LONDON, England – Incidents of piracy on the high seas is down to a five-year low, according to a new report by the International Maritime Bureau (IMB).

According to findings released Wednesday (January 16th), "IMB's piracy figures show a welcome reduction in hijackings and attacks to ships. But crews must remain vigilant, particularly in the highly dangerous waters off East and West Africa," said Captain Pottengal Mukundan, director of the IMB, which has monitored piracy worldwide since 1991.

Officials say the chief agent of change was a huge reduction in Somali piracy, though East and West Africa remain the worst hit areas, with 150 attacks last year.

In Southeast Asia, four vessels were hijacked, including a Malaysian tanker subsequently recaptured in Vietnam.

Across the Indonesian archipelago, there were 81 reports of petty theft, accounting for more than a quarter of global incidents in 2012. Thirty vessels were attacked in the last quarter of the year.

IMB noted reports from Indonesia increased every year since 2009. Vessels were boarded in 73 incidents, and 47 crew members were taken hostage. Fourteen incidents were reported at Belawan by ships anchored or berthed.