Fluorescence and Wild trout

[np01]

Fluo green tailed Kate muddler is seldom off the cast throughout the season. Probably my most successful fly for the last 2 seasons, from Watten to Whiteadder, taking fish from 2.5lb to 4oz. Saved many a potential blank.

As regards UV materials, I'd read somewehere that UV light only penetrates the water for about the first 3 or 4 feet, so anything fished deeper than that is unlikely to flourese. Don't know how accurate this claim is but seems logical in terms of the different light wavelengths and different energies associated with each.

[haresear]

I've never been that fussed about fluorescent materials, by which I mean I don't like nor do I dislike them on a pattern.

It seems to me that if a fish is approaching the fly from below, then the fishes view of the fly means that idayglo type materials would be unlikely to fluoresce to any great extent.

Alex

[Malcolm]

Gets me thinking..... first to tie up a flee with a wee battery and LED wins a prize. First to catch something on it wins a bigger prize!

You can already get these tiny lights (or used tobe able to). They used to be fairly popular for seatrout. They last for about 10 years.

Well it seems to me I'm in a minority of approximately one (not for the first time on this forum). Maybe if I put some on a fail-me-never like a muddler or Peter Ross I'll get some confidence in them.

[Fishtales]

Fish don't see the fluorescence like we do If they see in ultraviolet light the fluorescence will be a bright spot, or a dark spot. Bees use ultraviolet light when looking for flowers. This page describes it a bit better.

http://ecf.hq.eso.org/~rfosbury/home/natural_colour/biochromes/UV_flowers/nc_bio_flower_uv.html

If fish use it the same way then materials that fluoresce in UV light, whether from below or not it will still glow, should help them home in on the food item. It is possible that some invertebrates glow in UV light. Look at scorpions which glow bright in UV light, that is how researchers find them in the dark. In daylight they probably do the same to an animal that can see UV, which we can't so all we see is the colour of the scorpion.

[Scotaidh]

Even if the trout can see UV wavelengths a fluorescent material absorbs these and emits them them as a longer wavelength.  This is why they appear bright to us, because the are absorbing something we can't see and giving off light we can.  If the trout can see the fluorescent wavelength then it is the same as us, but if it can't it will be a black spot.

If the UV is filtered out by the water then it will not fluoresce anymore.  A much more useful property in this instance is phosphorescence "day-glo" since it will absorb the UV light but give out longer wavelengths much, much more slowly, and thus appears to glow in the dark.  So it absorbs while you cast then when it sinks down the water will give off light.

Fluorescent materials should also theoretically work better at dusk and dawn as the angle of the sun makes the light more suitable.

(I'm a chemist, not the pill dispensing kind)

[Ian_M]

(I'm a chemist, not the pill dispensing kind)

I may be wrong but I think that this is physics    :worms

[haresear]

I've learned a lot in this thread about physiology and physics. I don't say that sarcastically. I really have.

On the other hand, I still don't know whether fluorescent material  makes any difference to my catches :?.

As it happens, I was out doing some casting practice into twilight today and I noticed that as the light faded, my disgustingly orange fluoro line appeared to shine like a beacon. That really made me reconsider and question my earlier comment about fluorescence being much reduced when viewed against the light. I suppose that is how fluorescent materials work, they gather available light more efficiently than other materials.

I take your point Fachan, about fish following flies and approaching them horizontally, rather than hitting them from below. That makes sense.

If the UV is filtered out by the water then it will not fluoresce anymore.  A much more useful property in this instance is phosphorescence "day-glo" since it will absorb the UV light but give out longer wavelengths much, much more slowly, and thus appears to glow in the dark.  So it absorbs while you cast then when it sinks down the water will give off light.

Scotaidh, phosphorescence has been a major breakthrough in fishing for rainbows in NZ's lake Taupo (the browns don't respond to them the same). In the above quote, you seem to say that the water itself will give off light (presumably laying a trail to the source of the phosphorescence. Is that right?

Alex