Changing coastal distribution and life-history patterns of Inconnu in northwest Alaska

Climate change is driving shifts in fish distributions across Arctic ecosystems. Inconnu (Stenodus leucichthys) are an important subsistence and recreational fishing species and depend upon a mosaic of aquatic habitats that are rapidly changing. The freshwater migratory patterns of these fish are well-documented, but information on their coastal movement patterns and life histories are largely unknown. To better understand northwest Alaska Inconnu coastal habitat use, we integrated Traditional Ecological Knowledge, long-term fish monitoring data (2012–2024), analyzed otolith chemistry 87Sr/86Sr chronologies, and deployed pop-up satellite archival tags on adult fish to characterize movements and distribution. Distinct natal region 87Sr/86Sr differentiated Kobuk and Selawik River Inconnu populations. Otolith chronologies revealed extensive juvenile (age-0–age-4) use of estuarine and marine habitats and identified at least four life history patterns. We found that Inconnu are increasingly traveling to coastal areas up to 250 km away from their historical distribution, hundreds of kilometers from natal rivers. This dispersal of Inconnu into new areas may affect existing fish assemblages and could cause changes to subsistence fishing catches. Improved understanding of Inconnu coastal ecology will better inform management of this important resource, which is needed as aquatic ecosystems change and industrial activities increase in Arctic Alaska.