Trout On The Look Out

Sunday evening, I was clicking through the news channels … Michael Jackson was the only subject.

Click: Reports that MJ was spotted living incognito in a northern Minnesota trailer park prove false. … Click: Authorities deny that MJ was sighted exiting a roadside dinner in rural Arkansas. … Click: Alien spokesbeing in Roswell, New Mexico, denies report that MJ has applied for asylum at their embassy.

Multiple clicks finally let me escape the Great Dismal Swamp of News to a show about fly fishing for winter steelhead in Canada – a pleasant change of pace.
But the pace was slow for a guide and his guest, so they decided to try another stream. When they arrived, the guest remarked that the guide had placed him much closer to this pool than at the others.

“Well, the fish are holding right down on the bottom,” the guide replied, “they can’t see out all that well.”

That guide got it all wrong … absolutely bass ackwards, as trout anglers like to say.
Anatomy and environment give trout some remarkable visual abilities, and they can take a good look at the world from the bottom of theirs.

Trout anatomy creates an eye with remarkable abilities. The lens shape projects a focused and detailed image to all parts of the retina.

This is radically different from human vision. Our ability to see detail clearly is confined to a small area on our retina, and we have to turn our head or redirect our eyes to clearly focus on an object. Trout perceive objects at the edge of their field of view with full clarity. 

Speaking of that field of view, the placement of a trout’s eyes combined with the eye’s structure gives trout an arc of vision that extends 320 degrees. If you had the same field of view you’d be able to see your ears and the back of your shoulders.

Trout also have the ability to use both monocular and binocular vision. They can focus on two different objects simultaneously by using each eye individually. Directly in front of them is an area where both eyes can be used to perceive distance accurately. That’s vital for their ability to seize prey.

Their environment provides the final remarkable elements of their visual abilities. Light striking the water at an angle of less than 10 degrees is reflected and light striking at a greater angle penetrates. From the trout’s position, this creates two distinct areas on the water’s surface, the window and the mirror.

The window is a circular area above the trout through which it views the world outside the stream, and its size is directly proportional to the trout’s depth. The deeper the trout holds the more of the outside world he sees.

The mirror occupies all the rest of the surface visible to the trout, and it reflects an image of the stream’s bottom. This give the fish an ability to view in the mirror what’s on the other side of solid objects in its direct line of sight.

Don’t underestimate their abilities. Trout are always on the lookout for danger.