A sea of loss: Pieria mussel farmers face climate devastation
With 80% of this year’s harvest lost, growers in northern Greece grapple with impact of rising temperatures, polluted rivers and the grim uncertainty of future production
A funeral of sorts is taking place at the Kitros Salt Pit in Pieria, northern Greece, as local mussel farmers bury their harvest, lamenting the massive loss of 80% of this year’s yield. On this overcast day, the harbor is quiet; instead of collecting mussels, the growers sit in cafes, desolately sipping tsipouro and nibbling on meze.
The conversation drifts to the climate crisis, rising temperatures and pollution in the Axios River. The people facing the industry’s collapse this year do not use scientific jargon; theirs is a straightforward idiom. Climate change is something they experience firsthand every single day when they pull up their mussel ropes only to find shells that crumble on the deck. They witness its effects when they pull up a mix of mud from the sea – a “slime,” as they call it – that is poisonous to the delicate mussels. They feel it in their bones as the octopus vanish, fish become scarce and the southern winds, which normally stir the waters, fail to arrive. And they know its impact when “800 people, meaning 300 families, who all depend on this industry, have no bread on the table,” they tell us in a taverna in the village of Kitros.
“We’re talking about total devastation in the mussel farms of Pieria,” says Tassos Draganis, president of the Agricultural Cooperative of Mussel Growers of Makrygialos Pieria, in an interview with Kathimerini. We meet him by his fishing boat, currently being repaired and repainted in preparation for the next harvest – “If that ever comes!” he exclaims. According to Draganis, this unprecedented annihilation of mussels is affecting the entire Thermaic Gulf, leaving nothing in the farms. The pressing concern now is the destruction of the larvae, which threatens next year’s production.
Hot seas
“Mussels can survive in temperatures up to 27-28 degrees Celsius. Here, we recorded sea temperatures of 30-35 degrees. We can’t survive this. We need a team of scientists to guide us through these changing conditions. There are 75 entrepreneurs and 800 people working in the mussel farms of Pieria. We should at least be compensated for our fuel costs,” he says in frustration.
Meanwhile, the Ministry of Rural Development, which has responsibility for agriculture and fisheries, has already conducted an on-site inspection to assess the scope of the damage.
“The damage is done,” says Ilias Hatzichristodoulou, president of the Pieria Chamber of Commerce, as he arrives at the harbor to meet us. “We are working closely with the Ministry of Rural Development to secure immediate compensation for the mussel farmers. We have already approached the government in a coordinated effort, as special support measures will be essential for the industry in 2025, when there will be no production. Additionally, regulations must be put in place to ensure the continuation of mussel farming in the Thermaic Gulf,” he states. He adds that samples of water and mussel flesh have been sent for laboratory analysis to pinpoint what exactly wiped out the mollusks and assess the overall situation.
According to Hatzichristodoulou, the bulk of Greek mussel production is concentrated in the Thermaic Gulf (in Thessaloniki, Imathia and Pieria). Renowned for its high quality, 90% of the yield is exported to Italy, France and Spain.
“We are desperately searching for larvae and have contacted our colleagues in Taranto, in Magna Graecia, to see if their strain can work for us,” says Draganis, referring to the southern Italian district and expressing a glimmer of hope for the next harvest. “I spoke with their president. I told him, ‘Please, you need to send two shipments in September and October so they can spawn in time.’ We need 40-50 tons of larvae. The Italians are our friends; they will help us. We need this to meet our 13,000-ton production target.”
Mass deaths
Konstantinos Koukaras, a biologist and postdoctoral researcher at the Institute of Applied Biosciences at the Center for Research & Technology Hellas (CERTH), has been studying mussel farming since 1999. He tells Kathimerini that this year, the Thermaic Gulf experienced conditions similar to those of summer 2021.
“We had high temperatures in the surface layers of the water again, exceeding 30 and 31 degrees Celsius in the first 5 to 10 meters of the water column. As a result, organisms in the top 10-15 meters, whether along the shoreline or attached to mussel farms, experienced mass die-offs,” he says.
“The high water temperature has two main effects,” Koukaras continues. “First, there are fatal episodes due to thermal shock. Second, the higher the water temperature, the greater the solubility of oxygen in the air. Essentially, oxygen from the sea escapes into the air more rapidly, reducing the oxygen content in the water and leading to low oxygen concentrations.”
According to Koukaras, the larger, less resilient mussels die first, followed by the smaller ones. “The death of larger, commercially valuable mussels deprives producers of immediate profits from sales, while the loss of larvae jeopardizes next year’s harvest.”
He goes on to emphasize the challenge of compensating these farmers. “Until recently, the European Union did not recognize increased temperatures as a phenomenon warranting compensation, considering it an extreme natural event,” he explains.
Ideal conditions
Mussel farming is the only trade the locals in the area know well. It began in the early 1980s, adopting techniques from neighboring Italy. Many fishermen turned to mussel farming due to the region’s particularly favorable conditions, where mussels grow to the desired consumption size in less than nine months. “This is because the region’s rivers – the Axios, Loudias and Aliakmonas – flow into the western Thermaic Gulf, carrying a wealth of nutrients into the sea and creating ideal conditions for cultivating large, flavorful mussels,” Koukaras elaborates, highlighting the region’s deep connection to mussel farming.
