The European Crayfish (Astacus astacus), also known as the Noble Crayfish, is the best-tasting crayfish in Europe. It was common in the past, but is now an ‘endangered species’. The demise of the European Crayfish is due to many of man’s activities.
Crayfish Plague
An American parasitic fungus (Aphanomyces astaci) was brought to Europe in the nineteenth century, probably in the water that ships used for ballast. It has now spread throughout the whole of Europe. Crayfish Plague seems to be less of a problem for some of the American species of crayfish, and the Signal Crayfish was deliberately introduced into Sweden to take over from the disappearing European Crayfish.
Signal Crayfish
The Signal Crayfish (Pacifastacus leniusculus) was a great success in some ways – it provided a continued supply of crayfish to eat! Unfortunately, while not itself badly affected by the parasitic fungus, it can carry it. The subsequent introduction of Signal Crayfish into many European waters hastened the spread of crayfish plague among the remaining populations of the European Crayfish which has no resistance at all.
Louisiana Crayfish
The Louisiana Crayfish (Procambarus clarkia) has also been introduced into many parts of Europe, and together with the Signal Crayfish it seems to have ‘sealed the fate’ of the European Crayfish. The Louisiana Crayfish, as well as carrying the Crayfish Plague, is able to out-compete the European Crayfish in its preferred habitat (clear unpolluted water). It is also able to live in more turbid and stagnant water, to tolerate brackish conditions and to walk across dry land to find a new home. The Louisiana Crayfish is a very competent ‘invasive species’ in Europe.
Bank Damage
The Louisiana Crayfish makes deep burrows in the banks of watercourses, often causing serious damage. This can allow the water to leak out of natural channels and is harmful to natural water-courses, canals and irrigation systems alike. Once established the Louisiana Crayfish is almost impossible to control and it is considered a major nuisance.
Eating Crayfish
Although the European Crayfish is supposed to have the best taste of all, the other two species are very acceptable. (How to cook and eat crayfish). The problem with the loss of the European Crayfish is not so much a culinary problem as an ecological one.
Ecological Problems
The European Crayfish evolved in European waters where it had its natural predators and prey. Things were ‘naturally’ in balance. We do not know enough about the ecology of the European Crayfish to be able to predict what problems are likely to emerge as a result of its extinction, and it is now almost too late to carry out any research – there are very few populations left. Introduced species often present new (and unpredictable) challenges, and only time will tell how the ‘replacement’ species of crayfish will interact with other European organisms.
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