On Italy's Po River, Europe's biggest clam harvesting production preserves a way of life

A fishing boat is shrouded in fog on la Sacca di Goro, situated on the northeastern coast of Italy, where the Po River drains into the Adriatic Sea. The lagoon is a place where local people have managed to strike a delicate balance between making a living and respecting nature through shellfish harvesting. (Megan Williams/CBC - image credit)
A fishing boat is shrouded in fog on la Sacca di Goro, situated on the northeastern coast of Italy, where the Po River drains into the Adriatic Sea. The lagoon is a place where local people have managed to strike a delicate balance between making a living and respecting nature through shellfish harvesting. (Megan Williams/CBC - image credit)

"Vedi, vedi, vedi, vedi ..."

It's seven in the morning, so dense with fog that Italian fisher Vadis Paesanti grips the wheel of his small fishing vessel and repeats to himself like a mantra:

"Watch out, watch out, watch out, watch out ..."

His eyes jump from tall wooden marker poles that suddenly emerge on the right and left, to the radar beside the wheel, which signals the location of nearby boats shrouded in fog.

We're gliding along what feels like an infinite expanse of waist-deep water known as la Sacca di Goro. Situated on the northeastern coast of Italy south of Venice, the lagoon is a place where earth and water meet and mingle, as the Po River drains into the Adriatic Sea — an eerie, blue-grey midst where flamingos wade and, on clearer days, storks and herons float above.

It's also where local people have managed to strike a delicate balance between making a living and respecting nature through shellfish harvesting.

Megan Williams/CBC
Megan Williams/CBC

Paesanti, a rigorous 54, is vice-president of Fedagripesca-Confcooperative in the northern region of Emilia-Romagna, an association of fishers and shellfish farmers.

The allevatori di molluschi, mollusk breeders, are more farmers than fishers — sowing and reaping in the shallow water of the bay.

"It's the phases of the moon and its pull on the tides which determine when we go out," Paesanti said. "In the winter, the low tide is in the warmers hours of the day, in the summer in the coolest."

1,800 fishers harvest clams from lagoon

The Sacca is a UNESCO World Heritage site and home to Europe's biggest clam harvesting production. The Venerupis philippinarum, or the Manila clam — in Italian the tasty vongole veraci — supply the main ingredient in a favourite Italian pasta seafood dish.

It's prepared quickly in a pan with olive oil, garlic and parsley, and — only in this northern region that produces the world-famous Parmigiano Reggiano cheese and ham for Prosciutto di Parma — a light sprinkle of Parmesan. (The addition to pasta alle vongole is a culinary no-go anywhere else in Italy.)

Megan Williams/CBC
Megan Williams/CBC

Intensive clam breeding and harvesting in the Po's once malaria-infested delta began in the 1980s, when local fishers worked to revitalize the clam population that had nearly died out.

Today, some 1,800 fishers, organized into co-ops, harvest about 15,000 tonnes a year of the vongole from the lagoon — more than half of Italy's total clam production. Recently, they've even launched a new project to cultivate the only indigenous oysters in Italy.

Megan Williams/CBC
Megan Williams/CBC

Out in the lagoon, Paesanti drops anchor, pulls on heavy rubber overalls and lowers himself into the water. Using a motorized hydro scraper, he and fellow harvesters begin dragging the sand for clams just below the surface of the sand. A crane hauls their take on board, where they sort the clams by size, tossing the smaller ones back into the water.

Each co-operative takes an order from the buyer the night before, divides the order among co-op members and assigns each boat a spot to harvest. Today, the total amount they're harvesting is 20 kilograms.

"This way, we're selling on request and are guaranteed a price," Paesanti said. "With fishing instead, it's all about how much you can catch."

WATCH | Harvesting mollusks from Italy's Po River:

Mollusk harvesting a carbon sink: research

The Mediterranean, which includes the Adriatic Sea, is one of the most overfished areas in the world. A recent report by the General Fisheries Commission for the Mediterranean, part of the Food and Agriculture Organization of the United Nations, found that almost three-quarters of commercial species are fished at a rate double of what is considered sustainable.

Thanks to the European Union's common fisheries policy, overfishing in the Mediterranean has fallen in the past decade, but not enough.

