Dear Julio and
Marmamers
I just returned from
Mundo Azuls first month of field work photo-identifying bottlenose dolphins in
the area between Perus Capital Lima and the Island Asia (100 km of coastline)
and the area between Paracas and Tambo de Mora (40 km). According to our
preliminary analysis of the several thousands of pictures taken, in the first
area we managed to determine several distinct populations with a total of at
least 180 dolphins. In Paracas/Pisco we managed to photo identify at least 85
dolphins with some aditional ones in the area between Pisco and Tambo de Mora. I
would like to confirm Julios observation. Of the 85 dolphins we identified in
the area Pisco/Paracas, which is heavily afected by contamination, at least 16
of the 85 dolphins we encountered showed this skin condition. Diving studies of
Mundo Azul in 2004 and 2006 collecting a total of 400 bottom samples and
invertebrate samples have shown that a great area (approximately 15 square
kilometers within the bay) are near biologically dead or bilogically dead, with
the bottom being covered by a thick layer of gelee like organic matter
(information concerning this contamination, satelite images and research results
can be obtained on our english web site within the part on marine contamination
- www.mundoazul.org - click on the
british flag in the upper right corner in order to enter in the engish version).
This year we also could confirm a heavy contamination with petroleum accumulated
in the seafloor south of Pisco.
In the other
populations that we identified so far we could not find one single specimen
showing a similar skin condition. With exemption of a small group near the
capital in an area where a main sewage pipe enters contaminating the sea with
the sewage of a few milion people. We do not yet have a lot a pictures from this
group as sea conditions during our stay in the are have been very tough but the
few pictures we were able to take so far showed at least one dolphin with a
similar skin contidion like the dolphins in Paracas. From this we can conclude
that there definitely can be assumed a connection between the contamination and
the skin disease, as Julio points out. As our field investigaion in the area
goes on I am sure that I can provide more input for the list on this topic. I
therefore would be also very interested to get more information on this type of
skin disease and would like to ask listmembers to also forward their information
to our emal: [EMAIL PROTECTED]
I would like also to
raise another interesting topic concerning the Paracas population and ask list
members for literature and comments on similar behavior in other
populations. The bay of Paracas is very shallow. We could observe dolphins to
perform the following feeding behavior in water depths of 1.5 to 5 meters. A
single dolphin or groups of up to three dolphins swam in tight circles with the
snout aparantly in the sediment and the fluke out of the water (sometimes
vertically) steering up a lot of sediment. We thought of several possible
explanations: they might have fished bottom dwelling fish or have steered up
sediment in order to confuse fish and catch them in the murky water caused by
this behavior - it could also be that the steered up sediment and organic
material attracts fish which then can be caught by the dolphins. The later seems
a probable hypothesis as we could also observe a similar behavior related to
fishing boats. Artisan fishing boats entering the harbor of Paracas are used to
pump out their bilges and throw the fishblood and remains into the water when
cleaning their wooden boats. This organic material seems to attract fish which
then is consumed by the dolphins. We observed that whenever a fishing boat
enters in the port a huge number of dolphins (up to ten) follows the boat and
then fishes around the anchored boat witin the water that is contaminated with
the organic waste, while fishermen continue to throw over
board bloodwaer and clean their boats. I would be very interested to learn
if similar behaivors have been observed in other places. I am sure that Julio
can confirm this behavior and maybe would be interested to also receive
information from listmembers about similar fishing behaviors in other
places.
All the
best
Stefan
Austermühle
Mundo
Azul
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