Somalia piracy attacks against merchant shipping fell to the lowest in six years in the third quarter as armed guards on vessels and naval patrols cut attempted hijacks on the trade route linking Asia and Europe.

One ship was attacked compared with 36 in the same quarter a year ago, the London-based International Maritime Bureau, which has been tracking incidents since 1991, said in an e- mailed report today. That's the fewest since the same period in 2006, when no attacks were reported, Assistant Director Cyrus Mody said by e-mail.

Governments spent almost $1.3 billion last year on military interventions including naval patrols, the One Earth Future Foundation, a Broomfield, Colorado-based non-profit, said in February. Attacks cost the industry and governments $6.9 billion last year, it estimated. Fourteen out of 28 ships briefed by the U.K.'s Royal Navy in the week to Oct. 19 were carrying or recently carried armed guards, U.K. Maritime Trade Operations said in an e-mailed report Oct. 20.

"We welcome the successful robust targeting of pirate action groups by international navies in the high-risk waters off Somalia," IMB Director Pottengal Mukundan said in the report. "There can be no room for complacency. These waters are still extremely high-risk and the naval presence must be maintained."

Trade worth $952 billion transited the Gulf of Aden and Indian Ocean in 2009, according to a 2011 report for the U.K.'s Chamber of Shipping and the London-based Oil Companies International Marine Forum.

About 48,000 vessels a year sail through the Indian Ocean, and 23,000 transit the Gulf of Aden, the European Union Naval Force Somalia said in June 2011 evidence to a U.K. parliamentary inquiry. Ships using Egypt's Suez Canal pass Somalia when sailing to Europe from Asia and the Middle East.

Somali attacks in the first nine months declined to 70 from 199 a year ago, the report said.

While attacks off Somalia slumped, incidents off West Africa climbed to 34 in the first nine months of 2012 from 30 a year earlier. The number of attacks off Indonesia advanced to 51 from 46 for all of 2011, it said. (Bloomberg)