Managing sustainable sea urchin fishery and marine forest conservation – MUrFor

MUrFor acts at the interface of ecosystem dynamics, habitat conservation and resource use by exploring sustainable management options for sea urchin fishery in tri-trophic systems with fishes, sea urchins and macroalgae. Macroalgal forests enhance coastal primary productivity, maintain high biodiversity and provide ecosystem services, including habitat for commercial target species. This ecosystem is affected by multiple human pressures leading to contrasting responses. Overfishing may impact macroalgal forests by reducing predatory fish numbers: this results in the loss of predator control on herbivores (sea urchins), and in their uncontrolled proliferation, with consequent loss of habitat structure. In contrast, sea urchin overharvesting can lead to local population collapses. In the Mediterranean Sea, both sea urchins and fish constitute locally important target species for small-scale fisheries. Uncoordinated management can result in overfishing of either or both resources, and/or in overgrazing of macroalgae, leading to habitat and biodiversity loss and to permanent regime shifts. Although this situation is common in coastal systems, there are hardly any examples of effective coordinated management of fisheries and habitats. MUrFor sets out firstly to improve our understanding of coastal ecosystem dynamics and their relationship to environmental variability in the context of alternative stable states. The objective is to identify critical thresholds leading to irreversible regime shifts on the habitat (overgrazing), the resource (overharvesting), and the fishery (economic sustainability). This will be achieved through a multi-modelling approach based on a suite of single-species, multi-species, ecosystem, economic and bio-economic models, which account for multispecies dynamics and socio-economic analyses of relevant scenarios emerging from stakeholders. Models will be informed by tailored in-situ experiments and stakeholder engagement exercises. Study areas will be based on two contrasting regional conditions: Catalonia (Spain), where the reduction of seabreams is leading to widespread barrens; and Sardinia (Italy), where intensive sea urchin harvesting has resulted in the collapse of local populations and of the related fisheries. These contrasting situations will serve as a benchmark to assess how effective ecosystem-based management of the fisheries and the habitats, tailored to local specificities, may deliver reasonable trade-offs between conservation and exploitation. Through active stakeholder engagement, the project will develop a toolbox to co-design an actionable research/management program for both marine forest conservation and sustainable sea urchin fishery. The toolbox includes a “best practice” manual of sampling protocols, multiple support tables and a management decision tree describing how the framework has been applied and can be exported elsewhere, and a visualization tool to showcase general results as examples.