Emilie, Nanda and Clara celebrating the accomplishment and approval of the thesis!

I had the wonderful opportunity to write my master thesis within the SES-LINK group at the Stockholm Resilience Centre under the supervision of Dr. Emilie Lindkvist and Dr. Nanda Wijermans. Also involved were Prof. Maja Schlüter and Dr. Tim Daw, as well as Prof. Ulrike Feudel from my home university in Oldenburg.

The underlying question of my thesis was “how to formalise complex population dynamics for a stylised ecological model of small-scale fisheries?” – the complement to social modeling within a social-ecological system perspective. 

It has been found that the few social-ecological models of small-scale fisheries (SSF) pay less attention to the ecological side – often representing only a highly simplified implementation of the ecosystem, too simplistic for the diverse ecological realities of SSF. As these tools explore, test and predict certain outcomes of policy decision-making its reliability is essential. This can be strengthened by including ecological aspects for SSF, such as multiple species, habitats, physical parameters, environmental variability, and more. However, to keep model interpretation possible, maintaining a medium level of complexity of the ecosystem was essential. 

Not only the lack of the ecological component in SSF models is problematic but also the one of the key issues of interdisciplinary science: the communication issue across disciplines. Hence, my thesis  further contributes to establish a foundation for an interdisciplinary dialogue between modelers of different research fields. Both challenges were worked on and discussed in my thesis.  

Starting from a literature review, my thesis provides a list of relevant fishery and/or marine ecosystem models (in total 57 models and 14 case studies using relevant modeling approaches) as well as a taxonomy and a preselection of these models.  The analysis of the identified models demonstrated that  

• The concept of a model of intermediate complexity ecosystem assessment (MICE) best captures the need for modeling fish dynamics for a stylized ecosystem model for SSF.
• The best practice advice on how to design each aspect of an ecosystem model for fisheries, given by the Food and Agriculture Organization of the United Nations (FAO) (2008), are additionally important to consider. 

Besides the analysis of existing models, a detailed elaboration of developing an ecosystem-based fishery model was worked out. First, by giving an overview on the possibilities of how to implement the ecosystem based on what was found in the literature. Second, by developing guidance within a questionnaire for modelers focusing on the implementation of multi-species and spatial environmental considerations. Furthermore, general model resolution and structural recommendations as well as the link to the human component were discussed. Thereby, a detailed overview on ecological modeling is given, serving as a basis for collaboration of modelers from other fields (e.g. social science) to improve the interdisciplinary exchange. The resulting questionnaire was subsequently applied to the case study OctoPINTS (also a project at SES-LINK) and corresponding recommendations for how to proceed with the modeling were given.  

A guide to formalizing the ecological system in small-scale fisheries models. Each step is elaborated on in the thesis.

Curious what my thesis says in detail? Then follow this link to the PDF with the complete thesis. 

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