.......................  ......Fly Fishing Yellowstone National Park


Choosing the Right Fly - Part 12

The Big Misconception:
When there is no hatch occurring (which is probably 75% of the time) anglers
tend to think they are better off using an attractor or generic imitation that
imitates a variety of things. A fly that imitates no specific insect but rather a
variety of them works best when environmental conditions (water temp, oxygen,
stream levels, etc) are near perfect and lots of insects are readily available for
the trout to eat. In other words when anyone that can cast a Royal Humphy
twenty feet upstream in a run can catch trout. When you can hit them over the
heads with the line and they still will eat the fly, a Royal Wulff works great. When
there is little challenge in catching trout, most anything made of feathers and
hair with a hook in it will produce some good results.

This big misconception came about because book after book about trout fishing
lumped things into one of only two categories - selective feeding or opportunistic
feeding. Most anglers think that trout are feeding either one way or the other. It
is true that if trout are not feeding exclusively on one insect, they are
categorized as feeding opportunistically, so by strict definition, I suppose they
are. That is fine as far as categorizing them is concerned but it has little to do
with what is really going on and it is of little information or use in catching trout.

For example, lets suppose that there are lots of Little Yellow Stonefly nymphs
crawling to the banks to hatch. Don’t think the trout don’t know it. They view their
underwater world 24 hours a day and they know and see exactly what is going
on. Since these nymphs are crawling across the bottom to get to the banks, they
are easy prey for the trout. Naturally, the trout will focus on feeding on the easy

If the trout are eating these nymphs migrating to the banks and a stray mayfly
nymph happens to come along, the trout may or may not eat it. Most likely, if the
trout does not have to go out of its way to do so, it may very well eat the
mayfly nymph. If it takes more effort than it does to catch another stonefly
nymph crawling to the bank, it most likely won’t eat it. Lets suppose a trout did
eat the mayfly nymph. By definition you would have to categorize the trout as
feeding opportunistically. That is why marine fishery biologist classifies all trout
as opportunistically feeders. It makes sense from a scientific standpoint but little
sense from a practical standpoint of catching fish. A particular trout may be
feeding selectively at the same time one a few feet away may be feeding
opportunistically. One run or riffle may have several trout that are feeding
selectively at the moment when another run or riffle a few yards upstream may

Call it whatever you prefer to call it. Under these conditions, would you rather be
fishing an imitation of a stonefly nymph or a mayfly nymph? I think most anglers
would agree that your odds would be greater if you were fishing an imitation of a
Little Yellow Stonefly nymph.  

Continued tomorrow

Copyright 2009 James Marsh