and Seismic Exploration: A Major Headache for Whales
of Sound-based Technologies for Ocean Exploration Has Scientists
the Strait of Juan de Fuca in 2003, the USS Shoup (horizon)
deployed its mid-range sonar in the presence of killer whales.
Whalewatchers reported seeing distressed behaviour from the
Centre for Whale Research/Ken Balcomb
trying to function with a jackhammer thundering on and off outside
your window, night and day.
Barrett-Lennard, Senior Marine Mammal Research Scientist at the
Vancouver Aquarium Marine Science Centre, uses this analogy to describe
the deafening torment endured by whales in areas of oil and gas
even more detrimental to marine mammals than to terrestrial creatures,
as hearing is their primary sense. And because sound travels so
well in water, the noise could be 50 kilometres away but will still
seem like it is just around the corner.
noise is not a new phenomenon. Natural noises occur in the oceans
constantly, including earthquakes, storms and singing baleen whales.
However, it is the man-made noises that are causing problems: in
particular, military sonar and the use of seismic testing for oil
and gas exploration.
uses sonar to detect enemy submarines. Sounds are emitted across
the ocean and bounce back when they hit an object. The lower the
frequency of the sounds, the further they travel. At present, mid-frequency
active sonar (MFA) is in widespread use and low frequency active
sonar (LFA) is being developed for use by the US and its allies.
LFA sonar can generate one of the loudest sounds that it is possible
for humans to make.
use their own form of sonar – echolocation – to navigate
and to find food. They also use sound for communication. The loud
and far-carrying noise of sonar is thought to disrupt the whales’
ability to navigate, forage and communicate. It is also believed
to cause the whales to panic, inducing strandings and collisions.
sonar can cause whales to make a dramatic change in behaviour. On
hearing sonar, whales may dive or rise deeply and rapidly. This
can cause a form of decompression sickness, also known as ‘the
bends’, resulting in sometimes fatal damage to the lungs,
brain and ears.
Whaling Commission (IWC) recently released a report that backs up
previous claims of the harm sonar can do. The report suggests that
the noise produced by the military is damaging to cetaceans (whales,
dolphins and porpoises) and in particular, rare beaked whales.
cites recent cases, such as the unusual behaviour in Hawaii of 200
melon-headed whales (Peponocephala electra) in July 2004.
These typically deep-water whales were observed swimming in a tight
circle in shallow water just 100 feet from shore, showing clear
signs of distress. One of the whales was later found to have died.
This bizarre and near-stranding behaviour coincided with a U.S.-Japanese
naval training exercise.
case documented the mass stranding of 17 cetaceans in the Bahamas
in March 2000. Six of the dead animals, which included five Cuvier’s
beaked whales and one Blainville’s beaked whale, were found
to have experienced acoustic or impulse trauma that led to their
stranding and subsequent death. The strandings also coincided with
ongoing Naval activity using MFA sonar in the area.
sonar exercises have taken place, mass strandings and whale mortalities
have occurred. These include cases in the Haro Strait off the coast
of Washington State, the Canary Islands, Madeira, the U.S. Virgin
Islands, and in Greece.
numerous scientific studies and reports proving the damaging effects
of sonar, the US Congress passed a new bill in November of last
year that will allow the Secretary of Defense to permit the Navy
to use sonar wherever and whenever they “need” to.
of conservation groups, including NRDC (Natural Resources Defense
Council) and The International Fund for Animal Welfare (IFAW), are
threatening to sue the US Navy. They say the military’s use
of mid-frequency sonar violates laws imposed to protect marine mammals,
such as The Marine Mammal Protection Act, set up in 1972.
researchers use spectrograms like this one to analyze the
calls of whales and dolphins.
source of man-made marine noise is ‘seismic exploration’
or ‘seismic testing’, which is used by the oil and gas
industry to detect the presence of fossil fuels underwater. It is
similar to sonar in that both rely to varying extents on making
sounds and listening for echoes. However, seismic exploration takes
advantage of the fact that sound penetrates objects and surfaces
to different degrees, depending on their geological or biological
makeup. This enables engineers to locate oil deposits below the
sonar devices measure distances (the time interval between a sound
pulse and its echo), seismic sounds continue for long periods and
provide more of a chronic threat that can drive cetaceans from their
are currently condemning plans by the Shell corporation to drill
for oil in the Russian Far East. The proposed construction of
an offshore drilling platform and the installation of a seabed pipeline
near Sakhalin Island could threaten the survival of the area’s
western gray whales, of which only 100 remain world-wide.
there are fears that a 32-year moratorium on oil and gas exploration
off the BC coast may soon be lifted. As well as the considerable
underwater noise that this would cause, there is also the risk of
an oil spill. If the moratorium is lifted, exploration and drilling
would take place in the Queen Charlotte Basin, which is home to
endangered species such as the blue whale, sei whale, and North
Pacific right whale, as well as killer whales, fin whales, beaked
whales, dolphins and porpoises.
to Dr. Barrett-Lennard, if things are allowed to continue the way
they are going, the outlook for marine mammals is not good.
as a form of chronic environmental degradation is a relatively new
notion,” he says, “but it is my opinion that seismic
exploration and the use of sonar are two of the greatest threats
to cetaceans at present, and all the indications are that they are
going to get worse.”
Pamboris is a British freelance
wildlife writer with five years' experience
at the BBC's Natural History Unit.