Salmon Flies on the Henry's Fork

Craig Richardson

“Dude, it's go time. They’re starting to fly. It's going to be wild.”

It's a hatch that people from around the world dream of seeing. The Henry’s Fork salmon fly hatch is one of the pinnacles of trout fishing around the world. These oversized bugs make some of the biggest trout in Western rivers show themselves.

This year has been pretty peculiar with chaos and unrest everywhere. I was one of the few lucky people that would be able to hit the Henry’s Fork through the salmon fly hatch and possibly get to see it in all its glory.

I was getting settled back into my Idaho lifestyle when out-of-state fishing licenses we not being sold. This completely flipped my world again, knowing I could potentially not be able to fish until sometime in June. I was told “you’ll probably have to wait until the 15 th of June to get a license”. Bear in mind this was around the 5 th of May so I was pretty upset that I would have to more than a month to fish again. Luckily the governor of Idaho opened fishing to people from out of State on the 16 th of May and the bugs had not started their migration to the banks to hatch. It ended up all falling perfectly in place.

I got a call one evening from my buddy TJ Powell saying we need to be on the river in three days time. “The water is almost ready and the big bugs are getting closer to the bank.” The night before we were meant to get on the water TJ called me again, “Dude, it's go time. They’re starting to fly. It's going to be wild. Make sure your camera batteries are charged.”

We planned on meeting at 08:00 to drive up to the river. We live about forty-five minutes from the boat ramp and arrived at Ora Bridge to an absolute shit show of cars. It turned out that the information had been shared throughout the West. Utah and Montana license plates flooded the parking lot.

We knew it was going to be a somewhat busy but we didn’t expect to see around fifty cars in the parking lot. I was a little pessimistic because I’ve seen how these fish can completely shut off with too much pressure. TJ cracked a breakfast beer and told me not to worry, “these fish gotta eat man, they know they don’t have much time”.

We lifted the anchor and moved down river to try open up some space. I was up first while TJ was on the oars. He keep saying “as tight as you can get it to the bank is where you need to be at all times. Anything more than thirty centimetres from the bank is too far, you’ll only get the babies.”

On the third drift tight on a rock wall a big brown nose stuck up and sucked down my size six dry. I lifted into it and could feel it was a solid fish. I tried my best to control the fish and keep in clear of the log jam thirty yards downstream but I was not the one in control throughout that fight.

That fish completely wrecked me. It tore off down stream, jumped a coupled of times and buried me deep into the log jam.

TJ laughed it off, grabbed his rod and told me to get behind the oars. As he stood up a giant female salmon fly flew straight into his face. The fishing was about to go off. He cut back his leader and tied on some 2X - dry fly fishing with size six flies and 2X tippet? Sounds pretty ridiculous to me.

We hit a long grass bank that was crawling with bugs; caddis, salmon flies and a giant mix of mayflies all fluttering about. The fish didn’t care about any other bugs, they just wanted the massive bugs. TJ threw a long reach cast and landed the fly about five feet onto the bank, almost landing in the potato fields. He ripped it back, pulling out some grass from the bank and knocking around ten salmon flies into the water. We watched them drift down for a while and nothing came up for them.

A lone straggler about five metres above them drifted down the same lie. A giant white mouth opened up and engulfed the bug. I dropped the anchor and we planned how we were going to approach this fish.

After a pretty brief discussion TJ got out the boat and waded about twelve metres upstream of this beast and waited to see if it would rise again. Again a huge white mouth came clear out of the water and engulfed another natural. It was TJ’s time to shine.

He sent a clean cast landing the fly three metres ahead of the fish. It felt like the fly took forever to reach the fish but when it did the fish stuck its entire head out the water as ate the fly.

TJ lifted the rod and set the hook and the amount of water that fish displaced was insane. It started bucking and rolling before tearing off down stream.

TJ chased it down, falling a few times. At one stage he was completely submerged with just his rod out of the water. I grabbed the boat and rushed down to him but sadly that fish had kicked his ass - no two ways about it!

The rest of the day we drifted and threw massive dries at the bank, under trees and along rock walls. We had around twenty-five decent size fish smash the dry.

Everything in the area was trying to get a piece of the hatch and the birds were going nuts! Red tail hawks were grabbing and eating them in mid air!

It was an almost impossible drift to get and even if you hooked the fish the chances of getting it to the net were extremely slim. I was up and decided to try get a better angle by wading. I hopped out the boat and walked slightly upstream of it hoping that I could get a drift deep under the willow without drag.

