SOME INFORMATIONS ON MINKE WHALESFROM THE ANTARCTICTOSHIO KASUYA AND TADAYOSHI ICHIHARAINTRODUCTION

Williamson ( 1959, '61) already reported on the specimens of Balaenoptera bonaerensis
Burmeister (1867) caught in the Antarctic whaling areas II and III. Though he
did not made any conclusion on the taxonomical position of B. bonaerensis and B.
acutorostrata, he considered that B. huttoni Gray (1874) is a synonim of B. bonaerensis
and that B. bonaerensis will be common in the Antarctic Ocean.
Utrecht & Spoel (1962) reported a male B. bonaerensis captured in the area
III in the Antarctic whaling season 1959/60. They pointed out a difference of thelength of the flipper between B. acutorostrata and B. bonaerensis and concluded thatB. bonaerensis is a variation of B. acutorostrata.
A Japanese whaling fleet, the Nissin-maru No. 3, captured 96 little piked whalesin the area III and IV in the Antarctic whaling season 1963/64. The whalers saythat all of the little piked whales caught by the fleet were another type of little piked
whale, namely B. bonaerensis, and judging from a coloured picture and a collectedbaleen plate it is sure that some of them, at least 14 whales presented on thepicture, were B. bonaerensis. So we can give some informations on these whales.
We acknowledge to Mr. Keiji Sasaki of the Taiyo Gyogyo Co., who showed
us some data concerning these whales. Mr. Kaoru Yamada and Mr. Fusao Ozawaof the Japanese Fisheries Agencies, kindly presented us photographs and a baleen
plate of whales which are included in this paper.

DISTRIBUTION

The captured positions of the little piked whales by the Nissin-maru No. 3 are shownin Table 1. The whales shown in Fig. 3 were captured on Jan. 6, 1964 and theposition is 62°-54'S, ll5°-l9'E. This is the first record for B. bonaerensis captured
in the Antarctic whaling area IV.
TABLE I.

POSITION OF CAPTURE AND SCHOOL COMPOSITION
NumberDate captured
Dec. 13, 1963
Dec. 28, 1963
Jan. 6, 1964
Jan. 7, 1964
Jan. 8, 1964
Jan. 10, 1964
TotalMale
10155012

Position captured
61°-55'S, 120°-44'E
62°-42'S, 55°-14'E
62°-54'S, l 15°-l9'E
63°-00'S, ll9°-35'E
62°-56'S, 124°-05'E62°-2l'S, 133°-l 7'E

7937

Female
0I3JO
3017TotalI
1860
15I96

Ratio ofmale (%)
100.0
0.0
83.3
83.3
80.0
100.0
82.3

38T. KASUYA AND T. ICHIHARA

Fig. 1 shows the position where B. bonaerensis were captured including theposition reported by Burmeister (1867), Gray (1874), Williamson (1961) and Utrecht& Spoel (1962).
From this figure it is suggested that B. bonaerensis distributes in the Atlantic
and the Indian part of the Antarctic Ocean, and probably in the Pacific part of
the Antarctic Ocean also.
60°El 20° E\)
0008•

..,.

4't;;. 40° s
60° s

Fig. 1.

Captured position of B. bonaerensis, each point shows one whale.
D: Utrecht & Spoel (1962)
O: Williamson (1961)£:,,.: Burmeister (1867)x : Gray (1874)

e: Nisshin-maru No. 3

EXTERNAL CHARACTERS

The external characters of our specimens coincides fairly well with those reported
by Williamson (1961) and Utrecht & Spoel (1962), particularly in the flipper without
white band, baleen plate with darkly coloured external edge.

Fig. 2.

Schematic figure of the pigmentation of B. bonaerensis.

But our photograph shows that the pigmentation of the left side of the headregion exceed that of the right side. The darkly pigmented area of the jaw isbroader in the left side and the white area on the upper rip is longer in the right.
The number of baleen plates without the darkly colourd edge, which distribution
seems to correlate to the presence of the white area of the upper rip, is smaller in theleft side than in the right. This coincides better with Utrecht and Spoel ( 1962)rather than Williamson (1961). One of two pale streaks, which begin near theanterior insertion of flipper, extends toward shoulder and the other points to ear inour specimens. But these streaks also have the possibility to occur on B. acutorostrata. The dark dorsal pigmentation in B. bonaerensis expands toward the flank infront of the dorsal fin (Fig. 2).

恥fTHEANTARCTIC
恥1INKE WHALES FRO

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BALEENPLATE

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1962)1)andUtrecht & Spoel (691
Williamson (awhichtartsorotu
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isnereano.bfB
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efoundmore
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f baleen f
The diameter osetal
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siegnirff
nnumber,oo114i
from84t

T. KASUYA AND T. ICHIHARA

40theirdiametera
tthebasewithamicrometer. Thesemeasurementa
reshowninFig. 6 and Table 2. Theysuggestt
helargerdiameteri
nB.t
JonaerensisthanB.

︶−︒

εU一4o 一♀

*。
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。

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•ム5

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1015
Lengthof baleen plate lcmI

20

Fig.4. Relation between thelength and the breadth ofbaleenplate.
B. αcutorostrat
a .. male, 0 female，ム unknown
B.bonaerensis....企 sexunkhowneFi
g.5. Baleenp
latesofB.αcutorostrata(leftthree)andB.bonaerensis(right，） ×0.
22.

