Conservation Risk and Uncertainty in Recovery Prospects for a Collapsed and Culturally Important Salmon Population in a Mixed‐Stock Fishery

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Connors, Brendan & Atlas, William & Melymick, Christina & Moody, Megan & Moody, Jason & Frid, Alejandro. (2019). Conservation Risk and Uncertainty in Recovery Prospects for a Collapsed and Culturally Important Salmon Population in a Mixed‐Stock Fishery. Marine and Coastal Fisheries. 11. 423-436. DOI: 10.1002/mcf2.10092.

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Mixed‐stock fisheries simultaneously exploit populations that may differ in their conservation status, and uncertainty in stock‐specific harvest rates can hamper evaluations of recovery prospects for depressed populations. These difficulties are exemplified in the Sockeye Salmon population from the Atnarko watershed, which collapsed in the early 2000s, causing cultural and economic hardship. A recovery plan identified the incidental harvest of Sockeye Salmon by mixed‐stock fisheries in the Atnarko as a potential, but poorly understood, impediment to recovery. We reconstructed harvest rates for salmon in Indigenous and commercial fisheries and used an age‐structured state‐space model of stock–recruit dynamics to predict how a range of future mixed‐stock harvest rates would influence recovery. Under recent harvest rates, there is a 50–60% chance that the population will grow to exceed a recovery goal of 15,000 spawners over the next four generations. Eliminating the harvest of Sockeye Salmon altogether increased predicted recovery prospects to a maximum of 69%, suggesting that factors other than fisheries are contributing to the lack of recovery (e.g., ocean conditions) and that harvest management alone is unlikely to lead to recovery with a high degree of certainty. We developed a generalized migration, harvest, and catch monitoring simulation model to quantify how different monitoring scenarios might improve estimates for mixed‐stock harvest rates. Increasing the number of specimens collected for genetic samples improved the harvest rate estimates for each stock caught in the mixed‐stock fisheries, particularly for the smallest stocks, and relative to single sampling events conducted near the peak of the return migration, weekly sampling improved estimates only slightly but provided insurance against missing the peak of the return migration. Our study highlights collaborative research initiated and directed by the Nuxalk Nation to promote the recovery of a depressed stock that is inherent to traditional foods, thereby contributing to a global effort to integrate Indigenous cultural values with biological conservation.

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