How Colors Are Viewed Underwater

[GLF]

A large part of vision underwater is being able to distinguish different colors. Seeing colors underwater depends on the amount of light reaching the particular depth at which one is at. Another factor in seeing underwater is the condition of the waters and, more specifically, the conditions of the surface. There are several ways to make the colors easier to see. However, it is most important, to simply understand that colors change underwater and it is sometimes hard to distinguish between them.

One factor in seeing underwater is the fact that as light passes through the water it is absorbed, and much of it is lost in the process. This causes objects to lose their color as they go deeper down or further away. To add to this, the wavelengths that make up our perception of color are absorbed differently. The length the wavelength changes how fast the color is absorbed. Red has the longest wavelength, more than 700 nm. One "nm" stands for one nanometer, which is on millionth of a meter. After red comes orange which is somewhere in-between 700nm and 600nm. After orange comes yellow and so on, all the way down to the blues and purples which are the shortest at around 400 nm.

Depending on the length of the color's wavelengths you can predict how a color will change underwater. For example, in clear water, the longest wavelength is lost first. So if you were in a pool swimming downward, the first color that would be hard to see is red.

Another factor in seeing color underwater, is the condition of the water. Light from the sun is reflected by the surface of the water. This means that the surface of the water can cause significant change in one's perception of color underwater. Different surfaces can be different amounts of bubbles, pollution, decomposing plants or plankton. Even if the change is simply more motion in the water, causing more bubbles and a different angle between the rays and the surface of the water, light would be absorbed faster, and color would be therefore lost faster. However, something such as plankton can significantly change perception of color underwater. This is because plankton absorbs violets and blues. So the presence of plankton would cause blue and violet objects to lose their colors much faster compared to red and yellow objects. Red was the first to lose its color in clear water, and the blues and violets were the last. So the condition of the water can ultimately reverse the situations, before the longer wavelengths were the first to be absorbed and with plankton the shorter wavelengths are the first. Thus, the condition of the water is a huge importance when seeing colors underwater.

Understanding how colors change at different depths and in different conditions is the first step, understanding what they change to and how to work with that is the next. In clear water, if you go down far enough a red object either appears unlighted or black. This makes since as clear water absorbs red light and eventually you can reach a depth where no red light reaches the object. The same thing could happen to a blue object in coastal waters, it could appear black. Even though red is absorbed faster in clear water and blue in coastal waters, all the colors are absorbed in water, just at different rates. So the farther you go down the less color is perceived. Plus, the further down you go different color objects all start to look the same color, the color they all look like tends to be the color that is best perceived in that water condition. For instance, if it was clear water, at a certain depth all the objects would start to look gray. So even before you reach a depth deep enough to make colors look black you can get easily confused between the different colors. One way to distinguish between different colors is their relative brightness or darkness. Several of the most visible colors are light, bright colors that cause a good brightness contrast with the dark water background. If there was a different background, such as white sand, darker colors would be easier to see. Another good way to distinguish different colors is to use two colors that cannot be mixed up in any type of water. A good example would be orange and green.

[GLF]

Every spring, the tackle counters of local sport shops are filled with attractive displays of the latest lures in a myriad of colors designed to capture the attention of eagler anglers, to say nothing of eager fish. Most tackle boxes are bulging with lures of every hure, and each fishing trip becomes a study of what color bait will entice the fish today. However, certain principles of vision and the behavior of light as it penetrates the water can make lure selection more scientific.

Most fish can see in color. As in people, the retina of a fish's eye contains two types of cells, rods and cones. Cones are used for day vision and are the cells used to see colors. Rods are used for night vision and cannot distinguish colors, although they can judge light intensity. The eyes of most freshwater fish contain both rods and cones, though day feeders tend to have more cones, and night feeders more rods.

In theory, then, day feeders like bass, trout, and salmon are more sensitive to color than night feeders like walleyes. Studies have shown that rainbow trout and Pacific salmon have color vision similar to that of humans. They can distinguish complementary colors and up to 24 spectral hues. Other studies have shown that brown trout are capable of sharply focusing on near and far objects at the same time and that they can clearly see different colors at different distances.

But light behaves differently in water than it does in air. The various colors of light travel at different wavelengths. The longest wavelengths are the reds, followed by oranges, yellows, greens, blues, indigos, and violets. When light travels through water, some of its energy is absorped, and the longest wavelengths are the ones absorbed first. Thus, the warmer colors fade out and gradually appear black as light penetrates the water column. Red light is almost completely absorbed within the first 15-20 feet. Orange penetrates to 30-40 feet, and yellow to 60-70 feet, while green and blue remain visible for as deep as the light penetrates.

The total amount of light also decreases with depth. At 50 feet, a yellow lure will still appear yellow, but will not appear as bright as it did at 20 feet. While red may be visible down to 15 feet in the clear water of open Lake Michigan, it may disappear within six inches of the surface in the turbid Fox River. At depths where it is nearly dark, a white or silver lure would show up better than a blue or green lure against a blue-green background of water. Products that are designed to reflect any light that strikes them, like Prism-lite, also make lures more visible.

Commercial fishermen have experimented with this principle in reverse, using it to make their nets less visible. Nets for use in very deep water have been dyed blue or green so they would blend into the background color of the water. Perch fishermen in southern Green Bay have experimented with dying their nets red, presumably because red fades out first in these shallow turbid waters.

Total light intensity is also important. On a cloudy day, colors will not penetrate as deep as they will on a sunny day. At dusk, as light intensity falls, reds are the first color to go, followed by orange, yellow, green, and blue. As total light intensity decreases, the fish's eye switches to vision with rods, and the fish is no longer able to distinguish colors. After dark, fishermen should choose between a light lure or dark one. At dawn, as light intensity increases and fish switch back to cone vision, the order is reversed, and blues, greens, yellows, oranges, and reds appear. At early dawn, some anglers are successful with a red J-lug near the surface. To fish striking from below, it shows up as a dark lure against the lightening sky. As the day gets lighter, red no longer works well, and anglers must experiment with more visible colors.

Studies on salmon have shown that their feeding behavior depends on whether they are seeing with rods or cones. During the day, salmon use cones to give them information on the hues and shades of moving prey. When prey are first located, they are stalked and eaten head first. From dusk to dark, rod vision takes over. Schools of prey fish break up and salmon assume a position below their prey to see them in contrast against the water surface, watch them move for a few moments, and then snap them up one by one.

Ultimately, the appeal of the lure to the fish is most important. Fish must strike the lure either to eat it or attack it. While fish may locate the general area of the bait by smell or sound, most of the fish in the Great Lakes make their final attack by sight. Fish scents and noisemakers can draw fish to the area of the lure, but before it can strike, the fish must also be able to see it. This is why lure visibility and color are important to successful fishing.

[GLF]

There are a lot of variables that have an affect on the depth/lure color equation. Sunny day or cloudy day, position of the sun(time of day), calm day or choppy day, and water color.

These depths are not set in stone. All they are is a guide. The actual depther the color is visible at is directly affected by the above variables.

red will be visible from 0' - 30'

orange will be visible from 0' - 45'

yellow will be visible from 0' - 60'

green will be visible from 0'- 80'

blue willl be visible from 0' - 100'

purple will be visible from 0' - 120'

Generally what happens when you fish a color deeper than the depth it will show, it becomes black or gray depending on the lure color.

Glow in the dark lures will help in the deeper depths.

I am no expert on this. If any of you would like to share some info on this, please feel free to add to the thread.