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Does the fly really matter?

I thought I might be the first to do the definitive study of "does the fly really matter" but it seems that a team of CRACKPOT investigators has beaten me to it. Not only did they beat me to the study, the published it in The BMJ (British Medical Journal), one of the oldest and most prestigious medical journals in the world. Britton and his colleagues tested five dry flies on the River Kennett: black gnat, parachute Adams, grey Wulff, cinnamon sedge, and gold-ribbed hares ear (dry). And their results were staggering, especially given their suppositions about these flies.

Despite their scientific study, they knew some would not approve of their methods and some have even questioned their methodology and objectivity.

It may be objected that our study is no more than a fishing expedition in that we had no agreed a priori hypothesis on the relative efficacy of the flies tested. Our results may therefore be regarded as hypothesis generating rather than hypothesis testing. Clearly, however, the possible prolongation of doctors' leisure time consequent on the use of unproductive trout flies has resource implications that the NHS may not read­ily bear. Our findings call for the urgent funding of a definitive, large multiriver trial.

After many arduous hours of testing, the authors were able to come to some results and started to try to understand these results. It is, as I have written a few times, very difficult and maybe impossible to try to understand what it is a trout is "thinking". Despite these challenges, the authors pressed on and did their best to try to get inside a trout's brain.

Like all anglers and researchers, they went into the experiment with expectations based on their prior experiences. They were fans of the Grey Wulff and had their doubts about the cinnamon sedge. The black gnat, parachute Adams, and Gold Ribbed Hare's Ear (dry) fell in between those two extremes.

And like most experiments, our a priori expectations may not match our results. The Cinnamon Sedge dry fly caught the largest bag both in numbers and in total weight. The Black Gnat caught the largest fish on average, though it caught by far the fewest trout and the lightest bag. Rainbow Trout (Oncorhynchus mykiss) which the authors disparage as rather "dumb" fish were more readily caught on the GRHE dry fly and the Cinnamon Sedge only caught one of these dumb fish. Wily Brown Trout (Salmo trutta) were much more commonly caught on the Cinnamon Sedge than any other fly.

Does Fly Really Matter?

Maybe you are a bit dubious about the CRACKPOT team's methods, results, and/or their conclusions. Fly certainly matters but how much? I do not know - nor does anyone else. We all have our favorite flies, the flies we have confidence that will catch fish for us. I get no shortage of shit, err, a jolly 'ole ribbing from friends for having the world's most diverse yet underfished fly boxes. I wrote a post about my Driftless baker's dozen - fact is that while I fish them all throughout the year, my confidence flies are the CDC and Elk, the Milwaukee Leech, and Andrew Grillos' Hippie Stomper. Add in "my cricket" when the fishing is really tough in the middle of summer, a Sparkle Dun when we get a mayfly hatch (too seldom recently), and a Coulee Cranefly when they are hatching. Yes they are all dry flies - what do you take me for, a heathen?!

Grillos' Hippie Stomper in purple - why purple? Who knows but it works.

One of my most unique days of fishing was on a bit of private property we asked permission to fish and probably were better off to have asked another day. The stream was high and brown and the fish were way less than cooperative. We tried all the dirty water flies - San Juan worms, woolly buggers and other dark streamers, and the whole gambit. The solution was a large bright pink Chernobyl Ant which broke the skunk. Did fly matter? Maybe, or maybe I hit ran across a few willing fish.

Pink Morrish Hopper
A pink Morrish Hopper in a Driftless Brown Trout's mouth. Why pink, who knows (and one of these days I'll finish up writing that post).

Many would argue that "presentation" trumps fly but then the definition of "presentation" is rather ambiguous. Presentation is some combination of the fly and how it is cast and manipulated. And of course fly has a lot of effect on how the fly moves, how it sinks or floats, how easily it is mended, how it attracts good - and not bad - attention from fish. So I went to the source, Borger's Presentation and pulled it off the shelf for the first time in more than a few years. He writes:

Presentation is often described as the ability to make an artificial fly look, to the fish, like something good to eat. And consequently it's usually though of in terms of casting and line handling techniques.

He goes on to write about - in rather great detail - about the hows and whys of presentation. Borger writes about aspects of fly design - many of the same ideas in a post on moving flies I wrote a month or so ago (and nobody read...not that do it for the reads...). The long and short of it is that fly pattern matters but it is but one aspect of being successful. Rarely is the fly probably the limiting factor, the reason you are not catching fish. But sometimes it may be.

Rick Frye Memorial Fly Box
The Rick Frye Memorial fly box that I bought at the Wisconsin Trout Unlimited State Banquet - flies for the Driftless tied by a number of Rick's friends (including me).

The old adage goes that when fly matters, it matters the least. And when fly matters, shape, size, and color - in that order - are generally said to be the criteria fish use to determine what to eat or not eat. Of course this is in no small part speculation based on angler experiences but we don't really know why they choose a particular fly.

Low Rider Cricket
A low floating cricket (or beetle) pattern that I have supreme confidence in during the late summer.

Certainly fly purveyors want us to think that fly matters, a lot. There are hundreds of different patterns - from quite realistic to impressionistic. My thoughts? Find a few fly patterns you have confidence in and work on the things that matter more than does the fly. And that is not just the cast. Want to increase your odds? Work on not only the cast but how to make your presentation simpler. Think about how you can be stealthier. Those things all matter a lot more that fly pattern, though fly pattern matters.

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2 commentaires

Jason G. Freund
Jason G. Freund
07 févr. 2022

Thanks for the story - I agree, of course fly matters. It's just difficult to know how much and when. Lots of efforts goes into figuring it out, or at least trying to.


Of course the fly really matters.

I grew up near Lake Superior’s North Shore, fishing for the wild brook trout in the headwaters of the streams. What could be easier to catch than a bunch of hungry small stream freestone brook trout? But some flies worked better than others. Over a period of two years I changed each material and each color of a wet fly one at a time and tested each new fly on the wild trout, keeping the best changes and discarding the others, until I had a fly that worked all season long on my brook trout streams. It had a silver tinsel body, pale yellow calf tail underwing, turkey quill slip wings and three turns…

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