Epsilon Archive for Student Projects

Abstract

In the face of current deterioration of marine ecosystems management aimed at restoring and conserving marine habitats is important. In Sweden there is a national call for increased ecosystem-based management (EBM) in the Baltic Sea, where overfishing and eutrophication are of growing concern, to preserve biodiversity and secure the provision of ecosystem services. Simulating the outcomes of management frameworks can be especially relevant for marine systems, due to the high uncertainty related to assessment of marine habitats, and modelling of different scenarios may also be useful to optimise the effect of management. Fuzzy cognitive
mapping (FCM) is a modelling approach that can be used for such evaluations. In the southern Bothnian Sea a regional management framework, as well as a fuzzy cognitive map of the socioecosystem, have been developed by local stakeholders and scientists from the Swedish University
for Agricultural Sciences (SLU). The aim of this thesis was to investigate how FCM modelling could be used to support EBM, by assessing potential effects of the management measures of the Southern Bothnian Sea, considering emerging trade-offs and synergies, and by developing scenarios for herring management.

One of the central findings includes the importance of submerged aquatic vegetation (SAV) in the
system. Measures that benefitted vegetation generally had positive effects on the rest of the system, while measures that were negative for aquatic vegetation generally negatively affected other ecological components and ecosystem services. This contrasting effect on vegetation is one example of a trade-off between measures identified in the analysis, while synergies found included measures related to herring management. The results also suggested that management focused on herring would benefit from the use of long-term management measures and marine protected areas (MPAs), instead of, for example, setting annual fish quotas. Depending on the preferred outcome of stakeholders these results could be used to discuss how measures can be adjusted to increase their positive effect on the socio-ecosystem, and how to avoid potential conflicts. FCM modelling could therefore provide managers and stakeholders with a deeper understanding of system interactions, while highlighting current perceptions of the system. In the context of EBM, where analysis of whole social-ecological systems is of use, such insights may be especially relevant.