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Fly Fisherman Throwback: Big Limestone Trout

They're the toughest game in town, but they can be caught using these special techniques.

Fly Fisherman Throwback: Big Limestone Trout

Limestone spring creeks like Big Spring Creek in central Pennsylvania often hold large trout. Although these fish are extremely wary, they can be caught. (John Randolph photo)

Editor's note: will periodically be posting articles written and published before the Internet, from the Fly Fisherman magazine print archives. The wit and wisdom from legendary fly-fishing writers like Ernest Schwiebert, Gary LaFontaine, Lefty Kreh, Robert Traver, Gary Borger, Joan & Lee Wulff, Dave Whitlock, Vince Marinaro, Rene Harrop, Doug Swisher & Carl Richards, Nick Lyons, and many more deserve a second life. These articles are reprinted here exactly as published in their day and may contain information, philosophies, or language that reveals a different time and age. This should be used for historical purposes only.

This article originally appeared in the March 1990 issue of Fly Fisherman magazine. Click here for a PDF of the print version of "Big Limestone Trout."

On a small, crystalline limestoner, on a sultry July afternoon when I was eight, l saw my first leviathan trout. It came out from an undercut bank and surfaced like a German submarine in broad daylight. And then, to my amazement, it gently sipped something small off the surface. I thought that the biggest browns fed with barracuda-like slashes during the ghostly hours of the night. This one made only a dimple. Here was a refined trout, a connoisseur. From that day on, my pursuit of such leviathans has been a personal challenge ... and a passion.

Trout grow large on such limestone spring creeks as the Letort, Penn's and Spruce creeks in the East and Armstrong's, Nelson's, and Silver creeks in the West. They have everything trout need: uniform water flows, clarity, the right temperatures, excellent growths of aquatic vegetation and undercut banks for cover. And dissolved calcium and magnesium carbonate from the limestone bedrock make the water quality especially rich in foods, including crustaceans, mayflies, midges, and sculpins.

Limestone trout can be highly selective, and the largest ones learn early in life to key in on protein-­rich food found in the weed-filled channels and undercut banks. They adhere to the "why go up, when you can stay home comfortably" mentality of feeding. Because of this wariness, when going after trophy browns I use subsurface flies, especially when I fish small to mid-size limestoners.

Components of the Lie

Spring-creek structure provides many benefits to the trout trying to minimize its energy output. Besides providing foraging habitat, the weeded channels and undercut banks offer protection from sunlight and currents.

You'll find primary spring-creek lies for large trout where a there is a union of desirable spring-creek features. In Figure 1 a gravelly riffle, a weed-channel with a clear, sandy patch, and an undercut bank creates the conditions for a choice feeding and holding lie. The lie can be deceptive. Look closely; many anglers focus only on deeper runs and pools when stalking big trout.

Illustration of typical spring creek trout lies
Figure 1. Notice how weed channels, instream obstructions, changes in the stream's bottom, and an undercut bank combine to form a primary lie for large trout. A secondary lie is shown behind the primary lie. Large trout hold in these types of lies and can be caught if you present your fly to them naturally. (Rod Walinchus illustration)

The weeds and watercress oxygenate the water and add to its depth and displacement, in addition to providing forage for plankton and crustaceans. The aquatic vegetation shields the current's flow and filters out silt, creating clear, sandy patches that are essential for a large trout's clutter-free surveillance. Various species of Baetis, Pseudocloeon, Tricorythodes, Simulium, and chironomid midges also favor these areas. An undercut bank allows the trout to survey and pursue the current's biological drift (drifting insects and crustaceans) while having a roof to hide under. Such a primary lie supports the theory that a large trout takes 90 percent of its food on or near the bottom.

A secondary lie, an open lie, is one to which the fish must move to feed. Large fish are drawn to this more vulnerable lie during intense hatch or drift periods. Such a lie, often a stream-bottom pocket, often exists in the shallow tail section of the primary lie. During intense hatch periods, the large trout of the primary lie might occupy this shallow area for feeding on emergers, duns, and spinners. And during terrestrial season it may move into the shallow pocket in broad daylight.

