Not sure about pellet pigs but for saltwater I avoid it at all costs. The trouble is some flash is subtle so you think it looks ok in the shop then you see it in sunlight and it flashes purple

There is a lot of assumption around what fish can and cannot see.

 

Some light reading

Phytoplankton Lab: Hydrologic Optics Primer

Phytoplankton Lab: Hydrologic Optics Primer

Colour Vision in Trout

The reason ultra violet is seen as purple in daylight is because of the light contamination by the other wavelengths. Under ultraviolet light or in very deep water it will 'shine' like a beacon.

 

All still based on 'our' eyesight Fishtales or theory with fish. Truth is no one knows for sure.

However this might be good for trout but I don't want my saltwater patterns to 'light up like a beacon' as I'm sure the bait doesn't do this.

 

mg:

How Fish See and use UV rays to find bait fish

 

I asked Myriad to move this thread to Fly Tying, as I put it in Viewpoint accidentally.

 

A key question might well be 'how often do you fly fish a fly at a depth of more than 15 feet?'

 

Using flies with uv materials early morning, just before sunrise, late in the evening, just after sunset, and during moonlight would make the UV glow too, even on the surface.

Fluorescent reds/oranges and yellow/greens glow better at sunrise and sunset if using them on flies, well to our eyes they do .

 

Using flies with uv materials early morning, just before sunrise, late in the evening, just after sunset, and during moonlight would make the UV glow too, even on the surface.

Fluorescent reds/oranges and yellow/greens glow better at sunrise and sunset if using them on flies, well to our eyes they do .

Just add a bit to FT's comments. UV this, that, the other, is THE hot ticket the past two years for Salmon and Steelhead fishing here in the PNW. My first exposure to UV materials was Salmon fishing up on the Harrison River in BC.

Same fly tied with UV materials 'out-hooked' the contemporary material(s) 3-1. Made a believer out of me.

 

I am firmly in the camp of "not quite sure, probably cant see it and even if they could would it make a difference"

The link cited above is contradicted by lots of peer reviewed papers on the matter where the only evidence for UV vision used in feeding behaviour in trout was in juvenile fish and even then was fairly weak.

I would be very wary of the integrity of an article talking about UV vision in fish whilst trying to sell you a UV produfct for fishing, especially one called Fool-A-Fish lol.

Dan

 

I understand that young fish up to 2 years old have UV receptors in their retinas.

Stocky rainbows at 2 years old can weigh 4lbs. Therefore most of the stockies can see UV.

Use it sparingly as too much can scare the fish.

John H

 

Fish eyes go green | Science News for Kids

Green Gleam Helps Fish See Violet - Science News

In the four-eyed fish (Anableps anableps), the regions of the retina exposed to aquatic and aerial light do not express the same set of opsin genes

That's me exhausted all my bookmarks

 

Pardon me for being a thickie here and not going off and reading up on the subject (lunch break nearly over ), but what is it that the UV materials are supposed to be doing? My understanding of fluorescents is that they absorb light in the UV spectrum and reflect it in our 'visible' spectrum, which is why they glow nice and bright to our eyes, especially late in the evening when the visible is on the way out but there is still a lot of UV about. Is that correct?

So, with UV materials - what are they supposed to be doing? Absorbing from the visible and reflecting in the UV, or what?

Col

 

They need to be able to reflect light in the UV spectrum (400-320nm). If they absorbed it then there'd be nothing for an observer, said predator fish, to detect. I don't think we're talking about fluorescence here (this being what us humans see when a substance absorbs light in the UV spectrum and, as a result, emits light in our visible spectrum).

 

Hi All, I've tied with UV strands for some time now and I find that small amounts work well.

If you tie Holo Diawl Bach's then over rib with UV this glows in low light. True it looks purple to our eyesight and I don't know what the fish see it as, but it works.

I've just tied some Nomads with it, so these will have a wetting on my next outing. Mix the UV with some normal Pearly flash or other Holo and experiment through the day. You'll be surprised how they hit the flies.

Best Regards

Stuart

 

A key question might well be 'how often do you fly fish a fly at a depth of more than 15 feet?'

