Blue catfish population characteristics and dispersal along a Great Plains river gradient

Understanding movement and dispersal dynamics of mobile, large-river fishes is essential to adopting an ecologically relevant spatial scale for research and management. Movement and dispersal patterns of Blue CatfishIctalurus furcatus, a large-river specialist, have been mostly investigated in large river systems within their native range, with little emphasis on tributaries and the influence of connectivity. Here, we examine longitudinal movement patterns, natal environments, and population demographics of Blue Catfish in a tributary system of a large Great Plains river. Blue Catfish tagged in the Kansas River were recaptured in five different rivers of varying size and order, and individual movement was highly variable (0-475 rkm). Adult fish (>400 mm) collected within segments (i.e., Segment 1 and 2) of the Kansas River with connectivity to the Missouri River displayed relatively equal natal contributions from the Kansas River (34-48%) and Missouri River (38-65%) while disconnected river segments contained a high percentage (64-87%) of individuals that originated from reservoirs located on tributaries to the Kansas River. The Kansas River segments (Segment 1 and 2) connected with the Missouri River had lower instantaneous mortality (Z = 0.19, SE = 0.05) and higher proportions of large fish (PSD-M = 9 & 11, PSD-T = 3 & 5, respectively) compared to disconnected reaches (Z = 0.27, SE = 0.08; PSD-M = 3, PSD-T = 0). Mean length of Blue Catfish collected in disconnected reaches were greater than those from connected reaches for individuals at age-3 and age-6, and relatively equal at age-10. Our data provide additional resolution to movement and dispersal patterns of Blue Catfish within large-river tributary systems, highlight the role of localized reservoir stock contributions, and illustrate species plasticity across varying levels of river network connectivity.