Freedom Charter’s
Connemara was chartered for two days out of Eden, NSW.
Saturday’s weather was dominated by a moderate SW with
a wind of 15-20 knots and seas of 1.0-2.0m with a 0.5m
swell. There was some rain in the afternoon. Sunday
started fine with 0.5m swell and a light SW wind of less
than 10 knots rising by mid afternoon to about 20 knots
and backing SE.
According to the CSIRO
Sea Surface Temperature website, a warm-core eddy of the
East Australian Current was present offshore with its
southern front about equal in latitude to Eden and the
western extreme skirting the edge of the continental
shelf just beyond the 200m drop off. This
manifested itself as a rise in over 1 degree Celsius
between the shore and the continental slope, peaking at between 18.7 and 19 degrees.
The East Australian Current plays a particularly
important role in dictating the abundance and
distribution of birds, cetaceans (the collective term
for whales and dolphins) and fish off the east coast of
Australia. Warm core eddies, such as the one present off
Eden on the 6th and 7th of November, rotate
anti-clockwise, drawing surface water away from the
coast creating an upwelling as water from beneath is
drawn up to fill its place. This mixing of water layers
brings nutrients to the surface creating blooms of
plankton. These eddies also concentrate the resource
along their edge - if you can find the edge, then there
will inevitably be large concentrations of seabirds and
cetaceans. The centre of these eddies which comprise
warm water from the Coral Sea however, are nutrient
poor. As the East Australian Current strengthens
throughout winter its southern boundary (sometimes
referred to as the Tasman Front) will move further
south. To view further information on the East
Australian Current from the CSIRO website click here.
Many of the birds and cetaceans on Sunday, when the
weather was fine, were seen along current lines in water
depths of between about 150 and 300m. Click on the
figure below to see a map of sightings showing the
position of the warm core eddy (pictured right).
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