Also, a point which is often overlooked is that UV is attenuated as it passes through a column of water and severely so if the DOC content ( dissolved organic matter) is high, as it often is in UK freshwaters and also in the sea close to the shore.

Dave.

 

Putting aside the question of whether there is any merit in using materials that absorb light in the visible spectrum and reflect it in the UV spectrum (no one has actually answered my question - is this what UV materials are supposed to do???)...

If UV light is blocked by water at shallower depths than 'white' (our visible) light, then UV material at a depth below the UV limit but above the white limit might absorb white and reflect UV - so it would stand out.

If all that is the case of course - I'm still clueless.

Col

 

I understand that young fish up to 2 years old have UV receptors in their retinas.

Stocky rainbows at 2 years old can weigh 4lbs. Therefore most of the stockies can see UV.

John H

The figure of 2 years was based on fish naturally reared and not those subject to highly accelerated growth.
The reason given for older fish losing UV corner cones in their retina is ......... when juvenile they feed mainly on UV absorbing and reflecting plankton and sieve this from the water with their gill rakers. As the fish increase in size, the gaps in the gill rakers become too wide to trap the plankton so they seek larger forms of feed and no longer need UV vision.
So, although a four pound skockie may be within the 2 year time range, it does not necessarily follow that it will still have UV cones in it's retina.

I very much agree with danielp. I have kept pretty much up to date with the published scientific papers on this subject but, although I would be only too pleased if it does turn out that older trout do retain some UV vision capability (and that this capability is actually used for prey detection), up to this point non of the evidence is sufficiently convincing to prove that they do.
Until a study has been carried out on 3,4,5 year old naturally reared fish which confirms they do use UV for feeding, I will not be splashing out any cash for UV reflective** fly tying materials.

**Fluorescence is a different matter.

Dave.

 

They need to be able to reflect light in the UV spectrum (400-320nm). If they absorbed it then there'd be nothing for an observer, said predator fish, to detect. I don't think we're talking about fluorescence here (this being what us humans see when a substance absorbs light in the UV spectrum and, as a result, emits light in our visible spectrum).

Isn't that what I just said?

 

So, with UV materials - what are they supposed to be doing? Absorbing from the visible and reflecting in the UV, or what?

I was focused on the last point of your earlier post

---------- Post added at 09:18 AM ---------- Previous post was at 09:15 AM ----------

Col,

The commonest use of this phenomenon is in washing powders where near UV energy is absorbed and then emitted in the blue area of our spectrum - to make white clothing material etc appear "whiter than white" - and for 'fluorescent' paints and dyes.

Also in paper - nice bright white paper - an issue for fine art printers who want to avoid this like the plague because they fade over time.

---------- Post added at 09:22 AM ---------- Previous post was at 09:18 AM ----------

Thanks - that was what I was needing to know - that there is no 'boost' like you get with fluorescent materials. So, just a higher reflectivity of the UV spectrum. Well, they are certainly the 'in-thing'. Some in favour, some agin

Col

My bet is that the basket of "UV" material out there is a collection of both UV reflective and fluorescent material. Note sea anglers often use fluorescent material which they charge with a UV torch.

 

Col,

Put simply, UV reflective 'materials', the subject of the current fad, do just just that. They reflect a high proportion of UV wavelengths of light incident upon them although the proportion reflected is dependant upon the wavelength (and the composition of the 'material').
If older trout can 'see' this reflected UV and do use it for food selection then it might be useful to us as anglers.

As you know, the majority of humans cannot see these wavelengths because the lenses in our eyes act as a filter. Similarly, the lenses in the eyes of Brown trout become more opaque to UV as they age (see papers by Yvette W. Kunz et.al.) and this is probably the case with Rainbow trout also ( it's likely) but there has been very little written about this aspect regarding the latter named fish as all of the research appears to have been done only on juvenile and smolt (immature) aged fish.

UV fluorescent materials absorb UV wavelengths and emit a proportion of the energy in the visible spectrum thus adding to the reflected visible wavelength(s). The commonest use of this phenomenon is in washing powders where near UV energy is absorbed and then emitted in the blue area of our spectrum - to make white clothing material etc appear "whiter than white" - and for 'fluorescent' paints and dyes.
Fluorescent materials are generally thought to be useful when used in some fly patterns.

