Assessing large-scale movement of an endangered fish: Dispersal of stocked age-0 pallid sturgeon in the lower Missouri River

Large-scale movement of fishes is a challenge for conservation and management in rivers, especially when individuals can cross jurisdictional boundaries. Assessing large-scale movement is particularly difficult during early life stages, especially when endangered species are involved. After hatching, free embryos of the federally endangered pallid sturgeon (Scaphirhynchus albus) drift long distances during development. Following the transition to exogenous feeding, individuals may continue to move downstream, resulting in a potential two-step migration. Tagged age-0 pallid sturgeon were stocked into the lower Missouri River, which provided an opportunity to assess pallid sturgeon dispersal as well as the hypothesized two-step migration. From July 2018 to April 2021, 79 individuals were captured, with most dispersing 200-800 km downstream from the stocking location. The observed dispersal of pallid sturgeon supports the two-step downstream migration hypothesis. This migration may lead to dispersal into the Mississippi River, which highlights the need for expanded monitoring into the Mississippi River for an effective evaluation of pallid sturgeon recovery actions. This study also reinforces the importance of inter-jurisdictional management and collaboration to better account for the large-scale movement of river fishes.

Automated summary

Large-scale movement of fishes poses a challenge for conservation and management in rivers, especially when endangered species are involved. Research on pallid sturgeon shows that they disperse over long distances during early life stages and potentially undergo a two-step downstream migration, highlighting the need for expanded monitoring for effective evaluation of conservation actions. Inter-jurisdictional management and collaboration are important to account for large-scale movement of river fishes.