Recently Robin Combe wrote a blog post on his incredible trapping efforts aimed at eradicating the non-native American Signal Crayfish from the Watering Lane, Glaven tributary.
Unfortunately, just after Robin’s blog, he discovered a small number of signals in the main River Glaven below Letheringsett Mill. Hopefully they will never get above the mill, but this find highlights an imminent threat to the Glaven’s native White-Clawed Crayfish population…
With this in our minds, over the 13th-14th September, we undertook the second transfer of White-Clawed Crayfish from the Glaven to the River Stiffkey (see the Autumn 2011 RGCG Newsletter for a summary of the first transfer last year). The Stiffkey used to contain native crayfish with records for the 1980s. Despite suitable habitat, however, surveys over the last few years have failed to find them, suggesting extinction.
We took around 400 crayfish (carefully measured, sexed and checked for any signs of disease) from the Glaven and transferred them to two new sites on the Stiffkey. We also moved around 50 crayfish to the Gunthorpe stream, giving them a safer place to reside in the Glaven catchment.
The transfer was organised by Mike Sutton-Croft (Norfolk Non-native Species Initiative) and supervised by that legendary campaigner for Glaven crayfish, Martin Pugh (Essex Wildlife Trust). A large number of volunteers were involved representing several organisations including RGCG, Environment Agency, Norfolk County Council and University College London. Thanks SO MUCH to everyone.
During the sampling Martin Pugh also made a search for crayfish at the previous Stiffkey re-introduction site and guess what…after several hours of fruitless hunting, and just before he was about to give up…he found one! Our previous re-introduction was clearly successful and that is brilliant news! We hope for the same following this new batch of transfers.
Watch this space next year for more news.
Carl Sayer