The claim
（福島第一原発）魚の大量死は処理水の影響
Original review summary
The review says that large fish strandings had occurred in Hokkaido before treated-water releases began. A fisheries researcher considered a large sardine school, together with rough weather, a sudden drop in water temperature, or predators, a possible explanation for the Hakodate event.[S1]
Additional context
The mass stranding occurred on December 7, 2023, on the coast of Hakodate, Hokkaido. [S1]
The review reports that environmental monitoring on November 28 found measured substances below detection limits, and a fishery center reported no mass-death strandings along Fukushima’s coast after treated-water releases began. [S1]
Research date:
Sources and attribution
- [S1] 日本ファクトチェックセンター original review
Original review · Retrieved October 16, 2026