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Thousands of fish can spawn in the canals of Utrecht NL despite the lock. Fortunately, there is a bell - and human support. (archive picture)
Keystone
Thousands of fish migrate through the canals of Utrecht NL to spawn. But a lock blocks the way. Fortunately, there is a bell - and human support.
A doorbell for fish is causing a sensation on the Internet: in the Dutch city of Utrecht, a digital bell has been installed at a historic lock to give fish free passage through the canals. With the help of an underwater camera with an internet connection, anyone can see live whether there are fish in front of the lock. If so, viewers can press the virtual bell button and give the signal to open the lock.
Last year, almost three million people around the world watched and kept an eye out for fish. The ecologists even receive reports from Australia and the USA. "It's a kind of slow TV," says Utrecht urban ecologist Nijs. "Many people find it a positive story, and they can also do something for nature themselves."
Every spring, thousands of fish migrate through the canals to the Crooked Rhine, an arm of the Lower Rhine, explains Nijs. "They want to lay their eggs in warmer water". But in Utrecht, the 400-year-old Weerdsluis blocks their path. The lock can only be opened by hand and this normally only happens when boats want to pass through. But this is rarely the case in spring.
The fish have no choice, says the biologist. There is only this passage. "The fish wait in front of the gate and are easy prey for birds, for example." The fish also lose a lot of time and energy.
The bell has been in place for five years and is the first of its kind in the world, according to the operators. Fish alarms by bell button are possible between the beginning of March and the end of May. An ecologist came up with the idea of the underwater camera and livestream. Now everyone can see who is cavorting in front of the heavy gates: Perch, carp, pike and sometimes even an eel. The warmer it gets, the more fish there are.
Not much happens during the day, when you mainly see gray-green water and the occasional bubble. The best chances are in the early morning and in the evening.
Of course there are also ringing pranks, says the ecologist. But spectators don't alert the lock keeper directly. When the bell is pressed, a screenshot is automatically sent to the ecologists. If there is a hit, they inform the lock keeper. He opens the gates by hand and lets the animals through. "It's not for every single fish, but a few times a week."
23.03.2025, 07:43
