A countryside charity has called on the Scottish government to support the grouse shooting industry to "secure" its contribution to the economy.
The Game and Wildlife Conservation Trust (GWCT) said the sport was worth millions of pounds in Scotland and supported more than 1,000 jobs.
But the trust said grouse numbers were threatened by predation and disease.
A report commissioned by the GWCT said the number of grouse shot in 2009 was less than half the figure from 2001.
Economists at Strathclyde University, who carried out the study, said the sport generated at least £23m a year and supported the equivalent of 1,072 full-time jobs in Scotland.
It also found that the Scottish red grouse population - estimated at about one million - had not been hit by the severe winter as badly as first thought.
The GWCT's Dr Adam Smith said: "This report clearly shows that Scotland is benefiting to the tune of millions of pounds from economically active moors, where grouse shooting is the main aim.
"It is therefore a grave concern that grouse numbers appear to remain under pressure from predation, disease and future afforestation when shooting has such socio-economic benefits."
The trust said the main costs for sporting estates were managing the habitat and controlling the number of predators.
With the numbers of grouse being shot falling, the cost of shooting has become more expensive.
The trust said it was concerned that without help from the government, the industry would not remain economically viable.
Dr Smith added: "The GWCT is working with the Scottish Gamekeepers Association and other bodies to ensure that policies and tools are developed by government and agencies that ensure grouse shooting can continue."
Report author Stewart Dunlop said the report "strongly suggested" that policymakers should engage with the grouse industry to secure its contribution to the economy in remote rural areas.
The results of the study have been released the day before the Glorious Twelfth, when Scotland's grouse shooting season begins.
The trust said there was a "healthy" number of grouse, despite fears the unusually long and cold winter could have killed many of the birds.
Property consultants CKD Galbraith's sporting lets department said demand for grouse shooting this year was generally buoyant despite the effects of the recession.
Robert Rattray, partner and head of the firm's sporting department, said: "The general opinion is that despite one of the hardest winters in recent decades, some parts of Scotland are going to have better grouse numbers this year."