North American Journal of Fisheries Management 24:1163–1172, 2004 � Copyright by the American Fisheries Society 2004 Summer Movements within the Fish Community of a

• Main Authors: Small Montane Stream, David A. Schmetterling, Susan B. Adams
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Cottus cognatus; Slimy sculpin
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.400.3445; http://www.srs.fs.fed.us/pubs/ja/ja_schmetterling001.pdf

16 August 2001. We operated six weirs with two-way traps and one additional upstream trap, separated by 14–1,596 m, to quantify the timing, direction, and distance of movements and to estimate fish populations in the study reaches. We trapped and marked 567 fish of seven species, including 368 westslope cutthroat trout Oncorhynchus clarkii lewisi and 172 sculpin (slimy sculpin Cottus cognatus and an unidentified species similar to mottled sculpin C. bairdii). We recaptured 173 westslope cutthroat trout and detected net movements as long as 1,581 m (median, 91 m). Bidirectional movements for 116 westslope cutthroat trout ranged from less than 18 to more than 1,581 m (median, 64 m). Sculpin moved as far as 209 m (median, 26 m). We estimate that 14% of sculpin and 48 % of westslope cutthroat trout were mobile during the study. We captured all species more frequently at night or twilight (n � 296) than during the day (n � 83) and more frequently moving downstream (n � 419) than upstream (n � 277). These results demonstrate considerable summer movement by the fish community in a small stream. Movements are critical to the ecology and demography of many lotic fish populations. Movement of fish can affect population gene frequencies