The city of Utrecht in the Netherlands has created a unique solution to help humans and marine life live in harmony. It created a fish doorbell.

Utrecht has many dams and locks that disrupt fish migration.

The fish travel Utrecht's Vecht River, a branch of the Rhine River, to the Kromme River, where they spawn in the shallow waters of the Kromme.

But manmade structures, such as dams and locks, frequently disrupt their migration. In Utrecht, the Weerd Lock is one such obstacle to migratory fish. Ecologist Mark van Heukelum told the Weerd boat lock manager that the boat lock was an obstacle for fish.

The lock manager said he would open the lock for fish, but he didn’t know when fish were ready to get through. That is when an idea was born!

Van Heukelum came up with the idea of an underwater webcam that anyone could view online, and when people saw a fish, they could ring the virtual doorbell and the lock manager would open the gate. 

The idea has worked marvelously. In its first spring season in March 2023, people rang the fish doorbell more than 100,000 times. The video feed will be inactive until March, when the fish will be knocking at the door again.

You can watch the fish at visdeurbel.nl.