Now in the peak of summer it is time once again to do the trout a favor and discuss water temperature and how it relates to trout and specifically trout fishing. Remember, not the air temperature but the water temperature is what we are discussing. It is a well known fact that water temperature has a big impact on trout’s metabolism. The higher the temperature above their comfort zone the more they are stressed.
Alan Peak at Rocky Mountain Fly Fishing Guide has obviously put a lot of thought and effort into producing a diagram to act as a guide to help understand the effects of water temperature.
As with most general rules there are factors that affect the normal. For instance, the major variable is the amount of oxygenated water. Some streams as well as some areas of streams have more oxygenated water than others. The oxygen content is the problem not directly the temperature. The water temperature is indirectly responsible since oxygen content is inversely proportionally to water temperature. Also, fast flowing water that tumbles will have more dissolved oxygen.
Another factor to consider is the amount of stress caused by hooking, landing and handling the trout. Do not overplay the trout but land them as quickly as possible. This means that light rigs are more appropriate. Do not keep them out of the water or better yet, keep them under the water as you remove the hook. Alan’s graph below gives the basics.