摘要：Loss and degradation of freshwater habitat reduces the ability of wild salmon populationsto endure other anthropogenic stressors such as climate change, harvest, and interactions with artificiallypropagated fishes. Preservation of pristine salmon rivers has thus been advocated as a cost-effective wayof sustaining wild Pacific salmon populations. We examine the value of freshwater habitat protection inconserving salmon and fostering resilience in the Kitlope watershed in northern coastal British Columbia—a large (3186 km2) and undeveloped temperate rainforest ecosystem with legislated protected status. Incomparison with other pristine Pacific Rim salmon rivers we studied, the Kitlope is characterized byabundant and complex habitats for salmon that should contribute to high resilience. However, biologicalproductivity in this system is constrained by naturally cold, light limited, ultra-oligotrophic growingconditions; and the mean (± SD) density of river-rearing salmonids is currently low (0.32 ± 0.27 fish persquare meter; n = 36) compared to our other four study rivers (grand mean = 2.55 ± 2.98 fish per squaremeter; n = 224). Existing data and traditional ecological knowledge suggest that current returns of adultsalmon to the Kitlope, particularly sockeye, are declining or depressed relative to historic levels. This poorstock status—presumably owing to unfavorable conditions in the marine environment and ongoing harvestin coastal mixed-stock fisheries—reduces the salmon-mediated transfer of marine-derived nutrients andenergy to the system's nutrient-poor aquatic and terrestrial food webs. In fact, Kitlope Lake sediments andriparian tree leaves had marine nitrogen signatures (δ15N) among the lowest recorded in a salmonecosystem. The protection of the Kitlope watershed is undoubtedly a conservation success story. However,"salmon strongholds" of pristine watersheds may not adequately sustain salmon populations and fostersocial and ecological resilience without more holistic and risk-averse management that accounts foruncertainty and interactions between ecosystem fertility, harvest, climate dynamics, and food web dynamicsin the marine and freshwater environments encompassed by the life cycle of the fish
