Scientific results are expected on Tuesday into the mysterious deaths of thousands of rainbow trout at one of Scotlands top fisheries.

Government biologists are studying the dead fish and water samples from the Lake of Menteith which has been closed as result of the incident which took place last week.

The lake, in the heart of the Trossachs, has been closed as a “precaution” until May 4 causing major headaches for organisers of competitive angling in Scotland.

In six weeks’ time Scotland is scheduled to host the World Fly Fishing Championships for the first time and the 700-acre lake in Stirlingshire is to be one of five central Scotland venues.

The event is the blue riband of angling with hundreds of competitors from 27 countries taking part.  It opens on June 5.  Organiser Dr Neil McCarry said today:

“We are waiting to see the results and hopefully it will be a temporary situation. We have exactly 40 days until the championships start, so all the arrangements are already in place.

“There are several alternative options. Scotland has so many choices, we will not be short of other venues, but that may not be necessary.”

More immediately, the fishery – Scotland’s only “lake” – was due to be the venue for heats for the Scottish national fly-fishing team on Tuesday.  Around 60 anglers were due to take part.

Tom MacTaggert, competitions secretary of the Scottish National Anglers’ Association (SANA) said today: “We are working right now to make alternative arrangments and expect this to be completed later today.

“It is disappointing, but the Tuesday heats, and another on Thursday will go ahead elsewhere.”

It is unusual for a fish stock to be wiped out so rapidly due to natural causes.  But MacTaggart said there had been “one or two” similar instances at English fisheries in the last 20 years.

The problem had related to a sharp drop in oxygen levels due and had been resolved by aeriation programmes.

Biologists from the University of Stirling’s department of aquaculture and the government’s Fisheries Research Services in Aberdeen were called in after dead and dying fish were found at the lake last Thursday.

One theory suggests that a rapid spread of algae has led to a severe depletion of oxygen levels, asphyxiating the fish.  The lake also holds a population of specimen pike and perch.  It is not known if all aquatic life has been affected.