Spotting sharks on your sounder to help reduce bite-offs

“The taxman”, “the men in grey suits” or just plain old “bloody sharks.” Whatever you call them, sharks biting off your prized catch as you bring it into the boat can be the bane of many fishers’ fishing trips north of Geraldton.  

As fishers prepare to head north for their eagerly anticipated winter fishing trips, we continue to arm you with information that can help reduce, if not completely prevent, the number of hooked fish lost to sharks.   

A good starting point is this web page we have put together having talked to some of the experts with a bunch of good tips, one of which is avoiding areas where sharks are present.  

But how can you tell if you’ve got sharks under the boat where you’re fishing? In this latest article we’ve talked to a number of fishers and charter fishing operators who regularly encounter sharks during their fishing trips and asked for their advice on how to spot sharks on your sounder. This can allow you to choose not to bother having a drop or a troll where they’re already present, or moving on as soon as you see them coming into your spot.  

Want to avoid this under your boat while fishing? Check out our tips below!

A sounder approach to limiting shark bite-off

With sounder technology going to the next level in the last decade or so – it means fishers can survey what is under the boat before dropping a line better than ever before.  

While sharks have an advantage at picking up fish scents and fish struggling on the end of your line in a flash – to their distinct disadvantage they are relatively easy to spot on a sounder.  

How do they stand out? Unlike scalefish generally targeted by fishers, sharks do not have gas-filled swim bladders. 

This means they will generally appear as a continuous solid or even wavy line on sounders, rather than the curved arches that show up on the sounder screen that generally indicates scalefish.

As seen above in this Simrad sounder image supplied by experienced fisher Ben Knaggs from the Exmouth Game Fishing Club, sharks can be spotted as long, solid lines on sounders, while fish will show up as hill-shaped arches.


Sharks are usually a strong, continuous line from left to right and do not show up as arc shapes due to their absence of a gas-filled swim bladder. These sounder images demonstrate how they will appear on most Simrad sounders with varying scan options. Thanks to Chris Tanti for providing these images.

Josh Bruynzeel, skilled fisher and crewman from On Strike Charters in Exmouth, said sharks are easy to distinguish on all sounders, regardless of their price range or brand if you know what to look for.  

“Sharks appear as a solid line that goes from left to right on your sounder rather than a fish arch,” Josh said. “They will also move under the boat and follow you regardless of your speed, whereas fish will generally sit on structure and tend not to move too much. 

“You will get a solid echo from the front to back of sharks, the line doesn’t tend to fade either as it does with fish. Depending on the ping speed of your sounder, if it is higher you may also get multiple lines appearing on top of one another and that is a shark, but generally they appear as one long, continuous line and I would advise you don’t bother dropping a line if you see that on your sounder.”  

Chris Tanti, a Simrad and Richter pro-teamer, and a recent winner of the Shimano WA Open in Jurien Bay, also said sharks are easy to differentiate from fish.  

“The main difference between sharks and fish is sharks don’t have that arched ‘boomerang’ appearance on your head unit. Another factor is unlike bottom-dwelling fish that generally live close to the ocean’s substrate, sharks are generally higher in the water column and must ‘continually swim to live’ so to speak,” said Chris.  

Chris Tanti also provided an array of other measures fishers can explore on their sounders during fishing trips. 

“Because most fisherman aren’t targeting sharks, generally I wouldn’t play with your sounder settings too much. For instance, if you’re targeting bottom fish leave the settings that best suit you for that style of fishing. This is where bottom lock and depth line comes in handy to clearly differentiate the seabed from fish species,” said Chris.  

“Another handy feature for pelagic fishers is TVG (or Time Variable Gain). Having this turned up will show you the ‘actual’ size of the fish as the head unit will work harder to show ‘true’ sizes of fish and sharks deeper in the water column. For example, if your TVG is set at 1, a 6-foot shark may look much bigger at 10 metres than say 20 metres.” 

Pictured above is an example of the solid echo from a shark on a Furuno sounder, showing a continuous line from left to right with the absence of arch.


Some modern sounders with advanced technology such as the Garmin Livescope pictured above have highly detailed down-scans below the boat and can easily identify when sharks are present with clear outlines. To see a video showing sharks on a Garmin Livescope sounder, click here.

Be selective about the ground you fish

Josh also recommends steering clear of good-looking structure close to shore that is commonly fished, as sharks know hooked fish are easy targets at these locations. 

While this kind of structure can look mouth-watering to anglers on sounders and often holds fish, sharks learn that these spots frequently see lines dropped down, leading to hooked fish and easy meals.  

“The further away you travel from shore, the less likely it is you will come across sharks. I catch 99 per cent of my demersals off flat ground and most fishers don’t realise that bigger fish frequently sit under ledges only half a metre high.  

“I don’t bother fishing big lumps or structure because it is almost always covered in sharks. I’ll fish mud, sand or rubble where fish will still gather but sharks don’t tend to,” added Josh. 

