Last Thursday saw a team of volunteers from the Yorkshire Wildlife Trust get their feet wet in search of our native White-clawed crayfish. Some old faces re-appeared from last year’s day surveying with the Wild Trout Trust as well as some newbies to The Cluster. The lower the river the better when searching for crayfish (for which you need a license as our native crayfish is a protected species). The Arkle didn’t disappoint. We’ve had very little rain in the dale recently and I can’t really remember it being any lower.
So what is a crayfish? To quote from the https://www.wildlifetrusts.org website “the UK’s only native freshwater crayfish, the White-clawed crayfish is in decline due to the introduction of the non-native North American signal crayfish. This invasive species has brought disease to which our indigenous crayfish has no natural resistance. An omnivorous crustacean, the White-clawed crayfish eats invertebrates, carrion, water plants and dead organic matter. It inhabits small freshwater streams of a depth less than 1 metre, hiding underneath stones and rocks and in small crevices where they forage for food.”
So now we know the crayfish is an ‘omnivorous scavenger’, what do they look like? Well here is a comparison between our native crayfish (good) versus an American signal crayfish (bad) pinched from Malvern Hills Crayfish Group (hope they don’t mind?)
So what did our intrepid explorers find? Did they find any native crayfish? Did they find any American signal crayfish? Well the answers are lots, no and no.
There were a large amount of caddisfly larvae (caddisfly are an interesting wee beastie which really deserve a blog of their own…well ‘about them’ may be a better way of putting it as the last time I looked there weren’t any caddisfly blogs currently online), lots of bullhead (small fish also known as ‘Miller’s Thumb’) but sadly no native crayfish. But on a positive note, no invasive Americans were found.
Thanks to the Yorkshire Wildlife Trust https://www.ywt.org.uk and their Crayfish Stakeholder Officer and to the volunteers who also did a bit of a clear up (mainly washed down plastic silage wrap) as they went.
*Krays…(you’ll have to look it up if yr young!)