THESCIENTIFIC REPORTS
OF· THE WHALES RESEARCH INSTirfUTE
No. 31

THE WHALES RESEARCH INSTITUTETOKYO·JAPAN.

DECEMBER 1979l!~Res. Inst., No. 31 j~~

THE
SCIENTIFIC REPORTS
OF
THE WHALES REREARCH INSTITUTE

No. 31

THE WHALES RESEARCH INSTITUTETOKYO, JAPANDECEMBER, 1979

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

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE
CONTENTS OF NUMBER 31
Page

KASUYA, T. and K. KuREHA
The population of finless porpoise in the Inland Sea of JapanKASUYA, T. and R. L. BROWNELL, jR
Age determination, reproduction, and growth ofFrnaciscana dolphin Pontoporia
blainvillei . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

45

juRAsz, C. M. and V. P. juRASZ
Feeding modes of the humpback whale, Megaptera novaeangliae, in southeast
Alaska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

69

OMURA, H. and T. KASUYA
A skull of baleen whale dredged from the Inland Sea of Ja pan . . . . . . . . . . . .

85

KAMIYA, T., T. ToBAYAMA and M. NisHIWAKI
Epidermal cyst in the neck of a killer whale . . . . . . . . . . . . . . . . . . . . . . . . . . . .

93

MAJOR, P. F.
An aggressive encounter between a pod of whales and billfish. . . . . . . . . . . . . .

95

KATO, H.
Carotenoid colored minke whale from the Antarctic . . . . . . . . . . . . . . . . . . . . . . 97
KATO, H.
Unusual minke whale with deformed jaw ................................ 101
NAITO, Y. and S. KoNNO
The post breeding distributions of ice-breeding harbour seal (Phoca largha) andribbon seal (Phoca fasciata) in the southern sea of Okhotsk . . . . . . . . . . . . . . . . 105
NAITO, Y.
A record of the bearded seal wandering with special reference to the wandering speed .......................................................... 121
MIYAZAKI, N., K. ITANO, M. FUKUSHIMA, S. KAWAI and K. HONDA
Metals and organochlorine compounds in the muscle of dugong from Sulawesi
Island ................................................................ 125
KAMIYA, T., S. UCHIDA and T. KATAOKA
Organ weights of Dugong dugon ........................................ 129
NisHIWAKI, M., T. KASUYA, N. MIYAZAKI, T. ToBAYAMA and T. KATAOKA
Present ditribution of the dugong in the world . . . . . . . . . . . . . . . . . . . . . . . . . . 133

目 次
粕谷俊雄・呉羽和男
瀬戸内海産スナメリの資源粕谷俊雄・ R
.L
.B
r
o
w
n
e
l
l
,J
r
ラプラタカワイルカの年令査定，繁殖，生長

45

J
u
r
a
s
z
,C
.M.andV
.P
.J
u
r
a
s
z
南アラスカにおけるサドワクジラの摂餌行動

69

大村秀雄・粕谷俊雄
瀬戸内海で得られたヒゲ鯨の頭骨．．．．．．．．．．．．．．．．．．．．．．．

8
5

神谷敏郎・鳥羽山照夫・西脇島治
シャチの表皮嚢胞．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

93

Major,P.F.
クジラとカジキの闘争

95

加藤秀弘
南氷洋で捕獲されたカロチン体色のコイワシクジラ

97

加藤秀弘
顎奇形のコイワシクジラについて．．．．．．．．．．．．．．．．．．．．．．．

1
0
1

内藤靖彦・紺野繁幸
オホーツク海産ゴマフアザラシとクラカケアザ、ラシの繁殖後の分布．．．．．．．． 1
05
内藤靖彦
千葉県沿岸に出現したアゴヒゲアザ、ラシの移動と移動速度．．．．．．．．．．．． 1
2
1
宮崎信之・板野一臣・福島実・川合真一郎・本国克久
スラウェシィ島で捕獲したジュゴンの筋肉中における重金属及び有機塩素系化合物． 1
2
5
神谷敏郎・内田詮三・片岡照男
ジュゴンの臓器重量．．．．．．．．．．．．．．．．．．．．．．．．．．．．． 1
2
9
西脇昌治・粕谷俊雄・宮崎信之・鳥羽山照夫・片岡照男
ジュゴンの最近の分布．．．．．．．．．．．．．．．．．．．．．．．．．．．． 1
3
3

fi
＼
＼

THE POPULATION OF FINLESS PORPOISE
IN THE INLAND SEA OF JAPANTOSHIO KASUYA
Ocean Research Institute, University of Tokyo, TokyoAND
KAZUO KUREHA
Himeji Aquarium, Himeji, Hyogo

ABSTRACTThe observation of 1,194 finless porpoises made through 11,549 km ofsighting cruises in the Inland Sea and some ancillary observations provided
the following informations. The porpoise migrates annually to and from the
Pacific coast mainly through the two passes at the eastern Inland Sea. The
highest density (4,900 individuals) is found in April at the beginning of parturition season, and the lowest (1,600) in early winter. The ratios of solitary
adults, of solitary calves, and of cows with calf show seasonal fluctuation,
and allow the analyses of the seasonality of reproduction. Gestation last for
about 11 months. Parturition occurs between April and August with apossible peak in April and May. Most of the cows with calf born in April
and May are suspected to leave the Inland Sea in summer months. Weaning
occurs from December to June after a nursing period ranging from 6 to 15
months. Pregnancies in two contiguous years are not frequent. A 2-year
breeding cycle seems to be most common. Annual production of about
870 calves (both sexes), and gross annual reproductive rate of 17.9% are provisionally estimated for the individuals in the Inland Sea.
INTRODUCTION

On the Pacific coast of Japan, the finless porpoise, Neophocaena phocaenoides (G.
Cuvier, 1829), ranges from the west coast of Kyushu, through Inland Sea, Ise Bay,and Tokyo Bay, to the Sendai Bay (Anon., 1965; Kuroda, 1940; Mizue et al., 1965,
1968; Nakajima, 1963; Ogawa, 1950). Though the incidental catch of the species
once numerous in the Tachibana Bay in the western Kyushu (Mizue et al., 1965)
has ceased by the change of the fishing method (K. Mizue, pers. comm.), small
number of incidental catch and strandings are still common in the above range.
The confirmed northern limit of the range is at the Sendai Bay (38°20'N, 141°15'E),
but the species is considered to migrate further north (Ogawa, 1950). The species
is often trapped in set nets or sighted in the Sendai Bay in June and July, but it isabsent in winter season (T. Shimoyama, pers. comm.). The distribution of thespecies in the Sea of Japan is not confirmed.
The Inland Sea is a well known, and possibly the largest habitat of the finlessSci. Rep. Whales Res. Inst.,

No. 31, 1979, 1-44

2

KASUYA AND KUREHA

porpoise in Japan. The species is legally protected since 1930 as a natural monument. However the protection covers only the porpoise in a 1.5 km radius witha center at the southern tip (34°18.3'N, 132°57.l'E) of Awashima Island near
Takehara City. The reason of the protection is described in Kaburagi (1932).
Namely the angling fishermen of Tadanoumi Town near Awashima used to use
the feeding finless porpoise as an indicator of a kind of fish, Chrysophrys major Temminck and Schlegel, which is believed to feed on small fish Ammodytes personatus
Girard as the finless porpoise supposedly does. This fishery, operated in winterseason, ceased about 10 years ago by the disappearance of Ammodytes in the area (S.
Shiromoto, Manager of Tadanoumi Fishermens Cooperative Union, pers. comm.).
In recent years the pollution of the Inland Sea has progressed, and the increased frequency of red tide and gradual change of the fish fauna is indicated(Hoshino, 1972). However the Inland Sea is still a very productive ground offisheries and aquiculture. The fishery production, excluding aquiculture, in 1977
was 181,902 tons of fish and 102,385 tons of invertebrates and algae (Chugoku
Shikoku Noseikyoku, 1978). Though a law was established in 1973 to regurate
the amount of the pollutant discharged in the Inland Sea and the regulation was
intensified in recent years, there is no indication of improvement of the situation(Anon., 1978).
Since the catch of the finless porpoise is not practically regulated in Japan,
the possibly small population of this coastal species might be damaged if there
occurs a fishery for the finless porpoise in response to the increase of the demandof live specimens for aquariums. Furthermore the population will not be freefrom the influence of the pollution progressing in the region. The present study
was intended to analyse the distribution, abundance, seasonal movement, andreproduction of the finless porpoise in the Inland Sea, and to provide the basic
biological data necessary for the conservation of the species.
MATERIALS AND METHOD

Description of the Inland Sea and area division
The present study covers the Inland Sea proper. It is an area of about
14,300 km 2 of water with about 3,000 islands scattered in it, and is connected toopen sea or other bay by four narrow passes.
The Kanmon Pass is situated at the northwest and opens to the Sea ofJapan.
It is the narrowest of the four passes, with the minimum width of 0.6 km, depthof 19 m, and maximum current of 8.2 knots.
The Hayasui Pass at the southwest entrance opens to the Bungo Channel
which is connected to the Pacific. It is the widest of the four passes, 11.5 km
wide and 186 m deep. The maximum current is 6 knots.
The Naruto Pass opening to the Kii Channel at the southeast corner of theInland Sea has the maximum current of 10.6 knots. The minimum width is 1.3 km,
and the maximum depth at the place is 65 m.
The Akashi Pass connects to the Osaka Bay, which is another small inland
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

Sea of Japan..

3

Honshu0(")(")

Pacific Ocean

Kyushu

131°

132°

133°

134°

135°E

Fig. 1. Geography of the Inland Sea ofJapan. Numeral indicates the area number
used in this study. The boundary between the strata is not indicated.

water opening at the southern part to the Kii Channel. It has the minimum widthof 3.7 km and the maximum depth of 104 m. The maximum current is 6 knots.
As shown in Figs 7 and 11, the depth of the Inland Sea is less than 40 m inmost of regions. The mean depth is 31 m. The depth is larger in the western
open area north of the Hayasui Pass. The depth of about 98 m, the maximum
in the Inland Sea, is recorded in this region.
The water temperature recorded in the present study was between 6.0°C in
March and 28.0°C in September. The seasonal change in the surface watertemperature is more drastic than the open waters. Because of the inflow of external water from the wide Hayasui Pass and the larger water depth in the westernregion, the western open area is more oceanic. Namely the water temperature
in winter is higher at the western part than at the eastern region, and reversed insummer. The difference of the surface water temperature between the two regions
is 3°C to 4°C in both summer and winter seasons.
As the possible result of the oceanic environment, there were often observedsome oceanic delphinids in the open water of the western Inland Sea (Figs 7
and 9).
As mentioned in the later section, the finless porpoise is distributed near thecoast. Though it is not certain if it is related to the water depth or to the distancefrom the shore, the areas were divided in the present study based on the distancefrom the coast and on the group of islands. The entire research area was, at firststep, divided into three strata. The first is the stratum of 0 to 1 nautical mile off
the coast. This stratum was divided into five areas of 1 to 5, considering the
distribution of the islands. The second stratum corresponds to the waters 1 to
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

4

KASUYA AND KUREHA

3 miles off the coast. This stratum was divided into four areas (areas 11 to 14)
by the way mentioned above. Then there remain three independent waterswhich are more than 3 miles apart from the coast. This is the third stratum anddivided into three areas of 21 to 23 (Fig. 1).

Research period and data source
The field observation started in April 1976 and finished in October 1978.
Kureha made the observations between Himeji and Ieshima Islands andthose between Himeji and Fukuda, which routes are shown by dotted lines in Fig.
11. He had 24 expeditions in that part. Each expedition covered only a daywith more than one trip on each route.
Kasuya had 10 expeditions, 10 to 15 days each, to observe most of the partof the Inland Sea which are not cruised by Kureha.
Kasuya's 9th expedition, 6 to 15 March 1978, was for the observation of the
movement of the porpoise at four passes. The lOth expedition, 15 April to 2 May
1978, also includes cruises outside of the Inland Sea. Kureha had four expeditions to the Kanmon and Aka'>hi Passes. Though the results of the observations
made outside of the Inland Sea are not included in the Appendix, they are shownin Figs 7 to 14.
The data of some of the Kureha's expeditions in the Inland Sea were combined with those of Kasuya, and used for the population estimation (see Appendix).
A six hours cruise was made on 13 April 1976 in the nearshore waters off thenortheastern Shod03him3. Island (34°3l'N, 134°10'E) on board of a small fishingvessel. Though 4 7 porpoises were encountered, these data are not used for the
population estimation, because the course was altered by the presence of porpoise.
They are used only for the analyses of the school composition.
The aerial sighting records of the finless porpoise in the Inland Sea andadjacent waters were provided by the Fisheries Aviation Co. Ltd., Kojimachi, Tokyo. The flights were to monitor the pollution by scanning the area systematically,
and covered the years from 1972 to 1978. The season was usually limitted toJune to October with a few exceptional flights in other seasons. The observation of the porpoise was made by an experienced navigator at the altitude of 450 m,
but lowered to 100 to 150 m for the precise observation. These data were used
for the limited purpose to compare the relative density between the areas or between the seasons.
Vessels
With the exception of one trip made by the research vessel Tanseimaru (230gross tons) on 12 November 1976, all the observations were made on various commercial ferry boats. They were either for passengers or for both passengers andcars. The four of the five former cases were generally small (100 to 150 grosstons), and had cruising speed of 8 to 13 knots. The height of observer's eye wasfrom 3 to 4 m. An exceptionally large passenger boat was used between Beppu
and Imabari, and between Takamatsu and Kobe. The speed was about 18
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

5

knots, and the eye height of observer was about 15 m. Other ferry boats carrying
both passengers and cars had large variety of size. However the eye height (6to 6.5 m) was almost constant, because the roof height of car deck was designed
about 4 m. The speeds were between 8.4 and 14.2 knots.
The speed composition of 28 vessels (34 trips) in the 5th expedition, May
1977, is shown in Fig. 2. The mean speed was 11.3 knots (non weighted) or 12.3
knots (weighted with cruised distance).
miles

100
80
>u

c

<II
:::J
CT
<!J

60
JJ.

~

u.. 40,o-----0

',

'

tr

20

\,

b
',

08

10

12

14

16

18

Velocity in knot
Fig. 2. Speed composition of the vessels used in this study. Closed circle and solidline indicate the frequency weighted with cruising distance, open circle and dottedline nonweighted frequency, and vertical line the average speed.

Though the course was arranged as far as possible to cover the waters evenly,
the sighting effort was scarce in the western areas 1 and 11. The sighting effort
in offshore stratum (areas 21, 22, and 23) was scanty. Since the first expedition,
12 to 23 April 1976, was exploratory, the areas were covered in the case less completely compared with the following expeditions.

lvfethod of observation
The observer situated at a position where the maximum field of vision isavailable. It was sometimes the front seat of the cabin. However, in most of thecases, it was the posterior upper deck. Both naked eyes and a binocular (8 X,
8.5°) were used alternatively. The former were used for the near side of about
500 m or less, and the latter for the far side between 400 and 1,000 m. Though
the field of observation from 270° to 360° was available by moving between port andstarboad side, the observation of the front direction was difficult at the posterior
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

6

KASUYA AND KUREHA

upper deck. The time of one scanning was about 20 seconds with binoculars andabout 10 seconds with naked eyes. Namely a set of far side and near side scanning
took about 30 seconds, if there was found neither porpoise nor symptom suggesting
the presence of the finless porpoise. The course of vessel was not altered by thepresence of porpoise or of the symptoms.
For finding the porpoise, not only the body of porpoise or wave caused bysubmerged porpoise, but also the flock of feeding sea birds or the direction of flying
sea birds (mainly sea gulls) were extremely usefull. These indications were, if
found, carefully inspected with binocular.
When the body of finless porpoise was first confirmed, the time, direction fromthe vessel (if possible), radial distance from the observer in nearest 10 m, distancefrom the nearest coast line (if possible), number of individuals in a school, internal
structure of the school (if present), the estimated growth stage of each individual, andspecial behavior of the porpoise (if observed) were recorded. The growth stage wasrecorded as adult, juvenile (intermediate), and calf. The distinction was madebased principally on the body length relative to that of full grown individuals.
The first category represents the large individuals, and their estimated length ismore than 150 or 160 cm. The last is composed of the newborn calf which shows
its typical dark colour or older paler individuals not exceeding 120 or 130 cm inbody length. Though the juvenile (intermediate) is expected to indicate theindividuals between the two length range or those between 135 and 155 cm, theaccuracy will be worse than the other two. If an adult was accompanied by a calf,
they were considered as a mother and its calf. These individuals were always
swimming in parallel, and usually stayed within the distance of 1 m, which is muchcloser than the ordinary two adults do.
The position of the vessel was estimated from the relative position of islands
or of land marks, or from the fairway buoys.
Surface water temperature was measured two or three times a day on cruising
vessel. The wind force was recorded, in Beaufort scale, during entire cruising hours.
The observation was conducted in a wind less than 3 in Beaufort scale, andin a visibility exceeding 0.5 nautical mile (926 m).

Principle of population estimation
When the abbreviations are defined as follows,
D: Cruised distance, nautical miles
N: Number of counted porpoises
P: Number of porpoises present in area of S square nautical miles
R: Finding rate, ratio of porpoises counted to the porpoises present within
0.5 W miles distance from observer (both sides)
r: Apparent finding ratek: Finding rate at 0 m distance from the course
S: Dimensions of the sea, square nautical miles
W: Observed width, nautical mile
there are following relationships.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

7SN
P= D·W·R(1)

R = r·k(2)

As mentioned in the later section, r is influenced by the weather and other oceanographical environment. And N/(D·r) is used as an population density index corrected for the seasonal change of the apparent finding rate.
ESTIMATION OF PARAMETERS

Observed width (W)Several experiments made on a straight river or on a sea surface of known
distance suggest that a surfacing finless porpoise is identified from 450 m with nakedeyes and from 900 m with binocular at the sea condition of slight breeze (Beaufort
wind scale I). All the sightings in this study, except for two cases, occurred within
1000 m. Accordingly W was assumed in this study as I nautical mile. Even if
this estimation is biased in some degree, it does not cause any biase in the estimation of population abundance (see equations (1) and (3)).
Apparent finding rate (r)The swimming of finless porpoise is usually gentle exposing only part of headand dorsal region, and the jumping clear out of water or sprashing is rare. They
are usually indifferent to the boat encountered. No bow wave riding was observed.
The response to boat is observed as (1) a deep diving or minimum alternation of
direction when the cruising courses of the two cross about 5 to 20 m ahead of theanimal and collision is anticipated, or (2) a kind of stern wave riding lasting only
few to several seconds. The latter occurs occasionally when stern wave passes overthe porpoise.
Figure 3 shows the relationship between the number of porpoises counted andthe distance from observer. Since the finless porpoise is almost indifferent to thepresence of cruising vessel, above relationship is considered to indicate the increase of overlooked individuals with that of the distance.
The frequency of finding is relatively high at the distance below 400 m, andthe points come on a straight line (Fig. 3). This is the range where the porpoises
are identified with naked eyes. If y intercept of the linear regression is shownby Y0 in number of individuals per 100 m range, and the number of total porpoises
dealt by n, there is expected the following equation.

_ /(v.o 0.5·W·l852)
100

r- n

(3)

Wind will have serious influence on the apparent finding rate. Table 1 shows
the seasonal difference of the mean wind force and the number of porpoises sighted
per one hour's observation in different weather conditions. It shows that thesighting efficiency rapidly decreases with the increase of wind force. The efficiencies at the wind scale I to 2, and at 2 to 3 are 53.3% and 15.3% of that at wind
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

8

KASUYA AND KUREHA°loJan.- Feb.
N=40

8

y:56.88-0.2125x

20
4

20

•

•

Mar.
N:165

•

20

•

•

•

•
•

•

20
>
u 20
c
0
Q.I

::J

O'"

(!)

20

1.1...

0

0

May
N=109

6

Jun.
N:108

2

Jut.- Aug.
N:77

•

•
•

7

y:32.64 -0.0843x

20
0
40
20
No.

5

•

L..

•

Apr.
N:256

10

y:30.06-0.0569x

20

Apr.
N:133

y=22.81-0.0248x

•
•

Sept.

•
3

N:57
Nov.- Dec.
N=34

306.9 porpoises/ 100m range
y=30.6.9-0.592x

Total

200

•
00

200
400
Distance from••

N,,981•600
800
observer in•mFig. 3. Relationship between the distance from the observer and the number ofthe porpoises sighted. Numeral indicates the expedition number. Data ofKasuya
and Kureha included.

