Title
Evaluation of fish movements, migration patterns, and population abundance with Streamwidth PIT tag Interrogation systems
Date
2003
Keywords
fish movement, migration, PIT tag, survival, smolt, production, salmonids, juvenile, coho, salmon, trout, steelhead, laboratory study, tagging
Summary
None supplied. From executive summary: Two remote PIT tag Interrogation systems (SPIs) were operated continuously for over one year to test the feasibility of these systems for generating movement, migration, survival, and smolt production estimates for salmonids. A total of 1,588 juvenile (< 100 mm FL) naturally produced salmonids (7 coho salmon, 482 cutthroat trout, and 1,099 steelhead) were PIT tagged above the upstream-most SPI (9 sites approximately 1 linear km each) in Fall 2001. Over 390,000 detections were recorded from October 2001 to 31 July 2002. Efficiencies were site dependent, but overall detection efficiency for the creek was 97% with 95% confidence intervals of 91-100%. PIT tag detection efficiency raged from 55 - 100% depending on the SPI and varied throughout the year with average efficiencies of 73% and 89%. Steelhead and cutthroat trout were primarily detected moving in the Spring (April - June) coincident with the anticipated smolt migration. Steelhead were also detected moving past SPIs at lower numbers in the Fall and Winter. A laboratory study was designed to determine the effects of 3-sized PIT tags (12 mm, 20 mm, and 23 mm) on survival and growth of individuals. Survival from surgical implantation of 23 mm PIT tags was >98% for fish (coho salmon and steelhead). Retention of 23 mm PIT tags was 100% for coho salmon and 89% for steelhead. For both coho and steelhead, growth rates during the first month were affected by tagging, but by the end of two months growth effects equalized for all tag sizes.