Adding to the mix – Challenges of mixed-fisheries management in the North Sea under climate change and technical interactions

Technical interactions (multiple fleets fishing multiple species with various gears, as either target or bycatch), bycatch regulations through a landing obligation, and biological and economic effects of climate change, affecting fisheries yield and profits, provide a challenge for demersal mixed fisheries of the North Sea. A multi-stock, multi-fleet, bioeconomic model was used to understand management options under these combined influences. Scenarios considered climate change effects on recruitment of three main gadoid stocks (cod – Gadus morhua, saithe – Pollachius virens, whiting – Merlangius merlangus), possible future developments of fuel and fish prices, and strict implementation of a landing obligation. The latter leads to decreased yield and profits in the short term due to increased choke effects, mainly of North Sea cod, being influenced by climate-induced productivity changes. Allowing fishing above F_MSY, but within sustainable limits, or limiting year-to-year quota changes, could help buffer initial losses at the expense of decreased profits in the mid- to long-term. Economic performance of individual fleets was linked to their main target's stock status, cost structure, and fuel and fish prices. The results highlight a need to consider both biological and economic consequences of climate change in the management of mixed fisheries.