“Carpet” of dead fish found in the Atlantic Ocean near France

The Dutch vessel FV Margiris, the world’s second largest fishing vessel, has spilled more than 100,000 dead fish into the Atlantic Ocean off France, forming a floating carpet of carcasses that have been spotted by environmental activists.

The spill, which occurred early Thursday, was caused by a rupture in the trawler’s net, said the fishing industry group PFA, which represents the vessel’s owner. In a statement, the group called the leak a “very rare occurrence.” An environmental group disputed that it was an illegal discharge of more than 100,000 unwanted fish.

The French arm of the campaign group Sea Shepherd first published footage of the leakshowing the ocean surface covered in a dense layer of blue whiting, a subspecies of cod, used to mass-produce fish, fish oil and meal.

Sea Shepherd France said it did not believe the incident was accidental, but rather an attempt by the trawler to unload a type of fish it did not want to process, a practice known as bycatch offloading which is prohibited under EU fishing rules.

Lamya Essemlali, head of the campaign group in France, told Reuters he believed the fish were deliberately discarded. Sea Shepherd France said the spill affected more than 100,000 fish.

French Sea Minister Annick Girardin called the images of the dead fish “shocking” and said she had asked the country’s national fisheries surveillance authority to launch an investigation into the accident.

Trawlers like the Margiris use trawls more than a kilometer in length and process the fish in onboard factories, a practice heavily criticized by environmentalists.

After protests by activists, the Margiris was forced to leave Australian waters in 2012.

Traffic data from marinetraffic.com on Friday showed that the vessel, which is owned by Dutch company Parlevilleet & Van der Plas and sails under the Lithuanian flag, was still engaged in fishing activities off the coast of France.