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Facts About Sharks in Hawaii
Facts about sharks in Hawaiian waters, from the State of Hawaii,
Department of Land and Natural Resources, Division of
Aquatic Resources.
Species of Sharks in Hawaii
There are about forty species of sharks that occur in Hawaiian waters,
ranging in size from the deep-water pygmy shark (about 8 inches) to the
whale shark (up to 50 feet or more).
About eight species are somewhat common in nearshore waters. The most
frequently encountered are the whitetip reef, sandbar, scalloped
hammerhead, and occasionally tiger.
These inshore species are top-level carnivores, feeding primariy on
fishes. Their roles in reef ecosystems are not fully understood,
though they may keep fish population sizes in check, and remove
sick and injured fish, leaving the healthiest to survive and reproduce.
How Sharks Detect Their Prey
Sharks have extremely well-developed sensory capabilities. They can
detect sounds and smells from prey at great distances (up to a mile
or more, depending on water conditions). Their eyesight is good, but
depends greatly on water clarity.
As sharks approach their prey, they can detect the faint electric
fields given off by all living organisms. Receptors on their snouts,
known as ampullae of Lorenzini, allow sharks to locate their prey
without seeing it.
Using these and other senses, sharks can find prey at dusk, night,
and dawn, which is when some inshore species are generally believed
to feed.
Sharks are very much attuned to their environment. They know when
people are in the water long before people are aware of them.
Encounters between sharks and people are infrequent, and most
inshore species pose little threat to humans.
Human Encounters With Sharks
Although any shark may be potentially dangerous, especially if
provoked, it is believed that only a few species of Hawaiian
sharks have been responsible for biting people. However, many
inshore species are difficult to distinguish from each other,
and positive identification is often not made.
In cases where the offending shark can be identified, tiger sharks
top the list. A tiger shark is easily recognized by its blunt
snout and the vertical bars on its sides. Hammerheads are also
easy to identify, and have been implicated in a few cases where
they may have been provoked.
Tigers are considered the most dangerous sharks in Hawaiian waters.
White sharks, which are also very dangerous, are rarely seen in
Hawaii. Because of their size and feeding habits, tigers occupy
the very top niche in inshore feeding relationships.
For years tiger sharks were believed to be territorial in nature.
Individuals were thought to remain for the most part in a fairly
limited area. Recent evidence suggests this is not the case.
Tiger sharks have been found to navigate between the main
Hawaiian islands, and thus appear to occupy home ranges much
larger than had been previously suspected.
Tiger sharks are often attracted to stream mouths after heavy
rains, when upland fishes and other animals are swept out to sea.
They can easily locate prey in such murky waters. Tigers are
also attracted to waters frequented by fishing boats, which
often trail fish remains and blood.
Of all the inshore species, tiger sharks have the most widely
varied diet. They eat fish, lobsters, birds, turtles, dead
animals, even garbage, and may feed whenever a food source
is present.
It’s not known why tiger sharks sometimes bite humans. The
idea that they mistake a person for a natural prey item, such
as a turtle, is not supported by any evidence. The shark may
be trying to determine if a person is a potential prey item,
it may come across a person while in a feeding mode, or
perhaps there is some other explanation.
Incidents of sharks biting people in Hawaiian waters are very
rare, occurring on average at a rate of about three or four
per year. Fatal shark bites are extremely rare, especially
considering the number of people in Hawaii’s waters.
People who enter the water need to recognize that there are
hidden dangers. A number of marine animals can cause serious
injury to people, and sharks are just one example. Entering
the ocean should be considered a wilderness experience, where
people are visitors in a world that belongs to the sharks.
The risk of injury caused by sharks is extremely small, but
it is a risk accepted by anyone who enters the shark’s world.
By learning more about sharks, using common sense, and observing
some basic
Shark Safety Tips, the risk may be greatly reduced.
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Islands of Hawaii
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