Where the Pineios River completes its long journey and its waters meet the Aegean Sea, a remarkable resident moves among the fishermen’s boats and nets.

With its distinctive blue-tipped claws, powerful pincers, and aggressive behavior, the blue crab has been a familiar presence in the river delta for many years. To the locals, it is known as “the Italian.” To fishermen, it is both an old acquaintance and a major nuisance.

From late spring and especially throughout the summer, the blue crab appears in large numbers at the mouth of the Pineios River. It gets tangled in fishing nets, cuts through fishing gear with its powerful claws, and makes life more difficult for the people who depend on the river and the sea for their livelihood.

It is the Atlantic blue crab, scientifically known as Callinectes sapidus. According to findings from a research project by the Region of Central Greece on the marine ecosystem and invasive alien species, the blue crab originates from the western coast of the Atlantic Ocean, where it inhabits estuaries, lagoons, and other coastal ecosystems.

At the mouth of the Pineios River, the highest concentrations are typically observed from early to mid-June, according to local records. Fishermen know from experience that during the winter the blue crabs move into deeper waters, while in spring they return to the coast and river mouths to reproduce. Their catch increases during the summer months, when their presence in shallow waters becomes more pronounced.

Speaking to the Athens-Macedonian News Agency, Nikos Dagkas, Deputy Advisor for Tourism at the Municipality of Agia, discusses the long-standing presence of the blue crab at the mouth of the Pineios River, while also explaining the unique name used by local fishermen in both the area and the Thermaic Gulf. It is a name passed down by word of mouth, reflecting how fishing communities first encountered this unfamiliar creature in their nets.

“We’ve been seeing the blue crab here for many years, and during the summer the mouth of the Pineios is full of them. The locals here, just like those in the Thermaic Gulf, call it ‘the Italian.’ Behind this name lies an old story, according to which the species entered Greece through the Italians during World War II. It’s a story that has been passed down from generation to generation and remains alive today, along with the image of the blue crab as a foreign ‘invader’ that settled in the waters of the area,” Mr. Dagkas says.

This account, however, survives as an oral tradition and has also been documented in European research material. Scientists, meanwhile, believe that the blue crab most likely arrived in Europe through the ballast water carried in ships’ tanks.

“Over the years, its presence became so widespread that it no longer surprised anyone. Today it may be an invasive alien species, but it has become a familiar sight in the estuary and part of the daily life of the people who live and work alongside the Pineios,” Mr. Dagkas adds.

Speaking to ANA-MPA, Giorgos Georgakis, a local fisherman with many years of experience fishing at the mouth of the Pineios River, describes fishermen’s relationship with the blue crab. As he explains, he has known the species since childhood, as its presence in the area is nothing new.

“I’ve known them since I was a little boy. They’ve been here for many years, but it’s mainly in the summer that they appear in very large numbers,” he says.

For the people who cast their nets in the estuary every day, the presence of the blue crab is far from welcome. According to Mr. Georgakis, it is “a major nuisance” for fishermen, as the crabs become entangled in fishing gear and cause damage.

“They cut through the nets and create a lot of problems. Their claws are as strong as pliers. Once they get caught in the net, they snap them open and shut with force, grabbing anything in front of them and refusing to let go. You have to be extremely careful when untangling them because they’re very aggressive and can even injure the fisherman,” Mr. Georgakis explains.

However, Giorgos Georgakis, like all the fishermen and local residents, also knows the other side of the blue crab—the one revealed once it reaches the dinner table.

“Its meat is delicious and has a unique flavor. Here we serve it as a meze, placing it in the middle of the table alongside tsipouro and good company. It’s one of those meze dishes that perfectly matches the summer and life by the sea,” he says.

Amateur fisherman Christos Liapis also shared his experience with the blue crab, describing a simple yet distinctive way of catching it from the shore.

“In the past, the blue crabs we caught were much larger than the ones we see today. I’ve caught crabs weighing as much as 500 grams. Their claws are incredibly strong, and you have to be very careful when approaching and trying to remove them because once they grab something, they don’t let go easily. The nice thing is that you don’t necessarily need a boat to catch them. You can stand on the shore, use a piece of chicken as bait, and wait. As soon as the crab grabs the bait, you slowly lift it and scoop it up with a landing net. It takes patience and careful movements, but it’s a wonderful way to fish. And once you’re done, it makes an excellent meze with delicious meat, perfect for the table and a glass of tsipouro,” Mr. Liapis says.

The spread of the blue crab is linked to its ability to survive under a wide range of environmental conditions.

According to the research project conducted by the Region of Central Greece, Callinectes sapidus is both euryhaline and eurythermal. This means it can tolerate significant changes in both water salinity and temperature.

These characteristics allow it to establish itself in coastal areas where freshwater from rivers mixes with seawater. Such conditions also prevail in the Pineios Delta, creating an environment well suited to its presence and development.

Every summer, however, the same scene returns to the mouth of the Pineios Delta. Boats head out onto the water, the nets are hauled in, and among the fish emerge the familiar blue claws. The fishermen carefully try to untangle them, grumble about the damage, and then, once the day’s work is over, one of the crabs ends up in the middle of the table beside a bottle of tsipouro. That is how life unfolds at the mouth of the Pineios River, where even an “invader” can, over time, become part of the area’s stories and traditions.