Line/rod flash & false casting

[davewallbridge]

macd,

It's worth reading through to the end but you may have to do this bit at a time. ....... :-) !!
If you need a glossary to explain some of the terms these can be found on-line. Do a 'Google' for "Glossary, Neurobehavioral / Neurobiology" or similar (useful for any subject also).

Dave.

[albyn73]

Fish cant feel no pain, nor can they experience fear, just the same as fish only have a thirty second memory, aye, but they always know where all the good snags are when they have'nt been in the river that long. And all these flashy rods, lines, watches and all the other wee flashy things that hang from an anglers vest & jacket. Then you go and put on a big flashy tube to catch a salmon. With all this debate about flashy rods, i wonder what Miss Georgina Ballantyne would have made of it all....

[severnfisher]

And why would a salmon connect any of the above with the fly?

Your logic is a bit ropey Willie.

Of course they can't connect the two intellectually, but the disturbance can still put them down. They are wild.

Are people saying that stealth is of no importance? Surely not.

[tynetraveller]

Re. WG's point about salmon IQ- It isn't high. Take a look at the Utube clip of a load of (fortunately pacific ) salmon that took a wrong turn and got themselves trapped in a tiny dead end inlet.

www.youtube.com/watch?v=AXtJfZIbbyU

[splash]

davewallbridge said:

williegunn said:

And why would a salmon connect any of the above with the fly?

Quite agree , Willie.

From what I have read, lacking a developed neocortex, fish are not capable of abstract thought (awareness) so cannot connect line shadow etc. with the fly or human activity. Nor can they experience fear or pain as we perceive those emotions.

There is an interesting paper here :

www.nal.usda.gov/awic/pubs/Fishwelfare/Rose.pdf

Hard work but some interesting facts IMO.

Dave.

This is a really good thread and I'm sorry to come late to it. Fish may not be capable of abstract thought and associating line flash or shadow etc with human activity, but they sure can associate it with danger. I remember fishing Rutland with dry flies several years ago and one of our party was using a Cortland 444SL (the mint green one). This line clearly gave off line flash and spooked fish when when cast overhead and the results were all too clear -nae fish. Side casting with dull lines such as the aircel ultra in buckskin or mastery xps made a massive difference to catch rates. What was interesting here was that line flash as opposed to line colour or rod flash was the key problem
On the other hand, as Jock Monteith has already alluded to, underwater flash can have a positive effect as anyone who has ever fished a spread for tuna will know. The addition of teasers with inbuilt mirrors will often transform a quiet day and the chance of multiple hook ups increases dramatically once a fish is hooked and starts to flash and that competive thing with the others in the school kicks in. How many times have you had another fish follow a hooked fish to the boat?
For me though , the bottom line is that you will always have a greater chance in any form of fishing with a quiet, stealthy and considered approach and for me that means nae flashing !

[davewallbridge]

splash said:

For me though , the bottom line is that you will always have a greater chance in any form of fishing with a quiet, stealthy and considered approach .......

splash,

I agree with that, absolutely.
Living next door to the Dyfi most of my fishing is for Seatrout - don't think I need to say much more !

Unlike yourself, I have never noticed any problems related to line colour or flash but on the river I seldom false cast or spey cast and on stillwaters (trout), fishing from the bank, I mainly target fish in the margins and use a curved cast to present the fly.
My thoughts on this subject are that, when using a floating line, the fish should never have the opportunity to see the fly line or it's shadow.
I think it's a different matter when it comes to the sunk line though and I have no worry about my sink tip or intermediate line crossing in front of the fish. There are so many odd bits and pieces - weed, bits of tree etc. - travelling down a typical river that a thin, dark coloured line would not stand out as a particularly unusual object.
As the linked to paper explains, the fish are not capable of associating such an object with the following fly or my activities.

My earlier post was really just to point out this fact and to give the other members the opportunity to read what I think is a very informative technical paper.

Dave.

[severnfisher]

Hi Dave,

I found it an interesting read, thanks very much for putting up the link. It provides a very well grounded critique of some of the anti's propaganda.

The point about line flash, shadows from a floating fly line, etc is that they can trigger predator avoidance behaviour.

This discussion has reminded me of a EA worker's description of the behaviour of salmon, sea trout and rainbow trout fry in hatchery conditions.

When the lid is taken off the tubs, the rainbows cruised near the surface, apparently undisturbed, the salmon dropped down in the water while the sea trout bolted and tried to hide under the rim.

Tom

[splash]

severnfisher said:

Hi Dave,

I found it an interesting read, thanks very much for putting up the link. It provides a very well grounded critique of some of the anti's propaganda.

The point about line flash, shadows from a floating fly line, etc is that they can trigger predator avoidance behaviour.

This discussion has reminded me of a EA worker's description of the behaviour of salmon, sea trout and rainbow trout fry in hatchery conditions.

When the lid is taken off the tubs, the rainbows cruised near the surface, apparently undisturbed, the salmon dropped down in the water while the sea trout bolted and tried to hide under the rim.

Tom


Find that hard to believe having both conducted and observed some scientific c research looking at behaviour al patterns of both salmon, brown and rainbow trout at the parr stage in the past without any obvious differnces in "shyness". My favorite EA story was the (true) one when they turned up at a famous Tweed beat recently. "which way is the sea asked the EA biologist to the (incredulous) ghille !!!

[hornet]

If flash is actually a put off for targeted fish then why has all the various tackle manufacturers not seen or discovered this during the testing / researching phase.

You would think that all kit would be <= 30% low matt finish which would eliminate flash from tackle. I for one have not really given flash from tackle much thought apart from leader material when i fish for bows.

Must check this when out next.

Hornet

[severnfisher]

Hi Splash,
It is possible the story might have been embellished a bit, it is after all a fisherman's story , but knowing the source I would be surprised if it was made up entirely without any basis in fact.

