What is the Solunar Theory all about and how can it help improve your catch?
Credit for the Solunar Theory goes to John Alden Knight, the author of "Moon Up...Moon Down"
(Solunar Sales 1972), "The Modern Angler: Including the Solunar Theory" (C. Scribner's Sons, ltd.
1936) and "The Theory and Technique of Fresh Water Angling" (Harcourt Brace and Company
New York 1940). In 1926 , he decided to evaluate 33 factors which might influence behavior of
fresh or saltwater fishes that caused them to be periodically more active. Of those, three seemed
to merit further examination: sunrise/sunset, phase of the moon and tides. From that effort, this
avid fly fisherman created the Solunar Theory (Sol = sun ,and Lunar = moon).
Tides had long been known as an important factor in saltwater fishing success and the connection
with moon phase was well understood. Knight then supposed that the relationship of the sun and
moon, rather than actual tidal stages might be the determining factor. As his research continued,
he determined that in addition to the time of moon up - moon down there were intermediate
periods of fishing activity that occurred midway between the two major periods. So he coined the
phrases 'major periods' and 'minor periods' to describe them respectively.
Knight used this information to publish the first Solunar Tables in 1936. These tables are still
widely published and numerous programs, some on digital watches, emulate them. To be accurate
the precise times from each table must consider the geographic location and be adjusted for
Daylight Savings Time, if appropriate.
The periods of greatest animal activity (not only fish are influenced) last from 1.5 to 3 hours
depending on the moon’s relationship to the sun. Minor Solunar periods are indicated during the
rising and setting times of the moon, and major periods are indicated during the two transits.
To substantiate this theory, Knight attempted a systematic inquiry by considering the timing of 200
'record' catches, more than 90 percent were made during a new moon (when no moon is visible).
This is the time when solunar periods appear strongest, and they were made during the actual
times of the solunar periods.
Because of the interaction between the many lunar and solar cycles, no two days, months or years
are identical. June has a greater combined solunar influence than any other month. During a full
moon, the sun and moon are nearly opposite each other and given the length of the day, one or
the other is nearly always above the horizon. During a new moon, both bodies are in near-perfect
rhythm traveling the skies together with their forces combined.
Please keep these facts in mind as we explore the effects of the moon: The moon and the sun
have been timing instruments used by the earth's creatures since the beginning of time.
It is only in the last few hundred years that man has used a clock, and man is the only creature
that has a clock.
All other creatures still keep time by observing the sun and the moon. There are two mechanisms
that creatures use to keep track of the sun and the moon.
The first, and by far the least obvious, is sight. Animals see the sun and the moon and react
accordingly. The second, and far less obvious, is gravity.
The moon has 1/6th the gravitation pull of the earth and it is close enough to our planet to have
major gravitational influences. In some ocean bays the tide can vary as much as 50 feet!
The sun has 2 million times the gravitational pull of the moon, but the sun is so far away that it
exerts only about 1/3rd as much gravitational pull on our planet as the moon.
Tides are caused by changes in local gravity due to the positions of the moon and sun, primarily
High tide occurs when the moon is directly overhead, and low tide occurs 6 hours and 12 minutes
before and after high tide (when the moon is on either horizon). Ocean creatures have been
timing their activities on gravity and the tides for millions of years. And bass evolved from ocean
There is much circumstantial evidence that suggests bass have retained their gravity/tide reading
ability. This is in spite of the fact that most black bass live in waters that are not influenced by tides.
Doug Hannon,known in bass circles as The Bass Professor. For 25 years Doug has been using
scientific principles to study black bass. He studies them by fishing for them and keeping detailed
records of each fishing trip. He studies them by keeping bass in large aquariums and
experimenting with them in a controlled environment.
And he spends hour after hour scuba diving so that he can observe bass in their natural habitat.
Again, Doug fishes for bass almost every day and he keeps meticulous records.
One of Doug's research topics is the effect of moon position on the bass bite. In one study, he
plotted his fishing success over a 10-year period against the moon's position.
Here is what he found. If he assigns a score of 1.0 to his fishing success on all days fished over
the entire 10 years, then his success factor when the moon was either overhead or underfoot
would score a whopping 2.5. Fishing was 2.5 times better than average when the moon was
overhead or underfoot.
When the moon was on either the eastern or western horizon, the bite was better than average by
a score of 1.5 to one.
