Hutchies III: Sounding Out Hutchies With Frank Oo
  |  First Published: July 2008

Last month I mentioned that I’d been fortunate enough to fish the Hutchies region with Bribie Island bluewater guru Frank Oo. During fishing and chatting to Frank I interviewed him about his fish finding philosophy. The answers were pure gold!

The study of bottoms and baitfish using your sounder is the single most important item I see novice crews overlooking when they hit the bluewater in search of bottom fish. Learning how to read your sounder is fundamental to great results, so read on to get some secrets to success.


The coral reefs around Hutchies can be quite tall and can be full of ledges, caves and drop-offs. The varieties of fish that live on Hutchison’s Reef are amazing, and although there are millions of fish on top of the reef itself, they consist mainly of wrasse and lancers that are very colourful but small. Hutchies is a location where you really have to study the bottom until you find congregations of larger fish and this normally occurs in depths over 35m.

In the more adventurous days of his earlier life, Frank used to do a lot of spear fishing. He tells that when he first started spear fishing he could never understand why the other guys would always get the bigger fish until one of the guys told him that you actually have to put your head under the ledges to be able to see into the darker areas of the reef. Only then could you see the crayfish and other species of fish that live in and under the ledges. Frank was amazed to see that the majority of reef dwellers remained in hiding until tasty morsels of food proved too much to resist, then they would dart out of hiding and snatch the bait.

Pelagic fish have their own environment and live around the reef when the baitfish are there but most of the reef dwelling species will use the reef as cover. Pearl perch use the wire weed and many other species also use the kelp beds to hide in. Cobia are known to inhabit the ledges and can often be found swimming in large schools next to a vertical drop or ledge that is formed by part of a reef or rock.

Frank mentioned that he had always thought snapper lived on the bottom but since using soft plastics he found that it is quite common for snapper of all sizes to slam the lure within seconds of hitting the water. So the evidence has him convinced that snapper definitely school anywhere from mid water to the bottom.


Good fishing spots are becoming harder to find so during the warmer months Frank does a lot of trolling for the pelagic species such as marlin, sailfish, mackerel, wahoo, mahi mahi and tuna.

While trolling he keeps one eye on the sounder keenly looking for new spots. Fortunately for Frank, and everyone else who employs the tactic, Hutchison’s Reef is also surrounded by some of the best marlin grounds in South East Queensland. The area between the Trench and Hutchies still provides marlin, mahi mahi, Spaniards, wahoo, cobia and tuna on a regular basis.


A caveat to this section; I will admit that what you are about to read won’t always agree with the simplistic view given in various media on how to set up your sounder. However, I’ve been privileged to fish with some of the best Aussies ever to dial in a sonar and this method, while slightly more involved, will catch you more fish. Guys who work their sounders hard certainly find the fish.


Frank recommends getting the highest power transmitter available when selecting your sounder/transducer combination. This allows you to view the bottom very clearly whilst trolling.

It is also really important to be able to interpret the information that you are receiving so you must be able set up your sounder to give you the clearest information.


Frank states that manually selecting both the upper and lower limit of the depth range will give you a much clearer picture than just simply zooming in on the bottom.


Set your sensitivity to allow you to identify more clearly each individual fish or the type of bottom you are trolling over.


If you invest in a good quality dual frequency sounder with a high resolution, you can actually identify each individual fish as an arch. In saying that, a big fish doesn’t necessarily mean that it will be displayed as an arch. An arch will only occur if the fish is positioned in a certain spot relative to the transducer, but that is another story.

In most cases fish may only be shown as lines and depending on the strength of the sonar return, you may see a stronger echo. Don’t forget that you will only see arches if you have selected raw video, if you have selected a fish icon that is all that you will see. Frank prefers raw video because he can understand a lot more from that type of display.

The following quote from Frank is right on the money,

“I find it very hard to distinguish one fish from the other on the sounder, in fact it is impossible. The first 20 years of my working life was spent working as an electronics technician with the Royal Australian Air Force and during that time I spent three years teaching RADAR theory. Sonar is just RADAR underwater. The transducer sends out a pulse and waits for a return echo from the ocean floor below or a fish.

“The size of the screen paint is dependent on the size of the return. A really big fish will give you a strong return but may not paint a really big line on the screen. A hard rocky bottom will also give you a much stronger echo and can be seen as a thicker bottom because the strength of the echo has increased. A modern colour sounder can discern the size of the echo by allocating a more vivid colour to the stronger echoes. The hard bottom or larger fish is painted red whilst the smaller fish may be light green or yellow. A very tight bait ball can be shown as a big red blob and you can quickly see if something is chasing them by the holes formed in the blob.

“I have found that you can predict the type of fish by their habits. It is normally very easy to identify amberjack by the long trails that move up and down the screen as they chase the bait. The pearl perch seem to hang around in big blobs just off the bottom and the snapper appear to be suspended some meters off the bottom but in a more open school.”

To throw in an observation by the author, patchy snapper can often appear on your sounder as a faint squiggly line, with maybe a red dot or dash in the line.


Frequency can be an important factor yet Frank offers a very interesting observation on this,

“Mostly shallow water anglers won’t see any benefit from a dual frequency system. I suggest that a more powerful sounder (2,000W) is far more important because most fishers would not fish much deeper than 60m. Having said that, there are many of us that do venture out in deeper water but I find that my sounder will still let me see everything up to 150m.

“A second lower frequency (slower rate of pulses) can be quite useful in identifying fish in much deeper water. In fact most dual frequency sounders will have the ability to view both returns by splitting the screens so you can compare the echoes. The dual frequency transducer will allow you to send out both frequencies and will discriminate between them by filtering out only the correct frequency for each system.”

Bottom Study

Closely examine the size and type of bottom by studying the sonar screen. On a Lowrance colour unit the sounder will indicate the type of bottom by offering you a strong thick line on hard reef or rock, and a saw-tooth return occurs over wire weed. Sand on the other hand, is shown by a very thin line on the bottom with very little contrast.


Ideally you’ll have found an abundance of bait close to the structure. Often, if there is no bait there will be no fish. And Frank’s opinion on the importance of baitfish,

“It is also important to understand that although the bait is not there at that time it does not mean that the bait will not be there three hours later. If you want to catch fish you have to find the bait. You only have to examine the food chain to understand that the smaller fish will be eaten by the bigger fish. But I should also add that just because there is a lot of bait on the sounder, it does not necessarily mean that there will be bigger fish lurking around underneath.”

Next month we’ll look at the other part of the electronic equation, and explain how you can combine your GPS and sounder information to multiply the benefits of both.

Also, patchy snapper can often appear as a faint squiggly line, with maybe a red dot or dash in the line.

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