Hiroyuki Yokomizo
(Department of Biology, Faculty of Sciences, Kyushu University)

05/12/13, 13:30 at Room 3631 (6th floor of building 3 of the Faculty of Sciences)

We consider optimal conservation strategies for a population whose viability is affected both by an alien species (e.g. a competitor, a predator, or a pathogen) and by a random fluctuation of the environment (e.g. humidity). We assume that the survivorship of the endangered population can be improved by a conservation effort, but also by an extermination effort that decreases the density of the alien species. Both efforts decrease the extinction probability of the endangered population, but they are accompanied by economic costs. We assume that the optimal strategy minimizes the weighted sum of the extinction probability and the economic costs. We derive necessary conditions for the optimal conservation and/or extermination efforts to be positive and obtain the optimal effort levels. We also examine the effect of lack of information on the impact of the alien species on optimal effort levels.

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