If asked to think about crayfish, images of the Louisiana Bayous might come to mind, or perhaps your mouth waters as you remember a delicious recipe for a crayfish chowder - what you probably don’t think of is the Netherlands. In spite of this fact, however, RTL Nieuws reports that this freshwater crustacean is becoming increasingly common in the Netherlands, making appearances on pavements and terraces across Dutch cities and towns.

Crayfish popping up on pavements across the Netherlands

Pigeons, parakeets, the odd rat; this is the kind of wildlife one can generally expect to encounter when out and about in Dutch cities - particularly in Amsterdam. If you venture out into the countryside, to the dunes or a national park, you might be lucky enough to spot some deer or a wolf, but that’s about as exciting as nature gets in the Netherlands. 

What you probably don’t expect to see wandering around on the pavement or in your local park is a riverkreeft, or a crayfish. The species can typically be found in freshwater rivers and streams, and so unsurprisingly thrives in Dutch waters. But the animal’s ability to walk and breathe on land means that when necessary, it is easily able to expand its habitat to look for a new home - resulting in crayfish suddenly making appearances in the most unlikely of places. 

According to the article in RTL Nieuws, crayfish have recently made unexpected appearances on bike lanes in Helmond and Utrecht, and in a park in Arnhem. While some people do keep crayfish as pets, these are no escapees; they're simply crustaceans on the hunt for a new home.

Nog niet eerder tegen gekomen op park #presikhaaf ...dit is toch een kreeft? 😮Er lagen ook resten van andere langs het water, dus er is óf een jagerbeest langs geweest of en mens. Ik vind ze maar eng hoor haha!🦞🤣 pic.twitter.com/HpXrNSHHBX

— Tina MeMyselfandI (@ervaringswerke1) August 4, 2023

Dutch water boards looking to take action 

While a crayfish might be an exciting - or at least notable - discovery for many, ecologists are concerned about the rate at which they’re taking over in the Netherlands. Crayfish eat aquatic plants, which play a key role in maintaining the quality of freshwater ecosystems. Without enough plants, lakes and rivers can become overwhelmed with blue algae. 

"When the aquatic plants are gone, the crayfish start on all the other life in the water. Then you're left with a bare ecosystem," water quality and ecology advisor Martijn Hokken told RTL Nieuws. They then up sticks and move on to somewhere new: "They're colonising a lot of new areas,” says Fabian Helsloot, Aquatic Ecology advisor at Waardeburg Ecology.

Water boards across the country are now looking into how the crayfish population can be controlled. "There are different systems for catching them,” explains Helsloot. “We are now testing a system in which the crustaceans are led to a collection tank with tubes. The collection tank floats on the water and the lobsters are collected in it. It is one-way traffic, so they can't get out.”

Thumb: Ellen Koppen-Fodelianakis via Shutterstock.com.