Pros: Consistent and effective producer, widely available in a variety of sizes
Cons: Must differentiate between Mercer's Epoxy BIOT Golden Stone and Mercer's Poxyback Golden Stone when buying/ordering
First, a little background...
It's interesting that while you can find uncounted numbers of fly-fishing shops which stock his flies and many, many fly-fishers who instantly recognize and depend upon his patterns, Mike Mercer has remained one of those rare, quiet talents who unstintingly share their creativity while remaining below the radar as a "spotlight personality" in the industry. A devoted family man, Mercer has worked for The Fly Shop in Redding, California for over 25 years; first as a young guide, then a retail store manager, and now as a travel expert. Having fished throughout the American West, Alaska, Chile, Christmas Island, the Bahamas, Mexico, Belize, Honduras, Kamchatka (Russia), Argentina, and Canada, Mike has humbled more than his share of fish; not to mention deflated the egos of more than a few dilettantes who mistook his quiet spoken nature for a lack of intensity while angling.
A standing room only lecturer at fly-fishing shows, Mercer has been a fly designer for Umpqua Feather Merchants for quite some time; with 39 pattern variations in the company's 2005 product catalog. He has had articles published in nearly every fly-fishing magazine on the newsstand. But, it was only in August of 2005 that Mike came out with his first, long-awaited book. Published by Wild River Press, Creative Fly Tying details the history, the thought process behind, and tying instructions for a dozen of his patterns; including the Biot Epoxy Golden Stone Nymph. (see link below) Now, on to the fly...
A little lesson in the lingo might help to clarify things a bit; particularly given that, currently, there are three or four variations of "epoxy" or "poxyback" stonefly nymphs by Mike Mercer on the market. The "biot" portion of the name typically refers to the short fiber found on the flight feathers of either a turkey or a goose. Such feathers are dyed in a variety of colors and are readily available in most fly tying catalogs or fly shops which stock fly tying materials. The name "poxyback" or the "epoxy" portion of the name stems from the use of 5-minute epoxy (see link below) to create an hardened "shellback" over the thorax portion of the nymph.
As for "stone" well... Being merciful, I shall dispense with a lecture pillared on Latin, graduate level biology, and the entomology of regional variation. Suffice to say that "stoneflies" (sometimes referred to as "salmonflies" or mistaken for helgrammites) are everyone's image of "BUGS" incarnate. These insects have a three year life cycle, living most of their lives on the bottom of gravelly streams; "residing in the stones" - thus the name. When they are ready to hatch (anytime from about late April through August depending on location) they crawl on the stream bottom to the bank, cling to rocks or streamside bushes, the shell then splits and the winged adult takes flight.
"Stonefly" nymphs can be as small as a size 18 in the Little Yellow Stone, or as large as 6 or even a 4 on a 3X or 4X long hook (each "X" represents the equivalent to the length of a hook's eye beyond the standard hook shank length). That means they can range from about 1/4 or 1/3 inch to as long as 3 inches in size for the Pteronarcys californica. With their three year lifespan, they are ALWAYS available to trout and represent the quintessential "trout food;" i.e., one that provides the fish with high calories with a minimum of effort. In fact, in his seminal work "Nymphs," famed fly-fishing author Ernest Schwiebert flatly claims that the giant P. californica is "the most numerous insect form on our major western rivers." (p. 45)
Primarily found in the well-oxygenated water of fast moving, gravel bedded riffles, imitations of stonefly nymphs generally need to be heavily weighted to get down to the bottom. Again, these insects spend most of their lives clinging to or crawling among stream bottom rocks. And, that is where the fish are going to look for them. This is when the old nymph fishing maxim truly applies: "If you aren't getting hung up on the bottom on a regular basis, you ain't fishin' deep enough." Mercer's Biot Stone Nymphs have lead wire under the thorax (front) portion; and the gold bead version adds even more weight in helping to get it down. However, in faster water, you may still need to use splitshot placed about a foot or so above the fly. Due to this "bottom bouncing," not to mention the often vicious takes, heavier leaders and tippets of 1X to 4X (12lb. - 61b.) are generally used; the heavier leader/tippet also helping to cast these slightly heavier nymphs.
Generally priced between $1.75 and $2 each, Mercer's Biot Stone Nymph comes in two colors, Dark and Golden; both being available with and without a "bead head.". (DO NOT confuse Mercer's Biot Epoxy Golden Stone with Mercer's Poxyback Golden Stone. They are two, entirely different flies.) The Dark version is intended to imitate the larger, dark stonefly nymphs; which often exhibit an orangish, "salmon" color on their underside when they are ready to crawl to the bank and hatch. The Golden variation is for just what it sounds like; an imitation of the slightly smaller Golden Stonefly (although the smaller versions of this nymph COULD be used in an effective, though slightly misguided attempt, to fool fish feeding on Little Yellow Stones - more effectively imitated with Mercer's Little Yellow Stone nymph). As such, the Dark Stone is available in sizes 6 to 12 and the Golden Stone is offered in sizes 8 to 14 from Umpqua; though ALL the sizes may not be available in every store or mail order catalog.
