Delft Is Crawling With Crayfish

The Netherlands is well known for its international atmosphere, but not all new arrivals are welcome. Take, for instance, the red swamp crayfish. No one is happy to welcome it to The Hague.

Crayfish were first sighted there in the early 1980s, but the issue went relatively unnoticed for many years. These crustaceans arrived from Louisiana, and made their way into aquariums or garden ponds. Then they escaped. Now, the region’s crayfish population is considerable: “In Delfland, we’re talking [about] at least millions. You look underwater and grab a net and you see thousands in a square meter,” says Ernst Raaphorst, an ecologist working for the Delftland Water Authority. This sounds like a lot, but Raaphorst puts the numbers in perspective: “The smaller the animals are, the more you need [in order to] take notice of them. There are millions of square meters of fresh water in Delfland, so it quickly starts adding up. It’s still many, but it’s not like they’re everywhere.”