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AUTHORS: Jonathan Spurgeon, University of Nebraska-Lincoln; Mark Pegg, University of Nebraska-Lincoln; Norman Halden, University of Manitoba
ABSTRACT: Variation in movement and source of immigrants among habitats is fundamental to understanding population structure and differing life-history strategies of large-river fishes inhabiting riverine-networks. We evaluated movement and natal origin of channel catfish Ictalurus punctatus between main-stem and tributary environments using otolith microchemistry. We assessed both water and otolith chemistries using univariate and multivariate statistical approaches. Water and otolith chemistries differed among river segments, and channel catfish were correctly classified to environment of capture between 75% and 96% of the time. We also assessed natal origins of channel catfish, and 92% were predicted to be of tributary origin. Movement behaviors suggested the channel catfish population consisted of a combination of non-migrants, migrants that return to natal environments, and random dispersers. Changes in the otolith microchemistry signatures of channel catfish suggests connectivity among main-stem and tributary environments, and indicate tributaries may support demographic processes at large-spatial scales. Consideration of the importance of habitats in both main-stem and tributary systems at different life-stages may, therefore, benefit conservation and management of large-river fishes.
