| Fly Fishing Devon | "The Heuristic Trout" | Wild brown trout in Dartmoor rivers are special

Words of wisdom and experience ...

The actor Sir Michael Hordern learnt to fly fish when his parents moved to Dartmoor in 1925:  "By day I got to know the wilder moorland streams, the East Dart, Swincombe, West Dart, Cherrybrook. Wallabrook.... I developed a love of the moor that has never left me."

But in his later years he was critical of changing attitudes: "Actually catching the fish used to be of secondary interest, what really mattered being the expertise required in presenting exactly the right fly to the fish. These days an enormous amount of people have taken up fishing as a sport and all they seem to want to do is catch the biggest fish possible."

Sir Michael was under no illusions about the size of Dartmoor trout: "Dartmoor fish may be small but my God they're the best that swim."

This video was inspired by an article in The Independent newspaper by Andrew Brown who summed up the attraction of fishing on Dartmoor:

"To gain a sense of remoteness from the quotidian world, and closeness to primal monsters, is one of the main reasons for fishing. This is quite unrelated to the size of the quarry. It is a function of their wildness. Wild brown trout are now almost impossible to find in the south-east of England, and are little valued where they are found, compared to fat stocked fish. Dartmoor offers the last remaining accessible and affordable fishing for them in southern England."

Some questions ...

The majority of wild brown trout caught on Dartmoor and in South Devon are less than eight inches long, but each season anglers catch larger 12 or 13 inch fish.

As guides and instructors we are often asked:
  1. Are big fish more difficult to catch than smaller fish?
  2. Are big fish 'smarter' than smaller fish?
As guides and instructors we often ask ourselves:
  1. Do skilled anglers catch more fish?
  2. Do skilled anglers catch bigger fish?

This page discusses the size of trout in Dartmoor rivers, and the expertise required for their capture. I hope it will help you appreciate our fish - of whatever size. It's our job to show you the necessary skills to catch them and explain why we treat them all with great care.

The next two histograms show
  • the number of trout in a range from 1 to 17 inches collected in an  electrofishing survey  conducted in 1962 on the Devonshire Avon.
  • the same data with the approximate age highlighted at each length (based on data in Frost and Brown 1967)
  • The size of trout in a South Devon river

    The age & size of trout in a South Devon river

    Size of trout caught by anglers

    This graph shows the numbers of trout of various sizes caught by anglers on a West Country river:
    1. most of the trout were less than 8 inches long
    2. relatively few trout of 10 inches or longer were caught
    3. hardly any fish of 13 inches or longer were taken
    Two questions spring to mind:
    1. Why were so few big fish caught?
    2. Are bigger fish 'older and wiser' and therefore less likely to be caught by anglers?

    Age of trout caught by anglers

    The larger fish are certainly older.
    This graph shows the growth rate of wild brown trout in our area.

    1. fish of 12 to 14 inches take six years to reach that length
    2. our trout are about three years old before they spawn for the first time
    1. consequently small fish should be carefully returned to the water so that they have an opportunty to reproduce
    2. it also helps to use barbless hooks

    But, are older fish 'wiser?

    Trout mortality

    The older fish are certainly 'survivors'.
    This graph shows that out of 1000 eggs laid by a female trout only two will survive to their  fourth birthday.

    1. mortality is especially high in the period between hatching from the egg to establishing a territory
    2. only 20 fish reach their first birthday
    • so, the next time you hear someone complain about the small size of the fish they are catching, remind them that an eight inch fish is probabaly three years old and is one of a group of maybe only six fish that remain from a clutch of 1000 eggs!

    But are larger surviving fish necessarily 'smarter' and more difficult to catch than smaller younger fish?

    They are better at avoiding predators. They may be more easily 'scared' by unfamiliar shadows, sights and vibrations than non-survivors. But we need to remember that fish have evolved to deal with their natural enemies, not necessarily angler's flies. Provided you can present an appropriate fly at an appropriate time and place and most importantly - do it in such a way that you do not scare the fish - there is no reason why you should not be successful.

