Popular shark myths, misconceptions and factoids
During this inquiry, various beliefs about how shark behaviour and the
causes of shark bite incidents were discussed. Some of these have gained a
degree of acceptance in the community; however, they are not supported by
expert evidence. One of the major challenges in ensuring accurate information
about sharks is the acceptance of correlation implying causation. That is,
increases or decreases in human–shark encounters in particular areas are
attributed to changes in some other variable, such as whale migration or the
presence of shark nets, without scientific evidence demonstrating a link
between the two changes.
It can be difficult to disprove and dispel some of the myths and
misconceptions that exist. There are significant challenges in conducting shark
research about human–shark interactions. It is also generally accepted that
there is a need for further research to improve understanding about shark populations,
behaviour, movement and breeding patterns. The difficulties associated with
obtaining and disseminating reliable scientific evidence are in stark contrast
to the ease in which incorrect information can spread, gain credence and become
accepted as fact. For example, it has been argued that incorrect
information about shark behaviour shown in the blockbuster film Jaws,
in which a terrifying monster targets humans at a particular location, has
shaped people's attitudes towards sharks.
This appendix provides a selection of myths and misconceptions about
sharks and shark bites, followed by evidence received during this inquiry that
responds to them.
Questioning and challenging widely held beliefs about sharks is important for
evidence-based policy, particularly as it is evident that many of these myths
and misconceptions influence how interested individuals (and governments)
approach the debate on shark mitigation and deterrent measures.
All sharks are dangerous
Although around 180 species of sharks can be found in Australian waters,
the available data indicate that the overwhelming majority of shark bites
in Australia, including 99 per cent of fatalities, can be attributed to the
following three species:
white sharks (Carcharodon carcharias);
tiger sharks (Galeocerdo cuvier); and
bull sharks (Carcharhinus leucas).
The shark population has 'exploded'
That the number of sharks in Australian waters has increased
significantly was put forward by many individuals who contributed to this
Unfortunately, reliable data on shark populations is not available,
although there is work underway by CSIRO to develop an estimate of white shark
abundance. Nevertheless, due to what is known about sharks, shark experts
consider it highly unlikely that the population could have dramatically increased.
For example, Professor Jessica Meeuwig explained that white sharks only
start reproducing between 17–20 years of age and 'have one or two offspring
every couple years'. The professor emphasised that white sharks 'are just not
capable of rapid rebound like a herring or a pilchard'.
Professor Nic Bax, a senior principal research scientist at CSIRO told
the committee that, with respect to the white shark population, 'it would be
hard to imagine that their growth rate could be more than about four per cent a
Experts suggested that the perception of an increasing shark population
could be explained by a greater number of people being in the water resulting
in a higher number of observations.
Potentially, a larger number of sharks could be approaching the coast due to
changes in the distribution of their prey.
Sharks target humans as prey
As the Department of the Environment and Energy explains on its website,
the current understanding of shark species known to be dangerous to humans is
that these sharks do not target humans as prey. The majority of human–shark
encounters that occur are instead because the shark confuses the person with
its normal prey.
It was noted that 'sharks are inquisitive (and opportunistic) animals,
and will investigate almost anything in the water column or on the surface'.
Furthermore, it is considered that most sharks take a 'cautious investigative
approach' to large objects in the water.
Professor Daniel Bucher added:
Basically, sharks being a top predator, the only enemies they
have are bigger sharks. Anything that is sitting on the surface is worth
investigating as a potential food item. I do not think they are mistaking us
for other prey; I think they have got this electrical sense. They have got a
really good sense of sound and movement. They k006Eow this is not their normal
food, but it is big enough and it is sitting there, and it is not doing much,
and it does not seem to be able to swim as fast as all the other food it might
be eating. That is why a lot of attacks are from behind; they are a
Killing 'rogue' sharks will solve
to the suggestion that sharks hunt humans is the theory of 'rogue sharks'.
The existence of rogue sharks was theorised by Victor Coppleson in the 1950s.
Essentially, the theory centres on a 'rogue' shark or sharks that have developed
a taste for human flesh, and that a series of shark encounters in the same area
can be attributed to 'the work of a single shark—a rogue shark—which maintains even
for years a beat along a limited stretch of shore'.
