Getting even with the crays
It is early Tune 2017 and on my little chalkstream an irregular spate of sulphur mayflies are hatching, tearing and pushing through the surface tension before coursing downstream. Bobbing, racing and spinning, faster then slower, it is almost as though they are riding an aquatic waltzer, dodging hungry wild brown trout and passing through the midday sunlight.
This pastoral drama has been re-enacted for thousands of years on our fertile southern rivers, but on this particular day it was overshadowed by my first brush with an illegal alien. A single crushed claw, the leftovers from an otter’s midnight feast, was the clue to an invader from the other side of the pond. It is most certainly not good news for my precious chalkstream beats.
The signal crayfish, , hails from North. Both share similar freshwater habitats, preferring an adequate depth of moderately flowing oxygenated water, feeding predominately on freshwater invertebrates such as mayfly, caddis and mollusc and spending most of their time sheltered among rocks, tree roots or under the riverbank edge.
