What do fish see?

By DENNIS APRILL, Outdoors Columnist

The first time I saw a black Jig-N-Pig many years ago, I wondered what fish would go after such a silly looking thing. Years later, I watched an experienced bass angler land a good-sized largemouth bass near a Lake George dock using almost exactly the same lure. Apparently that black ball with plastic fringe looked good to the bass.

Since then I have looked at chartreuse-colored Buzz baits, white spinners and God knows what else, and thought: What are the fish that go after these lures thinking or seeing? I then decided to do some investigating to find the answers.

The search started with fish anatomy, most importantly their eyes. Like human eyes, fish eyes have a cornea, iris, lens and retina, the latter containing rods and cones. Rods are used for night vision, so night feeders like walleyes, as expected, have more rods than day feeders. Cones allow for color vision, so fish can see color in varying degrees. Salmon and rainbow trout have a highly developed color viewing system. According to Lynn Frederick of the University of Wisconsin’s Sea Grant Program, "They can distinguish complimentary colors and up to 24 spectral hues." This is why males, some who become brightly colored during the spawn, are more recognizable to females.

Seeing color is one thing, but knowing how that color stands out in water, which is much denser than air, is the next step in interpreting why fish are attracted to certain colors. That same Sea Grant study reports that various colors displace differently in water. For example, red, which has the longest color wavelength, is usually the first to disappear, being visible to only 15-20 feet in clear water and only a few inches in murky water. After red comes orange, which remains visible up to 40 feet, then yellow to 70 feet. Blue and green are visible as deep as light penetrates.

However, the deeper each color goes, the less strength it has because of light diffusion. Studies have found that in depths where light is almost absent, white and silver stand out better than even blue or green. Perhaps there is a message here for those who troll deep water for lake trout.

All this is significant because fish locate food primarily by sight. Sound and smell will attract fish, especially top of the line predators like northern pike, to an area, but the final strike is based on sight. In one study done by the University of Trent, Ontario, Canada, researchers found that muskellunge have color vision throughout the color spectrum except for blue. They can see red, orange, yellow and green. However, unlike humans who process information through the cerebral cortex, muskies do so in the optic tectal lobes of their brains, which are much less complex than mammal brains, so they must turn and face their prey before going after it.

And, like all freshwater fish, muskies have eyes with 180-degree vision placed on each side of their heads, thus giving them an overall 360-degree view of their surroundings. However, they are capable of focusing down, each eye independently, when a food source or lure is spotted.

What does all this mean? For those using lures, this may explain why certain colors are effective on certain days. In overcast weather or in turbid waters, silver or white may be better than gold or red. Ten years ago, I remember fishing the Vermont side of Lake Champlain for lake trout and salmon. I was with a party using Mooselooks and Needlefish on downriggers. While we trolled, I listened to the radio chatter and heard that copper seemed to be the color of choice that day. So we switched from silver to copper with good results. Other times, even after weighing all the constants - baitfish, lure, color, water temperature - I have come home empty handed. So, knowing what a fish can see doesn’t always make it bite.

One of the more interesting analyses of what fish see comes from Doug Hannon, the well-known "Bass Professor." His general advice for fly-fishing is, "Use small flies that emulate an abundant source of prey. They should glide quietly through the water with the least amount of ruckus. They are the most effective because that is how real prey behave underwater." Hannon goes on to add, " Small, quiet, simple flies tied in natural colors don’t give off negative cues which the fish see and sense. Sized to match available food sources, they can be presented to imitate the actual motions of real prey."

His final advice is probably the most difficult for most of us anglers to follow for we are often hooked on the latest color or shape without really knowing what our intended target fish are actually seeing. Hannon concludes, "Keep the gimmickry out of your fly designs and keep your flies effective!" Sometimes that is easier said than done.