From The Archives -- Anglers tend to favor green, clear, brown, or high-visibility lines for various fishing tasks. Still, we know of no valid scientific tests on the differences in catchability associated with the use of variously-colored lines.

Scientists* have shown that largemouth bass react differently to Berkley 8-pound-test monofilament line in white (unpigmented), fluorescent white, fluorescent yellow, optically brightened green, and blue-green. Juvenile (8- to 10-inch) bass saw and reacted differently to live worms attached to lines of each of these colors. Fluorescent yellow was the color most easily identified and learned. The slowest learning involved comparison of white and fluorescent-white lines. Still, all line colors were visible to bass in clear water.

Which line's least likely to trigger an avoidance response? Fish can learn to avoid or seek anything they see and associate either with danger or food. Nevertheless, we continue to catch fish, suggesting that the line-avoidance lesson isn't easily learned.

Clear lines appear to human eyes as white. Even fluorocarbon leaders are whitish and slightly visible in clear water. Non-fluorescent green lines tend to fade into greenish backgrounds underwater. Brown and black lines fade when backgrounds are brown and black. Still, dark green line is visible against light backgrounds, as is black line.

Background color, not just water clarity or hue, affects line visibility. These are human visual responses, however, and may not be what bass, walleyes, or other species see.

Human color vision is based on three sets of color-sensitive cones, while walleyes apparently use only two types of cones, orange and green. Thus, green may appear brighter to walleyes than other line colors, even though we don't see it that way. Anglers gain confidence from any reduction in line visibility.

Ideally, an angler should have reels spooled with lines of different colors, making adapting to existing conditions easier. Gray-green line, though, fits many, if not most, fishing conditions, so many anglers compromise with this single line color. If visual detection of light strikes is critical, a high-visibility line may increase hookups even if fish see the fluorescent line more easily.

The test is whether we catch more fish using a variety of colors of the same diameter. Hundreds of fish catches under controlled conditions are needed to make scientifically valid comparisons. Most anglers have only casual opinions based on fishing experiences in random conditions. Valid tests can't be accomplished during normal fishing, when variables affecting fish catches are too diverse.

*Miller, R. J. and F. T. Janzow. 1979. An experiment on visual discrimination in the largemouth bass, Micropterus salmoides. Proc. Okla. Acad. Sci. 59:34-40.