On French Mediterranean, invasive blue crab wreaks havoc on local molluscs

In France, blue crabs are not appreciated by diners and worth merely €2 (S$3.20) per kg. PHOTO: REUTERS

CANET-SAINT-NAZAIRE LAKE, FRANCE (REUTERS) - Against the backdrop of a Mediterranean sunrise, fisherman Yves Rougie pulled up a net from the waters of the Canet-Saint-Nazaire lake in southern France. He was hoping for a catch of eels. Instead, it was full of blue crabs.

Once, Mr Rougie could depend on a bountiful haul of eels from the lake to earn a living. But this invasive species of crabs has been proliferating in the lake in recent years.

"Before, we were catching 10 to 15kg, sometimes 40 to 50kg of eels per trip," Mr Rougie said. This time, only four eels were in the mix, three of them dead, he said, disappointed but not surprised.

The blue crab - callinectes sapidus - has been destroying populations of eels, oysters and mussels that are traditionally caught in the area's lagoons and coastal lakes.

Native to North American Atlantic waters and brought to the Mediterranean in the ballast waters of commercial ships, the crabs have spread quickly from around 2017, according to the French Office for Biodiversity, which is helping fishermen to control their numbers.

In the United States, blue crabs can fetch US$90 (S$121) per kg, but in France, they are not appreciated by diners and worth merely €2 (S$3.20) per kg.

Mr Rougie can only sell some 50kg of the total catch of 450kg per fishing trip, the rest is thrown away, but the local authorities encourage fishermen to continue the crab catch in order to control their population.

With President Emmanuel Macron set to attend the opening of the International Union for Conservation of Nature's (IUCN) congress in Marseille on Friday (Sept 3), fishermen and scientists called on the government to fund local fishermen's efforts to curb the population of blue crabs.

"This should be funded and fishermen should be paid by the regional authorities and the state to conduct this work, which really is almost a public service mission," said Mr Pascal Romans, head of the nearby Banyuls-sur-Mer Oceanological Observatory.

He said there could a big impact on the oyster and mussel fishing industries, which are a key economic activity in the area.

Fisherman Rougie knows that fishing out all the blue crabs from the lake is an impossible task. "A female lays two million eggs, that's huge. Even if only 5 per cent hatch, their species can survive," he said.

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