What Can Bass See? Part 2- Fish Tales

In part one of the vision series, I discussed various properties of the electromagnetic spectrum, how water affects light transmission via scattering and absorption, the anatomy of a bass’ eye, and what colors bass can see.  The electromagnetic spectrum consists of both visible and invisible waves which are defined by what the human eye can see.  Light waves invisible to the human eye include gamma, x-ray, infrared, radio, micro, and ultra violet waves.  In this article we will discuss UV light, some of its properties and if bass have the physical ability to detect it visually.  You may be asking yourself why you should I be concerned with UV light in regards to bass fishing.  There are bait and scent companies, like Pro Cure, Persuader and Tightlines UV, currently using UV properties in their manufacturing process to potentially attract bass.  In my quest for answers to this question, I scoured the internet searching for published research and interviewed Dr. Keith Jones of Pure Fishing, Professor of Visual Neurobiology Dr. Craig W. Haryshyn, owner of Persuader Premium Bass Baits Cliff Liddy and owner of UV Tightlines baits Brett Ware in hopes of finding answers.

Ultra Violet light (UV) is electromagnetic radiation in the violet portion of the spectrum with a wavelength shorter than that of visible light.  UV waves range from 10nm to 400nm.  The human eye, having three cone receptors (red, green and blue-trichromat) can only detect light in the range of 400-700nm.  We are only able to see the effects of UV light via a black light which uses a specialized bulb causing certain substances to glow or fluoresce.  Most UV light emitted by the sun is blocked out by the Earth’s atmosphere via gases like ozone and the rays that do get through are what cause sunburn.  There are some animals and insects that can see UV; for example there are over 40 species of diurnal (active during the daytime) birds which can see UV light.  Scientists, using a combination of dissection, behavioral analysis and gene sequencing, have verified that these birds do in fact posses four cone receptors (red, green, blue, and ultra violet-tetrachromacy).  The ability to detect UV light has also been noted in various species of turtles, fish and bees.

To help determine if baits containing UV reflective properties will help anglers catch more bass, I contacted the following industry experts.

Dr. Keith Jones

Dr. Keith Jones is the director of research at the Berkley Fish Research Center in Spirit Lake, Iowa. He is the author of "Knowing Bass, The Scientific Approach to Catching More Fish"; a no nonsense scientific fact-based book with emphasis on what bass can sense, how they use their senses to feed, how they relate to fishing lures and how they interact with anglers.

Lesieur:  In your book you write that bass only have two pigment receptors in the retina- red and green.  There is no mention of a specialized receptor for UV detection. During my research I was unable to find any scientific research regarding UV light detection by bass.  So can bass see UV light?

Dr. Jones:  You are correct.  The bass retina contains only two types of color cones: a red and a green.  They do not possess a blue cone, and certainly not a UV cone.  Moreover, assuming bass follow the pattern of other centrarchids, their ocular media (the fluid in their eyes) strongly absorb light with wavelengths shorter than 450nm, meaning that very little UV light would ever reach their retina anyway.  So, no.  Bass do not see UV light.

Dr. Craig Hawryshyn

Dr. Hawryshyn is a professor of biology at Queen’s University Canada and obtained a PH. D. in Vision Science and Biology at the University of Waterloo, Ontario.  His research has provided some of the first evidence for ultra violet vision in vertebrates.

Lesieur:  Can bass see UV light?

Dr. Hawryshyn:  One problem here is that no one has measured the spectral sensitivity in the UV spectrum.  There is one paper (Kawamura 2002 Fisheries Research) that measured spectral sensitivity of largemouth bass showing blue, green, and red sensitivity but they did not look into UV.  My suspicion is that they do see UV and have UV cones.  They would be capable of detecting UV light even if they did not have UV cones but that system would be somewhat inferior to one having UV cones.

Lesieur:  If largemouth bass can potentially see UV light without UV cones, how would that system work?

Dr. Hawryshyn:  They can potentially see UV light through the beta-absorption band of their visual pigments.  Kawamura shows clearly they have blue, green, and red sensitive visual cones and it would be a logical extension to assume they have all four cone types.

Cliff Liddy

Cliff Liddy is the owner of Persuader American Angling.  Persuader manufactures spinnerbaits, buzzbaits, jigs, popping walkers, soft plastics and weed-less spoons.  Their weed-less spoons use UV enhanced technology in which Persuader applies a powder coat UV base coat and then overlays a digital image of prey.  It comes in both a natural or chartreuse color scheme.

Lesieur:  When did you first hear about the possibility of bass being able to see UV light and decide to use UV powder coat on your spoons.

Liddy:  We wanted to be a little different than everybody else and heard that some anglers in Minnesota and Wisconsin were doing well with baits that contained UV.

Lesieur:  How do you know that bass can see UV light?

Liddy:  We found a study done by the Minnesota Department of Fish and Game that talked about fish and UV light.

Lesieur:  Have you done any testing on your own to show that UV works on your baits?

Liddy:  We field tested the spoons at the Ca Delta and up at Lake Shasta.  We had one angler using a spoon without UV and one angler using a spoon with UV.  The UV bait would catch around 10 fish to every 7 the non-UV bait would catch.  I know damn well fish can see the UV bait down at 50 feet based on our testing.  We also use black lights at trade shows to show our customers how the bait lights up when UV light hits it.

Brett Ware

Brett Ware is the owner of Tightlines UV Bait Company.  Tightlines manufactures soft plastic baits that use a proprietary Nano-Infused Polymerization technology (NIP) in order to reflect UV light which is supposed to help bass better detect their bait versus baits without NIP technology.

Lesieur:  Can bass see UV light?

Ware:  Absolutely.

Lesieur:  How do you know?

Ware:  We use special filters on lights during our tests in which only UV light passes through. This light is shown to bass which follow and react to the presence of UV light.  They chase it just like a cat does when shown a laser pointer.  We have also done field testing in which one angler uses a bait that does not contain UV infused color while another angler uses a bait which does.  The bait that contains the UV infused color out fishes the non-UV bait every time.

As you can see there is definitely conflicting information and opinions in the bass fishing industry regarding this subject.  I am man of science and at this point don't plan on adding UV enhanced baits to my tackle arsenal.  Until next time, stay focused, fish hard and I’ll see you on the water.

References:

*Gunzo Kawamura and Toshihisa Kishimoto (2002).  Color vision, accommodation and visual acuity in largemouth bass.  Fisheries Science 2002; 68: 1041-1046 

*Ruth Nettling (3/37/2007).  The Electromagnetic Spectrum.  Retrieved on 3/14/12. http://science.hq.nasa.gov/kids/imagers/ems/uv.html 

*Unknown author (3/20/2009).  University of Bristol. School of  Biological Sciences/Ecology of Vision.  Exploring the Fourth Dimension. Retrieved on 3/16/2012.

 http://www.bristol.ac.uk/biology/research/behaviour/vision/4d.html