Assessment of Range, Habitat Use, and Diel Movement of Flathead Catfish (Pylodictis olivaris) in the Wabash River Using Ultrasonic Telemetry

Flathead Catfish (Pylodictis olivaris) are one of the most targeted species for recreational and commercial fishing within the Mississippi River Basin. With heavy harvest pressure placed on many populations, proper management is crucial; however, the species range, habitat requirements, and diel movement patterns have rarely been investigated in free flowing rivers. Therefore, I used ultrasonic telemetry with active tracking to monitor movement and habitat use of 44 Flathead Catfish from August 2012 to December 2013 in the lower 280 km of the Wabash River. This system is ideal to evaluate broad and fine scale movement of Flathead Catfish because the population is well-established and individuals are able to move without restriction caused by impoundments. Fish were located by reach and diel tracking performed seasonally, and monthly site specific tracking. I found that Flathead Catfish exhibit relatively small movements within a localized annual range (\u3c 12 km). Most often, fish were observed using shoreline habitat, specifically, outside bends and channel borders containing dense woody debris. Although there was no seasonal difference in the range of movement, season was a major driver in daily activity and habitat use. Flathead Catfish showed the most diel movement during summer, utilizing shoreline and main channel habitats, whereas movement decreased dramatically during winter when fish only used shorelines. Results from my research indicate habitat requirements for Flathead Catfish during annual spawning and overwintering are found in outside bends containing logjam structure. I suggest these areas are crucial for the species persistence within lotic systems and should be recognized as such. Managers can use this information to ensure habitat requirements are met and to assist with development of restoration and conservation strategies if future populations begin to decline