Sighting of a red coral [Corallium rubrum (Linnaeus, 1758)] population living at Gibraltar Strait

Red coral has been overexploited in the Mediterranean for more than two thousand years, being probably the marine species of highest economic value in this sea. Shallow populations have long been overharvested due to their accessibility and this has caused a clear regression within its distributional range. However, the information available on the red coral is limited, and mainly focused on the Northern Mediterranean (Ligurian coast of Italy, France and NE Spain). Considering this, a dense shallow (15–25 m) population in the Southern coasts of the Strait of Gibraltar was found in 2014, where the species is currently rare. Analyses on size, density, branching pattern and age were carried out, as well as the description of the associated vagile macrofauna. The results of the current study indicated that the red coral showed a good conservational status in this area, achieving greater density (166 ind/m2) and size (6.37 mm of mean basal diameter and 62.11 mm of mean height) than many other populations already studied in the Northern Mediterranean. The estimated age ranged from 15 to 27 years. Dealing with the associated macrofauna, species richness and abundance were low in comparison with other corals and gorgonians from surrounding areas and could be explained by the small size of colonies and the trophic strategy of the species. Demographic results and the shallow location indicate the relevance of isolation and actual protection (military, in this case) for the conservation of this overexploited coral.