Evaluation of transportation of juvenile salmonids and related research of the Columbia and Snake rivers, 1989
transportation, juvenile, salmonids, Snake River, smolt, marking, Lower Granite Dam, chinook, salmon, Menary Dam, delayed mortality, mortality, adult, releases, steelhead, Bonneville Dam, upstream, McNary Dam
U.S. National Marine Fisheries Service, Northwest and Alaska Fisheries Centre
1. Due to persistent drought conditions in the Snake River Basin, smolt marking operationsto re-evaluate transportation from Lower Granite Dam were suspended in 1988. NMFScompleted only 1 year (1986) of marking under the current 3-year evaluation.2. Totals of 50,029 test and 75,036 control spring/summer Chinook salmon and 60,013transport and 60,010 control fall Chinook salmon were marked at MeNary Dam in 1988,the final year of a 3-year marking study to re-evaluate transportation from that facility.3. Post-marking delayed mortality (48 hour) averaged 0.4% for both spring/summer and fallChinook salmon at MeNary Dam in 1988.4. Observed adult returns to Lower Granite Dam of spring/summer Chinook salmon taggedas juveniles for transport index purposes in 1985 are complete to the dam only. Theobserved return of 0.22% is similar to returns for the 1983 and 1984 transport indexgroups and is much improved compared to returns for transport releases of this speciesfrom 1976 to 1980. Adult returns to Lower Granite Dam 10 from 1986 juvenile transportresearch show transport and control recoveries of 0.11 and 0.06%, respectively.5. We have recovered as adults 1.8% of the juvenile steelhead that were marked andtransported to below Bonneville Dam in 1985. The majority of these fish were recoveredat Lower Granite Dam. Low river-flows and accompanying high water temperatures in thesummer and fall of 1987 appeared to have considerably reduced the recovery of 2-oceanage fish from these releases. The same may be true for 1ocean age adults from transportand control groups marked and released in 1986. One-ocean age adult recoveries of0.34% for the transports and 0.21% for the controls were well below the expectedrecovery. These fish also migrated upstream in the summer and fall of 1987.6. Adult recoveries of spring/summer and fall Chinook salmon marked as juveniles atMcNary Dam in 1986-87 are still few and scattered. Recoveries of these fish shouldincrease considerably next year.