Steelhead Vision

What do steelhead see?

Do you ever find yourself asking this question? The real question starts with asking "how do they see?" Lately I have been reading a book titled What Fish See by Colin J. Kageyama, published in 1999. I would like to share with you my learnings on the topic of how these beautiful creatures see and how it relates to catching them.

Why am I so interested in learning how they see? Because I still have never caught one and the rest of this year I am dedicating my life to gaining more knowledge and experience about steelhead and steelhead fishing as to aid in my life journey and goal of landing a big beautiful bling bling chromer in my hands, with my camera ready of course!

With that said let's continue to the super-interesting scientific part that I love. Steelheads eyes change twice during their life in freshwater and in the ocean due to visual pigments in their eyes that enable them to adapt to the change in water color, light, food, predators, etc. It is amazing how mother nature plans these kinds of things. As a baby fry, a visual pigment called porphyopsin makes the color-sensitive cells in its eyes sensitive to red light. This enables them to see in bright, shallow, fresh water conditions to find food, and survive until it gets out to the ocean.

After becoming a smolt it goes downstream towards the ocean. Once it's in the ocean, its eyes change again to allow it to survive in saltwater. The photochemical in its eyes become rhodopsin, which is similar to the pigment in human eyes that we use for night vision. In the depths of the sea, the light reaching the steelhead is blue and green, thus this photochemical makes its eyes sensitive to blue and green light to enable to find food, stay away from predators, etc..

When the steelhead returns to freshwater as a mature adult to spawn, the color-sensitive cells in its eyes convert back to porphyopsin and become sensitive to red light again. It makes it easier to find other steelhead as mentioned before, and of course, eggs to fertilize (sexy time)! Once the chemical change is complete it will be able see in bright, shallow water conditions again that would have blinded it when it first came from the deep, blue, green ocean.

Now for the technical application. Let's go back to the question "What do steelhead see?" Below I have posted an excerpt from this book which describes in further detail how color shifts in the water, distance, water clarity, and lure/fly colors affect a steelhead's vision:

"A summer steelhead shot across the river toward a small spinner. The fisherman braced himself for impact, but at the last instant the fish pulled back and did not strike. What happened?"..."It was a bright sunny day in a large clear pool of water. The steelhead spotted the spinner when it was about 20 feet away. It was attacking a small red spinner when the decision was made to move on the lure, the spinner appeared to have a black body, black blade and dark tail. When the fish got within 5 or 10 feet, the spinner probably appeared to change color to bright red. The steelhead 'put on the breaks' and appeared to stop within two feet of the spinner, then swam away. The color shift from black to red was unlike anything that the fish would observe in nature. Had the lure maintained its dark appearance for the entire distance, it is likely that the steelhead would have ended up on the hook."

Any comments or questions?