Hauliers are running at half their normal capacity due to the cancellation of sailings by P&O.
The Road Haulage Association has told UTV there is enough freight in Scotland to fill two boats to Northern Ireland.
John Martin said: "They are 50% behind, in other words there is enough sitting in Cairnryan to fill two ships, the sandwiches, the fresh vegetables, the fresh fruits."
"If a load is delayed for a day, the delivery that is supposed to come tomorrow arrives at the same time. "You have nothing on the shelf today and then too much tomorrow."
Meanwhile Agriculture Minister Edwin Poots has told his counterparts from England, Scotland and Wales that Northern Ireland’s agri-food industry is facing extreme challenges brought on by the Ukraine invasion and the suspension of P&O services.
Speaking after the meeting of the Inter-Ministerial Group for Environment, Food & Rural Affairs, Minister Poots said: “The shocking crisis in the Ukraine is having a knock-on impact in our part of the world as businesses struggle to deal with the escalating costs of grain, energy and fertiliser in particular."
Warning of the real and damaging impact on local industries, Minister Poots added: "We need to be as prepared as we can be for further disturbances to our supply chains as a result of a prolonged conflict in Ukraine."
“We must act quickly to ensure our capacity to produce food is maintained."
On the suspension of P&O ferry sailings, Minister Poots said Northern Ireland face a challenge "due to its geographical dependence on the supply of critical goods (food and medicines) carried on GB-NI ferries across the Irish Sea".
"An interruption to those crucial import and export supply lines has the potential to cause short term disruption to Northern Ireland businesses and ultimately to consumers.
“I have asked that food is prioritised on any sailings coming to Northern Ireland to ensure food continues to make it onto shelves."