This “paper” is non-peer reviewed and published at the lowest level of scientific literature: A Blog. However, being able to fish almost every day, sometimes questions about what we are doing and why can add to the excitement of fishing. The answer to the question above is somewhere in this “paper”. Feel free to jump to the discussion section if you can’t bear the suspense. Enjoy.
There are no references in this paper as most explanations about the benefits of a flashback on a fly are mostly speculations in Internet posts and books. If there are sources for references then I did not research this topic correctly and fully.
Introduction
For decades the use of flashback materials for the shell back in trout flies has been popular. The reasons proposed were that flashbacks made flies more enticing, either just from the flash or the flash simulating an air bubble from the nymph escaping its shell. The most commonly used pheasant tail nymph on Lewiston Lake is a gold bead flashback pheasant tail nymph. This study was conducted on Lewiston Lake, California, between August 10 and September 3, 2021, and was designed to test the null hypothesis:
Ho: There is no difference in the number of trout hooked between a Gold Bead Flashback PT
nymph and a Gold Bead Non-Flashback PT nymph.
Methods
Thirty one-hour fishing sessions, in sets of two successive hours, were conducted in the afternoons and evenings on Lewiston Lake, California, between August 10 and September 3, 2021. The fly used for each hour of fishing (Gold Bead Flashback PT nymph or Gold Bead Non-Flashback PT nymph) was determined randomly using a generator at random.org.
Lewiston Lake is a tailwater of Claire Engel Lake, locally known as Trinity Lake, in Trinity County, California. Water is delivered to Lewiston Lake from the bottom of Trinity Lake. Lewiston Lake has cold water and produces aquatic life and favorable conditions for trout all year.
The flies used in the study were tied by the author, are modified pheasant tail nymphs, and are shown in Figure 1. Each fly was tied on a barbless (smashed barb) hook, size 16 TFS 2457: 2x strong; 2x wide; 2x short. The tails were Coq de Leon. The bodies were made with brown 6/0 thread wrapped with small UTC gold wire. The thoraxes were made of peacock herl strengthened with thread wraps. Beads were 2.5 mm gold brass beads bought from wholesaleflies.com. The flashback material was UTC Pearl Tinsel Flat Medium. For the rest of this paper references to the gold bead on each fly will be GB.
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Figure 1. Examples of Gold Bead Flashback PT nymphs and Gold Bead Non-Flashback PT nymphs used on Lewiston Lake, California. August 10, 2021 to September 3, 2021.
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The rod used was a 5-weight, 6 piece, 9 weight Redington rod from their Classic Trout series. The reel was an Aventik HVCE Graphite Fly Reel Center Drag System Classic III size 3-4. Twenty pound backing was used with a Scientific Anglers Air Cel Weight Forward 5 Weight floating fly line. The leader was made from 4 feet of 1x Maxima tippet material, tied to 2 feet of 3x Maxima tippet material, ending with a loop and an indicator made from Hareline McFlylon. The tippets were 2.5 to 5.0 feet long made from Rio Fluorocarbon Pro 4x. The flies were attached using Kreh loop knots. The net used was a JTA Products Measure Net. The net had a measuring tape system embossed in the bottom of the net.
Definitions
A BUMP occurred when the indicator twitched on the surface or was pulled under, but no fish was seen or felt when the hook attempt was set. A TAKE occurred when a fish was felt when the hook was set, or seen swimming away, jumping out of the water, or being hooked with up to 3 tugs on the line before escaping. A HOOKUP occurred when a fish was hooked giving 4 or more tugs on the line while being reeled in, but eventually escaped before being landed. A LANDED FISH occurred when the fish was netted and measured. The count of HOOKED FISH consisted of the sum of HOOKUP and LANDED fish totals. Data were analyzed using Chi Square at the 5% confidence interval.
Data Collection
Data were collected using a data sheet (Appendix 1). The number of Bumps, Takes, and Hookups were recorded using a TOPTIE 4-Unit Desktop Tally Counter Counter Clicker with Base. Landed fish and their length were recorded directly on a data sheet. The length of fish was determined to be equal to the last marker passed by the fish, or rounded down to the nearest low whole inch.
Fishing methods consisted of anchoring my 12 foot aluminum boat where fish were active, and if none were active on the surface, fishing would occur at locations known for holding fish. If a fish rose within casting range, I would cast to near the spot the fish surfaced. When no activity was present, casts were made directly in front of the boat, rotating 45 degrees with each cast until a circle of 8 casts were made. When a fish was hooked, I would cast to near the same spot until no more bumps, takes, or hookups were made. Casts were allowed to sit from 30 to 45 seconds, followed by two gentle pulls of the line to give movement to the fly, followed by quickly stripping of the line for the next cast. If fifteen to 20 minutes had gone by without a bump, take, hooked, or landed fish, the boat would be moved towards fish active on the surface or areas known to have held fish.
