THESCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTITUTE
No. 28

THE WHALES RESEARCH INSTITUTETOKYO · JAPANOCTOBER 1976

THESCIENTIFICREPORTSOFTHEWHALESじTERESEARCHINSTIT
8
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THE
SCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTITUTE
No. 28

THE WHALES RESEARCH INSTITUTETOKYO, JAPANOCTOBER, 1976

THE WHALES-RESEARCH INSTITUTE
1-3-1, ETCHUJIMA, KOTO-KU, TOKYO

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE
CONTENTS OF NUMBER 28
KAWAMURA, A. and SATAKE, Y.
Preliminary report on the geographical distribution of the Bryde's whalein the North Pacific with special reference to the structure of filtering
apparatus ................................................................. .
P1VORUNAS, A.
A m<Jthematical consideration on the function of baleen plates and theirfringes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
OMURA, H. and KASUYA, T.
Additional information on skeleton of the minke whale from the Antarctic 57
OMURA, H.
A skull of the minke whale dug out from Osaka.. . . . . . . . . . . . . . . . . . . . . . . . . 69
KASUYA, T.
Reconsideration of life history parameters of the spotted and striped dolphins based on cemental layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
McCANN, C.
Notes on the foetal skull of Mesoplodon stejnegeri ............................ 107
G1ANUCA, N. M. and CASTELLO, H. P.
First record of the southern bottlenose whale, Hyperoodon planifrons from
Brazil ...................................................................... 119
BROWNELL, R. L. Jr., AGUAYO L., A. and TORRES N., D.
A Shepherd's beaked whale, Tasmacetus shepherdi, from the eastern South
Pacific ...................................................................... 127
BROWNELL, R. L. Jr. and PRADERI, R.
Records of the delphinid genus Stenella in western South Atlantic waters.. 129
YAMASAKI, F., SATOMI, H. and KAMIYA, T.
An observation on the papillary projections at the lingual margin in the
striped dolphin ............................................................ 137
KASUYA, T. and MIYAZAKI, N.
An observation of epimeletic beha vior of Lagenorhyncus obliquidens . . . . . . . . . . 141
KAWAKAMI, T.
Squids found in the stomach of sperm whales in the northwestern Pacific .. 145
LEUNG, Y.M.
Life cycle of C)•amus scammoni (Amphipoda: Cyamidae), ectoparasite of graywhale, with a remark on the associated species ............................ 153
KAGEI, N., ToBAYAMA, T. and NAGASAKI, Y.
On the helminthum of Franciscana, Pontoporia blainvillei .................... 161
TsuYUKI, H. and IToH, S.
Fatty acid component of lipid of Euphausia superba ........................ 167
NAITO, Y.
The occurrence of the phocid seals along the coast of Ja pan and possible
dispersai of pups .............................................. ',. . . . . . . . . . . 175
NAITO, Y. and OSHIMA, M.
,·
The variation in the development of pelage of the ribbon -seal with reference to the systematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187

PRELIMINARY REPORT ON THE GEOGRAPHICAL
DISTRIBUTION OF THE BRYDE'S WHALE IN
THE NORTH PACIFIC WITH SPECIAL
REFERENCE TO THE STRUCTURE
OF FILTERING APPARATUS
AKITO KAWAMURAAND

YUKO SATAKE
Whales Research Institute, Tokyo

ABSTRACT

Some external characters of the Bryde's whales caught during thesummer of 1975 in the waters off Sanriku, northwest Pacific were studied.
Although no prominent external characters which may suggest an intraspecific variation in distinguishing the differenciation of possible races
were found among the fourteen animals examined, one animal, Sy7518(12.5 m, male, see Table 6 and Appendix III) showed considerably distinct characters which make the animal be distinguished clearly fromthe others. It is, however, still obscure whether or not the animal
could be said as allopatric forms since no reproductive conditions were
examined. It was suggested that one of the most important external
characters should be examined for the North Pacific Bryde's whale was
the overall morphological characters for the filtering apparatus such as
the length of baleen series, whole shape of the apparatus, nature ofbristles and the filter area. There found at least two types ofBryde's whales in the regions concerned: the first one is quite less inthe number of ventral grooves, lower but broad based in dorsal fin,very coarse and considerably small in its filter area. All of these suggests its closer character to the Bryde's whale. proper whereas thesecond one is almost opposite character to the former in may respects
with some intermediate varieties and showed somewhat similarity to
sei whale. There seems two more possible populations in the North
Pacific Bryde's whales: the first one is largely f9und in the pelagic
waters of the North Pacific, and the other is in the waters off west
coast of Kyushu. A possible invasion of the former population into
Sanriku, Northwest Pacific is suggested.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 1-35.

2

KAWAMURA AND SAT AKE

INTRODUCTION
The North Pacific Bryde's whale is one of two mysticete species to be caught
currently by Japanese whaling both in pelagic and coastal waters, and provides
an important components among the total catches. Although its taxonomical
problem against sei whale in the North Pacific region seems to have been
settled by establishing the species which occurs and predominates widely over
the warmer waters in the Pacific region (e. g. Omura, 1966a; 1974), little has
been studied concerning to its general biological characteristics including thediagnosis for the subspecies or the races. A considerable variations in external
appearance for the North Pacific Bryde's whales such as the case known in theSouth African population (Best, 1970; 1974) have been noticed through theprevious studies (Omura et al., 1932; Omura and Fujino, 1954 ;. Omura, 1959,1962), but the matter was left behind from the further consideration. One ofsuch problem may be found in the intraspecific and morphological variations
by occurring localities over the world oceans in large and/or small scale, andthe variations are, to some extent, possibly related to the difference by local
populations or stocks. It is, therefore, the current problem to elucidate whether
any racial defference or allomorphological forms could be found in the North
Pacific Bryde's whale. Althouh it has been noticed that there must be somedifferences in the character of baleen plates taken from the Bryde's whalescaught in the North Pacific region, little attention was paid for this matter
until we got the knowledge from the South African waters. More recently,
however, Masaki (1975) compared the baleen plates of North Pacific Bryde's
whales with a hope to distinguish their local populations by examining widthlength ratio and some morphology for the bulk of baleen plates collected atmany localities over the North Pacific regions along with the recovery data oftagged whales. Masaki (1975) considered that there must be at least two possible
subpopulations of Bryde's whales in the North Pacific: the first one is restrictedin the waters west of 150°E longitude, while the second one is found in the
pelagic region lies between 160°E and 160°W longitudes. However, as far as
the figures given by Masaki (1975) are concerned, there seems some differencein the pelagic population which could be separated each other somewhere between l 70°E and 180° longitutdes. Under these circumstances, the main purposeof our study was to know and, if it was present, was to find out some criticaland well representing external characters showing an intraspecific variation bywhich the racial difference of Bryde's whale population might be suggested.
In the course of examining Bryde's whales at the landstations both in Ayukawa
and in Onagawa, northernjapan, we noticed that there were some intraspecificdifferences in the general structure and the nature of filtering apparatus for the
Bryde's whales although the present result should be considered still tentative
due to so small number of animals observed. The result is presented briefly
in this report along with some considerations.
Sci. Rep. Whales Res. Inst.,
No. 28, '1976.

3

NORTH PACIFIC BRYDE'S WHALE

MATERIAL AND METHOD
During 24 July to 3 August 1975 following number of whales were caught andexamined in Sanriku region :Land Stn.

Company

Ayukawa
Ayukawa
Onagawa

Taiyo Gyogyo
Sanyo Hogei
Nippon Suisan

Bryde's

Fin

91)

4
22)

1) No observations for one carcass.
2) Examined only baleen plates for one of two carcasses.

A total catch figure for the Bryde's whale at four land stations during
baleen whaling season, May to October 1975, was 116 animals (045, ~71) inall, of which the majority (86.2%) was caught during the months of May to
July, so the time when we examined the animals was almost near at the endof Bryde's whaling season. One out of fifteen Bryde's whales landed was not
examined. Observed result on a fin whale at Taiyo Gyogyo was not treatedin this report except an item for Table 2.
An ordinal biological observations on carcasses were carried out as muchas possible for 14 animals. However, the observations on carcasses have had
to be done by only one person in the field, no measurements of so-called bodily
proportions were made except several measurements for minor part of body forthe later convenience (Appendix I). In this survey we focussed our observations
especially on mearnring the structure of filtering- apparatus in general since it
was sup?osed that the differenciation of intraspecific variation as an external
character in Bryde's whale would likely be well resulted both in feeding habits
and in the form or the character of filtering apparatus through the cetacean
evolution.
As for counting the number of so-called baleen plates we followed to thesuggested definition by Williamson (1973), that is, when the width of baleen
plate has three or more times of its thickness at gum level, we counted it as
the ' real baleen plates'. Diameter of baleen bristles was measured at threepoints, tip, middle and base, under the microscope with a aid of micrometer
mounted in the eyepiece. To calculate the whole area of filtering apparatus
we measured the overall length of baleen series along gum level and also thelength from the base of palatal ridge to the tip of baleen plates section bysection so as to be figured out the unfold shape of filtering apparatus on thesectioned paper. By this treatment the filter area was calculated by counting
the number of unit squares encircled by the figure. Another minor ways ofobservations and measurements were described elsewhere in the text where it
was thought to be necessary.
Sci. Rep. Whales Res. Inst.,
No. 28, '1976.

KAWA MURA AND SAT AKE

4

RESULT

General descriptions
The Bryde's whales examined were consisted of 8 male and 6 female withthe body length of ranging 10.l-12.7m (Av. 11.78m) in the former and 10.814.2 m (Av. 12.93 m) in the latter. All these animals were caught in the whaling
ground formed some 140-280 nautical miles east off the coast of Sanriku region
where relatively high surface sea temperature of above 23°C prevails during
mid summer (Figs. 1-a, 1-b). Shift in the location of Bryde's whaling groundwas not found when it was compared with the locations occupied in 1953
operations (Omura and Nemoto, 1955). One female of 14.2 meter (Sy7519 animal)
carried a well burried steel tag (No. 0789, Fishery Agency Japan) in the midstof her right side back between blow-holes and dorsal fin. The tag had been
shot at 26°08'N, 143°00'£ on 8 May 1950 and has been reported as sei whaleof 38 feet ( 11.6 m). Thickness of the blubber ranged 4.0-5.5 cm in six measured
animals, and that of mammary gland in two animals was 1.5 cm (Sy7519) and
3.0 cm (Ty7544) respectively. No lactating animals were found. Since carcasses
are largely cut opened at their ventral cavity to keep the meat more fresh, thestomach contents, reproduction organs and foetus are washed off and lost very
( 1)

140
145
150
E
Fig. 1-a. Distribution of surface sea temperature (Japan Meteolological Agency, 1975)
and the location of catch in the late July, 1975. (1) Sy7518, (2) Ty7544, (3) Ty7541,(4) Sy 7519, (5) Ty7543, (6) Ns7564, (7) Ns7563, (8) Ty7546, (9) Sy7520.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

5

often while the animal was on the way towing back to the land station. Neither
foetuses nor the condition of reproductive organ for female were observed, andconsequently the data on the reproductive condition are unavailable in thisstudy. Contrary, weight of testis was obtained from three animals; it was 1.2, 2.1(Sy7518); 0.4, 0.3 (Ns7563): and 0.2, 0.1 (Ns7564) (Kg) respectively. Comparing
these figures with those found in South African waters (Best, 1974), the above
animals were adolescence of sexually immature.
Number of ventral grooves was counted at the anterior insertion of flipper
on the visible half of body and the number was doubled. The obtained number
varied from 50 grooves to 70 (A v. 62) through four animals. It is note worthy
that one animal (Sy7518) showed only 50 grooves while another three wereover 62.
Abundance of white scar on the epidermis varied considerably by eachanimals. Number of scar counted i.n most animals was found somewhere between
15-40 scars on the visible half side of abdomen, and it gave an appearance ofmoderate state in scarring except two animals which were quite heavily scarredwith an appearance of like a newly galvanized iron or zinc plate. One animal(Sy7518), however, was exceptionally smooth in its epidermis with very little
number of white scars and, still more, the open pit was completely absent from

140

145

150

Fig. 1-b. Distribution of surface sea temperature (Japan Meteolological Agency, 1975)
and the location of catch in the early August, 1975. (10) Ty7541, (II) Ty7548, (12)Ty7550 (13) Ty7549, (14) Sy7521.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

6

KAWAMURA AND SAT AKE

its surface. Usually 1-4 of oval shaped open pits was found in lumber part,flipper and in the upper surface of the rostrum. The measured dimensions ofopen pit was 8.0 x 4.5 cm and 3.9 X 6.7cm or thereabouts, and these sizes foropen pits are likely to represent through the animals examined. It is unknown
whether the scratched scars were on the under surface of tail flukes.
There found at least three kinds of ectoparasites in some animals though
they were not infected altogether on a definite carcass. The parasitic organisms
found were Xenobalanus, Pennella and stalked barnacles, but both juvenile andadult forms of Balaenophylus sp. were found on the surface of larger sizedbaleen plates in every animals.
Very few of stomach contents were observed, since it was, as mentioned
before, also cut open while towed back to the land station. However, fouranimals had luckily kept some amount of stomach contents. The kind offoodstuff was consisted of young pacific mackerel, Pneumotophorus J aponicils
japonicus of about 13.5-15.6 cm in fork length in three animals. P. japonicus
japonicus occurs very abundantly over the Sanriku region toward considerable
pelagic region (Kawamura, 1973) during northern summer, and even migrates
into the Ayukawa harbour. The another one was said to have kept euphausiids.
Although no specimen of this euphausiids was collected, it might considered
probably be Euphausia pacifica, since the bulk of this species occurs in thewhaling ground off Sanriku region (Komaki, 1967) and also having beenfound in the stomach of blue, fin, sei (including Bryde's) and humpback whales(N emoto, 1959).
C0llected ear plug and female reproduction organ are usually sent to the
Far Seas Fisheries Research Laboratory, Fisheries Agency, when the whaling
season was closed, and the age of whales concerned is not yet known to theauthors as of March 1976.
In the observations on the general external appearance of Bryde's whales
examined, there found no distinct characteristics which may enable to distinguish from one another. However, as it was suggested before, one animalof 12.5 m female (Sy7518) was found to be rather different in its external
characters, viz. so small number of ventral grooves along with smooth and little
scarred good looking epidermis. This coasely grooved throat well corresponds
to that of ' sei whale' caught in the Bonin Islands whaling ground (Omura etal. 1952).
0Proportions
It does not seem to enable in obtaining any conclusive different charactersfrom the present data on body proportions since only several minor measurements
were made sporadically (Appendix I). However, some measurements would be
worth to be mentioned in connection with the results on the filtering apparatus.
To show rather distinct difference in some animals from the rest, we extracted
some figures from the overall data and summerized in Table 1.
Measurements other than Table 1 showed very well coincidence with all
2)

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

7

NORTH PACIFIC BRYDE'S WHALE
TABLE 1.

PERCENT FIGURES FOR SEVERAL NUMBER OF MEASUREMENTS
AGAINST BODY LENGTH SHOWING THE ANIMAL WHICH
LARGELY DIFFERED FROM THE OTHERS.
No. of animalmeasured

Average8

21. 8511

11. 20Distance between Yakobson's organ
and the tip of snout
Dorsal fin: (a) anterior edge(b) width

12

0. 76

8
9

5. 10
4.24

( c) Height

12

2.47

12
12

12.60
2.44

Measurements
Length of a row of baleen plates
along the gum level
Length of ridge on the head

Flipper: (a) anterior edge(b) width(3&)

Figures for prominent
difference from theaverage (%)
19.20
17.59
6.80
9.27
1. 43
1. 31
6.56
{ 5.843. 14{ 1. 93
2.04{14.2914.38
1. 69

Animal
Sy 7518
Sy 7521
Sy 7518
Ty7546
Ty7543
Sy7519Sy7518
Sy7518
Ty7550
Ty7546
Ty7550
Ty7547
Ty7550
Ty7548animals examined, and could be discarded from the considerations. As far as
Table 1 is concerned, several animals which showed different proportions could
be picked up. Among those animals enlisted in Table 1, Sy7518 animal which
was very coarsely grooved and smoothly skinned animal, showed significantly
different proportions from the others especially in the length of rostrum, palatalridge, baleen series, and dorsal fin, giving highest frequency in the number ofdeviated measurements. Proportions for dorsal fin in Sy7518 animal showedvery low and broad triangle which was quite characteristic from the others.
The dorsal fin of like this shape had been also known in the 'sei whale' ofsouthern type which occurs in the Bonin Islands waters (Omura et al. 1952).
This animal as going to be metioned later was also different at two mostimportant measurements while majority of the rest were only distinct at more lessimportant ones. Best (1974) suggested the difficulty to distinguish both inshore
and offshore forms of Bryde's whales only by a morphometric examinations
due to so frequent occurrence of intermediate forms. From the overall results
already mentioned, however, it might be considered that there seems to be atleast two or three unusual animals which could be distinguished at several
measurements on the external characters.

Filtering apparatus
Filtering apparatus in baleen whales would be one of the most important
external characters should be examined closely for the consideration of
intraspecific variation or racial problem of whale population until we will have
got more biological, physiological, and ecological knowledge on the species
concerned. Results obtained are summerized and given in Appendix II.
a) Row of baleen plates
3)

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

8

KAWAMURA AND SAT AKE

Both the length of a row of baleen plates along gum level and that alongpalatal ridge are indispensable agents for calculating the area of filtering
apparatus. For those animals which had not measured those length above
mentioned, it was able to estimate reasonably by drawing the actual unfolded
shape of filtering apparatus with the aid of measurements for inside of thefilter obtained section by section at every 30 to 50 cm intervals.
The overall length along gum level varied for 190.0-314.0 cm through ten
examined animals while the length along palatel ridge was 190.0-285.0 cm. As
it was given in Appendix I and Table 1, proportional figures for the length
along gum level was small in Sy7518 and Sy7521 animals. Fig. 2 demonstrates
290

8$
bO
"' 250"d

Sy7520 /

·c

/

(ii

"'cii

,,,,
""

(ii
0.

Cl
.0::

tO

Sy7518

/

/

/

"'"

o-l

200
Ns7564

•

200

250

300

Length of a row of baleen plates along gum level (cm)Fig. 2.

Length both for a row of baleen plates and for the palatal ridge.

TABLE 2. RA TIO FOR THE TRANSVERSE LENGTH OF FILTERINGAPPARATUS(A) AGAINST ITS MAXIMUM SPREADALONG BALEEN SERIES(B).
Body length (m)Animal

B/A

Male

10. 1
12.5
12.6
12. 7

Ns7564
Sy 7518
Ty7543
Sy7520

0.35
0.37
0.45
0.42

Female13. 7

Ty754414.2
15. 3 (Fin)Sy7519Ty7542

0.44
0.40
0.42

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

9

the relationship between both above mentioned lengths. From this figures it
is observed that there are two different characters in the general structure offiltering apparatus, that is, rather slender shaped apparatus as shown by theline A in Fig. 2 and more oval shaped one which belongs to the line B. This
relationships are more well represented in Table 2. The calculated ratio forthe maximum spread connecting tip to tip of both sides of baleen plates against
the length of palatal ridge showed that there are two kinds of clearly different
figures which are comparable with Fig. 2. Both Ns7564 and Sy7518 animals
showed considerable slender shape in their filtering apparatus, but they must
be considered separately as being different each other since the former seems
to be possibly resulted from its younger age, while the figures for Sy7518 animal,must be noted along with the large enough body length. Although those twodifferent figures are found among male animals, the difference would not be
due to the sex.
b) Number of baleen plates and hairs
A total number of so-called baleen plates in a series of baleen plates wascounted. The figures as given in Appendix II varied between 254 and 325
plates through eleven animals with 283.5 plates as an approximately averaged
number. By comparing these figures with those by Omura et al. (1952), majorityof the number of baleen plates in the present study was less than 290 plates,
and well agrees to that known in the southern type of ' sei whales' from Bonin
Islands waters except Ty7541 and possibly Ty7544 animals both of which showedsomewhat more ordinal sei-whale-like characteristics. However, the overallvariation between each animal seems to be still within an allowable range as
Bryde's whale species, and the data provided by Best (1974) for the Bryde's
whales of both South African and Chilean waters also suggest variable in thatcharacter, though the number of baleen plates of somewhere between 270 and
290 may be a reasonable figures for the Bryde's whales over the many localities.
Quite insufficient data are available for the number of creamy white hairs
and plates arranged on the distal end of baleen series as it has been known in
fin, minke and some sei whales. As far as the available data are concerned,
there was found no clear difference or tendency between animals and also
between both right and left baleen series in the amount of creamy white hairs
and plates. lntraspecific variation is unlikely to be figured out from this kindof character although there found some noteworthy difference between bothright and left sides in Sy7518, Sy7519 and Sy7520 animals. It is, however, still
unknown whether those difference or variation are significantly responsible tosuch a extent as to show a difference of races or allopatric forms.
c) Baleen plates
The shape of cross sectioned beak at cranial to blow-holes was reported as
relating agent at least to the morphological difference in both sei and Bryde's
whales (Omura, 1962). In connection with this relative angle ({}) which is formedby the outer edge of baleen plate against vertical axis was measured (Table 3).
To measure the angle actually, the gum line was adopted as one of two angle
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

10

KAWA MURA AND SAT AKE
TABLE 3. RELATIVE ANGLE FORMED BY THE LINE AT GUM
LEVEL AND THE OUTER EDGE OF BALEEN PLATES.

Male

FemaleAnimalBody Length (m)Angle (8)Ns7564
Ns7563
Ty7547
Ty7541
Sy7518
Ty7549Ty7543

50.4
53.6
48.5

Sy 7520

10. !
11. I
11. 2
11. 5
12.5
12.5
12.6
12. 7

49.8

Sy 7521
Ty7548
Ty7550
Ty7544
Ty7546

10. 8
11. 2
13. 7
13. 7
14.0

47.4
43.6
50.0
53.4
48.8

Sy 7519

14.2

56.3

53. I
49.2
53.6
52. I

38
e Ty7550• Ty7544
Sy7520

Ty7546• ••Ty7543 •Ty7547•
Ty7549

8

~
U)

<l.l

.µ

ro

-a
c:

<l.l
<l.l

ea
..0

30

......
0~c:<l.l.....120
Width of baleen plates (cm)Fig. 3.

Width and length of largest baleen plates.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

II

forming basal lines. Consequently, it means that the larger in this angle themore well the baleen plates hanged vertically. The upper and lower extremes
for this angle were 56.3° and 43.6° respectively. The general trends in thefrequency of this angle seem to change proportionally with the increase or
decrease in body length, and this tendency could be considered along with thewhole shape of filtering apparatus, viz. length-spread ratios in a series of baleen
plates (see Table 2). Some animal showed well horizontally spreading baleenseries while another were not. The angle varied so randomly over the examinedanimals and no significant relationship for the better understanding of an
intraspecific variation was found among this characters.
The width-length ratio (=quotient) for the largest baleen plates has been
one of the most well examined characters in many previous studies. This figure
as given in Appendix II and as demonstrated in Fig. 3 varied between 1.45
and 2.03 with an average of 1.79. From Table 3 and Figs. 4 and 5 which were
given by Omura et al. (1952), it can be said that the lower the value in thisratio the more closer character is seen as orignally known Bryde's whale itself.
In this point ,of view, following three animals, Sy7518, Sy7519 and Ty7546
showed relatively small width-length ratio than the rest and, consequently, theyshould be considered to keep somewhat distinguishable character in their baleen
shape than the others. Only in Ty7541 animal exceeded in the ratio. Although
all the figure obtained was in the range which had been found in Bonin Islands
population (Omura and Fujino, 1954) when Fig. 3 is compared with the result
as demonstrated by Best (1974), it might be said that the majority of animals
in this study carried a similar character with that known in offshore form of
the South African waters while those above mentioned three animals were morecloser character to one of two forms found in Brasilian waters.
In Bryde's whale, however, there found no only one or two most prominent
size of baleen plates but they are found for a section of baleen series consistingof several tenth number of baleen plates to be the same size while their widthvaries as shown by the function of width-length ratio among them for about
0.5 (Fig. 4). This suggests that it would be very hard to consider and/or try
to find out the variations only by means of the width-length ratio of baleen
plates unless one gets larger enough difference in that figures.
d) Number of minor baleen plates
Small brush-like baleen plates (=minor plates) are furnished between the
inner most end of main plates and the base of palatal ridge (see Williamson,
1973, Fig. 8). The minor baleen plates form also an important filtering mesheson the ceiling of upper jaw. The number of minor plates including a very
tiny stump of hairs varied along with both the position of main baleen plates
and animals within 5 to 13 plates with three exceptions. Usually the number
did not vary much within an animal and may not be so significant characterfor the purpose of this study (Fig. 5).
e) Baleen bristles
The character of hair-like bristles (=fringes) which finally form straining
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWA MURA AND SAT AKE

12
7.0

6.0

5.0

~
" 4.0
t::
.<::
<])

'Cl

-.

~ 3.0

•

2.0

•

:
I

. ..

r • [ .• I .I

·rqlltL!l~;.d!~:I •• F • L • •

•

r

1

!

•

:

•

•

:.,

•

S.

I

Z

1

•

I

1

•

•

1.0

0

1

20

40

60

80 100. 120 140 160 180 200 220 240 260 280 300 320

Ordinal number of baleen plate
Fig. 4.

Variation in the width.length ratio by the part of baleen series.

25116
15
214
.a13
H 12

g 11

"§10
'+-<

9

~ 8

1l 7

zs

6
5
4
3
2
1

1

20

40

Fig. 5.

60

80 100 120 140 160 180 200 220 240 260 280 300
Ordinal number of baleen plate
Variation in the number of minor plates.

meshes of filtering apparatus are considered as to be one of the most important
agents should be examined more closely. Since baleen bristles are easily
damaged through the sampling and examining process on baleen plates, nomeasurements on their length were made but examined and measured only their
thickness in terms of diameter and the number of bristles per unit length of
inner margin of baleen plates.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

13

As it is noticed in the figures on Plate II there were found two kinds ofbristles which can be easily distinguished by their appearance: the first one isvery long and thick structured in its diameter and streches out straight. This
bristles obviously form the main body or structure of the fringe of baleen plates.
The second one, on the other hand, is very thinly structured bristles with a
trace or an appearance of folding in zigzag shape at one or more angles.
This kind of bristles make the filtering apparatus to be more finer netting byentangling with both kind of another bristles from several neighboring baleen
plates to result a role as a sort of ' connecting tissue' throughout the baleenseries. This thin and zigzagged bristles are very fragile at their angled corners
where the bristles are rather flattened like a ribbon string, and are easily
damaged by the angles.
By distinguishing above two kinds of baleen bristles, one of author (A. K.)
counted their number per unit length of inner edge of baleen plates to give adensity which may show the extent of coarseness of netting in filtering apparatus. The determination of density in baleen bristles was made approximately
at the halfway of inner margin of the largest baleen plates by sampling allbristles within 2.0 cm length since 1.0 cm as a sampling unit length wasconsidered to be too small for this purpose. The number combined both kinds ofbristles varied for 39-85 per 2.0 cm unit length with an average of 60.9 bristles
per 2.0 cm. To see the overall result most animal carried the straight andthick bristles of about 1/3 to 1/4 of the number of zigzagged ones. On closer
examination, however, it can be noticed that these proportional balance in thenumber of both kinds of bristles are deformed in both Ty7541 and Sy7518
animals. The former completely lacks the zigzagged bristles and the latter wasvery little in the number of slightly zigzagged bristles which can be consideredalmost straight appearance (Fig. 6). The latter was very similar to those foundin the animals from Bonin Islands waters previously. In Fig. 6 some additional
data which were obtained from another baleen plates of Bryde's whales fromvarious localities were plotted. The result make the authors complicated at theirconsiderations: that is, the all results obtained from our previous collections
showed almost or complete lack in the number of zigzagged baleen bristles.
They were very similar to the character found in Sy7518 animal. Some ofthem undoubtedly must have been damaged to result bearing no thin andzigzagged bristles. However, the number of straight bristles as demonstrated
in the figure suggests that the animals of previous collection were well
luxuriously furnished with straight bristles than the majority of animals in
the present study, and only Sy7518 animal corresponds to those figures fromthe preserved materials. Besides, Ty7541 animal showed also an exceptional
character in the number of straight bristles. As far as Fig. 6 is concerned, it
can be said that most animals in the present study showed a character of more
sei-whale-like Bryde's whales. In Fig. 6 the position where the Bryde's whales
from the pelagic waters of the North Pacific or those from the coastal waters
off western Kyushu would be placed may be an another interests. This will
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWAMURA AND SAT AKE

14

Sy752070•<l):E""" 60
'O

E
u

0

N

<n

50

.0
'O

40

'-

~
·~

"'
"'""""
N

7549
Ty7543 Tr
Sy7519.\ eNs7563
Ty7548 .;Ns7564
Sy7521 •Ty7550

1 Brasil, Cabo Frio
2 Oshima, Kii, Japan
3 Brasil, Cabo Frio(Omura, 1962)
4 Ayukawa, Sanriku, Japan
5 Bonin Islands, Japan
6 Kyushu, Japan
7 Calamajue, Baja California

Ty7546• eTy7544
eTy7547

"" 30

·;:;

4-<

0

c5

z

20
Sy7518

•

10

1

•

( 5 '~
I ,_, I

6 7
4
40
50
60
30
No. of straight bristles/2.0cm of fringe

23
10

20

Ty754170

80

Fig. 6. Density of the two kinds of baleen bristles by the animals fromvarious localities.
TABLE 4. PROVISIONAL CLASSIFICATION FOR THE TYPES OF BALEEN
PLATES BASED ON THE MEAN DENSITY OF BRISTLES (N0./2.0 cm).
Kind of bristles
Type
Straight

Total

Corresponding animal

Zigzag

I

50

6.5

67

Ty7541, Sy7518

II

10

36.3

43.3

Ty7547, 7544, 7546

III

13

49

62

Ty7543, 7548, 7550
Ns7564, Sy7519, 7521

IV

17.3

58+

76

Ty7549, Sy7520
Ns7563be mentioned later in Addendum and demonstrated in Fig. 12. The result
seems very important external character for the better understanding of an
intraspecific variations though the matter needs still more accumulation offurther evidences. In connection with this the present data concerning to thecharacter in the density of baleen bristles can be summerized by distinguishing
the four provisional types of characteristics in the netting of filtering apparatus(Table 4).
Thickness of straight bristles was observed under the micrometer by
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

0.7

15

O Sy7519
Ty7550Sy751800eTy7549 Ty7544 0Ty7546
Sy7520•0.6
Ty7541•

0.5
Ns7564

E 0.4

s

U)

Q)

0.3
tl
·.:

•

Ty7547
Sy7521 e
0
OTy7548•Ns7563
11

Ty7543

•

12

(a)

13

15

14

..0
.µ

..c:
OJ)

·;;;
b

0.5

Sy7518

U)

Q)

..c:
.µ

... 0.4

Ty7547

0

Q)

<::
u

""~

0.3

Ns7564•

Ty7541

• •

4-<
U)
U)

•
•

Sy7519Ty75440
0 0Ty7550
eSy75200
Ty7546

Ty75-19

O Ty7548
0
Sy?S 2l e Ns7563

eTy7543

(b)

0.2
11

<::

ro

13

12

15

14

Q)

::8
0.4

•••

Ty7549 Sy7520
0.3
Ty7548 Ty7547

c. •

0.2

Ty7541

Ns75640.1

Ts7518•

Ty7543

Ty7546
Ty7550 0
000
Sy7519Ty7544

Sy?~21 e Ns7563
11

(c)

12
13
Body length (m)1415

Fig. 7. Thickness of straight baleen bristles at the base (a), middle (b), and at thetip (c) for 14 animals. Shaded circles are males and open ones are females.

measuring their diameter on five pieces of the bristles per animal at their base,middle, and at the tip, and each measurements were averaged. Measurements
at the base may give the most reliable figures since those bristles, mere or less,might have possibly been damaged. The straight bristles are tapered toward thetip, and grow thicker with an increase in body length (Fig. 7). Each measurement distributes within some reasonable ranges in many animals with varying
trends with their body length. However, as clearly shown in Fig. 7, diameterat the base for Sy7518, Ty7541 and Ns7564 animals were rather unusually thicker
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

16

KAWAMURA AND SATAKE

than the rest while Ty7543 animal was quite thin in the diameter. The former
two are note worthy for their corresponding figure to the type I of baleen plates
which almost or completely lack the zigzagged bristles (see Table 4). Comparing
the figures at the base with those at the middle and tip, the latter two animals,
Ty7543 and Ns7564, both are considered to be rather normally charactered in
the nature of their bristles. No difference by sexes was observed. As far as
the Fig. 7 is concerned, the Bryde's whales which bear on no zigzagged bristles
are furnished with robust and thicker baleen bristles to give a typical characterof general qualities of baleen plates having been b10wn in the 'southern type'of sei whales (Omura and Fujino, 1954). Table 5 shows averaged diameter ofbristles, and Table 6 does similar data obtained in the animals from various
localities. By comparing those figures, it might be suggested that there wereat least two forms of bristles. The first one is very thick bristles of more than
0.5-0.6 mm in diameter at the base, and the second one is more thin bristles
less than about 0.5 mm. In connection with the South African animals (Best,1974), the occurrence of Bryde's whale similar to those offshore form in Japanesewaters is evident. Although the details about animals from various localities
are not known well, all data suggest similar character to those obtained inpresent study. Some animals, however, clearly showed their more prominent
character with finer netting which can be distinguished easily from the anotherextremes.
In addition to morphometrical difference, coloration of the bristles was
distinct in Sy7518 animal : in this respect the bristles of this animal showed
completely creamy white even at the base of bristles while the others showedrather greyish white with brownish coloration at the base.
f) Area of filtering apparatus
The row of baleen plates was measured section by section at both its lengthfrom the gum level to the tip of baleen plates and from the base of palatalridge where the arrangement of minor baleen plates ends to the tip of mainplates. Using this two series of measurement, filter areas which are formed byboth outer surface of a row of baleen plates (expressed by So in Appendix II)
and inner surface (expressed by Si in Appendix II) were calculated on elevenanimals. The filter area for inner surface possibly effects on substantial abilityof animals to straining out the foodstuff engulfed, and consequently, it gives
much larger figures than that formed by the outer surface. The averaged filter
area through examined animals was 1.14 squaremeters for the outer surface
while it was 1.82 squares meters for the inner surface respectively. As we cansee in the column of Si/So in Appendix II, the area for the inner surface keeps
1.46 to 1.76 (Av. 1.61) times larger figures than that for the outer surface. Fig. 8
demonstrates the type of whales by the schema which may be classified by the
relationship of the filter area between both outer and inner surfaces. In theschema the ratio for Si/So in right whale, for instance, may possibly show close
to 1.00 and give a regression of an angle of about 45 degree. When the schemais introduced to the case in Bryde's whale, then the figures can be expressed
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

17

NORTH PACIFIC BRYDE'S WHALE
TABLE 5.

AVERAGED THICKNESS OF BALEEN BRISTLES.

r----'~

Midst______,.____,------''-,_

Str.

Zig.

Str.

Zig.

Str.

Zig.

Ty7541
Ty7543
Ty7544
Ty7546
Ty7547
Ty7548
Ty7549Ty7550Sy7518
Sy7519Sy 7520
Sy 7521
Ns7563
Ns7564

0.49
0. 35
0.59
0.54
0.42
0.36
0.56
0.62
0. 60
0.69
0.49
0. 39
0.32
0.41

0.45
0.28
0.48
0.41
0.27
0. 30
0. 35
0.45
0.44
0.37

0.35
0.27
0.41
0.38
0.35
0.28
0.40
0.42
0.46
0.45
0.37
0.27
0.24
0.27

0.30
0.25
0.32
0.32
0.26
0.22
0.29
0.28
0.32
0.26
0.26
0.20

0. 19
0.22
0.21
0.26
o. 19

0.22
0.18
0. 18
0.21
0.19
0. 16
0.22
0.20
0. 32
o. 17
0.19
0. 14

Av.

0.4879Base

Animal

0.28
0.27
0.23
0.37

0. 19

Tip

0.19
0.29
0.22
0.28
0.23
0.20
0. 13
0.12
0. 12

0.14

TABLE 6. THICKNESS OF STRAIGHT BALEEN BRISTLESIN BRYDE'S WHALES FROM VARIOUS LOCALITIES.
Body
length(m)

Thickness of bristles (mm)
Sex

13. 1
13. l

M
F
F
M

13.4

F

12.5
12.2

Locality
Base

Midst

Tip

0.43
0.58
0.55

0.38
0.32
0.48
0.46
0.40
0.24
0.33

0.29
0.24
0.27
0.31
0.29
0. 18
0.23

0.67
0.64
0.35
0.59
0.46 (0. 19~0.84)
0.49(0.22~1.11)

Baja California 1l
Cabo Frio, Brasil 2l
Oshima, Kii, Japan
Bonin Islands
Cabo Frio, Brasil
Kyushu, Japan
Ayukawa, Japan
South Africa, inshore 3l
offshore 3l

1) Collected by Dr. R.L. Brownell Jr. Baleen plate was possibly not from the largest
part, and no details about the animal are known.
2) For further details, see Omura (1962b).
3) Best (1974).

as given in Fig. 8. As far as the Fig. 8 is concerned, there seems to exist twoslightly different groups among the examined Bryde's whales : one shows morecloser character to sei whale (suggested by line I) and the other does more
likely to Bryde's whale proper (II). One of another data for the filter area
in Bryde's whales is available (Nemoto, 1970). By quoting Nemoto's data,
Kawamura (1974) figured the filter area of slightly less than 1.7 square meters m
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWAMURA AND SAT AKE

18
2.6

II

More closer characterto bryde's whale

2.4

2.2
~

""- More closer character' t o sei/right whales

..§

§ 2.0

"

"t:l

:~

ui

3 1.8

"'
....

"'
§:

"' 1.6
2
bJ)

.s

I

'i'i

/sy751s'0I"' 1.4
<l.)

....

<

1.2
/

1.0

.9/Sy7521/•Ns7564'Right''Sei''Bryde's'

A

~'

"!\so

Si>So

Si >So

Si~So

0.6

1.2
1.0
1.4
1.6
0.8
Area of filtering apparatus, outside (So) (m 2 )

1.8

2.0

Fig. 8. Filter areas for both outside and inside surfaces along with the schema ofshowing area size relationships.

15 meter Bryde's whale. This relative figure well corresponds with the area
found in Sy7518 animal. If we extraporate this size of whale into the regression
as given in Fig. 9, then we will obtain about 2.5 square meters of filter area (seealso Kawamura, 1974, Fig. 8-6). What the above mentioned suggests is that
there might present at least two different types of Bryde's whales both of which
are presumably distinguishable by comparing their filter area. It is still unknown
whether above mentioned grouping is valid for distinguishing the intraspecificvariation in the North Pacific population of Bryde's whales, those figures forfilter area strongly suggest a validity for this purpose of study by accumulating
more amount of data.
Fig. 9 demonstrates the relationship between the areas of filtering apparatus
for both inner and outer surfaces and their corresponding body length. To see
the figure it may be noticed that there are two important characters among
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

9

10

11

12

13

14

15

16

Body Length (m)Fig. 9. Area of filtering apparatus against body length. Black spot and (Si)indicate the filter area for inside surface, and open circle and (So) indicate
the filter area for outside one.

the examined animals. The first is found in relatively small filter areas
compared with body length such as Sy7518 animal. The second one is found inboth Sy7521 and Ns7564 animals. It should be noted, however, that these latter
two animals do not differ from the relationship shown by the majority attheir outer surface area (So), but agree well to the regression in general. By
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

20

KAWAMURA AND SA TAKE

consulting also with the data given in Table 2, the filter area for the inner surface
in two above mentioned animals would be on the half way of quite rapid
development by growing their width of skull or a corresponding structure at
somewhere around 10-11 meters in body length while the filter area of outersurface remains unchanged so much. That is, the smaller animals in their bodylength are narrower in their skull or head dimensions than the larger animals.
Relative increase in the size of head region with growth is a well known
evidence through several species of baleen whales (e. g. Mackintosh and Wheeler,
1929; Matthews, 1937, 1938) and, similarly, growth in width of skull could bealso considered.
Apart from the main purpose of the present study, it is also suggested by
the unusual figure in those above mentioned two animals that they might had
been under a quite rapid development in their feeding apparatus. A rapid
development in the structure relating to more active feeding, which is said tooccur in coincidence with the weaning of animal, has been known both in somedolphins such as Stenella (e. g. Perrin 1975a, b) and in baleen whales (Mackintosh
and Wheeler, 1929). According to Mackintosh and Wheeler (1929), the southern
blue whale weans at 16 m, and relative size of its head increase from 15.3%(13.5 m in body length) to 21.2% (26.5 m). Similarly, mean curve for the growthof baleen plates in fin whale changes steeply pointing upward at 12.0-14.5 m ofbody length (Mackintosh and Wheeler, 1929).
More recently, Best (1974) reported that a stranded female Bryde's whaleof 8.5 m (28 ft) was found to be a calf under suckling with only remains of milkin her stomach. By considering these facts along with the result obtained inthis study, it seems then that both Sy7521 and Ns7564 animals might have
weaned slightly before of the current season, and supposed to be under aphysiological condition between nursing and adolesecence. Their weaning might
took place at somewhere around 8-9 meters in body length. From these
considerations the difference in the areas of filtering apparatus in both Sy7521
and Ns7564 animals could be supposed quite normal. In summerizing the data
concerning to the filter area only one animal, Sy7518 showed a quite small
filter area against its body length and it may be one of significant external
characters which make the animal be distinguished almost completely from theothers.
DISCUSSION

As it has been mentioned in the previous sections, the Bryde's whale which
occurs in the Sanriku region during mid summer shows to some extent themorphological variations by each animal in its external characters; someshowed quite different external characteristics from the others in a measurement
or a nature over the general appearance of body while the matter wascompletely different from each other in another respect of observations. As tothe purpose of this study, which aims to find out some valid external characters
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

21

NORTH PACIFIC BRYDE'S WHALE

for distinguishing the difference of animals by localities the matter seems,
therefore, to go into fairly complexities when the animal is examined moreclosely.
To make the matter more clear the results which have been mentioned
elsewhere in the previous sections were summerized in Table 7. From this table,
it may be obvious that an animal, Sy7518 was quite distinct in its external
characters in many observed respects which enable the animal be distinguishedwell from the rest. Another two animals, Sy7519 and Ty7541, will come to thenext but more less characteristic than the former. The another six animals
differed to some extent only in one or two items of observations and/or
measurements. When we consider about those results or evidences, it can besaid in general that an actually important morphological variation could befound in the difference of the character of filtering apparatus and relating
functions or structures such as the number of ventral grooves and filter area.
TABLE 7.

DISTINCT EXTERNAL CHARACTERS FOUND IN NINE BRYDE'S WHALES.
CONCRETE DETAILS FOR THE PARTICULARS ON THE LEFT
COLUMN ARE FOUND IN APPENDICES, TABLE, AND
FIGURES GIVEN ELSEWHERE IN THE TEXT.
Sy

Ty

Sy

Sy

7518 7543 7519 7521
Scarring
No. of ventral grooves
Proportion
Creamy white baleen series
Length of baleen series
Shape of baleen series
No. of baleen plates
Breadth-length ratio forthe largest baleen plate
Density of baleen bristles
Thickness of baleen bristles
Area for filtering apparatus

Sy

Ty

Ty

7520 7546 7541

Ty

Ty

Ns

7547 7544 7564

+
+
+

+
+
+

+

+

+

+

+

+
+

+

+
+
+

+

+

+

+

+
+

As it was shown in Table 4 and Fig. 5, the difference in the density andgeneral appearance of baleen bristles in addition to the filter area may be one of
the most important characters which are valid for distinguishing the intraspecificvariations at least in the North Pacific Bryde's whales. Unfortunately wehave had no occasion to examine the baleen plates and the bristles of both
inshore and offshore forms of Bryde's whales in South African waters (Best,
1970; 1974), and it is still unknown whether or not all animals examined inthis study belongs to those offshore form. However, as far as the descriptions
by Best (1970; 1974) are concerned, the Bryde's whales examined in this study
should belong to the offshore form without any exceptions as stated previously
by Omura (1959). Since those more sei-whale-like Bryde's whale in the shape
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

22

KAWAMURA AND SAT AKE

of baleen plates have not been known at present from the North Pacific region,'
it may be possible that the animals other than Sy7518 and possibly Ty7541 could
be considered as rather an inshore like type of character among the North
Pacific Bryde's whales although the habitat for both types of whales, as far as
the catch location is concerned, does not seem different from each other.
The recovery of whale tags suggests that most of Bryde's whales occur
during winter in the waters of Bonin Islands head directly to Sanriku region
in the following northbound migrations but some of them also head to bothKii and Kyushu regions although some animals headed to Kii region may enter
finally into the Sanriku region (Omura, 1974). Recent tag recovery suggeststhat one of Bryde's whales in the south-western -of the North Pacific, which
was tagged at 02°20'N, 135°26'E, on 4 February 1975 was found to be relating
to the so-called North Pacific pelagic stock by recoverying the tag at 29°20'N,
175°20'E on 19 July 1975. The baleen plates which were collected previously in
the Bonin Islands waters, as examined and classified by four types in this study(see Table 4), do not include such character of more finer netting with many
zigzagged bristles.
According to Omura (pers. comm.) all baleen plates of Bryde's whales
examined at Bonin Islands were those robust nature ones with coarse and thicker
bristles (see Plate III, figs. 1-2). These characters are considered very similar
to those found in Sy7518 animal which is, at present, supposed to be very scarceamong the Bryde's whales caught throughout the whaling season in Sanriku
region (it occupies the share of only about 7.0 percent of total catch in thisstudy). When we consider this along with whale movements by the recovered
tags, there might occur some changes such as niche shifts among Bryde's whale
populations that make northward migrations close to the northern Japan. When
we assume that majority of Bryde's whales in the Bonin Islands waters migrate
up to Sanriku region, then the question arises where those more sei-whale-like
Bryde's whales come close to that region and/or whether any possibilities tooccur these whales too in the Bonin Islands waters.

CONCLUSION

Although no decisive conclusion was drawn in this study, it may be said that
there occurs at least two types of Bryde's whales in the waters off Sanriku
reg10n. It is still unknown whether or not they could be called as allopatric* There is only one baleen plates which suggests the occurrence of inshore form of Bryde's
whale in Japanese waters (see Best, 1974, fig. 4). We examined the same baleen plate again
and found that the specimen lacks some inner most part by damage (Breadth: 14.0 cm,
Length: 35.0 cm). The bristles of baleen plate were really finer than the ordinal ones (seeTable 5 in the text). However, the position from where the specimen was collected is
unknown. As it was shown in Fig. 4 in the text the width-length ratio for baleen plates varies
much with the position in baleen series, the treatment for this specimen seems better to beheld for the time being.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

23

forms untill we will have more information on their reproductive conditions.
One of them, however, clearly shows analogous characters with the animals
known in Bonin Islands waters, but it occurs with less prominent among thenumber of migrating animals head to Sanriku region. The external characterswhich make both types of Bryde's whales be distinguished from each other arevery slight, and could not be distinguished by an overall treatment of the data
since those chracteristics in external characters might be greatly reduced bydilution through the analysial process.
Addendiim
In the course of finishing the manuscript there was an opportunity to
examine the baleen plates of Bryde's whales caught in both Kyushu and pelagic
region of the northern North Pacific through the courtesy of the Far Seas
Fisheries Research Laboratory, Fisheries Agency. The obtained result· seems
to contain some indispensable evidence and worth to be presented here for thefurther corn parison and considerations of concerning to those racial problem
in the North Pacific population the Bryde's whales.
One of present authors (A. K.) made the baleen plate measurements on
thirty-eight animals from the catch in Kyushu region and thirteen animals fromthe pelagic waters of the northern North Pacific. As to the thickness and thedensity of baleen bristles, 17 out of 51 materials were counted and measured
their diameter at the base by following similar procedure as having been
described in the previous section. Although the number of animals and materials
above mentioned consists only a part of total catch figures for both regions,animals to be examined were selected randomly from the bulk of material kept
at the above mentioned laboratory, and the result can be considered to represent
the whole.
In regard to the relationships between width and length in largest baleen
plates, it was clearly shown that the length of baleen plate against its width
in the animals from pelagic region of northern North Pacific was undoubtedly
larger enough to be distinguished from the majority being found in the animals
from the waters off the west coast of Kyushu except one instance (Fig. 10;
Plates VI, VII). In the material from Kyushu, there found no such slim shaped
baleen plate as mentioned before, and each baleen plate was rather small but
furnished with more thicker bristles than the former and robust nature in
general. It should be noted that there were no baleen plates which exceeded
31cm or more in their overall length in the materials from Kyushu, and also
there were no overlapping figures of baleen plate dimensions between the
populations of both the pelagic waters of the North Pacific and the coastal waters
off Kyushu. In comparison with the results found in Sanriku region, figures
for width-length relationships were shown by encircling them with broken line
(Fig. 10 and, see also Fig. 3). With this figure the isolated plots for both North
Pacific pelagic and Kyushu are completely filled up by overlapping each other,and make Fig. 10 be completed as to present a series of variation in the shape
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

24

KAWA MURA AND SAT AKE

42

i

;!;

: Male and female forNorth Pacific pelagic

40

38

6

! t

: Arakawa, Kyushu: t: Tamanoura, Kyushu

36

~
00

3

c."'

34

"'"' 32

<ii"'

.0
~

0

.s 30
""
"'"'
....l

28

26 -

24

22

Width of baleen plates (cm)Fig. 10. Width and length relationships of largest baleen plates for the animals caught
in the North Pacific pelagic and in the coastal waters off western Kyushu .

......

0.7

a

0

0

• •

5 0.6

o
o

Q)

tl

ii 0.5~//•-----.,,,,,,...-----.....0

.6

0.4

''~

.!<:

u

//

- - _____ - _____.......

..- /_......

I

I

I

/
/

/~

00

/

(/)

~

0

--M

...... - /

(/)

,,,,

--,

,/''

/

,,.,,.,

.6.

/ .6.

:.a
E-< 0.3 ' - - - - - - - ' - - - - - - - ' - - - - - - _ L_ _ _ ___J__ _
10

11

12

13

14

Body length (m)Fig. 11. Thickness of straight baleen bristles at the base for the animals both Kyushu
and North Pacific pelagic. Plot distribution for Sanriku region is indicated by anencircle. Shaded circles indicate the animal from Tamanoura, open ones from Arakawa,and triangles are from the North Pacific pelagic.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

25

NORTH PACIFIC BRYDE'S WHALE

TABLE 8. THICKNESS AND DENSITY OF BALEEN BRISTLES OF BRYDE'S WHALESBOTH FOR KYUSHU AND FOR THE NORTH PACIFIC PELAGIC REGIONS.
Range of
Averaged no. of
No. ofNo. ofthicknessstraight A''.eraged bristles/2.0 cm
animal for straight bristles thicknessof fringe
examinedbristles,---'~
measured (mm)(mm)
straight zigzag
30.244-0.647

3

0.388-0. 734

64

0.316-0.691

44
22

0.437
0.545

15.0
8.0

38.0+
32.0

4

66
30
50

0.491

0.496-0. 766
0.334-0.637

0.635
0.523

11. 5
16.25
16.0

35.0
12.25
20.5

3
11

0.453-0. 710
0.428-0. 704

24
104

0.609
0.589

9.0
13. 75

20. 7
17.82

Remarks

NPP-3N, 1972 1l
NPP-3K, 1974 2 J
Av. for both NPP-3N & NPP-3K
JCAK, 1973 3 J
JCAK, 1974
JCTK, 19744 J
Av. for both JCAK & JCTK

1) North Pacific, pelagic, Nisshin Maru No. 3.
2) North Pacific, pelagic, Kyokuyo Maru No. 3.
3) Japan, coastal, Arakawa land-station, Kyushu.
4) Japan, coastal, Tamanoura land-station, Kyushu,

of baleen plates from northern to southern regions.
The thickness for straight appearance of baleen bristles and the densityof bristles are given in Table 8. The averaged thickness for the pelagic
population of the northern North Pacific was 0.491 mm while that for the Kyushu
region was 0.589 mm. When these figures along with their body length werecompared with those in Sanriku region (Av. 0.488 mm, Table 5), it can be said
that the baleen bristles for Kyushu are distinctly thick enough to be separated
from those in another regions (Fig. 11), and overall figures for the Sanriku
population make complete the thickness distribution for both the North Pacificand Kyushu populations as it was seen in the width-length relationships forbaleen plates.
Density of baleen bristles in terms of the number of straight and zigzag
shaped bristles per 2.0 cm of baleen fringe differed much between two above
mentioned regions : the density for zigzagged bristles in the North Pacificpelagic animals was 35.0 bristles/2.0 cm on average whereas it was only 17.82
bristles/2.0 cm in Kyushu animals. The former seems to correspond to someof types II to IV of baleen plates (Table 4) and the latter would possibly beto type I. An important character in the density of bristles is not the absolute
number or abundance of bristles but relative dominancy between straight andzigzagged shape of bristles since baleen fringe is apt to be damaged throughmany occasions prior to examination. When the number of straight baleen
bristles is plotted against that of zigzagged ones, it is clearly noticed that very
little number of zigzagged bristles are found in the animals from Kyushu, while
they are more prominent in the animals from the pelagic waters of the northern
North Pacific. The latter shows well coincidence with the character of baleen
bristles found in the animals from Sanriku region (Fig. 12).
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWA MURA AND SAT AKE

26
70+ Sy7520

Q)

g 60
~

,,,-,

......
0

E 50
u

I

I

q

...__

/
I/',
I

I

""

I

<fJ

~<fJ 40
·;:::

•'I

.A.II

..0

I

"b

\ ... / 0

"

~
~

OS

N
~

'I

/

I

30
0

''1
......

Jt,.

0

z 20
ci

oLl
0

0

0
0

Jt,.

10

Sy75180+0Ty7541
10

20

30
40
50
60
No. of straight bristles/2.0cm of fringe

70

80

Fig. 12. Density of the two kinds of baleen bristles for the animals from
Kyushu and North Pacific pelagic. Corresponding distribution for Sanriku
region is indicated by an encircle and cross marks. Open circles indicate
the animal from Kyushu and triangles indicate that from the North Pacificpelagic.

