Illegally fished old precious corals: first taxonomic survey of the shallow water black corals from the southwest of Madagascar and insights on their age

Antipatharians, called black corals, are marine organisms living for the most part deeper than 100 meters. These corals have attracted people for a long time. Historically, they were used by religious people and for medicinal purposes, but nowadays they are mainly collected for jewellery. Small black coral fisheries have always existed around the world until it became an important source of income in several regions. Except in Hawaii where these fisheries are well known, black coral harvests are usually made without any control or any management. This is the case in many tropical islands and particularly in Madagascar, where an illegal trade is occurring. Since 2011, traffic of black corals has been expanding in the main cities of the southern and coastal regions of the country. Despite this and the continual harvesting of these natural resources, there has been no study of the excessive exploitation in this region until our enquiry. Species from the Indian Ocean, and especially from Madagascar, are completely unknown. Numerous species of the Indian Ocean have been described from incomplete specimens or with a lack of clear taxonomic traits more than a century ago. A lot of type species of the Indian Ocean are lost or missing, which makes more difficult the identification of the species. For the first time in the Indian Ocean region, we described a black coral bed in the north extremity of the Great Reef of Toliara, , and we made the first taxonomic survey of the shallow waters corals of the southwestern coast of Madagascar, resulting in the inventory of 18 species. Because poachers and fishermen are always looking for the longer and larger colonies, we also decided to make radiocarbon dating measurements on some specimens. We sampled whip black corals which appeared to be approximately 70 years old when measuring 3 meters in height.