Chondrichthyes (cartilaginous fish,
including sharks, rays and chaemeras) >
Shark attack
There are few phenomena injurious to people
that are more misunderstood than shark attack. Popular perceptions
and statistical realities are separated by a vast gap of fear,
supposition, and ingrained images or archetypes. Sharks have been
long been known to attack people, but at an extremely low rate
compared to the vast number of people at risk.
Shark attack in Southern Africa
The pattern of shark attack off southern Africa
is similar to other regions in being positively correlated with sea
temperature. This is related to the greater number of people using
the sea for recreation in warm-temperate and subtropical waters of
the east coast and also to the greater diversity and abundance of
potentially dangerous sharks in warmer waters.
Attacks on swimmers, surfers and divers occur
at a low rate along the west and east coast from Namibia to
Eastern Cape. Very few attacks have been recorded from
Namibia to Cape Town, although
Great white sharks and
Spotted
sevengill sharks are common on the west coast and have been
encountered by divers underwater. Shark attacks are commoner on the
southwest and southeast Cape coasts, with most occurring in False
Bay and off East London.
KwaZulu-Natal's warm climate and warm temperate sea has
long made it a holiday Mecca, particularly for inlanders who flock
to the sea for their vacations. This coast has a higher rate of
shark attack compared to the Western and Eastern Cape coast although
absolute numbers are small.
Widespread shark netting off the Natal beaches
started in earnest in the mid-sixties and has had a marked effect in
reducing shark attack from netted areas. The nets do not, however,
act as an absolute barrier like a shark enclosure, and a few attacks
have occurred inside the nets on netted beaches. With improved
knowledge concerning treatment of attack victims, especially by
lifesavers of the Surf Lifesaving Association of South Africa
(SLASA), fatalities of attack victims have been reduced.
Increases in shark attack from the 1940's to
the present have been slight, even in areas where shark nets and
other forms of fishing have not reduced the resident shark
population. This is despite increasing use of the sea by a rapidly
expanding population. Furthermore, there has been a postwar increase
in water sports as a result of advances in technology that produced
aqualungs, wetsuits, fibreglass surfboards and fishing equipment
which has resulted in a concomitant introduction or popularization
of sports such as surfing, SCUBA diving and spearfishing. These
sports take people well beyond the inshore protection of shark nets
and into unnetted sections of coastline, but there has not been an
onslaught of shark attacks proportional to the increasing numbers of
people utilizing the water.
The higher attack rate in KwaZulu-Natal compared to
Cape waters has been attributed primarily to greater numbers of
people in the water, particularly off popular tourist beaches. An
additional contributing factor is likely the greater diversity and
abundance of potentially dangerous sharks in warmer waters,
particularly a few species of large, powerful and omnivorous requiem
sharks such as the
Zambezi and
Tiger sharks. The fatality rate for
the decades 1940-49, 1950-59, and even 1960-69 (during which period
shark netting off beaches began to reduce the numbers of potentially
dangerous sharks) is strikingly higher than in Cape waters. This may
also reflect a difference in the species composition of sharks
perpetrating the attacks:
Great white sharks, the principal
attackers in Cape waters, show a strong inclination to abort attacks
on people, while off KwaZulu-Natal some of the attackers (presumably
omnivorous requiem sharks such as Tiger and Zambezi sharks), may
tend to actually feed on people. The reduction of shark attacks from
the late sixties to the present time, after the shark netting
programme was well underway, is correlated with the decline in numbers
of resident omnivorous sharks, particularly Zambezi sharks, as
evidenced by shark net catches.
Anti-Shark Measures
In former times bathing
enclosures were used in Natal to protect swimmers from sharks, which
were effective but expensive to keep repaired. Following the lead of
Australia, where gillnets were installed off the Sydney beaches in
New South Wales in the late 1930's, the Durban municipality opted
for the more aggressive and flexible method of shark netting off
bathing beaches, which reduces shark attacks by killing large,
potentially dangerous sharks. Present anti-shark measures in Natal
rely on gillnets installed by the Natal Sharks Board (NSB; once
called the Natal Anti-Shark Measures Board), which came into being
as a direct result of the media-fanned fear of shark attack in the
vacationing public during the late 1950's. More importantly,
anti-shark measures, and the NSB, grew from the economic fears of
business interests in Natal which had suffered from the results of a
spate of shark attacks in Natal during the Christmas holiday of 1957
and 1958. The public deserted the beaches en masse after `Black
December' and caused a marked decline in the local, recreation-based
economy.
