Bass Vision

Editor Note: From the pages of the July 2024 issue of In-Fisherman magazine.

Bass are effective predators, and vision is their dominant sense for detecting and selecting prey. But bass live in diverse and dynamic habitats where environmental conditions—particularly the amount of light that penetrates the water—change seasonally, daily, and even within a day. To obtain energy essential for growth and reproduction—and, thus, survival—in these conditions, bass have evolved other senses that play a role in feeding: taste and smell, hearing, and detecting water movement with the lateral-line system.

Indeed, bass use the lateral line to detect prey and successfully feed in total darkness. Where light is sufficient, all senses are involved in feeding, but vision is the primary sense; it provides precise, real-time location of the prey (and obstructions to capturing it) and important details about the prey such as type, size, and speed and direction of movement.

A note is in order about what is “sufficient light.” A bass can see at about one-tenth the amount of light we need to see. The depth at which bass has sufficient light to rely on visual stimuli is easily approximated by relying on basic physical laws about light penetration in water. Lower a white object (a spinnerbait or a jig will work) until it disappears. Measure that distance and multiply by four to estimate the depth at which a bass can effectively use vision for feeding. Of course, the clearer the water or the shallower you are fishing, the farther away the bass can see your lure and the better the bass’ visual discrimination.

The biology of bass vision has been well studied and summarized in previous In-Fisherman articles. More details can be found in Keith Jones’ book Knowing Bass and more recent scientific studies, but here are the salient points. Bass have binocular vision and are neither nearsighted nor farsighted. Bass have color vision and see the same colors anglers see, although research at the University of Illinois asserts that bass see chartreuse as white. Different wavelengths (colors) of light are selectively filtered by water, with reds being most attenuated; but in clear water and at depths less than 25 feet where most bass anglers fish, all colors are visible to bass. Bass have an acute ability to detect motion.

Realizing that almost all lures may appeal to multiple senses and may be critical to eliciting a strike, all lures share several visual triggers: shape, size, movement, color, flash, and location in the water column. Dialing in the “right” visual package to elicit a strike can, obviously, be difficult.

Shape

An effective shape often depends on the prevalent forage bass are keying on. Sunfish are deep bodied; yellow perch, minnows, and shiners are slender; and shad are intermediate. Mark Fisher, accomplished bass angler and longtime lure designer for Rapala, emphasized the importance of silhouette in a lure’s effectiveness. Shape is the starting point for lure design according to Dan Spengler, Senior Product Engineer who has been designing and developing hardbaits and terminal tackle for Berkley for 13 years.

The shape must match the profile of the forage but also be hydrodynamically sound. A fat jerkbait, for example, won’t dart. Jose Chavez, Director of Product Development at Z-Man Fishing Products, shared a similar thought. “Form dictates function; you may have to change a shape to get a particular type of movement. There is a lot of give and take. How a lure resembles forage is important, but not necessarily critical.” Indeed, shad-shaped lipless crankbaits catch a lot of bass in northern waters lacking shad, and slender-bodied swimbaits are effective for shad-gorging bass in southern waters. But shape is just one of the visual stimuli involved in feeding.

Size

Size can be a wildcard because multiple species of forage are available in each body of water, and each changes size as they grow throughout their life cycle. For mimicking some forage, a range of lure sizes may be okay, but at times there is merit in match the hatch. This is certainly the case in southern reservoirs in the fall when shad-loving bass are feeding heavily on schools of two- to three-inch young-of-the-year threadfin shad. In these same reservoirs some anglers search for larger age-1 gizzard shad hoping to find bigger bass, but small shad imitations are in order when groups of bass are marauding schools of young threadfin shad. Effectively exploiting the size component of visual stimuli may require knowledge of not only the food preferences of the bass but also the seasonal behaviors of their forage.

Movement

Fish, including prey fish, swim slowly and smoothly with almost imperceptible undulations and rolls of the body. Mimicking these subtle movements likely is why the very first Rapala minnows were so incredibly effective that Lauri Rapala and his hand-carved lures were featured in a Life magazine article in 1962. Rapala minnows still catch fish, but anglers now have a long menu of soft-plastic swimbaits that nicely replicate the natural swim of many forage species and can easily be fished at different depths.

