Stream Dispersal of Dead Fish and Survey Effectiveness in a Simulated Fish Kill

• Published in: Transactions of the American Fisheries Society (1900) 2000-01, Vol.129 (1), p.89-100
• Main Authors: Ryon, Michael G., Beauchamp, John J., Roy, W. Kelly, Schilling, Elizabeth, Carrico, Brian A., Hinzman, Roxanna L.
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Freshwater; Fundamental and applied biological sciences. Psychology; Pisces; Vertebrata
• ISSN: 0002-8487; 1548-8659
• DOI: 10.1577/1548-8659(2000)129<0089:SDODFA>2.0.CO;2

The dispersal and recovery effectiveness of tagged dead fish were determined in a simulated stream fish kill. Two experiments were conducted under different flow regimes within a 2.3‐km section of headwater stream. The first experiment used 120 tagged dead fish that were released at three locations when the mean daily flow was 153 L/s. In six surveys conducted over 2 d, we found that a majority of fish (58%) were dispersed less than 35 m. Fish that were dispersed more than 35 m traveled quickly and traversed significant distances (up to 605 m). A unique distribution pattern was noted at each site, ranging from very limited to widespread dispersal for most fish. The second experiment used 216 tagged fish that were released at the same locations when the mean daily flow was 771 L/s. In six surveys conducted over 2 d, we found that 70% of the fish were dispersed more than 35 m. As in the first experiment, a range of dispersal patterns was found. In both experiments, surveys of tagged fish were effective, with 33 to 85% of fish found in each survey on the first day and with 81 to 93% of the released fish seen at some point during the experiments. However, daily surveys for dead fish may underestimate actual mortality, in part because there is substantial removal by scavengers.