Thursday 5 September 2019

Loch Ness eDNA results released

The results are out and you can view the press conference here and the eDNA results are officially published here.

Having now watched the whole feed, the gist of it to me was that they did not find any unusual DNA, certainly no reptilian DNA. He did say all the expected fish DNA were found including lots of eel DNA, in fact a surprising amount of such data, which led him to suggest that Loch Ness could harbour a giant eel.

This was not concluded from the eel DNA as the experiment (he said) could not distinguish between large and small eels. Also, no seal or otter DNA was found. Again, I do not find that surprising as the seal is an itinerant visitor to the loch and otters may have specific locations not visited by the samplers. Adherents of the itinerant Nessie theory will not be surprised by this. Neil Gemmell did say that about 20% of the DNA they found could not be identified, though the main issue there may be that such fragments were not amenable to analysis. To that end, he related the story of how 40% of DNA samples taken from an American subway station (?) were not identifiable. Is there a loophole there for some believers as any sequence not matching the species database would be set aside?

You may wonder about any catfish or sturgeon DNA results. No such DNA was found, but again for sturgeon, the itinerant theory can be invoked. For catfish, the only hope for such adherents is that the population is so small, perhaps even one individual, that it was missed in the sampling (a limitation of the sampling that Neil readily admitted to).

Personally, my own view from some years back that we have an exotic fish of some sort remains viable. Neil Gemmell implied that the degree of accuracy of the analysis was not species level but some level above. I would like to know more about that. The related giant eel theory has received a boost, though that theory needs further work to explain features not usually associated with eels (e.g. raised humps).

My second favoured theory of itinerant/trapped visitors was never going to be touched in this regard and Loch Ness will continue to receive visitors of all sorts, usual and unusual now and from centuries past.The fact that the experiment failed to identify any visitor species was a bit of a surprise and made me wonder if migratory salmon or trout were missed.

May I also say I was particularly interested in one DNA find and that was "a bacteria most commonly associated with salty waters in the freshwater loch". How did such a specimen get there? Once again, that reopens the discussion as to whether there is a subterranean path to the sea from the loch. Also of interest to me was whether these results can help towards estimating the total biomass of the loch or relative abundances of species - a item of data important in predator foodstocks.

In the end, the professor was not suggesting this disproves the Loch Ness Monster and the "legend" will continue and people will continue to report strange things. Indeed, there was perhaps a bit of the old spin in the conference because not only are scientists and cryptozoologists interested in these results, but local and national tourism interests. The experiment did not prove giant eels but it also did not disprove them. I am sure VisitScotland will be happy with that!

The Otago team will put a searchable species database online soon and there will a documentary on the UK Discovery Channel on the 15th September while Neil Gemmell hopes to publish a peer reviewed article for a scientific journal by the end of the year. The BBC has published a summary with reactions at this link.

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Monday 2 September 2019

Large eel like object in River Ness?

Something large seems to have passed by one of the underwater cameras that the Ness Fishery Board employs to monitor salmon runs. It has all the appearance of a large eel. It's a bit indistinct due to our helpful peaty water but it looks alive and big. Not quite a 30 footer but easily outsizes the salmon in the foreground which gives the impression of backing off from this object before moving back in.

Assuming this was taken at the weekend when we had a lot of rain and rivers were in high spate, something seems to have taken advantage of this high water level. I assume from the motion of particles in the water and the salmon that the flow is from left to right indicating Loch Ness is to the left and the Moray Firth to the right. In other words, this object is heading from the loch towards the sea.

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