A total of 90 Snake River sockeye salmon spawners have been trapped as of Wednesday in central Idaho as part of the long-running program to boost production of a species that has since 1991 been listed as endangered under the Endangered Species Act and, during that time period, came close to extinction.
That total already registers as the sixth most sockeye returning to Idaho high country since the early 1980s. And there should be plenty more to come, according to Eagle Hatchery manager Dan Baker, who notes the daily sockeye arrivals are on an upward trajectory. The highest daily count so far this year was 11 sockeye trapped on Wednesday.
The sockeye, which is the southernmost population of their species, must swim 900 miles up the Columbia, Snake and Salmon rivers to reach their destination in Idaho’s Stanley basin. Most are the product of a hatchery captive broodstock program begun early in 1991 as an attempt to preserve the genetics of a species about to wink out.
That program has shown dividends in recent years, with returns as high as 1,355 in 2010.
Between 1991 and 1998, only 16 wild sockeye salmon returned to Idaho. All of these adults were incorporated into the captive breeding program and spawned at the Eagle Fish Hatchery.
The program releases eggs and fish back to the habitat in a variety of ways. Eyed-eggs are planted in egg boxes and placed in lakes in the fall, presmolts are released directly to lakes in the fall, smolts are released to outlet streams in the spring, and prespawn adults are released to lakes in the fall. A monitoring and evaluation effort is in place to document the success of the different reintroduction strategies.
The smolt releases have far and away produced the best results so the Idaho Department of Fish and Game has, largely with money provided by the Bonneville Power Administration, rebuilt a hatchery in eastern Idaho that will provide the capacity to increase the production of smolts from about 200,000 to more than 1 million. That hatchery is scheduled to begin operations next month.
Between 1999 and 2010, 3,193 mostly hatchery-produced adult, sockeye salmon returned to the Sawtooth Valley. For comparison, in the 14 years from 1985 through 1998, 77 natural-origin sockeye salmon returned to Idaho.
The percentage of naturally produced returns has increased in recent years. This year, it is estimated that 26 of the 90 returns to-date are of natural origin – either from fertilized eggs outplanted in the basin’s Pettit Lake, from resident sockeye that have spent their entire life cycle in freshwater, or from adult fish (either returns from the Pacific or fish raised within the hatchery system) that had earlier been released into Redfish Lake and allowed to spawn naturally.
Though the sockeye originally spawned and reared in as many as five central Idaho lakes, the captive broodstock program thus far has focused its sockeye recovery efforts on Redfish Lake. So far this year 85 of the 90 returning spawners have been captured at a weir spanning Redfish Lake Creek, which flows downstream from the lake to the Salmon River. The other five fish were trapped at nearby Sawtooth Hatchery. The captured fish are transported more than 100 miles to Eagle Hatchery, where they are kept until spawning time nears. In September a share of the returned adult fish will be released into Redfish Lake, along with sockeye reared to adulthood at Eagle and elsewhere.
Meanwhile, fisheries managers are playing a waiting game. Sockeye are counted as they pass over the fish ladders at southeast Washington’s Lower Granite Dam on the lower Snake River. Through Wednesday 731 fish had passed the dam, which is the fifth highest total since construction of the hydro project was completed in 1975. The sockeye run appears to have peaked in early August, with counts in recent days falling into the single digits.
The fish still have about 400 miles to swim after reaching Lower Granite, which is the eighth and final dam they must pass on their way up the Columbia and Snake rivers. They turn into the Salmon River upstream of Lower Granite.
It takes two weeks or more the fish to swim from Lower Granite to the Stanley basin. In a good year the survival rate over that stretch run can be 60-70 percent. In years like this with relatively low flows and warmer than average water temperatures that conversion rate – survival from lower Granite to the Stanley basin – can be lower, Baker said.
The program is a cooperative effort with the IDFG developing and maintaining captive broodstocks and conducting field monitoring and evaluations such as investigating the success of outplanted groups. The IDFG also provides genetics monitoring and support for the program such as background genetic identity analysis and development of spawning designs.
NOAA Fisheries Service, which is responsible for assuring listed anadromous fish species are protected, shares captive broodstock fish culture responsibilities at two facilities located in Washington state. The Oregon Department of Fish and Wildlife provides smolt rearing for the program.
Also involved are the University of Idaho, which provides genetic support for the program, and the Shoshone-Bannock Tribes, which conduct habitat investigations geared toward determining the ability of nursery lakes to receive eggs and fish from the program and evaluates lake fertilization.
BPA as part of its obligation under federal treaties and the ESA and Northwest Power Act provides funding and technical administration and oversight. Bonneville markets power generated in the Columbia-Snake river hydro system.
In the 1880s, observers reported lakes and streams in the Stanley Basin teeming with “redfish” -- sockeye. Returns were estimated between 25,000 and 35,000 sockeye.
Construction of the Sunbeam Dam on the Salmon River in 1913 blocked upstream fish passage. The dam was partially destroyed in 1934, which reopened the upper Salmon River to fish passage. But, the IDFG says, no one immediately tried to restore the salmon runs. The source of the present sockeye in Redfish Lake, which has fueled the captive broodstock program, is uncertain.