August 29, 2013
By Matt Straw
Physicists say time stands still at the brink of the event horizon in a black hole. For one veteran angler, replays of giant walleyes gliding into the net over a lifetime create a similar event. In a way, all those walleyes were caught at the same moment. That moment is called "civil twilight." It occurs every morning, and again each evening. It may last five minutes or so in the middle latitudes. At the poles, where night lasts all winter, civil twilight can endure for weeks at a time. "After 40 years of guiding, I don't know of a time during the day when the odds are higher for catching a trophy walleye," said Greg Bohn, author of Master the Art of Slip Bobbering. "It's certainly the best time for trophies during August and September. It's when the biggest fish in the system make the most mistakes. The few minutes of civil twilight that occur each day are when the odds for netting a trophy walleye grow exponentially. "Civil twilight is that brief moment when light is brightest during each twilight period," Bohn continued. "It happens when the sun is actually below the horizon. In the evening, the sky is getting darker and suddenly brightens. It occurs briefly before sunrise, too. Civil twilight lasts just a few minutes. After keeping records for years, I have no doubt that walleyes are very aware and ready for those few minutes to occur. It triggers feeding and the end of it triggers the end of feeding and turns them off like a switch for the rest of the day. I've guided clients to more trophy walleyes during those few minutes of civil twilight than all other time periods during the day combined."
Avoidance or Signal?
What is it about twilight? "Are walleyes just freaked out by a lot of light?" Bohn asks rhetorically. "I don't think so. The way I see it, civil twilight is a signal that registers. They notice that slight change in the intensity of light, and I think changing light levels literally tell walleyes how to behave this time of year. During that few minutes, big fish make big mistakes. It's bizarre how many trophies are caught at that brightest moment just before it gets dark in the evening and again just before the sun rises. It happens night after night, all summer long. That moment, twice a day, is when trophy walleyes consistently make mistakes.
"Walleyes 27 inches and larger are cyclic feeders," Bohn added. "They're not spawning, not recuperating, and not stocking up for winter. They're feeding in a predictable, cyclic manner. You can time those cycles with light events. Trophy walleyes are systematic and reliable, like a fine timepiece. They tend to show up within seconds or minutes of the same time as the previous night, every night. One summer I boated the same 31-inch walleye two nights in a row within minutes of the same time on the clock."
He considers civil twilight to be a signal for bigger fish to binge, but thinks activity levels are always higher during the hour that surrounds each sunrise and sunset. "Even though civil twilight only lasts for minutes, there's about an hour of low light," he said. "The 30 minutes prior to and 30 minutes after sunrise and sunset are periods when big fish are more vulnerable than any other time of the day in summer. On cloudy, windy mornings, that bite extends into the day for another 30 minutes to an hour."
Approaching storms, warm fronts, cold fronts, wind speed, wind direction, and moon phases all bear watching, Bohn says. He keeps track of moonrise and moonset, too, and considers the hour surrounding those events to be times when big fish sometimes feed. But most anglers miss out on all of it. "Most people get in line to get off the lake before it gets dark," he said. "It's so common on every lake I fish. Every night, all summer, we're slipping nets under trophies when boat lights and trailer lights are lined up at the ramps. That's when all the good stuff happens, and nobody's out there. They're missing the bonanza — one of the most important moments of the day. I've netted countless 10-pound walleyes while watching taillights backing down the ramps."
In the morning, Bohn says he's often pulling out of the parking lot when the first other boats arrive. "You can see walleyes leaving the bars we're fishing with electronics when the sunlight hits the treetops in the morning," he said. "Doesn't mean you can't catch walleyes throughout the day, but the 30-inch-plus fish are done until evening. In summer, they stop biting around 4 a.m. By 5 a.m., I'm getting off the water. The bite's over and other anglers are just beginning to arrive.
"Too many 30-inchers hit at this magic time of day and time for it to be a fluke," Bohn added. "It's the deadliest period every day for trophy-size fish. When I hear of big fish being caught, it so often happens during magic time. Some nights are better than others may due to conditions, but whether it's cloudy or clear, you're still going to have two twilight periods and a good shot at a trophy every day. The opportunity is there regardless of conditions. But if it's cloudy, windy, or both — wow. I've had nights I never discuss with anybody because nobody would believe me. It's mind boggling what happens at civil twilight with some chop on the water."
