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Imitating Forage Fishes for Big Predators

This post will largely link back to a post I wrote some time ago about forage fishes for trout to musky and I am finally getting back to writing about tying for different body types.

Let's start with fish body shapes. After all, if we are going to imitate forage fishes, their shape - length, width, and height - is probably the most important thing to imitate. There are a lot of different ways to quantify and describe fish body shapes.

Image from Riddin et al. 2016; Creative Commons.

Probably the most technical of the ways to quantify fish body shape is through truss building using a landmark system. Landmarks tend to be origins and insertions of fins and other such easily replicated locations. Without getting to into the weeds, trusses typically are analyzed using multivariate statistical techniques such as principle components analysis (PCA) which uses the relationship among variables - in this case landmark distances - to extract meaningful axes that explain the general trends in the data. We typically do this to talk about differences among closely related groups. However, we can group fishes that share similar shapes that may not be all that closely related. As humans, we love to classify and categorize things...

This is but one way to classify fish body shapes - this one is based on their crossesctional areas. Most fishes are fusiform however some fishes - like Bluegill and other Lepomis species - are more compressiform. And because these are broad categories, many fishes fit somewhere between these broad categories.

Yet another way to classify fishes by shape - like I said, we humans like the categorize things. The top row categorizes their length to depth ratio and the bottom row is more of a crosssectional view. To put this shapes with forage fishes for large predators like pike and musky, sunfishes (Lepomis spp.) are deep and compressed - one of the harder shapes for fly tyers to effectively imitate. Most suckers (Catostomidae) have a moderate depth to length ratio and are generally somewhere between round and slightly compressed. And many minnows (Cyprinidae) have more elongate bodies such as the Notropis shiners, whereas others tend towards a more moderate depth to length ratio.

Hornyhead Chub
Hornyhead Chub - a common minnow (Cyprinidae) of small to moderate sized rivers. This species has a moderate depth to length ratio with a slightly compressed cross-section.

Body shape tells us a lot about where fishes live (Chan 2001). Fishes are strongly gape limited - meaning that they can only eat what they can fit in their mouths. Fishes with strongly compressed bodies have effectively increased their depth which greatly limits the number of predators that can eat them. However fishes with strongly compressed bodies are generally poor at navigating currents and are best suited for lakes, reservoirs, and slower streams and rivers. While suckers with moderate body depth to length ratios and generally round to slightly compressed bodies - and most importantly soft fin rays - are a favorite food of pike and musky.

Pumpkinseed - a Lepomis sunfish - is an example of a deep and compressed fish body shape.

Data on diets of Muskellunge are largely from lakes which offer a generally different community of forage fishes to musky. In Wisconsin lakes, Yellow Perch (Perca flavescens) and White Suckers (Catostomus commersonii) were the most represented in musky diets whereas black basses (Micropterus spp.), Northern Pike (Esox lucius), cyprinids (minnows), and Walleye (Sander vitreus) were poorly represented in musky stomachs (Bozek et al. 1999). Of musky with items in their stomachs - across all lakes only about 34% of musky had food in their stomachs. And 74% of those musky had only one item in their stomachs and 90% had 1 or 2 items (Bozek et al. 1999). This suggest that the old adage that musky will eat large prey items and do that rather rarely hence being the fish of 10,000 casts. In a Minnesota study (Herwig et al. 2022) found that in lakes with Cisco (Coregonus artedi), 50% of musky diets consisted of Ciscoes and there was relatively little diet overlap with Northern Pike and Walleye.

The above figure is from a Gaeta et al. 2018 article titled, "Go big or … don't? A field-based diet evaluation of freshwater piscivore and prey fish size relationships" from the Public Library of Science (PLoS ONE). For Muskellunge, a 1 meter long (1,000 mm or about 39 inches) musky's median prey size is a bit over 200 mm or 20% of its body length. Note that fish weights generally increase to the power of 3 so a prey fish 20% of the length predator's body length is nowhere close to 20% of the predator's body weight. You will also note from that panel that musky are more likely to eat larger fusiform prey than they are to eat laterally compressed prey of similar lengths. This is a good bit of evidence for gape limitation in fishes. Northern Pike of similar lengths are likely to eat much smaller prey items compared to musky. In the Susquehanna River in Pennsylvania, Muskellunge over 60 cm (about 24 inches) switched from eating several minnows to eating larger prey like suckers (Deutsch 1986).

Lastly, before we get into tying forage fish body shapes since we are on the topic of muskies - there is no evidence that have an effect on other game fishes where they have been introduced and stocked (Knapp et al. 2021). In particular, Minnesota anglers were convinced that musky were negatively impacting Walleye populations which the study shows no significant changes in populations or Walleye size (Knapp et al. 2021). In fact Walleye catch rates were higher after musky stocking - but those differences were not statistically significant.

Tying Forage Fishes for Large Predators

First, in total transparency, I really enjoy tying musky flies but I don't really fish them. Yeah, I know but I live in the Heart of the Driftless and that is how I spend most of my time, chasing trout. So my experience in what it is musky really want is quite second hand.

String of predator flies
Predator flies for decorations - that's one use for them.

That said, bucktail is probably my favorite single material and I have a fly shop's worth of it. Most of these flies are going to involve bucktail since it is so versatile and using the proper location on the bucktail and tying techniques will allow you to tie nearly every shape of baitfishes with bucktail.