0 to 1. As shown in Fig. 4, it can be said for any of 9 expeditions that the sighting
efficiency was higher in the weather of lower wind force.
The r calculated for each expedition shows a seasonal fluctuation (Table 1).
The relationship between the mean wind force and r is shown by a linear regression.
However, as shown in Fig. 5, the 2nd (July to August) and 3rd (November toDecember) expeditions give extremely low apparent finding rates. Though theprecise observation of density of sea bird was not recorded, it is worth to note thatthe extreme scarcity of sea bird in the 2nd expedition was noticed and recorded on
several pages of the field book. This may perhaps have a effect to lower theSci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

.....

9

Wind scale:J5.......

..c
,_
(!J
a.

4

··O··

Ill

3

-

2

0

c:n
.£
..c
c:n

0-1
1- 2
2- 3

7

3

(/)

M

F

J

A

0- - -------- - - --- - - -o-- --------_______ .o------

0

J

M

J

A

s

0

N

D

Month
Fig. 4. Relationship between the wind force and the number of individuals sighted
per one hour of observation. Upper limit of each wind range excluded. Numeralby the circle indicates the expedition number .
.5

. .
5

1
Apr.

-:::-

May

2 .4
6•June~.

10•Apr.
li•Mar.

01

c

-g .3

.

7
Sept.

2

Jul.-Aug.

c
Cll

~ .2

a.
a.

<(

.
3

.
B

Jan.-F~ .

Nov.-Oec .

. 1'---'-~-'---'~-'--~~~~-'---'~-'--~~~~-'---'
.6
.8
1
1.2
1.4
1. 6

Mean wind force

Fig. 5. Relationship between mean wind force and the apparent finding rate (r).
Numeral indicates the expedition number.

apparent finding rate.
Though it is not possible to explain the low r value of the 3rd expedition,
it is concluded that the apparent finding rate r calculated by the above method
reflect the wind force and probably some other oceanographical conditions. So
it is unnecessary for r to have further wind force correction. The visibility will notneed to be corrected because the observation was made only when the visibility exceeds the observable distance (W/2). There might be personal difference of the rvalue. However it was confirmed in the previous cooperative works that oursighting ability is not significantly different.
Though it is more reasonable to use perpendicular distance measured fromthe position of porpoise to the course of the vessel instead of the radial distance between porpoise and observer (Seber, 1973; Doi, 1974), it was not used in the present
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND KUREHA

10

study mainly from the absence of adequate data. Where the porpoise is densely
distributed, the recording of both finding direction and the distance was often impossible for single observer without increasing the overlooked individuals. Only
the radial distance at the first sighting was recorded in such a case. When the
direction of finding is group into nearest 45° angle, they are distributed as follows.
Number of individuals
22
28
601
27
7
685

Direction

oo

45°

goo

135°.
180°
Total

Percent
3.2
4.1
87.7
4.0
1.0
100.0

The finding on stern (180°) or bow (0°) direction is only a few percent of the total,and most of the sightings occurred on the side direction or between 67.5° and 112.5°.
This tendency will be more exagerated in the dense area where angle was notrecorded. Though the present calculation will slightly overestimate the r value,
the above analysis of the finding direction suggests that the bias will not be solarge compared with the uncertainty of the estimation of k value mentioned below.
TABLE 1.

EFFECT OF WIND ON SIGHTING OF FINLESS PORPOISE

no.

date

8 27/I-10/II
4 2/III-15/III
l l 2/IV-23/IV
10 15/IV-30/IV
5 8/V-19/V
6 14/VI-25/VI
2 22/VII-4/VIII
7 15/IX-28/IX
3 12/XI-21/XII
Total
Total, no./hr
Total, no./hr rate

Wind force 2lSightingsll

Expeditions
no.

hrs.

0-1

1-2

2-3

mean

36
155
251
256
109
101
76
57
51
1092

29.86
53.93
49.57
55.43
50.57
47.05
49.63
51.64
57.00
444.68

0.167
0.530
0.920
0.618
0.827
0.515
0.915
0.350
0.519
0.613
3.174
I

0.420
0.381
0.080
0.195
0.128
0.380
0.085
0.551
0.243
0.267
1.693
0.533

0.413
0.089
0
0.187
0.045
0.105
0
0.099
0.238
0.120
0.486
0.153

I. 746
1.059
0.580
1.069
0. 718
1.090
0.585
1.249
1.219
1.007
2.456
0.774

lJ Only data obtained by T. K. included.
limit inclusive, Beaufort scale.

2lApparent
finding
rate (r)
0.190
0.345
0.473
0.356
0.498
0.378
0.280

o.:m
0.165
0.345

Shown by the ratio of length of time, wind range lower

Estimation of k and R
For the estimation of the population size the true rate of finding at zero distance need to be estimated. Since the mean speed of the vessels is about 12.3
knots, an entire observation field of 1 nautical mile is cruised within 4.9 minutes,
and more efficient observation field of about 900 m within 2.4 minutes. On theother hand the surfacing interval of the finless porpoise ranges form 4 to 80 seconds
with an average of about 40 seconds (T. Kataoka, unpublished data). Then theSci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

11

number of surfacings expected for one porpoise in an observation field is from 73
to 3. 7 occasions with an average of 11, and that in the efficient observation field
is from 36 to 1.8 with an average of 3.6. These figures will be doubled for a schoolof average size (l.97 individuals/school). On the other hand one complete scanning, near side and far side, was made at most once every 30 seconds, and certainly less when porpoise was sighted. This means that one observer can scan
the near side and far side ranges only less than five occasions. Then it will besuggested that t~e finding rate at zero distance (k) must be below l.
In the present study k was estimated from the relationship between the numberof sightings and number of observers on one vessel. This experiment was madein 9th expedition on both sides of the Naruto Pass. The season corresponds to thatwhen the porpoise is most abundant. The weather was calm. The other observer
was Mr T. Hiwatari, a graduate student with one week experience of whale
watching. The sighting was recorded by Kasuya in two categories. The first is
the porpoises found by Kasuya or Kasuya and Hiwatari. The second represents
the porpoise which might have been overlooked if Hiwatari had not been there.
There was 73 individuals in the first category and 37 in the second category. When
X indicates the probability of one surfacing not encountered with a visual angleof one observer, the probability of a surfacing not encountered with the visual
angle of any of n observers is shown by xn (Doi, 1974). Accordingly when p indicates the number of finless porpoises present on the course of a vessel, there willbe the following equations,l-k=p-73p(l-k)2 = p-(73+37)p

and k is calculated as
k = 0.493

which is rounded to 0.50.
When a school of porpoise is sighted, the scanning has to be stopped in orderto have its detailed observation. This means that the presence of a porpoise may
obstacle the finding of another school, and that the estimation of k is inversely
correlated with the density of porpoise. Because the density of the porpoise aroundthe Naruto Pass, where k value was estimated, was extremely high as indicated in
the latter section (Table 2 and Appendix I), true k in calm seasons (expeditions
I, 2, and 5) can be 0.5 or larger. However, since k is suspected to be inversely
correlated with the wind, the value for other expeditions will perhaps close to 0.5
or lower.
Though the finding rate R is calculated by

R = k·r
various uncertainties of the estimation of k and r have to be remembered.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

12

KASUYA AND KUREHA

5000
3000
1000

v\

100
>u
c
(!)

::J
CJ"'

?

80

(!)
I...

u....

60

'
'

40
'

20
\
~ ...

0

0

5

10
15
20
No. of individuals

Fig. 6. Frequency distribution of number of sightings in each 1 nautical mile
section of the cruise (closed circle and solid line), and the Poisson distribution
with the same mean and same sample size (open circle and dotted line).

Confidence range
One of the most important factors causing error in the estimation of population size will be the biase of sighting effort. Since the present study was made on
board of commercial regular service vessels, most of the observations were madein the nearshore waters. It was to decrease the effect of this bais that the analysesof the data were often made by each stratum or area.
The other problem is the simple error of the estimation of density index. The
distribution of the porpoise is not random even in an area or in a stratum, but as
mentioned in the later section more porpoise are apt to aggregate in a small area.
When the course of a vessel is divided into contiguous 1 nautical mile sections andnumber of the finless porpoises encountered in each section is compiled into a frequency distribution, all the individuals in each expedition were found in the sections
from 3.0% to 11.5% of the total number of sections. This feature is shown in Fig.
6, where the data of 9 expeditions used for the calculation of the population arecompiled. Though this frequency distribution seems to follows the Poisson distribuSci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

13

tion, it is significantly different from the Poisson distribution of the same meanvalue (0.203 individuals/mile).
The standard error and the 90% confidence range of the mean number ofsightings per observation of one nautical mile was calculated from these frequency
distributions, and used to estimate the 90% confidence range of the population ineach stratum. The variance of the sum of population estimates of three strata
was calculated as the sum of the variances of the mean population estimate of eachstrata, and then the confidence range of total population was calculated.
RESULT

Geographical and seasonal variation of density
The actual positions of sightings and the course of the vessels are shown in
Figs 7-16. In the Inland Sea, the finless porpoise is frequently distributed near
the coast, especially off the pointed rocky shore or near narrow passes between
the islands. The current of these places is usually moderate. Though the actual
density of porpoise may change seasonally, the density in most of these locations isin any seasons higher than that in surrounding waters. There are other kind ofwaters which is occupied only in spring months by large number of individuals
but almost vacant in other seasons. Typical example of these locations are southernpart of the Hiroshima Bay (34°N, 132°30'E), between Setoda and lnokuchi(34°17.0'N, 133°03.5'E), and around Nakajima (33°58'N, 132°33'E).
In case of aerial sighting records used in this study, the position of sighting
will be less accurate and the porpoises in the nearshore area seems to have been
overlooked. However the absence of the species in the deeper part of the Inland
Sea is clearly indicated in Figs 15 and 16.
If the distribution of the finless porpoise is analysed in relation to the distance from the coast line, it becomes clear that 82.4% of the individuals were observed within one nautical mile from the coast, 15.5% between 1 and 2 miles,
1.5% between 2 and 3 miles, and 0.6% in waters more than 3 miles from the coast.
This general tendency is true even when the bias of the effort is corrected (Fig.
17). The number of individuals sighted per 10 nautical miles of observation is
2 .5 7 individuals in the nearshore stratum (0-1 mile from the coast, areas 1 to 5 ),1.19 in the intermediate stratum (1-3 miles, areas 11 to 14), and only 0.24 in theoffshore stratum (more than 3 miles off coast, areas 21 to 23). Namely the relative
density of the porpoise in the three strata is 1: 0.46: 0.09. However it must be
noted that these figures are strongly influenced by the distribution of the porpoisein the season of highest population density.
The relative density of finless porpoise in the intermediate stratum expressedby the ratio to the density in the nearshore stratum is shown in Fig. 18. It gradually
increases from the minimum in November to the following September when thedensity apparently exceeds that of nearshore stratum. This is an indiciation thatthe porpoise leaves the coastal stratum and the animals are going to be evenly
distributed in summer low density season. The decrease of relative density ofSci. Rep. Whales Res. Inst.,
No. 31, 1979

~.:~

~~

..i....:""

""'~

~~

~

~

~

0

..,..,z

I

I

!~

J.I

;,">:

R"

I

·····...........

~/I

I

f

/

Fig. 7. Observation routes and number of sightings of the finless porpoise (circle),a school of Delphinus (D), and a school of Grampus (G). March to May. Small
closed cicle indicates one individual, large closed circle 5, and open circle 10.
Numerals in the circle indicates number of cruises, dotted line the 40 m contourof water depth.

-------~--;-------~\--7f~ ~132°E
Mar. Apr. May

~

g;

~

~

;;

c

cr.i

;.>-

\i'l

"""

-

:9•

u

S'

~
?

1'..,""....

..... .
~~
<o ..

~~

~

:a: l{l.., r~ ------------------------z·---------

1320E

;~

I

I

June July Aug.

I --

~

Fig. 8. Observation routes and sightings of the finless porpoise. June to August.
For marks see Fig. 7.

------ ------~)~---

131°E

U1

-

tTl

U'l

::;;

2l
2l.....

U'l

~
U'l

l'!j

z

~.;~

~~

~~ ~

"' "'::i:i;,,'.'.?; ~

~

~

::i:i

!"·

~

z

<'>

(¥')

z0

<'>

),

~

y'\

131°E

r-...__

c~/

.

•

.
~~ ~

I

132°E

I

I

Sept. Nov.

~-

• "°'i-1. o

;,~ .

I

Fig. 9. Observation routes and sightings of the finless porpoise (circle), and two
schools of Tursiops (T). September and November. For other marks see Fig. 7.

?~ ·"")J

r·--. 7 ~I___ ;I ......_______

I

!

;'

·

I

----------17
I '"J
~
--</
~.
~~
1
I ' ~~,~~' ~~r··~---../~-----~~r,,?

.t'

D(::~
7 &Ji

!\~·~

/

e., -

..

~

trj

~:;o

~

~

~
c

1JJ

o;

!""·

~-

~

~

"'
~

~~

......

~~..."- ~~~~\,...._"'.I>1,I

132°E

Fig. 10. Observation routes and sightings of the finless porpoise.
marks see Fig. 7.

,!:_.
~-- ~St ;a~/~-~ ~~<

\

I ·~

~~-~~

I

I

I

131°E

February.

~

For

-"

tr:!

u:i

0
.....

"C

:;d

0

"C

u:i
u:i

>'rj

zt;;

~

:-·

<.,

~.:

to ~

~ ::tl..."- ~

"'

~~

~

~

!:ti

-···--r----

~
<')

0

1JJOE

<')

-

z
0

·---

"··--·-. --1L-.

I

"'---

""\

~~ (

'~~

Fig. 11. Observation routes and sightings of the finless porpoise. March to May.
The routes indicated by dotted line are those observed by Kureha for the entire
study period. For other marks see Fig. 7.

"'...:.~B-f)·.,...v····~:;;>':·-~-c.,,/:-···,

13411E

.

~-

\

I

I

I

135°E

··, a/J;'.,,_1J,.

Mar.Apr.May-~

t:°':I

~~

~

~

c::
~

.IJJ

00

*

'?:
~ ~·

.r-

S'

~

"'

~~
.,...
"'

~~

..""'::.::,
.....

..,

·---

~

0

--------~

/

"

!'
I

------

I
I
I

'

%

~V"'
-)
"
~.., ----·--./
De)r::;J)·--/:C.,,/""'".

"'2·

J

r

,,..,v-~:~

Joo•J,lyA"g;;;?"'
.-4
~

/~.

·

A

-

I

-- ·--- · - .•. ·-

---

'---

.

.··I

J

~;;··•~->(JI

/ ;?

0

·n{~

-~~;~-~

~

~"­

v-"'~

i

i
I

;
!

/]