In 1983 some 45 beaches were netted by the NSB
in Natal, with 381 nets deployed, each net being 100 m long (except
for 300 m nets deployed around Durban). Present numbers of nets are
probably over 400, with over 46 beaches netted off Natal and
northernmost Transkei. The numbers of nets deployed per beach are
dependent on local conditions. Large resorts and municipalities pay
for the cost of the nets, but smaller entities have part of the cost
defrayed by the Natal authorities.
The NSB has a large, impressive headquarters at
Umhlanga Rocks which is its administrative and logistics centre,
with sections for net building and repair, staff housing, boat and
vehicle maintenance, research, and public relations. Considerable
scientific data is collected by the NSB on netted sharks, from
netting teams and from dissection by NSB scientific personnel at
Umhlanga Rocks. Such data is entered into a computer database which
is currently being extracted for publication by NSB scientists, and
will eventually become available on the biology of several species
of sharks caught by the NSB nets.
Sharks taken by the NSB ranged in number from
808 to 1,842 per year from 1968 to 1983 (average about 1,151 per
year), for a total of 18,423 sharks taken. This does not include
sharks taken by the Durban municipality from 1968 to 1979, which
during this period operated independently of the NSB. For the period
1978 to 1984 the Natal anti-shark nets yielded about 8,333 sharks,
of which approximately 9.7% were
Great whites,
Zambezi, and
Tiger
sharks, considered the most dangerous local species by various
authorities. Another 2.8% were
Great hammerheads and
Java sharks,
potential attackers, and 1.2% were
Shortfin makos. Most sharks taken
were of minimal danger to humans:
Spotted ragged-tooth shark, 12.0%,
Dusky sharks, 18.6%,
Copper sharks, 12.6%,
Sandbar sharks, 2.0%,
Blacktip and
Spinner sharks, 20.6%,
Scalloped and
Smooth
hammerheads, 18.9%, others 1.6%. Other animals caught in the nets,
including rays, turtles, and
dolphins, are released by the netting
teams if still alive, and lately live sharks are being released
also.
The NSB has changed qualitatively in greatly
increasing its public outreach programs, displays, and other public
relations work that promulgates a positive image of its activities,
and encourages their continuation and expansion. This interlinks
with public ignorance of the minor danger of shark attack and its
unreasoning fear of sharks, the tendency of the newsmedia to
overpublicize shark attacks and frighten the public, and the
expanding tourist industry. With a circular logic in a
positive-feedback loop, the presence of shark-netted beaches
generates the demand for more shark-netted beaches as new resorts
open or smaller ones with netless beaches become larger or more
popular. The same thing happened in Australia: the netting programme off the state of New South Wales spawned a new netting operation off
Queensland as that state's Gold Coast developed for tourism, despite
the low frequency of shark attacks there.
No efforts have been made to extend the
activities of the NSB elsewhere in southern Africa except northern
Eastern Cape, and the defined sphere of operation of the NSB is limited
by its charter to KwaZulu-Natal. There
have been sporadic and abortive attempts to install shark nets off
East London and in False Bay in the past few decades following a few
overpublicized shark attacks and spates of shark hysteria and
paranoia.
The increasingly wide-ranging activities of the
NSB has generated considerable controversy in KwaZulu-Natal. There is
concern on the ecological effects of long-term shark netting,
particularly amongst anglers, scientists, and conservationists.
Obviously, the specialist anglers who fished for big sharks in
southern KwaZulu-Natal have been adversely affected by the shark nets, and
have either abandoned their sport or go further afield to northern
KwaZulu-Natal or northern Eastern Cape for large sharks.
