Large, commercial vessels illegally stripping the sea of fish are driving some desperate local fisherman to become pirates who in turn harass merchant fleets so they can feed their families.
It's a vicious cycle of piracy that people in government and shipping worry could become worse, especially as piracy around the world becomes more sophisticated, and more successful.
"When people don't have any way of feeding their families by fishing, they don't have many options," said Lisa Speer, director of the international oceans program at the Natural Resources Defense Council.
Local fishermen who have plied their trade for generations in Latin America, Africa, Asia and even Northern Europe increasingly find their livelihood threatened by commercial fishing operations whose scale and more advanced vessels are just too much to compete against.
"When people don't have any way of feeding their families by fishing, they don't have many options."
Though it's impossible to quantify how many pirates were once fishermen, experts agree that many small fishermen have turned to stealing from big merchant ships as their fisheries have been wiped out.
Countries that border on an ocean all have a 200-mile boundary within which they have exclusive fishing rights. (Exclusive economic zones extend much further into the ocean than "territorial waters" do.) But poorer countries often don't have the naval craft needed to patrol and protect their own rightful economic zones.
The problem is exacerbated by commercial fishing companies that fly "flags of convenience" on their ships. Companies illegally poaching on a country's fishing rights often fly the national flag of some third-party nation — usually one that can't or won't exert control over its own flagged vessels — to conceal their true identities and avoid international laws, according to a 2012 report from the Food and Agriculture Organization of the United Nations. Some flag-of-convenience countries, such as Bolivia and Mongolia, are landlocked.
Other reports from government agencies, such as Australia's Department of Agriculture, Fisheries and Forestry, support those U.N. findings. Illegal fishing operations take between $10 billion and $23.5 billion worth of fish annually.
Decimating the Fish
Such illegal fishing ships, which are much bigger than private fishermen's vessels and can haul in tons of fish, sometimes decimate the fishing stock of a particular area and then move on to somewhere else. That leaves local fishermen without a livelihood. Some of them are turning to piracy, especially as pirates from Indonesia, Malaysia, the Horn of Africa or Nigeria repeatedly demonstrate how profitable it can be.
"If enough impoverished areas of the world feel that what [the pirates] have carried out has been very successful, this will spread," Capt. David Watkins, a fleet quality assurance manager for Swire Group's China Navigation unit, told CNBC this month.
The widespread dependence on fishing for people in poor nations is demonstrated by examining aggregated data on the world's fishing fleet. There were about 4.7 million fishing vessels in operation in 2012, according to the United Nations, of which only 57 percent are motorized.
Among the vessels with engines, about 79 percent are under 12 meters (about 39 feet) in length.
An Australian government examination of data from naval insurer Lloyd's Register of Ships found that many of the companies that use flags of convenience are actually based in Taiwan and the European Union, with Spanish firms accounting for about half of the EU total. Russia is another prominent flag-hopping nation, according to Lloyd's.
The most common flags of convenience come from Panama, Liberia, the Marshall Islands and Malta. More than half of the world's merchant fleet is flagged to one of those countries, according to the U.S. Central Intelligence Agency.