07/03/10
Insects and other foods the trout may be eating:
1.    Blue-winged Olives
2.    Cinnamon Sedges (Caddisflies) (Abrams Creek)
3.    Green Sedges (Caddisflies)
4.    Little Sister Caddisflies (Abrams Creek)
5.    Little Yellow Stoneflies -Yellow Sallies
6.    Slate Drakes
7.    Little Green Stoneflies
8.    Golden Stoneflies
9.    Ants
10.  Inchworms
11.  Beetles
12.  Grasshoppers
13.  Hellgrammite
14.  Cranefly
15.  Sculpin, baitfish and small crayfish (Imitate with streamers)


New Series on Fly Selection and Presentation - Part 5
Note: If you missed parts one through 4, please read them.

Scientist have been able to analyze a fish's vision. They understand what a fish can
and cannot see by knowing the makeup of their eyes, how the rods and cones are
arranged and many other things the average person is unaware of. To make a
simple statement about their eyes and ability to see, you can say that the trout's
eyesight is well engineered to allow it to feed and be able to detect any predator.
Fish are not on top of the food chain. They are near the middle. They have
predators that eat them and they eat other prey. Their eyes are well suited to be
able to quickly detect anything out of the normal, yet be able to feed on tiny insects
with precision.

To put this in even more layman-like terms. Fish can quickly detect a large bird or
large fish that it may get eaten by, not so much from being able to see it clearly and
in detail, but from its movement that's out of the ordinary. That's why a large crane
will stand in one place dead still until a fish swims beneath it. The crane is
conditioned such that it's aware that if it moves, it will spook all the minnows and
small fish within several feet of it.

If you are a hunter, you are aware that you detect game like turkey easier by getting
a glimpse of their movements in the woods than being focused on one particular
area of the forest. Fish detect their predators much the same way. The difference is
their eyes are arranged to do this much better than our human eyes.

In order for us to understand what the fish can and can't see, we have to be familiar
with what is called the 'field of vision". The entire area we see, or any animal sees, is
called the field of vision. When you shut one of your eyes, the area you can see is
called "peripheral vision". The area we see with both of our eyes is called  
"binocular vision'.

We have a 176 degree field of vision. That means it covers about half of the 360
degree area around us. Our zone of binocular vision is 90 degrees. That leaves 86
degrees or 43 degrees of our peripheral vision on each side of our binocular vision.

The eyes of a trout are on the sides of its body. This provides for wide peripheral
vision and but narrow binocular vision. In comparison to our vision, a trout has only
a 30 degree wide field of forward binocular vision. Its peripheral vision is 300
degrees or 150 degrees on each side of its forward binocular vision. It can see
almost all the way around itself. Peripheral vision allows both us humans and trout
to detect movement better than we can using our binocular vision. Since animals
rely on this to survive, most of them have very wide peripheral vision.

Binocular vision allows good depth perception and the ability to see things in detail.
A trout uses its narrow binocular vision to feed. Although trout do use their
peripheral vision to detect food, when they do, they have to turn their heads to get it
within the binocular field of vision to see it in any detail. I[m sure you have noticed
that when you cast to the side of a trout, as soon as it detects your fly, it turns its
head toward the fly. It has to do that in order to get better look at it.

I'm sure most all of you have done this at one time or another, even if it was years
ago in school, but for those that are not at all familiar with focus try this. Hold your
finger in front of your face about a foot and a half in a room inside your home or
office. Focus on the tip of your finger and you will notice everything at the far end of
the room goes out of focus. Focus on the end of the room and you will notice your
finger go out of focus. I'll get into how this relates to the trout tomorrow.

Fish see color wherever light penetrates the water. In fact, they see color better
than us humans. This is one of the things I will also get into soon.