Dr Christopher Neff has observed, the film Jaws captured the public
imagination about the risk of sharks and provided a vehicle through which rogue
shark theory became accepted as a true explanation for human–shark encounters. The committee
was also referred to other examples where individuals have called for rogue
sharks to be killed to solve the problem of human-shark encounters.
Governments have also hunted 'rogue' sharks following shark bite incidents.
experts who the committee questioned during this inquiry do not accept the rogue
shark theory. In particular, it is emphasised that sharks are migratory. CSIRO
explained that bull, tiger and white sharks have similar movement patterns in
that they 'roam over considerable distances (1000s of km)...and utilise both
nearshore and offshore waters as part of their normal habitat'. Regarding white
sharks, CSIRO noted that they 'are not permanent residents at any one site'
with movements that 'indicate temporary residency at various sites, mixed with
periods of long-distance travel that may include common corridors'.
experts were clear that they 'have no evidence for anything called a rogue
Sharks are dumb
Jessica Meeuwig argued that sharks 'are actually quite smart'. To illustrate,
the professor referred to learned behaviour where sharks start to follow boats
that are chumming.
Professor Bax from CSIRO stated that sharks are 'highly evolved creatures
in a very specialist area'.
The presence of sharks in an area means an attack is likely
there is a belief in some quarters that if a shark is in the area, then an
attack is likely. In response to this suggestion, Professor Bax from CSIRO told
Clearly we've seen areas where there are large numbers of
white sharks with no attacks. Similarly, large numbers of tiger sharks were
caught in the WA drum line program when there weren't attacks by white sharks.
So just because there are sharks there doesn't mean there's going to be an
it was noted that the waters off Port Stephens in New South Wales are a known
residency location for juvenile white sharks and, although encounters often
occur between humans and sharks 'it is not implicated as a particularly high-risk
It was also noted that bull sharks regularly travel through the waters off
Sydney and in Sydney harbour, and that this activity occurs without incident
when people are in the water.
Lethal measures stop human–shark
Although lethal measures reduce the risk of a human–shark encounter by
reducing the number of sharks in the water, the degree to which this risk is
reduced is impossible to quantify. Nevertheless, the available evidence
suggests that culling programs do not reduce the number of shark bite
fatalities. For example, in Hawaii over 4,500 sharks were culled over nearly
two decades. After an evaluation demonstrated that the cull did not affect the
number of fatalities, the program was abandoned in favour of non-lethal
Culling programs can also fail to target the species of sharks
associated with shark bites in a particular region. For example, the trial of
drum lines conducted in Western Australia in 2014 is estimated to have killed
173 tiger sharks but did not kill any white sharks. White sharks were the
species involved in the shark bite incidents that led to the trial, whereas
tiger sharks have not been implicated in any lethal attacks in the region since
New South Wales and Queensland shark control programs also do not prevent
human–shark encounters. For example, the committee was advised that:
Since the Queensland measures were introduced, 17 human–shark
encounters have occurred at beaches with drum lines and/or nets, including one
fatality. The fatality occurred at a location where eight drum lines were in
place. It was also noted that shark encounters have
increased at the Central Coast beaches since shark nets have been installed.
In New South Wales, 40 non-fishing related human–shark encounters
have occurred at netted beaches, including 24 incidents between September 1992
and the end of 2016 (almost one per year). It was also noted that no shark bite
fatalities occurred between 1929 and 1937 (when the nets were introduced),
or during World War II when the nets were removed.
that serious injuries have resulted in recent shark bite incidents, when
considering the low rate of fatalities, several stakeholders argued that
improvements in medical responses (such as blood loss prevention) need to be
taken into account.
location of lethal shark measures also mean that people involved in activities
associated with a higher risk of shark encounters are unlikely to be protected.
For example, divers are unlikely to be protected by drum lines or nets located
evidence regarding the effectiveness of lethal measures is in Chapter 4.
Shark nets provide a barrier
separating sharks and humans
nets have limited coverage and do not provide a barrier that separate people in
the water from sharks. This is because the nets are only 150 metres to
186 metres wide, and are six metres deep with limited vertical coverage (bottom
set nets result in a gap between the surface and the top of the net, whereas
surface-set nets result in a gap underneath the net to the seafloor). The nets
are generally deployed up to 500 metres offshore.
is not intended that the nets create an enclosed area: rather, they are a
passive fishing device designed to cull sharks in the area. Sharks can,
and do, swim around them.
are new types of non-lethal devices that seek to provide a barrier between
sharks and beachgoers, such as the eco barriers. These products are discussed
in Chapter 6.
