For most of us the salmon fly hatch is the main event on the annual Montana fly-fishing calendar — period, end of discussion. For example, as word spreads the Big Hole version is indeed imminent, anglers from all over come out the proverbial woodwork; a sort of whirlwind, mob-like affair more in line with rock concerts than mere insect hatches. Proof: the front page headline of Montana Standard (Butte) Sunday edition reads: SALMON FLY HITS BIGHOLE. That afternoon I count over 60 rigs at a boat launch where less than a dozen sat the previous afternoon. Weeks prior to the big bugs’ earliest-ever appearance, fly shop phones start ringing, panting callers desperate to hear the magic refrain, “Yep, best drag butt or you’ll miss it, sure.”
The attraction is the possibility (real, imagined; no matter) of hooking the “trout of lifetime.” Such as the 35-inch, 20-plus-pound monster brown trout Butte’s Bob Kingston landed during the 2009 Big Hole blitz. In case you are interested, Kingston caught the beast using a 5-weight rod, pitching two salmon fly nymphs “right by the bank and he gobbled it up.” (Good plan, by the way.) Rational thinking individuals realize the odds of catching such a fish are off the charts, but then, as we all know, not many of us are capable of such thinking, so … .
WHAT ARE THEY?
The salmon fly is largest member of the aquatic insect family we call stone fly. At 2- to 3-inches long, food value-wise perhaps only the biggest, juiciest grasshoppers compare among insects. Unlike many aquatic insects that mature in about a year, the salmon fly matures in 2-3 years. The larval stage — nymph — possesses rudimentary (undeveloped) gills, and thus requires copious amounts of oxygen. Clean gravel and heavy water help to nurture, even speed up, the maturation process. Lousy swimmers, several days to a week or more prior to hatching, the nymphs crawl to the banks, up onto the nearest structure — rock, stick, bush, tree, tall grass stem, what have you — whereupon the skin (exoskeleton) splits, the adult crawls out and, just as feeble on the wing, flutters and/or crawls to a higher perch. In due time, mating takes place. Ever-clumsy, lovers often fall off, a faux pas trout seldom miss. Mated, the female flutters out over the river and, following repeated crash landings, dispenses eggs and dies; males simply die where they are and eventually fall into the river or are snatched up by ever-present, opportunistic birds.
MAKING AN ENTRANCE
Conventional wisdom is the hatch starts downriver and moves up. How far down and up depends and varies considerably year to year. The accepted average is 5-7 miles per day. Why the variation? I don’t know. But, except for those times the hatch just explodes bugs everywhere all at once, it moves upstream over a period of days or even weeks, so you have plenty of time to get with the program. Fishermen being, well, fishermen, we all have our pet theories how best to proceed — chase the peak, stay ahead of the hatch, lay back and pick up the leavings or ignore the hatch altogether and go somewhere quieter. One time or another, all seem to have merit.
Drifting big stone fly nymphs in fast water is rarely a bad idea. Thus, my go-to rig is two big stone fly nymphs, tied on short, 4-inch droppers, 18-inches or so apart, depth and weight adjusted accordingly. Should that fail, I replace one stone fly nymph with a San Juan Worm or, based on the theory salmon flies aren’t the only game in town, rig a big stone and a smaller nymph or even two smaller nymphs; PT, Hare’s ear, Copper John, Prince, etc. can be deadly. For no other reason other than I like to cover all my bases, I often rig one guest with nymphs and the other with whatever dry stone fly pattern is hot. You never know unless you try it. This is, after all, fishing.
If I could somehow get the bugs and fish to cooperate, for me the salmon fly blitz would be one big dry-fly fest. There would be bugs in the air all day long and we’d pitch size 4 dries until our arms drop off or darkness falls, whichever comes first. Who among us doesn’t thrill to the sight and sound of a big ol’ trout smashing a big ol’ dry to smithereens? Alas, absent flying naturals, dries work only sporadically at best, at worst not at all. For the purists in the crowd the best advice I know is to remain flexible, be ready to hit the river or meet your guide at a moment’s notice. Generally not much happens until the air warms up. High, even muddy, water has little effect on egg-laying flights, but nasty weather — forget it. If I were to pick one time period it would be late afternoon to early evening, while bearing in mind all of this is way more crap shoot than science.