Hatches divided by half-month.
Super Major Minor Slight None
|Pale morning dun|
|Pale evening dun|
It's May, so watch the river levels carefully. If you see a sudden large increase, you can figure fishing is going to be poor on that river until the flows stabilize or drop significantly. If the flows are only up a little and the river is slightly colored, you'll do best with nymphs, and those nymphs will usually work best when drifted near the bank.
Trout are taking--or will soon be taking--drifting salmonfly and golden stonefly nymphs on rivers that host populations of these mega-sized insects. The key to effective nymph fishing is to get your fly to the bottom. Period. Spilt shot, beadhead, extra weight under the body dubbing--whatever it takes and is still legal. If you aren't losing a few nymphs, you're not doing it right.
Salmonfly nymphs are most active at dawn and dusk, so that's when they are most likely to get knocked loose and drift in the current--and when trout will be waiting for them. But that doesn't mean you can't catch fish all day, either. It just tells you when you'll probably do best. Fish below riffles, among boulder fields, and through drop-offs. Kaufmanns Stoneflies , Rubber Legs , etc.--they all work.
By mid-month, adult salmonflies will start to hatch. The key to the hatch is water temperature. When it gets around 52-53 degrees, the nymphs begin crawling to shore in earnest. Once out of the water, the adult emerges from the nymph, dries its wings, and flies to an alder tree where it utters the insect equivalent of "Hey, Baby, Baby." In their relentless pursuit of the opposite sex, adult stoneflies often fall or are blown out of the trees, land in the water, and are devoured by trout.
So if you cast a Clarks Stonefly , Low Ball Stonefly , Stimulator , or similar fly near shore and just downstream or downwind from overhanging vegetation--especially in the afternoon when the bugs and the wind are at their most active--you may catch a fish.
Note that just because the adult salmonflies are out, it doesn't mean trout are taking them yet. Trout are creatures of habit, and they can be slow to make the switch from nymphs to adults.
One hint: if you buy your salmonfly flies, buy them now because the fly shops only stock-up once and won't re-order until next year. If you wait too long all you'll find are empty bins or flies that are the wrong size, pattern, etc.
By late May we should be seeing some green drakes in the Metolius and a few other rivers. Hatches of this large insect usually occur in early afternoon. Green drakes are not found in large numbers in Oregon streams, but the bug is big enough to catch the interest of trout, both before and during a hatch. Before the hatch, a Poxyback Green Drake can catch fish when drifted through a run with a slow to moderate current. This fly has a shiny back, based on the fact that top of the thorax of most mayflies gets shiny just as it is ready to emerge. Use this fly before the hatch. During the hatch, use the Green Drake Paradrake , Green Drake Cripple , or similar pattern. Wait until a trout rises to a natural insect so you know where it's lying, then cast to that fish. Blind casting will only put the trout down.
You can still find occasional blue-winged olive hatches. These late bloomers tend to be big (for a blue-winged olive). A few size 16 and 18 Parachute Baetis , olive Sparkle Duns , or Baetis Cripples should be in your fly box. You may also encounter some very small blue-wings, about size 22-24.
Caddis continue to be important. Caddis-rich rivers such as the Deschutes and McKenzie have large populations of green caddis (genus Rhyacophila) and spotted caddis (genus Hydropsyche). Try a Sparkle Larva or Czech Nymph in size 14. The larvae often drift in the current and are taken by trout. This month we will also see hatches of spotted caddis. See below for the adult patterns. There are also sporadic hatches of green caddis 1-3 p.m. in soft water below riffles. The green caddis will hatch the early part of May, then come back again in fall.
Grannoms (genus Brachycentrus), the "Mother's Day Caddis," are important on some Oregon rivers. Use a Sparkle Pupa or Deep Sparkle Pupa with a green body and a tan shroud before and during the hatch. Dead drift it near the bottom, then let it swing up to the surface. If you see trout feeding consistently just subsurface or making splashy rises, cast a Sparkle Pupa upstream-and-across and let it drift drag-free just under the surface. See below for the color and size of adults.
Weedy water caddis (genus Amiocentrus) hatches will be found in slow-moving parts of some rivers this month.
With caddis fly patterns, "close" is usually good enough, so you only need a couple of fly patterns; just vary the color and size to match the natural insects. For a dry, an Elk Hair Caddis , Deer Hair Caddis , Casanova Caddis , X Caddis , or similar pattern works in these combinations:
- Green rock worm: size 12-14; dark olive body, gray wing
- Spotted caddis: size 12-14; brown to tan body, tan wing
- Saddle-case caddis: size 18-20; tan body, dark wing
- Grannom: size 12-16; olive body, tan or cream wing
- Weedy Water: size 16-18; dark olive body, dark wing
Many caddis species lay eggs by swimming or crawling underwater, and they are often taken by trout. Use a wet fly such as a Soft Hackle or a Diving Caddis in the sizes listed above for adults; caddis get darker when ready to lay eggs, so use darker versions of the listed colors.
Trout and steelhead have been spawning in many rivers, so if you're wading over gravelly areas or see small rocky spots that are "cleaner" than their surroundings, you're probably on a redd. Get off it, and don't fish in that area. Spawners need their rest.
Also, this is the time of year that salmon and steelhead smolts migrate to sea. They congregate in backeddies, below riffles, and near shore. They're suckers for a dry fly or anything near the surface. If you're catching a bunch of 5-8 inch "trout" that are shiny and silvery and maybe have the adipose fin clipped off, you're into smolts. Move on and fish another area. They are likely to be damaged by your fly, whether it's barbless or not.
Hatches divided by half-month.
Super Major Minor Slight None
Callibaetis hatches will begin in earnest on many lakes this month. They usually occur late-morning to mid-afternoon. Trout will feed on nymphs for a couple of hours before the hatch. Take advantage of this and cast a nymph pattern, then retrieve it slooooooowly; use an intermediate line with a long leader. A Flashback Callibaetis or Flashback Pheasant Tail , size 14-16, should work quite well. In my experience, a Flashback PT outfishes a regular PT by 3-to-1 during this hatch. The reason is that many nymphs develop a shiny back just before they hatch, and trout look for this feature.
Trout will also be feeding on midges . Look for several hatches of different species throughout the day. The deep midge tactic is good for midday hatches because trout are reluctant to leave the safety of deeper water and prefer to take their midges farther down the water column.
In many desert lakes, there is a very large midge that hatches in early May and is preferred by trout. It is matched by a black-bodied, silver or white ribbed pupa pattern in size 10 or 12; the pattern MUST be slender.
Damselfly nymphs should become effective on many lakes as they warm up. Present a good pattern, such as Dougs Damsel , Marabou Damsel, or Approximate Damsel , near weedbeds. The standard damselfly retrieve is to pull two inches of line in two seconds, pause two seconds, then repeat. Use an intermediate line; damselfly nymphs move in the top inch or so of water. That said, you can do pretty well just trolling a damsel nymph as you slowly and steadily kick around the lake in your float tube. But fishing writers don't like to talk about stuff that's that simple.
If the weather continues to be cool, most of Oregon's higher lakes will be locked in snow and ice, and it will be several more weeks before some of the lower high lakes are open.