Human communities often utilize areas of the sea for purposes which are not primarily aimed at nature conservation, but which may in some circumstances have a positive and reinforcing effect on ecosystems. Examples are:

• Areas with common fisheries management;
• Marine and coastal regions that are managed for tourism;
• Wind farms and oil rigs, which contribute in various ways to increasing biodiversity around subsea infrastructures;
• Marine and coastal areas that are reserved for other purposes but may also support nature conservation, e.g. military training areas, coastal defences, protected channels for communications cables and pipelines, and areas of the sea in which, due to their significance for marine life, special regulations apply to shipping;
• Large ocean regions (e.g. the Northeast Atlantic or Baltic Sea region) in which certain species are legally protected on a transboundary basis.

If these forms of use of the oceans strengthen local ecosystems, they are known as „Other Effective Area-Based Conservation Measures“ (OECMs). Less than one per cent of the world’s terrestrial and freshwater environments and less than 0.1 per cent of marine areas are currently designated as OECMs. However, now that the international community has embraced the target of protecting and conserving ecosystems in at least 30 per cent of the ocean by 2030 and only using them sustainably, OECMs are becoming more important as a management tool – for as experience shows, marine protected areas alone will not suffice to end the climate and biodiversity crisis affecting the ocean.