Ringing this doorbell helps fish migrate through a lock in the Netherlands.
The world’s first fish doorbell has just gone live in the Dutch city of Utrecht.
‘Fish doorbell season’ officially began, on 3 March for the fifth year in a row. A camera showing live footage allows viewers to let the lock keeper at the Weerdsluis lock know when fish are waiting to swim upstream so they can open the gate.
Linda Voortman, alderwoman for Utrecht, says each year the fish doorbell is received with enthusiasm by the people of the city and far beyond.
“In fact, last year there were almost three million unique visitors who together helped thousands of fish through the Weerdsluis gates in Utrecht,” Voortman says.
“It shows that many people are involved in underwater nature and enjoy making a contribution.”
Why is the fish doorbell needed?
The fish doorbell went live for the first time in 2021 to help fish like bream, pike, and bass make their spring migration through the waters of Utrecht to find a suitable place to lay their eggs. Each year, they migrate from the River Vecht to the River Kromme to reproduce.
The Weerdsluis is a vital passage through which they migrate.
“The sluices, pumps and dams we use to keep the water at the right level prevent the fish from getting in,” says Gijs Stigter of water authority De Stichtse Rijnlanden. That’s why, Stigter adds, the water authority is building fish passage points to help them get through.
But for now, a closed sluice gate at the lock can slow them down, making them easy prey for predators along the route. The lock is mainly closed for boats during early spring, meaning the fish can sometimes stay stranded for weeks.
The fish doorbell was introduced by two ecologists – Anne Nijs and Mark van Heukelum – as a solution to this problem.
Viewers watching the stream can press the button as soon as fish appear, alerting the lock keeper to their presence. The keepers can then open the door promptly, allowing the fish to continue their migration. Thousands pass through each year because of this initiative.
Helping fish and monitoring water quality
Fish help to keep the water in balance, eating algae and small animals. Some species also indicate the quality of the water, surviving where it is clean and oxygen rich.
“By ringing the Fish Doorbell, we not only help the fish, but also nature and water quality in and around Utrecht,” Stigter explains.
As well as opening the gates, videos and screenshots from the underwater camera allow ecologists to monitor what fish species are in the canal and when they arrive. They can see which fish pass through, at what time of year, their size, and gender.
It also means they can observe and track any other changes and behavioural patterns from previous years.
The camera has even spotted some unusual species like eels travelling in the opposite direction. Eels reproduce in the Sargasso Sea – 5,000 km away from the Netherlands.
“Fish let us know how the water is doing. If certain species thrive, such as pike, that is a sign of clean and healthy water,” Stigter adds. “The water authority uses this information to further improve water quality.”
The fish doorbell has become an online phenomenon
The fish doorbell started as a local initiative but soon went viral with people all around the world tuning in to help the fish make their way to their ideal spawning grounds.
Last year it attracted 2.7 million viewers from America to Brazil and even New Zealand. The doorbell was rung over 40,000 times.
It has gained an international following as people eagerly wait for the early March to early May period when the doorbell is active. People have been sharing their excitement about the camera going live across social media platforms like X and TikTok. The ecologists behind the initiative say they have even received fanmail.
