When blue crabs first started appearing off the coast of the island of Djerba in 2015, the island’s fisherfolk were afraid.
“Daesh had arrived. It was panic stations,” recalled Hakim Gribaa, 34, a fisherman and the president of Marine Fisheries Development Grouping in Ajim, Djerba’s biggest port.
Daesh is the Arabic acronym for the Islamic State of Iraq and the Levant (ISIS/ISIL), a name also given to the crabs for the terror they cause.
“This crab devours nets, bites fishermen, and reproduces very quickly. That’s why they call it Daesh: it’s an invader,” explained Fethi Naloufi, an engineer and head of the interprofessional grouping of fishery products (GIPP by its French acronym) in Zarzis, a public organization responsible for promoting fisheries and the aquaculture sector in Tunisia.
An even more serious problem: the crab eats all the other fish and has few predators. Scientists say this makes it an invasive species, introduced to the Mediterranean sea as a result of human activities.
Climate Change Driving Invasion
The blue crab (portunus segnis) originates from Indo-Pacific waters and reached the Mediterranean in 1898 shortly after the opening of the Suez Canal. Until the 2010s, it was mostly found in the eastern Mediterranean, where the waters are warmer.
“But its proliferation has been intensified by the warming of surface waters, as a result of climate change,” said Jamila Ben Souissi, researcher and teacher at the National Agronomic Institute of Tunisia.
As a recent WWF report stated, almost 1000 non-indigenous species are now present in Mediterranean waters warm enough to support them, spreading north and west every year and displacing resident species.
The blue crab was first identified off Tunisian coasts in 2014 by a Tunisian team that included Lotfi Rabaoui at the time a researcher at the Faculty of Science at the University of Tunis in El Manar. The crab already had an ominous reputation at that point. It was then later found on the Kerkennah islands before reaching Djerba.
“The blue crab has found everything it likes in the Gulf of Gabes. Climate change has favored its spread across our coasts, as shallow water and high temperatures are what it prefers,” explained Marouene Bdioui, a researcher at the State’s National Institute of Marine Science and Technology (INSTM by its French acronym).
The Gulf of Gabes, whose coastlines spans about 200 kilometers from Sfax to Djerba, is considered an important nursery for several fish species. It is also the source of about 40 percent of Tunisia’s national fish production. But climate change and the pollution from the State-owned phosphate company’s (Tunisian Chemical Group) factory in Gabes have changed the Gulf’s biodiversity. A growing number of invasive species have been detected, and the Mediterranean’s seagrass (posidonia oceanica), home to many endemic species, are on the brink of extinction.
Under the Ministry of Agriculture, the INSTM has been following the evolution of the blue crab since then. They explained that the crab can reproduce extremely quickly: up to four times a year, with litters of 100,000 per female.
Since then, everything has changed for those who make a living from fishing in the Gulf. Fisherfolk along the Gulf of Gabes coast have held demonstrations to alert authorities of the destruction the crab has wrought, calling on them to manage the problem.
Fisherfolk Lose Their Fish
There are 360 fishermen registered at the Ajim port in Djerba, among them Hakim. With the arrival of the blue crab, their livelihood was at stake.
“Before 2014 and the arrival of this crab, I worked day and night more than 300 days a year, as long as the weather allowed it,” Hakim told Meshkal.
Before the invasion, Hakim used to catch a wide variety of seafood: sea bass, sea bream, red mullet, mackerel, octopus. Today, it’s mostly just blue crab which has devoured the other fauna, as it eats almost anything, including clams, oysters, mussels, smaller crustaceans, freshly dead fish, and plant and animal detritus. And there are too few of its only two natural predators—the octopus and the sea turtle—to limit its spread.
“Since then, my work time has been cut in half. The blue crab represented almost 70 percent of my fishing [catches], and I did not know what to do with it,” Hakim said.
But today, Hakim has learned to live with the blue crustacean in his nets. In the last four years, fisherfolk have gone on the counterattack.
“At first, we were clueless,” said Naloufi of the GIPP. “We did not know what to do with all these crabs. They remained piled up in the port, or they were thrown back into the sea.”
Now, locals have begun to process and package the crabs in factories and market it for export worldwide.
“While waiting for a national strategy to be launched, collection centers were organized to enable fishermen to sell their hauls to nearby factories,” explained Naloufi.
