Northwest Fisheries Science Center

Display All Information

Document Type: Contract Report
Center: NWFSC
Document ID: 5529
Title: Monitoring the smolt migrations of wild Snake River spring/summer chinook salmon smolts, 1993
Author/Editor: Steve Achord, D. J. Kamikawa, Benjamin P. Sandford, Gene M. Matthews
Publication Year: 1995
Publisher: National Marine Fisheries Service
Contracting Agency: Bonneville Power Administration. Portland, Oregon
Contract Number: 91BP18800
Project Number: 91-28
Pages: 88
Date: 1995
  1. We PIT tagged and released 9,774 wild chinook salmon parr in 16 streams in Idaho during July and August, 1992.
  2. Total observed mortality from collection, tagging, and 24-h delayed mortality tests was 2.4%.  No PIT tags were lost during delayed mortality tests.
  3. From PIT-tagged fish we released in 1993, the overall adjusted percentage subsequently detected at dams averaged 14.7% (range 7.8-40.0%, depending on stream of origin).
  4. Fish that were larger at release were detected the following spring and summer at a significantly higher rate than their smaller cohorts (P < 0.001).
  5. Juvenile wild fish migrating in April and May were significantly longer at release than fish migrating after May (P < 0.001).
  6. Over an average of 272 d between release and recapture at Little Goose Dam in 1993, 52 wild chinook smolts grew an average of 38 mm in length and gained an average of 8.6 g in weight.
  7. Migration timing of wild spring/summer chinook salmon smolts at Lower Granite Dam in 1993 was similar to that in 1991, with peak passage in both years during the third week of May.  Although peak detections of fish from most streams occurred during the third week of May in 1993, peak passage periods for fish from 6 of 20 streams (including some Oregon streams) occurred before 2 May at Lower Granite Dam.
  8. The cooler-than-normal weather and low water temperatures from late winter to early summer appeared to delay juvenile migration.  However, high flows in the third week of May appeared to move a large portion of fish through the dams.
  9. Diel timing patterns of wild chinook salmon smolts passing from the fish and debris separators varied among dams.  At Lower Granite Dam significantly more fish exited the separator during nighttime hours (1800-0600 h), than exited during the day (0600-1800 h) (P < 0.001).  At both Little Goose and McNary Dam, more fish exited the separators during daytime hours than at night; however, this difference was significant only at Little Goose Dam (P < 0.05).