Around the globe, fisheries managers strives to practise effective management that provides a clear path towards conserving ocean biodiversity while contributing to human well-being. A wide range of area-based fisheries management tools achieve positive biodiversity outcomes. Many also conform to the definition, criteria, and guidance on ‘other effective area-based conservation measures’ (OECMs) developed by the Convention on Biological Diversity Conference of Parties. In a fisheries context, OECMs are established, spatially defined management and/or conservation measures other than protected areas, which produce positive, long-term and in situ biodiversity outcomes, in addition to the intended fishery outcomes. However, considerable confusion abounds with regard to which measures qualify as OECMs. This handbook, the first product published under the FAO Fisheries OECM series, aims to promote practical guidance on issues related to Fisheries OECMs, describes key characteristics of Fisheries OECMs and outlines a basic process for identifying, evaluating and reporting OECMs in marine fisheries in order to encourage global recognition of the role that fisheries management plays in biodiversity conservation.