Contributions to the Life History of Kuskokwim River Inconnu

A radiotelemetry study conducted during 2007–2016 in the Kuskokwim River drainage in Alaska expands our understanding of the life history strategies of Inconnu Stenodus leucichthys . The Inconnu like other whitefish species has specific spawning habitat requirements and consequently spawn in very few areas. Documenting specific spawning, feeding, and overwintering areas is the necessary first step to ensure their habitats are protected. Four spawning areas in the upper Kuskokwim River were identified from radio‐tracking and verified with on‐site sampling. Inconnu arrived at their spawning areas during late July through mid‐September and spawned during late September through early October. Postspawning outmigration occurred during 1–1.5 weeks in mid‐October. Most radio‐tagged Inconnu made extensive postspawning downriver migrations and overwintered in the lower Kuskokwim River and in the brackish waters of the upper Kuskokwim Bay; however, some Inconnu made only short postspawning migrations and spent the winter in the middle and upper Kuskokwim River. After spring ice out, many fish that overwintered in the lower river swam upriver and spent summers feeding at the mouths of major tributaries. A high degree of site fidelity among years was observed for spawning, feeding, and overwintering areas. Habitat characteristics of spawning areas were similar with respect to spawning substrate, temperature, pH , conductivity, dissolved oxygen, and turbidity. Information gathered from this study can be used by to identify a reliable index stock for the spawning population that can be enumerated periodically to ensure the long‐term sustainability of the population.