With cooler temps and changing leaves it is my favorite time of the year to be on the water, and casting for smallmouth during this season is incredibly fun. As water temperatures begin to dip into the lower sixties the smallmouth start to cycle into a migratory behavior. This behavior is brought on by a need to find over-wintering locations in the river in order to survive the upcoming winter months. While stretches of the river may become vacant of bass, the good news is that they are still feeding and when you find where they are it can be exciting hooking into a number of them.
So where do the bass go and how far do they travel? It depends on the size and structure of the river you are fishing. But by and large smallmouth are looking for spots that have more depth and slower current than other stretches of the river. A decent amount of underwater structure is also key. When ice begins forming on the river these areas will help to keep bass alive.
Those shallow riffled runs that had back eddies or deep pockets nearby may not be sufficient for bass anymore. So it is key to begin searching the river for these new areas, and it may take some time to explore a river if you have never fished it in the fall.
Once you find a location with smallmouth it is now time to decide what flies to cast, and how to present them. A quick note on casting into these spots: If you find a location that has bass then do not blast a cast as far as you can to hit some distant target. Rather, fish close and then work your way out. You will spook fewer fish this way and waste less time double-hauling only to wear yourself out.
A slow retrieve is really important. While bass are still feeding, especially the larger ones, they still need to pick and choose their food in order to not waste precious energy pursuing some fleeing prey. Dropping your fly on target, getting tight to it immediately, and then retrieving at a slow rate with some pauses will entice the bass. If they pursue the fly but do not bite then pause and twitch the fly, or give it a chance to fall as bass seem to strike when the fly behaves this way.
Baitfish fly patterns, both weighted and unweighted, work great during autumn. Crawfish patterns work as well but crawfish in general become less and less active with the cooler water temps and are not as available to bass. However, if you think the bass might be hugging the bottom then it is definitely worth using a heavy crawfish to get down to where they are and then jigging it along the riverbed.
When starting the day out, I will first try using a floating line with an unweighted or lightly weighted streamer. This allows me to cast into the shallow areas and then strip the fly right over a shelf. If there are bass waiting in the depths below then it can produce some exciting strikes. Another great spot to try this is where there is some underwater structure, like boulders and logs, and slowly stripping an unweighted streamer over top.
Lastly, the time of day to go out and try this does not need to be at first or last light. Late morning to mid-afternoon is typically when the water will warm a few degrees and get the bass into a feeding mode. In fact, picking a day that has a bump in air temperature after a few colder days can be a very productive outing.