April 13, 2023 at 11:27 a.m.
The Lake Where You Live
They own the night
By Ted Rulseh-
The walleyes actually spawn a few hundred feet west of where we live; our piece of lake bottom is silty sand, and walleyes prefer a hard substrate. But a neighbor down the way has told me about shining a flashlight into the water at night and seeing the reflection in the eyes.
Ah, those eyes! They are the walleyes' trademark, for their appearance and for what they allow the fish to do: hunt and feed successfully in low light and at night. Fisheries biologist Paul Radomski, in a recent presentation at the North Lakeland Discovery Center, showed a picture developing walleye eggs.
Take one guess what features was apparent at this early stage of life. That's right: the eyes. And in walleyes from fry to adult, the eyes are the keys to success in lake and river habitats.
Walleyes' eyes are adapted to be highly efficient in gathering light. In dimly lit conditions they can see where their prey fish cannot, and that gives them a huge tactical advantage. They don't see well in complete darkness, such as in the middle of a moonless night or under ice covered by a thick blanket of snow.
And they don't see in great detail. The retinas in the eyes have rods and cones, the basic cells that enable vision in humans and many creatures. The cone cells let the walleyes see colors, and some details like the color patterns on lures. But those cone cells are among the largest in the animal kingdom, and that makes walleyes' vision somewhat fuzzy. Think of the pixels in a computer screen. The larger the pixels, the less sharpness in the on-screen images.
Walleyes do see in color and are best able to see the longer-wavelength end of the visible spectrum (orange, red, green). The eyes are the most sensitive to green, which happens to be the color that pierces deepest into lake water, Radomski says. In very low light they don't see color, only shapes and shades of black-and-white. The eyes are positioned to look mainly to the sides.
Walleyes' eyes have the ability to make the most use of light entering through the lens and the fixed-size pupil. Faint light passes over the rods and cones. The light then hits a structure called the tapetum lucidum and is reflected back, so that it passes over the rods and cones again. This is why the eyes are reflective when hit by a flashlight beam.
The extreme sensitivity to light explains why walleyes during daylight take to deep water or hide out in the shade of weedbeds. Even here on Birch Lake where the water isn't especially clear, it's hard to find walleyes out in the open when the sun is shining. The best times are cloudy days and around dawn and dusk.
Walleyes are perhaps best described as stealth predators. They prey on fish that don't see nearly as well when the light has faded.
Ted Rulseh is a writer, author and lake advocate who lives on Birch Lake in Oneida County. His new book, "Ripple Effects," has been released by UW Press. You can learn about it by visiting his website at https://thelakeguy.net.
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