Juvenile Coho Salmon Utilization of off-Channel Habitats in the Lower Klamath River

The Yurok Tribal Fisheries Program (YTFP) and the Karuk Tribal Fisheries Program (KTFP) initiated a collaborative study in 2006 to better understand juvenile coho salmon habitat use within the Klamath River mainstem corridor, which encompasses the main river channel and its side channels, off-channel habitats and the lower reaches of tributaries near the Klamath floodplain.  Fish sampling efforts have included the use of fyke nets, beach seines, and electro-fishing.  Fish marking techniques have been used to document fish movement patterns, estimate fish densities, and assess residence time in several off-estuary slough and lower tributary locations.  Marking young-of-the year coho salmon with Passive Integrated Transponder (PIT) tags by KTFP and YTFP throughout mainstem and tributary habitats has enabled tracking movement and growth of individual fish between the time they are marked and subsequent recapture events.  Results indicate that fish migrate substantial distances from natal tributaries and mainstem habitats into off-estuary sloughs and off-channel wetlands in the Lower Klamath River beginning with the onset of the first fall freshets. Beaver ponds and similar open-water wetlands appear to provide preferred over-wintering habitat in the Lower Klamath for non-natal juvenile coho salmon.  Growth rates of coho rearing in these habitats are substantially greater than those of fish sampled over the same time frame in free-flowing tributary habitats, indicating an advantage for fish that use these still-water habitats with relatively warm winter water temperatures compared to winter habitat conditions in natal inland streams.  PIT tagged coho from throughout the basin are consistently captured in these types of off-channel habitats, indicating that they play a key role in the growth and survival of coho salmon from throughout the Klamath Basin.  Life–stage habitat requirements and spatial distribution of these habitats seem to determine migratory behavior of juvenile coho.  Information regarding the importance of off-channel/beaver pond habitats is guiding our restoration efforts in the Lower Klamath Basin.  The YTFP has completed several off-channel pond enhancement and construction projects in recent years and monitored some of these sites with PIT tag antenna arrays and fish sampling efforts.  Juvenile coho have been observed utilizing newly constructed or enhanced ponds immediately following the first fall freshets, indicating that they are vital over-wintering habitat for both natal and non-natal fish from throughout the Klamath Basin.