Movement and habitat use of flathead catfish (Pylodictis olivaris) in two Missouri interior streams

The movements and habitat use patterns of adult flathead catfish were studied in two Missouri interior streams via radiotelemetry. At the largest spatiotemporal scale investigated, annual movements patterns included seasonal migrations commonly tens of kilometers long between overwintering, prespawn and spawning habitats, and postspawn feeding and growth habitats. Spatial variation in annual cycles within and between the Grand River and the Cuivre River were observed. Seasonally, fish moved the least during an overwintering period, moved the most during the prespawn/spawning period of spring and early summer, which was followed by a third period of restricted movements during late summer and fall.; Habitat use during the overwintering period was investigated in the Grand River and the adjoining reach of the Missouri River using a river habitat mapping system operated by the U.S. Geological Survey. During the postspawn restricted movement period, the home range of fish in both rivers were determined using univariate kernel density estimation. Home-range sizes were variable (median = 1085 m; range = 70–69090 m), and no differences between fish size classes, sexes, or rivers were evident. Habitat use was considered in an information-theoretic framework in which an exploratory all-subsets logistic regression analysis ranked the relative importance of 13 measured habitat components. Components of cover (especially large woody debris) and depth were found relatively more important than measures of velocity and substrate. Habitat use regression models from each river were evaluated and predicted well when applied to out-of-sample data from the other river. Diel activity patterns and 24-hour movement paths were presented. An appendix provides methodological information on univariate kernel density estimation in rivers and streams.