Report on the impacts of fisheries on stocks and landings under SEAwise EBFM

SEAwise research

As part of our efforts, a range of different climate and management scenarios were assessed, including measures relating to catch limits and efforts controls, gear changes, reduction in trawling effort, and spatio-temporal closures of specific areas. Grouped into five broad categories these were as follows:

• Main management scenarios: including a Maximum Sustainable Yield target on top of full implementation of landing obligation, a more flexible Pretty Good Yield (PGY) target, current effort level, and a case specific scenario.
• Climate change scenarios: combining management scenarios with two climate scenarios depicting moderate (RCP4.5) and more severe (RCP8.5) warming.
• Technical change scenarios: whereby gear changes were implemented in terms of selectivity measures or quota adjustments.
• Trawl Ban scenarios: where trawling effort was reduced by half and various options were explored for remaining fishing gears.
• Spatio-temporal closure scenarios: whereby a one month area closure to protect dolphins was implemented in the Bay of Biscay, and different Marine Protected Areas (MPAs) to protected seabed habitats were tested. 

According to our assessment, the effects of management measures and impacts of climate change varied significantly across regions, fleets and stocks, highlighting the need for context-specific, regionally tailored approaches. On the whole, climate change effects were mainly negative – however, some positive impacts were observed at the local-level for some areas (e.g. whiting in the North Sea).

We also found that the socio-ecological system was more resilient when fish populations were in good status, and this was generally realised when MSY or PGY approaches were implemented on top of full implementation of a landing obligation. Technical measures produced diverse outcomes across regions, signposting the importance of targeted implementation.

To summarise information from scenarios, Multi-Criteria Decision Analysis (MCDA) – a structured approach to help decision-makers rationally choose between multiple options where there are several, sometimes conflicting, options – was employed. This analysis also allowed for the identification of trade-offs and ranking of scenarios, based on the preferences of stakeholders. The employment of the analysis revealed that the ‘best management options’ were largely determined by regional priorities – whether economic or environmental.