color vision

this is my watercolor plate. my friend once told me, it looks like teeth! ha... how terrible! look at all these holes... : P . unfortunately, I have been leaving them "clean" like this for almost two months. too busy to play with them...

There are some growing interests in color vision in fish lately in other blogs. What fish see? what color of flies and ultimately, as we all interested in, Works~!! Well... there are some discussions about the color vision in fish in terms of which color fish can see better, which color stand out better in the light environment which fish live... all good points from physiology and ecology... BUT, there is one big chunk of information have been overlooked. It is the behavior part of the fish? why fish bite your fly? I think I will address this a little bit more since I do interested in fish behavior and have been working on animal behavior in general for a while. As we all knows, fish bite flies can attribute into two gross categories. First, for food, because fish see it as a food, so they eat them. Second, because fish see it out of curiosity (or aggression), so they need to feel them with mouth. Those initial motivations in fish are very important in understanding fish strike flies. Without those information, we will Not be able to pin down which flies to use during any given time of year, weather, water and light condition.

For trout, we all know "match the hatch", what match the real insect will trigger fish rises. The better the match, the less hesitate the fish. We match the color/size right, we will get fish. Simple. Trout see those mayflies as food, so they rise up and inhale them like food. Better yet, if you are fishing during caddis hatch, you want to twitch the Elk Hair Caddis fly to match the skating behavior of the real insect. Those will give trout more clues about "food", come get it! But what trout see the color? Is our Elk hair color close to the real caddies enough in fish's eye? This question involve two steps, 1. physic light spectrum reflect on trout's retina and 2. neuro-physio brain process in trout brain "the size of pea". We can simply measure trout's eye property - the color sensitivities from different color pigments in the eye. But this is only complete step 1. Step 2 is much more commplicated. It's more psychology question. How those signal transfer and process in the brain. We feel cool when see blue, "feel" hot and danger when see red. All those process and describe is neuro-phsio process. Those process and discussion can go on and on into more philosophy discussion.

But I say, for the perspective of being a fisherman. We don't need to dig into that kind of details, because what fish see and feel is NOT the real "fuzz" for a fisherman in this particular first category (food trigger eat behavior). The real "fuzz" is fish eat it as FOOD or not. How close is the color of flies to the real bug. If we know the insect looks brown (to us), and we use something (feather) looks brown (to us), it should work right?. and it does work better if the presentation is right. How about flies underwater? Should we care about what flies looks underwater environment? no. we don't. If we pick up a mayfly nymph under the rock, they looks deep brown on our hand (above water), we should imitate the deep brown color without consider light environment in the water. All thing being equal, the flies looks similar in our hand will still look like a real insect underwater, even the water filtering out some light spectrum. But how about UV reflectance in those real insect? Good point! Because human only see color from 400-700 nm light wavelength approximately. Everything under 400 nm is into UV region. We now know there are lot's fish and bird see UV color. We could miss out the whole channel and mismatch the whole color. e.g. the deep brown drab mayfly nymph is not as drab as we think, IF they reflect UV light, and trout see UV. If this is true. We will have to use UV reflecting brown material (UV_brown) to match the insect. This is a easy task, just use spectrameter and we will know if mayfly nymph is true brown? or UV_brown? (to be continued...) in the next few posts I will address few other important issues, a. Fish can see some color better is not necessary the color trig them strike. b. the color trigger aggression response.