Ecosystem based management of fish stocks in the North Sea (ECOMAN)

The ecosystem approach to fisheries management is a key element in the Common Fisheries Policy (CFP). In light of the importance of the North Sea to the Danish fisheries, Denmark needs to take a leading role in the development of best practice and methods for the implementation of the ecosystem approach to fisheries management.

The ECOMAN project consisted of five separate work packages. WP1: Sampling designs should ensure the provision of accurate data on biological parameters and stock information to be used as input to single-species assessments and multi-species models. Via this project, we were able to engage in discussions and thereby influence the development of data collection approaches.

WP2: The productivity of fish stocks in the North Sea has undergone substantial changes in recent decades, with some species increasing in numbers, while other species have shown prolonged recruitment failure with a resulting decline in stock size. Here we investigated multiple aspects of stock productivity in order to identify important drivers, such as density dependent regulation and spawner quality; all of which are ecological processes not accounted for conventional stock-by-stock fisheries management.

Also methods for estimating biomass reference points were scrutinized and changes over time in the environmental conditions were visited. The latter results provided a basis for improving how reference points are defined and which processes needs further attention (i.e. in management strategy evaluations).

WP3: Natural mortality is a key component of estimation of historical stock development and the setting of reference points such as Bescapement, MSY Btrigger, FMSY and Fcap. The natural mortality varies considerably over time, and particularly the mortality introduced by grey seal and mackerel has increased for North Sea fish stocks in the most recent decades.

The present project was used to built an application that allow scientists and stakeholders to view (interactively) the results produced by the complex SMS multispecies model applied by ICES; who-eats-who? And how much?. WP4: The landing obligation (LO) reform of the CFP is a major challenge to a successful implementation of an ecosystem approach to fisheries management, and the ultimate aim should be to avoid bycatch species while maximizing the catch of target species.

One way to address this issue is to make informed decisions in management based on the consequences for both the target stocks, bycatch species, and fisheries. The ECOMAN project contributed significantly to the development of mixed fisheries modeling by considering the potential effects of controlling the selectivity patterns in the fisheries.

WP5: Lastly, we acknowledge the importance, for the subsequent uptake of results, of involving stakeholders and international experts in the process. A major output of the ECOMAN project is therefore the web site https://sites.dtu.dk/ecoman. The purpose of this web site is to provide an easy way to access complex data, analysis and information relevant to scientists as well as stakeholders interested in ecosystem based fisheries management.

The ECOMAN project has also served as a precursor to the Horizon 2020 project SEAWISE.