Understanding the Tides

Understanding the tides

by: Capt. Greg Francis

TIDES! Tides can create just about as much confusion for saltwater anglers as an isle full of artificial baits at our favorite tackle shop. We like what we see and we want desperately to know everything that might improve our success, but we’re awfully confused and don’t want to make a costly mistakes! maybe the information I’m about to present will help remove some of the confusion.

First of all, what are tides? Tides are the vertical rise and fall of water in the ocean and in our very own bay system. Tides are caused by the interaction of the gravitational forces or our Earth, the Moon, and the Sun. Even though the moon is much smaller than the sun, its about 400 times closer. Therefore, it exerts a larger gravitational force upon the earth and is capable of influencing our tides to a far greater degree.

If measured from Earth, the Moon and Earth combined have about twice the gravitational pull of the Sun. The Sun has its greatest impact upon the tides when the Sun, Earth,, and Moon are all in one line causing an unusually strong gravitational pull that in turn creates a much stronger than normal tide. When this happens, it is called a spring tide, which has nothing to do with the four seasons. Spring tides, sometimes called moon tides occur every two weeks, right in line with the new and full moons. Fishing on these spring tides can be exceptional because of the stronger than normal currents.

Neap tides, which are the opposite of spring tides and not very strong tides at all, are caused when the Sun and Moon form a right angle from the Earth causing their gravitational pulls to be in some degree equalized. The same as spring tides, neap tides also occur every couple of weeks and coincide with the first quarter and third quarter moons. Now, let’s throw in lunar apogee and lunar perigee for a moment.

Lunar apogee is a term that describes the moon in its farthest position from Earth. When this happens, the tides will be lower than normal. Lunar perigees, is the term that describes the Moon in its closest position to Earth. In this situation, the tides will be higher than normal. This is caused by the gravitational pull of the Earth and Moon in tandem. Lunar apogee and lunar perigee are spaced exactly 27 1/2 days apart.

Another factor that can have great impact on our tides is the wind. Let’s think back to last winter when we had those strong north winds. When we had an ebb tide (outgoing) in the face of strong north wind, our bays drained to just about their lowest natural levels making it very difficult to get around unless you operated a true skinny water boat. With the same north wind blowing for several days, it makes it very difficult for a flood tide (incoming) to fill the bay system back up. During the spring and summer, just the opposite happens. The predominant south and southeast winds hold the tides from falling out.

Why should we even be concerned with tides? Well, for one thing, fish like to feed when the water is moving. When the tide starts to rise and fall it starts to move baitfish around causing them to start looking for a safer place to hide. For example, on a high tide, bait fish might be moved up into a small bayou or canal. When the tide starts receding, the bait fish are forced out, drawing them back out to the main body of water. This is where predator fish (Trout, Reds, and Flounder) can and will stack up and ambush these baitfish and shrimp.

Tides pretty much control the bait and their movements. Learning how to locate them or even how to predict where they will be at any given time will greatly enhance your catching! During slack water times (no tidal movement) there is no current to concentrate schools of baitfish or force them out of their hiding places. As a result, the fishing at this period is generally slow.

Tides play a variety of roles. Not only do they induce the movement of baitfish and feeding our game fish, they also provide the critical flushes that our bays frequently require. Tides bring in fresh water and flush out estuaries and other inlets. They also bring rich nutrients to the bays for the plant life and plankton for baitfish to feed upon. There are many different aspects of tides. One could go on and on about many causes and effects or tides and their movements. I hope I was able to shed a little light on the subject without causing any more confusion.


Capt. Greg Francis

Gulf Coast Connections June 2001


Leave a Reply