A record number of fall chinook were counted at Lower Granite Dam on the lower Snake River in 2010, and a record number of them built egg nests or redds in the gravels of such places as Alpowa and Asotin creeks and the Grande Ronde and Imnaha rivers.
Almost every place where fall chinook redds were counted produced a record, and the spawners are spreading out, breaking new spawning ground.
The annual redd surveys were conducted by biologists from the Idaho Power Company, Nez Perce Tribe, U.S. Fish and Wildlife Service and the Washington Department of Fish and Wildlife. It was the 23rd year that intensive aerial surveys have been conducted in the Snake River and most of its major tributaries above Lower Granite and the 19th year for ground surveys in tributaries downstream of the southeast Washington dam.
The redd total was 5,626, which was 1,910 more than the previous record set in 2009.
The fall chinook count at Lower Granite, the eighth and final hydro project the fish must pass on their spawning journey, rose to 41,815. The previous high was 16,628 in 2008.
The rebounding stock was listed as threatened under the Endangered Species Act in 1992 and includes naturally produced fish from the Snake, Tucannon, Grande Ronde, Imnaha, Salmon and Clearwater rivers and tributaries, as well as 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.
Much of the upswing is due to the fall chinook acclimation project led by the Nez Perce Tribe that began in 1996. The program involves bringing hatchery produced juvenile fish to "acclimation" sites on the lower Snake and the Clearwater River -- for their final rearing before release. The sites are located near major natural spawning areas.
The 2010 return to the Columbia Basin also got a boost from estimated to be good ocean conditions during their saltwater sojourn when climate conditions combined to create cold water and adequate food.
Efforts over the past two decades have aimed at improving freshwater habitat, along with mechanical and operational improvements at the dams.
Ground surveyors, on a tip that spawning had been witnessed, returned to Alpowa Creek, which enters the Snake a short distance downstream from Clarkston, Wash. The stream, which had not been surveyed in recent years, held a total of 31 redds.
WDFW staff in 1988-1991 walked the lower 1.5 miles of the creek but neither fish nor redds were observed so surveys ceased until 2010, according to the Jan. 31, 2011 “2010 Snake River Fall Chinook Salmon Spawning Summary” prepared by the NPT, USFWS, IPC, WDFW and Pacific Northwest National Laboratory.
In the Grande Ronde River, which streams from Oregon and across the southeastern corner of Washington, redds were seen in new spawning areas and totaled 50 distinct locations, according to the survey summary. No redds were observed in the Wallowa and Wenaha rivers, which feed into the Grande Ronde.
Natural production there and elsewhere have literally been resurrected over the past few decades with particular growth in recent years. Since 2003, the mean number of redds occurring in the Grande Ronde River Subbasin has been 132, ranging from 41 to 263. The lowest redd count for the Grande Ronde River, since intensive surveys began, was zero in 1989 and 1991, while the highest count was 263 in 2010.
A total of 132 redds were found last year in Oregon’s Imnaha River. Since 2003, the mean number of redds occurring in the Imnaha River has been 50, ranging from 17 to 132. The lowest redd count for the Imnaha River, since intensive surveys began was zero redds in 1994, while the highest count was 132 in 2010.
On the other side of the Snake, a total of 1,924 redds were counted in the Clearwater with most of them, 1,632 found in the lower river mainstem. Another 281 were found in the Potlatch.
The tribe’s surveyors said they continue to find new spawning locations throughout the Clearwater subbasin. The mean number of redds occurring in the subbasin since 2003 is 874. The lowest count since the surveys began was only four redds in 1990 and 1991.
A record total of 2,944 redds were found during ground, aerial and underwater video counts by IPC and USFS staff in the mainstem Snake River, from the face of Hells Canyon Dam 100 miles downriver.
“Visibility during aerial surveys was poor to good throughout the season. Poor weather conditions (strong winds and heavy snowfall) in both the lower and upper river section caused us to either postpone or abort surveys early on 25 October and 23 November (at RM 228, and 237, respectively),” the summary says. “However, good counts were still obtained by the end of the season. Additionally, 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.”
“For 2010 the total redd count for the Snake River was 2,944. Since 2002, the mean number of redds occurring in the Snake River (including deep water counts) has been 1,643, ranging between 1,025 and 2,944. The lowest redd count for the Snake River, since intensive surveys began, was 46 redds in 1991, while the highest count was 2,944 redds in 2010.”