The birds do it, the bees do it, gotta let the fish do it too! In the Netherlands, it’s spring — that time of the year when fish swim upstream through the country’s waterways in search of a place to mate and spawn. 

The water level and traffic in these canals is managed with sea locks that have to be opened manually. But springtime is also when ship traffic is at a low, which means fish often end up wasting time waiting for the lock to be opened, during which time they are also exposed to predators.