Shark senses, and the development & testing of shark repellants – UWA. Part 2.

Following on from last week’s post, and just to recap, I was lucky enough to be invited to attend a seminar on ground breaking research into shark sensory perception and how they were developing and testing shark repellants. You’ll need to read the previous post to get a bit of background so we can understand how and why the following devices show promise.

 

Chemical repellants against sharks

Nathan spoke on the use of chemical repellants that would be detected by the olfactory system (sense of smell) of sharks. What they found was that sharks were repelled by the essense of dead shark, special slime produced by the sole fish and sea cucumber and also, some common household detergents. Good news? Yes, in a way. But testing showed that these were impractical because diffusion of the chemical stimuli is too slow, and in the field where there is water current, these smells would not stay put.

 

Accoustic shark deterrents

It is known that sharks can hear low frequency sounds and are attracted to them. Research showed that they do not like loud sounds. But with time, they become habituated to it (used to it) and so they will return. So, loud sounds don’t really work in the long term. They were planning on trialling whale sounds. Not the relaxation ones people use for meditation, but ones from the predatory killer whales (OK, before you kick me, I know they are not considered true whales). They did talk about the theory of neophobia (fear of new things). Here they tried electronic sounds like from the Star Wars’ R2D2 which seemed to repel sharks. What also seemed to work was songs from ACDC! Sharks are no fans of the heavy metal music (frankly, I don’t blame them).

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Visual protection against sharks

Sharks are attracted to yellow and silver, and they tend to investigate objects sporting these colours. They have found that low contrast material work as camouflage. For divers, they trialled 3 different shades of blue with patterns to break up the silhouette and they found it worked. They also trialed novel, unpleasant visual stimuli like very bright flashing lights which seemed to work. There is also the theory of biomimicry, having contrasting black and white stripes to imitate venemous sea snakes.

 

Electric deterrent system

Some products are being marketed as “shark shields”. These are electric deterrent systems and they do appear to be effective. There is promise for it to be used to protect swimming areas, and as a personal-based device. But more research needs to be done to know what are their limitations. Does it matter what species of shark, shark size, will it work with multiple sharks and will sharks become habituated?

 

But the most simple, and most promising thing researchers have found is….

…. in my blog post next week 🙂

 

 

 

 

 

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3 thoughts on “Shark senses, and the development & testing of shark repellants – UWA. Part 2.

  1. First it should be acknowledged that from the moratorium on white shark mortality of the mid 1990’s white shark attacks were expected to increase including in WA and look what has happened. No different to the situation with crocodiles in northern Australia which funnily enough has not entered into the shark debate.
    The moratorium on white shark mortality was considered by most scientists would to lead to a stock increase that would lead to increased shark attacks. That situation was either applauded or condemned by the Australian./ most State administrative and research people involved depending on whether they derived their research grants from enhancing shark numbers or not. Situation normal.
    The incredibly low level of fishing at tight controlled sites in Queenslands shark programme served as a low but representative index of white shark abundance. Queensland also had a period when white sharks were not being landed but it turned out not to be due to a lack of sharks but to the increasing size of white sharks that the gear could not cope with. Queensland corrected that situation. WA Fisheries was informed but did not make the changes which may have been in part why some white sharks were not landed in the restricted fishing programme.
    There has been an extremely low level of deliberate and accidental acoustic investigation into shark behaviour over the past few decades with marginal government support. It was more about correction of electronic components of acoustic devices utilised for other purposes that were directly related to changes in shark catch rates.
    All states would be further down the track of shark attack mitigation if it had been addressed decades earlier. It is good its happening now and there will be ups and downs and commentators should not go off on tangents derailing the work as it proceeds and if the end result does not suit them.

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      1. I was there and involved and I can only say what happened not what people think might have happened.
        I cant recall politics being involved in any shape or form on the committee, .save the machinations of individual scientists.

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