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.

Tips from the experts on how to avoid shark bite-off

All around Western Australia and particularly heading north of Geraldton, a lot of fishers know the frustration of losing prized hooked fish to sharks.  

Many of us have experienced the sickening thump on the line, as the rod locks over with the line sizzling off the spool as your would-be catch gets engulfed, leaving just a lifeless head to be reeled in. It’s that or worse still – a clean bite-off with all your rigs going with the ‘tax-man’ as well as your fish.  

That’s usually the dinner bell for multiple sharks to gather in the area, meaning getting hooked fish on the boat becomes a frantic race against the chasing pack.  

This scenario quickly steals not just hooked fish, but also the enjoyment out of fishing, not to mention is financially painful from lost rigs.  

As seen above, prized catches can fall victim to shark bite-off, with only portions of the fish being landed or not at all. Left image credit: Marco Fraschetti.

Unfortunately, for fishers who decide to stay in the same spot and carry on battling mother nature’s most adapted marine predator, it is more often than not a losing battle leading to high fish mortality.  

Losing high volumes of high value species to shark bite-off is avoidable though.  

While sharks might have 400 million years on us regarding perfecting hunting fish in the ocean – there are many experienced fishing experts who have great tips on how to best avoid sharks – and profanity-riddled fishing trips.  

Here is some great professional advice on avoiding the ‘men in grey suits’ from Steve Riley – owner of Exmouth Tackle & Camping Supplies and the staff from Tackle World Exmouth.

Keep moving fishing spots 

This is the simplest yet most effective tip. It is widely known that once sharks move in on your spot, it’s only going to get worse. “Don’t leave a bite to find a bite,” may be an old fishing adage that holds water – but if you’ve been successful in getting a couple of fish on the boat, it might be worth considering moving spots before the sharks join the party.

It is also worth trolling off to the side of renowned prized fishing spots. The artificial King Reef located east of Exmouth is one spot favoured by many that holds plenty of fish not only on the structure, but 50-100m away from the artificial reef itself. So avoid dropping a line directly on top of the reef as sharks will congregate in more numbers next to the structure. Fishers at the reef also report better catches that are untouched by sharks when fishing adjacent to the structure itself.

The moment your catches start falling victim to sharks, it is time to move spots immediately. Most of the time, shark bite-offs are only going to get more likely and worse the longer you stay at each fishing spot.

Avoid areas known to be shark hot-spots  

Don’t waste your time and gear going to a spot you know to have been bad for shark-bite off previously. Sharks are opportunistic feeders and will learn where it’s likely to grab an easy feed. For this reason, it is always a wise idea to fish a fair distance away from boat ramps.  

Sharks attuned to the sound of outboard motors have also been observed following boats out from boat ramps.  

Consider using shark deterrent devices  

Shark deterrents do not stop sharks entering a fishing area, but they do provide more time for anglers to land their fish, which is crucial. DPIRD research suggests the probability of sharks taking fish can be reduced by as much as 65 per cent when using deterrents.  

To get the most out of these devices, it is important to rig them properly and position them within one metre of your bait and only have one hook if using a paternoster rig setup. Regardless of using deterrents, the rate of bite-off is highly likely to increase the longer you remain in a fishing spot.  

Click on the video below for tips on how to properly rig shark deterrents like Sharkbanz

Turn your sounder and engine off once reaching your fishing spot  

Sharks have been known to sense the sonar activity from sounders and a running engine can also bring them in knowing fishers will start dropping a line.  

One crucial step to avoiding sharks is stealth. If you are confident in the reliability of your engine, switch it off at each spot along with your sounder. If your engine can be tricky to start, avoid turning it off and simply move spots frequently.  

The sonar emitted from your sounder and the rumble of boat engines is known to attract sharks, which can quickly turn treasured fishing spots into ‘shark city’ when you drop a line.

Try putting your reel in free-spool if your fish is being chased by a shark 

It is a natural reaction to try and ‘skull drag’ fish into the boat when they are being chased down by attempting to reel it in as quickly as possible. Many fishers think burning the forearms and biceps is the way to go when sharks are lurking, but in reality, you are tipping the odds back in their favour.  

Sharks have 20-50m rapid bursts of speed, then fatigue quickly. Let the fish’s endurance work in your favour.  

Once your fish is in the clear and also starts experiencing fatigue, chase it down in your boat – then get it in quickly.

Sharks fatigue quickly and will attempt to attack fish using short bursts of energy. If your fish has a shark hot on its tail, flip your bail arm over on your reel to free spool your line and allow the fish to outswim the shark and tire it out.

Leave the burley bucket and bait at home 

Sure, bait and burley work well in attracting the fish to your hook, but those scents are picked up even more acutely by sharks.  

Lures, jigs and soft plastics are always better options in avoiding shark bite-off and oily baits such as mulies and burley will rapidly bring sharks into the area. Live-baits will also attract sharks close by.  

Avoid catch-and-release fishing  

If you have just spent a considerable amount of time pulling a demersal fish to the surface, it will be exhausted and if there are sharks in the area, it is highly unlikely that it will make it back to the bottom without being picked off.   

If you want to release a fish and improve its chances of avoiding awaiting jaws, swim the fish alongside the boat a fair distance away from where it was landed until it starts to kick.  

Hold your rod and have lures closer to the boat when trolling  

As soon as you hook a fish when trolling, you want to react as quickly as possible and create the smallest window of opportunity for sharks.  

Keeping a hand on the rod when trolling means anglers can react quicker and prevent the fish taking more line, reducing the fight time. Also, rather than trolling lures 30-50m from the back of your boat, try 15-20m instead as this will not decrease your odds of a hook-up while reducing the distance of the fish to the boat. 

When trolling, keep your hands on your rod and be ready to go in the event of a hook-up. Every second potentially counts!

Try drifting rather than anchoring  

While anchoring up can keep you locked on to your preferred spots, drifting helps you cover more ground and the sound of anchors grabbing on to structure is also known to bring in sharks.  

Keep your fishing depths to a minimum 

The deeper the water being fished, the more time you spend fighting the fish in order to bring it up to the surface. Try targeting demersals in the shallowest depths possible where they are known to roam.  

Catching coral trout in 10-15m of water will always have a better success rate of avoiding sharks than targeting them in depths of 40-50m. 

Stick to the shallower depths if you know this still produces quality fish. Greater depths mean a larger window of opportunity for sharks to take advantage of fighting fish.

Clean your fish on land rather than at sea 

Throwing the discards of your filleted fish back into the waters around your preferred fishing spots will only help accumulate more sharks in that area.  

Cleaning your fish on land for composting ensures sharks do not start gathering at popular fishing spots commonly frequented by boats. 

Try to avoid discarding fish remains out at sea near prime fishing locations and do this on land for composting. This helps in preventing sharks from congregating around spots frequented by boat fishers.

Tap into local knowledge 

If you are heading out for a fish and want to know where sharks have been highly active, simply pay a visit to your local tackle store and ask for tips. Not only do they know where the best fishing action is occurring, they can help increase your chances of avoiding shark bite-off, ensuring much more enjoyable fishing.  

Big thanks to Steve Riley – owner of Exmouth Tackle & Camping Supplies and the staff from Tackle World Exmouth for their tips.