Study on fisheries resources with particular reference to red coral, spiny lobster and other target demersal species in Sardinian Seas

This PhD thesis contributes to the sustainable management of marine resources in Sardinian waters by addressing critical knowledge gaps in the assessment of key commercial species: red mullet (Mullus barbatus), red coral (Corallium rubrum) and spiny lobster (Palinurus elephas). These resources represent both ecological keystones and economic pillars for regional small-scale fisheries, yet have historically suffered from insufficient scientific evaluation. The first part of the research presents the inaugural stock assessment of red mullet in Geographical Sub-Area 11 (GSA 11), using data-rich, age-structured models (Extended Survivors Analysis, XSA). The results revealed a sustainably exploited stock, suggesting opportunities for adaptive management and compensation for effort restrictions under the Western Mediterranean Multiannual Management Plan. The second part focuses on red coral, applying a suite of data-poor models (CMSY, SPiCT, and LBSPR) to two distinct populations in northern and north-western Sardinia. This novel application highlighted key biological differences and unsustainable exploitation under current legal size limits. Area-specific management recommendations, including revised minimum conservation reference sizes and effort reductions, were proposed to promote long-term sustainability. The third part delivers the first stock assessment of spiny lobster in the Asinara Marine Protected Area (MPA), revealing overexploitation driven by a mismatch between capture size and maturity. This assessment establishes a critical baseline for future MPA performance evaluations and highlights the utility of length-based methods in data-limited contexts. Overall, this thesis integrates modern stock assessment approaches with local monitoring data to deliver actionable insights for management. It reinforces the value of combining biological evidence and adaptive strategies in Mediterranean fisheries. The outcomes support the development of sustainable, resilient fisheries policies in Sardinian waters, aligning ecological conservation with socio-economic viability.