Por Dorota Szalaj (Instituto Dom Luiz, Faculdade de Ciências da Universidade de Lisboa).
Depletion of fish stocks worldwide signal a failure of conventional fisheries management practices and ineffective governance. Therefore, the scientific community and Common Fisheries Policy (CFP), emphasise the necessity to integrate environmental concerns and move towards a more holistic ecosystem approach to fisheries management (EAFM). Key characteristics of this approach include multispecies consideration, trophic interactions, socio-economic dimension, and impact on habitat and ecosystem. Consideration of EAFM, in Portuguese continental waters is especially important, taking into consideration, severe decline in sardine biomass, observed in the Iberian waters in the last decade. As a result, a framework that demonstrates the utility of GIS to support fisheries management in the context of an ecosystem approach, has been developed. Design of the framework includes five scenarios that enable not only to identify the areas that are of highest importance to conservation but also, to address multiple conflicting objectives and imply trade-offs between conservation and fisheries objectives. The analyses indicate that some areas are suitable for conservation in several scenarios, such as the area near Aveiro and the area near the Tejo estuary. However, conservation measures implemented in the area near Aveiro would imply higher economic trade-offs when compared with the actions applied in the region near the Tejo estuary. Results also suggested some of the conservation objectives, such as the protection of sardine eggs and juveniles, to not be compatible. Moreover, a time-dynamic ecosystem model (Ecosim) representing Portuguese continental Shelf ecosystem (PCSE) was developed in order to explore the drivers needed to simulate the observed food-web dynamics between 1986 and 2017. The preliminary results, showed that the main drivers that explain ecosystem dynamic in the studied period, are trophic interactions considered with fishing followed by environmental factors. When considering only sardine dynamic, the main contributors to its changes are trophic interactions and fishing. The development of both methods, GIS framework that can address conflicting objectives during conservation sites selection process, and dynamic ecosystem models that improve an understanding of the complex ecosystem dynamics and its drivers, demonstrate their importance as useful tools supporting EAFM in Portuguese waters.
