Tags increase sharks’ appetite for humans, says vet
BALLINA animal rights activist and veterinarian Dr (Captain) Peter Kerkenezov has called for a review of the current practices of large shark tagging, claiming tag transmitter frequency only increases their appetite for humans.
The former mariner believes if a tagged shark emitting unique acoustic beeps at 69kHz was readily detected by man-made receivers, it followed that any animal with a hearing range within the frequency will pick up a tagged shark's presence.
"In areas such as Ballina where there are no pinnipeds, the white sharks longer than 3.5m length depend on dolphins, whales and large fish. The 69kHz frequency emission from implanted white sharks sits in the middle of the hearing range of dolphins, so a shark's presence is now easily detected.
"The dolphins may now adopt a silent mode to avoid predation. A hungry shark likely becomes a dangerous shark. That is, until it becomes sick and dies from surgical complications or detected and killed by its only ocean predator, the killer whale."
A spokesperson from Department of Primary Industries, however, has refuted the local vet's claims.
"There is no scientific evidence to suggest that the 69kHz frequency interferes with marine life and 69kHz is not an adverse sound to marine mammals," the spokesperson said.
"This frequency is universally standard and used on thousands of tagged aquatic animals (sharks, fishes, invertebrates) around the world."
Dr Kerkenezov was also concerned over reports that just one of 222 great white sharks being tracked by satellite-linked receiver buoys off the coast of Western Australia had been detected in the first two months of this summer.
He believes that the tagging could be causing long-term distress and changing the sharks' natural behaviour, even causing death.
"It seems mortality and morbidity data is unavailable and if institutions do have such data then it should be made available," he said.
"There is no real idea of how many of these sharks will die as a consequence of wound infection, or other complications after release."
The DPI refuted the Dr Kerkenezov's claims that the surgical tagging was inhumane.
"Many thousands of aquatic animals have been tagged using this procedure, each project around the world being endorsed through various ethics committees that include veterinary specialists," the DPI spokesperson said.