Sensory Muskies

Imagine if the sounds and vibrations produced by your favorite lure were silent to muskies below the surface? What if vibration itself played little role in the hunting and feeding behavior of these mighty green fish? Such importance has been placed on the vibration factor in lure design that sales of blade-adorned muskie baits have dwarfed all other categories this past decade. But is it vibration (sound) that's made these big bladed lures so successful? Or could other factors such as flash, speed, profile, or color trump vibration? We've regularly reported that most freshwater fish hear at low-frequency vibrations up to about 1,000 cycles per second (Hz). Pike and muskies detect sounds that resonate at less than about 400 Hz. Muskies and other fish use the lateral line to orient themselves to their environment, and to detect other fish at close range. But how well can they detect the vibration patterns of certain lures? Do these lures even resonate at ranges that can be detected by muskies?

Two recent studies shed light on the extraordinary and unique sensory system known as the lateral line. Dr. Horst Bleckmann, zoology professor at the University of Bonn, Germany, reported a host of intriguing findings. Among them was that blind cave fish use lateral-line information to build spatial maps of their surroundings.1 More applicable to muskies, he wrote that benthic and pelagic fish use the lateral line to sense water motions (oscillations) made by other animals, and can use the information to localize the source. Bleckmann reports fish can even detect the direction of movement and the velocity at which an object (another fish) is traveling. This relates to the concept of "fish footprints," and the ability of predators to detect hydrodynamic oscillations and distinctive signatures left by the swimming motions of specific fish.

It's important to understand vibration and the frequencies at which most fish operate. Bleckmann noted that most fish and other swimming animals produce movements below 10 Hz. The oscillations left in the wake of swimming movements, however, occur at up to 100 Hz. Muskies and other fish can detect these movements quite well, even though we don't know the effective distance from which the lateral line operates (Can a muskie hear or feel a cisco swimming from 5 feet away? 50 feet?)

Relative to lure design — particularly the popular in-line spinner — to our knowledge, no manufacturer has measured the dominant frequency of sounds given off by the lures they make. For instance, we don't know for sure that in-line spinners produce underwater frequencies that are detectable by the sensory systems of muskies. Thus, the belief among anglers that big-bladed spinners work so well because of their "intense vibration" is no better than an experiential guess.

One intriguing resource is the website of Mepps Lures (mepps.com), which offers the actual underwater sounds produced by their various lures. As specific frequency values aren't provided, each sound pattern is open to interpretation, but the low versus high "pitch" produced by certain blades is perceptible and fascinating to hear. Among five of the company's muskie baits, the #7 French blade on the Magnum Musky Killer gives off perhaps the deepest thump and lowest frequency sound of the group. It also appears that pitch is closely related to the rate at which the blade pivots around the shaft. Take a listen and draw your own conclusions.

If one wanted to know the specific frequencies of various lures, measuring these sounds wouldn't be difficult. This was undertaken by a group of university researchers many years ago, who used a hydrophone and computer software to measure dominant frequencies given off by crankbaits. Of note, just 3 of 23 lures tested produced a dominant frequency under 1,000 Hz.

Sight, Sound & Research

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What we know for certain about muskie feeding behavior is that vision is the most important sense used for hunting, stalking, and striking prey. This conclusion was affirmed in a study by Dr. John New of Loyola University, in which the roles of visual and lateral-line sensory systems were evaluated relative to strike and feeding behavior.2 New and his colleagues determined that muskies use vision almost exclusively for the initial detection of preyfish from afar. Once baitfish were sighted, muskies nearly always entered the familiar slow stalk sequence. And when they passed within a few inches or less, the fish would then use both vision and the lateral line to orient themselves at an optimal distance and angle, and finally issue a forceful lunge toward the preyfish.

The research revealed that blinded muskies that possessed normal lateral-line function showed no outward physical signs of remote prey detection (including no stalk sequence). Only once the baitfish passed within a few inches of their head did these muskies strike. Conversely, muskies with suppressed lateral-line function but normal vision showed almost no limitations in long-range detection, stalking or strike success, relative to the control group, which possessed both normal vision and lateral-line sense. The lateral-line-suppressed group displayed a slightly higher success rate in striking at and capturing prey than the control group.