Anglers and scientists have noticed a marked
increase in numbers of juvenile
Dusky sharks,
Milk sharks, and
possibly other small sharks in the past decade, and attribute this
to the shark nets. According to this view, which is opposed by the
NSB, the shark nets have depressed the numbers of larger sharks that
feed on smaller sharks, and increased the survivorship of young
dusky sharks and in small sharks generally. There is an apparent
decline in bony fishes targeted for sport, which may be induced by
greater numbers of juvenile and adult dusky sharks as well as
increased angling pressure. In the ensuing controversy, the NSB
denied that such an increase in dusky sharks was occurring, but
organized anglers, commercial fishermen, and fisheries scientists in
KwaZulu-Natal have argued otherwise from long-term fishing records.
A heated and emotional public
controversy arose over dolphins caught in the shark nets. The
long-term effects of shark netting on inshore dolphin populations
are uncertain, but some segments of the Natal public have reacted
strongly to the killing of dolphins by the nets. From the late
1960's onwards, dolphins and other cetaceans have acquired an
intensely positive, anthropomorphic public image in the West that
generates strong sympathy for them (`Flipperphilia') and action
against people who cause their demise (`save the whale' campaigns).
While the small sharks and dolphin controversies still rage, there
is currently no move to independently access the ecological effects
of shark netting in the much broader and massive context of
human-induced environmental degradation along the Natal coast.
Alternatives to current Anti-shark Measures
Shark netting originated at a time when knowledge of the biology of
large sharks was minimal, and when it was blindly assumed that all
large sharks were dangerous and potential `maneaters'. At present we
know that even the most powerfully armed sharks will not
automatically attack people in the water. To put it bluntly, human
beings are not `on the menu' of large predatory sharks, which
normally eat aquatic organisms. This is different from some of the
large terrestrial carnivores, such as
lions, tigers,
Spotted
hyaenas,
leopards, the larger bears, wolves, and the largest
crocodiles, which in primitive times probably included humans as
regular prey. Large sharks may approach divers without any attempts
at predation and may depart without aggression, but may also give
warning displays and inhibited threat bites similar to those used on
members of their own species, on other sharks or on other marine
organisms. Numerous encounters between divers and
Great white sharks
suggest that this formidable superpredator may not normally regard
human beings as prey. This seems true for large species such as the
Spotted ragged-tooth which differ from the white shark in largely
feeding on fishes and invertebrates and avoiding mammalian prey. The
most dangerous sharks may be the few species of omnivorous
requiem
sharks (family Carcharhinidae), particularly the
Tiger and
Zambezi
sharks, which are highly opportunistic feeders like the
Spotted
hyaena and readily take mammalian meat, carrion and garbage.
However, even these sharks will not automatically attack divers
underwater, and probably only rarely turn their attention to
swimmers and bathers as actual prey. Shark netting seen in this
context is unselective and analogous to dealing with the problem of
occasional man-eating lions or tigers in a game park by randomly
shooting all carnivores down to the size of
caracals and
jackals,
and potting some of the ungulates for good measure!
Several alternatives to shark netting are
possible. The NSB has as its primary mandate the protection of the
beaches of KwaZulu-Natal, which does not necessarily lock it to shark
netting and could include its major participation in the
development, promotion, and maintenance of non-lethal alternatives.
We suspect that shark netting became popular in Australia and in
KwaZulu-Natal not only because it reduces shark attacks, but because it
actively and aggressively destroys the `enemy'. Such a macho,
warlike public reaction to large apex predators has been common in
the past, but has been largely superseded by a tolerant,
unaggressive, respectful approach toward dangerous terrestrial
predators. This has partly extended to sharks by the experiences
conveyed by divers and diving scientists to the general public,
which show sharks as far more benign creatures than the ferocious,
malevolent JAWS bogeyman promoted by the popular media. In the light
of the continuing controversies over shark netting, and public
concern for its possible environmental effects, we mention a few
alternatives here.
