During the winter in the Crown Prince Gustav Channel in Graham Land, ice tends to form at the northerly end first, thus isolating pools of open water. The pools normally freeze some two months later; but in 1955 this unusual pattern of sea-ice formation cut off nearly 200 whales from the open sea. Originally there were 120 Lesser Rorquals Balaenoptera acutorostrata, sixty Killer Whales Orcinus orca and one Berardius arnuxi. The activity of the whales prevented the pools freezing completely, but there was marked crowding and some unusual photographs were taken.
All the Killer Whales and many Lesser Rorquals disappeared after four months. They may have died or travelled 65 kilometres under the ice to open water. The latter is more likely. However some twenty Lesser Rorquals stayed by the pools for six months and latterly very little if any food can have been available.
The single species of Berardius was shot at by Argentine soldiers and presumably killed.
It is suggested that the initial concentration of whales and also of seals may have been due to a large concentration of plankton.