135°E

1·~~-----~7--------;---__
I

',/

;{

l«J/,f(F--,,.__·v~--~)----(-Ji/fi~';,~/ /

I

I

134°E

Fig. 12. Observation routes and sightings of the finless porpoise. June to August.
For marks see Fig. 7.

~~~--/-----•-_<!)·_:_\

'

133°E

~1---)

"?-

<.O

-

ti'l

rJJ

0.....

'"d

l:d

21

rJJ
rJJ

~

"l
.....

~

~ _;~

~~

.............

~~
~

~~

~

~

~

:-'·

"""

0

z

?;..,

b

z

\

\I
~

134°E

Fig. 13. Observation routes and sightings of the finless porpoise.
November. For marks see Fig. 7.

~'l..i>:'

1330E

September to

1JJ

of""

Sl'pt. Oct. Nov .

135°E

>

~

ti::I

~i'.:I

tl

~
z>

c:::

CFJ

:;>:1

""
0

!"'·

~-

~

~

"'

"~

~ ;,§

.....

""~
............
~

~

~ f<>

m·

I
I

133°E

1

I
I

D.o.J•oH

I

i

135°E

I
>rj

December to

0

ci

'1"

'\,_,r

ef~

1"'

~

~ ~ _Jf · I

.

~I

•

Fig. 14; Observation routes and sightings of the finless porpoise.
February. For marks see Fig 7.

,/

I

134°E

KASUYA AND KUREHA

22

-- --

------ /i:--.-_

I--~/'----.

/---------------------•

Fig. 15. Aerial sighting record, poisition of the occurrence of the finless porpoise.
Each circle indicates one encounter. For effort data see Fig. 20.

135°E

134°E

z

g
~ ---::-/-:~·""·~------~
I?'-~_~.

_,,, ..

-.)•

Fig. 16. Aerial sighting record, position of the occurrence of the finless porpoise.
For other explanations see Fig. 15.

Sci. Rep. Whales Re~. Inst.,
No. 31, 1979

FINLESS PORPOISE

23

300

en

ti

::J

u

·::; 200
u

c

.....
0

100

0

z

0

0

2

0.5

Distancefrom3coast in miles

Fig. 17. Distribution of the finless porpoise and the distance from the coast. Closed
circle and solid line indicate the actual number at actual position. Dotted line
indicates sightings per 1,000 nautical miles of observation, where the position of
the vessel was used as that of the porpoise.

-

>'iil

- - Areas 11 to 14--o-- Areas 21 to 23

c

~ 1.0

0

0

~

0::

J

FMAMJJASOND

Month
Fig. 18. Seasonal change of the relative density of the finless porpoise in intermediate (areas II to 14) and offshore (areas 21 to 23) strata indicated by the ratio
to the density in the nearshore stratum. Numeral indicates the expedition number.

intermediate strata in October to December will be the result of the migration to
the nearshore stratum. This is followed by the immigration from the external
waters to the Inland Sea in December to April mentioned below.
Figure 19 gives the geographical and seasonal fluctuation of the finless porpoise. density in the Inland Sea. The density is expressed by the minimum estimate persquare mile (tentative assumption of k= 1). For the estimation of real density,
this has to be divided by k or about 0.5. Two or three expeditions are grouped toaccumulate sufficient amount of data for each area. Generally speaking, thedensity is low in the eastern and western areas, through which the Inland Sea isconnected to the outer ocean. In the areas of the nearshore stratum the density
is highest in March and April, and the highest density is observed in the areas
3 and 4. However the density continues to decrease in all the areas of the nearSci. ]lep. Whales Res. Inst.,
No. 31, 1979

24

KSAUYA AND KUREHA

shore stratum until July-September. The decreasing trend is faster in area 4 inthe east than area 2 in the west. This makes, in May to September, the density
in area 2 higher than that in area 4, though the actual density is certainly decreasing.
In November-February season the density in the nearshore stratum start to increase, again at a higher rate in eastern areas. These features indicate that thelarge scale seasonal migration in the population starts in the eastern part andis spread to the west.
In the intermediate stratum, the decrease of the density from March to September is not clear, but there is observed a slight increase in the area 13 in the

1.Sf Mar.-Apr.
.5
14

":~
:!,,~,:,:,:,:,:,:,,,,~ I

!

i:[~J
Nov.- Feb.

west

Area

east

Fig. 19. Seasonal change of the density distribution of the finless porpoise in the
Inland Sea.

eastern part of the Inland Sea. In November-February the density in area 12
reaches to the minimum, however in the same season there is observed an increase of density in areas 13 and 14 at the eastern part of the Inland Sea, a possible
suggestion of movement to nearshore stratum. The abrupt increase of the density inthis season in area 11 at the western Inland Sea is difficult to be concluded becauseof the scarcity of the observations. However it will be reasonable to suspect fromthe seasonal trend of the density in both intermediate and offshore strata, and fromthe presence of similar trend in the aerial sighting records (Fig. 20), that the density
in the western part of the Inland Sea stays slightly high in summer and autumn
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

25

FINLESS PORPOISE
K1i Channel

~

4

8

~ 0
Osaka

Bay

4
0

14

InlandEast of~133.5°E

12

3

10

~
Vl

c

Cl1
Inland

12

2 0

\

6
4

0

-....

8

Sea

132°-133.5°E

Cl1

OI

0 .i:

:c

OI

2 Ji

8
6
4

0
2

12

8
4
Ql--l-~-+---.1~-'---''-""==---i.~-'-~-'---'-~...:L.~.L..1

0

4o~~~__,--=~~~--~-+-~+---'-~-'-~.w

A

M

A

s

0

N

D

F

Month

Fig. 20. Aerial sighting records of the finless porpoise. Seasonal change of thenumber of encounters per 1,000 nautical miles (closed circle and thick solid line)
and number of individuals (open circle and thin solid line) per 100 nautical miles.
Amount of effort are shown by dotted line (thousand nautical miles).

season and the spring concentration of the species in that part of the Inland Sea
seems to start slightly earlier than eastern Inland Sea (see Discussion and Conclusion).
jVfovements between outer waters

Observations were made at four passes connecting the Inland Sea with outerwaters. The intention was to get direct informations on the migration route of
the finless porpoise. The season covered both before and after the peak of the
population in April. Though the swimming direction was examined, it was foundto be insignificant as the indication of migration.
At the Kanmon Pass, 6.4 hrs (15 March 1978) and 11.5 hrs (2 May 1978) land
based observations at the narrowest point of the pass provided no sighting.
At the Hayasui Pass, five cruises made on 11 and 14 March 1978 provided
no sighting. Two cruises made on 24 and 26 April across the pass did not show
the presence of the porpoise, except for the three individuals off Beppu (Fig. 7).
Some ancillary cruises in the Bungo Channel gave no sighting of the finless porpoise.
The observation at the Akashi Pass was made by Kureha on board of small
Sci. Rep. Whales Res. Inst.,

No. 31, 1979

26

KASUYA AND KUREHA

ferry boat connecting Akasi and I waya across the pass.
Hour
0800-1826
0800-1820
0800-1823
0800-1720

Date
17 Mar., '78
20 Apr., '78
26 Apr., '78
12 Oct., '78

The result is as follows.

No. trips
16
16
16
14·

No. sighted
5+1
0
0
0

The larger school was sighted at 1040 when the current was flowing eastward.
The school was moving westward at the position about 400 m off the coast (Fig.
11 ). The other solitary individual was found at 1707 at the same position withanother school. Both the current and the swimming direction were eastward.
The position of these porpoises is same with that of a school of two individuals
found by Kasuya and Mr T. Hiwatari during the land based observation madeon 7 March 1978. The school was moving westward.
TABLE 2.

DISTRIBUTION OF FINLESS PORPOISE AT THE NARUTO PASS

Expedition no.

9 (two observers)

10 (one observer)

Date

8-9, March, 1978

30, Apr.-1, May, 1978

Current, flowing toNorth side

{ n. miles
no.
no./10 miles

South side

{ n. miles
no.
no./10 miles

North

South

Total

North

South

Total

8.9
15
16.9
30.7
47
15.3

11.9
26
21.8
21.9
22
10.0

20.8
41
19.7
52.6
69
13. 1

17.8
41
23.0
8.1
24
29.6

14.8
2
1.4
25. l
56
33.3

32.6
43
13.2
33.2
80
24. l

North side : Inland Sea, South side : Kii Channel.

The observations at the Naruto Pass were made in early March, and April
to May (9th and lOth expeditions). The former was done by Kasuya and Mr
T. Hiwatari, and the latter by Kasuya. The frequency of the swimming direction seemed to be influenced by the current, turbulance, and topography of thesea than the migration direction. Large concentration of porpoise was usuallyfound in the rapid current flowing from the pass. The presence of large concentration of the porpoise at the Naruto Pass suggests the migration of the species
through the pass. For the comparison of the porpoise densities between the two
expeditions, the number of observers must be corrected. The number of porpoises
sighted by Kasuya at the Naruto Pass was only 73 (9th expedition). This gives
the number of sightings per 10 nautical miles as 73-;-73.4X 10=9.9. This is about
half of the density observed in April/May expedition. The weather condition
will have no relation with this difference, because the wind was between 0 and
1 in both expeditions.

Population estimation
As the data was insufficient to calculate the population size by expeditions
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

27

Areas 21-23.5
Areas 11-14
2

lll

"O

c:

<IS

lll
:::J
0

0

:5
c: 2

8)

·ollla.
'-

0

-

a. 0

oc
Total

0

~

.c
E
:::J

z

28

I

4
T

1

i

3

20

12

T

:,

.....

2

4

0

F

M

A

M

J

J

A

s

0

N

D

Month
Fig. 21. Seasonal fluctuation of the finless porpoise population in the Inland Sea.
Mean population estimates and the 90% confidence range (closed circle and solidline), and range and mean of the surface water temperature (open circle anddotted line) are indicated. Since k= 1 is tentatively assumed, the population size
expressed here is close to the half of the actual estimation. Curves are drawn
by eye.
TABLE 3.
Month

2

SCHOOL SIZE FRFQUENCY OF FINLESS PORPOISE IN THE
INLAND SEA, AND ADJACENT BAY AND CHANNELS
3

4

5
1
Jan.
1
11
Feb.
9
101
41
Mar.
9
3
15
126
Apr.
19
95
38
38
13
4
May
25
19
8
2
June
4
12
July
4
1
3
Aug.
6
Sep.
9
2
::!
2
Oct.
12
Nov.
10
2
6
Dec.
4
341
Total
243
57
25
Total,% 48.1 34.3 8.0 3.5

5

4
4
2
2
2

15
2.1

6

7

8

9

11

12

13

Total

Mean

1
0.1

6
21
163
271
97
57
22
10
21
5
25
11
709
100

1.17
1.52
I. 74
2.03
2.04
1.95
2.73
3.10
2.71
1.40
1.84
1.55
1.97

1

3
4

10

3

3

2

9
5
1.3 0.7

5
0.7

0
0.0

5
0.7

2
0.3

0.1

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

28

KASUYA AND KUREHA

and by areas, data of some expeditions or of some areas were combined. The
first method is to group the data of one expedition into three strata and to estimate
the population for each stratum. The second is to group the data of two or three
expeditions to calculate the population in each area. As shown in Appendix, thetwo kind of estimations give a reasonable coincidence.
The population abundance in nearshore stratum attains the maximum in
April and followed by the decrease to the minimum level in September (Fig. 21).
The population level in the intermediate stratum, however, seems to continue todecrease until December. Though this differs in the expression with Fig. 19,
both of them indicate the same phenomenon of the porpoise migration. Further
discussion on the migration of the species will be made in the later section.
When the value of k is considered as 0.5 (see page 10), the population of
finless porpoise in the Inland Sea is estimated as about 2,450/0.5=4,900 in the
maximum season in April and decreases to the minimum level of about 780/0.5=
1,560 in early winter. The overall population density in April is 4,900/14,260=
0.34 individuals/km 2 • The approximate density in each stratum in this monthis given as 3,710/4,805=0.77 for nearshore stratum, 928/5,061=0.18 for intermediate stratum, and 260/4,394=0.06 for offshore stratum. In the intermediate
stratum, however, the highest density of 1,470/5,061=0.29 individuals/km2 will beattained in August (Fig. 21 ). Though the direct comparison will not be meaningfull because the body size, food requirement, and the environment can be different,
it is worth to note that the above densities are close to those of the Atlantic Tursiops
truncatus, 0.23 to 0. 75 dolphins/km 2 , calculated for coastal or semienclosed waters(Barham, 1979).

School size
In order to avoid the influence of the preoccupation, the analyses concernig
the school structure and the size frequency of the porpoise were made after thecompletion of all the expeditions.
The largest school encountered in the present study was composed of 13 individuals. As shown in Table 3, however, most of the schools of this species areso small to give the overall mean school size of 1.97 individuals. About 50%of the encounters were solitary individuals, and the school of 3 or fewer numberof animals comprises 90.4%. These figures suggest that the school of this species
is slightly smaller than that of Phocoenoides dalli which shows the mean school sizeof 4.62 (Kasuya, 1978).
The seasonal fluctuation of the school size is shown in Fig. 22. The ratioof solitary individuals in the total encounters shows an annual cycle with the highest
in January and the lowest in July. The mean school size shows the similar annual
cycle.
School structure
The body length of the porpoises in a school is variable, and the relative distance between the members is not same. These characters are considered in theSci. Rep. Whales Res. Inst.,.No. 31, 1979

FINLESS PORPOISE

65

Jan.

N=6

Feb.

N=21

Mar.

N=163

Apr.

N=271

May

N= 97

Jun.

N=57

Jui.

N=22

Aug.

N:10

25
50

25
~ 25

29

c
>.

u

25

c

~

---

50

er

._
u..
QI

•

•

Sept. N:21

25
50

•

•

~

Oct.

N=5

Nov.

N: 25

Dec.

N=11

9

11

--+-

25

-+3

5

7

13

School size
Fig. 22. Seasonal fluctuation of the school composition (closed circle and solidline), mean school size (vertical bar), and 90% confidence range (holizontal bar).
All the data obtained in the present study included.

present study as an indication of the internal structure of the school.
Though there was found solitary calf or juvenile (Fig. 23, type 1-b, 1-c),
more frequently they were found with another individual of various growth stages.
The most common was the combination of a calf and an adult, presumably corresponding to the mother and calf. The less common was the school of adultand juvenile, some of which may represent the combination of the mother andelder calf of the previous season. The school of weaned individuals (types 2-d,2-e, 3-h), and that of one cow and two juveniles (type 3-g) are scarce.
Most of the adult individuals encountered were solitary or in a pair withanother adult individual (types 1-a and 2-a). In some cases, the adult porpoisesof up to five individuals were found to aggregate to form a school (types 2-a, 3-a, b,
4-a, b, c, 5-a, b ). However, it was more common for the schools of three or more
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND KUREHA

30

3

4

5

------11

~
a~

2
::::=
ao------

2a~bo--- 1317c.-a~ a:==--::::=

b-----11 ------2 _____!
b==== b = -------2
b:::==
c._ GOd::::::=,.______lc::::=_

4

~

__-2
c-~

":=

4

d--

-- :=--1
1

t:=--

e--

,.______l:::--1

g:=

f

7

---2.

.__l

a ,.____,.____
o---------

0---------·

o-------_1-------- b====~c:=---~

3----:=-------1

a::==

b====

---- ::::-1

Co---

d~

-----1eo--

---1

6

0---------0----------d~~:::::::~:\

co---------0----------·
o---------·

L~~~~~}=

do-----------

:=---

h~

11

12

&::.·.::.::~--imt~{~{t8b--8:::::::::::.
8::::::.:::::

0---------..
0------------

0----------()-......... .

o-----------

10...._.
,._

13::::--1o----------0.-----------------

0-------·-- .....--

Fig. 23. Schematic figure of the school of the finless porpoise, relative size of theschool members and subgroups are indicated. Numeral at the top of column indicates school size, numerals by each type the number of encounters. Two dimensional arrangement of subgroups is indicated only in cases of type 8-b and 10.
Long bar, adult; intermediate, juvenile; short bar, calf; open [ircle and dotted
line, size unknown.

individuals to contain the combination of cow and calf. It was frequently observed that a cow with calf was followed by one or two adult individuals. Presumably they represent the case where, after certain length of nursing period, a
cow accompanied by the calf (type 2-c) approaches the next oestrous cycle andis attended by adult male(s) (types 3-c, f, 4-d). The number of such schools was
22, or about one third of the number of schools of the cow and calf. This indicates that most of the cows accompanied by the calf, consequently for most of
the nursing period, are not attended by adult male.
Another information on the school structure was obtained from a land based
observation on 5th March 1977 at Teshima (34°23.5'N, 133°40.5'E) in the Inland
Sea. Several finless porpoises, varying between 1 and 6, fed in a small rocky
inlet open to south. Their position was about 20 m from the beach. It seemed,
at a glance, to be one feeding school with several internal structures. However
the subgroups were continuously changing. The subgroup, two or three individuals
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

31

in it, arrived one after another from the southwest direction, fed together for 20
to 30 minutes in the same area with other subgroups, and then slowly left the place
toward southeast offshore direction. Their leaving passage was traced for morethan 1 km by the presence of a flock of sea gulls. By this way total of 5 subgroups
were confirmed by 2 hours' observation.
From above informations we suspect that the most stable basic unit of theschool will not exceed three individuals in number, and they are combinationsof the cow and calf or of adult male and female. Probably the school of morethan four individuals would have been formed through the aggregation of thesefundamental units. An example of the transitional stage is shown in Plate I, Fig.
2, where all the seven individuals will be considered without doubt as one school
if the three units were situated slightly closer.

GO
~
0

c
~ 40

c

Cl.I
:::J

O"'

J: 20
J

F M A M JJ

A S 0 N D

MonthFig. 24. Seasonal change of the solitary adults. Closed circle and dotted line
indicate the ratio of solitary adult to total number of the adults, dotted line themoving average of the three. All the data obtained in the present study included.

Mating Season
Though the copulation was not confirmed, there were several occasions toobserve the probable precopulatory behavior of the finless porpoise in the Inland
Sea. They were one couple in March, four in April, two in July, and one in
September. They suggest that the mating occurs from March to September.
Another indirect indication was obtained from the seasonal change of thefrequency of solitary adult. The number of solitary adults was about 40% of thetotal adults in any months between October and March, but decreased below 30%
in April to September, with the lowest frequency in June to August (Fig. 24).
This season coincides with the peak of mean school size, and is considered as themating season of the species in the Inland Sea.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

32

KASUYA AND KUREHA

Parturition and weaning season
The parturition season was estimated from the seasonal change of ratio ofcows accompanied by the calf to all the adult individuals (Fig. 25 ). The ratio isstable from November to March at a level of about 10%, and start to increase in
April to attain the maximum of about 27% in September, which is followed bya rapid decrease to initial level in October and November. The increasing season,
April to August with the center in June, will correspond to the parturition season.
1

15 147 213 122

7

2

13

10

2

5

24

14

Juvenile0
Solitary calf

-!

20

•

c

u>-

10

c

~ 0
CT
Cl>

~

[J..

20

to
QL--'-__.,~..___.___.~_.____.____.....__.....___._~~~JF M A M JJ

A S 0 N D

MonthFig. 25. Seasonal change of the frequency of juveniles, solitary calves, and cows
with calf. Frequency is shown by the ratio to the total number of the adultshown at the top. Months with small sample size are grouped.

The rapid decrease of the cow with calf in October and November is followed
by a rapid increase of solitary calves in November and December, which tails off
towards next summer. This will be the indication of the weaning season. Namely
most of the weanig will occur in October and November, but some calves seemto accompany their mother until next spring or summer.
The decrease of solitary calves after December is followed by the high levelof juveniles, which will indicate the growth of the weaned individuals.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

33

DISCUSSION AND CONCLUSION

Seasonal movements
The continuity of distribution of the finless porpoise between the Inland
Sea and the Kii Channel through the Naruto Pass suggests that the annual migration of the species will be done through this pass. The seasonal change of thedensity in the Kii Channel appeared in the aerial sighting records suggests a peak
before July, low density in August and September, and the winter increase inJanuary and February. This change is similar to that in the Inland Sea. The
decrease of the density from April to September in nearshore stratum is faster ineastern areas than western areas, but both the speed of the density decrease andthe areal difference of the speed are not large in the intermediate stratum. Theseobservations suggest that most of the migratory individuals start to move, in April,from the coastal stratum to eastern areas of offshore stratum, and then to the Kii
Channel. The low porpoise density in the Kii Channel (Table 4) suggests thatthe finless porpoise will not spend summer in the channel but will be dispersed inwide coastal area facing to the Pacific. The migration into the Inland Sea will
