Seite - 26 - in options, Band summer 2016

europe 26 options + summer 2016 www.iiasa.ac.at regional focus Gone fishing: New stocking strategies to keep Irrsee’s anglers busy Recreational fishing is a popular pastime in Austria, where every summer keen anglers head to Alpine lakes with their—as yet—plentiful yields of whitefish. But as water temperatures rise as a result of global warming, both the biomass of the whole populations of these fish and that of the catch will become increasingly affected. IIASA researcher Rupert Mazzucco participated in a study to see how stock management can be used to mitigate the effects of climate change. The study centred on Lake Irrsee, which  is heavily fished and also heavily managed—nearly all the stock that goes in through stocking is taken out through fishing. Using a process‑based model to project the whitefish population under different stocking and temperature scenarios for the next 50  years, Mazzucco and colleagues found that warming will reduce the total population biomass between 2.6% and 7.9% and the catch biomass between 24% and 48%. Rather than the established strategy of adding larvae to maximize biomass, which makes a negligible difference to catch under constant temperatures, they  recommend stocking one‑summer‑old fish, which will maximize catch with rising temperatures. Since  the two stocking strategies have similar effects on catch under constant temperatures, this finding underscores how fisheries management strategies need to—and can—adapt to climate change. “The alternative strategy is better for anglers, who prefer to catch fewer, but  larger fish. However, a more important message is that changing stocking strategies cannot, in the long run, prevent an overall reduction in the biomass of cold‑water fish species,” says  Mazzucco. CW Further info Ficker  H, Mazzucco  R, Gassner  H, Wanzenböck  J, Dieckmann  U (2016). Stocking strategies for a pre-alpine whitefish population under  temperature stress. Ecological Modelling 320:170–176 [doi:10.1016/j.ecolmodel.2015.10.002]. Rupert Mazzucco mazzucco@iiasa.ac.at Multiple perspectives for better risk management By engaging citizens and experts in a participatory project, IIASA researchers have found new solutions to a challenging quandary for landslide risk management.The project—the first public participatory process for addressing landslide risk in Europe—focused on landslide risk mitigation options for the town of Nocera Inferiore in southern Italy, which is located at the base of the landslide‑prone Mount Albino. The  most recent major slide, in 2005, caused three deaths and major property damage. But three years later, the municipal council rejected a proposal for a risk mitigation plan proposed by outside experts. IIASA Risk and Resilience Program Director JoAnne Bayer led one area of the project focused on risk management. “People have different worldviews, different backgrounds, and different priorities. This  doesn’t mean that any of these views are wrong,” she explains. So the researchers designed a process to take different viewpoints into account, and help people understand others’ viewpoints so that a compromise could be agreed upon. They aimed to include not just technical and economic aspects, but also the social, institutional, and regulatory context. In addition, they aimed to change the role of “experts” from the uncontested authority on a topic, to one voice among many valid inputs. To  reach a compromise, experts co‑produced several risk mitigation options based on their specialized knowledge, taking into account local knowledge and values. As a result, the community has now agreed upon a set of mitigation measures to reduce landslide risk, which are now in progress. KL Further info Linnerooth-Bayer J, Patt A (Eds) (2016). Rethinking participatory processes: The  case  of landslide risk in Nocera Inferiore. Natural Hazards 81(Suppl.1):S1–S144. JoAnne Bayer bayer@iiasa.ac.at©