Scott wrote: ↑Tue May 05, 2020 9:51 am Great thread Hovis. I know little of the science behind these fascinating creatures, only the basics.
Story time.
I once spent a few days up at Blea Tarn trout fishing. When I finally came down the fells I went for a pint at the Langstrath Inn. There was an old timer sat at the bar, reckoned he’d never left Cumbria and only been out of the valley a handful of times. (Bizarrely enough, there was photograph of him in a frame on the wall of the bar behind his head as I spoke to him). Anyway, I told him that I’d been up to Blea Tarn,
“Oh aye, used to fill my basket up there, some good eating to be had out of that tarn, the trout fishing is good too if you know what you’re doing.”
“Oh, you weren’t eating the trout then?”
“Don’t care for trout, eels, big uns too.”
I’ve always meant to try for them up there, it’s rich in minnows. What always amazed me was the journey the eels had evidently made; Up the river Cocker, through Bassenthwaite Lake, up the river Derwent, through Derwent Water, up Lodore Falls, through Watendlath Tarn and finally up the fell becks to Blea Tarn.
Amazing, one day I’ll go eel fishing there, nothing like following a story told by a mysterious old man in a country pub.
That's particularly interesting Scott.
I've just consulted that handy tome from the Anglers Library - " The English Lake District Fisheries" By John Watson and edited by the delightfully named Sir Herbert Maxwell, Bart. and F.G.Aflalo published in 1899. If you haven't got a copy I'd suggest that you take a look, like stepping back in time.
We digress. I've checked out the section on Blea Tarn contained within and found 2 entries. For clarity Blea Water refers to the large (41 acres) that sits under High Street that famous Roman road (and excellent walk I must say). Blea tarn refers to the smaller water that is semi-private and is best seen from the south looking up the pass into the Langdale Pikes. Trout here are described as plentiful, never seen in good condition and "slinky" a possible reference to their impoverished state?
Eels aren't mentioned specifically within any of the high tarns but referenced throughout the book as been almost universally present including the high tarns. There is a fairly extensive section on the eel and it mentions of numerous commercial operations to capture them, one to the tune of £50 - a great deal of money back then. Rather interestingly I've found the eel here referred to as "the sharp nosed eel" Anguilla vulgaris as the most numerous species then "the broad nosed eel" Anguilla latirostris as being present within several tarns and present in the Kent estuary in large numbers, its also noted that it fails to attain the size of Anguilla vulgaris. There is also a sub-note that questions if A.latirostris is indeed a distinctive species. Indeed the note was correct and the European eel Anguilla anguilla as we know it now has "replaced" both A.vulgaris and A.latirostris as the species we are referring to here. One possible explanation for this initial confusion, and here one must remember that it was popular at the time for gentlemen to pursue "the sciences" giving rise to many interesting theories, is the eels amazing ability to change its physiological characteristics dependant on it food sources. Those eels feeding mainly on benthic invertebrates tend to keep a smaller gape size and smaller head. Where eels tend to grow large (in my experience) is where they switch to a much more varied diet focused on small fish, although their ability to hunt and catch such fish is questionable. These eels are much broader and have a wide gape enabling them to consume large prey the difference is stark and very obvious when you see them side by side. Interestingly I don't know what the triggers are for these changes and I've caught both "type" from the same water.
Back to your high altitude eels. I've no doubt they are present in the tarns and that this is entirely natural. How many make it there is debatable, few would be my guess given the struggle involved. After walking the outfall to red tarn its difficult to comprehend just how they get up! One thought that did occur is the eDNA, that is environmental DNA, is a relatively new technique where you can take a water sample and extract and trace the DNA contained within. This should provide a reliable means in the future of assessing species presence if traditional sampling is difficult. It's not yet proved and there are many questions about its accuracy, for example if a pike angler used a mackerel as bait can it be detected? I think it might have been used in the Lakes already to detect the presence of Ruffe in Windermere?
Interesting stuff! When we are out of this I'll come up your way for an eel trip, maybe try for a char too?