occur from January to April (Fig. 21 ). However the concentration of the porpoise
into the nearshore stratum seems to start in November (Figs 18 and 21). In otherwords, the seasonal migration of the species seems to start in the nearshore areas.
TABLE 4.

AERIAL SIGHTING DENSITY OF FINLESS PORPOISE, BASEDON RECORD OF FISHERIES AV. CO., 1972-1978
Distanceflown(n. mile)

Bungo Channel
Western Inland Sea
Central Inland Sea
Eastern Inland Sea
Osaka BayKii Channel
I)

3,387
7,471
12,025
12,0333,310
6,666

Schools
no.
21>
45
97
137
9
14

Individuals

no./100 miles

no.

no./100 miles(0.06)
0.60
0.81
1.14
0.27
0.21

2Jll
376
659
863
37
50

(0.62)
5.03
5.48
7 .17
1.12
0.75

A school of 20 individuals of doubtful identity included.

The porpoise density in the summer season is slightly higher in western area
than in eastern area. This will mean that the coast of oceanic western Inland
Sea is in some degree used as the summering ground of the species.
The presence of small number of sightings in July and August in the Bungo
Channel (Fig. 20), and the increase of the density in the western Inland Sea in
October to November (Figs 19 and 20) suggest that some individuals of the finless
porpoise in the Inland Sea will migrate to and from the Bungo Channel throughthe Hayasui Pass. However, the low density of the porpoise at the Hayasui Pass
and large water depth in the Bungo Channel will not give suitable reason to expect
such a large number of migrating porpoises as expected for the Naruto Pass andthe Kii Channel.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

34

KASUYA AND KUREHA

Considering the several sightings at the Akashi Pass and the relatively highdensity of the porpoise in the Osaka Bay (Table 4), it will be reasonable to consider
that the pass is one of the migration routes of the species.
According to the record of the Toba Aquarium, the incidental capture of 30
individuals in the past 13 years in the Ise Bay occurred from September to April
with one peak in February to April. This pattern resembles the seasonal density
fluctuation in the Inland Sea, and it is suggested that the species migrates seasonally between inshore and open waters. However it is unreasonable to. suspectthat the species migrates to the offshore open waters, because the species is often
sighted or captured within a few hundred meters from the beach facing the Pacific(Kasuya, unpub.) and has not been sighted in the true offshore water.
Any environmental factors controlling the migration of the species mentioned
above are not certain at present. In the Inland Sea, the species is found in thesurface water temperature between 6°C and 28°C. Such a wide adaptability is
uncommon in the pelagic delphinids (Kasuya, 1976). The migration into Inland
Sea start in January before the lowest peak of the water temperature, and attains
the population peak in April when the water temperature is still lower than theouter waters. These are indications that the migration is not controlled by thewater temperature.
It is generally believed by the Inland Sea fishermen, that the finless porpoise
migrates to the Inland Sea to eat Ammoqytes personatus. The fishing ground of A.
personatus and the distribution of the finless porpoise coincides well. As far as
investigated, only the peak of fishing season of A. personatus in April or May showssome degree of coincidence with the density of the finless porpoise in the Inland
Sea. Though some of the finless porpoises in the Ise Bay were found to feed A.
personatus (Kataoka et al., 1976) and the porpoise in the Inland Sea had the fish in
the stomach (Kureha and Kasuya, unpub. ), the frequency is not high to support the
hypothesis. Alternative explanation is made below in relation to breeding season.

Breeding season and reproductive cycle
Table 5 gives 17 records of the finless porpoise born in aquarium, incidentallykilled, or stranded. The individuals below 100 cm were listed. The higher
frequency between 65 and 85 cm suggests the mean length at birth in this range,
and the parturition season from April to June. Perrin et al. (1977) and Kasuya(1977) gave some methods to estimate the gestation length of odontoceti based on
the neonatal length. The former method and the neonatal length of 75 cm givethe estimated gestation time of 10.6 months. The lattter gives 10.5 months,
assuming 0.135 X gestation time for x-intercept of linear growth line. The mating
and parturition seasons estimated from the analyses of the school structure are from
April to September and from April to August respectively. They give the roughestimation of gestation time of 11 to 12 months. As this value is close to the estimations made above, it will be safe to conclude in the present study that the
pregnancy will last for about 11 months in the finless porpoise.
Furuta et al. (1977) state on this species kept in the Toba Aquarium in theSci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

35

Ise Bay that the copulation occurred most frequently in every April and May inrecent several years and this led to a birth in April 1976 (Table 5). This datum andthe gestation time of about 11 months suggest the parturition season in March andApril. Though this gives a good coincidence with the parturition season indicatedby the newborn calves in Table 5, it does not well agree with the season estimatedfrom the frequency of the cows accompanied by the calf. The difference exist in
the prolongation of the parturition season until August. An important fact wemust remind with this connection is that the analyses of seasonal change of theschool structure are not based on the same group of individuals. The most of the
porpoises leave the Inland Sea after April, and do not come back to the area until
early winter. If it is assumed that the main peak of parturition of the Inland Sea
TABLE 5.

RECORDS OF NEWBORN FINLESS PORPOISE BELOW
100 CM IN BODY LENGTH

Body length

Sex

Date

Locality (latitude)

Author60.0 cm
94.8 cm
96.4 cm
68.8 cm
71.5 cm
72.0 cm
65. 3 cm
79.0cm
83.0 cm
85. 5 cm
85.0cm
81.5cm91.3 cm
80. 0 cm
69.0 cm
71.5 cm
97 .6 cm

S
S
S

20, Mar., 1924
26, Mar., 1924
24, May, 1924
14, Apr., 1977
24, Apr., 1974
3, May, 1976
4, June, 1976
11, Apr., 1973
22, Apr., 1976
27, Apr., 1966-, Apr., 1964
17, Apr., 1976
20, May, 1979
5, June, 1969
16, May, 196327, June, 1973
18, June, 19:33

China
China
China
Omura Bay, 33°N
Inland Sea, Fetus
Inland Sea
Inland Sea
lse Bay, 34°40'N
Ise Bay, 34°40'N
Ise Bay, 34°40'N
Born in Toba Aquar.
Born in Toba Aquar.
Shimizu, 35°N
Sagami Bay, 35°15'N
Yokosuka, 35°14'N
Yokosuka, 35°14'N
Sendai Bay, 38°20'N

2
TK 415
KS 76-7
TK 478345567
TK 296
8
TK 396
9

S
S
~

S
J
J
S
S
J
J

S

1) Howell, 1927. 2) Takemura, p.c. 3) Kataoka et al., 1974 4) Toba Aquarium, unpub. data.
5) Kataoka et al., 1969. 6) Furuta et al., 1977. Measured after death on 3 May. 7) Masaki, p.c.
8) Nakajima, 1963. 9) Ogawa, 1950.

population of the species is in April and May, and that the cows accompanied by
the newborn calf leave the sea for the summering ground, then the above disagreement will be explained. This also explains the rapid drop of the ratio of
the cow with calf in May. We can, by this hypothesis, duly evaluate the ratio of
the nursing cows represented by large number of samples in the months fromMarch to May. Most of the small number of cows which gave birth to the cow
after May will spend the summer in the Inland Sea and will contribute to the apparent increase of nursing cows in the waters. Accordingly it will be most reasonable to suspect that at least one of the main factors controlling the migration of
the species into the Inland Sea could be the breeding.
Sci. Rep. Whales Res. Inst., 'No. 31, 1979

36

KASUYA AND KUREHA

Mizue et al. (1965) estimated for the finless porpoise in the waters off the west
coast of Kyushu that the parturition season will be from late August to early September. Their estimation is based on one lactating female caught in October
1962 and unconfirmed information of the fishermen on the occurrence of newborn
calves in early September. It is strange that they did not refer, for the conclusion,
their specimens collected in late September to early October mainly from theincidental catch in set net and amounting more than 50 individuals. They writethat the smallest individuals they collected were 101.6 cm in females and 112 cm
in males. We are not going to deny the possibility of the tailing off of parturitionseason in September or the presence of small number of newborn calves in themonth. However it will be reasonable to consider that if there is a main peakof parturition in August and September, they should have obtained smaller calvesin their collection. We feel that it is unrealistic to expect for the finless porpoisein the western Kyushu a parturition season different from that in the Inland Sea.
The length of nursing period is estimated from the seasonal change of thefrequencies of nursing cows, of solitary calves, and of juveniles. The ratio of cows
with calf decreases and that of solitary calves increase in October and November.
This season is a time when the migrating porpoises are still outside of the Inland
Sea. Accordingly the change seems to have happened on the resident population.
The decrease, from 27% to 7%, is too large to be explained by the weaning of
calves which have been nursed since previous winter or about 10% of the adultof that season. Accordingly it must be considered that the calves born in thepreceding season are weaned in October and November. Some calves born inthe season will be nursed until next June or July as suggested by the increase ofsolitary calves in the months. This implies that the nursing period will last from
6 to 15 months.
The total number of weaned or suckling calves and that of juveniles attains theequal frequency of about 10% of the adults in March (Fig. 25). The body length
separating the two categories is roughly 120 to 130 cm. The age of individuals at
this body length can be deduced as follows. Firstly the body length frequency of theindividuals stranded or accidentally captured in March to June shows three groups.
The smallest is of 14 individuals ranging from 65.3 cm to 97 .6 cm and consideredas the newborn individuals. The intermediate is composed of total of eight individuals with the distribution of one at 117 cm, three in the range from 125 to
129 cm, one at 130 cm, two from 135 to 139 cm, and one at 141 cm which was anadult female. At least most of the individuals at the lower part of this group will
be one year old. The third group is composed of 22 individuals ranging from145 cm to 188 cm. They must represent older and presumably adult individuals.
Secondly, if the body length of 120 to 130 cm is attained at one year after birth,the mean annual growth rate is from 60 to 73%, which is sufficiently close to thecorresponding values, 55 to 65% known on several delphinids (Kasuya, 1972;
Kasuya et al., 1974) and phocoenids (Nielsen, 1972; Kasuya, 1978). They suggest
mean nursing period not exceeding one year and average body length at weaning
below 120 or 130 cm.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

37

Though the study of age determination and growth of the species is in progress, the exploratory examination of 25 strandings and accidental catches madeafter completion of this study shows that the dentine deposition is annual. Namely
a narrow layer strongly stainable with haematoxylin is deposited between September and June, and a wide weakly stainable dentine in June to September. Thisrate is same in cemental layers. The age frequency of the sample is as follows(both sexes); eight individuals between 0 and 0.9 years (65.3 to 130.2 cm in bodylength), four between 1.0 and 1.9 years (119.8 to 128.0 cm), and one at 3.0 years(length unknown) and 13 between 8 and 23 years. All the individuals in the last
category were sexually mature. This supports the above deduction on the growthof juveniles, and indicates low mortality rate after weaning and before 8 years ofage. These samples were obtained both inside and outside of the Inland Sea.
Most of the females which have weaned the calf before April will start thenext gestation in the mating peak in the April and May. The cows which do
not wean the calf before the mating peak will also be attended by some males as
analysed in the school structure, and will start the nexst pregnancy by the endof August, or in some cases in the next mating season.
TABLE 6.
Month

FREQUENCY OF GROWTH STAGES OF FINLESS PORPOISE
IN THE INLAND SEA AND ADJACENT WATERS
Jan. Feb.

Mar.

Apr.

May

213
20
62
295

122
4
19
145

19
102

49

18
26

14
19

Adult
Juvenile
Calf
Total

7
1
0
8

21

147
13
13
173

Cow with callSingle adult

0
3

3
6

10
61

15
1
5

57

Jun.

Jul.

Aug.

Sep.

78

20
0
8
28

13
0
2
15

28
0
9
37

6

2
4

9

5

5

Oct. Nov.

Dec.

5

24
0
10
34

14
0
2
16

0
3

3
9

0

5

0
0

5

The ratio of the females which breed in two successive years, or that of thefemales which do not breed more than two years are not known. However, thelow ratio of cows with calf attended by adult male, rather sharply defined mating
season, and relatively short nursing period suggest that the most usual breeding
cycle of the population will be about 2 years. Among the five records of the adultfemales, the three individuals caught in June were not lactating nor pregnant
and were either before ovulation with large follicle in the ovary or after recent ovulation, one female caught in November was lactating and simultaneously pregnant
with 43.5 cm fetus, and another female in April was not lactating but pregnant
with 71.5 cm fetus. These informations suggest that the overlapping of lactationand pregnancy is not common (20% of five females).
The examination of gonads provided the following provisional result. In males,.
a 144 cm (1.5 years old) individual seemed to be at early pubertal stage, but otherfour males of 148, 157, 166, and 187 cm were undoubtedly mature. In females
all six females from the Inland Sea measuring 141 cm or more were sexually mature.
Their body lengths were 141, 154, 162, 163, 164, and 164.2 cm. Though, becauseof the underrepresentation of weaned immature individuals, the correct estimation
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

38

KASUYA AND KUREHA

of the body length or age at the onset of sexual maturity is impossible, it will bepossible to conclude that the individuals clasified as " adult " in this study will besexually mature so far as they are concerned with the females. Then the roughestimation of the annual gross production is calculated by assuming the equalsex ratio. As shown in Table 6 the ratio of the adult individuals is 71.5% of thetotal individuals in April. If the " adult " is assumed to be sexually mature, thenumber of adult females will be 4,900x0.715X0.5=1,751. The two years breeding cycle gives calves produced in the Inland Sea in one season as 1,751 x0.5=875
individuals of both sexes. In other words the gross annual reproductive rate seems
to be 17.9%. The annual calf production, 25% of the total adult, is consistent
with the number of calves and juveniles in the following March, 20% of the total
adults (p. 36).
Nothing is known on the popul~tlon discreteness of the species in the Japanese
coastal waters.
ACKNOWLEDGMENTS
This study is greatly indebted to the World Wildlife Fund Japan and Professor
M. Nishiwaki of the University of Ryukyus, who offered the research fund and led
the project. Dr I. Uchida, Director of the Himeji Aquarium provided many
porpoise carcasses in his collection and offered the aquarium facilities for theprocessing. Thanks are also due to the Fisheries Aviation Co. Ltd. for giving theprivilege to analyse their aerial sighting records, and to Mr S. Sudo, Chief Managerof the Shikai Fishermens Cooperative Union for offering a fishing vessel for the
porpoise observation. Mr T. Kataoka of the Toba Aquarium, Dr Y. Naito of
the Polar Research Institute, Dr Y. Masaki of the Far Seas Fisheries ResearchLaboratory, Mr T. Shimoyama of the Matsushima Aquarium, and Mr S. Kondo
in Tadotsu City presented the specimens or unpublished data of the finless porpoise.
Dr. S. Ohsumi of the Far Seas Fisheries Research Laboratory critically read themanuscript. This study was technically assisted by Mr T. Hiwatari, Ms M. Nakagiri, Ms Y. Oka, Ms S. Wada, and Ms K. Iwata. We would like to express our
sincere thanks to all who helped the present study.
REFERENCES
ANON., 1965. On the rearing and ecological observation of the finless black porpoise (Neophocaena phocaenoides). pp. 31-40. In: T. Kataoka (ed.) Ten years history of Toba Aquarium, Toba Aquarium, Toba.
(In Japanese)
ANON., 1978. Annual report on the trend offisheries presented to the 87th congress, 53th year of Showa [1978]. Tokyo,
159 pp. (In Japanese)
BARHAM, E. G., ]. C. SWEENEY, S. LEATHERWOOD, R. K. BEGGS, and C. L BARHA11, 1979, Aerial census
of the bottlenose dolphin, Tursiops truncatus, in a region of the Texas coast. Fish. Bull. 77 (3) : (inpress).
CHUGOKU SHIKOKU NosEIKYOKU [C. S. AGRICCL. ADMINIS. BuR.], 1978. Fisheries statistics of the Inland
Sea indicated by areas, pp. 86-97. (In Japanese).

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

39

Dm, I., 1974. Further development of whale sighting theory. pp. 359-368. In: W. F. Schevill (ed.) The
Whale Problem, A Status Report, Harvard Univ. Press, Cambridge, Massachusetts, 519 pp.
FURUTA, M., 0. TsuKADA, and T. KATAOKA, 1977. On the birth offinless porpoise, Neophocaenaphocaenoides
in captivity. pp. 1-12. In: Toba Aquarium (ed.) Report on the rearing and behavior of finless porpoise(Neophocaena phocaenoides) in Toba Aquarium, Toba Aquarium, Toba, 50 pp. (In Japanese withEnglish summary)
HosmNO, Y., 1972. Pollution of the Inland Sea. Iwanami, Tokyo. 202 pp. (In Japanese)
HOWELL, A. B., 1927. Contribution to the anatomy of the Chinese finless porpoise Neomeris phocaenoides.
Pros. U.S. Nat. Mus., 70 (13): 1-43, pl. !.
KABURAGI, T., 1932. The migrating place of the Indian porpoise (Neophocaena phocaenoides) and fishery,
Hiroshima Prefecture. pp. 72-75. In: Ministry of Education (ed.) Report of the survey of natural monuments, animals part 2, Min. Education, Tokyo, 114 pp.
KASUYA, T., 1972. Growth and reproduction of Stenella caeruleoalba based on the age determination by meansof dentinal growth layers. Sci. Rep. Whales Res. Inst., 24: 57-79.
KASUYA, T., 1976. Preliminary report of the biology, catch, and populations of Phocoenoides in the western
North Pacific. FAO/ACMRR/SC/21, 20 pp.
KAsuYA, T., 1977. Age determination and growth of the Baird's beaked whale with a comment on the feta!
growth rate. Sci. Rep. Whales Res. Inst., 29: 1-20.
KASUYA, T., 1978. The life history of Dall's porpoise with special reference to the stock off the Pacific coastof Japan, Sci. Rep. Whales Res. Inst., 30: 1-63.
KASUYA, T., N. MIYAZAKI, and VV. F. DAWBIN, 1974. Growth and reproduction of Stenella attenuata in the
Pacific coast of Japan. Sci. Rep. Whales Res. Inst., 26: 157-226.
KATAOKA, T., M. FURUTA, and S. KITAMURA, 1974. On the feeding to newly captured finless black porpoise,
Neophocaena phocaenoides. J. Jap. Ass. Z,ool. Garden. Aquariums, 16 (1): 1-5. (In Japanese with English
summary)
KATAOKA, T., S. KITAMURA, M. SEKIDO, and K. YAMAMOTO, 1976. On the feeding habit offinless porpoise(Neophocaena Phocaenoides). Mie Seibutsu, 24 and 25: 29-36. (In Japanese with English summary)
KATAOKA, T., S. KITAMURA, K. YAMAMOTO, S., MANABE, and M. SEKIDO, 1969. On the external proportions of finless black porpoise, Neophocaena phocaenoides. J. Jap. Ass. Z,ool. Garden. Aquariums, I I (3):54-56.
KURODA, N., 1940. On the cetacean in the Suruga Bay. Shokubtsu o_yobi Dobutsu, 8 (5): 1-10. (InJapanese)
MIZUE, K. A. TAKEMURA, and K. NAKASAI, 1968. Studies on the little toothed whales in the west sea areaof Kyushu-XV, underwater sound of the Chinese finless porpoise caught in the Japanese coastal sea.
Bull. Fae. Fish. Nagasaki Univ., 25: 25-32.
MizuE, K., K. YosHIDA, and Y. MASAKI, 1965. Studies on the little toothed whales in the west sea area of
Kyushu-XII, Neomeris phocaenoides, so-called Japanese "sunameri ", caught in the coast of Tachibana
Bay, Nagasaki Pref. Bull. Fae. Fish. Nagasaki Univ., 18: 7-29. (In Japanese with English summary).
NAKAJIMA, M., 1963. A lost infant of finless porpoise. Geiken Tsushin, 147:1-4. (In Japanese)
NIELSEN, H. G., 1972. Age determination of the harbour porpoise Phocoena phocoena (L.) (cetacea). Vidensk.
Meddr. Dansk Naturh. Foren., 135: 61-84.
OGAWA, T., 1950. A dolphin research trip in the summer of Showa 9th. pp. 28-37. In: T. Ogawa A
tale of whales, Chuo-koron, Tokyo, 211 pp. (In Japanese)
PERRIN, W. F., D. B. HOLTS, and R. B. MILLER, 1977. Growth and reproduction of the eastern spinner
dolphin, a geographical form of Stenella longirostris in the eastern tropical Pacific. Fish. Bull., 75 (4):725-750.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

40

KASUYA AND KUREHA
APPENDIX I.
Expedition

no.

date
12, IV, '76

I
223, IV, '76
22, VII, '76

I
34, VIII, '76
12, XI, '76

4

2, XII, '76
2, Ill, '77

515, III, '77
8, v, '77

6

19, v, '77
14, VI, '77

725, VI, '77
15, IX, '77

828, IX, '77
27, I, '78

910, II, '78
6, III, '78

10

15, III, '78
15, IV, '78

I
I

I
I

I

I
I
I

x 6

30, IV, '78
17, I, '77

Xl39, VIII, '77

Xl525, x, '77

Xl615, XI, '77

Xl7

13, XII, '77

Area
N. mile 2
km 2
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles

RESULT OF SURVEY OF

1

2

3

4

5

Sum

245.2
841

433.7
1,488

255. l
875

358.8
1,231

108.0
370

1,400.8
4,805

17.5
0
0
17.4
0
0
13.8
0
0
12.8
0
0
13.8
0
0
14.0
2
1.429
13.7
0
0
26.5
0
0
16.0
10
6.250

130.7
83
6.350
135.2
35
2.589
141.6
17
1.201
135.5
46
3.395
122.8
40
3.257
134.4
27
2.009
142.5
14
0.982
98.7
2