My first attempt was nothing short of shocking. I managed to break off my first fly about three metres up onto the bank. I couldn’t have done worse if I tried!

I tied on a fresh fly and tippet and walked back into position, stripping some line off and laid a cast I that was very happy with. The fly drifted perfectly over the fish and I had no response.

I laid my second cast and got another great drift with no response. I changed my fly to something a little smaller and more natural and made another few casts, but this fish just wouldn’t eat it. I changed back to my first fly and layid out a pretty average cast. The fish rushed it and hammered the fly.

Somehow this fish just ran straight towards me into the open. If he had turned downstream it would’ve been game over. I was pretty surprised at how easily we got that fish to the net. It turns out it was blind in its left eye, all of my drifts but my final cast were all on its left side. It started to make a little more sense!

Sadly we didn’t get our chance to land one of the monsters the Henry’s Fork is known for but we did have our opportunity to hook two of them. This is a fishery every trout fisherman needs to experience. The sheer volume of bug life is incredible and being able to fish dry flies that big will never get old.

The Henrys Fork, also called the North Fork, is a an approximately 200km tributary of the Snake River, in southeastern Idaho in the United States. It shouldn’t be confused with the Henry’s Fork of the Green River in Utah and Wyoming.

The river is named after Andrew Henry who built Fort Henry on the upper Snake River, but who abandoned this first American fur post west of the continental divide the following spring.

The river flows south through a high plateau in northern Fremont County, through the Caribou-Targhee National Forest, and passes through Island Park Reservoir. It emerges from the reservoir and flows through a canyon that opens up into a broad, flat meadow in the Island Park Caldera in central Fremont County.

The river then flows slowly past the town of Island Park, through the Harriman State Park, otherwise known as the "Railroad Ranch", and descends swiftly as it approaches the wall of the caldera, flowing over both Upper Mesa and Lower Mesa Falls, and emerges from the mountains onto the Snake River Plain near Ashton.

Island Park Reservoir is used for irrigation in the Snake River Plain. Its drainage provides one of the most important rainbow trout fisheries in Idaho in terms of habitat, fish populations, and use by anglers. The section of the river between Henry's Lake and Big Springs is a major spawning area for trout and is closed to fishing.

Henrys Fork has long been noted for its superb fishing, especially its dry fly fishing, although conditions vary and you will need to time a trip according to your preferred method of fishing. If you enjoy using tiny dry flies then late September is a great time for your visit. If you would like to try casting big grasshoppers then August is the time to be here.

Generally, the salmon fly hatch on the Henry’s Fork starts during the last week in May. The hatch moves up river and is usually over by the end of the first week in June. You will also find pale morning duns and caddis on the slow sections.

PMD’s, blue winged olives and caddis will be prevalent on the Firehole River. The Golden Stoneflies begin to emerge shortly after the salmon fly hatch, and usually provide several weeks of good fishing opportunity in the Box Canyon and other fast water Henry’s Fork sections at this time.

The salmon fly (Pteronarcys Californica) nymph can grow up to fifty millimetres and is often the only organism in the river smaller than the fish themselves. This makes them a firm favourite of the Western flyfisher and, of course, trout. When they hatch every spring they draw anglers from all over the world.

Salmon flies require rivers that are neither too hot nor too cold in currents that are between moderate and fast. They can live underwater for up to three years so consistent conditions are critical.

When they lose their grip on the river bottom or crawl to the shore in their migration to complete their lifecycle trout will feed heavily on them. Salmon fly will move under low light as cover and will try to find reeds, rocks and tree trunks to crawl up on and out of the river. They will emerge as up to seventy millimetre adults with two pairs of wings and an orange (salmon) and black body and take flight.

The adults will find a mate and the female will return to the river to lay their eggs. At this point they are vulnerable to predation and are important to trout anglers. This is one time of the year when big, wise adult fish will move to take the helpless natural from the surface.

If fishing for huge rising trout with size six dry flies is your thing then this is the hatch for you.

In a cruel irony of the natural world trout will often consume so many of these monstrous insects that they take three to four days to digest them and during this time, despite the hatch continuing, they become difficult to catch. The hatch is notoriously difficult to time and many guides suggest waiting a few days for the hatch to end and then fishing with salmon fly imitations while the memory of the natural is fresh in the trout’s mind.