Crayfish in our Becks

Our Environment Group has been working with Bristol University on the distribution of invasive Signal crayfish in our becks. PhD students at Bristol University are developing novel methods of detecting crayfish using environmental DNA (eDNA) from filtered water samples.

The students spent a week with us in early September taking samples from our four main becks.

We have known for a long time that there were populations of invasive crayfish in Town Beck and Back Beck, but we wanted to find out how far up the becks the crayfish had moved and whether they had invaded Lumb Beck.

After months of lab work back in Bristol they have now sent us the results (see map). They detected crayfish DNA at all sites where crayfish were found by hand sampling (see a small one in Jack’s hand!) in Town Beck and Back Beck.

The good news is that crayfish haven’t (yet) moved up Town Beck beyond the Townhead Trading Estate or up Back Beck beyond Bridge 55.  The long culvert at Townhead and the high step at Bridge 55 may be acting as barriers.

The bad news, however, is that crayfish DNA was found in Lumb Beck.  No crayfish were found by hand sampling and we have not had any sightings of crayfish in Lumb Beck.  This is a worrying discovery as there are no barriers to upstream movement in Lumb Beck. 

Addingham Civic Society