Fish the Moon:
Day or Night

From sneaky snook to behemoth broadbills, understanding lunar cycles helps focus in on key feeding periods when anglers are most likely to succeed!

Capt. Mike Genoun September 22, 2009

Since the very beginning, we’ve gazed to the sky in wonderment – transfixed by the most brilliant celestial body apparent from the earth’s surface – the moon. As centuries passed, inquisitive minds began to understand a direct correlation between various oceanic events and different moon phases. Today, man knows a great deal more about lunar cycles and their effect on nature – but the fascination remains. Fortunately for us, saltwater fishermen can use some basic knowledge about moon phases to stack the odds in their favor.

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Snook are especially aware of moon phases and tidal conditions as they prepare to ambush outgoing prey. Photo: Steve Dougherty

Because of its proximity, we know that the moon has a dramatic effect on the earth due in part to the gravitational force that it places on our oceans. This gravitational force causes the oceans of the world to move resulting in what we refer to as tides.

Many captains in Florida are students of lunar cycles and have studied how they influence fish behavior – not only feeding patterns but fish movements and spawning cycles as well.

For a clearer understanding, imagine the earth completely covered by water. As the earth rotates, this water is balanced evenly on all sides by centrifugal force. The moon’s gravitational pull on this layer of water as it orbits the earth causes the water to literally bulge toward the moon. Because the earth is spinning, there is always a bulge on the opposite side of the globe as well. The resulting areas of high water levels are high tides and the areas of low water levels are low tides.

Now consider that since the earth and the moon constantly rotate around the sun, there is an added factor. When the sun and moon are aligned, they create exceptionally strong gravitational forces causing very high and very low tides, which are called spring tides (no relation to the season). Spring tides occur twice per month. In the Bay of Fundy Nova Scotia, spring tides can reach an astonishing 70-feet!

When the sun and moon are not aligned, the gravitational forces cancel each other out and the tides are nowhere near as dramatic. These are called neap tides, and are generally regarded as the worst time to fish.

Tides vary from day to day because as the earth, moon and sun orbit, their positions constantly shift, causing slightly different gravitational effects. This causes the tides to occur at slightly different times with each passing day. Tides also vary from place to place with geographical landmasses playing a role as well. An excellent example would be the Gulf of Mexico where there is only one high tide and one low tide each day.

We know that the moon revolves around the earth in about four weeks. The first phase of the moon at the beginning of a new revolution is called a new moon – when the moon is in the shadow of the earth causing it to reflect no light and appear dark. A week later the moon moves into its first quarter, meaning that one-quarter of the moon’s total surface is reflecting light. We only see 50-percent of the moon’s surface at any given time so when the moon is in its first quarter it is sometimes referred to as a half moon. One week after the first quarter, or half moon, the moon will be full and the entire 50-percent of the moon that is visible to us will be reflecting light. One week after the full moon, and again the moon will appear as half since it will be in its last quarter. One week after the last quarter and the moon will have completed an entire lunar cycle and be a new moon again.

As mentioned, the correlation to the alignment of the sun, moon and earth is actually what determines the strength of the tide. So during a new or full moon, the earth, moon and sun are in alignment – gravitational pull is at its strongest and tides are higher and more powerful. The height of the high tide begins to decrease after the full moon, reaching its lowest levels during the last quarter moon. Tides begin to increase from there and reach their peak again at the new moon when the earth rotates between the moon and the sun. These strong tidal periods produce increased water movement and consequently a much better shot at angling success – day or night.

All of us know that a strong tide is a good tide to fish, but what effect does the moon have as it tracks across the sky each night? Remember, just because we can’t see the moon during a cloudy night doesn’t mean it is not influential. The strongest tides occur when the moon is either directly overhead – what’s referred to as moon over – or directly below us – moon under. Since the moon’s orbit takes approximately 24 hours, it will be directly overhead roughly 6 hours after it rises and directly behind us 12 hours later. Study the moon carefully whenever you’re fishing at night. Over time you’ll find that about one hour before moonrise until about one hour after the moon becomes fully visible to be a very productive period. As the moon nears and finally sinks over the western horizon, the same applies.

Many captains in Florida are students of lunar cycles and have studied how they influence fish behavior – not only feeding patterns but fish movements and spawning cycles as well. They firmly believe that understanding how fish adapt to changes in their environment allows anglers to better predict where their quarry is likely to be and when the targeted species will likely be feeding.

Imagine a mouth of an estuary or any inlet during a full moon when the tide is falling. Water is spilling into the ocean at an extremely high velocity. With all this moving water powerful currents sweep the seafloor. Food organisms and juvenile crustaceans that live on or near the bottom become part of this mass exodus of water that is rapidly flushing out to sea. Baitfish feed on these organisms, bigger fish feed on the crustaceans, even larger fish feed on the bigger fish…and you can follow the food chain up from there.

Snook – a favorite inshore game fish – are especially reliant on the tides. Snook will not spawn during any quarter moon – their eggs must be swept far offshore to hatch, then be carried back inshore to estuaries a day or two later as larvae. Egg bearing females wait until a full or new moon to spawn in order to take advantage of the stronger tidal flows. Another example are pompano which become very active along the beaches during major tides. The extra powerful surge flushes sand fleas – pompano’s favorite forage – out of the sand and into the surf where they gather to gorge.

The feeding habits of the ocean’s roaming pelagics also vary depending on the phase of the moon. Highly prized wahoo are notorious for feeding heavily just before and after a full moon when strong outgoing tides flush large volumes of forage off shallow banks and into deeper water. The recent August full moon delighted South Florida anglers with a phenomenal wahoo bite.

Another example of the role the moon plays offshore can be revealed with broadbill swordfish. If you asked ten different swordfishermen, “What’s the best moon phase?,” you’d get ten different answers. The fact is, catch records and scientific data prove swordfish are most active for a few days leading up to the full moon and for a few days after a new moon. Why swordfish concentrate their feeding habits at certain depths on any given night or why the bite is better during different times of the month is almost obvious.

Swordfish are predatory species feeding primarily on squid and mackerel, both of which are nocturnal meaning that during the day they remain deep in the dark depths. As night falls, they rise toward the surface. Moonlight undeniably plays a role in where these forage species concentrate. During a full moon, plenty of ambient light protrudes through the ocean’s surface causing the forage to remain deeper in the water column. Conversely, during a quarter or new moon with little to no moonlight, bait wanders closer to the surface, with broadbills in tow.

There are other variables to take into consideration as well, not just the moon phase. Water temperature, weather patterns, ocean currents, and how you cooked your eggs that morning all play a role in your success. Swordfishermen should always fish baits at various levels in the water column regardless of moon phase just to cover the bases. However, the moon phase is an extremely reliable indicator of what depth swordfish will most likely be feeding in.

If you are not already convinced, moon phases play a leading role in saltwater fishing. Anglers in constant pursuit of success should really know how because it just makes good sense to fish when the fish are most active and therefore most likely to strike.

Other Considerations

Regardless of moon phase, severe weather patterns have an impact on how, where and when fish feed. When a front is approaching or just after one has passed; it’s a good time to fish.

Game fish are more likely to feed with reckless abandon during transitional periods with winter to spring and summer to fall being the two best fishing times.

There’s no substitute for spending time on the water. The more time we spend practicing, the better anglers we become. It’s that simple.

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