From time to time I have come across the remains of crayfish on the banks of the Guadalhorce river but had never seen any live specimens until yesterday evening when I chanced upon three individuals which I must have disturbed from the marginal vegetation. They scurried out into the shallow river leaving a trail of disturbed silt in their wakes.

One of the three was considerate enough to allow me to get a reasonable photograph. If they are undisturbed they move slowly on their legs like ballerinas on their points but if they feel threatened they whip their abdomens and use their broad “tails” to propel themselves sharply in reverse. The largest of the three crayfish sat enticingly in the shallows and posed nicely. I was careful not to approach too closely because otherwise I would be looking at nothing more than a cloud of sediment!

As far as I can tell these were specimens of an alien species Procambarus clarkii which hail originally from the southeastern part of the States and which have a number of familiar names including the red clawed crayfish and Louisiana Crawfish.

These crayfish are expanding their range here in southern Europe and edging out the native crayfish species – the white clawed crayfish (Austropotamobius pallipes).

It is sad to see the demise of native species of crayfish but unfortunately it is not an isolated event. Native European crayfish species are being ousted by introduced species including, most noticeably, the signal crayfish which was introduced to Scandinavian countries in the 1960s and which spread crayfish plague which put native species under the kosh, as well as outcompeting them for a similar ecological niche.

While it was very nice to see the crayfish yesterday evening it is also a reminder that even in a tranquil river there are wars being fought and that there are winners and losers. I hope that the native species manages to hold on but, in the southern part of Spain at least, they have their work cut out for them.


The new kid on the block: Louisiana Crawfish

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This is the native species. I have not seen one yet and so I have stolen this image from Wikipedia.