By high and low roads, Scots desert the islands

Scotland needs to attract 50,000 young immigrants a year to stave off a population crisis that could drain rural island communities of life, according to a leading economics professor.

The country has the highest rate of population decline in Europe and by 2009 the number of people living there is expected to fall below five million.

In the Western Isles numbers have dropped by 0.4 per cent and in Shetland by 0.3 per cent. At the last count, in 2001, the number of people living on Scotland's 95 inhabited islands, whose populations range from one to almost 20,000, had fallen below 100,000.

Between 1991 and 2001, 64 islands experienced a fall in population and the average age of the residents rose. "The number of people of pensionable age is going up while the number of people of working age is going down and, in a pay-as-you-go welfare state like we have, it is creating an increasing imbalance," said Professor Robert Wright of Stirling University.

"The problem is that services provided outside the central belt, where most of the country's population lives, are much more expensive to provide on a cost-per-head basis, which means they could be among the first to face cuts."

Professor Wright said many communities were now facing a situation similar to that experienced by the last 36 residents of St Kilda, who asked to be evacuated in 1930. "If people living in these small communities want to take advantage of the same kind of services provided on the mainland their local economy has to be big enough to pay for them or they will have to move somewhere else," said the professor. According to statistical analysis carried out by Eurostat, the European Commission's statistical agency, there is a critical population mass which determines the viability of population growth on islands. According to Eurostat's research, any island with a population of less 4,000 is likely to experience net emigration, an ageing population and inadequate provision of facilities.

In 2001, only six Scottish islands could boast populations greater than this critical mass - Arran, Bute, Skye, mainland Orkney, mainland Shetland and Lewis and Harris.

"The responsibility for immigration must be devolved from Westminster," said Professor Wright.

"My research suggests we need about 50,000 migrants a year - that's about 1 per cent of the population - if we are to have any deceleration effect on the ageing population."

Alistair MacDougall, Argyll & Bute councillor for Mull and Iona, said he shared Professor Wright's fears. "I could see Iona facing a St Kilda-style evacuation in the next 20 or 30 years as they have hardly got any houses left which are not holiday homes," he said. "We already have to fight to retain essential health services such as an old folk's home."