From the Gunnar Brammer video above, does a nice and simple job of explaining the parts of a bucktail and how they behave differently and are useful for different tying applications. The closer to the body, the more hollow the hair will be and the more it will flare and the closer to the tip, the less it will flair and it more useful for tails, bucktail jigs, and Clouser Minnows. Below are a number of links to Gunnar Brammer videos showing some of these style of flies and techniques.

Finding quality bucktail has gotten a lot easier in recent years but different tails will be useful for different purposes. And before I move on, aside from Gunnar Brammer whom I think has some of the best, most useful YouTube videos, there are other channels to check out like Paul Monoghan, Fly Fishing the Ozarks (Brian Wise), and a host of others have great videos on how to tie large predator flies. I will link a few videos in a range of patterns below.

The video above does not do much to explain what and why they are tying in bucktail. Bucktail basically allows you to tie any shape if you modify the pressure, where the hair is applied, and where the hair is taken from the bucktail. In the video above,

  • Straight Tie - best for tails or for when you want a more elongate

  • Reverse Tie / Fake Hollow - a bit more flair then the straight tie.

  • Hollow Tie - a method to create a fly with a lot of inherent movement and bulk without much weight

  • Bulkhead - a finishing technique to create a head that will push some water but creates a moderately bulky head

  • Reverse Bulkhead - a generally cleaner version of the bulkhead with more flair and a bulkier head than a standard bulkhead.

  • Buford Head - not in the video but a bulkier head that pushes more water. (Paul Monoghan video)

Types of streamers are often broken into three categories. For two different takes on the types of streamers, read the story by Streamer Fishing and Hatch Magazine.

Body Shapes

Probably the easiest to tie shape is the rounded, non-compressed body shapes - and probably the most difficult to execute are the more horizontally compressed forms. Though I will say that all of these flies require a bit of planning and thought. To tie a round fly, you have to think about how the fly is going to taper.

Since this is getting on the longer side of my posts, I am going to keep this part full of videos and sparse on commentary. The fly above is a fairly laterally compressed fly, largely by how the head is shaped because of the eye.

One way to achieve a more laterally compressed body form is epoxy, UV resin, or other glues that hold the shape. This is often more easily accomplished with synthetic materials like craft fur, streamer "dubbing", and other materials.

This fly is largely tied "in the round" by flaring bucktail evenly around the shank and the body taper is achieved by the selection of bucktail fiber length.

Another "in the round" streamer, this time using synthetics rather than bucktail.

The flies above this one may push some water but they would be considered swim flies. The Buford is your protypical push fly with a large head that is used to create movement in the back 80% or so of the body though the effect of the head on water movement around the fly.

Another way to create a push fly - this one uses braided tubing to push water. Other methods for creating push heads have been spun or stacked deer hair, pusher disks, foam, and I am sure plenty of others.

Depressed / dorso-ventrally flattened provides many of the same challenges that laterally compressed flies do.

The Wrap-Up

I fully admit to a few things here: 1) I cut the end short and used a lot of videos - a feature, not a flaw, I think, 2) I am not an expert on muskies or musky fishing but a lot of the same techniques are used on trout and bass flies, just on smaller flies, and 3) I have barely scratched the surface here. Part of what interests me to streamer tying is the amount of innovation occurring is so great. There are so many new materials, techniques, and fly patterns.

Hopefully there is a thing or two (or three) that you took from the post. Comments are always welcome.

Literature Cited

Bozek, M. A., Burri, T. M., & Frie, R. V. (1999). Diets of muskellunge in northern Wisconsin lakes. North American Journal of Fisheries Management, 19(1), 258-270.

Chan, M. D. (2001). Fish ecomorphology: predicting habitat preferences of stream fishes from their body shape. Virginia Polytechnic Institute and State University.

Deutsch, W. G. (1986, January). Food habits of Susquehanna River (Pennsylvania) muskellunge. In Proceedings of the Pennsylvania Academy of Science (pp. 169-173). Pennsylvania Academy of Science.

Gaeta, J. W., Ahrenstorff, T. D., Diana, J. S., Fetzer, W. W., Jones, T. S., Lawson, Z. J., ... & Vander Zanden, M. J. (2018). Go big or… don't? A field-based diet evaluation of freshwater piscivore and prey fish size relationships. PloS one, 13(3), e0194092.

Herwig, B. R., Zimmer, K. D., & Staples, D. F. (2022). Using stable isotope data to quantify niche overlap and diets of muskellunge, northern pike and walleye in a deep Minnesota lake. Ecology of Freshwater Fish, 31(1), 60-71.

Knapp, M. L., Mero, S. W., & Staples, D. F. (2021). Are Muskellunge affecting fish communities in waters where they have been introduced? A re‐examination of Minnesota’s stocked Muskellunge waters. North American Journal of Fisheries Management, 41(1), 229-241.

Riddin, M. A., Bills, I. R., & Villet, M. H. (2016). Phylogeographic, morphometric and taxonomic re-evaluation of the river sardine, Mesobola brevianalis (Boulenger, 1908)(Teleostei, Cyprinidae, Chedrini). ZooKeys, (641), 121.

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