|
Tuesday 11th January 2006
RVIB Aurora Australis
59 S, 82 E
 The marine science
voyage that I am participating in as a whale observer is known as ‘Broke
West’. It is ‘Broke’ because the ship got broken during the
first survey of this kind! (This became known as Broke East) and
‘West’ because we are working in the West Antarctic region. Towards
the end of our voyage we will be visiting the Australian stations, Mawson and
Davis, neither of which I have been to before.
Our voyage is
international and multi-disciplinary in nature. As well as physical
oceanographic studies, we are investigating bio-geographical cycles, conducting
a detailed krill survey and monitoring cetaceans (visually and acoustically),
seals, seabirds and sea-ice. The survey area is made up of blocks in which the
ship moves systematically from north to south, towards the coast, along a bit
and then from south to north, away from the coast, below 62 S and between 30 E
and 80 E. The area for which we are heading is managed under the Convention for
the Conservation of Antarctic Marine Living Resources (CCAMLR), and is called Area 58.4.2.
We will be trawling for krill at set stations along these transects, on other
legs we will be conducting acoustic sampling surveys. An aim is to provide
CCAMLR with the data to produce an updated catch limit for the krill fishery in
this area. Although no fishery currently exists, increases in the use of krill
for many uses, and primarily feeding of aquaculture (fish bred in cages). This
is already the largest fishery in the southern ocean. As aquaculture is
burgeoning around the planet, and as krill fishing technology improves, we can
expect this fishery to increase substantially in future years. This may of
course have knock-on effects to all the krill dependant predators, including
penguins, seabirds, seals and cetaceans.
We have now successfully
completed a test CTD (Conductivity, Temperature and Depth) in the Antarctic
Circumpolar Current (ACC). The CTD is deployed from the side of the stationary
ship at various positions along our transect lines. It is an incredible piece
of equipment that collects water samples every few hundred metres change in
depth from the surface to the ocean floor. These samples are then analysed to
measure and monitor changes in CFCs, nutrients, oxygen, temperature and
salinity. During our 72 days at sea, once we have reached the survey area, we
will be conducting 111 CTDs at various set stations on alternating transects,
each leg heading towards the ice. Amongst the many questions being asked on
this voyage, some of the most important relate to the sources and climatic
changes in bottom water, surface circulation and carbon cycles.
Whale
observations and acoustics will be uninterrupted on the opposing transect legs
when we move out away from the Antarctic coast towards open ocean. These
transects have been designed to take the ship over areas of interest – the
shelf, slope and areas of the abyssal plain, as well as the Kerguelan plateau
to begin with. We will be crossing a number of Gyres, or large circulating
bodies of water, which are important to our studies as krill are expected to be
found within them.
Sarah Dolman/WDCS©
Image shows the
whale team onboard the Aurora Australis from left: Paul Hodda (Team Leader),
Sarah Dolman (WDCS), Maria Garcia, Marty Gent, Zachary Schakner and Marguarite
Tarzir from Deakin University, Warrnambool, Victoria, Australia.
Back to Antarctic
2006 |
