Motivated by a few sky-high ransom paydays, Somali pirates are holding on to hijacked ships and crew almost twice as long as they did only 18 months ago, prolonging the hostages' ordeal and increasing their numbers to above 500, a possible record.

Ships hijacked in April, May and June have been held an average of 106 days, up sharply from the 55 days that the average ship hijacked in early 2009 was held, maritime expert Cyrus Mody told The Associated Press. Pirates now hold 508 hostages from 22 vessels, Mody said Thursday.

"People are making really huge amounts of money now," said Roger Middleton, a piracy expert at the London-based think tank Chatham House. He said that whereas pirates in 2009 and 2008 were getting around $1 million per vessel, ransoms appear to be going higher. Middleton said reports that a $9.5 million ransom was paid earlier this month for a South Korean tanker carrying crude oil were credible.

"Maybe the increased ransoms have changed the pirates' expectations of what they should be being paid, that they should hold out longer for a higher ransom," Middleton said. "The pirates are thinking, well, let's aim for a little more."

The last four ships released by pirates were held an average of 150 days, said Mody, an analyst with the London-based International Maritime Bureau.

The hostages believed to have been held the longest were released Sunday after being held for 388 days. Yet the case of Paul and Rachel Chandler — private citizens who were taken from a 38-foot yacht near the island nation of Seychelles — is different from most. Usually pirates go after shipping vessels, taking the one or two dozen crew onboard hostage.

Shipping companies behind those vessels typically pay a ransom that now appears to average more than $2 million, said Middleton. The Chandlers are not wealthy and had no company behind them, which is probably why they were held longer than other hostages.

It's not clear if the total number of people being held captive by pirates is a record because such statistics aren't kept. But last November pirates held about 200 hostages, and the current number of 508 is extraordinarily high.

The mariners are being held captive in a hot, dry corner of Somalia controlled by pirates with little or nothing to do to fill their days.

"We are happy to be alive, happy to be here, desperate to see our family, and so happy to be amongst decent, everyday people ... because we've been a year with criminals and that's not a very nice thing to be doing," Rachel Chandler said on Sunday, the day she and her husband were finally released.

For a ship taken in the first quarter of 2009, the average hostage situation lasted 55 days, 77 days for a ship taken in the second quarter, 89 in the third quarter and 91 in the fourth, Mody said.

Hostage times kept getting longer this year. In the first quarter of 2010 the average length was 101 days. It rose to 106 days in the second quarter, he said.

One of the longest held vessels is the Raf Africana, which pirates seized on April 11 between the Seychelles and the Kenyan coast. The crew of 26 from India, Pakistan and Tanzania is still being held.

The ship's owner, Ajak Kotwal, the chief executive of United Arab Emirates-based Rak Training Ship Sindbad, said "these despicable" pirates are pressuring him to pay a high ransom. Kotwal said he has no income because one ship is hijacked and his other has technical problems. He told AP he has exhausted all sources that could assist him financially.

"The RAK Africana has now been hijacked for 207 days," Kotwal said in an e-mail earlier this month. "During this period my primary concern has been the crew and their families. I have done all in my power to achieve their release and continue to do so. The families of the crew are suffering terribly and I am trying to do all I can to support them."

No ship and crew has ever been abandoned by the ship's owner. Middleton said the shipping industry has been good at making sure its sailors are released, although there have been situations — like Kotwal's — where it has been difficult for ship owners to scrape together ransom money.

Countries are taking more measures to protect against piracy. The Kenyan Maritime Authority announced Thursday that ships heading to the port of Mombasa will be protected by the country's navy. That step follows recent hijackings in Kenyan waters.

The EU's anti-piracy force, which has taken more aggressive action over the last year to thwart hijack attempts, said it intercepted a skiff Wednesday with seven suspected pirates on board. Two rocket-propelled grenades and an AK-47 were confiscated and the suspects were taken to Somalia.

Before the $9.5 million payment this month, another shipping company paid $7.5 million, Middleton said, an indication that pirates are getting better at extracting money.

"It only takes a few ship companies willing to pay $9 million or $7 million to get pirates to hang on to ships and crew for longer periods of time," Middleton said.


Associated Press reporter Hooman Nasri in Dubai, United Arab Emirates contributed to this report.