Moon Magic Largemouth Bass
January 19, 2012
Abundance, position, and vulnerability of prey are important factors in the eagerness of bass and other predators to attack. With the exception of the spawn, bass strike to obtain food. My observations and diet analyses show that adult bass feed only when hunting conditions are favorable, remaining inactive when opportunities are poor in order to save energy. This behavior apparently has evolved to promote survival.
Even in summer when food is abundant, more than half of adult largemouth bass sampled often have empty stomachs, even more during winter. They bite if opportunity knocks, but preyfish use survival skills to avoid capture.
Bass tend to feed in low-light conditions — dawn, dusk, and when clouds and wind reduce underwater visibility. These are unquestionably prime times to catch bass, outgunning lunar effects. But from ancient times, hunters and fishers have noted 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 until his patent ran out. Today, many solunar calendars are available, differing slightly in length and estimated potency of minors and majors, as well as inclusion of other factors. For 20 years, I've relied on versions of Casio's Fish in Time or Pathfinder watches, which are programmed to show these periods.
Many anglers, from weekend warriors to touring pros, 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 tournament strategies. He now uses the FishMate app on his iPhone as a source of major and minor feeding times, wherever the BASS Elite Series takes him. "If I have a group of bass pinpointed, I make sure to fish that spot during a major period," he says, noting that this strategy has boosted his earnings at many events. Other anglers don't place much value in this concept, focusing instead on weather, shade, or barometric effects in planning strategies.
The Data Set
My new data set includes all adult bass I and my fishing partners hooked from 1992 through the middle of 2010. We fished a total of 2,500 outings, lasting 10,466 hours. During that time, we logged 8,900 bass of 12 inches or longer, including bass that escaped when close enough to be identified, as the timing of bites was of utmost interest. This total was more than three times larger than in my 1992 analysis. To increase accuracy, I used the Multiyear Interactive Computer Almanac (MICA) provided by the U.S. Naval Observatory to define major and minor periods, as it lists precise lunar transit times.
I separated catches of individual anglers in describing catch rates. I also kept track of bass over 5 pounds or 21 inches for separate analysis, as some theorists have maintained that larger bass may be more influenced by moon effects than small and perhaps less discerning fish. We tallied 371 bass of five pounds or more, including 40 from 8 to 10.8 pounds. I also noted water temperature, wind speed and direction, and sky conditions.
Our efforts included reservoirs and power-plant impoundments as well as ponds. While nearly all effort was in Texas, we also fished in Louisiana and New Mexico. We fished famed Lake Fork frequently from 1998 to 2007, but from 2000 to 2005, the lake suffered the effects of Largemouth Bass Virus, and fishing was far slower than before the disease outbreak or at present.
When Bass Bite Best
Figure 1 depicts catch rates over the 12 hours of the lunar cycle. Catch rates were significantly higher on Major +1 (the hour following the midpoint of solunar majors); the following hour (Major +2); the Minor hour; and the following hour (Minor +1). The statistical tests I ran found differences among periods to be highly significant when data were combined for anglers and lakes.
Average catch rate was 0.85 bass per hour. Our highest catch rate (0.95 bass per hour) occurred on the solunar minor, with the second fastest catch in the hour following. These results support what I'd come to suspect from my earlier analysis, that minor periods may actually exert greater effect on bass feeding than major periods, and should at least be weighted equally. The data also suggest minor periods should be lengthened.
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, in the range of 0.74 to 0.78 bass per hour, occurred in the hours just before majors and minors. It seems that bass activity may peak within a couple hours of major and minor peaks, not always directly on them. It would pay to fish hard through these periods and continue for up to two hours afterwards.
As I'd found in my earlier analysis, bass over 5 pounds were not as influenced by moon position. Figure 2 shows that the two hours with highest catch rates for lunkers occurred within an hour of majors and two hours after minors. Another peak occurred midway between majors and minors. But because such catches are relatively rare, and thus catch rates were low (maximum of 0.045 lunkers per hour), these differences in catches among periods were not statistically significant. The data set was too small to compensate for daily or weather-related variability in hourly catch rates of big bass.
