.......................  ....................  ...Fly Fishing Yellowstone National Park
06/05/12
New KISS Bug Series - Part 38

Salmonfly
Nymph










When it comes to fishing the Salmonfly hatch, most anglers immediately envision large trout coming up and
eating full grown adult salmonflies from the surface of the water. Such thoughts are reasonable and at
some point in time during the hatch, that is usually the case; however, for one to think of the Salmonfly
hatch as only a dry fly fishing opportunity will only results in less action than the hatch could provide. Trout
eat a heck of a lot more Salmonfly nymphs during the hatch than they eat Salmonfly egg laying adult
females.

Although it isn't necessarily true inside Yellowstone National Park, some streams have such large Salmonfly
hatches that the trout become stuffed or gorged on the stonefly nymphs to the point they have little interest
in eating the egg laying adults. That happens on the Madison River outside the park frequently. There are
so many of the large stonefly nymphs crawling to the banks to hatch in some sections of the river that the
trout simply get their bellies full. The lag in action is usually only temporary. Just hang around a day or two
and you will usually find out things change and trout eat the egg laying adults like they are starving to
death. The point I want to make is that if you ignore fishing imitations of the nymphs during the early part of
the Salmonfly hatch, you may be missing the most of the action the hatch has the capability of providing.

Salmonfly nymphs are huge. It doesn’t take many of them to interest the trout to the point they become
selective in feeding on them. When the hatch is taking place, in clear water you can usually spot them
moving across the bottom of the stream. Like most all stoneflies, the Salmonflies crawl out on the banks
and rocks to hatch into adults. Most of this activity takes place during the evenings but some hatch during
the day, especially if it's late in the day or early in the morning. Overcast, rainy days usually provides good
nymph fishing but that's not a requirement. Trout can be taken to some extent all day long on imitations of
the nymphs, especially during large hatches. Trout get accustomed to seeing them and feeding on them
and seem to accept imitations presented anytime, day or night.

The weight of your imitation is very important. It should be heavy enough to stay on the bottom. Using
added weight helps but the fly itself should be weighted at least to some extent. Remember the non-toxic
rule for the park. You can easily find the large nymphs by picking up the stones on the bottom. They are
usually mixed in with other caddisfly and mayfly nymphs. Although they look like they could bite you, they
don’t.

When the Salmonflies are hatching, you can always find their shucks along the banks. If you examine the
bushes along the banks of the stream you will most always be able to find the adults. They live a relatively
long time out of the water and are easy to spot due to their large size. In fact, if the hatch is prolific the
bushes will be loaded with the adult stoneflies. They are very easy to spot when they are mating.

In many streams, the hatch moves upstream sometimes as much as three to five miles a day.  This
distance strictly depends on the changes in elevations, weather and the associated water temperature. If
the weather is stable, the water temperatures are usually warmer at lower elevations than higher
elevations. As the water warms upstream, the hatch progresses upstream. Of course, a cold front can
change these conditions quickly. Very warm, unseasonable weather can speed the hatch up. Those
anglers that have never fished the Salmonfly hatch should certainly try to catch it. It is a spectacular event
to behold.
Copyright 2012 James Marsh
Salmonfly:
Species:                             
Type:                                  
Availability to trout:             
Hook Size:                          
Numbers:                            
Distribution:                        
Type of water:                    
Emergence time:                
Duration of hatch period:

pieronarcys californica species
Clinger
Excellent
20
Moderate
Isolated
Fast
Late Afternoons, mostly evenings
Short
Salmonfly Nymph