|Document Type:||Contract Report|
|Title:||Relative survival of juvenile salmon passing through the spillway of The Dalles Dam, 1999|
|Author/Editor:||Earl M. Dawley, C. J. Ebel, R. F. Absolon, Benjamin P. Sandford, John W. Ferguson|
|Publisher:||National Marine Fisheries Service|
|Contracting Agency:||U.S. Army Corps of Engineers. Portland, Oregon|
In 1999, we continued a third year of passage survival tests at The Dalles Dam, comparing 30 to 64% spill conditions. Test fish were collected from the fish collection facility at John Day Dam and tagged with passive integrated transponder (PIT) tags. Approximately 139,000 yearling Chinook and coho salmon were tagged in April and May (spring migrants) and 167,000 subyearling Chinook salmon were tagged in June and July (summer migrants).
About 50% of the test fish were released through the spillway at either 30 or 64% spill (~25% each), and about 50% were released in the tailrace as survival reference groups. Half of the test fish were released at night and the other half in daylight. The tailrace groups were released at a site away from turbulence and areas of suspected predation, and at a time to coincide with passage of treatment groups. Spillway releases were apportioned, as equally as possible, to three lateral locations in the spillway forebay, and spill conditions were alternated every 3 d between 30 and 64% of river flow.
Based on data collected through the third year of this study, we arrived at the following conclusions:
The following are recommendations for research in 2000: