The incredible eyesight

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

The other day whilst I was packing my gear after a reasonable morning's success with the fly rod, I was taken by the number of trout jumping clear of the water to catch terrestrial insects, including adult damsel fliesthat where flying over the water's surface.

Some of these trout were jumping at least 5 feet out of the water and grabbing with pin point accuracy damsel flies which were flying erratically over the water.

Now think about this: A trout laying at about 12 inches below the water's surface has to maneouvre itself into position and with the power of its body leap high into the air and grab a flying insect. Not only that, the fish has toestimate where the insect will be when it jumps. Now the refractive index of water is different to that of air and obviously distances from under water look different to what they are. That makes what these rainbow trout were achieving even more remarkable.

I sat down and thought hard about what was happening all about me. Now I have fishing in umpteen different countries for lots of different species of fish and I have never seen a display of speed, power and sheer accuracy of sightingto equalthese rainbow trout. And they were all rainbow trout that I saw,I am sure of that.

I came to the reinforcement of a conclusion I made many years ago. Rainbow trout have probably the best eyesight of any fish in freshwater!

But what do you think?

Wolfman Woody · Sep 1, 2008

"Now the refractive index of water is different to that of air and obviously distances from under water look different to what they are. That makes what these rainbow trout were achieving even more remarkable."

You're perhaps being a little anthropomorphic there, Ron, judging their sight from and based your own experiences.

Ric Elwin · Sep 1, 2008

Dunno Ron. It's certainly a challenge to a fly angler though, how to present your Damsel creation 5 feet above the water...

coelacanth · Sep 1, 2008

<blockquote class=quoteheader>Woody the Moaning Marlow Meldrew wrote (see)</blockquote><blockquote class=quote>

"Now the refractive index of water is different to that of air and obviously distances from under water look different to what they are. That makes what these rainbow trout were achieving even more remarkable."

You're perhaps being a little anthropomorphic there, Ron, judging their sight from and based your own experiences.</blockquote>

Nah, physics is physics. Same things apply, roughly, although what we see as visible light and what a fish sees might differ.

"Best eyesight" is open to interpretation, but I would say that the Archerfish can top the Trout.

Mark Wintle · Sep 1, 2008

Five foot above the water? Easy use a helicopter rig!

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

But light travels at different speeds in air and water. That won't change whether a trout or a human is observing from under the water Jeff.

I can't tell you exactly what a trout sees, but the differences of refraction between air and water is going to change the way a trout sees the image, just as it changes the way a human sees the image, compared with seeing it in air for example

And I get the feeling that trout probably have better eyesight than we have in certain conditions.

I was speaking to my friend Derek Gibson today and he mentioned work that was done some years ago by a pair of Japanese scientists on what fish can see. He mentioned that various conclusions were made by these two people, including the fact that trout exhibited the best eyesight of the lot.

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

I had an idea that the archerfish might be mentioned here.

But I wonder.........

coelacanth · Sep 1, 2008

<blockquote class=quoteheader>Ron 'The Hat' Clay (ACA) wrote (see)</blockquote><blockquote class=quote>

I had an idea that the archerfish might be mentioned here.

But I wonder.........</blockquote>

There are stenohaline species of Archerfish BTW, before you point out they are euryhaline and therefore not true freshwater....

Some freshwater Atherinids are also pretty impressive, I've seenthem in aquariatracking a fly on the other side of the room.

Wolfman Woody · Sep 1, 2008

"But light travels at different speeds in air and water. That won't change whether a trout or a human is observing from under the water Jeff."

It doesn't matter, it's what the animal has evolved to seeing. It's optics and brain (even though simple) will allow for those differences.

Those differences you allude to are also the same as with a pair of spectacles and yet you need them Ron and couldn't see without them. Are you saying that light travels at the same speed through air and glass? Or that there is no refraction between galss and air?

Why then does an optometrist test your eyes and make allowances for axis and barrel distortions? Surely that's the same thing?

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

But a trout is watching from inside the medium of water to the medium of aira lotthe time. And the depth varies too, as well as the height above water! To adjust from water to air in my opinion is a very remarkable ability, and then to jump from the water an incredible distance, often up to ten times its own body length to catch an insect which is jinking about all over the place is quite honestly bloody incredible.

The trout doesn't succeed every time, but many times it does.

Spectacles have nothing to do with what we are discussing by the way. They are just extra lenses which are stuck on the front of our eyes to correct faults of vision.

I think this is a greater feat than even what an archerfish does which is a simple aiming procedure.

J K · Sep 1, 2008

<blockquote class=quoteheader>Mark Wintle (ACA) wrote (see)</blockquote><blockquote class=quote>Five foot above the water? Easy use a helicopter rig!</blockquote>

Helicopter Rig<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=6,0,40,0" width="425" height="350"><param name="src" value="http://www.youtube.com/v/nW150U-RuTE" /><param name="width" value="425" /><param name="height" value="350" /><embed type="application/x-shockwave-flash" src="http://www.youtube.com/v/nW150U-RuTE" width="425" height="350"></embed></object>

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

And catch a nice bluegill.

Where can I buy a radio controlled chopper, that looks like a lot of fun.

slime monster · Sep 1, 2008

that was a little disappointing i was expecting a giant rainbow to leap 5 ft out of the water and inhale the chopper.

Sean Meeghan · Sep 1, 2008

As I understand it the trout have no real concept of the surface and are strking at insects that they think are swimming above them. They will only be able to take insects that are nearly directly above them as refraction will make it impossible for them to locate insects significantly off centre. The insects will of course appear higher than they really are, but I expect that that won't really matter.

Ron 'The Hat' Clay (ACA) · Sep 1, 2008

The fact is Sean that after watching the trout jumping for flying insects for some time, I came to the conclusion that they didn't succeed with every jump.

I would love to get a camcorder with a long lens on the job and then slow down the action. Many is the time when the trout turn and twist in the air as if in the short time they have got, they are trying to orientate their bodies so that they can grab an insect. getting footage, however, is not going to be easy for obvious reasons.

I certainly think that trout DO have a a concept of the surface. One can see this when they take a floating fly or artificial.

Wolfman Woody · Sep 1, 2008

" I came to the conclusion that they didn't succeed with every jump."

So now you're saying their eyesight isn't all that good after all, otherwise they'd have a 100% score rate, wouldn't they?

Start off on one claim, then change tack, and finish with denying it ever happened most probably.

/forum/smilies/smile_smiley.gif

Never mind, at least you get to meet new friends every day. /forum/smilies/wink_smiley.gif

Morespiders · Sep 1, 2008

Ron, I cannot agree with you,the rainbows where Uncle Dave, Bibbyand Marsdenfish have terrible eyesight!!.

Cant remember last time one took their fly/forum/smilies/nerd_smiley.gif

slime monster · Sep 1, 2008

think they jump because ...................they can.

Philip · Sep 1, 2008

What about the Archer fish ? That must have pretty good eyesight to shoot its prey above the surface with a jet of water from below it ?

As for UK fish Ithought I saw some studies about Chub having Unbelievably good eyesight ....but the fishy mega boffins maywant to correct me on that.

Also what about poor water/low lightconditions? …I recon a Zander would take a Trout to the cleaners there.

The incredible eyesight

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