White-clawed Crayfish

• It has no resistance at all to crayfish plague, a fungus introduced with American crayfish that can wipe out a whole river population within a few weeks.
• It is listed in Annex II of the European Union Habitats Directive, which requires special areas of conservation to be designated.
• Its presence indicates clean, well-oxygenated water: it disappears at the first serious organic pollution.
• It is the native river crayfish of the Iberian Peninsula and much of western Europe, and it is listed as Endangered.
• Its decline has one main culprit: aphanomycosis, or crayfish plague, caused by the oomycete Aphanomyces astaci, which arrived with the American crayfish introduced in the 1970s and which is almost always fatal to European species.
• The American carriers, the red swamp crayfish and the signal crayfish, barely fall ill, so they act as a permanent reservoir: their mere presence in the basin is enough to keep native populations from recovering.
• Added to that are direct competition, pollution and the fragmentation of rivers by dams and weirs.
• Its conservation now rests on refuge populations in isolated headwaters, with no connection to stretches where American crayfish occur.
• Its presence is an indicator of good water quality, because it is among the first invertebrates to disappear when a river degrades.

Skeleton type

Invertebrate - chitin exoskeleton (crustacean)

Habitat and environment

Clean, cool, hard-water rivers and streams, with refuges under stones

Sexual maturity

3-4 years

Sources consulted: Wikipedia (es): Austropotamobius pallipes

The pins mark the parks where its presence is documented.