Waving a Magic Wand(le)

Posted on August 20, 2010

Very hot news just in is that after many months (years!) of assessment, planning, design, negotiation and hard work; permission has just been granted for my design of habitat restoration and enhancement works to go ahead on the upper Carshalton arm of the Wandle.

Many thanks to Bella from the Wandle Trust hosting our E.A. flood risk assessor and putting our case so well and also great effort from Tanya in E.A. fisheries for making the weir removal programme happen.

An extensive array of structures will be installed over around 600 m of river which will create high quality spawning and adult holding habitat along with some additional juvenile habitat to complement the existing opportunities for young trout. When this is coupled with the increased connectivity along this section of the Wandle (through a combination of weir removals and fish pass installation), then the potential for robust self-sustaining populations of wild trout will be greatly increased.
The final piece of this part of the puzzle will come with the hoped-for opportunity to import wild trout parr from nearby in the catchment. Rather than depleting adult brood stock from the donor site — juveniles will be sourced from a population that is producing a natural surplus of parr (mixture of 0+ and 1+ age classes)in a comparable stream. In this way, with the phasing in of sterile “triploid” eggs for use in “Trout in the Classroom” instead of fertile hatchery strain fish — the adaptable and well-prepared wild fish will have the best chance of establishing themselves and successfully breeding in the Wandle once more. The classroom fish have done an admirable job in proving that survival, growth and even a little spawning can happen in stream (they have been the canaries in the cage). The next exciting phase is hoped to be to see how the streetwise wild fish take to their new home.