This publication reviews the costs and benefits of climate change adaptation measures in the fisheries and aquaculture sector. It highlights the challenges of applying conventional appraisal and decision-support tools in this context, examines emerging frameworks, and looks into economic tools for appraising adaptation options. With increased international finance available for climate change adaptation, and the emergence of national adaptation plans and projects, there is a growing focus on the economic appraisal of adaptation. Economic appraisal is standard practice in public-sector investment decisions in many countries, as well as in international development finance and assistance. It helps decision-makers to ensure appropriate use of available resources, and to assess the options available for meeting objectives by assessing costs, benefits and performance against other decision criteria. According to this paper, available evidence is insufficient and a key priority is to improve the application of economic analysis to adaptation case studies. The publication also provides supplementary guidance for application of the adaptation toolbox developed by FAO in 2018 to help guide communities, countries and other key stakeholders in their adaptation efforts.