Map Oceans with Song
Leake, Science Editor
London Sunday Times
from the :
American Association for the Advancement of Science Conference
of the whale has been revealed as much more than just a conversation
between the world’s largest marine mammals. New research
has found that whales use the songs as a form of radar, picking
up echoes from thousands of miles away to build up detailed maps
of the ocean around them.
solves one of the mysteries of marine science — how whales
are able to migrate across thousands of miles of ocean with great
accuracy. It also suggests that they may be more intelligent
than had been realised because the ability to create and interpret
such maps would need powerful brains.
insights came after scientists were granted access to a network
of undersea microphones installed across the north Atlantic by
the US navy to listen out for enemy Soviet submarines. The research
was carried out in Cornwall where the US navy has one of its listening
base at St Mawgan the researchers retuned the underwater microphone
system to listen in to the songs of hundreds of blue, fin, humpback
and minke whales scattered across the ocean. Once they had
identified the animals they used the system to plot their positions
and movements across the north Atlantic.
Clark, director of the bioacoustics research programme at Cornell
University, New York, who led the work in Cornwall, said that
after the animals sang they would wait and listen for the echoes
to return. The noises emitted were so powerful they could
traverse hundreds of miles of ocean before bouncing off a geological
feature and returning to the whales that had made them more than
20 minutes later.
will aim directly at a seamount that is 300 miles away, then once
they reach it, they change course and head to a new feature. It
is as if they were slaloming from one geographic feature to the
next. They appear to have acoustic memories analogous to
our visual memories,” said Clark.
research Clark obtained thousands of acoustical tracks of singing
whales for different species throughout the year. The recordings
confirmed that whales were also using their songs to talk to one
other, again often over vast distances.
a meeting in Washington of the American Association for the Advancement
of Science: “We now have the ability fully to evaluate where
they are and how long they sing for. We have evidence that they
are communicating over thousands of miles of ocean. Singing is
also part of their social system and community.”
The US navy
system is so sophisticated Clark was able to move a cursor around
a screen and listen in on different areas of the Atlantic to find
found one he could fix its location and observe it interacting
with animals hundreds of miles away. Clark listened in to
one “whale conversation” where a creature off Bermuda
appeared to be communicating with another off Newfoundland.
conclusion was that whales must perceive their world on a much
larger scale than humans — feeling themselves as travelling
“with” companions who might be hundreds of miles away
and determining their position in relation to distant continents
and land masses rather than nearby features. But besides
the sound of whales singing, Clark also picked up more disturbing
sounds — the roar made by human activities such as shipping
traffic, oil and gas exploration, and recreational traffic.
with past research suggests that such noises are doubling in intensity
every decade — and that it may be deafening whales.
It is already
well known that loud underwater noises such as those used by naval
sonars or oil prospecting equipment can destroy a whale’s
ability to navigate, often resulting in mass strandings. Clark
believes that such sound pollution may already have shrivelled
the distances over which whales can communicate and find mates.
study published this weekend shows that this new threat to whales
comes at a crucial time with their populations are at an all-time
low because of past human whaling activity.
by Steve Palumbi of Stanford University, attempted to work out
how many whales there were before whaling started. He looked
at the amount of variation in the DNA of whale meat bought in
a Japanese market. The amount of variation in certain types
of DNA is known to reflect the size of past populations. He found
that the modern populations of most species number less than a
tenth of what they once were.
people argue that modern whale populations are recovering and
that we can start hunting whales once again but the DNA tells
a different story: a past with an ocean that was teeming with
whales and from which most have been wiped out,” he said.