Definition of fishing light attractor

Just as fisherman seek conditions where the chance of catching fish is optimized, fish seek areas where the chance of catching their food is optimal. Most game fish seek waters that are rich in food such as smaller fish, insects or shrimp. And, it follows, that these smaller fish, insects and shrimp congregate where their food is most concentrated. 

Scientific research shows that all members of this food chain have eyes sensitive to the colors blue and green. This probably evolved because the water absorbs longer wavelengths (Mobley 1994; Hou, 2013). The color of the body of the water is largely based on the constituents inside, combined with the absorption spectrum of the light in water. The colored dissolved organic matter in the water will absorb blue light very fast, then green, then yellow (exponential decay with wavelength), thus give the water a brownish look. Keep in mind that the transmission window of light in the water is very narrow and red light gets absorbed very fast. See above reference for details.

Fish and some members of their food chain have color receptors in their eyes optimized for the light of their “space”. Eyes that can see a single space color can detect changes in light intensity. This is equivalent to a world in black, white and shades of gray. In this simplest level of visual information processing, an animal can recognize that something is different in its space—i.e., that there is food or a predator “over there”. Most animals living in a lighted world have an additional visual resource: color vision. By definition, that requires that they have color receptors containing at least two different visual pigments. To efficiently perform this function in water illuminated with light, an aquatic animal would have visual pigments sensitive to the background “space” color and one or more visual pigments offset from this blue-green region, say, in the red or ultraviolet region of the spectrum. This imparts a clear survival advantage to these animals because they can detect not only changes in light intensity but also contrasts in color. Many fish, for example, have two color receptors, one in the blue region of the spectra (425-490 nm) and the other in the near UV (320-380 nm). Insects and shrimp, members of the fish food chain, have blue, green (530 nm) and near UV receptors. In fact, some aquatic animals have up to ten different classes of visual pigment in their eyes. By comparison, humans have three with maximum sensitivities in the blue (442 nm), green (543 nm) and yellow (570 nm). It is the differential responses of these receptor cells that enable color vision.

It has been known for a long time that a light attracts fish, shrimp and insects at night. But what is the best color for a light attractor? Based on the biology of visual receptors discussed above, the light should be blue or green — the space colors of fish and members of their food chain. However, while blue or green light is desirable it is not essential. Even if the eyes of fish or members of its food chain have color receptors most sensitive to the blue or green, these same receptors have a broad but decreased sensitivity to other colors. So, if a fishing light source is intense enough, other light colors will also attract. For example, a sodium vapor light with its characteristic yellow color will attract fish — if intense enough. A fishing light attractor can also be white light because a portion of its total energy is in the blue to green region.

The perfect fishing light would have the following properties: 1) high intensity, 2) emit its light in a color similar to the fishes space (blue or green), 3) be powered by a portable electrical supply and 4) be submersible. The last attribute is desirable because significant amounts of light energy from land- or boat-mounted lights are lost by reflection off the surface of the water. No commercial light satisfies all four of these criteria. For example, many high intensity lights such as tungsten-halogen (incandescent), medium pressure mercury or metal-halide discharge lights are so power hungry that they can only be operated for very short periods of time on a battery, thus compromising convenient portability. While LEDs and fluorescent lightsdraw much less electrical energy, most are not very bright. Further, many of the above lights cannot be submerged in water without risk of electrical shock or damage to the light system.