Few events in fly fishing match the annual and reliable penonmenon of the Madison River Salmon Fly Hatch. We're talking about Pteronarcys californica, the pinnacle of aquatic insects that trout in Montana go absolutely bonkers over. Madison River trout eat Salmon Fly nymphs 365 days a year, but for only a couple weeks in June do they have a chance at devouring these gigantic bugs in their adult form. This is the time of the year when the biggest fish in the river look to the surface for the trout's equivelant to a 5-Star Wagyu Rib Eye buffet.
Salmonflies can be found in river ecosystems across Canada, The Rocky Mountains, and as far west as California. These aquatic insects spend 3 years in the nymphal stage before emerging as winged adults. An aquatic insect population sample can clearly show the different generations of nymphs that are conveniently 1, 2 and 3 inches long. A dominance of 3 inchers in a population sample potentially indicates a big hatch year, but generational variance can be expected along the entire stretch of a river.
Salmonfly nymphs spend most of their day wedged between and underneath rocks along the river bottom. Salmon flies are detritivorous insects and when not in hiding, they can be found clinging and crawling on the rocks as they forage on decaying plant material. This when they are most vulnerable to predation by trout. Rather than emerging upward through the water coloumn like caddis and mayflies, the 3-year olds begin their morph into adulthood by migrating to the edges of the river, where they then crawl out onto dry rocks and vegetation adjacent to the river bank. This is the best time to throw large stonefly nymph patterns at trout that are readily targeting the migrating nymphs. Flies like the Pat's Rubberlegs, Delektable Mega Prince and the 20 incher perform well throughout the hatch. Once out of the water, the sun dries out their exoskeleton and a winged adult emerges. During the hatch, anglers can walk the river banks and find the shoreline littered with exoskeletons, or "shucks", as they are more commonly referred to by anglers.
The adult male salmonflies begin the reproduction process by "drumming" the rocks in an attempt to attract females. Ovipositing females carry eggs on the posterior end of the abdomen and will drop their eggs near the surface of the water so that they sink to the bottom of the river for development. It is thought that the female salmonfly is primarily responsible for triggering a trout's response to feed on the surface. The females are not graceful fliers and they will either accidently clip the water, or get blown off course by a sudden gust of wind. The result is a crash landing on the surface of the water and an unfortunate demise for the salmonfly.
The Salmonfly hatch can be difficult to predict, but if you happen to find yourself in the thick of it, get ready for some epic dry fly fishing. The hatch will begin in the lower section of the river and gradually move up river. It's no suprise that many, many obsessed anglers follow suit, throwing bulky foam imitations in the direction of rising trout. On occasion, the dry fly fishing can be tough when fishing in the most intense hatches. Usually the fish are either full, over pressured or not impressed by our imitations. This is a great time to throw streamers, nymphs or large caddis dries at them. Rather than fishing in the center of the hatch, it is common for experienced anglers to fish ahead or behind the hatch in an attempt to find hungry, less pressured fish. This is when a knowledgable Madison River Fishing guide plays a big role in finding the best fishing.
If you are interested in experiencing the great Salmon Fly hatch on the Madison River, you better plan ahead as we book up fast. Check out our Fly Fishing Trips page for more info.