2013 Fall Chinook Redd Counts in Lower Snake River
A total of 6,391 fall chinook salmon redds (scoured out nests in river bottom gravels) were estimated to have been built in the lower Snake River basin in 2013, representing the highest estimate since intensive surveys began in 1988.
The year's estimate showed 761 more redds than the previous high estimate of 5,630 redds in 2010.
"It just keeps going up and up," the Nez Perce Tribe's Bill Arnsberg said of redd counts that have risen from a low of only 45 in 1990, including 37 in the lower Snake River upstream of Lower Granite Dam, one in the Grande Ronde River, three in the Imnaha River and four in the Clearwater River.
In 1990 a total of only 384 adult fall chinook were counted climbing over fish ladders at Lower Granite, which is the eighth dam the spawners pass on their way up through the Columbia/Snake river system. Lower Granite is located 107.5 miles upstream from the Snake's southeast Washington confluence with the Columbia. Salmon passage on the Snake is blocked 140 river miles upstream of Lower Granite at Hells Canyon Dam. Three dams were built in Hells Canyon in the 1950s and 1960s that prevented access of historic spawning grounds in the upper Snake.
With populations at low ebbs, Snake River fall chinook salmon, as well as Snake River spring/summer chinook salmon, were listed in April 1992 under the federal Endangered Species Act as threatened.
Before and since the listings, a number of actions have been implemented in an attempt to improve the survival of fall and spring/summer chinook headed for the lower Snake and tributaries such as the Clearwater, Salmon, Imnaha, Grande Ronde, Wallowa, Wenaha and Tucannon rivers and Asotin and Alpowa creeks. Hydro operations have been tailored to better accommodate upstream and downstream passage, habitat improvements have been implemented, harvests have been limited, and hatchery operations have in some cases been used to help boost the number of fish that return and spawn in the wild.
The Nez Perce Tribe has led that hatchery effort with its "supplementation" program, which outplants juvenile hatchery fish near historic spawning grounds so those fish come back to those areas to begin a new family tradition of natural reproduction.
The overall count of adult fall chinook passing over Lower Granite in 2013 was also at an all-time high (since the dam was built in 1975) at 56,565. That was nearly 15,000 thousand higher than the previous high, 41,815 in 2010. And future returns should be strong as well. A total of 22,395 jacks -- young fish that return after one year in the ocean -- were counted last year at Lower Granite in 2013. That was the second high count on record compared to 41,249 in 2009. A total of 21,990 jacks were counted in 2012. The jacks signal the strength of future returns since their broodmates return as 3 and 4 year olds.
Federal, state and tribal fishery officials have yet to finalize their forecast for the 2014 Snake River fall chinook return, but most expect it should be "pretty similar" to the 2013 return, said Stuart Ellis of the Columbia River Inter-Tribal Fishery Commission, an entity that provides technical-biological and legal support for the Nez Perce, Umatilla, Warm Springs and Yakama tribes.
Ellis said that, again a preliminary calculation, the 2013 return included a record total of about 21,000 natural origin fish.
The 2013 Snake River fall chinook salmon redd surveys were conducted cooperatively by biologists from the Idaho Power Company, Nez Perce Tribe, U.S. Fish and Wildlife Service, Washington Department of Fish and Wildlife and Normandeau Associates, Inc. The summary report on those efforts can be found at: www.fpc.org/documents/fachin_planningteam/2013CooperativeFallChReddSummary.pdf
This was the 26th year that intensive, cooperative aerial surveys have been conducted in the Snake River and most major tributaries above Lower Granite Dam and the 22nd year for ground surveys in tributaries downstream of Lower Granite Dam. The area immediate below Lower Granite Dam was the only lower Snake River dam surveyed in 2013.
During aerial, ground, and underwater video counts, IPC and USFWS staff observed a total of 2,667 redds in the mainstem Snake River, according to a survey summary report. During the most recent five years (2009-2013), the mean number of redds occurring in the Snake River (including those found in deep water) has been 2,474, ranging between 1,828 and 2,944. The highest redd count for the Snake River, since intensive, cooperative surveys began, was 2,944 redds in 2010.
During aerial surveys, NPT staff counted a total of 2,956 redds in the Clearwater River subbasin. Redd searches covered the entire Clearwater River from the Clearwater Paper Mill in Lewiston, Idaho to the forks of the South Fork and Middle Fork Clearwater rivers (71 miles), lower Potlatch River (5 miles), about one half mile of the lower North Fork Clearwater River below Dworshak Dam, the entire Middle Fork Clearwater River (22 miles), lower South Fork Clearwater River (14 miles), and lower Selway River (19 miles).
"Not many redds were thought to have been missed in the Clearwater River Subbasin this year, except maybe some deep water redds," the summary report says. "For example, in a deep water (> 15 ft) run just below Big Eddy, we observed 55 new redds in the last survey on 25 November. These redds were most likely constructed earlier and were not visible during the previous surveys with slightly less water transparency. This was also an area where we had never recorded redds in the mainstem during previous years."
Arnsberg said tribal officials expected "a few more redds to be counted" given the high passage at Lower Granite. On average only one redd per eight adult fish were counted this year as compared to one redd per 5-6 fish in past years.
Since 2009, the mean number of redds occurring in the Clearwater River subbasin has been 1,872 ranging between 1,185 and 2,956. The lowest redd count for the Clearwater River subbasin, since intensive surveys began was four redds in both 1990 and 1991, while the highest count was last year's total.
A total of three aerial surveys conducted by NPT staff on the Grande Ronde River resulted in a total of 255 redds observed in 2013. The lowest redd count for the Grande Ronde Subbasin since intensive surveys began, was zero in 1989 and 1991, while the highest count was 313 in 2012.
The summary report data is considered preliminary. Final results will be provided in annual reports to Bonneville Power Administration. Past reports can be found at www.bpa.gov. Final report by Normandeau Associates, Inc. will be provided to the U.S. Army Corps of Engineers, Walla Walla District. Past reports on fall chinook salmon spawning areas downstream of Lower Snake River dams can also be obtained through the Corps Walla Walla District.
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