The operative word here is trigger. I too do not believe that color alone is a trigger as much as it is something that captures their attention first. Upon this they can then rely on their binocular vision to tighten in on the footprint. I believe the triggers are made up of several variables and that it is impossible to narrow it to one. I also believe that these triggering components shift through out the course of the hatch and subsequent feed. The footprints that we refer to are not the same ones that trout are capable of seeing, as we see them with out UV and/or IR.

The color red travels further than any other color in the water. Color will travel further than footprints as the different colors on footprints have different independent wavelengths. A foot print consisting of several different colors may only deliver the section of one portion of that foot print via the wavelength of that associated color. This is what leads me to believe that color captures the attention of the trout first. (Very important to note that I said ?captures attention? and not ?triggers?). The color red has been proven to trigger an aggressive response, in lab studies, with many of the game fish species. Perhaps it is sparse samples of red that do trigger something innate in wild creatures. Meaning; red is the color of blood and potential injured prey and/or easy capture of said prey; this would also convey color first.

As far as lighting conditions; remember again that trout also have UV and IR capabilities, which are also types of filters. They are capable of seeing 4 shades of color as opposed to the 3 that we see. Humans do have the UV rods but we are unable to use them. Studies have been conducted with UV source lighting that did trigger neurology in the retina of trout in a dark lab. There are some die hard types that will build their fly?s with colors chosen under UV lights, while comparing the match to a natural sample under the same light source. These UV fly?s did have higher yields of response on the river as opposed to the ones that were built with out the use of UV lights. The sample was made up of exactly same patterns; one tied by the choice of color determined with natural lighting, the other under UV.

As the trout age some of the eye cells do self destruct, they are one of the very few species that have this cell degeneration and as such are excellent ongoing study animals for Alzheimer?s research. The older trout loose most of their UV abilities but not the IR. This may better explain why the larger trout are better caught at night and why they primarily feed at night. Research is still ongoing but some believe that their IR abilities get even stronger with age and that this also explains why larger trout seek deeper and/or darker waters where UV is no longer required to feed. They do maintain all other features but their UV site.

Also worthy of re-mentioning; the microscopic anatomy of the trout?s eye is such that they are able to see everything in front, to the side and behind them; the anatomy structure is such that they just can not see straight below them.


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Best Regards




[This message has been edited by BenC (edited 06 September 2005).]