Project Abstract
This project offers the first scientific research of fish communities in the Fox River Flats Critical Habitat Area, located in Kachemak Bay, southern Cook Inlet, Alaska. Fish assemblages were assessed in a variety of habitats initially, with research becoming focused on juvenile salmon in four tidal channel habitats spanning an estuarine gradient from oligohaline near the top of the estuary to euryhaline near the mouth. Water temperature, salinity and depth in these channels were driven by varying mixing of glacial melt water from the Fox River and tidal influence. Over 14,000 fish were sampled in the four tidal channels over the duration of the project. Juvenile Coho and Sockeye salmon were the most abundant species in the channels, with both species peaking in July, with densities of 30 Coho/m and 18 sockeye/m. Both species were present from at least late April through early October. Diet samples were analyzed from 113 Coho and 104 Sockeye. Juvenile Coho and Sockeye salmon fed on 83 different prey taxa overall, with Sockeye having somewhat more compressed diets than Coho salmon. Seasonal bioenergetic models show high rates of growth in August (0.15-0.19 g g-1 d-1), likely fueled by high consumption rates and high energy density of prey. The prolonged presence and active feeding, substantiates that the Fox River estuary provides is providing beneficial rearing and outmigration staging habitats for juvenile Coho and Sockeye salmon.
