Visitor numbers to the north-west over the past five months are down by an average of 15 to 20 per cent from the same period last year. Business has declined by more than 30 per cent in some sectors.
The regional tourism authority expects this trend to continue throughout the rest of the summer because of bookings lost in March and April as a result of the foot-and-mouth outbreak.
The manager of North West Tourism, Mr Paul McLoone, said he did not expect bookings from overseas visitors to start reaching last year's levels again until the autumn.
Overseas visitor numbers are down by up to 20 per cent and Mr McLoone said checks with airports and tour operators had confirmed that they would remain at this level for the rest of the summer. Since May, bookings had started to increase again.
To fill the beds left vacant by foreign tourists, efforts are now being concentrated on attracting visitors from Northern Ireland and the eastern region. The good weather during May had attracted increased numbers from the North.
Mr McLoone said he was doing interviews with media in the eastern region to try to dispel the myth that the north-west was further away than Kerry. The journey from Dublin to south Donegal took just three hours, he said.
Sectors specifically linked to the countryside and outdoor activities, such as angling and hill-walking, have been worst affected. Country houses and farmhouse accommodation providers have seen their business drop by between 30 and 40 per cent.
Mr McLoone said it had been "extremely difficult" for people in specialist interest areas. While he was not aware of anyone going out of business, people with large borrowings who now had to base repayments on a three-month rather than a six-month season were having a very difficult time.
The efforts to attract more domestic tourists over coming months were aimed at helping them, he said.