Under European Union legislation, the government must investigate the possibility of reintroducing indigenous species (Article 22, EU Habitat and Species Directive, 1992). The re-introduction of indigenous species into Scotland involves bringing back species which were once present in Scotland. It is believed that eight species of mammal have become extinct in Scotland since the tenth century due to the effects of man. Of these, only the reindeer has been successfully re-introduced. Currently, species being discussed for re-introduction include: the wild boar, the lynx and the wolf, however it is thought that the next species to be re-introduced will be the beaver.
The beaver has been selected for re-introduction due to its suitability to the present environment, and the expected advantages it will have upon the biodiversity of the Scottish countryside. The beaver became extinct due to hunting, for both its fur which was very desirable for coats, and its secretion called castoreum which contains salicylic acid, the active ingredient in aspirin. It is believed that a re-introduction would be successful because of the laws which now exist to prevent this hunting. .
It is considered that beavers will play a large part in the enrichment of natural heritage, and thus will increase ecotourism. This is due to the fact that the beaver has the ability to create new wetland habitats and so can therefore support a new ecosystem. It is expected that with the re-introduction of the beaver, the populations of dragonfly, otter, water shrew and water vole will also increase. As beavers dam, water quality will be improved because it is aerated as it seeps through the dam, therefore oxidising any pollutants present. The dam will decrease the speed of the water travelling through the water system and so reduce the damage caused by sediments. It is a common misconception that beavers eat fish, they are in fact herbivorous and so do not pose any risk to the fishing industry.