[A-List] Scorched Earth: disappearing sharks

["Michael Keaney" <michael.keaney@xxxxxx>]

It scared you stiff, now the great white faces its own crisis

Report reveals catastrophic drop in shark populations

Tim Radford, science editor
Friday January 17, 2003
The Guardian

Sharks - those sleek and ancient predators of the seas - have taken a steep
dive. Populations of the great white shark, scalloped hammerhead and
thresher have fallen in the north-west Atlantic by up to 90% in the past 15
years, according to research released today.

Sharks are history's survivors - they have been around far longer than
dinosaurs, mammals, fish, reptiles or birds. Palaeontologists recently
unearthed the jaws of a primitive shark that dated back 400 million years.
But the silent cruising beasts could be on the way to oblivion, thanks to
overfishing.

Writing in the US journal Science, a team of scientists led by Julia Baum,
of Dalhousie University in Halifax, Nova Scotia, reveal the results of an
analysis of the logbooks of American long-line fleets that hunt tuna and
swordfish in the Caribbean, the Gulf of Mexico, the Florida coast, the
Sargasso sea and the north central Atlantic. Long lines carry up to 550
hooks apiece and logbooks should record sharks that are also caught.

"We estimate that all recorded shark species, with the exception of makos,
have declined by more than 50% in the last eight to 15 years," the
scientists report. They warn that existing measures to save species,
including planned marine reserves, will not be enough to halt the decline of
the threatened species. The existing protection for other large marine
predators, such as sea turtles and tuna, should be extended to sharks as
well.

Their research confirms a growing overall picture, on both sides of the
Atlantic, of mounting problems for marine predators. The Atlantic halibut
has all but disappeared in many areas, while pelagic fish in some waters
have been reduced to 15% of what were healthy populations. Just as big cat
numbers provide a clue to the diversity of life in the forests and
savannahs, shark numbers provide a snapshot of life in the deep.

"Sharks are one of the best natural barometers to indicate the health of our
seas and oceans. If sharks do not exist it spells bad news," said Ian
Fergusson, of the International Union for the Conservation of Nature.

Sharks, skates and rays are all elasmobranchs, as distinct from bony fishes.
They take a long time to mature, and produce few young. Once a population
starts to decline, it becomes vulnerable to extinction because adults
disappear before they can replace themselves.

But the catch, for researchers, is that the Atlantic is huge, deep and
opaque. They must use indirect ways to monitor shark populations. The
fishing fleets' logbooks provided the only consistent data of shark numbers
year by year. These logbooks told an alarming story, revealing that the most
pronounced decline was in the ham merhead population, which had dropped by
89% since 1986.

White sharks - the great white shark was the villain of Steven Spielberg's
thriller Jaws, and is one of the few species known to attack humans - showed
an estimated 79% decline. In some areas, no white sharks had been reported
for a decade. Tiger shark catch rates fell by an estimated 65%, and thresher
sharks by 80%. Blue shark populations had fallen by 60%, and the oceanic
whitetip shark by an estimated 70%.

This is part of a much larger picture of accelerating extinction rates. A
quarter of all mammals and at least one bird species in eight are threatened
with extinction because of human activity. Up to 30% of terrestrial plants
are also at risk.

Conservative scientists calculate that species are vanishing at 1,000 to
10,000 times the average through the history of life on Earth, with some of
the most dramatic losses occurring in the oceans. Fish ing fleets have have
all but extinguished the cod in once-rich Atlantic waters, and trawlermen
who used to be able to hug European coasts are now ranging as far as the
Antarctic for commercial catches.

"On this side of the Atlantic, things are just as bad and probably worse. On
the US coastline there is actually a fisheries management plan, which has
been in force for a number of years now to manage shark fishing. Some
species are completely protected by law," said Mr Fergusson. "We have a
bigger issue here. There is scientific attention to the problems. It is not
as if there is nothing to go on. But the regulation of the fisheries here is
minuscule."

Sharks have always been accidental victims of long-line fleets. Once caught
they are usually killed and dumped at sea. But now they could become
deliberate targets.

"Spain takes an awful lot of sharks, and lands huge piles of them at
Algeciras next to Gibraltar," said Mr Fergusson. "Sharks suddenly are now
worth money. There was a time when they were just a pain in the neck but now
they are worth money on their own. The fins of some sharks are worth
hundreds and hundreds of dollars in the Far Eastern import trade."

In 2000, according to the shark attack file kept by the University of
Florida, there were 79 unprovoked attacks on humans worldwide, the largest
total ever recorded. However, more people were killed by lightning that year
in the US alone. The shark inspires fear, but it remains at the mercy of
humans, according to Mr Fergusson. Decades of abuse and fisheries
mismanagement had led to the decline of many species in the Mediterranean,
including the great white, first recorded more than 2,000 years ago by
Aristotle.

"There is a terrible irony here," he said. "We may see the white shark
disappear from the place where science first described it. And that would be
the most appalling comment on the way we manage our oceans."

>From killers to plankton eaters

· Sharks, skates and rays fall into a group called elasmobranchs. They have
no bones, only cartilage. There are more than 1,100 species, including 800
varieties of shark. They have no swim bladder, and must move or sink

· According to the UN's food and agriculture organisation, the shark catch
in 2000 was 828,364 tonnes - an increase of 20% since 1990

· Some sharks eat plankton. The basking shark grows to almost 14 metres. The
whale shark is the world's largest fish and lives to more than 60. It takes
30 years to mature

· Although sharks made 76 recorded attacks in 2001, there were only five
deaths, compared with 12 the previous year. Surfers were the most frequent
victims

·Florida scientists have devised a quick genetic test to identify the dried
fins of blue, dusky, longfin and shortfin makos, porbeagle and silky sharks,
collected for sharks fin soup

· Health shops have sold shark cartilage as a preventive because of claims
that sharks never get cancer. In fact the US national cancer institute has a
register of 40 cases of tumours in sharks, skates and rays

· MSI-1436 is a natural compound from the cholesterol in the liver of
dogfish. It suppressed appetite and lowered bodyweight in rodents. A weight
loss drug could be in trials this year

· Squalamine, also found in the dogfish liver, stops the growth of the new
blood vessels that feed tumours, according to scientists at Johns Hopkins in
Baltimore