Growth pattern and exploitation status of two Corallium rubrum (Linnaeus, 1758) stocks in Sardinian waters (Western Mediterranean)

Red coral facies are key Mediterranean biodiversity hotspots that have suffered a dramatic decline due to intense fishing pressure and highly destructive trawling gears. Its extremely slow growth and long lifespan make red coral particularly vulnerable to fishing. Despite the growing interest in red coral biology and recent safeguarding actions by the General Fisheries Commission for the Mediterranean, its harvest status has rarely been assessed. In the Mediterranean context, Sardinia represents a unique case in terms of data availability on this precious resource, having always been a hotspot for red coral. The available morphological data for the north-western and northern Sardinian waters confirm a possible differentiation between the two areas, which were already considered to be genetically isolated at the time. Two stock assessment models, stochastic surplus production model in continuous time and Length Based Spawning Potential Ratio, were applied separately to the two stocks. Both showed spawning potential below the reference level (B/B MSY < 1), but the north-western stock is exploited below F MSY (F/F MSY < 1), while the northern stock exceeds this target (F/F MSY > 1). These contrasting stock statuses suggest that the current management measures need to be revised. In particular, adjustments to the Minimum Conservation Reference Size and permitted fishing effort are recommended to align exploitation more closely with the specific ecological and demographic dynamics of each population.