Learning From Improved Age‐0 Sampling to Inform Conservation of an Endangered Fish

ABSTRACT Sturgeon are highly imperiled due to many potential factors including overfishing and habitat fragmentation; however, persistent knowledge gaps for early life stages have limited conservation efforts. In the central United States, two native, sympatric congeners with differing population statuses occur in the Missouri River: shovelnose sturgeon ( Scaphirhynchus platorynchus ) are self‐sustaining and abundant, whereas pallid sturgeon ( Scaphirhynchus albus ) are federally endangered. We document challenges with sampling young sturgeon in a highly modified, large river and detail the steps taken to improve sampling efforts. Building on lessons learned from prior field studies coupled with a willingness to adapt research and monitoring efforts increased capture effectiveness of age‐0 Scaphirhynchus sturgeon in this large river system. These efforts resulted in historically high captures of age‐0 pallid sturgeon, which provided an unprecedented opportunity to address knowledge gaps regarding adult spawning success as well as location, distribution, drift dynamics, and habitat use of early life stages. We demonstrate how this new information provides critical insight for pallid sturgeon conservation, including stocking practices, habitat creation projects, hybridization, and the use of surrogate species. We caution against pursuing extensive habitat projects based solely on hypothesized links to life history requirements as this may jeopardize success and ultimately public support for management efforts. Lessons learned may be applicable to other difficult‐to‐sample large river fishes during early life history and helpful to managers balancing tradeoffs between uncertainty, taking action, and tenuous public support.