Have you ever wondered how trout see and if they actually perceive color in their underwater world? Trout have eyes that differ from ours in two important ways. First, they focus on an object by adjusting the distance of the lens from the retina, rather than by changing the shape of the lens as in our eyes. Secondly, trout have little or no ability to regulate the amount of light entering their eyes, while we can do this by changing the diameter of the pupil (and squinting). Sharks and their relatives are one of a limited number of fish groups that can also contract their irises to control light entry as we do. Trout, with their relatively large pupils, tend to avoid areas with high light concentrations—an important consideration for anglers. I’ve noticed in several of my trout photos in brightly lit conditions that their eyes are rotated downward—it’s the best they can do in that situation given their lack of eyelids and adjustable pupils!
Trout (along with most other fishes) can see and respond to color, such as when choosing food. Color vision helps distinguish prospective food items from the streambed or the surrounding water. In an interesting set of lab experiments using colored trout eggs (summarized by Willers 1991), rainbow trout were found to have color preferences related to the color of nearby objects and the background, to light intensity, and to previous experience. For example, with natural lighting and a pale greenish-blue background, egg color preference (in order) was blue, red, black, orange, brown, yellow, and green. However, at lower light levels, color preference was yellow, red, blue, and black. Some color combinations (e.g., yellow/black, yellow blue, and red/orange) produced high consumption rates while others (e.g., red/green) had the opposite effect. With other background colors, eggs of a contrasting color (e.g., yellow on red, red on yellow, and red on black) were generally preferred.
The take home message here for anglers is not necessarily what colors are best to use, because the preferences listed above could differ for other species and under the almost infinite variety of conditions that could possibly occur. Rather, the important concept is that color can affect food choice and consumption rate. Consequently, it would be wise to be prepared with a variety of colors and color combinations and then to make changes as necessary to catch or continue catching fish. Such changes may need to occur as lighting, water clarity, streambed composition, and other conditions change. Generally, “warmer” colors such as reds and oranges are less visible at greater depths or lower light intensities (e.g., at dusk and dawn), while yellows, greens, and blues are more visible under those conditions. Fluorescent colors show up well against a wide range of backgrounds or light intensities and trout are particularly attracted to these. Black can also be quite effective at times because of the especially distinct silhouette it provides. So, a trout angler can reasonably expect that lure color will matter at some point on most outings.
Reference: Willers, B. 1991. Trout Biology. Second edition. Lyons and Burford Publishers, New York.
< back to experts corner