The Eyes Have It

There is no question that more large fish are caught on streamer type fly patterns than any other fly style. Streamer flies, designed to imitate small fish, are the preferred target of larger fish. Why? By allowing minnows and bait-fish to do all the work of concentrating nutrients from smaller organisms, larger fish are capitalizing on the collective efforts of all the smaller fish that they eat. This is a far more efficient feeding strategy that allows large fish to grow even larger than they otherwise would.

So what makes a good streamer pattern? It all comes down to feeding mode and search image. If fish are feeding opportunistically, just the darting motion of the retrieve is enough to suggest a minnow in distress – the actual streamer pattern used is irrelevant. If fish are in the non-hatch mode, size shape and color will come into play – here, matching the color pattern of the predominant bait-fish is needed to trigger a response. For the more selective fish, other elements that complete the search image are needed – and the number one element to complete the search image is often the eyes.

There are hundreds of different streamer pattern out there, and all will catch fish to some degree depending on target species, location, and feeding mode. But the number one proven streamer that includes all of the search image elements in one package has to be the Clouser Minnow. This fly can be tied in a variety of sizes and, with its predominant dumbbell eyes, will trigger even the fussiest fish into striking.

If you are looking for solidly tied and durable Clouser Minnows, in a variety of colors and sizes, check out some of Brian’s creations on troutfodder.com

Hopper Heaven

One important lesson I have learned as an entomologist is that yearly weather trends can have a big impact on the population levels of different insect groups. Here in the east slopes of Alberta, the summer has mostly been hot and dry. Fewer mosquitoes to be sure, but the wasp populations are booming. A fair trade as far as I’m concerned.

Another advantage of hot, dry summers is the inevitable boom in grasshopper numbers. They have literally reached plague proportions in some communities in the far south, and while the numbers along my favorite trout streams have not developed into a waking nightmare, they are numerous enough to draw the full attention of feeding trout.

Like any other trout feeding scenario, when specific bug species become more numerous, they inevitably end up in the drift more often. As trout encounter and feed on these specific bugs more often, they develop strong search images that drive future feeding behavior.

Mature hoppers are a big mouthful for most trout – and well worth the effort and risk of taking up feeding stations right along the bank. When I see lots of hoppers diving out of my way as I walk the stream, running a hopper pattern tight to the bank becomes my MO for picking up some big fish.

The Observant Angler

Any time you are out fly fishing you should always be on the lookout for signs of actively emerging bugs and be prepared to adapt to unexpected situations. This past weekend my expectations for the usual Green Drake and PMD hatches did not materialize. Rising fish were sporadic at best and my Green Drake and PMD patterns were completely ignored. As the morning wore on I noticed an increasing number of Ameletus exuvia on the stream-side rocks and a few duns fluttering about.

Fresh Ameletus exuvia along the edge of a small freestone river.

These mayflies crawl out to emerge so there are no nymphs rising to the surface, no emerger stage, and the duns are generally not available to feeding trout. Despite this, the hatch can still provide for some good action on the nymph. 

Ameletus nymphs tend to inhabit the slower margins of streams but still like to be in proximity to faster flows. Their habit of darting out into deeper and faster water during emergence migrations can get them into trouble with trout lurking along the seams and waiting to pounce.

I switched to a mottled Hare's Ear type pattern in size 14 and targeted the softer water along the edges. The presentation included the usual segment of dead drifting but at the end of the drift I would swing the fly towards shore to imitate the nymphs swimming back to safety. Takes were both on the dead drift and on the swing.

I connected with a reasonable number of fish through the afternoon but the catch rate could have been higher if I had not been so focused on what worked in the past or was supposed to work. It is the observant and adaptable angler that sees the most success.

Drunella vs. Pteronarcys

As I mentioned in last week’s blog post, competition for resources can lead to more bugs in the drift as cohorts of individual species reach maturity – this is what we call intraspecific competition (intra = within, and specific = species). But competition between different species (interspecific competition) is also quite common.

In this week’s Short Shots video, a Green Drake nymph (Drunella grandis) is feeding on a dead Baetis nymph it has found. Along comes a much larger and brawnier Pteronarcys nymph who, after a short altercation, claims the prize for itself. In this case, instead of the loser being cast into the drift, it just sits nearby and sulks.

Taking Advantage of Pre-hatch Migrations

We often think of the opportunity to fish nymphs during pre-hatch or hatch migrations as being limited to insect groups that crawl out to emerge. But for insect groups that emerge at the surface in open water, like many mayflies and caddisflies, there are also migratory activities in the days leading up to a hatch that increases their exposure to feeding trout and imprint search images in the trout’s brain.

As each generation of each insect species approaches maturity, and the bugs become bigger, requiring more resources to support final development, competition for prime feeding spots heats up. This competition can result in more bugs in the drift through two mechanisms; direct conflict and intentional migration.