While smooth and steady may be the forage’s usual gait, startled forage fish dart erratically seeking cover. And individual fish in a school occasionally break rank and flash, even when no disturbance seems apparent. Whether forage exhibiting these erratic behaviors actually are more vulnerable to capture, as many anglers surmise, is questionable. But these behaviors likely make the prey more conspicuous and entice anglers to impart irregular movement to crankbaits, spinnerbaits, and other hardbaits, either by deflecting them off cover or by manipulating the rod or retrieve speed, which, in turn, also makes the lures more visible.

The movement or the action of the lure, which is influenced by shape, size, and angle of the bill and pull point, is Spengler’s number-two consideration in designing a lure. A real-world example demonstrates the importance of movement. Berkley tests their lures on bass in a large indoor tank before field testing. One hundred and forty different prototypes of the new Berkley Dime crankbait were tested to dial in what action bass preferred, before field testing began. Very slight differences in lure movement affect bass striking.

Retrieve speed can matter. Cadence—the jerks, twitches, and pauses in the retrieve—is important, too. And retrieve speed and cadence can apply to bottom-fished jigs and soft plastics as well as lures in the water column. Fisher noted that the mood of a bass determines what cadence is effective, particularly with a jerkbait. I’m not a bass psychologist, but it does seem that sometimes bass are more aggressive than at other times. Whether that is the case or not, effective retrieves vary day by day, even within a day.

A forage movement that clearly signals vulnerability to easy capture by a bass is the slow, nose-down sinking of a moribund baitfish. This is particularly common in southern reservoirs where late winter-early spring shad die-offs occur, but I enjoyed a notable early spring largemouth bite in Lake Erie’s Presque Isle Bay with a gold Rapala X-Rap. Although most X-Raps suspend horizontally, the gold X-Rap turns nose down and very slowly descends. Cast, pull it down, wait, watch the line for the slightest tick.

Bass don’t only feed on forage fish swimming in the water column. Some forage remain motionless in vegetation, woody cover, or on the bottom. Crayfish are a dietary staple of both largemouths and smallmouths. Although conspicuous when tail flipping across the bottom, most craws are nearly motionless as they graze on algae and dead plant and animal matter on the bottom. Same for gobies and sculpins. Of course, a crayfish (or a tube, a jig, or other craw imitation) hopping off the bottom is likely to get the attention of a nearby bass. But if you’re trying to mimic a crayfish (or a goby or a sculpin), a lot of deadsticking and dragging is in order. Fisher noted that no motion is a form of movement; and the absence of motion—or maybe the stopping or starting of motion—may, at times, be the best visual stimulus.

Color

Color is, no doubt, an important visual trigger. When I interviewed five accomplished touring bass pros a couple years ago about visual stimuli they considered important in lure selection, only one identified color as extremely important, although a second noted that “hue”—whether the side of the lure is gold or silver or dark—was very important. Regardless of where color ranked among important visual stimuli, all pros agreed that natural colors were the default option in clear water.

But what is natural? B.A.S.S. Elite angler and lure designer Bernie Schultz elaborated on spinnerbaits. The blades get the bass’ attention from the distance, but it’s the body—the head, skirt, and trailer—that the bass now decides is food or not food. Schultz made a strong point that the skirt of a spinnerbait should resemble a forage fish, the basic pattern being dark dorsal, pale sides, whitish belly. Other accent colors can be added to match more specifically the prevalent forage. The same reasoning applies to any skirted bait, from jigs to bladed jigs to buzzbaits.

Schultz makes a compelling argument for hand tying spinnerbait skirts, and it is further underscored by the exceptionally successful bass pros Guido and Dion Hibdon who collected crayfish from tournament waters so they could hand tie jigs to match. Yet, thousands upon thousands of bass are caught on lures with anatomically incorrect multi-color skirts. Chavez noted that a lure has to look right but also must not have any “red flags,” stimuli that put the bass on alert. Apparently, some stimuli, like anatomically incorrect skirts, are not red flags if other stimuli are sufficient to elicit a strike.

Is it the color or confidence? Hardbaits come in dizzying arrays of colors. Add to that the cadre of anglers who insist on having lures custom painted. Softbait colors are even more diverse. Lure makers sell a spectrum of colors because anglers buy them. I have my confidence colors, but I have learned that when a color is hot on a particular fishery, you better have it.

