Stopping the introduction of pike into Scottish lochs for fishing could help ensure the future of one of Scotland's rarest and most beautiful birds, according to research by RSPB Scotland.

However, an angling organisation has cast doubt on the findings.

The Slavonian grebe only began breeding in the UK in 1908 and its population today remains largely restricted to northern Scotland, where latest counts have shown only 29 breeding pairs remain.

Around half of the UK population of Slavonian grebes breed at Loch Ruthven, 16 miles south-west of Inverness, where the RSPB has a nature reserve.

The study, led by RSPB and part-funded by Scottish Natural Heritage, looked at which factors influence the grebes to choose certain lochs to raise their young.

It found the species likes moderately-sized lochs with an abundance of small fish such as sticklebacks and minnows to feed on, clear water and plenty of nesting habitat.

It also said lochs containing pike had fewer small fish, which are a valuable food source for grebes.

Conservationists hope a better understanding of the species, particularly during the breeding season, could help determine which measures are needed to reverse the population decline.

But George Holdsworth, Scottish policy officer for the Salmon & Trout Association, expressed surprise the report found lochs containing pike had fewer small fish. He said: "Most other research does not support these findings."

He said the common minnow was not native to Scotland, and introducing it to new waters should not be allowed.