Dam Passage and Spill
Protected young Snake River steelhead migrated safely through US federal dams on the Columbia and Snake rivers to the ocean last year at the second-highest rate on record, according to newly released research. About 21% more steelhead passed safely through the dams in 2010 compared to the average since the late 1990s.
Young chinook and sockeye salmon also made it safely through the eight federal dams at higher-than-average rates, NOAA's Northwest Fisheries Science Center found.
Researchers said the higher survival rates likely reflected two factors: the spill of water to help carry young fish past dams and recently installed surface passage systems that let fish slide through spillways near the water's surface, where they naturally migrate.
Spill and surface passage are both central components of the federal biological opinion that outlines measures to protect Columbia and Snake river fish listed under the federal Endangered Species Act. The biological opinion calls for spill at all eight federal dams on the Columbia and Snake rivers through the end of the active juvenile salmon migration in August.
The US Army Corps of Engineers has also installed surface passage systems at all eight federal dams on the Columbia and Snake rivers in the last decade. Electric ratepayers fund most of the improvements through the Bonneville Power Administration.
NOAA research indicated that the surface passage systems, such as a new temporary spillway weir - also called a fish slide - at Little Goose Dam, helped speed young fish downstream by moving surface water more quickly through spillways. Faster travel downriver increases survival by reducing the exposure of young fish to predators and higher water temperatures, NOAA's report said.
About 35% of fish were transported downstream by barge, fewer than in almost all previous years since 1995.
NOAA's report also indicated that new aerial wires to reduce bird predation below John Day Dam and completion of a spill wall to guide fish away from predators at The Dalles Dam aids fish survival through the final three Columbia River dams - John Day, The Dalles and Bonneville. About 95% or more yearling salmon and steelhead passed safely through each of the three dams.
2009 FCRPS BiOp Progress Report
Study Shows Dam Improvements Help Fish by Staff, The News Tribune, 12/23/10
12/23/2010 josephbb comments at the News Tribune:
There are multiple problems with this "study" and its findings. First of all, dam passage (are fish alive before the dam? are they alive after the dam?) is an intentionally narrow question and analysis. A comprehensive analysis tells a much darker story. For Snake River salmon, there are 8 dams that juvenile 3-5 inch fish must pass to arrive at the ocean. Does the study account for cumulative effects? Does it merely track salmon passage through each individual dam, and then start anew at the next dam? To give a real and unvarnished picture of salmon survival, it needs to track salmon and their survival from the first dam to the eighth. There is significant loss of salmon that is not detected in this one-dam-at-a-time analysis. Dam passage is stressful and salmon may (and do) die in large numbers (10-15% per dam and reservoir) on their way through the reservoir en route to the next dam. Or after arriving in the estuary. Eight dams and reservoirs MAY pass fish alive to the ocean, but so stressed or injured that they die soon after. And dam passage does nothing to address the problems of the reservoirs themselves - the warm currentless water, the predators (pike minnows for example) that thrive in these still waters.
If dam passage were all that mattered, why does the current federal salmon plan (2010 Obama Administration Salmon Plan) seek legal permission/protection to kill up to 90% of the Snake River fish as they migrate to ocean? The fact is, the feds have been passing salmon through the dams at or near these levels for the last decade; nonetheless, threatened and endangered stocks are not recovering. Fisheries managers recently estimated that spring and summer chinook are expected to return to the Columbia and Snake Rivers in 2011 at roughly the same levels that they have been over the last ten years. Bumping along at the bottom, at continued risk of extinction, is not recovery, nor "trending toward recovery."
And it leaves fishermen and fishing communities in the NW, in Idaho, and across the Pacific Coast struggling to survive. Salmon means business and economic development, but the Obama Administration, like Bush before, keep muffing the job.
From your email I couldn't tell if you had gotten our memo to you responding to your questions that we sent last September. If not, the link is below -
In the memo we noted that none of the studies we reviewed included an adult survival component. "While juvenile survival may have improved at this project, it is unknown if this specific operation has had an effect on survival to adulthood since no specific studies have been conducted." So you are correct that there is no adult return evidence.
I also have attached the final report from the 2007 studies that were conducted at Little Goose Dam in case you didn't already have it.
Let me know if this helps -
Margaret J. Filardo, Ph.D.
Fish Passage Center
1827 NE 44th Ave Suite 240
Portland, OR 97213
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