Rainbow trout are a favorite winter quarry, and where you find them, you will often find whitefish, which are also fun to catch. (Read more about catching whitefish.)
You will find trout and whitefish in similar places you find them other times of year, but in late season, they often favor deeper, slower water, although you can still catch them in riffles as well.
Also remember that while fish remain active during winter, they're still a cold-blooded animal, and they may be a little sluggish.They're unlikely to chase food, but they will take it, or a good imitation of it, when it's placed in front of them.
Whitefish school up in the fall and typically spawn in November, so where you catch one, you're likely to find more.
Tweak your techniques
Winter fishing doesn't really require any special tactics, just remember the basics of stream fishing, such as figuring out where the fish are and what they're likely to be feeding on, and adjust for the conditions.
Drifting bait or fly fishing with nymphs are often your best tactics.If you see dimples on the water, it may be fish feeding to eat insects, which will like be tiny midges or mayflies, and trout will also rise to the surface to take a dry fly.
Try different sections of the river and try to figure out where fish are holding and feeding. After you catch a fish, seek out similar water, but remember, fish may move around during the day. But where you find them one day during winter, they're likely to remain nearby, so keep those places in mind when you return.
Fly anglers should not overlook streamers. They can look like a big, easy meal when presented slowly, but don't expect trout to vigorously chase them like during summer. Even dead drifting a streamer can be effective.
Repeatedly cover likely looking water before moving on. You may be surprised that you can catch multiple fish in a fairly small area, so cast and drift (or slowly retrieve) your bait or fly numerous times before moving to the next spot.