What are the Odds?

Mick Fanning gets buzzed by a shark at the JBay Open last month.

There was a worldwide media frenzy after Mick Fanning’s high profile encounter with a shark in the finals of the 2015 J-Bay Open on 19 July. 1 Fanning was unharmed, but nearly three weeks earlier a recreational surfer and a bodysurfer survived "unprovoked" shark bites a day apart in Plettenberg Bay and Buffalo Bay in the southern Cape. 2

The incidents focused public attention on the risk of shark attack, but what are the actual risks, particularly to us in South Africa?

One often hears statistics on how rare shark attacks are. For example, the International Wildlife Museum in landlocked Tucson, Arizona, USA indicates that the "odds of being attacked and killed by a shark in a lifetime are 1 in 3,748,067. In a lifetime, you are more likely to die from fireworks (1 in 340,733), lightning (1 in 79,746), drowning (1 in 1,134), a car accident (1 in 84), stroke (1 in 24), or heart disease (1 in 5). There are 70 to 100 shark attacks worldwide every year, 5 to 15 result in death.” 3

However, these figures apply to your average American. They might give surfers, particularly those in California or Florida, a false sense of complacency.

Your average hillbilly has zero chance of dying from shark bite.

Public awareness of the low risk of a shark attack is reiterated among shark conservationists in South Africa. Recently, Alison Kock, the research manager at Shark Spotters in Cape Town, indicated the general point that the “probability of being bitten by a shark is statistically extremely low. There were 72 shark bites, three of them fatal, reported worldwide in 2014. Considering that hundreds of thousands of people use the ocean daily for recreation, this is a staggeringly low number.” 4

In turning to South African shark attack data, a different view of recreational ocean use risk can be noted. “Sometimes predicting or identifying risky situations is not possible and on average South Africa experiences four shark bites, two of them fatal, in a year. In some years there are no incidents at all; in others there have been up to eight.”

While numbers are important in determining risk, other contextual factors should be considered. Kock points out that if one is entering the ocean that they should “bear in mind that each location will be affected differently according to the species present, and its reason for being there, as well as your activity like swimming or surfing”. 5

This last point is important for determining the risk scenario to surfers. However, the general population and recreational ocean use statistics noted above do not give an accurate picture when assessing the risk to surfers — specifically as most fatal shark attacks involves surfers. 6

Of all unprovoked shark incidents worldwide, both fatal and non-fatal, 65% of these involve surfers. If the total surfing population of the world is estimated at 3 million, it makes up only 0.04% of the world. Furthermore, surfers only represent a small percentage of a country’s general population, of which the majority will never swim in the ocean. Their risk of a fatal shark attack is therefore zero.

Comparing surfer risk by country

A more appropriate means of calculating the risk of a shark attack to surfers is to determine country specific risk profiles, and then relate this to a known risk such as car accident deaths. This allows for a comparative view of surfer risk for an unprovoked fatal shark attack per country. For this exercise, data for three countries where shark attacks have received much recent attention are set out, namely: Australia, Reunion and South Africa (see Table below).

CountryPopulation
of country
in millionsSurfer
population
(7)Surfers:
fatal shark
attack in
last 10yrs
(8)Surfers:
fatal shark
attack (ave
in last 10yrs)Surfers:
risk of fatal
attack in
1 year
(9)Surfers:
relative risk
of fatal
attack in
one yearFatal car
accident:
risk in one
year
(10)Reunion0.8451,00060.71:1,66711:20,400South Africa5460,00060.61:100,000601:3,500Australia23196,00070.61:280,0001681:12,500

What can be deduced from these statistics?

1) The relative surfer risk of a fatal shark attack.

Reunion is used as the baseline for interpreting this data. The relative surfer risk of a fatal unprovoked shark attack in a year in South Africa is 60 times lower than in Reunion, while it is 194 times lower for surfers in Australia than those in Reunion.

2) Surfer risk of fatal car accident vs risk of fatal unprovoked shark attack

For a surfer in Australia the probability of dying in a car accident is 22 times higher than an unprovoked fatal shark attack. For a surfer in South Africa, the odds are 29 times higher of a fatal car accident than being killed in an unprovoked shark attack. Keep in mind that both shark and car accident risks are more than 3 times higher in South Africa compared to Australia.

3) Reunion surfer risk is highest

For the average surfer in Reunion Island (a French overseas territory) the probability of an unprovoked fatal shark attack is 12 times higher than dying in a car accident in France.

4) South African hardcore surfer risk of a fatal unprovoked shark attack is only slightly lower to the risk of a fatal car accident

While the average surfer, surfs only 22 times a year (every second weekend), a hardcore surfer could surf every single day, increasing the risk 17 times. We have 0.6 unprovoked fatal shark attacks on surfers on average in a year (in last 10 years) and only 60 000 surfers. On average there may be 3600 surfers in the water a day (assuming 22 sessions per surfer per year on average). Therefore, for a South African surfer that surfs every single day the risk is 0.6 in 3600, that is 1 in 6000 in a year. This is slightly lower compared to the risk of dying in a car accident which is 1 in 3,500 per year. For the average South Africa surfer who may surf once every 2 weeks, the risk is 0.6 in 60 000, that is 1 in 100,000 in a year. This is a low number, but not a staggeringly low number.

