Smoky Mountain Steam Journal:

Stream Water Temperatures (8/19/07):
We are still getting a large amount of email from concerned anglers - some from
this site but mostly from our new Yellowstone site                
www.flyfishingyellowstonenationalpark.com).
We do not have a Journal set up for the Yellowstone site but we hope this will
answer most of your questions regarding water temperatures as related to
oxygen content for the Smokies.
I am not a marine biologists. For the last thirty or so years I have been fishing
(the last twenty plus years on a full time basis or professional basis - meaning
that it accounts for the majority of my income and many years - my only income)
I have been able to fish with and discuss on the water and off the water such
environmental related subjects at length with many marine biologists as well as
numerous other professional anglers.  
When I fished the professional BASS circuit in the late seventies and early
eighties, it was a prime subject. Catch and release was being practiced and
BASS had penalties (and still do) for dead fish. This could cost an angler a
substantial amount. I remember one tournament on West Point Lake Alabama
where a two ounce penalty cost an angler over $20,000.00. The high air
temperature during the three days of the tournament stayed above 100 degrees.
Now I realize bass are not trout but I also realize that there are similarities in the
manner in which the two types of fish ( different bass and trout species) relate to
oxygen and water temperature levels and changes. We studied and learned
everything we possible could about water temperatures and oxygen content due
to the fact in was a factor in catching bass and keeping them alive. We all had
surface water temperature gauges built-in our boat as well as the type you drop
down to the bottom or any depth. We even had electronic oxygen measuring
gadgets for a while back then. We did everything we could to keep bass alive. If
a fish showed the slightest indication it was starving for oxygen (and believe me
we knew) we did many things to help it out. Live wells were required and how
one handled fish was critically important.
My many years of saltwater fishing dealt with this same thing, just different
species of fish. I didn't charter my boats, work in a tackle shop or fish only on
weekends - I fished almost every day on camera. I produced over a hundred
television shows and forty-six instructional videos on saltwater fishing. I am told
that more of my videos have been sold on saltwater fishing than any others in
the world. They still sell in good numbers today. Now I will get off my background
and on to the subject of trout.
During the past eight years of trout fishing we have been concerned with this
issue almost every year. Water temperature is important anytime of the year.
Again, we don't fish on weekends only, work in a fly shop or guide beginners.
We fish on camera over two-hundred days a year from coast to coast. We study
the subject of trout fishing on a full time basis. We are in constant contact with
several biologist and entomologist regarding whatever our quest for information
may be. This subject of water temperature and oxygen content of the water has
come up many, many times but mostly concerning the Western states. There the
air temperatures can and often does start out at thirty-five degrees in the
mornings and reach ninety-five that afternoon.
I could write a book about the subject (and may just do that one day) but I will
get to the point.
We don't catch or release trout when there is a reasonable doubt as to whether
or not the fish will live. We don't have to worry about whether they will live or die
because we know what we are doing. When you catch trout almost every day for
eight years, and release everyone of them, you would have to be plain stupid
not to realize when the trout were stressed.
We never guess at the water temperature. We carry two thermometers and
check it almost every day we fish, especially if there is a question about it being
too warm or too cold.  
What I am about to say about this varies from location to location as well as to
the species of trout, so keep that in mind.
The amount of dissolved oxygen in the water is directly related to the water
temperature. In case you don't know, cold water holds oxygen much better than
warm water. The effects of water temperature on the amount of dissolved
oxygen doesn't change at a constant rate. It changes at an accelerated rate.
In general, for most species of trout, the fish are most active when the water
ranges from about 50 to 65 degrees. The cold-blooded trout feed at the
maximum rates due to their metabolism level in this range. From 65 to 70, this
accelerated rate I referred to begins to take place. In simple terms, at 65 there is
no problem and the trout feed aggressively. At seventy degrees, there can be a
problem depending on the type of water. The dissolved oxygen content can be
low.
Still water is one thing and fast, turbulent water is another. The amount of
dissolved oxygen will vary greatly. That is why you hear to "fish the oxygenated
water" all the time.
When the trout start hurting for oxygen, they will begin to cease their feeding
activity. It is not a great deal different from the way they react in very cold water,
just due to a different reason.
When the water reaches about seventy-four degrees, the trout just about have
to have highly oxygenated water to survive. Again, keep in mind that these
temperatures are guide lines. Again, the particular species of trout and its
location and more specifically the type of water it is in will vary this somewhat -
not greatly, but a little.
All of us that want the fish to survive want a safety margin. We don't want to
catch a fish that shows signs of being stressed. Just like when you climb a high
mountain and give out of breath (especially out West at ten thousand feet), you
will have to sit down and you will struggle for breath - the trout will stop fighting
as hard. If it is in your hands being released, it will not be difficult to hold. When
you put it back in the water (which should be done just as quickly as possible), it
want hesitate to leave. It won't swim off slowly. It will shoot off like a rocket, as
Angie often says.
If it rolls over, or slows down and want shoot off like a rocket, it may be stressed.
Does this mean it will die? Not any faster than you when you give out of breath
climbing the mountain. It puts the fish at some risk, but just how much risk
depends on a lot of things. To shorten this, there has been many times that I
have wanted to give bass mouth to mouth, only to see them active as they could
be minutes later.
Will they swim off and die? According to many studies on just this subject, the
answer is usually not. The great majority of them will be just fine. Of course,
every once in a while, one may die. In my opinion, they will die at about the same
rate as you if you give out of breath climbing the mountain. Far more will die
from anglers taking pictures and/or mishandling the fish otherwise - far more.
This summer, if there is any question about the water temperatures, fish at the
high elevations. Take the water temperature. Don't guess at it. If it is below (lets
say sixty-eight degrees) catch all you want and just make sure you release them
as quickly as possible. If it is higher or has the chance of getting any warmer, I
would suggest you look for another location. They will not be easy to catch and it
is possible, if the fish is mishandled, for one to die.
For the past week we have found several locations on streams above three
thousand feet where the water was sixty-two to sixty three degrees. When we
have, the fish have been easy to catch and they all have been released in very
good condition.
We appreciate the concern of many of you. We had much rather see the
concern than not see the concern. However, some have blown this problem of
fish stress and mortality completely out of proportion - some unintentional and
some trying to impress anglers as the "savior of trout". You will never see them
on the water and you will never hear them raising hell at the National Park
biologist for allowing anglers to keep and kill their fish according to current bag
limits. However, you do hear them wanting to see hard scientific data on fish
survival under drought conditions. It seems they rely on the biologist only when it
suits their purpose.

Copyright 2007 James Marsh