Juvenile Salmon in the Skeena Estuary: Implications for Climate Change and Industrial Development

Diadromous salmon utilize estuaries during their downstream migration from freshwater to marine habitats, but the relative importance of these habitats for juvenile salmon is poorly understood. Over the last several years, we have conducted a juvenile salmon sampling program in the estuary of the Skeena River, a relatively intact estuary at the base of a the second largest salmon-producing watershed in Canada that has several pending large-scale industrial projects. We found that the highest abundances of some species of juvenile salmon, including culturally and economically important Chinook and sockeye salmon were captured in areas proposed for development. Stable isotope analysis “clocks” provided evidence that different species of juvenile salmon occupied the estuary for different lengths of time, with some individuals feeding in the estuary for many weeks. Genetic analysis revealed that the juvenile salmon captured in the estuary came from tributaries throughout the Skeena watershed and beyond. Furthermore, different sockeye salmon populations have different migratory phenology. Given ongoing ocean warming, these different salmon populations may respond differently to shifting oceanographic conditions and provide resilience to the Skeena salmon metapopulation. More generally, this research reveals that the Skeena estuary region proposed for development supports high abundances and diversity of salmon.