Juvenile Coho Life History Tactics Utilizing the Mid-Klamath River Corridor with Linkages Between Inland and Coastal Riverine Habitats

The Karuk Tribal Fisheries Program (KTFP) and the Yurok Tribal Fisheries Program (YTFP) initiated a collaborative study in 2006 to better understand juvenile coho salmon habitat use within the Klamath River mainstem corridor. The mainstem corridor encompasses the main river channel and its side channels, off-channel habitats and the lower reaches of tributaries in close proximity to the Klamath floodplain.  Sampling efforts include use of beach seines, fyke nets, directional weir traps in combination with marking and tagging fish to determine extent of residence, fitness and distribution in  relation to seasonal shifts in habitat characteristics.   In addition, KTFP and YTFP used passive integrated transponder (PIT tags) and remote PIT tag detection arrays to document movements into and residence times associated with various mainstem corridor habitats. Results indicate that some juvenile coho leave natal areas and re-distribute within the mainstem river corridor with movements closely associated with seasonal changes in water quality and flow patterns.   The use of non-natal habitats within the mainstem corridor, including small tributaries and off-channel features, appears to be an important survival mechanism for some juvenile coho in the Mid Klamath region during summer when water temperatures exceed lethal levels, and during winter when high flows occur. The relative importance of an overwintering re-distribution, however, appears to differ between the upper part of the Mid Klamath region, where winter flows are more stable due to less precipitation compared to the lower part of the region.  Flow patterns are much more dynamic downstream of Indian Creek where runoff from coastal mountains is dominated by a mix of rain and snow during late fall and winter.   Migrations of sub-yearling coho have been documented to exceed 120 miles in some cases along the mainstem Klamath River, combined with considerable movement upstream into small tributaries with preferred habitats.  Findings indicate that recovery actions could be tailored to benefit juvenile coho that utilize the mainstem corridor, thereby improving overall population viability. Strategic habitat restoration within the corridor could benefit all spawning aggregates located upstream.