Diver Matteo Cavessi removes the venomous spines of a lionfish. Photo / Adrienne Surprenant, MYOP, For The Washington Post
A month earlier, the two divers had scoured this exact seabed, spearfishing a single species until the craggy floor was nearly bare.
Now, they cut the engine and wriggled into their wetsuits. Two empty coolers waited on deck. They suspected the same fish had returned in force.
“Let’s see,” said Matteo Cavessi, and he slipped into the water.
As the Mediterranean sets warming records, scientists point to a spiky marine intruder – the lionfish – as the warning siren.
The fish, native to the tropics of Southeast Asia, slipped in more than a decade ago through the Suez Canal and is overtaking the azure waters around Greece, Cyprus and Lebanon.
Researchers predict that its territory, expanding by the day, might eventually reach all the way to Spain.
While the Mediterranean, like any sea, teems with non-native species, the lionfish is almost singularly damaging, and it has the potential to upend a vast marine environment that has sustained civilisations for millennia.
It devours shrimp, crabs and smaller fish, its stomach swelling 30-fold during a feeding frenzy.
It is also a hardened survivor, capable of going a month without food. Its venomous spines deter any would-be predators. And a single female can spawn two million eggs in a year.
“They will massively disturb the ecosystem,” said Jason Hall-Spencer, a marine biologist at the University of Plymouth. “It is the fastest-invading fish in the world.”
To slow the spread, divers are holding hunting derbies off the coast of Cyprus.
Environmentalists are trying to build demand for buying and eating lionfish – emphasising that, yes, they are delicious fried or in soup.
When Greece’s Parliament held a special hearing this year on the invasion, one researcher said that the Greek seafood diet hadn’t changed much for 3500 years – but that climate change and other human activity was shifting the make-up of the local catch toward lionfish and other non-native species.
“It’s absolutely changing in front of our eyes,” said Anastasia Miliou, scientific director of the Archipelagos Institute of Marine Conservation, a Greek non-profit.
Over the past four decades, the Mediterranean has warmed by 1.5C.
It is lashed frequently by blistering marine heatwaves – including a record-breaking temperature spike earlier this northern summer.
One research study published last year, modelling the lionfish’s expansion, said the warming had created conditions similar to the lionfish’s native Indo-Pacific, “allowing the species to survive and reproduce in areas previously too cold for them”.
With the lionfish preferring to hide out in rocks and crevasses near the seafloor, divers are the best witnesses to the takeover.
Around the Greek island of Elafonisos, there is no better diver than Cavessi, 49.
He learned to love the sea as a teenager after a doctor prescribed water as a therapy for claustrophobia. Cavessi, ponytailed and wiry from his aerobic bike training, can plunge as deep as 42.5m without oxygen.
On his lionfish expedition last month, Cavessi stayed briefly at the surface, bobbing while he scanned the depths through his snorkelling mask. Then, spear-first, he descended 15m until he was eye-to-eye with whatever was hidden in a jagged maze of rock.
He fired his weapon.
He returned to the surface with a plump, foot-long lionfish skewered on the endpoint of his spear.
“They’re here,” he said.
For the next three hours, Cavessi and fellow diver Aldo Babbone carried on with what seemed like – under most circumstances – a triumphant day of fishing.
The sun shone. A mound of fish rose from the hatch near the boat’s motor. The work was easy; the fish, languid in their hideouts, barely even moved.
“There’s two in the same stone,” Cavessi told Babbone as they made one last descent.
But when they climbed back aboard, more than 40 lionfish filling the cooler, Babbone said the experience had been unsettling. The abundance was an environmental “catastrophe”, he said.
They sat at the edge of the boat, opening the fish, cleaning out the organs, clacking shards of spine and fin into the water. A few seagulls swooped in.
Cavessi started the motor and returned to port.
“Two weeks from now,” he said, “it’ll be as if we were never here.”
As far as intruders go, lionfish are dazzling to behold – at least from a distance. They are banded in flowing white and orange stripes. A line of venomous spines, resembling a mohawk, runs across their topside. Their fanlike fins seem borrowed from a dragon.
“They are beautiful,” said Paraskevi Karachle, who studies fish as an ichthyologist for the government-funded Hellenic Centre for Marine Research in Greece.
The global track record for controlling the lionfish, once they start to feel at home, is not promising.
Starting in the mid-1990s, lionfish emerged in a different region – around Florida and the Caribbean – most probably after being dumped into the ocean by aquarium owners who wanted the predators out of their tanks.
There, they gobbled up snappers and groupers – favoured fish for restaurants in the Caribbean.
