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).
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 🙂