The Fish Doorbell

Humanity possesses the impressive ability to mold natural elements to make our lives better. We can manipulate waterways, drive through mountains, and harness invisible forces to generate power.

Today, scientists and engineers understand well how these projects might affect other species. But before we had a nuanced, non-ignorant view of the interconnectedness of ecosystems, we often pumped out infrastructure without thinking about its impact beyond the primary objective.

Consider, for example, the mega-dam. The massive walls we constructed to control water are extraordinary engineering feats and allow us to manage a crucial resource, but few other species benefit.

In reality, these barriers often mean death to creatures such as fish.

To some, the benefit of humanity might supersede any concern for other species, but we now know that every part of an ecosystem plays a role in the health of the whole. Thwarting one species might have consequences up and down the chain that could seem unfathomable in a vacuum.

Modern development attempts to plan for ecosystem health. For some older or unavoidable projects, we’ve had to get creative.

We’ve begun to build wildlife crossings on high-risk highways. These overpasses allow animals to cross roadways without dodging traffic, saving the lives of drivers and prancers.

We invented fish ladders, structures that allow aquatic creatures to bypass dams or obstructions without removing the existing infrastructure.

In some places, a fish ladder might be beneficial but practically impossible.

For centuries, the Dutch have fought a never-ending battle with the ocean. A quarter of the Netherlands lies below sea level, while half the land rests just feet above zero (the High Point of the Netherlands rises just 1,058 feet above sea level at the tripoint with Belgium and Germany). The people there have employed many methods to tame the waters: dikes, dams, levees, storm surge barriers, locks, and canals. They’ve even created “sand engines,” artificial hooks off the coast that allow natural forces to spread replenishment sand.

The age of the canals and locks in the Netherlands, coupled with the dearth of space in urban Europe, means that creating fish ladders isn’t always possible.

In the past, this reality meant fish in the Netherlands might not reach spawning grounds, or they might become easy pickings for predators at choke points.

In Utrecht, the fourth-largest city in the nation, a pair of researchers developed a method to maintain Dutch water systems while also looking out for aquatic wildlife: the Fish Doorbell!

Locks are structures that allow vessels to traverse waterways with varying elevations and, by design, can open or close when needed. If open, fish can move freely throughout the waterway; if closed, they hit a dead end.

The ancient locks of Utrecht require a person to turn a wheel. The process is too cumbersome to initiate each time a fish comes knocking, and officials can’t just leave the spigots open in the Netherlands.

So, ecologists Anne Nijs and Mark van Heukelum gave the fish a doorbell.

They added a camera to the water near the lock in Utrecht and streamed the footage to a website. Each spring, viewers can check in to see if a significant number of fish have congregated in the waterway. If critical mass warrants an opening of the lock, users can push a button – ring the doorbell – to alert lock operators.

Since 2021, everyday browsers have pooled in the millions to watch Utrecht’s migrating fish, pushing the doorbell hundreds of thousands of times.

They’ve helped perch, bleak, catfish, pike, and even eels and crabs navigate the waterways. It’s a cost-effective, low-impact way to help the environment.

And a reminder that human progress and environmental stewardship are not mutually exclusive. We can creatively tackle problems in ways that allow us to keep innovating.

Officials in Utrecht hope one day the idea can spread beyond the Netherlands.

Until then, from March through May, you can join the Dutch doorbell army, helping fish make it home.