Trout feed best at 62°

THE FACTS

1. Trout are cold-blooded. Varying water temperatures can radically affect behavior.
2. Trout in the San Juan River in New Mexico, live year-round in 43° – 45° water  – and eat like pigs.
3. Let’s suppose water temperatures are stable at 62° and fish are feeding well.  Then we have a really cold night with a hail storm and the water temperature drops to 56° within 12 hours. You will not be able to buy a fish.  Two days later when temperatures are back to 62° – fishing is great.

4. Now, suppose that, on the same stream, water temperatures are stable at 68° and fish are feeding well. Now we have the same two cold days and nights with hail and water drops to 62°. Go home and have some hot chocolate. There will be no bite at 62°.

5. I have caught trout with water temperatures as low as 37° and as high as 74°. That’s quite a range! The key is how fast and in what direction the temperature moves.

6. Freestone streams have radical temperature changes over very short periods of time, thus one reason for the more inconsistent fishing. Tailwaters and spring creeks have very small temperature movements, thus the more consistent feeding.

7. 68° is moving towards the high end of a trout’s tolerance. Anything above 70° is very stressful for the fish and I seldom fish at those temperatures so as not to damage the fish.  Montana closes rivers at 70°.

8. Bigger fish are more sensitive than smaller fish to temperature swings and to warm temperatures.

CONCLUSION: If you want to know when fishing is likely to be good or not so good, carry a thermometer and watch for the water temperatures changes. The examples listed in numbers 4 and 5 above, waiting until afternoon it would be a wise decision. If you must fish in those conditions, you need very narrowcasting lanes and slow-moving flies. Fish will not move far or fast for a fly.