Patterns of Variability in the Distribution and Movement of Individual Fish Predators in a Heterogeneous Aquatic Ecosystem

Movement can dramatically change the outcome of ecological interactions and the effectiveness of fisheries management. To integrate consequences of mobility into existing paradigms, researchers and managers need to know how distribution and movement varies within and across fish populations and species. During multiple diel periods, months, and years, we tracked 123 acoustically tagged (VEMCO V9-V13) blue catfish (Ictalurus furcatus, mean = 505.3 mm, SD = 136.7, range = 300-1090 mm TL) in Milford Reservoir, KS. From June-November, 85.4-100.0% of the tagged fish were detected at least once a month by an array of 20 stationary receivers (VR2W) [Total Detections: 1,156,679 (2012) and 2,237,064 (2013)]. Individual blue catfish moved regularly (e.g., individuals were detected by 10 receivers on average), but spent most of their time in the central reservoir (mean = 198.5 hr). Groups of individual blue catfish displayed different patterns of movement that varied in region used, distance traveled, and frequency of movement. Thus, our tagged predators did not have restricted movements, did not use all habitats equally, and exhibited complex within-population behaviors. Insights from our research can provide a framework for quantifying variation in the distribution of mobile predators of other species in other ecosystems.