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2010 Juvenile Survival Through Hydro System Near Record Highs by Staff NW Fishletter, April 19, 2011

Federal biologists say added spill and spillway weirs at most federal dams on the Columbia and Snake rivers kept juvenile fish survival high last year, despite the relatively low flows.

The final survival estimates from PIT-tagged fish, fine-tuned from preliminary results reported last September, show that juvenile yearling chinook survival from the Snake River trap to below Bonneville Dam was over 55 percent, higher than the 12-year average of 49 percent and slightly better than 2009's 53 percent.

Juvenile steelhead survival was nearly 62 percent, down from 2009's 68 percent, but much above the 40-percent average survival since 1997.

The feds reported the high steelhead survival the past couple years was "particularly noteworthy." They pointed to a new temporary spillway weir installed at Little Goose Dam on the lower Snake as a probable factor in reducing travel time. Also, a wire array to deter bird predation in the tailrace of John Day Dam may be paying off as well, along with a new spillway wall there that reduces the time young steelhead spend in the tailrace where predators like pikeminnow congregate.

The high spill levels and weirs reduced the numbers of spring chinook smolts (hatchery and wild) transported downstream by barge to only about 30 percent--the second-lowest number since 1993, and 9 percent below 2009 levels. Some years in the early 2000s, more than 90 percent of the spring chinook were barged.

Only about 36 percent of the steelhead (hatchery and wild) were barged in 2010, down from 2009's 44 percent, and the lowest percentage since 1993. As late as 2005, up to 98 percent had been barged, but the court-ordered spring spill program that began in 2006 has reduced the number of steelhead barged. Years of data on adult returns has shown that barged steelhead typically return at twice the rate of inriver migrants.

The report noted that significant fish mortality occurs before hatchery fish even reach the hydro system. Yearling chinook released from Dworshak, the closest facility to Lower Granite Dam (tailrace), showed a 90-percent survival rate, but yearling chinook from McCall Hatchery and released into Johnson Creek had only a 27-percent survival rate.

Only about 15 percent of young sockeye released last spring made it from the Redfish Lake trap to the dam, a distance of about 450 miles. Sockeye released from the Sawtooth trap did a little better, with a 25-percent survival rate. Their survival rate from the railrace of lower Granite Dam to below Bonneville averaged above 54 percent. -B. R.

Related Sites:
2009 FCRPS BiOp Progress Report

Related Pages:
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.

Hi Scott,

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 -

www.fpc.org/documents/memos/146-08.pdf

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