Dioxins in Baltic herring and salmon: an inter-sectoral decision analysis for optimal management of the problem

Ecosystem-based management (EBM) of natural resources requires recognition of the systemic intertwining of ecosystems and human society and an inter-sectoral approach. We used a Bayesian influence diagram to integrate different types of knowledge for evaluating alternative sectoral and inter-sectoral strategies to manage the dioxin problem of Baltic salmon and herring fisheries. The following strategies were evaluated: 1) decreasing dioxin and nutrient loading to the ecosystem, 2) herring and salmon fishing strategies, 3) dietary recommendations, and 4) improved information concerning the benefits of fish eating. In total nine decisions and their combinations were evaluated in the light of three alternative assessment criteria: 1) the dioxin concentrations of Baltic herring and salmon, 2) the human consumption of Baltic salmon and herring, and the associated health risks and benefits, and 3) the commercial value of herring and salmon catches. The results demonstrate the requirement to understand the effects of management measures in a holistic way: managing only one species or policy domain may not be effective, and may also have unanticipated systemic effects in the ecosystem. In general, optimal management depends to some extent on the assessment criteria used, as well as the order in which the decisions are made. Unsynchronized management decisions in different sectors may decrease each other’s effectiveness. This implies that to control the dioxin problem as effectively as possible, collaboration between the public health, environmental and fisheries sectors is needed.