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Chapter 10
Human Problems
(from a shark’s
viewpoint)
Are any sharks endangered?
The recognized worldwide authority on extinction risk in plants and an-
imals is the International Union for the Conservation of Nature (IUCN),
a United Nations–sanctioned clearinghouse for such information. The
IUCN publishes a Red List of endangered plants and animals that it up-
dates regularly. In 2012, the IUCN had assessed the status of 1,090 chon-
drichthyan species; population information was available for only half of
these. When population trends indicate a species is threatened with extinc-
tion, the IUCN assigns ranks of “critically endangered,” “endangered,” or
“vulnerable.” The 2012 assessments indicated that 3% of sharks, skates,
and rays were critically endangered, 4% were endangered, and 11% were
vulnerable. This means that 18%, or about one-fifth of assessed species, are
theoretically threatened with global extinction. Whether we can assume
that unassessed species are equally at risk is an unknown.
That is the global view. At more local, regional levels, the picture can
be even bleaker. Diver surveys at numerous Caribbean locales found few
sharks other than Nurse Sharks. This conclusion stands in stark contrast
to historical accounts of shark abundance in which researchers stated that a
variety of sharks could be “expected anywhere at any time” in the west-In-
dian Caribbean. Today, except for Nurse Sharks, sharks are expected “any-
time almost nowhere.” In the Mediterranean Sea, comparisons going back
to the early nineteenth century indicate significant declines in large sharks,
especially hammerheads, Blues, makos, Porbeagles, and thresher sharks.
Human activities that have resulted in habitat destruction and pollution
have undoubtedly affected shark populations. But overexploitation appears