On the sunny quay of the picturesque Greek island of Poros, veteran fisherman Spiros Papaioannou makes no bones about imminent plans to expand fish farming.

"We don't want them on our island," the rubber-booted man in his seventies grumbled while cleaning his nets.

"We fishermen are going to be chased away, that's for sure," he said.

Greek-Spanish group Avramar, which presents itself as the world's leading producer of Mediterranean fish, already operates several fish farms in Poros.

The Greek state has long planned to make the Saronic Gulf island of 3,000 inhabitants near the Peloponnese peninsula one of the country's top aquaculture sites for sea bream and sea bass, which mainly end up at French and Italian restaurants.

Eventually, fish farms would cover a quarter of the island, 600 hectares on land and 269 hectares at sea.

A Mediterranean country with more than 15,000 kilometres (9,300 miles) of coastline, Greece is keen to develop its aquaculture industry and has earmarked 25 sites for fish farm installation.

The European Union has allocated 92 million euros ($101 million) to promote aquaculture in Greece by 2027.

According to the Hellenic Aquaculture Producers Organisation (HAPO), the industry in 2021 saw a seven percent increase in volume to 131,000 tons.

In Poros, annual production would increase eightfold to more than 8,800 tons from 1,100 tons currently over the next five years, according to local project managers POAY Poros.

Poros mayor Yannis Dimitriadis is among those opposed to the initiative, which he says will endanger the island's existing tourism industry.

"Yes to maritime tourism, no to fish farming", read a banner hanging from the Poros cultural centre building.

Poros "is 95 percent dependant on tourism, directly or indirectly," Dimitriadis told AFP.

- Upsetting the balance -

"We are going to become an industrial zone, calling into question the whole balance of our economy", added the mayor, who claims to have already twice met Prime Minister Kyriakos Mitsotakis to explain his opposition to the project.

Contacted by AFP, the Avramar group, which achieved a turnover of 157 million euros in 2021, did not wish to provide details.

"The project is in a preliminary phase. However, we can assure you that we are committed to transparency and will share updates as soon as we are able to do so," the group said in a statement.

According to POAY Poros, the Greek state is expected to approve the project by November 2024.

- 'Not Mykonos' -

With its pastel-coloured buildings and oleander and bougainvillea-filled squares, Poros presents itself as a far cry from the mega hotel model.

"We don't want to be Santorini or Mykonos," explained Magdalena Iwaszko, owner of a small hotel near the island port.

"Tourists come here to relax... the establishment of fish farms would have enormous environmental consequences. Nobody wants aquaculture here," she said.

Poros' advantage is "crystal clear waters and an untouched coast," the hotelier argues.

The sea off the northern part of Poros is dotted with large floating cages.

"I am not (fundamentally) opposed to fish farms," said fisherman Tasos Ladas, acknowledging that Greek seas are "being emptied of fish year after year" one way or another.

"They are a necessary evil. But it has to be done correctly, with strict protocol and controls -- and not in tourist areas," the fisherman noted.

Mayor Dimitriadis is also worried about the environment, arguing that the high concentration of fish in small basins encourages disease.

He is also concerned about the possibility of fish waste and administered drugs and chemicals, such as formaldehyde.

"All this then spreads into the sea," he says.

Fish farms deny these accusations, insisting that protecting the environment and ensuring fish health are essential to their business.