SEAwise report on predicting effect of changes in ‘fishable’ areas on fish and fisheries

The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management (EBFM) in their fisheries. This SEAwise report aims to investigate the available tools for predicting the impact of various spatial management options on fisheries distribution, yield, profitability, and selectivity. Such spatial plans may affect the remaining ‘fishable’ areas by displacing and concentrating the fishing pressure, and so may alter stock abundances, distributions, size- and species catch composition and fuel expenditure and cost. The report provides early insights into how spatial plans that exclude certain fishing activities may affect these outcomes. Spatially explicit approaches are used, along with scenarios of underlying stock productivities and distributions, to assess the performance of spatial management measures. Scenario-based testing is conducted to examine the interrelated effects of management options and stock productivity. A major aspect of the work involved gathering and organizing information on specific zones from several sources such as Natura2000, CDDA, SPA, SAC, and UK-defined areas. We found that most of these zones did not have any previous management plans in place that would outline fishing restrictions. Therefore, we developed a method of assigning limitations to certain fishing techniques based on the perceived vulnerability of specific areas to these practices. This approach has allowed for an examination of how these restrictions potentially affect fish and fisheries.

Initially, we used a static approach in anticipating the potential fishing effort displacement to measure the impact of fishing in the Northeast Atlantic area. Our research shows that while such spatial management measures may reduce fishing opportunities, it may be possible to offset in the short term some of these spatial opportunity losses by fishing in nearby locations (Figure 1). On the Med side, an analysis of fishing effort displacement from restricted areas in the Adriatic Sea is exemplified in a before/after situation, showing that the effort is not reduced but redistributed and can further redistribute far from the restricted areas.

If in the short term, spatial management may increase operating costs by displacing the effort, this may eventually be recovered in the long term if the stock is recovering from previous overfishing. To determine whether conservation measures (such as Marine Protected Areas) that limit specific fishing techniques and areas could help mitigate the negative effects of fishing, a more advanced approach to fisheries management is required. This involves using a dynamic approach deploying spatial bioeconomic models that consider changes in environmental drivers and spatial restrictions, allowing it to assess potential changes in fishing effort facing, for example, new regulatory or ecological conditions. While bioeconomic models require more data and assumptions to forecast "alternative futures", they offer a more comprehensive approach to fisheries management, which is particularly useful as testing MPAs effects in real life is a challenge. A suite of bioeconomic models have been deployed to provide preliminary findings about the effect of spatial restrictions on fish, fisheries, benthos and bycatch.