The most widely applied decision-making process for balancing the trade-offs between conservation and development activities is the biodiversity mitigation process, implemented using environmental impact assessment supported by a conceptual ‘mitigation hierarchy’ framework. Yet to date, the exploration of the biodiversity mitigation process to the primary resource sectors has not been widely investigated as a subject of study in conservation. In this thesis, I explore mitigating impacts from fisheries on marine megafauna, linking system-wide approaches with individual-level incentives in a unified framework. The majority of this thesis focusses on a case study of sea turtle captures and mortalities in a coastal fishing community in Peru. A linked, but separate case study explores the application of the framework to all human impact on biodiversity more broadly. I begin at the broadest scale, by exploring challenges and solutions for a global mitigation hierarchy for nature conservation that could enable tracking of progress towards an agreed overarching objective, based on net conservation outcomes. The global framework research precedes an exploration of the biodiversity mitigation process in the case study coastal fishing system. Throughout the fishery case study, I draw on established decision-making processes to better understand the conservation issue at hand and to develop an understanding of what is necessary to empirically calculate net outcomes in data-poor fishing systems using the proposed framework. The decision-making processes I employ include qualitative ecological risk assessment theory to assess the efficacy of current management systems, and a qualitative management strategy evaluation process to support consideration of trade-offs. I seek to further improve data gathering processes in data-poor fishing systems by applying the IDEA (“Investigate”, “Discuss”, “Estimate” and “Aggregate”) structured elicitation protocol to control for personal bias and heuristics when drawing on stakeholder knowledge. Finally, I characterise the social network of fishing-related information-sharing between fishers to inform understanding of social influences on decision making using network null models. As humanity seeks to deliver nature conservation alongside development, broader perspectives on human impacts, and how best to mitigate them are needed. This research contributes to an important and timely dialogue that seeks to shift emphasis away from piecemeal actions that prevent biodiversity loss, and instead adopt a strategic and proactive approach to restoring nature that links broad scale concepts to locally tailored solutions.