Captive broodstock rearing efforts at the Manchester Research Station include gene rescue efforts for U.S. Endangered Species Act (ESA) listed endangered Snake River sockeye salmon Oncorhynchus nerka from Redfish lake in the upper headwaters of the Salmon River in the Sawtooth Valley in Idaho. These fish are reared in freshwater at the station’s Burley Creek Hatchery and in pumped, filtered, and sterilized seawater in land-based bio-secure buildings at Manchester. In recent years, the NWFSC’s Redfish Lake sockeye salmon captive broodstock program has provided an average of about 250 adults and 140,000 sockeye captive broodstock progeny were provided to Idaho for use in recovery efforts.
In November 1991, NOAA Fisheries listed Snake River sockeye salmon (e.g., the population returning to Redfish Lake, ID) as endangered under ESA. Redfish Lake sockeye salmon make the longest migration (900 miles) and spawn at the highest elevation (6,500 feet) and southern most latitude (44.15 North) of any sockeye salmon stock. For the past two decades since the ESA listing, a group of agencies including NOAA Fisheries, the Idaho Department of Fish and Game (IDFG), the Shoshone-Bannock Tribes of Idaho (SBT), and the Bonneville Power Administration (BPA) have been collaboratively engaged in the captive broodstock-based gene rescue program to recover Snake River sockeye salmon.
The Redfish Lake sockeye salmon were virtually on the brink of extinction in the early 1990s. Based on probable extinction scenarios, all of the 16 anadromous adults (11 males and 5 females) were taken into a gene rescue captive broodstock program. To avoid the risk of catastrophic loss, redundant captive broodstocks were established: one at the IDFG Eagle Hatchery near Boise, ID and one at the NWFSC Manchester Research Station. Fish rearing at each facility is conducted at low density in tanks in bio-secure buildings.
Over the years, these captive broodstock programs have enjoyed considerable success. The Redfish Lake program has produced over 10,000 adult descendants from the 16 wild adult sockeye salmon that returned to the Sawtooth Valley during the 1990s. Egg survival to the eyed-stage of development has improved greatly and now often averages greater than 80%. Fry-to-maturation survival for captive broodstocks is now routinely in the 80% range, and size and body conformation of fish is often equivalent to the wild progenitors. The genetic focus of the program and adherence to various central tenets of conservation aquaculture has enabled program managers to retain approximately 95% of the original founding genetic variability of the population.
The combined NOAA Fisheries/IDFG Redfish Lake sockeye captive broodstock efforts have produced over 3.8 million eggs and fish for reintroduction to Sawtooth Valley lakes and tributary streams. Of these, 1,592,623 were released as pre-smolts, 1,119,337 released as smolts, 1,108,256 planted as eyed-eggs in egg boxes, and 8,021 released as pre-spawning adults. Since the first program-produced fish started returning in 1999, almost 4,300 adults have returned to collection sites in the Sawtooth Valley; over 250 times the number that returned from wild spawners during the entire decade of the 1990s. Without the steps undertaken by the Redfish Lake sockeye gene rescue program, this ESA-listed endangered stock might currently be extinct, just as it seems a virtual certainty that the steps described above have put the population onto the road to recovery.
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