly quibble with the details. The measurements for the other rivers are taken further downstream. Predator densities are highest below Bonneville Dam, so the Columbia and Snake River numbers above need a downward adjustment—perhaps 10% more mortality, perhaps more. The Sacramento River measurements were in a particularly warm, dry year. One might question effects on adults, though radio-tagging studies suggest that adults move upstream through dams and reservoirs faster than in a natural river.

A more exact analysis could easily show adverse effects from the dams, as compared to a more natural, dam-free river, but those effects would be small, and probably not enough to make much difference at all to adult returns. Here is a recent graph of the relationship between downstream steelhead survival and adult returns:

Juvenile survival through the Columbia and Snake Rivers explains only one percent of the variance in adult returns; the number is higher for chinook.

The NMFS memo is careful to say that the data from other rivers are “preliminary” and “it is not appropriate to imply their meaning regarding policy issues at this time”. But one wonders when it will be time for Northwesterners to wake up and realize that the massive and continuing campaign against the dams is based on very significant misrepresentations. Powerful interests (investor-owned utilities) have earned hundreds of millions of dollars annually from reducing power production at the publicly-owned dams on the Columbia and Snake Rivers. They get to sell the power instead from their own plants. Powerful harvest interests, such as Northwest Tribes and commercial fishing interests from Oregon to Alaska, all distract the public from the largest sources of human-induced mortality: continuing overfishing. Almost no one is left to speak in defense of the dams, as even the organizations ostensibly founded to protect them have lined up in support of the latest draft biological opinion pushing the same old misrepresentations.

Pretending that the dams are killing most of the fish (rather than Mother Nature) saddles us all with billions in increased electric rates, and funnels millions of tons of additional carbon dioxide into the atmosphere annually. Even if fish advocates don’t care about that, they ought to be wondering whether all this focus on dams distracts sportsfishing interests from what is really needed: sensible harvest and hatchery management. Why on earth do we take money from every taxpayer to release hatchery fish that aren’t fin-clipped, so only the Tribes can keep them? Why does a small Northwest minority with rights to “fish in common with all citizens” get to take the vast majority of salmon and steelhead out of the river? Why do sportsfishing interests get thrown off the river with paltry allocations while gillnets continue to decimate salmon and steelhead runs? In large part, it is because sportsfishing interests are distracted with constant fraudulent attacks on dams and landowners that have no reasonable prospect of putting more fish in the river to catch.

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              Page Updated: Thursday May 07, 2009 09:14 AM  Pacific

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