Catching and eating crayfish can be beneficial to the Dutch water system

Catching crayfish on a larger scale in a trial has produced good results. The crustaceans are not native to the Netherlands, and underwater life has improved considerably after two years of "targeted and intensive" attempts to catch crayfish in the Krimpenerwaard region. In the ditches where the water used to be teeming with crayfish, underwater plants, such as bladderwort, are now growing again, the water board said.

The majority of those that were caught were sent to the market, said a spokesperson. The larger crayfish wound up on the menu in restaurants. Some of the smaller specimens, which are not easy to sell, were sent to the Blijdorp zoo in Rotterdam during the trial period.

"They are fed to raccoons and meerkats, among others," said the spokesperson for the Schieland and Krimpenerwaard spokesperson. In 2021, the water board started catching the crayfish, which are a plague in some areas in the Netherlands. American crayfish in particular are a major problem. They generally come from aquariums and escape, or are deliberately released into nature, Kennisnetwerk Invasieve Exoten, a research service focused on invasive species.

The big problem with the non-native crustaceans is that they dig plenty of holes, burrow in the soil and hack away aquatic plants. This can cloud clear water and reduce the diversity of species. That in turn is bad for fish, amphibians, beetles and birds, the research center said.

Last year, the water board increased the catching of crayfish. About 2,500 kilograms of crayfish were caught in eighteen weeks with almost eight hundred traps and baskets. "With this effort, the desired result has been achieved: aquatic plants have started to grow again in a large part of the test area." This year, the water board will continue further with their trial.

At the same time, the water board wants the national government to do more to combat exotic crayfish. Last month, together with other parties including Zuid-Holland, it sent an urgent letter to Minister Piet Adema of Agriculture, Nature and Food Quality asking him to address the matter.