By Patrick Straub explorebigsky.com Fishing Columnist

The next few weeks are a happy time for most area fly shops. Phones are ringing, summer inventory arrives daily, and folks out fishing tend to buy more flies than in high summer. Translation: they tend to lose more flies!

The Gallatin River is priming for the salmon fly hatch, when trout gorge themselves on the river’s largest post-runoff aquatic insect. The salmon fly – aka Pteronarcys californica for those with overly refined pallets – is a giant bug on the minds of any Montana fly fisher for the next several weeks.

Because these insects hatch near bank-side structures, it is imperative to fish near the banks. This doesn’t necessarily mean you have to change your game entirely, just make a few tweaks here and there.

I can cast a 100 feet. Do I need to?

As a young angler, I was obsessed with casting 100 feet of fly line. My brother Carl was a born distance-caster, and his fly would always land a leader’s length beyond mine. So I learned to study the water closer to where I stood, quickly finding that there’s always fish to ply within 40 feet or less from where I waded.

As a guide, it’s always nice to have a “hucker” in the boat, someone who can really air it out, but the folks who catch the most fish cast 40-50 feet with accuracy and manage their lines diligently. Whether guiding or fishing on my own, I’ll take a precise 40-foot cast over an in-the-ballpark 100-foot cast any day.

Join the buffet line. Follow the food source, and you’ll find more fish.

In morning hours, trout congregate beneath overhanging willows and near bankside structures to catch the migration of stonefly nymphs, which make their way from mid-stream boulders to banks in order to climb ashore and hatch. Later in the day, trout will seek out eddies where the dead or crippled bugs are still swirling around. The old saying, “fish where the fish are” should be modified: “fish where the food is, and the fish will be there.”

Go big or go home (or to your local fly shop). Increase your tippet strength and your fly size.

Trout hang out along the banks to access food but also take refuge there because the banks provide safety from predators and offer a break in the post-runoff currents. Although rocks, trees and other fly-snagging nastiness are ideal for trout, they translate into snags and lost flies. You’re going to lose flies, but you’ll lose fewer if you fish a heavier pound-test tippet. I rarely fish anything lighter than 2X while pre-hatch nymph fishing. I also ensure my knots are properly tied and my tippet isn’t old. Now might be a good time to restock your tippet as the stuff deteriorates with age.

As for fly selection, bump up a size or two from what you think is large enough. Salmon and stonefly nymphs are large and in the fast water of the Gallatin you’ll need a fly that sparks a trout’s interest. Hook sizes 2, 4, and 6 are common sellers this time of year. When you snag a stick, a larger hook tied on a stout tippet stands a better chance of dislodging the stick than breaking off. And the larger hook might mean you land that pig brown trout, even in the heavy currents of runoff.

The next few weeks serve up some of the season’s most exhilarating fishing. Rivers are in post-runoff and large insect hatches are the norm. Your fishing mindset doesn’t need a total overhaul, just a slight tune-up.

Pat Straub is the author of six books, including The Frugal Fly Fisher, Montana On The Fly, and the forthcoming Everything You Always Wanted to Know About Fly Fishing* *but were afraid to ask. He and his wife own Gallatin River Guides in Big Sky.