|Document Type:||Contract Report|
|Title:||Research related to transportation of juvenile salmonids on the Columbia and Snake Rivers, 1992|
|Author/Editor:||Jerrel R. Harmon, Benjamin P. Sandford, Kenneth L. Thomas, Neil N. Paasch, Kenneth W. McIntyre, Gene M. Matthews|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers. Walla Walla, Washington|
|Pages:||25 p. plus appendices (162 p.)|
In 1992, National Marine Fisheries Service (NMFS) research addressed two areas related to smolt transportation. The first was completion of a 3-year marking program to evaluate barge transport of smolts from Lower Granite and McNary Dams to a release site below Bonneville Dam. The second was an estuarine release-site study on barged steelhead Oncorhynchus mykiss smolts.
Transportation Studies—Drought conditions in the Snake River Basin again precluded marking of spring/summer Chinook salmon O. tshawytscha and steelhead smolts for the final year of a 3-year reevaluation of transportation from Lower Granite Dam. A similar 3-year study marking juvenile fall and spring/summer Chinook salmon at McNary Dam was completed in 1988.
Adult recoveries continued for these studies and for a group of spring/summer Chinook salmon smolts marked for transport at Lower Granite Dam during the 1990 drought year. Adult recoveries from transport and control groups of spring/summer Chinook salmon smolts marked at Lower Granite Dam in 1989 are complete, but are much lower than expected. Nevertheless, significantly more transports than controls were recovered, with a transport to control ratio (T/C) of 2.4 and a 95% confidence interval (CI) of 1.4 to 4.3. Adult recoveries of spring/summer Chinook salmon smolts marked for barge transport in 1990 are incomplete. So far, this group is returning at a higher rate than any group we have marked since 1983.
Adult recoveries of steelhead smolts, marked as transports and controls and released in 1989, are also incomplete, but like adult returns of spring/summer Chinook salmon marked in that year, are much lower than expected. The preliminary T/C is 2.1 at Lower Granite Dam.
Marine-mammal abrasions—We continued to observe high abrasion levels from marine mammal teeth and claws on adult spring/summer Chinook salmon. Prevalence of abrasions in 1992 was 15%, with open wounds occurring on about one-third of the fish with abrasions.
McNary Dam—For the McNary Dam studies, adult returns from transport and control groups of spring/summer Chinook salmon smolts marked in 1988 are complete. The TIC was 1.6 with a 95% CI for combined recoveries between 1.0 and 2.6. For fall Chinook salmon, adult returns for juveniles marked as transports and controls in 1986 are complete. Significantly more fall Chinook salmon transports than controls were recovered from all locations, with a T/C of 3.0 in the ocean fisheries. Adult returns for the 1987 and 1988 study years are incomplete; however, recoveries from all areas continue to strongly favor the transported groups.
Steelhead Release-Site Study—In 1992, we began a 3-year marking study to compare adult returns of barged steelhead srnolts, released in the upper Columbia River estuary at Tongue Point at river kilometer (rkm) 29.3, with those released at the traditional site just downstream from Bonneville Dam near Skamania Light (rkm 224.0). Between 1 and 20 May, we marked seven release lots of approximately 9,000 steelhead each for the Tongue Point releases, and seven lots of 10,000 steelhead each for the Skamania Light releases. Overall post-marking delayed mortality and tag loss were low, averaging 0.7 and 0.5%, respectively.