Biodiversity is being lost in all the world's seas, at catastrophic rates in some.
Biodiversity conservation has historically focused on the terrestrial environment, and while there are common principles for the conservation of terrestrial and marine biodiversity, there are also several characteristics of the marine and coastal environment that present decision-makers and resource managers with a unique set of problems. Marine resources fall under national ownership, but not in oceanic waters outside of this area; the fact that species straddle or migrate across political boundaries; the "invisibility" of marine, coastal and other aquatic environments, which makes research and monitoring particularly difficult; and the environmental continuity of the oceans, meaning that local impacts may have global effects. Adding complexity to this situation is the fact that aquatic organisms - primarily fish - are the only major human food resource harvested directly from wild populations.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities. Agenda 21 recommends that states should identify marine ecosystems exhibiting high levels of biodiversity and productivity and other critical habitat areas and should provide necessary limitations on use in these areas, through, [inter alia], designation of protected areas. Priority should be accorded, as appropriate, to: coral reef ecosystems; estuaries; temperate and tropical wetlands, including mangroves; seagrass beds; other spawning and nursery areas.
The [Convention on Biological Diversity] (1992) requires that contracting parties shall implement the Convention with respect to the marine environment consistently with the rights and obligations of states under the law of the sea.