Echo sounders really are invaluable when fishing the big, wild waters for predatory fish. Most of the time, the echo sounder is used for looking at the depth and finding fish-holding structure. In my experience, even the most sophisticated echo sounders cannot be relied upon when it comes to identifying individual big fish. I often laugh when I see anglers staring at the screen, usually with the ‘fish symbols’ mode switched on and remarking ‘oh, there’s a really big pike…’

The fact is that echo sounders are like computers – they interpret the signals they recieve to a pre-programmed set of perameters. That is why they will mistake a sub-surface leaf for a fish, a shoal of prey fish for a single, bigger fish and so on.

Without a doubt, however, echo sounders are getting better and some are better than others. So far, I have found nothing to beat Lowrance. I have owned an X-19 C for four years now and I cannot praise it highly enough.

Here are some screen shots taken from the unit on a recent trip to Ireland. I find them fascinating and also a tribute to the amzing power of the Lowrance. Bear in mind, as you lok at these pictures, that the fish ID is turned off.

Baitfish appear as small streaks of red or yellow. The denser the shoal, the deeper the colour until the mass of fish shows as a large ‘blob’ of red and yellow.

Bigger fish, including predators show as larger streaks or ‘arches.’

 

  This shot shows a huge shoal of baitfish on the bottom. Look at the 30 foot mark and you will see a broken line rising from right to left that signifies the shoal is lying on a slope. The depth of the shoal is over fifteen feet. The shoal is a large vertical cluster that extends from the bottom marker up toward the surface, with the peaks being above the fifteen foot marker on the right hand side of the screen. This is a huge shoal of fish, probably roach or roach bream hybrids. 

 

Here is another shot showing a cluster of baitfish on the right (typical ‘ball’ formation) and the larger arches on the right probably being predators. This shot is very interesting because it shows how the larger predators (the arches on the left of the picture) have balled the baitfish into a tight group. In my experience, predators are often found adjacent to baitfish shoals though the distance will vary according to whether the predators are resting or feeding. In this case it is my belief that the predators were actively balling the baitfish up ready to attack.

The next shot shows predators located in a more typical position away from the main shoal of baitfish. 

In this case, the predators are lying together and their position seems to indicate that these are resting, not feeding fish.

Finally, lets look at an attack situation.

In this instance there are some distinctly larger arches located among and over the baitfish shoal. These may well be attacking predators.  

At the end of the day, the screen shots shown here are snapshot pictures of an underwater scene that needs to be interpreted by the viewer. The more you understand about predatory fish behaviour the better you will be at interpreting what you see on the screen.

I must repeat that echo sounders are not infallible but tuned correctly they provide valuable clues as to what is going on down below. Certainly, the better echo sounders will give more reliable information and they must be tuned correctly to optimise performance. Read the manual carefully and tune your sounder to filter out unwanted interference. Always use the sounder on ‘arches’ not with the fish ID switched on.