The global fleet of dedicated refrigerated cargo ships is shrinking in size and shows no signs of reversing in the future.

But the number of containerships equipped to carry refrigerated containers has increased by six percent year-on-year and is set to grow 20 percent by 2018, according to the latest Reefer Shipping Market Annual Review & Forecast published by London-based Drewry Maritime Research.

As a result, with the number of capacity-restricted dedicated reefer ships shrinking, “there is no alternative but for cargo to be shipped by reefer-capable containerships” – a trend, the report found, that is accelerating as the volume of seaborne refrigerated cargo grew 4.9 percent in 2014, virtually all of which was carried by reefer-capable containerships.”

The trend “will leave utilization levels on the reefer containership fleet virtually unchanged over the next few years at 20.4 to 20.6 cargo tons per ‘000 cubic feet equivalent of reefer container capacity,” it said.

“The specialized reefer fleet has an average age of 25 years,” said report editor Kevin Harding. “With little likelihood of new buildings, in the large size range at least, ongoing recycling is inevitable, as is a shrinking fleet. However, the containership order book is substantial and is expected to remain so.”

An exception to the trend, is Belgium-headquartered Seatrade, which has said it will invest in a new building program of ships specifically designed to carry only refrigerated containers.

The carrier has firm orders for six vessels of between 500 and 700 FEU (40-foot Equivalent Units) of reefer capacity with options for a further six. Plans call for the new ships to be operated “in current and newly developed trades and form an integrated part of the ‘Fast, Direct & Dedicated,’ or FDD, concept developed by Seatrade in recent years.”

“Whether other specialized reefer operators follow suit remains to be seen,” said Harding.

Despite the changes for both modes of transport, cargo flows are forecast to continue to increase and therefore to weather any economic or climatic difficulties, at least on a global basis.

“Overall utilization levels are forecast to be relatively stable, although undoubtedly there will continue to be strong competition between the modes at a trade lane level,” he concluded.