As In-Fisherman has often reported, walleyes have a vision advantage over perch and most other forage species at twilight and throughout the dark hours. Bohn believes civil twilight triggers activity levels that allow big walleyes to use that advantage. During the two periods of civil twilight that occur each day, he sees the critical aspects of location as: 1) Main-lake structures; 2) Proximity to deep water; and 3) Boulders or weeds.
For Bohn, certain spots might as well have neon signs with arrows pointing into the water: "Big Fish Here." That's where his lines have to be when civil twilight hits. Throughout summer, he restricts his hunting to main-lake structures with certain critical features. "Mid-lake structures like humps, reefs, submerged islands, and bars tend to be the best trophy spots," he said. "I look for boulders on those spots. Boulders are critical for big fish at magic time. Big walleyes find those boulders every night. I don't think a spot can be too shallow or too deep at night. If boulders are present, walleyes might be there. The bigger the boulder, the better it is."
Another key spot is the peak of the bar, hump, or reef. "Big fish come right up to the top of the bar," Bohn said. "It might only be a 1-foot difference from the rest of the bar to the peak, but that shallowest point is magic. I like to see about 12 or 15 feet of water on top of that hump or bar. Deeper, too — but boulders are the key. If it's 8 feet deep with boulders, it's better than 15 feet with no boulders."
Alternative cover and proximity to deep water are the other aspects Bohn looks for. "If the spot is near deep water, that's great," he said. "If you can find 60 feet of water nearby and it comes right up to 16 feet, that's about perfect. Another key is weeds. Mid-lake bars bordering deep water with huge boulders outside a weedline are ideal."
In the hunt for big fish, Bohn creates a milk run of trophy spots on each lake and reservoir he fishes, spending only as much time on each one as the fish indicate he should. "I fish as many of those bars and humps as I can, every night," he said. "Not catching a 30-incher on a spot is common, so I just keep moving. One thing you don't want to find is a bunch of 15-inchers. You want very few bites. The spot tells you what you've got. Some spots I've found have boulders, weeds, and everything is right — but I never catch a 30-incher there. Conversely, once you catch a 30-incher off a spot, you're going to catch another one there at some point. Big-fish spots are always big-fish spots."
Temperature isn't a barrier. "Big walleyes move into water in the high-80°F range at night," Bohn said. "If you find a shallow bar with boulders in 5 feet of water, check it out. I have at least three places in mind before I set out every night. I pick those spots based on wind direction, heading to those bars that top out at 10 to 25 feet with boulders where the wind is blowing directly onto that spot. Waves at night are important. They loosen fish up. Waves create a sound barrier that helps anglers hide their sonic signature. It's amazing how walleyes respond to wave movement. They're on the move and active on windy nights. They're already moving before sunrise and before sunset when the wind is blowing. Walleyes take longer to commit to those feeding zones on calm nights."
Bohn has few preconceived notions about where trophy walleyes might choose to feed until he finds one and adds the spot to his list. Finding wallbenders, after 40 years, led to the development of a process. "A lot of the lakes I fish have big-fish reputations but are difficult to fish during the day," he said. "That generally means deep, clear lakes most anglers think are a challenge during the daytime. Anything that makes a good lake bad during the day suggests fishing it at night. You have better night-fishing on lakes after bad daytime conditions, too. Like high, cloudless skies with very little wind. I love it when I hear the daytime crowd complaining. That means the night bite will be hot."
The Many Faceted Twilight
Twilight is defined as those periods of time separating sunset from dusk and dawn from sunrise. Each twilight is divided into three segments by astronomers and navigators: Astronomical, Nautical, and Civil. Before sunrise, as the sun reaches a point 18° below the horizon, astronomical twilight begins. When the sun is 12° below the horizon, nautical twilight takes over. And when the sun comes within 6° of the horizon, civil twilight begins, and it ends as the sun reaches the horizon (sunrise).
The process is reversed in the evening, with civil twilight occurring first. The length of each period changes with latitude and with time of year. At the poles, civil twilight can last for weeks during early winter and again during late winter. At the Equator, the entire twilight period lasts 25 to 30 minutes through most of the year.
Casual observers may see no difference between night and astronomical twilight, but astronomers know it's the best time for using telescopes, especially for viewing distant galaxies. It's that "always darkest before the dawn" moment.
