Intensive Surveys Tracking Snake River Fall Chinook Redds,
An air, ground and underwater effort this past fall produced the third largest count yet of fall chinook salmon redds (nests) in what is a 25-year record of intensive surveys conducted in the Snake River drainage and most tributaries above Lower Granite Dam and downstream of the Hells Canyon Complex.
The 4,795 estimated redds ranked only behind the previous two years. The 2012 total was 215 redds less than the second highest estimate 2011 and 835 redds less than the record estimate in 2010.
A preliminary survey summary report can be found at: www.fpc.org
The fall chinook red surveys were conducted cooperatively by biologists from the Idaho Power Company, Nez Perce Tribe, U.S. Fish and Wildlife Service and Washington Department of Fish and Wildlife. They involve manned aerial surveys, and on the grounds checks of stream reaches. Also employed were ground checks, as well as the use underwater cameras to plumb the depths.
For the second year in a row drones, equipped with digital cameras, were also used.
Idaho's Clearwater River drainage was the top performer with an estimated count of 1,958 redds in 2012, its highest since the surveys began.
Like in most of the Snake River basin, the Clearwater adult salmon returns have risen from the depths. Only four redds were found in 1990 and 1991. Having reached a low point, the Snake River fall chinook stock was listed under the Endangered Species Act in 1992.
The mainstem Clearwater River final estimate was an extrapolation, since no air or ground counts could be conducted after Nov. 8 due to persistent rains and turbid water. A total of 1,118 redds had been counted by that date. To estimate redds missed on the Clearwater, biologists averaged the previous five years counts up to Nov. 8, and calculated what percentage of the overall total of redds counted to that date, then applied that percentage to 1,118 to get an estimate of 1,610 redds, or 492 redds missed.
"We believe this is a conservative estimate since conditions were only ‘good' on 8 November and redds in deep water spawning areas were difficult or impossible to see," according to researchers preliminary report, "2012 Snake River Fall Chinook Salmon Spawning Summary."
The Clearwater flows into the Snake just upstream of the head of Lower Granite's reservoir.
One of the promising tributaries to the Clearwater contributed to the record with a record of its own. A total of 283 redds were counted in the Potlatch River in 2012. That was two more than the previous high, recorded in 2010. Likewise the researchers feel that some Potlatch redds might have been missed because of poor weather and river viewing conditions.
"… the Potlatch River, they really pulled in there last year," said Bill Arnsbert, project leader for the Nez Perce Tribe.
"Every year, we continue to observe redds in new spawning locations throughout the Clearwater Subbasin," the report says. "During 2012, we observed redds in areas on the S.F. Clearwater, M.F. Clearwater, and the Selway rivers where no redds had been previously recorded."
The count for the South Fork was 41 redds, the third highest total in the Clearwater basin, though a small fraction of the mainstem total. With their number growing considerably in recent years, the fall chinook seemed to be spreading out to some degree to take advantage of available habitat.
"We're seeing something different because they're going into smaller rivers," Arnsberg said. Fall chinook had traditionally been described as mainstem spawners.
Since 2008, the mean number of redds occurring in the Clearwater River subbasin has been 1,533, ranging between 965 and 1,958.
The number of returning spawners has been growing since that 1992 listing because of a variety of remedial actions and, in some years, help from favorable river and ocean conditions. Measures have been taken to improve habitat conditions for juvenile and adult salmon and to ease their passage up and down through the Columbia-Snake hydro system. Lower Granite is the eighth dam the fish must past on their way to spawning grounds and hatcheries. Harvests are also monitored carefully.
Hatchery input also is credited with helping boost abundance. A fall chinook "supplementation" project led by the Nez Perce Tribe began in 1996. The program involves bringing hatchery produced juvenile fish to acclimation sites on the lower Snake and Clearwater rivers for their final rearing before release. The sites are located near major natural spawning areas in hope that the fish would return as adults to spawn.
The overall return over Lower Granite also includes hatchery fish too that are outplanted each year by IPC below Hells Canyon Dam.
"To see those kind of numbers is pretty cool," said Phil Groves, a IPC biologist who has been in the Snake River fall chinook restoration since 1991 when small handfuls of spawners returned.
The 2012 fall chinook count (34,687 adult fish) at Lower Granite, which includes both hatchery and wild fish, was the second highest on a record dating back to 1975. The highest was 41,815 in 2010.
The return includes naturally produced fish from the Snake, Tucannon, Grande Ronde, Imnaha, Salmon and Clearwater rivers and tributaries, as well as fish from four artificial propagation programs: the Lyons Ferry Hatchery, Fall Chinook Acclimation Ponds Program in the Clearwater and lower Snake, the Nez Perce Tribal Hatchery, and Oxbow Hatchery fall-run chinook hatchery programs.
During aerial, ground, and underwater video counts, IPC and USFWS staff observed a total of 1,828 redds in the mainstem Snake River. Since 2008, the mean number of redds occurring in the Snake River (including deep water counts) has been 2,300, ranging between 1,819 and 2,944. The lowest redd count for the Snake River, since intensive, cooperative surveys began, was 46 redds in 1991, while the highest count was 2,944 redds in 2010.
Intensive deepwater spawning searches were conducted throughout the main river corridor, using remote underwater video cameras, in areas too deep to be viewed from the air.
Like elsewhere in the basin, poor weather and river conditions hampered survey efforts.
"We expected to see quite a few more redds" in the lower Snake mainstem, Groves said.
Another of the top Snake tributary counts in 2012 was a record total of 541 in southeast Washington's Tucannon River. Since 2008, the mean number of redds in the Tucannon was 334, ranging from 252 to 541. The lowest redd count for the Tucannon River on record was 16 redds in 1987.
The Grande Ronde had a record fall chinook redd count last year, 313. Since 2008 the mean number of redds found in the Grande Ronde has been 203, ranging from 101 to 313. The Grande Ronde flows out of northeast Oregon and across the southeast corner of Washington before entering the Snake.
The Imnaha River, which flows out of Oregon and into the Snake at the Idaho border, had 85 observed redds counts in that lower 19 miles of the Imnaha and since 2008 have ranged from 24 to 132. The low count since the surveys began was zero in 1994.
Final results will be provided in annual reports to Bonneville Power Administration. Past reports can be found at www.bpa.gov
learn more on topics covered in the film
see the video
read the script
learn the songs