Workshop on establishing a roadmap for possible sonservation measures for herring in the Baltic (WKHERBAL)

The Workshop on establishing a roadmap for possible conservation measures for Herring in the Baltic (WKHERBAL) was established in response to a special request from DGMARE. The potential drivers of the observed changes in age and size structure and condition of central Baltic and Gulf of Bothnia herring (Clupea harengus) stocks were discussed.The timing of the observed declines was notably different between the two stocks with the decline in Central Baltic herring starting in the mid-1980s and lasting over a decade to the late 1990s. Whereas the decline in the Gulf of Bothnia started around 1990 and continued until the mid-2000s. Both stocks also show a similar sudden decline in weight-at-age in 2021 followed by a recovery in 2022. The reasons for these changes are likely to be multifactorial and while several possible causes have been suggested the relative contribution of these has not been established.WKHERBAL identified several actions in the short and long-term to further investigate the potential drivers of the observed changes in age and size structure and condition. These actions can be further elaborated and supported through dedicated scoping and resourcing to transform them into an operational roadmap to address the six evidence needs identified in the request. To implement the proposed actions, effective and sustained cooperation between all relevant Baltic Sea countries is needed.