Despite these findings, most scientists (and many anglers) believe that the lateral line and inner ear of fish function as distance receptors, allowing them to detect acoustic signals lying a distance from the source. According to Dr. Keith Jones and his book, Knowing Bass, however, the lateral line of bass is only effective within a few body lengths of the sound's source.3 Beyond this range, the lateral line's acuity drops, at which point the inner ear becomes the primary sound receptor. Moreover, in shallower water, where most anglers cast for muskies, low-frequency sounds fade fast, particularly vibrations near the surface. However, in deep water, especially over a soft bottom, a broader spectrum of sound frequencies are broadcast greater distances. Further obscuring the pure signals of baitfish and lure sounds is background noise. In high traffic waters, food-linked vibrations can be quickly canceled out by a thousand other artificial sounds.

Spinner Sound vs. Spinner Sight

Despite evidence suggesting that relative to vision, sound may be less important to muskies at longer ranges, most anglers believe in the power of vibration. While it's rarely wise to discount field observations and intuition, the findings described above may serve as motivation to lean more toward the vision factor, particularly as it relates to choice in spinner blades.

Legendary muskie angler Mark Windels has long pointed to the power of sight-attraction, yet also remains a steadfast believer in vibration. Almost 40 years ago, Windels introduced the Musky Harasser — an in-line blade design that continues producing muskies at a steady rate of success. "I always felt it was important to fish with a bait that was a little harder to retrieve," Windels recounts. "I like something that offers resistance and bucks the water when you pull it along. If there's no work involved in the retrieve, there's no disturbance being given off­ — no underwater sound signature. But the lure's visual signature is equally and perhaps even more important than its vibration.

"On the Harasser, I like the #8 French blade, which provides a perfect compromise between thump and visual attraction." On a sliding scale, narrower willowleaf, French, and Indiana blades rotate increasingly father from the shaft. Particularly in high sun, light reflects well off tight-spinning blades, producing ample flash. It's tempting to say that willowleaf blades produce higher-frequency vibrations that fall outside the hearing range of muskies, whereas slower spinning Colorados more likely give off a lower frequency muskies might hear. But we don't know for sure where each blade falls on the sound scale. And retrieve speed should be a factor as well.

Windels choice of a #8 French blade is a compromise between highly visible flash, water resistance, and rotation speed, which may be a function of vibration. Since we don't know which blade produces the sounds most perceptible and appealing to muskies, we lean heavily on intuition and experience.

"For me, the visual factor in blade selection is huge," Windels says. "When I pull a lure through the water, I want to be able to see it. I want something that looks good in the water. If it looks and feels right, my confidence in it soars. Conversely, if it doesn't spin correctly, doesn't pull back when I retrieve it, if the blades don't start easily, my confidence goes down and I won't fish effectively."

Windels adds: "Anglers always emphasize speed. But more speed isn't a cure-all. Its main value is in triggering strikes. Too much speed at the wrong time can be a problem, especially in tough conditions or dirty or cold water. With a bait like the Harasser, I can adjust speed in and out of a figure-eight. That's key. I'm not sure those giant double Colorado bladed baits perform quite so well in the 'eight.' But with a well-made bait with narrower blades, which turn freely at any speed, I can go from slow in the corners to extra fast in the straightaways and never worry about an interruption in rotation, pulse, or flash."

Another advantage to fishing a bait with narrower blades is versatility, he says. "When I fish a reef, I want to work the whole structure. Usually, on one side of the structure, you're casting into the wind — and that side could be holding active fish. So you need a bait that's compact, relatively heavy, and aerodynamic enough to cast distances into the blow. The last thing you want is to get to the good water and then be limited because your bait can't reach the sweet spots.

