Help These Fish in the Netherlands Ring a Doorbell

I am waiting for a fish to show up on this webcam. It’s daytime here but evening in the Netherlands, so I may have missed the peak of fish activity that occurs at dusk. But the website tells me that eels and pike often show up at night, so I’m still hopeful. And when the fish start to show up, I will ring the doorbell for them.

This “visdeurbel” (fish doorbell, say it out loud) is a project from the city of Utrecht, where fish swim every spring from the Vecht to the Kromme river. As the fish doorbell website explains, the city has plenty of canals and rivers, and the fish are part of the local wildlife. They eat aquatic insects and help to maintain good water quality.

But every spring, as the fish migrate to shallower water to reproduce and lay their eggs, they run into human-built structures like dams and locks. They can get through when somebody opens the lock, but while they wait, they are in danger of being eaten by predators like herons and cormorants. That’s where the fish doorbell comes in.

The Weerdsluis, or the Weerd lock, is one of the structures the fish can’t cross by themselves. Workers open the lock to let boat traffic through, but it’s harder for them to know when fish are waiting to cross. (Since they’re underwater and all.) Hence the webcam: You can log on from anywhere in the world to watch for fish. When you see them waiting, press the big red button to ring the “doorbell” for them. This alerts the lock keeper, who can then open the lock.

A lock, by the way, is sort of an elevator for water. It’s used to connect bodies of water where one is at a slightly higher elevation than others. A compartment can be filled or drained to allow boats—or, in this case, fish—the ability to travel from the lower to the upper level, or vice versa.

More than 10,000 fish swam through the lock last year, the Visdeurbel site notes, thanks to the help from fish doorbell ringers such as yourself. The fish migration season is just beginning, with more activity expected in mid-April. But if you check it out today, you might be able to open the doors for some of those early arrivals.