Keep moving spots to keep the odds in your favour

Eddie Lawler, owner of Peak Sportfishing charters in Exmouth, said one of the easiest ways to avoid shark-bite off when fishing is to move spots frequently as boat activity and increased fishing action can act as a dinner bell for sharks. 

“My biggest tip is to keep moving, regardless of whether you’re catching fish or not. As soon as we get one or two fish in the boat, we move spots immediately and try to put a fair amount of distance between each drop,” said Eddie.  

“I’ll also do mock drifts over the spot I plan to fish with no lines in the water to analyse what it looks like on the bottom, to see if any sharks are in the area and to confirm the direction of the drift, but moving frequently is essential. Do not sit on a spot all day because your odds of getting sharked go through the roof. 

“When we catch billfish, we also try to limit the amount of time that the fish are tied to the side of the boat and we never lift them out of the water. We release them as quickly as possible and don’t sit on one spot waiting to be sharked.”  

If the fishing action is red hot at a particular spot, Chris Tanti said it’s wise to protect the future of that spot by not lingering for long.  

“If you have a favourite ‘honey hole’ and suddenly lose a nice fish to a shark there – I’d highly recommend picking up and motoring (with haste) to another spot to protect that cohort of fish,” Chris said.  

“I was bottom-fishing recently off Mandurah and hooked a solid dhufish before it got sharked and I only got the head back. There is absolutely no point in staying there when that happens, you’ll just lose more fish and knock off the local population without getting any fish on the deck,” said Chris. 

Many fishing experts such as Chris Tanti advises all boat fishers to get to know their sounders well and learn to differentiate how fish and sharks will appear on the scan.


Chris Tanti is a highly decorated sportfisher in Western Australia and has spent years mastering how to avoid sharks in our State’s northern regions.

More shark tips from one of Australia’s best sportfishers 

As for what to do once you hook a fish to keep it away from awaiting jaws, Chris has numerous tips you can try.  

“For bottom fishing – especially deep dropping in places like Exmouth where sharks can be a real problem – I like to click the boat into gear once the fish is clear of the bottom as the sharks have learnt to follow the boat. This brings the catenary of the fish up on a larger angle.  

“Once the fishes swim bladder expands and it starts to come up quickly, I usually try to get on top of the fish as quickly as possible. You can also throw diversions at the sharks such as bait if you have any.”  

With a lot of impressive sportfish catches and experience under his belt, Chris also advised fishers should lower their drag right back when they hook a fish while trolling.  

“For pelagic fish – don’t be afraid to almost free spool your reel if a shark is on its tail. Sometimes sharks give up on an easy feed if a fish powers away with speed and the fish is easy to chase down and get in the boat when you do that as its lactic acid has built up, meaning less work to land it safely. This is a great technique if you like using lighter gear and enjoy your sport fishing. 

“Don’t be afraid to chase your fish down either in the boat if you’re trolling. If the fish is running away from the boat, chase it down and reduce the amount of line you need to reel in when it runs and this also puts the odds more in your favour,” added Chris.  

The crew from Peak Sportfishing in Exmouth move spots frequently to reduce their odds at attracting sharks and quickly release all billfish landed without bringing them on board.

Chasing more tips on how to avoid sharks on your fishing trips? Check out our webpage containing all the best shark bite-off tips here.

Continue Reading

July 02, 2024

Check out the stunning marine life brimming around the artificial reefs off Mandurah and Perth!

Check this out, metro fishers – large schools of fish being spotted on our Perth “Fish Towers” and Mandurah artificial reefs picked up by our latest scientific monitoring using baited underwater cameras…

Read More

June 26, 2024

King of the Reef crown and $15k up for grabs in Exmouth Fishing for Science comp!

To celebrate the spectacular fishing on offer at Exmouth’s King Reef, Recfishwest is teaming up with Woodside Energy and the Exmouth Game Fishing Club to deliver the ’King of the Reef’ Fishing for Science…

Read More

June 18, 2024

Senior Police Sergeant says fishing safety angel ring saved man’s life at Quobba

A Carnarvon senior police officer at the centre of a risky rescue of a fisher washed off the rocks on our Mid-West coastline said the man would not be alive had he not been kept afloat by an angel ring –…

Read More

June 07, 2024

Gascoyne’s spectacular fishing on full display at Carnar-Fin Fishing Competition!

Hundreds of local community members and more than 250 fishers flocked to Carnarvon to experience the highly anticipated Carnar-Fin Fishing Competition.  Since its inception in 1992, Carnar-Fin has become an annual…

Read More

May 31, 2024

Get your marine park submissions in by June 16 to defend access to our cherished fishing spots

Recfishwest is urging ALL FISHERS who care about protecting access to cherished fishing spots to make a South Coast Marine Parks submission before the June 16 deadline. Whether you live and fish on the South Coast…

Read More

May 30, 2024

Fishing families flock to Denham for 2024 Shark Bay Fiesta!

For the 29th year running, the coastal town of Denham swelled in size for the hugely popular Shark Bay Fiesta that celebrates the fantastic fishing on offer in the Gascoyne region.   Recfishwest joined the Denham…

Read More