Shark repellents may not work on most deadly: research
Courtney TrenwithApril 25, 2012
The recent work with shark embryos at UWA continues to help develop repelling devices for different shark species. Photo: Ryan Kempster
Existing shark repellents may be less effective for the three most deadly species, new Western Australian research suggests.
University of WA Winthrop Professor Shaun Collins said recent work to better understand shark sensory systems, including visual and electroreception, had revealed differences in how various species use their senses under different conditions.
The findings by UWA's Oceans Institute suggest that developing repellents that targeted specific shark species would be more effective than using a one-size-fits-all approach.
The world-leading discovery follows four fatal shark attacks in WA in the past year.
Most recently, father-of-two Peter Kurmann was attacked off Busselton Beach on March 31. Scientists believe the shark responsible was a great white.
In October, a shark attack claimed the life of American tourist George Thomas Wainwright, 32, after he was mauled while diving alone 500 metres north-west of Rottnest's Little Armstrong Bay.
Earlier that month, 64-year-old businessman Bryn Martin disappeared while swimming at Perth's popular Cottesloe Beach, and is believed to have been taken by a shark.
Only Mr Martin's bathing suit which had fabric tears consistent with that of a three metre great white shark could be recovered.
In September, 21-year-old bodyboarder Kyle Burden was killed near Bunker Bay in the state's South West by a 4.5 metre shark.
The state government responded to increased public angst in relation to the spate of attacks and announced $13.65 million in funding over five years for shark-related projects, including a $2 million Shark Response Unit, which would assess the effectiveness of technologies such as shark repellent devices, among other things.
The most common repellent on the market is a shark shield, usually attached to a diver's tank, which emits a high level electric current to deter sharks and is usually effective for a few metres.
"Sharks have this series of small pores over their head which pick up weak electric fields in the water," Professor Collins said.
"[The electric fields] are produced by anything living or anything with an electric current in it. All of its prey items produce some sort of electric field and [the sharks] use it to hone in at short range to find something to eat.
"The repellents that are currently on the market upset this electric system by producing a really strong electric field which the animals don't like so when they get quite near the divers, sharks, or at least some species, are deterred and they'll swim away.
"From our research, we know that every species is different and that it's probably that some species won't be repelled or deterred as well as others."
Professor Collins said the findings opened up opportunities to develop new, species-specific repellents, which may target the sharks' other senses such as light, sound or smell.
There also was scope to develop a device to protect larger areas, such as an entire beach.
"They really are masters of detecting their surroundings," Professor Collins said.
"Every species is different and the implications from that are that if you have got a device it may deter some but not others."
Professor Collins said the three most deadly sharks - great white, tiger and bull - which accounted for majority of all fatal attacks, may be undeterred by existing repellents.
His work would concentrate on better understanding those species and developing repellents for them.
The institute is seeking about $500,000 over three years to get to the testing stage.
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