TABLE 9. STOMACH CONDITION FOR FIFTY-ONE BRYDE'S WHALESWHICH BALEEN PLATES WERE ADDITIONALLY EXAMINEDFOR THE COMPARISON OF PRESENT STUDY.
Sardine Mackerel Fish Unknown 1l Unknown 2l Euphausiid Empty
May
Arakawa3l

June

2

July

4

August13

93

September
Tamanoura

rune
July
AugustNorth Pacific {Julypelagic 4l August

5
2

8

2

I) Unknown kind of stomach contents.
2) Unknown whether there were any food or not.
3) Data for both 1973 and 1974 are combined.
4) Data for both 1972 and 1974 are combined.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

27

The result which was found by treating the materials under grouping eachindividuals suggests that the filtering apparatus in the animals of the North
Pacific pelagic region is structured more finer in its netting than those of
Kyushu region, and that the animals in Sanriku region shows an intermediatecharacter as a whole. However, it must be remembered that there were somuch variations in the latter animals. To support this tendency the stomach
condition for the animals of both North Pacific pelagic and Kyushu is given
in Table 9. The kind of food organisms in Kyushu region is represented bymackerel, sardine and some small fishes, which are somewhat similar to thatfound in Sanriku region, while euphausiids predonimated in the animals caught
in pelagic region of the northern North Pacific.
To summerize the result presented as addend'itm, it may be said andspeculated to some extent that there must be two possible different populationsof Bryde's whales in the northwestern North Pacific region: the first one ischaracterized by relatively longer and finer netting of baleen bristles, and isfound in the pelagic waters of the northern North Pacific where they prey on
the euphausiids and small swarming fishes. The second one, on the other hand,
is found widely over the waters off western Kyushu, which sometimes extend
even to the midst of the Yellow Sea. Animals found there carry very small but
more coarse netting in filtering apparatus, which is possibly similar characterto that has been found in Sy7518 animals in the Sanriku region. The Bryde's
whale population off west Kyushu is possibly consisted of the animals both fromsouthern waters of the western Pacific and of an endemic populations possibly
from the Yellow Sea and the East China Sea regions. The animals caught in
the Sanriku region show an intermediate external character in an overall
treatment by dilution but each animal can be distinguished as to be placed in
one of both above mentioned extremes. This suggest a possible mingling ofdifferent populations in that region. The Bryde's whales in Bonin Islands keep
migratory relationships to Sanriku region, but it is still unknown whether or
not they show a similar external characters to those have had been known
previously in that region. If there were no niche shifts and Bonin Islands
population has been remained unchanged in those region, then a considerable
invasion of the North Pacific pelagic population into the Sanriku region must
be considered so as to give an intermediate characters for the population in
Sanriku region.

ACKNOWLEDGMENTS

We are much indebted to the whaling land-stations of Taiyo Gyogyo K. K.,
Nippon Hogei K. K. both in Ayukawa and of Nippon Suisan K. K. in Onagawa
for their kind assistance and offering their facilities in collecting the data andmaterials through this work. Courtesy of the Whales Research Section of the Far
Seas Fisheries Research Laboratory, Fisheries Agency in Shimizu made us enable
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWAMURA AND SAT AKE

28

to compare the result on the animals in Sanriku region with that both inKyushu and in the pelagic region of the northern North Pacific. Personally, we
are indebted to Dr. Seiji Ohsumi of above mentioned laboratory for permittingof our sampling the baleen bristles, and also Mr. Siro Wada of the samelaboratory for prepering and assisting our laboratory work in Shimuzu. Without
their kind help no data were available for the animals both in Kyushu andin the northern North Pacific, and these circumstances are greatly appreciated.

REFERENCES
BEST, P. B., 1970. Two allopatric forms of bryde's whale on the west coast of South Africa.
Paper submitted to Scientific Committee, 22nd Meeting of IWC, Sc/22/15.
BEST, P. B., 1874. Two allopatric forms of bryde's whale off South Africa.
Scientific Committee, Special Meeting, La Jolla.
JAPAN METEOROLOGICAL AGENCY, 1975.

The ten-day marine report.

Paper submitted toNos. 1037-1038.

KAWAMURA, A., 1973. Food and feeding of sei whale caught in the waters south of 40°N in
the North Pacific. Sci. Rep. Whales Res. Inst., 25: 219-236.
KAWA:VJURA, A., 1974.
KOMAKI, Y., 1967.
448.

Food and feeding ecology in the southern sei whale.

On the surface swarming of euphausiid crustaceans.

MACKINTOSH, N. A. and J. F. G. WHEELER, 1929.
I : 257-540.
MASAKI, Y., 1975.
bryde's whales.

Ibid., 26: 25-144.

Pacific Science, 21: 433Discovery Rep.,

Southern blue and fin whales.

A provisional study on the subpopulations for the North Pacific stocks ofGeiken Tsushin, 288: 61-66. (in Japanese)

MATTHEWS, L. H., 1938.

The humpback whale, Megaptera nodosa.

MATTHEWS, L. H., 1938.

The sei whale, Balaenoptera borealis.

Discovery Rep., 17: 7-92.

Ibid., 17: 183-290.

NEMOTO, T., 1959. Food of baleen whales with reference to whale movements.
Res. Inst., 14: 149-290.
NEMOTO, T ., 1970. Feeding pattern of baleen whaes in the ocean.
Steele( ed.), Oliver & Boyd, Edinburgh, 552 p.

Sci. Rep. Whales

In: Marine food chains. J.H.

Sci. Rep. Whales Res. Inst., 14: 1-33.

OMURA, H., 1959.

Bryde's whale from the coast of Japan.

Olv!URA, H., 1962a.
7-18.

Further information on bryde's whale from the coast of Japan.

OMURA, H., 1962b.

Bryde's whale occurs on the coast of Brazil.

OMURA, H., 1966. Bryde's whale sn the northwest Pacific.
(ed. K.S. Norris): 70-78. Univ. Calif. Press.

Ibid., 16:

Ibid., 16: 1-5.

In: Whales, Dolphins and Porpoises.

OMURA, H., 1974. Review of the bryde's whale stock in the northwest Padific.
to Scientific Committee, Special Meeting, La Jolla.

Paper submitted

OMURA, H., S. NISHIMOTO, and K. FUJINO, 1952. Sei whales (Balaenoptera borealis) in theadjacent waters of Japan. Japan Whaling Association, pp. 1-80.
OMURA, H., and K. FUJINO, 1954. Sei whales in the adjacent waters of Japan.
studies on the external characters. Sci. Rep. Whales Res. Inst., 9: 89-103.

II. Further

OMURA, H., and T. NEMOTO, 1955. Sei whales in the adjacent waters of Japan.
between movement and water temperature of the sea. Ibid., 10: 79-87.

III. Relation

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

29

PERRIN, W. F., 1975a. Variation of spotted and spinner porpoise (Genus Stenella) in the eastern
Pacific and Hawaii. Bull. Scripps Inst. Oceanogr. Univ. Cali]. 21: 1-206.
PERRIN, W. F., 1975b. Distribution and differentiation of populations of dolphins of the genus
Stenella in the eastern tropical Pacific. ]our. Fish. Res. Bd. Canada, 32(7): 1059-1067.
WILLIAMSON, G. R., 1973. Counting and measuring baleen and ventral grooves of whales. Sci.
Rep. Whales Res. Inst., 25: 278-292.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KAWAMURA AND SAT AKE

30

APPENDIX I.

BODY PROPORTIONS OF THE BRYDE'S WHALES

Serial No.

Ns7564

Ty7547

Sex

Male

Male

Body Length (m)Length, row of baleen plates along gum level
Length, anterior end to largest baleen plates in baleen series

10. l

11. 2
10.8

Length, largest baleen plate
Length, palatal ridge
Spread of filtering apparatus across both sides (maximum)

18.81
6.53

Width, palatal ridge close to anterior end
Ratio, item 6/item 5
Spread of arch across both lower jawbones (maximum)

0.84

8. 75
I. 07

0. 35
8.61
12.27

10.09

Distance between right and left side ridges at their anterior end

I. 98

I. 12

Distance between right and left side ridges at their posterior end

5.34

Distance, tip of snout to anterior end of side ridges
Distance between both depressions of Yabobson's organ

0. 12

0.09

0.64

0.67

Length, side ridges on the head

Distance, tip of snout to Yakobson's organ
Distance, Yakobson's organ to anterior end of baleen series
Length, dorsal fin (anterior insertion to tip)

13. 30

5.00

Length, dorsal fin at base
Height, dorsal fin (fin tip to base)

3.86

2. 77

Concavity, dorsal fin (deepest part of posterior border to line between fin tip
and posterior base)

3.80
2.41
I. 07

Length, flipper (posterior insertion to tip)
Length, flipper (anterior insertion to tip)

11. 58

8.81

10.09
14.29

Width, flipper (maximum)
Length, fluke (notch to tip)

2.37
11. 882.50
12.86

Length, fluke (anterior insertion to tip)

13.93

Width, fluke (shortest distance between anterior border of flukes and notch)

6. 13

6.34

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

31

CAUGHT OFF SANRIKU, NORTHWESTERN PACIFIC IN 1975.
Ty7541 Sy7518 Ty7549 Ty7543 Sy7520 Sy7521 Ty7548 Ty7550 Ty7544 Ty7546 Sy7519
Male Male Female Female Female Female Female Female
Male Male Male
11. 5
28.69
9.91
2.56
20.35
I. 13

10. 26
12.69

12.5
19.20
12.96

12.5

12.6
22. 14

12. 7

19.84
8.88
I. 03
0.45

19.84
8.27
0.94
0.42
9.84
11. 26
0.39

8.95
12.08
2.60
12.43
12.43

11. 2
21. 25
11. 88

13. 7

13. 7
21. 97

14.0
21. 86

14.2
22. 11

4.50
18.64
6.96
0.88
0.37
10.96
11.66

6.80
0.56

0.13
0.65
0. 17
5.04
5.04
2.69

10.8
17.59
10.83

I. 36
0. 16
0.52

I. 11

11. 76

19.93
8. 76
0.88
0.44
9.92
12.07

10.00
9.27

8.29
0.93

8.57
0. 76

I. 02

9.82
11. 30
I. 12
3.57

10. 73
11. 61
I. 53
2. 34

0.54

0. 10
0. 73

0.09
0.66

0.09
0.64

5.58
3.57
2.59

4.82
4.60
2.63

4.57

3. 14
2.04

0.10
o. 76

I. 34
0.91
I. 43

6.56
5.84
2.88

2.48

4.32
3. 41
2.26

2.52

4.91
2.41

I. 28

I. 08

. 0. 67

1.10

0. 74

0.85

0.37

I. 09

0.34

8.24
11. 52
2.60

9.04
12. 72
2.48
13. 12
13.84
6.24

8.49
12. 14
2.53
12. 14

9.61
11. 57
2. 76
12. 13
12.91
6.46

7.96
11. 85
2.32
12.22
13. 15
6.20

8.66
13.26
I. 69
12. 14
12.95
6.25

10.07
14.38
2. 70
12. 7013. 14
6.35

8. 76
13. 14
2.26
12.66

8. 71
12. 79
2.46
12.57

6.22

6.07

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

6.26

0. 12
0.59
4.88

I. 93

20.07
8.02
0.94
0.40
10.98
3.09

0.09
I. 31

32

KAWAMURA AND SAT AKE

APPENDIX II.

MEASUREMENT ON THE FILTERING APPARATUS OF BRYDE'S

Measurement

Ns7564

Sy7521

Ns7563

Length, total (m)10.1
201. 510.8
190. 0

11. 1

190.0
66.0
24.0

27.5

28.5

12.6

14.5

14. 7

1.90

1.90

1.94

Length, row of baleen plates along gum level (cm)Length, row of baleen plates along palatal ridge (cm)
Maximum spread of filtering apparatus across both sides (cm)
Largest baleen plate

Length: L
With: W!

L/W
Number of baleen plates (total)lJ

261

Right
Number of creamy white hairs and plates (number/length) {
Left

282
15/10. 5

?

19

19

19

lO+a 4
10

12
12

18

Number of bristles on largest baleen plate (number/2.0 cm) 3 Zigzag

49

48

52

Total

61

60

0.41

0.39

70
0.34

Number of hair of stump of hairs in baleen series

Anterior{ Posterior

Number of minor plates at largest baleen plates 2JStraight

!

0. 27

o. 27

0.24

0. 13
0. 67
1. 10

0.12

Outside: So
Inside: Si

0. 12
0. 65
1. 04

Si/So

1. 59

1. 65

Averaged thickness of straight baleen bristles (diam. mm) at 1:is;dle
Tip
Areas for filtering apparatus (m 2 )!

I) Definition for so-called baleen plates was based on that by Williamson (1973)
2) Number of small brush-like plates which are arranged between main row of blaeen
plates and the palatal ridge
3) Length of bristles was not measured due to poor condition of preserved materials
for this purpose

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE

33

WHALES CAUGHT OFF SANRIKU, NORTHWESTERN PACIFIC IN 1975.
Serial No. of animal
Ty7547 Ty7548 Ty7541 Ty7518 Ty7549 Ty7543 Sy7520 Ty7550 Ty7544 Ty7546 Sy7519
11. 2

11. 2
238.0

11. 5
237.0
234.0

12.5
240.0
233.0

12.5

12.6
279.0
250.0

12. 7
252+
252.0

87.0
112. 0
96.0
105.0
29.0
32.0
31. 5
33.5
32.5
33.5
17.2
16.5
18.5
18.3
18.5
16. I
2.03
I. 69
I. 73
I. 78
I. 81
I. 96
286
325
266
267+a 2260+a 1-/57.0?/39.0 -/39.0
15/8.59/2.
727~28/8.0-/19.038/19.0 20/11.0
22
23
21
18
23
18
13
21
21
14
12
II
6
7
7
10
14+59·l) 26
17
17
15
10
12
]35J
51
ca.68
34
48
54
44
74
39
66
85
60
73
0. 42
0.60
0.56
0.35
0. 49
0. 36
0.49
0.46
0.27
0.37
0.35
0.28
0.35
0. 40
0.22
0.20
0.28
0.29
0. 19
0.19
0.19
I. 24
1.16
0.97
I. 06
I. 06

98.0
33.0
17.5
I. 89
254
45/27.0

I. 75

I. 76

I. 65

I. 65

I. 65

I. 50

I. 53

I. 81

I. 82

I. 92

I. 46

I. 66

13. 7

13. 7
301. 0
273.0

14.2
314.0
285.0
116.0
114.0
120.0
32.0
33. 7
37.0
36.0
22.0
21. 2
20.5
21. 0
I. 75
I. 75
I. 60
I. 45
273 or 283
3ll+a 3 293
50/22.0 24/- 27/17.0-/26.0 23/6. 7 53/38.0
1012
17
25+a 1730+a 21
II
13
II +a 4 II
13
II
9
14
47 5l
37 5l
38
51
48
47
60
65
0.62
0.59
0.54
0. 69
0. 41
0.42
0.38
0.45
0.22
0.21
0.26
0.23
I. 32
I. 48
I. 43
I. 53
2.32
2.20
2.44
2.31
I. 49
I. 71
I. 76
I. 51

4) 15 thick long bristles and 59 slender ones of straight features
5) Not heavily zigzagged features of almost straight.
Possible number for alpha letter:a=unknown, a 1 =10-15, a 2 =20, a 3 = 1-2, a 4 = I, respectively

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

14.0
298.0

34

KAWAMURA AND SAT AKE

EXPLANATION OF PLATESPLATE I
Fig. I. Baleen plate of type I (see Table 4 in the text): Sy7518 animal of 12.5 m,
male caught at 34-56N, 145-37E on 24 July, 1975. Ayukawa, Sanriku, Japan.
Fig. 2. Baleen bristles of the above ·animal.
Fig. 3. Baleen plate of type II: Ty7547 animal of 11.2 m, male caught at 37-16N,
144-58E on 1 August 1975. Ayukawa, Sanriku, Japan.
Fig. 4. Baleen bristles of the above animal.
PLATE II
Fig. I. Baleen plate of type III: Sy7519 animal of 14.2 m, female caught at 36-00N,
146-12E on 27 July, 1975. Ayukawa, Sanriku, Japan.
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of type IV: Sy7520 animal of 12.7 m, male caught at 37-16N,
146-lOE on 30 July, 1975. Ayukawa, Sanriku, Japan.
Fig. 4. Baleen bristles of the above animal.
PLATE IllFig. I. Baleen plate of No. 134 animal of 13.08 m, female caught in the waters of
Bonin Islands on 15 May, 1950.
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of Bryde's whale from Kyushu, southwestern Japan. No details
about the animal is known.
Fig. 4. Baleen bristles of the above animal.
PLATE IV
Fig. I. Baleen plate of No. 16 animal of 12.19 m, female caught at 33-35N, 136-25E
on 31 May, 1952. Ohshima, Kii, Japan.
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of No. 19 animal of 13. 41 m, female caught at 37-07N, 141-20E
on 4 July, 1953. Ayukawa, Sanriku, Japan.
Fig. 4. Baleen bristles of the above animal.
PLATE V
Fig. 1. Baleen plate of 13.11 m (43ft), male animal caught at 23-13S, 41-53W on
14 September, 1961. Cabo Frio, Brasil (see also Table 2 in Omura, 1962 for body
proportions of this animal).
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of 12.5m, male animal caught at 22-56S, 41-52W on 27 September,1960. Caba Frio, Brasil (see also Omura, 1962). Note completely different shape andcharacter of this specimen from the above shown one.
Fig. 4. Baleen bristles of the above animal.
PLATE VI
Fig. I. Baleen plate of 10.9m, male animal caught at 32-36N, 128~05E on 10 August,
1974, Tamanoura, Kyushu, Japan.
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of 11.2 m, male animal caught at 31-42N, 128-51E, on 13 June,
1973, Arakawa, Kyushu, Japan.
Fig. 4. Baleen bristles of the above animal.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NORTH PACIFIC BRYDE'S WHALE
PLATE VII
Fig. I. Baleen plate of 13.1 m, female animal caught at 37-41N, 167-05E on 9 July,
1972, pelagic region of the northern North Pacific.
Fig. 2. Baleen bristles of the above animal.
Fig. 3. Baleen plate of 13.6m, female animal caught at 37-07N, 168-41E on 9 July,
1972, pelagic region of the northern North Pacific.
Fig. 4. Baleen bristles of the above animal.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

35

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A MATHEMATICAL CONSIDERATION ON THE FUNCTION
OF BALEEN PLATES AND THEIR FRINGES
AUGUST PIVORUNAS
Yale University, New Haven

ABSTRACT

Many have suggested that baleen fringes are adapted to the foodthat is caught and strained by baleen whales. A study reported heresuggests that the situation is slightly more complicated.
In balaenopterid whales, the baleen is arranged so that when the jaws
are opened more than about 15 degrees, the mouth becomes open all theway to the rear of the mouth, making filtration impossible, but allowing
freedom of movement in the jaws when the whale is making large gulps.
The baleen plates are curved, which makes them rigid in the center ofthe baleen row, while making them flexible around the margin, which isinterpreted as producing a sealing zone that prevents openings fromdeveloping in the baleen while the whale is straining his food.
The fringes, of taxonomic interest, vary in characteristics in thesame whale. There are actually at least 2 different kinds in the fin
whale-a large kind and a small kind. The fringes give the baleen plate
an internal structure that is grainy, like wood. This brings about astriking phenomenon-the more acutely the plate's edge cuts across thisgrain, the fewer fringes can be produced by the plate in this region.
Therefore, where the plate edge is very steep, as in the right whales,
the diameter of the fringe must be very small to make up for thisshortcoming. A sei whale was found where the angle was zero degrees
between the edge and the grain, and correspondingly, no frin'ges at all
were on the plate at this level.
A mathematical formula was developed that relates fringe characteristics with baleen plate characteristics. Several shortcomings to thisformula are mentioned.

INTRODUCTION

As is fairly well known, the whalebone whales have a specialized feeding
structure involving hardened, keratinized palatal rugosities ~ (Barge, 1936, p. 43)* There has been some doubts expressed in the literature as to what constitutes the true mammalian palate in the whalebone whales, with Cuvier and a number of authors believing thatthe baleen stands upon the regular mammalian palate, while Eschricht believed that theregular palate took in only that surface exposed within the area covered by the baleen,
the latter area being thus a new addition to the mammalian palate. The matter was lastconsidered by Freund in 1912, who decided that the baleen were to be considered what Cuvier
had held them to be-palatal rugosities standing upon the regular mammalian palate.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 37-55.

38

PIVORUN八S

e
x
ten
仁l
e
di
n
t
ot
hef
or
m ofas
e
r
i
e
soft
r
ans
¥
・
er
s
el
yarranged pl
a
t
e
sonea
ch s
i
d
eof
t
he upperjaw (
Tom
i
l
in
.1
9
57
.p
.6
)
. Teet
har
eon
lypr
e
s
en
tduringat
r
a
n
s
i
e
n
t
embryonics
tage(
Ride〜
＇1
ood.1
9
2
2
)
. The p
a
l
a
t
a
l pl
a
t
e
s
. al
s
o knowna
sba
l
e
enor
whalebone andpopu
larlycaled .g
ils"o
r
・
・s
tr
a
i
ners" bythos
einvolvedi
nthe
whale fishery
. are mor
er
el
at
ed t
oh
a
i
ri
ns
t
r
u
ct
ur
e and compositionthan tobone,whicht
he term whalebonedecepti
velyi
mpl
i
e
s
. 〜
Vha
l
ebone i
scomposed
ofalargenumberofhairliketubulesarrangedi
nparallelandcementedtogeth巴r
by a matrix ormarro、＇・whichbecomesbrokenup on t
he i
n
t
e
r
n
a
l edgeoft
he
町

. Th
el
e
f
tb
a
l
e
e
nr
o
w
so
fa自nwh
al
e(
i
nf
r
o
n
t)
F
i
g.I
ando
fs
e
v
er
als
eiwh
al
e
s(
t
ot
hel
e
f
ta
n
dbe
h
in
d
)

F
i
g
.2
. Thef
ri
n
g
e
sa
n
db
al
e
e
no
faf
i
nw
h
a
l
e(
i
nf
r
o
n
t)
a
n
das
e
iw
h
a
l
e(
b
ehi
n
d)
.
Sc
i
.Rψ. W
h
a
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sRe
s
.I
ns
t
.
,
N
o
.2
8
,1
9
7
6
.

BALEEN PLATES AND FRINGES

39

plate by friction against the tongue which releases the tubules, that then forma tangled fringe along the border of the plate (Turner, 1873; Tullberg, 1833;
Tomilin, 1957 (1967)). These freed tubules are usually referred to as bristles orfringes. Since the term " bristle" is also used for the sensory hair fibers or
vibrissae found on the surface of the head and jaws in whalebone whales, aswell as for the bristle-like anterior serial homologs for the baleen plates in thefront of the palate, the term " fringe" is used here. The fringes obstruct theslitlike spaces between the palatal plates, and form a layer or screen on theinternal margin of the plates, typically concealing the latter from view fromwithin the mouth (Figs. 1 and 2). The baleen plates and fringes are known todiffer in several ways from species to species, so that they have taxonomic value,
while it has also been suggested that the characteristics of the palatal plates
and the fringes are adapted to the nature of the food taken by each species,
depending on whether the food is minute, consisting of copepods (right whales
and sei whales), or krill, a Euphausid crustacean (blue whale), or fish (fin whale,minke whale, humpback whale) (Tomilin, 1957; Nemoto, 1959; and personalobservations made on northwest Atlantic whales). It is generally held that finer
fringes are necessary for trapping finer sizes of plankton, and that coarser fringes
are needed for imprisoning fish and krill (Nemoto, 1959, p. 155). Nemoto
believes further that it is the fringe fineness and not the fringe density that
influences or is correlated with food preferences.
WHALEBONE FORM AND CONFIGURATION

The whalebone, as already mentioned, is composed of a series of plates thatform a uniformly graded series from the front of the mouth, or tip of the snout,
to a level somewhat behind the eye, on a greatly enlarged palate. In all baleen
whales, the baleen on either side of the mouth is separated at the rear by the
median palatine keel, while in front, the baleen is separated by a space in theright whales (Eschricht and Reinhardt, 1861; Nemoto, 1959), while they are
joined by a series of coarsely bristle-like serial homologs to the palatal plates
in the balaenopterid whales or rorquals, the latter term being understood toinclude the genus Megaptera. This crossband is called among other things the
Zwischenband by Freund in his studies of the cetacean palate (loc. cit.). The
zwischenband has been presumed to have a functional significance, although
this function is not yet known. In bulk, it is only a tiny fraction of the entire
structure of baleen on the palate, so that its consequences would seem to beminimal. It is probably a secondary condition, for it is absent in the graywhale as well as in right whales.
The skull has a long, flattened rostrum to support this straining apparatus
which is entirely confined to the oral cavity. The absence of a cheek, in whichplace there lies exposed a spacious vestibulum oris s. pariacoel in front of theangle of the mouth, permits the angle of the mouth to lie very far posteriorly,
behind the eye, giving the head a reptilian appearance that has been recognized
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

40

PIVORUNAS

by others (von Schulte, 1916). The cheek's absence is correlated with the absenceof cheek teeth and any form of mastication. The enormous palate is supportedby specialized processes of the maxillary bone that reach backward, and whichhave been described by G. S. Miller (1923) as a part of the telescoping of thecetacean skull.
Transversely, the baleen is separated into a single dominating large
triangular plate, that tends en masse to close the oral cavity on each side fromabove, and a number of ribbonlike medial platelets, of variable form, that areshort and occupy a linear zone between the main lateral plates externally andthe smooth median palatal crest or keel that forms a prominent longitudinalarch along the middle of the roof of the mouth. The terminology for thesevariable features of the baleen has been discussed by Williamson (1973). In thefin whales of the northwest Atlantic, the medial platelets are coalesced into asmall triangular platelet that sometimes even fuses with the main lateral plate.
The baleen closes the entire side of the mouth, except for an oval opening
in front, when the jaws are opened on the order of 10 to 15 degrees. It isinteresting to note that an opening of the mouth greater than this quickly or
abruptly opens the mouth cavity all the way to the rear, and thus completely
frees the lower jaw from the whalebone on the upper jaw. The lower jaw,
thus freed, is allowed to adopt any number of configurations permitted by an
intramandibular kinesis, to which it is known to be adapted (Lillie, 1910, p. 99).
These facts have led to two contrasting hypotheses related to feeding in therorquals; the first is continuous feeding supposed while the jaws are open on
the order of 10 to 15 degrees, and the second is the supposition of intermittant"gulping" or engulfment of dense swarms of the prey. The smallness of theforward aperture in the rorquals when the jaws are open 10 to 15 degrees
argues against the continuous mode of feeding in the rorquals, for filter-feedingvertebrates have a clearcut tendency to develop large mouths that are closed
on the side. Nearly all the anatomical structures that are here described andelsewhere during this study all suggest that the rorquals feed by the engulfmentof swarms of prey, rather than by true filter-feeding, which seems to be confinedto the bowhead and the right whales, where there is also a large opening formedin the front of the mouth.
The main lateral plate of the rorqual palate approximates a right triangle
whose short base is lodged within a matrix on the ventral surface of the palate,
and whose other edge stands externally, so that the hypotenuse sweeps along
the internal face of the plate and produces and supports the fringes that line
the internal border of the baleen (Fig. 3). The triangle has a curve along its
length, causing the apex of the plate, which projects downward into the oralcavity, to be situated further laterally than the lateral edge of the plate's basesecured to the rostrum. This character of the baleen plates in the rorquals
forces a complication upon the jaw kinetics which has not been generally
recognized; namely, the mandibular rami must rotate around the baleen duringopening and closing of the mouth. This rotation may be seen in whales brought
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

41

BALEEN PLATES AND FRINGESbFig. 3.

A sei whale baleen plate and its curvatures, diagrammatically shown.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

42

PI
V OR UNAS

up and p
r
o
c
e
s
s
e
d dur
i
時 Aen
s
i
時， and is 仁O川 rolled by t
h
ea
c
l
d
u
c
t
e
rj
a
¥
1
・
mus
cu
l
a
t
u
r
e
.a
s was demonstratedbyL
i
l
l
ie (
J
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. ci
t
.p
.9
9
)
. Thi
scomp
li
ca
t
ion
i
snoli
n
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icatedi
nt
hecl
a
s
si
caldiagramsdemonslrati
ng t
h
ef
eedi
ng me
chan
ism
orbal
aenop
ter
i
d wh九！
es, wheretheouい・
Varelsweep o[the ¥vhalcbone i
sus
u
a
l
ly
not i
n
d
i
cated. Thisisbyandlarge due t
ot
h
ef
a
c
tt
h
a
tt
he
s
ediagramswere
ザa
rdS
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1
・
c
c
po「t
h
eaduI
ts
t
age had yetbased on foet
almater
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al
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e
a
r
sr
el
a
t
i
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e
l
yl
a
t
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n embryoni
cl
i
f
e
.s
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h
a
ti
ts
generalcon
f
i
g
u
r
a
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o
n can only beseen i
n po
s
t
n
a
ta
ls
pe
cimen日
[
n cr
o
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s
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s
e
c
ti
on t
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ep
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a
te
s show anotheγ bend orcu
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v
e
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h
a
t was e
a
r
li
e
s
t
recogniz
ed by Scoresby int
he bowhead (
1
8
1
0
,p
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7
9
)
. In the rorqual
st
h
e
pl
a
t
e
s are concave p
o
s
t
e
r
i
or
ly and convex an
t
e
r
i
or
ly
, gi
vinga sinuousc
o
u
r
s
e
t
ot
h
es
l
i
tl
i
kes
pa
c
e
st
h
a
tpa
s
sbet
ween consecut
ive pl
a
t
e
s(
F
ig
.3
)
. Thi
scurvehas been found to give r
ig
id
it
yt
o each plate. and atlea
stmakes t
hem r
e
s
i
s
t
deformat
ion i
nt
he c
en
t
ralar
e
a ort
h
e bal
een when considerable pressur
eisbroughtto bearon t
hem. Thisci
rcumst
anc
e mus
tbec
o
n
si
der
eda
sappl
i
cable
onl
yt
ot
he r
or
qu
a
ls
.f
o
rt
h
ee
x
tr
emely f
lexi
b
l
e pl
at
e
s or balaeni
d w・ha
l
e
s
s
ug
g
e
s
t
s an ent
i
r
el
yd
i
f
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e
r
・
ents
i
tuat
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n
,a
shasbeen recogniz
ed by Nemot
o(
l
o
c
.
c
i
t
.p
.1
54
) and Tomil
i
n(
19
5
7
)
. In t
he r
o
r
q
u
a
l
s
,t
h
el
a
t
er
a
ledgeoreachpl
ateterminat
e
sa
sa t
h
i
n bl
ade with a s
harp e
d
g
e
. whi
c
h on theo
therhand i
s
1
・
c
l
a
l
i
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BALEEN PLATES AND FRINGES43

In this way an effective seal can be made between the baleen and the lower
jaw while food is being strained out of the water. These relations are fairly
plain when one examines the baleen in situ on fresh specimens. The close or
intimate relation indicated above between the palatal plates and the lower jaw
can be f'urther demonstrated by the typical presence of furrows and ridges
impressed upon the medial face of the lower jaw, which matches the pattern andspacing of the baleen plates, and suggests considerable pressures brought to bear
between the lower jaw and the distal region of the whalebone in balaenopterid
whales (Fig. 4). These furrows and ridges on the mandible are not a post mortem
artifact of towing the whale in for processing, as this produces patches of freshly
exposed dermis next to zones where the baleen is shredded into long ribbons
along its grain.
Whereas the palatal plates of the balaenopterids are relatively short, sturdy,
and apparently subjected to considerable stresses, the whalebone plates of theright whales are very long, narrow, and straplike, and extremely flexible, evenin dried specimens. What flexibility the rorqual baleen has is lost whenpreserved as a dry specimen.
CHARACTERISTICS OF THE FRINGES

The fringes are formed by abrasion of the tongue against the edges of thepalatal plates. In life they are limp, extremely flexible, and elastic, capableof being stretched a good fraction of their length without breaking. This is
not the case in dried study specimens. The fringes lie freely against the baleen
in any direction, according to the current conditions that might dominate intheir vicinity of the mouth. A randomly-woven net or mat thus has a tendency
to form over a large portion of the plates, where intricate entanglement forces
the fringes to stay close to the margins of the plates for much of the fringes'
length. This tangling tends to vanish along the distal apex of the baleen, andalong the medial margin, where the small medial platelets stand adjacent to
the exposed palatine crest.
The fringes vary in characteristics along the edge of the palatal plates, andmay actually be classified into different sorts (Figs. 5 and 6), which produces
a complication that must eventually be reckoned with when quantitative
relationships or taxonomic criteria are developed for more detailed comparisonof fringes and fringe density between whale species.*
The fringes along the apex or distal tip of the baleen are stiff and coarse,and do not become tangled. The whalebone matrix may be slow to erode awayfrom the fringes here, or else a process of splitting in the plate takes place here,
to help bring about making larger and stiffer filaments, which helps give theventral margin of the baleen the appearance of a brush along its length (Figs.
1 and 2). As already remarked, this portion of the baleen is apparently trapped* Rund (1940, p. 6, figs. 2 and 3) illustrates these two sizes of fringe for a fin whale.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

44

PIVORUNAS

Fig. 5. The characteristics of the fringes from the distal region of the baleen
plates of a fin whale. Only -one large type of fringe is present.

Fig. 6. The characteristics of the fringes from a more proximal portionof a baleen plate from a fin whale. The fringes are arranged into two
kinds in three series, a smaller kind of fringe being intercalated between
the two outer rows of large fringes,

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

BALEEN PLATES AND FRINGES

45

between the floor of the mouth and the tongue medially and the lower jaw
laterally during feeding, effectively sealing the opening between the lower jaw
below and the palatal plates above with an extremely dense set of stiff coarse
fringes. Toward the median line, coarse fringes persist somewhat in the fin
whale, as two layers, adjacent to each face of the plate, giving the face a grained,
grooved appearance to its surface. These fringes gradually become finer as themedial side of the plate is reached. Between these two layers of long and coarse
fringes there appears a finer, shorter type of fringe, which the rest of the
thickness of the plate supplies, so that the thicker the plate is locally, the moreof these finer fringes are accommodated (Fig. 6). They may be as short as one
centimeter or even less, in contrast with the coarser variety, that often reaches 20
centimeters in length. The finer fringes come to dominate in number medially,giving the baleen of the fin whale a fine white silky appearance (occasionallywith black patches of pigmentation that interrupt this texture with a darker
shade of fringes). The most medial fringes are supported weakly by rows ofmedial platelets, in such a manner that slight pressure applied to the layer offringes here, as produced by the palm of one's hand, causes the collapse of theribbons or platelets of whalebone underlying the fringes. This region of thebaleen also appears to be relatively densely fringed, although it has yet to be
demonstrated objectively. It may also be interpreted as a zone of sealing, where
the complex of fringes and whalebone platelets collapses during the feeding
cycle to form a mildly water-resistant barrier that prevents openings fromdeveloping and enlarging into the thinner screen supported by the main lateralplates. By various means the fringes also appear to increase in density toward
the front of the mouth (by the closer approximation of plates) and posteriorly(both by closer approximation of plates and change in plate configuration). In
this way the whalebone appears to be completely surrounded by a region thatprevents the development of openings in its margin while filtration is taking
place (see also below). It is here suggested that not the entire screen surfaceof the baleen takes part in the actual act of filtration, but only a semiovoid
area in the central and rearward portion of the whalebone. At any rate, themarginal area takes on a second function, if it does filtration as well, of acting
as an intermediate sealing area that prevents openings from appearing andgrowing while the food is being strained from the water. This consideration
would prevent a simple relation from appearing when a comparison is attempted
between the total screen areas of different species of mysticete whales for the
purpose of attempting to determine relative feeding efficiencies between species,
unless the filtering, active portion of the baleen is proportionate throughout all
the rorqual species.
In a relationship with water isomorphic or similar to Ohm's law for electric
currents, water is determined to flow along the path of least resistance, and sowould seem to be mostly confined to the central region of the whalebone series,
where the fringe density appears to be minimum (see also below), and where
the plates are most rigid and most widely separated, so that closure between
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

46

PIVORUNAS

plates during stress cannot ordinarily take place. The relative contributions ofthese two factors, first the plates themselves locally closing around the margins
to shut out a water current, and second the relative different densities of fringes
around the baleen, has yet to be determined. In the event that the second
factor should prove to be relatively significant, methods of determining or
calculating fringe density would be needed to establish the part that the fringes
play during the feeding cycle. That a current regime is set up within themouth that involves water flowing along the path of least resistance, which canbe structurally controlled to some degree, has previously been suggested inrelation to the function of the gill slits and gill rakers of fishes (Galbraith, 1967).
Certain of the relations between the fringes and the palatal plates aredemonstrated in Table I, where fringe counts were made along with othermeasurements, of three consecutive plates taken from approximately the middleof the row of a 56-foot male fin whale taken by the Atlantic Whaling Co. at
Williamsport, Newfoundland, in 1972. Each plate was divided horizontally, or
perpendicular to its grain, or the course of the tubules within its substance,
into 3 centimeter ribbonlike units. For each such unit, the number of fringes
it contributed along the plate edge was counted. This was converted into adensity per transverse centimeter. Secondly, it is important to note that the
inner edge of the plate cuts the grain of the tubules at an angle, so that thefringes, relatively dense when considered per transverse or horizontal distance,
are thinned out by having to be spread along a longer edge than this, over avariable length. This relationship holds for all whalebone whales, and has
notable consequences for the narrow plates of the right whales.
Thus, as the table shows for the first fin whale plate, in the ribbonlike unit
between 12 and 15 centimeters from the medial edge of the plate, a total of
285 fringes, or 95.1 per transverse centimeter, both of the coarse and fine variety,pass to the edge of the plate. Since, however, the edge of the plate makes anangle of only about 11.5 degrees with the tubule grain at this location, the edgeof the plate corresponding to this portion of the baleen is 15.2 centimeters long,to produce a density of only 18.8 fringes per direct centimeter of edge. The
sine of 11.5 degrees is approximately .197, and, correspondingly, 3 cm./15.2 ems.
is .197, and .197x95.l fringes per transverse centimeter yields the observed 18.8
fringes per direct edge centimeter. Thus the steeper the edge of the plate, andthe more acutely it cuts the angle of the plate's grain, the more thinned out
are the fringes. Thus, as can be seen in the table, the thinnest densities tend
to occur along the middle of the edge of the plate, where the plate is steepest,
notwithstanding the fact that it is also relatively thick in cross-section here
as well, and so relatively densely fringed when considered by transverse or
horizontal units of distance. Local irregularities in plate form, which commonlyoccur, prevent a perfectly smooth trend in fringe densities as taken along theplate's edge. The tables somewhat weakly suggest an increase in density
distally, but this emerges from the increased fringe size that predominates here.
Likewise, the increase in density is only weakly suggested medially. Here theSci. Rep. Whales Res. Inst.,
No. 28, 1976.

47

BALEEN PLATES AND FRINGESTABLE 1. FRINGE AND PLATE PARAMETERS MEASURED FOR THREE
CONSECUTIVE BALEEN PLATES TAKEN FROM THE MIDDLE OF THE
BALEEN ROW OF A 56-FEET MALE FIN WHALE TAKEN IN
NEWFOUNDLAND, 1972. FOR FURTHER EXPLANATION
OF THE PARAMETERS SET FORTH IN THIS TABLE,
SEE THE TEXT.
Position Number ofof plate
fringes in
portion3 transverse
counted or horizodtal
ems.

baleenplate
no. 1baleenplate
no. 2

baleen
plate
no. 3

0- 3

3- 6
6- 9
9-12
12-15
15-18
18-21
21-24
24-27
0- 3
3- 6
6- 9
9-12
12-15
15-18
18-21
21-24
24-27
27-30
0

3

3- 6
6- 9
9-12
12-15
15-18
18-21
21-24
24-27

102
124
170
194
285
264
211

135
85
118
137
187

Number ofLengthfringes inalong edge
1 transverse corresponding
centimeterto the 3 cmcounted

34.1

3.9

41. 3

7. 1

56. 7
64.6
95. 1
88.0
70.3
45.0
28.4
39.4
45. 7
62.3

Number offringes per
cm. ofdirect edge

3. 7

26.2
33.8
18.3
18.8
18.8
18. 7
26. 1
16.8
26.6

4.0
7.5
9.6

45.0
18.3
19.5

9.3
10. 3

15.2
14. 1
8.1
8.1

Plate
thicknessin mm.

Sin /7

I. 35

3. 49
3.02
2. 80

. 769
. 423
. 323
. 291
. 197
. 213
. 371
. 371
. 937

I. 69

. 750

I. 95

2. 75
3.23

3. 70
3. 75

!. 94

.400

2.03

. 312

. 273
.206
.206

234

77.9

11. 0

21. 3

2.42

314
305
213
157
79
22

104. 5

21. 5

3.52

20.9
26.6
19.2

3.89

22.3
7.3

14.6
14.6
8.0
8.2
3.0
3.0

101. 5
71. 0
52.4

124
134
184
229
308

102. 8

294

97.9

204

71. 3

146

48.6
29.3

88

3.54

. 375

2.80

.366

26.3

2.47

I. OOO

7. 4

!. 11

!. OOO

41. 3

4.2

29.5

!. 40

. 714

44. 7

7.6
9. 1
10. 6

21. 6

13.6
14.1
8. 7
8.6
3.6

22. 7

2.00
2.20
3.05
3.20

. 395

61. 4
76.3

17.6
20.2

20.9

3.52

23.5

3.49

17.0

2. 68

24.5

2.58

. 329
. 283

. 220
. 213
. 345
. 349
. 833

plates are relatively more numerous than their counterpart main lateral plates,and so provide a surplus of fringes in the medial palatal zone.
It will also be found that plate thickness is positively correlated with thenumber of fringes per transverse or horizontal centimeter of plate for thesethree fin whale plates. This correlation is only weakly developed for the fin
whale, however, due to the presence of two different kinds of fringes. ThereSci. Rep. Whales Res. Inst.,
No. 28, 1976.

48

PIVORUNAS

is one linear regression from the lateral edge of the plate to its center, where
the large fringes dominate and the plate is relatively thicker to support them,and another regression from the center to the medial edge, where the finer
fringes dominate. A stronger correlation may perhaps be found in other whales,
if there is not the same strong distinction between two different classes of fringes.
QUANTITATIVE CONSIDERATIONS
The fringes of the whalebone are the functional portion of the baleen, that
actually take part in capturing or imprisoning the food. The mechanism
apparently varies with the food item. Copepods and other minute plankton may
be strained out of the water somewhat inefficiently by sang mechanisms, whilelarger krill and fish are more easily and effectively retained by being too large
to pass between the fringe filaments and are thus imprisoned within the oralcavity, much as the food of many fish is impounded in the branchial chamberby the gill rakers. If the fringes were absent, most of this food, including fish,
could probably escape between the palatal plates, that are more to be considereda structural support for the layer of fringes which permits at the same time anexit for water passing through the screen. This "fishproof" filter is comparable
in design with that of the whale shark, Rhineodon typus, which was describedand figured by Gudger in 1941. This filter may be contrasted with that of thebasking shark, Cetorhinus maximus, the latter depending in part on the aid of
mucus secretion to help snag food out of the water. That mucus often figuresin filter feeding indicates the innate inefficiencies that are usually present in true
filter feeding mechanisms. Kawamura (1974) has presented evidence indicating
a similar inefficiency probably being present in the straining mechanism of thesei whale. The whale shark, with its "fishproof" filter is known to prey onfish schools (Gudger, 1915), while the basking shark is confined to feed on more
relatively inert plankton (Schnakenbeck, 1955), since its filter apparatus is notparticularly effective in restraining fish, as is also the case with the filter-feeding
Mississippi paddlefish, Polyodon spathula, (Imms, 1904). Due to the effect of aboundary layer in moving fluids, snagging mechanisms in filtration apparatuses
are likely to be inefficient (for a reference to boundary layer phenomena, cf.
Schlichting, 1968).
The denser the layer of fringes, the more effectively it retains food, but theharder it is to pass water through it and out between the plates, so that fringe
density has a minimum and maximum level between which there must lie an
optimum condition. This optimum condition will have a certain degree of
inefficiency, depending upon the type of food. The density of fringes covering
the baleen palatal plates seems to be controlled by a number of factors, no oneof which necessarily may stand out from species to species, according to thepreliminary observations so far made on various whalebone whales. That fringe
density is apparently correlated with the hydrodynamics of the whale's feedingmechanism implies what Nemoto (loc. cit.) suggested, that fringe density is not
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

BALEEN PLATES AND FRINGES

49

primarily correlated with food type (p. 155).
Fringe density can be formulated in several different ways: either as thetotal surface area of fringes per unit of screen surface, or as the total fringe
volume per unit of screen area. It may also be conceived as a total length offringes confined to each unit of area. Comparison between right whales andsei whales with such balaenopterid species as the fin whale shows that fringe
radius plays an important role in affecting the density. This excludes thedensity parameter expressed as the total length of fringes confined to each unitof area from consideration. The fact that fringe filaments can be approximatedas narrow circular cylinders allows the implication that volume is kept at aminimum while fringe surface area is made large. Volume density would
indicate the quantity of material obstructing the passage of food out throughthe baleen plates, and could also be correlated perhaps with another potentially
useful parameter, porosity. Surface area density on the other hand would
indicate the physical interaction possible between the fringes and the water
passing through them. Doubling the volume by doubling fringe length doubles
the surface area as well. Doubling fringe radius on the other hand quadruples
the volume while only doubling the surface area, thus making the volume versionof the parameter more sensitive to variations in fringe size. This quadrupledfringe volume density can be easily appreciated in comparing the baleen of thesei whale with that of the fin whale (Figs 1 and 2). Note that the denser andmore coarsely fringed surface of the baleen in the fin whale quite effectively
conceals the plates lying underneath. This effect is best brought out by
considering fringe density as the total volume of fringe filaments per unit ofscreen surface area. At any rate, the expressions for fringe volume and fringe
surface area differ simply by a factor of r, the fringe radius, when expressed
as proportionalities.
We thus define the density as being proportional to the average volume,
V, of a fringe, and the number of fringes, n, present:
dcxVn.

(1).

The avera~e volume of a fringe, approximated as a circular cylinder, is
proportional to the square of fringe radius, r, and the average fringe length, 1 :(2).

The number of fringes per unit of area is dependent upon several factors,
which are as follows:
ncx l/w, where w is the space between plates. Other factors being fixed,
doubling the width between plate halves the remaining fingedensity.
ncx b,
where b is the width of the palatal plate's edge. Other factors
being fixed, twice the plate edge thickness is assumed to acommodate twice the number of fringes provided by the plate. Thiscan only be approximate, however, for as shown for the fin whale
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

50

PIVORUNAS

discussed above, there are 2 kinds of fringes involved, anddoubling the thickness would affect only l of the 2 kinds involved,
or both to different proportions.
noc p,
where p is the density of fringe tubules per unit of transverse or
horizontal section area of the plate (see also the discussion above,
regarding Table 1). Doubling p doubles the number of fringes
per unit area. This seems to be achieved in life by usually
decreasing the average fringe radius, so that there is a tendency for
p to be in part a variable dependent on r, and vice versa, which
complicates this analysis, since it involves finding a formula forfringe density based on independent variables.
n oc sin{}, where {} is the angle that the plate's margin forms with the vertical.
(See also the discussion above regarding Table 1) Doubling sin{}doubles the quantity of plate supporting a given surface area ofthe screen, and thus doubles the number of fringes arising in thatarea.
Combining these four proportionalities yields

b .

nocpw sme.

(3)

Substituting (2) and (3) into (1) yields
doc r 2lp_Q_ sin{}word = kr 2l p ~ sin {}(4)

for some unknown constant of proportionality, k. Dimensional analysis of (4)shows that k has no physical dimensions.
Of the factors appearing in formula (4), several seem to be less variable
than the remaining ones, although this is based on preliminary observations.
In particular, w, the width between plates seems liable to least variation fromone species to the next, although in any one individual, it tends to decrease by
about half its value toward the front of the mouth and to the extreme rear.
When too narrow, the space prevents easy flow of water through the baleen,
whereas when too wide, it cannot satisfactorily support the fringes. In the latter
case, the fringes are prone to disentangle and wash between the plates, opening
up gaps among them. This has been observed to happen post mortem in several
sei whales, which seem especially prone to show this variably developed, andin a fin whale (Fig. 8).
There is next to be considered the possibility of a web of interrelationships
which would complicate the significance of formula (4), which is based in formon the ideal that all factors on the right-hand side are all independent variables.
Placing these 6 variables on which fringe density depends into the simplest
scheme, Figure 7, there emerges a set of ten possible complicating interrelationships, of which three seem at present to exist.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

51

BALEEN PLATES AND FRINGES

food type't.

fringeradiusv~ density
tub~lefringelength-fringedensity'plateangle ofi-thickness
plate marginI

plateseparation
Fig. 7. The simplest scheme of interrelationships observed up to now in thecharactedstics of baleen plate form and configuration and fringe characteristics. For discussion, see text.

(1) Fringe radius-fringe length. It seems probable that increasing fringe
radius entails an increase in fringe length, by virtue of making the fringe
stronger and more resistant to wear. Graphing as a histogram the fringes ofa fin whale yields a somewhat bimodal distribution of lengths, one mode long,for the fringes of larger radius. and another mode, among the shorter fringes,
for those of smaller radius.
(2) Plate thickness-angle of plate margin. In balaenopterid whales, there
appears to be valid grounds for believing that plate thickness increases withthe angle of the plate's margin, first as an artifact of wear, and secondly as anelement of design, an effect that strengthens the plate in that portion of
the baleen where rigidity is necessary to keep the screen of the whalebone
functional.
(3) Fringe radius-tubule density. In right whales especially, where there
is a very steep plate angle less than 10 degrees, the tubule density of the plate
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

5
2

PlVORUNAS

島
一
、
叫
書、
察
、思
＇ 雌盟加側四脇膨警
、

F
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g
.8
. Seiwhalebaleen, showing t
hemanne1i
n which t
he f
r
i
n
ge
s
may on occasion ash between t
he p
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a
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, which could r
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n
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. Such regions are
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目

溜感想魅認静思求額議夜明：.~－：~...＿，.町吋Fig.9. A growth pace ina seiwhale, from whichno fringes arise.
Thiszonei
sduet
oaweakdevelopmentofthεtubulematrix duringthat yearsgrnwth. Theangle oft
h
ep
l
a
t
ei
sh
e
r
es
os
t
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.

ringes to accommodate the long andmust increasesharply toprovide enough fvery steep border of the plate
. T his has been made possible by a sharp
reduction in the fring
e radius, which is thus related to the increase in tubul
e
densi
t
y
. O ntheotherhand,iffringedi
ameteristheprimaryvar
iableofconcern.
S
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N
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.28
,1
9
7
6
.

BALEEN PLATES AND FRINGES

53

where it must be small to function well with the food concerned, then the plate
must apparently have a steep angle to prevent the density of fringe filamentsfrom exceeding an optimum level. In all events the fineness of the fringes of
the right whale are correlated with the very narrow plate shape, whether or
not they are truly correlated with the prey taken.
Formula (4) conveniently summarizes several of the phenomena that havebeen above noted in the baleen studied of the various species. One moreinstance is worth noting, regarding the sei whale. An individual was taken at
Blandford, Nova Scotia, which shows the extreme consequences of the "rightwhale effect", where steepness of the plate's margin makes it difficult to develop
a satisfactory supply of fringes along the border. By formula ( 4), an angle ofzero degrees, which has a sine value of zero, implies that fringes disappear fromthat area entirely. Such regions have in fact been found in the steeper regionsof the sei whale baleen, where, for one exceptional pace of growth, no fringes
arise from the plate at all. This is matched more proximally with a bluntlyangled "step", where, by the formula, and as is evident in the photograph of
Fig. 9, a proportionally greater density of fringes arises.
CONCLUSIONS

1. There exist the following variables associated with the parameter offringe density in whalebone whales:a. fringe radiusb. fringe lengthc. tubule density of the plated. palatal plate thickness
e. angle of plate marginf. separation between plates.
2. These six variables may be combined to produce a formula expressing
fringe density as volume per unit of surface area. The use of this formula ismade complicated by at least 3 relations observed between the following
variables:a. fringe radius-fringe lengthb. plate thickness-angle of plate marginc. fringe radius-tubule density.
3. In particular, the plate form is correlated with fringe characteristics by
the presence of a trigonometric relation between the angle of the plate's marginand fringe density, and by plate thickness and fringe density.
4. The fineness of fringes is a sensitive variable that is correlated withplate shape. If fringe fineness is truly correlated with the food taken, it is also
correlated with the angle of the baleen plate's inner margin, and thus with plateform.
5. The lateral edge of the baleen plate in rorqual whales follows a curvethat sweeps outward, and which is everywhere closely related with the medial
Sci. Rep. Whales Res. Inst.,
No; 28, 1976.

54

PIVORUNAS

face of the mandible when the mouth is closed. This relation is substantiatedby the presence of furrows and ridges on the inner face of the mandibles (finwhale), which closely correspond to the configuration of the baleen.
6. The baleen plates arc thickened and arched in several planes, and thisprovides a rigidity that resists closure of the plates by collapse in the central
area of the baleen. This rigidity is in contrast strikingly absent around themargins of the baleen screen, which suggests the presence of a sealing zone thatprevents gaps from developing during the feeding cycle.
ACKNOWLEDGMENTS
This study was carried out while taking advantage of facilities and materials
kindly provided by Dr. Edward D. Mitchell of the Fisheries Research Boardof Canada.
REFERENCESBARGE, J.A.J., 1936. I. Mundhohlendach und Gaumen. In: Bolk, Goppert, Kallius and Lubosch,Handbuch der vargleichenden Anatomic der Wirbeltiere, 3 : 29-48.
ESCHRICHT, D.F. and J. REINHARDT, 1861. Orn Nordhvalen (Balaena mysticetus L.) K. Danske
Vidensk. Selsk. Skrifter, Naturvidensk. og mathem. Ajdeling. 5. Raekke, 5: 435-59tf;
FREUND, L., 1912. Walstudien. Wiener Akad. Situngsber. Math.-Naturw. Kl. 121, Abt. 1, Heft. 810: 1103-1182, 27 figs. and 2 pls.
GALBRAITH, M.G., 1967. Size-selective predation on Daphnia by Rainbow trout and yellow perch.
Trans. Amer. Fish. Soc., 96(1): 1-10.
GUDGER, E.W., 1915. Natural history of the whale shark Rhineodon typus Smith. Zoologica, 1(19):339-389.
GUDGER, E.W., 1941. The food and feeding habits of the whale shark, Rhineodon typus. Journ.
Elisha Mitchell Sci. Soc., 57(1): 57-72.
GUDGER, E.W., 1941. The feeding organs of the whale shark, Rhineodon typus. Journ. Morph.,
68(1): 81-99.
IMMS, A.D., 1904. Notes on the gill-rakers of the spoonbill sturgeon, Polyodon spathula. Proc.
Zool. Soc. London, 1904, pt. 2, 1 pl.
KAWAMURA, A., 1973. Food and feeding of sei whale caught in the waters south of 40°N in the
North Pacific. Sci. Rep. Whales Res. Inst., 25: 219-239.
K,\ wAM URA, A., 1974. Food and feeding ecology in the southern sei whale. Sci. Rep. Whales
Res. Inst., 26: 25-144.
KUKENTHAL, W.G., 1893. Vergleichend-anatomische und entwicklungsgeschichtlicge Untersuchunhen an
Walthieren. Jena, G. Fischer, 1893.
LILLIE, D.G., 1910. Cetacea. In Brit. Antarctic (Terra Nova) Expedition 1910. Zoology, I. Vertebrata. pp. 85-118.
MILLER, G.S. Jr., 1923. The telescoping of the cetacean skull. Smithsonian Misc. Coll., 76(5):1-70.
NEMOTO, T., 1959. Food of baleen whales with reference to whale movements. Sci. Rep. Whales
Res. Inst., 14: 149-290.
RIDEWOOD, W.G., 1922. Observation on the skull in foetal specimens of whales of the genera
Megaptera and Balaenoptera. Trans. Roy. Soc. Lond. 211, Series B. pp. 209-272, 16 figs.
RUND, J. T ., 1940. The surface structure of the baleen plates as a possible clue to age in whales.
Hvalradets Skrifter 23, 22 p.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

BALEEN PLATES AND FRINGES55

SCHLICHTING, H., 1968. Boundary-Layer Theory. 6th Ed. McGraw-Hill, New York, xix+ 747 pp.
SCHX."'KENBECK, W., 1955. (The gill seining apparatus of the basking shark, Cetorhinus maximus.)Zool. Anz., 154: 99-108.
SCHULTE, H. VON., 1916. Anatomy of a Foetus of Balaenoptera borealis. Mem. Amer. Mus. Nat.
Hist., New Series, 1, pt. VI: 389-502, pls. XLIII-LVII.
SCORESBY, W., 1811. Account of the balaena mysticetus, or great northern or Greenland \Vhale.
lvfem. Wern. Nat. Hist. Soc., 1 : 571'!-586, 1 pl.
TO~IILI:\f, A.G., 1957 (1967). 1Vfammals of the U.S.S.R. and adjacent countries. Israel Progr. for
Scientific Translations. Jerusalem, xxi+ 717 pp.
TULLBERG, T., 1887. Bau und Entwicklung der Barten bei Balaenoptera Sibbaldii. Nova Acta Reg.
Soc. Scient. Upsaliensis., Serie 3, 11: 1-36, pls. 1-7.
TUR:-iER, W., 1872. An account of the Great Finner Whale (Balaenoptera Sibbaldii) stranded atLongniddry. Trans. Roy. Soc. Edinburgh., 26(11): 197-251, 4 pls.
WrLLIA~!SO:\f, G.R., 1973. Counting and measuring baleen and ventral grooves of whales. Sci.
Rep. Whales Res. Inst., 25: 279-292, 12 figs.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

ADDITIONAL INFORMATION ON SKELETON OF THE
MINKE WHALE FROM THE ANT ARCTICHIDEO OMURA
Whales Research Institute, TokyoANDTOSHIO KASUY A
Ocean Research Institute, University of Tokyo, Tokyo

ABSTRACTA skull and postcranial bones of the minke whale from theAntarctic, kept at the Irako Natural History Museum, were studiedcomparing with two other specimens reported previously by one ofthe present authors. In general the present specimen supported theobservations made earlier, but the form of the pelvic bone is different
and more study is needed in future in this respect.
INTRODUCTION
Omura (1975) studied two skulls and postcranial bones of the minke whale fromthe Antarctic and found several characters which differ from the minke whale in
the northern hemisphere. Since then we were informed that an another sample
of bones is being kept at the Irako Natural History Museum in Aichi prefecture.
These bones were taken by a request of the museum for display on 4 December
1973 on the Kyokusei Maru, a minke whaling factory ship which operated in
the 1973-74 Antarctic season. Noon position of the ship of this day is 63°33'S
and 120°16'E. A total of 36 minke whales were processed on this day, and fromwhich a complete set of skeleton was collected, but there is no assurance that
all of the bones were taken from single animal.
These bones were transported to Japan in April the following year and had
been hurried in sand nearby the museum for extraction of oil until January
1976. We were permited by the museum to investigate these bones after dug
out from sand and prior to mounting for display. In this paper bones of thiswhale or the Irako specimen are compared with the two specimens (71J2793
and 71]2883) reported by Omura (1975).
SKULL
The skull is comparatively large and its length is 2,266 mm. Size of this skull
is compared with other two specimens in Table 1. As seen in this Table theskull of the Irako specimen is larger than that of 71]2793 but smaller than in
Sci. Rep, Whales Res. Inst.,
No. 28, 1976, 57-68.

OMURA AND KASUYA58
TABLE I.

COMPARISON OF SKULL OF THREE SPECIMENS OF THE
MINKE WHALE FROM THE ANT ARCTIC

Condylo-premaxillary length (mm)Breadth of skull, squamosal (mm)Sex, Body length (m)
- Age

Irako

71]2793*

71J2883*

2,266
1, 1772, 115
1,075

2,350
1,256

?
?

M. 8.5
Ad. 25 years

F. 9. 8
Ad. 39 years* Cited from Omura (1975).

71]2883, suggesting that this skull was obtained from a whale of about 9 m inlength.
Omura (1975) found several distinctions which separate minke whales fromthe Antarctic from those in the northern hemisphere. In the form of the skull
these are : 1. the rostrum is more rounded in dorsal view and flat in profile,
2. anterior margin of nasals is concave and no groove is present on inferior
surface, 3. no triangle region is formed by frontal and parietal (or interparietal)
at vertex, 4. hamular process of pterygoid is short and broad, and 5. lachrymal
is large and rectangular. The present specimen of Irako agrees in general in
all characters listed above. In Figs. 1 and 2 are shown the profile of the skull
and form of pterygoid separetely, on which no further explanation would beneeded.
In the region of vertex (Fig. 3), however, the shape of the frontal issomewhat different from the other two specimens. In the Irako specimen there
are two thin projections of frontal towards nasals and they cover partly posterior
ends of nasals and premaxillaries. At a glance the photograph shown in Fig. 3
resembles in some extent to that of the Matsushima specimen from the North
Pacific (Fig. 4 of Omura, 1975), but the most important point is that in the
Irako specimen no trace of parietal is appearing on the upper surface of thevertex and the nasals are situated very close to the supraoccipital bone, whereas
in the Matsushima specimen the parietal present at the center of the vertex andnasals are at more anterior position. The form of nasals of the Irako specimen
is quite similar to the other two specimens and their anterior margin is concave.
The shape of the lachrymal is similar in general, but shorter and broader
than in the two specimens. Measurements of malar and lachrymal are given
in Table 2.
Measurements of the skull are shown in Table 3. The percentage figuresof measurements against skull length are also compared with two otherspecimens in the table. All measurements for the Irako specimen are very
close to those of the two other specimens, excepting the measuremet no. 28(tip of premaxillary to anterior end of vomer) in which the Irako specimen shows
somewhat greater value. This means, however, a comparatively shorter vomer
and which is thought to be subject to individual or age difference. In any casethe specimens other than the Irako specimen are full grown animal of highSci. Rep. Whales Res. Inst.,
Na. 28, 1976.

C
INKE WHALESKELETOL¥" FROM ANTARCTItv.
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60

OMURA AND KASUY A
TABLE 2. MEASUREMENTS OF MALARS AND LACHRYMALS
OF THE IRAKO SPECIMEN OF MINKE WHALE
FROM THE ANT ARCTIC (in mm)
Length, greatest~

Malar
Lachrymal

Breadth at middle
~'
Right
Left

Right

Left

246
348

250

38

38

229

105

106

age, but the age of this specimen is not known.
In the skull measurements Omura (197 5) noted several distinctions amongminke whale populations from the Antarctic, North Atlantic, and North Pacific.
These are in the Antarctic specimen: 1. breadth of skull is narrower than inthose from the other two oceans, 2. rostrum is longer than those from the North
Pacific, 3. breadth of rostrum at base is narrower than those from the othertwo oceans, and 4, breadth at middle of rostrum is narrower than those fromthe North Atlantic. In these characters the figures for the Irako specimen(measurements nos. I 0, 11, 12, and 16) are all within the ranges of the othertwo specimens as seen in Table 3, and no change of observation is needed. In
conclusion the skull of the Irako specimen agrees well in general with the othertwo specimens from the Antarctic.

VERTEBRAE
The character which separates minke whales from the Antarctic from those in
the northern hemisphere in vertebrae is in the 7th cervical (Omura, 1975). In
minke whales in the northern hemisphere the 7th cervical has parapophysis
though it reduced to a tubercle, whereas the two specimens from the Antarctic
were lacking parapophyses and no sign of tubercle was noted. Also in the Irako
specimen parapophysis is lacking as seen in Fig. 4, but in this specimen there isvery low elevation of bone on the surface of body or a sign of tubercle, though
it is not clearly shown in the photograph. In this specimen the 2nd and 3rd
cervicals are united at lateral margins of the spinous processes.
In total 48 vertebrae were preserved in the Irako specimen. These are 7
cervicals, 11 dorsals, 12 lumbars, and 18 caudals (Fig. 5), but the size of the 18th
caudal is much larger than the expected size of the last, comparing with thoseof the other two specimens. It is possible, therefore, that the last caudal was
missed when sampled and the vertebral formula of the Irako specimen should be
C 7, D 11, L 12, Ca 19, total 49. This total number of 49 is in close agreementwith the other two specimens which numbered 49 and 50 respectively.
In the Irako specimen the vertebral epiphyses are not all fused to theircentra. Posterior epiphyses of the vertebrae from 3rd dorsal to and inclusive
2nd lumbar are not fused and in the 6th dorsal also anterior one is not fused.
In all of the above vertebrae linea epiphysialis is quite visible even in thoseSci. Rep. Whales Res. Inst.,
No. 28, 1976.

61

MINKE WHALE SKELETON FROM ANT ARCTICTABLE 3. SKULL MEASUREMENTS OF THE IRAKO SPECIME!'<OF MINKE WHALE FROM THE ANTARCTIC, COMPAREDWITH OTHER SPECIMENS
lrako specimen

Measurements

.~~
0

100
70. 6

I.

Cond y lo-premaxillary length

2,266

2.

Length of premaxillary, rightI, 6003.

, left4.

,, maxillary, superior, right

5.
6.

left

~

in mm

71j2793 and71J2883 (%)
100*
70. 4 - 72. 8

I, 633

72.1

71. 4- 72. 6

1,566

69. I

68. 6- 70. 0

1,586

70.0

70.0

Tip of premaxillary to vertex

1,668

73.6

71. 9- 72. 8,, nasalsI. 44563.8

64. 5 - 66. 0

8.

Length of nasals, median

183

8. 1

6.3.

9.

Breadth of nasals, anterior

118

5.2

7.

10.

Length of rostrum

1, 502

66.3

11.

Breadth of rostrum at middle

462

20.4

12.

Breadth of rostrum at base

727

32. I

13.

Breadth across maxillaries at vertex

236

10.4

14.

Breadth of frontal across nasals

250

11. 0

16.

Breadth of skull, squamosalI, 17751. 9

17.

, frontal

I, 14950. 7

18.

, maxillaries

1, 113

49. I
8.4

19.
20.

Length of orbit, frontal, right191, left

192

8.5

21.

Breadth of occipital bone

906

40.0

22.

Breadth across occipital condyles

209

9.2

23.

Height of occipital condyle, right

126

5. 6

123

5.4
3.2

"

, left24.
25.

Breadth of foramen magnum

72

26.

Height of foramen magnum

100

4.4

27.

Length from foramen magnum to vertex

628

27. 7

28.

Tip of premax. to anterior end of vomer, median,, palatine, median

29.

"

30.
31.

,, posterior ,,32.

Breadth across hamular processes of pterygoid

33.

Length of mandible, straight, right,, pterygoid

422

18.6

1,591

70.2

1,966

86.8
92. I

2,087
234

10. 3

2, 18696.5

34.

, left2, 18596.4

35.

, curved, right

2,340

103. 336.
37.

' leftHeight of mandible at coronoid, right

2,330

102.8

267

38.

, left

283

11. 8
12.5

39.

,, condyle, right

200

8.8

208

9.2

40.

, left• Actual length of skull is shown in Table I.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

7.2
4. 6- 5. 8
64. 0- 69. 4
18. 9- 22. 7
29. 8- 32. 8
8. 8- 10. I
10. 9 - 11. I
50. 8- 53. 4
49. 5 - 51. 9
46. 9 - 48. 7
8. 9- 8. 8
8. 8 - 9. 0
35. 9 - 37. 7
9. 6 - 9. 7
6.2
5. 9- 6. 0
3. 3 - 3. 4
4. 6- 5. 4
27. 7 - 28. 6
12. 2 - 12. 3
69.9-71.2
84.3-87.4
91. 5
9. 9- 10. 0
97. 2- 97. 5
96. 4- 98. I
104. 4-106. 2
104.0-106.9
13.2-14.3
13. 4- 14. 3
9. 4- 9. 5
9. 6- 9. 9

62

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64

OMURA AND KASUYARIBS AND STERuνI

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ig
.7
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:
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o specimen ofminke whalefrom t
he Antarctic.
γ ABLE 5. STRAIGHT LE!'¥GTH OF RI
BSO FT HE IRAKOSPECIME'"OF MINK E W HALE FROM T HE :¥:‑.ITARCTIC (in m m)
No.

LengthNo.

＿，、一−ー、

し巴f
l

1
,
289

I
.
243

I
.262

3
・ 9・ え d

1
,300

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Right
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t

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77

ll

71
4

1,078

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744

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I
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1
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1
,098
1
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l,099

S
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6
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C
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NKE W HALE SKELETOJ
ルfI

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.
he 71
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SCAPULA AND FLIPPER BON巳S
her
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OMURA AND KASUY A

66

TABLE 6. MEASUREMENTS OF SCAPULA OF THE IRAKO SPECIMENOF MINKE WHALE FROM THE ANT ARCTIC (in mm)

Greatest breadthGreatest height
Length of acromion, inferior
Breadth of acromion, distal end
Length of coracoid, inferior
Breadth of coracoid, distal end
Length of glenoid fossa
Breadth of glenoid fossa
Ratio of breadth against height

Right

Left

789
478
218
61
121
51
154
117

774

474
228
66

127
48
154
116
I. 63

I. 65

TABLE 7. MEASUREMENTS OF HUMERUS, RADIUS, AND ULNA OF THE
IRAKO SPECIMEN OF MINKE WHALE FROM THE ANTARCTIC (in mm),,________
RadiusHumerus

Length*Breadth*

Ulna

R~eft

Right

Left

R~eft

305
148

492
68

489
69

534
105

307
150

532
104

* Measured at middle.
TABLE 8. LENGTH OF PHALANGES OF THE IRAKO SPECIMENOF MINKE WHALE FROM THE ANT ARCTIC (in mm)
Phalanx

2
3
4

5

6
7

Right

Left

I

II

III

IV

86
85
75
57
21

85
95

95
101

58
62
64

77

77

57
38
25
14

55
37
23

40

83
86
74
58
33

II

III

IV

97
103

85
94
78
57

64
64
39

77

53
35
24
15

60

40

26
16

The phalangeal formula of the lrako specimen is l 5 , Il 7, III 6 _ 7, IV 4, but
probably some small distal bones were missed at the time of sampling.
Measurements of phalanges are shown in Table 8.
HYO ID AND PEL VIC BONES

Hyoid bone of the Irako specimen is of no special feature and resembles tothose of other specimens reported by Satake and Omura (1974). Its transverse
breadth is 445 mm, height at middle is 102 mm, and the depth between two
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

MINKE WHALE SKELETON EROM ANT ARCTIC

67

forward promontories is 34 mm. Length of right and left stylophyals are 310
and 305 mm respectively.
Pelvic bone of the Irako speeimen (Fig. 10) is of some interest. This bone
was taken possibly from a male, but it differs in form from that of thespecimen 71]2793 from the Antarctic as well as from that of a specimen fromthe North Pacific (compare with Figs. 12 and 13 of Omura, 1975). Length andwidth of the pelvic bone of the Irako specimen are 205 and 44 mm in the rightbone and 202 and 44 mm in the left bone respectively. These figures are very
close to those of the specimen 71]2793, but the form is different. In the Irako
specimen bones are a little slender and curving inwards. Further the tubercle
or tuberculum laterale is not situated towards the middle of the bone, differingfrom that of the specimen 71J2793. Omura (1975) listed the pelvic bone in
Fig. 14 of his paper as one of the characters which separate the minke whale
population from the Antarctic from that from the northern hemisphere, but thisneeds further examination in the light of the present knowledge. Rather a wide
individual variation in the form is expected.

Fig. 10.

Pelvic bones of the lrako specimen of minke whale from the Antarctic.

ACKNOWLEDGMENTS

Our sincere thanks are due to the staff of the Irako Natural History Museum.
They not only permited us to investigate the bones, but also helped us greatly
during our work at the museum. The photographs shown in Figs. 2 and 3 weretaken by the staff.
REFERENCESOMURA, H., 1975. Osteological study of the minke whale from the Antarctic. Sci. Rep. Whales
Res. Inst., 27: 1-36.
SA TAKE, Y. and H. OMURA, 1974. A taxonomic study of the minke whale in the Antarctic bymeans of hyoid bone. Sci. Rep. Whales Res. Inst., 26: 15-24.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

68

OMURA AND KASUY A
APPENDIX.

MEASUREMENTS OF VERTEBRAE OF THE IRAKO SPECIMENOF MINKE WHALE FROM THE ANT ARCTIC (in mm)

Serialno.

Vertebralno.

Greatest
breadth

1
2
3
4
5
6
7
8
9
10
II
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49

c 1

387
539
511
488
519
510
511
522
523
492
520
570
636
684
703
715
703
709
667
665
674
669
659
650
629
636
625
598
594
504
458
419
366
303
237
T.P. disappear

2
3
4
5
6
7
DI
2
3
4
5
6
7
8
9
10

11
L I
2
3
4
5
6
7
8
9
10

II
12
Ca 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19

Greatestheight
237
246
197
190
194
205
210
230
294
340
374
395
412
432
453
452
476
493
521
528
544
569
576
594
599
588
589
596
572
562
528
505
453
410
364
309
271
239
207
S.P. disappear

Breadth
211
206
161 *
156
152
150
148
153
163
163
164
163
163
167
165
171
176
175
174
178
177
180
182
184
186
191
194
203
205
209
210
210
209
213
222
217
198
170
153
143
131
112
101
88
71
55
39
38

Centrum
HeightR. 128, L. 126
136
110*
110
117
117
118
119
121
121
123
125
127
127
125
123
125
124
137
141
144
145
148
156
156
155
154
161
171
169
171
178
189
196
201
202
200
190
184
151
116
97
89
74
59
43
33
23

?

Length
66
35
26
30
34
37
42
52
66
83
98+
106+
119
131
144
147
151
156
162
166
173
178
187
188
195
200
207
214
221
228
232
236
234
232
226
218
206
189
160
112
82
72
68
58
46
37
31
24
?

* Measured from posterior side, since 2nd and 3rd are united together.
In other bones all from anterior side.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

A SKULL OF THE MINKE WHALE DUG OUT FROM OSAKAHIDEO OMURA
Whales Research Institute, Tokyo

ABSTRACT

Among collections of bones of whales dug out from Osaka and now
being kept at the Osaka Museum of Natural History is included ahalf-broken skull of the minke whale, Balaenoptera acutorastrata. Aftercomparing with known specimens of this species this whale wasestimated to be a full grown animal of about 9 m in length.

INTRODUCTION

During several years in 1960's a number of bones of whales have been dug
out from various places in Osaka city while large-scale construction works suchas subways, expressways, and buildings were going on (Shindo, 1975). Thesebones are now being kept at the Osaka Museum of Natural History and I hada chance to observe these bones in December 1975 and found a half-broken
skull of the minke whale is included among the collection.
In addition to these, bones of sperm whale were also dug out recently fromunderground of Higashiosaka city. The species of this whale was identified
by Okazaki (1975) by the presence of the characteristic atlas and a tooth among
the collection.
At the period of Jomon Transgression (about 7,000-3,000 B. P. [years before
present]) a vast area from Uemachi Upland, where Osaka castle is situated,
eastwards and including Higashiosaka city to Ikoma mountain had been
invaded by sea water, forming a bay called Kawachi-wan. This area is now
the Osaka Plain. The development of the Osaka Plain was studied by
Kajiyama and Itihara (1972) with reference to the radio-carbon dates. They
recognized nine successive stages of the development. In the second or thestage of the Paleo-Kawachi Plain (ea. 9,000 B. P., earliest Jomon age) the sea
level was lower than in the present by 20 m or over. Osaka Bay was alreadyin existence, but the Kawachi area was not covered by sea water. In the thirdor the stage of the Kawachi Bay I (ea. 7,000-6,000 B. P., the first half of early
Jomon age) the sea level reached to that of the present and the Paleo-Kawachi
Plain was widely covered by sea water. In the fourth or the stage of the
Kawachi Bay II (ea. 5,000-4,000 B. P., latest early Jomon to middle Jomonages) the sea level remained nearly unchanged, but in the next stage of the
Kawachi Lagoon (ea. 3,000-2,000 B. P., latest Jomon to the first half of Yayoi
ages) due to the development of the sand bar north of the Uemachi Upland,
Kawachi Lagoon was formed and the inner part of the bay was filled with
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 69-72.

70

OMURA

fresh water. The growth of the sand bar continued and it developed
successively into the stages of the Kawachi Lake I and II, Osaka Plain I, andfinally to the stage of the Osaka Plain II or the present.
In the 3rd and 4th, and also in the 5th stages too, it is possible that whales
came into the Kawachi Bay and some of them stranded ashore or dead afloat
and finally sunk. This is the possible explanation why bones of whales dug
out from the alluvial deposits in Osaka. It is also possible, therefore, thatthese bones are of the existing whale species.

OBSERVATION AND CONCLUSION(Plates I and II)

This skull (0. M. N. H., F2639) was dug out from 14 m deep while constructmg
underground railroad at 2-Chome, Oimazato-hommachi, Higashinari-ku, on 11
August 1966. The skull was broken transversely towards middle part of thesupraoccipital bone by mishandling during preparation for transportation after
discovering. Its posterior portion is remaining in a very good condition,suggesting the skull was a splendid specimen before it was broken. Exo- andbasioccipitals, and temporals are nearly perfect, enabling me to measure thebreadth at squamosal or the greatest breadth of the skull, as well as othermeasurements concerning posterior region of the skull precisely. Posterior
marginal portion of the vomer is remaining attached, but pterygoids arebroken and tympanic bullae are lacking.
Vertex and facial region of the skull are completely broken, but orbital
process of the frontal of both sides, part of vomer, 170 cm in length, and somefragments of maxillary and premaxillary are remaining separately. Frontals
are broken at their proximal ends and their distal margins or orbits arecomplete and the orbital length was measurered accordingly.
At a glance this skull can be identified to be a species of balaenopterid
whales (Balaenopteridae) and from its comparatively smaller size to be theminke whale. Measurements of the skull are shown in Table 1, comparing
with corresponding measurements of other specimens from the North Pacificand Antarctic, cited from Omura (1975). Measurements numbers in the table
are the same as used in the previous paper (1975). The breadth of the skull
at squamosal of this specimen (F2639) is far greater than in the two specimensfrom the North Pacific (A Y69B, A Y69A), and lying between figures for thetwo specimens from the Antarctic, suggesting the body length of this whale isalso between these two specimens, i. e. 8.5-9.8 m and possibly around 9 m.
These two whales from the Antarctic are physically matured (Omura, 1975)
and since the body length at sexual maturity of minke whales is somewhat
smaller in those from the North Pacific than in those from the Antarctic(Ohsumi et al., 1970) this specimen from Osaka was possibly a full grown whale.
This is also supported by rigid structure of the skull.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

MINKE SKULL FROM OSAKATABLE 1.

71

MEASUREMENTS OF THE SKULL (F2639) COMPARED WITH THE
KNOWN SPECIMENS OF THE MINKE WHALE (in mm)

Measurements

F2639
Osaka

AY69B*
N. Pacific

AY69A*
N. Pacific71]2793*
Antarctic

71]2883*
Antarctic

16.

Breadth of skull at squamosal

1,180

708

1,256

Length of orbit, frontal, right
Length of orbit, frontal, left

207
206

156

613
146

1,075

19.
20.

157

146

188
190

207
207
886
228

21.

Breadth of occipital bone

822

563

473

760

22.
23.

Breadth across occipital condyle
Height of occipital condyle, right

229

157

124

98

154
120

203
131

24.
25.

Height of occipital condyle, left
Breadth of foramen magnum
Height of foramen magnum

124
79

96
83

100

124

80

70

79

60

90

85

97

127

M. 6.6m
juv.

M. 5.4m
juv.

M. 8.5mad.

F. 9.8m
ad.

26.

Sex, body length, and age

145
142

• Cited from Omura (1975).

In other measurements figures for this specimen are within the ranges ofthe values of the two specimens from the Antarctic or very close to them,
except the measurement no. 26 (height of foramen magnum), which is thought
to be of less importance. From this table it can safely be concluded that thisspecimen is a skull of the minke whale, Balaenoptera acutorostrata. Thereremains, however, still a taxonomic problem among minke whale populationsof the world, i. e. a possibility that the Antarctic minke whale, B. bonaerensis,
is in fact a different species or subspecies of the minkes in the northernhemisphere, B. acutorostrata. But the distinctions so far noted in the skull
are in the vertex and facial regions and not concern the posterior portion of
the skull (Omura, 1975). Accordingly this problem does not affect the above
conclusion.
ACKNOWLEDG MENTS
My sincere thanks are due to Mr. Hiroyuki Taruno and other members of
the Osaka Museum of Natural History. They extended me all possible
arrangement and help for the works done at the museum. Mr. H. Taruno
also read and commented on draft of the manuscript.
REFERENCES
KAJIYAMA, H. and M. ITIHARA, 1972. The developmental history of the Osaka Plain withreferences to the radio-carbon dates. The Memoirs of the GeologiJal Society of Japan. 7: 101-112.
(In Japanese with English abstract).
0HSUMI, S., Y. MASAKI and A. KAWA MURA, 1970. Stock of the Antarctic minke whale. Sci.
Rep. Whales Res. Inst., 22: 75-125.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

72

OMURA

OKAZAKI, Y. 1974. Higashiosaka-shi de Makko-kujira no Hakken (Bones of sperm whale
discovered in Higashiosaka city). Nature Study (ed. Osaka Museum of Natural History). 21(12): 143-144. (in Japanese).
OMUR.-\, H. 1975. Osteological study of the minke whale from the Antarctic. Sci. Rep. Whales
Res. Inst., 27: 1-36.
SHl'.'iDO, N. 1975. History of whales in the Inland Sea. Hyogo. 89pp.

EXPLANATION OF PLATESPLATE I
Half-broken skull of the minke whale dug out from Osaka and now being
kept at the Osaka Museum of Natural History. F2639.
Fig. I. Posterior view.
Fig. 2. Anterior view.
PLATE II
The same specimen shown in Plate I.
Fig. I. Superior view.
Fig. 2. Inferior view.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

d
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PLATE I
I

OルfURA

S
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RECONSIDERATION OF LIFE HISTORY PARAMETERS
OF THE SPOTTED AND STRIPED DOLPHINSBASED ON CEMENTAL LAYERSTOSHIO KASUY A
Ocean Research Institute, University of Tokyo, Tokyo

ABSTRACT

Growth layers are visible in both cementum and dentine of thedecalcified and stained teeth of Stenella attenuata and S. coeruleoalba. Theiraccumulation is annual in young dolphins, but in older animals only theaccumulation of cementa! layers are detected. Growth of the dolphin
lasts longer than expected from previous studies. The maximum age
is more than 45 years and sexual maturity is attained at 9 years infemales of both species. Annual natural mortality rate of 7.5% in S.
attenuata and the total mortality of 11.8% in S. coeruleoalba are estimatedfor adult females. In immature animals the mean mortality is lower,
and higher in adult males. Annual ovulation rate is about 0.41 inboth species. Reproductive parameters are analysed in relation to theage of animals and the present population level.
INTRODUCTION

The age determination of delphinids has been made by counting the growthlayers in dentine or cementum. The accumulation of layers was shown to beannual in case of Tursiops truncatus based on the animals born and died in an
aquarium (Sergeant 1959, Sergeant et al. 1973). Sergeant (1962), Kasuya (1972),
and Kasuya et al. (1974) also indicated the possibility of the same accumulation
rate for Globicephala melaena, Stenella coeruleoalba, and S. attenuata
respectively based on the materials covering limited seasons, and analysed thelife history of those dolphins.
However, through the analysis of life history parameters of an unexploited
population of S. attenuata, Kasuya et al. (1974) concluded that the accumulationof dentinal growth layers ceases in older animals as already indicated bySergeant (1962) for G. melaena. This made it difficult to study the life historyof the species, and even if the life history parameters are estimated by otherindirect method the accuracy was unsatisfactory.
The present study was undertaken to reconsider the life history parametersof the spotted dolphin, S. attenuata, and of the striped dolphin, S. coeruleoalba,
which were fomerly estimated through the analysis of dentinal growth layers
or by other indirect method (Kasuya 1972, Kasuya et al. 1974, Kasuya andMiyazaki 1976). Since the cemental layers abandoned in the study by Kasuya
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 73-106.

KASUYA

74

et al. (1974) were found in this study to be readable if the teeth were stained
after the decalcification of a thinner ground section.
MATERIALS AND METHOD

All the materials used in this study were collected from the catch of the drive
fishery off the Pacific coast of Japan. Though the samples were collected
randomly from the catch, as the species have the tendency to form a separate
schools in relation to the sex, growth and reproductive stages (Kasuya 1972,
Kasuya et al. 1974, and Miyazaki 1975) and also some members of a school
will be lost during the drive, the samples are not necessarily an unbiased
representative of the population. This bias was considered in the analyses.
As shown in Table 1 all the samples of S. attenuata are the same as thoseused by Kasuya et al. (1974) except for 2 schools (nos. 8 and 9), which were
examined by Mr. S. Matsui of The Taiji Whale Museum and by myself
respectively. The data from these two schools were used only for the estimationof the sex ratio at birth.
TABLE I.
Schoolno.

SpeciesS. attenuata

SOURCE OF MATERIALS USED IN THIS STUDY
Date ofdriving

23, Oct., '70
10, Nov., '70
4, Nov., '72
3
4
13, Nov., '72
516, Nov., '72
12, Feb., '73
6
72, Ju!., '73
824, Jan., '75
916, Jan., '76
S. coeruleoalba 14, Dec., '71
22
38
17, Nov., '72
15, Nov., '73
43
20, Nov., '73
44
23,24, Nov., '75
45,46

Place ofdriving
Kawana

2

Fu to
Taiji

KawanaNo. dolphinscaught examined
264
1381

131
273

189
192
67
146
60
102
91
903
411
414
1724
1000

48
117
23
122
36
102
44
3061 )
203
250
470
399

No. dolphins aged
males females
17
9
17
54
7
45
9

27
15

217 2l

62 2l

37
105
78

68
65
81

13
54
15
67
9

1) All immature except 7 sexually mature males.
2) Based on dentine layers read by ordinary method.

The materials of S. coeruleoalba were collected from the catch of six drives
off the lzu coast. The school numbers in Table 1 are the same as those usedby Miyazaki (1975). Though the five schools from nos. 38 to 46 in Table 1 werecomposed of mature and immature animals of both sexes, the school no. 22 waspeculiar in the extreme scarcity of mature animals and the higher ratio of themales as indicated in Table I and Figs. 18 and 19 showing the age composition.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

75

From school nos. 45 and 46, only the informations on body length, sex, and ratioof reproductive stages of adult females are available.
The growth layers were counted independently by three methods on alongitudinally sectioned tooth. The first is the ordinaly one (Kasuya et al.
1974), or to count the opaque dentinal layers under transmitted light with astereoscopic microscope ( x 50 to x 80). The thickness of these sections was 50
to 70µ. For the second and the third methods, the tooth slides used for the
first method were ground thinner to a thickness between 10 to 20µ, anddecalcified in the 5% water solution of formic acid for several hours. Then they
were stained with Mayer's haematoxylin solution and mounted with glycerin.
By this preparation the dentinal and cementa! growth layers are observed clearlyas the well stained and poorly stained layers arranged alternatively. For theage determination by the second method, the number of stainable dentinal layers
was counted with a microscope ( x 100). The f et al dentinal layer is not includedin the count. The disagreement of repeated count by this method was less than
5%. The counting of cementa! layers, the third method of age determination,
was made with a microscope ( x 150) on a same slide used for the second, andat a part of the thickest cemental layer, which usually situates at a position
between cervix and the midlength of the root. Though the arrangement of
cementoblasts seems to be correlated with the stainable cementa! groundsubstance, the counting of the layer was made on the condition of the latter. Three
counts were usually made on the best spot of a slide and the middle figure wasused as the number of cementa! layers. The disagreement of the repeated counts
was usually from 5 to 15%. The discrepancy of the repeated counts is larger
in older animals. The fetal cementa! layer was not usually detected by theabove method, and possibly not included in the count.
As one accumulation cycle of the layers consists of a stainable and an
unstainable layer, the real number of the cycles of an animal with n dark layers
is expected to be between n-1.5 and n+0.5. Then the average number of thecycles of the animal is considered to be n-0.5, if the samples are obtained
evenly from all seasons. Though, it is not actually proved if each kind of layer
represent the period of 6 months, the figure n - 0.5 was used tentatively as theapproximate age of the animal.
The presence of corpora in the ovaries was used as the indication of thesexual maturity of the female, and their number was counted by the ordinary
method (Kasuya et al. 1974). Usually the weight of left testis was measured,and the right testis only when the left is not available. The maturity of themale was determined by the testis weight based on the mean weight of single
testis at the attainment of sexual maturity 68 g for S. attenuata (Kasuya et al.
1974) or 16.5 g for S. coeruleoalba (Miyazaki 1975, Kasuya and Miyazaki 1976).

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

76

KASUYARESULTS

Comparison of the methods
The relationship between the number of dentinal growth lyers counted byordinary method and that counted on decalcified and stained dentine is shownin Fig. 1. As the stainable dentinal layer seems to correspond approximately
with the translucent layer or with the part transitional from opaque totranslucent layer of undecalcified dentine, the two counts compared are notindicating the number of same kind of layers. So, the disagreement of only one

25

0

./

S. attenuata

510

S. coeruleoalba

20
25 0
5
10
No. layers (ordinary method)

15

15

20

25

Fig. 1. Comparison of count of dentinal layers made by ordinary method (undecalcified)
and that made after decalcification and staining. Open circle indicates female, closed circle
male, and solid line the equal accumulation rate. Larger circle indicates five animals, andthe smaller one.

layer is not significant, and it is suggested that the two methods can give almost
same result for the dolphins younger than 8 layers and that after this age thecorrelation becomes less. The count on undecalcified tooth with more than
12 layers gives, in general, smaller figure than that on decalcified and stained
dentine. There is detected no sexual difference in this relationship. The
disagreement of the counts of dentinal layers by the two methods will be causedby the difficulty of reading the layers in secondary dentine, or by the difficultyof distinguishing the thin layers of older animals. If so, the count made on
decalcified and stained preparation of thinner tooth section can be a better
indication of the age, since the layers are more clearly observed by thispreparation.
However, when the number of dentinal layers in decalcified and stained
tooth is compared with that of cemental layers of the same tooth slide, the twocoincide extremely well only up to the age of 9 layers in S. atteniiata or theSci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

S. attenuata

77lS. coeruleoalba

25
<II

.£
..... 20
c
<II
-0

.£ 15
(/)

......

<II

fi 10
0

z

5

5

10

15

22 32 42 05No. layers in cementum ·15

22 32 42

Fig. 2. Comparison of the accumulation rate of dentinal and cementa! layers.
counted after decalcification and staining. For other marks see Fig. I.

Layers wereage of 11 layers in S. coeruleoalba (Fig. 2). After these ages the latter usually
gives the higher number, and there is observed almost no correlation between
the number of layers in dentine and cementum in teeth with more than 20
cemental layers. This must indicate that the acumulation of the dentinal layers
ceases at an large variety of age above 9 layers (S. attenuata) or 11 layers (S.
coeruleoalba), and that the accumulation of cemental layers continues longer asin the case of G. meiaena (Sergeant 1962). The ages of the oldest animal were46 cemental layers in S. attenuata and 50 in S. coeruleoalba. They are about
twice as high as those estimated from the dentinal growth layers.

Acciimiilation rate of layers
As the sample of S. attenuata covers wider range of seasons, the seasonalchange of the dentinal growth layer was analysed for this species, Table 2
shows the condition of the dentinal growth layers being calcified at the time
TABLE 2. CONDITION OF DENTINE BEING CALCIFIED
AT THE TIME OF DEATH OF S. ATTENUATA~ntine*Date~

OctoberNovemberFebruary
July

Stainable layer
no. dolphins %

16
62
40

76.2
96.9
95.2
7. 7

* Stained dark or pale by haematoxylin.
Sci, Rep. Whales Res. Inst.,
No. 28, 1976.

Unstainable layer
no. dolphins
%
5

23.8

2

3. 1

2

4. 8
92.3

12

Total
no.

/o

21
64
42

100

13

100

0/

100
100

78

KASUYAof death. Only the animals younger than 9 growth layers were selected here,
because the accumulation of the layer ceases in some animals after this age.
The frequency of the dolphins with the stainable layer at the pulp wall is about
75% in the catch of late October, and it increases to about 95% in November
and February. However the ratio is reversed in early July. This is anindication of that the formation of stainable layer starts, on the average, inearly October and that of the unstainable layer in between March and June.
Kasuya et al. (1974) suspected from the observation of undecalcified tooth
sections of the same animals that the translucent dentine is formed in the seasonfrom December or January to April or May and opaque dentine in the otherseason. As it is easily expected that Kasuya et al. (1974) might have overlookedsome of the translucent layers or opaque layers which were too thin to be
detected on the thicker and undecalcified section, the seasons when the alternationof the layer occurs can be shown slightly delayed in their study than the
result of this study. So the slight difference between the two conclusions
is not significant. This .is another indication of the fact that the dentinal layers
stainable with haematoxylin correspond, as mentioned before, with translucent
layers or with the part transitional from the opaque layer to the translucent
layer of undecalcified section (Plate III, Fig. 2). As the seasonal change of thecondition of the incomplete latest dentinal layers of S. coeruleoalba studied by
Kasuya (1972) on undecalcified tooth section is same with that of S. attenuata
reported by Kasuya et al. (1974), the seasonal alternation of the dentinal layersof the two species seems to follow the same pattern. The present results on theseason of formation of dentinal layers is consistant even with the results on G.
melaena (Sergeant 1962), Hyperoodon ampullatus (Christensen 1973, Mitchelland Kozicki 1975), and Physeter catodon (Ohsumi et al. 1963).
In order to know the growth rate of dentinal layers, the seasonal changeof the thickness of the most recent incomplete layer must be detected. As a
preparatory procedure of this, the change of the thickness of the layers
accompanied with the age of the animal was checked on the enlarged photographsof the decalcified and stained tooth sections of two S. attenuata and two S.
coeruleoalba, some of which are shown in Plates. In these measurements thefirst incomplete layer which start from the neonatal line was not included.
The measurements of the subsequent layers are shown in Fig. 3. The thicknessof the layer of S. coeruleoalba decreases rapidly untill 3rd or 4th layers. After
this age the decrease is almost constant, and the thickness of a layer is about
95% of that of the preceeding layer. This feature seems to be same even in
the case of S. atteniwta, though the thickness of each layer is larger during
the first few years.
The following relationship is lead from this result.

when tn=the thickness of the most recent incomplete layer
T n=the expected thickness of the same layer at the time of completion
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA~---------------~

!''~

.30

'
R, ,o,,.ft ,<i

.25

E

E .zo

,R,

/\

;

I

'

\

P... ..

:~:::~\ \ / \/ \ \~! \~·! 1
:

\

if

..c .15: :\:,:·,:· ·:',:

3 .10

1.0
.8

\,f
ll

::'•

-0

1.2

337

!..•..,',,\.',,,

''

.~

79

0

0

.6 0:

\!
~

.05

.4

161

o~~~5~-'--'~,~o-'-'-~~,L5-'--'-'-L2Lo-'--J-'--L2~5_,_L-..J.2

No. of layers
Fig. 3. Thickness of dentinal growth layers shown in relation to the age of theanimals. Solid line indicate the thickness of each layer, and circle and dottedline ratio of one layer to the former layer. 27: S. attenuata, 183 cm, male, school
no. 7. 30: S. attenuata, 202 cm, female, school no. 7. 161: S. coeruleoalba, 221 cm,
female, school no. 38. 337: S. coeruleoalba, 232 cm, male, school no. 44.

T n-l =the thickness of the one cycle earlier complete layer
T n- 2 =the thickness of the two cycles earlier complete layer
Then, the rate of completion of the most recent incomplete layer, tn/T n' isshown as follows.
_t'!....=t ._Tn-2
Tn Tn-1 2
In the present study the thickness of one layer was measured from the start ofa stainable layer to that of next stainable layer, on the selected teeth of S.
atteniiata at the age betwen 4 to 12 layers. These teeth were selected considering
the preparation, clearness of layers, the regularity of layers, and in older animals
the coincidence of the numbers of layers in dentine and in cementum.
The result is shown in Fig. 4, where 4 schools caught in November aregrouped and plotted on the mean date of catch. Though there is observed asmaller peak in October, November and February, they will have been causedby the measurements of young tooth where the thickness changes rapidly. If thehighest modes were connected there is suspected a slower growth in the period
from November to June. The extraporation of the line connecting the modesin October and November suggests that the starting date of the accumulationof stainable layer is in early October, which coincides well with the estimation
has been made from the seasonal change of the frequency of the two kindsof layers being calcified. As the completion rate at the beginning of Julyis only 45%, the rate of 16.5% per month, which is close to the rate in October
15.0%, must be achieved in the accumulation of unstainable layer formed in
the summer months in order to expect the annual formation of the layer. Thisrate will not be improbable in view of the accumulation rate of opaque layers
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KASUYA

80

100 ,
0

0-

80

.\;;

c 60

.Q

Q;

a.

E 40
0
u
20
0

0

N

D

F

M

A

M

A

s

Month
Fig. 4. Seasonal change of the completion rate of dentinal growth layers.
The numerals at the top indicate the sample size. The interval of one
month corresponds to 5 animals. For further explanation see text.

of Hyperoodon ampullatus, about 30% in the fishing season of May and June,suspected by Mitchell and Kozicki (1975, see their discussion) based on the datareported by Christensen (1973). Possibly the growth of dentine in S. attenuata
is rapid in the summer season when the unstainable layer ( ·. opaque layer onground section) is accumulated, and slower in winter when the stainable layer( ·. translucent on ground section) is accumulated. Though Ohsumi et al. (1963)
showed a different feature on the growth rate of dentine of Physeter catodon,
as they measured the layer not on the thin ground section but on the half-cut
longitudinal section, the exact comparison is difficult at present.
As the conclusion it will be safe to say that the accumulation rate of thedentinal growth layers is annual in case of S. attenuata, and that the similarrate will be expected on the closely related species S. coeruleoalba. Since thenumbers of layers in cementum and dentine are equal in young animal andthe alternation of the layers will be affected by the same physiological change,
the accumulation of cemental layer is also considered to be annual.

Mean growth curve
The relationship between body length and age in S. attenuata and in S.
coeruleoalba are shown in Figs. 5 and 6. As the ages are grouped into eachn-0.5 years, where n indicate the number of stainable cemental layers, and thestainable layer start to be accumulated in the average in early October, theanimals of almost similar age can be grouped into separate age groups affectedby the slight difference of the dates of birth and death, or of the formation ofstainable layer, even if there is no misreading of the layer. In other words,
the difference of one year in the age of each individual is not significant.
The mean growth curves of S. attenuata in Fig. 5 were drawn by eye
referring the curves of S. coeruleoalba where the samples are more abundant,
Sci. Rep, Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

81

200
E 180
u

.!;

..c. 160f>- 140 . "

"C

S

H
120

,,

1001:

0

5

10

15

20

25

35

30

40

45

Age in years
Fig. 5. S. attenuata, scatter diagram of the relationship between body length and age estimatedfrom the cementa! layers (200 females and 158 males). Open circle and dotted line indicate
female, closed circle and solid line male, smaller circle one animal, and larger circle mean
body length. Data in parenthesis are excluded from the calculation.

---.o.;-~---------·-------- ...----------;.-----------------------

140
120
5

10

15

20

25
30
Age in years

35

40

45

50

Fig. 6. S. coeruleoalba, scatter diagram of the relationship between body length and age (340females and 488 males). The age data of the school no. 22 estimated by ordinaly method
were included. The age of other animal was based on cementa! layers. For other marks
see Fig. 5.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KASUYA

82

and are liable to the alteration when more data is accumulated. The bodylength at birth is about 89 cm (Kasuya et al. 1974). The animals of both sexes
attain the mean length of 142.5 cm in the first year. Then the male length
seems to exceed that of female at the age of two years. Though the data isscanty and the minor change of the growth rate is not clear, there might beagain a period, approximately at the age between 9 and 11 years, when themean length of the female may exceed or equal with that of the male. Apartfrom these minor and uncertain features, the general trend of the mean growth
curve of the immature stage does not differ from that shown by Kasuya et al.
(1974). But, as reasonably expected from the possible underestimation of theage in their study, the growth in immature period shown in the present study
appears slightly slower (Table 7). The mean asymptotic length of the female
S. atteniwta is attained at 11 or 12 years (Fig. 7), and the length is estimatedto be 193.9 cm from the mean length of 135 animals at the age more than 12
years. The mean growth curve of the male indicate slower growth after 12
years of age and seems to reach the asymptonic length of 207.1 cm at the age
100 [S. coeruleoa!ba

5. attenuata

E so

u

c

-~

60

11
..c 40
~

e 20

~

0

5

10

15

20

0

5

10

20

15

Age in years
Fig. 7. Annual growth rate of the two kinds of dolphins. The increase in mean
body length between n-0.5 and n+0.5 year groups is plotted at n years of age.
Closed circle and solid line indicate male, and open circle and dotted line female.
The feta! length was cited from Fig. 7 of Kasuya et al. (1974).
TABLE 3.

ESTIMATION OF THE. MEAN ASYl\fPTOTIC LENGTH

SpeciesS. coeruleoalba

S. attenuataSex).1ales

Females

Males

Females

Age range (years)~17. 5~22. 5~12. 5~21. 5

No. of animals

21

135

41

89

Smallest (cm)

195

177

220

200

Largest (cm)

216

211

248

250

Mean (cm)207. I

193.9

236.0

225.3

Standard dev. (cm)

8. 63

4.04

6. 14

15.29

Standard error (cm)

1. 88

0.35

0. 96

1. 62

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

83

of about 22 years.
The mean growth curves of S. coeruleoalba was drawn by eye assuming
99.8 cm for the body length at birth (Kasuya 1972). The age of the school no.
22 was estimated from the number of dentinal growth layers counted by theordinary method, because this does not seem to give bias since the animals
constituting this school are young ranging from 1.5 to 10.5 years of age (Figs.
18 and 19). As the dolphins of larger body length tend to attain the sexual
maturity at an age younger than the shorter animals do (see Kasuya 1972 Fig.
4), and other schools are mainly composed of adult animals, it is necessary to
add the age-length data of the school no. 22 to eliminate this bias.
S. coeruleoalba attains the mean length of 164.0 cm at the age of I year.
The sexual dimorphism of the body length appears at the age of about 2 years
as in the case of S. attenuata, and then the lengths of both sexes increase atan almost constant rate retaining the difference of about 4 cm until the age of
6 years. As shown in Table 7, the growth rate of this period is slightly smaller
than that estimated by Kasuya et al. (1974). The mean growth rate of thefemales increases at the age from 6 to 7 years, and attains at age from 7 to 8
years a length slightly exceeding that of the male. After the age of 8 years,
which is about one year before the onset of sexual maturity, the mean growthof the female becomes slower, and mean growth curve reaches the asymptotic
length of 225.3 cm at about 17 years. Though the growth of the male is slightly
faster at the age between 7 and I 0 years than the preceeding period, theaccelerated growth is not conspicuous. After the age of 10 years the growth ofthe male becomes slower and attains the asymptotic length of 236.0 cm at theage of about 21 years (Table 3).
The mean growth curves of the two species of Stenella discussed here show
similarpattern. The ages when the growth rate changes correspond to theacompletion of weaning at 1.5 to 2.4 years indicated by Kasuya (1972) and in
the latter section of this study, attainment of sexual maturity discussed below,
and the completion of the attainment of physical maturity. Though theaccelerated growth of the male near the attainment of sexual maturity is notconspicuous, the growth rate of the fem ale seems to become higher just before
the attainment of sexual maturity. The fact that the body length of the female
near the onset of sexual maturity exceed that of male at the same age is at
close resemblance to G. melaena (see Sergeant 1962, Fig. 11). The low growthrate preceding the age at asymptotic length might by a reflection of thedecrease of the growth rate of each animal and of the increasing ratio of theanimals which have attained the physical maturity. The age when mean growth
curve attains the asymptotic length will correspond to the age when all theindividuals attain the physical maturity.

Attainment of sexual maturity
When the presence of the scar in the ovary or the testis weighing morethan 68 g (Kasuya et al. 1974) is used as the criterion of the sexual maturity in
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KASUYA

84

S. atteniiata, the youngest sexually mature animals are found in the age groupof 7.5 years (both sexes) and the oldest immature animals in that of 11.5 years(female) or 15.5 years (male). The following formulae are obtained by the least
aquares for the relationship between the ratio of mature animals (y) and theage of the animals (x).
Female: y=l7.43x-106.93

6.5~x~l2.5

Male

6.5~x~ 16.5

: y= 10.59x-74.84

The age where 50% of the animals are sexually mature is estimated from theabove formulae to be 9.0 (female) or 11.8 (male) years (Fig. 8). These values
are slightly higher than those obtained by Kasuya et al. (1974), as expected fromthe limit of ageing by dentinal layers.

.8

S. attenuata
36 females
73 males.~.... .6

138 males

,,

;;J

0

,'1

~ .4

'

'

,' 0

o'

.2

'

I
I

:

I
I

,/

:

/

0 /
6

S. coeruleoalba
110 females

f

~

J

8

10

12

14

16

4

6

8

10

12

Age in years
Fig. 8. Relationships between age and the ratio of sexually mature animals. Opencircle and dotted line indicate female, and closed circle and solid line male. In
S. caeruleoalba smaller circles include school no. 22, and the larger exclude it.

In case of male S. coerideoalba the mean weight of testis at the attainmentof sexual maturity, 16.5 g, was determined Miyazaki (1975), where the presenceof spermatozoa or spermatid in the tissue taken from the center at the midlengthof testis was considered to be mature. In spite of this criterion, there werealways observed both spermatozoa and spermatid in the mature testis (Miyazaki1975) as in the case of S. atteniiata (Kasuya et al. 1974). As shown in Table 4,
this criterion seems to give a same age at the onset of sexual maturity withthe criterion based on the presence of spermatozoa in the epididymal smear.
However other criterion may give different results. For the female S. coeruleoalba, the maturity was determined by the presence of the corpus in the ovaries.
If the age-maturity data of 152 (146 immature and 6 mature) males and
25 immature females of the school no. 22 are dealt together with the data ofschool nos. 38, 43 and 44, the ratios of immature males are unreasonably low
in the age groups below 9 years and the age of 9.7 years is obtained as themean age of the male at the attainment of sexual maturity (Fig. 8). However,Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

85

TABLE 4. COMPARISON OF DIFFERENT CRITERIONSFOR THE MATURITY OF MALES. COERULEOALBA
No. oflayersAge in
years

2

I. 5
2.5
3.5
4.5
5.5
6.5
7.5
8.5
9.5
10.5
I I. 5
12.5
13.5
14.5
15.5

3
4
5
6
7
8
9
10
II
12
13
14
15
16

Testicular smear
imm. mat.
mat.%
2
8
0
2
3
4
0
2
0
0
0
0
0
0

0
2
I
3
6
I
7
6
8
17
29
2
7
4

0
20.0
100
33.3
50.0
85. 7
20.0
100
75.0
100
100
100
100
100
100

Epididymal smear
imm. mat.
mat.%
2
9
I
3
4
2
5
2

0
1

0
10.0

0
0
2

3
0

4
8
16
27

0
0
33.3
71. 4
0
71. 4
57. I
100
94. I
96.4
100
85. 7
100

2
0
I
0

5
0
5

3
6
5

Testicular weight 1l
imm. mat.
mat.%
9
11
8
7
7
7
7
6
7
4
4
1
0
0
0

0
0
0
0

0
0

5
6
12
22

0
0
12.5
22.2
12.5
45.5
46.2
75.0
84.6

32
6
11
8

97.0
100
100
100

2

I) Less than 16.5 g was considered to be immature (Miyazaki, 1975).

as mentioned before, this school is mostly composed of the immature males
affected by the special schooling behavior, and the data from this school may
not be suited for the present purpose. On the other hand, as the other 3 schools
show less specialized age distribution even if the frequency below 9 years israther low, they will give better estimation of the mean age at onset of sexual
maturity. The least squares regressions of the age-maturity relationship calculated for the data of these 3 schools are as follows.
Female: y=l2.60x-56.51

4.5~x~ 13.5Male

4.5~x~ 13.5

y= 12.05x-58.94

They give 8.5 years for female and 9.0 years for male as the age where 50%of the animals are sexually mature. Though the figure of the female is slightly
lower compared with the corresponding age of female 8.8 years (Kasuya 1972)
or 9.1 years (Miyazaki 1975), these difference may not be significant because aslight underestimation is expected from the scarecity of the immature animals
below 9 years of age in the 3 schools discussed here. The mean age of the maleat the attainment of sexual maturity estimated above shows good coincidencewith 9.2 years and 9.0 years estimated by Kasuya (1972) and Miyazaki (1975)
respectively.
Fig. 9 shows the relationship between age and the weight of a testis. The
weight shows a rapid increase at the age between 9 and 13 years in S. atteniiata
or between 7 and 11 years in S. coeruleoalba, which correspond to the age at
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

86

KASUYA

600 s attenuata
400
300

S. coeruleoalba

:

200

: .
.: .

..

..

. ...: .

100
Ol 80.......,
60--.:.t~iti~:·::,;.

-~

lll
Cl.I

._
~

. i .:. : ~· .
.,;.. .. :

40
30

:

0

Ol

·a;

S:

. '..

20

._

.c

.

' . ...

:

10

~·r

. .:....

. '. : ..

8
6

:

...
•I

.l~ i

l1;

:

4
3

·::

•

2 -·

I

5 9 13 17 21 25 29

5 9 13 17 21 25 29 33 37 41 45

Age in years
Fig. 9. Scatter diagrams of the relationship between age and the weight of testis.
Two age groups are combined. In S. coeruleoalba data from school no. 22 areincluded. Weight of right testis is plotted if the left is not available. Larger
circle indicates 5 animals and the smaller one.

onset of sexual maturity. However after the age of 15 years, the weights are
distributed between 120 g and 600 g (S. attenuata) or between 40 g and 150 g(S. coeruleoalba) and there is observed no increase related with the age of theanimal. This stage will correspond to the full sexual maturity and probably
to the stage of social maturity as suspected by Miyazaki (1975). This feature
is completely different from that observed in Physeter catodon where the weightof testis increases after the attainment of sexual maturity at or little above theprevious rate (Gambell 1972).

Accumuration rate of corpora in the ovaries
The persistency of the corpora for entire lifetime of the female wassuggested in S. attenuata by Kasuya et al. (1974). Possibly this is also true forS. coeruleoalba (Hirose et al. 1970, Miyazaki 1975).
In S. attenuata, though the individual variation is large, there is expected
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

87

a linear relationship between the number of corpora and the age (Fig. 10). The
following regression is obtained by the least squares for the animals older than
7 years of age,
y=0.412x-1.97
where y indicates the number of corpora, and x the age in years. This indicatesthe mean annual ovulation rate of 0.412, or 1.62 ovulations in one reproductive
cycle of 3.94 years (see page 88). Kasuya et al (1974) estimated, through theanalyses of corpora diameter, the annual ovulation rates of between 0.407 and0.595 for 5 age groups classified by the corpora number. And they concluded
from these estimates that the annual ovulation rate changes from 0.432 of young
animal to 0.487 of the animals with highest corpora number. Though they
considered that this indicates the change of the ovulation rate related with theage of the animal, it is theoretically incorrect because the number of corpora
in the ovaries is the function of both the age of the animal and of the individual
specific ovulation rate, and these two factors could not be separated in theirstudy. It should have been interpreted that the mean annual ovulation rate ofthe dolphins which may attain higher corpora number is higher than the mean
rate of the other dolphins. Furthermore, the diameter of the corpora is not amuch reliable indicator of the time elapsed after the ovulation, and the ovulation
rate estimated from its analysis is less accurate. Accordingly the ovulation
rate of S. attenuata estimated in this study will be the present best estimate.
As shown in Fig. 11, the relationship between the number of ovulations
and the age of S. coeruleoalba may not come on a single linear relation. If
the regression lines are calculated separatly for the age classes from 5 to 25
years and for those from 26 to 43 years. The following relations are obtainedby the least squares.
y=0.414x-2.40
5~x~25y=0.115x+6.55 26~x~43.
However, the first regression line seems to fit to the animals up to 33 years ofage. There are expected three reasons for this. The first is the simple sampling
error caused by the scarcity of the samples of higher age, the second is thedecline of the ovulation rate or the resorption of corpora at higher age, andthe third is the recent increase of ovulation rate might have happened as the
response of the population to heavy exploitation started since the last war.
The possibility of miscounting of the corpora will be neglected, because thecounting was made by myself with the same method for both species of Stendla.
The third possibility is also improbable because the ovulation rate of 0.115 perannum is too low even as the rate at initial population level, and because theovulation rate of S. attenuata possibly at the initial level (Kasuya et al 1974) isalmost identical with the first rate 0.414 per annum. Accordingly, the possible
explanations can be only the first or the second. And, though the first might
be more probable, the conclusion on this problem will have to wait until moredata are accumulated.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

KASUYA

88

ig 15
0

0

:i

~10

0

6

z

5

8 i:

0

20
25
30
Age in years

15

10

5

35

.40

.45

Fig. 10. S. attenuata, scatter diagram showing the relationship between age and numberof corpora in the ovaries (124 females). Thin straight line and thick straightline indicate mean corpora number and regression line obtained by least squares
respectively, for both only the data reoresented by closed circles are used.

20

C/l

c 15

.Q

0

:i
>

0

:

10

.

0

.

d

z

5

:
:

.

0
5

10

15

20
25
30
Age in years

35

.40

Fig. 11. S. coeruleoalba, scatter diagram showing the relationship between age andnumber of corpora in the ovaries ( 170 females). The data from school no. 22 are
not included. Larger circle indicates five animals and smaller one. For other marks
see Fig. 10.

Reproductive cycle
In this section the reproductive parameters of the adult females are analysed
in relation to the age of the animals. When the ratio of pregnant females inthe total adult females is shown by P, that of pregnant and simultaneously
lactating by PL, that of lactating by L, that of resting by R, and the mean
length of gestation by G years, the annual pregnancy rate and the mean calving
interval in years are estimated as follows.
Sci. Rep, Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

89
('/,)

tt

10

10.0
11.1
12.5

8

14.3
16.7

in 6
.....

Cl

20.0

QJ

>

25.0

4

33.3

1. \

''
\\
/'r:\
\.... _~~..~ _/ !

\

35

40

50.0
100

45

Age in years
Fig. 12. S. attenuata, relationship between age and the mean reproductive parameters
estimated from the ratio of reproductive stages. C: calving interval (left scale)and annual pregnancy rate calculated from it (right scale), L: length of lactation,
R: length of resting period, PL: length of the period lactating and simultaneously
pregnant. Each value is calculated combining the data of nearest 5 age classes.
The age classes indicated by arrow containe no pregnant female.

TABLE 5. DIFFERENCE OF REPRODUCTIVE PARAMETERS
OF ADULT FEMALES BETWEEN AGE CLASSES
S. attenuata

Species
Age class (year)

7-15

15-25

25-35

35-46

No. animals

31

64

22

13

130

Pregnancy (years)
PL (years)

0.83
0.10

0. 72
0.22

1. 46
0. 83
3.23
31. 0

2.04
0.55
3.53
21. 7

0.94
0
1. 40
o. 70
3.04
28.8

0. 79 (0. 82)
0. 14 (0. 12)

Lactation (years)
Resting (years)
Calving interval (years)
Annual pregnancy rate (%)

0.94
0
4.06
1. 87
6.87
14.6

0. 77 (0. 77)
3.69 (3. 94)
27. 1 (25.4)

Species
Age class (year)

5-15

15-25

S. coeruleoalba
25-35

35-49

Total

72
0.95

63
0. 73

No. animals
Pregnancy (years)
PL (years)
Lactation (years)
Resting (years)
Calving interval (years)
Annual pregnancy rate (%)

Total')

1. 99 (2. 23)

22

8

165

0.94

0. 75
0.25

0. 86
0.14

0.05

0.27

0.06

0.24
0.07

0.46
0.07

0.24
0.06

1. 31
76.4

1. 54
65. 1

(164)

0. 75

0.33

1. 29

0.25
2.00

0.08
1. 41

77. 3

50.0

70.9

I) In parenthesis includes age unknown animals cited from Kasu ya et al. 1974, Table 14.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

90

KASUYA

Annual pregnancy rate=(Calving interval)- 1 = P+cJL
Then mean length of each reproductive stage is estimated by the formulax

P+PL·G
where X indicates the ratio of females at one of the above 4 stages. This method
gives correct estimates only when the samples are not seasonally biased. As thepresent data, especially those of S. coeruleoalba, were collected in the limited
season, there might occur some bias of this kind. However, since the matingof both species of Stenella occurs in wide range of the seasons and there exist
probable three mating peaks in S. attenuata (Kasuya et al. 1974) and two(Kasuya 1972) or three (Miyazaki 197 5) peaks in S. coeriileoalba, such kind ofbias can be small enough compared with the bias caused by the inclination of
the dolphins to form separate schools by the sex, growth and reproductive stages
suggested by Kasuya (1972), Kasuya et al. (1974), and Miyazaki (1975).
The length of gestation of S. attenuata was estimated by Kasuya et al (1974)
to be 11.24 months or 0.94 years. If this gestation length is used for the above
calculation, the mean length of calving intervals is estimated to be 3.94 years,
mean length of lactation (L + PL) 2.35 years, and mean length of resting period
0. 77 years (Table 5). Though the data used here are same with those in Kasuya
et al (1974), as the treatment of the females pregnant and simultaneously lactating is different the figures are slightly changed. The analyses of the parameters in relation to the age of the female reveals that the mean calving interval
is shorter in the females below the age of 23 years and only in those age classes
the pregnant and simultaneously lactating females are observed. After this age
the length of calving interval increases, which at first step accompanies the increase of the length of lactation and then the increase of resting period. Thisphenomenon can be interpreted that, in the younger females, the lactation ceases
at about 2 years after the former parturition almost synchronizing with the startof the next conception, and in the older females as the start of the next conception delays the period of lactation is extended up to about 4 years in the
average when the calf stops suckling affected by the change of the behavior.
This age of the calf is the time when the calves are expected to leave the schoolof their mothers (Kasuya et al 1974). If, then, the next gestation does not start
for more than 4 years, there can occur the increase of resting females. The
extremely rapid increase of the mean calving interval after the age of 30 years
seems to suggest the presence of the females that ceases the ovulatory activity.
The decline of the length of calving interval or the increase of annual pregnancy
rate after the age of 37 years is the reverse of the former trend, but the similar
phenomenon is found also in S. coeruleoalba. One possible explanation for it
might be that the old females which ceases the ovulatory activity die, by theage between 35 and 40 years, earlier than the still active females which is fewer
in number, and even the latter females they often die at the last parturition
without followed by the lactation.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

91

25.0

•

28.6

33.3

•

40.0
0-------

50.0----- ---- -----

66.7------0--0__ _
-----

100
(°lo)

0'--~"---'--'--'--'---'-1.---'--'----'----'---'---'---'---'---'---'--'--'--'--'--L-'

'55

'60

'65

'70

'75

Vear
Fig. 13. S. coeruleoalba, annual fluctuation of the mean reproductive parameters estimated from the ratio of the reproductive stages. Closed circle and solid line indicate
the length of calving interval (left scale) and the annual pregnancy rate (rightscale), open circle and dotted line length of lactation (L+PL, left scale), andsquare and thin solid line length of resting period (left scale). For further explanation see text.
('/,)

33.3

3

40.0
50.0
66.7

100

5

10

30

35

40

Age in years
Fig. 14. S. coeruleoalba, relationship between age and the mean reproductive parameters.
For further explanation see Fig. 12.

For S. coeriileoalba, there is no reliable estimation of the gestation length,
however it was roughly suspected by Kasuya (1972) to be about 12 months.
In the present study this estimation is used without further confirmation. Kasuya
and Miyazaki (1976) indicated that the mean calving interval in the populationof S. coeruleoalba off the Pacific coast of Japan is decreasing accompaniedwith a decrease in the population level. If the data of 33 pregnant, 44 lactating,and 18 resting females obtained from the two schools caught in 1975 (see Table
1) are added to the data reported by Kasuya and Miyazaki (1976), the following
trend is estimated by the least squares (see also Fig. 13).
Calving interval= -0.040838x+82.944
Length of lactation= -0.044982x + 89.811
Resting period= 0.001951 x-3.485
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

92

KASUYA

where x indicates the calender year, and length of each stage is indicated by
year. The length of lactation includes both the period of lactation and thatof lactating and simultaneously pregnant. The above formula gives the estimation of the mean calving interval of 2.39 years in between 1972 and 1973
when the present materials were collected. This is slightly longer than thecalving interval estimated from the regression in Kasuya and Miyazaki (1976).
As shown in Fig. 13, the catch in these two seasons is strongly biased by thehigh ratio of pregnant females, and the mean calving interval estimated fromthe materials used in this study is only 1.41 years (see the short bar in Fig. 13),which is only 59.0.% of the unbiased estimate calculated from the above
regression. Accordingly only a general trend of the change of reproductive
parameters related with the age of the female can be discussed in this study,
and if necessary the above bias must be corrected.
In S. coeruleoalba, the period of shorter calving interval lasts about 10 years
longer than S. attenuata until about 32 years of age, and the period when thelactating and simultaneously pregnant females occur also last longer. After
this period, the pregnancy rate declines rapidly and then increases as observedin S. attenuata. Though the reason of the difference of the period of thehigh reproductive activity between the two species of Stenella is not conslusive, it seems to be possible to attribute it to the difference of the populationlevel because the Japanese coastal population of S. attenuata is close to theunexploited level (Kasuya et al. 1974) and that of S. coeruleoalba has been
exploited since before 1897 and the decline of the population is indicated (Kasuya and Miyazaki 1976).

Sex ratio
The sex ratio of S. attenuata was already analysed by Kasuya et al. (1974)
and the predominance of the male in fetal and juvenile stages was indicated.
Table 6 shows the sex ratio of fetus and of the juvenile animals not exceeding
142 cm in body length which corresponds to the age of one year on the mean
growth curve. As the sex ratio of the species at the time of birth will be between those of the above two growth stages, the ratio of females at the instanceof birth, 41.6.%, was obtained by combining the data of the two categories.
The ratio of females at the instance of birth in the population of S. coeruleoalba was estimated by Kasuya and Miyazaki (1976) to be 47.6.% based onlarge number of samples (Table 6). Though they included the animals corresponding, on the mean growth curve, to the age up to 1.25 years, it will notgive significant bias.
Fig. 15 shows the change of the sex ratio related with the age of the dolphins. The extraordinaly high ratio of the males at the age between 5 and11 years in S. attenuata or between 2 and 15 years in S. coeruleoalba is considered to be the result of the sexual segregation in the period between weaning
and the attainment of full sexual maturity. Possibly the ages when the young
dolphins move from the nursery school to the school of immature animals andSci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLATABLE 6.

SEX RA TIO OF THE DOLPHINS AT BIR TH

fetus

S. attenuata
juvenile 2 J

No. females

39
31

79
53

Female, %Male/Female

44.3
1. 26

41. 4
1. 49

SpeciesStage
No. males

93

S. coeruleoalba 1J

Total

fetus

juvenile 3l

Total

118

351
310

385
359

736
669

46.9
1. 13

48.3

47.6

1. 07

1. 10

84
41. 6
1. 40

1) Data cited from Kasuya and Miyazaki 1976.
2) Not exceeding 142 cm.
3) Not exceeding 172cm.

3.0 .,-----.---:0..-----r-----,-----.-----.----~-~
0

20

0

0
0

.2
.1'--"-'--'--'--'---'--'--'----'---'-.1........L-'--L-l...-'-.--'--'-'----'---'-.l........L-'---'-'-'--'--'--'--'---'--'--'

0

5

10

15

20

25

30

Age in years
Fig. 15. Relationship between sex ratio (male/female) and the age of S. attenuata(closed circle and solid line) and of S. coeruleoalba (open circle and dotted line).
The ratio for the age more than one year is calculated combining the data of thenearest 5 age classes. For other explanation see text.

then to the school of adult dolphins will be different between the sexes, andthis in combination with the kinds of schools studied by me will give sucha bias in the sex ratio. If these age classes are excluded there is observed adecline of the ratio with the progress of the age of the animals, which will
indicate the sexual difference of the mortality rate. When µ and µ' indicate
the annual natural mortality coefficient of male and female respectively, andRx the sex ratio (male/female) at the age of x years, there is expected thefollowing relationship.
The regression lines in Fig. 15 and the following figures are calculated by theleast squares based on the sex ratio at birth obtained above and the points in
Fig. 15 corresponding to the ages above 11 years (S. attenuata) or 15 years (S.
coeruleoalba). In case of S. coeruleoalba the mortality is affected by natural
mortality and fishing mortality. However, as the fishing mortality rate of theSci. Rep. Whales Res. Inst.,
No. 28, 1976.

94

KASUYA

species is not expected to be different between sexes, it can be neglected in thecalculation.
S. attenuata
S. coeruleoalba

µ-µ'

Ro

0.04120.0171

1. 32
1. 06

These figures indicate that the difference of the natural mortality coefficient
between the sexes is higher in S. attenuata, and that it is partially compensatedby the higher ratio of the male at birth.

Age composition and mortality
The age composition of S. attenuata obtained from 158 males and 200
females are shown in Figs. 16 and 17. The age composition suggests the presence of segregation related with the age and the sexual maturity of the animals
below the 13 years of age as already mentioned in the former sections. The
slope of the age frequency at the right side of this point indicates the natural
mortality, as the fishing mortality is negligible in this population. Though themortality seems to be slightly higher in the females above 31 years, the leastsquares calculated ignorering this minor change gives the following annual
mortality rate for S. attenuata.
Sex
FemaleMale

Coefficient
0.0779Rate in%
7.49

Age in years

0.1135

10. 7314~

14~

The difference of the annual mortality coefficient between sexes is 0.356 andcoincides well with the corresponding figure estimated from the sex ratio.
Since the above rates can be considered to represent the mean annual
mortality rate of the adult animals, the mean mortality of the immature stage
is estimated as follows. When the following abreviations are used
A : Number of mature females
lx : Number of females at the age of x years
C : Calving interval in years
L : Litter size
m: Mean age at the onset of sexual maturitys: Ratio of females at birthµ 1 : Mean annual mortality coefficient of immature femalesµ 2 : Mean annual mortality coefficient of mature females
there must be the next relations in an unexploited stationary population.

lo=

A·L·s
C

l_n = 10 e-µim
A= 1-n ~:e-µ2cx-mldx
As C=3.94, s=0.416, m=9.0, and µ 2 =0.0779 are obtained in this study, and theSci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

95

40
30
20

c 15 •

Ill

:.c0.
0

"'O

....0
d

z

10
8
6

.

.

''

4
3
2

6

9

13 17 21 25 29 33 37 41 45 49

Age in years
Fig. 16. S. attenu:ita, age composition of the 200 females based on cementa! layers.
4 indicate School no. 4, 6 school no. 6, S sum of the school nos. I, 2, 3, 5 and 7,
and the open circle and dotted line the total of the seven schools. Each two age
groups are combined.

40
30
20
Ill 15c::c0. 10
"O

8
6

0

4
3

0

....0
z

2

5

9

13 17 21 25 29 33 37 41 45 49

Age in years
Fig. 17. S. attenuata, age composition of the 158 males. Closed circle and thick solidline indicate the total of seven schools. For other explanation see Fig. 16.

litter size is 1.0 (Kasuya et al. 1974), the following estimate of the mean annual
natural mortality rate of immature female of S. attenuata is obtained from theabove formulae.
Sex
FemaleSci. Rep. Whales Res. Inst.,
No. 28, 1976.

Coefficient
0.0338Rate in%
3.32

Age in years;;;;9.0

96

KASUYAAs the difference of the mortality coefficient between the sexes is between 0.0412
and 0.0356 or approximately 0.038, the rough estimate of the mean annual
natural mortality of the immature male is as follows.
Sex
Male

Coefficient
0.072

Rate in%

6.9

Age in years;£9. 0The natural mortality rates of the immature dolphins estimated here are themean of the mortality of all the age classes from 0 year to the age at the attainment of sexual maturity, and the possible higher mortality expected for the
suckling calves is not separated. It was already indicated by Kasuya et al. (1974)
on S. attenuata that the mean natural mortality rate in the immature period
must be lower than that in the adult stage. The present study gives results
similar to those obtained in the previous study.
The age compositions of 341 females and of 488 males of S. coeruleoalba
are shown in Figs. 18 and 19. In these age data, the age of 62 females and
217 males of the school no. 22 was determined by counting the dentinal layers
by ordinary method. Because of the segregation of the immature individuals(Kasuya 1972, Miyazaki 1975) as in the case of S. attenuata, only the slope
above the age of 12 years in females or that above 14 years in males can indicate the mortality under certain assumption mentioned below. They are as
follows.
Sex
FemaleMale

Coefficient
0.09190.1143Rate in%

8. 78
10.80

Age in years
12 ;£
14;£

Above values can indicate the mean annual total mortality during theperiod from 1920's to 1959's only when the population is assumed to bestationary. However, as the exploitation of this population became higher
near the end of the last war as in the case of Phocoenoides (Kasuya 1976 a and b)
and the population has been decreasing (Kasuya and Miyazaki 1976), theestimation is not fully accurate. The total mortality rate in the postwar period
must be estimated separately. This can be made using the frequency of corpora
number, because the method can afford more abundant data. Fig. 20 shows
the age composition of sexually mature females calculated from the frequency
of corpora number cited from Kasuya and Miyazaki (1976) and the accumulation
rate of corpora (0.414/year) estimated in this study. There is observed two slopesin the age frequency. The first is from 15.9 (4 corpora) to 28.4 years (9 corpora)of age and the second slope is from 30.9 years (10 corpora) and above. If themortality is calculated separately, the following figures are obtained as theestimates of the total annual mortality rate of mature females.
Sex
FemaleFemaleFemaleCoefficient
0.12580.09510.0896Rate in%
11. 829.07

8.57

Age in years
15.9-28.4
30. 9-51. I
15.9-51.l

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENE,LLA..." .
' .

60

f,

40
30

,'

'

.

~

! \ :·~·"~·
20
&

C/l

c

22 ~11,'

'\

~-<t"

I•

d

:.c0. 15
0

-

R

,'1

I

\

10

" 86
0

d

z

4
3
2

5 9

13 17 21 25 29 33 37 41
Age in years

Fig. 18. S. coeruleoalba, age composition of the 341 females. Numerals indicate theschool number. The age composition of school no. 22 was based on the ordinary
method of reading of dentinal layers. For other marks see Fig. 16.

100

BO
60
40
30
C/l

c 20
.c 15
0.
0 10

-"
0

6

z

8

6
4
3
2

5

9

13 17 21 25 29 33 37 41 45 49
Age in years

Fig. 19. S. coeruleoalba, age composition of the 488 males.
For marks see Figs. 17 and 18.
S1i. Rep. Whales Res. Inst.,
No. 28, 1976.

97

98

KASUYA
100

80
60
40
30
VI

c

:c0.

0

"- 108
0

d

z

6

4
3
2

10

15

20

25

30

35

40

45

50

55

Age in years
Fig. 20. S. coeruleoalba, age composition of the 772 adult females based on the numberof corpora in the ovaries. Number indicate the sampling year, and closed circle andthick line the total. For further explanations see text.

The mortality rate calculated from all the age classes above 15.9 years coincides
well with the figure obtained above based on the cemental layers. This may
indicate the correctness of the above calculation. Furthermore, since the dateof birth of dolphins at the boundary of the two slopes, 28 to 30 years before
1972 when most of the samples were collected, approximately coincides withthe end of the last war in 1945, the annual mortality rate of 11.8% seems toindicate the rough estimation of the mean total mortality rate of the females
in the years near the end of the war to late 1950's. As the difference of theannual mortality coefficient between sexes is in between 0.0171 and 0.0224 orabout 0.020, the total mortality coefficient of the adult male in the corresponding years might be 0.126+0.020=0.146 or 13.6% per year. Though the meanmortality rate in the immature stage is expected to be lower than that of adultdolphins as in the case of S. attenuata, it is not possible to estimate it atpresent. The natural mortality rate is also unknown.
DISCUSSION

Age determination method
When the layers in dentine and cementum are compared, the higher number is almost always found in the latter in case of the dolphins older than 9(S. attenuata) or 11 (S. coeruleoalba) years of age. If, after these ages, thenumber of dentinal layers plotted against the number of cemental layers showed
an increase slower than that in younger stage, it would be possible to interpret
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

99

that the accumulation rate of cementa! layers increases after these ages and thatof dentinal layers stays constant. However, as the number of dentinal layersof older age groups is constant without showing any correlation with that of
cemental layers, it is concluded that the accumulation of the dentinal layers
stops at various ages between 9 or 11 years and about 25 years, or that thedentinal layers become too thin to be distinguished by the present method.
Recently same phenomenon was confirmed by Dr. P. B. Best (person. comm.)on Lagenorhynchiis obscurus through tetracyclin marking. He considers that"dentinal layers accumulate annually in young dolphins, but deposition ofdentine slows down in older animals and may cease altogether". As the toothat this stage is hardly distinguishable from that at preceeding stage throughthe observation of the pulp cavity, it seems to be safe to use the cemental
layers for the age determination of the dolphins with more than 9 (S. atteniiata)
or 11 (S. coeruleoalba) dentinal layers. However it must be noted for thepractical use of the cemental layer that the counting of the layers is moredifficult and unreliable than that of dentinal layers, and that it is necessary
to confirm the coincidence of the counts of the two kinds of layers on the
decalcified and stained preparation of the tooth of young dolphin.
Furthermore, it should be remembered that the suitable way of preparing
the tooth for age determination can be different between species of dolphins.
If the present method of preparation is applied on Phocoenoides or Lagenorhynchiis tooth, it gives good result for reading the cementa! layers. However,in cases of Globicephala macrorhynchus and Pontoporia blainvillei the decalcifi.cation and staining are not necessary if the tooth is ground thinly enough,and the thick and· irregular cemental layers in Platanista gangetica seems
difficult to use for age determination.

Life history parameters
From the above reasons, the life history parameters estimated previously
by reading dentinal layers and concerning the sexually mature dolphins are
now unreliable. They are the accumulation rate of the corpora, mortality rate,
and the age at the attainment of asymptotic length. In case of S. atteniiata,
the mean age at the onset of sexual maturity must also be corrected. However,as the accumulation rate of the corpora of this species was estimated from thecomparison of corpora diameter and the growth of suckling calves, and themortality rate from the corpora number and the accumulation rate (Kasuya
et al. 1974), they are not much affected by the present study (Table 7). It isalso confirmed that the ovulation rate and the calving interval estimated in thepresent study give the mean number of ovulations in one reproductive cycle
1.62 which is close to the estimation of 1.7 to 1.8 made by Kasuya et al. (1974).
Miyazaki (1675) estimated, for S. coeruleoalba, the annual ovulation rateof 0.59 based on the age-number of corpora relationship of the animals between
the age of 11 and 15 dentinal layers, and this result was used by Kasuya andMiyazaki (1976) for the estimation of the mortality rate and the population.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

100

KASUYATABLE 7.

COMPARISON OF LIFE HISTORY PARAMETERS OF THE TWO SPECIESOF STENELLA OFF THE PACIFIC COAST OF JAPANSpeciesS. attenuata
Present
study

S. coeruleoalba

Parameters

Previous
study 1 J

Previous
studies

Present
study

I. Gestation (months)

11. 2489142. 7142.5

1299. 81)
164.5

164.0

} 166.0

163.0
161. 5194.0
191. 0

193.0
189.0

191. 5
190.0

186.0
187.5

220.5
217.0

222.0
218.0

2. Length at birth (cm)
3. Length at 1 year of age (cm)4. Length at 3 years of age (cm)malefemale5. Length at 9 years of age (cm)malefemale6. Length at 50% maturity (cm)malefemale218. 33 )211. 5194.3
181. 97. Asymptotic length (em)234. 41)
223.5

236.0
225.3

22

12

12

JI

21
17

10.3
8.2

11. 8
9.0

9. 2 2)

8.8

9.0
(8.5)

24
24
4. 19
2.44
23.8
0.43-0.49

40
46
3.94
2.35
25.4
0.412

25 1)
26
2. 20 ('73) 3)
0. 89('73) 3)
45. 5 ('73) 3)
0. 590 4 )5049
2. 37 ('73)
I. 06('73)
42. 2 ('73)
0.414

12. 8 3)

I I. 8

203.3
194.9

207. I
193.9

male

12

femaleJI

malefemale8. Age at asymptotic length (years)

9. Age at 50% maturity
male
female10. Maximum age (years)
male
female11. Calving interval (years)
12. Length of lactation (years)
13. Annual pregnancy rate (%)
14. Annual ovulation rate
15. Annual mortality rate (%)
adult female

7. 4

7.5

immature female

3.2
14.8
11. 8
38.9

3.3

6.9
41. 6

8.3

9

16

2. 40 5 )0. 965,6)

adult male
immature male

16. Ratio of female at birth (%)
17. Maximum no. of calves produced
by one female
18. Mean no. of calves produced
by one female

JO. 7

13.6
47. 6 3)

1) Kasuya et al. 1974, 2) Kasuya 1972, 3) Kasuya and Miyazaki 1976, 4) Miyazaki 1975,
5) e- 9µ1J~ e-µ2-"dx/calving interval, 6) µ 2 =0.07, fishing mortality coefficient 0.0558, andcalving interval 2.90 years in 1960 are assumed.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

IOI

However, in view of the result of the present study, it seems to be improbalethat the age-number of corpora relationship can fit such a linear line asindicated by Miyazaki (1975, and see Kasuya and Miyazaki 1976). Actually,
any data possessed by myself or by Dr. Miyazaki, both of which were used in
Miyazaki (1975), failed to reproduce the graph cited in Kasuya and Miyazaki(1976). Possibly many individuals younger than 16 dentinal layers and withhigh corpora count might have been arbitrarily excluded from his calculation.
Accordingly, the accumulation rate of corpora estimated in this study, 0.414 perannum, is considered to be more reasonable.
However, as this ovulation rate is estimated from the gradient of
age-number of corpora relationship, it gives only the ovulation rate in theyear when the dolphin attained the sexual maturity. Even if the ovulation
rate is changing in recent years, it will not be detected by this method until
the recently matured females attain a certain age and the change of the gradientis detected. As the ovulation rate of S. coeruleoalba estimated in this study
is not different from that of S. attenuata at initial population level, and isclose even with 0.38 to 0.45 the rate of the P. catodon estimated by dentinal
layers (Bannister 1969 cited in Gambell 1972, Best 1970, Gambell 1972), 0.5 of
H. ampullatus (Christensen 1973), and 0.39 to 0.51 of G. melaena estimated byindirect method (Sergeant 1962), it is suspected that the annual ovulation rateof toothed whales at their initial population level will not be much different
between the species, and that the annual ovulation rate of two kinds of Stenella
estimated in this study must be that at initial population level.
The population of S. coeruleoalba off the Pacific coast of Japan has been
depleted in recent years to about half of the initial level, and the mean calving
interval is changing shorter (Kasuya and Miyazaki 1976, and see Table 8 andFig. 14 of this study). If the mean calving interval of this population in
between 1972 and 1973 is 2.39 years as calculated from the regression line (seepage 89) and the mean annual ovulation rate is 0.414, the mean number ofovulations in one reproductive cycle is only 0.989. This is not significantly
different from one ovulation per cycle, or the rate only theoretically possible
when all the ovulations are followed by the conception and seems to be actually
impossible. This problem can be explained by one or two of the following
assumptions.
I. Annual ovulation rate has started to increase in recent years, when thecalving interval is so shortened that the further shortening can not be
achieved by the improvement of the ratio of successfull ovulation.
2. Length of calving interval is underestimated.
Though it is sure that the estimation of the mean calving interval is liable toalteration when better estimation of gestation length is obtained or when thedata of the ratio of females at various reproductive stages covering wider seasons
are obtained, the bias of the present estimation was expected not to be large(page 88). And I suspect that the first assumption is more probable.
It has been generally supposed that when the population is depleted by
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

102

KASUYAthe exploitation, the pregnancy rate or the calving interval of the cetaceans
will change in order to result in the increase of recruitment (Laws 1961). Thisphenomenon seems to have been detected with insufficient accuracy in the
population of S. coeruleoalba off the Pacific coast of Japan (Kasuya andMiyazaki 1976). The difference of pregnancy rate between S. coeruleoalba andS. attenuata indicated in the present study can be the reflection of different
strength of exploitation. If the relationships between pregnancy rate and ageof the animals of the two species of Stenella are compared (Figs. 12 and 14) inview of the above hypothesis, there are expected several factors influencing thechange of mean pregnancy rate in a population. The first and the most direct
is the shortening of calving interval in all the age classes. This is expectedfrom the fact that the mean calving interval of the unexploited S. atteniiata
is about 3.4 years in the age classes of high reproductive activity, and thecorresponding figures of exploited S. coeriileoalba is about 1.4/0.590=2.4 years
when the bias of the data is corrected (see page 90). The second factor is theextension of the period of high reproductive activity from up to 22 years of age
as observed in S. attenuata to up to 32 years of age in S. coeruleoalba. These
two factors will result in the decrease of the mean length of lactation, which
is suggested from the facts that the shortening of mean calving interval of S.
coeruleoalba in recent years is achieved by the shortening of the period of
lactation (Kasuya and Miyazaki 1976, page 89 of this study) and that the lengthof lactation in the ages of high reproductive activity is generally shorter thanthat in older age classes (page 88). The third and the most indirect factor willbe the increase of the ratio of young and reproductively active females, whichis the result of the high recruitment rate brought by the former two factors
and of higher fishing mortality rate. Though the attainment of sexual maturity
at younger age is expected when the population decreases as already observedin fin whale (Lockyer 1972), it ts not clear if the difference of the mean age
at the onset of sexual maturity between the two species of Stenella observedin this study is due to it. It seems to be probable in the delphinids that thelength of nursing period is more variable than the age at the onset of sexual
maturity. So, when the population is depleted by the exploitation, the shortening of the calving interval directly related with that of nursing period as indicated in this study will occur before the change in the age at the attainmentof sexual maturity does.
Kasuya et al. (1974) estimated from the analysis of the size distribution of
the corpora in the ovaries that the maximum number of calves produced by
one female is 8.3 in S. attenuata. It was shown in the present study that theage of the oldest female of the species is about 46 years, mean calving interval
3.94 years and the mean age at the start of the sexual maturity 9 years. Thesefigures give the estimation of the maximum number of calves that can be produced by a female, or (46-9)/3.94=9 calves. This figure coincides extremely
well with the estimate made by Kasuya et al. (1974) through the analysis ofcorpora. If the similar calculation is made for S. coeruleoalba in the early l 970's,
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

103

it gives approximate figure (49-9)/2.4=16 calves. The extremely higher numberof production of calves in the latter species must be the sum of the above
mentioned reaction of the population to the exploitation.

Estirnation of the population of S. coeruleoalba
In view of the present study indicating the minor change of the parameters, the population analysis made by Kasuya and Miyazaki (1976) shall bereconsidered based on the improved parameters concerning total mortality rateof post-war period, annual change of mean calving interval, and calving interval
at initial population level taken from that of S. attenuata. Furthermore, thecatch statistics at Taiji in 1973 and the total catch of the same year shall becorrected to 1,000 and 8,200 dolphins respectively instead of 7,500 and 14,700
used by Kasuya and Miyazaki (1976), and the total catch of the species in
1974, 13,000 animals, was added.
If the analyses of the population is made by the same principle as used by
Kasuya and Miyazaki (1976), the relationship between net annual recruitment
rate (R in %) and the population (P in thousands) estimated for each year
between 1960 and 1975 based on the recruitment and catch is shown by thefollowing least squares regressions.
R= -0.01190P+4.437,
R= -0.01598P+6.462,
TABLE 8.

when µ 2 =0.07
when µ 2 =0.08.

COMPARISON OF POPULATION ANALYSIS OF S. COERULEOALBABETWEEN PREVIOUS AND PRESENT ESTIMATES
Kasuya and Miyazaki 1l

0.07
0.05354
Mean annual catch around 1960
14,000Total mortality coefficient
0. 1365
Fishing mortality coefficient
0.0665
Fishing mortality rate
0.0643Population around 1960
218,000
Population at 1974
129,000
R 4l at 1974 level
3.09%
SY 5 l at 1974 level
3,980
Initial population;?::321,000
Population, MSY 6l level
161,000
R at Msysi level
2.57%
MSY
4, 130Assumption, µ 2
Presumed µ 1 3J

2l

0.08
0.03870
14,0000. 1365
0. 05650.0549255,000
186,000
3. 21;';]'
5, 960;?::340,0'.JO
170,000
3.53%
6,010

Present estimation

0.07
0.0606
14,0000. 1258
0.05580.0543258, OOO
176,000
2.34%
4, 120;?::373,000
186,000
2.22%
4, 1400.08
0.045814,0000. 1258
0.04580.0448313,000
252,000
2.44%
6, 140;?::404,000
202,000
3.23%
6,530

1) Kasuya and Miyazaki 1976, 2) Annual natural mortality coefficient of adult female,3) Mean annual natural mortality coefficient of immature female calculated from µ 2 , sex
ratio 0.476, and calving interval of S. attenuata at initial level, 4) Net annual recruitment
rate, estimated from the relationship between P and R in the above, 5) Sustainable yield,
6) Maximum sustainable yield.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

104

KASUYA

These equations give reproductive rate slightly lower than that in Kasuya andMiyazaki (1976). The minimum initial population is estimated as the valueof P corresponding to R=O. Other revised population parameters based on
the above equations are shown in Table 8. Though, the population is suspected
to be continuously decreasing since 1970 at an mean rate of 2, 700 (µ 1 =0.08) or
4,800 (µ 2 =0.07) dolphins per year, it is unnecessary to alter their conclusion
saying that the present status of the population is "close to the level producing
the maximum sustainable yield of 4,000 to 6,000 dolphins per annum". This is
the result of the interference of the higher population estimate lead from thelower fishing mortality rate in the post-war period and the lower recruitment
rate calculated from the new estimate of mean calving interval. However it isalso important to note that the population parameters lead from the assumptionof the natural mortality coefficient µ 2 =0.07 might be closer to the truth. The
reason is that, if we consider that the length of lifetime of S. coeruleoalba isprobably longer than that of S. attenuata by about 10% (see Table 7), thenatural mortality coefficient of adult female of the former species is suspected
to be about 10% lower than that of the latter species µ 2 =0.0779.
The annual net recruitment rate at the instance of extinction is extraporated
from the above equations as 0.04437 (when the natural mortality coefficient of
adult female µ 2 =0.07) or 0.06462 (µ 2 =0.08). The mean calving interval giving
these recruitment rates, under the assumption that other parameters stays
unchanged, are calculated with the following equations modified from those inpage 92 of this study (Kasuya and Miyazaki 1976),

10 =A·L·s/C
A= 10e-Cµi+f)m/(µ 2+f)
R=l-e-f
where f indicates sustainable fishing mortality coefficient. They are 1.59 (whenµ 2 =0.07) or 1.18 (µ 2 =0.08) years. If the ratio of females which start the next
conception increase linearly after the preceding parturition and the length ofgestation of this species is about 12 months (Kasuya 1972), all the females must
start the conception within 1.2 or 0.36 years respectively after the last parturition.
Though they are not impossible, the latter seems to be difficult to be accomplished if the mating peaks of two (Kasuya 1972) or three (Miyazaki 1975)
times in a year are retained unchanged. However, it is possible to expect at
the lower population level, the non linear change of recruitment rate affectedby the change of other reproductive parameters (age at the attainment of sexual
maturity, sex ratio, or mortality rate of weaning calves) which are not detected
at present.
ACKNOWLEDG MENTS

I am greatly indebted to Mr. S. Matsui of the Taiji Whale Museum and to
Dr. N. Miyazaki of the Ocean Research Institute, University of Tokyo, for
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIFE HISTORY PARAMETERS OF STENELLA

105

collecting the data and samples. Dr. R. L. Brownell of the Smithsonian
Institution kindly read the manuscript and criticized. The preparation of
tooth sections and the analysis of the data were made with the assistance ofMiss S. Wada and Miss M. Oya of the Ocean Research Institute. These persons
are deeply acknowledged.

REFERENCES
BEST, P.B., 1970. The sperm whale (Physter catodon) off the west coast of South Africa. 5. Age,
growth and mortality. Invest!. Rep. Div. Sea Fish. S. Africa, 79: 1-27.
CHRISTENSEN, I., 1973. Age determination, age distribution and growth of bottlenose whale,
Hyperoodon ampullatus (Forster) in the Labrador Sea. Norwegian]. Zoo!., 21 (4): 33-340.
GAMBELL, R., 1972. Sperm whales off Durban. Discovery Rep., 35: 199-358.
HIROSE, K., T. KASUYA, T. KAZIHARA and M. NISI-IIWAKI, 1970. Biological study of the corpus luteum and the corpus albicans of blue white dolphin (Stenella caeruleoalba). ]. 1\famm.
Soc. Japan, 5(1): 33-39.
KASUYA, T., 1972. Growth and reproduction of Stenella caeruleoalba based on the age determination by means of dentinal growth layers. Sci. Rep. Whales Res. Inst., 24: 57-79.
KASUY A, T., 1976a. The stock of striped dolphin, part 1 and 2. Geiken Tsushin, 295: 19-23,
296: 29-35. (In Japanese)
KASUYA, T., 1976b. Preliminary report of the biology, catch and populations of Phocoenoides in
the western North Pacific. ACMRR/MM/SC 21, 20p.
KASUYA, T. and N. MIYAZAKI, 1976. The stock of Stene/la coeruleoalba off the Pacific coast ofJapan. ACMRR/MM/SC 25, 37p.
KASUYA, T., N. MIYAZAKI and W.H. DAWBIN, 1974. Growth and reproduction of Stenella
attenuata in the Pacific coast of Japan. Sci. Rep. Whales Res. Inst., 26: 157-226.
LA ws, R.M., 1961. Reproduction, growth and age of southern fin whale. Discovery Rep., 31:
327-486.
LOCKYER, C., 1972. The age at sexual maturity of the southern fin whale (Balaenoptera physalus)using annual layer counts in the year plug. ]. Cons. Inst. Explor. Mer., 34(2): 276-294.
MITCHELL, E. and V.M. KOZICKI, 1975. Autum stranding of a northern bottlenose whale(Hyperoodon ampullatus) in the Bay of Fundy, Nova Scotia. ]. Fish. Res. Board Canada, 32:
1019-1040.
MIYAZAKI, N., 1975. School structure of Stenella coeruleoalba. Doctoral thesis, Faculty of Agriculture
Univ. Tokyo (Manuscript, in Japanese).
OHSCMI, S., T. KASUYA and M. NISHIWAKI, 1963. Accumulation rate of dentinal growth layers
in the maxillary tooth of the sperm whale. Sci. Rep. Whales Res. Inst., 17: 15-35.
OHSUMI, S., 1965. Reproduction of the sperm whale in the North-West Pacific. Sci. Rep. Whales
Res. Inst., 20: 1-16.
SERGEANT, D.E., 1959. Age determination of odontocete whales from dentinal growth layers.
Norw. Whaling Ga;;.., 48(6) : 273-288.
SERGEANT, D.E., 1962. The biology of the pilot or pothead whale, Globicephala melaena (Traill)in Newfoundland waters. Bull. Fish. Res.· Bd. Canada., 132: 1-84 .
.SERGEANT, D.E., D.K. CALDWELL and M.C. CALDWELL, 1973. Age, growth, and maturity ofbottlenosed dolphin (Turiops truncatus) from Northeast Florida. ]. Fish. Res. Board Canada,
30: 1009-1011.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

106

KASUYA

EXPLANATION OF PLATESPLATE I
Fig. I. Decalcified and stained tooth section of S. attenuata, 167 cm male (school 5,
no. 54), pulp cavity at the right. White spots indicate 3 stainable cementa! layers,
and numerals stainable postnatal dentinal layers. Scale indicates 0.1 mm.
Fig. 2. Another part of the same tooth section in Fig. I, cusp at the left and pulp
cavity at the bottom. 0 indicates prenatal dentine. For other marks see Fig. I.
Fig. 3. Cementa! part of a decalcified and stained tooth section of S. attenuata, 19.5
cm female (school 3, no. 35), dentine at the right. 46 cementa! layers are counted.
Scale indicates 0.1 mm.
PLATE II
Fig. I. Decalcified and stained tooth section of S. coeruleoalba, 232 cm male (school
44, no. 337), cusp at the lower left and pulp cavity at the lower right. 28 dentinal
layers are counted. Scale indicates 0.1 mm.
Fig. 2. Cementa! part of the same tooth section in Fig. 1, dentine at the bottom.
28 cementa! layers are counted. Scale indicates 0.1 mm.
Fig. 3. Cementa! part of a decalcified and stained tooth section of S. coeruleoalba,
227 cm male (school 44, no. 166), dentine at the right. 40 cementa! layers arecounted. Scale indicates 0.1 mm.
PLATE III
Fig. I. Cementa! part of a decalcified and stained tooth section of S. coeruleoalba,
241 cm male (school 44, no. 295), dentine at the lower left. 49 cementa! layers arecounted. Scale indicates 0.1 mm.
Fig. 2. Comparison of a tooth section before and after the decalcification and staining. S. coeruleoalba, 161 cm male (school 38, no. 161), pulp cavity at the right.
Scale indicates 0.1 mm. Top: After decalcification and staining. Bars indicate
stainable dentinal layers. Bottom: Before decalcification. Bars indicate opaquedentinal layers.
PLATE IV
Decalcified and stained tooth of S. attenuata, 183 cm male (school 7, no. 27). 10 stainable layers are counted in both cementum and dentine. Numerals indicate prenatal
dentin (0) and postnatal dentinal layers (1-10). Pulp cavity at the lower right.
Scale indicate 0.1 mm.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

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NOTES ON THE FOETAL SKULL OF]}fESOPLODON STE]NEGERJ*CHARLES McCANN
8 Kiwi Street, Heretaunga, Upper Hutt, New Zealand

ABSTRACTThe cranial anatomy in the skull of a foetal Mesoplodon stejnegeri
True is described and illustrated. Some of the more important changes
which take place in the structures in the course of their developmentfrom the foetal to the adult state are discussed.
INTRODUCTION

The Ziphioid skull is, perhaps, the most asymmetrically distorted of all mammalian crania. In the adult some of the elements are partially or completely
overlaid, fused or so closely interdigitated that they defy separation and theirrelationship to one another is often most puzzling. In the advanced foetal
stage the bones fall apart readily, on maceration, and allow of a greater
understanding of the complex arrangement of the cranial components. However, it is seldom that a specimen, young enough, is available to study the
intricate anatomy of such a skull.
On the 28th September, 1937, the late Dr. W.R.B. Oliver collected a specimen of 1VIesoplodon stejnegeri True which stranded on the Waiterere Beach,near the Manawatu Heads (Dom. Mus. 619). The specimen, a female, contained
a full term foetus (Dom. Mus. 620, skeleton). The skeletons of both are preserved in the Dominion Museum, W ellin~ton.
In the flesh, the adult measured 4,200 mm (14 ft) in total length and the
foetus 1,550 mm (5ft 2 in). Mesoplodon stejnegeri is, perhaps, the smallest species
in the genus. As the neonatals of Mesoplodon are approximately one third
the length of the parent at birth, there seems little doubt that the adultpresumably came inshore to calve, when she met her death. Three species ot
Mesoplodon, JVI. grayi, M. layardi and M. stejnegeri, are known to calve in
New Zealand waters during the spring of the Southern Hemisphere.
Unfortunately, portions of the skull of the foetus have been lost or disintegrated during maceration; nevertheless, there is sufficient material available
worthy of description and comment. As most of the cranial elements havefallen apart along their sutures, description of the various components andtheir relationship to each other is made comparatively simple. I draw attention to the main features of the skull below.
* This paper was compiled during my service with the National Museum, Wellington.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 107-117.

108

McCANN

ANATOMICAL OBSERVATIONSAt this early age the axial base of the cranium (basis crani) is composed ofthree separate masses: anteriorly, the vomer-presphenoid mass; mesially, thebasisphenoid mass; and, posteriorly, the basioccipital mass.

Vomer-presphenoid mass. (Pls. 3, fig. I ; Pl. 4, fig. 1)
Viewed dorsally, the rostral portion of the vomer (V) is a lanceolate channel or trough, deepest proximally (Pl. 3, figs. 1, 4). At the point of fusion
with the presphenoid (PS), a portion of the vomer is obscured by the superimposition of the presphenoid (PS) and the ethmoid, but the vomer reappears
posteriorly as a thin, horizontal, retuse, somewhat ligulate bone, the laterallobes of which are slightly depressed on either side of the mid-line (Pl. 3, fig.
4). Viewed laterally, the vomer is somewhat canoe-shaped with a short 'dropkeel' (K) near the middle of its length. Ventrally, the vomer is strongly keeled
except for the posterior, horizontal expansion. At the point of fusion between
the internal, lateral walls of the vomer, and the presphenoid, there is an articular surface for union with the pterygoid bone. On the interior wall of thepresphenoid are clearly seen the lines of fusion between it (presphenoid) andthe ethmoid. The ethmoid fuses also with the adjacent walls of the vomer,
but at this early age the base of the ethmoid is not in contact with the vomer
below; at a later stage of development the union is completed.
The presphenoid rises in a steep curve from its almost horizontal floor toform the fore part of the cranial cavity. It lies across the axial base of thevomer, but it is free from the vomerine channel at this period of development.
No foramina are apparent on the walls of the presphenoid, but a shallow
sulcus is formed on the lateral edges which eventually contribute to the formation of the optic f oramen and the fora men lacerum. The suture between
the presphenoid and the basisphenoid is filled with cartilage. In the adult,
although the suture narrows, the two bones never seem to fuse; there is always
a gap between them.
Proximally, the ethmoid is composed of rather spongy bone fusing withthe presphenoid and the vomer; anteriorly, it continues in the trough of thevomer (mesorostral groove) as the masorostral cartilage. With advancing age
this cartilage ossifies and fuses with the adjacent bones and, in adult males
completely fills the groove with dense, ivory-like bone; but in females theossification is net so marked, the groove is only partially filled with bone ofa more spongy nature (Pl. I, OC). Some authorities hold that the filling of
the mesorostral groove is effected by proliferation of the vomer itself (Forbes,
1893)*, but this view does not appear to be borne out by careful examinationof transverse sections of the rostrum.
*Forbes, H.O., 1893.

Proc. Looi. Soc. Lond. pp. 216-236, pls. 12-15.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

FOETAL SKULL OF MESOPLODON STE]NEGERI109

Basisphenoid mass. (Pl. 3, figs. 2, 12 ; Pl. 4, fig. 2)
Viewed dorsally, the basisphenoid (BS) is somewhat butterfly-shaped(Pl. 3, figs. 2, 12), with great 'pedunclate' wings (alisphenoid) outspread obliquely
forwards, the anterior margins of which articulate with the pterygoids. About
the middle of the body of the basisphenoid is a shallow depression (pituatary
fossa); on either side of this fossa is a large foramen (foramen ovale) (FO).
The foramina pass obliquely backwards to the exterior.
As already observed, the anterior articulation is imperfect mesially, but theantero-lateral edges articulate with the presphenoid. The posterior articularsurface of the basisphenoid is not markedly separated from the basioccipital. In
the adult this suture fuses completely, and this union between the basisphenoid
and the basioccipital becomes almost invisible. Ventrally, the basisphenoid isshallowly grooved, longitudinally (Pl. 3, fig. 12). Posteriorly, on either side of
the median groove, are the elevated articular surfaces which articulate with thebasioccipital crests or wings.
Basioccipital mass. (Pl. 3, fig. 3; Pl. 4, fig. 3)
Viewed dorsally, the surface of the basioccipital (BO) is somewhat
triangular; the articular surface of the basioccipital with the basisphenoid
is marked by four scallops (Pl. 3, fig. 3; Pl. 4, fig. 3); mesially there is ashallow fossa on either side of which there are articular surfaces for theadjacent bones. Posteriorly, a rounded projection forms the lower margin ofthe· fora1nen magnum between the bases of the occipital condyles. Laterally,
the basioccipital crests fall away obliquely with forwardly directed projections
articulating beneath the basisphenoid. Postero-laterally, the basioccipital crests
articulate with the exoccipitals.
With advancing age, the basisphenoid is 'crushed' between the presphenoid
and the basioccipital, and, eventually, it (basisphenoid) fuses completely withthe latter bone. The alisphenoids appear as irregularly shaped bones on theexterior of the skull, adjacent to the squamosal. The posterior horizontal
portion of the vomer overlies the greater part of the basisphenoid and a portionof the basioccipital subsequently fusing with them.
Maxilla. (Pl 3, figs. 5, 6; Pl. 4, fig. 14)
Adpressed to the lateral portion of the vomer is the lanceolate projectionof the maxilla (MX) ; posteriorly, the maxilla flattens out almost horizontally
to form a broad supra-orbital expansion as in the adult (Pl. 3, fig. 6). Itsposterior margin bends round towards the mid-line of the skull and contributes
to the formation of the vertex and the lambdoidal ridge. In the foetus, abasirostral groove (DN) is present, extending from below the maxillary tubercle
to the anterior extremity, just below the dorsal profile of the maxilla. This
groove is believed to be homologous with the dentary groove of othermammals. This canal apparently houses the dentary branch of the superior
maxillary nerve. In the adult of Mesoplodon stejnegeri the basirostral groove
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

110

McCANN(BG) is absent, being completely filled with secondary bone. In. some species
this grove is present throughout life (M. grayi) and forms a useful accessory
character in diagnosis of the species.
The dorsal profile of the rostral portion of the maxilla slopes gently
upwards towards the nares (NR) ; the lower is almost straight, rising abruptly(at an angle of about 45 degrees) at a vertical dropped at the maxillary
tubercle (MT). The cranial portion of the maxilla is expanded laterally, as
already indicated above, but does not margin the orbit. The inner face ofthe maxilla is sculptured to articulate with the premaxilla and the vomer.
The outer face is sculptured posteriorly to articulate with the palatine bone(PL), (Pl. 3, figs. 5, 6). From above, on the inner side of the maxillary
tubercle, the large maxillary foramen (MXF) is visible. Another large foramen(sometimes additional secondary foramina are present), the post-maxillary
foramen (PMXF), is to be seen near the middle of the flattened expansion or'maxillary plate'. The expanded portion of the maxilla over-rides the malarbone (jugal}, the lachrymal bone and the frontal bone (F), except for its(frontal) lateral margin which forms the orbit.

Premaxilla. (Pl. 4, figs. 13)
The premaxilla (PMX) is a much elongated, compressed and twisted bone,anteriorly wedged between the vomer and the maxilla and posteriorly margining the anterior nares (NR) and forming part of the vertex. Its posterior
extremity forms part of the 'hood' over the anterior nares (the hood is mostpronounced in M. stejnegeri).
Dorsally, the premaxilla is perforated by the premaxillary foramen (PMF).
In the foetus the premaxillary foramina are approximately on· the sametransverse level as the maxillary foramina, but with the elongation of therostral bones, the premaxillary foramina mores a short distance behind themaxillary foramina as in the adult. A canal, carrying a branch of thetrigeminal nerve and the associated blood vessels, enters the matrix of thepremaxilla and travels to its anterior extremity. This canal is connected withthe premaxillary foramen. The dorsal margin of the premaxilla, together withthe wall of the vomer, encloses the mesorostal cartilage, but the premaxilla
exceeds the vomer in length, and, anteriorly, the premaxillae alone constitutethe groove. In the adult the bone of the premaxilla is much denser than thatof the maxilla.
Palatine bone (PL). (Pl. 3, figs. 5, 6; Pl. 4, fig. 15)
The palatine bone is sandwiched between the maxilla and the pterygoid
and when the latter bone is in place the major portion of the palatine isobstrucured, with only a narrow margin of its anterior extremity anddorsal edge margining the pterygoid above. Anteriorly, the palatine bone issomewhat arrow-headed in shape (Pl. 3, fig. 5, 6 (PL)). Postero-dorsally, two
short articular surfaces project, the upper in contact with the maxilla, frontal
Sci. Rep. Whales Res, Inst.,
No. 28, 1976.

FOETAL SKULL OF MESOPLODON STEJNEGERI

111

and the lachrymal bones; the lower, with the lachrymal alone. Posteroventrally, the palatine bends round the angle of the maxilla forming a small
lobe compressed between the maxilla and the vomer. The external face of thepalatine articulates with the pterygoid and eventually fuses with it completely.
A portion of the palatine enters the anterior nares.

