In response to the tragic death of 32-year-old American George Thomas Wainwright last Saturday, the Western Australian Government has given the go-ahead for any great white sharks to be killed if they pose a threat to human life.While the seems on the surface to be at best a knee-jerk reaction, at worst an attempt at political appeasement of infantile revenge seekers, I wondered if there was actually any merit to this literal plan of attack. Is there any evidence killing the shark will reduce attacks? Is there any evidence that shark numbers are increasing in the area (remembering that the plural of anecdote is not, and never has been evidence), and is there any evidence that killing these sharks is a really bad idea?
As my specialities are more land based, let’s see what the experts have to say:
The recent deaths attributed to the great white shark attacks in WA are most distressing and a terrible loss for the families of the victims. However, the culling of any species of sharks is not the solution. Not only will this be indiscriminate killing of a protected Australian species (under both the EPBC Act and state legislation), there is no way of being sure the sharks caught will be those responsible for the attacks. At present, there is no data to suggest that shark numbers are increasing off WA’s coastline and shark attacks in Australia have remained relatively constant over time, occurring at a rate of approximately one per year for the last 50 years. Sharks are apex predators and they play a critical role in the complex balance of oceanic ecosystems and their removal can have major impacts on other marine species. Education and surveillance are the best prevention of human fatalities off the WA coast until better repellent devices are developed. Non-lethal shark protection measures such as spotter planes and patrol boats should substantially improve the ability to identify large sharks and enable swimmers and divers to avoid them. Australia (and especially WA) has one of the highest levels of biodiversity in the world. Culling sharks will upset the important role these apex predators play. Our Neuroecology Laboratory at The University of Western Australia is currently working on various methods to repel sharks based on their battery of senses.”
Prof Shaun Collin is WA Premiers Research Fellow and Professor of Neuroecology in the School of Animal Biology and UWA Oceans Institute at the University of Western Australia
There is no scientific evidence to suggest that the short time period between the recent attacks is a reflection of an increased population size of white sharks. It could simply be related to the seasonal fluctuation of the number of white sharks within specific areas and that white sharks might naturally be more often occurring around the populated Western Australian coastline at this time of the year. Unfortunately, we currently have no reliable measure of the population size of white sharks. However, we do have some evidence of large variations in the number of white sharks from year to year within specific locations such as the Neptune Islands off South Australia. A below average number of white sharks one year does not necessarily mean that the white shark population is decreasing. Similarly, an above than average number of white sharks the following year does not necessarily mean that the white shark population has dramatically increased compared to the previous year. It is more likely dependent on the distribution of white sharks and the various and complex factors influencing the movements and migrations of these sharks.”
Dr. Charlie Huveneers is a Shark Ecologist within the Marine Environment and Ecology Program at the South Australian Research and Development Institute (SARDI Aquatic Sciences)
For further reading on this topic I recommend the following blog by fellow Griffith student, Ryan Pearson: The World…in plain english.
Also there is currently a petition here calling for an end to shark culling. I’ve signed it, have you?