February 19, 2020
Think about the choices you make every time you tie a bait onto your line: Topwater or subsurface? Hard lure or soft? Aggressive action or subtle? After these questions are answered, the internal debate shifts to color. Indeed, picking the best lure color can be as agonizing as any other bait-related choice, and the decision is frequently dominated by personal preferences and experiences. But what does science say?
Somewhat remarkably, biological research into largemouth bass color vision extends all the way back to 1937 (“Responses of the largemouth black bass to color,” by F.A. Brown Jr.). In this initial study, bass were trained with the help of food rewards to approach different colored targets, including red, yellow, green, blue, black and others. The results of this 80-plus-year-old work revealed that bass can distinguish between red and green. Pretty remarkable findings, given that anglers chasing bass in 1937 were using bamboo rods and carried rusty, all-metal tackle boxes!
Fast-forward to the 21st century. Science knows a lot more about bass vision than we did in the late 1930s. Much like human eyes, bass eyes contain different kinds of photoreceptor cells called rods and cones. Rod cells provide bass with visual abilities under low-light conditions and at night, but do not contribute in a significant way to color vision. Cone cells, on the other hand, are sensitive to specific colors. Humans, for example, have three different kinds of cone cells, with one type responsive toward red, another toward green and a third toward blue. Thus, humans have trichromatic vision, which is eye sensitivity to three different colors, and their many shades and combinations.
New research on lure color
Now, university researchers in Illinois and New York have found that largemouth bass eyes contain only two different kinds of cone cells: one that is sensitive to green and another that responds to red (“Seeing red: color vision in the largemouth bass,” by L.D. Mitchem, et al.). Thus, bass have dichromatic vision and are responsive to a range of colors that is more limited than the array recognized by humans. Yes, it’s no great surprise that the bewildering multitude of lure colors we see in any tackle shop is designed to appeal to anglers as much or more than the fish they pursue.
This research team also performed detailed behavioral analyses to determine how bass respond to different color stimuli, and also how well bass can differentiate between closely related colors. In these experiments, groups of juvenile largemouth were trained to attack a target with a specific color (red, green, white, chartreuse, blue or black) and rewarded with a food item when the correct color target was selected. This work revealed fish trained to attack either red or green exhibited a high degree of color selectivity: Red targets were chosen correctly more than 80 percent of the time, and green targets were chosen correctly almost 75 percent of the time. On the other hand, bass that were trained to attack blue targets would do so 48 percent of the time, but they also attacked black targets nearly 40 percent of the time. Likewise, bass that had been trained to attack white targets would indeed select white 33 percent of the time, but these fish would also select chartreuse 30 percent of the time.
What does a bass see?
What do these results mean? The cellular composition of the largemouth bass’ eye is tuned to respond to two colors: red and green. Bass can see these colors well and make decisions with high selectivity based on these colors. Outside of red and green, many dark colors appear quite similar to bass, which are unable to make highly selective decisions based on such colors like blue and black. Likewise, bass cannot readily distinguish between very bright colors like chartreuse and white.
Now it’s time for a grain of a salt, or rather, some context for the science. These experiments were performed in clear, well-filtered water, conditions that are not exactly representative of every single body of water where largemouth swim. We might imagine conditions under which the color selectivity of bass in cloudy or turbid water might be significantly different from that observed in clear water. Also, the behavioral studies used bass that were 8-12 inches in length, and it is possible that color perception may change with age. The investigators noted they assumed the color selectivity of their juvenile fish matched that of adult bass. Nevertheless, even with those limitations, the biological and behavioral studies could have broad impacts on bass fishing.
For me, these results will help to organize my bass lure collection into four basic colors: bright (white and chartreuse), green, red and dark (blue, brown, black). That white spinnerbait with a few chartreuse strands in the skirt is all white to a bass. And what about my collection of black-and-blue jigs? Might as well throw them in with the all-blue and all-black jigs, because to a bass, they likely all look the same, at least in terms of color. I think lures with obvious contrast between colors that bass can easily observe will remain important: baits like red cranks with black vertical bars, or bright jerkbaits with dark backs. But now, every shade of blue and purple doesn’t need to be stored separately—science says bass likely see them all as the same.
Color is an obvious factor when choosing a lure. Let your experience be your guide, but listen to the science, too. Bass see colors as bright, green, red and dark—and that’s about it.
Want todig deeper into the science of bass color vision? Put your lab coat on and read these two studies for yourself:
“Responses of the largemouth black bass to color,” by F.A. Brown Jr., Illinois Natural History Survey Bulletin (1937), volume 21, pages 33-55; and “Seeing red: color vision in the largemouth bass” by L.D. Mitchem, S. Stanis, M. Zhou, E. Loew, J.M. Epifanio and R.C. Fuller, Current Zoology (2019), volume 65, pages 43-52, academic.oup.com/cz/article/65/1/43/4924236.