The Effects of Solunar Forces on Bass Fishing

I recall one of the largest kerfuffles we ever got into during my 30 years of editing In-Fisherman was the issue, for reason of space limitations or contract problems (I can’t quite recall after all these years), in which we didn’t include our usual “Solunar Moon Times” table in an issue. We soon realized the extent of reader angst, as the first issues hit newsstands and mailboxes.

Distraught readers across the continent were beside themselves over this omission.

We were well aware of the importance of this information to many anglers, and had faithfully published the monthly calendars, that includes solunar majors and minors, as well as moon phases. But we failed to realize the depth of reliance on this information by our readers.

More recently, Curtis Niedermier, Editor In Chief of FLW Bass Fishing magazine, learned this lesson, too. “In our Winter 2019 issue, I cut our version of the chart, called ‘Solunar Tables,’” he wrote recently. “I did it because we had limited space, and I felt we had other content that was more valuable to our readers, and deserved some extra real estate.

“I was wrong. I received a number of phone calls and emails from concerned readers wondering why the Solunar Tables were missing and if they were coming back. Several readers told me they’d stop subscribing if I didn’t bring them back.”

Effects of the moon on fishing is one of those subjects that continually arises when anglers gather to discuss factors for successful fishing. It springs even more to the forefront during spring, when many rely on moon phase and daily tables to plan trips, believing that the spawning peaks of various gamefish, including black bass, are closely linked, or even controlled by the status and position of the moon. On the other hand, other equally knowledgeable anglers scoff at the notion, based on their own experiences and the lack of formal scientific verification of such linkages.

Solunar Theory

From ancient times, hunters and fishermen have placed importance on the moon’s positioning and brightness, as it seemed to influence the activity level and vulnerability of game animals and fish. In the 1920s, John Alden Knight devised the first solunar tables and held a patent on their production and sale until it expired. Dan Barnett’s “Charted Fishing Times” were published in Bassmaster Magazine from 1975 to 1987, replaced by Rick Taylor’s Astro Tables. Today, many solunar calendars are available, differing slightly in the length and estimated power of different majors an minors, sometimes influenced by other competing or complementing forces such as sunrise and sunsets, and time of year.

The late Doug Hannon, known as “The Bass Professor,” became fascinated by the moon’s effects on bass fishing and he charted his fishing success, and also used record-fish information to examine lunar effects and to develop “Hannon’s Solunar Calculator,” which sold widely and was published in In-Fisherman for over 20 years. In-Fisherman continues to publish a more recently devised table in each issue. A link on our website, in-fisherman.com, enables anglers to accurately chart the precise times of majors and minors, based on the zip code and date of the fishing location.

The BassForecast is a sophisticated prediction tool that’s available as an app for iPhone and Android users that combines solunar tables with weather forecasts from AccuWeather 10 days into the future. Designer Mike Mehlmann built in a scale, the BassForecast Rating (BFR), which computes outlooks from 1 (least activity) to 10 (most active). It also includes recommendations on lures, based on these factors. It uses GPS coordinates to define a location, ensuring the most accurate solunar timing. And a Catch Log lets you make notes on catches for future reference.

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According to solunar theory, major activity periods occur when the moon is directly overhead or directly below a reference latitude. Minor periods occur when it’s positioned at 90 degrees to either side. The moon’s orbit is elliptical. At its most distant position (apogee), it’s about 252,000 miles away. At its closest (perigee), it’s 233,000 miles away. Some theorists feel that the moon’s greater gravitational pull (as much as 20 percent stronger) means solunar peaks at this time further increase fishing potential.

Scientific Background

Behind solunar theory is the fact that the combined gravitational forces of the sun and moon create tides, which affect fish behavior. Many estuarine and near-shore species of saltwater fish, including snook and redfish, time their spawns to occur during strong lunar periods, which create higher tidal flows that serve to transport eggs to favorable habitat for incubation, hatching, and growth of larval fish. Tides are absent in inland waters, but could fish retain some primordial reaction to these periods?

