The Apparent Failure of Logic?

Rob's superb stream rainbow, but it raises questions about standard stream fishing logic.

Here I was, waxing lyrical about the way trout seem to learn from their mistakes, the effects of catch and release and a logical approach to what trout may “think” and then along  comes an incident that puts the entire process in the shredder. Or at least apparently so.

Small flies work better don’t they?

I have been firmly convinced for a long time that as catch and release fishing continues so the fish become more discerning and a good deal more tricky to fool.  One of the major tactics on dedicated Catch and Release  streams then is to “go smaller”. Tiny flies are frequently more effective on “educated trout”, simply in my view because most anglers avoid fishing micro flies much of the time. They are troublesome to tie (or obtain) and tricky to see on the water and the majority of fly fishers will then eschew the advantages in favour of patterns that they can more readily keep an eye on. So the theory goes that the fish start to realize that large tasty looking bugs, out of sync with the real insects present on the stream are likely to result in a stabbing pain in the nose and consequently “learn” to avoid them.

All well and good, perfectly logical in my book and one of the few things on which  a fly angler can pretty much “hang his hat”. Small is in general better, except when it isn’t..

The story:

Recently my very good mate Mike was fishing a local stream as the water levels dropped from late seasonal rain. With him his fishing buddy Rob, a man of some piscatorial aptitude but equally one who tends not to get bogged down with the minutiae of the sport, taking a rather generalist and pragmatic view of things. One of those happy go lucky rod wielders who are likely to throw caution to the wind and end up out fishing you if you aren’t darned careful.

So it was that with the water rather on the high side of fishable the two compatriots set about working their way upstream, on a particularly good, and often technically demanding stream. They fished a variety of methods, Czech Style nymphing, Mono nymphing, Dry fly and dropper rigs and all sorts as the water changed about them. The heavy stuff in the faster pockets and more generalist approaches to the slower sections, normally one might expect the fishing to be  a tad more easy in the higher water but at the same time presentation of the fly under such circumstances can be something of a struggle.

Apparently at some point, Rob, having battled to keep his dry fly afloat under the anchor like influences of his heavy nymph, tied onto the leader a fly of not inconsequential proportion. In fact Mike described the fly to me as an “overdressed, large (size 10), baby hedgehog pattern”.   A fly that no self respecting and well educated trout should so much as sniff at and indeed they didn’t. For most of the day not a fish even looked at this veritable monstrosity, they all came to the subsurface nymph and the dry fly (if a hedgehog pattern might be referred to as such), was simply there to serve the function of a strike indicator.

However fishing along the edges of a wide and rather rapid run, which generally holds fish under the bushes on the right hand bank Rob was casting away merrily into the slightly less rapid run on the left when the Jaws like maw of a large trout confidently broke the surface and inhaled the “Hedgehog”. Mike immediately realized the fish was well above average size for this particular stream and screamed advice to Rob not to go for the net too soon as he was sure the fish was going to “do a runner” at any moment. It turned out that with some careful manipulation of rod and line Rob successfully landed the fish after something of an extended battle. According to Mike later, the effort was aided by the fact that Rob was using unusually stout nylon, somewhere around 4 or 5 X and far too thick for fishing these streams under normal circumstances, (I seem to recall that in the telling Mike may have suggested the tippet would be better used to tie up a small boat, but that could be simply my imagination).  However, not withstanding that he was breaking all the rules, massive fly, thick leader etc, there was Rob standing in the stream with the trout of , if  not  a lifetime, at least the fish of the season.

One could easily write off the episode as simply good fortune, the fish starving after a long winter (although it was far from skinny), the water a tad coloured and running high, it at first glance puts a spanner in the works of all my thoughts on selectivity, presentation and the educated trout.

Or to misquote a popular if negative phraseology “It is a good theory, watch some B******* spoil it.”

To almost all regular fishers of these waters, catching such a fantastic fish with such gear is near to heresy so why should the trout show such aberrant disregard for what we all assume to be perfect logic?

This post sponsored by Inkwazi Fly Fishing Safaris

Perhaps trout only learn what we choose to “teach” them?