The State Steps in with Support
Then in November 2016, the Agriculture Ministry subsidized the sale of the crabs in order to encourage fish factories to process and put blue crabs on the market.
“The State provided the fishermen with 1300 crab traps,” said Naloufi.
Initially, the Tunisian General Labor Union [UGTT] facilitated linkages between the fisherfolk and factories as the conduit for State subsidies. The UGTT would buy the crabs for 1.8 dinars per kilo and then sell them at a rate of one dinar per kilo to the factories.
Today, with the export market successfully launched, the price subsidies have been removed and fisherfolk directly sell their catch to the factories at the rate set by the State: two dinars per kilo.
“The blue crab market did not exist. Nobody consumes it in Tunisia,” said Samia Lamine, the coordinator for the coastal resilience project in Ajim, funded by the United Nations’ Special Climate Change Fund and the UNDP.
Aside from the State support setting up the market, other programs have also been set up to help fisherfolk adjust. Since 2017, at the initiative of fishermen’s groups (registered as GDAs, Agricultural Development Groups), the UN Development Program [UNDP] along with the Tunisian Coastal Protection and Development agency (APAL by its French acronym) launched programs to train fishermen to harvest blue crab.
Building a Better Crab Trap
Driven by necessity, the fisherfolk of Ajim have been improving their net designs to trap crabs.
“We had to invent everything, starting with new traps,” said Naloufi.
An initial attempt had a cylindrical-shaped trap with a single entrance for crabs. But after several new model updates, the latest generation has kept the shape but increased the entrances to four.
“All this came out of our imagination,” said Hakim. “We worked with blacksmiths to design our new work tool and received a 100,000 dinars subsidy from the UNDP [United Nations Development Program] and APAL.”
At the port, fishermen pile the “special blue crab”traps onto their boats.
“We drop the traps at sea, and we come to pick them up a few hours later when they are full,” said Hakim, who begins his days around three in the morning, while much of the rest of the island sleeps.
During the high season in July and August, each trap can net up to five kilograms of crabs, he said. The crabs are then sent to the many factories around the Gabes Gulf, including in Djerba, which process them for export.
“In Djerba, we rely on the quality of our crab. It is the best in the Gabes Gulf, because our waters are clean and rich,” said Naloufi.
Every year, the catch has been increasing. In 2021, fishermen in the region harvested more than 9,000 tons of crab, three times more than two years ago, according to Naloufi. Today, blue crab is the primary source of income for the majority of small-scale fishermen in the region, said Bdioui the researcher.
The reversal of the situation has also benefited the island’s community of women clam collectors, who had also initially fallen victim to the proliferation of blue crabs that shear off clam shells and eat them. Because of climate change, marine biotoxins have also been detected in the clams, depriving the women of harvest and income for two years, said Lamine.
“There are no more clams on our coast. No matter how much we dig in the sand, nothing,” said Lamine.
The clam harvesting is one of the most vulnerable to climate change coastal activities, according to a recent report by the Ministry of Agriculture about the impacts of climate change on food security.
But as the blue crab industry began to grow, former clam harvesters—many of whom are married to fishermen harvesting blue crabs—took a training program, run by the UNDP, to make hand-made fishing tools for catching crabs instead.
Return to sender
While the domestic market still doesn’t have much of a taste for the crab, fishermen swear it tastes good.
“It eats all the best mollusks at sea, this is why its flesh is so delicious,” joked Naloufi.
A few blocks away from the Ajim port, a big business group, Bena Pesca, opened a new crab processing plant towards the end of 2021 after it signed a partnership agreement with one of the fishing GDAs.
“We understood that there was an opportunity for us to enter a new market in Tunisia,” said Mourad Ben Ayed, the factory manager.
In the central room of the factory, about thirty women sort, wash and package the crabs caught earlier in the night by the fishermen. All of them said that they used to harvest clams on the shoreline before the crabs wiped them out.
Fida, who asked that her real name not be used, has worked at the factory since it opened.
“It’s not the same setting. I miss the sea. But I’m lucky to have stability, a fixed income, and social security now,” Fida said.
She described her new work processing crabs:
“It is a very delicate crustacean, which must be handled delicately. Very sensitive to heat, it must be packaged quickly, without any defect,” she said.
Once the washing is done, Fida lines up a dozen crabs in a small white box with inscriptions in Korean.