Even terrestrial creatures seem to react to lunar activity, particularly full moons, which greatly enhance vision after dark. It’s often reported that police departments and hospitals try for full staffing at these times, believing that more aberent behavior then may bring an extra load of “clients.” For example a scientific analysis of cases of animal bites at a hospital in Bradford, England, found that incidence of animal bites did indeed rise during full-moon periods, at a statistically highly-significant level.

Researchers at Utah State University demonstrated the dramatic differences in the location and depth selection of Bonneville ciscoes, a deepwater relative of the whitefish, during full and new moons, which they attributed to differences in nighttime light levels.

Some scientists have theorized that fish may use the lunar periods as a “zeitgeber,” an animal behavior term to describe events that resynchronize the biological clocks of organisms to aid them in activities, including spawning, feeding, and migrating. A study done at the University of Guelph in Canada on young coho salmon showed that fish in a controlled lab environment could detect solunar forces and use them to regulate behavior. It’s thought that external stimuli like the sun and moon help synchronize the internal biological clocks that many species possess. A famous study on mollusks at Northwestern University involved moving the creatures from the East Coast to a lab in Chicago. For two weeks, they continued to open and close their shells in synchrony with tidal forces along the Atlantic Ocean. But they then resynchronized their biological clocks to a theoretical tidal cycle that would have occurred in the Midwest had it been submerged. Clearly these creatures sensed and reacted to the moon’s position. But how might such forces affect the willingness of bass to bite?

Manns on the Moon

Ralph Manns, a fishery scientist, avid bass angler, and longtime contributor to In-Fisherman on bass fishing and scientific topics, wrote a two-part series for ­In‑Fisherman in 1992 that was the most thorough analysis of this subject. In that report, he evaluated results from bass fishing trips he conducted from 1985 to 1991 and statistically analyzed data on catch rates to evaluate solunar effects. Catches included 2,360 bass over 12 inches, including 96 fish over 5 pounds caught primarily in central Texas.

Manns wrote, “The most noticeable peaks occurred on the major hour and one hour after the minor. Two distinct periods of poor fishing were evident: the hours between majors and minors, and the hour after majors.” He found these results statistically significant.

At the end of the series, he wrote, ”Solunar theorists were correct when they reported a detectable solunar force that affects fish behavior and angling catch rates. They have become so enraptured by these effects, however, that they’ve become overconfident in predicting the best times to fish. Solunar force is just one of many factors that influence fish behavior. Anglers should consult solunar tables to identify times that may provide better fishing. And I recommend trying to be on the water around minors as well as major periods.”

Over the next two decades, Manns continued to chart fishing results in relation to solunar periods, and reported further in a 2013 feature. This latter data set included 8,900 bass caught during 2,500 trips lasting 10,466 hours and including some night-fishing, primarily on Texas reservoirs and ponds. He reported that catch rates were highest on ponds, and that the best catches typically occurred within two hours of major and minor periods, at a high statistical level.

Bass in larger impoundments seemed less linked to moon effects. “As I reported in my earlier analysis, bass over 5 pounds were not as influenced by moon position as smaller bass,” Manns noted. “Nighttime catch rates peaked around majors, but were at their lowest around minors, though these relationships were not statistically significant. I suspect the night bite is more influenced by brightness than moon positioning. Research has shown that bass night feeding is far more efficient when ambient light is maximized. When a full moon corresponds with a major solunar period, plan to be on the water.”

Manns also examined catch rates for dawn and dusk and found dusk the prime time. “Our overall catch rate was 0.85 bass per hour,” he says. “At dusk, it was almost twice as high, 1.62 per hour, and 1.14 per hour around dawn. While solunar periods can affect fishing success, other forces such as light conditions and weather often overwhelm effects of moon position as postulated by solunar theory.”

