Montana Woods N Water June 2016 Print Edition | Page 22

FLY FISHING

Finding and Fishing the Salmonfly
Hatch, and a Caution By Chuck Stranahan
On many western Montana rivers the salmonfly hatch is underway. There have been
sightings and sessions of good fishing on those big bugs that cause a big frenzy among
anglers every season.
They don’t arrive all-at-once. The hatch just sputters along, gradually gaining
momentum for a couple of weeks, then holds its own for a couple more, and then
gradually disappears.

Bud Lilly’s 1982 catalog featured the Fluttering
Stone salmonfly on it’s cover; that fly is still
productive today.

Take the fishing where you find it – and don’t be in a rush to join the crowds. There
are salmonflies and other bugs, and trout to eat them, in places that don’t get hit that
hard or that often.
Typically on many rivers the hatch moves upstream at a predictable rate. A river tends
to warm as it moves downstream. The salmonfly nymphs begin their migration to
shore when the water temperature is at about 50 degrees.

So far so good, but that water temperature can fluctuate. You might find changes of several degrees if you drop your thermometer in the
same spot several times a day. Snowmelt, delivered to a main river by feeder streams, might drop the water temperature below that stream
mouth during spells of hot weather. It’s a cat-and-mouse, catch-22 situation.
These big bugs tend to crawl out of the river, split their nymphal shucks and crawl out, wait for blood circulation to pump up their wings,
and crawl off, at night. It’s a survival mechanism. At that, I’ve seen them do it in broad daylight. Some bugs didn’t get the message,
apparently. But spreading that hatch time out is another sort of survival mechanism: it’s as if it were designed that way.
To find where the big nymphs might be coming ashore, walk the banks of a river where they’re known to hatch and look upstream. See
where the current slows and moves to the inside of a bend. You might see the empty shucks of previously hatched bugs on the rocks or
willow stems that might, at this time of the year, stick out of the
water.
If you see active flies on the surface, and trout slurping them in,
Fish there. If there are no active bugs on the surface, fish nymphs.
Two salmonfly nymphs
Take a couple of salmonfly nymphs with you if you’re wading; one
should be heavily weighted, and the other should be fairly light.
Here’s why: in many places you’ll need that heavy nymph to
plunge down through the heavy current in the top of the water
column to get down to where the fish are.
Then there are the quiet lies where the salmonfly nymphs will
make their way to shore in relatively slow-moving water. In those
places, the trout will want to see a nymph that is drifting freely –
not plunging to the bottom. The right fly – not too heavily
weighted – is essential for a natural presentation in such places.
Forget that roaring torrent just a few feet from you – approach
cautiously, as is you were fishing a mountain meadow stream in
midsummer. Fish upstream, cast carefully, a few feet above a
suspected lie, and let your nymph drift into it as you gradually raise
your rod. If anything – anything – interrupts the flow of your
leader as it drifts back to you, quickly tighten up.
The best place to do this are at the head of the hatch, where there
are salmonflies galore in the air but no fish taking them. Why? The
action, or the best part of it, is all under the surface. Just recently
guide Chad Williams reported that the “boat horde” that attacks a
small section of local river annually was out in force, but not
scoring all that well on the surface.
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