As we are getting into the full swing of fall here in the Midwest temperatures have really started to change. We have been experiencing that roller-coaster ride of the typical Midwest fall, one day it's 70 degrees and the next it's 40, but how does this effect the fish? Since fish are cold blooded the changes in temps can dramatically change their behavior, you can bet if the temperature changes your behavior (stocking cap, coat, gloves) it is going to really change the fish's daily routine. By routine/behavior I mean when and what the fish eat, where they hold, and their activity.
As the temperatures begin to fall you can expect the fish will start slowing down and conserving more energy to prepare of the winter and if your in an area where there are brown and brooke trout they will start preparing for the spawn. How does a fish conserve energy? They start moving out the faster runs and become opportunistic feeders. In the fall when water temps drop around the 50 degrees mark expect the trout to be in the slower runs, riffles, and hanging out on the seems. They gradually start moving into slow water as the temps continue to drop. Think of the seems as a living room attached to a dining room. They will hang out in the slower seem (the living room) until they see something worthy of eating and they will slide over to the faster water (dining room) to eat. Pounding the seems with nymphs this time of year my be the most effective method of fishing. I really like fishing nymphs with a soft hackle collar and sometimes even twitching it along the seem to pull that fish out of the living room and making him eat. By staying out of the fast current and only moving into it to eat helps conserve energy.
When the water really starts cooling off and gets around the 40 degree mark, start looking for the fish in the slow runs, seems, and deep pools. Nymphs fished deep and small streamers slowly retrieved are typically the most successful methods of fishing during this time of year. Look for springs where more consistent temperated water is flowing. This is also when our wild trout in Missouri begin the spawn activity. I've noticed for most of our wild streams the majority of the spawning activity starts in December and continues through February. Our streams do not close for the spawn and if you're going to fish stay out of the water as much as possible, be aware of the redds. Also be able to identify a redd. The areas most likely to contain redds are the shallow, gravel tail outs, below a run or pool. These fisheries are dependent on the success of the spawn so please respect them, because in the end it will effect you. There are plenty of good fisheries to hit during this time, that do not depend on the spawn.
Bundle up and hit some water, Taneycomo, The White, and the Niangua are all great winter fisheries.