"If I'm fishing off the back of the boat with a Harasser while the angler in the front is casting a double #10 Colorado, I'm still likely to catch more fish because I'm covering more water and getting in twice as many casts. I also like the narrower French blades because they can be fished in deeper water, as opposed to big Colorados that work best up high. It's nice to have the flexibility to fish fast over shallow cabbage, or deeper along an 8-foot rock spine all with one lure. Baits with heavy yet narrow blades get down fast and stay down, even with a moderately fast retrieve. And the flash they offer gives me confidence that muskies can see and track them from a distance."

Relative to flash, sight-attraction, and perhaps vibration, the addition of a simple plastic twister tail often provides attraction and can trigger more fish. While dressing a hook with a plastic body isn't a new idea, it's becoming increasingly important to many anglers. Esox Assault Tackle (esoxassault.com), for instance, offers what they call Killer Tails. A special hook slot allows the plastic bodies to be easily rigged on a treble hook and makes a nice visual addition to almost any in-line spinner. Employing these often brightly colored, thumping or gyrating tails plays on intuition. We "think" it offers extra visual appeal and perhaps vibration, so we add it to our presentation.

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Factoring Blade Thickness

From the expanses of Georgian Bay, Ontario, guide and lure artisan Johnny Dadson says, "In clear water, muskies use vision to identify prey from long distances. Once they close in on a baitfish, they use their lateral line to lock in and strike. Conversely, in stained and tannic water, they rely more on their lateral line to locate prey, and then at close range, sight helps them seal the deal."

Dadson, who produces a line of in-line spinners (dadsonbladebaits.com), remains a lifelong student of muskies, blades, and vibration. While many anglers consider blade shape and size, he also recognizes the importance of a blade's thickness. "Most metal muskie blades today are .018-, .025-, or .040-inch in thickness. Size being equal, a .018-inch-thick blade pulls the hardest through water and perhaps offers the highest frequency. This gives thinner blades more 'lift' and makes them a good choice for working higher in the water column, say just above shallow vegetation."

The drawback, he says, is that "the force created by two #10 Colorado blades eats through the metal at the clevises, and you eventually end up losing a blade. Thinner blades eventually warp from water resistance, so it's best to stick with smaller sizes, such as a #5 or #6 Colorado or a narrower Indiana, French, or willowleaf which have less pull."

At the opposite end of the spectrum, he says that .040 blades are underutilized by most anglers. "The thick .040s shine for slow-rolling. When we're targeting muskies holding on deep structure, a .040 blade is perfect. It's durable, pulls easily, and works well in deep water, especially when retrieved slow and steady."

The most popular blade thickness today is a .025, Dadson says. "The .025 blade is comfortable to fish. It's holds up to extensive fishing. But most important, it seems to hit a specific pitch that big muskies favor."

Last spring, Dadson teamed with guide Mike Hulbert to craft 10 prototypes of a new bait they named the 9mm Bullet. Each was built with minute design differences, including size, style, and placement of blades, wires, skirting, and hooks. Among the 10, a singular combination emerged. The anointed bait, which they named "Snooki," produced 8 fish over 50 inches for Hulbert, including massive 57.25- and 56.75-inchers from Lake St. Clair.

The winning version of the 9mm Bullet consisted of .025 double #9 Colorado blades circling a .62-gauge wire shaft, and dressed with tufts of tinsel. Dadson and Hulbert believe the blade spacing on the shaft "calls" large fish by stimulating their lateral lines. If sales of the new lure are any indication, they may be right.

And who's to say? While science sometimes says one thing, our experience and intuition often tell us something else. Like legends and world records, one day, relative to lures, lateral lines, and muskies, all may be revealed.

1. Bleckmann, H. 2008. Peripheral and central processing of lateral line information. J. Comp. Physiol. 194:145 — 158.

2. New, J. G., L. Alborg Fewkes, A. N. Khan. 2001. Strike feeding behavior in the muskellunge, Esox masquinongy: contributions of the lateral line and visual sensory systems. J. Exp. Biol. 204:1207-1221.

3. Jones, K. 2002. Knowing Bass: the scientific approach to catching more fish. The Globe Pequot Press, Guilford, CT.