Translation 2783

• •
.
" 248
The rignt whales that winter-seiith:of.the Japanese islands
begin moving north as early.as February; .7 keeing to coastal regions
on %heir route. In March or April they arrive at the southwestern
Dart of the island of Honshu, and are'seen there until July. From
May to September they are seen off the east coast of the island of
Hokkaid'&: By May some of them have reached the southern part of the
Kurile Islands, and have even been recorded at 50 0 N (in Boussole
Strait). In the summer-autumn period (September-October) some of
the whales stay in the Kurile Islands area, some move into the Sea
of Okhotsk,' and some go northeast along the coast of Kamchatka to
the Aleutian Islands.and into the Bering Sea. Some whales already
begin to move in the opposite direction in September. That migration
also extends over a long period, sometimes until December.
During the same periods the whales of the American herd are
also migrating. By June or July they are already observed in the
Gulf of Alaska, where they remain, perhaps, most of the time; but
some of them pass through the straits in the Aleutian chain into
the Bering Sea. Their principal habitat in summer is believed to
be the waters near Kodiak Island. Concentrations of the whales are
dependent on the distribution of the plankton on which•they feed.
The whales feed mainly in the uppermost 25-metre layer of
the sea, their chief dietary item being Calanus (especially C.
Plumchrus and C. cristatus) It is estimated that an adult whale
consumes up to 3.5 or 4.0 tons of food every 24 hours.
Mating and parturition take place during the winter months;
gestation lasts for about a year, after which a single calf about
six metres long is born. Lactation lasts for more than six months,
and when the calves are about 10.5 metres long they transfer first
to a mixed diet and then to independent feeding.
The females mate for the first time at a length of about 165
14.0 to 14.5 metres, and the males at a length of 14 to 15 metres.
Recent Japanese data put these figures at 15.0-16.0 metres and
14.5-15.5 metres respectively.
North Pacific right whales do not usually stay under water
more than ten minutes. Their emergence on the surface is accompanied
by emission of a Iwo-jet spout up to five metres high. After making
a se -Pies of e::halations with short intervals between them the whales