As we enter the season of "many hatches" its important to keep in mind that the "whats biting" question varies from one place to another. This is due to a number of different reasons such as; aquatic environment (tailwater, stillwater, freestone, spring creek & etc), time of year, and temperature.When heading out to the river it is always a good idea to not only do your research beforehand, but carry a thermometer as well to note any temperature fluctuations affecting aquatic hatches and trout feeding behaviors.
Below is a list of the "optimal" temperatures of the main hatches we see around the southwest Montana area. These temperatures temd to fluctuate a few degrees here and there. Another thing to note is that time of year plays an influential role in the hatches, when the water has reached the specific "hatching" temperature, the hatch "runs through itself", therefore when it is done it does not come back that season. BWO's and certain midges are the only exception to this.
33 (F)- Minimal temperature for midge hatches
40 -Minimal Baetis hatch
40-44 - Lower end of optimal trout fishing (species dependant)
42 -Lower end of Sqwala hatch temps
42-46 -Optimal temp for chironomid hatches
42-47 -March Browns
50 -Optimal median temp for streamer fishing
-Beginning of Brown Drakes
- Lower end of crayfish activity
- Optimal temp for Cutthroat spawn
56 - Upper end of Baetis Hatches
- Caddis Hatch temps
- Trico hatch temperatures ( with a morning air temp of roughly 68F)
56-60 -Optimal for Salmonfly, Yellow Sallies and Goldenstones
58-60 -Optimal PMD temp
60 -Lower end of Damselflies
65-70 -Temperature at which trout become stressed and you consider not fishing for them.
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