At first glance, the eddies of Oregon's Deschutes River can look lifeless and empty in early spring. But often, if you peek through the bankside brush and carefully watch the part of the eddy where the big and sometimes brutal river turns on itself and ambles softly upstream along its banks, you'll see that the eddies are alive with dark, ghosting forms and large, lofting noses. If you draw closer or, better yet, use small binoculars, you might see precisely what tiny things those trout are taking.
At times you'll see tiny midges, usually pupae, just under the water's surface or pinned in the film of the lazy eddies. At other times you'll see #12-#14 March Brown mayflies (Rhithrogena morrisoni). Most often, though, you'll see trout nosing around after #18 and #20 Blue-winged Olives (Baetis), taking the nymphs as they rise toward the top, emergers as they struggle in the film, or duns as they boat the surface and wait for their fragile wings to dry.
Spring Olives are like candy to trout. Even when your preliminary scouting reveals larger insects, you must make sure no Olives are among them. If they're present, trout will often feed selectively on them and ignore the more obvious insects.
This Olive selectivity is true on most Northwest waters in early spring, from British Columbia's streams to Washington's Yakima and Oregon's Crooked, and from northern California's upper Sacramento to streams such as the Fall River and Hat Creek. Hatches begin around February in California and March in the northern waters. Almost all of these waters, whether freestone or spring creek in origin, have springtime Olive hatches that are difficult to see.
The biggest problem with matching the spring Olive hatch is noticing when it happens. That is true on any water, whether the surface is glass-smooth or slightly riffled, and trout only take Olives with delicate, imperceptible sipping rises. I don't know how many times I've sat out bad weather in the car, only to wade out later and discover that trout were rising almost invisibly. You must take that closer look.
The Baetis Complex
The Blue-winged Olive is not a single species. The name refers to a group of species in the genus Baetis. While there are many mayflies with olive bodies and gray- or dun-colored wings, it is not necessary to know whether trout are eating Baetis bicaudatus or Baetis tricaudatis.
Many anglers refer to the many different species of Olives as the "Baetis complex." To add to the confusion, there's been recent taxonomic revision of the Baetis group, and some species that were once listed as Baetis are now split out into other genera. Other species that were once listed as closely-related Pseudocloeon are now listed as Baetis. Interviews with trout since the revisions have revealed surprising news: The fish simply don't care.
Fish continue to eat the insects and accept the fly patterns that match them. The best way to determine an appropriate fly is to capture a local specimen (nymph, dun, and spinner) and examine it carefully. Look for three key aspects — size, form, and color — and select a fly pattern that closely matches the natural (see sidebar below). With the right pattern and a good presentation, you're sure to catch some trout. Trout are hungry in spring; they're not anxious to refuse you. Noticing that they're even taking Olives is the critical first step in the process.
Once you determine that trout are on Baetis, you must recognize which stage of the insect the trout are taking. Sometimes trout focus on rising nymphs; at other times, they prefer stranded emergers. When winged duns are most abundant, the fish might switch to them, or they might not. You need to notice.
Look at fish riseforms: Are they subsurface or surface? Look at floating duns: Do they go down in rises or do they float right through them? Noticing these clues can help you choose the right pattern. One of the easiest ways to sort it all out is to fish two flies — an emerger and a nymph dropper; or a dun and an emerger; or a dun and a nymph dropper. Where regulations permit, you might try three flies, but two are plenty and tangle less often.
It's critical that you have a variety of flies to match spring Olives. Trout rarely focus on color when they feed on these hatches; the naturals come in several shades, even within a particular species. However, trout are snobbish about size and form. One day a Sparkle Dun pleases them. The next day, or the next hour, a Harrop Hairwing Dun causes them to tip up and sip. If you're not armed with three or four variations with different silhouettes and sizes, you're narrowing your chances of catching trout. I stick with Sparkle Duns, Hairwing Duns, and traditional hackled dressings (#16-#22), but other styles like CDC emergers, thorax-style duns, cut-wing duns, and parachutes are effective patterns.
No matter what fly you choose, presentation is equally important. This piece is too brief to detail presentation techniques, but I will stress this: Take your time to set up the right approach. You'll need to establish a position that allows you to make the right cast according to the water conditions and the rising trout. Usually, an across-stream reach cast, downstream wiggle cast, or some variation of Art Lee's stop-and-drop cast gets the job done. The stop-and-drop, oversimplified, puts the brakes on the line in the air so that it settles to the water in a series of S-curves. As the slack in those curves plays out toward the trout, the fly floats drag-free.
Also, you'll need to refine your gear for this delicate fishing. Two- to 4-weight rods are ideal and help protect light tippets. Leaders should be 10 to 14 feet long and tapered to 3- and 4-foot, 6X or 7X tippets.
Springtime fishing in the Northwest for Olive-sipping trout is a delicate game, but the fish take drys deliberately if you make the right presentation. The instant that first fly of the season arrives in a fish's window, life approaches some sort of climax known only to fly fishers who look closely.
Matching Baetis Naturals
With a seine or dip net, you can gather Baetis nymphs or adults and use the following descriptions of the mayfly's stages to identify them onstream.
Nymphs. Baetis nymphs live in fast-moving water and are found in and around aquatic vegetation. Spring emergences begin when water temperatures pass through the mid- to high 40s F. and approach the low 50s.
The nymphs are streamlined insects that swim like minnows. They have three tails with a shorter center tail (some species have no center tail) and antennae two times longer than the width of their heads. Nymphs have single gill plates on their abdominal segments, and their bodies are tan, olive, or dark olive-brown. Size: #16-#22. Duns. Male duns are best identified by their large, cylindrical, upturned eyes. Both the male and female have tiny, elliptical hind wings (some groups have none), two tails, and pale to dark-gray wings. Their bodies are light to dark olive, olive-brown, or olive-gray. Size: #16-#22.
Spinners. Spinners also have large, cylindrical, upturned eyes. They have small or no elliptical hind wings, two tails, and clear wings. Their bodies are pale olive-tan to dark brown. Size: #16-#22.
Dave Hughes is editor of the Flyfishing and Tying Journal. He lives in Portland, Oregon.