Sustainable Societies

Oceans and Seas

Oceans and seas cover three-quarters of the Earth's surface and are indispensable parts of the life-sustaining hydrologic cycle. Their biological diversity is vital for economic prosperity, poverty alleviation and food security and they also sequester carbon. However, humans have severely damaged them through overfishing and pollution. Consider the following:

• Today's ocean fish populations are only 17% of what they were 100 years ago.
• 90% of large predatory fish populations, including tuna and cod, are gone.
• 40 million sharks per year are caught, have their fins harvested, and are dumped alive but dying back into the sea.
• Over 250,000 turtles get entangled in fishing gear each year.
• Coral reef populations have declined 50 to 90 percent in 40 years.
• Bottom trawling nets indiscriminately catch everything they encounter and permanently damage large areas of sea floor habitats while unwanted species are discarded overboard, dead or dying.

Global warming is raising sea levels, increasing flooding, and impacting the lives and livelihoods of millions of people while accelerating the process of ocean acidification. About 25% of excess atmospheric CO2 is absorbed into the ocean, lowering pH levels and increasing acidification.

Oceans and seas must be protected and managed wisely. There are ways to restore coastal ecosystems and increase fish populations. These include pollution mitigation measures such as the protection of coastal wetlands, increased wastewater treatment, and the planting of vegetated (riparian) buffers along riverbanks and coastal lands. Marine life conservation areas and no-fishing zones can be expanded to protect breeding areas, especially coral reefs and mangrove swamps, and catch limits can be implemented to allow fish stocks to recover. These practices work and must be replicated.