0.203

119.4
74
6.198
123.7
12
0.970
138.4
19
1.373
142.7
44
3.083
111.5
24
2.152
109.0
30
2.752
95.4
6
0.629
67.3
19
2.823

144.5
65
4.498
122.4
13
1.062
88.6
13
1.467
123.4
43
3.485
102. l20
1.959
117 .5
21
1.787
144.4
12
0.831
86.6
10
1.155

156.2
32
2.049

136.3
81
5.943

108.4
72
6.642

4. 7
0
0
5.0
4
8.000
5.2
0
0
4.7
0
0

22.9
0
0
19.0
2
1.042
51.0
0
0
71.0
7
0.986
28.5
2
0.701
60.4
0
0
33.2
0
0
29.8
0.336
20.8
41
19.71255.6
44
7 .914
29.8
0
0
29.7
0
0
31.0
0.323
22.2
5
2.252
21.4
0
0

417.5
222
5.317
417.8
62
1.484
437.0
49
1.121
486.4
140
2.878
377.7
86
2.277
435. l78
1. 793
429.5
34
0.791
296.1
32
1.081
47.3
41
8.668
472.5
239
5.058
29.8
0
0
34.4
0
0
36.0
5
1.389
27.4
5
1.825
26.1
0
0

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

41

FINLESS PORPOISE IN THE INLAND SEA
11

12

13

14

Sum

21

22

23

Sum

Grand total

332.7
1, 141612. l2,099

327.6
1, 124203.1
697

1,475.5
5,061

894.6
3,068

87.7
301

298.9
1,025

1,281.2
4,394

4,157.5
14,260

34 .2

17 .2

0.2

0.2

0
0

0
0

10.0
0
0
24.1
0
0
24.4

13.0
26
20.000
53.2
4
0.752
97.3
0
0
92.2
6
0.651
71.9
0
0
95.2
27
2.836
81.2
19
2.340
51.0

4
1.170
35.9
12
3.343
47.2
2
0.424
34.2
13
3.801
25.3
16
6.324
35.4

0.581
16.3
0
0
32.1
0
0
50.4
1
0.198
22.4
0
0
57.9

64.4
31
4.814
115.4
16
1.386
200.7
2

3

2

1.840
17.0
0
0
34.5
3
0.870

0.392

0.565
41.2
2
0.485
21.9
0
0

91.3
12
1.314

'.29. 74
1. 347

20.4
0
0

0.100
201.3
22
1.093
141.8
20
1.410
211.2
30
1.420
174.8
21
1.201
131.0
8
0.611
17.0
0
0
175.9
19
1.080

5.3
0
0
4.3
0
0
4.0
0
0
4.7
6
12.76628.0
5I. 786
25.2
0
0
20.9
0
0
21.2
3
1.415

33.3
5
1.502
29.5
0
0
24.9
0
0
25.9
9
3.475

2

0.820
22.2
4
1.802
22.7
0
0
19.6
0
0
16.3

2

0.173
32.8
0
0
41.8
3
0.718

7.2
0
0
15.2
0
0
50.0
0
0
49.6
4
0.806
43.8

0
0
57.7
2
0.347
29.8

2.2
0
0
11.2
0
0
2.2
0
0
4.4
2.273
4.4
0
0
2.1
0
0

0

0

86.5
0
0

4.4
0
0

0

9.4

0
0

0
0

28.3
0
0
3.0
3
10.000
1.6
0
0
22.9
0
0
25.3
0
0
0.4
0
0

54.7
0
0
55.2
3
0.543
55.6
5
0.899
71.1
0
0
85.1

2.1
0
0

93.0
0
0

2

0.235
30.2
0
0

482.1
253
5.248
542.6
78
1.438
692.4
51
0. 737
742.9
165
2.221
575.1
111
1.930
717.4
108
1.505
689.4
57
0.827
457.3
40
0.875
64.3
41
0.638
741.4
258
3.480
29.8
0
0
67.7
5

0.4
0
0

0.4
0
0
0.4
0
0

0.4
0
0
0.4
0
0
0.4
0
0

0.739
65.9
5
0.759
52.7
5
0.949
52.4
9
1. 718Continued ...

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND KUREHA

42

APPENDIX I.
X2121, VII, '78

X22

17, VIII, '78

X23

19, IX, '78

X24

17, x, '78

N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles
N. milesNo. sighted
No./10 miles

4.5
0
0
4.4
0
0
4.9
0
0
7.0
0
0

39.7
4
1.008
33.5
0
0
30.6
0
0
34.0
0
0

35.2
4
1.136
29. l
0
0
25.7
0
0
27.0
0
0

X : Survey conducted by K. Kureha in the areas 4, 5, 13, and 14. Four surveys conducted at Akashi
and Kanmon passes not listed.
1 : Includes Xl, May 5, 25.7 miles, 0 porpoise. 47 individuals in 16 schools observed on a fishing vessel
not included (area 4).
2: Includes X2, Aug. 8, 18.8 miles, 2 porpoises.
3: Includes X3, Oct. 20, 25.5 miles, 0 porpoise, X4 Nov. 18, 10.2 miles, 0 porpoise, and X5 Dec. 16,
42.3 miles, 0 porpoise.
4: Includes X7, Feb. 23, 20.4 miles, 0 porpoise, and X8 and X9 Mar. 1 and 22, 116.4 miles, 9 porpoises.

APPENDIX II.
Expedition
no.

date

4
1
9
5
6
2
7
3
8

2, III-15, III, '77
12, IV-23, IV, '76
15, IV-30, IV, '78
8, V-19, V, '77
14, VI-25, VI, '77
22, VII- 4, VIII, '76
15, IX-28, IX, '77
12, XI- 2, XII, '76
27, I-10, II, '78

11

MINIMUM ESTJMATION OF PORPOISE

Nearshore stratum
3

5

sumo

421

325

438

94

1,488

257

143

149

6

555

250

69

110

14

494

193

265

239

7

704

210

} 0
} 51
} 0

}

Intermediate42

sum 2l
1,170(201)
1, 574 (279)
1,970(380)641 (143)
665 (146)
744 (190)
335 (97)950 (261)
796 (215)

11

12

13

60

350

179

68

226

221

0

343

194

139

46

53

Calculated for each area after combining the data of two or three expeditions. The r values used are
0.391 (March to April), 0.438 (May to June), 0.306 (July to September), and 0.178 (November to

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FINLESS PORPOISE

43

Continued
4.1
0
0
4.4
0
0
4.0
0
0
4.4
0
0

25.5
4
1.569
25.0
0
0
26.9
0
0
29.0
0
0

29.6
4
1.351
29.4
0
0
30.9
0
0
33 .4
0
0

0.4
0
0
0.4
0
0
0.4
0
0

0.4
0
0
0.4
0
0
0.4
0
0

69.7
8
1.148
63.3
0
0
61.9
0
0
67.4
0
0

5: Includes XlO May 12, 59.5 miles, 2 porpoises.
6: Includes Xll Jul. 14, 66.0 miles, 2 porpoises.
7: Includes Xl4 Sept. 18, 66.4 miles, 0 porpoise.
8: Includes Xl8 Jan. 20, 517 miles, 1 porpoise, and Xl9 Feb. 17, 28.7 miles, 3 porpoises.
9: Survey conducted mainly at four straight and waters adjacent to the Inland Sea. Only the Inland
Sea records are listed.
10: Includes X 20 Apr. 13 49.3 miles 0 porpoise. Surveys made outside of the Inland Sea excluded.

POPULATION IN THE INLAND SEA, k=l ASSUMED
Offshore stratum

stratum
14

sum 1>

12

601

6

521

0

537

46

284

sum 2>
469 (173)
1, 502 (752)444 (185)
418 (283)
555 (177)
732 (560)
536 (405)
89 (88)474 (248)

21

22

23

sum 1>

0

0

432

432

87

23

0

110

90

0

0

90

0

0

0

0

sum 2>
202 (200)00232 (135)

Febraury).
2> Calculated for each stratum after combining the data of areas.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

60
91 (90)00Grand
totaP>

2,521
1,186
1, 121988

Grand
total2>
1,841 (332)
3,076 (810)2,414(432)
1,291 (344)
1,220 (230)
1,476 (591)962 (426)
1,039 (276)
1,270 (328)Standard error in parenthesis.

44

KASUYA Al'\D KUREHA

EXPLANATION OF PLATESPLATE I
Fig. I. Aerial photograph of seven schools of the finless porpoise. 1044 hrs, 12
July, 1976. 34°00'N, 132°25'E. Numeral and arrow indicate the position andnumber of distant individuals. Copyright, Fisheries Aviation Co. Ltd., Kojimachi,
Tokyo.
Fig. 2. Closeup of the three schools in Fig. I. It is also possible to consider themas one school. Copyright, Fisheries Aviation Co. Ltd.
PLATE II
Fig. I. Aerial photograph of two schools (two and seven individuals) of the finless
porpoise. Data are same with PLATE I. Numeral and arrow indicate the position and number of submerged individuals, all adult. Copyright, Fisheries
Aviation Co. Ltd.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

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PL
ATE I
I

KASUYA A:¥"D K UREHA

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λr
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.31,1979

AGE DETERMINATION, REPRODUCTION, AND
GROWTH OF THE FRANCISCANA DOLPHIN,
PONTOPORIA BLAINVILLEITOSHIO KASUYA
Ocean Research Institute, University of Tokyo, TokyoAND
ROBERT L. BROWNELL, JR.
National Fish and Wildlife Laboratory, National lviuseumof Natural Histor_v, Washington, D.C. 20560

ABSTRACTAn examination was made of 260 Franciscana dolphins taken off the
Uruguayan coast. Deposition of dentinal and cementa! layers is annualwith the formation of an unstainable layer between August and November.
Cementum deposition continues after the probable cessation of dentine deposition at four to seven years. Females usually have a 2-year reproductive cycle.
Calves are born at a length from 70 to 75 cm after a gestation of about 10.5
months, and weaned before one year of age. Sexual maturity is attained inboth sexes at an age between two and three years, which corresponds to thelength of 131 cm and weight of 25 to 29 kg in males, and to 140 cm and 33
to 34 kg in females. Physical maturity is attained soon after the onset of
sexual maturity. Sex ratio is at parity in immature individuals.
INTRODUCTION

The Franciscana dolphin Pontoporia blainvillei (Gervais and d'Orbigny, 1844) inhabits the coastal waters off eastern South America from Valdes Peninsula (42°30'S ),Argentina, north to the Tropic of Capricorn near Ubatuba, Brazil (Ximenez,
Langguth, and Praderi, 1972).
The purpose of this study was to investigate reproductive parameters andgrowth in this species. Specific objectives included collection and analysis of
information on age of sexual maturity, frequency and timing of calving, growth,and sex and age composition.
MATERIALS AND METHODS

The dolphins examined in this study, 123 females and 137 males, were collected
dead, offshore from Punta del Diablo, Uruguay, by local fishermen in gillnets set
for sharks. Details on the fishing methods used at Punta del Diablo are given
by Van Erp (1969), Brownell and Ness (1970), Pilleri (1971), and Brownell (1975).
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 45-67

46

KASUYA A"'.\'D BROWNELL

Ma.le

25
20

15
<ll

~

10

"O

·:;;
"O

5

c

Female

0

z

15
10

5
ou.....1--...-~'r'-""1"''IL''IL'-..U~~~~~~~..._i..-i~=-

eo

so

100

110

120

130

140

1so

1so

110

Body length in cm
Fig. 1. Body length frequency of Pontoporia blaiiwillei. Right column (black) represents the random sample cited from Brownell (1975), left column the present
material, and shaded area individuals of unknown age.
TABLE 1.

MATERIALS OF PONTOPORIA BLAINVILLEI USED IN THIS STUDY

Month
Male 1>
2)

Female1>
2)

Female, %'>79 3 >
0
57 3 >
0
41.9

II

III

VI

VII

VIII

3
0
7
0
'70.0

2
0
3
0
60.0

3
0
3
0
50.0

1
7
0
0
0.0
0.0

3

,, '%2)
1>:

Random s:imple,

2>:

4
25.0
80.0

IX
1
2
3
66.7
75.0

x
0
2
6
66.7
100.0

XI

XII

Total

0
1
2
6

33

126
11
98
25
43.8
69.4

rno.o
85.7

21
6
38.9
85.7

3

Nonrandom sample, >: One aged individual of unknown length included.

Over 400 dolphins were collected by us or a local fisherman Amilcar Olivera (AO)
between December 1970 and December 1973. The sample was heavily biased
toward December and January (austral summer), because of the seasonal natureof the shark fishery, with minimal coverage during the rest of the year. The bodyweight and external proportion data were obtained from specimens taken between
December 1972 and January 1973. The standard total length of each specimen
was measured in a straight line from the tip of the rostrum to the notch in the
flukes. The material we collected was a random sample of the catch, but the AO
specimens are biased towards adult females exceeding 135 cm in total length.
Olivera only agreed to collect a limited number of specimens. Therefore, we
asked him, in our absence, to collect all adult females landed.

Tooth preparation
Although the anterior teeth are slightly longer than the others, the difference
is not as extreme as in Platanista. Three to five contiguous mandibular teeth,
Sci. Rep. Whales Res. Inst.,

N1J. 31, 1979

FRANCISCANA DOLPHIN

47

starting at approximately the tenth from the front and moving posteriorly, werecollected and fixed in 10% formalin solution or 70% ethanol.
The principle of the preparation is to decalcify and stain a thin longitudinalground section glued with cyanoacrylate monomer on a clear plastic plate (Kasuya,1978). The tooth was ground down to a thickness of 20 to 30 µm. The decalcification was done with 5% formic acid for several hours at about 25°C. The
slide was then rinsed in running water for two hours or longer, stained with Mayer's
haematoxylin for 30 minutes, and finally mounted with Canadian balsam. Bothanterio-posterior and lingual-buccal sections were prepared for most individuals;
they were not significantly different in readability. However, since the teeth arecompressed anterior-posteriorly, the chance of missing the pulp cavity is less inthe anterio-posterior section.
Reading of growth layers
The age determination was based on the growth layers in the dentine andcementum. Observations of growth layers were made with a compound microscope (40 to 120 X ), without referring to the biological data. At first, about 20
slides, probably representing new born individuals and very old individuals, wereselected, and the standard of reading was established by comparing the growthstage and layer counts of the slides. Then all the slides were read by the same
standard. If the number of cemental layers exceeded significantly that in dentine,
the former was taken as the age. This only occurred when teeth had narrow pulp
cav1t1es. In cases where the counts of dentine and of cementa! layers differed
only by a fraction of a layer, the dentine count was taken as the age because it isclearer and more reliable than the cementa! layer. If the independent readingsof the growth layers in the same tissue of two slides from one individual were different, they were carefully compared including the difference of the finish, and thena final decision was made without referring to the biological data. When there wasno choice in the interpretation of the fraction of the last incomplete layer, themean of the two counts was used.
One complete growth cycle was considered to be composed of one broadstainable layer and a narrow unstainable layer. The final fractional layer was
estimated by eye to the nearest 0.1 layer. Although this is not highly accurate, it
gives a better result when the sample is seasonally biased.

AGE DETERMINATION
Morphology and number ef teeth
The number of teeth ranges from 48 to 61 on each tooth row (Table 2).
There are no consistent sexual or bilateral differences. However, the number ofteeth is significantly different between the upper and lower jaws (p<0.001).
The excess of upper teeth over the lower varies from -1 to + 11 with a mean of
3.3 in females, and from -1 to +9 with a mean of 2.7 in males. This is related
to the downward curving of the rostrum. In Platanista gangetica, the rostrum isSci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND BROWNELL

48

curved upward and the number of lower teeth exceeds the upper (Kasuya, 1973).
The straight length of a tooth is approximately 7 to 10 mm. The pointed
crown is compressed anterio-posteriorly and the tip is curved mesially. The rootis flattened lingual-buccally and the proximal tip is usually curved, through thegrowth, towards the posterior direction. The cementum forms a thick cingulum
at the cervix of the tooth. In old individuals the root is covered by the cementum
leaving small branching canals connecting the narrow pulp cavity and externalsurface of cementum. (Pl. IV, Fig. 1).
TABLE 2.
Position
Male
Up. left
Up. right
Lo. left
Lo. right
FemaleUp. left
Up. right
Lo. left
Lo. right

TOOTH COUNT OF PONTOPORIA BLAINVILLEI

Sample

Range

Mean

SD

SE

3·3
33
33
32

51-60
51-60
48-61
49-59

54.6
55.0
53.3
53.4

2.25
2.24
2.54
2.33

0.39
0.39
0.44
0.41

39
39
38
38

50-60
50-61
49-58
49-59

55.4
55.3
53.7
53.6

2.62
2.67
2.2li
2.40

0.42
0.43
0.37
0.39

Growth layers
When a thin ground section is observed under transmitted light, the growthlayers are seen as the alternation of optical density. The decalcification and staining of a thin ground section partially masked with wax indicates that the opaquelayer in the cementum and dentine corresponds to the stainable layer (Pl. IV, Fig.
2). The minute layer in dentine is detected more clearly on decalcified and stained
slides.
The fetal dentine has a thick, uniform, moderately stainable layer, and theneonatal line is an unstainable layer of about 5 µm width deposited on the innerwall of fetal dentine. Three kinds of layers and presumably cycles are found in
the postnatal dentine. The first is the coarse layer and is the most conspicuous.
As discussed later, we believe that this layer represents the annual cycle. One
cycle of this layer is composed of a thin (about 10 to 20 µm in the first layer) conspicuous unstainable layer and a wide stainable layer. The unstainable layer isclearer near the cusp than at the root. The stainability in the stainable zone is
not uniform, but consists of finer layers ranging from 10 to 17 in number with amode at 12 or 13. This is the second kind oflayer, which may correspond to theshort cycle cemental layers in the teeth of the Baird's beaked whale, Berardius
bairdii, suspected by Kasuya (1977) to represent a lunar cycle or an endogenous
rhythm of about one month. Some of these fine layers deposited just prior to theunstainable layer of the annual cycle are always stained more strongly than thepreceeding stainable dentine which forms the stainable layer of the annual cycle.
In other words, the annual cycle of dentine deposition is formed by the enhanceSci. Rep. Whales Res. Inst.,
No. 31, 1979

49

FRANCISCANA DOLPHIN

ment of some of the shorter cycle layers. This cycle is inconspicuous in the thirdand successive annual layers. There are often observed several narrow layers(third layer) in some of the second kind of layers, but it is almost impossible tocount them.
In the cementum, the alternation of narrow stainable layers and wide weakly
stainable layers is the only way to read layers. From comparison with the dentinal
layers, it appears that the stainable cementum corresponds to the strongly stainabledentine deposited just prior to the unstainable layer of the annual cycle. This
cemental cycle is clearest usually on the cusp side of the cingulum.

1.2

Male

E
E

c

0

1.0

c

0

I
I

0

0.8

E

u 0.6

.....
0
I/)

0.4

Cll

~
u 0.2
.s::.

I-

,tQ

0

o,

•'

~

,'

,,--o
0

0

.

/Oat _a,oO<flro

0

0

.

0

0
0

00

tJ'

0

0

0

0 0
0
.,

0

•

cJJ

..

~~

o,,~

o

~/ 0
,'° •

0

I

ee
0

o•o
•

•

••

•

•

0
0

O/' 0

q, _,' 0

I'•,/

/'•

,
0/

I
I

O

•

0
0

~----'i- 0

,

0

I

0

O

Cll

0

8

I

I
I
I

0

0

oO
0

0 /•O

Cll

Ill

0

0

E
:J

Female

0

•
••

•It •

.· ...•.· . ..•.. .

~/I • tP/•·
~ f> .o : ...

1••

Body length in cm
Fig. 2. Scatter plots of thickness of cementum at cingulum on body length. Opencircle and dotted line indicate anterio-posterior thickness, and closed circle andsolid line ligual-buccal thickness.

Thickness of cementa[ layers
Figure 2 shows the maximum thickness of cementum at the cingulum plottedagainst the body length. The cementum was present on all the individuals, which
had at least some teeth erupted. There were three juveniles, one female (98.5 cm)
and two males (84.5 and 96.0 cm), where 20 to 30 teeth on each jaw were left
unerupted. The teeth of these individuals had cementum of 5 to 12 µm in thickness. Their postnatal dentine ranged from 65 to 110 µm in thickness, or 14 to
24% of the mean thickness of the first postnatal dentine shown in Table 3. These
data indicate that tooth eruption and cemental deposition starts as early as one
or two months after birth.
These is a great deal of individual variation in cementum thickness. This
would, in some degree, have been caused by technical problem with preparation.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

50

KASUYA AND BROWNELL

However, it is clear that the cementum is thicker on the anterio-posterior direction,and that there is no sexual dimorphism of the thickness if compared between individuals of the same body length.
The relationship between the thickness of cementum and age is shown in
Fig. 3. The deposition is faster in the first 3 years, and then changes to a slower
growth phase which seems to continue until at least 9 years of age. The difference
between sexes is not significant.
1.2

, .0

1
0

0.8
0.6

Cementum13i 1.:~~.:3~1
3 h.. 2

E

E 0.8
c 0.6

25r.6---<(-' /':c 0.4 /I/i
3

<I>

:

i

122

1 ·-o-----~13'

J.{ i 7 '5DentineI

E 0.2 ~l<I>~~ 1.60f:,~ 1.4 ~.

Pulp cavity"

1.2 '\
1.0

\25

0.8

\!2j1 1r .

0.4

l~17
! ',,:
! ',

0.2

'

0.6

5

i ·. 9! ''>-----6.. --- 1 --~ _ 11 _Ji... 3
2

2

5

4

6

8

.

1

10

12 13-

Age in years
Fig. 3. Relationship between anterio-posterior dimensions of the tooth and age.
Closed circle and solid line indicate mean value in males, open circle and dottedline that in females, vertical line observed range, and numerals the number ofsamples. For further explanations see text.

Thickness of dentinal layers
Figure 4 shows the relationship between body leng1~1. and thickness of dentine
measured at the level corresponding to the proximal end of the prenatal dentine.
There was no sexual dimorphism in the thickness nor any difference related to thedirection of the preparation. Although the dentine deposition is slow in juveniles
under 100 cm in body length, there is a sudden increase in the thickness at lengths
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

51

FRANCISCANA DOLPHIN

E
E

Femal<?

Male

c

e

0.8

c
....c 0.6e'O... 11:1 .. 9 ..

0

,

~

0

•oo

o

/

,'

.o.......... ~,.. 0

Cl.I

-

0;' 0

0

~

G>

0

•O

00 0

8.

U"~:

0.4

• o ,•O •

,,. •

0

•
0

.. 0 • • 0

Ill
Ill
G>

0•

00

~

•

o

•

·~

•

c 0.2

. •••

~

u

.c

!-

0

0

100

80

120

•

0

100

140

120

140

160

Body length in cm
Fig. 4.

Scatter plots of the thickness of dentine on body length.

For key see Fig.

2.
TABLE 3.

THICKl"iESS OF DENTINAL LAYERS OF PONTOPORIA BLAINVILLEI (in µm)
Lingual-buccal

Male
lst
2nd
3rd
Femalelst
2nd
3rd

An teri o-pos terior

No.

Mean

SD

No.

Mean

SD

53
28
4

432
206
133

88.3
55.7
10.4

:36
18
4

458
204
100

95.ti
57.4
24.5

56
27
4

462
214
95

81.3
66.4
32.4

55
34
14

469
202
102

88.8
71.8
40.6

of 100 cm in males and 105 cm in females, which is again followed by a slower increase.
The body length of rapid dentine deposition coincides with an age of 0.5 to 1.0 years(Fig. 7). The increase of dentine thickness is almost negligible after the age of
4 years, and this is reflected by the change of the diameter of pulp cavity (Fig. 3 ).
The diameter of the pulp cavity attains the minimum of 40 to 100 µm at about 4
years of age. This stage nearly coincides, as mentioned below, with the age when
the number of cemental layers exceeds that of dentinal layers of the same individual.
Furthermore, in these individuals, the pulp wall is covered by strongly stainablestructureless thin dentine. We consider that this is an indication of the cessationof dentine deposition or of the deposition of such a thin dentine that the growthlayers in it cannot be counted by the present method.

Accumulation rate of the layer
Figure 5 shows the relationship between the number of layers of dentine andcementum in the same individual. When there are less than four dentine layers,
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

52

KASUYA AND BROWNELL

the difference between these two figures is usually less than a fraction of a layer.
The number of dentine layers usually exceeds the number of cementa! layers bya small fraction because of the difficulty of distinguishing a thin incomplete layer
in the cementum. The two figures often disagree after the age of 4 layers in males
or 5 layers in females. This suggests that the accumulation rate of the layers in
the two tissues is the same up to an age of approximately 4 to 5 layers (=years).
After this age, it appears that only the cementa! layer retains the same deposition
rate. It must be noted, however, that age determination by means of cementa!
layers is less accurate than by dentinal layers.
Female

Male

0

•

. 2

z

0 0

B

10

No. of

2-Z.

5-9

•

10-

12

..

t

•

•

14

16

cementa!

2

10

4

12

layersFig. 5. Relationship between number of growth layers lil dentine and that in
cementum.
TABLE 4.
Month
Unstainable
Male
FemaleTotal, no.

",%

Stainable
Male
FemaleTotal, no.

",%

NATURE OF THE LAST INCOMPLETE DENTINAL LAYER
II

III

VI

0

0
.0
0
0.0

1
2
100.0

7
10
17
18.5

14.3

0
0
0
0.0

40
35
75
81.5

0
6
6
85.7

3
4
100.0

VIII

IX

x

XI

XII

2
66.7

0
0
0
0.0

0
2
2
100.0

0
2
2
40.0

10
2
12
27.3

0
2
2
100.U

0
0

0
3
3
60.0

13
19
32
71.1

0

33.3

0

0.0

The seasonal frequency of the condition of the last incomplete layer wasstudied only on the dentinal layers, because the observation is more difficult on
cementa! layers. Only individuals with less than three growth layers were used.
These results are shown in Table 4. There is some difficulty in determining thenature of the last incomplete layer, because of the presence of finer structures inthe dentine. This will increase the apparent individual variatiod in the seasonal
formation of a certain kind of layer. A sufficient number of samples was available only in December and January, when most of individuals (70 to 80%) were
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPHIN

53

forming the stainable type of dentine. The ratio seems to be higher in January
through June, but decreases from August to November when only half of 12 individuals are forming the stainable dentine. These data, together with the factthat the thickness of unstainable layer is less than 5% of the total thickness of one
dentinal layer, suggests that the period of the formation of unstainable dentine israther short in each individual and that it occurs at various times between Augustand November.
Figure 6 shows the seasonal change of the fractional part of the dentinal layercount. This is estimated by eye at the time of age determination without referringto the biological data or the date of death. The graph indicates that the thicknessof incomplete layer increases linearly from November to September of the nextyear, when the deposition ofunstainable layer seems to occur in most of individuals,
to complete one deposition cycle.
From the above analyses it is concluded that the coarse dentinal layer isdeposited annually. The cementa! layer deposition also follows the same cycle.
, '(

I j

/

,

80

/

,,

.£: 60

,,,,"

Ill
Ill

\

(!)

~ 40
u
.c

/

~:/

/

/

,,/ '•

I-

/

20

'/

//~
,.'//I'

0

/

N

D

I

J

A
F

•
M A M J
Month

J

A

S

0

Fig. 6. Seasonal change of the thickness of the last incomplete layers in dentine.
For explanations see text.

GROWTH

Length at birth
The largest fetuses encountered were a male and female 68 and 70 cm long,respectively. The three next largest fetuses were 66, 65, and 63 cm. The smallest
neonatal animals were two males 84 and 84.5 cm long. The two next smallest
dolphins were a male and female, both 85 cm in length. The next was a male
92 cm long. The age of the 84.5 cm neonate was estimated at 0.2 years. Therefore, we conclude that the body length at birth is greater than 70 cm and less thanSci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND BROWNELL

54

85 cm, probably in the low 70 cm range.
Postnatal growth in body length

The calves which are born at a length between 70 and 75 cm attain a mean
length of 96.2 cm (13 individuals, sexes combined) at the age of about 0.5 year.
Although the sexual dimorphism in the body length might be present at the age
below I year (Table 5 ), the observed difference is not significant (p= 0.2). The
growth is slower in males and the mean body lengths are significantly smaller thanthose of females after the age of 1 year (p<0.001). No secondary growth spurt isobserved in either sex. The present materials indicate that the growth ceases at
the age of 4 years (Fig. 7). The mean asymptotic length of 133.3 cm for males
and 153.0 cm for females are estimated as the mean body length of individuals
4 years or older.
If the Gompertz equation (Zweifel and Perrin, in press) is fitted for threemean lengths below 3 years by forcing to have the asymptotic length of 133.3 cm,
the least squares calculation gives following equation for males:
TABLE 5.
Age (yr.)

AGE AND BODY LENGTH (cm) IN PONTOPORIA BLAINVILLEI
Mean age

No.

Range

Mean

S.D.

0.3
1.2
2.2
3.3
l:i.2

5
48
21
2
21

84.0-102.0
90.5-134.0
110. 0-152. 0
118.0-129.0
122.0-147.0

92.7
115. 7
128.8
123.5
133.3

8.04
9.72
10.59

0.5
1.3
2.2
3.2
6.4

8
54
25
0
28

85.0-105.0
100.0-143.0
120.0-169.0
145.0-160.0
137.0-171.0

98.4
122.6
141.2
152.2
152.8

6.02
10.64
14.41
5.46
9.23

Male

o;;;;, <l1;;;;, <22;;;;, <33;;;;, <44;;;;, ;;;;16
Femaleo;;;;, <1l;;;;, <22;;;;, <33;;;;, <44;;;;, ;;;;13
TABLE 6.
Age (yr.)

8.58

AGE AND BODY WEIGHT (kg) IN PONTOPORIA BLAINVILLEI
Mean age

No.

Range

Mean

S.D.

0.3
1.2
2.2
3.0
8.5

4
21
10

10.9-17.2
11.8-24.5
16.3-35. 7
17.2
19.9-32.2

14.2
18.6
24.0
17.2
28.2

2.74
4.35
6.40

0.3
1.2
2.3
3.0
5.6

3
26
9

11.8-14.9
14.5-30.8
17.7-34.9
34.4
29.9-52.1

13 .1
22.9
26.3
34.4
40.3

1.59
4. 72
l:i. 76

Maleo;;;;, <I
1;;;;, <22;;;;, <33;;;;, <45;;;;, :;:;;; 16
Female1>o;;;;, <11;;;;, <22;;;;, <33;;;;, <44;;;;, ;;;;8
1> No

4

5

5.66

8.55

pregnant female included.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPHIN

55

170

E i:Jour·
7 ~L-.!-.-f---'--!--'---!~'---'---'--~1~0-'-~12,.......,--:1~1-'---!~'--7--'-~--'--7.--'--:~'--~10--!'--:1~2-'

Age in years
Fig. 7. Scatter plots of body length vs. age, males at the left and females at theright. Immature individuals are indicated by the larger closed circles, matureindividuals by open circles, and those of unknown maturity by the smaller closed
circles. Dotted line indicates an individual where number of cementa! layers(circle at the right end) is used instead of dentinal layers (left end of dotted line).
Growth curves are drawn by eye.

E 160
u

.£ 140..c
Oi 120
c:

~ 105

~100

:,?-~·

~
07.

o••

0

'°
Body weight in kg
Fig. 8. Scatter plots of body weight vs. body length (the x and y axes are reversedin this graph). Closed circles indicate males and open circle females. For
further explanations see text.

Yt = 133.3 exp( -0.5611 exp( - l.2447t))

where Yt indicates the body length (cm) at age t years. Although this equationfits well to the male data, the analogous equation for females does not fit the data.
This may be due to the fact that the growth of females is more specialized, that
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

56

KASUYA AND BROWNELL

is, females grow at a faster rate for a longer period.
Postnatal growth in body weightThe sexual dimorphism of body length suggests the presence of sexual dimorphism of body weight in all the age classes above I year of age. However, theobserved difference of mean body weight is significant only in the age group fromI to 2 years and that above 4 years (p<0.05). This is because of the large individual variation of body weight and small sample size.

•

January0• Julyo December

14

0

Cl

c: 12

0

Ill
C1I

iii 10

-Cl.I

..c.
0

8

.0
0

6

---------------------------------- - ---

..c.

Cl

·~

~

.

------------------~

4
Oo •

2

0
0

~
0

0

0

.

•

o.

•
o •o

0 ~~~~~~~-'-~~....I..-~--'~~-'-~--'
80
90
100
110
120
130
140
Body length in cm
Fig. 9. Scatter plots of combined weight of both testes on body length. Horizontal
lines indicate the mean weight at the attainment of puberty or of sexual maturity
calculated in this study.

In Fig. 8, the body weights are plotted against the body length. No sexual
dimorphism is observed in the relationship. This is reasonably expected from thefact that there is no observed secondary sexual dimorphism in the external proportions of the species (Kasuya, 1974). The correlation seems to change at a bodylength 105 cm. The relationship of the body weight to body length is expressedby the following equations calculated by least squares,y = 3.459x 10- 2 -x 1•2993 ,y = 6.902x I0- 5 ·x2 •6347 ,

x;;;;IOS
x~I05

where y indicates body weight in kg and x indicates body length in cm.

A bodySci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPHIN

57

length of 105 cm corresponds, on the mean growth curve, to an age between 0.5
and 1.0 year, or probable weaning period as discussed below. If the growth of
the body in the longitudinal and transverse directions is the same, the coefficientmust be close to 3.0. However, it is much smaUer in this species. This indicatesthat the body of the species becomes slender with the increase of body length andthe tendency is more exaggerated during the suckling stage.

Weaning
The stomach contents of only four juveniles were studied. The smallest,male, 84.5 cm, 0.2 years of age, had milk in the stomach. Also present were numerous small unidentified discs of a diameter of about 0.3 mm. Although the originof these substances is unknown, they may have been derived from some solid
food. More than half of the teeth had erupted in this individual. Three otherjuveniles, 90.5 cm to 104.5 cm in body length and 0.3 to 1.1 years of age, had fish
otoliths, squid beaks or shrimps in their stomachs. The presence of milk was notnoted.

Ol

14

c

12

IJ)

QI
......

10....Cl>

-

8

0

6

.c.

4

QI

2

..
~

Ol

3=

••

•

IJ)

....

•

•
•

~

•

..
••

•

•
•

•

• •

•

,

.. ··'
••
0
•• •
•

0

2

I

4

6

8

16

Age in years
Fig. 10. Scatter plots of combined weight of both testes on age.
lines see Fig. 9.

For horizontal

These data suggest that the species starts to take solid food at about 3 months
after birth. The length of the suckling was not determind. The rapid increase of
the dentine thickness at a length of 100 to 105 cm, which corresponds to an ageof 0.5 to 1.0 year, possibly coincide with the period when the diet changes frommilk to solid food as suggested in Stenella attenuata by Kasuya, Miyazaki and Dawbin(1974).

Attainment of sexual maturity in male
Figure 9 shows the relationship between body length and combined weight
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

58

KASUYA AND BROWNELL

of both testes. The weight is below 2 g in juveniles, but shows a rapid increaseat a length of 120 to 130 cm, which will correspond with the approach of sexual
maturity. The present data on the testes weight are limited mainly to the monthsof January, July and December. The seasonal change of the testes weight was
examined between these three months. Since the mating peak of the species is
estimated to be in December to February (Harrison et al., Ms.) there is expecteda difference of the weight between the winter and summer months. However,as shown in Fig. 9, there is no observed seasonal change in the present materials.
This is probably because the sample contains so few adult animals. In case of
Stenella coeruleoalba, the seasonal change of testes weight is observed clearly only inadults (Miyazaki, 1977).
Figure 10 shows the relationship between age and weight of testes based on
13 males in December, 25 in January and one in February. The increase of theweight is rapid between 2 and 2.5 years of age.
TABLE 7.
Weight 1>
(g)
0-2
2-4
4-6
6-8
8-10
10-12
12-14
1l

SEXUAL MATURITY AND WEIGHT OF TESTES IN PONTOPORIA BLAINVILLEI
Immature

MaturePuberty

no.

%

no.

~~

no.

%

9
7
4

100.0
87.5
50.0
16.7
0.0
0.0
0.0

0
1
0
2
2
0
0

0.0
12.5
0.0

0
0
4
3
5
0
2

0.0
0.0
50.0
50.0
71.4

0
0
0

33.3
28.6
0.0
0.0

100.0

Total
no.
9
8
8
6
7
0
2

Lower limit included.

The determination of sexual maturity in males is less accurate than that infemales. In the present study it was done based on the histological examinationof testis. The epididymal development was used only for a reference. By examining all the available seminiferous tubules in a slide which is usually a crosssection of the entire testis, an individual was classified as mature if all tubules contained spermatids or spermatocytes, as immature if no tubules contained them, andas pubertal if some of the tubules contained them. The spermatid and spermatocyte are always observed together and often accompanied by spermatozoa,
but the presence of only spermatozoon was not observed. This criterion is similar
to that used for Phocoenoides by Kasuya (1978), and is not based on direct data if
the individual participate in the reproduction.
The development of the ductus epididymis seems to be completed before thatof the testis. This is indicated by the facts that the pubertal testis is usually accompanied by an epididymis with a fully developed ductus, and some immature testis
by an epididymis with a partially developed ductus.
The relationship between the combined weight of both testes and the maturity
is shown in Table 7. The largest immature testes appeared at the weight of 7.6 g
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPHIN

59

and the smallest mature at 4.6 g. Pubertal stage testes at a weighed between 3.1
and 8. 7 g. The least squares regression gives 5.1 g as the weight where thefrequency of" immature" individuals is 50%, and 6. 7 gas that where half of theindividuals are " mature ". The former value corresponds to the mean weight of
the testes when males reach the pubertal stage (see Fig. 9). In the following analyses of the growth of the male, the identification of maturity is based on the resultof the histological examination of the testis. Weight criteria were not used because
they did not improve the accuracy of the analyses.
TABLE 8.

AGE AND MATURITY IN PONTOPORIA BLAINVILLEI
FemaleAge(range)Male-·------- - - ----·---

--~-

1~,

<2
2~, <33~, <44~, <55~, <6Age(mean)

Im
no.

Pu
no.

M

M

no.

%

1.2
2.2
3.2
4.1
5.0

48
10
0

0
3
0
0
0

0
5
5
10
4

0.0
27.8
100.0
90.9
100.0

0

-·---

--------------~---

Age(mean)

Im
no.

1.2
2.1

12
4
0
0
0

4.0
5.0

Pu
no.

0
1
0

---·--

M
no.

M

0
3
0

0.0
37.5

2

%

50.0
100.0

Im: Immature, Pu: Pubertal, M: Mature.
TABLE 9.

BODY LENGTH AND MATURITY IN PONTOPORIA BLAINVILLEI
Male

FemaleBody length(cm)
115-119120-124125-129130-134
135-139140-144
145-149- --------------------- --

Im
no.

8
10
4
2
0

Pu
no.

0
0
2
0

M
no.

0
0
2
4
7

---··------------------

M
<}~

0.0
0.0
28.6
50.0
10\J. 0

Im
no.
2
5
2
4
I

0

Pu
no.

M
no.

M

0

0
4

0.0
44.4
25.0
50.0
60.0
87.5
50.Ll

1
3

5

6
7
2

%

Im: Immature, Pu : Pubertal, M: Mature.

Table 8 shows the relationship bet\veen age and maturity. The age of theoldest immature male is 2.1 years, and that of the youngest adult male 2.0 years.
The pubertals male appeared between the age of 1.2 and 4.0 years. These data,
gether with the principal uncertainty of the definition of sexual maturity of the male,
allow us to say with certainty only that the mean age of the male at the attainmentof sexual maturity is between 2 and 4 years. However, the scatter plot of testes
weight againt age shown in Fig. 10 strongly suggests that the males attain maturity
at an age between 2 and 3 years as in the case of the females.
Table 9 shows the relationship between body length and the growth stage.
If the unusually large immature male (RLB 835, 145 cm, 35. 7 kg, and 2.0 yearsof age) is excluded, body lengths of the smallest mature male and of the largest
immature are 121 cm and 137 cm, respectively. The pubertal males are foundSci. Rep. Whales Res. Inst.,
No. 31, 1979

KASUYA AND BROWNELL

60

between 118 cm and 145 cm. The least squares regression fitted for the data
in Table 9 gives 124.8 cm as the length where half of the individuals are immature.
The corresponding figure calculated for the ratio of mature males is 131.4 cm.
The former corresponds to the mean length at the onset of the pubertal stage definedin this study and the latter to that at the onset of the mature stage. Possibly
the mean length at the start of actual adult stage lies between the two values.
If the large immature male (RLB 835) is excluded, the weight of the heaviest
immature male is 24.5 kg and that of the lightest mature males 29.0 kg. One
pubertal male weighed 24.9 kg (Table 10). Accordingly, the weight of male atthe onset of sexual maturity is estimated to be between 25 and 29 kg.
TABLE 10.
Body weight(kg)

21.0-23.9
24.0-26.9
27.0-29.9
30.0-32.9
33.0-35.9
36.0-38.9
39.0;;;;;

BODY WEIGHT AND MATURITY IN PONTOPORIA BLAINVILLEI
FemaleMale--------- - - - - - - - - - - - - - - - - -----------------

Im

Pu

M

Im

Pu

M

3
2
0

0

0
0
2
2
0

5
6
6

0

0
0

0
l

0
0

0
0
0
0
0

0

l

l

0
0
0

0
0

l

0
0

0
2
2
2

Attainment ef sexual maturity in female
The sexual maturity of the female was determined by the presence of at least
one corpus luteum or albicans in the ovaries. Some immature females with developed Graafian follicles were considered as being at the pubertal stage. The
youngest mature female appeared at the age of 2.0 years and the oldest immature
at 4.0 years. The pubertal females ranged in an age between 2.1 and 2.8 years.
The mean age at the attainment of sexual maturity is calculated from the ratio ofadult females in each age group shown in Table 8. The least squares equation isexpressed as follows:y = 28.52x-26.39,

1 ~x~6

where x indicates the age in years and y the ratio of adult females in percentage.
The age where half of the females are sexually mature, or the mean age at theattainment of sexual maturity, is 2. 7 years.
The smallest mature and the largest immature female were 137 cm and 146
cm in length, respectively. The pubertal females were found between 136 cm and144 cm in body length. The least squares regression of the data in Table 9 gives
140.3 cm as the body length where half of the females are sexually mature. Thisvalue is significantly smaller than the approximate length of 14 7 cm read on themean growth curve corresponding to the mean age at the attainment of sexual
maturity. This difference is caused by the cessation of growth in body length soonafter the onset of sexual maturity.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPHIN

61

The body weight of the largest non-pubertal immature female was 30.8 kg(1.2 years of age), and pubertal females were found in the range between 29.0 kg(2 .4 years) and 33 .1 kg (2 .1 years). The smallest adult appeared at the bodyweight of 29.9 kg (4.0 years). All the females were sexually mature above theweight of 34 kg. Accordingly, it is expected that the female attains maturity at abody weight of 33 to 34 kg. The weight calculated for the mean body length at
the age at sexual maturity of 2. 7 years is about 35 kg, which is close to the above
figure.

Attainment of physical maturify
The fusion of vertebral epiphyses to the centrum was examined on a limited
number of individuals. The sexually immature individuals were, even if theepiphysis was not examined, reasonably considered in this study as physicallyimmature.
In the present sample only one male was physically mature. It was 132 cm
in body length and 16 years of age. The age of the oldest physically immature
males was 5 years, represented by two sexually mature males. Their body lengths
were 140 and 142 cm, respectively. Because of the scarcity of materials, it was
impossible to determine the difference of the age at physical maturity of males andthe corresponding value of females below.
The age of the oldest physically immature females was 4.0 years, and the age
range of five physically mature females was from 4.0 to 8.0 years. This indicates that females attain physical maturity at the age of about 4 years or about
1 year after the attainment of sexual maturity. The mean length of the femaleat the attainment of physical maturity will be very close to the asymptotic lengthof 153.0 cm estimated in the former section. The largest physically immature
female was 145 cm in body length, and the length of physically mature females
ranged from 148 to 171 cm.
DISCUSSION

Scott (1949) found in cetaceans the following linear relationship between the
maximum length of the adult, x in cm, and the neonatal length, y in cm:
y = 0.244lx+44.3(1)

Later, Ohsumi (1966) obtained for several species of odontocetes the following
allometric relationship between the mean length of female at the attainment ofsexual maturity, x in m, and neonatal length, y in m:
y = 0.532x 0•916(2)

If the asymptotic length of females 153.0 cm, and the mean length at the attainmentof sexual maturity, 147 cm, estimated in this study for P. blainvillei are put in theseequations, neonatal lengths of 81.6 cm and 72.6 cm are obtained from equations(1) and (2), respectively. The extraporation of the growth equation (page 55)
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

62

KASUYA AND BROWNELL

gives a neonatal length of 76.1 cm. These, figures, especially the second, are close
to the value estimaetd in the former section of this study.
The fetal growth rate al}d length of gestation can be deduced by the methodof Kasuya (1977) or of Perrin et al. (1977). When x indicates the neonatal lengthin cm and y the fetal growth rate in cm/day at the linear part of the growth curve,
the following equation was obtained from eight species of odontocetes (Kasuya,1977).
