THIS is the final installment of Solomon Franklyn’s investigation into WA’s shark management systems. In it, he looks into the intriguing behaviour of sharks when one is killed – and is there a way we can tap into that to make our beaches safer for swimmers?

OVER this series of articles, I have laid out three significant findings regarding shark management and the public’s perception of the issue. 

Those being: that fear of sharks is influencing ocean-use habits across Western Australia; that the public supports further shark mitigation provided shark conservation remains a priority; and that the previous SMART drumline trial was poorly suited to WA’s environment and lacked several features that make these systems effective. 

The question now becomes: what should come next? 

I propose that WA re-trial SMART drumlines, alongside further investigation into a new shark mitigation system that could provide the missing piece in our search for a solution. 

These may not necessarily be the most effective systems available, but they align with what the public is calling for, making them among the most realistic options for gaining public support and ultimately being trialled or implemented. 

People often view the subject of shark management as holding two competing objectives. 

Nil harm to sharks at the expense of humans, versus nil harm to humans at the expense of sharks. But what if there was a way that could do both? 

In South Africa at one of the Great Whites’ key aggregation spots, a pair of killer whales killed multiple White sharks, leaving their carcasses in the water. 

Almost as soon as these deaths started happening, sightings of Great Whites ceased, and those tagged were tracked fleeing the area. 

Following this incident, shark sightings remained unusually low for the next two years. 

This same pattern of behaviour was also seen off Neptune Island in South Australia, as well as in multiple other studies. 

What made the actions of these sharks following the death of one of their own so interesting was the reason behind their unusual behaviour. 

It is true that some of the sharks were likely leaving due to the appearance of a new predator, but there is another key factor contributing to this, necromones. 

These are oils released from a dead shark’s body that are essentially chemical distress signals; when another shark of that species smells these, they get a warning that there is a predator in that area that has been killing sharks of their species. 

Hence why sharks were seen leaving these areas post-attack even if they hadn’t encountered the predator at hand. 

Many experts believe that the effectiveness of mesh nets may be partly attributed to the death of sharks caught in them, which releases necromones that deter other sharks from approaching the area. 

That might be seen in NSW where, since the implementation of the nets after 1937, one fatality has occurred at these netted beaches. 

The significant downside to the NSW net strategy, however, is the large amount of marine death and by-catch. 

What I am proposing is that these necromones be further researched.

If we got to the point where scientists could replicate these oils, then who’s to say we couldn’t have them sitting in buoys out from our beaches, creating an invisible safety net. 

As well as this I propose that SMART drumlines should be re-implemented in Western Australia.

This time, drumlines should be managed in a way that suits our environment. 

With the hooks placed at the correct depth (8-15m below the surface), with bait that attracts Great Whites of all ages (tuna) and lastly positioned in known shark transit routes. 

Together these strategies could enhance shark conservation and improve human safety. 

When it comes to shark management these policies tick both boxes. 

So, perhaps this presents as an opportunity for the West Australian government to implement real changes. 

The current management systems we have in place hold shark conservation at the forefront, however they do little to increase safety to humans and in cases where they do (enclosed nets), it is only in a small space. 

These management strategies clearly don’t seem to be doing enough regarding human safety so why is it that nothing further is being trialled and/or implemented, especially when we are seeing our neighbouring states acting on similar issues. 

An example of this is the current saltwater crocodile management plan in the NT.

Saltwater crocodiles were affecting tourism, visitors, and locals, so a 10-year management plan to cull 1200 crocodiles per year in hope of bringing safety to the people was implemented. 

Not that different to our situation, is it? 

It might also be noted that saltwater crocodiles have been responsible for 19 deaths since 1969 in the NT, compared to WA’s 24 fatal shark attacks since 1971. 

So, what is the difference between WA and the NT? Why the lack of appetite by the West 

Australian government to genuinely explore shark management that increases safety for humans? 

How many deaths will it take, how much must our enjoyment of the ocean be affected, 

 and how far must our engagement with oceans and beaches decline before action is taken? 

I believe there is an approach out there that can fit WA’s needs, both for the public and the marine life. The most important thing is to just keep searching and testing until we find a solution that is suited to all.