Readers Cast


Neil Travis - July 16, 2012

Sysadmin Note
Part one can be found here

In my last Reader's Cast article I wrote about how we perceive objects in our environment. Our brains rely on shape and behavior to quickly identify objects that we encounter. We don't need to stare intently at objects that we routinely encounter in order to identify them. Likewise, it seems logical that fish use the same system when determining if something they encounter is food or not. If it has the general shape of a food item and it moves like a food item then it must be a food item. However, what about color? How does the color of the object affect their reaction?

Look at the images and see if you recognize the objects. They all are a different color but they are all the same object. Even though they are all different colors did you have any difficulty determining that they were all the same object? I have taken a basic image of a green tree and changed the color.  So, we have a series of trees, some are green, one is pink, one is orange and one is black, but our brains tell us that, since the shape is correct, regardless of the color, these images are recognizable as trees.

Now let's shift our focus from our perception of colors and to that of a fish. Scientists tell us that fish can "see" color, that is, they have the necessary structures in their eyes that allow them to detect color. The question for the angler is how does their ability to "see" color affect how they react to that color.

The series of variously colored trees in my illustration probably elicited very little reaction on your part. The objects have the right shape and even those objects that look different than similar objects that you encounter everyday your brain did not reject them as possibly being trees. In like manner, a fish that encounters an object that has the right shape and the right behavior is not necessarily inclined to reject it just because the color is different. Anyone that has been fishing for any amount of time has caught fish on an imitation that, color-wise, looks nothing like anything you would find naturally.

A few seasons back a fellow angler tried an experiment on one of our local spring creeks. Now every angler presumes that some of the most discriminating trout are found on spring creeks. These trout have seen it all, and some of the finest anglers and most demanding fly tiers regularly float flies over these fish. My friend tied an entire spectrum of Royal Wulff dry flies ranging in size from 14 to 24. These were standard Royal Wulffs' with white, upright wings, hair tails, peacock and floss body and brown hackle. He used these flies whenever there was a hatch on the spring creek, whether the flies were Baetis, PMDs', or Sulphurs he used the appropriate sized Royal Wulff.

Now it should be noted that my angling friend is a very competent angler. He is an extremely accurate caster and his presentations skills are second to none. The upshot of his experiment was that he consistently caught fish during all the various hatches, and was often catching fish with his non-hatch matching patterns when others were not catching fish with their imitative patterns. A Royal Wulff looks nothing like a Pale Morning Dun, so how is it possible that these spring creek trout were fooled by such a poor imitation of the food that they were eating?

Years before this I had another friend that tied up a series of dry flies in three shades of gray –light, medium and dark. He also tied up a series of spinners in the same colors. During the season – April to October – whenever he encountered trout feeding on mayflies on the surface he would determine if the insect was a light, medium or dark shade and then, regardless of the color of the natural, he would use an imitation that matched the shade of color of the natural with one of his gray patterns. At the end of the season he reported that he had caught just as many fish and of the same size as he normally caught on the same water using standard imitations. Like the previously mentioned experiment, it did not seem to matter that the color did not match the naturals. [Orvis® once sold a selection of flies tied in these three shades of gray]

To me the upshot of these two experiments and others of which I am familiar demonstrate that all the attention that fly tiers and fly fishers pay to making certain that the color of their imitation matches the live insect on the water is probably unnecessary.

Now I know that there some people that will read this and quickly recall an incident when they used several different imitations without success, and then they hit on one that was closer to the color of the naturals than the other patterns they had been using and suddenly they were catching fish. Can I explain it? No, I can't explain it any more than I can explain how it's possible to catch trout all season long using only Royal Wulff dry flies during specific hatches.

Now I am not suggesting that we all abandon tying flies that match the color of the naturals that we find living in our waters. However, I think that the type of experiments mentioned in this article demonstrate that factors other than color may be more important in determining whether or not a fish will attempt to eat our artificial.

The problem that we all face when having a discussion about why fish do what they do is that we cannot communicate with them. We can believe that they think like we do, and that they react to things the way we do, but we don't know and we can't know. The speculations are fun, the discussions are entertaining, but at the end of the day we really are no closer to knowing the real reasons behind what fish see and how they perceive it. At least not until we find that talking fish!


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