Page 52 - Shark

Sharks at bay

People who go into the water where there may be
dangerous sharks run a small risk of being attacked.
There is no simple way to keep sharks away from all
the places where people paddle, swim, surf, or scuba
Jonah and the? dive. Shark-proof enclosures have been built but these
In the bible story, can only protect small areas because of the large cost.
Jonah was swall-
owed by a large sea In South Africa and Australia, nets are used along
creature, which could the most popular beaches to trap sharks, but they also
have been a shark,
rather than a whale. trap and kill many harmless sharks, dolphins, rays,
Lifeguards
and turtles. Drumlines (baited lines Australian lifeguards look out for
with hooks) are also used to capture sharks. If sharks are spotted near a
sharks—and trap fewer harmless beach, the shark alarm is sounded and
swimmers leave the water. The beach
animals than nets. Electrical, magnetic, may be closed for the rest of the day, if
and chemical repellents are all sharks stay in the area. Always follow a
lifeguard’s advice on safe swimming.
being tested to keep sharks
away. A shark that gets
aggressive can sometimes Float
be pushed away with Net
a heavy underwater
camera. If all else fails,
kicking or punching a Anchor
shark’s snout may put
it off an attack.

sharK shieLd
The Shark Shield is designed to repel
sharks by generating an electric field. It
may throw the shark’s snout into spasm.

Float
Net

Anchor

in the bag
One way to help people who end up netting beaches
in the sea if a ship sinks or an airplane Mesh nets are used to protect the most popular beaches
crashes, is to give them large, inflatable by trapping sharks in the area. The nets do not form
bags. When tested by the US Navy, a continuous barrier, so sharks may be caught (on
sharks avoided them, because they both sides of the nets—either swimming toward or
could not see any limbs, sense any away from the beach). Heavy anchors keep the nets
electric signals, or smell blood or body on or close to the bottom and floats keep the top
wastes, which are kept in the bag. of the net suspended in the water. The nets are
about 660 ft (200 m) long and 20 ft (6 m) deep.
Marker buoys float at the surface so the nets
trapped are easily found again. The nets are checked
A shark, trapped in a mesh net almost every day and dead sea animals
off an Australian beach (right), removed. After three weeks the nets need to
is landed. In the l930s, during a be replaced because they become fouled by
17-month period, 1,500 sharks seaweed and other marine growth, and so
were caught by this method. can easily be seen and avoided by sharks.
Since then, numbers of sharks Nets that have become tangled up in
have decreased sharply. storm waves also need to be replaced.

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