According to Koukaras, mussel production in Pieria is divided into three main areas: the mouth of the Axios River, at the boundary of the Halastra Municipality; the mouth of the Loudias River, near the Axios Municipality; and south of the Aliakmonas River mouth, along the coast of Pieria.
Down at the harbor, all the boats are docked. “This is the only job we know; what will we do if we don’t have the mussels?” asks Petros Haralambidis, 80, one of the area’s first mussel farmers, speaking to Kathimerini. He owns 30 acres, and both of his children now work alongside him. “2021 was a bad year too, again because of the heat. But it wasn’t like this. Everyone is in tears. Today, we pulled up some mussels and they were all dead. And when I talk to producers in Italy and Spain, they say they have the same problem. The waters are changing. We don’t know what to do. Are we placing the mussels correctly, at the right depth? Do we need to change something? Who will tell us?” he wonders.
Mussel producer Alexis Tsamalidis, originally from the Black Sea region, has 30 years of experience in the industry and owns 30 acres. He primarily exports to Italy but also supplies the Halkidiki peninsula and other parts of Greece. “We went in the other day and the small ones are dying. The large ones are already gone and now the larvae is going too. It’s 80% dead. The heat is to blame; conditions have changed, and we feel it firsthand. It’s been getting worse for the past three years. We won’t even have the money to repair our boats. Maintaining them is an expensive affair,” he explains, showing us his boat, the Agios Giorgis, named after his son. Most mussel farming businesses here are family-run, passed down from father to son – and now, also to daughters. “I have four grandchildren; we’re fighting for them now.”
A few meters away, mussel farmer Konstantinos Kongolos, 58, is tying up his boat after returning from the farms. “We need to be patient and understand what’s really happening. We need to listen to the scientists,” he says. “I send my mussels to Italy through traders. I’ve been in this business since 1990. I have 20 acres and my son has 10. If we can’t work, we’re done for. They’re telling us to turn to tourism. Is that the solution in this country, to go from being producers to being waiters? That’s what they’re suggesting.”
We board the boat of Spyros Vrahaj, who has been in the industry since 1993, when he moved to Pieria from Tropoje, Albania. From our conversation, it’s clear that rising sea temperatures aren’t the only concern for the producers.
Polluted rivers
“What’s really causing us major damage is the river water. It’s polluted,” says the 51-year-old mussel farmer, explaining that reduced rainfall means agricultural pesticides end up in the river. “This sludge isn’t from the sea. It’s like mud from below, coming like fire from the river and burning everything, burning the mussels,” he emphasizes, hauling up mussel ropes from the sea, his 16-year-old daughter by his side. “You only find about 10 alive in a net. What will I leave my children? This boat is everything I have.”
We ask Koukouras, the biologist, about the pollution phenomenon the locals describe as “fire in the sea.” “They have seen red patches in the Thermaic Gulf. However, we don’t currently know what the phytoplankton community is – meaning the microorganisms that have developed in the water. While specific locations are monitored and checked, these can’t indicate what is happening throughout the entire gulf. Therefore, we can’t confirm whether these patches contain toxic species. These are issues we won’t understand without continuous measurements,” notes the expert.
He also highlights a significant gap in the research. “The Axios River has sensors installed by the regional authority and other agencies as part of research projects but the data isn’t systematically studied. What is certain is that if we continue like this, very soon – within three years, I’d say – there won’t be a single Greek mussel left.”
As the sun sets, the producers offer to treat us. We order mussels, but at the Olympia taverna on the village’s beach, there are none.
The owner, Nikoleta Lemonopoulou, explains that if a taverna has mussels at this time of year, they are almost certainly imported from Romania. “I had mussel dishes at the beginning of the season, but now I don’t want to buy foreign ones,” she emphasizes. “There’s no local production right now, and even if there were, I’d be wary,” she adds. “We hear about water pollution from the river, bacteria and mussels dying from high temperatures. I can’t serve these mussels to my customers. Mussels are dangerous if they’re bad,” she concludes, serving us fried shrimp instead.
The ‘invader’
The species cultivated in the Pieria region is the Mytilus galloprovincialis, or the Mediterranean mussel. Native to the Eastern Mediterranean, as well as to the Adriatic and Black seas, this mussel has now spread to seas around the world, either through deliberate cultivation or by being transported, for example, via commercial ships.
Listed among the top 100 “worst invaders globally,” Mytilus galloprovincialis displaces local mussel species when it establishes itself in non-native areas. It is commercially farmed on a large scale in Japan and China, with Spain being the largest producer in Europe.
The cultivation process begins with collecting larvae that attach to special ropes known as collectors. Mussel farmers remove these larvae from the ropes and place them in plastic cylindrical nets, called “armathies” in Greek, which hang from ropes in the water. Farming can be done either on stakes (pole-based mussel farms) or on ropes suspended from floats (floating or long-line mussel farms).
From May to July, mussel farmers periodically open the armathies, thin out the mussels that have grown, and rehang them in the farms until the mussels are fully developed and ready for harvest.
The quality of the mussels is maintained through regular checks on the both the water and the mussels themselves.
However, mussel farming is not without its challenges and environmental pressures. The high density of shellfish farming units disrupts the movement of sea currents, which are crucial for shellfish development. Additionally, it causes the accumulation of material on the sea floor where the farms are located, negatively impacting the benthic communities that reside there.
