Within an ongoing round-the-clock radiotracking project, a subset of adult flathead catfish Pylodictis olivaris (n = 6) was continuously radio-tracked for 24 h to determine detailed diel movement path characteristics and activity in two Missouri streams. The ongoing radiotracking revealed that only a small percentage of point-in-time relocations were recorded as moving, while the majority (greater than 90% for every hour of the day) found fish stationary. The continuously-tracked subset of catfish generally moved by making discrete directed movements from one location to another, with locations corresponding to a physical habitat feature (large woody debris, clay point, undercut bank). All fish revisited locations during the 24-h tracking efforts. Movements were less than 100 m during early afternoon and the first 2 h after sunset, with longer movements undertaken from 2100 through the night to the 0500 hour, ceasing at sunrise. Movement paths had a median distance of 641.16 m with a median activity radius of 66.55 m. Fish spent a median 23.33 h stationary and 0.67 h moving during the diel cycle. The continuous tracking effort resulted in finer resolution and detail than was evident in the larger, typical point-in-time tracking dataset which did not highlight an early afternoon activity period, perhaps due to short, quick movements made at that time.
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The American Midland Naturalist
Vol. 155 • No. 1
January 2006
Vol. 155 • No. 1
January 2006