The last century has seen an overexploitation of many economically relevant fishes in marine and freshwater habitats, leading to dwindling catches and the collapse of many stocks. Management practices involving juvenile stocking or fishing restrictions based on size classes and bag limits have not always been successful in restoring populations. One reason is that, mostly due to life-history variability in highly abundant early life stages, interannual population fluctuations are often pronounced. Another reason is that life-history dynamics are affected by harvesting and that harvesting, in turn, is affected by life-history dynamics. It is necessary to account for these two complicating factors when assessing the ultimate effects of management interventions. In this project, we do so using a model based on stochastic population projection matrices calibrated with empirical catch data for a whitefish population (coregonids) in Lake Irrsee, Austria. We consider populations with stable, as well as with non-equilibrium, demographic distributions. Since life-history rates and their fluctuations depend on water temperature, which is currently slowly increasing in Alpine lakes, we will use this model to investigate the joint impacts of climate change, management, and harvesting on Alpine fish populations.
Last edited: 24 March 2016
International Institute for Applied Systems Analysis (IIASA)
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