The future for the River Culm’s white-clawed crayfish

As we near the end of the Culm Community Crayfish project, here’s a little about what we’ve done and what we now know:

The crayfish project in numbers

• We trained 48 volunteers to carry out crayfish surveys
• Led 48 survey days between April and October
• Totalling 252 volunteer days – worth £37,800 in kind!
• Our volunteers ranged in age from 5 to over 75
• Engaged 1700 children and 45 teachers, involved 8 schools and a home education group
• We delivered 11 community events, attended by over 500 people
• Obtained permission from more than 80 land owners to survey on their land
• Used 383 crayfish traps
• In total, we surveyed 27km of the River Culm!

We’ll soon be ready with our full survey report. We’ll upload it here when it’s ready.

What did we find out?

We surveyed the upper and middle sections of the River Culm (starting northwest of Churchstanton and working our way down to Uffculme) and two of its tributaries, the Bolham and Madford rivers.

The endangered white-clawed crayfish can be found surviving in the middle stretch of the River Culm, just downstream from Hemyock all the way to Uffculme.

Invasive signal crayfish are found both upstream and downstream of where the endangered white-clawed crayfish are found. In places the two species are co-habiting. The spread of signal crayfish will continue, further endangering the white-clawed crayfish although, at present, we don’t know how long the spread of signal crayfish will take.

Signal crayfish are a threat to white-clawed crayfish as they outcompete the native species, taking over territory and food supply and can spread crayfish plague. If introduced to the River Culm, this plague could completely wipe out all white-clawed crayfish. White-clawed crayfish are also less tolerant of water pollution and sediment in the river. Signal crayfish tend to erode the river banks, thus exacerbating the problem.

There is currently no failsafe way of completely removing signal crayfish populations from a river, but we hope in the future to be able to reduce and control this non-native invasive species to help boost the population of white-clawed crayfish.

Our plans to support the white-clawed crayfish population

We have several ideas and plans to help secure the future of white-clawed crayfish in the River Culm, one of only two sites in Devon where this endangered species remains.

We have teamed up with Paignton Zoo where white-clawed crayfish (taken from the Culm as eggs in 2015) are being raised in captivity with a view to releasing them back into the wild. Meanwhile, we are in the process of identifying potential ‘ark sites’ in the Blackdown Hills Area of Outstanding Natural Beauty. These safe havens could be ponds or tributaries with high water quality and no signal crayfish. Here white-clawed crayfish could be released, with a view to reintroducing them to the river at some time in the future. Paignton Zoo is leading funding applications to carry out this work.

We will continue to support our crayfish volunteers and provide them with the equipment to continue surveying crayfish in the River Culm, helping us to monitor the development of the crayfish populations we’ve identified.

Water quality is also an important issue which we’re keen to address. We are currently bidding for funding for Connecting the Culm, a project to connect communities to tackle flood risk, water quality, wildlife protection and landscape enhancement. We are also involved in Woods for Water, a project to stimulate woodland planting and management in appropriate locations to combat flooding and improve water quality.

How can I help white-clawed crayfish?

Our white-clawed crayfish are certainly up against it, but there are things you can do to help:

• Check, clean and dry: Crayfish plague can easily be spread between sites, so if you’re out enjoying the river, make sure your clean your boots, fishing tackle, dogs etc. before you visit a different location.
• Help improve water quality: Be mindful of the fact that what we put down the drain and what we put on our land can wash down into our rivers. The fewer pollutants that get into the river the better the water quality, improving habitats for white-clawed crayfish along with many other species.
• Don’t put crayfish on the menu: It has been suggested that foraging for invasive signal crayfish could help address the problem. Please don’t be tempted to do this. This isn’t an effective way to control populations of signal crayfish and can often make matters worse. It’s very easy to mix up the two species so you risk harming the endangered white-clawed crayfish. You also risk spreading crayfish plague while you’re foraging. Be aware also that there are legal restrictions relating to trapping crayfish.