Impact of fish stocking on Eurasian otter (Lutra lutra) densities: A case study on two salmonid streams

摘要: Stocking of fish into streams is a common practice in fisheries management to increase the yield for anglers and support populations. European otter (Lutra lutra) predation on stocks both economical recreational value causes conflicts many countries. However, these stocking activities may also attract additional predators site. This case study aimed investigate whether leads higher densities linear freshwater habitats Central Europe. Otter faeces data were collected province Lower Austria along two salmonid streams, which differ considerably strategies. We used non-invasive genetic sampling (NGS) methods (genetic analysis faeces) ascertain individuals. Prey populations assessed comparing length frequencies biomass obtained from electrofishing series measures. Individual identification socio-spatial organisation resident otters revealed similar with 0.22 0.23 adult per stream kilometre. Length frequency distribution indicated disappearance stocked specimen at time surveys showed no significant difference between streams. These results suggest that not affect number territories studied, because availability limited angling season. conclude provide seasonally important food resources otters, but raise question substantially contribute diet carrying capacity throughout year. Furthermore we discuss efficiency measures where self-sustaining fish-eating occur.