I think that it may just be that over the years the practice of catch and release combined with the ever continuing “arms race’ between angler and quarry has meant that for much of the time, more and more anglers are avoiding really large flies. So that where in the past fish have learned that consumption of large , even if apparently real, flies, is an unwarranted risk, now they would rarely see a massive fly on the water that wasn’t indeed real. It is possible that having taken advantage of the odd windfall of a large beetle, dragonfly or perhaps hopper over the years without any ill effect a fish such as the one described would feel confident in inhaling a relatively massive pattern.

I can’t profess to understand trout, but I do have an inherent belief that few things happen in the natural world that are not logical, even if we as observers cannot see that logic, and it strikes me that if this spectacular fish ate Rob’s imitation then there has to be a logical explanation as to why.

To me it may be an indication that larger flies may well start to make something of a comeback on our waters, at least until everyone starts to use them and then the fish will wise up again and the cycle will be repeated.

More food for thought I suppose, but perhaps these vagaries are what in the end makes fly fishing for trout such an entertaining pursuit. It sometimes appears to be as illogical as female shopping behavior, but I think that I may just be getting some understanding of the trout and the shopping thing is still a mystery. Perhaps that is at least some sort of progress?

Tags: , , , , , ,

2 Responses to “The Apparent Failure of Logic?”

  1. Paddy Coleman Says:


    Still wallowing in my start of year funk, I have re-read your blogs Tim. I’m surprised by how firmly you placed yourself in the Intelligent Trout camp 13th December 2009! I’ve decided I can’t stand by while my number 1 fishing guru stakes a shaky – to me – position for himself without at least attempting to lure him away from the dark side.

    First however, let me play my ultimate get out of jail free card.
    Whatever our debate on the subject, it really doesn’t matter if we think trout are smart or dumb. To catch them we still have to figure out what they’ll take in any given situation and make it work. It doesn’t really matter If I change my fly because I think Tommy the Intelligent Trout has seen that pattern in the past few months and is wary of it so long as I realise I’m not going to catch him if I don’t change my tactics! Which all means we can enjoy debating a terrific bar room topic, that involves neither politics nor religion, (well not a recognised religion at least) and still catch fish without having to change our minds!

    Furthermore let me acknowledge up front that your intuition is based on many years of very successful practice on myriad waters around the world, whereas I approach this topic without even 1% of your experience, and armed only with second hand ideas lifted from experienced fishermen and writers like yourself, a strong personal belief in rational analysis, and a love for a good old argument.

    So, back to Tommy the Intelligent Trout – or TIT for short: You’re right on the money when you mention some b*****d screwing up a good theory. That’s called peer review and is a practice of picking holes in incomplete theories until we get to the truth, a practice which coincidentally was pioneered by the Royal Society which is celebrating its 350th anniversary this year.

    The number one problem I have with TIT theory is that it while it’s obviously useful to explain why I don’t catch a trout while accommodating my fragile ego, it cannot accommodate a number of observed facts. Like the fact that trout have very small brains and very big eyes that require most of the trout’s miniscule brain power just to process visual signals. Or the fact that the same trout that are believed to recognise previously seen fly patterns, and associate those patterns with learned experiences, then do silly things like eating a fly with a hook sticking out, or scattering like crazy – and expending precious energy reserves – just because the sun glints off your watch. Or the fact that spooked trout will stop feeding completely – and pass up precious energy gains – instead of simply feeding more carefully for a while because strangers are in the area. And if trout can remember flies, why don’t they stop feeding completely as soon as they see a wrong ‘un, instead of letting us pass umpteen flies their way until we stumble on the right one?

    On the other hand I do think the idea of a hard-wired one-thing-only trout – or OTO – theory explains pretty much everything if applied rigorously. In this theory Otto the Trout is not intelligent in the human sense, but a highly evolved and specialised predator constantly living on the edge of starvation and coping with a dangerous environment. This creature reacts predictably to correct signals, like a well presented fly of the right size, shape and colour, and doesn’t react at all when the signals get scrambled. We fishermen fail to catch when we send the wrong signal or scramble them.

    When not breeding, Otto is entirely occupied with trying to get enough food without getting eaten. So he’s a bit like a simple computer program. “Am I safe? Is this food? Repeat.” We already know we can’t catch him if we spook him, but it’s our misunderstanding of the delicate security/supply balance that gives rise to TIT theory.