Pterygoid bone (PY). (Pl. 3, figs. 1, 8; Pl. 4, fig. 16)
The pterygoid bone is somewhat triangular in general shape. Posterodorsally the pterygoid articulates with the vomer and the base of thepresphenoid and, in time, fuses with them; its internal lateral face abuts theexterior of the palatine bone and eventually fuses with it. Externally, thepterygoid is concaved and forms what is known as the mesial lamina (PML);
its lower margin turns outwards and posteriorly forms the pterygoid hamulus(H). Together the paired pterygoids form the posterior nares which contains
the laryngeal mass. The pterygoids approximate each other along the axial
line but, normally, do not fuse with each other, even in the adult.
Lachrymal bone (L). (Pl. 3, figs. 11 a, 11 b ; Pl. 4, fig. 12)
The lachrymal bone is roughly oblong in shape. Viewed ventrally, theanterior half is flat, but the posterior half presents a strong keel. Dorsally, it
is in contact with the maxilla and the anterior portion of the frontal, forming
the orbital margin. Posteriorly, it is also in contact with the palatine andwith the pterygoid. Anteriorly it is in contact with the malar bone. (Pl. 3,
figs. lla, llb)
Malar bone (Jugal).
The malar bone is missing in the specimen under discussion. In the adult,
the malar is a flattish, triangular bone giving off, posteriorly, the slenderzygomatic process; it is in contact with the maxilla internally and with thelachrymal externally. Anteriorly, it borders the antorbital notch.
Together with the lachrymal, and the anterior extrenity of the frontal
forming the orbit, the malar contributes to the formation of the antorbital
tubercle.
Frontal bone (F). (Pl. 4, figs. 9, 11 ).
Dorsally, the frontal bone (F) is almost completely overlaid by the
expansion of the maxilla, but, laterally, it borders the maxilla and contributes
to the foramation of the orbital-the lateral border of the frontal forms thesuperior border of the orbit. Anteriorly, its extremity interlocks between the
maxilla and the lachrymal; posteriorly, the orbital ridge terminates in a free
process above the squamosal. Posteriorly, the edge of the frontal can befollowed, wedged between the maxilla and the supraoccipital, and thence
twisting round into the vertex of which it forms part, under the maxillary'plate'. Its posterior wall forms part of the brain case.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

112

McCANN

Nasal bone (N). (Pl. 4, fig. 10)
The nasal bone (N) are paired. Each bone is somewhat cuboidal in shape(Pl. 4, fig. 10) in the foetus; they are 'free'-they drop out of position onmaceration. In the adult the nasals lose some of their shape and become
welded to the adjacent bones posterially and laterally; anteriorly they are
free, and contribute to the formation of the anterior nares. In the foetus thetwo nasals are in contact with each other mesially, but not fused; laterally
the bones are adpressed to the internal faces of the premaxillae; ventrally
they are in contact with the mesethmoid.
Narial passage (NR).
The narial passage is divided into two by a septum formed largely by
the vomer and the ethmoid. The recurved walls of the vomer, together witha portion of the pterygoids, compose its posterior wall; the lateral walls areformed largely by the pterygoids and small segments of the maxillae andpalatines; and, the anterior wall, partly by portions of the premaxillae, maxillae
and pterygoids. The superior wall of the posterior passage is formed largelyby the horizontal, posterior expansion of the vomer and a small segment of
the frontals. The inferior walls are formed by the pterygoids.
A large foramen perforates each of the lateral walls of the anterior nares,
carrying a branch of the trigeminal nerve and the associated blood vessels.
Interparietal (IP). (Pl. 3, figs. 9a, 8b, 9e, 10; Pl. 4, fig. 4)
The interparietal is a dense obovoid bone with a ventral keel which fuseswith the falx cerebri. Anteriorly, it is in contact with the frontals; laterally
and posteriorly it fuses with the adjacent bones and with age loses its identity
as a separate element. In the foetal specimen its sutures are still visible onits ventral aspect.
Parietals.
The parietals are damaged beyond recognition m the specimen.
Siipra-occipital SO. (Pl. 4, fig. 4)
The suppraoccipital at this early stage is very fragile. It is domed, witha median depression exteriorly; interiorly a deep flange forms part of thefalx cerebri. At the posterior end of the falx cerebri is the internal occipital
protuberance.
Exoccipital (EO). (Pl. 4, fig. 5)
The exoceipital is somewhat squarish. The superior margin fuses withthe supraoccipital eventually; ventrally it articulates with the posterior marginof the basioccipital crest and, eventually, fuses with it; its lateral margin
articulates with the squamosal and fuses with it; at its inner angle is theoccipital condyle. Between the lateral margin and the condyle there is a deep
notch along its ventral border ; within this notch there is the exist leading
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

FOETAL SKULL OF MESOPLODON STEJNEGERI

113

outward from the internal condylar foramen. The fusion of the exoccipitalwith the basioccipital is so complete in the adult that it appears as though
the exit foramen was situated between the two bones.

Squaniosal bone (SQ).
The squamosal bones (SQ) have been lost in the foetal specimen.
portion of one is preserved but is insufficient for description.

A

Mastoicl process.
A mastoid process arises from the posterior of the auditory bulla andinterdigitates with the posterior protuberance of the squamosal; it is connectedto the bulla by a narrow neck. On its latero-ventral surface is an articularface which articulates with a corresponding surface on the posterior lobe of
the periotic bone. (Pl. 4, fig. 8).
Tympanics.
Viewed ventrally, it will be seen that the bulla (B) (Pl. 4, fig. 6) obscuresmuch, if not all (all in adult) of the periotic bone (Pl. 4, fig. 7) lying beneathit. The two bones are connected to one another by a thin, fragile piece ofbone. The eustachian canal opening is directed forward. Externally, theventral surface of the bulla is divided into two lobes, an internal lobe runningparallel with the basioccipital crest and an outer, smaller lobe.
The periotic bone (Pl. 4, fig. 4), perhaps, the most solid in the wholeskeleton (of cetacea), fits closely into a hollow formed in the squamosal. Anteriorly, the periotic is margined by a thin falciform process, arising from thesquamosal. The periotic bone may be divided into three regions; an anterior
lobe with an articular face for the margin of the eustachian tube, a central
lobe perforated by several foramina and a posterior lobe with an articularsurface to receive the counter part of the bulla already referred to.
Manclibles (MN). (Pl. 4, fig. 17)
The mandibles at this early age are very fragile. Along the superior
margin the dentary groove is completely open. Near the posterior union of
the symphysis a single mandibular tooth is present in each ramus. The tooth
is just a hollow triangular shell with an acute tip. (Pl. 4, fig. 17). On theexterior face of each ramus, in the vicinity of the tooth, there are the mental
foramina. The posterior blade of the ramus is about twice as deep as theanterior; the coronoid is slightly anterior to the articular condyle and, theangular slightly posterior to it.
Course of the 5th cranial nerve (trifacial). (Pl. 5)
The course of the 5th cranial nerve in Mesoplodon calls for some comment
because of the great departure of the cranial elements from the more familiar
mammalian type of skull. Because of the distortion that takes place, it isdifficult to correlate the various branches with the ramifications of theSci. Rep, Whales Res. Inst.,
No. 28, 1976.

114

McCANNcorresponding nerves observed in other mammals, including .Man. The exit
foramina of some of the major branches play an important role in taxonomic
description.
The courses of the nerves and the associated blood vessels are represented
in the skull by canals and these have been traced by means of wire tracers.
In the foetus of 1VIesoplodon stejnegeri, as with other mammals, the 5th
cranial nerve leaves the brain case through the foramen lacerum and entersa large cavity (homologous to Meckel's cavity in Man) situated just below themaxillary foramen (MF). Within the cavity lies a large ganglion, Gasserian
Ganglion, which gives off several branches to the facial region. Posteroventrally, a short branch perforates the lateral wall of the anterior nares (NR)tnrough the maxilla ('Nasal' branch). Postero-dorsally, another large branch
is given off which courses backwards, partly through the maxilla and partly
between the maxillary and frontal 'plates', and emerges to the exterior of theskull through the post-maxillary foramen (PMXF). This branch probably
corresponds to the frontal branch (of human anatomy).
Antero-dorsally, two closely associated branches are given off, the larger
emerging to the surface through the maxillary foramen (MF) the smaller,
passing under a bony ridge, crosses the suture between the maxilla andpremaxilla and, finally energes through the premaxillary foramen to the dorsal
surface of the skull.
Below the maxillary foramen a large branch from the ganglion courses
forwards the full length of the maxilla, just below its superior margin, in an
open channel. This branch is the homologue of the dentary nerve (DN) inother mammals. The bony channel is referred to, in cetacean parlance, as
the basirostral groove. The presence (in 1\!I. grayi and 1\!I. bidens) or absencein 1\!I. layardi and others) of the basirostral groove in 1\!Iesoplodon is of somediagnostic value when describing or determining adult skulls and it has been
made use of. In the adult skull of 1\!I. stejnegeri the basirostral groove (BG)
is absent but in the foetal skull the groove is present. (Reference to thedisappearance of the groove in the adult will be discussed below).
From below the premaxillary foramen, a branch leaves the ganglion andcourses forwards, at first through the matrix of the premaxilla and then along
the suture between the premaxilla and the maxilla, to the extremity of therostrum. The canal for this nerve is readily seen in a cross section of therostrum (PN).
Below the dentary branch (DN) another large division leaves the ganglion,
at first descending between the maxilla and the palatine bone, then, entering
the matrix of the maxilla at about the middle of its depth, it descends
gradually to the inferior margin of the maxilla where it emerges by a foramensome distance short of the extremity of the maxilla (median maxillary nerveMMN). Yet another large nerve leaves the ganglion and after coursing
forwards through the matrix of the maxilla emerges by a foramen close to theexit of the median maxillary nerve (MMN). This lower nerve I refer to as
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

FOETAL SKULL OF MESOPLODON STE]NEGERI115

the inferior maxillary nerve (IMN). The last two mentioned nerves probably
correspond to the spheno-palatine nerves.
The presence of the basirostral groove in the foetal skull and its absencein the adult skull, already referred to above, calls for some explanation. As
already observed, the dentary branch enters the so-called basirostral groove
below the maxillary tubercle (MT). Apparently, at an early period of development, the dentary nerve (DN) is intact from the point of emergence from theganglion to the extremity of the rostrum. As growth proceeds secondary bonedevelops at its proximal end and gradually strangles the nerve and blood
supply, eventually cutting off both the neural and vascular supply completely.
This severance of the nerve in lkI. stejnegeri appears to commence some time
before birth, the groove itself gradually filling up, subsequently, with secondarybone, leaving little or no trace of the basirostral groove; however, its erstwhile position is sometimes demarcated by narrow, fragile planges on either
side-its position is often visible throughout the length of the rostrum. Hence,
M. stejnegeri is described as having "no basirostral groove". In the adult ofM. grayi, although the channel is closed off proximally under the maxillary
tubercle (MT), leaving the socalled 'pit', the rest of the channel remains open
permanently.
It is remarkable that, in M. grayi, in which the basirostral groove isalways present, rudimentary teeth frequently occur in the upper jaw, but such
teeth are not socketed in the maxilla, whereas in species devoid of the basirostral groove in the adult, rudimentary teeth have not been observed. Thisobservation seems to suggest that, in M. grayi, the dentary nerve is strangled
at a later period of development than in those species in which the dentarychannel (basirostral groove) is obliterated by the growth of secondary bone.
This suppression of the dentary nerve and blood supply at an early period
of development possibly accounts, at least in part, for the absence of teeth inupper jaws of most Mesoplodon and in other ziphioid whales. However, it isinteresting to observe that, in addition to the functional teeth (in males),vestigial teeth do sometimes occur in some members of the Ziphiidae andtheir presence may be dependent on the extent to which the dentary nerve
has been 'strangled'.
The course of the mandibular branch of the 5th nerve is obviously nottraceable in the foetal specimen. The inferior dental groove is however, open
along its entire length and the functional mandibular teeth are present in thein the rami (one in each). As far as I am aware, rudimentary mandibular
teeth have rarely been observed in Mesoplodon. Fraser (1953) illustrated thepresence of such vestigial teeth in M. bidens. Rudimentary mandibular teeth
have been more frequently reported in Hyperoodon (Boschma, 1950) and in
Ziphius. In Tasmaeetus, the rarest of the family, teeth are present in both
upper and lower jaws. The presence of teeth in both jaws of Tasmaeetus
suggests, perhaps, that it is less specialised than the other ziphioids and retains
part of its more 'primitive' characters.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

116

McCANNACKNOWLEDGMENTS

My thanks are due to Dr. Sir Robert A. Falla, late Director, National Museum,
Wellington, for the opportunity of undertaking the study; to Messrs F. O'Learyand P. M. Hedgland for the photographs accompany this paper, and, last but
not least, to Miss M. Hall, our Librarian, for her help with the relevant
literature.
REFERENCESBOSCH!v!A, H., 1950. Maxillary teeth in specimens of Hyperodon rostratus (Miller) and Nfesoplodon
grayi von Haast stranded on the Dutch Coast. Proc. K. ned. Akad. Wet. Amsterdam, 53: 775786.
FLOWER, H. H., 1872. On recent ziphioid whales, with a description of the skeleton of Berardius
arnouxi. Trans. Zool. Soc. Land., 8: 203-234.
FORBES, H. 0., 1893. Observations on the development of the rostrum in the cetacean genus
1Vfesoplodon, with remarks on some of the species. Proc. Zool. Soc. Land., 1893: 216-236.
FRASER, F. C., 1953. Report on the cetacea stranded on the British Coasts from 1938-1947. Rep.
Get. (Brit. Mus. Nat. Hist.) No. 13: 1-48.
NoR~IAN, J.R. and F.C. FRASER, 1937. Giant Fishes, Whales and Dolphins. London. pp. 1-361.
OLIVER, W.R. B., 1922. The Whales and Dolphins of New Zealand. N. Zeal. Journ. Sci. &Tech., 5(3): 129-141.
RANKIN, J.J., 1956. The structure of the skull of the Beaked Whale, Mesoplodon gervaisi (Deslongchamps). journ. Morph., 99(2): 229-258.

EXPLANATION OF PLATESPLATE I
Stejneger's Beaked Whale: Mesoplodon stejnegeri True.
adult female showing arrangement of elements.
Courtey Nat. Mus. Wellington, N. Z.
(For explanation of lettering see end of paper)

Lateral aspect of cranium of
Photo P. M. Hedgland

PLATE II
Stejneger's Beaked Whale: Mesoplodon stejnegeri True.
adult female showing arrangement of elements.
Courtesy Nat. Mus. Wellington, N. Z.
(For explanation of lettering see end of paper)

Dorsal aspect of cranium of
Photo P. M. Hedgland

PLATE III
Stejneger's Beaked Whale: JV!esoplodon stejnegeri True. Disarticulated elements of the
foetal cranium.
I. Vomer-presphenoid mass (dorsal aspect); 2. Basisphenoid (dorsal aspect); 3.
Basioccipital (dorsal aspect); 4. Vomer-presphenoid mass (lateral aspect); 5. Maxilla(internal face); 6. Maxilla and palatine bone (external face); 7. Pterygoid bone(external face); 8. Pterygoid bone (internal face); 9a. Interparietal (anterior face);
9b. Interparielal (lateral face); 9c. Interparietal (ventral face); 10. Interparietal
with adjacent frontals (dorsal aspect); Ila. Lachrymal bone (ventral aspect); Jib.
Lachrymal bone (dorsal aspect); 12. Basisphenoid (ventral aspect).
de!. C. McCannSci. Rep. Whales Res. Inst.,
No. 28, 1976.

FOETAL SKULL OF MESOPLODON STE]NEGERIPLATE IV
Stejneger's Beaked Whale: l1{esoplodon stejnegeri True. Disarticulated elements of
foetal cranium.
1. Vomer-presphenoid mass; 2. Basisphenoid; 3. Basioccipital; 4. Supraoccipital;
5. Exoccipitals; 6. Bulla; 7. Periotic bone; 8. Portion of squamosal; 9. Posterior
portion of frontal (damaged); 10. Nasal bone; 11. Orbital portion of frontal(damaged); 12. Lachrymal bone; 13. Premaxilla; 14. Maxilla (posterior portion
incomplete) ; 15. Palatine bone; 16. Pterygoid bone; 17. Mandible (with tooth).
(Excepting nos. 5, 9, paired bones show opposite faces; all other bones show thedorsal aspect on! y.
Courtesy Nat. Mus. Wellington, N. Z.
Photo F. O'Leary
PLATE V
Stejneger's Beaked Whale: /Vlesoplodon stejnegeri True. Showing courses of the main
nerves and vascular supply traced in the rostrum of a foetal specimen (Semidiagramatic).
I. Outer aspect of left rostral portion of maxilla. 2. Transverse section on maxilla.
3. Proximal portion of right maxilla showing maxillary foramen and passage ofpremaxillary branch to premaxillary foramen. 4. Divisions of the 5th cranial
nerve ( Diagramatic).
(For explanation of lettering see end of paper.)de!. C. McCann

EXPLANATION OF LETTERING ON PLATESAN-Antorbital notch.
A T-Antorbital tubercle.
B-Bulla.
BG-Basirostral groove.
BO-Basioccipital.
BOC-Basioccipital crest.
BS.-Basisphenoid.
C-Occipital condyle.
DN-Dentary nerve.
EO-Exoccipital.
F-Frontal.
FO-Foramen ovale.
FP-Falsiform process.
GG-Gasserian genglion.
H-Hamulus.
!MN-Inferior maxillary nerve.
IP-lnterparietal.
K-Keel of vomer.
L-Lachrymal.
MC-Meckel's cavity.
ME-Mesethmoid.
MMN-Median maxillary nerve.
MN-Maxillary notch.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

MT-Maxillary tubercle.
MX-Maxilla.
MXC-Maxillary crest.
MXF (MF)-Maxillary foramen.
N-Nasal bone.
NF-'Nasal' nerve foramen.
NR-Anterior nares.
QC-Ossified mesethmoid cartilage.
OG-Optic groove.
OT -Antorbital tubercle.
PL-Palatine bone.
PMF-Post maxillary foramen.
PML-Pterygoid median lamina.
PMX-Premaxilla.
PMXF-Premaxillary foramen.
PS-Presphenoid.
PY-Pterygoid bone.
SO-Supraoccipital.
SQ-Squamosal.
TF-Temporal fossa.
V-Vomer.
VN-Fifth cranial nerve.

117

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PLATE V

McCANN

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

FIRST RECORD OF THE SOUTHERN BOTTLENOSE WHALE,
HYPEROODON PLANIFRONS FROM BRAZILNORTON M. GIANUCA*
A1useo Oceanografico de Rio Grande, BrasilAND
HUGO P. CASTELLO**
Museo Argentina de Ciencias Naturales, Argentina

INTRODUCTION

On the 26 March, 1975 a specimen of the southern bottlenose whale, Hyperoodon
planifrons was discovered on the beach, 5 km north of Chui, near the Brazilian
frontier with Uruguay.
The carcass had been partially £lensed on the middle of the back bynative fishermen who removed some neural spines with fresh meat. When
first observed by staff members of the Museo Oceanografico de Rio Grande(M.O.R.G.) it had probably been dead more than a month and almost all
entrails and some of the left ribs were lacking. The skin, except on thehead and the flukes had sloughed and was partially discolored. A number ofphotographs were taken, dissections were made and the entire skeleton wascollected. Lately it was cleaned and mounted (M.O.R.G. cetacean coll. n°15)
and it is being exhibited in the Cetacean Hall of the previously mentioned
institution. The Brazilian specimen, in addition to extending the range of thespecies from southern Buenos Aires province (Argentina) coast, has provided
data in relation to bone pathology of the species.
EXTERNAL FEATURES

The animal was an adult, total length 7500 mm, black greyish coloured.
The head presented a prominent rounded melon or forehead and a well defined
beak (Fig. I). The V-shaped grooves, 300 mm long each, beneath the chin, adistinctive character of the Ziphiidae, were deep and well defined, The blow hole
showed no curvature, it was 50 mm wide and took the form of a transverse slit
lying just anterior to a transverse plane through the eye.
The pectoral fins, 750 mm long, were small; the dorsal fin that in otherpreviously described specimens is falcate, was lost. A pair of alveoli, 30 mm
wide, with spongy bone on the base can be clearly seen in the tip of the lower* Caixa Postal, 379; 96.200 Rio Grande, RS-Brazil.
** Avda. A. Gallardo 470, Sue, 5; CC 10 Cap. Fed., Argentina.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 119-126.

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GIANUCA AND CASTELLO

122

TABLE 1. SPECIMENS OF THE SOUTHERN BOTTLENOSE WHALE, HYPEROODONPLANIFRONS COLLECTED, PHOTOGRAPHED OR MEASURED IN
SOUTHERN HEMISPHERE WATERS.
RecordNo.

Locality or latitude
and longitude at sea

I

Beach of Lewis Island
Dampier Archipiel.;
NW Australia

before1882

I
I Flower,
1882
I

2

13 miles S. Port Victoria, Yorke Penins.;
S. Australia

22 November, 1929

Hale,
1931

3

Humewood, Port Eliza-18, January,
beth; S. Africa
1964

Tietz,
1966

Date ofI stranding I Authors

MuseumI SexlTotal
ISkull I Evidence Icollection
length lengthn'[-----+1.20( Mutilated Type, 1814A
British Mus.
mt skull(Nat. Hist.)--2852, South
6.93 I. 39 Complete
Australia
0 mt
mt skeleton
Museum0

6. 361 I. 21
mt
mt

Skull andmandible

I

I. 15
mt

Skull
fragment

CanterburryMus.; notavailable--

4

Beach at East Cape;N. Island; New Zealand

5

Brown's beach, near
Timaru, 5 miles from
Winchester, S. Island;
New Zealand

6

Malvinas (Falkland)lsl.; Gran Malvina
and Soledad Island

7

Vicinity of Orcadas de!
Sur (S. Orkney) Isl.

8

Vicinity of Georgias delSur (S. Georgia) lsl.

9Leith Harbour, Georgias del Sur (S. Georgia) Isl.

before1912

i

Waite,
1913

7.50
mt

----- --before
1959

McCann,1961

August*1950

Hamilton,
1952 andQ
Fraser, 1964

Symphyseal
1417
mandible
Dominion
portionMuseumQ---

I

I January,
1915
near,

BritishRest of
Museumthree
specimens (Nat. Hist.)

6. 70*
mt---

Fraser,1945

1934

Fraser,1945

3 January,
1927

Fraser,1945

Photographed ona whal. ship1---6.50 I. 19
Q
mt
mt

Completeskeleton

1934. 7.23.3
Brit. Mus.

--

----

0

4.63
mt

Photo0.69 graphed in
mt whal. stat.

-----

10

Near Gritviken, Georgias del Sur (S. Georgia) Island

November,
1929

Carcelles
1948

II

Near Shetlands delSur (S. Shetland) Isl.

before,1929

Marelli,
1929

12

On the beach near
Arroyo Sauce Viejo, s.
Buenos Aires Prov,;
Argentina

13

60 km SW of Viedma,
Rio Negro Province;
Argentina

14

Vicinity of Chubut
River, Chubut Province; Argentina

0

6.54

I. 44

54-110, Mus,
Arg. Cs.
Completeskeleton Nat.; Buenos
Aires

---

Five specimens hunted---

early,
1884

Moreno,1895

La Nacion
25 August, 19/X/65;
1965
Brownell,
1974
Moreno,
1895

6.25
mt

I. 15
mt

Completeskeleton

1121, Mus.
Cs. Nat.
La Plata
Argentina

Photographs Salesianand skull Museum at
Viedma+7.00
mt+ 1.10mt

SkullMus. Cs.
Nat. La
Plata

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

HYPERUODON PLANIFRONS

123(Continued of Table 1.)

---1
15

16

I, Beach at Santa Cruz
I Bay, Santa Cruz Pro- IrIIvince; Argentina____

South Pacific Coast;
Chile ?
_

I

I
~,
17
I 61 o09'S-86o4 4 'E[

I Moreno, !['
I
1895
11

11

1

1,

l

1·

I
1

1

!

18-20

45 lYS- 58 IO'W
00

I 57°33'S-05°08'E

I 56ol4'S- 86 o58 ElMoreno,1895
Fraser,
1964

I

i
r

1

I mt [ mtl:-1I, Q j 7. 45]
I mt J

CompleteskeletonCompleteskeletoni- 6. 80 1---1

3 April, I
1962
I Zemskii \1 16 DecemandI1ber, 1966 \ Budylenko, [1970,
18 January, I
1968

'!

r'

I

II Mus · Cs ·Nat. La
Plata

I

i~l~I 0. 81
ILeftmandible

I ~~:: 2~·
I Plata

IBrit. Mus.
(Nat. Hist.)I

mt I
I Photo7. 00 : 1. 31 graphed and[d
mt I mt 0i;:e:s~i;'fal-,

5. 70 I
mt I

ing vessel?
?

I* Female complete skeleton collected at East Falkland.

More recently at 45°'S-58°10'W, one bottlenose whale 6.80 m long was hunted
by a Russian whaling ship and was measured by Zemski and Budylenko (1970).
In the Chilean coast, Clarke (1962) reported a sighting of five specimens
off Valparaiso (21/X/1958). Morzer Bruyns (1971) saw a pod off Chile, estimatedto comprise about 40 specimens (May, 1965).
According to McCann (1962), Hyperoodon planifrons is restricted to thesouthern Hemisphere, south of 20 degree latitude and it has been alsomentioned (Table 1) for New Zealand by Waite (1913), McCann (1961) andGaskin (1968), for South Africa by Tietz (1966) and Australia by Flower (1882)
and Hale (1931).
During the summer it seems to be abundant in the Subantarctic andAntarctic oceans (Table 2).
CONCLUSIONS

Including the Rio Grande do Sul specimen, 8 complete skeletons of the southernbottlenosed whale had been recovered, half of them are stored in Argentine
and Brazilian museums. Only one specimen is known to have stranded alive.
The Rio Grande do Sul specimen, probably a male, was surely very old as
the several hyperostotic growths and decalcification signs may suggest.
ACKNOWLEDGMENTS

We want to express our gratitude to Dr. Eliezer Rios, director of the M.0.R.G.
who helped to bring the bottlenosed whale carcass to Rio Grande city andalso to clean the bones. To Mr. Lauro Pereiro Barcellos and Mr. Rodnei
Nascimento who actively worked and mounted the whole skeleton in the
Cetacean Hall of the M.O.R.G. Also to Mr. Lauro Calliari who passed us
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

GIANUCA AND CASTELLO

124

TABLE 2. SIGHTINGS ATTRIBUTED TO HYPEROODON PLANIFRONS IN THE
SUBANTARCTIC AND ANTARCTIC OCEANS ACCORDING TO LIOUVILLE(1915), LILLIE (1915), WILSON (1907), TOMILIN AND
LATYSHEV (1967) AND DUGUY (1973).
RecordNo.

LI"

oca ityII

I

Latitude and I D
f . h .
Number of: Ob
longitude' ate o s1g tmg specimens iserver:_ _ _ _ ___ _ _ _ _ _ _ _ _ _ _ _ _ _ !_ _ _ _ _ _ !

---------III
Weddel Sea

2
3

72°22 1 -19°10'
69°46 1 -19°10'

II

73°30'-24°00'

4 March, 1904 I
some
Wilson[ 21 Fehr., 1903 I ·-sc_a_r-ce_I _______

il~h, 1904J s_ev~;J"~/--.-,-,- -Fehr.,~~--'

4 - 1 - - - - - - - - - 1/WoS'-32°10'---/.....!O
2·--·--_ _5_ _ ,_ _ _ _"_ _ _ _ _ _ _65_0_2_9_'-_4_4_00_6_'_1 12 March, 1903 j _ _2___ ,_ _ _" _ __
1
1
6
I South Atlantic
59°43 1 -48°10' 1 28 Nov., 1903 f _-=-.....:.=_i __B_ro_w_n__7

Drake Passage--

7 Dec., 1972

I

i
0
0
___
a __ ,__D_ec_e_p_t_io_n_Is_l_an_d_ _ _ /_6_3__00_'_-6_0__40_'_\28 Nov 1909- I
6 Jan.:' 1910

9Petermann Island/ 65°10'-66°12'----1----------1
10
Bransfield Strait
64°49'?-65°40'

5 May 1909'
27 Nov., 1909

_ _l_l__ 1__M_at_h_a_B_ay~---i-~~50'-70°00'_ _1_2__ 1__M_e_r_d_e_la_B_e_lg"-i~q.__u_e_I 69°54 1 -82°35'

I

"
,,

2 or 3.

1'!- 3.______1±_Jan., 1909----·:-----------1-------,

15

20:! Liouville
I
"
1---·
1_ _". _ __/'"70°15'-87°05'

7 Nov., 1898__l_o_r_2 ··-·

6 Sept., 1898__3_o_r_4_j _ _ _" _ __lst Jan., 19101-----,1

Liouville

19 Jan., 1899

3 or 4

Racovitza1----[----------

Racovitza

J

70°16' -87°12'
20 Jan., 1899i00
_ _1_7__ 1_ _ _ _'_'_ _ _ _ _ _ 1__7_0_3_0_'-_9_3__57_'_ 1__15_F_e_b~.,'--18_9_9_
18"
70°38'-88°56'
2 May, 1898----·1---------1-------1---~~---1
19"
70°41'-86°34' 1·1--3~Ju_l~y-~,_1_8_9_8_'11
20
Admunsen Sea
68°24' -122°38'
22 Jan., 1910
·

f

Duguy

i.

1
·1

13 - 1 - - - -"- - - - - - 1 i 69°55'-82°36'--- - - - - - 1,
14"
69°29 1 -85°47' j
16

2

i

-1-----1----·-------1-----~----1------,

I

1
3 or 44
5 or 6
I,---.. ,,l---"---"
1-----

1---"--jI___l_:.iouv~

21
ss lea, Balleny
69°51'-166°17'
29 Dec., 1912
/ ---- i
Lillie1- - - - __s_a_n_s_a_r_e_a_ _ _ _ 1_ _ _ _ _ _ _ 1_ _ _ _ _ _ _ _1
12~_M_c_?v_Iu_r_d_o_St_r_a_it___ 1__
77_0_0_0_-_l_66_0_0_0_
I 25 Fehr., 1902
_6_o_i:._8_ _ _W_i~_so_n__0j-----

11I

77°30 1 -166°00 1
Fehr., 1904 : ._-_-_-_ , __\:Yi_l~on _00__24_ _ 1_R_os_s_S_e_a_ _ _ _ _ -6-2-0_0_'_-_16_2__03_'_l _ _l_O_M_a__rch, 1911 I _2___
25"
69°51'-166°17'
29 Dec., 1912
i --"
23

"

26

"

I
1

27

Subantarctic Indian
Ocean sector

77°32 1 -173°22'
48 o 00 , _100 o 00 , E·---1- - - - - ----·~-

1903

I

Racovitza

---

I

l
'"ils. on
5 N ov., 1904 ?· !1_ _ _____vv_ _ __

Antarctic Indian1_ _2_a__ 1__0_ce_a_n_se_c_t_o_r_ _ _ , 57000'-150000'E(_l_7_J_a_n_._'_I_9_65__ ,___3___
29

Antarctic Pacific
Ocean sector

I 62°00 -162°03'E I 10 March, 1911 1I
1

2

Tomilin and
Latyshev

I

Lillie1

information about the stranding. Our gratefulness to Lie. Raul Aramburu
and Dr. Roberto Menni from La Plata Natural Sciences Museum, Argentina
for passing us information and photographs of the Viedma museum. Also to
Dr. Edward Mitchell who kindly reviewed this manuscript while he stayed at
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

HYPEROODON PLANIFRONS

125

Buenos Aires and made some good suggestions. Also to Prof. Euripides Falcao
Vieira, Dean of the Rio Grande University who helped the second of us
to travel from Argentina to Brazil and provided support for studying thebottlenosed specimen.
REFERENCES
BROWi\ELL, R. L. ]., 1974. Small odontocets of the Antarctic. In: Antarctic Mammals (ed. G.
Llano), Amer. Geogr. Soc. Antar. Map Flio Ser. no. 18: 13-19.
CARCELLES, A., 1948. Los cetaceos en !as aguas argentinas. Argentina Austr. 20(208): 1-10.
CLARKE, R., 1962. Whale observation and whale marking off the coast of Chile in 1958 andfrom Ecuador towards and beyond the Calapagos Islands in 1959. Norsk Hvalfangst-tid., 51 (7) :265-287.
DAGUY, R., 1973. Notes de voyage en Mers Australes (Patagonie, Terre de Feu, Antarctique).
Science et Nature, No. 120: 2-9.
FLOWER, W. H., 1882. On the cranium of a new species of Hyperoodon from Australian seas.
Proc. Zoo!. Soc. London: 392-396.
FRASER, F. C., 1945. On a specimen of the southern bottle-nosed whale, Hyperoodon planifrons.
Dicovery Rep., 23: 19-36.
FRASER, F. C., 1964. Whales and whaling. In: Antarctic Research (ed. R. Priestley and others)•
Butterworths: 191-205.
GASKIN, D. E., 1968. The New Zealand Cetacea. Fish. Res. Bull. New Zealand No. I (New Ser.):
1-92.
HALE, H. M., 1931. Beaked whales-Hyperoodon planifrons and Mesoplodon layardi from South
Australia. Ree. Austral. Mus., 4(3): 291-311.
HAMILTON, J.E., 1952. Cetacea of the Falkland Islands. Comunic. Zoo!. Mus. Hist. Nat ..
Montevideo, 4(66) : 1-6.
LILLIE, D. G., 1915. Cetacea. In: Brit. Antar. "Terra Nova" Exped. 1910. Nat. Hist. Rep. Zool.
3(1): 85-124.
LIOUVILLE, J., 1913. Cetaces de l'Antarctique (Balein, Ziphiides, Delphin) in 2eme. Exped. Antar. Franc.
1908-1910, comm. par. ]. Charcot. (Masson et Cie. ed) : 276 pp.
MARELLI, C. A., 1929. El exterminio de !as ballenas en nuestros mares. "El Argentino'', edicion
7 /V /1929, La Plata.
McCAN"', C., 1961. The occurrence of the southern bottle-nosed whale, Hyperoodon planifrons,
Flower in New Zealand waters. Ree. Dominion Mus. New Zealand, 4(3): 21-27.
McCANN, C., 1962. The taxonomic status of the beaked whale Mesoplodon paci.ficus Longman.
Ree. Dominion Mus. New Zealand, 4(10) : 95-100.
MORCH, J. A. C., 1911. On the natural history of whalebone whales. Proc. Zoo!. Soc. London:
661-670.
MORENO, F. P., 1895. Nota sobre los restos de Hyperoodon conservados en el Museo de La Plata.
Anal. Mus. La Plata, ::;ool., 3: 3-8.
MbRZER BRUYNS, W. E.]., 1971. Field guide of whales and dolphins. 258 pp, Amsterdam.
NISHIWAKI, M., 1972. (Cetacean) General biology. In: Mammals of the sea, biology and medicine(Ed. Ridgway) : 3-204; C. C. Thomas Pub!., Springfield.
TIETZ, R. M., 1966. The southern bottle-nose whale, Hyperoodon planifrons, from Humewood,Port Elizabeth. Ann. Cape Prov. Mus., 5: 101-107.
TOMILIN, R. M. and LATYSHEV, V. M., 1967. New data on the flat-fronted bottle nose, (Hyperoodon planifrons). Moskrov. Obshch. Ispytateel Prirody. Biull. Otd. Biol., 72: 119-122 (inRussian).
VIEIRA, C., 1955. Lista remissiva dos mamiferos do Brasil. Arq. Zoo!. Est. Sao Paulo, 8: 341-474.
WAITE, E. R., 1922. Two Ziphioid whales not previously recorded from South Australia. Ree.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

126

GIANUCA AND CASTELLOSouth Austral. Mus., 2: 209-214.
WILSON, E. A., 1907. Cetacea. In: Nat. Antarct. Exped. Nat. Hist. Zool., 2:
XIMENEZ, A., LANGGUTH, A. and PRADER!, R., 1972. Lista sistematica de los mamiferos de!
Uruguay. An. Mus. Nac. Hist. Nat. Montevideo (2a. serie), 7(5): 1-49.
ZEMSKII, V. A. and BUDYLENKO, G. A., 1970. Flatheaded botlenoses from the Antarctic, Trudy
Atlant. Nauch. Issled Inst. Ryb. Kho;;,. Okeanograj., 29: 193-202.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

A SHEPHERD'S BEAKED WHALE, TASMACETUS SHEPHERD!,FROM THE EASTERN SOUTH PACIFICROBERT L. BROWNELL, JR.
Department of Vertebrate Zoology, National Museum of Natural History,
Smithsonian Institution, Washington, D. C.

ANELIO AGUAYO L.
Section for Vertebrate Zoology, Swedish Museum of Natural History, Stockholm

AND
DANIEL TORRES N.
Departamento Ciencias Naturales y Exactas, Sede Santiago Sur,
Universidad de Chile, Santiago

W.R.B. Oliver (1937) described a new genus and species of beaked whale (Family:
Ziphiidae) from a carcass found stranded on the coast of North Island (Ohawe,
Taranaki), New Zealand. Since the holotype was described only six additional
records of this species have been described: five from the New Zealand region
and a sixth from Peninsula Valdez, Province of Chubut, Argentina (Mead andPayne, 1975). We report here a new record from the eastern South Pacific.
A cranium, left mandible, and cervical vertebrae were found by Aguayo
and Torres just south of Loberia Vieja (see Figure 2 in Aguayo et al., 1971)
on the eastern coast (ea. 33°46'S, 80°47'W) of Isla Mas Afuera (Alejandro Selkirk
Island), Juan Fernandez Archipelago, Chile, 19 February 1970. The specimen
was not collected, but was photographed. These photographs are on file at theDivision of Mammals, Smithsonian Institution. It was identified as T. shepherdi
by comparing these photographs with those published by Oliver (1937) and
Moore (1968). The photographs also agree with the specimen of T. shepherdi
in the U.S. National Museum (No. 484878). The characters of the vertex andthe numerous alveoli are clear in the photographs and leave no question about
the identity of the specimen. The skull length of the new specimen, with partof its rostrum damaged, is estimated at 100 cm. We estimate that the original
condylobasal and mandible lengths were 125 cm and 107 cm respectively. This
specimen, with no reference, was one of the eight records of T. shepherdi
recorded in Anonymous (1975: 897). The Isla Mas Afuera and Peninsula Valdez
specimens suggest that T. shepherdi may have a circumpolar distribution in theSouthern temperate oceans, as do many other species of cetaceans (Brownell,1974).
We thank JG. Mead for reviewing our manuscript.

.Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 127-128.

128

BROWNELL, AGUAYO AND TORRESREFERENCES
AGUAYO L., A., R. MATURANA C. and D. TORRES N., 1971. El lobo fino de Juan Fernandez.
Rev. Biol. Mar., Valparaiso, 14: 135-149.
ANONYMOUS, 1975. Review of biology and fisheries for smaller cetaceans. E. Mitchell [ed.],J. Fish. Res. Board. Can. 32: 875-1242.
BROWNELL, R.L.JR., 1974. Small odontocetes of the Antarctic. In: V.C. Bushnell [ed.], Antarctic Map Folio Series, Folio 18, Am. Geogr. Soc., New York, pp. 13-19.
MEAD, J.G., and R.S. PAY!'IE, 1975. A specimen of the Tasman beaked whale, Tasmacetus shepherdi, from Argentina. J. Mammal., 56: 213-218.
MOORE, J.C., 1968. Relationships among the living genera of beaked whales, with classifications,diagnoses and keys. Fieldiana: Zoology, 53 : 209-298.
OLIVER, W .R.B. 1937. Tasmacetus shepherdi: a new genus and species of beaked whale from New
Zealand. Proc. Zool. Soc. London, ser. B, 107: 371-381.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

RECORDS OF THE DELPHINID GENUS STENELLA
IN WESTERN SOUTH ATLANTIC WATERSROBERT L. BROWNELL, JR.
Department of Vertebrate Zoology, National Museum of Natural History,
Smithsonian Institution, Washington, D. C.

AND
RICARDO PRADER!
Afuseo Nacional de Historia Natural
Casilla de Correo 399 Montevideo, Uruguay

INTRODUCTION

Little information has been published on Stenella spp. from the western South
Atlantic Ocean. Numerous references (Lahille, 1899 and 1905; Beddard, 1900;
van Beneden and Gervais, 1880; Figueira, 1894; and others-see text) exist citing
the long-snouted dolphin, S. longirostris, in Brazil, Uruguay, and Argentina,
but none of these reports are confirmed with specimens. A single report of S.
attenuata in this area is an unconfirmed mention from Cape Horn (Beddard,1900). The holotype of the striped dolphin, S. coeruleoalba, was collected somewhere around the mouth of the Rio de la Plata (River Plate) between Uruguay
and Argentina (Meyen, 1833). Since that time only three additional specimens
have been reported from this region (Malm, 1871; and Praderi, In: Ximenez,
et al., 1972).
The purpose of this note is to provide information on museum specimensof Stenella spp. in Uruguay and Argentina. We will also discuss the older
references of S. longirostris in western South Atlantic waters.
MATERIALS

The present study is based on the examination of the cetacean collections infive South American museums. These are: Museo Argentino de Ciencias Naturales "Bernardino Rivadavia ", Buenos Aires, Argentina (MACNBA); Museode La Plata, La Plata, Argentina (MLP); Museo Nacional de Historia Naturalde Montevideo, Uruguay (MNHNM); Museu Nacional do Zoologia de la Universidad de Sao Paulo, Brazil (MZSP) ; and Museu N acional do Rio de Janeiro,
Brazil (MNRJ). No specimens of Stenella were found in either of the Brazilian
museums.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 129-135.

130

BROWNELL AND PRADER!

SPECIES ACCOUNTS

Stenella coeruleoalba-Fraser and Noble (1970) have concluded, based on pigmentation patterns of specimens, that several nominal species of Stenella (Delphinits
coerulealbus Meyen, 1833; D. marginatus Desmarest, 1855± 1; D. euphrosyne,
Gray 1846; D. styx, Gray, 1846; and D. lateralis Peale, 1848) with a spinal blaze
and eye-to-anus stripe (terminology of Mitchell, 1970) probably belong to one
species, S. coeruleoalba Meyen, 1833). Hubbs et al. (1973) have stated that theirrecords of S. coeruleoabla across the tropical Pacific supports the view " that thenorthern and far-southern populations of this species are conjoined and thus
confirms the synonymy adopted by Fraser and Noble (1970)."
We have examined two S. coeruleoabla specimens: (1) a skull (MNHNM
1305) from Balneario Solymar, Depto. de Canelones, Uruguay (34°49'S., 55°55'W),
Rio de la Plata; and (2) a skull (MACNBA 2625) from Miramar, Pcia. Buenos
Aires, Argentina (38°17'S.) Atlantic Ocean. The cranium from Punta Jose
Ignacio, Uruguay that Praderi reported in Ximenez et al. (1972) was not available to us.
The only skull measurements available for this species from the type locality
are those of Meyen (1833) and Malm (1871 : 63, holotype of Clymenia bitrmeisteri). Cranial dimensions in millimeters and dental counts of the two specimens we examined of S. coeruleoalba are presented in Table 1. No additional
information is available for the Miramar specimen. The Solymar skull wascollected from a stranded specimen by Praderi on 23 August 1959. The total
length of the carcass (notch to tip of lower jaw) was 242 cm. The specimen
was a male.
Stenella spp.-Various scientific names are currently used for spotted dolphins. These include S. attenuata (Gray, 1846) in the Pacific, Indian, andAtlantic Oceans, and S. dubia (G. Cuvier, 1812); S. frontalis (G. Cuvier, 1829),
and S. plagiodon (Cope, 1866) in the Atlantic. There are probably only two
valid species (Perrin, 1975).
'
We examined one skull that can be referred to the spotted dolphin complex.
This specimen (MACNBA 23-46) is from Mar del Plata, Pcia. Buenos Aires,
Argentina (38°00'S.) Atlantic Ocean. The date of collection was 1923, but noadditional information is available for this specimen. Skull measurements anddental counts of this specimen are presented in Table 1. The skull is illustrated
in Plate 1.
Stenella longirostris- This species was described as Delphinus longirostrisfrom an unknown locality (Gray, 1828). Van Bree (1971) stated that the complete synonymy proposed by Hershkovitz (1966: 37-40) is probably correct, but"much more must be known before definite conclusions can be drawn about the
taxonomic status and nomenclature of Stenella longirostris." This species has
been reported from both sides of the tropical Atlantic Ocean (Moore, 1953;
Cadenat and Doutre, 1959; Layne, 1965; van Bree, 1971; Caldwell et al., 1971;
and van Halewijn and van Bree, 1972). We found no specimens referable toSci. Rep. Whales Res. Inst.,
No. 28, 1976.

131

STENELLA SPP. SOUTH ATLANTICTABLE 1.

SKULL MEASUREMENTS (MILLIMETERS) AND DENTAL COUNTS OFSTENELLA SPP. FROM WESTERN SOUTH ATLANTIC WATERS.
MAC NBA

Measurements

2625

%CBL

mm
Condylo-basal length
Rostrum length
Rostrum basal width
Rostrum, width 60 mm anterior to base
Rostrum, width at middle

442
260
111
70
59

100.0
58.8
25. 1
15.8
13.3

MNHN

MACNBA

1305

23-46

mm

mm

402+

389
230
93
60
45

100.0
59.1
23.9
15.4
11. 6

34

8. 7

24
272

6.2
69.9

163

41. 9

162

41. 6

43
70
142
65
48
186
189

11. 1
18.0
36.5
16. 7
12.3
47.8
48.6

120
77

Rostrum, width at 3/4 the distancefrom the basePremaxillae width at middle
Tip of snout to blowhole
Tip of snout to pterygoid
Preorbital width
Post-orbital width
Orbital width
Zygomatic breadth
Blowhole, width atMaximum width premaxillae
Braincase width across parietals
Temporal fossa length
Temporal fossa height
Length of tooth row upper R.
Length of tooth row upper L.
Mandible length
Coronoid height
Length of symphysis
Length of tooth row lower R.
Length of tooth row lower L.
Number of teeth upper R.
Number of teeth upper L.
Number of teeth lower R.
Number of teeth lower L.

305
321
185
206
191
209

150
71
46
230
229
374
67
50
226
226
44
45
43
43

69.0
72.6
41. 8
46.6
43.2
47.3

33.9
16. 1
10.4
52.0
51. 8
84.6
15.1
11. 3
51. 1
51. 1

217
236
215
233

174
71
45

%CBL

407
76
231
227
34+
37
50+
49+

S. longirostris in five eastern South American museums. As noted in the
introduction, numerous authors have reported S. longirostris and the probably
conspecific nominal species (see van Bree, 1971) Delphinus alope and D. microps
from localities including Brazil, Uruguay, Argentina and Cape Horn. All
southern " records" are without documented specimens or observations. In viewof this confusion, we present below the genesis and chronological review ofwestern South Atlantic "records" for this species.
Gray (1866) reported Delphinus alope from "Cape Horn", but the specimen
is apparently now not extant in the British Museum (Natural History) and no
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

132

BROWNELL AND PRADER!

additional information is available in the museum on the collection locality ofthis specimen (W. F. Perrin, per. comm., 1973). Based on the valid records of
S. longirostris, this species is known worldwide only in tropical waters. It isextremely unlikely that S. longirostris will ever be recorded from the coldtemperate waters of southern South America. In fact, this species is still not
known from any of warm-temperate waters of the world. The reports of thisspecies from Chilean waters by Schneider (1946) and Mann (1957) are without
any type of documentation and should be discounted. The "records" of Gray
(1866), Schneider (1946) and Mann (1957) are probably what influenced Marcuzzi
and Pilleri (1971) to map the erroneous distribution of S. longirostris around
Cape Horn.
Gray's comments (1850: 126, 1866: 240 and 1871: 69) are all apparently basedon one specimen of Delphinus microps from the " coast of Brazils " from Dr.
Dickie's collection. This specimen was probably collected in the tropical waters
somewhere north and east of Rio de Janeiro. Burmeister (1867 and 1879)
provided the following accounts about D. microps: (1867) "vive en el alto
mar Atlantico al sud del ecuador y se presenta muchas veces a los viajeros enbuques de velas. Tenemos en el Museo Publico dos craneos completos, el uno
regalado por el Sr. Dr. D. Miguel Olaguer Feliu", (We could not find eitherof these skulls in the museum, MACNBA.) and (1879) "on trouve cette espece
clans l'Ocean Atlantique, principalement au sud de l'Equateur, par troupes de
20 a 30 individus. Ils suivent quelquefois la marche du navire et passent enbondissant a son avant. Je les ai apercus et etudies plusieurs fois pendant lesquatre voyages que j'ai faits clans cette partie de l'Ocean. (Voyez mon voyage
du Bresil, page 37, Berlin 1853)". Van Beneden and Gervais (1880) cited D.
microps from the mouth of the Rio de la Plata and the coast of Brazil. They
provided no new data and probably just followed the above statements by Grayand Burmeister. Figueira (1894) noted that "Delphinus microps Gray. Tonina.
Es una de las especies mas comunes en nuestras costas sobre el Rio de la Plata,
especialmente en los meses de Noviembre a Febrero ". Tonina is used today
in Uruguay by laymen for Tursiops cf. truncatus and this is what Figueira's
records of D. microps must have been. Lahille only noted the following: (1899)"Delphinus delphis Linneo. Esta especie (D. microps Burm, nee Gray) se hanotado en las costas del Chubut" and (1905) "Prodelphinus longirostris. Cahode Buena Esperanza, Australia; Costas de la Provincia de Buenos Aires".
Carcelles (1948) stated that "Prodelphinus longirostris Cuvier, Habita tambien
el litoral atlantico bonaerense, asi como las Islas Galapagos, Panama, Australia.
En el Museo de la Estacion Hidrobiologica de Puerto Quequen, puede verse
un modelo en yeso del craneo ".
RESUMEN
Se proporcionan medidas y detalles de 3 especimenes de delfinidos del genero

Stenella del Oceano Atlantico Sudoccidental. Se cita por primera vez para esta
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

STENELLA SPP. SOUTH ATLANTIC

133

area un ejemplar del "spotted species complex". Se mencionan tambien 2
especimenes de S. coeruleoalba, 1 de Uruguay y 1 de Argentina, de lasproximidades de la localidad tipica (desembocadura del Rio de la Plata).
De S. longirostris no se encontraron ejemplares en ninguna de las colecciones
de 5 museos sudamericanes (ver Materials) del cual tampoco existen datos deespecimenes documentados en la literatura, citados para el Oceano Atlantico
Sud occidental.
ACKNOWLEDG MENTS
We are indebted to the following for allowing us to examine specimens in theircare : Jorge Crespo and Elisa Kantis (MACNBA); Raul Aramburu (MLP);
Miguel A. Klappenbach (MNHNM) ; Paulo Vanzolini (MZSP) ; and Daley deAlbuquerque (MNRJ). William F. Perrin provided valuable information andPerrin and P.J. H. van Bree read the manuscript and provided useful criticism.
REFERENCESBEDDARD. F. E., 1900. A book of whales. John Murray, London. 320 p.
BENEDEN, P. J. VAN, and P. GERVAIS, [ 1868-1880]. Osteographie des cetaces vivant et fossiles
comprenant la description et iconographie du squelette et du systenie dentaire de ces animaux
ainsi que des documents relatifs a leur histoire naturelle. Arthus Bertrand, Paris. 634 p.,
68 pl.
BREE, P. J. H. VAN, 1971. On skulls of Stenella longirostris (Gray, 1828) from the eastern Atlantic.
(Notes on Cetacea, Delphinoidea IV.). Beaufortia, 19: 21-25.
BURMEISTER, G., 1867. Fauna Argentina. Mammifera Pinnata Argentina. An. Mus. Publico B.
Aires, 1(7): 301-311.
BURMEISTER, H., 1879. Description physique de la Republique Argentine. Animaux Vertebres. !ere.
Partie. Mammiferes vivants et eteints. Avec Atlas, 3 ,: 1-555.
CADENAT, J., and M. DoUTRE, 1959. Notes sur les Delphinides ouest-Africans. V. Sur un
Prodelphinus a long bee capture au large des cotes du Senegal Prodelphinus longirostris (Gray)
1828? Bull. I. F. A. N. Ser. A 21 (2): 787-792.
CALDWELL, D. K., M. C. CALDWELL, W. F. RATHJEN, and J. R. SULLIVAN, 1971. Cetaceansfrom the Lesser Antillean Island of St. Vincent. Fish. Bull., 69(2) : 303-312.
CARCELLES, A., 1948. Los cetaceos en las aguas argentinas. Rev. Mus. Arg. Cienc. Nat., Pub!.
Extra, 238: 5-10.
FIGUEIRA, J. H., 1894. Contribucion a la fauna Uruguaya. Enumeracion de Mamiferos. An.
Afus, Nac. Afontevideo, Ser. I, 1: 187-217.
FRASER, F. C., and B. A. NOBLE, 1970. Variation of pigmentation pattern in Meyen's dolphin,
Stenella coeruleoalba (Meyen). In: G. Pilleri [ed.], Investigations on Cetacea, Vol. 2, p. 147-163.
GRAY, J.E., 1828. Spicilegia zoologica; or original figures and short systematic descriptions of
new and unfigured animals. Treuttel, Wurtz and Co. and 'vV. Wood, London.
GRAY, J.E., 1850. Catalogue of the specimens of Mammalia in the collection of the British Museum.
Part I. Cetacea. Trustees, British Museum, London. 153 p.
GRAY, J.E., 1866. Catalogue of seals and whales in the British Museum. Trustees, British Museum,London. 402 p.
GRAY, J.E., 1871. Supplement to the Catalogue of seals and Whales in the British Museum. Trustees,
British Museum, London. 103 p.
HALEWIJN, R., and P. J. H. VAN BREE, 1972. On the occurrence of the common dolphin,Sci, Rep, Whales Res. Inst.,
No. 28, 1976.

134

BROWNELL AND PRADER!

