Understanding Moon Phases

From ancient times, hunters and fishermen have noted that the moon's position and brightness seemed to influence success. In the 1920s, John Alden Knight devised the first solunar tables and held a monopoly on moon times until his patent ran out. Today many solunar references are available, but none as popular or as fine-tuned as the In-Fisherman Solunar Calendar. It can calculate the precise moon position according to the zip code of the waterway you plan to fish.

Many top anglers place great faith in solunar theory, planning to be on prime spots during major and minor periods. For example, veteran Oklahoma pro Tommy Biffle has consulted tables in planning fishing tournament strategies. He now uses the FishMate app on his iPhone as a source of major and minor feeding times wherever the Bassmaster Elite Series takes him.

"If I have a group of bass pinpointed, I make sure to fish that spot during a major period," Biffle says, adding that this strategy has boosted his earnings at many events.

Power Periods

Major periods occur when the moon is directly overhead or directly below a reference latitude. Minors occur when it's positioned 90 degrees to either side. The movements of the earth and moon mean that majors and minors occur slightly more than six hours apart. When days and nights are about equal in length, around spring and fall equinoxes in March and September, a major at dawn places a minor at noon, and another major around dusk, likely making this a prime day to be on the water. In winter, a noon major is surrounded by minors before dawn and after dark, likely not prime times to fish.

The moon's orbit around the earth is not round, but elliptical. At the most distant point (apogee), it's about 252,000 miles away. At its closest position (perigee), the moon is about 233,000 miles distant. Some theorists feel that the moon's greater gravitational pull (as much as 20 percent stronger during perigee positions) means solunar peaks at this time create even better fishing potential. When the moon's closest, it's also sometimes called a "super moon," due to its additional influence on tides.

When Bass Bite Best

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Scientists don't know how bass might detect moon position. Some theorists feel that invertebrate movements are related to solunar productivity and that these tiny creatures move and become more vulnerable depending on moon phase, leading to increased activity by species that feed on them. Their activity might, in turn, encourage feeding by walleyes, bass, pike, muskie, and other predators.

Fishery scientist and long-time In-Fisherman contributor Ralph Manns of Rockwall, TX, undertook a massive project to test the effects of solunar periods on catches of bass. His database included 2,500 fishing trips lasting 10,466 hours. During that time, he and his fishing companions caught 8,900 bass that were 12 inches or longer. He also kept track of bass over 5 pounds or 21 inches for separate analysis, since some observers feel that larger bass may be more influenced by moon effects than small and perhaps less discerning fish. Included in his catch were 371 5-pounders and 40 bass from 8 to 10.8 pounds. He charted catches over the 12 hours of the lunar cycle.

He found that catch rates were significantly higher on the Major +1 (the hour following the midpoint of solunar majors); the following hour (Major +2); the Minor hour; and the following hour (Minor +1). He ran statistical tests on these results and found that they were highly significant, meaning that the chances that these results were random were slight.

Their overall catch rate of bass was 0.85 per hour. The highest catch rate (0.95 bass per hour) occurred on the solunar Minor, with the second fastest catch in the hour following. These results suggest that minor periods may actually exert greater effect on bass feeding than major periods and should be considered great times to catch fish. Catch rates in the two hours following majors also were high, the only other hours of the day with rates over 0.90 bass per hour.

The lowest catch rates occurred in the hours just before majors and minors, suggesting that bass may postpone feeding until lunar conditions peak. It also shows that anglers should fish hard in key locations during majors and minors and to continue for up to two hours after their passage.

When he compared catches of 5-pounders to smaller bass, Manns found that large bass were less influenced by moon position than small ones, although the two hours with the highest catch rates for big fish occurred within an hour of majors and two hours after minors. But because catches of big bass were relatively few, results had less statistical influence and could not be verified as statistically significant. The data set was too small to compensate for daily or weather-related variability in hourly catch rates of big bass.

Manns also teased out seasonal effects from the catch data, and found the least lunar effects in winter and around spawning time. Note: he did not evaluate any effects of moon phase in this analysis, as they represent a different sort of influence. Some anglers feel that full and new moons spur peaks in spawning activity, especially for sunfish and bass.

By May, catch rates in Texas began to follow predictions of solunar theory more closely, with distinct peaks at Major +1 and Major +2. Through summer, catches peaked in the hours around majors and minors.

Manns also noted that any strong bite, whether due to solunar forces, light, or weather conditions, typically is followed by a period of slow fishing that may last up to 12 hours. This likely results from a larger-than-normal proportion of the population turning relatively inactive while digesting food eaten during the hot bite. The lunar influence on bass fishing also seemed more potent in waters where the food web is based on invertebrates and sunfish, rather than on shad. Plankton and invertebrates seem most influenced by lunar forces, and their movements may trigger stronger bites as panfish and bass become more active. But other forces, such as light conditions (dawn, dusk, and overcast skies) and other weather activity often overwhelm effects of moon position as postulated by solunar theory.

Best Times To Fish

If you can choose fishing times, go in the late afternoon or evening, shortly before the start of a major or minor period. Focus on prime areas and note changes in fish activity. As predators become more active, faster, more aggressive presentations typically work better than those that tempt bites from inactive fish.

Even in the strongest lunar periods, differences in catch rate may mean just a couple extra bass in a long day. Top professional anglers, however, go to great lengths to maximize the minutes they fish, as it ups their chances for a catch. They drive fast boats, cast with maximum efficiency, tie knots quickly, and more. That extra boost can put a big bass in the boat or mean an extra pound or two at a weigh-in. To maximize your efficiency, add solunar calendar to other factors you consider when planning a trip.