They put stress on coral reefs by devouring herbivorous fish that control algae growth, allowing algae to overgrow and leaving coral to suffocate.
And – perhaps most discouraging – they prevailed despite significant human efforts to stop them.
Caribbean Governments waived restrictions in marine-protected areas to allow the hunting of lionfish. The Bahamas issued prize money for “removal” competitions, with teams catching 2000 lionfish in a single day.
Little of it mattered.
Scientists call the lionfish’s Atlantic expansion one of biggest marine invasions on record.
As a result, marine researchers in the Mediterranean have been left reaching for last-ditch ideas.
Several companies have piloted autonomous lionfish-hunting robots. And engineers have devised lionfish traps – though the logistics and cost of dispersing them across the world’s biggest semi-closed sea seems unfathomable.
“You’d need people to deploy them, maintain them – it’s just too big,” said Davide Bottacini, a doctoral researcher studying lionfish at Wageningen University in the Netherlands.
Other researchers have floated the idea of creating a saline barrier at the mouth of the Suez Canal – essentially re-creating an unpassable zone of salt that used to exist naturally before the canal’s expansions. That would limit further break-ins of non-native species.
But the lionfish is already inside.
Karachle said the best tool for slowing the lionfish’s spread might be the most obvious one: putting them on restaurant menus and stoking a motivation for fishermen to catch them en masse.
“The most promising option,” Karachle said, “is eating them.”
If the vision of widespread lionfish consumption has an evangelist, it is Enrico Toja, an 82-year-old Italian who spends summers on Elafonisos, uncorking great wine bottles while orbited by a mix of friends and adult grandchildren.
Although Toja spent his career far away from the ocean – as a corporate manager – he also started an environmental NGO, which is now working on lionfish.
He has tapped a network of contacts with the goal of turning the tiny fishing island – home to several hundred fulltime residents – into a hub for studying and cooking the spiky fish.
His vision: lionfish carpaccio on menus across the Greek islands.
“A dream, but oh well,” Toja said. “If you have no dream, you have a boring life.”
Elafonisos, though, is also a microcosm for the difficulties that can come in persuading people to change their habits.
Fishermen say they are hauling in lionfish in ever-growing numbers while they trawl for other species – and they often throw them back into the sea, saying there is no demand.
Despite a pitch from Toja, the island’s lone fishmonger doesn’t stock lionfish, saying customers “don’t know it so well”.
Four of the six seafood tavernas on the main road do not offer it. The owner of another – who added it to the menu this summer – said it had been ordered zero times.
“It takes time for people to get the idea,” said Chris Berdoussis, a chef and restaurant owner who said he might add lionfish to his menu in the coming weeks.
“Over here, people are looking for the traditional food – octopus, calamari.”
These tend to be the items with the highest profit margin, and the dishes that tourists most associate with Greek islands.
But it’s not what the seas are producing.
Fishermen say that they rarely catch squid and that octopus has been increasingly difficult to find over the past decade.
Even if volume increased, it wouldn’t match the demand from the summer surge of visitors.
Restaurants mark frozen items with a small asterisk, but few seem to notice. Up and down the main whitewashed strip on Elafonisos, at tables overlooking the sea, tourists eat grilled octopus imported from Morocco.
“I do understand it,” said Hall-Spencer, the marine biologist. “We like to eat what our mothers ate, and their mothers ate. If you never grew up eating lionfish, you’ll be mistrusting of it.”
Across Greece, the World Wide Fund for Nature has sponsored chef-led demonstrations about lionfish cooking.
However, the lionfish hasn’t made inroads in the capital, Athens, and is not available at the central fish market. On the large islands of Rhodes and Crete, markets have begun stocking it.
The one spot on Elafonisos that regularly serves lionfish sits at the end of the main road, where the owner, Pavlos Liaros, 62, operates his own small fishing boat. Unlike many of the other fishermen, Liaros does not discard the lionfish from his nets; he takes them back to make soup.
On a recent night, Toja, arriving with his own white wine, took a spot at the head of the long outdoor table, joined by relatives and friends, including Cavessi, the diver.
The sun had set, a few sea urchins tumbled in the shallow bay, and out came plates of fried zucchini fritters, Greek salad, eggplant and wild greens.
Then the soup arrived.
It had been prepared in the classic Greek style – the whole fish cooked with carrots and potatoes to flavour the broth, and then extracted and served on a separate platter. The broth was light red, bobbing with hearty chunks of vegetables. Cavessi cut into the lionfish and dropped flakes of white meat into the soup.
People passed around lemon and pepper and gradually started talking about things other than lionfish. But when the chef came out, Toja told him the soup was “perfect”.
“This,” Toja said, “is the local catch”.