In support of below hypothesis, I have repeatedly observed in moribund
captured small cetaceans (in artisanal fisheries settings)
that a peri-mortem posture is maintained after a death struggle as rigor
mortis sets in fast. If dolphins die in a cramped posture,
eg S-shaped, it is very difficult to straighten the body immediately
after death straigas to take accurate axial measurements. These are
observations
in landed cetaceans; in a state of suspension in the water with no
gravity interference, I would expect the likelihood of maintenance
of peri-mortem posture increased.
Now the reason why a wild small cetacean would sustain an unusual
head-above-water posture in the general vicinity of a high-amplitude sound
source, e.g. seismic airguns, we suggested: severe acoustic distress, if
not internal injury. We also suggested it may have a
lethal outcome. Dedicated research is needed.
See: Gray, H. & Van Waerebeek, K. (2011) Postural instability and
akinesia in a pantropical spotted dolphin, /Stenella attenuata/, in
proximity to
operating airguns of a geophysical seismic vessel. /Journal for Nature
Conservation /19: 363-367.
Koen Van Waerebeek
[email protected]
On 12/01/2011 12:40 PM, David Bain wrote:
In the Haro Strait case, the sonar was audible in air while the ship
producing it was over 22 km away. It was over the horizon and hence
not seen at that distance. Mid-frequency sonar is used by both
military and non-military vessels, so could have been what was heard
even if no military exercises were underway. The regular interval
reported is more typical of mechanically generated sound than natural
whistles.
After rescue, I have observed stranded cetaceans rest with their
flukes on the bottom and heads above water. Air in the lungs provides
enough flotation for individuals that otherwise would be negatively
buoyant (it may be that resting like this improves survival
probabilities enough that sick or injured cetaceans have been selected
to come into the nearshore to attempt to recover, and some strandings
occur when they are too debilitated to remain offshore). I'm not sure
how likely it is that that posture could be maintained after death,
but if it died while holding its breath, it would have been in the
described posture until water movement pushed it away.
--Dave
On 12/1/2011 5:56 AM, Jasny, Michael wrote:
In response to one of Alexandros' questions: in at least one incident
involving Navy sonar training (the Haro Strait, Washington, event of
May 2003) witnesses reported hearing sonar whistles above the waterline.
These latest strandings are extremely concerning. It has sometimes
taken governments months or years to publicly divulge information on
intrusive acoustic activities -- including sonar training and seismic
surveys -- after a mass stranding event has occurred. Along with
Giuseppe, I would urge ACCOBAMS and CMS -- and other
intergovernmental organizations that have adopted resolutions on
ocean noise -- to request relevant information from their member
states; and I would urge states to respond as soon as possible.
Finally, this incident underscores the need for meaningful,
habitat-based mitigation for sonar training, seismic exploration, and
other intense sources of ocean noise. It seems clear -- simply on
the basis of prior mass stranding events -- that the eastern Ionian
Sea should be put off-limits to such activities, as were the Canary
Islands to mid-frequency sonar training through the responsible
actions of the Spanish government several years ago. The MPA that
ACCOBAMS has proposed there is long overdue.
Best to all,
Michael
*From:*[email protected]
[mailto:[email protected]] *On Behalf Of *Alexandros Frantzis
*Sent:* Wednesday, November 30, 2011 4:05 PM
*To:* [email protected]; [email protected]
*Subject:* [MARMAM] New atypical mass stranding of Ziphius in the
Ionian Sea,Greece
Dear all,
Once more we have bad news regarding Cuvier's beaked whales in the
Ionian Sea. The local population unit, which has repeatedly been
affected by NATO naval activity (last time in February 2011 east of
Sicily) may be steadily heading towards its extinction...
Today 30 November 2011 at least three Cuvier's beaked whales stranded
alive and atypically in west Corfu, along 23 km of coast. All whales
were led offshore by people who tried to rescue them. One whale died
some 200 m offshore. Another whale, after having swam some 600 m
offshore, returned and stranded once more (if this wasn't a different
animal). It was led once more offshore after the sunset, so no
further information is available so far. The third animal was not
seen after it was "rescued".
*I would like to draw your attention on two "peculiarities":*
*1)* Independent rescuers in two different stranding areas, reported
that they were hearing "whistles" while approaching the single
animals. The "whistles" were heard even out of the water at a
distance of 100 m from the animal (!), and became much louder when
the rescuers entered the water to approach the animal. The rescuers
kept hearing the "whistles" until they left the place, two hours
after the death of the unique whale present! They thought that there
might be other whales calling the stranded animal from further
offshore, although they could observe nothing for hours.
Two independent rescuers (separated by 23 km) described these
"whistles" as "emission"-pause of 10-15 seconds-"emission"-pause and
so on. *I wonder if what the rescuers were hearing was the probable
sonic cause of the stranding*. If you have a similar experience or
knowledge, please share it with us.
The rescuers didn't see any military or seismic survey vessels from
the shore. A fisherman from the area said that today he saw an
"unusual" research vessel offshore that he believes (it is known in
the area that seismic surveys have started or are about to start) was
performing research for oil.
*2)* The whale that died 200 m offshore was found at about 3-4 m
depth at an unusual position (to me at least). Its flukes were on the
sea bed while the beak and part of the head of the animal was out of
the water! For some reason the head could float at surface and the
animal never sunk. *Does anyone has an explanation?
*
Unfortunately no necropsy was performed to the animal that died.
The port-police authorities and local volunteers have been alerted
and we just hope that tomorrow we won't find more animals along the
coasts.
Repeated use of military sonar and now growing seismic survey
activity go on in an area that is critical for the two deep diving
Mediterranean species, the Cuvier's and the sperm whales. In 2007
ACCOBAMS officially proposed the creation of a MPA for deep diving
cetaceans in the eastern Ionian Sea (Hellenic Trench), but nothing
has happened so far.
Best wishes,
Alexandros
--
___________________________________________
Dr. Alexandros Frantzis
Scientific director
Pelagos Cetacean Research Institute
Terpsichoris 21
16671 Vouliagmeni,
GREECE
Tel.: +30-210-8960108
e-mail:[email protected] <mailto:[email protected]>
website:http://www.pelagosinstitute.gr
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