Human activities have substantial impacts on marine ecosystems, including rapid regime shifts with large consequences for human well-being. We highlight the use of model-based scenarios as a scientific tool for adaptive stewardship in the face of such consequences. The natural sciences have a long history of developing scenarios but rarely with an in-depth understanding of factors influencing human actions. Social scientists have traditionally investigated human behavior, but scholars often argue that behavior is too complex to be repre-ented by broad generalizations useful for models and scenarios. We address this scientific divide with a framework for integrated marine social ecological scenarios, combining quantitative process-based models from the biogeochemical and ecological disciplines with qualitative studies on governance and social change. The aim is to develop policy-relevant scenarios based on an in-depth empirical understanding from both the natural and the social sciences, thereby contributing to adaptive stewardship of marine social-ecological systems.

The roles of governance and technological innovation have been widely recognized as important parts of sustainability transitions. However, less attention has been paid to understanding the mechanisms of the emergence and spread of innovative ideas for stewardship of social-ecological systems. This study considers how theories of innovation and agency are able to provide explanatory power regarding the spread and impact of such ideas. This includes how innovations may contribute to resolving the mismatches between the scale of ecological processes and the scale of governance of ecosystems. The emergence and spread of Marine Spatial Planning (MSP) is used as an illustrative case study. The study shows that individuals embedded in informal networks have played a key role in driving the emergence of MSP across scales and in constantly re-framing the tool in order to overcome obstacles to adoption and implementation. In a number of cases, MSP has been decoupled from the ecosystem despite being framed as a tool for ecosystem-based management. Finally, this study is important to understand the process of emergence of new integrated tools for ecosystem stewardship at the global level.

The expanse of ocean which makes up all marine areas beyond national jurisdiction has been characterized as the last frontier of exploitation on the planet, a figurative final Wild West. Existing users of areas beyond national jurisdiction, with the exception of fisheries, currently have a limited footprint there as a consequence, in part, of substantial hurdles in technological development that need to be overcome before many resources can be extracted at a commercially viable scale. However, we argue surprise shifts perpetuated by both established and emerging users could lead to an expansion in actors taking opportunities to chase lucrative resources that they are currently constrained from exploiting. Rapid development could also lead to a crowded ocean due to the multiplication of users which could present a problem given the current lack of a unified institutional framework for governance connecting the different user groups. Here, we have collated trends in human use of areas beyond national jurisdiction and offer a framework for, and examples of, unexpected dynamics relevant to living and non-living marine resources. Such an approach is necessary in order to begin to mobilize an adequate governance response to changing conditions and uses of areas beyond national jurisdiction. This governance response must be able to govern established or potential users, be flexible and adaptive in response to unexpected and unpredictable dynamics and be able to transform in the face of unpredictable future uses of this vast area. Here we present a set of institutional design principles as a first tentative step in this direction.

Scenarios are important tools in developing capacity for dealing with the unknown and unpredictable, as well as the unlikely but possible. A range of scientific methods for developing scenarios is available, but we argue that they have limited capacity to investigate complex social-ecological futures. We contend that for most scientific scenarios 1) non-linear change is rarely incorporated and that 2) in attempting to engage with complexity they often fail to interest an audience outside of academia. This manuscript intends to address these two concerns, by drawing on narrative approaches to scenarios and applying the method of Science Fiction Prototyping. Using a rich and empirical scientific background on existing and emerging trends in marine natural resource use and dynamics, we develop four ‘radical’ futures for global fisheries. They are written for a wide audience and each was carefully designed to incorporate and extrapolate from existing environmental, technological, social and economic trends. We argue that Science Fiction Prototyping can complement existing methods for developing scenarios and can assist scientists in developing a holistic understanding of complex systems dynamics. This approach holds promise for making scenarios more accessible and interesting to non-academics and thus more useful in discussion on policy and governance questions in marine fisheries.