ON THE NORTHERN EXTREME OF THE PACK-ICE EDGE
OBSERVED BY WHALING VESSELS IN THE SUMMER
OF THE ANTARCTIC SEASONS 1957 /58-1962/63
AKITO KAWAMURA*Whales Research Institute, TokyoAND
TERUHIKO FURUNO
Nippon Kyodo Hogei K.K., Tokyo

During the cruise of exploratory fishing and scouting for sei whales by the freezer,
Eiho Maru of Hokoku Suisan K.K. in 1971/72 Antarctic season, one of the authors(A.K.) got acquaintance with Teruhiko Furuno, skipper of one of the whale catchers
belonging to Nippon Suisan K.K. that has been sending a couple of whaling fleetsto the Antarctic for many years since 1946. Furuno, one of present authors is awell experienced captain in the Antarctic whaling operation, and is very skillful
as the skipper of scouting boat. While we had been on high seas in the Southern Ocean, Furuno kindly permitted me to see and reproduce his important dataon the northern extreme of the drifting pack-ice which have been observed during
the whaling seasons in some Antarctic regions where the whaling has been mostintensively conducted through the past several seasons. The present material issolely based on the data recorded by Furuno.
Since its re-establishment of the pelagic whaling operation to the Antarctic
Ocean in 1946/47 season onward, Japan has successively sent thirty-one times ofwhaling expeditions to date. Each expedition during the seasons of 1957/58 to
1962/63 was operated by using six to seven mother ships, each of which usually accompanied about nine to ten catcher boats. In the whaling grounds those catcher
boats are generally dispersed widely over the region to be harvested in order tolocate the best place as the whaling ground. They scout about the region bylooking for the school of whales, and they also try to locate the position of the packice edge as much as possible along the steaming course since it is one of the mostimportant sea conditions for the stable whaling operation.
It may be easy to suppose that each whaling company keeps such kind of data
under their control, and usually those data are placed beyond the public use by reason of confidential material only be opened within the companies. Under these circumstances the figures shown in this report are considered one of those ' exhumed 'material showing the location of northernmost extreme of retreating pack-ice
during the austral summer. The figures are based on day-by-day reports ~x­changed between whale catchers worked out for the corresponding seasons. Although the behaviour of the pack-ice in the high Ant~rctic Ocean is observed rather* Present address: Faculty of Fisheries, Hokkaido University, Hakodate, Hokkaido.
Sci. Rep. Whales Res. Inst.,
No. 29, 1977, 137-141.

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KAWAMURA AND FURUNO

easily at present by using the artificial satellite systems, the material provided inthis report may be of interests for many purposes as the evidence of past years.
Although the material provides only a fraction of knowledge on the movementof pack-ice in time and space, one of distinctions be noted may be found in theirsimultaneousness in obtaining the positions of the pack-ice at the different localities,i.e., they were located within a relatively short intervals of the days, and this would
make ones enable to estimate how fast the pack-ice as indicated by the location ofnorthernmost extreme shifts back and forth. Still more, ~he material would be
helpful for estimating the area of ice coverage as to the environmental conditions
for the marine life in the regions such as the figures given by Mackintosh (1970).
Apart from these the present data may provide a reference in checking the monthly
mean position of the pack-ice edge that was reported previously (e.g. Mackintosh

19571958-··1959·-·1960-1961 ---1962 -------)

Fig. 1. Northern extreme of the pack-ice edge in November.
denotes the date of observations.

Numeral in the figure

Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

PACK-ICE IN THE ANTARCTIC139

DECEMBER19571958-··1959-·19601961--1962 ·······lO)

Fig. 2. Northern extreme of the pack-ice edge in December.
figure denotes the date of observations.

0Numeral in the30E

JANUARY
1958 -··1959 --1960 -Fig. 3. Northern extreme of the pack-ice edge in January.
denotes the date of observations.

Sci. Rep. Whales Res. Inst.,
No. 29, 1977.

lO\i\-t++++-++--+-++++-+++++-++10rn

Numeral in the figure

140

KAWAMURA AND FURUNO
30W

030

FEBRUARY
1958 -··1959 - · 1960·-\t-t-14-t-+-t-+-+-H-l-H-+-+-f.-HH-l~Fig. 4. Northern extreme of the pack·ice edge in February.
figure denotes the date of observations.

rn

Numeral in theand Herdman, 1940; Treshnikov, 1967).
Following are the notes based on the communications with Furuno, and theseshould be took in mind when one consults a matter with the figures demonstrated(Figs. 1-4):
1) The whole data for making those figures were obtained by all whalingboats participated to the Antarctic whaling seasons under the flag of the Nippon
Suisan K.K. Two kinds of whaling boats may be distinguished by the purpose of
their use; the first one is the whale chaser of actually catching the whales and thesecond one is the scouting boat which often heads for far distant region in searchof possible whaling ground to be harvested in near future. Furuno has been
worked out as one of the skippers of those scouting boats throughout the mostof his Antarctic life.
2) It was very often or usual that the ship's position was hardly determined
for several days or even more than a week due to ill conditioned weather, andtherefore there were no other ways but find the ship's position temporarily by theso-called dead reckoning. However, the position was corrected as much as possible
whenever the weather permitted to have sun shot.
3) It may be said empirically that the deviation of ship's position due _todead reckoning by rough weather would be usually somewhere around 5 to 6
nautical miles a day from the true position.
4) It was, however, very calm usually in the southern region close to thepack-ice edge, and most of the suggested positions in the figures could be consideredcorrect enough for the purpose of general use.
5) A slight ocean current was noticed in the regions close to the pack-ice,but there was strong current at times when the ship positioned at some distance,
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PACK-ICE IN THE ANTARCTIC

141

say, 10 to 20 miles off the ice limit though it varied considerably by the place andthe seasons.
6) Although there seems to be considerable varieties in the state of pack-ice
such as ' open ', ' close ', ' very close ' and so on, there were no specifications in thefigures.
7) In the northernmost extreme of tongue-like projection as a shape of packice distribution, the state of pack-ice was usually ' open ' or ' close ' ones. Thereobserved no 'very close' pack-ice in those above mentioned regions.
8) In the far more southerly region beyond the observed ice limit, it was very
often to exist a large ice free waters, especially in the place where the northernmost
extreme of the pack-ice greatly expands toward north and forms a tongue-likeprojection. In these regions there was a good deal of distance between the northernmost ice edge and the second one which lies considerably in the south.
We would like to express our appreciation to Nippon Suisan K.K. and to all
personnel who had been participated to the Antarctic whaling operations during
the seasons from which our data originated.
REFERENCES
MACKINTOTH, N. A., 1970. Whales and krill in the twentieth century. In: Antarctic Ecology, M. W. Holdgate (ed.), Vol. 1, Academic Press, London, 604 p.
MACKINTOSH, N. A. and H. F. P. HERDMAN, 1940. Distribution of the pack-ice in the southern ocean. Discovery Reports, 19 : 285-296.
TRESHNIKOV, A. F., 1967. The ice of the southern ocean. Japanese Antarctic Research Expedition, ]ARE Sci.
Reports, Special Issue, No. I : 113-123.

Sci. Rep. Whales Res. Inst.,

No. 29, 1977.