Roll on roll off (RoRo) ferry traffic from Irish to British ports dropped by 22% last year as a result of the impact of Brexit.
The decrease was driven by reduced use of the UK landbridge, as well as the movement of freight onto routes between Northern Ireland and Britain.
At the same time, traffic between Ireland and continental Europe rose by 94%.
Direct EU traffic now represents one third of all RoRo volume, compared to 17% in recent years.
The number of weekly sailings between Ireland and mainland European ports more than doubled from 30 to over 60 at times during the year.
At the same time, load on load off (LoLo) traffic, the bulk of which moves on direct routes to mainland Europe, increased to record levels, growing by 11%.
The data is contained in the latest edition of the Irish Maritime Transport Economist, a report produced by the Irish Maritime Development Office (IMDO).
The organisation describes how last year was marked by the reorganisation of Irish supply chains following the end of the Brexit transition period.
It also saw a rebound in port traffic as Covid-19 restrictions were gradually eased.
"I commend all stakeholders who contributed to the Brexit response and would like to express my appreciation for their efforts in maintaining Ireland's connectivity to both GB and European markets," said Hildegarde Naughton, Minister of State for International and Road Transport and Logistics.
"Ireland's maritime industry was instrumental in maintaining a strong, connected economy throughout the monumental challenges of Brexit and COVID-19."
"I would like to acknowledge the efforts of the ports and shipping sectors and express my thanks for the invaluable services they provide."
The report notes that the carriage of construction materials rose significantly during the year as the industry here recovered.
While liquid bulk volumes also returned to pre-pandemic levels by the fourth quarter.
Passenger volumes also increased as international travel returned.
"Looking ahead, there are many reasons to be positive about the future of the Irish shipping industry," said Liam Lacey, Director of the IMDO.
"Demand is expected to rise further in 2022 as the effects of COVID-19 dissipate, and the period of greatest Brexit-related uncertainty passes."
"However, many new challenges lie ahead. The IMDO will continue to monitor these closely and report on the impacts for the Irish maritime industry."