At the same time, science seems to be showing that mollusk harvesting is not only a more sustainable option but also a carbon sink.

A July 2022 study by researchers at the nearby University of Ferrara and the University of Manchester in England analyzed the total emissions of CO2 — from what the mollusks give off as they breath to the gas used in boats to harvest the shellfish — and compared it with the CO2 absorbed by the shellfish, also known as bivalves.

Megan Williams/CBC
Megan Williams/CBC

"We found that hard-shelled mollusks are different from any other kind of animal in that, as they grow and develop and enlarge their shell, they capture C02 from the sea and the atmosphere," said Elena Tamburini, one of the study's authors. "So they represent a completely natural way to permanently capture carbon dioxide, responsible for climate change."

During the growth phase, one kilogram of clams can bind 254 grams of CO2, while clam production requires just 22 grams per kilogram.

The findings and others like it update those from several decades ago that found shellfish produced more CO2 than they absorbed. Those older studies, Tamburini said, did not take into account the fact that plankton absorbs all CO2 produced by clams in the water before it hits the atmosphere.

Megan Williams/CBC
Megan Williams/CBC

"Compared to other forms of producing animal protein, such as aquaculture like fish farming, the environmental impact of harvesting shellfish is much lower," she said.

Another benefit: Clams, mussels and oysters feed themselves by filtering water, so they require none of the polluting chemical fertilizers or growth enhancers that fish farms do.

"So when we eat shellfish, we're eating something sustainable," Tamburini said.

'Commander of yourself and your boat'

Sasa Raicevich, a sustainable fisheries researcher at the Italian Institute for Environmental Protection, agrees that science and policy are leaning toward recognition of mollusks as a carbon sink. But, he said, more research needs to be done that takes into account the full life cycle of the shells. If, for instance, discarded shells are burnt rather than recycled to make concrete or pavement, the CO2 equation could flip, he said.

"I'm not sure the policy has caught up yet, though," Raicevich said, referring to the push to include the sector in the EU Emissions Trading System for Blue Carbon credits — a global initiative aimed at mitigating climate change through conserving and restoring coastal and marine ecosystems.

While mollusk harvesting is providing a hopeful alternative to exploitative fishing, it's also at risk — from climate change to agricultural run-off and an invasive species.

At an afternoon fish market inside a large, clean warehouse in Goro, in the Emilia-Romagna region, fishers unload their catch of sole, sea bass and shrimp — neatly packed and stacked in white Styrofoam boxes.

WATCH | Bringing in the day's catch:

But certain kinds of sea life have all but vanished from the area — devoured by the blue crab. The crustacean arrived from the coast of North America seven or eight years ago, is without predators here and reproduces at an alarming rate, fishers say. It's eaten through stocks of everything from shrimp and sand smelt to smaller varieties of crab.

The fishers fear it could decimate the farming of mollusks.

Megan Williams/CBC
Megan Williams/CBC

"Clams, mussels, oysters, smaller crabs, they devour everything," fisher Daniele Paesanti said. "We did a test with a biologist and put them in a tank of seawater. If you stuck your finger in the tank, they'd snap it off. They're doing enormous damage."

Fertilizer run-off — from fields protected by dams and rice paddies that lie flat over wide plains — overloads the bay water with nutrients and minerals, causing algal blooms that transform the water's surface into a green carpet, threatening sea life.

Rising water temperatures due to climate change is another threat.

While flooding has long been the overriding worry of the Po, climate change has turned that on its head. Last summer, Italy's most severe drought in 70 years led to stretches of the country's longest river running completely dry — exposing a German tank from the Second World War and the walls of a medieval town.

This winter, the river is 3.3 metres below the normal dry point, a level rarely reached even in the height of summer.

The average water temperature of the lagoon over the past decade or so has also risen — to 11 C compared with the previous average of 3 C. "When I was a boy, it used to freeze over," Vadis Paesanti said.

Megan Williams/CBC
Megan Williams/CBC

As we head back to port, we pass boat after boat, with the ghost-like silhouettes of the harvesters pulling for clams in the water.

"We're in the hands of nature, of creation," Vadis Paesanti said. "The work is hard and some years nature takes from you. But to feel the fog, hear the bird song, following the tide pulled by the moon ... to be commander of yourself and your boat, that's priceless."