Annan Fishery Management Plan - RAFTS

River Annan DSFB Fisheries Management Plan 2009 – 20145.2.2 Protect Against Alien InvertebratesThe North American signal crayfishPacifastacus leniusculus was first introduced toEngland and Wales through fish farms around20 years ago. It was first noted in Scotland inthe nearby River Dee in Galloway in 1995.They are also present on the upper Clyde andthe Tweed so the Annan is at a high risk of colonisation.The signal crayfish feeds largely on small fish, fish eggs and other invertebratesand is known to cause severe damage to stream ecosystems. Preliminarystudies by FRS have shown that these crayfish exclude juvenile salmon fromshelters during winter. This behaviour would increase the vulnerability of wildsalmon to predators (Marlab website). In addition, the species digs burrows up tothree feet long in riverbanks to lay its eggs. At times of increased flooding theburrows are increasingly causing river banks to collapse.An intensive trapping programme is has being undertaken in the Annancatchment with support from FRS. As yet there have been no crayfish trappedand long may this continue. However, although there have been reliablesightings of the species in the area, the lack of captures so far would suggestthat it is not yet distributed in great numbers or that the populations did notsucceed in breeding.Action5.2.2.aDescriptionContinue with monitoring & trappingprogrammeReactive orProactiveProactiveTimescaleOngoing5.2.2.b Education, e.g. provide leaflets for public Proactive Ongoing35