American crayfish take over the Krimpenerwaard, ‘urgent action needed’


Tens of millions of American crayfish are damaging the waterways of the Krimpenerwaard area in Zuid Holland and experts are calling on agriculture minister Piet Adema to take quick and decisive action against the invasive species.

The crayfish – Procambarus clarkii, or red swamp crayfish – are thought to have travelled from their native United States in the ballast tanks of large freighters and are well adapted to local waterways. They are particularly common in Utrecht, Noord-Holland and Zuid-Holland.

The animals are considered a pest and a threat to water flora and fauna. They also dig holes in the banks of the ditches which crisscross the Krimpenerwaard, and this undermines the land and presents a danger to cattle.

‘The waterways are now still and lifeless,’ local organisations said in a letter to the minister, calling for a ‘large scale, sustainable and organised’ approach to the problem.

In 2016 professional fishermen were licenced to fish for the crayfish commercially but this, combined with local initiatives to catch as many as possible, proved no match for the animal’s ‘explosive’ breeding speed.

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