The Department for Transport (DfT) has released provisional data relating to the UK's port traffic in 2012.
According to the statistics, 501.2 million tonnes of freight was handled across the nation's docks last year - a four per cent downturn on 2011.
Dover was the busiest port in terms of unitised traffic, but the Kent-based import/export hub still reported an eight per cent year-on-year downturn in activity.
Grimsby & Immingham was the best performing port for tonnage, with 60.1 million tonnes of cargo being shipped into the Lincolnshire facility.
Worryingly, Northern Ireland was the only nation to report an upturn in trade, with freight weighing 23.5 million tonnes entering the country.
These provisional results could be updated between now and September, when a final set of figures will be published by the DfT.
The report highlights an alarming downturn in maritime activity, although industry experts believe upgrades to ports in Liverpool, Essex and Suffolk could help to attract more business to the UK in the near future.