Repeat after me: Tide is everything in the marsh. Tide is everything in the marsh. Tide....is...everything.
Think of the blood that runs through your veins. If it suddenly stopped you would keel over and die. The marsh isn't a whole lot different. When the water is moving due to wind and/or tidal forces the marsh is alive and everything is feeding. When the water doesn't move at all the marsh becomes a ghost town as everything waits for the water to move again.
What moves the water?
I already covered this knowledge in Understanding how and why the Water Moves (in case you need to refresh your memory).
Why is moving water important to fish?
Moving water is important to fish because it brings their food to them.
Everything in the food chain becomes more readily available when the water is moving.
Rather than go searching for food and burn precious energy they can sit in one spot and wait for the food to come to them.
Crabs travel when the water is moving. Oysters depend on moving water in order to eat.
Shrimp eat organic detritus (a fancy phrase for crap and small pieces of rotted meat) and algae. They can find those things more easily if they are brought to them or the other way around.
See, baitfish like shrimp don't have a lot of swimming power, Neither do smaller finfish. They get swept away with the tide, so you can depend on flowing water being something like a highway that they travel on.
These highways become visible in the form of tidelines.
What are tidelines?
In some places throughout the marsh we can see something called "tidelines".
These are formed when moving water concentrates in an area and are often visible from your boat, but not always.
They are certainly visible from the sky and they are important to locating the "right" kind of moving water and catching a lot fish.
This is why Google Earth is so valuable!
Here is an example of a tideline in the marsh:
How to Find Tidelines
Tidelines usually appear in the same places under the same conditions. They can shift in one direction under a falling tide and the opposite under a rising tide. What's neat about Google Earth is that we can see tidelines on days there are rising tides and days there are falling tides, so we have an idea where we need to be fishing.
Open up Google Earth and take a look at the marsh at coordinates N 29° 45.680' W 89° 29.810'. Now, ensure you are on the same imagery I am on. Look at the bottom right corner.
Does it say October 31st, 2012?
If not, go to the Time Slider and set it to that date. The Time Slider is cool because you can go forward and backwards in time to see different images taken of the marsh. We can see how things have changed but also how things were on that specific day in time.
Now that we are on the same sheet of music and looking at October 31st, 2012 you can very easily see where tidelines are. Here is one coming out of the bay and going into the MRGO, that large canal that runs from northwest to southeast.
This one is very easy to see because the water became very low and dirty and the tideline was "painted" with that dirty water. A strong cold front had passed through, lowering water levels and dirtying water clarity.
If you scroll around the marsh you can see other tidelines as well. It is in these places where fish stack up and take advantage of the moving water to eat bait. However, they won't be at every tideline every time. The bio-mass of fish moves around the marsh with optimum conditions and bait, so it's possible you can pull up to a picture-perfect tideline and not catch anything.
How do we know if the tideline we see on Google Earth is from a riding or falling tide?
There are a couple ways. Generally speaking, if the tideline is pointing towards the center of the marsh, away from the sea, then the tideline is resulting from an incoming (or rising) tide. If the tideline is pointing towards the open sea, then the tideline was formed by a falling tide (or outgoing tide).
There is also another way to know.
You can look at historic data of weather stations posted throughout the coast of Louisiana. In this case, the nearest weather station is the one located on the shore of Lake Borgne in Old Shell Beach.
Shell Beach NOAA Buoy
Click on "Water Level" on that page and you are taken to a graphical interface of the meteorological and oceanic data that buoy is recording. You can input different dates to see what the conditions were like on that day. When we input October 29th, 2012 we see that the wind was howling out of the northwest
On that day in 2012 we can see that the wind was howling out of the northwest and dropped water levels considerably. Since the water was dropping all day, we know those tidelines are from falling water levels.
That may have been a little confusing to take in all at once, so watch this screencast to get a better idea as to what I am taking about.
Finding the "Right" Kind of Tideline
Like I mentioned earlier, not every tideline is going to produce fish. If you are fishing a part of the marsh the bio-mass is not present in then you are just fishing the wrong part of the marsh, regardless of how good the tideline looks on Google Earth.
But, there is a way to cut down on time lost fishing tidelines that look good, but really aren't that great. This is a trick I learned through trial-and-error as a charter captain and I am saving you a lot of time and energy spent by sharing this with you.
Remember when I referred to tidelines as highways? That is absolutely the case, but they are thoroughfares of varying sizes. Some tidelines are the equivalent of sidewalks, others are side streets and some are giant, bustling interstates. Some side streets get lots of traffic and others do not. Some interstates are lonely and others have bumper-to-bumper traffic.
This tideline is an example of a sidewalk:
This tideline is an example of a side street:
This tideline is an example of a huge highway:
Tidelines are very much the same way as roads and you want to locate the tidelines that have the most traffic. Time spent fishing empty streets will lead your fishing trip down the path of failure.
The sidewalk example, even if it is jam-packed, will never carry enough specks or reds to limit out on. It is a feasible strategy to hit up many "sidewalks", but I would concentrate on the larger paths of traffic first. I like to concentrate on "big water".
BIG water = BIG tidelines = BIG groups of fish.
The sidewalk tideline pictured above is an example of a tideline you wouldn't want to spend much time, if any, fishing. It simply does not have enough water coming out of it to carry enough bait to interest a huge school of speckled trout. However, there are always exceptions.
The "Huge Highway" tideline is an excellent example of the kind of tideline you want to spend time fishing. In big tidelines like that, you can anchor down in the middle of them and catch fish on either side of the boat.
Ultimately, know which tidelines are good and which ones are not will come with experience, having fished them not once or twice, but several times. Not all big tidelines produce fish and many small ones I have caught limits of fish from. You cannot beat experience.
...but tidelines are not everything.
There are many more features in the marsh that keep loads of fish waiting to be caught. In the following sections I will cover this.