One of the beacons of light for fly fishers in Northern California during 2020 was the Skwala stonefly hatch on the lower Yuba River. It was the Year of the Skwala. From December 27, 2019, to April 5, 2020, Skwala stoneflies were active on the water’s surface, native rainbows were eating them on a consistent basis, and fly anglers were reaping the reward in the form of bent rods. It was the longest and best stonefly hatch I’ve ever witnessed in an entire life working and fishing the rivers of California and the West. When the Yuba River received monstrous flows in 2017 and in 2019, the river changed dramatically, and nearly every aquatic insect took an accelerated ride out to the Delta from those f lows. However, Mother Nature is resilient, and in a short period of time, the bug populations rebounded once again, as they always do, including the Skwala stoneflies.
If there is one hatch I could say I’m really in tune with, this is it. I find it intriguing, because the bugs emerge in the middle of winter, at night, and their behavior is affected by so many variables from day to day. I’m always learning something new when I’m on the water in Skwala season. Six years ago, I wrote about what I knew then in “The Skwala Hatch” in the November/December 2014 issue of California Fly Fisher. The basics I discussed there haven’t changed, but here’s what I’ve learned about approaching the Yuba’s Skwala hatch since then.
The Hatch
Many anglers believe that the Skwala hatch happens nearly all at once in a rather short time span, when in reality, it is a drawn-out affair that starts slowly in late December, peaks in the middle of February, and slowly wanes though March. In early December, the first nymphs begin prestaging for emergence in idle side-water areas downstream of major riffles. You will start noticing the dried shucks from Skwala nymphs that emerged near the river’s edge, providing evidence of exactly where they were emerging. When I fish and guide a particular stretch of water on a near daily basis, I can keep track of how many Skwala nymphs are emerging at such spots. I choose a large cobblestone or wall of rock where there are numerous shucks. I then brush them off, wiping the slate clean. The next day, or on following days, I check the spot again and count the number of Skwala shucks since my last visit. This observation gives me an idea when and where Skwalas are emerging. Over the months, I keep checking these areas and keep a mental count, tracking the progress of the hatch. You can do this, too.
Yuba River Skwalas differ in color from most adult Skwala stoneflies across the West. Those are a true olive color, while in general, Yuba Skwalas are a spicy mustard hue with a hint of olive. But that’s a generalization. In 2020, I spent a great deal of time observing and handling many different Skwala adults as I walked among the cobblefields, and I was blown away by how each differed from the next in terms of color. Some had a splotching of black or brown over the standard color, some were very olive, with vivid yellowish segmentation marks, while others were completely bright yellow (freshly hatched, is my guess). Since adult Skwalas live a long time for an aquatic insect and ingest food and water, I’m starting to wonder if their diet affects their color. I wish I had the time to do the research. It seems like a good project for a keen entomologist with a master’s degree in Plecoptera.
Do these differences matter? The correct color can be of importance in fooling a rainbow into consuming your imitation. On the other hand, when a trout looks into the bright sun with a natural floating overhead, its color may not matter at all. As a guide buddy pointed out, his clients were having success during bright, sunny days using an all black Rogue River Stone pattern. That’s a pretty standard scenario on the Yuba River with aquatic hatches. One just never knows what the response of the trout will be at any given time.
I’ve also learned over the years that air temperatures greatly affect the general activity and the f light behavior of the adult Skwalas. In February, we had some pretty cold days with a sadistic north wind, the kind of wind that cuts right through you. On those days, finding an adult crawling around was a rarity, because they were hunkered down below the cobblestones, or, finding a wind break, basking in the sun. With fewer stoneflies buzzing about, fewer trout were looking up for them in the foam lines than there would be on a warmer day. For those colder days, an angler intending to fish the Skwala hatch needs to be prepared to fish any of the spontaneous mayfly hatches that may occur — Pale Morning Duns, “Pinkie” Epeorus mayflies, and Blue-Winged Olives, especially in foggy and drizzly situations.
Conversely, when air temperatures reach 70 degrees and above, there will be a lot of adults out during peak periods of the day, with an increase of in-flight activity, especially from ovipositing females. The most favorable weather conditions for hunting feeding trout with a Skwala dry on the Yuba River are 70 degrees with some cloud cover. The timing of daily peak activity varies with the month. On a cool day in late January, the best time may be from 1 p.m. to 4 p.m., but a month later, on a warm day in February, it can be from 11 a.m. to 5 p.m.
Emergence intensifies in the period around the full moon. This is an example of the type of behavior I find so fascinating when it comes to aquatic insects. Most stoneflies are nocturnal and hatch throughout the night or in the very early morning hours of darkness. One possible reason why Skwala stoneflies hatch in increasing numbers when the moon is full or nearly so could simply be that they can actually see what they are doing when first hatched, when mating as soon as possible and perpetuating the species is the sole reason for existing. Though a full moon can be a hindrance to good fishing on still waters such as Eagle Lake, it bodes well for fishing the Skwala hatch the next day on the Yuba River. When the hatch is in full swing, though, and the trout will not eat your adult pattern late in the day, sometimes it’s because their stomachs are full and they are no longer hungry. It happens on days when there are a lot of bugs drifting down the feeding lanes.