During nautical twilight, sailors can sight stars and still use them in reference to land masses. Outlines are visible, but detailed sightings are impossible without the aid of artificial light or night vision. Civil twilight is comprised of "magic moments" at the beginning and end of each day, when illumination caused by the scattering of light in the upper atmosphere makes the sky brighten just after sunset and again just before dawn.
Being perhaps the world's foremost authority on the application of slipfloats, it should come as no surprise that Bohn leans heavily on them during magic hour. "I need to have a lighted slipbobber out every night," he said. "We fish other tactics, too, but if we're going to fish into the dark, or start in the dark and fish into the light this time of year, at least one angler on the boat is using a lighted slipfloat. We use Thill Splash Brite and Nite Brite floats in magic time. Sometimes we all have lighted floats out. Water completes the circuit in the Splash Brite, so it automatically shuts off when you pull it out of the water. And I like the Nite Brite because you can replace the battery when it runs down."
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Bohn presents floats with 7- to 7.5-foot Leech Sticks he designs and markets. "I also pitch and vertically jig with those sticks," he said. "We've marketed the Leech Stick for 45 years now. It's versatile, with the right touch for jigging — medium power with an extra-fast tip. Most of my magic-hour spots are 15 to 20 feet deep on top, so I pitch and jig 1/8- to 1/4-ounce Lindy Jigs with 10-pound Stren Magnathin Green. I use 15-pound PowerPro high-vis yellow with slipfloats when we aren't pitching. Bright lines allow me to follow the float under water with my cap light after a strike, so I can see what direction fish are moving and maneuver accordingly."
Under his slipfloats, he uses pre-tied Thill Pro Series snells, which are offered in two styles. One terminates in a Lindy Bobber Bug Jig, and the other in a Tru-Turn hook. "Thill snells have 1/16- and 1/8-ounce Bobber Bugs, and I use both," he said. "Hooks tend to be better on calm nights when we're anchored, and I use #2 Tru-Turns. I like a big hook during magic hour."
It's a rare night when Bohn isn't carrying a variety of livebaits. His baitwells generally boil with various species of minnows, but he also carries jumbo leeches and big, bouncy crawlers. When hunting trophies, however, he maintains a preference for the latter. "The best big-fish bait I've ever put out is a whole nightcrawler," he said. "I nose-hook it, letting the whole crawler hang off the hook. I use it on a bladed snell or glow jig. My favorite color is glow red. It's the most productive color I've ever used at twilight. Something about a whole crawler on a red-glow jig at night drives big girls nuts. In summer, minnows aren't productive at magic time. Crawlers are my first choice — jumbo leeches are next.
"Thill rigs also feature small Indiana blades and red, faceted beads," Bohn added. "I like faceted beads. They catch light at more angles and flash brighter, helping walleyes zero in on them. The blade doesn't need to spin to add a little noise, flutter, and flash. At night, I try to keep the bait 1 to 3 feet off bottom. At night, we get real bites. Walleyes won't drop it. I let the float go down until it's almost out of sight. One of the coolest things every night is watching those lighted bobbers travel under water. It's exciting, so we wait until it's way down there before setting the hook."
He weights the rigs with 1/16- to 1/4-ounce Water Gremlin Rubbercor Sinkers because they don't damage his line. He places them directly on the 18-inch Thill snells, about halfway between the hook and the swivel. "Every night we try both styles of rig — hooks and jigs," he said. "I never know which will be more effective, but walleyes generally tell you. As a rule, if you're drifting or moving, jigs keep baits down in the strike zone better, but I tend to anchor at night.
"You need to be on your best big fish stand at the peak cyclic feeding time," Bohn added. "Arrive early, fish approximately an hour before and after twilight, and have all the kinks worked out and lines in the water when civil twilight arrives. We're only going to see 6 or 7 good bites. That's a great night, if you get 7 bites on big-fish spots."
Bohn kept his knowledge about civil twilight feeding sprees secret for 30 years. "I've never shared this pre-sunrise, post-sunrise feeding cycle with the media until now," he said. "Took years to share this pattern with anyone other than clients, but it's the peak of peaks for the slipbobber brigade at night." And now you know the rest of the story. Here's betting Bohn won't be watching your trailer lights this summer while netting giants in civil twilight.
*In-Fisherman Field Editor Matt Straw, Brainerd, Minnesota, has written for In-Fisherman publications for almost two decades. Contact Greg Bohn for guide trips and books, gregbohn.com.