Delphinus delphis, and the spinner dolphin, Stenella longirostris, off the coast of Venezuela. In.
G. Pilleri [ed.], Investigations on Cetacea, Vol. IV, p. 187-188.
HERSHKOVITZ, P., 1966. Catalog of living whales. U.S. Nat. Mus. Bull., 246: 1-259.
HUBBS, C. L., W. F. PERRIN, and K. C. BALCOMB, 1973. Stenella coeruleoalba in the eastern andcentral tropical Pacific. J. Mammal., 54: 549-552.
LAHILLE, F., 1899. Ensayo sabre la distribucion geografica de los mamiferos de la Republica
Argentina. Prim. Reun. Congr. Cient. Lat. Amer., 3: 165-206.
LAHILLE, F., 1905. Las ballenas de nuestros mares, sus costumbres y aprovechamiento. Rev.
Jard. Zool. Buenos Aires, I (I) : 28-82.
LAYNE, J. N., 1965. Observations on marine mammals in Florida waters. Bull. Fla. State Mus.,
9 (4): 131-181.
MALM, A. W., 1871. Hvaldjur I sveriges museer ar 1869. Kong!. Svenska Vetensk. Akad. Hand!.,9(2): 1-104.
MANN, F. G., 1957. Clave de determinacion para !as especies de mamiferos silvestres de Chile.
Invest. Zoo!. Chilenas, 4: 89-104.
MARCUZZI, G., and G. PILLER!, 1971. On the zoogeography of Cetacea. In: G. Pilleri [ed.],Investigations on Cetacea, Vol. III, p. 101-170.
MEYEN, F. J. F., 1833. Beitrage zur Zoologie, gesammelt auf einer Reise um die Ertle. Nov.
Act. Acad. Caes. Leop. Carol. Nat. Curios., 16(2): 551-610.
MITCHELL, E., 1970. Pigmentation pattern evolution in delphinid cetaceans: an essay inadaptive coloration. Canadian J. Zool., 48: 717-740.
MOORE, J.C., 1953. Distribution of marine mammals in Florida waters. Amer. Mid[. Nat.,49(1): 117-158.
PERRIN, W. F., 1975. Variation of spotted and spinner porpoise (genus Stenella) in the eastern
tropical Pacific and Hawaii. Scripps Inst. of Oceanogr. Bull., 21, 181 p.
SCHNEIDER, C. 0., 1946. Catalogo de los mamiferos de la Provincia de Concepcion. Bol. Soc.
Biol. (Concepcion), 21: 67-83.
XIMENEZ, A., A. LANGGUTH, and R. PRADER!, 1972. Lista sistematica de los mamiferos de!
Uruguay. An. Mus. Nac. Hist. Nat. ,Montevideo, 2 Serie, 7(5): 1-49.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

STENELLA SPP. SOUTH ATLANTICEXPLANATION OF PLATE
PLATE I
Fig. 1. Stenella sp. referred to the spotted dolphin complex (see text). This specimen(MACNBA 23-46) is from Mar del Plata, Pcia. Buenos Aires, Argentina (38°00'S.)
Atlantic Ocean. Dorsal view of specimen.
Fig. 2. Stenella sp. (MACNBA 23-46) ventral view of specimen.
Fig. 3. Stenella sp. (MACNBA 23-46) lateral view of specimen.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

135

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AN OBSERVATION ON THE PAPILLARY PROJECTIONS AT
THE LINGUAL MARGIN IN THE STRIPED DOLPHINFUSAO YAMASAKI
Department of Biology, Sapporo Medical College, Sapporo

HAJIME SATOMI
Department of Anatomy, Sapporo Medical College, Sapporo

AND
TOSHIRO KAMIYA
Department of Anatomy, Faculty of Nfedicine, University of Tokyo, Tokyo

ABSTRACT

Papillary projections were observed along the anterolateral marginsof the tongue in fetal and young stages of the striped dolphin, Stenella
coeruleoalba. The projections appear in the fetal stage and attain maximum development in the early postnatal period. They disappear almost
completely by weaning, although small vestigial eminences remain at thecorresponding region in the adult. The projections may have a close
relation to suck milk.

There are few descriptions of the anatomy of the tongue in Cetacea, and many
uncertainties remain concerning lingual structure and function in many speciesof this order of mammals. One of the most remarkable features of the tongue
in Cetacea is the completely absence of lingual papillae.
We have found papilla-like projections at the anterolateral margin of the
tongue in fetal and young individuals of some species of dolphins. Growthand involution of these projections were demonstrated in the striped dolphin,
Stenella coeruleoalba. The fact that the projections appear temporarily, anddo not persist throughout life, has not been reported previously.
As shown in Fig. 1, small projections, approximately 0.5 mm in length andabout twenty in number on each side, are present at the lateral margins of theanterior one-third of the body of the tongue in a 27 cm fetus. The projections
are distinct (1 to 2 mm long) occupying the entire anterior margin of the tongue
in an 80 cm fetus. In a 98 cm fetus, they have grown longer (2 to 5 mm) andwider than those in the 80 cm fetus (Fig. 2) and some of them are subdivided
at their tips (arrows in Fig. 2). In a young Stenella (body length 150 cm),
projections have become somewhat thinner and broken, and some of them havedisappeared in the posterior part (Fig. 3). In an adult animal, several distinct
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 137-140.

138

YAMASAKI, SA TOMI AND KA:\1IY A

eminences are present near the apex of the tongue (Fig. 4). In another larger
adult one, the eminences have reduced in size and the lateral margins areslightly uneven in appearance. The entire dorsum of each tongue we observed
was quite smooth and no lingual papillae of any type were present.
Since the body length of Stenella coeriileoalba is about 100 cm at the timeof birth (Kasuya, 1972), the appearance of the tongue in the newborn animal
is probably similar to that in the 98 cm fetus we observed. Thus, it is certainthat the papillary projections in the Stenella appear during intrauterine lifeand gradually develop towards parturition. The projections may be mostnumerous and well developed in the early postnatal period and they may begin
to degenerate and disappear at about the 150 cm stage, which roughly corresponds to weaning in Stenella coeritleoalba (Kasuya, 1972). How the numberof the projections increase and how the projections disappear are interesting
points. It can be assumed that the former increase due to subdivision of the
projections that arc present in the 98 cm fetus as shown with arrows in Fig. 2,
and the latter vanish through repeated narrowings in several parts of eachprojection (arrows in Fig. 3) and finally shed off from the tongue proper.
In the adult Franciscana dolphin, Pontoporia blainvillei, no papillae were
present on the dorsum of the tongue but small eminences were observed at its
lateral margins. Distinct papillary projections (2 to 3 mm long) were foundat the anterior free margin of the tongue in a young, 98.5 cm, Pontoporia(Yamasaki, et al., 1976), and the same region was dotted with warts and fringes
in a young animal (Burmeister, 1869). The small eminences at the anterolateral
margins of the tongue of the adult Stenella and also of the adult Pontoporia
appear to be the remnants of the papillary projections seen in the young
animals. We also observed well developed projections (2 to 4 mm long) at theanterior margin of the tongue in a newborn finless porpoise, Neophocaena
phocaenoides (71.5 cm). And foliate projections (3 to 6 mm), which decrease in
their number with age, were observed in young bottlenose dolphin, Tursiopus
truncatus, and Risso's dolphins, Grampus griseus (Nakajima, et aL, 1963). Thus,
the papillary projections will be found in the fetuses and the young of someother dolphins or toothed whales. Although Anderson (1879) and Sonntag (1922)
described filiform and fungiform papillae on the tongue of Ganges dolphin,
Platanista gangetica, the dorsum of the tongues of the adults was completely
smooth and no type of lingual papillae could be observed (Arvy and Pilleri,
1970, Yamasaki, et al., 1976). As they only observed the tongue in the young
stage without observation in the adult, projections were propably described as
the lingual papillae mentioned above.
The projection is composed of a core of the lamina propria mucosa anda thick stratified squamous epithelium without taste buds. Both are continuouswith those of the tongue proper. This structure, as a whole, is similar to thatof filiform or fungiform papillae. However, the projections differ markedly
from the lingual papillae of the general mammalian tongue in that they aretemporary, localized at the anterolateral margin in a radial manner and large
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

LINGUAL PAPILLARY PROJECTION OF DOLPHIN

139

m size.

Sonntag (1922) stated that the apex of the tongue in toothed whales
may or may not have processes and warty growths, however, we suppose that
he observed the tongues in variable stages of involution of the papillary
projections. Since the projections only appear in a specific period during
life, more care is neccessary as to the estimation of the age when observing
the appearance of the cetacean tongue.
The function of the lingual papillary projections described above is notknown. Because they are well developed during the suckling period they may
have an important mechanical functions during suckling in these aquatic
mammals.
As there as yet seem to be several unclear and interesting problems
concerning the papillary projections in dolphins, further observations will bedone on the relationship between the existence of the projections and thesuckling period as well as on food habits and on the process of their development
and degeneration, macro- and microscopically. In addition, comparative
functional anatomical studies with other cetaceans will be neccessary to clarify
this problem.
ACKNOWLEDGMENTS

Greatest thanks are due to Dr. M.M. Bryden, School of Anatomy, Universityof Queensland, Australia, who gave us valuable suggestions and kindly checked
the draft. Dr. T. Mitsui, Department of Anatomy, Keio University, Dr. T.
Ogawa, Department of Medical History, Juntendo University, Dr. K. Takahashi, Department of Anatomy, Sappro Medical College, Dr. H. Ohmura,
Whales Research Institute, Dr. T. Kasuya, Ocean Research Institute, Universityof Tokyo, and Dr. R. L. Brownell Jr., Department of Vertebrate Zoology,
National Museum of Natural History, Washington, D.C. are also acknowledged
for their advice for our study.
REFERENCES
A'iDERSO'i, J., 1879. Anatomical and zoological researches: comprising on account of the zoological results of the two expeditions to Western Yunnan 1868 and 1875; and a monographof the two cetacean genera, Platanista and Orcella. Vol. 1, pp. 433-435, Quaritch, London.
ARVY, L. and G. PILLER!, 1970. The tongue of Platanista gangetica and remarks on the cetacean
tongue. In: Investigation on cetacea., Vol. II, ed. by G. Pilleri, 75-77, Berne.
BURM El STER, H., 1869. In: Descripci6n de cuatro especies de delfinides de la costa Argentina
en el Oceano Atlantico. Anal. Mus. Publico Buenos Aires., 1 : 348-445.
KASUYA, T., 1972. Growth and reproduction of Stenella caeruleoalba based on the age determination by means of dentinal growth. Sci. Rep. Whales Res. Inst., 24: 57-79.
NAKAJIMA, M., K. TAKAHASHI, M. 0GURA, and K. SAWAMURA, 1963. On the growth of infantsof the small size toothed whales. J. Jap. Assoc. Zool. Gard. Aqua. Tokyo, 5: 16-22. (in Japanesewith English summery).
SONNTAG, C. F., 1922. The comparative anatomy of the tongue of the Mammalia. VII, Cetacea,
Sirenia and Ungulata. Proc. Zool. Soc., 639-646.
YAMASAKI, F., H. SATOMI, and T. KAMIYA, 1976. The tongue of Franciscana (La Plata) dolphin,
Pontoporia blainvillei. Okajimas Fol. anat. jap., 53: 77-92.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

140

YAMASAKI, SA TOMI AND KAMIYAEXPLANATION OF PLATE I
Four stages of the growth and degeneration of the lingual papillary projections of
the striped dolphin, Stenella coeruleoalba.
Fig. I. Small projections have already appeared at the lateral margin of the anterior
part of the tongue in a 27 cm fetus.
Fig 2. Projections in a 98cm fetus are distinct and occupy the entire anterior marginof the tongue in a radial manner. Some of the projections are subdivided at theirtips (arrows). The dorsum of the tongue is concave along the long axis.
Fig. 3. In young Stene/la (150 cm), projections have become thinner and some at theposterior part have been broken and have disappeared. Note the narrowing seen
in some projections (arrows). The transverse and longitudinal incisions were madeto improve fixation.
Fig. 4. Vestigial small eminences of the projections can be seen at the margin near
the apex in an adult.

Sci. Rep. Whales Res. Inst.,

No. 28, 1976.

17
1
.
.
L
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LVS Dl.VSVWVλAN OBSERVATION OF EPIMELETIC BEHA VIOROF LAGENORHYNCUS OBLIQUIDENSTOSHIO KASUYA
Ocean Research Institute, University of Tokyo, TokyoANDNOBUYUKI MIYAZAKI
University of the Ryukyus, Naha, Okinawa

The records of the epimeletic behavior in various cetaceans are documented
in Caldwell and Caldwell (1966). On the Pacific whitesided dolphin Lagenorhynchiis obliquidens Gill 1865, he showed three cases where the behavior was
directed to wounded or captured animals of the same species, and another casewhere it was directed to the dead carcass. The present observation adds anotherexample of the latter, and will show that the behavior is common in this species.
On board of the research vessel Tanseimaru, we had a cruise (KT75-7) for
the observation of marine mammals. The cruise started at Toyama (36°46'N,
137°13'E) on 9 June 1975 and ended at Tokyo on 18 June. During the two
days' observation in the Sea of Japan, the surface water temperature was
between l 7°C and 21°C, and only two schools of L. obliquidens were observed
at 39°46'N, 139°33'E and at 41°15'N, 140°16'E. They were composed of about
30 and 10 animals respectively. In the Pacific area the species was concentrated
in the coastal waters between 38°N and 36°30'N. In the south and north of
this range, there, were observed tropical and boreal species respectively (Fig. 1).
Among many Phocoenoides observed, only one dalli-type was confirmed swimingwith 5 truei-type. The identified truei-type were 34 animals.
The sea was calm on 15 June, and at 1300 hr. a carcass of L. obliquidens
floating on the side by its own buoyancy was found. The position was 36°47'N
141°56'E. The surface water temperature at the spot was 17.9°C. When the ship
approached it to pick up, it was found that the carcass was moving rhythmically by a dorsal fin of the live animal of the same species. As the dorsal
fin of the latter was moving vigorously above and beneath the water, it wasconsidered that the animal was tossing the carcass. However, it is sure that thecarcass does not sink without this effort. When the ship came at the distanceof about 20 m, the dolphin which was larger than the carcass and probably .
an adult or subadult swam around beneath the carcass. It disappeared when
the carcass was caught by a hook and pole. Though we found only one live
dolphin near the carcass, the captain Mr. K. Ueno who stayed at a higher placeobserved two L. obliquidens of the same size swam away from the carcass. At
this spot, there was observed no other dolphins in the sight.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 141-143.

KASUY A AND MIYAZAKI

142

'
''

'?

''

L1

) 1'

3

38°N

?/
41°N

~21J

//;tGr20

JY ~

39°N

36°N

J.
/~

/li/'"~25'

v1

26'

,f
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142°E
Fig. I. Distribution of marine mammals and surface water temperature (°C) observed
from 11 June to 17 June 1975. C: fur seal, D: delphinids unidentified, G: Globicephalasp., Gr: Grampus griseus, L: Lagenorhynchus obliquidens, P: Phocoenoides, Ps : Pseudorca crassidens, X: carcass of L. obliquidens. Numerals by the species indicate the number ofindividuals, and the dotted line course passed in the night.

The dead dolphin was a young male measuring 176 cm in body length.
On the decalcified and stained tooth slide, there were observed three postnatal
dentinal layers stainable by haematoxylin. The first stainable layer was thin,and the last was wide and situated on the pulp wall. If the layer is formed
annually and the stainable layer is accumulated in the season from autumn
to spring as in the case of S. attenuata (Kasuya 1976), the age of the deadanimal can be little more than two years. There was found no external orinternal injury on the carcass. The carcass was already cold and the skin andmuscle were very fresh, but the internal organ showed a very slight smell of
decomposition. The stomach was empty. The several barnacles found at
the posterior edge of tail fluke were identified by Dr. T. Yamaguchi to be
Sci. Rep. Whales Res. Inst.,

No. 28, 1976.

EPIMELETIC BEHA VIOR OF LAGENORHYNCUS OBLIQUIDENS

143

Xenobalanus globicipites Steenstrup 1851. Possibly the dolphin died of somenatural cause in the preceding day and had been floating since the death.
Though the succorant behavior may not be rare in this species (Caldwell andCaldwell 1966), it is not known in the present case if the live dolphins were
continuously with the carcass after the death.
REFERENCESCALDWELL, M.C. and D.K. CALDWELL, 1966. Epimeletic (care-taking) behavior in cetacea.
In: Whales, Dolphins, and Porpoises (ed. K.S. Norris, Univ. of California press, 789 pp): 755789.
KASUY A, T., 1976. Reconsideration of life history parameters of the spotted and striped dolphinsbased on cementa! layers. Sci. Rep. Whales Res. Inst., 28: 73-106.

Sci. Rep. Whales Res, Inst.,
No. 28, 1976.

SQUIDS FOUND IN THE STOMACH OF SPERM WHALESIN THE NORTHWESTERN PACIFIC*T AKEHIKO KAWAKAMI
Tokai Regional Fisheries Research Laboratory, Tokyo

ABSTRACTThe squids obtained from the stomachs of sperm whales caught off
Joban, the northwestern Pacific in November, 1972 were examined.
It was found that the squids were the most important food for sperm
whales in this sea area. The species found were Moroteuthis robusta,
Gonatus sp., Gonatopsis borealis, a member of Gonatidae, Ommastrephes bartrami
and Histioteuthis dofieini.
INTRODUCTION

It is well known that squids are the important food for sperm whales, Physetercatodon (Linnaeus).
Omura (1950) and Mizue (1951) also reported that squids were the mostimportant for the food of sperm whales in the waters adjacent to Ja pan.
Ishikawa and Wakiya (1914) reported a gigantic squid, Moroteuthis robusta(Verrill), from the stomach of a sperm whale caught " in the open sea off thesouth of the strait of Tugaru" in August, 1911.
The specimens of squids in the stomachs of eight sperm whales caught in
the waters off Joban in November, 1972 were examined. Here this reportdeals with the result of identification of these specimens.
MATERIALS

The present samples were collected through the surveys carried out at thewhaling station in Ayukawa in November, 1972.
The field observations were made on all sperm whales caught, and thecontents of stomachs were classified into squids, fish and others. The observation
was made on the first stomach contents. The squids were preliminary classified
into A, B, C, D, E and F, and a part of samples were preserved in 10% formalinwater to be brought home for close examination.
The localities of the capture of the sperm whales observed are shown in
Fig. 1.
* Contribution from Tokai Reg. Fish. Res. Lab., B628.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 145-151.

146

KAWAKAMI
T41E

142E

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Fig. 1. Localities of catch of sperm whales off Joban, the northwestern Pacific.
Numerals in the figure suggest the animals given in Table !.

SYNOPSIS OF THE SPECIES IDENTIFIED
The species of squids are shown in Table I. On the basis of the samples
brought to the Whales Research Institute, each group was found to be composedof the species as follows :A: Histioteiithis dofleini (Pfeffer, 1912)
B : Moroteuthis robusta (Verrill, 1876)
Gonatidae (species is unknown)
Gonatus sp.
Gonatopsis borealis Sasaki, 1923
E : Moroteuthis robusta (Verrill, 1876)
F : Ommastrephes bartrami (Lesueur, 1821)
The exact identification for C and D could not be made, because no
specimens of these two groups were brought home. The reason why only theGroup B contained four species may be due to that they are much looked
alike each other since specimens removed from stomach are so frequently badly
mutilated and lost the characters such as hooks and suckers. Sometimes samples
are only stripped mantles without arm-head part.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

~

~

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::;..

::>::i'->'°.~~;;-"'~.......;;.

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:-·

24

8

"

"

37-16 N141-59 E

37-46 N142-52 E
Female

"
JO. 1

12.3

J0.8

JO. 9

11. 4

9.5

10.2

11.3 mBody length

"

"

"

"

"

"

.

(F)

(E)

(ABCD)

(AB)

(AB)

(AB)

(B)

Squid (A)Kind (Group)

rr

r

rrr

rrr

rr

rrr

rrr

rr

Quantity

Stomach contents

Remarks) R, rrr, rr and r indicate the relative quantity in decreasing order.
F, fff, ff and f indicate 4 grades of freshness in decreasing order.

"

"

23

7

Male

37-49 N142-36 E

.,

"

20

6

..

..

.

. ..

5

Male

Female37-24 N
142-07 E..

FemaleSex

Sperm whale

ff

ff

ff

ff

ff

fff

fff

ff

Freshness

Species of squid

Ommastrephes bartrami (Lesueur)

Moroteuthis robusta (Verrill)

Moroteuthis robusta (Verrill)

Gonatus sp.
Gonatopsis borealis Sasaki
Histioteuthis dofieini (Pfeffer)

Gonatidae (species is unknown)
Histioteuthis dofieini (Pfeffer)

M oroteuthis rob us ta (Verrill)
Histioteuthis dofieini (Pfeffer)

Moroteuthis robusta (Verrill)
Gonatopsis borealis Sasaki

Histioteuthis dofieini (Pfeffer)

SPERM WHALES OBSERVED AND THEIR STOMACH CONTENTS

37-11 N
142-05 E

"

"

"

4

"

16

"

..

..

..

37-21 N
142-04 E

Locality ofcapture14 Nov. '72

Date ofcapture

3

2

I

No.

TABLE I.

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148

KAWAKAMIOEGOPSIDA

Onychoteuthidae
Moroteuthis robusta (Verrill, 1876)
This species was found in the stomachs of four of eight sperm whales.
The specimens brought home were measured about 43.5 cm, 30 cm, 26.5 cm,
ea. 80 cm and ea. 90 cm. The last two specimens are only of very large broken
mantles like waste pieces of cloth. But, characteristic warty sculptures of theintegument showed that they belong to M. robusta.
Gonatidae
Gonatus sp.
This species was found in the stomach of only one of eight sperm whales.
The dorsal length (on only remaining portion) was measured 12 cm, but thegladius length was 16.5 cm. The specimen has very long tentacles of about
30 cm (right) and 28 cm (left) long. Both of them have a single large hookon their club. This is decidedly one of a species so far called G. fabrieii(Lichtenstein, 1818) (Plate I, fig. 1).

Gonatopsis borealis Sasaki, 1923
This species was found in the stomachs of two of eight sperm whales. The
mantle of one specimen without head and arms is about 26 cm long and has alarge rhombic fin (length: ea. 10.5 cm, width: ea. 16 cm). The posterior end of
the mantle is obtuse (Plate I, fig. 2). The mantle of the other specimen isabout 22.5 cm long and the width and the length of the fin is about 16 cm
and 8 cm respectively. The ends of the both sides of the fin are deformed
to be sharp as shown in Plate II, fig. I. The mantle and fin might haveshrinked lengthwise in formalin water. Arm formula is 3, 2, 1 · . 4. From thecharacters of general shape, skin and mantle cartilage these specimens wereidentified to be this species.
A member of Gonatidae, the species of which is unknown
A specimen of only mantle of about 14 cm long was found from the stomach
of a sperm whale. It has no fin, which seems to have been attached to theposterior part of the mantle. It has no character for identification to species,
but seeing from its shape and the feature of muscle, it seems to belong to
Gonatidae (Plate II, fig. 2).

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

SQUIDS IN THE STOMACH OF SPERM WHALES

149

Ommastrephidae
Ommastrephinae
Ommastrephes bartrami (Lesueur, 1821)
This species was found in the stomach of only one of eight sperm whales.
The specimen is lacking in head and arms. The mantles is about 40.5 cm longand has a muscular and rhomboidal fin of ea. 15.5 cm long and 25.5 cm wide
(Plate III, fig. 1). The inverted T-shaped funnel elements of the mantle-funnel
fusion are easily separated from the mantle elements. A lot of photogenic tissues
are observed in the ventral integument of the mantle.
Histioteuthidae
Histioteuthis dofieini (Pfeffer, 1912)
Nine specimens from the stomachs of four of eight sperm whales were examined,
the dorsal mantle length of which measured from about 6.5 cm to about 12 cm.
The neck is separated from the mantle. Arms have no hooks, the both sidesof the fin attached to the posterior part of the mantle are muscular and convex.
All specimens have tentacles missing. Because of numbers of photophores
over the surface of the mantle, head and arms, these specimens were easily
discriminated to belong to Histioteuthidae. The final identification to thespecies was made because of the triserial photophores on the arm IV and theshape of the funnel organs (Plate III, fig. 2).
THE OCCURRENCES OF SQUIDS

Among the sperm whales caught off J oban and Sanriku and dissected at thewhaling stations at Onagawa and Ayukawa in November, 1972, 65 whales wereobserved of their stomachs, all of which had only squids. Though the numberof samples may not be large enough for discussing the important species as foodfor sperm whales, Histioteuthis dofieini and Moroteuthis robiista might beconsidered the most important for this sea area (Table 1). The members ofHistioteuthidae have not been reported as the food for the sperm whales in
the North Pacific, but were reported numerically dominantly in the dietof sperm whales from the Azores Region (R. Clarke, 1956) and Madeira (M. R.
Clarke, 1962). The members of Onychoteuthidae have already been reported as
the most important food for sperm whales in the waters adjacent to the AleutianIslands (Okutani and Nemoto, 1964: M. robusta), off central California (Rice,
1963: M. robusta) and in the Antarctic (Korabelnikov, 1959: Onychoteuthisbanksii). The members of Gonatidae also seem to be important as the foodfor sperm whales in the waters off Joban, because Beteshava and Akimushkin(1955) and Sleptozov (1955) reported that the members of Gonatidae are the mostimportant diet of sperm whales in the Kuril waters. Okutani and Nemoto (1964)
also found considerable number of Gonatid family in the sperm whale's foodSci. Rep. Whales Res. Inst.,
No. 28, 1976.

150

KAWAKAMI

in the Bering Sea and the northern North Pacific. This time Ommastrephes
bartrami was found in the stomach of one sperm whale. It is noteworthy that
this species has not hitherto been reported as the food for sperm whales before
the present finding.
ACKNOWLEDGMENTS

My thanks are due to Dr. H. Omura, the Director of the Whales ResearchInstitute, who encouraged me to carry out this investigation, and Dr. S. Ohsumi
of Far Seas Fisheries Research Laboratory and the staffs of the Ayukawa
whaling station of Taiyo Gyogyo K. K. for their kindness of collecting thesamples. I also like to thank Dr. T. Okutani of the Tokai Regional Fisheries
Research Laboratory for his help in identifying the specimens.
REFERENCES
BETESHAVA, E. I. and I.I. AKIMUSHKIN, 1955. Food of sperm whale (P. catodon) in the Kuril
Islands. Trans. Oceanogr. Inst. Moscow, 18: 86-94 (Fide CLARKE, M. R., 1962).
CLARKE, M. R., 1962. Stomach contents of sperm whales caught off Madeira. Norsk HvalfangstTid., 51 (5) : 173-191.
CLARKE, M. R., 1966. A review of the systematics and ecology of oceanic squids. Adv. Mar.
Biol., 4: 91-300.
CLARKE, R., 1955. A giant squid swallowed by a sperm whale. Norsk Hvaljangst-Tid., 44(10):589-593.
CLARKE, R., 1956. Sperm whales of the Azores. Discovery Rep., 28: 237-298.
ISHIKAWA C. and Y. WAKIYA, 1914. Note on a gigantic squid obtained from the stomach of a
sperm whale. J. Coll. Agric. Imp. Univ., 4(7) : 435-443.
KORABELNIKOV, L. V., 1959. The diet of sperm whales in the Antarctic. Priroda, 310: 103-104.
(In Russian) (Fide CLARKE, M. R., 1962)
MATTHEWS, L.H., 1938. The sperm whale (Physeter catodon). Discovery Rep., 17: 93-168.
MIZUE, K., 1950. Food of whales in the adjacent waters of Japan. Sci. Rep. Whales Res. Inst.,
5: 81-90.
NESIS, K. N., 1971. New form of squid, Genus Histioteuthis, from the eastern Pacific. Zool. J.,
50(10): 1463-1471. (In Russian)
OKUTANI, T. and T. NEMOTO, 1964. Squids as the food of sperm whales in the Bering Sea
and Alaskan Gulf. Sci. Rep. Whales Res. Inst., 18: 111-122.
OMURA, H., 1950. Whales in the adjacent waters of Japan. Sci. Rep. Whales Res. Inst., 4: 27113.
PIKE, G. C., 1950. Stomach contents of whales caught off British Columbia. Prog. Rep. Pacific
Coast St., 83; 27-28.
RICE, D. W., 1963. Progress report on biological studies of the larger cetacea in the waters off
California. Norsk Hvalfangst-Tid., 52(7): 181-187.
SLEPTOZOV, M. M., 1955. On the biology of cephalopod molluscs of the far eastern seas andthe northwestern Pacific. Trans. Oceanolog. Inst. Moscow, 18: 69-77.
TAKI, I., 1964. On eleven new species of the Cephalopoda from Japan, including two new
genera of Octopodinae. J. Fae. Fish. Anim. Hush. Hiroshima Univ., 5(2): 277-330.
Voss, N. A., 1969. A monograph of the Cephalopoda of the North Atlantic. The family
Histioteuthidae. Bui. Mar. Sci., 19(4): 713-867.
YOUNG, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from theseas off southern Calisfornia. Smithsonian Contr. Zool., 97: 1-159.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

SQUIDS IN THE STOMACH OF SPERM WHALESEXPLANATION OF PLATESPLATE I
Fig. I.
Fig. 2.

Gonatus sp., gladius length 1.65 cm.
Gonatopsis borealis, dorsal mantle length ea. 26 cm.
PLATE II

Fig. I.
Fig. 2.

Gonatopsis borealis, dorsal mantle length ea. 22.5 cm.
A member of Gonatidae, dorsal mantle length ea. 14 cm.

Fig. I.
Fig. 2.

Ommastrephes bartrami, doral mantle length 40.5 cm.
Histioteuthis dojleini, dorsal mantle length ea. 12 cm.

PLATE III

Sei. Rep. Whales Res .Inst.,
No. 28, 1976.

151

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LIFE CYCLE OF CYAMUS SCAMMON! (AMPHIPODA:CYAMIDAE), ECTOPARASITE OF GRAY
WHALE, WITH A REMARK ON THE
ASSOCIATED SPECIESYUK M. LEUNG
Department of Biological Sciences, Universityof Southern California, Los Angeles

ABSTRACT

G_vamus scammoni, parasitic exclusively on gray whale, was studied
under the provision of special scientific permit. Its life cycle wascompleted during the journey of winter migration. C. ceti and C.
kessleri, messmates of C. scammoni, followed the same pattern in many
respects. Significantly, the whale-lice can survive out of water forseveral days though other am phi pods are poorly adapted for terrestrial
life. The cyamid causes certain damage to the cutaneous tissue of thehost when the juvenile begins its livelihood.

INTRODUCTION
The whale-louse, ectoparasite of mysticete and odontocete, has been recognizedever since Oniscus ceti of the bowhead whale recorded by Linnaeus in 1758.
Although scores of papers on taxonomy have elaborately been published, yetmany facets are still unexplored. This accounts for the fact that systematicinvestigation is not always feasible, not only because the population of thewhale species is widely distributed in different hemispheres, but the cyamids
are often discarded by the commercial whalers. Moreover, the whales arelegally protected so that collecting is no longer available.
The gray whale, Eschrichtius robustus, summers in Chukchi, Beaufort, andwestern Bering Seas for food, and in winter it migrates along the Californiancoast to the lagoons of Baja California, Mexico, for breeding and calving. As
the herd travels along a defined course in definite seasons, the life cycle of thecyamid may well be traced through a successive survey during the entire
journey. Under the provision of the specific scientific permit, the author was
privileged to participate the whaling expedition on several occasions, and visited
the shore station at intervals to collect series of samples of which the accumative data were of significance to make this study possible.
MATERIAL AND METHODThis study was based on series of Cyamus scammoni and the associatedspecies, C. ceti and C. kessleri, taken aboard the catcher boat off central CaliSci. Rep. Whales Res. Inst.,
No. 28, 1976, 153-160.

154

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LIFE HISTORY

Cy
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,i
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t
.
The brood wasapparently full‑grown insummerbefore migratings
outhwards.
and mating beg
an when itreach巴d sexual mawrit
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F
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.2
)
. An ovigerousfemalec
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ight
）× 1
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ng
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e
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as
edf
rom
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eej
uven
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l
e,measuringthe brood‑
p
oucht
o mai
n
t
ai
nl
i
f
eindependently. Th巴 f1.
0‑1
.5mm, f
as
t
e
n
e
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el
fwi
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h peaveyhook‑likeungu
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of
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k
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),o
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ongbothj
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on a
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S
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.and bifurcatewhen thetheknob‑s
haped gills began to expand and cu
young a
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henumber o
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s
to
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仁lt
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um. I
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remale
whe
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om t
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hemal
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s
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t
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s began to appear; the pai
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. Whale
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N
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8
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7
6

1
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LEUNG

.
.
、

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ig
.3
. M
i
c
r
o
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r
a
p
ho
faj
u
ve
n
il
eC. scammo11i, v
ent
r
a
lv
i
e
w,s
h
ow
i
n
gt
hek
n
o
b
‑
o
t
et
heunnamedc
h
o
n
o
t
r
i
c
h
o
u
sc
i
l
i
a
t
e
s
s
h
a
p
e
dg
i
l
l
sbe
f
o
reb
if
u
rc
a
t
i
n
g
. x45. N
i
n
f
e
s
ti
ngt
hev
e
n
t
r
als
u
r
f
a
ceo
ft
heb
o
d
y
.
geni
t
alval
v
e
s ont
h
e5
t
hs
omit
co
rt
h
e femalec
ould bet
r
a
c
e
d
. I
n Marchmo
s
t
oft
h
ei
n
d
ividualsreached maturit
y measuring 1
4‑1
8m m in male,and 10‑1
2mm in female
,t
h
eg
il
ls
,a
c
c
e
s
s
o
r
yg
i
l
l
s and the genital appendages ofthemale werefully developed; wher
e
a
st
h
eo
o
s
t
e
g
i
t
e
soft
he femalehad s
hape
dt
o
form a brood‑pouch,of whi
eh t
h
e po
s
t
er
iorp
la
t
e
sextended overt
heant
e
r
ior
ones
. Thee
l
a
b
o
r
a
t
e overlapping arrangement oft
he oo
s
t
egi
t
ess
h
e
l
t
e
r
e
dt
h
e
eggsandt
heyoungi
nt
he brood‑pouch t
hroughout t
h巴 incubationp
e
r
i
o
d
, but
S
c
i
. Re
戸 Whal
e
sRe
s.I
ns
t.
,

No.2
8
,1
9
7
6
.

LIFECYCLEOFCYAMUSSCAMMON!

57
1

.
. x25
st
eho
h
ft
lyo
ebe
h
nt
so
e
ol
ngh
i
ungC.scammo11i bor
g.4. YoiF

5i x2. scammon
ungC
y yo
db
e
lydamag
i
v
a
e
sueh
is
nt
i
k
sts
rmo
te
u
eo
. Th
.5
ig
F

cmightlema
・l‑grown. A I
ulheyoung ¥l"aS fcaly opened when t
twasautomatiidhe numberwoul.and tds
pouch homewar
he brood‑nt
0eggs i
8
3
50‑
t3
i
depos
y
l
l
u
r
s
a
w
d
o
o
r
b
e
h
t
.
y
l
a
n
i
F
.
e
m
i
t
me
o
s
r
e
t
r
a
y
t
i
c
a
p
a
c
l
u
f
s
t
i
o
et
s
ea
ncr
i
s
a
w
t
i
t,and
a
t
i
b
a
ummer hn the sle ihe whaivalor tr
he ai
loped upon t
c
・
de,
.
le
e cyc
r
i
el
h
et
et
hsto complne mont
o ni
tt
gh
t ei
tunderwentiahtimated t
s
e
.
i
r
e
l
s
s
iand C.ke
et
s.C.c
e
smat
s
sme
t
i¥¥"aS the counterpart ofinw
11. SCαniChere toched bcr
t
e ha
s wer
nce the egg
i
ier s
l
r
e ea
t matured mor
s
a
el
h
but t
.
t.
ns
s.I
s Re
e
. Whal
p
. Re
i
c
S

.
6
7
9
,1
8
No.2

158

LEUNG

F
ig
.6
. j
uv
e
nl
ie
se
m
b
e
d
d
i
n
gi
nt
hec
l
e
f
tso
ft
heendemi
cc
i
rr
i
p
e
ds
o
nt
h
es
i
d
eo
rt
h
el
o
we
rj
a
w.x2
5.
s
e
as
onalmigrat
ion began. Of3921 C
.k
e
s
s
l
e
r
it
a
ken a
tP
t
. Bar
r
o"・i
n.
J
u
ly
and August. 3534 werej
u
¥
・
e
n
i
l
e
s
.onl
y3
8
7 adults. 』¥
Ihen t
h
eh
o
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t mi
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at
c
d
so uthw~川l p
a
s
si
ng c
e
n
t
r
a
l Cal
if
o
r
n
i
ai
n midJ.anuary,someofthe femaleshadalready been d
e
p
o
s
i
ti
ng eggs inthe brood‑pouぐIi. During t
he cou
r
s
e of
r
e
t
u
r
n
i
ng northwar
di
nl
a
t
e Mar
ch,t
h
e new generationa
t
t
ai
ne
df
u
l
lmaturityasamong58f
emales examined.25 werecar
ryingeggs.1
8wit
hjuve
n
i
l
e
si
nt
he
brood‑pouch.and 1
5 havi
ng r
el
e
as
ed t
h
e
i
r young. An ovigerous C
.k
e
s
s
l
e
r
i
car
ri
ed 21
5‑300eggs.onl
y1
50‑260(about 75‑80%)were f
e
rt
i
l
iz
e
d
. wher
e
a
sC
.
c
e
t
i carried 1
54‑242 embryos. but 131
‑1
46 (about 70‑75%) were f
er
t
i
l
iz
e
d
.
Obvi
o
u
s
l
y
.t
he numberofembryosproduced isvar
ied accor
d
i
ngt
ot
hes
peci
e
s
and t
hes
i
z
eoft
he f
e
m
a
l
e
.
Ther
ei
ss
pe
eul
a
ti
on a
st
ot
he numberofi
nstar$ofC.s
cαm
,
m
,
o
n
iand t
h
e
a
s
s
o
ci
a
t
e
ds
peci
e
sast
henumberofe
c
c
l
ys
i
si
suntraceab
le. However
,i
ts
e
ems
l
ik
e
l
yt
h
a
tt
h
e
re ma
y beatl
e
a
s
ts
e
v
en o
r ei
ght s
t
a
g
e
sa
sf
a
ra
st
h
er
ange ofsizeand thedevelopment oft
he mor
p
h
o
l
o
g
icals
t
r
uct
u
re
sar
eco
ncerned. Fur‑thermore, itisprobablet
h
a
tt
h
ecycl
eov
e
r
l
a
p
sby 閃 as
on t
h
a
ts
omejuveni!
e
s
a
r
eal
wayspresent on each colony.
GENERALCONSIDERATI
ON
Des
pi
t
et
h
e cyamid belongst
othes
amegroupwi
t
ht
hecap
r
e
l
l
i
d(Cap
r
e
ll
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LIFE CYCLE OF CYAMUS SCAMMON!

159

cyamids, particularly those of infesting larger mysticetes, have rigid host specificity and site restrictiveness (Leung l 970a) as C. scammoni occurs habituallyeither on the delicate skin tissue of the belly or on the scar of the endemic
cirriped along both jaws of the whale; C. ceti, being received at the sametable occasionally with C. sca11imoni, is found generally on the creases of thelips, flippers and flukes; whereas C. kessleri localizes only on the umbilicus,
genital opening and anal aperture of the host. During the whaling seasons,nine whales had been inspected aboard the catcher boat and in the shore
station, and all animals were heavily infested with cyamids of different stages.
Among the three species, C. scammoni exceedingly predominated over theother two.
The cyamids breathe by means of gills, however, it is remarkable that they
are able to exist beyond the environmental condition. At the shore station it
was not uncommon to see the whale-lice crawling for many hours after thewhale drawn from the sea. While cruising on the catcher boat, it was curious
to observe three individuals of C. scammoni reposing on a steel cable of thewinch in the late afternoon as no whale was taken during the day. Obviously,
these individuals had survived from the catch of the previous day. Further
surprising evidence was afforded by G.]. B. Ross of the Snake Parks and Oceanarium of S. Africa (per. comm.) who reported that the cyamids could outlive
for three days on a stranded south right whale at Algoa Bay in 1971. Integumentary respiration of the whale-lice is of considerable significance, because
they were able to survive for several days divorced from the aquatic environment even though the amphipods are poorly adapted for terrestrial life.
The mouth parts of the cyamid are for piercing. There is some likelihoodthat whale-lice are omnivorous feeding on the algal filaments and the outermost layer of skin tissue of the host. However, the bill of fare seems to be
the cutaneous tissue of the host as the young customarily encases itself bypiercing the delicate skin tissue or embedding itself in the cleavages of thesessile cirriped when it begins to maintain its livelihood. Since the host provides favorable sites and adequate food supplies, opportunity of building up
large population is eminent. On the other hand, the small streamlined odontocete
furnishes neither adequate accommodation nor profuse provisions, and thesurvival rate is therefore in a reverse direction (Leung l 970b ).
Three species of cyamids occur on the gray whale. With the exceptionof C. scammoni, the systematic status of C. kessleri and C. ceti have long been
bewildered. Although C. kessleri was recorded by E. Wosnessensky in 1864
at Metschigmensky in the vicinity of the Bering Strait, yet the host had notbeen identified. It did not come to light until 1954 when Mohr (Hurley andMohr 1957) collected a few hundred individuals of this species from a graywhale killed by the Eskimos off Pt. Barrow, Alaska, and the host proper was
finally justified. C. ceti was described from the bowhead or the Greenland
right whale, but the association with the gray whale is poorly known. Since
the bowhead and the gray whale inhabit in Arctic waters, the possibility ofSci. Rep. Whales Res. Inst.,
No. 28, 1976.

160

LEUNG

accidental transfer by bodily contact is not unlikely to happen. However, it
is seemingly not the case as our colleague, Dr. F. E. Durham, a bowhead biologist, reported that he found neither C. scammoni nor C. kessleri but C. cetion the bowhead (per. comm.). For this reason, the likelihood of interchange
seems unlikely. Virtually, C. ceti is akin to C. monodontis of the narwhal
which Lutken (1873) described it as a "peculiar dwarf-form" of C. ceti. In
view of C. ceti of the gray whale, there is reason to speculate that it may fallwithin the original description from the bowhead, and a concept of specificindependent species has been conceived. Consequently, both species should bethoroughly reviewed.
There are various unnamed species of chonotrichous ciliates (Chonotricha)
infesting the ventral surface of the young cyamids (Fig. 4). It is of interest
that these collar ciliates, alike the cyamids, demonstrate an extraordinary modeof parasitism that shares on other congeners to occupy the same community,
and the occurrence of interchange is uncommon even though the messmates
are colonized at the adjoining locality. Accordingly, it is suggested that it
may be a contributing factor to identify the whale-lice and the cetaceans in
the presence of the ciliates.
Finally, the whale-lice cause certain damage to the whale skin when theyoung begin to maintain their livelihood, and the injury is a result of piercing
the tissue in which they shelter for safety and for food. As a matter of fact,
the outermost layer of whale skin is extremely thin and delicate in structure,
hence it is no wonder that the unwelcome guests frequent these haunts forliving.
ACKNOWLEDGMENT
I am grateful to Mr. Dale W. Rice and Mr. Allen A. Wolman of the National
Marine Fisheries Service for their pertinent information and facilities; to Del
Monte Fishing Co. for permission to make observation in the factory ; andparticularly to the skipper and his crew members of the catcher boat " Allen
Cody" for their full cooperation to make this study possible. The use of thelibrary and laboratory of Allan Hancock Foundation is gratefully acknowledged.
REFERENCES
HcRLEY, D. E, and J. L. MOHR, 1957. On whale-lice (Amphipoda: Cyamidae) from the California gray whale E. glaucus. ]. Parasitol., 43(3): 352-357.
LEC'W, Y. M., 1965. A collection of whale-lice (Cyamidae: Amphipoda). Bull. Soc. Calij. Acad.
Sci., 64(3): 132-143.
LEC:-IG, Y. M., 1970a. Cyamus orcini, a new species of whale-louse (Cyamidae, Amphipoda) froma killer whale. Bull. de Inst. Fundamental D'Afrique Noire, Universite de Dakar, T32, ser A, N'3:
669-675.
LEU'.'iG, Y. M., 1970 b. First record of the whale-louse genus Syncyamus (Cyamidae, Amphipoda)
from Western Mediterranean, with notes on the biology of obontocete cyamids. In: Investigation on Cetacea II. Univ. of Berne, Swirzealand, pp. 243-247.
LUTKEN, C. F., 1873. Bidrag til kundakab om arterne af slaegten Cyamus Latr. eller Hvallusene. Vidensk. Selsk. Skr., (5) 10(3) :t 229-284.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

ON THE HELMINTHUM OF FRANCISCANA,
PONTOPORJA BLAJNVJLLEJNOBORU KAGEi
Division of Parasitology, The Institute of Public Health, TokyoTERUO TOBAYAMA AND YU NAGASAKI
Kamogawa Sea World, Chiba

ABSTRACT

Three helminthes, Anisakis typica (Diesing, 1860), Procamallanus sp. andCorynosoma cetaceum Johnston and Best, 1943, were isolated from a Franciscana, Pontoporia blainvillei (Gervais, 1842); collected at Punta del diabulo, Urguay. This is the new host-record against these helminthes.
INTRODUCTION

In January 1973, many materials were obtained from the stomach of a Franciscana, Pontoporia blainvillei (Gervais, 1842), collected at Punta del diabulo,
Urguay, for scientific studies. These materials consists of two species of nematodes and one of Acanthocephala and all mounted as microscopic preparationsin glycerinejelly, lactophenol or gum-chloral after the fixation in 70% ethyl
alcohol. Further details may now be added the description of the species.

Anisakis typica (Diesing, 1860)
Materials: Thirty-one worms obtained from the second stomach of Franc1scana.
The materials consisted of 2 larvae, 10 males and 19 females (Table 1).
The worms (Photograph 1) were whitish in color, in alcohol fixation.
TABLE 1.

COLLECTION RECORDS OF HELMINTHES IN THE STOMACH OF
FRANCISCAN A PONTOPORIA BLAINVILLEI (GERVAIS, 1842)

Species of Parasites

Sex

No. Vv orms recovered

Anisakis typica

LarvaeMale
Female10
19

Procamallanus sp.

Female2

2 nd stomach

Corynosoma cetaceum

Male
FemaleIll99

3rd and 4th
stomachSci. Rep. Whales Res. Inst.,
No. 28, 1976, 161-166.

Habitat2
2 nd stomach

162

KAGEI, TOBA YAMA AND NAGASAKI

Description: Anisakinae, Nematoda. Three lips each bearing a bilobed
anterior projection which carries the single dentigerous ridges (arrow at Photograph 2); inter labia absent; lateral cervical alae absent; cervical papillae bear
the nerve-ring. Body attenuate more toward anterior than toward posterior
extremity, which ends conically. Cuticle with cuticular striations 19-59µ broad.
Excretory gland with duct opening between ventro-lateral lips; oesophagus composed of two portion; anterior muscular portion (M. at Photograph 3) and posterior ventriculus (V. at Photograph 3), the latter being oblong and somewhat
sigmoid or else as broad as long ; no ventricular appendix or intestinal caecum.
Male: 28.3 to 56.4 mm in length by 0.60 to 1.39 mm in breadth; anterior
muscular portion 2.28-3.62 mm in length at the body length 28.3-47.0 mm, ventriculus 0.90-1.50 mm in length ; tail (0.16-0.26 mm in length. Photograph 4)compressed dorso-ventrally with dorsal median rounded keel and with lateralalae. It is curved ventrally and bears numerous papillae; 10 pairs of postanal
papillae without doublepapilla, of which I, 2 and 3 are conical and near thetip; 4 to 10 shorter and near the cloaca; spicules unequal, the right spicules(R. of Photograph 5) measured 0.94 mm while the left (L. of Photograph 5)
measured 2.86 mm at the worm of body length 46.0 mm (ratio, I : 3.04).
Female: 21.7 to 90.8 mm in length by 0.56 to 2.00 mm in breadth; vulva
in 10.2-11.3 mm (46.3-47.0.%) from anterior extremity of body. Anterior muscular portion 1.98-3.52 mm; Ventriculus 0.56-1.20 mm at female of body length21.7-42.4 mm. Tail length 0.14-0.30 mm (Photograph 6).
Larva: 25.4 and 25.8 mm in length and 0.56 and 0.57 mm in breadth, withlength muscular region of esophagus of 1.96 and 2.02 mm, ventricular length of
0.84 and 0.83 mm (Photograph 8) and tail length of 0.08 and 0.12 mm (Photograph 9). The larvae had the characteristic boring tooth on their lip mass
(Photograph 7 and 10), and the one-shaped cuticular mucron on their tail end,
and their long ventriculi were connected with their intestines obliquly. Therefore, the authors consider that these larvae belong to the Type-I larva of
Anisakis described by Berland (1961).
Discussion: Examination of the material detailed above shows that thisspecies is characterized by the very marked unequality of the spicules (1 : 3).
This range is clearly distinct from that found for A. simplex (1 : 1.6).
The postanal papillae are also different from A. simplex (A. typica 10 pairs;
A. simplex 6 pairs with one double papilla).
It is interesting that Davey (1971) described that although A. simplex distributed on the wordwide, but more particularly in colder temperature andpolar water, A. typica found on warmer temperature and tropical waters between 40°N and 36°S.
A. typica were recorded only from cetaceans of the families Stenidae, Delphinidae and Phocaenidae. Accordingly, this host (Pontoporia blainvillei;
Platanistidae) is the new record against A. typica.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

HELMINTHUM OF FRANCISCANA

163

Procamallanus sp.
Materials: Two females were obtained from the second stomach of aFranciscana.
Description: Camalanidae; Spiruroidea; Nematoda. The materials consisted one mature and one immature female (Table 1 and Photograph 11 ). The
worms whitish in collor, in alcohol fixation. Body slender; attenuated towards
both extremities. The materials are in length from 29.1 mm and 41.7 mm, andin breadth from 0.31 mm and 0.54 mm. The cuticule thick, and finely striatedtransversely. The anterior end without lip bears 6 papillae-2 lateral and 4
median. The brownish-yellow buccal capsule (Photograph 13) is broadly barrelshaped, and its anterior opening is hexagonal. It is in length 0.10 mm and 0.12mm, and in breadth 0.08 mm and 0.09 mm. The internal surface of the wallof buccal capsule is probided with ridge like thicknings, numbering 12-13, which
traverse it in a spiral fashion. The esophagus is divided into the two parts.
The anterior muscular portion is club-shaped and measured 0.65 mm and 0.66
mm in length by 0.12 and 0.14 mm in maximum width. The posterior glandular portion measures 0.95 mm and 1.05 mm in length, and unlike the muscularpart, has a uniform breadth. The intestine was conspicuous on account of its
being full of partly difested blood. The nerve ring encircles at narrowest pointof the muscular esophagus, 0.36 mm from the anterior end. Excretory pore
situated in the region of the nerve ring and a short distance from anterior tojunction of muscular :md glandular portion of esophagus.
Posterior extremity is bluntly rounded; it has length 0.12 mm. Numerous
conspicuous muscle strands extend across body cavity region of anus. Tail
(Photograph 12) terminates in a small conical tip, 0.05 mm long, at extremityof which are two extremely minute spinal projections, apparent only under thehigher magnification.
The vulva is situated on the middle of body (14.5 and 19.4 mm; 46.5 and49.8.% from the anterior part). Eggs were seen in the uteri, which contained
a larva.
Discilssion: Up to the present, 40 species of Procamallanus have beenrecorded, all of which, exception of the batrachian parasites, P. xenopodia andP. slomei, are intestinal parasites of marine and freshwater fishes, and 11 species
posses the spiral thicknings in the inner surface of the wall of buccal capsule,viz., P. spiral, P. amarali, P. hilarii, P. hanoslimai, P. fariasi, P. f ulvidraconi,P. wrightii, P. monotazis, P. murrayensis, P. pereirai and P. globoconchus.
Five species, P. amarali, P. hilarii, P. barroslimai, P. wrightii and P. feriasi,
in these species were reported from fishees from Brazil. However, they differs
our species in the following points.
The main points of difference are in the length of posterior glandural esophagus (P. soiral and P. hilarii) and in the tail of female. In our species thetail of the female appears to have a process with two spines; in other species
Sci. Rep. Whales Res. Inst.,
No. 28, l!J76.

164

KAGEI, TOBAYAMA AND NAGASAKI

there are not spine.
The species resembles P. montaeis in some features, but differs in the formof the buccal capsule, which is more spherical.
The present species could not identified, because of not-finding the male.
I (N.K.) think that these dolphin is not the definitive host of these worms.

Corynosoma cetaceum Johnston and Best, 1943
Materials: Two hundred-ten worms obtained from the third and fourth
stomach of a Franciscana (Table 1). The materials consisted of 111 males and
99 females. The worms (Photograph 14 and 15; scale is mm.) were witish-yellow
in coll or, in alcohol fixation. They have been preserved in fixative for manydays. Observations were based on whole mount with gum-chloral.
Description: Corynosomatinae; Acanthocephala. In body from there isdistinct sexual dimorphism (Male: Photograph 14; Female: Photograph 15).
Anterior part of trunk bulbously swollen and spined, and in male tapered
towared posterior extremity which is about two-third to three-fifth of the bodylength (Photograph 16), with extro-atached bursa (0.93-l.40mm by l.OO-l.25mm.
Photograph 23) having the many sucker-like projections in the inner surfaceof the wall (Photograph 24) ; female more roundish than male, pouchlike, withsmall attenuated posterior extremity (Photograph 17). Male very in length from
7.15 mm to 9.25 mm, and in width from 2.35 mm to 2.80 mm. Female in lengthfrom 3.90 mm to 4.65 mm, and in width from 2.50 mm to 2.70 mm; maximum
width at level of anterior trunk.
Trunk spines (Photograph 20 and 21) of female extending almost entire
length of the body ventrally but dorsally reaching only the region of maximum
diameter; in males the spines extend along ventral surface to point only a shortdistance posterior to the hind margin the cement glands, much of hind-trunk
devoid of spines (Photograph 22). Trunk spines usually 22.8µ to 65.4µ longin males. Genital spines lacking in males.
Proboscis (Photograph 18) of both sexes arising from discoid swelling oftrunk and bent ventrally, cylindrical, 0.80-1.13 mm length; maximum width atlowere third of proboscis (0.30-0.40 mm).
Proboscis hooks, sickle-shape, arranged in 18-19 longitudinal rows with 1213 in each row, becoming grandually stouter (70.0-75.1µ) from apex toward
swallen region, than abruptly small. Hooks nearest to base of proboscis smallest
in size (30.6-35.8µ).
Proboscis receptacle double-walled, slightly longer than proboscis (1.55-1. 75
mm by 0.40-0.53 mm) (Photograph 19).
Lemnisci sqmewhat shorter than proboscis receptacle, leaf-shaped.
Testes elliptical, 0.93-1.40 mm by 1.00-1.25 mm, lying symmetrically tothe posterior region of the for-trunk, reaching anteriorly to the level of theposterior and of the proboscis receptacle.
Six cement glands, immediately posterior to testes, in two groups of theseSci. Rep. Whales Res. Inst.,
No. 28, 1976.

