The last outbreak of Somali piracy cost the world's shipping industry billions of dollars as pirates paralyzed shipping lanes, kidnapped hundreds of seafarers and seized vessels more than 1,000 miles from Somalia's coastline.
Since then, growing use of private security details and the presence of international warships have effectively neutered the pirates. Yet one side effect of this decline has been a rise in illegal fishing, with trawler captains increasingly confident they can operate with impunity, Somali officials say.
Alan Cole, an official at the United Nations Office for Drugs and Crime (ODC), said piracy could return as criminal gangs and pirates use the rise in illegal fishing as a pretext to hijack other vessels.
"The international community has spent millions of dollars trying to counter piracy, help Somalia and make sure that (sea) trade is not interrupted, but because of the activity of a relatively small number of illegal fishing vessels, all that is put at risk," Cole said.
The last successful hijacking took place in May 2012 and some 26 sailors are still being held captive by Somali pirates seeking ransom, down from about 750 at the peak of piracy crisis at the beginning of the decade, U.N. officials said.
Security measures taken by shipping companies and the presence of the 30-country Coalition Maritime Forces (CMF) naval group means any fresh piracy outburst is likely to be contained.
However, the merest hint of a return to the bad old days will once again push up insurance premiums, meaning the cost to the global shipping industry could be significant.
A 2014 report by the Oceans Beyond Piracy group put the total economic cost of Somali piracy -- by far the largest single threat to international shipping in recent years -- at $3.2 billion in 2013, down from $6 billion in 2012.
The issue of illegal fishing has been rising up the political agenda in Somalia, where several hundred Mogadishu residents this month protested against the practice.
Two Iranian-owned fishing vessels, with 48 Iranian sailors on board, were seized and detained earlier in March by angry fishermen near Somalia's coastline, a regional official said. The sailors were handed over to the local government which is still deciding what to do with them.
There is no official data on illegal fishing, but Yaasin Ali Yuusuf, director general of the Ministry of Fisheries in Puntland, a semi-autonomous region, said many South Korean, Chinese and Iranian vessels have been fishing without license in Somali waters, or with forged license.
South Korea dismissed the claim. What had been previously South Korean vessels have since been sold and the real ownership of the vessels now belongs to countries including Oman and Somalia, said an official at Seoul's ministry of fisheries.
Chinese foreign ministry said China has always demanded its citizens fish in accordance to law.
Yuusuf said locals are looking at ways to chase away foreign trawlers -- a move reminiscent of how Somali piracy started in the early 1990s, when successful attacks on fishing boats eventually led to lucrative assaults on oil tankers.
"It's a very serious issue and I’m very concerned ... that it might bring back piracy," said Yuusuf, who added that Somalia could not deal with the illegal fishing problem on its own.
Many Somalis are frustrated naval forces tasked with stopping piracy, as well as the smuggling of drugs and arms, have not detained illegal fishing vessels.
"If they have a mandate to protect the (shipping) lanes from the pirates, they have to protect the resources of these poor people against illegal fishing," said Abdiwahid Mohamed Hersi, chief executive of Global Sea Food International, a Somalia company exporting fish to Oman.