Anglers follow the bugs to the trout

New York TimesMay 15, 2013 

— The sky was not exactly dark in a blotting-out-the-sun sense, but the salmon flies were certainly thick above central Oregon’s Lower Deschutes River. Thousands of female specimens circled 30 feet above the water’s surface, preparing to descend and drop their eggs. Occasionally, a bug would spiral slowly down to the river, flutter awkwardly on the surface, then disappear in a sudden splash.

The Deschutes’s native rainbow trout take notice of the salmon flies’ arrival among the river’s rimrock walls. And anglers do, too.

For most trout enthusiasts, dry fly fishing represents the pinnacle of the pastime. Mayflies, caddis flies and a host of other minuscule insects emerge from the river bottom and make their way to the surface. The trout, which have been feeding on the nymphal forms of the insects lower in the water column, shift their focus to the top, where the bugs float at the whim of the current. Observant anglers can identify the kind of bug that is emerging and choose a fly pattern that emulates the natural insect – matching the hatch, in their parlance – then, if all goes right, enjoy the visceral thrill of watching the trout rise and take the fly.

The challenge, at least for anglers of a certain age, is that many aquatic insects and the flies that imitate them are considerably smaller than a pinkie nail. Identifying one’s fly on the water among the many natural bugs – or tying it on the line – can be frustrating.

One reason that the salmon fly hatch brings such joy to the faithful is that these bugs can be the length of a pinkie, making them visible even to older eyes. Another is that even the wariest trout seem to throw caution to the wind when these insects appear, gorging indiscriminately.

‘Bucket-list experience’

“Guided trips for the peak of the salmon fly season on the Deschutes – from late May through mid-June – are usually booked by the beginning of March,” said Damien Nurre, co-owner of Deep Canyon Outfitters, based in Bend, Ore. “There’s a four- or five-day window during the hatch when the fish will eat almost any fly we cast. The salmon fly hatch is one of those bucket-list experiences that people plan for months in advance.”

Salmon flies (Pteronarcys californica) occur on many Western rivers: the Gunnison in Colorado, the Madison in Montana, the Henry’s Fork in Idaho, to name a few. They spend most of their existence as nymphs, encased in a black shuck and nestled in cracks and crevices in the river bottom. When the water temperature hits the low 50s in late May or June (the exact temperature and timing vary system to system), the nymphs begin their trek to shore and plant themselves on rocks, tree trunks and any place else that they can.

Ranging from two to three inches in length with an even longer wingspan and a telltale orange abdomen, salmon flies represent a significant source of protein; on many river systems, they are the biggest bug the trout will see. During this time, the wind that may sometimes dog the fly that anglers cast can become a friend, blowing the hapless bugs into the water. It is then – and when the females return to the water to deposit their eggs – that the top-water feeding bacchanalia begins.

A feeding frenzy

“In a river like the Deschutes, salmon flies are a major food source,” said Rick Hafele, a writer and aquatic biologist formerly with Oregon’s Department of Environmental Quality. “Because the salmon fly hatches occur so consistently and there are thousands of bugs emerging at once, the trout key on them. I’ve hooked fish that had salmon flies spilling out of their mouths, but they still took my fly. Their stomachs were distended, hard as a rock.”

At the height of the salmon fly hatch, many Deschutes rainbows move up against the river’s banks to wait for insects to drop off overhanging branches. This can make for some tricky casting, though the fish are not particular about delicate presentations.

“I like to position anglers downstream from alder trees, where salmon flies are fluttering about,” Nurre said. “You want to get the fly as far under the branches as possible, as that’s where the fish are waiting for the bugs. It doesn’t hurt to slap the fly down, as the natural bugs don’t land gently. We use short, stout leaders, so you can yank the fly out of the branches if you hang up.

“There’s a lot of variation in how the trout take the fly. If the current is slower, the fish will come up and inspect the fly. If they’re satisfied, they’ll suck it down. If the water is moving faster, the takes are more splashy and aggressive, as the fish have less time to make a decision.”

The salmon fly hatch has inspired many notable fly patterns over the years. Early flies, like the Sofa Pillow and the Stimulator, relied on hackle (cock feathers) and elk hair to keep them afloat.

“With the traditional patterns, I found that my clients were spending half their time false-casting to dry them off,” said Jason Yeager, a commercial fly tier who also guides on the Gunnison. “That’s time the fly isn’t in the water, fishing. I started experimenting with foam. Some didn’t think the foam-bodied flies would be effective, but they have a realistic silhouette and float well, even in the rapids.”

One of the more popular patterns on the Deschutes is called the Chubby Chernobyl, a mostly foam fly that bears no clear resemblance to the insect.

“It shouldn’t work,” Nurre said. “But it does.”

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