- From:
"Bahamas Marine Mammal Survey"
<bmms@mail.oii.net>
-
- Dear
colleagues,
-
- Attached
is my letter to the US Navy concerning high power
military sonars. It is obvious that dead and dying
whales are often found coincident with tests and
exercises employing the sonars, and I have attempted
to explain why. I would appreciate any feedback you
may have on this subject.
-
- Ken
Balcomb
-
- ---------------------------------------------------
-
- 2/23/2001
- Mr.
J.S. Johnson
- Attn:
SURTASS LFA Sonar OEIS/EIS Program
Manager
- 901
North Stuart Street, Suite 708
- Arlington,
VA 22203
-
- Dear
Mr. Johnson:
-
- Thank
you for sending a copy of the Final Overseas
Environmental Impact Statement and Environmental
Impact Statement for Surveillance Towed Array Sensor
System Low Frequency Active (SURTASS LFA) Sonar. Since
my comments to you on the Draft OEIS/EIS (O-26;
Balcomb, November 12, 1999), I have had the unique
opportunity to witness and study a mass stranding of
whales and a dolphin caused by a US Naval Sonar
Exercise in the Bahamas (Pirie, ltr. June 15, 2000).
That incident unequivocally demonstrated the lethality
of high-powered sonars, and it provided the
opportunity to understand how sonar has been
inadvertently killing whales in vast expanses of ocean
around the world.
-
- The
killing is largely due to resonance phenomena in the
whales cranial airspaces that are tearing apart
delicate tissues around the brains and ears. This is
an entirely separate issue from auditory thresholds
and traumas that the Navy has fixated upon. In my
earlier comments, I questioned whether there might be
a problem with injurious resonance phenomena created
by the sonar system described in your OEIS/EIS; but,
now I have seen the problem and can attest to the fact
that there is massive injury to whales caused by
sonar. This is not an exaggerated statement, and I am
reasonably sure that the Navy knows that. Please allow
me to explain what happens to the
whales.
-
- Resonance,
as engineers well know, can dramatically contribute to
shear forces that can be quite damaging; wings tear
off airplanes, bridges gallop, and buildings collapse,
etc. due to unanticipated resonance phenomena which
can afterwards be explained by simple physics and
mechanics. I wondered about tissue damage caused by
resonance, and I specifically asked what the Navy
calculations for lung resonance frequencies of a
beaked whale were at various depths. [You
sidestepped my question by responding generically to
my comment with response 4-4.15].
-
- Subsequent
to my asking you about specific resonant frequencies
and depths, I found that in 1998 NATO and the US Naval
Undersea Warfare Center had already calculated the
resonance frequency of airspaces in Cuvier beaked
whales (Ziphius cavirostris) to be about 290 Hz at 500
meters depth (page H2, SACLANTCEN M-133), which is
almost precisely the middle frequency of LFA (100-500
Hz) described in your OEIS/EIS! That information is
quite important, with specific reference to Technical
Report 3 of your DOEIS/EIS, wherein there are several
citations of Navy sponsored studies that clearly
demonstrated vestibular dysfunction (eg. dizziness,
vertigo) and lung hemorrhage, etc. in laboratory
animals exposed to LFA at their lung resonance
frequency.
-
- In
other words, the Navy has sufficient information
available to know there is at least theoretically a
very serious problem to whales from LFA for even brief
periods of time. The scientific and medical literature
contains numerous examples of hemorrhagic injuries and
death occurring in humans when they are inadvertently
exposed to loud sound, particularly at their lung
(airspace) resonance frequency. Undoubtedly such
damage could also be demonstrated as occurring to
whales if they could be tested and did not sink to the
bottom of the ocean when they die.
-
- The
NATO report I referred to for resonance calculations
was concerning the mass stranding of at least twelve
Cuvier's beaked whales in Greece on 12 May, 1996
coincident with a NATO acoustic trial employing both
LFA (450-700 Hz) and mid-frequency sonar (2.8-3.3
kHz). Superficially, in reading that report one might
wonder whether either frequency range caused the
whales to strand in Greece, since neither matched the
reported resonance frequency in that instance for
Cuvier's beaked whales airspaces at an arbitrarily
chosen 500 meters depth.
