Quantifying regional patterns of collapse in British Columbia Central Coast chum salmon (Oncorhynchus keta) populations since 1960

Abstract

In recent decades, chum salmon ( Oncorhynchus keta) on the Central and North Coasts of British Columbia have experienced increasing variability and declining abundance. Chum are targeted by mixed-stock commercial fisheries despite declining trends and limited stock assessment to clarify conservation and fishery tradeoffs. We analyzed trends in chum salmon run sizes to 25 watersheds in the Central Coast region, to support co-governance of fisheries under newly ratified Fisheries Resources Reconciliation Agreement. Central Coast chum have declined by ∼90% since 1960, and only three populations did not undergo an evident decline. Bella Coola enhanced chum had an increasing trend but have experienced 29-fold variation in run sizes since 2005. Recently, Bella Coola enhanced chum comprised over 50% of Central Coast chum abundance and the contribution of this stock to overall abundance has more than tripled (from 13.8%) since enhancement began. Given concerns about the long-term health of chum salmon stocks and the social–ecological systems they support, commercial fisheries were closed on the Central Coast in 2021. If current trends continue, fishery opportunities may remain limited.