Now, note this well: When the moon was more than an hour and a half away from one of these four
positions, the average score was 0.5 to one. In other words, Doug was five times more likely to
catch bass when the moon was in its most favorable position as opposed to the moon's least
Doug attributes this to feeding habits that have developed over eons of time. Just as people feed
early in the morning, at noon, in the evening, and they snack at other times, Doug believes that
bass feed when the moon is overhead, underfoot, and they are apt to snack when the moon is on
either horizon. The rest of the time they are not actively feeding.
The Phase of the Moon
When Doug started plotting his data he thought that the days around the full moon period were
the worse days to fish. This is a widely held view that Doug had picked up from fishermen.
Therefore, he was quite surprised when his data showed otherwise. The bass bite best during a
seven-day period that has the new moon as the fourth day.
Next, they bite best during a week that has the full moon on the fourth day.
The bass do not bite as well during the other two weeks of the moon's 29-day cycle. He also notes
that the most effect of the moon's phase is in late spring and summer.
From late fall until the spawn the following year, bass tend to feed in the middle of the day
regardless of moon cycle or position.
When the sun is low on the horizon, the bass are influenced more by the amount of light than by
moon phase. From spawn until fall this condition reverses itself, and they feed heavily on the dark
of the moon and on the full moon.
There is an important point that has been left unsaid.
There is never a time when an experienced fisherman cannot catch a fish.
No matter where the moon is, and no matter what the weather conditions are, an effective lure
presentation with in a foot of a bass's nose will cause that bass to bite nine times out of ten.
On the other hand, where the bass will be, and how active they will be, is strongly effected by the
weather, the previous weather, and by the moon.
Tides and Their Causes
NOAA, US Dept of Commerce
The tides are a natural phenomenon involving the alternating rise and fall in the large fluid bodies
of the earth caused by the combined gravitational attraction of the sun and moon.
The combination of these two variable force influences produce the complex recurrent cycle of the
tides. Tides may occur in both oceans and seas, to a limited extent in large lakes, the atmosphere,
and, to a very minute degree, in the earth itself. The period between succeeding tides varies as
the result of many factors and force influences.
The tide-generating force represents the difference between (1) the centrifugal force produced by
the revolution of the earth around the common center-of-gravity of the earth-moon system and (2)
the gravitational attraction of the moon acting upon the earth's overlying waters. Since, on the
average, the moon is only 238,852 miles from the earth compared with the sun's greater distance
of 92,956,000 miles, this closer distance outranks the much smaller mass of the moon compared
to the sun, and the moon;s tide raising force is, accordingly, 2 1/2 times that of the sun.
The effect of the tide-generating forces of the moon and sun acting tangentially to the earth's
surface (the so-called "tractive force") tends to cause a maximum accumulation of the waters of
the oceans at two diametrically opposite positions on the surface of the earth and to withdraw
compensating amounts of water from all points 90 degrees removed from the positions of these
tidal bulges. As the earth rotates beneath the maxima and minima of these tide-generating forces,
a sequence of two high tides, separated by two low tides, ideally is produced each day.
Twice in each lunar month, when the sun, moon, and earth are directly aligned, with the moon
between the earth and sun (at new moon) or on the opposite of the earth from the sun (at full
moon), the sun and the moon exert their gravitational force in a mutual or additive fashion. Higher
high tides and lower low tides are produced. These are called spring tides .
At two positions 90 degrees in between, the gravitational forces of the moon and sun - imposed at
right angles - then to counteract each other to the greatest extent, and the range between high
and low tides is reduced. These are called neap tides.This semi-monthly variation between the
spring and neap tides is called the phase inequality.
The inclination of the moon's orbit to the equator also produces a difference in the height of
succeeding high tides and in the depression of succeeding low tides which is known as the diurnal
inequality. In extreme cases this phenomenon can result in only one high tide and one low tide
The actual range of tide in the waters of the open ocean may amount to only one or two feet,
However, as this tide approaches shoal waters and its effects are augmented the tidal range may
be greatly increased. In Nova Scotia along the narrow channel of the Bay of Fundy, the range of
tides may reach 43 feet or more (under spring tide conditions) due to resonant amplification.
In every case, actual high or low tide can vary considerably from the average due to weather
conditions such as strong winds, abrupt barometric pressure changes, or prolonged periods of
extreme high or low pressure.
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