Sea Sabres Scuba Diving club, Southern
California, Fullerton
Sea Sabres
Safety and Education
Shark Attacks
PROPER PERSPECTIVE
Sharks
attack some 50-75 people each year worldwide, with perhaps 8-12 fatalities, according
to data compiled in the International Shark Attack File (ISAF). Although shark
attacks get a lot of attention, this is far less than the number of people
killed each year by elephants, bees, crocodiles, lightning or many other
natural dangers. On the other side of the ledger, we kill somewhere between 20
and 100 million sharks every year through fishing activities.
Great
White Shark
Of
the 350 or so shark species, about 80% grow to less than 5 feet (1.6 meters)
and are unable to hurt people or rarely encounter people. Only 32 species have
been documented in attacks on humans, and an additional 36 species are
considered potentially dangerous.
Almost
any shark six feet or longer is a potential danger, but three species have been
identified repeatedly in attacks: the great white, tiger, and bull sharks. All
three are found worldwide, reach large sizes and eat large prey such as marine
mammals or sea turtles. More attacks on swimmers, free divers, scuba divers,
surfers and boats have been reported for the great white shark than for any
other species. However, some 80% of all shark attacks probably occur in the
tropics and subtropics, where other shark species dominate and white sharks are
relatively rare.
Identifying
the species of shark responsible for an attack is often difficult. As a case in
point, most attacks in Australia prior to the 1970's were attributed to the
sand tiger shark, Odontaspis taurus, called the grey nurse shark by the
Australians. Since the shark seen in an attack often was described as grey in
color, the name association implicated this species. The resulting bias towards
these sharks led to the extermination of this species from the populated areas
of southeast Australia. The fact is that the grey nurse is not among the more dangerous
shark species, and it is now protected in these same Australian waters.
WHY ATTACK
Many
shark attacks occur in nearshore waters, typically inshore of a sandbar where
sharks may be confined at low tide. Sharks may also congregate along steep drop-offs,
near channels or at river mouths, because their natural food items congregate
there.
There
may be a number of reasons why sharks attack humans in these areas. Some
attacks may be purely an inquisitive testing, some may be territorial
responses, some could be due to unintentional interference by the victim in
shark courtship activities, and some may be directly associated with feeding
behaviors. Some scientists speculate that shark attacks on humans often are
cases of mistaken identity, except in unusual situations such as when a sinking
ship throws many people into the water. Whatever the cause, shark bites produce
serious, sometimes life-threatening wounds.
Bull
Shark
Whereas
other sharks are likely to approach with caution, swimming around and poking
the prey before attacking, the white shark often goes straight for the kill,
relying on stealth to catch the victim off-guard. When feeding on prey at the
surface, this shark rushes upward and, with an explosive splash, bites down on
the unsuspecting victim. Although white sharks feed readily upon seals and sea
lions, they often spit out birds, sea otters, and humans after the initial,
albeit severe injury. Some shark experts have thought this indicated that human
flesh or the neoprene of wetsuits was distasteful to the shark or that this
reflected a "bite-and-release" attack strategy of the white shark,
while others have speculated that these sharks only bit humans to defend their
territories. Divers in wetsuits, surfers on short surfboards, and perhaps even
kayakers may appear in silhouette like marine mammals, these sharks' natural
prey, and some biologists have speculated on a connection. But if white sharks
attack humans for food, the fact that nearly 75% of these attacks are non-fatal
indicates that either the method of attack is allowing the human victim to
escape, or we just don't taste right to them.
TYPES OF ATTACK
Unprovoked
shark attacks can be categorized as hit and run, bump and bite, or sneak attacks.
Hit and run attacks typically occur in the surf zone with swimmers and surfers
as targets. The victim seldom sees the attacker, and the shark doesn't return
after inflicting a bite. According to ISAF Curator George Burgess, these
attacks in most cases are probably due to mistaken identity where water
visibility is poor, wave and current action are high, and human recreational
activities are prevalent. Some of these attacks could also involve social
behaviors unrelated to feeding, such as dominance behaviors similar to those
observed in land animals. Injuries from this type of attack are usually
relatively small lacerations, often on the leg below the knee, and are seldom
life-threatening.
Bump
and bite attacks are characterized by the shark circling and often bumping the
victim prior to the attack. Sneak attacks occur without warning. In both cases,
repeat attacks are common and injuries are usually quite severe, sometime
fatal. These shark attacks, which include most attacks involving airplane and ship
accidents, may be the result of deliberate feeding or combative behaviors
rather than cases of mistaken identity.
PREVENTION
The
best prevention for shark attack is common sense applied to where you swim and
what activities you undertake, and awareness of what may invite or provoke an
attack. General guidelines for swimming in areas inhabited by sharks include:
·
Swim,
dive or surf with other people -- never alone. Don't swim where dangerous
sharks are known to congregate.
·
Avoid
swimming between sandbars, near steep drop-offs, near channels or at river
mouths where sharks are found.
·
Don't
swim in dirty or turbid water. Avoid wearing shiny jewelry that might simulate
the scales of a prey fish, and also avoid uneven tanning and contrasting,
bright-colored clothing. Don't swim at dusk or at night.
·
Refrain
from excessive splashing. Keep pets and domestic animals, with their erratic
movements, out of the water.
·
Don't
swim near people who are fishing or spear-fishing, or near sewage outfalls.
Avoid spreading blood or human wastes in the water.
·
If
schooling fish start to behave erratically or congregate in large numbers,
leave the area.
·
If
a shark is sighted in the area, leave the water as calmly and quickly as
possible.
Sharks often are called unpredictable, but this has been more a reflection of our own knowledge rather than the behavior of the sharks themselves. Learning more about sharks' natural behavior is needed. A person armed with such knowledge may be able to predict with some confidence the behavior of a shark that they encounter in the water, and avoid provoking the shark to attack.
