Recruitment Sources of Channel and Blue Catfishes Inhabiting the Middle Mississippi River

Abstract

Abstract Insight into environments that contribute recruits to adult fish stocks in riverine systems is vital for effective population management and conservation. Catfishes are an important recreational species in the Mississippi River and are commercially harvested. However, contributions of main channel and tributary habitats to catfish recruitment in large rivers are unknown. Stable isotope and trace elemental signatures in otoliths are useful for determining environmental history of fishes in a variety of aquatic systems, including the Mississippi River. The objectives of this study were to identify the principal natal environments of channel catfish Ictalurus punctatus and blue catfish Ictalurus furcatus in the Middle Mississippi River (MMR) using otolith stable oxygen isotopic composition (δ 18 O) and strontium : calcium ratios (Sr : Ca). Catfishes were sampled during July–October 2013–2014, and lapilli otoliths were analysed for δ 18 O and Sr : Ca. Water samples from the MMR and tributaries were collected seasonally from 2006 to 2014 to characterize site‐specific signatures. Persistent differences in water δ 18 O and Sr : Ca among the MMR and tributaries (including the upper Mississippi, Illinois, and Missouri rivers as well as smaller tributaries) were evident, enabling identification of natal environment for individual fish. Blue and channel catfish stocks in the MMR were primarily recruited from the large rivers (Missouri and Mississippi) in our study area, with minimal contributions from smaller tributaries. Recruitment and year class strength investigations and efforts to enhance spawning and nursery habitats should be focused on in large rivers with less emphasis on smaller tributaries. Copyright © 2016 John Wiley & Sons, Ltd.