Goose hybrids, captive breeding and restocking of the Fennoscandian populations of the Lesser White-fronted goose (Anser erythropus)

The lesser white-fronted goose (Anser erythropus) isthe most threatened of the Palearctic goose species with a decliningpopulation trend throughout its distributional range. The currentestimate of the Fennoscandian subpopulation size is 30–50 breedingpairs, whereas it still numbered more than 10000 individuals at thebeginning of the last century. Reintroduction and restocking have beencarried out in Sweden and Finland using captive lesser white-frontedgoose stock with unknown origins. We have carried out a study of thegenetic composition of captive-bred stock by sequencing a 221 bphypervariable fragment of the mitochondrial DNA (mtDNA) control regionfrom 15 individuals from the Hailuoto farm, Finland. Two out of thethree maternal lineages detected in the captive stock are also presentin wild populations. The third maternal lineage among the captive lesserwhite-fronted geese originates from the closely related greaterwhite-fronted goose (Anser albifrons). None of the investigatedwild lesser white-fronted goose individuals carried the mtDNA of thegreater white-fronted goose. The presence of greater white-fronted goosemtDNA in the lesser white-fronted goose captive stock suggests thathybridization has occurred during captive propagation.