Type of Waterbody
Catch rates varied among waterbody type. Figure 3 shows that ponds produced the fastest fishing, always above 1 bass per hour, and peak times were within two hours of majors and minors, demonstrating a highly significant positive relationship between lunar periods and catch rates. Power plant lakes, primarily Fayette County and Bastrop, ranked second, with catch rates about half as fast. Large reservoirs such as Fork, Ray Hubbard, and Austin area impoundments produced the slowest fishing, peaking at just over 0.60 bass per hour, with lows of 0.53 per hour. Results for power-plant lakes and reservoirs did not show statistically significant relationships to solunar periods. Reservoirs produced higher catch rates of 5-pound and larger bass, while ponds were least productive for big fish.
I have no explanation for differences among water bodies, concerning lunar influence on catch. Some theorists feel that invertebrate movements are related to solunar productivity, that these tiny creatures move and become more vulnerable during periods of higher lunar influence, leading to increased activity by species that feed on them, such as bluegills. Their activity might, in turn, encourage feeding by bass. In reservoirs, food chains are primarily based on planktonic algae, shad, and bass. Plankton shift vertically in response to the sun's position, and shad move with them, keying bass feeding at times of greater vulnerability. This relationship might reduce the importance of lunar effects in shad-based systems, but that's speculation only.
Majors and Minors
According to solunar theorists, major periods occur when the moon is directly overhead or directly below a reference longitude. Minors occur when it's positioned at 90 degrees to either side.
The moon's orbit is not round, but elliptical. At the most distant point (apogee), the moon is about 252,000 miles away. At its closest position (perigee), it's about 233,000 miles distant. Some theorists feel that the moon's greater gravitational pull (as much as 20 percent stronger) means solunar peaks at this time create even better fishing potential.
Timing of Majors and Minors
Moon and earth movements mean 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 a prime day to be on the water.
In summer, lunar intervals are shorter than daylight intervals, so a major at noon is preceded by a minor well after dawn, and followed by a minor well before twilight. In winter, a noon major is surrounded by minors before dawn and after dark.
When a major fell within an hour of sunrise (Figure 6), our catch was only average, followed by subaverage catches until the minor around noon. The bite then steadily improved up until the twilight major.
When majors were around noon, catches then were near average, and continued that way through the afternoon. The bite improved dramatically on the following minor in late afternoon, however, and remained strong through sunset, dropping off at dark. Night catches were well below average. Statistical tests showed these hourly differences to be highly significant.
When majors fell at dusk (Figure 7), the evening bite was excellent, a pattern that was suggested in my 1992 results as well. Statistically, this bite should not be missed. In several of these scenarios, a fast bite typically is followed by a period of poor fishing.
When majors coincided with midnight (Figure 8), distinct catch peaks occurred on minors and three hours after the major, but statistical tests failed to show significance, due to insufficient data.
When minors occurred around noon, the bite was average, but fishing heated up, starting with the following major and continuing through evening twilight, followed by a drop after dark. Finally, when minors were around sunset (Figure 9), the bite was strong for the hours surrounding it and the night bite afterward remained above average.
I also examined differences among seasons. Like most anglers, we fished less between November and March. But from March to November, we fished about the same amount of hours per month. When I separated catch data for winter, prespawn, and spawning months from the May to November data, I found that winter and spring catches showed little lunar influence. But from May through November, hourly catches were linked to solunar periods in a highly significant fashion, based on statistical analyses. This result led me to postulate that lunar influences may act upon fish via the invertebrate segment of the food chain. Lunar influence proved weaker in coldwater months when feeding activity is reduced.
Around the spawn, lunar forces showed no effects. We were as likely to catch a spawning or guarding bass in the weakest lunar hours as in the strongest. Note that we did not investigate effects of moon phase.
The catch rate of adult bass as well as lunkers peaked in April, around the spawn, as shown in Figure 4. The catch stabilized through summer and early fall, with the catch of smaller bass increasing slightly as young fish grew into the adult size-class by October. Catches of large bass remained low but stable into winter, following the spring bonanza.
By May, catch rates began to follow the predictions of solunar theory more closely, with distinct peaks at Major +1 and Minor. In June, catches peaked at Major +1, Major +2, and the following hours. Through summer, catches peaked in the hours around major and minors. Though catches declined in November, peaks occurred on Minor +1 and on the Minor, and in December, peaks occurred before and after minors.
