FAO 19/10/2021

Figure: The blue crab was initially a disaster for fishers, ruining nets and traditional fishing techniques. ©FAO/Valerio Crespi.

"It eats everything, leaves nothing and reproduces very quickly," laments Mouradh, a fisherman from the Tunisian islands of Kerkennah. For the country’s fishers, the blue crabs that were being hauled out of the water, tangled up in their broken nets, were a disaster.

An invasive species introduced into the Mediterranean through the Suez Canal, the blue crab threatened the artisanal fishing techniques used along the Tunisian coastline, specifically damaging the gillnets and traps used in the Charfia (a traditional, fixed fishery system that blocks the path of fish and leads them to traps). With their sharp shells and claws, blue crabs ruin these fishing nets and feed on other fish species also caught in the nets or traps.

Blue crabs were first found off the Tunisian coast in 1993. By 2014, they began proliferating massively, causing significant damage to the coastal artisanal fishing sector, especially in the Gulf of Gabès in southeast Tunisia, where, during the high season, the blue crab represented more than 70 percent of the catch off this Mediterranean gulf.

These predatory crabs compete with indigenous species for space and food. They feed on all other species of fish, and its only natural predator, the octopus, is not enough to limit its spread. By disturbing the natural ecosystems, the blue crab has also negatively affected the yields of Tunisian women clam collectors, who were supported by FAO to improve their household incomes.

See https://www.fao.org/fao-stories/article/en/c/1443166/