Blue crabs Callinectes sapidus and Portunus have been in chaos since arriving in the Mediterranean. With their long claws and voracious appetites, they have become the worst enemies of local fishermen.
Since 2006, a species of blue crab native to the western Atlantic has begun to be discovered in numbers on the Albanian coast: it is Callinectes sapidus, whose flesh is known to be delicious.
But the crustacean is also known to be very voracious and aggressive, so much so that it is now one of the 100 most invasive species in the Mediterranean and the Adriatic.
This year it has increased especially in Albanian waters to the great misfortune of local fishermen: “We fishermen are very worried, because the blue crab has starved everything, it destroys the nets, the fish, the eel on our waters has completely disappeared,” said Stilian Kishta, a Albanian fisherman, to AFP on July 24.
Callinectes sapidusa has also been discovered off some of the French and Spanish coasts. But at the moment, the situation is not yet critical, according to Christine Pergent-Martini, specialist in coastal ecosystems: “In France, we are happy to monitor these populations, see if they spread and whether or not they pose special problems in the new environments there. they arrive, she explains.
The Tunisian example
Tunisia first encountered another blue crab, cousin of Callinectes sapidus: Portunus segnis, from the Indo-Pacific region. In 2014, the spread began to become problematic.
Destroying everything in its path, has the nickname “Daesh” by Tunisian fishermen. The latter have expressed their concern on several occasions and in 2017 the state responded by launching a plan to exploit and develop this crab.
Fishermen were trained to exploit the species, which had not been fished before. Foldable versatile traps, more efficient at catching it, were provided, and the government began subsidizing the purchase price. by paying financial support for each kilopeached and sold.
Factories have also begun to produce frozen crabs for export, especially to the Gulf and Asia, where demand even exceeds supply.
Today, these exports make up the bulk of the profits from the sale of Portunus segnis. Crabs are also sold in markets in coastal Tunisian cities, but remain uncommon in the rest of the country.
A new, more aggressive crab
The measures that have been taken have helped to stabilize the species’ population. But Marouene Bdioui, a researcher at INSTM, admits that he is now worried about the arrival of Callinectes sapiduss on the Tunisian coast.
“It seems to me that this species is more valuable, there is more meat in Callinectes, but it is also a very aggressive species, he specifies. If the Tunisians think that Portunus segnis is aggressive, Callinectes is ten to me. Times more aggressive. Its pincers are larger, more robust … This species should be treated much more carefully than Portunus segnis. “
The researcher has already been contacted by European colleagues to discuss the measures to be taken before the spread of blue crabs. For him, this mutual support is important. Against this torment, “all Mediterranean countries must act hand in hand,” he assures us.