Night Fishing with a Light Attractor

Just as fisherman seek conditions where the chance of catching fish is optimized, so fish seek areas where the chance of catching their food is optimal. Most gamefish 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. So, to catch fish, look for the location of their food chain.

Scientific research shows that this food chain has eyes sensitive to the colors of blue and green. This probably evolved because the waters these animals live in is blue to greenish in color, depending upon how much and what kind of particulate matter is suspended in the water. This is the color of their space–the equivalent of a room with the ceiling, walls and floor painted blue or green.

The source of this color comes from the white light of the sun. Sun light contains the familiar colors of the rainbow: red, orange, yellow, green, blue and purple as well as additional light humans cannot see; ultraviolet and infrared. Pure water, which contains little particulate matter, scatters light in the blue-purple region of the spectrum. Human eyes see a body of this water as blue. If water is rich in nutrients and contains photosynthetic microorganisms and plants, the chlorophyll in their bodies preferentially absorb red light. The remaining, unabsorbed light is transmitted and scattered, thus giving the water a greenish appearance. If the water contains a lot of organic material from decaying plant life or suspended sediment, it may take on a yellow-brown color.

Fish and 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 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 (530nm) and near UV receptors. In fact, some aquatic animals have up to ten different classes of visual pigment in cells of their eyes. By comparison, humans have three with maximum sensitivities in the blue (425 nm), green (530 nm) and red (560 nm). It is the differential responses of these receptor cells that enable color vision.

Since it has been known for a long time that a night light attracts fish, shrimp and insects, what is the best color for this light attractor? Based on visual receptors, the light should be blue or green - the space colors of fish and members of their food chain. However, while blue or green colored light is a desirable it is not essential. Even if fish or members of its food chain have color receptors in their eyes centered at the blue or green spectrum, these same receptors have a broad but decreased sensitivity to other colors. Therefore, if a fishing light source is intense enough, other 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 part of its total light 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. Practically speaking, no commercial fishing light is able to offer all of these attributes. Many high intensity lights such as tungsten-halogen, medium pressure mercury or metal-halide lights are so power hungry that they cannot be operated for long on a battery, thus limiting convenient portability. While green colored LEDs or specially coated fluorescent lights are energy efficient, they are not very intense. And, many lights cannot be submerged in water without risk of electrical shock or damage to the light system.

With a better understanding about the vision of fish, one might ask how the colors of lures impact on fishing success. The answer to this question is a subject of much product hype. Except when a lure is very close to a fish, it is likely that green or blue colored lures are indistinguishable from white lures. If the fish is looking downward toward a dark background, a light colored lure will have the most contrast against the background. Likewise, red lures appear dark or black to their eyes. A red, brown or black colored lure will have greatest contrast to a fish looking upward toward the water surface. Fish and their food chain understand this color relationship well. It helps protect them from predators. The bottoms of many fish are white. Predators viewing them from below will have difficulty making them out from the white light of the water surface. Conversely, the red, brown or dark gray color of the top of a fish matches the color of deeper water or the lake or bay bottom, thus making it difficult for predators to detect the fish from above. Other popular camouflage strategies are a silver or reflective surface or, as is the case with shrimp, transparency.

Search for fishing lights on the internet or a fishing supply catalog and you find a wide assortment of lights. These lights fall into two general groups, those that are portable and those that are permanently mounted. This writer has limited experience with portable lights. Further, and as mentioned earlier, all commercially available portable lights are limited to relatively low light intensity because they are powered by battery. The old classic, a 12 volt automobile headlight mounted on a Styrofoam float ring is probably the least expensive. More efficient but more expensive are special green fluorescent lamps enclosed in a waterproof, submersible plastic housing. Multiple arrays of LED lights is an up-and-comer.

Permanent lights have adequate power supplies. Placed on poles at the end of a dock or pier, the least expensive are 175 watt mercury vapor or 70 and 150 watt high pressure sodium vapor flood lights. Sold as security lights, they are readily available from most hardware or farm supply stores. They cost $30 to $90. Most are photocell controlled for automatic dusk-to-dawn operation and the fixtures include the bulb. These lights use 115V house current, are efficient in converting electricity to light and stand up well to outside weather conditions. For the purpose of a fishing light, one can redirect light toward the water by installing a 5"X10" piece of aluminum flashing bent into a half circle inside the standard circular acrylic lens. These security lights can also be modified to operate submerged. This later modification yields great results. However, the modification must be done professionally as the high voltages that power these lamps can be lethal. Two sources of complete kits, both costing about $300, are Green Monster Fishing Lights (Dadeville, AL, www.thegreenmonsterfishinglight.com) and Underwater Fishing Lights (Corpus Christi, TX, www.underwaterfishinglights.com). The lamp's power transformer is mounted on a pole in a dry location. To it is connected a waterproof medium pressure mercury lamp via a waterproof cable. The lamp floats like a bobber and is held in submerged position by weights. A unique feature of this kind of submerged light is that its outer glass envelope gets hot enough to prevent establishment of marine growth. This is not the case with underwater pool lights which typically contain tungsten lights sealed in a waterproof housing. While pool lights operate at a safe 12 volts, they must be frequently cleaned.

Many commercial flood lights use tungsten or tungsten-halogen (quartz) bulbs. Even though they work as fish attractors, they are energy inefficient and a large portion of their light is "invisible" to game fish and their food chain. Florescent lights are energy efficient but commercial outdoor fixtures using fluorescent tubes are expensive.

For those who embrace a cost be damned view, there are stadium spot lights. Rated at 250, 400 and 1000 watts, the parabola-shaped reflectors, light ballasts and high intensity discharge lamps are sold separately. These lamps are designed to emit in white, blue-green, green or yellow. Unlike most colored lights, they do not use colored filters. Therefore, little electrical energy is wasted producing and filtering out light of other colors. Obviously, for fishing waters of the Texas gulf, the lamp color of choice is green. A complete light fixture and lamp will cost about $400: $200 for the lamp and $200 for the stadium or sports flood light fixture. The cost of the lamps with different wattage ratings are roughly the same, so most people go for the 1000 watt monster. One source for these lights is Light Bulb Depot (San Antonio, TX, www.lightbulbdepot.com, Items #01060K and #02157A). It takes two people to install these big lamps and you may want to include a switch, timer, heavy duty 10 or 12 gauge wiring and perhaps a circuit breaker hookup, thus adding to the cost.

What does one get with these lights? The action starts after 11 pm in the Laguna Madre. On a good night you see dozens of speckled sea trout milling around the lights. Tail slaps abound. Shrimp and small bait fish are hopping out of the water. White or light colored plastics, top lures and spinners take your pick, all work. You don't have to cast far or long to catch your limit.