October Fly Fishing Tips: Go Big or Go Small

A lower Madison River brown trout. Courtesy Brian McGeehan.

In many trout fishing locations around the country, October represents the last opportunity to target active trout before winter sets in. Late season fishing often produces some of the best opportunities of the year to hook up on some monster trout.

Dry fly fishing over fall hatches can also be outstanding and usually represents the last wave of good surface activity until midge hatches commence in the early spring. The added bonus of fishing in autumn is that many destination fisheries receive very little angling pressure. As a Montana fly fishing outfitter, I am always amazed at how few people are on the water during the month of October.

We strongly encourage our guests to try an October trip to enjoy the empty rivers and have a great shot at large trout. Many of our guides have found that going really big or really small with fly selection can be the key to success.

Going big!

Brown trout are fall spawners and begin moving upriver in October. Most browns spawn in November or December based on latitude and water temperatures. Large brown trout become much more aggressive in the fall and sometimes move out of larger rivers or reservoirs into waters that provide better access to fly fisherman.

In Montana and many other parts of the country, anglers target lake run browns that move out of reservoirs or natural lakes and into rivers. Large browns are notorious for being carnivores and enjoying a large meal. During the summer months, most of the monster browns feed in the middle of the night and are rarely caught.

In the fall the fish are again most active during the day. Many “hog hunters” fish large articulated streamers exclusively in the fall months. As the temperature continues to drop it is best to slow down the strip retrieve when pulling streamers. A sink tip line can be a handy accessory when fishing bigger rivers to target the deeper main runs.

If continuously throwing giant 6-10” streamers begins to take a toll on your elbow, try switching to a nymphing rig with a large streamer such as a zonker or sculpin pattern as the top fly. Let the nymphs swing off the bottom at the end of the drift and hold on! Nymphing a large streamer is often just as deadly as stripping one. Although pulling massive amounts of bunny fur around your favorite brown trout river doesn’t always result in big numbers it will result in some of the largest trout of the season.

Go Small

Once October arrives, the dominant insect species available to trout across much of the country are the mayflies of the baetis genus. These small aquatic insects are frequently referred to as blue winged olives and are best imitated with a size 18-20 hook.

On most fisheries, the hatch is a daily occurrence in the early afternoon. Cloudy days and wet weather often produce hatches that are dramatically more intense than on sunny days and will often trigger intense surface action from trout. On sunny days the hatch will be much more sporadic but will still generate interest from the fish. During sporadic hatches search out back eddies and foam lines for trout feeding on the surface.

These eddies often concentrate floating material that includes stillborn duns and will often hold the only trout in the river that are actively feeding on top. Nymphing during a sporadic hatch is often very effective and trailing a larger streamer with one of the many different blue-winged olive nymphs can be very effective. A small size 18 or 20 pheasant tail is a great choice during the BWO hatch, but we also have a lot of success fishing a BWO emerger pattern with a short wing as a nymph. Targeting trout feeding on baetis mayflies can often produce dependable fast action in the month of October.

Brian McGeehan is a Montana fly fishing guide and owner of Montana Angler Fly Fishing.