Invasive Crab: a Threat to Local Fishermen in Tunisia

a fisher holding a blue crab
Youth Magazine
Djerba, Tunisia
Invasive Crab: a Threat to Local Fishermen in Tunisia

Radhia Jouili still recalls the unwelcome guest who came to the shores of Djerba in the summer of 2014. "After we threw nets in the places where we always fished, we were surprised by a large number of crabs, some of whom ripped the sides of the nets. A number of fish looked mangled."

Radhia, 43, has been working with her husband Belgacem Chadi in the fishing industry for more than a decade. The couple wake at dawn, head to the Djerba-Ajim beach, and take their small boat out a few kilometers to fish for catch.

"From 2000 until 2012, fishing was profitable and my husband owned a larger boat and ran a team of five. But with young people reluctant to work in the fishing industry, declining fisheries and the health problems he has faced, Belgacem is now content with a small boat and I share the work with him to lower expenses,” says Radhia.

Radhia notes that the appearance of the crabs is their main challenge. The oyster populations that are traditionally fished in Djerba, for example, have been decimated by the crabs. “This aggressive creature invaded our waters and multiplied rapidly without us knowing the source, which frightened the sailors," she explains.

Fishers call the newcomer "ISIS" because it kills fish with its sharp front claws. The scientific name for the species – commonly known as blue crab – is “Callinectes Sapidus.

Although it was hoped the presence of this invasive non-native species would be temporary, the crabs have remained and even proliferated. Mitigating their damage is difficult, as they account for more than 70% of catches in Tunisia during the high season. For this reason, some seafarers have sought to make up for their losses by catching the crab and selling it to factories that export it abroad.

"Selling blue crab to factories is not a bad option, but its yield is weak and we have to sell it cheaply in light of the scarcity of customers,” says Radhia. “In addition to the price problem, factories only buy large crabs so half of our catch isn’t large enough, and the margin for negotiating better prices seems limited due to the low demand for crab locally."

Radhia reveals that she sells one kilogram of blue crab for around US $0.30 to $0.50 to factories that later package it and export it to many destinations, most notably Italy, Australia, and the United States.

While a number of processing companies refused to disclose the price of packaged blue crab, the French supermarket Carrefour sells it fresh for US $1.40 per kilogram.

For her part, the entrepreneur Najah Chaaban, who runs a marine canning unit in the Zarzis region in Tunisia, says that blue crabs have actually enhanced the income of the local community. She adds that her company employs more than 20 workers and has also provided dozens of "drayen" (multi-purpose cages made of plastic) to Zarzis sailors to keep their nets safe and enable them to catch crab more effectively. Chaaban’s outfit has many clients on the other side of the Mediterranean basin in Italy and southern Europe.

Tunisian authorities are likewise trying to break into new markets. Naila Nouira Ghonji, Tunisia's Minister of Industry and Energy, officially inaugurated a new South Korean industrial facility for processing blue crabs on March 7, 2022, in the Zarzis Economic Activities Space. The project is expected to create between 500 and 700 jobs in its first year.

In May 2021, blue crab exports comprised 2,091 tons worth US $7.2 million (about 19.6 million Tunisian dinars), more than double the exports for the same period in 2020, which did not exceed 796 tons worth US $3.1 million (or 8.6 million Tunisian dinars).

Blue crab in a shop in Tunisia
Blue crabs sold in a Carrefour shop in Tunisa, July 2022 / Credit: Achref Chibani.

Mystery of its source

After appearing sporadically in the 1990s, large incursions of crab occurred in the Gulf of Gabes (southeastern Tunisia) in 2014. The newcomer continued to proliferate on the North Africa coasts, where it was first seen in April 2017 west of the Libyan city of Tobruk. It was also spotted on the coast of the Algerian city of Jijel in 2018.

Though there are many theories of how the crab entered Tunisia, human interference is clear, with experts suggesting that merchant ships, especially oil ships, contributed to the new organisms invading the coast. Italian environmental and agricultural expert and president of the NGO “QG Enviro” Giuseppe Scandone says, "​We cannot imagine that​ the blue crab arrived to the Mediterranean alone, but with shipping, in the ballast water of the large ships that arrive in the ports and unload their shipments.​​"​

Similarly, Tunisian independent environmental expert Laroussi Bettaieb highlights that the ballast water used by sailors to balance the ship when it is empty is a suitable nesting environment for many invasive organisms that reproduce rapidly. Bettaieb further explains that random fishing on Mediterranean coasts reduced the number of the crab’s only natural predator, the octopus, allowing the blue crabs to destroy local mollusks.

Iraqi environmental expert at Akhbar Alan Khaled Suleiman considers climate change the main reason for the blue crab invasion due to warmer temperatures helping the crabs to establish themselves in the Mediterranean as an invasive species, noting that they arrive through water channels from the Suez Canal.

Suleiman warns that the crabs are a threat to biodiversity. Although the Mediterranean Sea accounts for less than 1% of the world's marine surface waters, it is one of the most important reservoirs of marine biodiversity, containing between 4% and 18% of the world's marine species.

Suleiman adds that affected countries must implement joint programs so that livelihoods are protected. This could include marketing crab both globally and locally. Moreover, according to scientists, if not addressed quickly rising sea temperatures in the Mediterranean basin could also cause a depletion of fish, bringing hardship to this region of more than 500 million people.

Lack of joint coordination in the Mediterranean

Though the blue crab is providing a source of seasonal income for some residents of countries bordering the Mediterranean, such as unemployed youth in Gaza (Palestine) and Larache (Morocco), government efforts in these countries to deal with the crabs’ influx appear modest and lack coordination, deepening the crisis of the fishing sector, which is already suffering from structural difficulties and overfishing by industrial-sized vessels.

To address this, Italian environmental and agricultural expert Scandone calls for investing more money in monitoring species like the blue crab, and in this specific case encourages fishermen to capture and sell the tasty delicacy to restaurants and citizens in order to control their population at sea.

“We already know that we can only adapt to a climate that is changing so fast, so we need to change our mindset and focus our efforts on creative solutions for controlling invasive species," he says.

In this context, Haithem Smida Guesmi, a Tunisian independent researcher in rural politics and agriculture, argues that neoliberal debt policies imposed on Arab governments have deepened the gap between the state and society, as governments have abandoned economic planning and the management of relations of production, exchange, and distribution and have turned toward the principle of "a whale eats a whale and little effort dies", a Tunisian proverb that means governments are not proactively dealing with issues but leaving them to private enterprise.

But if Tunisia and the wider region are to deal effectively with the blue crab problem, governments must unite to create policies and programs that not only address fishermen’s livelihoods, but the effects of climate change more broadly. This environmental invasion is one of myriad challenges affecting or soon to affect the region’s populations and their social and economic well-being. Robust state intervention prioritizing the environment is imperative.


This story was produced with support from Internews' Earth Journalism Network. It was first published in Youth Magazine on 17 October 2022 in Arabic. It has been translated to English and lightly edited for length and clarity.  

Banner image: A blue crab / Credit: MichalPL via Wikimedia Commons. 

By visiting EJN's site, you agree to the use of cookies, which are designed to improve your experience and are used for the purpose of analytics and personalization. To find out more, read our Privacy Policy

Related Stories