Movement of flathead catfish in the Missouri River: examining opportunities for managing river segments for different fishery goals

The dispersal patterns of 2939 flathead catfish, Pylodictis olivaris (Rafinesque), were determined within a 90-km section of the Missouri River, USA. Fish were captured by electric fishing and tagged in early June each year from 1999 through 2001. Dispersal was determined via angler tag returns between 1999 and 2001 or by subsequent recapture during sampling 1 or 2 years after initial tagging (June 2000 or 2001). Dispersal was localised for the majority of the 370 flathead catfish recaptured in the Missouri River. Over 80% of recaptures were within 5 km of tagging location, and 94% were within 20 km of tagging location. Maximum displacement was 160 km. To examine differences in movement patterns of various sized fish, flathead catfish were placed into one to three size groups (305-380, 381-507, or greater than or equal to508 mm). A significant difference (P<0.001) was detected in dispersal patterns among the three size groups; the largest size group moved greater distances than either of the smaller size groups. Movements average 4.5, 5.6 and 12.6 km for small, medium, and large size classes, respectively. Dispersal movements of flathead catfish in the Missouri River appeared to be localised, suggesting that different sections of the Missouri River could be managed for different fishery goals for flathead catfish to accommodate a variety of angler types and desires.