Working Group on Multispecies Assessment Methods (WGSAM; outputs from 2025 meeting)

The Working Group on Multispecies Assessment Methods (WGSAM) aims to advance the operational use of knowledge on predator-prey interactions for advice on fisheries and ecosystem management. Key runs are multispecies and ecosystem models reviewed against high quality criteria. They are developed to contribute to ICES advice.

This report presents the definition of a key run and an update to the SMS model key run for the Baltic Sea. The updated model extends input time-series to 2024 by extending the data for herring, sprat and cod. The key run provides updated estimates of cod predation mortality for the Baltic Sea sprat and central Baltic Sea herring stocks. Low cod stock size leads to low predation on both herring and sprat. Forecasts of cod abundance are used for parts of 2023 and 2024 due to the most recent Eastern Baltic Sea cod assessment not being accepted. Stomach samples are important for determining predator-prey interactions and alternative stomach sampling designs for the Baltic Sea are evaluated. This provides a framework for how to balance sampling effort with the provision of useful data.

Continuous updates to the Baltic Sea key run require non-forecasted data on cod abundance. Due to the low stock size for cod, inclusion of other sources of predation, such as seals or birds, should be considered.