12/02/10
Insects and other foods the trout may be eating:
1.    Blue-winged Olives
2  .  Sculpin, baitfish and small crayfish (Imitate with streamers)
3.    Great Autumn Brown Caddisfly
4.    Midges


Holiday Gift Guide - Somebody You Know Wants One Of These Sets
Of Flies.
Click Here for A List of Trout Fly Selections


Part One: New Great Smoky Mountains National Park Trout Food
Series
Before I even got started good, I realized I have already thrown out some
terminology that some of you may not be familiar with. I mentioned clinger, crawler,
burrower and swimmer mayfly nymphs. I also mentioned that most all stonefly
nymphs are clingers. I failed to explain what these different types of nymphs are. By
the way, all of the stoneflies except about a half of one percent are clingers, so
before some genus complains, I'll correct that. Let me say, a very few species of
stoneflies, which don't exist in the Smokies, are called a crawlers.

Now, what does these names mean.
A
clinger nymph is one that is generally wide and flat. It actually does "cling" to
rocks. In fact, to get some of them unattached can be a problem. You almost have
to pry them off the rocks, usually the bottom of a rock. Their configuration can
actually provide a suction that helps them "cling" to rocks. They are found in fast
water and the "flat" configuration of the nymph helps keep down the drag of the
water. They are streamlined to cut through the water even in strong current. Like a
race car uses down-force to keep it low and fast, the clinger nymphs use similar
laws of physics. They don't live on top of the rocks, by the way. They live in crevices
and spaces down between and under them and only come out to feed, exposed on
the bottom during low light situations or at night. Again, we have lots of clinger
mayflies in the park and all of our stoneflies are clingers. Scientists sometimes call
clingers nymphs Flatheads. March Browns, Cream Cahills, Light Cahills, and Quill
Gordons are examples of clinger mayflies.

A
swimmer nymph is one that acts more like a small minnow than a nymph in many
ways. They can actually swim short distances, or in short spurts. They dart about in
the water and can hide in cracks and crevices of rocks or just about anywhere for
that matter. They cannot handle swift water. It will carry them along with the current
so they avoid it altogether. The prefer slower to moderate speed water. You may
find some an inch away from swift water, but not in it. They like the calm pockets,
eddies, and anyplace the water is flowing slowly. They are streamlined like a small
fish, with longer, narrower bodies, shorter legs and gills. Scientists sometimes call
these "minnow-like" nymphs and some, the "bushy-legged" mayflies. Slate Drakes,
Blue-winged Olives (most of them, not all), Blue Quills and a few others.

A
burrower nymph is one that lives in a burrow, or hole in the bank or bottom.
They only come out at night or low light to feed. Naturally, they have to have soft
soil to be able to dig a burrow or hole. They are found in slow to moderate flows.
There are very, very few in the park. They do exist in Abrams, in the form of Green
Drake mayflies. They also exist in some of the larger streams close to the point they
exit the park but usually in water to warm for trout. There are also a few Yellow
Drakes. Most all drakes are burrowers.

The
crawler nymph is a "catch all" category because it has a large variation in the
shapes and configuration of the nymphs, their habitats and their behavior but in
general, I would describe them as follows. They cannot swim as such but when they
hatch, they can wiggle their way to the surface and I guess you could call that
swimming. Their bodies are generally round shaped. Some are very short and
stocky and not well streamlined but others are about the same length as clingers.
They generally "crawl" around on the bottom when they are feeding. They are not
well suited for fast water. You will find some of them in the streams of the Smokies,
but only in the slower and more moderate sections of water. They can live in areas
of riffles and faster water but they select the slower areas of the flow and avoid the
fast water. For example, a Sulphur mayfly is a crawler nymph that lives in large
numbers in the South Holston River where the water can be moving fast; however,
they hold in specific areas of slower water out of the strong currents such as behind
rocks, under ledges, in the marginal water out of the main flows. In the freestone
streams of the Smokies, they are not nearly as plentiful overall as the clingers. Of all
the mayflies that exist in trout streams, the crawlers are by far the most plentiful.
This isn't true in the Smokies and it is isn't true in most any fast water, headwater
stream. Crawlers can live in riffles and even the bottom of fast runs but only in
certain areas where they can avoid the current. By the way,  most generic or
standard type nymphs, such as the Hair's Ear Nymph, are shaped more like
crawlers than any of the other three types. Most generic nymphs are very poor
imitations of clingers, swimmers and burrowers. Scientist sometimes break the super
family of crawlers down into more classifications to help distinguish them. They call
the Blue Quills nymphs "Spiny Crawlers". "Little Stout Crawlers" are the shorter,
heavy legged crawlers like the Eastern Blue-winged Olives.  As just mentioned,
Sulphurs are crawlers along with Eastern Pale Evening Duns, Hendricksons, and
others.

One simple tip that will be covered in much more detail is this. Trout can see very
little above the water (through Snells Window) and the view trout can get is mostly
distorted due to light refraction. They cannot view anything outside of this relatively
small circle (window) directly above them and only then if the water is smooth, or not
rippled. However, they can see everything very clearly beneath the surface in clear
water. They can easily see all the movements and all the creatures in the water
around them. They can see underwater objects much, much clearer than objects
above the surface of the water. They are just as used to seeing nymphs,
crustaceans, minnows, etc., as we are food on the table and fast food places along
the highway. These statements aren't opinions. These are facts. I will get into the
subject of how trout view things around them at a later date in more detail.

Now, using your own common sense, which do you think is most important. Having a
nymph that looks like a real nymph, or having a dry fly that looks more like the real
fully grown insect?

Why do fly tyers and for that matter, most anglers pay far more attention to the
appearance of their dry flies than they do their nymphs?

What's the big deal about the type of nymphs:
Now that all of the above has been stated about the classifications of different types
of mayfly nymphs, and stoneflies that are all clingers for that mater, what is its
importance to an angler? These different types of nymphs, that have been put into
four basic classifications,
have evolved to live in different types of water in
regards to current flows, bottom types, and food that's available for the
nymphs to eat
. I will get into that in Part Two, tomorrow. For now, let me make a
quick summary.

1. Clingers - Flat heads and bodies suited for fast water with lots of oxygen. There
are far more clingers than any others in the Smokies. These nymphs stay well
hidden most all of the time and are not often readily available as trout food.
2. Swimmers - Minnow like nymphs with small, narrow bodies that can swim and hide
in almost any type of cover about the same way a minnow can. These are the
second most plentiful nymphs in the Smokies. Let me also mention the reason there
are many is the fact most all of them will be eaten by fish and its takes a large
quantity early in the year to end up with enough to sustain their population.
3. Crawlers - Rounder bodies, larger gills and legs and build to crawl around to hide
and feed. Third most plentiful nymphs in the Smokies but the most numerous in all
trout waters. Like the swimmers, lots of these get eaten by trout and it takes a larger
number of eggs and juveniles early in the year to sustain the smaller population.
4. Burrowers - Round, longer with some type of claw or way to dig holes in soft
bottoms of soil from one to six inches deep. Big Gills for less oxygen. Least
numerous in the Smokies.

For now, lets (almost) just forget #4, the burrowers, for consideration in the Smokies
except for the Green Drakes in Abrams Creek that I will get to in the near future.
Forget the small number of Brown, Gray, Yellow and large Hex drakes that exist
mostly in the large creeks at the point they flow out of the park. There are plenty in
some streams just outside the park, in typical smallmouth water and stocked trout
water, but not inside the park. They could be important but only in highly, isolated
circumstances.

Tomorrow, I will explain why knowing the type of nymphs of the various mayflies is
very important.

Copyright 2010 James Marsh