MANAGEMENT STRATEGIES FOR THE WOLVERINE IN SCANDINAVIA

The use of Population Viability Analysis has recently been criticized mainly because uncertainties in population predictions are often ignored. We analyzed the viability of Scandinavian wolverine Gulo gulo populations that allow for the inclusion of uncertainties in parameter estimates and stochastic effects on population dynamics. We used the insight gained from analyses of stochastic population models to quantitatively analyze different management options for the wolverine. These management options were based on data from an individual-based demographic study in the Sarek National Park, Sweden, and data from monitoring schemes in Norway and Sweden. Stochastic components in population dynamics of the wolverine were large. Strong density regulation occurred around the carrying capacity. According to the World Conservation Union (2001), the carrying capacity of populations must exceed 46 sexually mature (≥3-yr-old) females to be considered not vulnerable. Continuation of the current levels of offtake in Norway will lead to extinction of the wolverine over large parts of the country. Hence, current rates of mortality of female wolverine make the northern population endangered, whereas the southern population is classified as vulnerable. Management plans allowing harvest of individuals should be based on a proportional threshold harvest strategy. Only 40–60% of the surplus individuals exceeding a certain threshold for harvesting should be removed. Our analyses emphasized the importance of including estimates of precision in parameter estimates, including stochastic factors in recommendations based on Population Viability Analysis, and examining the robustness of the conclusions against variation in crucial parameters by sensitivity analyses.