Dave.

 

Col,

Put simply, UV reflective 'materials', the subject of the current fad, do just just that. They reflect a high proportion of UV wavelengths of light incident upon them although the proportion reflected is dependant upon the wavelength (and the composition of the 'material').
Dave.

Thanks - that was what I was needing to know - that there is no 'boost' like you get with fluorescent materials. So, just a higher reflectivity of the UV spectrum. Well, they are certainly the 'in-thing'. Some in favour, some agin

Col

 

UV isn't only found in manufactured materials! Lot's of bird feathers have highlights that reflect in the UV spectrum. Some birds see in Ultraviolet, so that robins' breast isn't only red, it's also got a bit of bling going on.

Just off the top of my head I'd say - peacock, jays, golden pheasant neck feathers - in many wet fly recipies as a tail feather. I bet a lot of mallard wing feathers are UV reflecting - the list must be endless.
The pigments that reflect UV can be pretty much anything - pink, green, red, blue, purple. Even some white feathers have UV patches.

Example of UV:

R-L: through human vision (R+G+B), only UV vision (bright = UV), simulated bird vision (tetrachromatcic: UV+R+G+B)

 

Some birds see in Ultraviolet, so that robins' breast isn't only red, it's also got a bit of bling going on.

Yes, from what I have read most, if not all, birds use UV.

Rather surprisingly, recent research has shown that some species of Bats also posses UV cones.
Whilst in total darkness they use echo-location to hunt their prey, at dusk when there is still a reasonable amount of UV present, this UV capability is useful to spot UV reflecting insects. It is speculated that it is also used by those species of Bat that feed on nectar to locate the best food providing flowers.

Dave.

 

I dont think Kingsmill Moore had too much UV materials in his flies. And they worked just fine. :thumbs:

 

That's exactly what I'm talking about - his flies would have had the natural UV properties from the feathers used - so actually he did use UV materials.
Perhaps some of these feathers with good UV properties have made their way into patterns over the years because of the UV light they reflect and the fish attracting properties- rather than the look of the fly in our visible light spectrum. Just a theory.

Stan - I think the idea is to simulate life as closely as possible... Which is why I once asked the question - why not magnetise a fly hook? That way it will have a small magentic field, which a fish with it's lateral line can detect - but that's been discussed before - ie: brassies being made of wound copper wire over a steel hook - that will create a small magnetic field, and does that have an effect on the simulation of life? I must now say - I don't magnetise my hooks, but all you people out there with magnetic fly holders...

Really interesting discussion.

 

This is all very interesting, and excuse me if I'm getting this all wrong, but are we talking about two very dissimilar things here. Many materials have a 'UV' ticket attached to them which simply have a violet flash and have nothing to do with ultra-violet light, which we can't see anyway, and fluorescent material which absorb UV light transferring it into the visible spectrum.

Secondly, there is a peculiar fact about living things in that they seem to be 'brighter' than inanimate objects. A hare in a ploughed field is much more visible (stands out) than the similarly coloured stones around them. In torchlight, at night, living things seem to glow with life whereas inanimate objects (sticks, stones, etc.) are dull and lifeless. Are we using fluorescents to imitate this 'living glow'?

 

Stan,

If the GP feathers reflect UV you wouldn't be able to see it anyway

I think the only way you may be able to detect it would be to photograph the UV illuminated feathers through a UV 'pass' filter (one that excludes visible light).
From what I have been told, many digital cameras are sensitive, to some degree, to wavelengths below 400 nm - I'm sure someone on here will know more about this and will correct me if I'm wrong

Dave.

 

Well, I understand that, and I would suppose that any vaguely reflective surface would reflect uv light, whether the human eye can detect or no.

My point was that there is no evidence of fluoresence from gp feathers when uv light is shone on them. mg:

 

Stan,

I understand now.
From the quotation you posted I assumed you were hoping to see reflected UV not fluorescence.

Dave.

 

Interesting that, thanks Gander.

Shame it was wasted effort - we now know IR starts at about 900nm but Salmonids vision cuts off at about 800nm - but, as you said, at least he was thinking about how the fish might be viewing his flies rather than just blindly following tradition.

Dave.