Following last month’s article on the threat posed by Signal crayfish, photographer and writer Paul Hobson spends time with the ‘Crayfish in Crisis’ project
White-clawed crayfish were once common throughout the White Peak and much of lowland Derbyshire and Staffordshire. They favour limestone rivers but are not exclusive to these and small populations did, and in some cases still do, occur in the northern part of the county, the Peak and Sheffield.
Their tragic loss from so many rivers is down to a number of reasons, including pollution, but the major factor is the spread of the alien signal crayfish and the deadly plague it carries.
The situation is so dire that the white-clawed crayfish is now listed on the IUCN (International Union for the Conservation of Nature) Red List as endangered and therefore is considered to be facing a very high risk of extinction in the wild.
Ensuring its survival almost seems hopeless. What can be done? Luckily many groups, such as Staffordshire Wildlife Trust, The Forestry Commission, The Environment Agency and the Peak District National Park, simply will not give up on our white-claws. The outcome of their efforts was the creation of the ‘Crayfish in Crisis’ project, funded by the Heritage Lottery Fund through the South West Peak Landscape Partnership led by the Peak District National Park. The mission of the Partnership is ‘by working together in the South West Peak, we will shape a better future for our communities, landscape, wildlife and heritage where trust and understanding thrive’.
Last October I joined Nick Mott from the Staffordshire Wildlife Trust (SWT) and his team to learn more about their fight to save the white-claws in our area.
At present there is no effective method of removing signals from a body of water when they have colonised it. Catching them can actually be counter-productive and there is no poison or bio-cure that will kill signals and leave all other forms of waterlife unaffected. Perhaps in years to come we may find a bio-cure, such as a disease that will only target signals, but that isn’t likely in the near future. So what can be done? The answer is simple in theory, difficult in practice, and is only a stopgap solution until hopefully, in the future, a long-term remedy can be found.
Nick and his team have been spending the last nine years surveying existing populations and, where the number of white-claws is high enough, translocating some to new sites which are aptly termed ‘ark sites’.
Ark sites are streams or ponds where it is virtually impossible for signals ever to reach. If a breeding population of white-claws can be established in enough ark sites across Staffordshire and Derbyshire then there is a nucleus of healthy crayfish that can be used to repopulate other areas.
Ark sites are not easy to find. They may be streams where white-claws used to exist so the reason for their disappearance must be understood and removed. They can also be sites that have never had any crayfish. Nick and the team then have to assess carefully whether the site can sustain a healthy population over many years. Does it offer the right quality of water, banks for shelter, sufficient food, and is the landowner supportive of the project?
During the two days I spent with the team we collected crayfish from a woody donor site in Staffordshire and relocated them to a small upland stream in the Peak.
Before we started everyone had to disinfect their wellies, waders and all the kit that would carry the crayfish or go into the river. When we were on site Nick explained how he wanted us to collect the crayfish. In some areas of the stream he had previously placed bundles of twigs to encourage them to hide. We started by searching through these. Once we had done this we carefully searched under stones and, using nets and torches, worked our way along the stream. Nick explained to us that size is important, though we were going to take virtually all the crayfish we caught. Contrary to the expectations of most of us, the smallest crayfish, even those just a few millimetres long, are the most important. This is because they will live the longest and colonise all the small micro-habitats in the ark stream.
When a group of us had worked through a section of the stream we took the crayfish back to our headquarters – a 4 x 4 that held large tanks to use for transportation. Here every crayfish was carefully measured and given a health check. I was shown a couple of crayfish that were diseased, not thankfully with the plague but with a natural disease called porcelain disease. These were left at the donor site.
Nick had given us a target of 200 crayfish. At the beginning of the day this had seemed a little over-optimistic, but by mid-afternoon we had exceeded all our expectations and had caught 420 healthy white-claws of different sizes.
The crayfish were then carried to the ark site an hour’s drive away in large tubs with an in-built aeration system. Arriving at the ark site (which was quite different from the donor site), Nick was unsure if it offered enough safe refuges for the incoming crayfish so our first job was to build 30 crayfish safe houses. These are simply a collection of house bricks with large holes. On top of each refuge we placed a cap stone to add stability and shade. Once we had completed this we released all the crayfish into the stream – larger ones individually by hand next to a refuge, smaller ones by carefully pouring them into a reasonably slow part of the stream. The feeling of satisfaction at the end of a long day was superb.
To date Nick and the team have populated 11 ark sites in Staffordshire and lowland Derbyshire and four in the Peak District. Hopefully these 15 sites – with more to come over the next few years – will be the beginning in the fight to save one of our most threatened species. The fight has a long way to go and we are probably going to lose more natives before we can turn the tide. However, with luck one day in the future we will discover a way of controlling the American interloper and be able to use the ark sites to provide us with healthy white-claws to repopulate rivers such as the Dove and Lathkill.
If you feel motivated to help in the fight to save our native crayfish you can find more information about the ‘Crayfish in Crisis’ project on the South West Peak website. You can help protect white-claws by remembering ‘The Crayfish Code’ to check-clean-dry your wellies, fishing gear and dogs before entering the water. The project is also keen to hear where people remember seeing crayfish in the past and if you’re aware of places where they still survive, or where American crayfish have appeared. This is crucial information in helping to plan ahead for future ark sites. Please contact Nick at SWT, www.southwestpeak.co.uk, www.nonnativespecies.org/checkcleandry
