FLYMPH FORUM

Hi Everyone,
I just thought I'd ask if any of you have done any testing of the correlation between trout activity- feeding and water temperature. I myself have noticed a few things, and was wondering what others have noticed.

I'll post my observations later. In the meantime I'd be very interested in other ideas, thoughts, theories, and correlations.

Mark

A favorite topic . . . When I fished the Delaware drainage, the magic number for both hatching and feeding was 50 degrees. While I occasionally observed Baetis hatches on the Willowemoc at lower water temperatures, nothing would ever rise to the hatched duns. I once sat on a stretch of the W. Branch with Bob Nastasi, checking water temps every ten minutes on a cool April day. At 49 degrees, there was nothing happening. At 50 degrees, the Hendricksons began emerging in clouds, and the fish came up with them. Experience on the Beaverkill was identical.

Occasionally, I would find fish in the Beaverkill rising in cooler water to midge pupae drifting in the film, but this was generally in very specific locations and more often than not involved freshly stocked fish.

All of that said, fish and insect behavior seems to be governed entirely by the particular ecosystem. Example: the San Juan in NM below Navajo Dam emerges from the base of the dam at about 38 degrees, and it doesn't get a heckuva lot warmer in the first several miles. Yet, you'll routinely experience good BWO hatches and rising fish in water that is about 43-44 degrees, as well as good populations of hatching mideges that the fish gorge on.

EP

Mark,

If anyone is looking for good info on the correlation between water temp and trout feeding behavior, I would recommend checking out the book "Trout Tactics" by Joe Humphreys. The first section is completely devoted to this topic, and the revised edition includes an updated section in the back on the same info.

Tight lines,
Jay

Thanks, Jay, I'll need to dig that one up.

Mark

I realized I had not posted my findings, and would ask that everyone look at their findings as well to see if, perhaps, they coincide. I must say, at the onset, that every ecosystem is different, and the variables in that system would determine the conditions that are right for feeding activity.

Most of my fishing is done on freestone rivers and streams, with very little tail water fishing, which I am sure is somewhat different than where I fish. Some years back I read an article by Len Wright, Jr regarding temperature and feeding. Since that time, I have been testing the information presented in that article and found it to be true, at least, for where I fish.

The article stated that the highest point of trout feeding took place at 63 degrees F. It was not holding at 63 degrees, but approaching 63 degrees from either the lower or higher end. In other words as the temp approaches 63, the most feeding occurs. I have found this to be pretty much true.

Of course, as Eric has pointed out, 50 degrees is also an important number. It is usually when insect activity begins, and that also has a correlation to the 63 degree mark as well. Wright said the most insect activity occurred as the temperature approached the 63 degree reading as well.

I also know that trout MUST feed to stay alive, and will feed if they need nourishment; that their metabolism determines when this is; and water temperature affects their body temperature and metabolism. Oxygen content, as Mike has said, gets lower as temps climb, stressing the fish. These facts, however, do not undermine Wright's article. I may still have that article lying around, and if I do I'll see what I can do to share it.

Just as a little experiment, I suggest if you don't take water temps you start, and look at when the most feeding and insect activity occurs where you fish. Whether you discover the same as me or not, it will improve your knowledge.

Mark

Thanks Mark. Once again, you have challenged me to think and learn more about this great hobby.

Barometric pressure also has a bit to do with movements of freshwater invertebrates triggering hatches etc as well..

Mike,

I have no scientific evidence to base this on other than my own experiences but the most difficult times I have had fishing have been when the barometric pressure is actually changing. Once it has stabilized, whether high or low, the fish seem to become active again. I have also noticed somewhere between 2 minutes to 30 seconds before a rain storm, the fish become very active. These are strictly my own observations over the years. To be clear, this is on lakes. I can't say I have observed this on streams or rivers.

File on water temps. If it takes too long to open, I'll modify it.

Mark

http://flymphforum.com/files/WhenTroutFeed.pdf

Hi Mike, and all interested others,
Len Wright is one of my favorite authors. Unfortunately he passed away a while ago, but if you really liked that article, he's written number of great books. One is mentioned at the beginning of the article. Others include Fishing the Dry Fly As A Living Insect; and more recently Neversink, which I found not only very entertaining, but very informative as well. Mr. Wright chronicles his attempts to manage some of an area of The Neversink River in New York State. What he learned in doing so was wonderfully valuable. If you can procure a copy, I would suggest it to anyone interested in trout, rivers, streams, etc.

Mark