y = 0.001802x+0.1234

Accordingly, the length of time from the date when the extended straight feta!
growth line cuts the axis of time to the mean date of birth is calculated by x/(0.001802x+0.1234). If the neonatal lengths 81.6 cm and 72.6 cm are put inthe equation, the duration is calculated as 291 and 275 days, respectively. The
estimation of length of time from the start of gestation to the date when the extended linear growth line cuts the axis of time has some uncertainty. Hugget
and Widdas (1951) estimated for the growth curve indicated by the cube root of
the fetal weight that the length of time is 0.2 X (gestation time) for the gestation
over 400 days. Laws (1959) indicated that the value will be 90% of the value
estimated by Huggett and Widdas (1951), if the growth curve is based on thelength. After repeated calculations beginning with a gestation of 350 days (fordetails see Perrin, Coe and Zweifel, 1976), the values obtained for species P. blainvillei were 0.130 (for linear growth period of 291 days) or 0.139 (275 days). Thesefigures give a total gestation time of 334 days or 11.0 months (neonatal length of
81.6 cm) and 319 days or 10.5 months (neonatal length of 72.6 cm).
Perrin et al. (1977) found the following relationship between length of gestationin months (Y) and length at birth in cm (X).
LogY = 0.4586 LogX+0.1659

This equation and the neonatal lengths of 81.6 cm and 72.6 cm calculated above
give gestation lengths of 11.0 and 10.5 months respectively. Presumably the latter
figure, 10.5 months, will be closer to the true value. These estimates show a good
agreement with the range of 10.5 to 12 months obtained by Harrison et al. (Ms.).
Further improvement of the estimate will depend on a better calculation of theneonatal length.
The age at the attainment of sexual maturity, 2. 7 years, obtained for female
P. blainvillei is the lowest in any cetacean which has been studied. This may berelated to the small body size of the species. The only comparable species is Phocoena
phocoena, which in the western North Atlantic attains sexual maturity at the ageof 4 years (Gaskin and Blair, 1977). The same species in the North Sea is considered to attain maturity at 5 years in males and 6 years in females (Utrecht,1978).
The age frequency of the present materials is shown in Fig. 11, where only
the data of random collection are listed. A mode exists between 1 and 2 years.
The frequency of the calves below 1 year of age is only 13 individuals, and theSci. Rep. Whales Res. Inst.,
No. 31, 1979

63

FRANCISCANA DOLPHIN

!!20
<U
:J

u

.~10
-0

c

7
/

..... 5

\\

0

ci 3

\

z

2
1
0

/\\

2

4

\

/
b.- --o'68er- --016

1012

Age in years
Fig. 11. Age frequency of P. blainvillei. Closed circle and solid line indicate males,
and open circle and dotted line females. Only the random catch samples areincluded.

presence of bias in the sample is suggested. According to Harrison et al. (Ms.)
the parturition peak of the species is in the second half of November to the second
half of December (depending on the estimation of the mean neonatal length).
Since most of the present materials were obtained in December and January,
there should have been more newborn calves if the materials were not biased.
The number of pregnant females, namely the number of calves which would
have been born in the next year, is close to the number of calves below 1 yearof age. This is again an indication of the under representation of pregnant
females, and presumably that of other adult individuals of both sexes. This bias
may cause an error in the estimation of the mean age at the attainment of sexual
maturity, the mean growth curve after this age, and the maximum length of lifespan. However, since the correlation between age and sexual maturity is very
high in the present species, the bias in the estimation of the first two figures will
be slight. Samples bias related to the method of fishing is known in Stenella
coeruleoalba and Phocoenoides dalli (Kasuya, 1978).
Though catchability might be different between the sexes, the difference wasnegligible in the immature individuals. The ratio of females in the total of 148
individuals below 3 years of age is 50.0%. This is considered to be close to thereal sex ratio at the immature stage.
Among 27 adult females dealt with here, the reproductive stage is known in
15 individuals. They are seven pregnant, two pregnant and simultaneously
lactating, three lactating, and three resting females. The last category indicates
adult females neither pregnant nor lactating. The lactating or resting females arelimited to December and January, the parturition season of the species. The
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

64

KASUYA AND BROWNELL

data from other months are one pregnant in August, two in October, and two
in November. These data suggest that lactation usually lasts a short period, presumably not longer than eight or nine months. This figure is in good agreementwith the length of nursing:period estimated in the former section. Females which
weaned a calf before August or September will become pregnant in the next mating season in January. Accordingly we suspect that a two years cycle of breeding will be most frequent in this species.
ACKNOWLEDGMENTS

This study would not have been possible without the cooperation and assistanceof all the fishermen of Punta del Diablo and especially the Olivera family who
made our work in the village possible. Major financial support came from the
National Geographic Society, Office of Naval Research, National Science Foundation (grant number GF-42389), Ministry of Education, and Japanese Society for the
Promotion of Science. The following individuals helped in various ways during thisstudy: M.A. Klappenback, J. G. Mead, A. Mones, M. Nishiwaki, R. Praderi, S.
Toscano, and A. Ximenez. T. Kamiya, K. Numachi, and F. Yamasaki helped
us collect specimens in Punta del Diablo. M. Oya and S. Wada assisted withmany phases of the data handling and processing. We thank all these persons
for their help.
REFERENCESBROWNELL, R. L. JR. and R. NESS, 1970. Preliminary notes on the biology of the Franciscana, Pontoporia
blainvillei (Cetacea, Platanistidae). pp. 23-28. Jn: Proc. Sixth Annu. Conf. Biol. Sonar and Diving
Mammals, Stanford Res. Inst., Menlo Park, Calif.
BROWNELL, R. L. JR., 1975. Progress report on the biology of the Franciscana dolphin, Pontoporia blainvillei,
in Uruguayan waters. J. Fish. Res. Bd. Canada, 32 (7): 1073-1078.
GASKIN, D. E. and B. A. BLAIR, 1977. Age determination of harbour porpoise. Phocoena phocoena (L), in
the western North Atlantic. Can. J. Zoo!., 55: 18-30.
HARRISON, R.J., M. M. BRYDEN, D. A. McBREARTY, and R. L. BROWNELL, JR., (Ms). The ovaries and reproduction in Pontoporia blainvillei (Cetacea, Platanistidae).
HuGGET, A. ST. G. and W. F. WmnAS, 1951. The relationship between. mammalian foetal weight andconception age. J. Plrysiol. 114: 306-31 7.
KASUYA, T., 1973. Freshwater dolphins and their biology. Dobutsu to Shizen (Tokyo), 3 (12): 4--8. (InJapanese)
KASUYA, T., 1974. Morphology and growth of Franciscana dolphin pp. 12-24. In: Report of Scientific
Expedition of La Plata and Amazonian Dolphins, Univ. Tokyo Freshwater Dolphin Expedition, Tokyo
93 pp. (In Japanese)
KASUYA, T., 1977. Age determination and growth of the Baird's beaked whale with a comment on the feta!
growth rate. Sci. Rep Whales Res. Inst., 29: 1-20.
KASUYA, T., 1978. The life history of Dall's porpoise with special reference to the stock off the Pacific coastof Japan. Sci. Rep. Whales Res. Inst., 30: 1-63.
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.
LAws, R. M., 1959. The foetal growth rates of whales with special reference to the fin whale, Balaenoptera
physalus Linn. Discovery Rep., 29: 281-307.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

FRANCISCANA DOLPH!.:\"

65

MIYAZAKI, N., 1977. Growth and reproduction of Stenella coeruleoalba off the Pacific coast of Japan. Sci.
Rep. Whales Res. Inst., 29: 21-48.
0HsUMI, S., 1966. Allomorphosis between body length at sexual maturity and body length at birth in the
Cetacea. ]. Mamm. Soc. Japan, 3 (1): 3-7.
PERRIN, W. F., J.M. CoE, and J. R. Zweifel, 1976. Growth and reproduction of the spotted porpoise,
Stenella attenuata, in the offshore eastern tropical Pacific. Fish. Bull. 74 (2): 229-269.
PERRIN, W. F., D. B. Holts, and R. B. Miller, 1977. Growth and reproduction of the eastern spinner dolphin,a geographical form of Stenella longirostris in the eastern tropical Pacific. Fish. Bull. 75 (4): 725-750.
PILLER!, G., 1971. On the La Plata dolphin Pontoporia blainvillei off the Uruguayan coasts. Investigations on
Cetacea (Berne), 3 (1): 59-68.
SCOTT, E.O.G., 1949. Neonatal length as a linear function of adult length. Pap. & Proc. Roy. Soc. Tasmania,
1948: 75-93.
UTRECHT, W. L. VAN., 1978. Age and growth in Phocoena phocoena Linnaeus, 1758 (Cetacea, Odontoceti)
from the North Sea. Bijdragen Tot de Dierkunde., 48 (1): 16-28.
VAN ERP, I., 1969. In quest of the La Plata dolphin. Pac. Discovery, 22 (2): 18-24.
XIMENEZ, A., A. LANGGUTH, and R. PRADER!, 1972. Lista sistematica de los mamiferos de! Uruguay.
Anal. Mus. Nacional Hist. Nat. Montevideo, Ser. 2, Vol. 7: 1-49.
ZWEIFEL, J. R. and W. F. PERRIN, in press. Fitting curves to odontoceti length tooth layer data. In:
Proc. Int. Conf. Age Determ. Odont. Cetaceans and Sirenians. Rep. Int. Whal. Comm. Spee. Issue.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

66

KASUYA AND BROWNELL

EXPLANATION OF PLATESPLATE I
Fig. I. Immature testis. RLB809, body length 111 cm, weight of testes I. 7 g, age
2.0 years. 19 Dec. 1972. Scale indicates 0.1 mm.
Fig. 2. Pubertal testis. RLB821, body length 130 cm, weight of testes 3.1 g, age
2.2 years. 24 Dec. 1972. Same magnification with Fig. I.
Fig. 3. Mature testis. AOl972-4, body length 124 cm, weight of testes 5.8 g.
29 July 1972. Same magnification with Fig. I.
Fig. 4. Mature epididymis. A01972-4. Same magnification with Fig. I.
PLATE II
Decalified and stained thin _sections of teeth. Scale indicates 2 mm, all figures insame magnification. C, cementum. Open circle, neonatal line in dentine.
Fig. I. RLB600, 0.2 dentinal layers, 84 cm male, 14 Jan. 1971. Immature.
Fig. 2. RLB861, 0.4 dentinal layers, 103 cm female, 4 Jan. 1973. Immature.
Fig. 3. RLB648, 1.5 dentinal layers and 1.8 cementa! layers, 105 cm female, 27Jan. 1971. Immature.
Fig. 4. RLB698, 2.5 dentinal layers and 2.3 cementa! layers, 120 cm male, 18
March 1971.
PLATE III
Decalcified and stained thin sections of teeth. Scale indicates 2 mm, all the figuresin same magnification. C, cementum. Open circle, neonatal line in dentine.
Fig. I. A01971-54, 4.0 dentinal layers and 4.5 cementa! layers, 157 cm female,
24 Dec. 1971.
Fig. 2. A01971-57, 6 dentinal layers and 8 cementa! layers, 153 cm female, 30
Dec. 1971. Sexually mature.
Fig. 3. RLB592, 7 dentinal layers and 13 cementa! layers, 144 cm female, 14 Jan.
1971. Sexually mature.
PLATE IV
Fig. I. Decalcified and stained thin section of a tooth. RLB577, 6 dentinal layers
and 7 cementa! layers, 125 cm male, 5 Jan. 1971. Sexually mature. Scale indicates 2 mm. For other marks see Plate III.
Fig. 2. Decalcified and stained preparation of partially masked tooth. Left half,
undecalcified thin section; right half decalcified and stained part. RLB878,
133 cm male, 16 Jan. 1972. Immature. Scale indicates 1 mm. Photographed
under transmitted light. For marks see Fig. 1.
PLATE V
Comparison of annual layers in dentine and cementum Scale indicates 0.5 mm, allfigures in same magnification. Bar, boundary of prenatal and postnatal dentine.
C, cementum. Closed circle, annual growth layers.
Fig. 1. RLB600. Same tooth with Plate II, Fig. I.
Fig. 2: RLB861. Same tooth with Plate II, Fig. 2.
Fig. 3. RLB648. Same tooth with Plate II, Fig. 3.
Fig. 4. RLB698. Same tooth with Plate II, Fig. 4.
PLATE VI
For explanations see Plate V.
Fig. I. A01971-54. Same tooth with Plate III, Fig. I.

Deposition of osteodenSci. Rep. Whales Res. Inst.,
No. 31, 1979

67

FRANCISCA.NA DOLPHIN
tine started.
Fig. 2. AOl971-57. Same tooth with Plate III, Fig. 2.
most of pulp cavity leaving narrow canals.

Osteodentine nearly fills

PLATE VIIFor explanations see Plate V.
Fig. I. RLB592. Same tooth with Plate III, Fig. 3. Deposition of osteodentine
started on some part of pulp wall.
Fig. 2. RLB577. Same tooth with Plate VI, Fig. I. Central part of pulp cavity
is almost filled by osteodentine.

Sci. Rep. Whales Res. Inst.
No. 31, 1971

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IN SOUTHEAST ALASKACHARLES M. JURASZ AND VIRGINIA P. JURASZ
Sea Search, Ltd., Alaska.

ABSTRACT

Three methods of feeding by humpback whales (iVfegaptera novaeangliae)
are described based upon twelve years and over 15,000 hours of observation
in Southeast Alaska. " Lunge feeding " is a method used by a single whale
or by a group in unison. The whales emerge abruptly through the water's
surface, mouth open, as they engulf euphausiids (Euphausia pacifica ), herring(Clupea harengus) or capelin (Mallotus villosus ). Lunge feeding includes threebasic variations: "lateral lunge feeding", "vertical lunge feeding", and" inverted lunge feeding "; the adjective refers to the angle of the sagittal
plane of the whale to that of the water's surface. Sometimes during lunge
feeding a sound described as " castanetting " is produced when the whale's
mandibles repeatedly strike the rostral margins producing in air a soundanalogous to that of a castanet. "Bubblenet feeding" involves a releaseof a discrete sequence of bubbles underwater that form a ring or closing
spiral at the water's surface. Within the ring or " net", the target feed isconcentrated and contained as the whale emerges, mouth open within thering. Sequences of sounds have been heard only when two whales fed cooperatively using a bubblenet to capture herring. In "flick feeding", awhale lashes its tail forward at the water's surface, concentrating euphausiids,
then rapidly dives forward into the feed, mouth open. It has been concluded
that feeding methods used by humpback whales vary depending on the kindand quantity of feed available.
INTRODUCTION

Although the foods of the humpback whale (Megaptera novaeangliae) have become
well-known through the examination of carcasses at whaling stations and stranded
specimens (Mathews, 1937; Lillie, 1915; Nemoto, 1970), few observations havebeen made and recorded of the actual feeding behavior of living whales. It has
sometimes been suspected that observed whales were feeding, but direct evidenceof feed was not found (Perkins and Whitehead, 1977; Schevill and Backus, 1959).
One of the few references to feeding behavior prior to the present study of
humpbacks in Alaskan waters was given by Andr. Ingebrigtsen (1929). He described two methods; one in which a humpback swam around in a circle lashing
the sea into a foam with its flukes, then diving below the frightened krill only toappear a moment later in their midst with its mouth open. In the second method,
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 69-83

70

M. JURASZ AND P. JURASZ

the humpback whale appeared to dive a short distance below the water's surface
and then released air while swimming in a circle. The rising bubbles rose to thesurface like a thick wall of air bubbles, and these formed a net.
The present study began in 1966 with observations on feeding humpback
whales near Juneau, Alaska and was expanded to adjacent areas of Southeast
Alaska over the next twelve years (Fig. 1). We have found that Alaskan humpback whales have a varied diet and employ three basic feeding modes with several
vanat10ns. Data documenting these feeding modes were gathered during morethan 15,000 hours of observation.
DESCRIPTION OF THE STUDY AREA
Southeast Alaska, currently the summer home for approximately 60 humpback
whales is characterized by an intricate system of protected bays and inlets withnumerous small islands (Fig. 1 ). The areas under observation include Glacier Bay,
Lynn Canal and Frederick Sound. Air temperatures in summer (June-September)average l4°C with a range from 5°C to 27°C; surface water temperatures range
from 5°C to l 4.4°C. Fresh water runoff from rivers, and melting snow and ice
creates variable surface salinities, ranging from l%o to 25.9%0 in 1977 and 1978.
During the summer daylight lasts for 18 to 20 hours.
Little hydrographic data are available, but the latest charts by the National
Ocean Survey and the U.S. Coast Guard indicate depths to approximately 160
meters. Average tidal amplitude is 2 to 3 meters with a maximum of 8 meters.
METHODS
A 3-meter fiberglass skiff powered by a 20 hp outboard was used as an observation
platform for the first five years, 1966-1971. Since 1971, the 15-meter Rf V GinJur,
a wooden-hulled diesel-motored vessel equipped with silencers, has served as theresearch platform and laboratory for from four to ten observers. Observation
distances are commonly 20-meters and sometimes as little as 4-meters. Observations often extend over the full 18 to 20 hours of daylight.
Visually, whales were sighted and approached. Most whales were identified
individually by the color pattern of the underside of the flukes in addition to otherbody characteristics. The whales were tracked visually and their behavior
recorded. A battery-operated stop watch was employed to time submergenceintervals of whales and to insure that noted behavior is recorded in sequence.
Feeding environs, behavior and temporal aspects of the sequences were recorded
and photographed. These still photographs aided in the analysis of sequencesof events during feeding activities.
The bubblenet has been recorded underwater for further analysis by Dr P. 0.
Thompson of the Naval Ocean Systems Center, Dr Roger Payne of the New York
Zoological Institute and Dr Sylvia Earle of the California Academy of Science.
When whales were feeding, the target feed was photographed within the gape
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

HUMPBACK FEEDING MODE71

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of the whale's open mouth. Collections of food species were made with plankton
tows and fish trawls to verify the species. Samples were submitted to National
Marine Fisheries Service, Auke Bay, Alaska, and to the NMFS Laboratory at
Tibinon, California for identification. Voucher specimens have been depositedat the California Academy of Science, San Francisco, California.
Feed in Southeast Alaskan waters appears for the most part to consist of euphausiids (Euphausia pacifica), herring (Clupea harengus), or capelin (Mallotus villosus).
DISCUSSION
The main structures involved in the feeding of the humpback whale according toSci. Rep. Whales Res. Inst.,.No. 31, 1979

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Nemoto (1970) are the baleen plates, the mouth opening, the tongue and theventral grooves in the throat and abdomen. To feed the humpback whale takes
water and feed in through its mouth causing the pleated throat to swell and expand(Fig. 2). The mouth is closed and water is compressed out of the mouth (Fig. 3).
The retained feed is then swallowed. Humpback whales are in the "swallower"or "gulper" catagory rather than the "skimmer" catagory (Nemoto, 1970).
In addition, we have observed humpback whales occasionally using bothflippers and flukes in feeding. The flipper is thrust toward the open mouth ina scooping fashion. The flukes are employed in one particular mode called,"flick feeding", that will be discussed later in the text.
Humpback whales employ three different modes of feeding, depending on
the species and the density of the feed. The modes are identified here as discrete
activities that may vary in terms of body positions or angles of attack.

Lunge Feeding
One of the most commonly witnessed modes is designated as lunge feeding.
This mode occurs when the feed is abundant. We have observed lunge feedingon euphausiids (Euphausia pacifica), herring (Clupea harengus), capelin (Mallotus
villosus), and mixed schools of the latter two species.
In lunge feeding, the humpback swims vertically at approximately 5-knots
through an aggregation of feed, opens its mouth in the upper 3-meters of waterand engulfs the feed. The humpback's body is nearly vertical when its mouth isopen to receive the food (Fig. 4). During this type offeeding, other species offeed
may be incidentally ingested. There were many instances when walleye pollock( Theragra chalcogramma) were seen swimming leisurely at the surface feeding on
krill. In some cases, the pollock were dispersed at the surface and in other cases
they were schooled. When a whale is lunge feeding, it sometimes engulfs thesepollock along with the krill. Since the mass of euphausiids seen within the mouthof the whale is far greater than the mass of pollock, the euphausiids appear to be
the target feed.
When lunge feeding is employed by the humpback at a frequent rate, e.g.,
12 lunges per hour, the results include an audible in-air characteristic occurring
as a soft " clap ". The sound is produces by the rostral margin and the mandibularmargins striking one another with the cupped effect of the partially filled auralcavity producing a resonance similar to that produced by a castanet, hence wehave referred to it as " castanetting ". Castanetting is associated with those feeding
procedures which, as in lunge feeding may have a significant amount of verticalmotion, i.e., enough to bring the entire labial surfaces above water at the momentof rapid closure.
Other than vertical lunge feeding, there are two other variations in lunge
feeding: lateral lunge feeding and inverted lunge feeding (Fig. 5 ). The adjectives
refer to the angle of the sagittal plane of the whale to the plane of the water's
