from the article Every spring, thousands of fish swish through the Netherlands’ fourth-largest city, seeking shallow waters in which to lay their eggs. Some sw

from the article Every spring, thousands of fish swish through the Netherlands’ fourth-largest city, seeking shallow waters in which to lay their eggs. Some swim all the way to Germany, like piscine Adam Peatys. Slight snag: they often have to wait at the Weerdsluis lock, which seldom opens at this time of year. Local ecologists came up with an ingenious solution: the world’s first fish doorbell or visdeurbel in Dutch (try saying it out loud). If webcam watchers spot fish waiting to pass, they simply press a virtual doorbell and the lock keeper – who can’t see down into the water, which is 2.1 metres (7ft) deep, from dry land – is sent a notification. When enough fish have gathered, the operator opens the 200-year-old sluice gate by hand to let them through.