On a misty early morning you might find a large trout still cruising the shallows, continuing its nightly feeding binge on sculpins or crayfish. However, the shallow lie is often be occupied by another trout lying in wait to take over the larger trout's primary lie. Spring-creek trout are competitive and territorial.

Trout in secondary lies are more easily spooked than trout in primary lies, perhaps because a trout in a secondary lie has a feeding lie separate from its secure holding lie, while a trout in a primary lie has a secure holding and feeding lie in one location. However, fish in the secondary lies are more willing to accept a fly.

Though large spring-creek trout concentrate on subsurface food, they occasionally surface-feed during periods when food is abundant. On larger limestone spring creeks, such as Silver Creek, Penn's Creek, the Henry's Fork, and the Test, the sheer magnitude of the water gives a large trout the comfort it needs for cruising the surface.


Larger limestone spring creeks have relatively featureless structure, so feeding lies for large, surface­feeding trout are difficult to detect. But choice primary feeding lies do exist, and they are guarded closely by the large trout. I look for areas where the stream's flow is one to two feet per second or where surface feeding is persistent.

Limestone Biological Drift

Large limestone trout feed year-round on the abundant crustaceans, followed by periodically emerging aquatic insects, predominantly Olives, sulphurs, caddis, Tricos, and Simulium midges. Trout easily pick off these chief components of the limestone creek's biological drift in the relative calm of the bottom waters, where the vegetation cushions the stream's current. Anyone who has experienced the highly-touted sulphur hatch knows the importance of fishing the nymph heavily weighted along the bottom. Though cased caddis are found in extraordinary numbers in the alkaline waters of a limestone stream, they are rarely components of drift and are seldom sought by trout.

I believe that on spring creeks where heavy populations of crustaceanss are not present, trout free rise more often. I was surprised to learn in fishing the Test, Avon, and Itchen rivers in England that the waters are relatively sparse in protein-rich crustaceans. The world-famous free-rising of the Test trout may be due to that stream's scarcity of crustaceans, the feeding of floating pellets to the trout in the hatcheries and stew ponds, and the relatively long time that the stream's large mayflies (Ephemera danica) float on the surface while drying their wings.

Peculiar Behavior

When pursuing large limestone trout, look for peculiar behavior that may make the trout more vulnerable or, conversely, impossible to catch. As our leviathan grows older, it seems to become preoccupied with concealment and deception. But sometimes, even during the daytime, the fish leaves its protective cover and rampages, chasing other competitor fish, burrowing for crustaceans, or just playing the town bully. It then vanishes back to its hidden security. And dropping a sculpin or nymph pattern into the fish's path can often trigger a vicious cake.

Green water cress loaded with cress bugs
Large spring-creek trout feed heavily on protein-rich cress bugs (above), shrimp, and other organisms that live among the stream's weeds. (John Randolph photo)

Most spring-creek fishermen are familiar with trout burrowing behavior in taking crustaceans living in elodea and watercress. The trout burrows into the vegetation to shake loose scuds or cress bugs, then drifts downstream and engulfs them as they float by. Large wild fish use this feeding behavior, and hatchery trout, when exposed to the food and feeding in a spring creek, adopt it as well.

I recall an encounter with a big brown on Big Spring in south-central Pennsylvania. This garbage disposal of crustaceans was foregoing the burrowing. Instead, he took large chomps with his hooked jaw directly out of a moss-covered log, engulfing dozens of cress bugs at one time then doing his best to expel moss from his mouth.

After watching in amazement as the fish fed, I noticed chat its chomping was confined to an area of about a square foot along the log. I tried to cast my weighted fly to the choice spot and then let it lie in the elodea, but I scared the trout off to the overhanging willows.

As a result of the dredging by the large brown, a flow of food was created directly downstream of the log. I noticed that an 18-inch wild brook trout had moved from under the willow and had taken up station, feeding feverishly on the dislodged smorgasbord of cress bugs. I took the fish on my first drift.

