“The problem of illegal fishing is enormously widespread,” observes Michael Lodge, an OECD fisheries expert.
“We have estimated the problem as being as much as 20% of the global catch.”
Since 2000, the UN has been warning about the grave consequences of overfishing in the world’s seas.
However, the impact of illegal fishing is adding to the strain on the already overexploited oceans.
The skippers of the illegal fishing boats tend to favour the waters of some of the poorest nations, which are often inadequately policed as a result of a lack of resources.
The Atlantic Ocean, off the coast of West Africa, is one of the most fertile fishing grounds in the world.
For centuries, the waters have supported generations of small coastal communities, but as the world’s appetite for fish continues to grow, the rich fishing grounds have attracted the attention of illegal vessels.
Many developing nations do not have funds to police their waters.
Almost half of the boats in the area are estimated to be operating outside the law.
Marine conservationist Helen Bours, who has been tracking illegal and unlicensed boats for more than 20 years, says that it is a hidden world of which very little is known.
“These vessels are at sea for years,” she tells Television Trust for the Environment’s (TVE) Earth Report programme on the BBC World News Channel.
“They transfer their fish on to other vessels, they get refuelled at sea; even the crews are changed at sea.
“So nobody sees what’s happening, and there’s nobody to go there and tell them to respect the rules. It’s another world.”
Fisheries experts from the UK government have attempted in recent years to assess the scale of the problem.
“In 2005, we commissioned a major study of the impact of illegal fishing on developing nations,” said Tim Bostock, a fisheries advisor for the UK’s Department for International Development.
“We were able to derive a total figure for the value of fish stolen from the world each year.
This figure was of the order of US $9bn (