Understanding the tides
25 September 2015
The importance for fishos to understand the tides cannot be underestimated. Al McGlashan reveals pointers that are sure to help you catch more. Tides are the single most important factor in dictating bite times. It doesn’t matter what species you’re chasing, from billfish to gurnard, their movements are dictated by the tides.
Everyone seems to understand the importance of the tidal effect in estuaries, especially up north where the tides can be huge. But offshore it seems it is rarely considered by most anglers, yet it is just as important. We can’t see it so we don’t think about it.
The common misconception is that there is no tide offshore, but that is only because we can’t physically see its effect.
In an estuary you can see the tide exposing the sand banks then comes back in flooding everything, but offshore there is nothing to actually compare it against.
While anglers may not be able to see it, the fish can certainly notice it.
The tide influence is just as strong on all predatory fish be it snapper or marlin. However, its effect goes one step further and it is worth pointing out that tide often affects prey species even more than the predators.
How tides work
Everyone knows that the tide comes in and goes out, but when you delve deeper into it, there really is a lot of detail involved in the tide and how it works.
The earth and the sun spinning on their axes have a big bearing on the tide but the biggest influence is in fact the moon.
Being closer than the sun, its gravitational pull is substantially stronger and it pulls the water out towards it as it spins around the earth. This creates a bulge in the water wherever it is pulled towards the moon. It is mirrored on the opposite side while at each end of the earth it shrinks to compensate. As the earth and moon move relative to each other the moon pulls the water with it creating the high tide.
The moon circles the earth every 28 days.
During this time the earth rotates every 24 hours and 50 minutes, which is why the tide change varies from day to day.
When you see the moon rising it will be a run-out tide but when it is overhead it is a high tide because you will be in the centre of the bulge. Slack water is when the tide comes to a complete stop before swinging and going the other way. It’s a bit like throwing a ball in the air - it goes up, stops dead and them comes back down.
What is interesting is how long it stops for. On the full moon the slack tide may last a few minutes while off the moon it can be 20 minutes or more. This seems to be directly related to the intensity of the bite.
On spring tides the bite can often be really intense but it never lasts long, alternately on neap tides the bite period tends to last a lot longer.
Basic understanding like this will play a massive role in helping you to understand how to maximise your time on the water.
If you are planning any fishing time in saltwater then you need to use the tides. When you have a good day on the water check and compare the time to the tide so you can build up a mental bank of when the fish bite according to the tide. Do this and you will catch more fish.
A classic example of this occurs most days at the entrance to most estuaries and bays. With the run-out tide, bait starts to stack up as it is forced out. The predators know this and congregate to take advantage of the situation. Salmon to sharks and kingfish all take advantage of this tide-induced feeding frenzy. This is a scenario that is repeated right around the country.
Offshore the upcoming tide change sees massive bait shoals rise up from the depths towards the surface. While the bait isn’t the primary target, it certainly draws up predators with it so the tide directly affects the bait, which in in turn influences the target species. Why the bait rises up is still something no one can answer.
As a general rule you have four tides a day. As a result of this we get the occasional days where we end up with five or three tides. Try to coincide your fishing day with at least one tide change and preferably two. If fishing offshore an 11am and 5pm is just about perfect and means you don’t have to get up too early!
In estuary waters where the run-out or run-in will produce the better fishing you have to be a bit more precise with your fishing to match specific tides as opposed to simply a tide change.
King of tides
Tides are not equal. They vary greatly in size throughout the year. In places like Auckland the variation is minimal, barely more than a metre.
In the Kimberley in Northern Australia it’s more than 10 metres.
Larger spring tides occur around the full and new moon when the sun and moon are aligned creating maximum draw. The smaller neap tides occur on the first and last quarters (half moons) when the moon’s effect is least.
Some of my best fishing sessions have been around the build up to the full moon, which happens to be the neap tides. One of my favourite times is the end of the neap tides just as they start to grow towards the springs because we have the clearest water but increased water movement at the same time.
This writer hates fishing on a full moon when the springs are in full effect. It is the week leading up to the moon that sees the most consistent action.
Kingies and snapper inshore and even marlin offshore all see an increase in activity four to five days before the moon.
Don’t discount big tides in the estuaries. The water clarity will be less but being bigger the springs cover more ground at the top of the tide.
This allows many of the estuary inhabitants a chance to feed over fresh ground. Species such as mullet will get right up in the flats and as a result predators like trevally follow them.
Things change dramatically after the tide turns and suddenly all the prey species need to get back and the predators are there waiting.