Approach and Presentation

Most limestoners flow through open pastures, bogs, and lowlands often void of light-shielding trees. Since shadows are frightening to a large, deep-lying trout whose window of vision is maximized by its depth, I confine my trophy-stalking to cloudy days.

Illustration of a trout's field of vision
A trout's cone of vision depends on its depth in the water. (Rod Walinchus illustration)

It's best to move slowly with a low profile, stopping often to watch the water. Train your eyes to detect sub-surface movement and hidden feeding lies. If you find yourself spooking a lot of fish, don't abandon hope. Large trout are accustomed to the hordes of spring­-creek fishermen, and due to the abundance of food, they seldom stay off the feed for long. When alarmed, a big brown will either be spooked or semi-spooked. A spooked fish may bolt downstream or into its prime cover. I have seen fish startled by a sculpin or nymph pattern that had recently hooked them.

A semi-spooked trout often moves slowly upstream as you advance toward it. Sometimes it turns downstream, semi-circling, and then swims back to its original lie. I have often induced such fish to take by plopping a sculpin or nymph to either side or directly in their path.

Look for large-trout lies near obstructions and undercut banks associated with the primary and secondary lies. Bridges, dams, hatch pools, trees, and stumps are ideal spots. Bridges provide a sense of security, protect the trout from sunlight, and funnel the stream' current, thus channelizing the drift.

Undercut banks often go unnoticed by some anglers. Study them carefully. Large boulders and logs, especially near gravel area and watercress beds, provide quick and easy cover for large trout. They use them, particularly in the early morning when they get caught venturing too far from their protective lies. Any obstruction capable of concealing a large fish can provide security.

During the early- and late­-winter months, shallows play an important role in large­trout feeding habits. The abundance of Chironomid and Simulium midge larvae there make these areas irresistible. Sculpins, leeches, crayfish, and dace also like to sun themselves in the shallows during cold weather.

At dam and mill pools, look for undercut concrete or rock ledges that hold big fish. Tree stumps, especially ones next to a primary spring-creek lies, often hold the largest fish in the stream. Large trout sometimes territorially hold such lies and feed in the shallows either above or below. When spooked, they retreat for the security and cover of the stump. I approach stumps carefully so as not to spook fish lying downstream in the shallows.

On large spring creeks, where trout roam more freely, big trout often hold in the shallows and on the far bank, where presentations are difficult. Enthusiastic wading spooks fish on the near shoreline and at mid-stream. Ironically, the place fish feed and concentrate on big, wadeable spring creeks are often determined by how and where fishermen wade.

Sight-fishing for Trophies

Once you’ve learned how to read the water and present the fly to trophy trout, you should spend time locating fish and observing their feeding patterns. With practice, you'll take large fish consistently. Not all choice spring-creek lies hold large trout, and blind-fishing is often unproductive. Sight-fishing is the most productive way to go.

When sight-fishing for a large trout, ask yourself the following questions: Is the trout in a holding lie, a feeding lie, or both? Is the fish actively or passively pursuing food? ls it displaying any rhythm of movement in feeding? Is its orientation toward the surface or the bottom? Can you identify the food the trout is eating?

Concentrate on the fish while estimating where the imitation is at any time. If you can see your fly, rarely the case, it's to your advantage. Since many spring­-creek patterns are difficult to see in the water, you should set the hook at any suggestion that the fish has taken the fly.

Styrofoam strike indicators can increase your perception of a take on riffle waters, but they are often useless on clear, placid spring creeks. On limestoners, trout take long, selective inspections of the imitation, and they accept and eject the offering before the strike indicator moves. Sight-fishing is often the only method that works when fishing these waters with wets.

Learning to recognize the take is often half the battle. Watch for these signs of a take: quick horizontal movements by the fish to either side, forward and lateral; a slow, steady backward glide; quick jaw motion during opening and closing of the mouth (easily detected due to the white mouth of trout); quick pulsating of the pectoral and ventral fin; rapid gill pulsations; quick upward or semi-circular motion by the trout.

