Six Sockeye Salmon Make the Journey Back to Idaho

In early September, the final two sockeye salmon returning to the Sawtooth Valley were captured, bringing the total number collected at fish weirs operated by the Idaho Department of Fish and Game to six. Thirty people were involved in the seining operation conducted to collect two stubborn sockeye salmon holding in the river just downstream of the Sawtooth Fish Hatchery's adult trap. The crew included Fish and Game personnel from the Salmon Region, the Southwest Region, and Shoshone-Bannock tribal biologists. Seining involves laying out a large net for the fish to swim over then gathering the net and capturing the fish. Workers donned waders and even snorkel gear to get the job done. The seining operation was a huge success, with only three passes required to capture the remaining two sockeye from below the Sawtooth Fish Hatchery weir. According to researchers at the University of Washington, 10 adult sockeye salmon have been counted passing Lower Granite Dam, the last dam in the sockeyes' 1,800- mile round-trip journey back to Idaho. Typically, 50 percent of the sockeye salmon adults that pass Lower Granite Dam successfully make it to the Sawtooth Valley. Biologists refer to this as the "conversion" of adults from one point to the next in their journey. The fish returning to the Sawtooth Valley were produced by the Redfish Lake Captive Broodstock Program. The Captive Broodstock Program began in 1991 just before Redfish Lake sockeye salmon were placed on the federal endangered species list. By breeding sockeye in captivity, biologists maximize survival and protect the genetics of the population. The Redfish Lake Captive Broodstock Program is a cooperative effort among IDFG, the Shoshone-Bannock Tribes, the University of Idaho, and the National Oceanic and Atmospheric Administration-Fisheries. The program is funded by Bonneville Power Administration as mitigation for the Federal Columbia River Power System. Eggs produced by captive broodstock are reared primarily by Fish and Game at the Eagle and Sawtooth hatcheries, as well as at NOAA hatcheries in Washington State. Biologists place some of the eggs in nursery lakes as eyed eggs. Some of the hatchery-born salmon enter the lake environment as pre-smolts, while others are released into streams when they reach the smolt stage. Fish and Game also releases a certain number of sockeye adults from the hatchery program in hopes that they will spawn naturally. Anadromous adult sockeye returning to Idaho are produced from one of these release strategies. In 2003, an estimated 31,067 hatchery and naturally produced sockeye salmon smolts left the Sawtooth Valley en route to the Pacific Ocean. The six adults returning to the Sawtooth Valley this year are most likely from that group. Project cooperators expected about 30 adults to pass Lower Granite Dam this year. Only a third of that number have made it. Some runs of adult Chinook salmon were lower than expected in many locations this year as well. Biologists aren't certain why numbers were lower than expected this year. Eagle Hatchery manager Dan Baker says the low number at Granite is disappointing, but the conversion rate presents a silver lining. "With six out of ten adults making it to the Sawtooth Valley our conversion rate is 60 percent," Baker said. "That's good." This is the second year anadromous sockeye were seined from below the Sawtooth Fish Hatchery weir. Program cooperators and geneticists around the Northwest feel it is important to breed returning anadromous sockeye with captive reared sockeye broodstock. The genetics of these fish are already contained in the captive broodstock at the Eagle Hatchery, but the fish that swam thousands of miles have something the broodstock don't. "The fitness these anadromous fish demonstrated through migration corridors can not be duplicated in a captive broodstock program" Baker said. With one-third of the anadromous returning sockeye still in the river, it was important to seine the last two fish to identify marks, tags, age, genetics, sex, and pathology information after spawning of individual fish. This information will help biologists evaluate the various release strategies used in the Sockeye Salmon Captive Broodstock Program.