Beavers in Scotland

The recent re-introduction of beavers into the Knapdale Forest in Argyll has received a lot of publicity. There has been a great deal of debate on the potential impact of a widespread naturalised population of beavers on populations of wild migratory salmonids in Scotland. Fisheries interests regard the dam building habit of beavers to be one of the biggest risks to migratory salmonids. Small to medium sized burns are extremely important spawning and nursery habitat for wild salmon and trout including the declining sea trout. There are long established regulations and laws controlling man-made dams, for good reason, one of the major causes in the decline of salmon populations was the widespread building of dams for mills at the start of the industrial revolution.

The Scottish Beaver Trial website states that beavers will only build dams where there is no suitable pre-existing habitat http://www.scottishbeavers.org.uk/beaver-facts/beaver-trial-faqs/do-beavers-build-dams/.  This highlights another concern of wild fishery interests; beavers change existing habitat to suit their own needs. Shallow fast flowing burns could be turned into stillwater ponds inundating trout and salmon spawning habitat. The Tweed Foundation have researched the impact of beavers on wild fish in great detail and recently published a feature on a visit to a small colony of beavers in Tayside http://news.rivertweed.org.uk/blog/_archives/2009/4/2/4141320.html. The ability of beavers to manipulate habitat to suit their own needs is cleary demonstrated.

Unfortunately the Knapdale beaver trial is in an area where there is no significant population of migratory salmonids. This suggests that the trial may not be able to provide answers on one of the most contensious issues surrounding their introduction.