IN THE NEWS: On FEB 7, 2016
SHARK attack survivors want authorities to test whether shark tags could be contributing to attacks on people, after a WA study found the acoustic tags affect the animals' ability to feed.
The scientific research paper by the state's leading acoustic experts calls into question multimillion-dollar shark tagging programs set up in response to fatal attacks and funded by the Barnett Government, the WA Department of Fisheries and the CSIRO.
A tagged shark was confirmed as one of two animals that mauled surfer Sean Pollard, who lost both hands in an attack as he surfed near Esperance last year.
It was one of more than 200 great whites fitted with internal or external acoustic devices that have a battery life of up to 10 years and work by sending out bursts of ultrasonic sound at a frequency of 69 kilohertz, identifying individual sharks when they pass a receiver.
But the new study – being peer-reviewed now and produced by Curtin University Centre for Marine Science and Technology researchers Kim Allen, Dr Christine Erbe and Dr Miles Parsons in collaboration with Dr Rob Williams, a researcher for the Oceans Initiative – examines whether the acoustic devices could have a "cat collar" effect.
Like a cat bell that warns birds of a predator, the frequency emitted by shark tags could warn marine mammal prey when a shark is in the area, according to the research paper titled Aquatic animal telemetry: A powerful tool with potentially serious side effects.
The frequency could also have a "dinner bell" effect, attracting predators such as killer whales.
- it was unclear "how many species of predators or prey may detect tags and how often we may safely ignore this issue".
- that "prey may receive an early warning of the predator" and that an almost identical frequency is used in a device that is available on the market to deter dolphins – common prey for sharks.
- that future tagging programs should "consider the potential for acoustic tag detection by the tagged animal as well as other fauna in its habitat".
However, it cautioned that sharks also scavenge for food and only a small proportion of a shark's prey is likely to hear the most common tag frequencies.
David Pearson, a shark attack survivor who founded Bite Club to help other survivors and their families, said the study raised questions about the unintended consequences of tagging.
"Sharks love to eat dolphins and if a dolphin can hear a shark coming, you've got to wonder what the consequences of that are," he said.
Mr Pearson said he "often wondered" if a tagged shark tracked off Crowdy Head in NSW on the same day as his attack at the same beach in 2011 was that one that bit him.
Abalone diver and former marine scientist Peter Stephenson – who has lost several friends to shark attacks – said authorities were playing a "game of Russian roulette" with acoustic tags.
"These government-sanctioned scientists are tagging sharks without a full understanding of the effects that these devices and the tagging process have on shark behaviour and welfare," he said.
Sharon Burden, the mother of WA fatal shark attack victim Kyle Burden, said there were "big implications" if tags were affecting the feeding habits of sharks and she said "we may need to be flexible and find even better ways" to study the animals.
Shark attack survivor David Pickering, who has lifelong arm injuries after a bite from a tiger shark at Coral Bay in 2012, agreed more research was needed.
Mr Allen, the study's principal author, said his personal opinion was that there should be "more attention paid to the practice of attaching and implanting electronic devices on to or into large apex predators in proximity to popular beaches".
"We don't fully understand what all the complications could be," he said.
Most tags used in WA are produced by Vemco and spokeswoman Denise King said the Canadian marine company was "aware of some lab-based studies" suggesting tags affected feeding habits but was "sceptical that this would translate into the wild due to the low output power and infrequent nature of the tag transmissions".
The attack on Mr Pollard is the only one confirmed by a tagged shark.
Fisheries Department executive director of research Dr Rick Fletcher said from the available data, shark tags appeared to have "no obvious impact on feeding success".