An alien species in Tunisian waters
Over the last decade, the Mediterranean ecosystem has drastically changed due to climate change, populating itself with alien species that endanger biodiversity and, in some cases, the livelihood of communities.
The blue crab (Portunus Segnis) is an invasive alien species from the Red Sea that has settled and proliferated in several Mediterranean seas, including the Gulf of Gabès in Tunisia. Arrived in 2014, with a demographic explosion in August 2015, the crab found favorable conditions for its settlement thanks to the vulnerability of the ecosystem and climate change. Expanding rapidly throughout the gulf, it has become a dominant species which, together with pollution and intensive fishing, contributes to the decline of marine biodiversity, feeding mainly on crustaceans, molluscs and fish.
Daesh is the nickname used by Tunisian fishermen to name it, chosen precisely because of the devastating impact on the ecosystem and on the fishing nets, cut by the power of its claws and the thorns around them. The proliferation in Tunisian waters meant that nets and pots were filled almost exclusively with the voracious blue crab. To cope with the problem, the fish market has successfully worked to reconvert fishing and processing techniques, and sell Daesh in the foreign market, where it is very successful. However, for small fishermen, the situation is still critical since the purchase price of the crab is lower than that of marine species caught before its proliferation.
I chose to investigate this phenomenon in the Kerkennah Islands, following the activities of two small fishermen, Sara and Mohamed, the factories converted for processing and export to the food market; with a look that also pays attention to all the causes that threaten the ecosystem of the island.