Sophisticated computer simulations can support effective science-based evaluations to facilitate better governance of the marine space with evidence-based policies. We developed a range of spatial fisheries models, integrating biological with fishers´decision-making dynamics and management for assessing the management of multiple activities. We present the outcomes of case-specific evaluations with different ecological and socio-economic characteristics i.e. Adriatic, Ionian, Black, Baltic and Celtic Seas, and priorities like fisheries, aquaculture, offshore wind energy or conservation areas. For each case, we applied the DISPLACE agent-based modeling platform for simulating bioeconomic dynamics and clarifying options for sustainable and viable fisheries in presence of other marine sectors. The work is ongoing and we foresee clear outcomes delivered by mid-2019.
The ban on discarding unwanted fish overboard when fishing, which was decided during the last 2013 EU Common Fisheries Policy reform, requires that everything retained in a commercial fishing gear is recorded and counted against fish quotas when some exist like in Northern European waters. It is, however, difficult to reduce catches of a single fish species when a variety of fish is generally caught together. This creates a risk for early closures of fisheries when the quota of one fish (the “choke species”) is exhausted before the others. To cope with this and avoid an unnecessary low rate of quota utilization, fishermen can try to lease extra quotas, or modify their catches, either by switching to more selective fishing gear types or through changes in when, where and how to fish, by trying to avoid areas where there is a fair amount of possible choke species, and displace the fishery as soon as a large catch of choke species is encountered. This ability to displace will depend on the skills and choices of the skipper but also on how the fish stocks distribute in space and time (patchily vs. evenly distributed). We are developing here a platform to test such interlinked effects in a clear and detailed manner by accounting for varying skipper’s decision-making, such as for example the one described in the adjacent decision tree.
By analyzing fishers´ decision making consequences and predicting likely responses of fisheries to spatial management options, the DISPLACE modelling approach is assessing whether actual fishing opportunities and technical management measures (e.g. regulation of gears, spatial restriction for fishing, etc.) perform well by ensuring sustainable fishing and food provision to the value chain without affecting important fisheries economics. In this context DISPLACE now provides scenario-based assessment and projections of the amount of income generated by national fishing fleets (or other finer fleet segments level economics and fishing harbor communities) over months, quarters and years as long as national input data are available.
On this issue, important results have been obtained in a row of applications including the Adriatic Sea CS (paper here), the Ionian Sea (in progress), the Black Sea (in progress) and the Baltic Sea CSs, with ongoing data conditioning for the Irish Celtic Sea, some Norwegian Fjords and NE Atlantic Coasts in Portugal.
With our approach we aim at modelling the interaction between fisheries and stock spatial dynamics and assessing the interlinked consequences on both the vessel economy and the viability and sustainability of the harvesting (including the issue of energy efficiency for greener fisheries). We explore alternative fishing effort allocation scenarios and management options. As such, we are designing a benchmark tool for conducting management strategy evaluations to capture short-term economic reactions from individual fisherman tactical decision-making.
In the growing marine spatial planning (MSP) legislative context, concurrent uses of the sea are constraining the possibilities of displacing each vessel´s fishing activities. These new constraints call for studies that would empower the fishing industry with the right tools and knowledge to engage in fair MSP dialogues. We should consider the impact assessment and scenario evaluation of wider marine cross-sector use, exploitation of the marine environment and competition for space in a spatial evaluation tool and our ongoing evaluation is precisely dedicated to investigating this aspect.