- Associated Press - Sunday, June 22, 2014

HEBGEN LAKE, Mont. (AP) - The first time I heard the swelling crescendo by the lakeshore I thought it was an airplane nearing overhead. It took a moment to realize the buzz was emanating from thousands upon thousands of midges - tiny insects that hatch in huge numbers on Hebgen Lake.

And then a breeze came through the timber and the air was silent again.

“You hear that sound early in the season, and it is already waning,” Josh Duchateau, head fishing guide at the lakeside Firehole Ranch, said recently. “The conditions were just perfect for (a big midge hatch) this year - temperatures in the 70s and calm days.”

Hebgen Lake, just outside West Yellowstone on the border of Yellowstone National Park, is quite a bug factory. And all those insects provide a food base for a robust trout fishery. As soon as the ice comes off the lake in the spring, brown and rainbow trout cruise the surface looking for a meal.

Duchateau said the term “gulper fishing” comes from the sound the fish make as they feed - the steady gulp, gulp, gulp of a consistently rising fish.

“Those trout will travel in pods,” Duchateau said. “In the evenings I have seen some incredible things. I have seen 40 to 50 fish coming at my boat and basically I can just close my eyes and cast, but that is a special, special thing.”

When the magic happens the gulper fishing on Hebgen Lake can be fantastic. According to Montana Fish, Wildlife & Parks, brown and rainbow trout average 17-18 inches on the lake, with some fish growing much larger.

But conditions on Hebgen Lake don’t always make things easy for anglers. The slightest breeze can create a chop on the water that may put the fish off.

Anglers hoping to catch gulpers on Hebgen Lake should keep a close eye on the weather forecast. Focusing efforts early in the day, when bugs are hatching, and late in the day, when the wind settles down, will lead to success.

Early in the season, chironomids (midges) are a prevalent food source. Though trout regularly rise to midges, Duchateau said they don’t feed on them the same way they do another important bug on the lake - callibaetis mayflies.

“Pursuing these fish on a chironomid is difficult, because they don’t track the way they do on a callibaetis,” Duchateau said. “For midges, I’ll fish a Griffith’s gnat with a pheasant tail nymph or an indicator with a leech pattern and a chironomid . You can literally cast a leech in front of a rising fish and they will crush it.”

At 16 miles long, Hebgen Lake is a big body of water that gives fish a lot of room to roam. The Madison and Grayling arms are well known among gulper fishers, and for good reason.

Duchateau said nutrient-rich geyser basins upstream in Yellowstone National Park influence the Madison Arm. Shallow inlets and bays in both the Madison and Grayling arms shelter weed beds that provide oxygen and a food base for bugs and fish alike.

Peter Scorzetti, of Blue Ribbon Flies in West Yellowstone, said callibaetis hatch in huge numbers on the Madison Arm in August.

“There are so many bugs that the fish get selective and leader shy,” Scorzetti said. “Something about the ecosystem is right for callibaetis and it makes for some really prolific emergences. The gulpers can be crazy.”

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