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The lion’s new den: this poisonous fish is moving into the mediterranean

A lionfish (Pterois miles) hunts for food A lionfish (Pterois miles) hunts for food Laura d/Shutterstock
06 Oct
New research finds population levels of invasive lionfish are exploding across the Mediterranean

Marine biologists and divers familiar with the Caribbean and western Atlantic will know all about the problems caused by invasive lionfish (Pterois miles). Far from their native home in the Indian Ocean, a few individuals were infamously released (whether accidentally or intentionally is still up for debate) off the coast of Florida in the early 1990s. Within a decade they were fully established across most of the Caribbean and the Gulf of Mexico. Eradicating lionfish from this part of the world has become a priority for restoring the health of the regional marine ecosystem.

Braving deep into territory in which many believed they wouldn’t be able to survive, lionfish are now being discovered in increasing numbers in the Mediterranean. ‘The lionfish are expanding fast,’ says Demetris Kletou, Director of the Marine and Environmental Research Lab, a marine environmental consultancy based in Cyprus. ‘Last I heard, they have reached Tunisia.’

Prey is naïve and doesn’t recognise lionfish as a potential predator. It is also possible that potential predators do not recognise lionfish as prey

Kletou and colleagues, working alongside the School of Marine Science and Engineering at Plymouth University, have published their latest research, in which they found this alien and highly venomous species to be rapidly colonising the eastern Mediterranean. Both sea surface warming and the recent expansion of the Suez Canal have allowed the lionfish to colonise almost the entire southeastern coast of Cyprus in just one year.

‘Prey is naïve and doesn’t recognise lionfish as a potential predator,’ explains Kletou. ‘It is also possible that potential predators do not recognise lionfish as prey.’ With this Darwinian advantage, combined with high ecosystem versatility and fast reproductive rates (they spawn every four days, producing around two million buoyant gelatinous eggs per year), lionfish populations are able to grow extremely rapidly. This could lead to a devastating decline of local prey in the Mediterranean, as well as of other local predators who lose out through increased competition for food.

‘These impacts may also be felt by the fisheries and tourist sector,’ adds Kletou. ‘Incidences where naïve divers get stung by its toxic spines may also happen.’ He encourages rapid, targeted removal of the fish to try and stop the spread before it gets completely out of control.

This was published in the October 2016 edition of Geographical magazine.

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