The number of recorded non indigenous species (NIS) in the Mediterranean Sea is far higher than in other European Seas; their number more than doubled between 1970 and 2015, with the greatest increases recorded in the 1990s and the 2000s. Though States are responsible for ensuring that activities within their jurisdiction do not damage the environment of other States, effective implementation of the IAS regulation (EC 2014) concerning marine NIS in the Mediterranean Sea depends on policy coordination with the Regional Sea Convention (Barcelona Convention). At the Ordinary Meeting of the Contracting Parties to the Convention for the Protection of the Marine Environment and the Coastal Region of the Mediterranean and its Protocols (Greece, February 2016) the parties adopted the ‘Updated Action Plan concerning Species Introductions and Invasive Species in the Mediterranean Sea’. This plan focuses on the collection of data and the further development of the Marine Mediterranean Invasive Alien Species Database. The plan lacks management actions to prevent NIS introduction, control their spread, and mitigate the damage they cause to the marine ecosystem.