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June 28th, 2004
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Q. Being a fish biologist and familiar with some of your work, I was quite pleased to get a chance to "talk" with you. I live in central WA state and have recently (3 years) started fly fishing. One disparity has always puzzled me to some degree. Why are the rivers of Montana and some of the other Rocky Mt. states so much better at producing more and larger fish than the rivers in my neck of the woods?
A.
You're exactly right, there are many factors that
interact to produce the productive characteristics
of streams. You cite some of the major out-of-stream
factors, and it would take me more space than we
have here to enumerate the many in-stream factors
that influence productivity. I'm not trying to
dodge your question; it is just too complex to
tackle here. Suffice it to say that one of the
crucial points influencing salmonid production
(and I'm speaking now about resident trout, not
anadromous salmonids) is the amount and type of
secondary production in the form of trout food
(usually insects). Now, substratum, nutrients,
and light regime are important factors influencing
the amount of primary production (algal growth)
in a stream which is a major source of food and
energy for the insects, so we can add these to
your list. Terrestrial organic matter falling
into the water and decomposing is another important
food source for invertebrates. From the other end,
predation, cover, suitable spawning habitat, and
fishing pressure can all influence the numbers of
fish present. I'm just getting rolling here, but
better stop before I have to let a lot of loose
ends hanging. I wrote an article entitled "Sunshine,
bugs and trout" in the Spring 1995 issue of TROUT
that attempts to briefly describe how stream ecosystems
function and what factors influence the structure and
function of flowing waters. Though not exhaustively
detailed, it does a pretty fair job of hitting the
highlights. If you'd like to read it and can't locate
a copy, let me know and I can send you a xerox copy
of the article. Contact me at cecushing@aol.com
I'm going to throw out a couple of other observations
pertaining to your question. I went to WA in 1961
after having been raised in CO (where I now live)
and working as a fish biologist in CO and MT. I
was amazed at the emphasis WA fish biologists gave
to anadromous salmonids and at how little they
seemed to be interested in resident trout populations.
My neighbor and co-worker was a fishery biologist
and he gently made me aware of where the priorities
were in the state. It seemed to me that resident
trout were just above trash fish in priority! This
led me to believe that the paucity of trout fly
fishing in the state was possibly related to
management decisions, i.e., manage the streams
for salmon and steelhead and don't worry about
resident trout. I also came to wonder if healthy
resident trout populations could exist in streams
that supported extensive anadromous fisheries;
could resident trout populations compete with
larger salmonids?. However, all you have to do
is look at the Deschutes River in Oregon to see
that the two can co-exist.
Well, I've talked all around your basic question
of why the fishing is better in the Rockies than
in the Cascades. I agree, and rather that fight
it when I retired, I moved back to CO!!
~ C. E. (Bert) Cushing, aka Streamdoctor 105 W. Cherokee Dr. Estes Park, CO 80517 Phone: 970-577-1584 Email: streamdoctor@aol.com
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