The world's commercial fleet grew less and got older in 2014 than in any other 12-month period in over a decade, with the effects of mergers in liner shipping becoming more prominent, the UNCTAD Review of Maritime Transport 2015 unveils.

At the beginning of 2015, the fleet totalled 89,464 vessels, with overall 1.75bn in deadweight tonnage, a 3.5% percent increase from a year earlier, and the lowest annual growth rate in over a decade.

Data on fleet deployment illustrate the process of concentration in liner shipping, which has seen the recent mergers of Compañía Sudamericana de Vapores and Hapag-Lloyd, and Compañía Chilena de Navegación Interoceánica and Hamburg Süd. While the container-carrying capacity per provider for each country tripled between 2004 and 2015, the average number of companies that provide services to each country's ports decreased by 29 percent.

Both trends illustrate two sides of the same coin: as ships get bigger and companies aim at achieving economies of scale, there remain fewer companies in individual markets.