A report from Scottish Natural Heritage says the number of Moray Firth dolphins is at a critical level.

BBC Scotland's Katie McDonald reports on the dolphins' plight

A computer profile predicts that the population is dropping at a rate of 5% to 6% per annum and now stands at 129.

At that rate the colony, already internationally classed as endangered because it numbers fewer than 250, would die off in 40 or 50 years.

It is estimated they bring in £750,000 in spin-off tourism revenue per year and directly employ about 15 people in the eight boats that go out dolphin watching.

A number of factors could be to blame - disturbance, pollution, the availability of fish such as salmon and even changes in water temperature.

The dophins are a tourist attraction

Scottish Natural Heritage Highland area manager George Hogg said: "Because there are assumptions in this study one could argue about the precise rate of decline, but it is clear there is a decline.

"Quite simply this study tells us the dolphins are not going to be there in a number of years time.

"But there is no finger pointing going on. There is no single reason attributed to the decline, it is more likely to be a cocktail of factors both natural and human."

"It also tells us that there may be opportunities to do something about that. It may be possible to halt or even reverse the decline, and that is what we must aim for.

"Awareness is half the battle so that people can take account of the dolphin's vulnerable status. Better informed management decisions will we hope lead to the current pressures being reduced."

Aberdeen and St Andrews universities carried out the study for SNH over the past 10 years and revealed the mammals were very vulnerable and in need of assistance.

Protected area

The national and international importance of the colony has led to the Moray Firth being selected as a candidate for Special Area of Conservation under the EC Habitats Directive. The UK's other colony is in Cardigan Bay.

Computer modelling allowed predictions to be made about the future viability of the dolphins and it is hoped the findings will enable action to be taken before it is too late.

Dr Paul Thompson: "Population vulnerable"

Dr Paul Thompson, of Aberdeen University, said: "We knew that the Moray Firth dolphin population was small and vulnerable, but conventional monitoring hasn't yet been able to determine whether or not the population is changing.

"The key finding from this study is that our modelling work predicts that the population is declining. It has been thought that if you keep conditions the same things will be all right.

"But the signs are we must start identifying areas where we can alleviate any threats.

"Computer models such as this inevitably involve a number of assumptions, which we now need to test in more detail.

Raised awareness

Now the new information will be sent out to those around the shores who make management decisions so the dolphins' vulnerable status can be taken into account.

The report states that the chances of long-term survival could be greatly increased by measures which prevent even one extra death every five years of an adult female.