As fly
anglers, we all look forward to dry fly opportunities. It truly is the epitome
of fly fishing, and why I relocated from Graeagle to Nevada City to be able to
fish and guide the best winter dry fly fishery in the state – The Lower Yuba
River. After spending 27 years living above 5,000 feet with 6 of those years at
10,000 feet, I can truly appreciate the milder temps of the foothills of the
Sierra. The Lower Yuba River is well known for its winter hatches, where BWOs,
PMDs, and Brown Duns make a daily appearance along with a special stonefly too.
Enter the Skwala. Unlike a tiny winter stonefly, the Skwala is much larger and
the first big meal of the new year for trout. It’s an overrated hatch for sure
with promises of stellar action on the surface, but to me it is one of the most
intriguing hatches that grace our tail waters and freestone river systems of
the Northern Sierra.
This
family of stonefly, Perlodidae, is
same as the Yellow Sally stonefly, and a very important species inhabiting most
watersheds in the North American continent. They are often mistaken for early
instars of Perlidae (Golden Stones),
which they closely resemble. The most notable differences between the two
families are the perlodids have much longer tails and antennae, and usually a
more slender appearance.
The male
Skwala is much smaller than the female at 13-15mm, and the female, a robust
18-22mm size that is a requirement to be able to carry the hundreds of eggs she
will be ovipositting as an adult. The color of the nymph is a yellow/olive with
hints of brown for camouflaging. They live beneath the surface for 2 to 3 years
molting into several new instars as they grow before reaching maturity. The
adult’s color differs from when it is first hatched, to near the end of its life.
A freshly hatched Skwala on the LYR will be a brighter yellow/olive, and as it
ages, it ripens like a banana and takes on the color of golden spicy mustard. The
wings of the Skwala stone are mostly clear with a smokey tinge, and
thickly veined. On the Truckee River, the color of a Skwala adult is a true olive
and more typical of Skwala populations that reside in the West. A stonefly can
live a long time for an aquatic insect, up to 2 months as it can eat and drink
water, unlike a mayfly with its 24 hour life expectancy.
Skwala
nymphs are predaceous and will eat smaller mayfly nymphs, free living caddis,
and midge larva. Both male and female Skwala nymphs when fully mature will
start staging in the idle side water downstream of major riffles about a
month prior to emergence. Water temperature, and lunar cycles trigger the
nymphs to crawl out in the darkness of night to cobblestones next to the bank,
often some will crawl well over 30 feet from the side water. They follow other
Skwala nymph’s scent pheromones which they trace to livable spaces under the
cobblestones. They split their nymphal shuck and emerge into a winged adult
resulting in an incomplete metamorphous. Immediately, the males seek out
females to mate with, and no time is wasted during this effort. Often while
flipping cobblestones on dry land searching for the adult you will find a group
of them mating. During
night time and cold periods, they reside underneath the larger cobblestones. As
the sun warms the surrounding cobbles through solar radiation, they crawl out
and sun themselves until warm enough to actively crawl and sometimes fly.
Skwala stones are most active from mid-day until late afternoon. They love
sunny days and will often hide and protect themselves under the cobblestones
during prolonged periods rain, and cold weather.
When
walking the bank while searching for active rising trout, I always keep an eye
on the surrounding willows. When I do see swarms of Skwalas in the willows,
it’s a good clue on where to concentrate your fishing efforts. Adult Skwalas can
mate several times through the time period they are alive. Most crawl from spot
to spot, or float downstream with the currents, and at times will fly to
relocate themselves, lay eggs, or to find a new mate. It takes on average, a
few days to a week for eggs to develop inside a female Skwala stone. The eggs
are then pushed out to the tip of her abdomen and are held in place until ready
to be deposited in the water.
The
egg ball consists of dozens of smaller eggs held together in a sack, the ball
is sparkly and shiny and black in color and easy to identify to the naked eye.
Most females will crawl to the water’s edge, enter the water, and drift
placidly down with the currents while ovipositing their eggs. Other females may
fly over the water and splash down to achieve the same result in ovipositing.
