Montana Springtime Fly Fishing: Discerning Hatches – Fins and Feathers Bozeman
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Montana Springtime Fly Fishing: Discerning Hatches

When there are multiple hatches happening at once, it can be tricky determining which type of insect the trout are feeding on. Here's a general overview of rise forms as it relates to springtime fishing.

We stood ankle deep in the Gallatin River. Twenty-five feet upstream a pod of six fish were rising on the inside seam. In the eddy to our right, BWOs, March Browns and midges swirled. We'd seen a couple skwalla stoneflies earlier in the day. Now, we had a decision to make: which fly do we tie on?

The fish were rising consistently, slowly exposing their nose, dorsal fin and tail. This told us they were eating adults floating on the surface. We ruled out the stoneflies, since there weren't that many around. Plus, stonefly eats are normally more aggressive and inconsistent.

Midge dries would be the last thing we tried, mostly because they are tiny and hard to see and fish. Plus, there were two other, and larger, food sources drifting through their feeding lanes.

Now we had two options -- BWOs or March Browns. Both are mayflies that slowly emerge in cloudy weather, so the rise forms would be similar. There were more BWOs out, but the March Browns offer a larger meal. They were about a size 12 vs. the size 18 Baetis that were coming off.

Montana Fly Fishing BWO

We started big and cast a size 12 Purple Haze, landing it a few feet above the nearest fish. He ate it, as did three others. We moved along to the next spot in search of more risers, happy that we made the right decision.

Now, if after a couple good drifts that mayfly imitation didn't get chomped, we would've changed flies and put on a size 18 Parachute Adams to try to match the BWOs that were hatching. And if that still didn't work we would've tried a midge imitation. We got lucky that the fish were keyed into the large mayflies. It was so much fun not having to squint to see a tiny dry fly dancing in the current.

In a couple weeks, the water temperatures will rise and we will have another insect species to deal with -- caddisflies. Caddis quickly ascend from the bottom of the river to the surface and fly away. This makes the fish chase them resulting in splashy rises near the surface. Sometimes the trout will even launch into the air chasing caddis. So, if you see this type of activity tie on a caddis dry fly or emerger.

While matching the springtime hatches I like to fish a slightly softer four or five weight rod. On the Gallatin we were fishing a five-weight Orvis 3F with a Rio Technical Trout fly line. The Scientific Anglers Trout taper is also a great dry fly line. These lines tend to land softer than their heavier counterparts, like the SA MPX or Rio Grand, which are great lines for nymphing or throwing larger dries.

We fished a 9-foot 4x leader. There is generally no need to fish smaller tippet in the spring, because the trout are less educated and the water normally has some color to it. Sometimes in the low, clear water of the fall I'll go to 5x and extend my leader, but even that is rare.

I'll always carry a floatant and some type of dry shake to help keep my fly floating throughout the hatch.

Stop by our Bozeman Fly Shop for advice, flies and gear to help you trick the trout during these pre-runoff hatches. It's one of my favorite times of the year to fish.