Risk averse policies foster bio-economic sustainability in mixed fisheries

This paper examines the role of risk aversion on the sustainable management of multispecies fisheries with technical interactions. We consider a bio-economic dynamic model of multiple species harvested by a single fleet with uncertain costs of effort. We assume that the regulatory agency aims at reaching MMEY (Multispecies Maxi-mum Economic Yield) in an uncertain context by maximizing the expected utility of total profits, where utility is a quadratic function capturing risk aversion. We ana-lyze the impact of risk aversion on optimal fishing effort, profit, production, biodiver-sity and conservation. We show analytically that such a risk-averse MMEY promotes bio-economic sustainability as it mitigates the risk of biological and economic over-exploitation of the different species. Risk aversion also enhances biodiversity in the sense of evenness within the portfolio of the fishery. However, by reducing the effort, risk aversion lessens the expected profit and food production. Thus, a trade-off be-tween different bio-economic goals is exhibited through risk aversion. We illustrate the analytical findings with the case study of the Australian South East Fishery, where small risk aversion levels allow for high global bio-economic performances and balanced management objectives, therefore fostering sustainability.