With this large data set, I also examined other factors and compared catches among various environmental conditions:
Night Fishing: We made 702 trips after dark and averaged 0.52 bass per hour, considerably less than our daylight average of 0.87. Night-time catch rates peaked around majors, but were at their lowest around minors (Figure 5), but the relationship was not statistically significant at a high level. I suspect that the night bite is more influenced by relative brightness, via moonlight, than moon positioning. Studies have shown that bass feeding is more effective at night when ambient light is greatest. But if a full moon corresponds with a major period, plan to be on the water.
Dawn and Dusk: To cipher the importance of two key times — dawn and dusk — I separately analyzed those data. I considered dawn the 30 minutes prior to sunrise to an hour after sunrise; dusk was the hour before sunset until 30 minutes after it. While sample size was too small for statistical verification, the evening bite was considerably faster, 1.62 bass per hour, compared to 1.14 per hour at dawn.
Weather: Cloud conditions influenced catch rate, with lower catches during clear skies, and better than average fishing in partly cloudy conditions. Surprisingly, overcast conditions yielded only average catches. The fastest bite occurred in the rain.
Wind direction didn't much affect fishing success, though breezes from the south or southeast, or north or northeast accompanied slightly better results. Wind speed was more important, with average catch per trip rising from 2.85 in calm conditions (0-3 mph) to 3.60 per trip in light wind (4-8 mph), to 3.71 in medium wind (8-15 mph), and to 3.77 per trip in strong winds.
The bite was slowest in cold water (49°F to 58°F) at 1.87 bass per outing. Between 59°F and 68°F we caught 3.66 per outing, but the best range was 69°F to 78°F (4.66 bass), conditions that foster generally shallow bites in late spring and early fall in the Southeast. Success declined on warm water (79°F to 88°F) to 3.2 fish, but was a bit higher at 3.77 per outing in the hottest conditions.
In general, we had higher catch rates when fishing for longer periods, perhaps because time on the water led us to spots where bass were concentrated, or we had time to fine-tune presentation. I've also noticed 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 a hot bite.
In the absence of other factors that encourage feeding — low-light conditions, wind, or approaching fronts — bass may become active on solunar peaks as a zeitbeger response, one that synchronizes the biological clocks of organisms to aid them in predicting when to start and stop behaviors.
The lunar influence on bass fishing seems to be more potent in waters where the food web is based on invertebrates and sunfish, rather than 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 and weather, often overwhelm effects of moon position as postulated by solunar theory.
If you can choose fishing times, go in the evening around a major or minor. Focus on prime areas and note changes in bass activity. As bass 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 an extra bass or two in a long day. But that boost can put a big bass in the boat or add extra pounds at weigh-in. To maximize efficiency, add lunar charts to the other factors top anglers consider in planning trips.
*Ralph Manns, Rockwall, Texas, is a fishery biologist and a long-time In-Fisherman contributor.
In-Fisherman: In 1992, In-Fisherman published a 2-part feature by fishery scientist and long-time contributor Ralph Manns, describing how lunar position affects bass fishing, the most in-depth analysis of the subject to date. This topic has fascinated anglers for ages, and readers and website viewers pay close attention to the "Best Fishing Times" chart published in each issue and on in-fisherman.com, as well as on In-Fisherman's Facebook page. Manns demonstrated that catches tended to follow predictions of solunar theory — that, all other factors being equal — more bass would be caught during major periods, when the moon is positioned directly overhead or directly below a given longitude; or during minor periods, when the moon is positioned at 90 degrees from a latitude. Majors typically last two hours, according to most charts, while minors are shorter. Although Manns' initial analysis showed some positive relationships between good catches and solunar periods, and found minors as influential as majors, results were not statistically significant at a stringent scientific level. Knowing that many factors cause bass to bite, and likely have more influence than solunar periodicity, Manns felt a larger sample of bass catches might increase the power of his assessment. This, the final chapter in his lunar evaluation has, for the first time, demonstrated a statistically significant link between moon position and bass catch rates.