Three locations were fished on Lewiston Lake during this study: 1) The Rock Pile just above Pine Cove Marina (40.76678, -122.78036); 2) Below the island across from Pine Cove Marina (40.76112, -122.78476); and 3) the Brushpile approximately 1.5 km downstream from Pine Cove Marina (40.75122, -122.78262).
Results
The number of trials for each type of fly, and the numbers of hooked fish are summarized in Table 1. The average length of netted fish were 13.9 inches (N = 37, Range = 8 – 15 inches) for the GB Non-Flashback PT nymph and 13.6 inches (N = 40, Range = 9 – 17 inches) for the GB Flashback PT nymph.
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Table 1: Locations and Number of Fish Hooked Using Gold Bead Non-Flashback PT nymphs and Gold Bead Flashback PT nymphs. Lewiston Lake, California. August 10 to September 3, 2021.
| Gold Bead Non-Flashback | _________________________ | Gold Bead Flashback | _________________________ | |
| PT nymph | PT nymph | |||
| Location | Sessions | Fish Hooked | Sessions | Fish Hooked |
| Marina | 1 | 0 | 1 | 1 |
| Rockpile | 3 | 7 | 1 | 5 |
| Brushpile | 10 | 42 | 14 | 65 |
| TOTALS | 14 | 49 | 16 | 71 |
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The average number of fish hooked per session were 3.50 for the GB Non-Flashback PT nymph and 4.44 for the GB Flashback PT nymph. The differences in hooked fish by fly type were not significant at the 0.05 confidence interval: X2(1, N=30)=0.3352, p>.05. Therefore, the null hypothesis that there is no difference in the number of trout hooked between a Gold Bead Flashback PT nymph and a Gold Bead Non-Flashback PT nymph was not rejected.
The average number of bumps per session were 5.57 for the GB Non-Flashback PT nymphs and 8.13 for the GB Flashback PT nymphs. The differences in bumps per session by fly type were not significant at the 0.05 confidence interval: X2(1, N=208)=0.9291, p>.05.
Discussion
The difference in total number of Fish Hooked between GB Non-Flashback PT nymphs and GB Flashback Pt nymphs being statistically insignificant at 0.05 confidence level means that if the experiment were conducted 100 times, 95 times the results will be close with both GB Non-Flashback PT nymphs and GB Flashback PT nymphs coming out on top many times. It is as if catching fish in this experiment were equal to flipping a coin many times on many days. The number of heads and tails will be different, but never far enough apart to show that the differences are statistically significant (such as using an unbalanced coin).
One factor that may have diminished the effects of a flashback on a PT nymph may be that both flies, GB Non-Flashback and GB Flashback PT’s, had a bright gold bead. The flashback on a size 16 PT nymph has much less surface area than a gold bead. Furthermore, the flashback is only on a portion of the fly while the bead head is nearly spherical, seen from many more angles than the flashback. Therefore, this experiment will be conducted again with dull, black beads used on each fly to limit flash to only the flashback fly.
The use of PT nymphs that had no pheasant tail material was a decision based on the durability of the flies used in this study compared to “real” PT nymphs. Flies used in this study were modifications of The Two Minute Fly Tying: The Pheasant Tail nymph (Cammisa, 2012, https://www.youtube.com/watch?v=GW8ut5oX5cY). Pheasant tail material is not as durable a tail material as Coq de Leon, and not as durable a body material as thread. One to three flies were used each hour due to the hard fighting abilities of Lewiston Lake trout. It was estimated that double the amount of flies would have been necessary for the study if pheasant tail was used in the flies of this study. The choice of thread body PT nymphs was made due to financial and durability considerations.
APPENDIX 1: Data Collection Sheet
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Trial___ Fly____ Date______ Weather____________ Time_____ Location___________
Bumps____________ Takes____________________ Hookups____________________
Landed _______ _______ _______ _______ _______ _______
Landed _______ _______ _______ _______ _______ _______
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Trial___ Fly____ Date______ Weather____________ Time_____ Location___________
Bumps____________ Takes____________________ Hookups____________________
Landed _______ _______ _______ _______ _______ _______
Landed _______ _______ _______ _______ _______ _______
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Trial___ Fly____ Date______ Weather____________ Time_____ Location___________
Bumps____________ Takes____________________ Hookups____________________
Landed _______ _______ _______ _______ _______ _______
Landed _______ _______ _______ _______ _______ _______
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Trial___ Fly____ Date______ Weather____________ Time_____ Location___________
Bumps____________ Takes____________________ Hookups____________________
Landed _______ _______ _______ _______ _______ _______
Landed _______ _______ _______ _______ _______ _______
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APPENDIX 2: Typical 14 inch Lewiston Lake Rainbow Trout