Dr. E. D. Smith of the National Physics
Research Laboratory developed a pulsed-current cable system that
forms an electromagnetic barrier to repel sharks. After initially
promising results with a small shark cable in a tank at the
Oceanographic Research Institute, Durban, full-sized cables were
installed in the sea off a beach at Margate, but ran into chronic
and expensive operational difficulties. Problems with electronic
equipment gave inconclusive results in a 1988 series of
field tests of the latest version of the cable at Margate, and the
future of government funding for the programme is in doubt. The
electronic cable remains one alternative to netting despite the
operational problems at Margate, but needs much additional testing
and expensive modifications that may not be pending. There have been
individual electronic shark repellent wands marketed in the USA that
can be carried by individual divers and which will ward off
inquisitive sharks.
Shark enclosures could be built using modern,
lightweight, strong materials such as new alloys, plastic
composites, and new high-tensile strength fibers such as Kevlar.
These may be able to withstand the destructive and corrosive action
of the sea more effectively than the steel enclosures used in
earlier times. If used in conjunction with existing pier structures,
or with specialized multiple-use recreation piers, these could even
be removed in the event of extremely heavy seas or floods. The city
of Durban recently built an elaborate and expensive set of public
wading pools along the beachfront to cater for tourists, and such
assuredly sharkproof facilities can be extended to the ocean itself.
Intact enclosures have the advantage over shark nets of offering
100% security from shark attack without removing sharks or other
marine life. Materials and site research and development is
necessary to produce modern shark enclosures and shark-proof
breakwaters that can fit into plans for city beach development.
Equivalent protection for divers includes small portable shark cages
developed in Australia for commercial perlemon (abalone) divers, and
steel-mesh shark armour that fits over ordinary wetsuits.
The use of ultralight spotter planes, small piston-engine
helicopters, or small blimps by lifesaver-observers may also prove a
non-destructive method of preventing shark attack by warning bathers
when large, potentially dangerous sharks approach them. Our own
experience with helicopters and light planes show the effectiveness
of aerial observation in spotting sharks off beaches. The advantage
of using microlight aircraft would be the greatly reduced operating
costs compared to conventional light planes and helicopters.
Technological innovations may yield a method of
detecting sharks that approach too close to bathing areas on beaches
using automated remote sensing techniques that can issue warnings to
bathers and swimmers. Such equipment is readily available for land
use, and it is probably a matter of time before an equivalent can be
developed for bathing areas.
Research on shark repellents in Israel and the
USA have finally yielded effective substances that can be used to
protect divers and bathers from shark attack. Certain industrial
detergents (including sodium lauryl sulfate) have a powerful effect
in repelling sharks, and have been successfully tested in the field
by scientist-divers. Possible uses include shark-billy applicators
for divers that squirt a jet of repellent at an approaching shark,
shark-repellent salves, special repellent wetsuits for divers,
surfers and bathers, and even shark-repellent coatings for
surfboards. The Moses sole, a small flatfish of the Red Sea,
secretes a natural shark repellent that inhibits sharks from biting
it, which could be imitated by shark repellent apparatus designed
for human use.
In view of the heavy mortalities to sharks
caused by fishing activities along the coast and the low number of
attacks, it has been suggested that the expense and effort of a
provincial shark netting programme may, in fact, be unwarranted. As
shark products increase in value worldwide and recreational angling
for sharks becomes more popular in southern Africa, increased
commercial and recreational fishing with line gear may be able to
substitute for netting programs and will accomplish the same
purpose, depletion of stocks of potentially dangerous sharks.
Although dolphins, turtles and some rays would not be affected by
line gear, the environmental impact of removing large sharks would
be the same no matter what gear is used, and such fisheries would
have to be carefully regulated to insure the survival of local
sharks.
An alternative approach to shark attack, which
is apparently repugnant to many but not everyone in KwaZulu-Natal, is
non-intervention, as currently practiced on the Cape coast as well
as in California, Hawaii, Florida, New Zealand, and several other
places where shark attacks are regularly reported. Florida has a larger and more valuable tourist industry than
KwaZulu-Natal and a
higher rate of shark attack (14 in 1981) than Natal prior to
shark-netting, but has no anti-shark measures whatsoever. California
has its shark scares and media hyperbole as in southern Africa but
nothing is done except to occasionally close beaches and post
warning signs on beaches off which shark attacks have occurred. Up
to 7 attacks per year have occurred there, but this is miniscule
compared to the vast numbers of people using the water. There are
upwards of 400,000 registered SCUBA divers at any one time in
California, plus numerous commercial abalone and sea urchin divers,
skin divers, surfers, swimmers, commercial fishermen, and anglers
that share the water with large white sharks and probably vastly
outnumber them, yet attacks are few and far between.
