According to the Biological Invasions Records journal, a Whitemargin Unicornfish, Naso annulatus, has been caught in the Maltese waters of the Mediterranean Sea. Native to islands as far apart as Hawaii and Madagascar this large species of surgeonfish is a seasoned traveler, but has never before been found in the Mediterranean until now. Despite its wide natural range, the Whitemargin Unicornfish is not found in the Atlantic Ocean, the only natural entrance to the Med, but there are three other ways that it could have got there. The first is that someone released it from an aquarium, although with a maximum size of 100cm they are not commonly kept in aquaria. Second is via cargo ship ballast water, the process where ships take on large amounts of water in one place and then release it somewhere else, and the third is that it simply swam there, via the man-made Suez Canal which now connects the Red Sea to the Mediterranean. It has been documented in the Red Sea previously and could travel up from East Africa.
It’s not the first non-native fish species to be found in the Mediterranean either, with records of Lionfish, Rabbitfish, Angelfish, Damselfish, and even Butterflyfish being documented previously. Invasives are a problem the world over on land and sea, fresh and saltwater, although in this case it was a single Whitemargin that was spear-fished in shallow waters, gutted, and later consumed. There is no evidence of a breeding population. Prior to the building of the Suez Canal in 1869 the waters of the Mediterranean and Red Seas hadn’t mixed for five million years, and neither had its wildlife. Now they are connected we expect to see further Lessepsian migration, especially from East African and Red Sea fish and invertebrate species which can now take the shortcut to new European habitats, either voluntarily or against their will and transported in ballast water as larvae.
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