    Armed with a rudimentary brain, Otto only survives long enough to breed by keeping it simple. While he often bites bits of crap, and spits them out, once he bites something edible that doesn’t require too much work to gather, his simple selection system locks onto that food pattern until either it is no longer available or it is swamped by a better option. So during a hatch Otto will be locked onto emergers, until they are no longer the best option, and then (very rarely in my opinion) duns and finally spinners. And yes, that better option might be ants for half an hour. Otto doesn’t have a fridge you see.

    If Otto lives in a chalk stream with abundant size 20 morsels, there is no reason for him to deviate from that choice. So he won’t, and our delicious once only offer of a size 16 fly won’t be enough to tempt him. Natural selection has killed off all Otto’s inquisitive cousins who didn’t keep it simple! This isn’t intelligence; it’s survival of those fittest for a single purpose.

    So “selective” trout aren’t being smart; their food needs are instead being satisfied with a very narrow range of offerings.

    “Educated” trout aren’t educated. They might be spooky, locked onto a single food type, or both, but I’ll bet a week’s wages they can’t remember what they ate yesterday or even an hour ago. Their actions instead reflect the behaviour necessary to survive in their particular water. For me tough neighbourhoods, that become known as “technical” water, require spooky careful trout. Not flick knife tough but water without abundant food supplies. If food is scarce, they have to take more chances, so their spook systems are running at full throttle. Evolution has cleared out the sloppy ones, and while the guys remaining will usually consider any and all food items, they will clam up at the first micro hint of a problem. And if there is a sudden abundance of a certain food – like a big mayfly hatch that messed with my mind one day on the Holsloot – they are no longer spooky, just locked into that food only.

    In these conditions – which I think could describe the Cape streams – it begins to make sense that the flies that work one day might not work the next. Conditions for the trout only have to vary minutely for them to change food targets, or even appear to stop feeding. Truth is however they can’t stop feeding. They must instead be eating something we don’t understand. It also fits that one of the more successful trout in the stream, large enough to reduce predator risks while he waits between meals to ambush better offerings, and occupying a great location under a bank or bush, will slurp down Rob’s baby hedgehog fly. And whether the tippet was 8x or barbed wire would make no difference so long as at that instant in time it didn’t trigger any alarm in the ambusher.

    It’s not that you need 8x tippet to catch smart trout on the cape stream. You need to maximise your confidence and minimise the risk of poor presentation of your fly. The lightest possible tippet will always do that, but now and again, with the right conditions and a bit of luck you’ll get away with heavier stuff. And Tim I know you know 5x isn’t that heavy either!

    To me Tim this approach to trout behaviour makes more sense than pea-brains with PhDs. It’s easy to see why we love the idea of smart trout, but hey, some people watch pro wrestling too. A great chalk stream with a super abundance of food will reward fish who feed on one thing only. A poor stream will demand that fish look at more food options, but reject even real food if it looks a bit off. I see it as all part of a security/suppy balance continuum. When a stream has fishing pressure, we are actually impacting on the security/supply balance. That does indeed cause a change in feeding, but not because of memories.


    • paracaddis Says:

      Aha Paddy, either a slow day in the office or you are missing your proposed fishing trip, laid waste by rescheduled business planning. However I would have to say that I don’t really see a heap of difference in your argument to mine, not that I give a fig who is right anyway, it is an interesting discussion. I must point out, I have searched exhaustively, (I didn’t trust my editorship so went control F (Memory).. there is no mention of memory in my article, so I am not suggesting, although it is more than possible, that trout have the ability to remember stuff. What I am suggesting is that they can moderate their behaviour based on experience. If to paraphrase your words the trout seem to think that something is “funny” that must be born of experience surely, in that it in some way doesn’t match up with expectations. ?
      I totally agree that environmental factors, food availability and fishing pressure must affect the way that the successfully evolving trout behaves, I am not sure that I would realy like to venture how they process that information but it seems to me that processing it they most certainly are.
      Thanks for the feedback , I hope some other people will feel free to venture their thoughts on the same subject, it is after all one that has to be at the forefront of the piscatorial mind..

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: