I have been doing a lot of research on shark risk reduction for recent media, so here is the latest information as I found it – please read as information and do all the research you personally need before making any decisions about your safety – there are links below and within to help you research further.
Happy Squid’s Summary of Available Information of Shark Interaction Risk Reduction
Sharks are wild animals and should always be treated with caution and respect like any other wild animal. To date, there is no technology or strategy that can completely remove the risk of a shark bite. There remains much doubt and conjecture about many aspects of shark behavior, but there are also some patterns and we are learning more every day.
These are activities that are known to significantly increase the risk of a shark attack and the risk should be considered before undertaking these activities:
Spear fishing, underwater hunting, and particularly carrying dead fish are a significant risk factor both because these activities have a significant effect on shark behavior and because they can attract nearby sharks. Carrying dead/dying fish on or near the body is a particular concern. The Australian Shark Attack File considers an attack whilst spear fishing a ‘provoked’ attack.
Burley, fish, whale carcasses or animal waste
Burley, fish or animal waste in the water is likely to attract any sharks in the area and increase the risk of predatory behavior that may lead to bites. Whale carcasses are particularly likely to attract large sharks. Fishermen should also be mindful of other ocean users before burleying up the water.
Things to consider from the research:
In the past two decades 91% of shark attacks have occurred away from major population centers.
White sharks are much more likely to be present in water under 20 degrees Celsius, and less likely to be present in water over 22 degrees Celsius. Tiger sharks and bull sharks are generally more commonly found in warmer more tropical waters.
Patrol helicopters or the local surf, dive or beach community often reports large shark sightings. White Sharks are responsible for most fatalities in WA and they are highly migratory, so if there is a large shark reported in your local waters consider taking note and adjusting your behavior until it’s gone. Report any sightings to the Water Police so the community can be notified via Surf Lifesaving Australia and beaches can be closed if necessary and also to Shark Alarm website which is being very successful in sharing information about shark movements.
Seals and other ocean wildlife
Be aware that according to the Australian shark attack file, 89% of severe injuries and fatalities come from swimming, surfing or diving near seals or seal colonies. Being in the water amongst large schools of schooling fish, dolphins or seals can increase the risk of shark interaction. A WA Department of Fisheries correlation study found that there wasn’t evidence in WA of attacks being concentrated around seal colonies, but still recommend caution given white sharks are known to feed in these areas.
Shark Repellant Devices
Shark repellant devices have the potential to reduce the risk of shark attacks. The technology is still in its infancy with more research required.
Two independent studies have been conducted on the most common of the shelf device in WA, Shark Shield. One concluded the SharkPOD™ product reduced the probability of an attack from 0.7 to 0.08. Another on the Freedom7™ found that the product did alter the predatory behavior of white sharks but didn’t deter or repel all sharks in all situations. There are many anecdotal reports and videos available online of Shark Shield repelling sharks with some people attributing the product to saving their lives. Such reports are interesting and useful but also need to be carefully considered as there isn’t always evidence that the device was the reason for the sharks behavior change, although it seems likely it was in at least some instances. Be aware of the research when watching these (read it for yourself via links at the end of this blog).
Other promising research is being conducted on using other senses to repel sharks, such as smell, visual and noise. The University of Western Australia is undertaking research in this area. The Support Our Sharks website has further information on shark repellant research written by a shark scientist.
Cloudy Water, Deep Channels and Drop Offs
All these factors are considered to increase the risk of a shark bite or attack.
Distance from Shore and Water Depth
A correlation study by the WA Department of Fisheries found that most white shark attacks occur more than 30m from shore. The same study found that risk is lower in water depths less than 5m.
Time of year
On Western Australia’s West Coast, white sharks that are responsible for most fatal attacks in WA are significantly more active in winter and spring, and less active in summer and autumn.
Know your sharks
If you see a shark, it may or may not be dangerous. If you are unsure, calmly leave the water and avoid excessive splashing or noise. Generally, sharks under 2m have not been implicated in fatalities in Australia but have bitten people. Swimming with Grey Nurse sharks, whale sharks and Port Jackson sharks can generally be considered safer under most circumstances. Whalers and wobbygongs have been known to bite and should be treated with caution. Juvenile white sharks are known to be mistaken as whaler sharks. Tiger sharks, bull sharks and white sharks, especially those over two meters, should be considered a risk as they are most likely to bite and if they do, to cause fatal injuries.
Diving or swimming in a group
Sharks are less likely to approach a large group of divers or swimmers, such as on a charter vessel. There is only one reported white shark sighting from a dive charter in Western Australia after decades of diving involving hundreds of thousands of dives and this did not result in a bite or close interaction.
Swimming between the Flags
Swimming between the flags at a patrolled beach with aerial surveillance significantly reduces the already low risk of a shark attack. Helicopter aerial surveillance by Surf Life Saving WA runs for 198 days weather permitting for metropolitan Perth beaches with sweeps of Rottnest. From late November to the end of January a patrol operates from Bunbury to Margaret River. This risk is lower again in summer and autumn in water depths less than 5m and less than 30m from shore.
The Australian Shark Attack File records that in 54 incidents where the victim sought to deter the attacking shark, in 37 the shark gave up the attack. Methods used by victims were hitting, punching, kicking, eye gouging, grabbing fins or using spear guns, surfboards or other objects to push into the shark’s mouth.
Which Activities Are Most Risky?
Of attacks considered as ‘unprovoked’, so not including circumstances where the person involved was fishing for, spearing, stabling, feeding, netting or handling a shark, or where the shark was attracted to the victim by activities such as fishing, spear-fishing or cleaning captured fish, the following activities recorded shark interactions up to 2011:
‘Sharky Weather’ – Myth or Real?
A WA Department of Fisheries Correlation study made some findings that will remain contentious with many ocean users by going against surfing and diving ‘folk lore’.
They found that there was no correlation with time of day, air temperature or weather conditions – going against the typical theories of avoiding dawn and dusk, or overcast ‘sharky’ weather. West (2011) – see references below – also seeks to debunk the dawn and dusk theory but doesn’t discuss weather conditions.
I’ve not seen in my reading any science based evidence of weather or time of day influencing the risk of shark attack; however, I’m leaving it at saying I think the jury is out on ‘sharky’ weather and the relative risks of swimming at dawn and dusk.
References / recommended reading
West, 2011, Changing patterns of shark attacks in Australian waters
McPhee, D.P. (2012) Likely Effectiveness of Netting or Other Capture Programs as a Shark Hazard Mitigation Strategy under Western Australian Conditions
White Shark Recovery Plan, 2002. Commonwealth of Australia.
Support Our Sharks
WA Department of Fisheries
Shark Safety Webpage
A correlation study of the potential risk factors associated with white shark attacks in
Western Australian waters, November 2012, http://www.fish.wa.gov.au/Documents/occasi onal_publications/fop109.pdf