Visdurbel (Fish Doorbell)

Visdurbel (in Dutch), or Fish Doorbell, is a system that allows fish to pass through a closed sluice gate through crowdsourced input when fish are present. The Utrecht Visdeurbel uses a livestreamed underwater camera that allows users to press a doorbell button to notify the lock operator that there are fish swimming in the gracht, and that the lock should be opened. It is designed to aid in seasonal fish migration, as an alternative to a physical fish ladder. The purpose of the project is to increase the survival of local fish that are otherwise vulnerable to predation during migration. The doorbell does not solely benefit fish. Crabs, lobsters, frogs, and geese have been caught on the livestream.