Determining the subspecies composition of bean goose harvests in Finland using genetic methods

Management of harvested species is of great importance in order to maintain a sustainable population. Genetics is, however, largely neglected in management plans. Here, we analysed the genetics of the bean goose (Anser fabalis) in order to aid conservation actions for the commonly hunted but declining subspecies, the taiga bean goose (A. f. fabalis). We used mitochondrial DNA (mtDNA) and microsatellites to determine the subspecies composition of the Finnish bean goose harvest, as the hunting bag is thought to comprise two subspecies, the taiga bean goose and the tundra bean goose (A. f. rossicus). The latter subspecies has a more stable or even increasing population size. Other eastern subspecies (A. f. serrirostris, A. f. middendorffii) could additionally be part of the Finnish hunting bag. We estimated genetic diversity, genetic structure and sex-biased gene flow of the different subspecies. Most of the harvested bean geese belonged to the taiga bean goose, whereas most of the tundra bean goose harvest was found to be geographically restricted to south-eastern Finland. The mtDNA data supported strong genetic structure, while microsatellites showed much weaker structuring. This is probably due to the extreme female philopatry of the species. The taiga bean goose had lowered genetic diversity compared to other subspecies, warranting management actions. We also detected A. f. serrirostris mtDNA haplotypes and evidence of interspecific hybridization with two other Anser species.