White-clawed crayfish for the uninitiated Part 1

Friday, November 23rd, 2012

Several members of The Ecology Consultancy’s staff met at our Norfolk office for an in-house workshop on white-clawed crayfish (Austropotamobius pallipes) run by The Ecology Consultancy’s crayfish expert and licensed surveyor Alex Prendergast. The main aims of the day were to develop familiarity with this often overlooked protected species, review survey methodologies and to understand the acute threats posed by non-native crayfish and disease, as well as to discuss issues on specific on-going projects. The white-clawed crayfish is protected under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) making it illegal to disturb and take (including to handle) this species without a licence. It is also a BAP species across much of its range.
A morning classroom session focused on discussing identification, habitat requirements, survey methodology and biosecurity issues. We quickly devoured lunch and headed out into a blustery but sunny autumn day, for a whistle-stop tour of some of Norfolk’s crayfish hotspots.
First stop was a river near Norwich which supports one of Norfolk’s few remaining natural populations of white-clawed crayfish. Duly disinfected we headed down to the river where Alex demonstrated a technique for sampling amongst roots and vegetation. Michelle Fielden soon caught our first (and only) white-clawed crayfish of the day, a medium-sized female, which was passed around the group for inspection. Walking slowly upstream we saw various habitats used by crayfish and practised a range of survey techniques including stone-turning (part of the ‘Standard Technique’) on a patch of riffle. We found white-clawed crayfish burrows and the braver amongst us poked in our fingers to see if anyone was at home, and to tempt them out. (A consideration when doing this is to avoid poking a water vole, which are easily angered and bite!) Here we also found several bullhead (Cottus gobio), and stone loach (Barbatula barbatula), a BAP species previously unfamiliar to most of us.

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