Episode Details

Dr. Trevor Keyler has spent years investigating what the underwater world looks like through the eyes of a walleye. His research reveals a fish with an astonishingly sophisticated visual system — one perfectly adapted to hunting in the low-light world beneath the surface.

Trevor explains how walleye eyes capture incredibly faint light, why they're most sensitive to the blue-green wavelength and how water clarity dramatically changes the underwater light environment. And then there's this jaw-dropping finding: under ideal conditions, a walleye can detect light at depths approaching 77 metres .... or 250 feet.

But there's much more to the story than simply, "How deep can a walleye see? " Trevor explains the crucial difference between detecting light and seeing prey well enough to capture it — and his findings offer fascinating insights into lure colour, contrast, silhouette, water colour, twilight, moonlight and why walleyes come alive as the sun is disappearing.

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