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Harrington: How Light Intensity Impacts Walleye Fishing

Harrington: How Light Intensity Impacts Walleye Fishing

By Nick Harrington,

There are many factors that walleye anglers need to consider when they hit the water. Anglers are constantly looking at factors such as wind direction, wind speed, cloud cover, temperature and water clarity to dictate where and how they should target fish. Whether you are discussing wind, clouds or water clarity, they all factor into one topic: light intensity.

Walleyes are famous for their low light vision capabilities. They’re equipped with more rods than cones in their eyes and most famously their tapetum lucidium. This is the organ responsible for the shine we see when light falls on a fish in the water or on our line. This organ captures all available light in the environment and allows the creature to harness that light to enhance their vision capabilities. This is the same organ found in mammals, such as deer, dogs and other organisms that are known for their eye shine.

Walleyes are adequately equipped to feed at all times of the day, but they are most active during twilight periods. This is because their prey is still active, but their vision capabilities are quickly fading. This makes them vulnerable to attacks from walleyes. Indeed, there are lakes that are known for an outstanding night bite and there are other rivers and reservoirs where you can catch fish all day long. The ability to target fish at different waterbodies is one of the aspects that makes walleye fishing so exciting.

Light intensity is import to walleyes for two reasons: comfort and foraging. Increased light intensity can make walleyes, particularly larger walleyes, uncomfortable and drive them to deeper water or shaded areas to become more comfortable. Decreased light intensity allows them to utilize their vision capabilities to give them the edge over their prey, triggering feeding. Light intensity impacts anglers every time they hit the water, whether they know it or not. Many anglers, particularly anglers fishing from shore, will focus their fishing efforts around sunrise or sunset. During the twilight period, walleyes are often most active and utilizing their low light capabilities on prey. In addition to when anglers fish, anglers are often looking for where the wind is creating a “walleye chop” or dictating what waterbody they fish based on its water clarity.

Harrington: How Light Intensity Impacts Walleye Fishing

How Photoperiod can dictate when walleyes will begin to bite

The first, and arguably most important factor in light intensity, is photoperiod. Photoperiod is how long the days are based on the length of the light. This will stay consistent all year long and not be impacted by weather conditions or other factors. Photoperiod is a major driving factor in spawning activity, as well as other major natural activities, such as bird migrations, the rut in deer and even vegetation growth.

On a more specific level, photoperiod can also dictate bite windows on an individual day. In fact, these specific bite windows are often most visible in trophy caliber fish. These patterns will emerge on rivers, reservoirs and lakes of all sizes. Walleyes, particularly large walleyes, are creatures of habit. They often become active when light conditions reach levels they are both comfortable and equipped to forage in and they will often have a short, intense bite window in which they are seeking larger meals.

Photoperiod can be used to dial in bites over a calendar year and also on a day-to-day level. As mentioned above, photoperiod is a major driving force in both spawning and seasonal movements of fish. While weather and water conditions, particularly water temperature, can have an influence on these activities, you can have a rough idea at approximately what time you should be look for fish and where.

Once you’ve determined where fish are and what they are doing, you can now start dialing in your bite on a daily basis. Stable weather conditions are when these patterns most emerge. Major environmental changes such as fronts, cloud cover, wind storms or runoff can impact these patterns on a day-to-day level, although they can still take place on a reduced level. However, when conditions are stable, you may be able to dial in a bite down to the minute.

How “walleye chop” impacts light intensity and feeding behaviors

Whether you’re a new walleye angler or a seasoned veteran, you’ve liked heard the term “walleye chop.” This term is the wave action created by the wind. This is an important aspect for walleye fishing because these waves will break up light penetration, keeping depths below dark and thus more comfortable and advantageous for walleye to forage.

The mechanics of this are simple. In calm conditions, sunlight will be able to penetrate to greater depths in the water column. These brighter conditions can drive walleyes, particularly large walleyes, deeper and put them in a more negative mood when it comes to foraging. In these conditions, their forage, such as perch, shad or shiners, will have greater vision capabilities and will largely be able to forage without fear. Walleyes will choose to relax in a more comfortable environment and wait for light conditions to decrease.

When the wind blows and the waves begin to rock, the wave action will refract sunlight and decrease the depth and intensity that light can penetrate into the water column. The greater the wave action, the less the sunlight can penetrate. Even on bright, sunny days, significant wave action can keep light conditions below the surface relatively dark and, in turn, more comfortable for walleyes. On days with an abundance of walleye chop, walleyes may take advantage of their vision capabilities and forage all day long.

In addition to breaking up light penetration, waves will also stir up sediment on the shoreline that will become dispersed in the water column. This will cause mudlines along the windblown shorelines and further darken the water column. It is no secret that fishing along windblown shorelines or structure is often quite productive. This is because aquatic invertebrates or bugs that float helpless in the water column will be pushed onto these areas. Juvenile fish and other baitfish will move onto these areas to feed on these invertebrates. Walleye will follow these baitfish and take advantage of the decreased light conditions to stay comfortable and effectively feed all day long.

Water clarity plays a major role in how walleyes will act throughout the year

The final factor in light penetration is water clarity. The clearer the water, the further the light can penetrate. As zebra mussels move across the walleye belt, water clarity continues to become an even more important topic in the sport of walleye fishing.

Zebra mussels are filter feeders. They filter plankton out of the water and reproduce at intense rates. When you combine their ability to establish a large population and filter vast amounts of water, it doesn’t take long for a newly invested zebra mussel waterbody to become very clear. In addition to making the water clearer, they also reduce plankton populations available for juvenile fish and other native species.

Water clarity impact walleye anglers’ fishing in a variety of ways. The first is light penetration. The clearer the water, the fewer particles there are to break up light penetration. Dirtier water lakes will naturally reduce light penetration regardless of wave action or other factors.

Anglers who are fortunate to have multiple good fisheries near them may pick and choose what lake they wish to fish based on light conditions. Clear water fisheries are often best for targeting in twilight conditions, when the waves are rolling or on overcast days. Dirtier water fisheries are often best for targeting in bright conditions and can often produce in the middle of the day.

The second major factor in water clarity is weed growth. Many classic zebra mussel fisheries will exhibit submerged weed growth in as much as 20- to 25-feet deep. As mentioned above, the clearer the water, the deeper the light penetrates. The deeper the light penetrates, the deeper weeds can grow. If there is adequate light, plants can carry out photosynthesis and grow to deeper and deeper depths.

Clear water fisheries are likely to have an abundance of submerged vegetation growing beneath the water’s surface. The clearer the water, the deeper that vegetation can be found. These lakes often present excellent weed line bites at any time of the year. If the weeds are green, there will likely be forage and, in turn, walleyes not far away.

Dirtier water fisheries are likely to have more emerged vegetation as opposed to submerged vegetation. This is because the dirty water prevents sunlight from penetrating through the water column and submerged plants are unable to carry out photosynthesis. This forces the plants to break through, or emerge, from the water to reach the sunlight they need. These fisheries are often adequate weed lines to hold fish and are more likely to have a basin or mud flats that hold most fish.

Light intensity is a factor that impacts anglers every time they hit the water, but the most successful anglers are the ones that can understand its impact on fish. Before you hit the water, consider how the light conditions will impact the fish. Understanding these conditions in the waterbody you’re fishing will help you catch more fish throughout the course of the season.

Thanks to Nick for sharing these awesome tips. For more information or to book a trip, visit

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