Lure Colours and
Fish Vision
by Dr Steve Adams

INTRODUCTION
Well, there seems to be a constant debate here in our Editorial Offices and on the bank, about lures colours — which are best to use under which conditions etc. We also get quite a few enquiries to our Ask The Team on the same topic. So we turned to Lab Manager Steve Adams for some answers, hopefully ...

COLOUR SPECTRUM, UNDERWATER
We all know that in air, white light is made-up of a wide spectrum of wavelengths and colours, very broadly from the ultra-violet end of the spectrum to the infra-red. Although UV and IR wavelengths are invisible to humans, here we are of course talking about what fish see underwater. The colours visible to humans are red, orange, yellow, bl;ue, indigo & violet. Some species of fish can see into the infra-red and even ultra-violet parts of the spectrum. How do we know? More of that later .....

But first, it's important to realise a couple of key things .... firstly that the colours of the spectrum are differentially refracted at the water's surface, into their various wavelengths & colours, and secondly, these wavelengths/colours are absorbed by water at different rates, with red traveling less distance underwater before being totally absorbed, and the blue/indigo wavelengths penetrating much further, in clear water at-least. This is why, at great depth, things are bathed in an erie blue light.

Of course, in murky conditions, light from the surface (from the sun) penetrates much less far, with the yellow, green and blues being most affected, proportionally.

Coupled with this information, we also need to understand what's actually happening when objects appear to be a particular colour. They appear to be a particular colour because this is the wavelength/colour that they reflect, while absorbing all the other wavelengths/colours. So, in simple terms, an object that absorbs none of the incident light i.e. reflects it all, is seen as a white object. In contrast, an object that appears black is absorbing all the colours of the spectrum i.e. reflects none of them.

So let's consider a white lure with a red head. Its head is absorbing O, Y, G, B, I & V and is reflecting red, while its body is absorbing none of the colours i.e. is reflecting them all. What happens then, as far as its apparently red head is concerned if the lure is at a depth or distance where all the red light has already been absorbed by the water? Well, the head of the lure still absorbs O, Y, G, B, I & V wavelengths but as there is no incident red light, it cannot reflect it to the viewer, and so the head of the lure will appear to be ......... black !

So, what colour will a blue lure appear to be, at a depth where it is bathed only in blue/indigo light? Answers to the Editor please, with a chance to win a Blue Lure!

LURE COLOURS & FISH
So, how can we study what fish see and how the react to different stimuli etc. Well, we can study the anatomy of the eye and its receptors, rods and cones. This gives us a good indication. Then we can add to that, some tank tests using different objects illuminated by different wavelengths, and we can study their responses.

We can do this with food, prey fish and lures. Of coursem because the conditions are artificial and the fish are out their natural environment, such tests are far from being definitive, but again, they give us a pretty good guide.

So, armed with all this information, we can at-least make a fairly good approximation of what fish perceive at various depths in various water clarities and conditions, and therefore how they may see coloured lures.

Of course, if water clarity is very poor, predators that can rely on alternative sensory mechanism will have an advantage over those that rely primarily on their vision. Perch for example though, can see wavelengths in the near-infra-red part of the spectrum and this may help them hunt in murky water. Even better than the perch is its cousin the zander, which has evolved with exceptional low-light vision using mirror-like cells lining the retina.

Pike on the other hand, have a wide combination of alternative prey-detection systems including smell, movement & vibration detections, and even they ability to detect muscular electrical impulses in the bodies of their prey, very similar to sharks. This is what makes the pike such a supreme all-round predator.

WHICH LURES COLOURS ?
Pedators rely on camouflage and speed to ambush and stalk their prey. Equally rpey fish rely on their own camouflage to deceive potential predators viewed from above, the side or from below, they appear to merge with the background. Predators have evolved to hunt-down their camouflaged prey.

