Investments in sustainable and green initiatives are needed to ensure the health and productivity of the world's oceans, which are strained by overexploitation, pollution and climate change, according to a UN report released on Wednesday. The report, Green Economy in a Blue World, warned that the ecological health and economic productivity of marine and coastal ecosystems are currently in decline around the globe, threatening food security and development. It called for governments and stakeholders to shift “to a more sustainable economic approach that taps their natural potential – from generating renewable energy and promoting eco-tourism, to sustainable fisheries and transport.” Green Economy was released in Manila during a meeting of experts and officials from 70 countries in the run-up to the UN Conference on Sustainable Development in Brazil in June. It said that approximately 30 percent of the world's fish stocks are overexploited, depleted or recovering from depletion, while 50 per cent are fully exploited. About 20 per cent of mangroves have also been destroyed and more than 60 per cent of tropical reefs are under threat.With as much as 40 per cent of the global population living within 100 kilometers of the coast, the world's marine ecosystems provide essential food, shelter and livelihoods to millions of people, the report added. “Oceans are a key pillar for many countries in their development and fight to tackle poverty, but the wide range of ecosystem services, including food security and climate regulation, provided by marine and coastal environments are today under unprecedented pressure,” said Achim Steiner, executive director of the United Nations Environment Program. “Stepping up green investments in marine and coastal resources and enhancing international cooperation in managing these trans-boundary ecosystems are essential if a transition to a low-carbon, resource-efficient green economy is to be realized.” The report recommended using low-impact fuel-efficient fishing methods, adopting innovative aquaculture production systems and harnessing community fishing associations to improve sustainable use of marine resources. The world economy could gain up to $50 billion annually if such efforts were implemented to restore fish stocks and reduce fishing capacity, according to estimates.