Lunar and tidal influences

The fish were right at Alan’s feet Gary Brown

Diagram 1 © Gary Brown

Lunar Cycle

The lunar cycle has nine phases in it (ref to diagram 1), and all of these phases have an effect on the tides which in turn play an important part in the day to day life of the angler and the fish species that they are targeting. You have the New moon, Full moon, First quarter, Last Quarter, Waning and Waxing Crescent and the Waning and Waxing Gibbous.

Diagram 2 © Gary Brown

Ocean Currents

Australia’s fish species are influenced by currents, wind drifts and eddies. If you take a look at the map of Australia (ref to Diagram 2) that has the schematic view of ocean currents that are found around Australia you may start to realize why there can be an overlapping of fish species that are found in Australia. Australia is affected by the South Equatorial current that is found in the top northwest part of Australia, which in turn joins up with the Leeuwin current that is found off the west coast of WA and part of South Australia. From there the coast of Australia is influenced by the Flinders current and the West Wind Drift. While the east coast of Victoria, NSW and Queensland has the East Coast eddies and the East Australian Current.

Effects on the Tides

Tides are periodic short-term changes in the height of the surface at a particular place caused by a combination of the gravitational force of the moon, sun and the motion of the earth.

The ocean responds simultaneously to inertia and to the gravitational forces of both the sun and the moon. If earth, moon and sun are all in a line, the lunar and solar tides (spring tides) will go to their extreme. This will result in higher high tides and lower low tides. But if the earth, moon and sun form a right angle (neap tides), the solar tide will tend to diminish the lunar tide.

Now if you have ever looked at a tide chart and wondered why there is a slight difference between the tides on one day to the next. It is because the lunar day (24 hours 53 minutes) is longer than the 24 hour clock that we base our day on. Therefore the highest tide will arrive 53 minutes later each day.

Alan Perry with a luderick that was caught while fishing the wash behind him. This was at the top of the tide. © Gary Brown

Tidal Patterns

You will find that in most populated parts of Australia there will be a tide change approximately every 53 minutes. How great the difference between the low and high water will depend on where you are fishing in Australia and at what stage the 28 day lunar cycle is at.

The rise and fall in the sea level as a tide crest approaches and pauses will cause a tidal current of water to flow into and out of bays and harbours. This water rushing into an enclosed area, due to a rise in the sea level is called a flood tide and water rushing out because of the fall in the sea level is called the ebb current.

For example, you could be fishing the Parramatta River in Sydney for yellowfin bream at the beginning of the month when the moon is in the first quarter and you have a high tide of 1.5 metres. Then come back and fish the same place when there is a new moon in the same lunar cycle, and find that you have a high tide of 1.9 metres. What this does for the yellowfin bream at this spot in the Parramatta River is that it allows them to forage further up the bank to areas that they normally won’t be able to get to, which then enables the angler more areas to target the yellowfin bream.

Bill is concentrating on watching his float for a down while chasing luderick at the last hour of the run-out tide © Gary Brown

As an angler you need to take note of these different tidal conditions, because these changes in the tidal current (flow) will governed whether you will need to change or adjust your rigs to suit the conditions.

To help you out I will give you three examples of what I mean:

Example 1 Estuary:

If you were fishing for luderick near the top of the tide on the run-out and the current/flow of the water was not fast you would be able to let your float go along with the current/flow. But what you would find as the tide started to get half way down the tidal current/flow would have increase to a point where you would have to slow your float down by holding it back.

Example 2 Beach:

Sand whiting and mullet are usually one of the first fish to start to forage up in the shallower areas of the beach. This will start to happen when the water starts to flood over sand spits, bars and right at your feet at the water’s edge. This rise in the tide will indicate to the pipis, crabs, beach and tube worms that it is also time for them to start and look for a feed. You will also find that the movement of the waves will dislodge some of these creatures ready for the whiting to pounce on. The sand whiting will also tend to be one of the last to leave these areas as well, making them easy prey for the larger fish species that will patrol the deep parts of the beach looking for a feed.

The author with a 79 cm dusky flathead that was caught while working soft plastics on a rising tide. © Gary Brown

Dusky flathead will be one of those larger fish species that will be waiting just off the edge where it drops into a gutter, channel or a hole. This will usually occur during the last part of the falling tide as the whiting are leaving the shallow areas. Dusky flathead will also go up onto the sand flats and bars and bury themselves and lay in wait for the unsuspecting fish that are foraging at high tide.

This type of rock formation would not be accessiable at the top of the tide. © Gary Brown

Example 3 Rocks:

I have been fishing off the rocks just before the top of the tide and have seen drummer and luderick come up with a wave and lay on their side to feed off the green weed and cabbage that is usually out of reach. There has been no more than 10cm of water. This would be a good time to use an unweighted piece of green weed or cabbage.