Official figures point to trouble for Turkey’s diverse ecosystems, with more invasive fish species now calling the country home. In the country’s seas, 540 "alien" species and 105 invasive species were discovered. A 2020 census by the Directorate of Nature Protection and Natural Parks indicates 14 species were among the world’s worst.

The study by the state-run body is part of a project funded by the Global Environment Facility Trust Fund and United Nations Development Programme (UNDP) for the assessment of the threat posed by invasive species to marine biodiversity areas. The project aims to prevent the entry of invasive species into different ecosystems while overseeing their control and management.

In the waters of the Mediterranean Sea along the Turkish coast, the number of invasive species has exceeded 1,000. Turkish territorial waters in the Mediterranean have the highest number of invasive species in the country, at 413. In the Aegean Sea, 253 species were detected while this number was 124 and 28 for the Marmara and Black Seas, respectively.

The most dangerous invasive species spotted in Turkey include the lionfish, a venomous coral reef fish, silver-cheeked toadfish, stonefish, sea snail, nomad jellyfish and striped eel catfish. Invasive species cause economic, social and environmental problems, experts say.

Invasive species find their way into Turkish waters through a wide variety of ways. Some are legally or illegally brought into the country for aquaculture, for recreational purposes or to be kept in aquariums. Others enter the Mediterranean via the Suez Canal and ballast water discharge of ships arriving in the country from all around the world.