The night-walkers of Uganda

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Shark species face extinction amid 
overfishing and appetite for fins
Call for marine reserves to protect migration 
hotspots as scientists fear decline will affect
other species
Alok Jha in Boston 
February 18, 2008
The number of sharks in the world’s oceans is 
falling rapidly. Scientists say that fishing and 
hunting sharks for their fins, known as ‘finning’, 
are the main reasons for the fall in the shark 
population. Nine more species of shark will 
soon be on the list of endangered species. One 
of these species is the scalloped hammerhead 
shark. Its numbers have fallen by 99% over 
the past 30 years in some parts of the world. 
The World Conservation Union (IUCN) list 
of endangered species will list the scalloped 
hammerhead shark as endangered worldwide.
“Sharks are definitely at the top of the list of 
marine animals that could become extinct during 
our lifetimes,” said Julia Baum of the Scripps 
Institution of Oceanography in California and a 
member of IUCN shark specialist group. “If things 
don’t change, some of these shark species will 
become extinct in the next twenty or thirty years.”
At a meeting of the American Association for the 
Advancement of Science in Boston, Baum said 
that as well as the scalloped hammerhead, other 
shark species will be on the IUCN endangered 
list later this year. They include the smooth 
hammerhead, short-fin mako, common thresher, 
big-eye thresher, silky, tiger, bull and dusky. 
There are already 126 species of shark on the 
IUCN’s list.
“People think that a worldwide species can’t 
become extinct because if they are in danger 
in one part of the world, surely they’ll be fine 
in another part,” said Baum. “But fisheries now 
cover all corners of the earth and the fishing is
so intensive that these species are in
danger everywhere.”
Studies have shown that all shark populations in 
the north-west Atlantic Ocean have fallen by an 
average of 50% since the early 1970s. Numbers 
of sharks can fall very quickly because they take 
a long time to grow to adult size - 16 years in the 
case of a scalloped hammerhead. The fins of 
hammerhead sharks are a very popular food in 
China and can cost as much as £140 a kilogram. 
Until 20 or 30 years ago only rich people ate 
shark fin in China, said Baum, but in the last 
25 years the middle class in China has grown 
and so has the market for shark fins. Shark 
populations in the oceans of the world have fallen 
by 90% as a result of fishing and by almost 99% 
along the US east coast.
When the number of sharks falls in a particular 
region this can have a very bad effect on the 
local marine ecology. In one example, Baum 
found that a major fall in the numbers of 
sharks in the north Atlantic after 2000 allowed 
populations of the sharks’ main food, cownose 
rays, to increase rapidly. Then the large numbers 
of cownose rays destroyed the bay scallop 
populations around North Carolina. “There was 
a fishery for bay scallops in North Carolina that 
operated for over a hundred years but it closed 
down in 2004 because of cownose rays.”
People are free to catch sharks in international 
waters, but Baum supports a United Nations 
resolution for immediate limits on catching sharks 
and a ban on shark finning. Sonja Fordham, of 
the Shark Alliance said: “Fishing has a really bad 
effect on shark populations. Worried citizens can 
really help by telling their fisheries ministers that 
they support limits on catches.”
Conservation efforts for sharks will focus on 
hotspots where sharks gather during migrations. 
Peter Klimley of the University of California found 
that scalloped hammerhead sharks migrate along 
fixed ‘superhighways’ in the oceans, swimming 
between a series of sites near coastal islands 
from Mexico to Ecuador. “Hammerhead sharks 
are concentrated at underwater mountains 
and offshore islands,” he said. “So, if we have