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

It created a fish doorbell.

It’s all because 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.

About four years ago, ecologist Mark van Heukelum was chatting with the Weerd boat lock manager, saying that the boat lock was an obstacle for fish. The lock manager said he would open the lock for fish, but he couldn’t tell when fish wanted to get through. And an idea was born.

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

The idea has worked marvelously. In its first spring season in March 2021, the fish doorbell was rung 100,000 times by people around the world.

The video feed will not be active again until March when the fish will again be knocking at the door, but when it is time, you can watch the fish at