Backgrounder: Climate Change Adaptation Strategies for the Nass River Watershed

The Nass River is the third largest watershed in the British Columbia. The watershed has a few large lakes and the climate is typical of coastal watersheds in the north, with moderate air temperatures with abundant precipitation over the year. The area is highly productive, supporting a variety of fish species including all Pacific salmon as well as steelhead and cutthroat trout. The watershed supports both lake and ocean sockeye. Status of these populations is generally strong.

Co-management, rigorous stock assessment, as well as habitat protection and rehabilitation have played major roles in protecting Nass River salmon stocks. Joint management through the Nisga’a Fisheries Program has been instrumental in minimizing impacts of over harvesting and habitat loss. Salmon are harvested in multi-species, mixed stock fisheries that take into account priorities including conservation, Nisga’a and other First Nations, recreational, and commercial interests. The Pacific Salmon Treaty has played an important role in protecting returns of Nass stocks.

The Nass River watershed is large and relatively pristine, with fewer development activities than watersheds in the Georgia Basin or Southern Interior. There are no agricultural activities or large urban centres adding stressors to salmon habitats and water supplies. Logging does occur in lower elevation areas from the mouth to the headwaters. Measures to off-set salmon mortality from marine harvest or logging-related impacts on habitats in the Nass River have been implemented.

Economic opportunities associated with the commercial catch are significant, notably for the Nisga’a Nation, to maintain control over their livelihood and maintain salmon-centred cultural activities. Salmon contribute marine-derived nutrients and biomass to forest, stream, and lake ecosystems, which are especially important in nutrient-deprived coastal watersheds.

With appropriate in-season harvest adjustments, sufficient assessment and monitoring and protection of critical habitats, Nass salmon have the best chance of coping in an era of climate change, but they are still sensitive to climate-driven changes in sea surface temperatures and hydrologic changes associated with changing patterns of precipitation and timing of snowmelt. To mitigate these effects, fisheries management practices must be adjusted.

Improved monitoring of escapement, better delineation of production goals, and genetic studies related to understanding importance of smaller stocks would also help ensure that overharvesting is minimized. In the Nass, conservation risks may be greatest for sockeye and chum salmon.
Low impact forestry practices should be implemented. Within the context of future climate changes and related vulnerabilities of freshwater habitats, changes in the frequency, timing, and magnitude of logging-created low-flow conditions may affect salmon migration, spawning, and incubation in the future. Low impact forestry practices and protection of critical habitats could help alleviate potential increases in salmon mortality.

Additional hydrological data will be critical to helping managers understand the potential implications of climate change on North Coast hydrology and salmon. Managers would then be better able to design forestry mitigation strategies that best off-set anticipated impacts on freshwaters habitats and salmon.