“Everything we pack here is sent abroad. For the moment, our best customers are Koreans. They love our blue crab,” explained Ben Ayed, the manager.
The Asian market is the top customer of Tunisian blue crab, an irony as the species originates from Indo-Pacific waters. The crabs are also sought-after in Italy, Spain, the United States, Australia, and Persian Gulf countries.
“It’s a shame that Tunisians don’t appreciate it,” said Samia Lamine, the coastal resilience project manager in Djerba.
In Djerba, the blue crab sold at markets is reserved for foreign vacationers. The French supermarket chain Carrefour is the only place on the island selling to local consumers.
“We can’t sell them directly in our markets; Tunisians wouldn’t buy them. They’re too scared by its appearance,” said Lamine.
However, Lamine hopes this will change and that locals will develop a taste for the crab.
“With the GDA, we have organized festivals and fairs at Ajim’s port to introduce the blue crab [to Tunisians] through new recipes,” she said.
The “Bleu-adapt”, an EU-funded project implemented by Tunisia’s Ministry of Agriculture, was set up in 2019 to study and respond to the blue crab’s invasion at a national level. In October 2022, the project will organize the first blue crab festival on the island of Kerkennah.
“Now we want it to stay”
In the Gabes Gulf, almost all the fishermen had initially seen their professional activity affected and their income reduced by the presence of the blue crab.
“But today, blue crab is our primary source of income. In the high season [from July to September], we can earn up to 2,000 dinars per month. It’s even more than before,” said Hakim.
While the initial invasion wiped out some of the marine ecosystem, the intensive fishing of the crab is now helping the local ecosystem recover somewhat, said Bdioui, the researcher from INSTM.
“We have observed a notable decrease in their numbers. This is also confirmed by the fishermen,” said Bdioui. According to his research, the average blue crab biomass in the sea was 34,000 tons in 2018, against 11,000 tons in 2020.
“However, it is not very clear whether this new activity has had an impact on the return of other species, especially if they are of commercial value,” he said.
While a whole new global supply chain is being built around this shellfish, there is a risk that it could disappear as quickly as it arrived.
“In Egypt, where the species entered the Mediterranean, stocks are almost exhausted today because of overfishing,” warned Naloufi. Turkey also saw its stocks perish due to overfishing.
In 2021, exports of Tunisian blue crab reached 7600 tons, which brought in 75.6 million dinars, twice as much as in 2020, according to the Zarzis interprofessional grouping of fishery products. In Tunisia, more than 30 factories process the crabs, and that number has been steadily increasing, exporting them to 27 countries.
For Hakim, the risk of overfishing in Tunisia now represents a threat to his work. According to him, the crab is attracting a growing number of investors because of the economic potential it represents, but that investment will help big businesses at the expense of small fisherfolk.
“These investors use fishing methods much more efficient than ours, including trawlers that scrape the seabed. Bottom trawls and other kinds of non-selective fishing equipment cause harm to other fisheries and to the marine environment by catching juvenile fish, damaging the seafloor, and leading to overfishing. The current national strategy tends to benefit them more than the small fishermen,” he said. For him, the State needs to regulate the sector.
Marouene Bdioui the researcher is of the same opinion.
“We have mobilized in an effort of resilience and adaptation. It is now necessary that this becomes sustainable,” he said. According to him, this kind of fishing has to remain artisanal. “Small-scale fishermen, who are the most vulnerable, now wish to maintain the presence of crab, and we must listen to them.”
In order to regulate it in a way that protects small fisherfolk, they say that the State will have to treat the crab like other marine species: prohibiting fishing out of season and during reproduction and imposing a minimum size below which it is forbidden to collect shellfish.
Aside from protecting the crab for fisherfolk who make their livings, there is also the challenge of protecting the local ecosystem.
“We need to set up systematic adaptation measures, as we did for the blue crab, in order to keep the balance in our ecosystems and economies,” said Adrianna Verges, a researcher on the ecological impacts of climate change at the University of New South Wales in Sydney.
According to Verges, one way to manage that might be to establish “Marine Protected Areas, to increase the biomass of large predators capable of consuming the blue crabs.”
Whatever steps are taken to balance the ecosystem and protect local livelihoods, Bdioui said such “good practices” should be put in place soon to make sure that the blue crab opportunity doesn’t again become a curse.
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