Salmonfly: The Giant Stonefly Hatch That Moves Upstream

Description

The Salmonfly (Pteronarcys californica) is the "main event" of the western fly fishing calendar. These are prehistoric giants—up to 3 inches long—that represent the largest meal a trout will eat all year (short of another fish). The hatch is more like a festival; seeing millions of orange-bodied giants fluttering around while 20-inch brown trout engorge themselves is a bucket-list experience. They are unmistakable: giant, dark bodies with a fiery orange thorax/abdomen band.

Life Cycle Stages

Nymph

The nymph is a beast. Sizes #4-8. They have a dark brown/black appearance with robust legs and antennae. They live in the fastest water for 3-4 years before hatching. The Migration: This is the key. 3-5 days before the hatch, the nymphs migrate en masse from mid-river to the banks. Nymph fishing 2 feet from the shore is often better than fishing the middle.

Recommended Fly Patterns

Atomic Stone

#6-#12

Dark Olive, Black, Brown

Bitch Creek

#6-#12

Brown, Black, Orange, Yellow

Pat's Rubber Legs

#6-#12

Black, Brown, Coffee, Coffee/Black, Dark Olive/Black, Olive/Brown, Yellow/Brown

Prince Nymph

#12-#18

Peacock, Brown, White, Gold

Twenty Incher

#6-#12

Brown, Black

Kaufmann's Stone

#4-#10

Golden, Brown, Black

Emergence

They crawl out of the water at night or early morning onto dry rocks, logs, and willows. You will see fresh "shucks" (empty skins) covering the riverside vegetation.

Adult

The adult has a dark grey/black wing folded flat and a prominent orange/red underbody. They are clumsy, heavy fliers. They spend days mating in the willows before females return to the water to drop eggs.

Recommended Fly Patterns

Water Walker

#6-#12

Golden, Orange, Olive, Black

64 Impala

#4-#6

Orange, Brown

Grillos' Dancin' Ricky

#4-#8

Orange, Black

Sofa Pillow

#4-#10

Orange/Brown

Salmonfly Adult

#4-#10

Black, Brown, Orange

Chubby Chernobyl

#6-#14

Tan, Gold, Olive, Purple, Black, Yellow

Stimulator

#6-#14

Orange, Yellow, Olive, Tan

Madam X

#8-#14

Yellow, Olive, Tan, Brown

Habitat

Salmonflies are picky. They require large, cold, high-gradient rivers with stable, giant boulder substrates. They need highly oxygenated, turbulent "white water" to survive. This is why famous Salmonfly rivers (the Madison, Big Hole, Gunnison, Colorado) are often large, powerful freestones or tailwaters with canyon sections.

Behavior

The hatch moves upstream. On a river like the Gunnison or Madison, the "head" of the hatch might travel 2-5 miles per day.

The Gorge: Trout eat so many salmonflies they literally get full. The best fishing is often in front of the hatch (nymphs) or just behind the main swarm (when fish are hungry again but looking up).
Egg Laying: Females crash onto the water to release eggs. It is not graceful. A loud landing is a dinner bell.

Fishing Information

Seasonality Late May through early July, depending on latitude and elevation.

Tactics

Tight to the Banks: Throw your dry fly inches from the grass/willows. That's where the bugs fall in.
Heavy Tippet: Use 2x or 3x. These flies are big and wind-resistant, and the fish are not tippet shy during the blitz.
The Splat: Don't lay it down gently. Smack the fly on the water.
Movement: Twitch the fly. A drowning Salmonfly flutters its huge wings.
Double Dry: Fish a Salmonfly with a Golden Stone or Caddis trailer.

Recommended Patterns

Nymph: Pat's Rubber Legs (Black/Brown), 20-Incher, Kaufmann's Stone.
Adult: Chubby Chernobyl (Orange/Gold), Rogue Foam Stone, Stimulator (Orange), Sofa Pillow.

Conservation Status

Very High Sensitivity. Salmonflies have disappeared from several historic ranges (e.g., parts of the Logan River, lower Provo) due to warming water, sedimentation, and pollution. They are the ultimate indicator of a pristine, high-gradient river ecosystem.