Dutch water authorities call for urgent action on invasive crayfish

NEWS

POLICY & LEGAL

Heleen Kommers, Tuesday 13 October 2026

107 sec

National coordination and funding are lacking, while research shows that trapping alone is ineffective

Invasive crayfish are becoming an increasing problem for water quality and biodiversity in the Netherlands. The Dutch Association of Regional Water Authorities is calling on the national government to quickly develop a nationwide strategy. Meanwhile, regional water managers are looking for solutions themselves. For example, Hoogheemraadschap De Stichtse Rijnlanden is investigating whether combining nature-friendly banks with crayfish trapping can be effective.

Image for illustration, generated with AI

American crayfish cause damage by eating aquatic plants and disturbing the sediment and banks of waterways. This makes the water cloudy, causes aquatic plants to disappear and reduces water quality. As a result, it becomes more difficult for water authorities to meet the targets of the EU Water Framework Directive. According to the water authorities, national coordination is needed to reduce crayfish populations to manageable levels.

Who will pay for the measures?

Under the EU Invasive Alien Species Regulation, the national government is responsible for taking action, but it leaves much of the implementation and costs to regional water managers. The water authorities consider this unreasonable. They want clear agreements on powers, responsibilities and shared funding between the national government, provinces and water authorities.
They are also calling for greater attention to prevention. In areas where crayfish are still relatively rare, rapid intervention could prevent further spread. The water authorities therefore want more research, early detection and national coordination.

Water authorities are calling for national coordination and shared funding

Extensive trapping, but no reduction in crayfish numbers

Research by Hoogheemraadschap De Stichtse Rijnlanden shows just how difficult controlling crayfish can be. In the Slimmenwetering waterway near Zegveld, crayfish were trapped on a large scale for four years. Despite these efforts, the population did not decline.
The water authority is therefore launching a new trial combining trapping with nature-friendly, more resilient banks. The results will be compared with ditches where no measures are taken. Trapping is scheduled to begin in 2027. Research is also being carried out in the Kromme Rijn, the Grecht and smaller waterways to determine which crayfish species are present and in what numbers.

Four years of intensive crayfish trapping failed to reduce the population

Nature-friendly banks as part of the solution

For now, De Stichtse Rijnlanden is not opting for large-scale trapping campaigns. These are expensive, can result in unwanted bycatch and, according to previous research, do not deliver sufficient long-term results. The water authority is therefore focusing primarily on creating a more resilient aquatic ecosystem that can better withstand damage caused by crayfish.
With funding from the national government, further trials are also being conducted near Zegveld, combining more intensive trapping across a larger area with measures such as dredging.

Trapping crayfish alone appears insufficient to achieve a lasting reduction in their populations

The letter to the Dutch government concerning the management of invasive crayfish is not expected to be discussed in the House of Representatives until the end of this year. Until then, the question remains how far water authorities can and should go in taking action themselves. And what role can municipalities and green space managers play in creating and maintaining nature-friendly waterway banks?

This article was previously published on 8 October 2026 on the website of Stad + Groen.

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