It takes a
period of time in the early stages of the Skwala hatch for trout to key in on
both the nymphs and adults, and also to recognize when Skwala adults are most
active. Once the trout dial it in, they will swim into the side water around
noon time next to the bank where Skwalas will be in the drift of the foam lines,
and wait patiently to intercept them. While drifting, the legs of a Skwala
stone are very active as they kick them back and forth. This is a trigger
mechanism for trout, and why rubber legs on fly imitations are an important
component for Skwala patterns.
 |
| Cast less, and observe more for greater success |
As mentioned
above, there are also good populations of Skwala stones on the Truckee River as
well as the East Walker, and the Wild & Scenic Middle Fork Feather River.
On the Yuba, Skwala emergence is from the middle of January to the middle of
March on average. As the hatch winds down in March the trout are used to seeing
them day in and day out, and will continue to take artificial patterns
presented properly. On the Truckee they emerge much later due to a higher
elevation and an overall colder environment. The hatch on the Truckee generally
is from the beginning of March to the end of April, and likewise for the MFFR,
but often we see them well into May. On the East Walker, the Skwala stones are
active from the middle of February to the end of March. These are general guide
lines as weather, high flows, and lack of sunny days can greatly influence the
emergence of the higher elevation Skwala populations.
Each river has
local favorite patterns. Below I have provided a list of my “go to” nymphs and
dry flies that imitate the unusual specific characteristics of the Skwala
stone.
Nymphs:
- Jimmy Legs Stone #10-12, mottled
yellow olive/coffee.
- Pat's Rubber Legs #10-12, mottled yellow olive/coffee.
- Mercer's Poxy Back Stone #10-12.
- John Barr's Skwala Stone #10-12.
Dries:
- Unit Skwala #10-12.
- Double Dutch Bug #10-12.
- Stimulator #10-12, yellow olive.
- Dan LeCount's Bullet Head Skwala #10-12.
On the left is the size 12 2xl Unit Skwala male, and on the right is the size 10 2xl female. This is the freshly hatched color I use.
This is the aged color of a Skwala adult with its more spicy mustard appearance. Male on the left, and the female on the right.
Presentations
for nymphing are straight forward and standard with your typical indo rig, or
tight line set up. Targeting specific water downstream of riffles and obtaining
a dead drift is much more important than a particular pattern. For dry fly
presentations, I typically use a standard upstream approach while searching,
and when a rising fish is encountered I will then use a fly first downstream presentation.
The “standard” presentation for fishing a Skwala dry fly involves making a cast
upstream and stripping in line with your line control hand as the fly rides the
currents back down towards your stationary position. Line control and keeping
slack to minimum is critical. In this scenario there are no rising fish, and
the angler makes a series of “fan casts” from near to far in order to
effectively dissect a small section of the river before moving upstream to
explore fresh unmolested water.
“The Reach Cast”
is considered to be a very technical presentation, and is often used to highly
educated trout because it delivers the fly first. Simply meaning that a rising
fish only sees the fly as it enters its cone of vision. This presentation is
best executed by being upstream and across from your acquired target. The
angler makes a series of false casts that is aimed slightly downstream towards
the rising fish, this allows the angler to gauge the correct distance of line
needed. On the final forward cast, while the line is still in the air, the
angler moves the tip of the rod upstream. In doing so, it provides an aerial
mend, and the fly lands first with the leader and fly line trailing upstream of
it. Once the fly, leader, and line make contact with the water, the angler
brings the rod tip back downstream and begins paying out line using the “Bump
Feed”. Also known as stack mending, line is dispersed from the tip by moving
the rod up and down, while the line control hand feeds the guides of the rod
with a specified amount of fly line. Again, line control will dictate your
success. Too much slack will result in a missed take, not enough slack will
drag your fly during the drift, and the trout will refuse your fly. An adult Skwala
drifts on the surface with very little movement, except for those twitchy legs.
The
allure of fly fishing to the different hatches we encounter is the fine tuning
of our approach to each unique individual species. From their behavior, to the
flies we tie to imitate them with, it’s the intricate details that count. I
often find the study of these aquatic insects and their connection to the
natural world far exceeds the actual fishing. I’m truly grateful for these
experiences…
