Lake of Menteith
9th Sept 2014
11/9/14 STOP STOP PRESS
Just received news from Stirling Council's Consultant in Public Health Medicine via Stirling Council Environmental Health Team - in the light of the algae being classified as non toxic....
"so long as there are still no fish mortalities and no fish are exhibiting abnormal behaviour in the lake, then any fish caught in the parts of the lake that are not affected by the algal scum can be used for human consumption. The liver and gut from any such fish should still not be fed to pets."
They have taken further algae samples as a precaution. In the meantime we all know we need some wind (hopefully arriving on Sunday) to disrupt the algae. Catching for the table is again possible. QG
9/9/14 Catch and Release at Lake while Algae Investigated.
The big story as most regulars will be aware is the algal bloom at the Lake. It is generally considered to be the heaviest bloom for many a year and thicker than many have seen before at the Lake. It is caused by blue green algae and is not related to the problem which occurred 5 ½ years ago which was due to anaerobic breakdown of disturbed sediment. The cause of the scum has not been attributed to increased nutrient levels in the Lake. Phosphate and nitrate levels appear not to have changed – although further scrutiny of these parameters (with an eye for future weather patterns) will be a wise step. The obvious factor that is different this year is the input of heat and light – the other important factors affecting algal growth. The variability in weather within Scotland and the UK is significant. We had practically no frosts at Menteith last winter – certainly not a shard of ice formed on the Lake and it has been followed by one of the driest/warmest summers on record. The lack of winter frost resulted in high algal numbers at the beginning of the year and with the higher than usual amounts of heat and sunlight acting on this increased algal presence – a bloom has resulted. Lastly the danger times for algal bloom is the autumnal turnover of the water column when cooler nights (we were scraping the cars a few weeks ago) cause cooling of the surface waters which displace warmer more nutrient rich water near the sediments causing them to rise up and bring nutrients to the surface - aiding algal growth. This has been followed by two weeks of very light winds which allows the algae to move to the surface of the lake where maximum photosynthesis and growth is possible. These same light winds lead to a thick accumulation of algae on windward shores and at levels where ingestion may be harmful. The first casualties (if the algal contains toxins) tend to be dogs that go in the water then lick their coats clean. Lake management was anxious to avoid any potential problems and therefor informed the authorities of the potential hazard accumulating on areas with public access. There has been no fish mortality, not surprising, as blue greens in themselves are non-toxic to fish. When an algal bloom decays, fish problems can arise due to lack of oxygen.
Due to our notification, Scottish Government advice then swung into action with pre-agreed protocols. It should be noted that these protocols are in the scientific vanguard against the potential dangers of blue green algae. This is due to Scotland being the home of two world algal experts in Dundee/Edinburgh and Aberdeen. It is probably fair to say that their knowledge has led to stricter guidelines being in force in Scotland than in other parts of the UK. It is also a known fact that there are many other fisheries with blue-green algal blooms at present but it seems the Lake is the only one where Scottish government guidelines are being followed to the letter and actually exceeded (regarding the imposition of catch and release only). The interests of public health is paramount and hopefully the investigations at the Lake will allow for more confidence in the future – re public health and blue green algae in trout fisheries. Samples of algae (taken from the thickest accumulations) have been sent to Robert Gordon University for analysis. According to the Prof in charge, there is a 50% chance that the algae will not contain harmful compounds and we can start keeping fish again. We will hopefully get a result on this tomorrow. In the event of the algae being shown to contain toxins then the scum warning signs would remain in place and fish samples will be analysed. No toxins have ever been found in fish in Scotland and the experts expect that the trout flesh will be clear of problems.
Catches have been reported to be excellent. With several boats (Mike Middlemas and Colin Taylor from Crieff, Mr.McKendrick from Alva and Jim Twaddle from Cumbernauld) anglers reporting their best ever days on the Lake. The clear areas have been predominantly the western basin (Malling shore) and Gateside – ask staff on arrival. The Butts and Lochend have also fished well. With the light southwesterly on shore breeze arriving at midday, the eastern shore and hotel bay (i.e. the boats) tend to have the thickest accumulation of algae. Two days of strong wind would probably be sufficient to end the bloom – unfortunately this is not forecast. The big competitions this Autumn will go ahead using catch and release tactics if need be. QG