Rigging
The prime sport when fishing the Skwala hatch is stalking rising trout with a dry fly. I’ve always preached using a long leader, which I still advocate for use in calmer weather and when targeting the slower water next to the bank and in glassy tailouts. Keeping your fly line far away from your imitation just makes sense. A 12-foot leader tapered to 4X is a good length for such occasions. However, on windy days, I’ve watched my students struggle casting with a longer leader, missing the feeding lane altogether or creating a bird’s nest of tangled monofilament. During blustery days, shorten your leader to 8 or 9 feet. With a shorter leader, you’ll have more control and better accuracy in the wind, completely turning over the fly line and leader. The wind actually can help the angler, because the ripples it produces reduce the need for stealth, including long leaders.
Most of the time, I use 4X to attach a Skwala dry. The trade-off is you’ll get more grabs with 5X, but fighting and landing the fish will require more finesse and the right rod with a softer tip to protect the lighter tippet.
For attaching the Skwala adult pattern, I like to use a Loop Knot to impart a little more movement of the fly and its rubber legs. Check this knot often to make sure it remains at maximum strength. With the movement of monofilament rubbing the eye of the hook, the knot tends to wear out. If you’re in doubt about your knot or if it fails when tested, clip off the fly and tie another knot. Keep in mind that a Loop Knot uses more monofilament material than a Clinch Knot. The loop should be tied as small as possible — too big a loop will entangle your fly or foul the rubber legs.
I don’t nymph much on the Yuba I’d rather fish dries during the time of day when that style is most effective but there are two ways to fish Skwala nymphs: using a movable-indicator rig or tight-line nymphing. The Yuba is a big, wide river, and an indicator rig allows the fly angler to make longer drifts farther out than a tight-line rig can reach. With either rig, though, at the end of the drift, you can allow the flies to swing in the current and hang like a soft hackle. Yuba trout are very receptive to a swung fly.
A basic indicator rig is composed of 2 feet of 15-pound mono tied to a 3-millimeter tippet ring, to which is attached 6 feet of level 3X fluorocarbon tippet. This section is where you attach a movable indicator to give you a wide range of water depths to fish. To this section another tippet ring is attached, this time using a 2-millimeter ring, then 12 inches of 4X or 5X fluoro, then a Skwala nymph pattern. Off the bend of the hook, add an additional 14 to 18 inches of 4X or 5X is added with a smaller nymph, such as a Pheasant Tail or similar fly that imitates a Baetis nymph.
Tight-line rigging is really a matter of personal choice, and there are many ways to do it. You should use the same size tippets as mentioned above, with the heavier Skwala nymph as your point fly and the Baetis imitation hanging off the tag end above it. It’s as simple as that.
Presentations
For the most success when stalking rising trout from the bank with a dry fly, you need to make a downstream, fly-first presentation. The drift could be 6 feet or 40 feet, but it has to be without drag and in the right feeding lane. This style of surface presentation is also the best choice when fishing from a drift boat, casting slightly downstream toward the bank and under overhanging willows. From a boat, your drifts will be much longer, and the pilot of the craft can make small adjustments with the oars for a drag-free drift.
There are some situations where I use an upstream dry-fly presentation, but when I’m searching the water this way, I’m careful not to line any fish while casting to potential lies as I work slowly and methodically upstream. These areas include the inside main seam at the head of a major riffle and extremely rough water that hides every mistake and the presence of the line and leader.
When nymphing, a drag-free drift is essential, whether using an indicator or tight-lining. Always cover water from near to far, and fish every seam between fast and slow water that you can reach.
When fishing dries, if you’ve done everything right and luck is on your side, you’ll be rewarded with a grab off the surface. When that happens, many of my guests yank the fly right out of the mouth of the trout, setting the hook a second too early. I’m guilty of it, too, at times, usually when I’m rusty from not fishing enough. If possible, watch the head of the trout dip below the surface after it eats the fly, then set the hook slightly off to the side. It can be nerve-wracking at times when you have an eater that comes up slowly, testing your patience. I can remember an occasion during last season’s Skwala hatch when a client new to fly fishing had one of the most beautiful takes ever. You could see the entire fish’s large side light up in the late afternoon sun as it appeared suddenly in a foot of riffled water. He pulled the fly away from the trout before it even got it in its mouth.
Playing and landing a powerful Yuba River rainbow begins when the fish makes a screaming run or two. Be ready for this, and allow the fish to take line off the reel, keeping enough tension on the line to keep the barbless hook in place. For an athlete of a fish, that’s easier said than done. It’s best not to fight your quarry with the rod held high, using only the tip section of the rod to play the fish. Instead, use the entire rod down to the butt by lowering the angle of the rod off to one side. From this position, your rod is performing as it was designed to work.
Keep the fish in front of you and move the rod slightly upstream while also bringing back the rod’s butt section toward you. In doing so, you can move the fish efficiently from the heavy current into softer side water. Manually steer the fish toward you while keeping it slightly upstream of your position. With your net in hand, bend one knee for a lower position and move the rod behind you to one side for an easier net job. One key to landing a fish successfully is to try and position the fish on its side on the surface of the water and plane it into the net. When a trout is on its side, it cannot dig its head into the water and thrust away from you and the net.
