The Port of Larne has been dealt a "worrying" body blow with the scrapping of a key passenger ferry route to Scotland.
P&O Ferries, which owns the Co Antrim harbour, is ending its Larne to Troon service because it was making a loss.
The ferry firm said: "The stark reality is that the company is continuing to make significant losses, and sadly the income from ticket sales is not sufficient to cover the annual vessel and port operating costs."
It already reduced the service during off-peak months last year. The more lucrative crossing for both freight and passengers between Larne and Cairnryan will continue to operate.
Roger Armson, general manager of Port of Larne, said the "traffic on the Larne-Troon route represented a single digit percentage of our overall annual revenue", which "has an overall minimal impact on freight".
He told how P&O had invested £15m in both Larne and Cairnryan in 2014 and added: "The Port of Larne continues to investigate new commercial opportunities for the port, and we are fully committed to developing this asset for the long-term benefit of Northern Ireland and our company.
"While it's a loss for Larne, the harbour also deals in a large level of haulage and freight flowing through the port each year."
According to the latest accounts for Larne Harbour Limited, the business remains profitable.
Pre-tax profits have remained reasonably strong, up slightly to £2.75m for the year.
A strategic report for the company said that "in light of prevailing economic conditions, both the results for the year and trading prospects are satisfactory".
It added: "Economic conditions, as Northern Ireland has lagged behind the UK recovery, have meant that there has been little growth (in its core ferry business)."
But it also indicated that the sole ferry operator, namely P&O, "expected to continue to operate services from the port".
The port itself employs around 30 staff, with wages making up around £1m of its costs.
The ending of the link is the "latest bad news" to hit the area, according to DUP Mid and East Antrim Mayor Billy Ashe.
But he said he was "heartened" by assurances from P&O that there would be no jobs lost as a result of the news.
The flow of traffic from the port supports a business park, which features an Asda store, cinema and eateries.
Stena Line once operated from Larne but ended its last remaining link to Fleetwood back in 2010.