Setting thresholds for management Advice – Environmental indicators as a tool for an integrated assessment of Eastern Baltic cod (Gadus morhua).

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Supplementing fish stock assessment with environmental indicators is the core of ecosystem‐based fisheries management. Indicator based approaches are important for fish populations that are strongly affected by climate‐induced changes in the environment, such as Baltic cod (Gadus morhua). Besides the effects of over‐fishing, reproductive success is a crucial process in cod population dynamics; hence, indicators that reliably contribute to forecast recruitment are candidates for integrated advice. Our study focuses on the identification of potential environmental indicators for cod recruitment success, including the setting of thresholds discriminating between good and bad environmental conditions for recruitment. The present study shows that (i) biotic and abiotic indicators explain variation in recruitment success of Eastern Baltic cod (BE) after accounting for the effect of spawning stock size, and that for this case study (ii) spatially explicit indicators and thresholds must be considered. Here we show that depending on stock and environmental conditions, thresholds are inevitable and essential tools in supporting assessment‐model based stock advice for predicting recruitment success and providing first steps towards ecosystem‐based fisheries management.