Status of alien species in the Mediterranean and Black Sea

This study, undertaken upon request by the General Fisheries Commission for the Mediteranean (GFCM), summarizes
the available information about the status of alien species in the Mediterranean Sea and the Black Sea. The biota of the
Black and Mediterranean Seas has started to change with the introduction of alien species in the last few decades due
to increasing shipping activities, lessepsian migration, Atlantic influx, intentional or unintentional introduction as well
as climate change.
In total, there are over 900 alien species in the Mediterranean and the Black Sea. Several fishing techniques such as
trawling, purse seining, setnets, gillnets and pots are used for alien species fishery. Due to a lack of overall statistics,
total catch in the entire basin is not known and not predictable. Some alien fishes which do not have any commercial
value, such as pufferfish and cornetfish, are discards. Some Atlantic-originated fish and invertebrates have also
extended to the eastern part of the Mediterranean Sea. Besides, ship ballast water and intentional and unintentional
introduction are growing threats for marine biodiversity in both basins.
Information dissemination and raising public awareness, mostly for harmful species, are therefore particularly
important at a regional level. Moreover, regional cooperation for monitoring and protecting marine biodiversity is
essential to minimize and reduce the impacts of alien species both in the Mediterranean and Black Sea. Finally, the
enforcement of the legal measures is necessary to reduce the introduction of alien species.
Examples of alien species:
1. Rhopilema nomadica; 2. Mnemiopsis; 3. Fistularia commersonii; 4. Lagocephallus sceleratus; 5. Calinectes sapidus; 6.
Rapana venosa; 7. Diadoma setosum.