Snake River Sockeye Salmon Captive Broodstock Program, Research Element : Project Progress Report, 2000 Annual Report.

Abstract

On November 20, 1991, the National Marine Fisheries Service listed Snake River sockeye salmon Oncorhynchus nerka as endangered under the Endangered Species Act of 1973. In 1991, the Shoshone-Bannock Tribes and Idaho Department of Fish and Game initiated the Snake River Sockeye Salmon Sawtooth Valley Project to conserve and rebuild populations in Idaho. Restoration efforts are focusing on Redfish, Pettit, and Alturas lakes within the Sawtooth Valley. The first release of hatchery-produced juvenile sockeye salmon from the captive broodstock program occurred in 1994. The first anadromous adult returns from the captive broodstock program were recorded in 1999 when six jacks and one jill were captured at Idaho Department of Fish and Game's Sawtooth Fish Hatchery. In 2000, progeny from the captive broodstock program were released using four strategies: eyed-eggs were placed in Pettit Lake; age-0 presmolts were released to all three lakes in October; age-1 smolts were released to Redfish Lake Creek, and hatchery-produced adult sockeye salmon were released to Redfish and Alturas lakes for volitional spawning in September. Anadromous adult sockeye salmon were released to all three lakes. Total kokanee abundance in Redfish Lake was estimated at 10,268, which was the lowest abundance since 1991. Abundance of kokanee in Alturas Lake was estimated at 125,462, which was one of the highest values recorded since 1991. Abundance of kokanee in Pettit Lake was estimated at 40,599, which is the third highest value recorded since 1991. Upon the recommendation of the Stanley Basin Sockeye Technical Oversight Committee, the National Marine Fisheries Service reopened the kokanee fishery on Redfish Lake in 1995 in an attempt to reduce kokanee numbers. Anglers fished an estimated 3,063 hours and harvested approximately 67 kokanee during the 2000 season. Angler effort and harvest were also monitored on Alturas Lake during 2000. Effort on Alturas Lake was 5,190 hours, and harvest of kokanee was 407 fish. Anglers harvested an estimated 11% of the catchable rainbow trout planted into Alturas Lake. The out-migrant trap on Redfish Lake Creek was operated from April 12 to June 14, 2000. A total of 126 wild/natural and 2,378 hatchery-produced sockeye salmon smolts were captured, and total out-migration was estimated at 302 wild/natural and 6,926 hatchery-produced smolts. Estimates of smolt out-migration to Lower Granite Dam (LGR) were made by release strategy and were based on PIT-tag interrogations. An estimated 115 wild/natural smolts passed LGR from Redfish Lake. An estimated 6,987 hatchery-produced smolts released as presmolts into Sawtooth basin lakes passed LGR. None of the 148 age-1 smolts released to Redfish Lake Creek were detected at LGR. Two hundred fifty-seven anadromous sockeye returned to the Sawtooth basin in 2000. All were progeny of the captive broodstock program. The majority (200) of the adults that returned were released back to lakes in the basin for natural spawning along with hatchery produced adults. Redfish Lake received 164 adult sockeye salmon, and 20 to 29 areas of excavation were sighted. Alturas Lake received 77 adult sockeye salmon, and 14 to 19 areas of excavation were sighted. Pettit Lake received 28 adult sockeye salmon. No areas of excavation were noted in Pettit Lake, but spawning was suspected to have occurred in water too deep for observation. ndex reaches on principal tributary streams of Redfish and Alturas lakes were surveyed in August and September 2000 to track bull trout population response to no-harvest fishing regulations. Similar numbers of adult bull trout were observed in both systems, but twice as many redds were observed in Fishhook Creek. Redd counts in both streams have increased since monitoring began in 1998.