Now for a bit of good news after the last pollution post: Trout are spawning on the Carshalton arm of the river again!
The picture shows a trout redd (nest of trout eggs). The redd is the light coloured gravels made by the hen fish with her tail. She scoops out the gravel by fanning her tail and then lays the eggs which when fertilised by the cock fish are covered with more gravel in the same way. Trout eggs need lots of cool, well oxygenated water flowing over them to mature and hatch.
Note, this is in the Butter Hill stretch which until our works last year was behind a weir. Notice the fast flow and healthy growth of marginal iris and watercress. And of course none of this would have been possible without removing the weir with the help of the Wild Trout Trust, and all the work of our marvellous volunteers!