Conserve and sustainably use the oceans, seas and marine resources for sustainable development 18. The increasingly adverse impacts of climate change (including ocean acidification), overfishing and marine pollution are jeopardizing recent gains in protecting portions of the world’s oceans.
- Global trends point to continued deterioration of coastal waters owing to pollution and eutrophication (excessive nutrients in water, frequently a result of run-off from land, which causes dense plant growth and the death of animal life from lack of oxygen). Of the 63 large marine ecosystems evaluated under the Transboundary Waters Assessment Programme, 16 per cent of the ecosystems are in the “high” or “highest” risk categories for coastal eutrophication. They are located mainly in Western Europe, Southern and Eastern Asia, and the Gulf of Mexico.
- Ocean acidification is closely linked to shifts in the carbonate chemistry of the waters, which can lead to a significant weakening of the shells and skeletons of many marine species (such as reef-building corals and shelled molluscs).
- Studies of marine acidity at open ocean and coastal sites around the world have indicated that current levels are often outside preindustrial bounds.
- Overfishing reduces food production, impairs the functioning of ecosystems and reduces biodiversity. The proportion of world marine fish stocks within biologically sustainable levels has declined from 90 per cent in 1974 to 68.6 per cent in 2013. However, the trend has slowed and appears to have stabilized from 2008 to 2013.
- Small-scale fisheries face numerous challenges. In response, about 70 per cent of the respondents to a survey representing 92 countries and the European Union have introduced or developed regulations, policies, laws, plans or strategies specifically targeting small-scale fisheries.
- When effectively managed and well resourced, marine protected areas are important mechanisms for safeguarding ocean life. In 2017, protected areas cover 13.2 per cent of the marine environment under national jurisdiction (up to 200 nautical miles from shore), 0.25 per cent of the marine environment beyond national jurisdiction and 5.3 per cent of the total global ocean area.
Source: Report of the Secretary-General, "Progress towards the Sustainable Development Goals", E/2017/66