Sometimes you must use different methods when sight-nymphing with crustacean or nymph patterns. Large, holding trout that do not display a feeding pattern can often be caught with an induced-take presentation (see Figure 2).

You can create a swimming motion, which resembles the upward movement of an emerging natural, by raising the rod slowly as the fly nears the fish. The same principle is used in the Leisenring Lift. In these induced-take methods the action of the fly can be enough to trigger a response, regardless of which pattern you use.

Illustration of the induced-take presentation for trout fishing in spring creeks
Figure 2. The induced-take presentation can often coax fish into striking a nymph. Cast your nymph upstream of a sighted trout, to give the fly time to sink. Drop your rod tip low as the nymph passes in front of you, then tighten the line and lift the rod tip as the fly approaches the fish. This causes the fly to simulate the upward emerging movement of a natural. (Rod Walinchus illustration)

Trout that show a pattern of taking naturals present a different challenge. When a trout feeds consistently on cress bugs, it often feeds in a narrow lane, a subsurface current created by the friction of water flowing by a moss-covered rock or vegetation. Cress bugs are spun off the vegetation and are carried down-current to the trout.

You must drift your imitation through the narrow, four-inch lane and at the proper depth, and you must do it naturally drag-free. The presentation often rules out the use of split-shot and other drag creators (strike indicators, heavy tippets). Spring-creek trout are wary of split-shot, especially in clear water, so use weighted patterns to get a proper drift speed and neutral buoyancy at specific depths. Carrying several patterns with various amounts of weight in them allows you to experiment as you encounter different flow conditions and trout lies.

When fishing sculpin and leech patterns, remember that sculpin, crayfish, and leeches live on the spring-­creek perimeters. They hide under rocks and vegetation, often near shore and undercut banks, and they rarely cruise down the center of a primary lie. Fishing streamers through the center of a lie often spooks trout. Live sculpins usually scurry, hide and rest, so let your pattern rest on bottom for short intervals, especially if you know that a trout occupies a nearby lie.

I have often seen large trout watch a resting sculpin pattern for several minutes and then smack it as I quickly pulled it away. Sometimes the trout even pulverizes the fly right on bottom, as the marabou fibers pulsate in the flow, making the fly too irresistible for the trout to ignore. By fishing the patterns near rock embankments and boulders, on the perimeters of vegetation, and near the shoreline adjacent to primary and secondary lies (see Figure 1), you can often coax large trout to take. If the trout doesn't take, mark the spot well and return another day.

Persistence and timing, combined with refined trophy-hunting skills, make a deadly combination for success in talking large lime tone trout. To catch such fish demands great skill and concentration. The results are worth the effort.

Fly Pattern Descriptions

Swannundaze Cress Bugs

These two patterns in brown/gray and olive/gray imitate the two most common colors of North American Asellus (Isopoda) found in spring creeks. They are unweighted and are appropriate for the rest-and-drift method of presentation, which is effective on trout cruising over elodea beds in streams and spring ponds. The buoyancy of the Swannundaze allows the imitation to rest lightly on the vegetation, so you can lift it and let it drift. Fish the fly with light tippets and an appropriate split-shot pinched on the leader approximately 18 inches above the fly.

  • HOOK: Partridge John Veniard Grub/Shrimp hook K4A, #18.
  • THREAD: Cream/olive.
  • BODY: Brown/gray: reel fox fur; olive/gray: mix of olive hare's mask, muskrat, and pale yellow dubbing.
  • RIBBING: Fine silver.
  • SHELL: Clear Swannundaze.
  • ANTENNAE: Fine deer-hair tips.
  • EYES: Black ink.
Illustration of a freshwater shrimp, scud
(Rod Walinchus illustration)

Tiny Swannundaze Scuds

The tiny olive and yellow scuds (Hyalella) are the most common in limestone spring creeks. They are weighted and sink quickly into feeding lanes. They have proven effective on limestone trout worldwide. The fine over-body ribbing of 6/0 light olive/cream thread is critical to the fly's effectiveness. The transparent ribbing of the natural is not always best imitated by wire or monofilament, since the natural has a faint olive coloration.

