Spatial structure of large‐river fish populations across main‐stem and tributary habitats

Abstract

AbstractThe spatial variability in demographic parameters represents fundamental information for conservation and management of large‐river fish populations. We assessed demographic processes including survival and movement across macroscale habitats in a large‐river network using 2 candidate large‐river species with contrasting life history strategies. We used mark–recapture data and a multistate model framework to estimate survival and transition probabilities between main‐stem and tributary habitats for both channel catfish and shovelnose sturgeon. Annual survival for channel catfish was similar in main‐stem and tributary habitats (range in S = 0.47–0.58). Annual survival for shovelnose sturgeon was less in the tributary (S = 0.68) compared with the main stem (S = 0.83). The probability of movement among macroscale habitats differed between species. However, the greatest probability of movement occurred from the tributary to the main‐stem for both channel catfish (ψ = 0.42) and shovelnose sturgeon (ψ = 0.27). Movement between main‐stem and tributary rivers may be a prominent characteristic for both channel catfish and shovelnose sturgeon and could influence population demographic rates and abundance across systems. Riverine fish populations are likely structured across multiple salient scales—including tributary and main‐stem habitats. Consideration of connectivity across tributary and main‐stem habitats with respect to species' life history strategy and life stage may better integrate a systems' perspective for conservation and management of large‐river fish populations.