More importantly, what, if anything, did you find out in the research you mentioned that has a bearing on the current discussion?

Tom

[splash]

severnfisher said:

Hi Splash,
It is possible the story might have been embellished a bit, it is after all a fisherman's story , but knowing the source I would be surprised if it was made up entirely without any basis in fact.

More importantly, what, if anything, did you find out in the research you mentioned that has a bearing on the current discussion?

Tom

Aye, most probably embellished a bit but a good story nevertheless... :)The research was really some personal experience that I had doing my biology degree research project over 20 years ago (sigh). I was looking into optimotor responses of salmon and trout (to establish whether they could see in colour) and had to keep them in tanks. They all behaved pretty similarly in terms of their response to the presence of humans but I concede that we didn't have sea trout parr or fry

cheers

Splash

[severnfisher]

Hi Splash,
I know it is off topic, but did your work cover the question of a shift in bias from the blue to red end of the spectrum in fish returning from the sea?

[stalker]

hi Gents
i have been following this thread with interest. Each year i actually dive in a selection of holding pools and waterfalls to check the amounts of salmon going up. Whats interesting is when i enter the water and just hang on the surface the salmon dont really react to much but when i dive down about 8ft, i have a particular rock i hang on to. What amazes me is that as long as i stay in that position the salmon cruise around me as if curious, even swim by my face without what appears to be any fear, i think this is because i am a part of their environment.

I have also had a friend cast while under the water to see the reaction of the salmon, their appears to be no real reaction to the line on the surface. What was even more noticable is that a white line appears to be more transparent against the sky making it less visible but darker colours do show. To me taht makes sense of predatory fishes under belly being a much lighter colour, generally white in the salmon and sea trout cases, that i would put down to the fact they are migratory fish and the sea has an impact on that colouring.

We also studied the reactions of a fish taking in low water conditions. I would estimate approx 150 salmon lined up in a nice pool ready to go up a small waterfall approx 5ft. We crept up on our hands an knees from above and cast over the top, a guest was watching from a vantage point overlooking the pool, after the 4th cast a fish took. The interesting bit is that the fish did not react until the one that took and then it was a type of blind panic, Salmon jus shot of over the whole pool hiding under rocks and whatever cover they could find. I took about another half hour before they began to show themselves around the pool again and the next fish was taken. The conclusion we came to was it was obvious that a fish in distress creates the problem, and bear in mind this was in extremely low water conditions.


mike

[elwyman]

Thanks for that Stalker, some interesting experiences there.

I often fish for sea trout at night in low water conditions, so your comment about a hooked fish causing panic in other fish was of interest.

It is not unusual to catch a sea trout, and then 2 or 3 more in quick succession. This would suggest that the sea trout are not alarmed by the distress of the first fish - but it could also mean that fresh fish are moving into the pool, so not as conclusive as your observations!

[stalker]

Hi Elwyman
I think that when fresh fish move into a pool it always creates a little action which causes more aggression. I often find that is generally a point when takes are very good and frequent for a short period+ but sea trout are feeding, salmon are in more a state of aggression. I have sat for many hours looking at what happens when new fish are entering a pool, one in particular as it is easy to see the fish entering but then the pool drops of quite deep. What has always been noticable then is activity below the surface of regular rapid flashes of silver of salmon showing their sides. I would put that down to upseting the pool and jockying for position. Some salmon are technically just passing through but to others its their spawning ground.

i have also stood hidden above a pool watching a friend cast over a grilse in water of i would say no more than 18" to 2ft with the fly passing right on its nose, no reaction at all. I beleive if a fish wants your fly its going to take it

[davewallbridge]

severnfisher said:

Hi Splash,
I know it is off topic, but did your work cover the question of a shift in bias from the blue to red end of the spectrum in fish returning from the sea?

Tom,

I spent a bit of time looking this up a few years ago following a discussion on the original FFF - a copy of the resulting post, slightly shortened, can be seen here:

www.sexyloops.com/articles/whatsalmonidssee.shtml

The actual mechanism, as described to me by Julian Partridge (prof. of Zoology) is -

" ..... As they move from freshwater into the sea migratory salmonids shift the spectral sensitivity of all their retinal
photoreceptors to shorter wavelengths. They do this by incorporating the aldehyde of vitamin A2 in place of the aldehyde of vitamin A1 in the visual pigments of their retinal photoreceptors. ...."

The effect is to change the chromophore in their visual pigments from retinal to dehydro-retinal when migrating from sea to river. This changes the name of the visual pigment from rhodopsin to porphyropsin and shifts sensitivity towards the red. The reverse change occurs when migrating from river to sea.


Dave.

[stalker]

Quote Sexy Loops article-
" On my local river, many of the old hands swear by predominately blue flies when fishing the lower reaches for fresh run fish. If the new arrivals colour vision was still blue shifted or in the transition phase, this might be a contributing factor to its success. "

Thats an interseting article and have read this before. I must admit when fishing estuary pools and based on past successes i now only use small tubes, mini type Sunray Shadow but with pure silver body and pure black hair wing about 1.1/4 ". I have also noticed when fishing sea trout in Saltwater bays again the same colouring is most succesful for Sea Trout but Blue I have never had any luck with.

mike

[splash]

severnfisher said:

Hi Splash,
I know it is off topic, but did your work cover the question of a shift in bias from the blue to red end of the spectrum in fish returning from the sea?

No it only looked at histological examinations of the retina to evaluate what receptor cells were present and then optimotor responses to see if they would follow colour stimuli (they did). I was pretty crude really but showed that both rainbow trout and salmon did follow colour stimuli

cheers
Splash

[severnfisher]

Thanks for that Dave and Splash