Breeding the European Noble Crayfish (Astacus astacus)

Breeding the temperate Astacus astacus: autumn mating, eggs carried under the tail through winter, hatching in spring. A Vulnerable species threatened by crayfish plague.

Overview

Astacus astacus, the European or noble crayfish (family Astacidae), is a temperate freshwater species that requires cold, well-oxygenated water and is sensitive to drops in oxygen. Males reach up to 16 cm and females up to 12 cm. The IUCN lists it as Vulnerable; populations have fallen to about 5% of former levels since the spread of crayfish plague (Aphanomyces astaci), carried by introduced North American crayfish such as the signal crayfish. It breeds as a berried female that carries eggs through winter.

Sexing

As an astacid crayfish, the sexes are separated by the underside genital openings and by the larger size and heavier claws of males, while females reach a smaller maximum length. Only a mature female carries eggs, so a berried animal is unambiguously female.

Conditioning

Animals become sexually mature after three to four years and a series of moults. Cold, clean, oxygen-rich water and an omnivorous diet are prerequisites; a seasonal cooling cycle aligns the animals with the autumn breeding window described for the species.

Breeding Setup

A large, cool tank with strong oxygenation, soft sandy substrate and burrows or shelters reflects the unpolluted streams and lakes the species inhabits. Mating occurs in October and November, after which the female attaches the fertilised eggs to her pleopods.

Berried Female & Young

The female carries the eggs attached to her pleopods through the winter until the following May, when they hatch and the young disperse. The long brooding period means stable cool water must be maintained for months while the female is berried.

Common Challenges

Crayfish plague is the defining threat: this species must never share water or equipment with North American crayfish, which can carry the pathogen. Sensitivity to low oxygen and the need for cold water make it demanding, and adults are unsafe with fish, shrimp, plants and other crayfish.