When the water starts warming in the late winter (in the south) or the spring (in the north), red and orange horizontal baits start producing. Why red or orange? I don’t know. I know of no fish that swims in fresh water outside of an aquarium that is red or orange. The crayfish argument just doesn’t hold up; most crayfish are olivaceous (green pumpkin) until they start being digested by a bass, and they don’t swim up in the water column. But you are wise to be carrying red lipless crankbaits and bladed jigs when the water warms to 50°F. Wiser still to be fishing them. The same applies for pink flukes and crazy-colored jerkbaits for smallmouths in many waters.

Flash

Flash happens when direct light reflects off a flat surface. The scales of all scaled fish provide the prerequisite flat surface for at least minimal flash, with flat-sided, silvery fish like shad emitting the greatest flash. But flash diminishes with depth, even in clear water, as light is increasingly scattered and strikes a baitfish or a lure from infinite directions.

Flash is probably best considered, as Schultz noted, an attention getter from a distance, but then something lifelike has to be present to seal the deal. Fisher considers flash a huge factor in shallow water and emphasizes the importance of flat-sided jerkbaits; but he advised the use of flat colors on dark days because chrome turns gray when bright sunshine is lacking.

Spengler also considers flash important but pointed out that flash is not only the glint from mirror-like surfaces. A lure with a dark back and light sides will show flashes of light as the dark top rolls left and right when retrieved, alternatingly hiding the light-colored sides.

Location in the Water Column

Where the bass—and the lure—is in the water column may be the most overlooked visual trigger. I have read many times that bass “feed up” and that lures should be presented at their level or above them. Anatomically, that is valid; the eyes of a bass are positioned on its head so it sees better forward and above than down. But bass are not confined to a horizontal posture. Much more telling to me are the numerous times when a drop-shot with only a 12-inch dropper caught far more smallmouths than a bottom presentation, or vice versa. Twelve inches isn’t a long way off the bottom, and that 12 inches shrinks to 6 or 8 inches when the drop-shot is pitched 30 feet away from the boat.

These occurrences suggest to me that at times bass may be keying on a different foraging window or forage image—something on or among the rocks versus something hovering mere inches above the rocks. Similarly, I’ve had the bite of largemouths on a steep rock-and-gravel bank switch from crankbaits to creature baits fished on the bottom and then back to crankbaits on successive days. The foraging window seems to change.

Winding a lipless crankbait, swim jig, bladed jig, or swimbait so it ticks the tops of weeds will catch a lot of bass, as will selecting a crankbait that runs slightly above the weedtops. In the absence of bass-holding weeds, a jig, soft plastic, or crankbait dragging or banging the bottom is often productive. But forward-facing sonar is proving that many bass suspend in the water column. Whether the habitat is a steep gravel bank, a flat point, a river ledge, or a creek channel, the water column above or away from those traditional fishing targets warrants exploration. For these bass, lures presented at or slightly above them are more effective.

Sum of All Stimuli

A bass relies on input from multiple senses to make a decision to strike or not to strike. To consider only visual cues for feeding or striking is unrealistic for most lures bass anglers fish. But when light is sufficient, visual stimuli provide the most complete and instantaneous information about the bass’ environment and are the dominant source of information about decisions to strike or not to strike. Clearly there are multiple facets to the visual image your lure provides. The challenge to anglers is to provide sufficient correct visual stimuli to elicit a strike with, as Chavez said, no red flags.

Biologists understand well the physiology of hunger, or the urge to eat. I know from my own research that largemouth bass held in laboratory tanks with continuously available bluegill forage consumed a rather stable average daily ration (ADR), measured as percentage of their body weight consumed per day. But importantly, the ADR was stable across a two-week time period; it was not necessarily the amount of food consumed every day. For example, a bass may eat a bluegill on several successive days, then not feed for two days and eat three bluegills on the third day. While the physiology of feeding is understood, what affects the actual behavior of attacking and consuming prey—what Fisher called the mood of the fish—remains unknown.

Can the right suite of visual stimuli—probably coupled with vibration and possibly chemical stimuli—provoke a strike in refractory bass, those bass that didn’t feed for several days in the lab tanks despite available, vulnerable forage? Maybe this is where garish colors, high-speed retrieves, or erratic actions—what some anglers refer to as triggering a reaction bite—become effective. But be consoled—while skipping feeding for several days was common among individual bass in the numerous laboratory feeding trials, at least some of the bass fed every day. On any day, the angler presenting the right combination of visual stimuli in the right place will be rewarded.

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