Though age has limited his fishing time and range of locations, he continues to make observations. His latest notes: When shad are present, the solar tables are irrelevant. Bass feeding periods are tied to where and when shad show up, and shad don’t seem to be affected much by moon position. In our local reservoir where I most often fish, the shad populations have been down for several years. These bass have been feeding more based on solunar cycles than when shad were abundant. And when shad schools have appeared in late June, feeling revolves around them.

“Without shad, these bass turn to sunfish as predominant prey and I’ve always noted that sunfish activity seems more linked to lunar forces. Lunar effects may be more pronounced on insect larvae and other invertebrates, which sunfish feed on, hence their feeding may also seem linked to these effects. I continue to see the strength of the evening twilight bite. Most bass anglers go home way too early. And tournaments are scheduled to end way too soon for the best bite.”

Manns on Catch Rates 

While anglers tend to recall fast bites best, creel survey and tournament data demonstrate that average bass catch rates are around 0.25 bass per hour. In top-notch southeastern waters, average catch rates of 0.40 bass per hour may be recorded. In recent decades, innovative harvest regulations have boosted overall catch rates in many waters.

Our catch rates were relatively high. Yet the difference between peak catch rate and average catch rate (0.10 bass per hour) might be overlooked by most anglers, as it would amount to one additional fish in a 10-hour fishing day. The difference between the slowest hours and the peak amounted to about 2 bass in a 10-hour day.

Although such a difference might be missed by casual anglers, it might mean the difference between winning a tournament or finishing 10th, since ounces often make a substantial difference in the standings. Moreover, top anglers go to great lengths to maximize the minutes they fish, driving fast boats, casting with maximum efficiency, and so on.

Even on the good waters we fished, we caught no bass during about half the hours, and caught one bass in about 30 percent of hours. 

Moon Phases and Fishing

Lunar followers often check moon phases as well as timing of minors and majors. Richie White is a veteran guide on Texas’ famed Lake Fork and has harbored a fascination with the relationship of the moon to bass fishing. “I examined catch dates and moon phase of Texas’ 50 biggest bass and found that almost half of them were caught with at least 75 percent illumination,” he says, “meaning rather close to a full moon. Only one quarter of all days offer this much illumination, meaning about half the giants were caught in one-fourth of potential fishing times. I did a similar comparison with my own top-50 bass and found similar results; 21 of them were caught with at least 75-percent illumination.

“Around spawn time, you hear a lot of anglers talking about the full moon bringing in a new wave of fish to bedding areas. I have seen this occur, and seen it fail to occur as well. You can’t deny that a lot of big bass are caught around the full moon in spring. But there’s some bias there, as anglers plan trips around full moons, increasing the likelihood of lunkers being caught.

“Observant anglers note that the moon rises in the east and sets in the west approximately 30 minutes to an hour later each day. Of course, it’s the earth that’s turning each day, not the moon, but that’s how it appears to us. During full moons, the moon rises at about the time the sun sets and sets about when the moon rises, which is believed to be a promising time to fish since the times tend to be productive even without additional lunar influence. Conversely, on the night of the new (dark) moon, it rises at daybreak and sets at sundown. About a week after a new moon, you see a half moon, which appears in the middle of the day and its into middle of the night. In another week or so, it will be full. During half-moon times, the morning and evening have the most lunar influence and I have indeed found these to be excellent fishing times over the years.”

The timing of hot bites is one of the most confounding aspects of bass fishing, as tremendous action often occurs during adverse conditions, and prime-appearing days frequently don’t produce as we’d hope. This adds to the mystery of fishing and the difficulty in trying to “master” it.

Bass rely on internal and external forces we don’t fully understand that lead them to feed, spawn, and undertake other behaviors. At times, lunar forces seem to play a role in the process, along with wind, water temperature, weather, barometric pressure, light level, water clarity, and more. While we’ve taken huge steps in locating bass, thanks to advanced sonar and GPS technology, their willingness to bite remains something of a mystery.

*In-Fisherman Field Editor Steve Quinn is a leading expert on black bass fishing, often tapping his fishery science background to connect biology and fishing.