Perhaps the most obvious explanation for the drop in attacks in Somalia is the increase in naval patrols of the region, with the European Union and Nato among organisations contributing resources to monitoring the vast area of sea in which the pirates operate.
Other states, such as China and Japan, have also mounted their own operations.
Changes in management practices on board have also helped: boats have better lookouts; simple deterrents such as water hoses and razor wire have been applied and some ships have been equipped with safe rooms, known as citadels, so crews have somewhere to hide safely if their vessel is attacked.
The International Maritime Organisation (IMO), the UN agency responsible for shipping, recently said it remained convinced "that the only long-term solution to piracy is to establish effective government and implement the rule of law ashore in Somalia".
However, until that is achieved, it warned there could be no room for complacency.
"Any reduction in the level of protection of merchant ships could lead to a resurgence of pirate activities. Piracy must continue to be suppressed through the visible presence of and robust action by, the world's navies, consistent with international law," the IMO said.
Michael Sharp, who underwrites kidnap and ransom risk at Beazley, a Lloyd's of London underwriter, says the decreasing incidence of piracy in Somalia may not be long-lasting.
"It is difficult to predict whether this trend will continue. With increased financial pressure on vessel owners it is likely that there could be a decrease in the number of vessels carrying armed guards going forward, which may result in an increase in piracy incidents once again."
Mark Lowe, the editor in chief of Marine Safety Review, an online information service for those in the marine industry, says the fall in pirate attacks also has much to do with military presence. "Piracy from Somalia is a diminishing problem - in part because of the four naval contingents there, as well as better management practices and the use of armed security details on commercial vessels."
He also believes the Somalian government has had some influence on the ground.
"They've been told to cool it and just enjoy the profits they have made," he suggests, of the warlords running the pirates.
With a long heritage of serving the shipping industry, several London-based businesses have also said they intended to launch private navies to escort merchant ships through the worst-affected areas of the Gulf of Aden.
One is called Typhon and is aiming to operate from the UAE, although which sovereign flag its boats will sail under is in negotiation. The company boasted some business and military luminaries on its board - including the former chief of the United Kingdom's defence staff Lord Dannatt - and was chaired by Simon Murray, the former chairman of the commodities trader Glencore.
However, more than 18 months after the company was first unveiled, it is yet to launch. A spokeswoman for the company would say only negotiations were still taking place.
In the UK's Daily Telegraph last year, Typhon's chief executive Anthony Sharp said the company's patrol boats would carry a crew of 20 and have 40 "security personnel" on board, recruited from former British servicemen. The ships would also carry a drone, for long-range surveillance, to detect any suspicious vessels approaching the convoy. Mr Sharp said Typhon's philosophy was not about matching the pirates' lethal force. "We are there to deter. Once any approaching pirate sees he is facing a credible force, experience tells us he will not risk an attack," he said.
Neil Roberts, the secretary to the London market's joint war committee, which is made up of underwriting specialists, says ship owners may also baulk at the additional expense of employing such outfits.
"Some of the British companies have run into difficulties getting going. The question is whether the ship owners, that are having their own cost pressures, will be prepared to pay for these services now."