In direct conflict, two individuals battle it out over the most productive feeding spots. The loser if often cast into the drift, where it may tumble with the current for a few meters before regaining a foothold on the bottom. I once witnessed two Brachycentrus caddisfly larvae doing exactly this. It was a hard-fought battle, but in the end, one was ejected into the current and went tumbling downstream.

Brachycentrus caddisfly larvae lined up in prime feeding stations. As the water level changes,
the best spots on the rock will change - leading to a game of "musical chairs".

While direct conflict results in sporadic numbers of nymphs and larvae in the drift, intentional migration results in consistently large numbers of bugs traveling with the current. If there is too much competition on a particular riffle, or the resources are being depleted, the most expeditious strategy for moving to greener pastures is to float downstream a ways and explore new areas. These migrations, often taking place in the late evening, are far more common than most anglers realize.

With specific species of nymphs or larvae being more common in the drift as hatch periods approach, trout are more inclined to form search images for, and feed on, the ones they are seeing most often. I often use this to my advantage by fishing the corresponding nymph of whatever insect has been recently hatching during periods when there are no active hatches.

More Migratory Mayhem

Dragonfly and damselfly nymphs are two of the biggest draws (or at least the biggest bugs) as far as aquatic insect migrations go in lakes. But if your preference is to fish streams and rivers, it is the stoneflies that cause a stir at this time of year with their migratory antics.

Like the Odonates, stoneflies crawl out to emerge and so the adults are not available to feeding trout until they return to the water to lay eggs (or get blown onto the water).  Despite this, stonefly hatches can provide some fantastic fishing both during a hatch and in the days leading up to a hatch.

Things that lurk in the dark (Pteronarcys californica adult)

As the time for emergence approaches, many stonefly nymphs will start to migrate from their preferred feeding habitats to near-shore areas where conditions favor a smooth transition to the terrestrial world. As they migrate they become more available to feeding trout; both as they crawl along the bottom, or enter the drift to surf into back-eddies and slicks. Trout will station themselves along edges near the shoreline to intercept anything that wiggles or crawls within range.

When hatches are heavy, shed exuvia can be found on many surfaces along a stream
(Pteronarcys californica exuvia)

With more trout feeding on these often larger nymphs, search images are formed and retained as the migrations progress to the actual act of emergence (often taking place after dark). Knowing what species are present in your local waters can be a big help in fly selection. A quick search of shoreline rocks, bushes, or bridge abutments can provide clues as to which species are active. Golden stonefly nymph imitations are generally a good choice and can simply be drifted along any shoreline edge or seam, or slowly worked along the bottom in the slack edge-water below a riffle.  These are big bugs that bring larger trout to the feeding trough, so even if the water is a little high and off-color, working the edges with a stonefly nymph is always worthwhile.

Golden stones are common on many western streams and rivers (Hesperoperla pacifica nymph)

Migrating Damselfly Nymphs

The month of June is prime time for fishing damselfly hatches on lakes. Although I have witnessed trout specifically targeting the adults as they perch on overhanging bushes along the shoreline, it is a rare event. During a hatch, most of a trout’s attention is focused on the migrating nymphs as they make their way from submerged weedy shoals to emergence sites along the lake-shore.  

Depending on conditions, and the damselfly species involved, migrations can take place along the bottom or just under the surface. I have only encountered a handful of hatches where I observed nymphs migrating just sub-surface. Most of the time, the nymphs are swimming along the bottom or just above the weed-tops. If I see signs of recent emergence, or an active hatch in progress, I will work a Migrating Damselfly Nymph on a sink-tip line with a slow or intermediate sink rate. In either case, the mode of propulsion for the nymph is the typical and somewhat inefficient side-to-side undulation of the body.

A multi-exposure strobe photo of a swimming
damselfly nymph (Enallagma annexum)

Creating a fly that effectively mimics this undulating behavior has been the goal of many a fly tier over the years. Strategies have included everything from long tails of marabou to articulating bodies, and even the addition of a tiny crank-bait style lip to the fly – but all to no avail. While some of these fly patterns do provide a small measure of undulatory action (in the up and down dimension as opposed to the desired side-to-side direction), I feel the advantages are not sufficient to warrant the extra effort. Instead, I focus on the more important factors of retrieve rate and search image.

A newly emerged (teneral) damselfly with shed exuvia (Lestes sp.) - a sure sign
of a hatch in progress.

If threatened, damselfly nymphs can move at a pretty good clip – but only for short bursts. During migration, they typically plod along in a very slow but determined manner, often pausing for short periods to rest. Your retrieve should follow this pattern. A very, very slow hand-twist retrieve (¼” to ½” per second) with the occasional pause will bring more takes than a rushed retrieve. It takes a lot of patience to work a fly this slowly, and you will need to use a line with a slow enough sink rate to avoid constant hang-ups, but the higher percentage of takes makes it worthwhile.

Search image requirements are fairly simple. There is the usual size, shape, and color to consider. Beyond that, I like a fly with prominent eyes and just a short tuft of marabou to imitate the broad set of gills at the posterior end. A medium olive Migrating Damselfly Nymph in size 10 gets the job done under most circumstances.