MINKE WHALES FROM THE ANTARCTICTABLE 2.

41

DIAMETER OF BALEEN FRINGES (mm)B. acutorostrata
Specimen
Length of baleen
plate
Number of fringes
measuredRange of diameter
Mean diameter
Range of two
standard error

0.1

B. bonaerensis

2345235

125

166

177

175

182

84

95

86

115

98

93

0.140-0. 728
0.354

0.101-0.537
0.211

0.134-0. 547
0.274

0 .111-0.486
0.225

0 .130-0. 789
0.293

0.141-0.830
0.279±0.033±0.016±0.022±0.016±0.022

0.028

0.6

0.7

0.2

0.3

0.4

0.5

0.8

Diameter of baleen fringe Imm lFig. 6. Diameter of baleen fringes, range, mean and the range of two standard error.
Top: B. bonaerensis, Bottom five: B. acutorostrata.

acutorostrata.
SCHOOL AND BODY LENGTH

Though the whaler says that all of the little piked whales caught by the Nisshi-maru
No. 3 seemed to belong to the same type, it was not observed by any biologist.
There is an evidence to suggests the occurrence of B. acutorostrata in the Antarctic(Taylor, 1957). During the marking voyage in the end of December in 1959,
lchihara observed three little piked whales swim around the catcher boat in area
IV in the Antarctic. From the white band on the flipper, these whales wereidentified as B. acutorostrata. Therefore, we cannot conclude definitely that all thewhales captured by the Japanese fleet were B. bonaerensis. But we present here thebody length, sex and the length of foetus for the purpose of reference.
As shown in Table 1 the whales are caught on January 6, 7 and 8, 1964.
It is said that the catches of each day belonged to one school respectively andnearly all of the component of each school were caught.

T. KASUY A AND T. ICHIHARA

42

The ratios of male whales in the catches from the three schools show nearlysame value 80 percent, which seems to suggest the dominance of male in the schoolsof B. bonaerensis migrating these latitude.

l 7 Females

15* 5>-ucQJ::>(]"~u...

2515

522Fig. 7.

26
Body length !feet}

2830

Body length composition of the little piked whales caught by the Nisshin-maru No. 3.
TABLE 3.

BODY LENGTH COMPOSITION

Body length(foot)

2223224
325
526
18272228
1829
9230Total
791) One is pregnant.
TABLE 4.

FemaleMaleTotal

22325491931l2522)
209241796
Two are pregnant.
I2)

BODY LENGTH OF THE FOETUSES (cm)Date captured

Body length

SexJan. 7, 1964
Jan. 8, 1964
Jan. 8, 1964

45
1918Female
MaleMaleMINKE WHALES FROM THE ANTARCTIC

43

Table 3 and Fig. 7 show the body length composition. There is no whale
shorter than 21 ft. Although we consider the selection of larger whales by gunners,
it is safe to say that larger whales dominently migrate to the higher latitude as in
the case of B. acutorostrata in the northern hemisphere.
The ovary and testis were not examined. But one and two pregnant whales
were found, in the catch on Jan. 7 and 8th, and their body length was 27 and 28 ft.
respectively. Willismson (1961) also reported a newly matured female of 27 ft.
Our data will provide some information on the body length at the attainment ofsexual maturity of female whales.
REFERENCES
ARSENYEV, R. K. (1960). Distribution of Balaenoptera acutorostrata Lacep. in the Antarctic. Norsk Hvalfangst-Tid., 49 (8): 380-382.
BURMEISTER, H. (1867). Preliminary description of a new species of finner whale (Balaenoptera bonaerensis).
Proc. :(ool. Soc. Lond., 1867: 707-713.
GRAY, J. E. (1874). On the skeleton of the New-Zealand pike whale, Balaenoptera huttoni (Physalus antarcticus,Hutton). Ann. Mag. Nat. Hist., 4 (8): 448-452.
]ONSGARD, A. (1951). Studies on the little piked whale or mink whale (Balaenoptera acutorostrata Laceped)
Norsk Hvaifangst-Tid., 40 (5): 209-232.
0MuRA, H. & SAKIURA H. ( 1956). Studies on the little piked whale from the coast ofJapan. Sci. Rep. Whales
Res. Inst., 11: 1-37.
SERGEANT, D. E. (1963). Minke whales, Balaenoptera acutorostrata Lacepede, of the Western North Atlantic.
]our. Fisheries Res. Board of Canada., 20: 1489-1504.
TAYLOR, R.H. F. (1957). An unusual record of three species of whale being restricted to pools in Antarctic
sea-ice. Proc. :(ool. Soc. Lond., 129: 325-331.
UTRECHT, W. L. v. & SPOEL, S. van der. (1962). Observations on a minke whale (Mammalia, Cetacea)
from the Antarctic. :(eitschrift fur Siiugetierkunde, 27 (4) : 217-221.
WILLIAMSON, G. R. (1959). Three unusual rorqual whales from the Antarctic. Proc. :(ool. Soc. Lond,. 133 (1):134-145.
- - (1961). Two kind of minke whale in the Antarctic. Norsk Hvaifangst-Tid., 50 (4): 133-141.