The Stream Doctor

March 8th, 2004

Email YOUR Questions directly to the Stream Doctor. This is your opportunity to get an experts professional opinion on anything stream related.

Q. From LSHEH: What are the water temperature ranges that best facilitate the optimum feeding cycle for the most popular trout, e.g., rainbow, cutthroat and brown.

A. This is very difficult to answer and what I say probably won't entirely satisfy you. The problem is that optimum temperature ranges for any activity can vary from species to species and among different populations of the same species. This is because optimum temperatures for spawning, feeding, etc. are largely determined by the temperature to which the particular population has been acclimated. A population of rainbows living in a relatively warm stream or lake will have different optimal feeding temperatures than a population acclimated to a cold environment. In general, warmer temperatures increase metabolic activities up to a point; then it adversely affects growth, movement, feeding, etc.

Thus, it is virtually impossible to answer your question with any degree of precision. I talked to a local fishery biologist to confirm the above and he agreed with me. There are data available showing the temperatures and ranges at which various species of trout grow best, preferred spawning temperatures, etc., but this doesn't address your question. Let me know ( if you want to pursue this further.

If you have a question, please feel free to contact me.
~ C. E. (Bert) Cushing, aka Streamdoctor
105 W. Cherokee Dr.
Estes Park, CO 80517
Phone: 970-577-1584

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to anything stream related directly to him for use in this Q & A Feature at

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