Alien species a mounting threat to seas’ biodiversity

The nets and longlines of fishermen in the southern Dodecanese islands and Crete are increasingly bringing in fewer fish, of which most are non-native species. 

Experts warn that the threat posed by growing numbers of invasive species – like the ubiquitous silver-cheeked toadfish – from warmer climates to marine ecosystems and fisheries is great. However, the state’s response has been nil, despite positive examples from neighbors like Cyprus and numerous scientific proposals and initiatives.

There are more than 1,000 alien species in the Mediterranean, with 650 of them having viable populations. Some 120 are invasive and pose a threat marine biodiversity.

“It’s a dynamic process, with six to seven new species being added every year. The empirical estimate is that 10% of them are trouble,” says Stelios Katsanevakis, a professor of marine sciences at the University of the Aegean.