Insects and other foods the trout may be eating:
1.   Blue-winged Olives - mostly Little BWO - Isolated hatches
2.   Cinnamon Caddis - Mostly Abrams Creek
3    Little Sister Caddisflies - Mostly Abrams Creek
4.   Midges - hatching in isolated locations
5.   Little Yellow Stoneflies - hatching (Little Summer Stones)
6.   Slate Drakes - hatching
7.   Little Green Stonefly - hatching
8.   Cream Cahills - hatching in Isolated locations
9.   Beetles
10. Grasshoppers
11. Ants
12. Inch Worms
13. Crane Flies
14. Helligramite
15. Streamers - matching sculpin, baitfish and small crawfish

The Learning Process - Part 24
Continued from Yesterday's Article

I have a difficult time of determining exactly when we began to figure out that
(1) when there was a large concentration of insects or (2) when there was a
moderate concentration of insects that were around for a long period of time, the
trout would ignore almost everything else and eat mostly those insects. This is what
many call "selective feeding". The problem with using that word is that it means
different things to different people. I suppose that if it means the trout are eating
only one insect, there wouldn't be any such a thing. If it is used to mean the trout
are ignoring most everything and mostly eating one item of food, then it happens
ever once in a while. If it means, the trout are mostly eating one insect and
excluding most of the others, then it happens quite often. So somewhere in between
those ranges lies the meaning of selective feeding depending on who you are
taking to.

We discovered the use of the word the first year we fly fished for trout. We also
discovered the use of the word "opportunistically". I too was often used to describe
the way trout ate their food. The phrase "Trout feeding opportunistically" was
described by some as when trout ate any and everything they could find to eat. We
determined that word or phase also had a range of meanings depending on the
person that used it.

As you can probably tell, I am not very good with the use of the King's language
anyway. My background is in engineering. I did have enough understanding to
quickly determine that trying to describe the way trout ate their food using only one
of those two descriptions (selectively or opportunistically) left a lot of questions. I do
remember that the first year we fished in the Smokies we were told that in the
Smokies, the trout only feed opportunistically. It took another two years or so, to
determine that trout really didn't feed any differently in the Smokies than they do
anywhere else in the World. We figured out that a brown trout was a brown trout,
and a rainbow trout was a rainbow trout. We did find out quickly that there was a
huge difference in trout that were raised in a hatchery and those that were born in
the stream. It quickly became obvious that you better qualify which type of trout you
were talking about as being stocked or wild before you said much of anything.

When we were fishing a trico hatch on the Missouri River in Montana, we were told
by the locals that the trout feed "selectively" on the trico mayflies. Before we were
told that, Angie managed to catch several large rainbow trout on a #16 fly that
imitated a beetle. However, when we used a trico spinner that was not exactly the
same size of the naturals on the water, we found out the trout ignored it. Several
other times, we found out when insects blanketed the water and the trout were
eating them right before our eyes that occasionally they would take a fly that didn't
come close to resembling the insects that covered the water. In fact, we found that
every once in a while, that seemed to be a good way to catch a trout. When your fly
represented only one out of a thousand of the insects in the water, it sometimes
paid to use something completely different. In other words, we really couldn't find
any situation where the trout would take only one and only one thing exclusively in
spite of how many insects there were one the water.

The problem was, under some conditions where one insect blanketed the water, we
found the trout seemed to ignore any other fly. Finally, my engineering background
began to be of more help than English. I realized that when someone is out on a
stream fishing, casting at trout for a few hours, the statical results of his or her
findings was almost completely irrelevant. In a tight race, you want figure out who is
going to win an election by asking twenty people. You need to ask at least a
thousand. My understanding of statical mathematics quickly pointed that out. We
couldn't find a single situation were the trout would only eat one and only one thing
and never consider anything else. We could find plenty of situations where that if
you didn't fish something identical to the bugs blanketing the water, you were
waiting a lot of time. It finally occurred to us, that was the reason scientist will tell
you trout never feed selectively. When they use the word selectively or
opportunistically, they use it with a strict interpretation of the word's meaning. If trout
ate 999 PMDs to one beetle, scientist would defined it as "opportunistic feeding".

