ARGENTINA:
Mystery of the Dead
Whales
By Marcela Valente*
BUENOS AIRES, (Tierramérica)
- It will be difficult
to determine exactly why
the number of whale
deaths has shot up along
the Atlantic coast of
southern Argentina’s
Patagonia region, but
experts studying the
phenomenon are pointing
to poisoning from the
"red tide".
The annual average of
deaths jumped from 40 to
85 in October and
November, according to
the Southern Right Whale
Health Monitoring
Program, conducted over
the past five years by
non-governmental
entities in the southern
province of Chubut.
Numbering around 5,300,
this colony of southern
right whale (Eubalaena
australis) is one of hte
biggest in the world.
They arrive at this
stretch of Argentine
coast between May and
December to reproduce.
They are also an
attraction for
whale-watching tourists.
But the number of whale
deaths this year is the
highest since 1971.
Most are young whales,
measuring up to eight
meters long, and have
been found around the
Valdés Peninsula.
The scientists studying
the matter are looking
at different theories as
they await the test
results of tissue
samples taken from the
dead whales. They don’t
expect the tests to
fully solve the mystery,
but they do expect
additional information
to continue weaving
their hypotheses.
"It will be difficult to
come up with conclusive
results" due to the
advanced state of
decomposition of the
animals analyzed,
biologist Mariano Sirona,
science director of the
Whale Conservation
Institute, one of the
organizations involved
in the program, told
Tierramérica.
The limits on the
studies are evidence of
the program’s lack of
resources, despite the
fact that whale-watching
draws thousands of
tourists to the Chubut
coast each year. Only
two people show up after
a whale is found
beached, trapped on the
sand. There is a lack of
means to act in a timely
and appropriate way when
such tragedies happen.
For the current whale
death crisis, the
program has received
special funding from the
U.S. National Marine
Fisheries Service and
from the International
Fund for Animal Welfare.
According to Sironi, one
of the most discussed
theories is that the
whales are dying from
intoxication. It is
suspected that toxins
from the microalgae that
give rise to what is
known as red tide are
the culprit. The
microalgae can be lethal
for sea birds and sea
mammals that feed on
toxic shellfish.
"In October and November
there was an intense red
tide in Nuevo Gulf,"
said Sironi, referring
to the area where the
most dead whales have
turned up. But he said
it is necessary to wait
for the laboratory
results before making
any definitive
statements.
Veterinarian Marcela
Uhart, co-director of
the monitoring program
and member of the
Wildlife Conservation
Society – another of the
participating
organizations – is
conducting the tissue
sample tests and gave a
preview of the results:
"They are quite meager,
as we expected," she
told Tierramérica.
The most likely is that
the whales were poisoned
by an especially lethal
type of toxin for
mammals, she suggested.
According to Uhart, the
last red tide "was
incredibly extensive"
compared with past
years, but she refused
to jump to conclusions.
She was also cautious in
commenting about the
possibility that sewage
runoff contributed to
the whale deaths.
Nuevo Gulf is near the
city of Puerto Madryn,
and a sewage treatment
plant in the El
Doradillo district flows
into the sea. "We
haven’t seen the young
whales feeding there.
But the it could be that
the mothers do, and
transmit the poison to
their offspring through
their milk," Uhart said.
"If we find a digestive
tract in a good state
(in a dead whale) we
would have a better
idea," she added.
The notion that the
young whales died of
malnutrition has been
ruled out. "The ones we
opened up had a very
thick layer of fat, were
apparently healthy and
well fed," said Sironi.
Also being considered is
a combination of causes,
such as the red sea in
combination with the
wounds that seagulls
cause on whale backs by
feeding on their fat.
Those lesions are an
open door to infections.
"If the toxins depress
the animal’s immune
system, the whale is
more vulnerable to
infection," he said.
The problems of
coexistence of whales
and seagulls have been
on the rise in this
region. "In 1974 it was
one percent of whales
injured by birds, and
the percentage rose to
38 percent in 1990, and
to 68 percent in 2000,"
said the expert.
Although the wounds are
not the cause of death,
they could be the coup
de grace if the animal
is already suffering
from toxins.
The scientists are not
optimistic that the
laboratory tests will
give the answer because
the samples were of such
poor quality.
"Most of the whale
bodies float for several
days, and when they land
on the beach they have
already begun to decay,"
said Sironi.
The research teams
arrive once the
monitoring program
alerts them.
Nadia Mohamed, field
coordinator of the
monitoring, explained to
Tierramérica that "due
to the topography of the
beaches, we can’t access
them all with vehicles.
Sometimes we have to
walk a long way to a
whale beaching site."
"We need four-wheelers,
and radios or satellite
telephones to
communicate, because
there is no cell phone
signal there. And a
boat, because there are
beaches with steep
cliffs that cannot be
reached by land," she
added.
The scientists also need
more staff, wetsuits,
necropsy equipment, and
money for fuel.
Meanwhile, the mystery
will remain unsolved.
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