Risk equivalence in data‐limited and data‐rich fisheries management: An example based on the ICES advice framework

Abstract

Fisheries management needs to ensure that resources are exploited sustainably, and the risk of depletion is at an acceptable level. However, often uncertainty about resource dynamics exists, and data availability may differ substantially between fish stocks. This situation can be addressed through tiered systems, where tiers represent different data limitations, and tier-specific stock assessment methods are defined, aiming for risk equivalence across tiers. As case studies, we selected stocks of European plaice, Atlantic cod and Atlantic herring, where advice is provided by the International Council for the Exploration of the Sea (ICES). We conducted a closedloop simulation to compare risk equivalence between the data-rich ICES MSY rule, based on a quantitative stock assessment, and the revised data-limited empirical management procedures of the ICES advice framework. The simulations indicated that the data-limited approaches were precautionary and did not lead to a higher risk of depletion than the data-rich approach. Although the catch based on generic datalimited approaches was lower, stock-specific optimisation improved management performance with catch levels comparable with the data-rich approach. Furthermore, the simulation indicated the ICES MSY rule can fail to meet management objectives due to increased depletion risk when management reference points are set suboptimally. We conclude that the recent revisions of the ICES system explicitly account for risk equivalence for data-limited fisheries management and are a major step forward.Finally, we advocate further consideration of simple empirical management procedures irrespective of data limitations due to their ability to meet fisheries management objectives with greater simplicity.

Empirical validation of integrated stock assessment models to ensuring risk equivalence: A pathway to resilient fisheries management

“…Ideally, risk equivalence should be considered so that objective-based management decisions can be maintained within acceptable risk levels and deliver results consistent with expectations and trade-offs between them [ 8 ]. In the context of single species advice, this means that in situations with poor or limited data and consequently greater uncertainty, management should not allow greater risks as required in tiered assessment frameworks [ 9 ].…”