Introducing a levy for cruise ships could "harm the reputation of Scotland as a tourist destination", Scottish ministers have been warned.
Bosses at the Port of Cromarty Firth in Invergordon raised concerns as the Scottish Government consults on whether it should give local councils the power to introduce such a charge.
The port attracted more than 100 cruise ships last year, carrying more than 213,000 passengers.
Adding that these visitors spend an estimated £19 million locally, port bosses are concerned a cruise ship levy could have a "net negative impact on the Highland economy".
This is because the amount of cash raised through the introduction of a cruise levy would be considerably outweighed by a much bigger drop in regional income as a result of an inevitable slump in ship and passenger numbers due to the new tax being applied.
The claim came in the port's response to the Government consultation.
MSPs have passed legislation which allows councils to bring in a visitor levy on overnight stays in places such as hotels, bed and breakfasts and holiday lets - with a number of authorities now looking at introducing such charges.
However with the visitor levy not applying to passengers on cruise ships, the Government is consulting on whether a separate charge should be introduced.
Port of Cromarty Firth said it has calculated that if a levy of £5 per passenger was introduced, port costs for ships visiting it would be increased by almost a quarter (23%).
In these circumstances it said a 10% reduction in cruise ships to the port would be the best case scenario it would expect.
The port added that while Highland Council could stand to collect £863,000 if such a charge was introduced, businesses and communities in the area could lose out on £2.4 million of spending by cruise passengers.
Alex Campbell, chief executive of Port of Cromarty Firth, said: "Our figures show that the cruise levy would not benefit the Highlands, but rather the introduction of this additional tax would adversely affect businesses that rely on income from tourism, and damage our communities who already find skilled labour hard to come by.
"The impact would disproportionately fall on smaller businesses and seasonal workers, such as shop owners, tour guides and taxi drivers.
"The cruise industry makes a much-needed multimillion-pound contribution to the Highland economy every year and provides a vital source of income to a wide range of businesses.
"In turn, through the wages of workers and employees and the profits generated by the supply chain that benefits from cruise, it raises tax revenues for Scottish and UK governments.
"The Port of Cromarty Firth does not understand the economic rationale for bringing in a local cruise levy. We believe that, far from benefiting our nation, it will in fact harm the reputation of Scotland as a tourist destination.
"Further, as an additional tax that is difficult to administer and collect, it will only damage relations with cruise operators."
The consolation runs until May 30, with Finance Secretary Shona Robison having already said it will "help to inform the Scottish Government's decision over whether or not to bring forward legislation".
Speaking at the start of the consultation earlier this year, Ms Robison said ministers had held a series of events to "hear the views of the cruise ship industry, local government, and others".