Tides play an important role in the movement of
fish. Knowledge of tides is especially important
for success with species like this bonefish landed
by Captain Rick Grassett
SUN PHOTO/RUSTY CHINNIS
By Rusty Chinnis
special to the sun
The early morning light played over the bare flats, exposing
sand bars, potholes, channels and grass beds that had
been covered with water an hour before. As my tide chart
had predicted, the water was just beginning to rise as
I anchored the boat and began wading the edge of a channel
that led onto the flat. I worked my way up as the tide
rose, taking snook, trout and ladyfish on almost every
cast. On a different day I would remember these contours
and target the fish as they dropped with the tide into
these same channels and potholes.
Most anglers have a general understanding of tides. They
know that they fluctuate approximately one hour every
day and that there are often four tides a day, two low
tides and two high tides. Anglers are also aware that
there may be only one tide some days and two or three
tides on other days. During full and new moons, we expect
the tidal range to be greater than during the quarters
and half moon phase. Since the moon rises one hour later
every day, it was long suspected that it had an influence
on the tides. In theory, if the ocean uniformly covered
the earth, the moons gravitational force would act
equally, deforming it and creating significant tidal effects.
The moon also affects the earths mass so that the
ocean on opposite sides experiences high tides as the
earth is pulled away from the water. As the moon rotates
around the earth, there are two high tides and two low
tides at any given time.
In reality, the oceans do not cover the earth uniformly
and they vary in depth. There is also significant friction
exerted between the oceans and the earths surface.
Other objects in the solar system influence the tides
as well. Most are negligible, except for the sun, which
has approximately one half the influence of the moon.
All of these combine to make tidal predictions extremely
When the sun and the moon line up at the full and new
moon, their combined influence creates a greater pull,
and we experience strong or spring tide. When the sun
and moon are at right angles to each other, during the
moons first and last quarter, they interfere with
each other and we experience weak or neap tides. In addition,
the tidal ranges are greater when the moon and sun are
at perigee, or closest to the earth.
For anglers, a general understanding of the tides is useful,
but a tide chart is necessary to predict them accurately.
Charts are helpful, but experience alone will teach the
angler how to benefit from the myriad factors that coincide
with the tide to produce good fishing.