Blue Crabs and Lionfish: Dispatches from an Increasingly Tropicalized Mediterranean

I thought of dedicating an issue of this newsletter to Stefano Liberti’s new book as soon as I heard of its release. How couldn’t I? Simply by reading its title, "Mediterranean Tropic,” I could sense the many points of contact with this project as well as with one of the topics I fondly covered in the past few years: climate change, a shifting Mediterranean biodiversity and fisheries — by the way, it’s Guia writing here. Then, early last month, I received a voice message from Emanuele Biscotti, one of the fishermen who took me on his boat in Lake Lesina, in southern Italy, when I was reporting on blue crabs. Fishers there use long tubular nets ending in a sack called bertovelli, which allow a good portion of marine creatures to enter but not escape.

“This year is terrifying," he told me. “With 12 bertovelli, we’re catching up to 800/900 kilograms (nearly a ton) of blue crabs a day. Fishing has become impossible in Lake Lesina."

In Lake Lesina, bertovelli are used to catch primarily eel, mullet, sand smelt, seabass and seabream. Since much earlier than in the Po Delta area, 320 miles north, local fishers practicing the traditional paranza fishing system in this Apulian brackish lagoon have found their bertovelli full of a species not native to Mediterranean shores: the Atlantic blue crab. Throughout the years, a small market has developed around these newcomers. But when quantities rise as much as they did  this year, blue crabs lose nearly all of their value and the little they are sold for can’t even cover the damages they cause to fishing gear.

Receiving such a message reminded me of the relevance of these biodiversity shifts for coastal communities and the importance of providing a platform to those fishers who are affected but don’t receive the same attention as the clam farmers in the Po Delta region.

Then, more or less around the same time, I received an invite to attend a conference in late October at the University of Gastronomic Sciences in Pollenzo, Piedmont. Researchers from major Mediterranean institutions specializing in marine biology and exotic species gathered at the Slow Food-founded university to discuss ways to tackle another invasive species making its way into the Mediterranean: lionfish, and specifically to keep it from spreading like it already has in the eastern portion of the basin. It got me thinking that maybe what happened with the blue crab holds, at the very least, a lesson for someone.

The gathering included not only research institutions from Italy, Greece, Cyprus, Türkiye, Monaco and France, but also Greek and Italian NGOs working in dissemination, tourism and environmental protection, as well as entrepreneurs active in the private sector. The driving force behind the meeting — strongly supported by the Sustainability and Circular Economy Lab at the University of Gastronomic Sciences in Pollenzo and the Elafonisos Eco association — was the urgent need to take action before the presence of lionfish in the central Mediterranean reaches the quantities found in Greece, Cyprus and Türkiye. Actually, the idea is to learn as much as possible from what has already been studied and implemented in other Mediterranean countries — and beyond — to anticipate the expansion of this invasive species.

Lionfish sightings are still limited in Italy — with Calabria being a hotspot — but this may just be a matter of time. This fish species, native to the Indo-Pacific Ocean, has spread along the eastern Mediterranean coast in only five years. In Elafonisos, a Greek island south-east of the Peloponnese, the lionfish have been showing up in incredibly big numbers for the past three years. As a species adapted to more tropical climates and seas, a warming Mediterranean may have favored their installment in combination with other crises that have degraded Mediterranean ecosystems, leaving them less resilient to the arrival of new species, as Stefano Liberti highlights in his book “Mediterranean Tropic.”

“This sea used to play a major role in regulating the climate,” Liberti told me, discussing the title of his book. “There was a Mediterranean climate. Now, the Mediterranean is becoming a subtropical sea, and the same goes for its climate.”

This interview has been slightly edited for length and clarity and translated into English.

“Mediterranean Tropic” discusses exotic species, fisheries and pollution. What is the underlying connection between these varied topics?
A changing Mediterranean, in my opinion, is the underlying link. I’ve spent a lot of my career focusing on land: how much the climate crisis is impacting the Mediterranean area and, particularly Italy, with extreme events, droughts and other major environmental changes. Then I said to myself, Actually, everything starts with the sea. In the sea, the changes are even more profound than on land. However, this transformation is less visible and tends to be overlooked by the broader Mediterranean community. As I traveled with fishers, biologists and climatologists, I noticed that the climate crisis in the Mediterranean Sea is accelerating pre-existing ones: overfishing, resource exploitation, pollution and so on. In the book, I tried to bring all these elements together because it's not just global warming impacting the Mediterranean; it’s also the way the sea is used and the lack of its protection, which intensify the crises we’re witnessing. The spread of invasive species is just the most evident manifestation of those crises.

In the chapter on Cyprus, you highlight two different approaches to dealing with this change: one is more anthropocentric and the other is more ecocentric. Which one resonates more with you?
As far as I am concerned, I feel more in tune with the ecocentric view. That said, I understand that humans have always shaped ecosystems. They have always had this claim to live within ecosystems by managing them. I also realize that nature’s timing doesn't necessarily align with human timing. When there’s an invasion of exotic species, nature eventually finds its own balance. In the meantime, however, local communities will be affected. We’ve seen how invasive species are impacting the entire Mediterranean basin, affecting fishers as much in Cyprus as in Tunisia or in the Po Delta. But this phenomenon is simply a symptom of a broader crisis that tells us that we need a relationship with the marine ecosystem — and, I would add, the terrestrial one, too — of greater attunement and less exploitation. We need to re-establish the concept of limits because these exotic species also settle when certain marine ecosystems have been overexploited. The environment has become so degraded that some ecological niches have been left essentially vacant, favoring the installment of these new inhabitants in our sea.

Then, of course, some people say, ‘Okay, but now we have an invasion of pufferfish in Cyprus. How do we manage this?’ And they try to come up with circular economy solutions, like using pufferfish skins to make handbags. And it’s certainly better to use them as fabric rather than incinerate them in landfills, which would require additional energy and cause further environmental impact.

There are many ways to make use of invasive species. Some are also considering turning the pufferfish into fishmeal for aquaculture feed, for example, or there’s been a lot of talk about eating blue crabs.
When I talk about blue crabs, I’m often asked why Italy hasn’t taken the same approach as Tunisia, where they built 51 processing plants and created jobs. Of course, not everyone in Tunisia is completely satisfied with this. But it’s a strategy that has involved a wide range of actors: the government, biologists, researchers, fishers and so on. It’s a process that takes time. In Italy, the blue crab crisis notably exploded in 2023. I think that if the blue crab continues to be abundant, especially in the Po Delta region and keeps damaging shellfish farming, eventually Italy will also implement a more articulated strategy to turn this invasive species into a resource that can be exploited and even consumed. But the key issue here is time. It takes time to imagine, develop and put solutions into practice.