-
- However,
also in that NATO report there were formulae of
Minnaert and Andreeva presented that indicated the
resonance frequency of airspaces can be calculated,
within acceptable limits, from their volumes. Lung
(airspace) volumes vary individually, and they also
vary with depth, hence their resonance will vary
accordingly. Nonetheless, the Navy used the formulae,
and so did I. You could, too.
-
- In
order to perform these airspace resonance calculations
correctly, one must know or take into account the
following:
-
- a.
Boyles Law PV=3Dconstant; therefore, lung (airspace)
volume will decrease with increasing depth due to
increasing pressure.
-
- b.
Lung (airspace) volume at the surface.
-
- c.
Functional anatomy of deep-diving beaked
whales.
-
- It
is the volume of air in the individual pterygoid sacs
and the laryngeal airspace, not the lungs, for which
resonance should be calculated. Below about 100 meters
depth virtually all of the air that was in the lungs
at the surface is forced into laryngeal and cranial
airspaces, wherein its volume continues to decrease
with increasing depth until it has a total volume less
than that of a football (compressed from, for example,
a 100 liter lung full of air). The two largest of
these remaining airspaces (pterygoid sacs or sinuses)
are bilaterally adjacent to the earbones and the base
of the brain (via the large foramen for the oversize
VIII cranial nerve); and, their diminishing volume at
depth is compensated for by retia mirabilia (a corpus
cavernosum-like vascular network extending to the
middle ear). [Envision the football-size airspace
further squeezed to the size of a ping-pong ball with
1500 psi air pressure, now tucked between the ear
bulla and the skull on each side of the head, thinly
separated from a bag of blood next to it on the soft
side. Following the Navys example and the formulae of
Minnaert and Andreeva, the frequencies of LFA (and
powerful mid-frequency sonars) precisely match these
cranial airspace resonance frequencies in these whales
at predictable depths where they normally forage
(500-1500 meters). [Now envision rapidly
compressing and decompressing the ping-pong ball many
times per second (sound and sonar travels as
compressions and decompressions of the medium through
which it is passing) until ultimately the amplitude is
exaggerated by resonance.] The result is both
astonishing and bloody. Many whales died due to this
sonar resonance in Greece and in the Bahamas.
Unfortunately, the Greek mass stranding incident
passed into relative obscurity because the SACLANTCEN
Bioacoustics Panel missed the crucial point of
matching resonance in critical airspaces; and, because
suitable specimen materials were not collected for
discovering the problem. At least seven beaked whales
died in the Bahamas stranding that witnessed; and, I
had opportunity to examine four of the carcasses by
necropsy.
-
- All
of these whales that were examined evidenced similar
lesions, i.e. hemorrhage in the acoustic regions of
the cranium and mandible and in tissues adjacent to
airspaces around the earbones (NMFS ltr. June 14,
2000). One fresh specimen that was examined by ultra
high-resolution computerized tomography (UHR-CT)
evidenced a subarachnoid hemorrhage (brain hemorrhage)
with a direct path to the ear hemorrhage. This same
specimen evidenced lung hemorrhage and laryngeal
hemorrhage upon dissection. These hemorrhages are of
the type of damage reported in laboratory animals
exposed to LFA at lung resonance frequency, and they
strongly corroborate the theoretical explanation of
such injuries in these whales. In order to approach
this problem empirically, prepared an endocast of the
pterygoid sac of one of the Cuvier's beaked whale
specimens from the Bahamas incident and determined
that its volume closely matched the calculated volume
used for the resonance formulae beginning around 170
meters depth where it would resonate at 470-590 Hz
(within LFA range). At greater depths the resonance
frequency of this pterygoid sac would increase to
around 3.5 kHz at 1400 meters. Because most of the
hemorrhage observed was in tissues adjacent to the
pterygoid sac at its most posterior end where it is
enveloped by retia mirabilia in a unique cul-de-sac of
sesamoid bone and dense earbone that keep this space
open during the deepest part of a dive, consider the
evidence compelling that resonance of this particular
airspace is a real problem.