Finally there is a obvious need for the public
to be educated on the realities of shark behaviour and the minor
objective importance of shark attack. Shark attack should be
demystified by the same kind of educational processes used in
dealing with other dangers of sea and shore. Hopefully this book
will contribute to this process, and to public education. We see the
popular newsmedia, which have so often helped to instill shark
paranoia and hysteria in the past, as instrumental in promoting a
sober, realistic awareness of the nature of sharks and of shark
attack. Serious threats to human life such as automobile accidents
are routinely reported in a straightforward fashion, without the
gory and unnecessary embellishment of shark attacks. We hope that
news reporters and editors will assimilate the realities of sharks
and shark attack, and will voluntarily refrain from emotional,
sensationalist, self-serving reportage in the future. Overheated
shark-attack accounts help to perpetuate the myths of shark attack
and the killing of sharks at a level far, far higher than the few
human fatalities.
Shark Sense
The low incidence of shark attack
can be further minimized by taking due care while using the sea
(`shark sense'). Each of us have had personal encounters with sharks
and the following advice is given from these experiences, from the
advice of colleagues, and from general advice in various
publications.
To lessen the likelihood of attacks, swimmers
should not: 1. Bathe at night in the sea. 2. Swim in turbid waters,
especially when rivers are disgorging large volumes of sediment into
the sea nearby. 3. Swim when bleeding either from a laceration or
during menstruation. 4. Swim alone far from shore over deep water.
5. Swim in the vicinity of popular fishing spots, particularly in
deep water.
Divers should not: 1. Have speared fishes on
their belts, because they may be injured by sharks trying to eat the
fish. 2. Dive where known concentrations of large sharks occur, such
as off seal colonies, near sardine and squid schools, and off river
mouths. 3. Have bleeding fish in the water for any length of time.
4. Spear fishes in turbid water. 5. Stay in an area if a shark comes
close and exhibits unusual swimming behaviour or a gaping display.
The diver should retreat and get out of the water.
Treatment of Shark Attack Injuries
Knowledge
of suitable treatment will greatly increase the likelihood of a
victim's successful recovery from shark attack, as has been realized
from treatment of victims in southern Africa and elsewhere. The
following is an abridged version of advice given to life savers of
the Surf Lifesaving Association of South Africa (SLASA):
-
Do not waste any time in recovering the
victim from the water.
-
Bring the patient ashore and get him to
the nearest dry area, and place him on the back with the head down
and legs elevated.
-
Stop any bleeding either by pinching off
arteries or by applying a tourniquet or a clean piece of cloth to
the open wound to allow the blood to clot. Do not disturb this
dressing by looking at the wound. Elevate the bitten limb. Check
that bleeding has ceased.
-
Record the time of application of the
tourniquet as it must be released an hour after application for five
minutes. If a limb has been amputated do not release the tourniquet.
-
Do not rush the victim to the hospital. The patient should be
given at least 30 minutes to stabilize on the beach before being
moved. If possible, get a doctor to the patient. Movement of the
patient before this stabilization occurs will probably result in
death.
-
Comfort and reassure the patient, and check the breathing
of the patient. Apply expired air resuscitation if necessary. Cover
the patient with a light blanket to prevent chilling.
-
Keep
control of the crowd and try and get competent paramedical or
lifesaver help if a doctor is not available. These people will bring
a shark attack pack to assist the patient.
-
Inform the medical
people with as much information on the attack and treatment of the
patient to date, including the time of attack and time elapsed since
first application of a tourniquet.
Remember that shark attack is a rare
phenomenon, and that the advice given above is much more likely to
be of assistance in helping a victim of a car crash than of a shark
attack!
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Text by Leonard J.V. Compagno, David A. Ebert
and Malcolm J. Smale
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