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Carlin tagging data for 1980–1991 were used to examine the influence of smolt size and feeding conditions on the post‐smolt survival of ranched River Neva salmon, (Salmo salar L.), in the the Gulf of Finland, which is the native feeding area of the stock, and in the Bothnian Sea, where the stock has been introduced. Because of better feeding conditions, the survival rates were higher and less variable in the Gulf of Finland than in the Bothnian Sea. In the Bothnian Sea, the annual variability in survival decreased and the mean value increased with increasing smolt size from the smallest (14–16 cm) to the largest (28–30 cm) size classes. The survival was positively correlated with growth rates, food resources and sea‐surface temperatures. This suggests that in the Bothnian Sea the annual variability in survival is mainly because variable marine conditions affect growth rates, and, thus, the vulnerability of the post‐smolts to size‐dependent predation. In the Gulf of Finland, the survival advantage of large initial size and rapid growth was counteracted by size‐selective post‐smolt mortality from fishing. The increase in the survival rate with increasing smolt size levelled off at 22 cm, and the correlations between survival, growth and the indices of feeding conditions were mostly insignificant. For large smolts, some negative correlations were recorded, suggesting that the relative significance of mortality from fishing may even exceed that of size‐dependent natural mortality. The implications of the results for management are discussed.

This overview article for the special series, "Bayesian Networks in Environmental and Resource Management," reviews 7 case study articles with the aim to compare Bayesian network (BN) applications to different environmental and resource management problems from around the world. The article discusses advances in the last decade in the use of BNs as applied to environmental and resource management. We highlight progress in computational methods, best-practices for model design and model communication. We review several research challenges to the use of BNs in environmental and resource management that we think may find a solution in the near future with further research attention.

ABSTRACT. It has been acknowledged that natural sciences alone cannot provide an adequate basis for the management of complex environmental problems. The scientific knowledge base has to be expanded in a more holistic direction by incorporating social and economic issues. As well, the multifaceted knowledge has to be summarized in a form that can support science-based decision making. This is, however, difficult. Interdisciplinary skills, practices, and methodologies are needed that enable the integration of knowledge from conceptually different disciplines. Through a focus on our research process, we analyzed how and what kind of interdisciplinarity between natural scientists, environmental economists, and social scientists grew from the need to better understand the complexity and uncertainty inherent to the Baltic salmon fisheries, and how divergent knowledge was integrated in a form that can support science-based decision making. The empirical findings suggest that interdisciplinarity is an extensive learning process that takes place on three levels: between individuals, between disciplines, and between types of knowledge. Such a learning process is facilitated by agreeing to a methodological epochè and by formulating a global question at the outset of a process.