How Light Level Affects Walleyes

Light level is the single most important influence on walleye behavior. It determines when and where walleyes feed, and where they spend their time when not feeding. Most anglers know that walleyes have light-sensitive eyes and shy away from bright sunlight, but they do not fully understand how light level affects their fishing.

The angle at which sunlight strikes the water determines how much of the light will penetrate. When the surface is calm and the sun just above the horizon, most of the rays are reflected. If the sun is directly overhead, most of the rays penetrate.

Sun angle can have different effects in different waters, depending on clarity. In low-clarity water, suspended particles or dissolved organic matter filter out sunlight, keeping light levels in shallow feeding areas relatively low. The examples below show how walleyes in a clear lake and a murky one react to changing sun angles. In these examples, the skies are clear and the surface calm.

The time of day at which walleyes feed may be much different in spring and fall than in summer. On the first day of spring and fall, the angle at which the sun strikes the water at 9 a.m. at the latitude of Lake Erie is about 30 degrees. On the first day of summer, the angle is about 50 degrees. In spring and fall, as a result, morning feeding periods last later into the day and afternoon feeding periods start earlier.

Weather conditions also affect the amount of light that penetrates the water. Although walleyes in clear water generally feed at dusk or dawn, an overcast sky or choppy surface can reduce the light level enough to allow some midday feeding. In some waters, heavy cover like boulders or tall weeds provide enough shade for occasional feeding during the middle of the day.

Canadian researchers have proven that the rate at which light intensity changes is the most important factor in triggering walleyes to feed. In a moderately clear lake, walleyes bit best as the sun rose above the horizon in the morning and as it disappeared below the horizon in the evening. Light intensity changed at a lower rate immediately before and after these periods, and walleyes bit at a significantly slower pace. This research also explains why walleyes bite so well when a storm is approaching.

How Walleyes React to Different Light Conditions

BRIGHT LIGHT. When exposed to a powerful spotlight held directly overhead, walleyes lie flat on the bottom. They remain virtually motionless, stabilizing themselves with their pectoral fins.

DIM LIGHT. When the light is turned off, the walleyes slowly become active. After about 20 minutes, they move about continuously in the tank. They spend much of their time a foot or more above the bottom.

SHADE. With the light directly overhead, a board is placed over part of the tank. The walleyes move to the shaded area. They move about somewhat more than they did in bright light.

ANGLED LIGHT. The light is moved to the side of the tank so that it strikes the water at a 30-degree angle. Much of the light is reflected, so the light intensity is relatively low and the walleyes are fairly active.

CLEAR WATER. (Above) At dawn and dusk (left), the light level is ideal, so walleyes feed heavily in the shallows. In midmorning and midafternoon (middle), light intensity is high enough to drive them deeper and slow their feeding. At midday (right), the intense light forces them into deep water and causes them to stop feeding.

MURKY WATER. (Above) At dawn and dusk (left), walleyes are in the shallows, but the light level is too low for feeding. In midmorning and midafternoon (middle), the light level is ideal. Walleyes remain in the shallows and feed heavily. At midday (right), light intensity is high enough to drive them slightly deeper and to slow feeding.


BRIGHT LIGHT. When exposed to a powerful spotlight held directly overhead, walleyes lie flat on the bottom. They remain virtually motionless, stabilizing themselves with their pectoral fins.	DIM LIGHT. When the light is turned off, the walleyes slowly become active. After about 20 minutes, they move about continuously in the tank. They spend much of their time a foot or more above the bottom.


SHADE. With the light directly overhead, a board is placed over part of the tank. The walleyes move to the shaded area. They move about somewhat more than they did in bright light.	ANGLED LIGHT. The light is moved to the side of the tank so that it strikes the water at a 30-degree angle. Much of the light is reflected, so the light intensity is relatively low and the walleyes are fairly active.


CLEAR WATER. (Above) At dawn and dusk (left), the light level is ideal, so walleyes feed heavily in the shallows. In midmorning and midafternoon (middle), light intensity is high enough to drive them deeper and slow their feeding. At midday (right), the intense light forces them into deep water and causes them to stop feeding.	MURKY WATER. (Above) At dawn and dusk (left), walleyes are in the shallows, but the light level is too low for feeding. In midmorning and midafternoon (middle), the light level is ideal. Walleyes remain in the shallows and feed heavily. At midday (right), light intensity is high enough to drive them slightly deeper and to slow feeding.