Mystery: Thousands of tons of dead fish wash up on Japan's northern coast

Thousands of tons of dead fish were found on the northern coast of Japan and no one seems to know why.

The sardines and mackerels were found on an over half-mile stretch of beach in Hakodate, Hokkaido on the country's northern main island, according to the Associated Press.

Some residents started collecting and selling the fish, prompting local officials to post a warning advising against doing so.

Officials said Friday they didn't know the reason behind the die-off.

Takashi Fujioka, a Hakodate Fisheries Research Institute researcher, told the Associated Press that there are multiple possibilities that could have caused the die-off, including predatory avoidance or oceanic temperature changes.

“We don’t know for sure under what circumstances these fish were washed up, so I do not recommend” eating them, Fujioka said.

See the fish blanketing Hakodate beach

Translated via Google Translate: (From the photographer) "Toi's sardines turned out to be amazing. I will upload the video to Doshin Digital later (Fuji)."

Translated via Google Translate: Breaking news: A large number of fish are washed up on Toi Beach in Hakodate. Currently being interviewed