Mitigating surfer risk

The risk to South African surfers considered here justifies beach safety measures such as those implemented by the Shark Spotters programme in Cape Town. The continued investment by local government and support from the public for the Shark Spotters has gone far in providing measures that improves surfer safety, contributes to the shark conservation research, and does not harm the environment.

Author note:

Dr Pieter Streicher is an avid windsurfer and surfer. He has a PhD in Civil Engineering from the University of Cape Town and is managing director of the mobile messaging company BulkSMS.com, which provides ongoing sponsorship for the Shark Spotters programme – most recently in supporting the deployment of the Shark Spotter’s mobile App. He writes in his personal capacity.

Notes

1  See World Surf League media release, collation of some international new media, and social media comments titled “J-Bay Open – Surfer vs. Shark: Fanning’s Take”, World Surf League website, 19 July 2015 (updated on 4 August 2015), http://www.worldsurfleague.com/posts/131142/j-bay-open-called-off-for-day-after-shark-attack.  

 2 See articles on the NSRI website, http://www.nsri.org.za/2015/06/young-man-survives-shark-encounter/ and http://www.nsri.org.za/2015/06/surfer-suffers-leg-amputation-in-shark-encounter/. An unprovoked shark attack, which may or may not be fatal, is defined by the International Shark Attack File, managed by the Florida Museum of Natural History in the USA, as “incidents where an attack on a live human by a shark occurs in its natural habitat without human provocation of the shark.” International Shark Attack File, “ISAF 2014 Worldwide Shark Attack Summary,” http://www.flmnh.ufl.edu/fish/sharks/isaf/2014summary.html. The Global Shark Attack File compiled by the Shark Research Institute in Princeton, USA build on the above in explaining the situations in which incidents of shark attacks occur: “We know that a live human is rarely perceived as prey by a shark. Many incidents are motivated by curiosity, others may result when a shark perceives a human as a threat or competitor for a food source, and could be classed as "provoked" when examined from the shark's perspective,” http://www.sharkattackfile.net/incidentlog.htm. The Australian Shark Attack File, collated by the Taronga Zoo in Mosman, New South Wales, uses the following definition: “An ‘unprovoked’ encounter between a human and a shark is defined as an incident where a shark is in its natural habitat and has made a determined attempt to bite a human without any human provocation,” Australian Shark Attack File Annual Report Summary for 2015, 4 August 2015, https://taronga.org.au/conservation/conservation-science-research/australian-shark-attack-file/2015.

 3 See the International Wildlife Museum, http://www.thewildlifemuseum.org/exhibits/sharks/odds-of-a-shark-attack/.

 4 Alison Kock, “Shark safety tips: sorting out fact from fiction,” The Conversation, 4 August 2015.  https://theconversation.com/shark-safety-tips-sorting-out-fact-from-fiction-45169.  

 5 Expanding on these factors influencing risk, Kock lists the following, among others, in her article above: whether the type of shark encountered is a great white, bull/Zambezi shark, or tiger sharks; the location of ocean use is at a beach near to a seal colony, at or near a river mouth, in an area with sewage outfalls, or in deeper water beyond the surf zone; factors determined by seasonality such as shark migration routes or inshore activity, the presence of bait fish (such as the sardine run), or heavy rains and flooding; whether surface water visibility is low due to murkiness; the time of day , especially dawn or dusk; and if a person is swimming, diving or surfing on their own.

 6 See International Shark Attack File, “ISAF 2014 Worldwide Shark Attack Summary,” http://www.flmnh.ufl.edu/fish/sharks/isaf/2014summary.html.  

 7 For surf population estimates are difficult to determine due to industry and organised surfing’s interests in inflating participation in the sport. The surfer statistic here are from the Australian Bureau of Statistics, Participation in Sport and Physical Recreation, Australia, 2013-14 (February 2015), Table 2, http://www.abs.gov.au/AUSSTATS/abs@.nsf/DetailsPage/4177.02013-14?OpenDocument; for Reunion, the estimate is drawn from French Surfing Federation, “French Surfing Federation on Reunion Island shark crisis,” (April 2015) http://www.surfingfrance.com/disciplines/surf/french-surfing-federation-on-reunion-island-shark-crisis.html; and the estimate for South Africa based on a figure published in Steve Pike, Surfing South Africa, (Cape Town: Double Storey, 2007).

 8 This data is taken from Shark Attack Data (www.sharkattackdata.com) which has organised data based on the Global Shark Attack File (www.sharkattackfile.net).

 9 This risk ratio is based on the assumption of an average of 22 surf sessions per year per surfer. This would probably account for most recreational surfers who surf every second weekend. The risk for a hardcore surfer, who surfs during the week and on weekends, or every day, would be significantly higher than a recreational surfer’s risk. The risk for beginner surfers, for their first few lessons, would be significantly lower than a recreational surfer’s risk.

10 These statistics are drawn from “List of countries by traffic-related death rate”, Wikipedia, https://en.wikipedia.org/wiki/List_of_countries_by_traffic-related_death_rate [accessed 7 August 2015]. Reunion’s data is reported within France’s. Data is most drawn from World Health Organisation (ed) "Global Status Report on Road Safety 2013: supporting a decade of action". Geneva, Switzerland: World Health Organisation (2013), as well as country specific reporting.