-
- Again
with respect to the Bahamas incident, have read (Pirie
ltr.) that the sonars employed were standard hull
mounted and operating at 3.5 kHz @ 235 dB re 1uPa SL
and 7.5 kHz @ 235 dB re 1uPa SL. What is important, of
course, is the received level (RL) of these projected
frequencies at the whales receiving location when
first impacted by the sound. I have been told that the
Bahamas situation may have been complicated by
oceanographic conditions and other factors that could
have resulted in a surface sound duct in which most of
the acoustic energy was trapped; but, I also
documented that the whales stranded over an area 200
kilometers across! In this case, if the Navy report of
several surface ships using standard, hull-mounted
sonar operating within normal mid-range frequencies,
power outputs, and duty cycles is true; and, if within
a range of 1000 meters from the ship in this surface
duct, the sound level from the sonars dropped in
intensity to less than 180 dB is also true; then, it
is not possible that all of the whales that stranded
over such a huge area experienced received levels (RL)
of these sonars above the alleged safe limit of 180 dB
(not enough ships; too large an area). I conclude that
the whales in the Bahamas incident were adversely and
lethally impacted by sonar pings at received levels
well below the 180 dB re 1uPa considered safe for
whales, and this was due to the aforementioned
resonance problem. These pings were of much shorter
duration (1/10th second) than the proposed LFA pings,
I might add. This sonar impact at received levels well
below 180 dB is likewise well documented in the Greek
incident reported in the NATO report SACLANTCEN M-133
(Annex G). The first whale to strand did so 40 km from
the ship one hour after the acoustic trial commenced.
If one takes into account how fast a beaked whale can
swim (about 15 km per hour, maximum), it must have
been at least 25 km from the ship when the first of
its 238 four-second pings was transmitted! At that
distance the RL was calculated by the Navy (NATO,
Annex G) to be approximately 150 dB! The Bioacoustics
Panel overlooked this important bit of evidence of
received level for impact.
-
- Therefore,
based on two significant mass mortality events (Greece
and the Bahamas) the body of evidence indicates that
not only is resonance with LFA and sonar frequencies a
problem for beaked whales, the sound pressure level of
180 dB RL is demonstrably not safe, and it is probably
not safe for other cetaceans (two minke whales and a
dolphin also stranded in the Bahamas incident).
Aversion and/or physiological damage evidently and
repeatedly occurs in beaked whales at levels of
somewhere between 150 and 180 dB RL (probably nearer
the former) of either low frequency or mid-frequency
sonar signals in the whales normal habitat.
-
- Clearly,
the impact of high-powered rapid-rise acoustic energy
(such as sonar), particularly at airspace resonance
frequency, on these animals is occurring at
significant distances well beyond the current
mitigation distance (1-2.2 km) used by the Navy. These
impact distances can be easily calculated, and they
are more like 20 to 100 kilometers, and more well over
the horizon of shipboard observers.
-
- Cuvier's
beaked whales were reasonably common in our field
study area prior to the Bahamas incident; we had
photo-identified about thirty-five of them, many
repeatedly. We typically sighted small groups of these
whales a dozen or more times per year in any month of
the year. But since the Bahamas sonar incident we have
seen this species only once in an entire year, and
that was a sighting of two previously unidentified
whales (i.e., new arrivals to our study area) about
two months after the sonar exercise. None of the
whales that were rescued have been seen again. In
retrospect, it is probable that all Cuviers beaked
whales in the region when the naval exercise commenced
were killed by the sonar, whether or not they were
returned to sea by well-wishers pushing them off the
shore. Considering the observed damage to the whales
that stranded and died, and the short time period
between stranding and death, the NMFS statement that
the whales died from stranding is patently absurd. The
whales that we observed swimming toward shore and
stranding were only temporary survivors of an acoustic
holocaust that can be likened to fishing with
dynamite.
-
- In
summary, I consider the Navy's Final OEIS/EIS fails to
justify the deployment of SURTASS/LFA with negligible
or mitigable potential to harm marine mammals,
therefore I recommend the No Action Alternative. In
fact, there really is no Alternative 1- the Navy
cannot reasonably mitigate the problem using visual,
active acoustic or passive acoustic monitoring, nor
can the Navy redesign the whales; at best it can only
reconsider and perhaps redesign the SURTASS/LFA
system. Considering that the facts of multiple whale
deaths and their almost certain cause are now known to
me, I cannot legally or morally support any
recommendation to deploy SURTASS/LFA as proposed, and
I trust that will be your conclusion as
well.
-
- Sincerely,
-
- Kenneth
C. Balcomb, III
- Whale
Biologist
-
- Cc:
Office of Protected Species, NMFS
-
CNO OP95
-
US Marine Mammal Commission
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