Over-fishing and eutrophication (too much nutrients) are among the most severe threats to the ecosystems of the Baltic Sea and the ecosystem services they provide. Despite the well-known fact that effective and sustainable management requires cooperation – among as well as within states – appropriate frameworks that work have not yet been constructed and successfully applied. This report summarises findings from a research project on cooperation for sustainable marine governance of the Baltic Sea carried out between 2013 and 2018. Three aspects of central relevance for the understanding of regional cooperation in environmental governance are distinguished: interests, knowledge and management. It is shown that it is not enough to design cooperative arrangements that make the group of users, stakeholders or states better off than without such an arrangement. It is furthermore required that all actors have individual interests to participate, and that free-riding on others’ contributions can be controlled. When this is not the case, effective abatement of eutrophication is not likely to be forthcoming, even though aggregated benefits from such measures are larger than expected costs.

Knowledge often play important roles in marine environmental governance, not least in relation to so-called epistemic communities, that is, groups of experts that share a common understanding of the environmental problem at hand, and how to address it. It is shown that the coherence of the epistemic group can be a crucial factor influencing its impact. In both abatement of eutrophication and management of fish stocks, these expert groups have been somewhat divided, which has limited their impact.

Modes of management can influence cooperation and outcomes in ways that can be difficult to predict. Although environmental taxes and subsidies are powerful policy instruments in contemporary governance, they must be carefully crafted to fit into exiting norms and contexts to be effective. It is shown that monetary incentives targeting farmers’ use of fertilisers tend not to be effective when they are at odds with deeply held norms on what constitute a “good farmer”.