Fly Patterns
For adult Skwala fly patterns, fishing flies that have the Yuba Skwalas’ spicy mustard color with a slight hue of olive makes a vast difference, but just as important is the correct size, and to complicate matters, the males and females are of different sizes. Carry both the smaller male adult imitations tied on a size 12 2X-long hook and female imitations tied on a size 10 2X-long hook. Some trout key on the male, while others look for the female, preferably with an egg sack attached. When it comes to shape, most commercial patterns are far too big and bulky for selective feeders.
The rubber legs on most dry-fly Skwala patterns provide movement that triggers a strike, but with the extreme angler pressure on trout during 2020, I learned that clipping the rubber legs the same length as the natural’s when a refusal occurred produced success. Take a break, catch a natural, and study the details of its profile, legs, and segmentation. Also observe how the natural rides flush on the water’s surface while drifting, with its legs robotically moving back and forth. The wings stay stationary and do not flutter, lying flat on its back. These details count when it comes to fish that have seen countless patterns drift overhead. While tying at the bench or streamside, make the adjustments that will help your flies become more effective.
There is one place for big, bushy adult patterns, and that is rough and turbulent water. Another lesson I learned from last season is not to overlook rougher water, whether a large inflow below a major riffle or the by-product of a midstream area of woody debris. A guest of mine found great success by covering that type of water during a trip last year. We were both amazed that a trout would come up and take a swipe at the fly in such conditions and marveled at how aggressive their behavior was.
Nymph patterns to imitate the natural are pretty basic. A standard for the Yuba is Pat’s Rubber Legs Stone, size 10, in olive. You can weight them with a bead in copper or gold or with lead wire. Vary the weight for fishing shallow or deeper water — I use a different color thread at the head of the fly to tell the difference between lightly weighted and heavily weighted nymphs. Or break the mold and create a new pattern that the trout are not use to seeing. Just keep the profile slender, with the exact size of the natural. Additions could include barred rubber legs, a different body material such as V-Rib, and some attractive sparkle dubbing in the thorax.
Tactics for Pressured Trout
Last January, there was great dry-fly fishing fly before lots of anglers turned their attention toward this popular hatch on the lower Yuba. Then the trout wised up. Later in the hatch, I started to fish and guide the more obscure areas that other wading anglers and boats did not touch. These locations include side water with bathtub-sized holes, shoals, back eddies, woody debris piles, and next to rock walls.
I can’t stress enough that the walk-and-wade angler needs to move slowly and keep a low profile while stalking individual trout from the bank. Then, before you make a cast, study the section of water you are going to fish, looking for concentrations of stoneflies drifting on the surface. Take notice of the foam lines and feeding lanes, make a solid plan for fishing the water in front of you, then execute it with confidence. But don’t pound the water over and over in the same place. Make a few good presentations, then rest the water while continuing to observe, then make a few more casts. You can also wander a hundred feet in either direction to probe for other active trout, then return to your previous spot, which has now been rested. A great accessory for observing and resting the water is a lightweight, compact, foldable, three-legged backpacking chair. Some of my older fishing buddies and clients use these and swear by them. They are a lot more comfortable than sitting on a cobblestone.
Looking Forward
It will be interesting to see how the 2021 Skwala hatch pans out. There are so many variables, from excessive amounts of precipitation that blow out the river to drought conditions that favor a stronger hatch. In today’s California, you just never know what the weather be. One thing is for certain, though, the Skwala hatch is always interesting, and there’s always something to learn from it that will increase your chances of success.
The Unit Skwala
I first learned about this pattern about ten years ago from a longtime client and friend. Dave would make the journey up to the Bitterroot River in Montana every March to fish the Skwala hatch. There, he was introduced to the Unit Skwala by his guide, John Cook. It is a fairly simple tie, but choosing the right materials makes all the difference. The materials noted below were chosen to imitate the Skwalas on the lower Yuba River.
For the body, select an acrylic sparkle yarn that is a spicy mustard color and twist it before wrapping it on the hook. This will give the appearance of segmentation in the abdomen and also will not absorb water as easily. The closed-cell foam underwing is an important component of the fly — it helps keep the fly floating while also giving the pattern the correct profile. Choose the highest-quality moose hair with minimal underfur for the bullet head and overwing. Unlike the original pattern, which has a full bullet head, I chose to tie a half bullet head, as on a Madam X, so I could show the smoothness and color underneath of the yarn material. The Unit Skwala is a proven pattern and my go-to fly for the Skwala hatch on the lower Yuba.
Hook: TMC 2302 or TMC 2312, size 10 for the female, size 12 for the male
Thread: Camel 6/0 UNI-Thread
Body: Spicy mustard acrylic yarn, spun tightly.
Underwing: Black Larva Lace stretchy closed-cell foam
Overwing: Premium moose hair
Legs: Brown circular medium rubber legs
Sighter: White EP Trigger Fibers
— Jon Baiocchi