  • HOOK: Partridge John Veniard Grub/Shrimp hook K4A, #18.
  • THREAD: Light olive/cream.
  • BODY: Olive: olive hare's mask (dark) mixed with yellow dubbing; yellow: pale yellow/olive dubbing.
  • SHELL: Clear and light yellow Swannundaze
  • RIBBING: Light olive/cream thread.
  • ANTENNAE: Fine deer hair.
  • EYES: Black ink.

Gray Caledonia Scud (Gammarus)

This large scud, originally discovered at the Caledonia, New York, hatchery is relished by spring-creek trout. However, it is not found in such concentrations as Hyalella. The pattern is heavily weighted for quick penetration into the water.

  • HOOK: Partridge John Veniard Grub Shrimp hook K4A, #14.
  • THREAD: Light olive/cream.
  • BODY: Dark hare's mask.
  • SHELL: Clear Swannundaze.
  • RIBBING: Light olive/cream thread.
  • ANTENNAE: Fine deer hair.
  • EYES: Black ink.

Big Spring Mouse

I designed this pattern, but it could have had its beginning back in the 1800s. George Gibson, one of the first fly-fishing writers, described his success with a similar imitation in the August issue of the Spirit in 1849. While fishing on Big Spring in Pennsylvania, he found himself catching difficult trout on a dry-fly pattern with a thick mohair body. The pattern was initially ineffective; that is, until the wings had fallen off. The mohair (camel) and the red and gray fox I use for the fly have similar appearance. I could only speculate as to why the fly is deadly for large brown trout.

Photo of oval with ridged grooves used to tie Supinski's Big Spring Mouse and Razor-back Cress Bug
A piece of thin plastic cut into an oval with ridged grooves on the outside helps give the author's Big Spring Mouse and Razor­back Cress Bug their distinctive shape. Tie in the weight and apply a base of flex-cement before attaching the shell. (John Randolph photo)

The pattern is only effective with the right thickness or girth of the shell, and with red fox hair. The eye are important; patterns without them do not work as well. The fly must be heavily weighted and allowed to dead-drift along the bottom–preferably on clear sandy patches. Trout chew the fly and try to crack the shell, instead of quickly disregarding it as they do other imitations. The fly does not work nearly as well unless the red-fox guard hairs are plucked out in a "wild" fashion. I have noticed balls of clinging cress bugs or doubles rolling helplessly downstream along spring-creek bottoms. The pattern might suggest them to the trout.

Photo of Supinski's Big Spring Mouse
The author's Big Spring Mouse has its origins in an 1849 pattern. The fly seems to work best when tied with red fox hair. Weight it heavily and include the eyes. (John Randolph photo)
  • HOOK: Partridge Captain Hamilton L3A, #14.
  • THREAD: Cream.
  • SHELL: Thin plastic cut in oval shape, with ridged grooves on outside to hold thread and dubbing (base of flex-cement).
  • BODY: Underlayer of red and gray fox guard hairs, overlayer of fine red/ginger body fur.
  • EYES: Black ink.

Razor-back Cress Bug

Similar to the mouse but smaller, the ridged back duplicates the shell structure of the cress bug. It sinks quickly and takes cress-bug-feeding trout. Tie the fly with a pinkish/gray fox fur and a black ink outline for the shell ridge. Trim it neatly. Sizes may vary.

Supinski's Razor-back Cress Bug fly, held in a vise
The author's Razor-back Cress Bug imitation has a shell of thin plastic cut into an oval shape with ridged grooves on the outside edges to hold thread and dubbing. (John Randolph photo)

Matthew A. Supinski lives in Washington D.C., and frequently fishes the spring creeks of central Pennsylvania and elsewhere. This is his first article in Fly Fisherman.

Cover image of March 1990 issue of Fly Fisherman magazine
This article originally appeared in the March 1990 issue of Fly Fisherman.

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