Köster's lecture will focus on the scientific knowledge base needed for explaining historical and projected fish stock dynamics, drawing on, amongst others, the findings of the recent ICES/NAFO Gadoid symposium on Ecology and Management of Rebuilding. The examples will include successful stock recoveries and continued depletions as well as unexpected stock declines. Gadoids will be used as examples, such as the anticipated successful recovery and subsequent failure to assess the status of one of the most well-studied groundfish stocks – the eastern Baltic cod. However, also cross comparisons to other stocks and species will be made, contrasting different life history characteristics, exploitation and ecosystem settings.
Köster will demonstrate the need for process understanding, especially in situations when purely observation based stock assessments fail and changes in ecosystems occur. This includes quantification of key population dynamic rates, such as mortality, growth, maturation; sound knowledge on stock structure as well as recruitment processes. Further, to understand top-down and bottom-up controls of stock dynamics requires sound information on all trophic levels, their temporal and spatial dynamics as well as physical and anthropogenic forcing. This in turn requires an integrated ecosystem monitoring, commonly structured and accessible data bases and modelling tools capable of handling physical, chemical and biological interactions and the complexity of ecosystems.
The talk will review scientific and technological progress made to potentially overcome some of these challenges and will identify future research and monitoring needs. Finally, it will emphasize the importance of cooperation and coordination between different scientific disciplines, nations and international organizations to allow for better integration of the information available and share costly work efforts.
Fritz W. Köster, DTU AQUA, Denmark