Tied on 2X long nymph (heavy wire) hooks, the nymphs' tail and antennae are imitated using biots. Mercer recommends turkey biots while I personally tend to goose biots for these segments. The abdomen is made by wrapping turkey biots (sulphur-orange, mottled with a brown permanent marker for the Golden and a darkish brown for the Dark) to the midpoint of the hook shank. The thorax is dubbed using Mercer's Select Buggy Nymph Dubbing (available from Umpqua in a variety of colors; Golden Stone and Dark Stone being the applicable ones for this nymph). [This dubbing mix has only been available for the last couple of years and I am still in the habit of mixing my own combination of various dubbing (usually predominantly from hare's ear) to a close approximation of the colors.] Over this dubbing is a wing case of dark turkey tail covered with a coating of Devcon 5-minute epoxy (see link below). The nymphs' prominent legs are imitated by using brown, hen-back feather between the dubbed thorax and turkey feather wing case.
If you choose to tie these flies yourself, there are two things you should bear in mind. When I first started using this fly, I tied it on a lighter wire, 2X long, "dry fly" hook because that's what I had. Of course, I ended up spending a lot of time tying new flies as there was a tendency for the hook point to break off on the rocks I kept hanging up on. Again, this is a "bottom-bouncing" fly. You MUST use a heavy wire hook; it will help the fly get down and will increase its longevity by not breaking off the point as easily. Umpqua offers these flies on the slightly curved, Tiemco (TMC) 2302 nymph hook; and this is the one Mercer recommends in his book. But, the straight shanked, TMC 5262 or the Mustad 9671 will work just about as well and are the ones I have consistently used over the years.
The second "must do" for the tyer is that once you have wrapped the turkey biot abdomen (and AFTER you have mottled them with the brown marking pen on the Golden version), you will need to coat the biots of the abdomen with a good head cement (I and Mercer recommend Dave's Flexament, also available from Umpqua). These turkey biots are NOT the strongest or most durable of tying materials when matched against the vicious takes, the rocky bottoms, and the LARGE fish that like BIG mouthfuls for their dining pleasure. The Flexament coating will add considerable longevity and durability to the body.
There are two Golden Stone nymphs that I regularly rely on in my piscatorial pursuits. One of these is my own design and its variations; one that is a bit bulkier and requires slightly more tying time. The other and, incidently, my FIRST consistently fished stonefly nymph, is Mercer's Biot Epoxy Golden Stone. I fish the non-bead head version in sizes 12 - 16 on 4X-6X tippets. Let's just say that this pattern has accounted for a "few" ... uh ... "nice?" fish. I've even used this fly, out of desperation, in lake fishing for bass; guessing that my success has to do with the bass confusing it for a crawdad/crayfish of some sort.
Although I may still tie it "incorrectly" vis a vis the instructions Mercer placed in his book for the Biot Stone Fly Nymph, it hasn't hurt the design's effectiveness. It works. In the end, that's the best encomium a fly tyer could hope for. It's also the phrase that should say it all when a fly fisherman is looking to stock their fly box.
"Biot" indicates both the materials used AND sounds like the recommendation I give to this fly.
Additional Mike Mercer Patterns Reviewed
Gidget Nymph; Glasstail Caddis Pupa; Micro Mayfly Nymph; Tungsten Caddis Larva; Tungsten Bead (TB) Glint Nymph; Tungsten Bead (TB) P.T. Prince Nymph; Z-Wing Caddis Pupa
Fly Pattern Reviews
A.K.'s Parachute Quill Dry Fly; Andy Burk's H.B.I.; Bird's Nest Nymph; Bivisible; Brassie; Comparadun; Copper John Nymph; Elk Hair Caddis; Gold Ribbed Hare's Ear Nymph; Gulper's Special; The Humpy Dry Fly; Jacklin's March Brown Nymph; Kaufmann's Simulator Nymph; Kaufmann's Stimulator; Krystal Flash Caddis; LaFontaine's Emergent Sparkle Pupa and Deep Sparkle Pupa; Muddler Minnow; Parachute Adams; Parachute Dry Flies; Pheasant Tail Nymph; Prince Nymph; Red Fox Squirrel Hair Nymph; Schroeder's Parachute Hare's Ear Dry Fly; Spruce Streamer; Tim Fox's Poopah; Wooly Bugger; Wulff Dry Flies
Other Reviews Cited Above
Creative Fly Tying by Mike Mercer
Devcon 5-Minute Epoxy