    But how do you catch the bigger fish? There is a well known saying that "10% of the anglers catch 90% of the fish". The graphs suggest that there are simply fewer bigger fish and therefore the more fish you can actually catch then the greater the chance that one of them will be big.

    If you do catch a big one, treat it with the respect it deserves. After all it's one of nature's great survivors.

    But don't worry if you don't catch a big fish, it really is just a matter of proportions!

    As guides and instructors we often ask ourselves:
    1. Do skilled anglers catch more fish?
    2. Do skilled anglers catch bigger fish?

    In early June 2014 Dartmoor was the venue for the Commonwealth Fly Fishing Competition(CFFC). Seventy five experienced anglers representing nine countries each fished the East or West Dartfor three hours.

    The next two images show my analysis of each angler's catch based on results posted on the CFFC website (currently unavailable 08-02-2021).

    Total catch by each angler

    This diagram shows that even experienced anglers find Dartmoor challenging

    Nearly a third (32%) of competitors failed to catch any fish over 6 inches long.

    (Note: I assume that only fish over 150 mm (about 6 inches) were counted

    A group of anglers were catching at a rate of at least one fish every 10 to 15 minutes

    Largest fish caught by each angler

    These results illustrate Sir Michael's point that Dartmoor rivers are home to relatively small fish

    1. But bigger fish are present
    2. Two 13 inch fish were caught 
    3. And a further 18 fish over 10 inches were taken across the three days of competition

    Some final thoughts ...

    The American author John Gierach has a refreshing approach to the increasing tendency to equate fishing quality with the size of the fish caught 

    For example he writes " Let me introduce an idea, just something to kick around. Maybe your stature as a fly fisherman isn't determined by how big a trout you catch, but by how small a trout you can catch without being disappointed. And of course without loosing the faith that there's a bigger trout in there"

    And - as this video shows - there are bigger trout in Dartmoor rivers: sea trout


    1. Frost and Brown, "The Trout", published by Collins, London 1967
    2. Watson, "The Trout: A Fisherman's Natural History", published by Swan Hill Press, Shrewsbury, 1993
    3. Michael Hordern, "A World Elsewhere", Michael O'Mara Books Ltd, 1994.
    4. Commonwealth Fly Fishing Competition website retrieved on 18/06/14 http://www.cwffe.co.uk/
    5. John Gierach, Fly Fishing Small Streams
    6. Andrew Brown, The Independent newspaper article "Country: Dartmoor/ Wild trout in a perfect, miniature world". URL retrieved 18/6/14:  http://www.independent.co.uk/news/uk/country-dartmoor-wild-trout-in-a-perfect-miniature-world-1337096.html
    7. Sir Michael Hordern entry in Wikipedia Available online

    About the author

    Paul guiding ITV News reporter in June 2019

    with sea trout in camera range ...

    Paul Kenyon lives in Ivybridge on the southern edge of Dartmoor about 6 miles from the Upper Yealm Fishery.

    Paul devotes more time than is reasonable to his love of all things associated with fish, fishing, instruction and guiding on Dartmoor rivers.

    He retired in 2006 from the Department of Psychology, University of Plymouth where he lectured in behavioural neuroscience and evolutionary psychology.

    email paul@flyfishingdevon.co.uk


    In this video Bob Wyatt ties his Snowy Shoe Hare Emerger

    Bob uses this material in place of CDC because he has found that CDC tends to be "a one fish fly" which is an absolute no-no for guides on local rivers.

    This article would not have been possible without the help and encouragement of Bob Wyatt. Bob is an artist, author, Certified Fly Casting Instructor and long-time angler. Born in Canada, he fished the freestone streams of southwestern Alberta in the late 1950s. He now lives on New Zealand's South Island. His articles have appeared in Fly Fishing & Fly Tying(UK), Gray's Sporting Journal, Fly Rod & Reel, and Flylife Magazine (AU). He has published two books: Trout Hunting: The Pursuit of Happiness (2004) and What Trout Want: The Educated Trout and Other Myths (2013). In this interview by April Vokey he discusses his “prey image” theory, trout fishing and the early days of steelhead fly fishing.