Cooperative Fish and Wildlife Research Units Program: New York
Education, Research and Technical Assistance for Managing Our Natural Resources

Sethi SA, Ashline J, Harris B, Gerken J, Restrepo F. (2021) Connectivity between lentic and lotic freshwater habitats identified as a conservation priority for coho salmon. Aquatic Conservation: Marine and Freshwater Ecosystems, 31:1791-1801.


1. Juvenile Pacific salmon exhibit diverse habitat use and migration strategies to navigate high environmental variability and predation risk during freshwater residency. Increasingly, urbanization and climate-driven hydrological variability present further stressors for these anadromous species, emphasizing a need to conserve freshwater habitat integrity to support life history diversity as a buffer against ongoing ecosystem changes.
2. To inform catchment management for salmon, information on the distribution and movement dynamics of juvenile fish throughout the annual seasonal cycle is needed. While a number of studies have assessed the ecology of juvenile coho salmon (Oncorhynchus kisutch) during summer and fall seasons, catchment use by this species throughout the annual cycle is less well characterized, particularly in high latitude systems.
3. Here, n = 3,792 tagged juvenile coho salmon were tracked throughout two complete annual cycles to assess basin-wide distribution and movement behavior of this species in a subarctic, ice-bearing catchment.
4. Juvenile coho salmon in the Big Lake, Alaska, basin exhibited multiple habitat use and movement strategies across seasons; however, summer rearing in lotic mainstem environments followed by migration to lentic overwinter habitats was identified as a prominent behavior, with two thirds of tracked fish migrating en masse to concentrate in a small subset of upper catchment lakes for the winter. In contrast, the most significant tributary overwintering site (8% of tracked fish) occurred below a culvert and dam blocking juvenile fish passage to a headwater lake, indicating these fish may have been restricted from reaching preferred lentic overwinter habitats.
5. These findings emphasize the importance of maintaining aquatic connectivity to lentic habitats as a conservation priority for coho salmon during freshwater residency.