In the Southern Hemisphere, Antarctic blue whales occur mainly inrelatively high latitude waters south of the "Antarctic Convergence
" and close to the ice edge in summer.
The convention applies to all Antarctic populations of fish, molluscs, crustaceans and sea birds South of the Antarctic Convergence
(the "convention area").
Shortly after the boat crossed the Antarctic Convergence
, a major zone of depression was rising in the south, on track to wallop the boat with winds reaching sixty knots.
The Antarctic Convergence
, which encircles Antarctica roughly 1,500 kilometres off the coast, divides the cold southern water masses and warmer northern waters.
For oceanographers, Antarctica includes the marine area south of the Antarctic convergence, or Antarctic polar front, between 48[degrees]S and 60[degrees]S.
At the southern edge of the Antarctic convergence there is a great increase in zooplankton density and biomass but these both decrease towards the south.
In 1963 and 1964, scientists on two Antarctic research cruises of the vessel Eltanin found so many specimens of Gigantocypris muelleri in the waters of the Antarctic Convergence
region (where antarctic surface waters and deeper subantarctic waters meet) that they suggested using the creature's presence as an indicator of the area.