September 30, 2021
So far just 42 sockeye salmon this year have completed the 900-mile swim through eight dams from the Pacific Ocean to Idaho’s Sawtooth Basin, an even lower return of the endangered fish to the basin than in 2015 when warm water in the Columbia and Snake rivers killed 90 percent of the run before they arrived at Ice Harbor Dam.
Still, according to the Idaho Department of Fish and Game, 2,750 sockeye are available to spawn in Redfish and Pettit lakes, or to be artificially spawned in hatcheries. Where did they come from?
In addition to the 42 sockeye trapped at Redfish Lake, some 201 sockeye were trapped at Lower Granite Dam on the Snake River and transported to IDFG’s Eagle Fish Hatchery near Boise (16 were identified as upper Columbia River sockeye and culled, leaving 185 Redfish Lake sockeye), 5 were trapped at the Sawtooth Hatchery on the Salmon River, for a total return of 232 Snake River sockeye. The rest of the 2,750 fish available for spawning are fish raised in hatcheries and captive broodstock. Trapping is ongoing.
It’s all part of a “spread the risk” strategy IDFG has used since the 1990s, the state agency said in a news release . That strategy includes sockeye raised in the wild that naturally swim to the ocean and return. But it also includes fish raised in hatcheries and released in the spring, also to migrate to the ocean. In addition, there are captive broodstock — sockeye raised in hatcheries to adults as an insurance policy if none – or only a few fish – return from the ocean.
“Having natural and captive broodstock means biologists can hatch, raise and send the next generation of young fish to the ocean, and if conditions fall in their favor, later welcome back hundreds, or potentially thousands, of adults returning from the ocean,” IDFG said.
The 2021 sockeye run faced a number of challenges this year, IDFG said. It began with poor ocean conditions and then a June heat wave that warmed the Columbia and Snake rivers to near the potentially lethal limit of 68 degrees Fahrenheit as the fish migrated towards their destination. That triggered the trap and haul operation at Lower Granite Dam. The trapped fish were transported to IDFG’s Eagle Hatchery to ensure some of the fish would be available for spawning. The 2015 heat wave also triggered a trap and haul operation at Lower Granite.
See CBB, December 4, 2015, “Post-Mortem 2015 Snake River Sockeye Run; 90 Percent Of Fish Dead Before Reaching Ice Harbor Dam,”
— CBB, Oct. 15, 2020, NOAA FISHERIES STUDY WARNS CLIMATE CHANGE POSES ‘CATASTROPHIC’ THREAT TO SURVIVAL OF ENDANGERED SNAKE RIVER SOCKEYE
Only 6.7 percent of the fish that had been tagged as juveniles made the complete journey as adults from Lower Granite Dam to Redfish Lake this year, whereas about 50 percent generally reach the Sawtooth Basin from Lower Granite in a normal year, IDFG said.
“Our preference would have been to allow those fish to complete the last leg of their journey on their own, because from a genetic perspective, sockeye that make it back to the Sawtooth Basin have a level of fitness that we want in our captive breeding program,” said Lance Hebdon, Fisheries Bureau Chief. “But based on river conditions, trucking fish from Lower Granite Dam to Eagle was a necessary tradeoff to increase survival.”
Sockeye trapping also takes place at two locations in the Sawtooth Basin and then fish transferred to Eagle Fish Hatchery for temporary holding, according to Eagle Fish Hatchery Manager Dan Baker. Genetic information from each fish is analyzed to determine which fish to keep for broodstock and which to release to spawn in the lakes. Baker said traps in the Sawtooth Basin are at:
— The Redfish Lake Creek trap intercepts sockeye returning to Redfish Lake;
— The Sawtooth Fish Hatchery trap intercepts sockeye on the Salmon River (smolts released to the Salmon River), Alturas and Pettit lakes;
“Currently, Redfish and Pettit lakes are the focus for releases,” he said. “Alturas Lake is the third lake in the Sawtooth Basin that is a part of Idaho’s Sockeye Program.”
Sockeye are captive reared at IDFG’s Eagle Fish Hatchery and at NOAA Fisheries’ Burley Creek Fish Hatchery in Washington’s Kitsap County on the West side of the Cascade Mountains. Each program begins with 1,500 eyed eggs that are hatched and reared to maturity and mature as three- or four-year old fish, Baker said.
“About 1,500 adults from both programs are needed for captive broodstock to produce eggs for the smolt production program at IDFG’s Springfield Fish Hatchery,” Baker said. “Adults not needed to meet broodstock are available to be released to Sawtooth Basin lakes. Anadromous adults returning to the basin are incorporated into the captive broodstock or released.”
During September, IDFG biologists and other agency partners released 477 adults from the Eagle Hatchery’s captive broodstock program into Redfish Lake. They also released into the Sawtooth basin lakes sockeye that had returned from the ocean: 49 in Redfish Lake and 3 in Pettit Lake. In addition, IDFG transferred and released additional captive broodstock from a safety net program operated by NOAA Fisheries in Washington, which brought the total number of adults released for spawning to 1,112 in Redfish Lake and 99 in Pettit Lake.
IDFG also has about 700 captive-reared adults and another 150 adults that returned from the ocean, along with 680 captive adults from NOAA, which are all available for spawning and replenishing hatcheries.
The goals for the Eagle and NOAA hatcheries combined is to produce around 1.1 million eggs to replenish the captive broodstocks and transfer and rear at IDFG’s Springfield Hatchery, which is expected to grow about 1 million young sockeye to be released to migrate to the ocean in the future, the agency said.
Snake River sockeye were listed as endangered in 1991 under the federal Endangered Species Act when only four adult sockeye returned to the Sawtooth Basin. The total number of sockeye that returned between 1991 and 1999 was just 23 fish, including two years when no sockeye returned.
During 2015’s heat wave, 50 sockeye were trapped at Redfish Lake, 6 at the Sawtooth Hatchery and 35 at Lower Granite, with a total run size that year of 91 fish. This year 42 were trapped at Redfish Lake, 5 fish were trapped at the Sawtooth Hatchery and 201 (culled it was 185), for a total run size of 232, according to information provided this week by Baker.
The largest run since 1991 was in 2014 when the total run size was 1,579 sockeye (1,479 trapped at Redfish Lake, 34 at the Sawtooth Hatchery and no fish were trapped at Lower Granite). The second best total run was 1,355 in 2010 and the third best run was in 2011 with 1,117 fish.
After a run of 596 sockeye in 2016, run sizes have dropped to 176 in 2017, 115 in 2018, 17 in 2019, 152 in 2020 and then 232 this year.