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Lake of Menteith Fishery Calls in Top Fish Veterinarian.
Lake of Menteith Fishery, which suffered a major unaccountable mortality to its fishery stocks has called in one of the world’s most distinguished Veterinarians to review the situation.
Professor Ronald J Roberts FRCVS, FRCPath, FRSE. is President of the World Aquatic Veterinary Medicine Association and also the chairman of fish health and welfare at the European Food Safety Authority (EFSA), the EU’s Food Safety Risk Assessment organisation, based in Parma, Italy. Professor Roberts, is an Emeritus Professor of the University of Stirling and is Hagerman Distinguished Professor at the University of Idaho, USA. In the 1980’s Professor Roberts led a four year UN Mission investigating fish kills across South East Asia, and also has extensive experience in investigating similar problems in Canada, Indonesia, Sweden and South America.
Professor Roberts visited the Lake of Menteith Fishery today, (Thursday 7th May). He reviewed all of the reports and results from the various agencies which have been involved in the problem and also collected material from fish for his own tests, (which including cooking and eating a sample of fish from the affected area).
In his report Professor Roberts stated. ………………………….
“……….It is clear from my review of all of the data, that there has been a serious “fish kill” event at the Lake of Menteith leading to a high mortality level among both trout and coarse fish of the loch, which I would place at Grade 3 on a five point scale.
The meteorological history of the previous few weeks coupled with the nature of the Lake, which is somewhat eutrophic compared to traditional Scottish lochs and is generally shallow but with one particularly deep area, suggests that there has been a significant toxic event related to water quality. There is no evidence from the pathology of the fishes that there has been any infection. The fish were, overall, in excellent condition.
In my experience such events may be of completely natural origin, occurring very irregularly and with long periods of time between them. From the nature of the lesions in the gills of the fish, the observations of Mr Glen and his colleagues, who have very detailed information on the sequence of events, and from the water quality and other data provided by SEPA and the results of Professor Geoff Codd of Dundee University, who has an international reputation in the field of toxic algae, I believe that it is probable that toxic algae played little if any role in the event, and the most likely cause would be an upwelling of toxic anaerobic organic matter, gases and associated bacterial toxins from the very cold benthic areas of the deepest part of the lake, which is adjacent to where the first and most serious mortalities occurred. Given Mr Glen’s recognition of the presence of necrotic odours around the area at the time of the loss, and his observations on the various water quality parameters, as well as the nature of the gill and liver lesions, it seems most likely that hydrogen sulphide, which is known to cause similar pathologies, was a significant factor. It is unlikely however to be the only factor as anerobic breakdown of organic matter releases a range of similar products. This will of course have been a very temporary situation and there is now no evidence of any such contaminants remaining. Such events are rare and I have not personally experienced them to recur.
In my experience, where such fish kills are not caused by infectious agents nor primarily associated with toxic blue-green algae, the effect is short lived and surviving fish recover well over three or four days, provided they are not stressed or challenged in relation to oxygen availability. Since fish have been taken from clean waters and placed in cages in the lake around where the losses took place and are surviving, behaving naturally and feeding well, and there has been a significant period of heavy rain and high wind in the area now for the last ten days, I am confident that all of the factors leading to the unfortunate event will now be dissipated.
In making such predictions I have always believed that one has to have the courage of ones convictions and so have today, 15 days after the start of the fish kill, collected live fish from the main affected area of the Lake of Menteith, cooked them and eaten them. There was no muddy taste or algal taint, and the fish has caused me no negative effect. I am therefore happy to recommend that the fishery is now likely to be safe to open and that there should be no problem with successful anglers consuming their catch.
Professor Ronald J Roberts Ph D, FRCVS, FRCPath, FIBiol, FRSE. Emeritus Professor, University of Stirling, Hagerman Distinguished Professor, University of Idaho.”
End of Report
Needless to say Douglas and I shared the Professors trout - they tasted great. It is time to enjoy living in the area again; pay the bills, cut the grass and put the fish in again - after my brief return to fish research.
We will be consulting over the next few days with various water quality experts in relation to safeguarding the Lake for the future - as an area for angling recreation.
There are some very important thanks to be made on behalf of the Lake of Menteith Fisheries and others in the community:
Prof Ron Roberts for his review of data and diagnosis. SEPA (too many to name so I'll include only a few - Brian Roxburgh, Robin Guthrie, Nicky Broad, Ian Lorimer, Alastair Duguid, Simon Spinks) for their massive effort, knowledge, scientific expertise and conclusions - as well as their continual involvement in research and monitoring with regard to safeguarding the future of the Lake. The Inverness Fish Vets for their contribution with the diagnosis (Pete Southgate) and histology (Dave Cox). FRS for their sampling of algae and histology and opinions. Prof Hugh Fergusson of the Institute of Aquaculture Stirling for his histology. A particularly knowledgeable star of an angler (you know who you are), as well as the support and assistance of a vast number of anglers - thanks for your patience. Marine Biologist Howard Dryden of Dryden Aquaculture, who knows a lot about water quality problems and solutions, I pestered him in the evenings - even although he was working in Germany. Prof. Geoff Codd of Dundee University for his world renowned expertise with algal toxins. Prof. John Lewis of School of Biological Science London for his comments and assurance re toxic production from bacteria. Colin Green the analytical chemist. Lawrence Carvalho of the Institute of Aquatic Ecology - Bush Estate. Sigrid Haande and Bjorn Olav Rosseland of NIVA - the Norwegian Institute Voor Water, for the information they gave concerning blue green algae and metals. The Department of Public Health. Environmental Health. Alistair Kean of IKM consultants. Rosie Glen for proof reading, support and advice. Sorry if I missed anyone.
Quint Glen Manager Lake of Menteith Fisheries ltd