As you can probably tell, the point I am getting to, is that trout may never feed
100% of the time on one and only one insect but under some conditions they may
very well feed from 75% to as high as maybe 95% of the time, on one insect. We
found out that often when one insect was present in larger quantities than the other
insects, the trout would feed mostly on the one that was most available, especially if
it was easy for the trout to acquire. Under those conditions, most of the time they
would exclude the other insects. We found it to be more to do with the trout just
focusing on the drift, or particular distribution pattern of the one insect than it had to
do with the particular insect itself. They simply want go out of their way to eat
another insect when they can stay in one area and continue eating whats most
available and what is following the same drift. It is just nature's way for the trout to
eat efficiently.

It seemed we and everyone else was making another mistake. We we were thinking
in terms of selective and opportunistic feeding, we were focusing only on the insects
on the surface of the water. It didn't always occur to us that trout eat far more
insects under the water than they do on the surface because we preferred the dry
fly fishing. Often you will hear anglers say trout eat ten times more food on the
surface than they do below the surface. I soon found out that it was almost
impossible to determine the percentages out on that. Unless you had a controlled
environment and underwater cameras set up, I don't know if you could ever get
close to knowing. I also suspect it would change from one day to the next and one
stream to the next stream. Okay, I will stick my neck out and say that if i were
pressed to guess, I would say trout eat 100 times as much food below the surface
as they do on the surface of the water. Yes, I really did say one-hundred times as

Now, if either ten times or one-hundred times is even close to reality, and trout
focus on eating the most available food, wouldn't it make sense that the trout often
focus on eating one type of nymph or larvae? Could I go back and use those same
two words "selective" and "opportunistic" as applied to trout eating food under the
water where they eat most often. If you will permit me to do that, I suppose I could
classify trout as either feeding selectively on nymphs or larvae, or feeding
opportunistically on nymphs and larvae.

For example, lets suppose Little Yellow Stoneflies (Yellow Sallies) were hatching.
We know that they move to the banks during the day, especially during the
afternoons, to crawl out of the water at night to hatch. We also know these stonefly
nymphs normally stay hidden down between and even under the rocks on the
bottom but when they crawl to the banks they are exposed. They are also
concentrated in one area of the stream - the banks. I guess we could say in that
event, the trout may be feeding selectively on Little Yellow Stonefly nymphs. All
things considered, wouldn't it make sense that your odds of being successful would
be fairly high if you fished an imitation of the Yellow Sally nymph along the banks?

Lets say that it is early spring and the Little Black Grannom caddisflies are
hatching. In the middle of the afternoons, there are lots of the Little Black caddis
pupae drifting to the surface to hatch into adults. The trout can almost line up down
the current seams and eat all they want to eat. I guess I could say, the trout are
feeding selectively on Little Black Caddis pupae. If nothing else was hatching,
wouldn't it make sense the trout would concentrate on eating the pupae?

Lets suppose that a couple of weeks later, the little Blue Quill mayflies are hatching.
These little nymphs are concentrated in the slower moving water in calm pockets
and along the banks. Lets condense it by saying the trout are feeding selectively on
Blue Quill nymphs. Wouldn't it make better sense to fish an imitation of their nymph
in type of water they hatch in that it would to fish something else?

Once we figured out what was really just plain common sense, we began to focus
on imitating the food that was most plentiful and readily available. It really doesn't
make any difference what you label or call it. We just knew that would increase our
odds of success more than anything we could do in terms of selecting a fly to use
and the method we used to present it. We don't have a favorite fly or a favorite
method of fly fishing. Like most everyone else, we prefer certain types of fishing
over others. However, if we are strictly trying to catch trout, or advising anyone the
best way to catch them, we focus on imitating the food that is most available and
easiest for the trout to acquire. That may change two or even three times during
one day. For example, it may change from a mayfly nymph, to a mayfly dun to the
mayfly spinner of a certain species. It may change from a mayfly nymph, to a
caddisfly pupae to a stonefly egg layer during the same day. Focus on the insects
that are the most plentiful and available at the time when you are fishing and see
just how much your success increases. You may just be amazed.

Copyright James Marsh 2009