White-clawed Crayfish in western Cantabria
Surprising locality for this endangered crustacean: a small 'reservoir' on the southern margins of the Picos de Europa.
Posted in: Other Invertebrates, Endangered Wildlife and Habitats | Cantabria | Mainland Spain, Northern Spain
Austropotamobius pallipes© Teresa FarinoOne of the most delightful places to spend the day in the foothills of the Picos de Europa in high summer is a small artificial waterbody – barely 50m across – in the municipio of Vega de Liébana. The margins are thickly vegetated and dragonflies abound, while the children’s fishing nets usually dredge up both Marbled and Palmate Newts. On 14 August 2009, said fishing nets had a further surprise in store: half a dozen crayfish, including both full-sized adults and a number of perfectly-formed juveniles, just a couple of inches long.
Three species of crayfish are found in Cantabrian waters: the native White-clawed or Atlantic-stream Crayfish Austropotamobius pallipes and two American species – the Signal Crayfish Pacifastacus leniusculus and the Red Swamp Crayfish Procambarus clarkii – both introduced to the region in the 1970s. Judging from the photos I took on the 14 August, our specimens would appear to be the native species, as was verified by Javier Espinosa Rubio de la Torre, head of the Dirección General de Biodiversidad in the Cantabrian Regional Government.
Austropotamobius pallipes© Teresa FarinoThe White-clawed Crayfish is a decapod crustacean found in rivers and waterbodies across Western Europe. Towards the end of the last century, however, many populations were wiped out by the ‘crayfish plague’ (in fact a fungus, Aphanomyces astacii, brought in by the American species), with further decline linked to habitat destruction in general, increased pollution of wetlands and over-collecting. As a result, today the White-clawed Crayfish is listed as threatened across much of its European range.
In Spain, the species is considered to be Vulnerable in the Catálogo Nacional de Especies Amenazadas, as well as in the Cantabrian Catálogo Regional de Especies Amenazadas. According to an article by Rosa, E. et al. in Locustella 4 (2007), between 2000 and 2006, 78 discrete populations of this species were located in Cantabrian rivers and streams, in every watershed except that of the river Miera. This is said to be equivalent to about 12% of all the populations known to occur in Spain.
juvenile© Teresa FarinoAlthough a map in this same article shows that our little ‘reservoir’ lies within the known distribution of the White-clawed Crayfish in Cantabria, what is unusual is that this is a body of standing water, fed by a minute streamlet and with an equally small outlet, lying a kilometre or so from the nearest watercourse of any size. This suggests that these crustaceans might have been introduced by the local people as a source of food at some time, probably in the middle of the last century, and have been able to survive here until now owing to the absence of pollutants, and – thus far – the two species of exotic crayfish and their associated diseases.
Nowadays, of course, the capture of White-clawed Crayfish is prohibited by law….whoops... I’d better tell the children!
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