Shipping agents say the companies are reluctant to pull out of a transit market that has served the whole region and still has great long-term potential because of its location.
"No major regular shipping lines are quitting at the moment. Once they withdraw from any service, it's very hard to restore," said Talal Halawani, a shipper whose Amman-based Liberty Shipping is an agent of a leading Italian line.
"Although they are suffering because cargo is not like before, they are still operating normally despite all the constraints. It's a wait-and-see attitude."
But other regional companies with no regular services have less ability to sustain losses, and they have omitted port calls or cancelled visits to Syrian ports altogether.
"Liners that made container ship calls four times a month are now calling three times a month. Some regional liners, including one or two Turkish liners, have even dropped port calls altogether," said a second Syrian transportation official.
Some shippers are seeking to offset the drop in their Syrian trade by offering more competitive rates for container slots in nearby Beirut, Mersin and Alexandria ports, which are in the same Europe-Mediterranean service.
The turmoil has prompted many lines to suspend plans, some drawn up only a few months ago, to add more container slots or introduce bigger vessels on Syrian port calls in anticipation of demand related to the reconstruction of Iraq.
Over the past five years, Syrian ports were able to boost their transit trade with Iraq, Jordan and the Arabian peninsula as Syria's red tape and state controls, a legacy of five decades of Soviet-style economic management, were reduced.
Latakia and Tartous were also revitalized by the award of contracts to manage their container terminals to foreign investors in partnership with local investors linked to the Assad family.
The foreign investors - CMA CGM in Latakia, and the Philippines' International Container Terminal Services in Tartous - upgraded the facilities and helped to nearly double the ports' container traffic last year to 620,000 TEU from around 365,000 TEU in 2004.
Nearly 40 per cent of Latakia's total incoming cargo volume has been Iraq-bound, shippers and Syrian transportation officials say, while for Tartous the figure has been as high as 70 per cent.
Syrian ports' flexibility and lower costs gave them a competitive advantage in Iraq-related business against Turkish and Lebanese ports and Jordan's Aqaba. Lower land transport costs were also a plus, along with the ability to bypass Suez Canal fees paid by importers using Jordanian and Saudi ports on the Red Sea.
Now, Iraqi, Jordanian and Saudi Arabian importers, who have used Syrian ports in recent years for bulk cargoes of wood, marble, steel and grains from the Black Sea area and North and Central Europe, are looking for alternatives.
"We are getting increasing inquiries from local and Iraqi traders who want to bring their goods to Jordan by sea from Turkey or other markets. This business traditionally would go to Syrian ports. Even goods that would normally go by land via Syria are now being shipped," said Captain Wahid Abu Ajamieh, general manager of CMA CGM Jordan.
"This is an indication that something odd is happening."