Signal Crayfish

Signal Crayfish

In 2004 North American Signal Crayfish were found to have colonised a tributary of the River Nairn. Originally introduced for aquaculture, crayfish are a non-native species that have since established in the wild and are now widespread. There are known breeding populations on the River Dee (Kirkcudbrightshire) and Clyde, with localised colonies in ponds near the Rivers North Esk and Tay.

The effects of signal crayfish on the ecology of rivers and lakes are not fully understood, but in common with many non-native species, the effect on the Spey would probably be:

  • Predation on juveniles and eggs
  • Exclusion of salmon parr from winter shelter, increasing the risk of predation
  • Competition for food
  • Burrowing into soft banks, causing collapse and siltation of spawning and juvenile habitat

Officially classified in the wild as pests, crayfish are almost impossible to eradicate once established. The River Spey is only 20km from the Nairn, and separated by the River Findhorn. Every effort must be made to prevent the spread of crayfish in order to protect local salmon and trout stocks and the River Spey Special Area of Conservation. With this in mind:

Do NOT keep crayfish as pets in ponds or aquariums
Do NOT introduce them for aquaculture or fisheries
Do NOT release them illegally
Check any equipment used in areas where crayfish exist for juveniles
Report any findings of crayfish on the River Spey to the Spey Fishery Board (Tel: 01340-810841)