A total of 8,097 naturally produced Snake River adult fall chinook salmon in 2011 made their way back from the Pacific and up through eight Columbia and Snake river hydro projects, according preliminary estimates produced by federal, state and tribal fishery experts.
Such a return would mark only the third time since at least 1985 that so-called “wild” fall chinook escapement above the lower Snake River’s Lower Granite Dam has surpassed 4,000, according data compiled by the 2011 Joint Staff Report prepared by the Oregon and Washington departments of fish and wildlife.
The naturally produced fish are fall chinook either of wild origin or are the progeny of hatchery fish that were acclimated as juveniles at various streamside sites and later returned as adults to spawn. The wild fish, listed as threatened, are protected under Endangered Species Act.
The record was a count of 9,583 in 2010. Third- place is now held by the 2001 return, which was estimated to number 5,083 naturally produced adult fall chinook salmon. No other annual estimate was more than 4,000, according to Joint Staff Report.
The estimates are developed through a collaborative effort that includes representatives from Nez Perce Tribe, WDFW, Idaho Power Company, NOAA Fisheries Service, Columbia River Inter-Tribal Fish Commission and Idaho Department of Fish and Game.
The estimates are for returns to Lower Granite Dam and as such they do not represent total return to the Snake River, according to Jay Hesse, director of research for the Nez Perce Tribe’s Department of Fisheries Resources Management.
Some of the fall chinook that turn off from the Columbia return directly to Lyons Ferry Hatchery, which is located between Lower Monumental and Little Goose dams, the second and third dams the fish encounter after turning into the Snake. Lower Granite is the fourth.
Some fish also make their way into southeast Washington’s Tucannon River, which empties into the Lower Monumental pool, to spawn. And some fish stay in the mainstem to spawn below dams downriver of Lower Granite.
Neither do the estimates represent fish available to spawn upstream of Lower Granite Dam, as some fish are collected at Lower Granite Dam for Lyons Ferry Hatchery and Nez Perce Tribal Hatchery broodstock. In addition, fish are collected at Nez Perce Tribal Hatchery for broodstock and some are harvested upstream of Lower Granite Dam in tribal and recreational fisheries. The Nez Perce Hatchery is located on the Clearwater River, which pours into the Snake above Lower Granite’s reservoir, in west-central Idaho.
The 2011 breakdown of Lower Granite Dam escapement includes a total wild-natural count of 8,097 adults (3,550 females and 4,548 males) and 4,239 early maturing jacks who spent only one year in the ocean before returning to spawn. The adults spent two or more years in the Pacific.
The 2011 escapement estimates include 11,098 adult hatchery males and 8,525 females. An estimated 11,101 hatchery jacks made it as far as Lower Granite.
The total 2011 escapement estimate is 27,720 adult fall chinook. That’s the second highest total on a record dating back to 1975 when counts began at the newly completed Lower Granite Dam. The high count at Lower Granite was 41,815 in 2010, according to data compiled by the Fish Passage Center.
Naturally produced fish made up 24 percent of the total 2011 escapement compared to 29 percent in 2010.
The work group that produces the hatchery vs. wild estimates applied new analytical methods in 2010 and 2011 so comparisons with past years are not yet ripe.
“We are in the process of applying 2010 and 2011 methods to earlier years to make sure results are not altered by method,” Hesse said. “So we are putting off analysis of trends until that retrospective application of current methods is complete.”
A portion of the overall run, usually about 10 percent, are trapped at Lower Granite to be evaluated and sampled with certain percentages of wild and hatchery fish transported to the hatcheries for use as broodstock.
Using the previous method over the previous seven years a range of from 9.5 (2009) to 33.5 (2006) percent of returns, as counted at Lower Granite, have been naturally produced. The preseason forecast was for a return of 5,300 wild Snake River fall chinook to the mouth of the Columbia River.
Of the overall escapement to Lower Granite, 23 percent of the fall chinook were jacks in 2011, as compared to 35 percent in 2010.
For more on adult fall chinook returns to the Lower Snake see CBB, Feb. 10, 2011, “2011 Fall Chinook Redd Survey In Lower Snake, Tributaries Produces Second Highest Count On Record” http://www.cbbulletin.com/416425.aspx