In Rankoshi, managed by Hokkaido Electric Power, the delay in opening the fishway at the Rankoshi Intake Weir is believed to have caused the mass death of about 3,900 cherry salmon due to lack of oxygen, raising concerns among stakeholders about the impact on fisheries and enhancement projects. Calls for appropriate measures from Hokkaido Electric are increasing.
The cherry salmon in the Shiribetsu River are mostly three-year fish. Born in the river, they migrate to the sea as they grow and return to the river in spring as adults to spawn in the fall. The fish that died included parent fish about to spawn.
