86 Sharks: The Animal Answer Guide
are underestimates because they record only starting and ending points for
sharks tagged at one place and recaptured at another.
White Sharks are now known to migrate between central California and
Hawaii, a minimum one-way distance of 3,800 kilometers (2,360 miles); the
return trip makes the journey almost 8,000 km (4,970 miles). Some “Cali-
fornian” White Sharks move back and forth along a fairly narrow corridor
to a place in the Pacific about 2,500 km (1,550 miles) west-southwest, tak-
ing only three to four weeks to make the journey. They spend fall and part
of the winter in California and most of spring and summer in the offshore
area, now called the White Shark Cafe. White Sharks tagged off South Af-
rica go to western Australia and back. One 4-m (13-ft) female nicknamed
Nicole (after Australian actress Nicole Kidman, an advocate of shark con-
servation) was followed by satellites across the Indian Ocean and then back,
traveling between South Africa and Australia. The round trip took nine
months, covering a minimum distance of 22,000 km (13,670 miles).
Whale Sharks move around and across oceans, arriving at particular
places to feed on eggs spawned by reef fishes and invertebrates. A Whale
Shark tagged off Mexico traveled 13,000 km (8,000 miles) across the North
Pacific Ocean. Another tagged in the Philippines traveled to Vietnam, a dis-
tance of 4,567 km (2,830 miles), in only 2.5 months, while another tagged
off Malaysia moved 8,025 km (4,987 miles) over a 4-month period. Many
of these movements involve migrations to areas of briefly abundant food;
after the food is gone, the animals may return to their starting point or go
to places that we don’t know about yet. Despite all this moving around,
genetic analysis of sharks sampled from the eastern Pacific (Mexico, Costa
Rica, Galapagos Islands), the Caribbean and the western Atlantic (Hon-
duras, Florida), and South Africa, western Australia, and the Indian Ocean
(Seychelles, Maldives, Djibouti, India) indicates that sharks intermingle
often when breeding. Basically, there is one world population of Whale
Sharks totaling between only 250,000 and 500,000 individuals, a finding
with strong conservation implications. (For comparison, the Spiny Dogfish
population off Canada’s east coast may number over 500 million sharks; see
“Which sharks are most or least abundant?” below.)
Basking Sharks, second in size only to Whale Sharks, also migrate
across oceans. Baskers tagged off the United Kingdom have been found
three months later off Newfoundland, Canada, on the other side of the
North Atlantic. Sharks tagged off the Cape Cod area during summer
headed south as water temperatures fell in autumn. Some went to the Ba-
hamas, others to the Caribbean, and a few traveled as far south as Brazil,
a straight-line distance of 6,500 km (4,030 miles); the actual track of one
shark indicated it had moved nearly 9,000 km (5,580 miles). While in pro-
ductive northern areas, Basking Sharks feed at the surface, but when in the
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