More than 20 million people employed in the fishing industry may need to be taken out of service and retrained for other work over the next 40 years if the final collapse of fish stocks in oceans around the globe is to be avoided, the UN has warned. The UN's environment branch, UNEP, gave a sneak preview of its green economy report that will be published in October. It said that if the world remained on its current path of over-fishing, by 2050 all fish stocks could have become uneconomic to exploit or actually extinct. Pavan Sukhdev, who heads UNEP's green economy initiative, said: "That is not as absurd as it sounds, as already 30% of the ocean fisheries have collapsed and are producing less than 10% of their original ability." At the heart of the UN's analysis is the $27bn of subsidies it estimates is being injected into fishing every year, mainly by developing countries. The UN says the subsidies are huge in terms of the scale of the industry � amounting to almost a third of the $85bn total value of fish caught. Among those subsidies, the UN defines just $8bn-worth as "good" in the sense of encouraging sustainable fishing of healthy stocks. Most of the subsidies are "bad", meaning they lead to overcapacity and exploitation, and about $3bn of the subsidies are "ugly", actively leading to the depletion of fish populations. Among the most egregious practices targeted by the report are inducements to increase the size of massive trawler fleets that are among the main culprits of overfishing, and fuel subsidies on fuel for fleets. "We are paying ourselves to destroy the very resource on which the whole fishing industry is dependent. We are in the process of eroding the natural capital that underpins our economies," said Achim Steiner, UNEP's director. At stake is not just the biodiversity of the oceans, but a substantial chunk of the global economy and the livelihoods that depend on it. The UN estimates there are about 35 million people directly employed in fishing, which translates to about 120 million including their households and 500 million � or about 8% of global population � taking into account indirect businesses such as packaging, freezing and transport. It is also a huge health issue, as fish provides the main source of animal protein for one billion of the world's poorest people. The paradox is that there is so much overfishing going on that the industry has become increasingly inefficient. The UN believes that by switching from large trawler fleets to more sustainable local or 'artisanal' fishing, fish stocks will recover and the total size of catch will grow. It is proposing an investment of $8bn a year over the next 40 years to help fish stocks recover. That would involve taking up to 13 million of the 20 million boats now actively fishing out of service, and retraining up to 22 million fishers for other work.