Using Depth Sounders

Part 5: Beyond Screen Time

Modern, state-of-the-art depth sounders are fantastic tools, and a massive aid to any form of boat fishing, but it pays to remember that they are only one part of the bigger picture… You also need to know when to ignore them!

Not so subtle signs! Golden trevally busting up on jelly prawns in a tropical estuary are clearly visible… but only if you look up from that mesmerising screen.
The two finest fish-finders ever created are the pair located on the front of your head… hopefully protected and enhanced by a pair of quality polarised sunglasses. Use them!
Birds like these pelicans can often pinpoint the presence of bait and larger fish. Study their behaviour carefully and take advantage of the clues offered.
These tuna were found by watching for seabirds and splashes, not peering at a sounder screen.
You might not mark these surface swimming mullet on a sounder, but they are very easy to see with the pair of "sounders" nature gave you.
Sometimes it's more about visual structure than anything your electronics can show you.
The best way to find out what's making those marks on your sounder is to drop a baited line or lure down there and catch one. Morwong look much like snapper on the screen.

Years ago, when I was working on Rex Hunt’s TV show, we were filming on a Top End billabong. I was in the camera boat and at one stage we’d cut the motor and drifted so the cameraman could shoot some boat-to-boat footage of Rex casting from the other vessel. Our boat had slowly drifted stern-first toward the bank, and eventually came to rest against a thick weed bed.

“Wow! This is where we should be fishing!” our boat driver suddenly announced. I looked at him with one eyebrow raised. “Check out all the fish on the sounder!” he explained, gesturing excitedly at the screen in front of him.

I walked back to the console and looked over his shoulder. We were only in a metre or so of water, but sure enough there were a couple of very interesting targets on the screen. Perplexed, I turned to the back of the boat where the transducer was located and peered into the water, which was quite clear for a tropical billabong. I could just make out the muddy bottom below and the edge of the weeds. There were no fish to be seen, but there were a couple of long strands of weed waving about in mid-water. These were no doubt the “fish” our skipper had excitedly identified. I was still pondering how to gently explain this to him when a shout from the other boat summoned us back to work and the moment was lost. But I never forgot that important lesson. It’s one I’ve seen repeated many, many times in the years since.

Many anglers spend too much time gazing at their sounder screens and miss a lot of the other things going on around them.


Modern sonar units or depth sounders are wonderful pieces of kit, and they’ve completely revolutionised much of our fishing. Many anglers (myself included) would be lost without them in some scenarios.

That said, I fear that many of today’s anglers spend far too much time gazing intently at that magical electronic screen and miss a lot of the other things going on in the real world all around them, including vital information that could directly impact their fishing success. This may well be a reflection of the “device dominated” era we live in nowadays: one that sees a lot of people (especially those from younger generations) glued to screens of various types for a huge chunk of their waking lives. I would respectfully suggest that they’re missing out on a great deal as a result.

The clues, cues and intel’ available to us as fishers runs the full gamut: from glaringly obvious signposts such as wheeling, diving seabirds over a school of feeding fish to far more subtle hints, like a barely perceptible change in the temperature of an aluminium boat hull detected through the soles of bare feet, or the flick of a single jelly prawn hard against a mangrove root caught briefly by our peripheral vision. Unless you look up from that screen occasionally and open your senses to the bigger picture, you’ll miss a lot of these subtle inputs.

Hand-in-hand with this big picture awareness should go a certain degree of healthy scepticism about what you’re actually seeing on the sounder screen. Social media is full of amazing images revealing various species of fish and other aquatic life displayed in graphic detail on various sounders. I love these spectacular screen shots as much as anyone else, but I also accept that the conditions needed to produce them are the exception rather than the rule. Far more often, we’re working with vague suggestions and tantalising clues rather than hard facts.

Lift your head from time to time and have a look around… There’s a whole world out there beyond those dancing pixels.

It pays to remember that a mullet or a blackfish can return a near-identical sonar signal to a bream or a snapper, that a carp looks very much like a golden perch on screen, or that strands of weed can pass as fish to the uninitiated.

Interrogate every assumption you’re tempted to jump to, and do your best to validate those assumptions with real-world experience and direct observation. In short, lift your head from time to time and have a look around… There’s a whole world out there beyond those dancing pixels.

Any questions about this tutorial?


  1. peach

    So very true Steve, great series of articles, thank you!

  2. Mark Dullow

    Eloquently put. That’s why I shout out the car window at people blindly walking along the street glued to their phone…… “The Phone works, try the brain”…….

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