Are Shark Attacks on the Rise?
2020 saw a total of 7 fatal shark attacks in Australia – the highest number on record since 1929 [1-3]. On average, there are 20 reported shark attacks in Australia every year, with less than 1 proving fatal .
Public fear of sharks has been provoked by scientists and media alike, beginning with the classification of white sharks as ‘man-eaters’ when they were first described in 1758 . False statements made by scientists have fed public fascination with mean-eating sharks and are the underlying basis for films like ‘Jaws’. Such imaginary representations of shark attacks have blurred the lines between fact and fiction and left the public with little information as to how dangerous sharks really are .
The high number of shark-related fatalities seen in Australia last year may leave people believing they have the information necessary to label sharks as ‘dangerous’. But if this is inaccurate, then what is responsible for the increase in fatalities?
To understand this, we first need to understand why shark attacks happen.
Why do sharks bite?
Shark attacks are generally categorised as either ‘provoked’ or ‘unprovoked’ [4-5]. Unprovoked attacks receive the most attention and are defined as: “a bite or near bite (fended off by human intervention) of a person (or the board on which he/she is perched) in the shark’s natural environment in the absence of any human provocation” . Examples of provocation generally include behaviours like spearing sharks, attempting to ride them, hooking them and dragging them onto boats. Swimmers passing very close to sharks that are otherwise ignoring their presence is also sometimes defined as provocation, however this is contested .
It is fairly obvious why a shark may bite or attack a human in many of these instances, however the reasons for unprovoked attacks are less clear and are still under debate [1,4]. Some research has implicated factors such as random opportunity, interference with reproductive activity and defence against threat, competition or violation of the shark’s space . This contradicts previous theories that shark bites are linked to feeding activity and instead suggests that the main drivers are aggression, sex and fear . Sharks also employ ‘bite-and-spit’ behaviour, which may explain why shark-related fatalities are relatively rare when humans are mistaken for prey such as seals (especially while surfing) .
So if most shark attacks are unprovoked, how is it that Australia saw so many last year?
Why are shark attacks increasing?
One of the most influential factors in determining the occurrence of shark attacks is simply the number of humans there are [6-7]. Not only are our populations increasing, but in Australia more people are undertaking water-based activities such as swimming and SCUBA diving [6-7]. Naturally, this increases the likelihood of coming into contact with a shark.
Although this is an important factor, beach attendance alone is insufficient to explain the observed increases in shark attacks [6-7]. In Western Australia the recovery of important prey species such as the humpback whale and New Zealand fur seal could be changing habitat usage by large shark species . In Southern Australia, weather patterns could be making the conditions preferable for these sharks, as the ‘shark attack season’ described by Baldridge (1974) is when waters are warm enough for human swimmers but below around 30°C when it becomes too hot for sharks [4-7].
A factor rarely mentioned is human interference. Alterations to sea surface temperature, freshwater runoff, turbidity and the circulation of water will all have significant impacts on animal physiology, as well as on their habitat use and distributions along the coast . Habitat use can also be altered by climate change as many large shark species undergo seasonal migrations, the patterns of which may change with environmental cues like weather patterns .
It is likely that the interaction between multiple variables is responsible for the reports from Australia in 2020, however disentangling these factors from one another is complex.
This begs the question: if we cannot understand why unprovoked shark attacks happen, then should we be afraid of them or not?
How afraid should we really be of sharks?
As the number of shark attacks increase, it can be assumed that so will the number of shark-related fatalities, however the severity of shark bites is unpredictable because of many interacting factors. For example, the remoteness of the location increases the likelihood of a shark attack proving fatal due to increased distance from emergency services . Attack severity is currently underrepresented in the literature and further study is needed in order to properly disentangle the factors involved.
Sharks are top predators that are both well-evolved and little-understood, and they evidently can pose a risk to human wellbeing. However, caution must be taken when terms such as ‘man-eaters’ are widely used by both the scientific community and the media.
Shark-prevention methods such as nets and baited lines have been employed widely for the past 80 years; often implemented by policymakers’ knee-jerk decisions in response to immense public fear [4,8]. However, people are becoming more aware of the endangered status of many shark species and the non-target animals that are killed as a result of these (often ineffective) preventative methods [6,8].
Reports of shark attacks can often be misinterpreted. For example, shark bites on kayaks or surfboards are reported as ‘attacks’ even if no humans are injured, and so we must take care when interpreting the information we are presented with . Snap-decision making intended to protect public wellbeing could end up spelling disaster for endangered shark species, which in turn will have unprecedented impacts on the functioning of both animal and human ecosystems .
Despite this, more people are beginning to appreciate and respect large creatures like sharks and accept the level of risk that comes with entering a species’ natural environment, offering hope to these incredible creatures.
1. Mao F. Is Australia really seeing more shark attacks? [Internet]. BBC News. 2021 [cited 21 February 2021]. Available from: https://www.bbc.co.uk/news/world-australia-54112992?fbclid=IwAR0OWG--d4_7NwXrzAPbC8NtuGb_a8LrkRXwQexj5zpCkNZbvp5wFesDq1Y
2. Barron J. Fisherman's wild reaction after being stalked by great white shark [Internet]. Mail Online. 2021 [cited 21 February 2021]. Available from: https://www.dailymail.co.uk/news/article-8855221/Fishermans-priceless-reaction-stalked-huge-great-white-shark-coast-Australia.html?fbclid=IwAR3ERPMSpSHiQPlNW9xLcLF2MfCaKnvMGFrKKWLgn1G0viQyigG0hvw2ZrI
3. Lackey B. Spearfisher spots a great white shark at Sydney's tourist beach [Internet]. Mail Online. 2021 [cited 21 February 2021]. Available from: https://www.dailymail.co.uk/news/article-8857695/Spearfisher-spots-great-white-shark-water-just-metres-Sydneys-tourist-beach.html?fbclid=IwAR103bh65XrC4jWeTavfpPTigCu_lJ35AfI4q4pliR49GrLw3DuLsgxg9yQ
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6. Chapman B, McPhee D. Global shark attack hotspots: Identifying underlying factors behind increased unprovoked shark bite incidence. Ocean & Coastal Management. 2016;133:72-84.
7. West J. Changing patterns of shark attacks in Australian waters. Marine and Freshwater Research. 2011;62(6):744.
8. Paterson R. Effects of long-term anti-shark measures on target and non-target species in Queensland, Australia. Biological Conservation. 1990;52(2):147-159.