The Queensland shark control
program is a model that other states should follow
this inquiry it was argued that due to the low number of shark-related
fatalities and injuries in Queensland since the Queensland shark control
program was introduced, other states should follow the Queensland Government's example
and introduce nets and drum lines. Putting aside evidence received about the
limitations of lethal measures in general, there are key differences between
the marine environments in Queensland and other areas, such as Western
Australia, that make comparisons problematic.
most significant difference is the species typically involved in shark bites
(white sharks in Western Australia and bull sharks in Queensland). Although the
lethal measures capture the shark species involved in shark bite incidents in
Queensland, when drum lines were trialled in Western Australia they failed to
catch any white sharks. The committee received expert evidence emphasising the
need to account for how different species behave, such as white sharks being
visual specialists whereas bull sharks rely on electro reception.
It was also noted that white sharks are migratory and travel great distances,
whereas bull sharks are more territorial; therefore the risk in Queensland
arises from bull sharks that spend significant time near the coastline. Furthermore,
other differences between the marine environments were noted, such as
Queensland being a semitropical to tropical environment where white sharks do
not spend large amounts of time, and the difference in seal and sea lion
populations (these animals are present in Western Australian waters but not in
the evidence available indicates that copying measures used in one region to
target a different species of shark in another region will not necessarily be
The closure of a shark fishery in
Western Australia has led to shark attacks
Western Australian Minister for Fisheries told the committee that there is a
local myth about a shark fishery in Western Australia which was closed and that
that this has contributed to recent spikes in human–shark encounters. The Minister
informed the committee that:
There has never been a great white shark fishery. We have
just never fished specifically for great white sharks for human consumption.
There is a shark fishery still here in Western Australia in the southwest. It
actually targets other species. My understanding is that most of the attacks
have actually occurred where that shark fishery operates. There is a bit of
confusion around: 'There's been a closure of a shark fishery.' People assume
that that must have been a shark fishery where they were targeting great
whites. There has never been a great white shark fishery as such, here in
The presence of whales has resulted
in higher numbers of sharks off the coast
factoid discussed during the committee's public hearings is the suggestion that
an increase in the number of whales off the Western Australian coast has
attracted greater numbers of sharks and resulted in a higher number of
human–shark encounters. When asked about this suggestion, Professor Bax warned
that correlation does not prove causation. More specifically, CSIRO referred to
a recently peer reviewed paper that examined coastal movements of white sharks
off Western Australia. CSIRO explained that the paper found that, 'although the
distribution of white sharks along the west Australian coastline overlapped
that of humpback whales, there was no evidence to support the statement that
white sharks were following the humpback whale migration'.
Instead, CSIRO suggested that many other factors are responsible for increased
human–shark interactions, such as changes in near-shore fish species preyed on
Electrical shark deterrents attract
committee was also advised that some people believe that the technology used in
electrical shark deterrent products, such as Shark Shield, attracts sharks.
In response, Mr Lindsay Lyon, the Managing Director of the company that
produces Shark Shield, explained that the electrical fields produced by the product
From a physics electronics perspective, it is extremely
difficult to transmit electrical fields under water. The reason we have
submarines in defence is when you have a nuclear explosion and it causes an
electromagnetic pulse it does not affect the submarines because the water acts
as a complete shield. The electrical field from these devices at about six or
10 metres is, in the technical marketing term, 'jack to none'. So it is very
hard to transmit under water.
Perceptions on the risk of shark
although this is not a myth as such, it is important to note that,
statistically, the risk of a fatal shark bite incident is very low. According
to data collected by the Taronga Conservation Society Australia (TCSA), in the
last 50 years there have been 47 fatalities in Australia arising from
unprovoked shark bites (an average of 0.9 per year).
Although the overall number of shark bite incidents in Australian waters has
gradually increased over the last few decades, the risk is very low when
compared to other causes of death and when the millions of beach visitations
that occur each year are taken into account. For example, Sea Shepherd
Australia cited TCSA data indicating that, over a person's lifetime the risk of
being killed by a shark is one in 292,525, compared to a one in 3362 chance of
drowning at the beach.
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