HELMINTHUM OF FRANCISCANA

165

each.
Egg fusiform with polar prolongations of middle shell; 154.8 (136.6-163.5) µlength and 46.1 (42.6-51.5) µ width (Photograph 25).
Discussion: Although Corynosoma had reported 22 species from marine
mammals, the present species, except for C. cetaceum, differs from these species
in size of the body, number of hooks at the proboscis and size of the eggs.
Morphorogical features and the measurements agreed well with the description of C. cetacum Johnston and Best, 1943 from Delphinus delphis and Tursiops truncatus. Accordingly, although Corynosoma sp. had been reported by
Dailey and Brownell (1972) from Franciscama, Pontoporia blainvillei, C. cetaceum
was first record from the precent host.
ACKNOWLEDG MENTS
We wish to express our hearty thanks to Dr. Masaharu Nishiwaki of the Ocean
Research Institute, University of Tokyo, as the leader of Japanese Scientific
Research Expedition against the Franciscana.
REFERENCES
ANNEREAUX, R. F., 1946. A new nematode, Procamallanus pereirai, with a key to the genus.
Trans. Am. Micro. Soc., LXV: 299-303.
BAYLIS, H. A., 1923a. Report on a collection of Parasitic nematodes, mainly from Egypt. Pt.
II. Camallanidae, etc. with a note on Probstmayria and an appendix on Acanthocephala.
Parasit., 15(2): 24-28.
BAYLIS, H. A., 1923b. Notes on Procamallanus spiralis Baylis, 1923 (Nematoda). Parasit., 15(2):137-138.
BERLAND, B., 1961. Nematodes from some Norwegian Marine fishes. Sarsia., 15: 1-50.
BULLOCH, W. L., 1958. Histochemical studies on the Acanthocephala. III. Exper. Parasit., 7(1):51-58.
CRUSZ, H., 1946. Contributions to the Helminthology of Ceylon. II. Notes on some parasitic
nematodes, with a description of Anisakis tursiopis sp. nov. Ceylon J. Sciens. Sect. B. zoology.,
23. Part 2: 57-66.
DAILEY, M. D. and R. L. BROWNEL 1972. A checklist of marine mammal parasites. Mammalsof the sea Biology and Medicine. edited by S. H. Ridgway. Charles C. Thomas.
DAVEY, .J. T., 1971. A revision of the genus Anisakis Dujardin, 1845 (Nematoda: Ascaridata).
]. Helminthology., XLV(l): 51-72.
DELYA;\!URE, S. L., 1968. Helminthofauna of marine Mammals (Ecology and phylogeny).
Jerusalem., pp. 522.
GOLVAN, Y. J., 1959. Acanthocephalus du Corynosoma Luhne, 1904, parasites de mammiferesd' Alaska et de Midway. Ann. Para., 34(3): 288-321.
HEil'iZE, K., 1934. Ein neuer Acanthocephala . (Rhadinorhynchus meJ•eri n. sp.) sus de, Zoo!.
Museum zu Griefsgald. Zoo!. Anz., 108: 255-256 .
.JOHNSTON, T. H. and E.W., DELAND, 1930. Australian Acanthocephala. Nors. I. and 2.
Austr. Sc. Abstr. Sidney. (9). p. 21; Tr. Proc. Roy. Soc. South Aust. Adelaide. 53: 146-166 .
.JOHNSTON, T. H. and P. MAWSON, 1940. Some nematodes paaasitic Australian freshwater fish.
Trans. Roy. Soc. South Australian., 64(2) : 340-352 .
.JOHNSTON, T. H. and E.W. D. BEST, 1943. Australian Acanthocephala. No. 3. Tr. Roy. Soc.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

166

KAGEI, TOBAYAMA AND NAGASAKISouth Australia, 66(2): (1942), 250-254.
LEIDY, J., 1886. Notes ef nematoid worms. Proc. Acad. Nat. Sci. Philadelphia, (3)16: 308-316.
LI, H. C., 1935. The taxonomy and early development of Procamallanus fulvidraconis n. sp. ].
Parasit., 21 : 103-113.
LINCICOME, D.R., 1943. Observations of the adult of Erhynthmorhynchus duocinctus Chandler,
1935 (Polymorphidae, Acanthocephalidae). Tr. Am. Micro. Soc. 63(1): 69-71.
MARGOLIS, L., 1955. Corynosoma hadweni van Cleave a probable synonym of C. wegeneri Heinze(Acanthocephala). ]. Parasit. 41(3): 326-327.
MONTREUIL, P. L., 1958. Corynosoma magdaleni sp. nov. (Acanthocephala) a parasite of the grayseal in Eastern Canada. Canadian ]. Zool., 36: 295-315.
OLSEN, L. S., 1952. Some Nematodes parasitic in marine fishes. Public Inst. Marine Sci. Univ.
Texas, 11(2): 173-215.
SAHAY, U., 1966. On a new key of the genus Procamallanus with a historical review. Japan.].
Med. Sci. Biol., 19: 165-170.
STILES, CH. W. and A. HASSAL, 1899. VII. Internal parasites of the fur seal. The Fur Seals
and Fur Seal Islands of the North Paciffc Ocean. Part 3: 99-177.
VAN CLEAVE, H.J., 1953. A preliminary analysis of the Acanthocephala genus Corynosoma in
mammals of north America. ]. Parasit., 39(1): 1-13.
YAMAGUTI, S., 1961. Systema Helminthum. Vol. Ill. Nematoda. New York.
YAMAGUTI, S., 1963. Systema Helminthum. Vol. V. Acanthocephala. London. pp. 423.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

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FATTY ACID COMPONENT OF LIPID
OF EUPHAUSIA SUPERBAHIDEO TSUYUKI
ANDSHINGO ITOH
Department of Food Technology, College of Agriculture andVeterinary Medicine, Nihon University, Tokyo

ABSTRACT

Lipids extracted from the raw frozen and boiled-frozen krill, Euphausia
superba, harvested in the Antarctic Ocean were identified and quantitatedby a combination of thin-layer and gas-liquid chromatography.
The lipid contents of E. superba on the wet weight basis were 3.41%of the raw frozen sample and 5.62% of the boiled-frozen sample. There
were shown to consist of 0.8% of steryl esters, 27.4% of free fatty acids,
52.3% of triglycerides, 4.7% of sterols, a trace amount of diglycerides,
2.2% of monoglycerides, 6.9% of phospholipids and 4.1% of pigments in
the raw frozen sample, and 0.6% of steryl esters, 4.6% of free fatty
acids, 76.8% of triglycerides, 4.2% of sterols, 9.2% of phospholipids and3.5% of pigments in the boiled-frozen sample. The predominant fatty
acids contained in total lipids and the fractions of free fatty acids,
triglycerides and phospholipids were myristic (5.98-22.16%), palmitic(16.83-30.49%), palmitoleic (5.92-26.31 %), oleic (19.31-29.17%), eicosapentaenoic (0.52-12.59%) and docosatrienoic (0.50-11.74%) acids.
INTRODUCTION

Euphausia superba is a shrimp-like crustacean of about 5 cm in body length,
and inhabits only in the Antarctic Ocean, though many euphausiid species arefound widely over the world oceans. E. superba composes one of the mostimportant prey organisms for the inhabitants in the oceanic regions of the
Antarctic ecosystem. In addition to utilization by the faunistic inhabitants
there, E. superba should be regarded as the food resources for mankind in the
future. The present study stands on such viewpoint, and intends to give abasic knowledge for utilizing E. superba as to be a possible humans' food.
There have been several reports on the chemical properties and the fatty
acid composition of E. superba lipids (Saiki and Mori, 1953; Saiki et al., 1959;
Tsuyuki et al., 1964a and b). So far as these works were carried out by thefractional distillation method, the minute examinations of the fatty acidcomponent have not been reported yet.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 167-174.

168

TSUYUKI AND ITOH

On the other hand, Kayama and Nakagawa (1975), and Kayama and Ikeda(1975) reported on the lipids of some micronektonic shrimps.
The objective of this study is to identify and quantitate the lipids and thefatty acid components of E. superba by a combination of thin-layer and gasliquid chromatography.
MATERIALS AND METHODS

Euphausia superba, used in this study were harvested in the waters off Enderby
Land, 10°E in the Antarctic Ocean between December, 1974 and February, 1975
by a expedition of commercial basis Nippon Suisan Co. Ltd. A part of theE. superba harvested was quickly frozen as the raw frozen products andanother part of them was similarly quick frozen as the boiled-frozen products
after flash boiling. Both products were processed as the whole body of E.
superba. They were in the range from 0.4 to 0.7 g in the body weight and in
the range from 3.5 to 5.5 cm in the body length.
The method of Bligh and Dyer (1959) was used to extract and purify thelipids in these samples. The extracted lipids were then weighed and stored at- 20°C under nitrogen atmosphere. The chemical properties of the extracted
lipids were examined by ordinary methods.
The fractionation of E. superba lipids was subsequently separated by thinlayer chromatography using 20x 20 cm glass plates coated with activated Silica
gel G (Merck Chemical Co.). The solvent systems used were petroleum ether:diethyl ether: acetic acid, 85: 15: 1, v/v/v. The pure standards e. g. phospholipids, cholesterol, steryl palmitate, mono, di, triglycerides, oleic acid (Nihon
Chromato Works Ltd.) were used to identify zones on the thin-layer plates
which were removed, dried, sprayed with 50% sulfuric acid and charred at
ll0°C for 15 min. The fractionated zones were scraped into Toyo filter paper
No. 2 cones (Toyo Roshi Kaisha Ltd.) and eluted with chloroform respectively.
The eluting solvents were evaporated off with a stream of nitrogen and weighed.
The three major fractions were recovered triglycerides, free fatty acids andphospholipids for analyzed the fatty acid components. The other minor fractions
were noted on the plates but were not in sufficient quantity to be recovered.
The fatty acid methyl esters from total lipids, triglycerides, free fatty acids
and phospholipids of E. siiperba lipids esterified by the saponification-transesterification method as described by Metcalfe et al. (1966). 5 ml of a 0.5 N
methanolic KOH solution were added to approximately 30 mg of total lipids,
triglycerides, free fatty acids and phospholipids, and heated over a steam bathfor 5 min. Then, 5 ml of 12.5% boron trifluoride in methanol were added tothese mixtures and boiled for 3 min. Thin-layer chromatography was used todetermine the completeness of the transesterification. Silica gel G plates werespotted with the reacted products and known standards, and developped withpetroleum ether: diethyl ether: acetic acid as previously described. A comparison of the R 1 values of the reacted products, triolein, methyl oleate andSci. Rep. Whales Res. Inst.,
No. 28, 1976.

169

LIPID OF EUPHAUSIA SUPERBA

oleic acid (Nihon Chromato Works Ltd.) indicated that the conversion of total
lipids, triglycerides, free fatty acids and phospholipids fractions to methyl esters
was complete.
The methy 1 esters were analyzed weth a Shimadzu Gas Chromatograph
Model SA (Shimadzu Seisakusho Co.) equipped with a dual flame ionization
detector. The columns used were 3 m X 3.0 mm I. D. glass coil tubing packed
with Diasolid ZF on 80/100 mesh, and with 3% SE-30 on 80/100 mesh Chromosorb W (Nihon Chromato Works Ltd.). The carrier gas was nitrogen at flowrate of 40 ml per min. The column were operated isothermally at 185°C for
Diasolid ZF and 225°C for SE-30. The injector block and detector were at
215°C for Diasolid ZF and 245°C for SE-30, respectively.
Some of the gas-liquid chromatographic peaks were identified by comparison
with standard peaks obtained from pure methyl ester mixture (Nihon Chromato
Works Ltd.). Also, equivalent chain-length values were determined according
to the method of Miwa (1963) and were compared with those reported by
Hofstetter et al. (1965) for identifying peaks for which no pure methyl esters
were available. A portion of each sample esterified was hydrogenated to confirm the correctness of identification of the unsaturated acids. Approximately
20 mg of methyl esters, 1 ml of methanol and a pinch of platinum black wereadded to a screw cap vial. Hydrogen was bubbled in for 5 min, the vial sealed
and then reacted for 15 min with frequent shaking. After reaction, the methyl
esters were transferred to n-hexane, dried, then taken up and injected into thegas-liquid chromatograph with the same condition as above mentioned. The
area of each chromatographic peak representing a fatty acid present was obtained by multiplication of the height of each peak by the width at halfheight. The areas of each peak was then compared with the total combined
area at all of the peaks to obtained the percentage of each specific fatty acid.
RESULTS AND DISCUSSION

The chemical properties of the total lipids extracted from Euphausia superba
are shown in Table 1. The lipid contents are comparatively low i. e., 3.41 %of the raw frozen sample and 5.62% of the boiled-frozen sample on the wet
TABLE I.

PROPERTIES OF TOTAL LIPIDS FROM EUPHAUSIA SUPERBA
LipidsAppearance (20°C)
Oil content (%)
Refractive index (40°C)
Acid value
Iodine value
Saponification value
Unsaponifiables (%)

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

Raw frozen sample
Reddish brown liquid

Boiled-frozen sample
Reddish brown liquid

3.41

5.62

I. 4788
74. I

142.3
181. 3
5.6

I. 4820

18.2
127.9
197.6
5.8

170

TSUYUKI AND ITOH

weight basis. The total lipid of the raw frozen sample was higher in iodine
and acid values, and lower in saponification value than those of the boiled-frozen
sample. These are seemed to be autoxidized during frozen storage or thawing.
The lipid composition of each extract as determined by thin-layer chromatography is markedly different between the samples of the raw frozen and boiledfrozen. By visual evaluation of these chromatograph as shown in Fig. 1, thezones of steryl esters, triglycerides, free fatty acids, monoglycerides, sterols,
diglycerides, phospholipids and pigments are appearently present in the raw
frozen sample while the boiled-frozen sample is not found the presence of
diglycerides and monoglycerides. There are also appearent differences in thecompositions of triglycerides and free fatty acids between two samples. The
lipid compositions of these fractions are reported in Table 2. In the extractsof the boiled-frozen sample, triglycerides are the preponderant fraction comprising 76.8% of the total lipid fractions, whereas in the raw frozen sample,
triglycerides fraction is much lower. On the other hand, the composition offree fatty acids fraction is much higher in the raw frozen sample than in the
boiled-frozen sample. These appearently explained to the difference of acidvalue in Table I. Also, the raw frozen sample had '.?.2% of monoglycerides- Front

SE

TG

Ill

FFAlll
p
DG

s
p

MG
PL

--• • •
.....

·(;

'···

0

~:::-

.
0

s

p

..PL

A

e Strong

(;

~:·>

:·:.~

~:~

-::::

--• • •TG ' '
FFAO
0 '
0
p

• • - Origin
0{~:-• • •B

O MediumC":·....··

Weak

Fig. 1. Thin-layer chromatograms of total lipids extracted from E. superba. A:
the raw frozen sample. B: the boiled-frozen sample. SE: steryl esters. TG:
triglycerides. FFA: free fatty acids. P: pigments. DG: diglycerides. S: sterols,
MG: monoglycerides. PL: phospholipids.
Sci, Rep. Whales Res. Inst.,
No. 28, 1976.

LIPID OF EUPHAUSIA SUPERBA

171

and a trace of diglycerides fractions while the boiled-frozen sample was notdetected them.
The fatty acid methyl esters of the total lipids and the main three fractions
contained fatty acids i. e., triglycerides, free fatty acids and phospholipids wereanalyzed by gas-liquid chromatography, but no attempt was made to further
study the component of other fractions. The presence of the fatty acids contained in E. superba lipid is a very wide variety as reported in Table 3, plus
trace quantities of unidentified fatty acid methyl esters. With a few exceptions,the fatty acids of the total lipids and the three main fractions in both samples
had nearly similar chromatographic patterns and distributions with each other.
The major fatty acid compositions of both total lipids were 14: 0, 16: 0, 16:
1, 18: 1, 20: 5 and 22: 3 acids and contained more than 87% of the total fatty
acids. Both triglyceride fractions contained 14: 0, 16: 0, 16: 1 and 18: 1 acids
as the predominate fatty acids whereas were not detected the fatty acids of 22:
5, 22 : 6 and 24: 1 which contained in the total lipids. The total compositionof 14: 0, 16: 0, 16: 1 and 18: 1 acids accounted for more than 85% of thetotal fatty acids. The free fatty acid fractions of both samples were mainly
consisted of 14: 0, 16: 0, 16: 1, 18: 1, 20: 5 and 22: 3 acids similar to thetotal lipids. The total composition of the six main fatty acids were more than
77 % of the total fatty acids. The fatty acids of 22 : 5 and 22 : 6 which contained in the total lipids were not found in this fraction of the boiled-frozen
sample. In both phospholipid fractions, the fatty acids of 14 : 0, 16 : 0, 16: 1,
18: I and 20: 5 as the predominant fatty acids comprised approximately 76%of the total fatty acids.
The compositions of the total saturated acids in the raw frozen sample
were 39.96% of the total lipids, 56.17 % of the triglyceride fraction, 37.96% of
the free fatty acid fraction and 27.14% of the phospholipid fraction, and thoseof unsaturated acids were 58.95%, 42.83% 60.84% and 71.56% respectively. On
the other hand, those of the total saturated acids in the boiled-frozen sample
TABLE 2.

LIPID COMPOSITION OF EUPHAUSIA SUPERBABY THIN-LAYER CHROMATOGRAPHY.
LipidsComposition
Trigl ycerides
Digl ycerides

Raw frozen sample (%)

Boiled-frozen sample (%)

52.3

76. 8

trace

Monogl ycerides

2.2

Free fatty acids
Phospholipids
Sterols

27.4
6.9
4. 7

4.6
9.2
4.2

Stery 1 esters
Pigments

0.8

0.6

4. 1

3.5

Unknowns

I. 6

I. I

Sci. Rep. Whales Res. Inst ..
No. 28, 1976.

TSUYUKI AND !TOH

172

TABLE 3.

FATTY ACID COMPOSITION OF EUPHAUSIA SUPERBA LIPIDS.
(percentage of total Ii pids)
Lipids in raw frozen sample

Fatty
acids

12: 0
12: I
13 :0
lso-14: 0

14: 0
14: I
lso-15:0

15: 0
15: I
lso-16: 0
16: 0

16: I
16: 2
lso-17: 0

17: 0
17: I
lso-!8: 0
I8: 0
18: I
18: 2
18: 3
19: 0

20: 0
20: I
20: 2
20: 3
20: 4
20: 5
21:0
22: I

22: 2
22: 3
22: 5
22: 6

24: I

Lipids in boiled-frozen sample

Total
lipidsTriglycerides

Free
fatty
acids

Phospholipids

Total
lipidsTriglycerides

Free
fatty
acids

Phospholipids

0.21
0.02
0.05
0.01
8. 71
0. 14
0.07
0.37
0.06
0.04
28.94
5.92
0. 14
0.02
0.69
0.09
0.04
0.40
19.84
2. 79
0. 12
0. 15
0.10
I. 02
0.28
I. 45
0.94
12.59
0.21
0.34
0.56
11.29
0.48
0.67
0.37

0.27
0.05
0.08
0.03
22. 16
0. 15
0.05
0.84
0. 13

0.16
0.02
0.03
0.01
9.07
0. 13
0.03
0.52
0.07
0.04
26.01
7.96
0. 71
0.01
0.57
0.07
0.04
0.96
29. 17
3.47
0.80
0. 20
0. 13
0.52
0. 12
0.95
I. 15
7.04
0. 18
0.92
0.31
6.89
0.13
0. 13
0.27

0.54
0.03
0.08
0.04
5.98
0.10
0.01
0.46
0. 15
0. 12
16.83
26.31
0.58
0.01
0.88
0.06
0.01
I. 78
28.49
2.53
0.54
0.07
0.20
0.52
0.47
0.83
0.47
6.59
0. 13
0.43
0.25
2.66
0.33

0.22
0.05
0.07
0.02
11. 54
0.09
0.08
0.59
0. 12
0.05
29.20
6.27
0.25
0.02
0.64
0.09
0.07
0. 78
19.31
2.43
0.06
0. 16
0.04
0.65
0.24
0.82
0.55
IO. 96
0.07
0.41
0.30
11. 74
0.23
0.41
0.36

0. 32
0.01
0.11
0.02
21. 35
0. 15
0.04
0. 73
0.10
0.06
24.04
13.37
0.83
0.03
0.68
0.06
0.05
I. 02
25.87
2.03
0.49
0. 13
0.55
I. 47
0. 74
0.60
0.87
I. 40
0.10
0.11
0.07
I. 20

0.47
0.03
0.09
0.02
8.66
0. 19
0.04
0.33
0.09
0.06
24.82
6.49
0.41
0.02
0. 73
0.11
0.02
I. 60
21. 82
3.03

0.85
0.12
0.19
0.19
9.62
0. 24
0.06
I. 08

0. IO

30.49
8.86
0.53
0.02
0.55
0. 17
0.05
I. 18
28.25
I. 87
0. 12
0.20
0.09
0. 76
0.13
0.35
0.26
0.52
0.06
0.08
0.10
0.50

0.22

4. IO

0.39
0.24
0. 77

I. 46
4.61
I. 64
8.84
0.22
0.51
0.06
6.38

0.59

0.28
0. 12

25.22
9.53
0.45
0.02
0.90
0. IO

0.09
4.52
26.24
2.42
0.41
0. 11

0. 15
0.53
I. 37
0.29
0.63
6. 12
0. 12
0.37
0.53
4. 12
0. 12
0. 78

were 43.60%, 49.20%, 38.71 % and 43.28% respectively, and 55.34%, 49.40%,
61.19% and 55.69% in the total unsaturated acids of them, respectively. Amongthe saturated acids, 14 : 0 and 16 : 0 acids were the most constituents in theSci. Rep. Whales Res. Inst.,
No. 28, 1976.

LIPID OF EUPHAUSIA SUPERBA

173

total lipids and all fractions of both sample lipids. Although the fatty acids of
16: 1; 18: 1, 20: 5 and 22: 3 among the unsaturated acids were the main constituents in the total lipids, free fatty acid and phospholipid fractions of both
samples, these were the least of amount in both triglyceride fractions. The
most pronounced difference between the trigylceride fractions and other lipids
was in the higher level of 14 : 0 acid and the lower level of the fatty acids morethan 20 carbon atoms. Moreover, the phospholipid fraction of the raw frozen
sample contained very higher level (26.31%) of 16: 1 acid as compared to oneof other lipids whereas 14: 0 acid comprised slightly lower level of 5.98%.
The fatty acids of 18: 3 (4.10%) and 20: 3 (4.61%) in the free fatty acid fraction
and 18: 0 acid (4.52%) in the phospholipid fraction of the boiled-frozen sample
were slightly higher levels compared to others. Finally, there were little differences in the fatty acid compositions and distribution patterns of both samples
except of the phospholipid fraction in the raw frozen sample.
Saiki et al. (1959) reported that the fatty acid composition of E. superba
lipid were 16.0% of 14, 33.0% of 16, 36.1% of 18 and 13.6% of 20 carbon
fatty acids. Also, Tsuyuki et al. (l 964a) reported that these were 6.2% of 14,
25.9% of 16, 35.2% of 18, 24.5% of 20 and 8.2% of 22 carbon fatty acids. We
have found that these were 8.86-11.65% of 14, 35.04-35.77% of 16, 22.65-23.19%
of 18, 13.26-16.38% of 20 and 13.09-13.34% of 22 carbon fatty acids in both
total lipids.
Although the fatty acid components analyzed by gas-liquid chromatography
between the raw frozen and boiled-frozen euphausiacea lipids was very low
difference, the total lipid thin-layer chromatograms indicated that the free fatty
acid fractions had appearently greater difference with each other. The results
obtained with the free fatty acid fractions fractionated by thin-layer chromatography in this study indicated that the boiling procedure supported considerably
in the maintenance of the E. siiperba lipid quality during handling andfrozen storage.
ACKNOWLEDG MENTS

Euphausiacea examined in this study was collected through the courtesy of
Nippon Suisan Kabushiki Kaisha Ltd. In particularly, we are much indebted
to Mr. Masahiro Makuta who is a member of the Central Research Laboratoryof Nippon Suisan. We also thank to Prof. Dr. Sadami Kadota, the Faculityof Fisheries, College of Agriculture & Veterinary Medicine, Nihon University,
for identifying the material, Eiiphausia superba.
SUMMARY

1. The chemical properties of lipid contained m Eiiphausia superba,
were studied.
2. The lipid fractions of the euphausiacea were quantitated by thin-layer
chromatography.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

174

TSUYUKI AND !TOH

3. The main lipid compositions were triglycerides, phospholipids and freefatty acids fractions.
4. The component fatty acids of the total lipids and each fraction fractionated by thin-layer chromatography were analyzed by gas-liquid chromatography.
5. The predominant fatty acids were myristic, palmitic, palmitoleic, oleic,eicosapentaenoic and docosatrienoic acids.

REFERENCESBLIGH, E. G. and W. J. DYER, 1959. A rapid method of total lipid extraction and purification.
Can.]. Biochem. Physiol., 37: 911-917.
HOFSTETTER, H. H., N. SEN and R. T. HOLMAN, 1965. Characterization of unsaturated fatty
acids by gas-liquid chromatography. ]. Am. Oil Chemists. Soc., 42: 537-540.
KAY AMA, M. and Y. IKEDA, 1975. Studies on the lipids of micronektonic fishes caught in
Sagami and Suruga Bays, with special reference to their wax esters. ]. Jap. Sci. Fisheries,
24: 435-440.
KAYAMA, M. and H. NAKAGAWA, 1975. Studies on the lipids of some micronektonic shrimps
caught in Sagami and Suruga Bays, with special reference to their wax esters. Ibid, 24:
441-445.
MIWA, T. K., 1963. Identification of peaks in gas-liquid chromatography. ]. Am. Oil Chemists'
Soc. 40: 309-313.
SAIKI, M. and T. MORI, 1953. Studies on the whale oil-I. Properties of oils contained invarious parts of a whale body (Part-I). On the sei-whale and fin whale. ]. Jap. Soc. Sci.
Fisheries, 19: 611-613.
SAIKI, M., S. C. FANG and T. MORI, 1959. Studies on the lipid of plankton-II. Fatty acidcomposition of lipids from Euphausiacea collected in the Antarctic and Northern Pacific
Oceans. Ibid, 24: 837-839.
TSUYUKI, H., U. NARUSE, A. MOCHIZUKI and S. !TOH, 1964a. Studies on the Euphausiacea,
Euphausia superba I. Acetone-soluble lipid. ]. Jap. Oil Chemists' Soc., 13: 203-206.
TSUYUKI, H., U. NARUSE, A. MOCHIZUKI and S. lTOH, 1964b. Studies on the Euphausiacea,
Euphausia superba II. Properties of phospholipids. Ibid, 13: 477-480.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

THE OCCURRENCE OF THE PHOCID SEALS ALONGTHE COAST OF JAPAN AND POSSIBLE
DISPERSAL OF PUPSY ASUHIKO NAITO
Kominato Marine Biological Laboratory, Tokyo University of Fisheries,
Amatsu-kominato, Chiba.

ABSTRACTThe distribution of the phocid seals was studied both outside area
and in the border area of their habitat. Sixteen catch or observation
records from Honshu, Shikoku and Kyushu of Japan were examined.
Three species appeared, the ice-breeding harbour seal (Phoca vitulina),
the ringed seal (Pusa hispida) and the bearded seal (Erignathus barbartus)
occurred while the land-breeding harbour seal (Phoca vitulina) and the
ribbon seal (Histriophoca Jasciata) did not occur in those areas. In theborder area of the habitat, all four species of the ice-breeding seals
occurred. These seals were mostly pups indicating that the new born
pups spread their distribution after ice season being carried by the ice
floes and some of them occurred far south from their habitats.
INTRODUCTION

The author has studied the pagophilic (ice-breeding) and the pagophobic (landbreeding) harbour seals (Phoca vitulina) comparing their ecology and morphology. The pagophilic form annually shifts their habitat from the edge zone ofdrifting ice to coastal area, while the pagophobic form stays at the same habitat(coastal) even in breeding season. These differences of their life systems between two forms may strongly relate with their adaptation systems, especiallyin the period of new born pups. In the pagophilic form the shift of habitat
occurs several weeks after their birth, and during this short period, importantlife events occur on the new born pups such as suckling, weaning, moulting,and moreover physical and morphological changes. It is the problem that these
events are performed on unstable ice floes in the edge zone of the drifting ice.
If the shift of habitat was unsuccessful processing these events, as Naito andNishiwaki (1972b) suggested, the pups would be carried away by ice drift so as
to spread their distribution. In the pagophobic form, however, such habitat
shift does not occur, and mother-pup relationship continues longer to result thesteady and successful weaning and independent life of the pups. Therefore,
the pup distribution of this form is settled.
The present study is aimed to examine the above understandings by studying the distribution of these seals (including other species) in the border areaof their habitat and also out side of the border.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 175-185.

NAITO176

DISTRIBUTION OUT SIDE OF THE BORDER OF THE HABIT AT

The present study deals with occurrences along the coast of Japan other than
Hokkaido (Honshu, Shikoku and Kyushu). Catch or sighting records of theseals along the coast of Japan other than Hokkaido are rare and scarce, so it
is difficult to collect such records. In the present study records and informations
were collected from following three sources. (1) The newspaper or T.V. broadcasting as a local news ; the seals in these areas are very strange animals, therefore if they were caught or sighted such seals were sometimes reported by them.
(2) Aquariums; if the animals were caught alive, they were usually sent to theaquariums near by for display, and aquariums kindly sent me the informations
to my requests. (3) The prefectural fisheries research station or local museum;the catch or sighting informations by local people were given to them. As tothe biological informations, species, date, place and length or approximate length
were available from above informations. However, to my regret, sex, bodyweight and age determined from canine teeth are unknown.
Appeared species
Three species, bearded seal, ringed seal and harbour seal were accidentallycaught or sighted along the coast of Honshu, Shikoku and Kyushu (Fig. 1).
Only two bearded seals were recorded at Akita and Niigata of the Japan Sea
coast of the Northern Honshu, and there are no records from Shikoku andKyushu. Out of 5 records of ringed seals, two were from Japan Sea coast of
Honshu and two were from Pacific Ocean coast of Honshu and Shikoku. The
130°E

14d'E

150°E

45°N

45°N

•
40°N

40°N
PACIFIC OCEAN

35°N

140°E

150°E

Fig. 1. Some catch or observation records of the phocid seals from the coastof Honshu, Shikoku and Kyushu of Japan and others.
the ice-breeding
harbour seal; .A., the ringed seal; •• the bearded seal.

e,Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PHOCID SEALS ALONG THE COAST OF JAPAN

177

far south record was from Fukuoka-city, Kyushu. Nine ice-breeding harbour
seals were recorded. Out of nine, 6 seals were recorded from the Pacific Ocean
coast of Honshu and only one seal was from Japan Sea coast of Honshu. None
were recorded from Kyushu. In the present study, records of occurrences fromJapan coast other than Hokkaido were dealt with as a materials, however, in
this chapter additional two examples were also included. One was the catchrecord by fishing boat from the Pacific Ocean, about 300 miles from the coast.
The other is sighting record by research vessels at the mouth of Port Hakodate,the most south of Hokkaido. From above records, it is supposed that the ringed
seal and the ice-breeding harbour seal occur more often and futhermore south
than the bearded seal, but it is quite difficult to get any conclusion as to themigration route of these seals from their habitat towards southern areas. The
most stressed facts in this chapter is that none of the ribbon seals which are as
popular as the ice-breeding harbour seal in the Sea of Okhotsk, and none of
the land-breeding harbour seal of which habitats distribute in the furthest southof Hokkaido, were recorded in the coast of Honshu, Shikoku and Kyushu.
Appeared season
The seasons when the seals occurred along the coast of Honshu, Shikoku
and Kyushu were shown in Fig. 2. In this chapter, the seals were not treatedseparately by species but as a total records of 3 species were treated, andaddional 2 records of the ice-breeding seal from the Pacific Ocean and the portof Hakodate were excluded because they were not the records from intended
area (Honshu, Shikoku and Kyushu). As shown in Fig. 2, the seals begin to occur
from April at 12.5% frequency, and the highest frequency was 25% in May.
After May seals decrease to occur. In June and July 18.7% of the total occurred

25.0

4
Ul

0:I

3

"U

>
iJ
c

0
.....
Q)

2
1

..0

E
::I

z

J

F M

A M

J

Fig. 2. The seasonal appearance frequency of the seals occurred along the coastof Honshu, Shikoku and Kyushu. Numbers were shown in percentage. Dottedspace shows the ice-breeding harbour seal; horizontal line, the ringed seal;vertical line, the bearded seal.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NAITO178

respectively and none of seals occurred in December. Seventy five percent
seals of all occurred from April to July. Being still short data, from mentioned
above, the following two problems were indicated. 1) The seals begin to occur in
April. This time well corresponds with after-season of drifting ice in Hokkaido.
2) The seals decrease to occur after May. This may indicate that the smaller
number of seals occur in later season in farther south area. The problem 1)
will be discussed later. The problem 2) may be explained by Fig. 3. In
M

A

•
•

N.HONSHU

S. HONSHU

SHIKOKU

J

M

-·

J

A

AA

A

0

N

•

D

9
64.3°/o2
14.3°1o••A•

KYUSHUs2
14.3°1oA

7.1°1oFig. 3. Time difference of the first occurrence between each area. The seals
begin to occur from north. They occur in Northern Honshu at ffrst and in
Kyushu at latest.
the ice-breeding harbour seal; .A, the ringed seal; . ,the bearded seal.

e,Fig. 3, the area where the seals recorded were separated to. four districts,
from north to south; northern Honshu, southern Honshu, Shikoku and Kyushu.
Honshu was sepatated by the line between Boso Peninsula and Noto Peninsula.
As shown in Fig. 3, in northern Honshu 9 seals (64.3%), in southern Honshu
and Shikoku 2 seals (14.3%) in each and only 1 seal in Kyushu were recorded
respectively. Furthermore, the seals were recorded from earier season innorthern Honshu, and in Kyushu it recorded in latest season. From all above
mentioned, it is suggested that the seals move towards south from main habitatin the Sea of Okhotsk and the adjacent waters.
Ages of the seals recorded
In the present study, age informations based on examination of canine toothwere not available. Only measured body size or approximate body size wasused for growth developmental class estimation. In general it is difficult toestimate ages by body size, however, body size indicates such growth stages aspup, young subadult and full adult. Tikomirov et al. (1969) showed the growth
curves of the bearded seal, ringed seal and the ice-breeding harbour seal. Naito
and Nishiwaki (1972) also showed the growth curves of the ice-breeding harbour
seal. From these curves and the measured body size or approximate body size
shown in Table 1, the growth developmental classes were possibly estimated tobe pups in the ice-breeding harbour seal and ringed seal. In the bearded seals
one was young or subadult and the other was also pup.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

~

about 100 cm
about 100 cm

Susaki-Bay, Kochi
Miyazu-Bay, Kyoto
Kiso-River, 20-25 km up from mouth of river

' '58
' '53
. '73

Jui.
Jui.

z

0

80cm
104 cm (total length)

Kominato.Bay, Chiba
Hazaki-Beach, Kashima, Ibaragi
Kashimanada, Ibaragi

Apr. 23, '72

May 30, '49<.c:>...,.....

>
'"tl
>
z

":!

'-<

-

Jui.

about 150 cm

0

...i

VJ.

>

0

::r:
l:T:I

Q
...i

16 kg

10 kg

0

>
I:""

VJ.

I:""

>

l:T:I

VJ.

t::I

0

-

'"tl

::r:

0

85 cm (measured bymolted specimen)
femaleless than 100 cm

Ayukawa, Miyagi''54(young)- (pup)less than JOO cm-

90 cm (total lengh)

11. 3 kg
12.4 kg

120 kgBody weight

60 cm (total lenght 88 cm)

May

male

male

75. 0 cm (total length)

Port of Ayukawa, Miyagi

mouth of Hakodate-Bay Hodkaido'Pacific Ocean 43°!4 1 N; 156°34 1 E

Azirozaki-Beach Hiwasa, Tokushima

Shiratori-Beach Toyama

Creek in Tsuyasaki-Bay Fukuoka

75.0cmmale

Teisan-Cannal Yuriage, Natori-city Miyagi

145 cm180cm

Body length

100 cm (total length)

male

Sex

Senami-Beach Murakami-city, Niigata

set net Teno-cho, Akita
Port of Niigata

Locality

THE LIST OF SEALS CAUGHT ALONG THE COAST OF JAPAN.

Jun. 7, '68
May 20, '69
May
' '54

4, '752, '75

"

Jun.
Nov.

Jun. II, '69
Aug. 7, '74

Apr. 28, '68
Oct. 18, '70
Sep. 15, '73"

Phoca vitulina largha

Pusa hispida

Erignathus barbartus

Date of catch,,..

Species

TABLE 1.

~

'~"'

1'"

.~~"'

._

""~
~Co~

~ ?:

180

NAITO

THE CATCH RECORDS IN THE BORDER OF THE HABITATAs already described, the bearded seal, the ringed seal and the ice-breeding
harbour seal had occurred along the coast of Honshu, Shikoku and Kyushu,
and the ribbon seal and the land-breeding harbour seal had never occurred inthese areas. It is also mentioned that these occurred seals were mostly pups.
They begin to occur from north to south indicating the southwards moves, andthese occurrences began from April indicating some relation with the time of
habitat shift from the ice floe to the coast in these three species, because theice floes melt and disappear from mid March to mid April in Hokkaido. In
this chapter, to examine above problems more precisely the catch records byfishing nets in the border of the habitat were studied in two seasons, after ice
season and in October (6 months after ice season).
There are two border parts in Hokkaido. One is the Soya Strait whichconnects the Sea of Okhotsk to the Japan Sea, and the other is the Nemuro
Strait which connects the Sea of Okhotsk to the Pacific Ocean. The study was
performed in the Nemuro Strait which is generally known as the southern borderof the habitat of the pagophilic seals in the Sea of Okhotsk (the bearded seal,
the ringed seal, the ice-breeding harbour seal and the ribbon seal, Naito, 1969).
Especially in the ice-breeding harbour seal the lake Furen in the Nemuro Strait
area is known as the southern edge of the distribution of their hauling grounds.

The catch records after the ice season
The Nemuro Strait area are also known as almost southern limits of annual
constant occurrence of the drifting ice from the Sea of Okhotsk. The ice prevails through this strait area from early February to mid or late March, sometimes mid April when the ice is eminent (Ruhyo-Sokuho, 1969-1975). During
this season, the ice moves from north to south being carried by the wind andcurrent, and it occurs in the Pacific Ocean passing through the strait (Fig. 4).
After the ice occurred in the Pacific Ocean it melts quickly near around the
Nemuro Peninsula. However, when the ice is extensive, it is occasionally driven
as far as the Point Erimo. The ice condition in the Nemuro Strait is notconstant, and it is always drifting making open seas somewhere in this strait.
The ice floes occuring in these areas are relatively small but varied such asslush ice, ice-cake, small or medium floe berg, rafted or hummocked ice, brash
ice. These ices in these areas are capable of supplying hauling or breedingsite for the seals. However, the breeding population were found only in thearea between the Shiretoko Peninsula and the Kunashiri Island (Naito, 1969;
informations from the hunters). In this area, the dominant breeding species is
the ice breeding harbour seal and the ribbon seal, and the ringed seal and thebearded seal are quite rare (Naito, 1969). After the ice season, from May only
the ice-breeding harbour seal occurs along the coast to haul out the grass bars
making 30-70 individuals groups in Odaito and the Lake Furen which open
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PHOCID SEALS ALONG THE COAST OF JAPAN

181

43°N

1970 MARCH 26-28

1971 MARCH 24-27

Fig. 4. The distribution of the pack ice in its southern border at the later puping
season of the ice-breeding seals. The ice floes occur in the Pacific Ocean from thesouthern Sea of Okhotsk passing through the Nemuro Strait or near by.

to this strait.
Sampling was performed at Kanazawa Fur Company from 1969 to 1971
during later half of May and June (1969, 1970 May 8-June 30, 1971 May 11June 30) when the ice completely disappeared. The results were shown in Table
2. The seals mostly caught accidentally by fishing nets along the Nemuro Peninsula (Both coasts of the Nemuro Strait and the Pacific Ocean) were collected at
this Fur Company. Almost of these collected seals were examined in 1969 and
1970, however, in 1971 about half of the collected were examined. All 4 ice
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

:">" ,;"'.,. .,

~~

"
~~
""~
.,,O::J ~

~

~

~

"'~-

1971

1970

1969

95.0 cm

May 28

NM 23

Sankaku

May 12
May 17
May 20

145
150
160

HanasakiMay 30June 7
May 14182
214

June 27
June 27
May 16

446
452

"
"
"
419

2

439

Ribbon seal

May 22
June

422

147

Sankaku

May 26175

78. 0 cm
85. 5 cm

femalefemalefemaleHokakemale

femaleHokakeSankaku

male

male

femalemale

91. 0 cm

99. 0 cm

98.0 cm

97.0 cm

88.0 cm

89.0 cm

89.0 cm

76 cm
104. 5 cm
male

101.0 cm

male
male

Futatsuiwa-

OnnetoOnnetoTokatan

May 24

167

Horomoshiri

May 20
May 23

male

-

165

95. 5 cm

femaleSankaku

100. 5 cm

125. 0 cm

female161

Ice-breeding harbout seal

Ribbon seal

"
"

"
"
"

femaleOnnetoIce-breeding harbour seal

"
166

male

Honioi227

Ringed seal

146.0 cm

female151. 5 cm
83. 5 cm

149.5 cm

femaleMay 14

148
Ochiishi

91. 0 cm

June 7
June 23
May 23

Sankaku

Tomoshiri

female87.0 cm

femaleMay 26

Sankaku

Sankaku

May 26NM 22

73. 5 cmmale
female-May 17

NM 10
NM 21

213

Bearded sealIce-breeding harbour seal

72. 5 cm

68.0 cm

141.0cm

femaleMay 30NM 24

femaleBody size

NemuroMay 19NemuroSankakuSex

77.5 cm

May 13

NM 5
NM 15

Locality

femalefemaleMay 21

NM 17

Date of catch

Ringed seal

Field number

CATCH RECORDS ALONG THE NEMURO PENINSULA AFTER ICE SEASON.

Bearded seal

Species

TABLE 2.

pup

pup
pup

pup

pup

probably pup

pup
pup

pup

1

pup

1

pup
1

pup
2

probably pup
probably pup

pup

pup

pup
pup

pup

pup

probably pup

pup

pup

Age

0

..,i

z

>
......

o;

""

183

PHOCID SEALS ALONG THE COAST OF JAPAN

breeding seals occurred in this area. The ice-breeding harbour seal occurredat the highest frequency as same as seen in Honshu, Shikoku and Kyushu areas.
The bearded and the ringed seals occurred at the same frequency. The ribbon
seal has never been reported in Honshu, Shikoku and Kyushu, but occurred inthis area at the lowest frequency. Concerning the ages of these seals, some were
not examined by the canine tooth, for the whole skulls were reserved andattached to the skin for the moulted specimen. However, as well as in former
chapter, the ages were estimated by the body size. In all species, the seals caught
in this area were mostly pups indicating same tendency seen in Honshu, Shikoku
and Kyushu areas. These facts may strongly relate to the movement of ice
mentioned above. In the present study, there were no direct observation thatthe ice carried such pups through this strait to the Pacific Ocean. However,to examine the seasonal changes the author studied the distribution of these
seals in other season, October, in the same area.

Catch records in October
The sampling was performed in October 1969 (3-30) by v1s1tmg the fishingvillage when informations were brought by fishermen. The results were shownin Table 3. In this season the result was quite different from that of the after
ice season. Only two species, the ice-breeding harbour seal and the ribbon seal
were caught. None of the ringed seal and the bearded seal were caught. The
TABLE 3.

CATCH RECORDS ALONG THE NEMUROPENINSULA IN OCTOBER (1969)

SpeciesFieldnumberDate ofcatch

Ice-breeding
harbour seal

Ribbon seal

Locality

Sex

Body size

7

Ochiishimale

162. 0 cm

8

9

Habomaifemale149.0 cm

Toritoishi

female160.5 cm

3
18

Age

16

October 14

18

October 15

Tohbaifemale36

October 23

Habomaifemale

156

cm

10

39

October 26

Odaitohfemale130.5 cm40

male

133. 5 cm

3
2

41

female33
34
43

October 23
October 27

Sankaku
Sankaku

male

adult

male

153. 0 cm
132. 0 cm

male

149.0 cmadult
immature
immature

data are quite small, however as seen in Table 3, half of the ice-breeding harbour
seals were adults, which had been never caught after ice season. In the ribbon
seal the adult seal was included.
Aboves are quite short data to get some conclusion, however it is clear thatage composition of the ice-breeding harbour seal which occurred in this area
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

184

NAITO

is quite different between after ice season and in October. In the former season,
seals were mostly pups (76.5%) and none of adult seals occurred. On the other
hand in the later season adult seals (50%) occurred in the same area. It is still
uncertain when these age compositions change, yet it is supposed that the dispersion of adult seals in this area is due to the salmon migration, because these
seals were caught by the salmon set nets which were operated from summer toautumn when the salmons migrate to the coast for their up river spawningmigration. There is no clear explanation why the bearded seal and the ringed
seal never occurred in this season. However, it is supposed that their habitats(hauling grounds) are too far north in Sakhaline (lnukai 1942) to occur in thisarea except ice season. Three ribbon seals were caught in this season, however,these seals were not caught by the coastal salmon nets but caught by the gillnets offshore in this area, and this seal is still seemed to be rare species in the
coast.
DISCUSSION
The author examined the distribution of the pagophilic seals in area outside of
their habitat and in the border area, and the followings are recognized. The
ice-breeding harbour seal, the bearded seal and the ringed seal occurred in
Honshu, Shikoku and Kyushu moving from north to south. These seals were
mostly pups. The ribbon seal has never occurred in this out side area of theirhabitat. The land-breeding harbour seal also has never occurred in this area.
In the border area of their habitat, all 4 pagophilic seals occurred along thecoast of the Nemuro Peninsula after ice season. The most of these seals were
pups. However in October in the same area, only two species, the ice-breeding
harbour seal and the ribbon seal occurred, and the adult seals occurred in highfrequency.
The present study depended on short data, however, above facts furthermore lead to the important conclusion as follows. The pagophilic seals especially
ice-breeding harbour seal (except the ribbon seal) disperse their distribution
during or after the drifting ice melted. On the contrary, the land-breeding
harbour seal which distributes along the Nemuro Peninsula to the Point Erimo
does not shows such wide dispersion not only by the pups but also by others.
These difference may due to their mode of life. The ice breeding seals shift
their habitat from ice floe to the coast except the ribbon seal. These shift
may occur pretty shortly after birth for the pups especially in the ice-breeding
harbour seal (2-3 weeks after birth), for they occupy the edge zone of theseasonal pack ice (Burns, 1970; Fay, 1972; Naito, 1972a). During this shortperiod, pups have to accomplish their life events on ice floe such as suckling,moulting of the lanugo coat and the weaning for their swimming life. The dispersion carried by the ice floes is innevitable for the pups which possess such
above life, and this periods is highly critical for their survivals. However,
perhaps for compensating these critical early stage of life, pups of these seals
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PHOCID SEALS ALONG THE COAST OF JAPAN

185

possess the very thick blubber as energy storage (Naito and Nishiwaki, 1972b).
The pups of the land-breeding harbour seal have much more stable life. They
begin to swim soon after birth. The mother-pup relationship continues longer(about 4-6 months-Naito and Nishiwaki, 1972b; Belkin et al., 1969), and theweaning occurs gradually. Therefore the dispersion of pups may not occur.
In the present study the ribbon seal has not occurred in Honshu, Shikoku andKyushu areas. This may relate with that the ribbon seal apparently becomespelagic after the breeding and moulting season (Burns, 1970; Fay, 1972).
ACKNOWLEDGMENT

Through this work, I owed it to many people that I could collect records andinformations about wondering seals along the coast of Japan for many years.
The greatest thanks are due to many aquariums, museums, prefectural fisheries
experimental stations who are very kind to send me the valuable informations
for my requests. In the field works, I wish to thank to Mr. Nobuyoshi Kanazawa, Kanazawa Fur Company, and many fishermen who gave me informations
and chances to examine the specimens.
REFERENCESBURNS, J. J., 1970. Remarked on the distribution and natural history of pagohilic Pinnipeds
in the Bering and Chukchi Seas. ]. Mamm.,51 (3): 445-454.
FAY, F.H., 1972. The role of ice in the ecology of marine mammals of the Bering Sea. International Symposium for Bering Sea Study. Hokkaido University, Hakodate, Japan. (inpress).
INUKAI, T., 1942. Hair seals in our northern waters (I). Shokubutsu oyobi Dobutsu, 10(10): 927932. (iu Japanese).
NAITO, Y., 1971. A report on Japanese sealing. Geiken Tsushin, 238: 49-52. 48-52. (in Japanese).
NAITO, Y., and M. NISHIWAKI, 1972a. The growth of two species of the harbour seal in theadjacent waters of Hokkaido. Sci. Rep. Whales Res. Inst., 24: 127-144.
NAITO, Y., and M. NISHIWAKI, 1972b. Ecology and morphology of Phoca vituline largha andPhoca kurilensis in the southern Sea of Okhotsk and north east of Hokkaido. Symposium on
the Biology of the Seal., University of Guelph, Ontario Canada.
TIKHOMIRov, E. A., 1971. Body growoth and development of reproductive organs of the North
Pacific Phocids. In: Pinnipeds of the North Pacific. (Israel program for scientific translations). Keter Press, Jerusalem, 213-241.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

THE VARIATION IN THE DEVELOPMENT OF PELAGE
OF THE RIBBON SEAL WITH REFERENCE
TO THE SYSTEMATICSY ASUHIKO NAITO
Koninato Marine Biological Laboratory, Tokyo Universityof Fisheries, Amatsu-Kominato, Chiba

AND
MASA YUKI OSHIMA
Kamogawa Sea World, Kamogawa, Chiba

ABSTRACT

More than four hundreds pelages of the ribbon seal (Histriophoca
fascita) were examined to know the development of the patterns andtheir variation. To describe them, some terminology were devised. The
formations of these bands pattern were closely related to the pigmentation. Concerning to the pigmentation, two types of the pigmentation
were found such as basic pigmentation and secondary pigmentation.
The former pigmentation was found in both ·sexes of all ages except
pups (not white coat pups), and the later pigmentation was found in
adult males and in some females. However, some adult males did notshow secondary pigmentation exceptionary. From these formations of
the pigmentation, the ancestral form of the ribbon seal was speculated.
The small ringed pattern was also found, and systematic reverse or
atavism was considered and discussed.

INTRODUCTION

The ribbon seal (Histriophoca fascita) is generally known for its ribbon mark.
Their color pattern is much characterized by sex. The ribbon seal and harp
seal are the only seals with banded pelage, and in these seals the color pattern
has not been discussed and argured while the sexual dimorphism seen inpolygamous form has been well noted from the point view of social biology,
evolution and so on. In general, however, divergence in the pinnipeds frommeaning of adaptation occurs in many directions. The less arguments anddiscussions on the color pattern of the ribbon seal may due to the less knowledge
on this seal. When we consider the problems on color patterns, we have quite
small knowledges on their distribution, movements, breeding, social behaviour
and etc. Yet, it is still necessary to discribe the color pattern itself for the sakeof future study of adaptation, evolution and systematics on this seal. The present
Sci. Rep. Whales Res. Inst.,
No. 28, 1976, 187-197.

188

NAITO AND OSHIMA

paper is written to introduce the color pattern itself of the ribbon seal, andvariations are described with some new findings.
MATERIALS AND METHODSAll pelages of the ribbon seal dealt in the present study were collected fromthe area along the Sakhalin (south to 50°N) in the Sea of Okhotsk from the
mid to the end of May 1975. The pelages of these seals were stocked in the
fur companies after they were tentatively tanned. The authors had a chance
to examine the pelages in October 1975 at Engaru Fur Company and Hakodate
Fur Company. The pelages were recorded by photo to examine. The pelages
size were measured from the nose tip to the root of the tail. The measurements,
however, were sometimes rough because the pelages were broken in the measuring points. The sexes were also recorded by examing the genital openings(penis openings in males and teats openings in females). The total numbers
examined in this study were 472 pelages (280 males and 192 females).

1.

