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

09/21/09

Catching Yellowstone Trout in Cold Water - Part 1

Since tomorrow is the first official day of Fall, I thought it would be appropriate to
discuss the effects of cold water on trout. When I say "cold water", for purposes
of the article, I am referring to water fifty degrees and below.

When the water temperature of a trout stream is around fifty degrees
Fahrenheit, trout fishing can be excellent. As a matter of fact, it can be as good
as it gets. Thats because the water temperature itself is not a direct factor. It is
an indirect factor that affects the trout's feeding habitats and the extent they
feed. Catching trout doesn't necessarily depend on how much the trout eat.  
What matters is that you get your fly in front of them when and where they are
eating. You are going to catch only a tiny percentage of them irrespective of
how much they eat.

In general, the ideal water temperature is usually considered to be about
fifty-five degrees. That depends on a lot of things, however. It depends on the
species of trout, for one thing. The native Yellowstone Cutthroat trout found in
the park are capable of surviving colder water than the brown trout which are
the off spring of trout brought into this country from Europe years ago and at
one time stocked  in the park. In general, the rainbow trout prefers slightly
colder water than the brown. It also depends on the amount of food available to
the trout and the effort or trouble they have to encounter to eat it.

If you will pardon the exceptions, and what I mentioned so far is only a few of
many, then I would like to try to cover the basics of how to fish cold water. Again,
for purposes of this discussion, lets consider cold water to be anything less than
fifty degrees F.

One thing that is always important is the availability of food. We all know that
when most aquatic insects hatch, the trout can eat them much easier than they
normally can find and eat the larvae or pupae. They become exposed, so to
speak, and put themselves in a position of being on the trout's dinning table.
They must accent to the surface or crawl to the banks or rocks to fly away.

Now you are probably wondering what this has to do with cold water. Well, for
one thing there are a lot of species of aquatic insects that thrive and hatch in
cold water, again meaning fifty degrees or lower. Many species of blue-winged
olives hatch in water around fifty degrees and less. Several species of them,
including many species of
baetis, commonly hatch in water that is in the mid
forties.

Many of the caddisflies will hatch in water fifty degrees and below. The second
most plentiful and important species, or group of species, the Branchycentridae
family species, hatch in water forty-six to forty-eight degrees. These Little Black
Caddis can cause a feeding frenzy in cold water. Of course these caddis,
usually called "Mothers Day" caddis hatch in the Spring, not the Fall, but again,
this is about catching trout in cold water not just in the Fall but anytime. Some
species of the short-horned caddis or the
Glossosoma genera hatch in water
from forty-five to fifty degrees.

I haven't mentioned a big one yet. One most of your probably never even think
of when you are fishing streams in the Yellowstone National Park and thats
midges. Trout feed on midges all winter long. They hatch on some of the coldest
days. In fact it is even common to catch trout feeding on the surface in water
that is in the high forties and low fifties.

I think you are aware that water between forty-five and fifty degrees can and
does bring on some big hatches. During those times, cold water temperatures
doesn't seem to intimidate anglers like it does when it is not time for those
insects to hatch. This time of the year, those that don't know any better, often
look at water in that same temperature range as being too cold. That is a huge
mistake and points to a big misunderstanding of trout.

Just because these big hatches aren't occurring doesn't mean the trout don't
eat in water in that same temperature range. They eat plenty. They eat enough
that catching them is no problem provided you know how. In fact, catching a lot
of them is in many ways easier in water within that range than it is in water that is
in the low sixties, for example.

Now I haven't discussed water less than forty-five degrees yet, but it is also not
that difficult to have a great day and catch plenty of trout when the water is
between forty and forty-five degrees. What do the trout eat in the cold water?
With the exception of blue-winged olives and a few other aquatic insects that
hatch, they eat the larvae and pupae of many aquatic insects. After all, between
now and about the first of June, you will find more larvae and nymphs in the
water than there will be anytime after next year's hatches start.

Tomorrow I will get into where the trout hold and how they feed in cold water.


Copyright 2009 James Marsh