The noble crayfish is a keystone species currently fighting for its survival in Europe

Nature · Published 3 October 2026 Swipe more like this →

In short: Once a prized delicacy for Swedish nobility and a staple of European freshwater ecosystems, the noble crayfish is now a vulnerable species. Threatened by invasive rivals and a deadly plague, its population has plummeted to just 5% of its former levels, leaving a significant void in the continent's aquatic food webs.

The noble crayfish, Astacus astacus, is a nocturnal crustacean native to unpolluted freshwater streams, rivers, and lakes across Europe. These creatures are highly sensitive to water quality, requiring high oxygen levels and specific shelter to thrive. As a keystone species, they play a vital role in maintaining the health of their environment. By foraging on aquatic plants, they prevent excessive macrophyte growth, which would otherwise lead to eutrophication and the degradation of water quality. Their presence supports a complex food web, serving as a primary food source for predators ranging from eels and perch to otters and European mink.

Despite their ecological importance, the noble crayfish has faced a catastrophic decline. The introduction of the invasive North American signal crayfish, Pacifastacus leniusculus, brought with it a devastating crayfish plague to which the noble crayfish has little resistance. This biological invasion has decimated their numbers, reducing the population to about 5% of what it once was. Consequently, the species is now listed as vulnerable on the IUCN Red List. This decline is particularly poignant given the crayfish's deep cultural history in Europe, where it has been a traditional food source since the Middle Ages and remains central to Nordic traditions like the late-summer crayfish party.

Beyond its culinary and ecological status, the noble crayfish has contributed significantly to biological science. In the 1990s, researchers isolated a family of digestive enzymes from the species, known as astacins. These enzymes have since been identified in a wide range of organisms, from simple hydra to humans, highlighting the unexpected ways this crustacean has influenced our understanding of biology. Today, as wild populations struggle, the focus has shifted toward intensive aquaculture of more resilient, non-native species, marking a transition from the traditional collection of wild noble crayfish to a more controlled, albeit less ecologically diverse, approach to meeting human demand.

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