At least 910 dolphins have washed up dead on French beaches in the Atlantic Ocean since mid-December, according to a new count by the Pelagis oceanographic observatory, which found 400 such cases in the last week alone.

“Approximately 420 small cetaceans” washed up between March 10 and 17, and 120 of them over the weekend of March 11-12, which is “unprecedented,” the institute said, though the numbers were not final.

Some of the dolphins had been dead for several weeks, others died recently, according to Pelagis, which has been recording the phenomenon since 1970. Most of those examined showed signs of being hit by fishing boat engines.

A first wave of deaths was recorded earlier in the year, with 360 dolphins washed up dead from mid-December 2022 to mid-January 2023. This was followed by a period of relative “quietness”, with only 130 dolphins dead by early March.

From 2017 to 2020, an average of 850 dead dolphins were recorded on the coast each winter. In February and March the dolphins come close to the shores to find food and consequently come into contact with fishing boats, as a result of which some of them are injured and die. Non-governmental organizations and scientists have called for a halt to fishing during this period, but the government has so far preferred to take other measures: documenting the phenomenon and proposing “technical” solutions, such as placing cameras or “repellents” on fishing boats.