The development of this second edition of these guidelines was in part a response to evidence of the widespread incorrect application of the categories to marine protected areas (MPAs). Marine management and sustainable fisheries management are critical elements of good oceans management, but are not the same as protected areas management, where the primary focus is conservation of nature. The primary purpose of these supplementary guidelines is to increase the accuracy and consistency of assignment and reporting of the IUCN categories when applied to marine and coastal protected areas. These supplementary marine guidelines are aimed at ensuring that the IUCN categories can be effectively applied to all types of MPAs as well as to any marine components of adjoining terrestrial protected areas, provided a site meets the IUCN definition of a protected area.