"An Iranian vessel, fishing illegally in Somali waters, was hijacked earlier this week," said Alan Cole of the United Nations Office on Drugs and Crime (UNODC).
At its peak in 2011, Somali pirates were responsible for the hijacking of 28 vessels and 237 incidents, but international navies and armed guards on ships reduced attacks.
Until the Iranian vessel was seized off Ceel Huur in the Mudug region this week, there had been no successful hijackings since May 2012, according to the UNODC.
In the past, Somali pirates justified their attacks saying they had to defend their fishing grounds from illegal trawlers. The reduction in piracy has been met with an increase in illegal fishing with many vessels brazenly trawling waters less than five miles off the Somali coast, where the Iranian vessel was seized.
"These are the conditions that started piracy in the first place," said Cole, warning that a resurgence could be on the horizon.
Initial reports on Monday suggested that local maritime police had arrested the illegal fishermen and impounded their vessel, but a senior official in the Himan and Heeb administration has denied their forces were involved.
Two South Korean vessels, currently known to be fishing along the Somali coast close to where the Iranian trawler was seized, are thought to be at risk.
"This was not Himan and Heeb police, but criminals and pirates using the excuse of illegal fishing to take a vessel and crew with the object of holding them for ransom," said John Steed, a retired British colonel who has negotiated the release of many hostages.
"There is a huge amount of illegal fishing going on right now."
Source : Middle East Online