Without any method of controlling Signal Crayfish once they have escaped into flowing water, this recently introduced species will spread throughout the Tweed system, with only caulds (weirs) or waterfalls offering any barrier to their spread.  Even though Signal Crayfish are causing serious problems in English rivers, and are increasingly being found in Scotland, there has been very little research on developing control measures.  To make matters worse there is still no government agency in Scotland responsible for Signal Crayfish, despite their discovery in Dumfries and Galloway over 15 years ago.


The size of the problem!

To help address this issue, an MPhil study looking at two different approaches to controlling Signal Crayfish is set to start ithis month.  The research is being undertaken by Newcastle University and is funded by the River Tweed Commission.  Based on laboratory work carried out in the first year, the intention is that the study will develop into a full PhD. 

The first approach will look at the potential for sterilising male Signal Crayfish that could then be returned to the river to predate on young Signal Crayfish and disrupt breeding with other females. The second avenue of research will look at the effect of using SLICE (used on fish farms to control sea lice) on Signal Crayfish. Research on North American lobsters, which are also crustaceans, has shown that SLICE can induce moulting which causes the lobsters to lose their attached eggs.


Female Signal Crayfish, loaded with eggs


Watch this space for further information on progress.