Understanding and accurately predicting past and future changes

To understand and predict how human activities will affect marine ecosystems in the future, models need to be accurate in detecting and attributing the effects of specific drivers on past ecosystem changes. Previously FishMIP’s primary focus has been on reporting climate change effects on marine fish biomass in the absence of other direct human influences (Lotze et al., 2019; Tittensor et al., 2021; Tittensor et al., 2018; Heneghan et al., 2021). This has been due to the lack of standardized historical fishing effort data at the global scale, meaning that fishing has been incorporated in only a small subset of the global models, in a variety of ways. To systematically tease apart the relative and combined effects of global climate change and fishing, and the extent to which future fisheries are at risk under different management scenarios (Tittensor et al., 2021; Scherrer et al., 2020), a consistent approach for incorporating fishing drivers is needed. This is especially important for the development of scenarios describing how evolving socioeconomic and environmental conditions are likely to affect future fishing fleets, from artisanal to industrial scales, and to provide knowledge on the potential cumulative and interactive impacts of fishing and climate pressures on marine ecosystems (see Chapter C.2).
To address these issues, ‘FishMIP 2.0’ has been developed to provide consistent data and scenarios to tackle questions related to changing climate and socioeconomic conditions, and to how future fisheries will evolve and adapt over time (Blanchard et al., 2024) across global and regional scales. This framework is divided into two tracks: ‘Past change’ and ‘Future scenarios’ (Figure 29).
The next two sections (C.1.1 and C.1.2) describe key components required to implement Track A ‘Past change’ of FishMIP 2.0. These include the development of a formal model evaluation framework to assess how well FishMIP models capture past catches, and improved realism in climate and fishing input variables to reduce key limitations and uncertainties associated with previous projections. Section C.1.3. focusses on Track B ‘Future scenarios’ of FishMIP 2.0, including the development of fishing scenarios and their implementation in all FishMIP models.