| 2. |
- Andrén, Henrik, et al.
(författare)
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Harvest models of small populations of a large carnivore using Bayesian forecasting
- 2020
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 30:3
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Tidskriftsartikel (refereegranskat)abstract
- Harvesting large carnivores can be a management tool for meeting politically set goals for their desired abundance. However, harvesting carnivores creates its own set of conflicts in both society and among conservation professionals, where one consequence is a need to demonstrate that management is sustainable, evidence-based, and guided by science. Furthermore, because large carnivores often also have high degrees of legal protection, harvest quotas have to be carefully justified and constantly adjusted to avoid damaging their conservation status. We developed a Bayesian state-space model to support adaptive management of Eurasian lynx harvesting in Scandinavia. The model uses data from the annual monitoring of lynx abundance and results from long-term field research on lynx biology, which has provided detailed estimates of key demographic parameters. We used the model to predict the probability that the forecasted population size will be below or above the management objectives when subjected to different harvest quotas. The model presented here informs decision makers about the policy risks of alternative harvest levels. Earlier versions of the model have been available for wildlife managers in both Sweden and Norway to guide lynx harvest quotas and the model predictions showed good agreement with observations. We combined monitoring data with data on vital rates and were able to estimate unobserved additional mortality rates, which are most probably due to poaching. In both countries, the past quota setting strategy suggests that there has been a de facto threshold strategy with increasing proportion, which means that there is no harvest below a certain population size, but above this threshold there is an increasing proportion of the population harvested as the population size increases. The annual assessment of the monitoring results, the use of forecasting models, and a threshold harvest approach to quota setting will all reduce the risk of lynx population sizes moving outside the desired goals. The approach we illustrate could be adapted to other populations of mammals worldwide.
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| 3. |
- Gervasi, Vincenzo, et al.
(författare)
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Compensatory immigration counteracts contrasting conservation strategies of wolverines (Gulo gulo) within Scandinavia
- 2015
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 191, s. 632-639
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Tidskriftsartikel (refereegranskat)abstract
- In wide ranging species, portions of the same population often fall within different administrative jurisdictions; where different regulations apply. The same species can be fully protected or heavily harvested on different sides of a border. This can generate a source-sink dynamic from the areas with lower to those with higher mortality, a process known as compensatory immigration. We tested this hypothesis on the wolverine (Gulo o gulo) population of southern Scandinavia, which is shared between two countries: Sweden and Norway. Wolverines are fully protected in Sweden, but subject to intensive population regulation in Norway. Using non-invasive genetic sampling and capture-recapture modeling, we analyzed the dynamics of wolverine survival and emigration patterns between 2002 and 2013. Wolverines in Norway experienced a lower survival than in Sweden. Migration across the national border was directed towards movements from Sweden to Norway. There was a functional relationship between harvest rate in Norway and emigration rates across the national border, both at the individual and population level, thus confirming the compensatory immigration hypothesis. Contrasting management regimes within the same population can generate undesired demographic and spatial dynamics, jeopardize conservation goals on the two sides of a border, and reduce the efficiency of management actions. This calls for the adoption of a coordinate population approach in large carnivore conservation and management. Failing to do so can cause a waste of the already limited resources allocated for large carnivore conservation, and it might hinder effective conflict mitigation.
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