On this basis, as far as lure-colours are concerned, we've got two main choices — to make our lures look natural, like prey fish species, or to make them stand-out against the background, using colours, patterns and contrast to achieve this. The most basic colours are therefore white or silver for the former, and black or red for the latter. There are of course any number of intermediate colours and patterns.

LURE ACTION, NOISE & VIBRATION
As we know, predators can detect their prey from sound-waves/vibrations transmitted through the water by their prey. Sound travels much better underwater than it does in air, so bear this in-mind when considering buzzing blades and internal rattles. This is especially true when it comes to surface lures, where shape, noise and action are much more importantly than colour because prey and lures traveling across the water's surface are mainly seen in silhouette, except when the incident light is from a certain direction.

Surface lure-fishing at night, especially in moonlit conditions, can be very productive, and because the lures can only be seen in silhouette, lure action, noise and vibration can be a big attractant.

DAYLIGHT LURE COLOUR & PATTERNS
It's very important to realise that there are no hard-and-fast rules or quick-fix solutions when it comes to choosing lure colours and patterns — if there were, it would take a lot of the enjoyment out of lure fishing. That said, what I will try to do is to point you in the right direction.

In crystal-clear water, lures that closely resemble natural prey are more likely to trigger a strike from a pike, rather than to make it wary or suspicious. Again, such a lure with a goog action will do much better than a lure with little or no action —jointed lures are a good example. If you can't find natural-looking lures, you can try spraying some of the ones that you have, with white or silver paint, and give them a nice black or red eye-spot .. and some hackled hooks!

If these lures fail to trigger strikes, then it's time to step-up the action, colours, patterns and contrast. The simplest contrasting pattern is the white body with the red head (as discussed above) but more complicated patterns such as coachdog (spots) and fire-tiger (stripes) as also great choices, especially when the water clarity just a bit less than perfect.

If water clarity is bad, then it's time to increase the action, and the colours and contrast if you want to make your lures obvious to predators. In shallow water, all-red or all black lures may well to the trick, but in deeper water, we have to use the knowledge we have gained about colours underwater and how they are perceived by different predators.

Of course, spinners and the like, are very successful all-round lures because they combine most of the strike-triggering factors that we have discussed, plus a healthy dose of flash into the bargain! .. and they're cheap too !

There are several schools of thought about lure colour and contrast in deep, murky water. One is to reply on the simplest of contrast to the surroundings, by using all-black or all-white lures. Another is to use fluorescent colours which are active colour emitters rather than the normal passive ones. These, coupled with stripes and spots can be very effective.

Another method to use our knowledge to its full extent, and to make lures stand-out, either wth apparent white or black patterns, and depending on the wavelengths/colours of the incident light. This is why lures with a blue back and a white belly sometimes come into their own — similarly with fluorescent chartreuse yellow and orange.

OTHER ISSUES
As well as being refracted into its spectrum of color wavelengths, many other things happen to light when it strikes and enters the water's surface — it is polarised, reflected, and, by suspended particles, diffused, but these factors and how they may also affect your choice of lure is a very complex subject, something that I'll be leaving for another time.

IN CONCLUSION
Leaving aside the equally important lure action, noise & vibration aspects of lure efficacy, here we're talking primarily about lure colours for different light conditions, different depths and different water clarities: it's worth trying natural colours first, and then changing to contrasting patterns with spots and/or stripes, and then to those with radical colours, even fluorescent ones, but never forget the simple trick of using red, black and white red for two reasons (i) it's the natural colour of many prey fish fins and gills and (ii) it soon becomes a nice contrasting red-black at great depth, even in clear water, because of the prior absorption of the red wavelenths by the water.

And finally, all this demonstrates the importance of having a good selection of lure colours, patterns and actions in your box — I am certainly not one of the lure anglers who insist on thrashing the water to a froth with the same lure for hours on end, rather than conceding that it's much wiser to change and change again until you get results .. and change not just lure colours but type and action too.

I hope you enjoyed this little article and that it help you get results. Please email Nick & Co., and let us know, or if you have any questions.

Have fun .. I do !
Dr Steve Adams

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