The formation of the ribbon pattern
It is widely known that the adult male ribbon seal has the characteristic
white bands on their head to neck part, lateral body sides and lumber partwhich are so-called ribbon pattern. These white bands are also found in adultfemales, yet they are not so distinct. It is also generally recognized that thesewhite bands are not seen in both sexes of young seals. Concerning the revelation of these bands, however, it is still uncertain when and how these bands
are formed.
According to the Tikhomirov (1966), during the time from the moulting of
the lanugo coat to the first moulting the seals have no pattern showing darkgrey color in the dorsal side and bright grey in the belly side. After the firstmoulting at one year old they begin to show the distinct shield shaped pattern
against the darker grey back, however there found no sexual dimorphism in thecolor pattern. After the second moulting at 2 years old, they first begin toshow the peculiar ribbon pattern in males, and sexual dimorphism was foundin the color pattern. The seals show the full adult type ribbon mark in males
at 3 years old.
In our pelage study, we failed to get age informations from canine teeth,
however, we got almost same results as Tikhomirov (1966) attained. As shown
Table 1 and Plate I, all pelages were easily classified into four categories inmales and three in females such as stage I, stage II, stage III, and stage
IV in males by the developmental stages of the pattern, and each stages ofboth sexes well corresponded with the results by Tikhomirov (1966). The sealsof both sexes of stage I have no ribbon pattern but showed grey or brownish
grey back and creamy white or brownish yellow bellies. The seals of thisstage were identified to be pups by the sealers and the pelage process workers.
Actually these pelages corresponded with the pelages of 0 year old described
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PELAGE PATTERN OF RIBBON SEAL

189

TABLE 1. PELAGE MATERIALS USED IN THIS STUDY. ALL PELAGES WERE
CLASSIFIED IN EACH 10 CM BY THE LENGTH, AND THE DEVELOPMENTAL
STAGES OF PELAGE PATTERN WERE EXAMINED. NUMBERS
IN PARENTHESIS SHOW PERCENTAGE OF
EACH STAGE IN EACH CLASS.
Class of pelage
size in cm

Numbers
stage I

Developmental stage of patternstage IIstage IIIstage IVMales

110-120120-130130-140140-150
150-160
160-170
170-180
180-190
190-200

2
10
31
35
63
75
55
7
2

2 (100.0)
9 ( 90.0)
10 ( 32.2)
5 ( 14.3)
I ( 1. 6)

280

27

6
12
28
17

6 (100. 0)
10 ( 83.3)
6 ( 21. 4)
2 ( 11.8)
I ( 2.2)

1 (10)

1 ( 1. 3)

2 ( 6.4)
17 ( 48.6)
58 ( 92.0)
73 ( 97.4)
55 (100 )
7 (100 )
2 (100 )

29

10

214

2 (16.7)
20 (71. 4)
9 (52.9)22 (48.9)

2 ( 7. I)
6 ( 35.3)
22 ( 48.9)

19 (30.2)
3 (16. 7)
l (33.3)

44 ( 69.8)
15 ( 83. 3)
2 ( 66. 7)

7691

16 (51. 6)

3 ( 9. 7)

II (31. 4)

2 ( 5. 7)
3 ( 4.8)

I ( 1. 6)
I ( 1. 3)

Females110-120120-130130-140140-150
150-160
160-170
170-180
180-190

45
63
18
3
192

25

by Tikhomirov (1966). From above the seals of stage I were supposed to be 0
year old. The seals of stage II still showed the same pattern between two sexes.
They begin to show the peculiar shield pattern with narrow white line at its
margin, and at the same time the initial pup dorsal dark color were still found.
These seals of this stage were also estimated to be 1 year old by the sealers andthe pelage process workers, and also the comparison with the results by Tikhomirov ( 1966) suggested these seals to be 1 year old. In stage III seals begin toshow the sexual dimorphism. Being incomplete, male seal pelages of this stage
showed the ribbon pattern with obscured ·white bands. These pelages did
not show as strong contrast as seen in full adult type pelages as over all
look, and shield pattern had developed extending four feet towards the belly
side to connect each other from both sides making the ring patterns at eachlateral sides. The margin of this developed shield pattern were relatively clear.
On the contrary, the other margin of white bands were unclear, so that the
ribbon pattern did not appear clearly at this stage. This may due to the time
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

190

NAITO AND OSHIMA

duration of pigmentation between four feeted dorsal pigmentation (developed
shield pattern) and other pigmentation, and also due to decolorization in whitebands parts. As a matter of facts in this stage unclear radial thin dark lines
were found in the white bands. In this stage initial pup dorsal dark color
which were found in stages I and II were already lost. Concerning the age ofthis stage, the sealers and the pelage process workers do not classify the pelages
by age, however, seals of this stage were supposed to be 2 years old in accordance with pelages of 2 years old seals described by Tikhomirov (1966). Pelage
pattern of female seals of stage III were apparently different from these ofmales. Wide variation being found, seals generally showed indistinct ribbon
pattern. The pigmentations did not develop as strongly as males of samestage. The peculiar shield pattern which were always found in stage II usuallychanged to have extended four feet. Over all look, however, was very bright,
for the pigmentations at lateral body side and hip parts were dim. The
decolorization at white bands developed to vanish the initial pup dorsal
dark color which was still found at stage II. The ages of female seals of thisstage III were supposed to be over 2 years old. Only in males stage IV waspossibly classified. Seals of this stage showed complete adult type ribbon
pattern. The ages of seals of this stage were supposed to be over 3 years old.
As already described, we do not have any age informations from the canine
teeth in this study, yet we could know the formation of .the ribbon pattern by
the age in accordance with the results by Tikhomirov (1966). However it isconsidered that age variation may occur in the formation of the ribbon pattern.
To make this problem much surer, we studied on the captured ribbon seals.
Kamogawa Sea World well succeeded in keeping a male and a female ribbon
seals. A male and a female pups were kept from 1973 and 1974 respectively.
This male seal developed his pattern showing the same stages as describedabove after each moulting in May, and showed complete ribbon pattern of the
final stage in this study at age 3 years old. On the other hand a female seal
showed the same pattern as stages I and II at age 0 and 1. However, she had
died at age I year old in 1974. From above all, stages I, II, III and IV wellcorresponded to the age 0, 1, 2, and over 3 years old in males, and stages I, II.
III also to the age 0, 1, and over 2 years old in females.

Analysis f rorn schernatic diagrarn
As mentioned above, the ribbon pattern was formed age by age
showing the peculiar age classes such as stages I, II, III, IV in males andstages I, II, III in females. We already described when these pattern appear,
however, we still do not know how they appear. To analize this problem, we
made some schematic diagrams in each sex, and for the explanation conveniencesome terminology were used. Farther more in the former chapter, we usedstage classes such as stages I, II, III, IV for the convenience, however, eachstage corresponded to age classes such as 0 year old, 1 year old, 2 years old
and over 3 years old respectively over all. Therefore we use age classes instead

2.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PELAGE PATTERN OF RIBBON SEAL

191

of stage classes m this chapter and later chapters.
Male
Plate II shows the schematic peculiar pattern of each age classes, this plate
also shows the degrees of pigmentation. Seals of 0 year old have their dorsal
pattern ·which are named pup pattern (P. P.). At age one, the darker shieldpattern (S. P.) appears in the center part of pup pattern, and at the same time
decolorization occurs at the margin of shield pattern. As a result pup pattern
are divided into four pattern such as initial neck pattern (I. N. P.), initial
lateral patterns (I. L. P.) and initial hip pattern (I. H.P.). The pigmentations ofthese patterns are same degree as pup pattern at age 0. The pigmentation anddecolorization develop quickly at age 2. The basic shield pattern developed
having four feet which connect each other to make round circle at lateral side.
This developed shield pattern (D.S. P.) is almost real black. The same degreeof pigmentation appears in the head and neck parts forming the neck pattern(N. P.) which took place the initial neck pattern (I. N. P.). The decolorization
at the outer margin of developed shield pattern occurs as fast as pigmentation
forming the neck band (N. B.), lateral bands (La. B.) and lumber band (Lu. B.),so that the initial lateral pattern at age 0 do not appear at age 2. At the sametime, however, the lesser new pigmentation begin to occur innerpart of thelateral bands and at hip part forming the lateral pattern (L. P.) and the hippattern (H.P.). The developemental stage of pigmentation and the decolorization attains the final stage at age 3. The neck pattern and the developed
shield pattern come to much more black, and the delayed pigmentation of thelateral pattern and the hip pattern develop to come as black as the pigmentation of other patterns. At the same time each bands appears whiter by thedeveloped decolorization.
As mentioned above, we could find out that time duration of the pigmentation and the decolorization exist in forming the so-called ribbon pattern, andfurthermore we can classify the pigmentation of each pattern by their developmental stages, while the decolorization of each bands is impossible to classify
because of their same developemental stage. Fig. 1 shows this pigmentation
stage of each pattern. The pigmentation of pup pattern is decreasing andtook over by other pigmentation or disappear. We call this as the degenerative
pigmentation. The pigmentation of the shield pattern is very stable and very
actively increase, and the neck pattern pigmentation is relatively stable andincreasing. These pigmentations are classified as the basic pigmentation. The
latest pigmentations of the lateral pattern and the hip pattern are not stable, forthese are much variable (explained in the later chapter). These are classified
as the secondary pigmentation.
FemalePlate III shows the schematic diagrams of pattern of each age class in females.
As shown in Plates II and III, females show the quite same pattern and the same
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

NAITO AND OSHIMA

192

degrees of pigmentation and decolorization as males at age 0 and 1. At age 0
they possess the pup pattern, and at age I the shield pattern, initial neckpattern, lateral patterns and initial hip pattern appear as well. At age 2, theshield pattern develop its four feet at each corner making the round circles
at lateral sides. This developed shield pattern is quite same as males not in
the degrees of pigmentation but in form. The neck pattern, the lateral pattern,
and the hip pattern also appear at this age, while the pigmentation of thesepattern also not so strong as males. These pattern and pigmentation do not seemto change over 2 years old. Compared with males, overall look of female
seems to be quite bright and no pattern seems to exist in females at firstglance. However, these are due to the less pigmentation in females. They
actually possess the each same pattern as males. These pigmentation stage ofeach pattern are also shown in Fig. I. Concerning to the sexual dimorphism, it
is generally believed that the male ribbon seal shows distinct ribbon pattern
and the female seal does not show it. As already mentioned above, it was
revealed that the sexual dimorphism are found not in the pattern itself but inthe degrees of the pigmentation of the pattern. As seen in Fig. I and Plates
II and III, the sexual dimorphism occurs after 2 years old, and completion ofdimorphism is found at age 3. Probably, these are closely related to the sexual
maturation. We do not know the age of sexual maturation of the ribbon seal.
According to Tikhomirov (1966), however, it seems to mature after age 2 and3 in fem ales and males.
ages

0

1

P.P

+

+
++

S,P.
Male

D.S.P.
N.P.
La.P.
H.P.
P.P.
S.P.

FemaleD.S.P.
N.P.
La.P.
H.P.

+

+
++

2

3

degenerative pigmentation

+++
+++
+++
++
++

+++
+++
+++
+++
+++

++
+
+
+
+

++
+
+
+
+

basic pigmentation

secondary pigmentation

degenerative pigmentation
basic pigmentation

secondary pigmentation

Fig. I. Development of the pigmentation of each pattern. Plus simbols show thedegree of the pigmentation. Abbreviation shows as follows. P.P., Pup Pattern;
S. P ., Shield Pattern; D.S. P., Developed Shield pattern; N. P., Neck Pattern; La. P.,
Lateral Pattern; H.P., Hip Pattern.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

193

PELAGE PATTERN OF RIBBON SEAL3.

The variations of bands, pig1nentations and other charactor
As already introduced, three types of distinct white bands are seen on the
pelage such as head band and two lateral bands which encircle the fore flippers,
and lumber band. Of all three type bands, head band showed the least variation. This band circulate the neck and the throat slightly prolonged anterior
at the head, so that it shows the chevron when we saw the tanned sheet ofpelage (Plate V). Being slight variation in this band, these are no individuals
in our materials which never form the chevron. The lateral bands which form
the large ringed patterns in the sheet of tanned pelages show much more variation than the head band. Some variation being found in the size of the ringitself and width of the band as well, and rather wide variations were found in
the connection or the combination to other bands. Concerning to the way ofconnection three basic types were derived such as type 1, no connection to otherbands; type 2, connection with lumber band (including the case of one sideband connecting to the lumber band); type 3, connection to both head bandand lumber band (including the case of one side band connecting to other band
(Plate IV). The appearance frequency of each type were shown in Table 2.
Type 1 is the most popular with 51.7% frequency, and 34.4% for type 2 and13.9% for type 3 respectively. However, there seemed no pelages which showed
the connection between the lateral bands and the head band. It also seemedthat each lateral band never connect at dorsal side while they usually connect
at belly side. The widest variation was apparently found in the lumber band.
The variation found in this band was so much wide that it seemed quite difficult to describe or classify into some categories precisely. For the convieniencein this study the lumber band variations were only shown in Plate V showing
from simple form to complicated form.
The variation seen in the bands was described already from the understanding that these bands are peculiarly specialized in this species. The patternof these bands, however, have never been interpreted from the point of viewof its origin, for these white bands are too much distinct and attractive todraw the attention to the dark pigmented counter pattern against the whitebands. The darker the pigmented counter parts the more remarkably the whitebands appears. On the other hand, the less pigmentation makes the bands be
TABLE 2. APPEARANCE FREQUENCY OF EACH VARIATION TYPE OF
THE LUMBER BANDS. NUMBERS IN PARENTHESIS SHOW THE
NUMBER OF CASES THAT ONE SIDE OF TWO LUMBER
BANDS CONNECTED TO OTER BANDS.
Type

Numbers

Type I.
Type 2.

108 ( 0)72 (18)51. 7Type 3.

29 ( 9)

Total

209

13.9
100

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

0/

/0

34.4

194

NAITO AND OSHIMA

more obscure. In the present study such above mentioned obscure bands were
found. As shown Plate VI, the less pigmentation were found in the lateralpattern and the hip pattern. We found six examples of this less pigmentation
pelages out of 214 pelages of over 3 years old male seals, and the frequency
was 2.8%. These less pigmentations make the lateral bands and lumber band
obscure as if those bands do not exist. On the other hand the pigmentation
at the neck pattern and the developed shield pattern were very strong andstable, and such less pigmentation were not found. This may relate to the lessvariation of the head band mentioned already. The less pigmentations inlateral parts and hip parts may relate to wider variation of the lateral bands
and the lumber band already mentioned. With regards to the female pattern,
the contrast being obscure, female shows the distinct dorsal pigmentation which
form the same developed shield pattern as the males, while the pigmentationin the lateral pattern and hip pattern are not strong as much as in the developed shield pattern. Therefore in the females no lateral bands and lumber
bands were often found. From above as already mentioned in the former
chapter, the pigmentation of the ribbon seal were possibly classified into twostages from the phylogenetic aspects, basic pigmentation and secondary pigmentation, indicating speculately that the ribbon seal in its ancestral form had thepigmentation in smaller area such face-head parts and shoulder-dorsal parts
showing the brighter phase as over all look (Plate VII), and secondary pigmentation had occurred in the lateral and hip parts resulted the formation of
the peculiar bands so-called ribbon marks. Of course sexual dimorphism by
the pigmentation degrees might existed even if it was not distinct as much as
today's ribbon seal.
The variation of the bands and pigmentation were described above, and theformation of the ribbon pattern were explained. In the present study farther
variation were found. As shown Plate VI, the small ringed pattern or spotted
pattern was found in some of pelages. The appearance frequency was as shownin Table 3. According to the numbers of rings or spotted patterns they wereclassified into three degrees. Males showed higher frequency (8.8%) and infemales these patterns are not distinct and they showed lower frequency (5.6% ).
This difference between sexes may due to that these small white ringed orspotted patterns are embossed against darker pelages of males and are easilyfound. This ringed or spotted patterns well resembles to those of the harbour
seal (Phoca vitulina; both ice-breeding and land-breeding types) which werementioned Belkin et al. (1969), and Naito (1973). On these ringed pattern of theharbour seal, McLaren (1966) pointed out to be atavism related to the ringed
seal. In this study it is quite difficult to deny that these small ringed patterns
are nothing but the only simple variation, because they appeared pretty highfrequency (8.8%) in adult males. The present stage of study on this problem
cannot settle the arguments, however, this fingding in the ribbon seal may
support that these small ringed patterns are the pretty stable systematic or
phylogenitic character which appears in some taxonimic groups.
Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PELAGE PATTERN OF RIBBON SEAL

195

TABLE 3. APPEARANCE FREQUENCY OF THE PELAGES ON WHICH
THE SMALL RINGED OR SPOTTED PATTERN \VAS OBSERVED.
THE PELAGES WERE CLASSIFIED INTO THREE DEGREESBY NUMBERS OF THE RINGS AND SPOTS.
Males

Females

Total

Numerous202Medium

4

0

4

Rare

14

Total

20

5
5

25

Numbers examined

226

90

316

Total ratio for examined numbers

8.8%

5.6%

19

7.9%

DISCUSSION

The pelage color pattern of the ribbon seal were studied, and revelation of thecolor pattern according to ages, sexual difference, the bands variation, theformation of the bands, and the small ringed patterns were examined as systematiccharacter.
Concerning to the sexual segregation in the pinnipeds, the divergenceoccurred in many ways. The remarkable sexual segregation are well known in
the land-breeding polygamous seals such as the fur seals, the elephant seals andetc. In these seals, sexual dimorphism seen in body size, size of canine teeth
and etc. seem to be derived from the possession of territory and mating females
through the struggles between males. On the contrary sexual dimorphism seenin the pelage pattern are only found in the ribbon seal and harp seal. The
ribbon seal occurs in the unstable dispersed pack ice area in the breeding seaon(Burns, 1970; Fay, 1972). This seal dose not aggregate but appears alone on
the ice floes. Each individual occupies each ice floe (Naito, unpublished).
Therefore these remarkable pelage pattern may have some effects to increase achance to mate, or may effect on females as display from a distance even on
ice floes or darker under water where the surface is covered by ice floes. The
breeding behaviours of this seal, however, are not known at the present stage of
our study, therefore explanation on some significance of this pelage pattern
seemed to be quite difficult from the aspects of breeding or scocial behaviour.
As to phylogenic problems, some findings were made in the present study.
The peculiar pelage pattern of this seal were formed by the two stages ofpigmentation such as the basic pigmentation and the secondary pigmentation.
The basic pigmentation was found in all of adult males and females even in
immature seals of both sexes, and the secondary pigmentation was not always
occurred in some adult females and even in some of adult males. When we
consider that the secondary pigmentation are the acquired character in theirpathway of evolution, it is supposedly considered that the ancestral form of theribbon seal would not have the lateral and lumber bands pattern, but showeddark patterns around the face and shoulder-dorsal area against the bright groundSci. Rep. Whales Res. Inst.,
No. 28, 1976.

196

NAITO AND OSHIMA

color. This speculated ancestral form would much resemblance to the harp seal
in the Atlantic, because this seal shows smaller pigmentation parts and brighter
color over all. However, to attain some conclusion on the relation between the
ribbon seal and the harp seal, it is essential to examine the variation of thepelage pattern of the harp seal as well as the ribbon seal.
The small ringed patterns were also found in this study, and estimated tohave some systematic characters. This may support the hypothesis that ringed
patterns occur as atavism (McLaren, 1966). Burns and Fay (1970) showed thesystematic relationship among the four smaller seals of the tribe Phocini (Histriophaca, Pagophilils, Phoca, Pnsa) by the osteological study. They indicatedthe stronger interrelationship between Histriophoca and Pagophilus, and alsosuggested the stronger interrelationships between Pagophilus and Pusa-Phoca
group than those between Histriophoca and Pusa-Phoca group. From above
relationships we can expect to find the some ringed patterns from the harp seal,
too.
ACKNOWLEDG MENTThis work were performed by examing the larger number of pelages, andwe are very much indebted to Mr. Y. Suzuki, the president of Engaru Far
Company and Mr. Kodama, the Hakodate Fur Company. ·They were kindly
permitted us to examine and take photographs their pelages. We also would
like extend our sincere thanks to them for their kindness to permitted us to
use their facilities.
REFERENCES
BELKIN, A. N., G. M. KOSYGIN, and K. I. PANIN, 1969. Marine mammals. Academy of
Scsences of U.S. S. R., Ministry of Fisheries of U.S. S. R., Moscow., 157-175.
BURNS, J. ]., 1970. Remarked on the distribution and natural history of pogophilic Pinnipeds
in the Bering and Chukchi Seas. ]. Mamm., 51(3): 445-454.
BURNS, J. ]., and F. H. FAY, 1970. Comparative morphology of the skull of the ribbon seal,
Historiophoca fasciata,with remarks on systematics of Phocidae. ]. Zoo!., 161: 363-394.
FAY, F. H., 1972. Tne role of ice in the ecology of marine mammals of the Bering Sea. International Symposium for Bering Sea Study. Hokkaido University, Hakodate, Japan.
MCLAREN, I. A., 1966. Taxonomy of the harbor seals of the western North Pacific and evolution of certain other hair seals. ]. Mamm., 47(3): 466-473.
NAITO, Y., 1973. Comparison in colour pattern of two species of harbour seal in adjacentwaters of Hokkaido. Sci. Rep. Whales Res. Inst. 25: 401-310.
SCHEFFER, V. B., 1958. Seals, sea lions and waluses. Stanford University Press, Stanford,
179pp.
T!KHOMIROV, E. A., 1966. The formation and variation of the pelage pattern of the ribbon
seal. Pacific Sci. Inst. of Fisheries and Oceanography 108: 239-241.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

PELAGE PATTERN OF RIBBON SEALEXPLANATION OF THE PLATESPLATE IThe developmental stages of the color pattern. From top stage I (pup), stage II(1 year old), stage III (2 years old), stage IV (3 years old). Left, males; right,
females.
PLATE II
The schematic diagrams of male pelage pattern.
year old, 2 years old and 3 years old.

From top to below 0 year old, 1

PLATE IIIThe schematic diagrams of female pelage patterns.
and 2 years old.

From top 0 year old, 1 year old

PLATE IV
The variation of lateral bands. From top, Type I (no connection to other bands),
Type 2 (connection to lumber band), Type 3 (connection to both lumber and headbands).
PLATE VThe variation of the lumber band. Arranged from simple form to more complicatedform from left top to right bottom.
PLATE VI
Examples of adult males which did not show the complete secondary pigmentation.
PLATE VII
The schematic diagrams of the speculated ancestral form, which were devised fromthe developemtal process of the pigmentation.
PLATE VIII
The examples of the small ringed or spotted patterns. The pelages were classified
into three degrees A, B and C according to the numbers of ringed patterns.

Sci. Rep. Whales Res. Inst.,
No. 28, 1976.

197

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Sci. Rep. Whales Res. Inst.,
No. 28, 1976

NAITO AND OSHIMA

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Sci. Rep. Whales Res. Inst.,
No. 28, 1976

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Sci. Rep. Whales Res. Inst.,
No. 28, 1976

PLATE VII

PLATE VIII

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THE SCIENTIFIC REPORTS OF THE WHALES RESEARCHINSTITUTE, TOKYO, JAPANNUMBER 1, JUNE 1948
Akiya, S. and Tejima, S. Studies on digestive enzymf' in whale. 3-7
Akiya, S., Ishikawa, Y., Tejima, S. and Tanzawa, T. Studies on tryptasf' from a whale (Balaenoptera
borealis L. ). 8-10
Akiya, S., Tejima, S. and Ishikawa, Y. Studit>s on the utilization of whale mt>at by the use of pancreatic tryptase of whales. 11-14
Akiya, S. and Kobo, F. The test culture of some microorganisms with whale meat peptone. 15-16
Nakai, T. Chemical studies on the freshness of whale meat. I. Evaluation of freshness and changes inquantity of several kinds of nitrogen in whale meat following deterioration of freshness. 17-26
Nakai, T. Chemical studies on the freshness of whale meat. II. On comparison between whale meatand beef on deterioration of freshn,.ss and autolysis. 27-30
Tawara, T. On the simultaneous extraction of vitamin A-D and vitamin B2 complex from the liver ofa fin whale (Nagasu-Kujira, Balaenoptera physalus L.). 31-37
Tawara, T. Studies on whale blood. I. On the separation of histidine from whalf' blood. 38-40
Nakai, J. and Shida, T. Sinus-hairs of the sei-whale (Balaenoptera borealis). 41-47

NUMBER 2, DECEMBER 1948
Ogawa, T. and Arifuku, S. On the acoustic system in the cetacean brains. 1-20
Yamada, M. Auditory organ of the whalebone whales. (Preliminary rf'port). 21-30
Nakai, T. Chemical studies on the freshness of whale meat. III. Effect of hydrogen-ion concentration
on decrease in freshness and titration curve of whale meat with HCl and Na 2 C0 8• 31-34
Ishikawa, S., Omote, Y. and Soma, Y. Analytical distillation of vitamin A in the whale liver oil. 35-41
Ishikawa, S., Omote, Y. and Kanno, H. Molecular distillation of sperm whale blubber oil. 42-45
Kaneko, A. Molecular distillation of fin whale liver oil. 46-50
Akiya, S. and Takahashi, K. Determination of tryptophane in whale meat. 51-54
Ishikawa, Y. and Tejima, S. Protein digestive power of sperm whale pancreatic enzyme. 55-60
Tsukamoto, S. Experiment on digestion of whale meat by koji-mould. 61-66

NUMBER 3, FEBRUARY 1950
Ogawa, T. and Shida, T. On the sensory tubercles of lips and of oral cavity in the sei and the fin
whale. 1-16
Ohe, T. Distribution of the red marrow in bones of the fin whale. 17-22
Hosokawa, H. On the cetac,.an larynx, with special remarks on the laryngeal sack of the sei whale andthe aryteno-epiglottideal tube of the sperm whale. 23-62
Akiba, T., Tsuchiya, T., Umehara, M. and Natsume, Y. Bacteriological studies on freshness of whale
meat. (Report No. 1). 63-70
Ishikawa, Y. Protein digestive power of sperm whale pancreatic enzyme. II. 71-78
Mori, T. and Saiki, M. Properties of fats and oils contained in various parts of a sperm whale body.
79-84
Tawara, T. and Fukazawa, R. Studies on kitol. I. Pn•paration of kitol from whale liver oil. 85-88
Tawara, T. and Fukazawa, R. Studies on kitol. II. Influence of kitol fraction on the determinationof the International Unit of Vitamin A. 89-91
Tawawa, T. and Fukazawa, R. Studies on kitol. III. The effect of sunlight, air and heat on thf' vitamin A and kitol fractions. 92-95
Tawara, T. On the respiratory pigments of whale (Studies on whale blood II.). 96-101

ii
Yoshida, M. Research on methionine in whale. 102-105
Mizue, K. Factory ship whaling around Bonin Islands in 1948. 106-118
Mizue, K. and Jimbo, H. Statistic study of foetuses of whales. 119-131
Nishiwaki, M. and Hayashi, K. Biological survey of fin and blue whales taken in the Antarctic season
1947-48 by the Japanese fleet. 132-190

NUMBER 4, AUGUST 1950
Omura, H. On the body weight of sperm and sei whales located in the adjacent waters of Japan. 1-13
Omura, H. Diatom infection on blue and fin whales in the Antarctic whaling area V (the Ross Sea
area). 14-26
Omura, H. Whales in the adjacent waters of Japan. 27-113
Nishiwaki, M. Determination of the age of Antarctic blue and fin whales by the colour changes incrystalline lens. 115-161
Nishiwaki, M. Age characteristics in baleen plates. 162-183
Nishiwaki, M. On the body weight of whales. 184-209

NUMBER 5, JUNE 1951
Akiba, T., Umehara, M. and Natsume, Y. Bacteriological studies on freshness of whale meat. (Report
No. II.). 1-4
Hosokawa, H. On the pelvic cartilages of the Balaenoptera-foetuses, with remarks on the specifical andsexual difference. 5-15
Ohc, T. Iconography on the abdominal cavity and viscera of the Balaenoptera, with special remarks
upon the peritoneal coverings .. 17-39
Akiya, S. and Hoshino, O. Isolation of histidine from whale blood using 3, 4-dichlorobenzene sulfonicacid. 41-47
Tawara, T. and Fukazawa, R. Studies on kitol. IV. Purification of kitol by chromatographie. 49-51
Ishikawa, S., Omote, Y. and Okuda, H. Substances related to vitamin A in the whale liver oil. 53-59
Ishikawa, S., Omote, Y., Kijima, M. and Okuda, H. Thermal decomposition of kitol. 61-69
Mizue, K. Grey whales in the east sea area of Korea. 71-79
Mizue, K. Food of whales (In the adjacent waters of Japan). 81-90
Nishiwaki, M. and Ohe, T. Biological investigation on blue whales (Balaenoptera musculus) and fin whales(Balaenoptera physalus) caught by the Japanese Antarctic whaling fleets. 91-167

NUMBER 6, DECEMBER 1951
Hosokawa, H. On the extrinsic eye muscles of the whale, with special remarks upon the innervationand func6on of the musculus retractor bulbi. 1-33
Murata, T. Histological studies on the respiratory portions of the lungs of cetacea. 35-47
Kojima, T. On the brain of the sperm whale (Physeter catodon L.). 49-72
Mizue, K. and Murata, T. Biological investigation on the whales caught by the Japanese Antarctic
whaling fleets season 1949-50. 73-131
Nishiwaki, M. On the periodic mark on the baleen plates as the sign of annual growth. 133-152
Nishiwaki, M. and Hibiya, T. On the sexual maturity of the sperm whales (Physeter catodon) found in
the adjacent waters of Japan (I). 153-165
Nakai, T. Chemical studies on freshness of whale meat. IV. Some informations of Archomobacter ubiquitum
isolated from whale carcass. 167-176
Nakai, T. and Ono, H. The effects of electric shock and fatigue on post-mortem changes in muscle.
177-185

iii
Omote, Y. Complete recovery of vitamin A from molecular distillation residue of whale-liver oil. 187191
Omote, Y. Chemical structure of kitol (I). Double bonds and hydroxyl groups. 193-198
Hirata, M. Experimental investigation on flattened head harpoon. An attempt for restraining ricochet. 199-207

NUMBER 7, JULY 1952
Ogawa, T. On the cardiac nerves of some cetacea, with special reference to thos<" of Berardius bairdii
Stejnegn 1-22
Akiya, S., Hoshino, O. and Motohashi, N. On an attempt to preserve whale meat freshness with 5nitro-furfuriden aminoguanidine from decay. 23-30
Akiya, S. and Sawamura, R. Colorimetric determination of 5-nitro-2-furfuridene aminoguanidine. 31-36
Tomiyama, S. and Takao, M. Studies on utilization of higher fatty alcohol from sperm whale oil. 3746
Omote, Y. A rapid method for the separate determination of vitamin A and kitol in the whale-liveroil. 47-50
Arai, Y. and Sakai, S. Whale meat in nutrition. 51-67
Yamaguchi, K. and Fujino, K. On the serological constitution of striped dolphin (Prodelphinus caeruleoalbus (Meyen)) (I). 67-77
Nishimoto, S., Tozawa, M. and Kawakami, T. Food of sei whales (Balaenoptera borealis) caught in the
Bonin Island waters. 79-85
Nishiwaki, M. On the age-determination of Mystacoceti, chiefly blue and fin whales. 87-119
Nishiwaki, M. and Hibiya, T. On the sexual maturity of the sperm whales (Physeter catodon) found in
the adjacent waters of Japan (II). 121-124
Ohno, M. and Fujino, K. Biological investigation on the whales caught by the Japanese Antarctic
whaling fleets, season 1950/51. 125-188

NUMBER 8, JUNE 1953
Yamada, M. Contribution to the anatomy of the organ of hearing of whales. 1-79
Omura, H. Biological study on humpback whales in the Antarctic whaling areas IV and V. 81-102
Fujino, K. On the serological constitutions of the sei-, fin-, blue- and humpback-whales (I). 103-125
Ogawa, T. On the presence and disappearance of the hind limb in the cetacean embryos. 127-132
Nishiwaki, M. and Yagi, T. On the age and the growth of teeth in a dolphin (Prodelphinus caeruleo·
albus). (I). 133-146
Kakuwa, Z., Kawakami, T. and Iguchi, K. Biological investigation on the whales caught by the Japanese Antarctic whaling fleets in the 1951-52 season. 147-213
Nishiwaki, M. Hermaphroditism in a dolphin (Prodelphinus caeruleo-albus). 215-218

NUMBER 9, JUNE 1954
Akiya, S., Hoshino, 0. and Motohashi, N. Attempt to preserv,. freshness of whale meat with germicides. II. 1-10
Ogawa, T. On the musculature of the sinus venosus and its continuation with the so-called conducting
system of the whale's heart. 11-35
Yamada, M. Some remarks on the pygmy sperm whale, Kogia. 37-58
Yamada, M. An account of a rare porpoise, Feresa Gray from Japan. 59-88
Omura, H. and Fujino, K. Sei whales in the adjacent waters of Japan. II. Further studies on theexternal characters. 89-103
Fujino, K. On the serological constitution of the sperm- and baired beaked-whales (I) Blood groups of

iv
the sperm- and haired beaked-whales. 105-120
Fujino, K. On the body proportions of the fin whales (Balaenoptera physalus (L)) caught in the northern
Pacific Ocean (I) (Preliminary report). 121-163
Nishiwaki, M., Hibiya, T. and Kimura, S. On the sexual maturity of the sei whale of the Boninwaters. 165-1 77
Uda, M. Studies of the relation between the whaling grounds and the hydrographical conditions (I).
179-187

NUMBER 10, JUNE 1955
Hosokawa, H. Cross-sections of a 12-mm. dolphin embryo. 1-68
Nemoto, T. White scars on whales (I) Lamprey marks. 67-77
Omura, H. and Nemoto, T. Sei whales in the adjacent waters of Japan. III. Relation between movement and water temperature of the sea. 79-87
Omura, H., Fujino, K. and Kimura, S. Beaked whale Berardius bairdi of Japan, with notes of ;:::,iphiuscavirostris. 89-132
Fujino, K. On the body weight of the sei whales located in the adjacent waters of Japan (II). 133141
Nishiwaki, M. On the sexual maturity of the Antarctic male sperm whale (Physeter catodon L.). 143149
Ohta, K., vVatarai, T., Oishi, T., Ueshiba, Y., Hirose, S., Yoshizawa, T., Akikusa, Y., Sato, M. andOkano, K. Composition of fin whale milk. 151-167

NUMBER 11, JUNE 1956
Omura, H. and Sakiura, H. Studies on the little piked whale from the coast of Japan. 1-37
Nishiwaki, M., Hibiya, T. and Kimura, S. On the sexual maturity of the sperm whale (Plryseter catodon)
found in the North Pacific. 39-46
Fujino, K. On the body proportions of the sperm whales (Physeter catodon). 47-83
Fujino, K. On the serological constitution of the fin whales II. Further studies on blood groups. 8598
Nemoto, T. On the diatoms of the skin film of whales in the northern Pacific. 99-132
Hoshina, T. and Sugiura, Y. On a skin disease and a nematode parasite of a dolphin, Tursiops truncatus(Montagu, 1821). 133-138
Iwai, E. Descriptions on unidentified species of dibranchiate cephalopods. I. An oegopsiden squid belonging to the genus Architeuthis. 139-151
Iwai, E. Descriptions on unidentified species of dibranchiate cephalopods. II. A cranchiidae squid of thegenus Taonius. 153-161
Uda, M. and Nasu, K. Studies of the whaling grounds in the northern sea-region of the Pacific Ocean
in relation to the meteorological and oceanographic conditions. (Part I). 163-179
Kimura, S. and Nemoto, T. Note on a minke whale kept alive in aquarium. 181-189
Ishikawa, Y. A characteristic property of whale oils concerning the absorption of gases. I. On theabsorption of carbon dioxide by whale oils. 191-213

NUMBER 12, JUNE 1957
Omura, H. Osteological study of the little piked whale from the coast of Japan. 1-21
Nishiwaki, M. Age characteristics of ear plugs of whales. 23-32
Nemoto, T. Foods of baleen whales in the northern Pacific. 33-89
Nasu, K. Oceanographic conditions of the whaling grounds in the waters adjacent to Aleutian Islands
and the Bering Sea in summer of 1955. 91-101
Kimura, S. The twinning in southern fin whales. 103-125

v
Ichihara, T. An application of linl'ar discriminant function to external measurements of fin whale.
127-189
Nishiwaki, M. Very small embryo of cetacea. 191-192
Nishiwaki, M. One-eyed monster of fin whale. 193-195
Ogawa, T. and Kamiya, T. A case of the cachalot with protruded rudimentary hind limbs. 197-208
Uda, M. and Dairokuno, A. Studies of the relation between the whaling grounds and the hydrographic
conditions. II. A study of the relation between the whaling grounds off Kinkazan and the boundary of water masses. 209-224
Abe, T. Notes on fishes from the stomachs of whales taken in the Antarctic. I. Xenocyttus nemotoi, a
new genus and n<"w species of zeomorph fish of the subfamily Oreosonimae Goode and Bean, 1895.
225-233
Tsuyuki, H. On the oils contained in various blubbers of northern elephant seal, Mirounga angustirostris.
235-240NUMBER 13, SEPTEMBER 1958
Omura, H. North Pacific right whale. 1-52
Nishiwaki, M. and Kamiya, T. A beaked whale Mesoplodon stranded at Oiso Beach, Japan. 53-83
Nishiwaki, M. and Randa, C. Killer whales caught in the coastal waters off Japan for recent 10 years.
85-96
Ohsumi, S. (Kimura), Nishiwaki, M. and Hibiya, T. Growth of fin whale in the northern Pacific.
97-133
Nishiwaki, M., Hibiya, T. and Ohsumi, S. (Kimura). Age study of sperm whale based on reading of
tooth laminations. 135-153
Nishiwaki, M., Ichihara, T. and Ohsumi, S. (Kimura). Age studies of fin whale based on ear plug.
155-169
Fujino, K. On the serological constitution of fin whale. III. Human B blood group substances in erythrocytes and some notes on anti-fin Ju specific antibodies. 171-184
Nemoto, T. Cocconeis diatoms infected on whales in the Antarctic. 185-191
Nemoto, T. and Nasu, K. Thysanoessa macrura as a food of baleen whales in the Antarctic. 193-199
Ichihara, T. Gray 'whale observed in the Bering Sea. 201-205
Ohsumi, S. (Kimura). A descendant of Moby Dick or a white sperm whale. 207-209
Nasu, K. Deformed lower jaw of sperm whale. 211-212.
Omura, H. Note on embryo of Baird's beaked whale. 231-214
Uda, M. and Suzuki, N. Studies of the relation between the whaling grounds and the hydrographic
conditions. III. The averaged conditions of the whaling grounds and their trends of variation during
1946-55. 215-229
Seki, Y. Observations on the spinal cord of the right whale. 231-251
Kamiya, T. How to count the renculi of the cetacean kidneys, with special regard to the kidney ofthe right whale. 253-267
Hosokawa, H. and Sekino, T. Comparison of the size of cells and some histological formations between
whales and man. 269-301
Ogawa, T., Tsunoda, T. and Osawa, M. Amino acid composition of whale meat. 303-307
Ishikawa, Y. A characteristic property of whale oils concerning the absorption of gases. II. On theabsorption of nitrogen by whale oils. 309-321
Tsuyuki, H. Component fatty acids of northern elephant seal oil. 323-332

NUMBER 14, SEPTEMBER 1959
Omura, H. Bryde's whale from the coast of Japan. 1-33
Nishiwaki, M. and Kamiya, T. Mesoplodon stejnegeri from the coast of Japan.
Nishiwaki, M. Humpback whales in Ryukyuan waters. 49-87

35-48

vi
Cushing, John E., Fujino, K. and Takahashi, K. Glycerol-freezing technique as an aid in blood typingof whales. 89-100
Fujino, K. and Cushing, John E. Blood typing of dried whale erythrocytes with 1 31 1 labelled antibody.
101-106lchihara, T. Formation mechanism of ear plug in baleen whales in relation to glove-finger. 107-135
Nasu, K. Surface water condition in the Antarctic whaling Pacific area in 1956-57. 137-143
Ohsumi, S. (Kimura). A deformed fin whale foetus. 145-147
Nemoto, T. Food of baleen whales with reference to whale mevements. 149-290
Yamada, M. and Yoshizaki, F. Osseous labyrinth of cetacea. 291-304
Nakai, T. Distribution of amino acid in proteins from various parts of whale body. 305-326

NUMBER 15, NOVEMBER 1960
Nishiwaki, M. Ryukyuan humpback whaling in 1960. 1-16
Ohsumi, S. Relative growth of the fin whale, Balaenoptera physalus (Linn.). 17-84
Fujino, K. Immunogenetic and marking approaches to identifying subpopulations of the North Pacificwhales. 85-142
Nasu, K. Oceanographic investigation in the Chukchi Sea during the summer of 1958. 143-158
Tokita, K. and ECG Research Group. Electrocardiographical studies on bottlenosed dolphin (Tursiops
truncatus ). 159-165

NUMBER 16, MARCH 1962
Omura, H. Bryde's whale occurs on the coast of Brazil. 1-5
Omura, H. Further information on Bryde's whale from the coast of Japan. 7-18
Nishiwaki, M. Ryukyuan whaling in 1961. 19-28
Nemoto, T. A secondary sexual character of fin whales. 29-34
Omura, H., Nishiwaki, M., Ichihara, T. and Kasuya, T. Osteological note of a sperm whale. 35-45
Jchihara, T. Prenatal dead foetus of baleen whales. 47-60
Nishiwaki, M. Mesoplodon bowdoini stranded at Akita Beach, Sea of Japan. 61-77
Nishiwaki, M. Observation on two mandibles of j'vfesoplodon. 79-82
Sinclair, John. An early dolphin embryo (Stenella caeruleoalbus) in serial sections. 83-87
Nemoto, T. Food of baleen whales collected in recent Japanese Antarctic whaling expeditions. 89-103
Uda, M. Subarctic oceanography in relation to whaling and salmon fisheries. 105-119

NUMBER 17, FEBRUARY 1963
Nishiwaki, M., Ohsumi, S. and Maeda, T. Change of form in the sperm whale accompanied withgrowth. 1-14
Ohsumi, S., Kasuya, T. and Nishiwaki, M. The accumulation rate of dentinal growth layers in the
maxillary tooth of the sperm whale. 15-35
Ichihara, T. Photometric method for counting laminae in ear plug of baleen whale. 37-48
Yoshikawa, T. and Suzuki, T. The lamination of the masseter of the humpback whale. 49-52
Fujino, K. Intra-uterine selection due to maternal-foetal in compatibility of blood type in the whales.
53-65
Cushing, John E., Fujino, K. and Calapric~, N. The Ju blood typing system of the sperm whale andspecific soluble substances. 67-77
Ni>moto, T. New records of sperm whales with protruded rudimentary hind limbs. 79-81
Nemoto, T. and Nasu, K. Stones and other aliens in the stomachs of sperm whales in the Bering Sea,
83-91
Nishiwaki, M. Taxonomical consideration on genera of Delphinidae. 93-103

vii
Nasu, K. Oceanography and whaling ground in the subarctic region of the Pacific Ocean. 105-155
Nemoto, T. Some aspects of the distribution of Calanus cristatus and C. plumchrus in the Bering and its
neighbouring waters, with reference to the feeding of baleen whales. 157-170
Tsuyuki, H. and Naruse, U. Studies on the oil of black right whale in the northern Pacific Ocean.
171-190
Yagi, T., Nishiwaki, M. and Nakajima, M. A preliminary study on the method of time marking withleadsalt and tetracycline on the teeth of northern fur seal. 191-195

NUMBER 18, MARCH 1964
Fujino, K. Fin whale subpopulations in the Antarctic whaling areas II, III and IV. 1-27
Ichihara, T. Prenatal development of ear plug in baleen whales. 29-48
Ohsumi, S. Examination on age determination of the whale. 49-88
Nemoto, T. School of baleen whales in the feeding areas. 89-110
Okutani, T. and Nemoto, T. Squids as the food of sperm whales in the Bering Sea and Alaskan Gulf.
111-122
Ohsumi, S. Comparison of maturity and accumulation rate of corpora albicantia between the left andright ovaries in cetacea. 123-148
Omura, H. A systematic study of the hyoid bones in the baleen whales. 149-170
Nishiwaki, M. Revision of the article "Taxonomical consideration on genera of Delphinidae" in No. 17.
171-172
Tsuyuki, H. and Naruse, U. Studies on the lipids in brain of black right whale in the northern Pacific
Ocean. 173-180

NUMBER 19, APRIL 1965
Ohsumi, S. Reproduction of the sperm whale in the north-west Pacific. 1-35
Kasuya, T. and Ichihara, T. Some informations on minke whales from the Antarctic. 37-43
Nemoto, T. and Kasuya, T. Foods of baleen whales in the Gulf of Alaska of the North Pacific. 45-51
Nishiwaki, M., Nakajima, M., and Kamiya, T. A rare species of dolphin (Stenella attenuata) from Arari,Japan. 53-64
Nishiwaki, M., Kasuya, T., Tobayama, T., Kamiya, T. and Nakajima, M. Feresa attenuata captured at
the Pacific Coast of Japan in 1963. 65-90
Nakajima, M. and Nishiwaki, M. The first occurrence of a porpoise (Electra electra) in Japan. 91-104
Hosokawa, H. and Kamiya, T. Sections of the dolphin's head (Stenella caeruleoalba). 105-133
Ohsumi, S. A dolphin (Stenella caeruleoalba) with protruded rudimentary hind limbs. 135-136

NUMBER 20, SEPTEMBER 1966
Ohsumi, S. Sexual segregation of the sperm whale in the North Pacific. 1-16
Ichihara, T. Criterion for determining age of fin whale with reference to ear plug and baleen plate.
17-82
Kasuya, T. Caryotype of a sei whale. 83-88
Kasuya, T. and Ohsumi, S. A secondary sexual character of. the sperm whale. 89-94
Nishiwaki, M. and Norris, K. S. A new genus, Peponocephala, for the odontoceti cetacean species Electra
electra. 95-100
Nishiwaki, M., Nakajima, M. and Tobayama, T. Preliminary experiments for dolphin marking. 101107
Neinoto, T. Thysanoessa euphausiids, comparative morphology, allomorphosis and ecology. 109-155
Nasu, K. Fishery oceanographic study on the baleen whaling grounds. 157-210
Ichihara, T. and Nishiwaki, M. External measurements and weight of a southern elephant seal. 211212

viii
Tsuyuki, H. and Itoh, S.
221

Studies on the oils contained in blubber of a southern elephant seal.

213-

NUMBER 21, JUNE 1969
Omura, H., Ohsumi, S., Nemoto, T., Nasu, K. and Kasuya, T. Black right whales in the North Pacific.
1-78
Nishiwaki, M. and Hasegawa, Y. The discovery of the right whale skull in the Kisagata shell bed.
79-84
Ohsumi, S. Occurrence and rupture of varginal band in the fin, sei, and blue whales. 85-94
Hosokawa, H., Igarashi, S., Kamiya, T. and Hirosawa, K. Morphological characteristics and myelinization of acoustic system in the dolphins (Stenella caeruleoalba). 95-123
Mo!, T. and van Bree, P.J.H. A short contribution to the history of whaling in Japan during the l 7th
century. 125-129
Tsuyuki, H. and Itoh, S. Fatty acid composition of finless porpoise oil. 131-135
Tsuyuki, H. and Itoh, S. Fatty acid composition of many toothed pilot whale oil. 137-141

NUMBER 22, JUNE 1970
Omura, H., Ichihara, T. and Kasuya, T. Osteology of pygmy blue whale with additional information
on external and other characteristics. 1-27
Nishiwaki, M. and Kasuya, T. Recent record of gray whale in the adjacent waters of Japan and aconsideration on its migration. 29-37
Kasuya, T. and Rice, D. W. Note on baleen plates and on arrangement of parasitic barnacles of graywhale. 39-43
Nishiwaki, M. and Kasuya. T. A Greenland right whale caught at Osaka Bay. 45-62
Nasu, K. and Masaki, Y. Some biological parameters for stock assessment of the Antarctic sei whale.
63-74
Ohsumi, S., Masaki, Y. and Kawamura, A. Stock of the Antarctic minke whale. 75-125.
Kawamura, A. Food of sei whale taken by Japanese whaling expeditions in the Antarctic season 1967/
68. 127-152
Nemoto, T. and Yoo, K. I. An amphipod, Parathemisto gaudichaudii as a food of the Antarctic sei whale.
153-158
Tobayama, T., Uchida, S. and Nishiwaki, M. Twin foetuses from a blue white dolphin. 159-162
Machida, S. A sword-fish sword found from a North Pacific sei whale. 16:3-164
Tsuyuki, H. and Itoh, S. Fatty acid components of black right whale oil by gas chromatography. 165170

NUMBER 23, SEPTEMBER 1971
Ohsumi, S. Some investigations on the school structure of sperm whale. 1-25
Kawamura, A. Influence of chasing time to stomach contents of baleen and sperm whales. 27-36
Kasuya, T. Consideration of distribution and migration of toothed whales off the Pacific coast of Japan
based upon aerial sighting record. 37-60
Omura, H. A comparison of the size of vertebrae among some species of the baleen whales with specialreference to whale movements. 61-69
Omura, H., Nishiwaki, M. and Kasuya, T. Further studies on two skeletons of the black right whalein the North Pacific. 71-81
Nishiwaki, M. and Kasuya, T. Osteological note of an Antarctic sei whale. 83-89
Hosokawa, H. and Kamiya, T. Some observations on the cetacean stomachs, with special considerations
on the feeding habits of whales. 91-101

ix
Lugassy, A. A., Korostoff, E. and "Rabinowits, J. L. Influence of incremental lines upon the compressive
strength of sperm whale dentin. 103-110
Nishiwaki, M. and Oguro, N. Baird's beaked whales caught on the coast of Japan in recent 10 years.
111-122
Mizue, K., Nishiwaki, M. and Takemura, A. The underwater sound of Ganges river dolphins (Platanista
gangetica). 123-128
Kasuya, T. and Nishiwaki, M. First record of Mesoplodon densirostris from Formosa. 129-137
Kawamura, A. and Kashita, K. A rare double monster of dolphin, Stenella caeruleoalba. 139-140
Tsuyuki, H. and Itoh, S. Fatty acid components of Ganges river dolphin oil. 141-147

NUMBER 24, NOVEMBER 1972
Omura, H. An osteological study of the Cuvier's beaked whale, :(:,iphius cavirostris, in the northwest
Pacific. 1-34
Nishiwaki, M. and Oguro, N. Catch of the Cuvier's beaked whales off Japan in recent years. 35-41
Nishiwaki, M., Kasuya, T., Kureha, K. and Oguro, N. Further comments of Mesoplodon gingkodens.
43-56
Kasuya, T. Growth and reproduction of Stenella caeruleoalba based on the age determination by meansof dentinal growth layers. 57-79
Kasuya, T. and Oguro, N. A new tagging method of dolphins. 81-85
Kasuya, T. Some informations on the growth of the Ganges dolphin with a comment on the Indus
dolphin. 87-108
Kasuya, T. and Aninul Haque', A.K.M. Some informations on the distribution and seasonal movementof the Ganges dolphin. 109-115
Tsuyuki, H. and ltoh, S. Fatty acid component of various blubber oil of Ganges River dolphin. 117-125
Naito, Y. and Nishiwaki, M. The growth of two species of the harbour seal in the adjacent waters of
Hokkaido. 127-144.
lchihara, T. and Yoshida, K. Diving dt>pth of northern fur seals in the feeding time. 145-148

NUMBER 25, SEPTEMBER 1973
Kasuya, T. Systematic consideration of recent toothed whales based on the morphology of tympanoperiotic bone. 1-103
Omura, H. A review of pelagic whaling operations in the Antarctic based on the effort and catch datain 10° squares of latitude and longitude. 105-203
Nasu, K. Results of whale sighting by Chiyoda Mam No. 5 in the Pacific sector of the Antarctic andTasman Sea in the 1966/67 season. 205-217
Kawamura, A. Food and feeding of sei whale caught in the waters south of 40°N in the North Pacific.
219-236.
Ohsumi, S. Find of marlin spear from the Antarctic minke whales. 237-239
Seki, Y. An anatomical study on the lower extension of the dorsal vagal nucleus to the upper cervical
cord in the sperm whale. 241-249
Tobayama, T., Nishiwaki, M. and Yang, H. C. Records of the Fraser's Sarawak dolphin (Lagenodelphis
hosei) in the western North Pacific. 251-263
Miyazaki, N., Kusaka, T. and Nishiwaki, M. Food of Stenella caeruleoalba. 265-275
Nishiwaki, M. Possible vestigial teats of killer whale. 277-278
Williamson, G. R. Counting and measuring baleen and ventral grooves of whales. 279-292
Tsuyuki, H. and ltoh, S. Fatty acid component of blubber oil of Amazon River dolphin. 293-299
Naito, Y. Comparison in colour pattern of two species of harbour seal in adjacent waters of Hokkaido.
301-310x

NUMBER 26, NOVEMBER 1974
Omura, H. Possible migration route of the gray whale on the coast of Japan. 1-14
Satake, Y. and Omura, H. A taxonomic study of the minke whale in the Antarctic by means of hyoidbone. 15-24
Kawamura, A. Food and feeding ecology in the southern sei whale'. 25-144
McCann, C. Body scarring on cetacea-odontocetes. 145-155
Kasuya, T., Miyazaki, N. and Dawbin, W. H. Growth and reproduction of Stene/la attenuata in the
Pacific coast of Japan. 157-226
Miyazaki, N., Kasuya, T. and Nishiwaki, M. Distribution and migration of two species of Stene/la in
the Pacific coast of Japan. 227-243
Kamiya, T. and Pirlot, P. Brain morphogenesis in Stene/la coeruleoalba. 245-253
Castello, H.P., Torno, A. P. and Panizza, J. S. First Antarctic record of a killer whale stranding. 255-

258
Kamiya, T. and Miyazaki, N. A malformed embryo of Stenella coeruleoalba. 259-263
Kamiya, T. and Yamasaki, F. Organ weights of Pontoporia blainvillei and Platanista gangetica (Platanistidae). 265-270
Machida, S. Surface temperature field in the Crozet and Kerguelen whaling grounds. 271-287
Machida, S. The voyage of the Konan Maru No. 16 to the Antarctic whaling grounds. 289-302
Itoh, S. and Tsuyuki, H. Fatty acid component of different blubber oil of finless porpoise. 303-306
Itoh, S. and Tsuyuki, H. Fatty acid component of Senegal manatee fats. 309-311.
Naito, Y. The hyoid bones of two kinds of harbour seals in the adjacent waters of Hokkaido. 313-320

NUMBER 27, SEPTEMBER 1975
Omura, H. Osteological study of the minke whale from the Antarctic. 1-36
Williamson, G. R. Minke whales off Brazil. 37-59
Kawamura, A. A consideration on an available source of energy and its cost for locomotion in fin
whales with special reference to the seasonal migrations. 61-79
Kasuya, T. and Nishiwaki, M. Recent status of the population of Indus dolphin. 81-94
Kasuya, T. Past occurrence of Globicephala melaena in the western North Pacific. 95-108
McCann, C. A study of the genus Berardius Duvernoy. 111-137
Nishiwaki, M. and Kureha, K. Strange organ in the anal region of the finless porpoise. 139-140
Machida, S. Distribution of sperm whale catches in the southern Indian Ocean. 141-159

NUMBER 28, OCTOBER 1976
Kawamura, A. and Satake, Y. Preliminary report on the geographical distribution of the
Bryde's whale in the North Pacific with special reference to the structure of the filtering
apparatus. 1-35
Pivorunas, A. A mathematical consideration on the function of baleen plates and their fringes.

37-55
Omura, H. and Kasuya, T. Additional information on skeleton of the minke whale from theAntarctic. 57-68
Omura, H. A skull of the minke whale dug out from Osaka. 69-72
Kasuya, T. Reconsideration of life history parameters of the spotted and striped dolphins basedon cementa! layers. 73-106
McCann, C. Notes on the foetal skull of Mesoplodon stejnegeri. 107-117
Gianuca, N. M. and Castello, H.P. First record of the southern bottlenose whale, Hyperoodon
planifrons from Brazil. 119-126

xi
Brownell, R. L. Jr., Aguayo L., A. and Torres N., D. A Shepherd's beaked whale, Tasmacetus
shepherdi, from the eastern South Pacific. 127-128
Brownell, R. L. Jr. and Praderi, R. Records of the delphinid genus Stenella in western South
Atlantic waters. 129-135
Yamasaki, F., Satomi, H. and Kamiya, T. An observation on the papillary projections at the
lingual margin in the striped dolphin. 137-140
Kasuya, T. and Miyazaki, N. An observation of epimeletic behavior of Lagenorhyncus obliquidens.
141-143
Kawakami, T. Squids found in the stomach of sperm whales in the northwestern Pacific. 145151
Leung, Y. M. Life cycle of Cyamus scammoni (Amphipoda: Cyamidae), ectoparasite of gray whale,with a remark on the associated species. 153-160
Kagei, N., Tobayama, T. and Nagasaki, Y. On the helminthum of Franciscana, Pontoporia blainvillei. 161-166
Tsuyuki, H. and Itoh, S. Fatty acid component of lipid of Euphausia superba. 167-174
Naito, Y. The occurrence of the phocid seals along the coast of Japan and possible dispersalof pups. 175-185
Naito, Y. and Oshima, M. The variation in the development of pelage of the ribbon seal withreference to the systematics. 187-197

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