Many anglers can’t figure out the human spawning process, much less that of a largemouth bass, but understanding when and where the fish spawn is essential to bass fishing success in the spring.

Many factors affect the exact timing of the spawn, such as water temperature and photoperiod (day length), and most anglers believe the moon also has some influence. Bass migrate from mostly main lake wintering areas to shallow protected bays to spawn, and determining where they are in the spawning process is essential to locating them in the waters you fish.

Dr. Hal Schramm, a professor of fisheries at Mississippi State University, is one of our country’s leading authorities on largemouth bass and the spawn. He says that across both the plant and animal kingdom, photoperiod controls many major events including migration and reproduction.

“For most fish, photoperiod is probably the master switch, then temperature synchronizes it,” he said. “This is good, because reproduction in fish is all about the offspring – the fish spawn so environmental conditions, including food resources, are ideal for the offspring.”

He simplifies it by describing photoperiod as the circuit breaker, and temperature as the wall switch. For bass to go on the beds, first the day length has to be long enough, then the water temperature must be warm enough. When these two factors coincide, bass should be spawning.

The optimum water temperature for largemouth bass to spawn is 65- to 79-degrees. Traditionally, bass are on the beds spawning as early as mid-February in extreme southern regions of Florida and Texas and later as you head north.  It can occur in mid-April across Oklahoma, Arkansas and Tennessee, and as late as mid-June in northern states like Minnesota and Wisconsin.

Anglers know when the actual spawn is getting near by examining the male bass they catch. Males that are fanning a nest (building and keeping a nest clean) will have tails that are raw and even bloodied.

The wild card most anglers throw into the deck is the moon phase. Some swear by the new moon, and others claim bass get on the nest during the full moon. There is evidence that some fish spawns are controlled by the moon phase, with the Grunion run the most-often cited example.

Grunion are small silvery fish found along the coast of southern California, and are unique in that they’re the only fish that deposit their eggs in the sand instead of in the water. They spawn from March through August, but only on three or four nights after the highest tide associated with each full or new moon.

For bass, however, no such evidence of the moon’s influence exists, although you’d be hard-pressed to convince many long-time “moonies” that there’s no correlation. Many spawning studies are conducted in smaller ponds and holding tanks with fairly uniform temperatures – hardly real-world environments that attract anglers. Even Dr. Schramm suggests that there may be a moon-spawn link.

“Temperature in lakes and reservoirs, especially big ones, is far from uniform,” he said. “Since a bass moving around through even a half acre could encounter temperatures that vary by 5 degrees, the moon may have a little effect.”

If a strong moon phase does affect the spawn, bass in a band that covers Oklahoma, Arkansas, Tennessee and North Carolina should spawn April 10 (new moon), April 25 (full moon) and a couple days on both sides of those dates. Working northward, important dates are May 9 (new moon) and May 24 (full moon).

One angler who believes the moon affects the release of eggs in female bass is Zach King, an FLW EverStart angler currently ranked No. 1 in the Central Division. King is on the water approximately 300 days a year. His home water is Arkansas’ Lake Dardanelle, where I had the chance to fish with him Sunday, April 7.

Bass were holding in less that 3 feet of water, and some female bass were already locked on beds. During the afternoon three anglers boated 55 bass with five of those females weighing 4- to 6-pounds.

“The fish are still coming into this shallow water,” he said. “You wouldn’t believe how many fish are compacted on these shallow flats.”

Vast flats pocked with last year’s dead lily pads comprise the prime bedding cover. King eases the boat through the shallow vegetation and fan casts a Texas-rigged, weightless YUM Dinger to locate bass. When fish are active, he holds the rod at the 1 o’clock position and keeps the soft plastic stickbait moving toward the boat with a constant retrieve and twitches of the rod.

“When I see a fish swirl on it or coming to it I stop the retrieve,” he said. “Let it fall and twitch it. Bass can’t stand it when you twitch it in front of them. It’s like it turns toward them, and they just eat it.”

If bass are less active, anglers should slow down the retrieve. Let the bait sink a few seconds before giving it a few twitches, then let it sink again.

Anglers often spook bass off beds before seeing them, but the fish don’t go far and often want to return, so King backs off a bit and holds still, watching for the fish to come back. When it does, he uses the same Dinger rig to pitch beyond the bed, then reel it over and drop it in the middle.

King watches for the fish to approach the bait, and when it does he gives it a slight twitch to pop it off bottom. It may take repeated attempts to get the fish to take the bait, but if it's a big fish he'll invest the time it takes to get it in the boat.

King says he’s seen a change in the way bass are bedding on Dardanelle. He believes bass are reacting to anglers by making their nests less conspicuous.

“The nests aren’t as clean as they used to be,” he said, “and the clean spots are smaller. I think they’re making them more camouflaged because of the fishing pressure.”