Page 58 - Shark

Tagging sharks Australian certificate (top), Two Australian
applicators
and card (bottom) for
details of captured shark
with nylon
and
plastic
tags
Anglers can help scientists find out where sharks go and
how fast they grow by measuring, tagging, and releasing
them. Tens of thousands of sharks have been tagged since Return
the 1950s, off the coasts of the US and Australia, as well address
as the UK and Africa. A few tags are recovered when Tag Metal tip
pierces
fishermen catch these sharks again. The record is for a shark’s skin
male Australian tope, which was first tagged in 1951 and
recaptured in 1986, 130 miles (214 km)
from its original release site. Its length
had increased by 7 in (17 cm). Blue sharks
are among the greatest ocean travelers.
One tagged near New York was caught
16 months later off Brazil, 3,600 miles
(6,000 km) away, while another tagged
off the UK’s Devon coast was recaptured Where blue sharks have been
tagged, released, and recaptured
off Brazil, 4,200 miles (7,000 km) away. Cornwall, UK
West Africa
Eastern Seaboard, US

0 600 1,200 1,800 miles

Bird ringing
Ringing bands around young birds’ legs gives information on
migration—just as tags do for sharks—if they are caught again.

Bait

Tagging/releasing sharks
1Like most sharks, blue sharks
have an excellent sense of smell and
are attracted to boats by dangling a
chum bag containing smelly, salted
fish over the side. The chum’s oil
spreads out in a thin film over the
water’s surface, attracting sharks from a great distance. The hooked reeling in
shark hooks are baited with freshly caught mackerel and the 2 Attracted by the oil and blood, 3 The shark is reeled in near the boat, very

fishing lines are let out to depths of 40–60 ft (12–18 m). the blue shark has taken the bait. carefully, so as not to damage the shark.
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