At least 910 dolphins washed up dead on its beaches France in the Atlantic Ocean since mid-December, according to a new count from the Pelagis Oceanographic Observatory, which found there were 400 such cases in the last week alone.

“Approximately 420 small cetaceans” washed ashore between March 10-17, 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 have been dead for several weeks, others have died just recently. Pelagiswhich has been documenting this phenomenon since 1970. Most of the examined showed signs of being hit by fishing boat engines.

The first wave of deaths was recorded at the beginning of the year. with 360 dead dolphins washed ashore from mid-December 2022 to mid-January 2023. A period of relative “calm” followed, with only 130 dolphins having died by early March.