surface. The position used appears to relate to the efficient use of body motion
at the instant at which the feed is encountered and dense enough to engulf. The
Sci. Rep. Whales Res. Inst.,
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complished as a cooperative effort, another factor which has direct bearing on thewhales' speed is the motility of the feed. The whale must swim faster to catch
faster feed. Euphausiids are the slowest; herring are the fastest. The frequencyof lunges is related not only to the species of feed, but also the abundance anddistribution of feed. Hence with any given feed the frequency with which lunge
feeding is applied to that species is consistent with the increased or decreased levelsof availability of that feed.
During the seasonal transitions of feed caution must be exercised to scrutinize
the feed involved in each case. In late September to October, although euphausiids
are the most common feed taken at the surface, herring are occasionally present.
Subtle differences in the feeding behavior were found to be an indicator of a change
in conditions. Lunge feeding may have value as an indicator of local feed level
rather than as an indicator of the seasonal population fluctuation of a single
feed species.
On 20 April 1974, sixteen instances of lunge feeding were observed involving a single whale during one hour. The target feed was herring and thelocation, the western side of Douglas Island (seven miles from Juneau, 58°13'N
134°30'W) had until recent years supported both a healthy stock of herring andat least six whales during the summer months. In contrast, twenty-eight feeding
lunges were observed during 10 minutes on 13 August 1976, in Glacier Bay witheuphausiids as the target feed.

Bubblenet Feeding
A feeding procedure having a high degree of sequencial continuity has beencalled " bubblenet feeding" because of the strong physical resemblance to thedeployment and effect of a seining net. The major differences lie in the whale's
advantages of being able to blow a new net each time, to deploy the net frombelow rather than above, and to have its digestive apparatus at the base of thepurse. In sequence, the whale apparently locates a body of feed, dives below thefeed, and discharges a line of bubbles from its blowhole while swimming in a broadarc which has both vertical and horizontal components. The whale, outswimming
the feed, deploys the bubbles while sweeping both ahead of the feed and towards
the surface. The feed is blocked from below by the whale's body, laterally by therising bubbles, and ultimately above by the surface. The feed is thus contained
and since it is driven to the surface, it is condensed, by the same action. Whenthe feed is herring, there is a frenzy of fish visibly boiling to the water's surface
only within the confines of the blown net. The sequence of surface phenomena is
as follows: The bubbles appear as discrete cantaloup-sized spheres rising to thewater's surface (Fig. 8). This trail of bubbles forms a large ring or, in some cases,
closing spiral that remains visible as smaller, later occurring pea-sized bubbles
rise (Fig. 9). As the ring nears completion, the feed can be seen within the diameter of the thickening ring of bubbles. When the feed is herring, the fish flip
about on the surface within the ring. If the feed is euphausiids, a blush or roughingof the water's surface occurs within the ring, as the feed leaps into the air. At theSci. Rep. Whales Res. Inst.,
No. 31, 1979

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80

M. JURASZ AND P. JURASZ

been seen and heard via underwater acoustic gear during daylight hours. In
areas where whales were seen using the bubblenet during the day, recordings weremade throughout the hours of darkness but no bubbling sounds were heard. No
observations have been made of the humpback whale feeding after dark.
Bubblenets were observed on 13 July 1974, from 1205 thru 1725 hours ADT
at the southern tip of Shelter Island, near Juneau, Alaska. Two adult humpback
whales feeding in 16 to 40 meters of water, produced bubbles beneath the surfaceof the water. The pattern of the bubbles formed a counter-clockwise circle ofapproximately 30 meters in diameter and required 55 seconds from the time atwhich the first bubbles were seen on the surface to the last bubbles of the circle.
As the circle of bubbles closed, herring appeared at the surface within the circle
in a " boil ". The sound produced by the herring at the surface resembled heavy
rain on the water. Within approximately three seconds, two humpbacks appearedat the surface on their sides, mouths agape, with their blow holes oriented towards
the center of the circle. The angle of the humpback's jaw rostrum to mandible
during the feeding procedure frequently reached 90° and the herring could beseen flipping in the water engulfed by the cavernous mouths. The end of theactivity was marked by the humpback whales righting themselves, blowing anddiving only to repeat the activity within the next five to seven minutes at a distance, usually less than 100 meters, from the previous net. The two whales blew
25 bubblenets in the five hours they were observed. The whales continued to blow
bubblenets and feed through the tide change at 1437 hours ADT.
During this incident the two whales were heard " singing" as the bubblenet
was blown. The song began with a discernable buzzing pattern. As the final
bubbles approached the surface, the song changed to a staccato of higher pitchedsounds and a pause of a second or two could be noted prior to the herring's appearance at the surface within the net. This feeding song has been heard several
times but only association with more than one whale feeding and when the feed
was herring. The song pattern appears to be uniform.
One of the first bubblenets seen in connection with euphausiids was on 21
August 1975, at 1300 hours ADT. A single whale was observed for forty fiveminutes during which time four bubblenets were seen. The whale was bubblenet
feeding midchannel, 4.0 km northeast of Five Finger Light in Frederick Sound.
Euphausiids could be seen as a blush or cloud in the water.
The bubblenet when used for euphausiids can be as small as l t meters acrossand is of smaller diameter than that used for herring which is usually around50 meters. From the first bubble to the sight of the whale within the net the timefor euphausiids ranges from ten to forty seconds as opposed to 50 seconds to l
minute 10 seconds for herring.
Flick Feeding

Flick feeding was first observed in Glacier Bay in 1977. In flick feeding, thehumpback whale begans a normal dive raising its flukes well above the surface of
the water. When the tail has submerged to the base of the flukes, the tail is flicked
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

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82

M. JURASZ AND P. JURASZ

forward producing a splash and an internal wave. As the wave moves forward,
the mouth of the whale appears at the surface admidst the wave (Fig. 11 ). The
whole procedure occurs in approximately three seconds and follows this sequence:
dive, flick, lunge.
Plankton tows have not yet been attempted during the procedure because of
the short duration in the feeding mode, but it appears as if it could be a concentrating technique or it could be employed when the target feed is close to the surface
and entails a very shallow dive causing the flukes to splash.
This mode of feeding has been observed only in Glacier Bay and only when
the feed was euphausiids. Flick feeding has been intermixed with the other modesof feeding, i.e., bubblenet and lunge feeding.
CONCLUSION

Humpback whales employ a variety of feeding modes which appear to relate to
the target feed and its density. All of the feeding modes have been observed intermixed and employed by one whale feeding in one location during one observation,e.g., on 28 July 1976, one humpback feeding on euphausiids employed; verticallunge, lateral lunge, vertical lunge, bubblenet, vertical lunge, during the courseof one hour. Similarily, on 2 August 1978, another humpback feeding on
euphausiids employed; bubblenet, bubblenet, lateral lunge, vertical lunge, lateral
lunge, vertical lunge, vertical lunge, bubblenet, bubblenet, vertical lunge, lateral
lunge, flick feed within a twenty minute period. The total feeding time during
this observation was two hours.
All of the feeding modes may be used by single humpback whales or bygroups. Feed species and abundance varies with location and time of year. Feeding has been seen as early as April and as late as November. Heaviest feeding inSoutheast Alaska appears to take place in July and August.
ACKNOWLEDGMENTS

We acknowledge both National Park Service and National Fisheries Service,Northwest and Alaska Fisheries, Marine Mammal Division who funded andfacilitated this study.
We thank Dr Micheal Tillman, Dale Rice, Allan Wolman, Dr Frederick
Dean and Dr Sylvia Earle for reviewing this article.
REFERENCES
BATES, D. W. and]. G. van DERWALDER, 1964. Exploratory experiments on the deflection of juvenile salmon
by means of water and air jets. Fish-Pass. Res. Prog. U.S. Bur. Comm. Fish.
INGEBRIGTSEN, A., 1929. Whales caught in the north Atlanticand ot her seas. Repp. Exp/or. Mer. LVI(27): 1-26.
LILLIE, D. G., 1910. Cetacea. British Antaritic (Terra Nova) expedition 1910. Nat. Hist. Rep. :(ool.,
1(3): 85-124.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

HUMPBACK FEEDING MODE

83

MATTHEWS, L. H., 1937. The humpback whale (Megaptera nodosa). Discovery Rep., 17: 7-92.
NEMOTO, T., 1970. Feeding pattern of baleen whales in the ocean, pp. 241-252. In:]. H. Steeles (ed.)
Marine Food Chains, Oliver and Boyd, Edinburgh, pp. 552.
PERKINS, J. and H. V\'mTEHEAD, 1977. Observations on three species of baleen whales off northern Newfoundland and adjacent waters. ]. Fish. Res. Board Can., 34 (9): 1436-1440.
ScHEVILL, W. E. and R.H. BACKUS, 1959. Daily patrol of Megaptera. ]. Mamm., 41 (2): 279-281.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

A SKULL OF BALEEN WHALE DREDGED FROM
THE INLAND SEA OF JAPANHIDEO OMURA
Whales Research Institute, TokyoANDTOSHIO KASUYA
Ocean Research Institute, University ef Tokyo, Tokyo
ABSTRACT

A half-broken skull was dredged by a fishing vessel in the Inland Sea ofJapan in August 1978. This skull was studied from the taxonomic standpoint
and was thought to be a skull of the Bryde's whale, Balaenoptera edeni.
INTRODUCTION

It was reported in a local press in Oita Prefecture dated 27 August 1978 a big boneof unknown animal was dredged by a small fishing vessel while the operation ofbottom drag net for shrimps and other bottom fish. The bone was so heavy thatthe fishermen could not haul it on to the deck they ceased fishing operation andbrought back the bone, hanging it outside the boat, to the fishing port of Kizuki
City (Fig. 1).
The bone was eventually brought to Kizuki-shiritsu Minzoku Shiryokan(Kizuki Municipal Folklore Museum) for preservation and identification of theanimal species. At first they consulted with Oita Marine Palace, a nearby aquarium and was told that the bone may be a skull of a w.hale and examination by
specialist is needed. Then they took photographs of the bone from various angles
and sent them to Dr Teruo Tobayama of the Kamogawa Sea World for identification of the species, who in turn passed them to the Whales Research Institute.
From the photograph we understood that the bone is half-broken skull ofa baleen whale, but identification of the species is very difficult without close
observation of the bone. And this is our great concern in the light of rather poor
scientific knowledge of whales hitherto obtained from the Inland Sea, though
there is a good reason to think that a number of whales came into the Inland Sea
and out annually until about less than one hundred years ago (Shindo, 1975;
Omura, 1974). Thus we made a trip to Kizuki City, Oita Prefecture, towards
the beginning of October 1978.
OBSERVATIONThe skull is completely lacking the maxillaries and premaxillaries.
Sci. Rep. Whales Res. Inst.,

No. 31, 1979, 85-92

Possibly thisOMURA AND KASUYA

86

is caused by loose articulation of bones in the facial region of the skull of the baleen
whales, contrary to the toothed whales. Fortunately the vomer is remaining(Pl. I, Figs 1, 2 and 3). Its upper margin and anterior tip are broken to someextent, but presumably only a few centimeters, and thus protruding forward greatly
and giving an impression of a flat rostrum in profile. Nasals are completely
lacking (Pl. I, Fig. 1). On the inferior side of the vomer there still attached thepalatines, to which pterygoids are also attached, but their posterior ends or hamularprocesses are broken (Pl. I, Fig. 2).
130°E

SEA OF JAPANz

0

PACIFIC OCEANz
Fig. I. Chart showing the position where the Kizuki specimen was dredged bya fishing vessel. Marked with a cross.

The brain case of the skull is rather in a good condition. The supraoccipitalbone has a broken hole just above the occipital condyles, and its outer margins
especially of superior regions are broken to some extent, but still it shows a characteristic feature of the balaenopterid whales, being roughly triangle in posteriorview and the surface being relatively flat and having no deep concavity (Pl. I,
Fig. 1 and Pl. II). Exo- and basi- occipitals are nearly complete. Temporals
are in good condition, except extreme end of the right zygomatic process whichis broken slightly. Orbital processes of the frontals are also in good condition,
especially in posterior portion and orbits, but the anterior portions are broken.
Parietals are also remaining on the lateral sides of the brain case and extend forSci. Rep. ~Whales Res. Inst.,
No. 31, 1979SKULL OF BALEEN WHALE
TABLE I.

87

MEASUREMENTS OF SKULL, KIZUKI SPECIMEN
Measurements:

Lengthin mm% ofbreadthGreatest breadth of skull at zygomatic process
Breadth of skull at orbital process of frontal, posterior
centerBreadth of skull at mastoid process of temporal
Length of orbit, right*, leftLength of vomer, from broken tip*
Length of palatine, greatest, right, left, along median line
Length of skull from broken tip of vomer to occipital condyle*
Breadth of occipital condyle
Height of occipital condyle, right, leftBreadth of foramen magnum
HeightHeight of supraoccipital bone from foramen magnum
Breadth of supraoccipital bone
Vertical height of skull from vertex to vomer
Horizontal length from vertex to occipital condyle

1,287
1,264
1, 181986
195
210
2, 125
582
583
559
2,560
259
160
166
85
96
623
871
431
668

100.0

98.2
91.8
76.6
15.2
16.3
165.1
45.2
45.3
43.4
198.9
20.1
12.4
12.9
6.6
7.5
48.4
67.7
33.5
51.9

* Least value due to breakage.
TABLE 2.

COMPARISON OF THE KIZUKI SPECIMEN TO BRYDE'S,
SEI AND MINKE WHALES
Kizuki specimen

l\1easurements

Lengthmm%

1l

Cited from Omura, 1959.

2)

Lengthmm%~45 ft(13.5m)
3,480 215.5
439
27.2

Sex and body length
Condylo-premaxillary length
Tip of premax. to anterior end ofvomerGreatest breadth of skull
Breadth of skull at orbit (center)
Breadth of occipital condyle
Height of occipital condyle
Breadth of foramen magnum
Height of foramen magnum
Height of supraoccipital bone fromforamen magnum
Length of orbit

Bryde's 1'

Sei 1lLengthmm

Minke 2l%

Length
mm

%

~9.8m

~43ft

(12.9m)
3,060 229.4

2,350
290

187.1
23.1
100
97. I
18.2
11.4
6.3
10.1
51.8
16.5

1,287
1,181
259
163
85
96
623

100
91.8
20. l
12.7
6.6
7.5
48.4

1,615

100

1,335

100

266
174
53
45
835

16.5
10.8
3.3
2.8
51. 7

251
167
84
97
768

18.8
12.5
6.3
7.3
57.5

1,256
1,219
228
143
79
127
650

210

16.3

234

14.5

233

17.5

207

Cited from Omura, 1975.

ward beyond the line of the vertex.
We made some measurements of the skull. The greatest breadth of theskull at zygomatic processes of the squamosals, and other measurements concerning
breadth of the skull are fairly accurate. Results of the measurements are shown
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

88

OMURA AND KASUYAin Table 1 and these measurements are compared with corresponding measurements of the Bryde's, sei and minke whales in Table 2.

DISCUSSION

In profile the skull of the Kizuki specimen is very fiat (Pl. I, Fig. 3). Although it
lacks maxillaries and premaxillaries the vomer is remaining in almost all its length,
and we can safely assume that the ventral border of the vomer represents that of
the rostrum itself. From this fact and combined with other evidence we candeny the possibility of the specimen of being Balaenidae as well as Eschrichtiidae.
In Balaenidae the rostrum is curved downwards greatly and roughly Tee shapedin dorsal aspect of the skull, but the Kizuki specimen shows no resemblance of
these character. In Eschrichtiidae the rostrum is curved downwards in less extent
than Balaenidae but more curved than in Balaenopteridae. Further in Eschrichtiidae the supraoccipital bone presents three deep concavities, and on the superior
portion two prominent and peculiar rugosities, and also present similar rugosities
upon the basisphenoid and basioccipital bones (Andrews, 1914), but the Kizuki
specimen has neither such clear concavity nor rugosity. Thus it is clear that the
Kizuki specimen belongs to a species of the family Balaenopteridae.
Among the family Balaenopteridae there are two genera of Megaptera (onespecies) and Balaenoptera (five species). We can erase the posibility of the humpback whale, Megaptera novaeangliae, because of its slender shape of the Kizuki
specimen. The skull of the humpback whale is robust and it has maximum relative zygomatic width in the family Balaenopteridae, or 57-66.9% of the condylopremaxillary length (Tomilin, 1967). In the Kizuki specimen the ratio is lessthan l,287/2,560x 100=50.3 (see Table 1). The skull length of 2.56 m is thelength from the broken tip of the vomer to the occipital condyles. Probably wecan add to this figure some 30-40 cm as the length from the tip of premaxillary
to the broken end of the vomer (see Table 2), which makes condylo-premaxillary
length to be 2.90-3.00 m, resulting the ratio as small as 43-44%. From this fact
alone the possibility of the humpback whale will be erased.
We can safely conclude, therefore, that the Kizuki specimen belongs to a
species of the genus Balaenoptera, and there remains five species to be considered.
First of all we can exclude the possibility of the minke whale, B. acutorostrata, because of the size of the skull. The condylo-premaxillary length of the minke whale
usually does not exceed 2 m (Tomilin, 1967) and the largest skull ever recorded,
2.35 m in length, was obtained from a 9.8 m female in the Antarctic (Omura,1975). The minimum estimate of the skull length of the Kizuki specimen is 2.56 m(Table 1), but the actual condylo-premaxillary length would have been 2.903.00 m as already stated.
The inferior aspect of the skull of the Kizuki specimen denotes two special
features important for the identification of the species (Pl. I, Fig. 2). One is theshape of the palatines. In the Kizuki specimen the mesial border of anterior partSci. R.ep. Whales R.es. Inst.,
No. 31, 1979SKULL OF BALEEN WHALE

89

of the palatines situate near the inferior edge of the vomer and in parallel with theskull axis, but in the posterior portion they diverge outwards and the inner edges
do not articulate to the inferior edge of the vomer. In the Kizuki specimen theright palatine was broken at its posterior portion along the edge, but in the leftpalatine the posterior edge is nearly complete, except a semi-round broken holejust anterior to the curved posterior edge. Such a shape of the palatine is usual
in all the Balaenoptera species except the blue whale, B. musculus. The skull of theblue whale differs from those of other Balaenoptera in the shape of palatines which
terminate abruptly, without forming left and right processes. Such form of thepalatines is observed also in the pygmy blue whale, B. musculus brevicauda (Omura
et al., 1970). In this feature this species is similar to the humpback whale (Tomilin,1967). From the above it is clear that the Kizuki specimen is not a blue whale.
Another feature of importance is the shape of the vomer at its posterior end.
Tomilin (1967) shows that the posterior end of the vomer is greatly expanded in
the adult fin whale, B. physalus, differing from the sei whale (Fig. 26 of his book).
Since no such expansion is observed in the Kizuki specimen it is also possible that
this specimen should not be assigned to the fin whale.
Among five species of the genus Balaenoptera we have already excluded three
species, i.e. the minke, the blue and the fin whales. The remaining two species
or the sei whale, B. borealis, and the Bryde's whale, B. edeni, are very close relatives
and it is very difficult to separate the two only from the skull. One feature of theskull of the Bryde's whale is the flat rostrum, compared with somewhat downwardbending rostrum of the sei whale (Junge, 1950; Omura, 1959). The shape of
rostrum in the Kizuki specimen, presumed from the vomer left on the skull, resembles the Bryde's whale rather than the sei whale (Pl. I, Fig. 3). Another character separating the two species is the state of the front margin of the nasals. The
anterior margin is concave in the Bryde's whale, but straight in the sei whale.
In the Kizuki specimen, however, nasals are completely lacking and this character
is of no use in this case (Pl. I, Fig. 1).
Miller (1924) considers the unusually deep and narrow sulcus formed at theregion of juncture between the squamous and articular portion of the squamosalin his Pablo Beach specimen of the pollack whale (No. 236680, US. National
Museum) as a specific character of this species or B. borealis. According to Junge(1950) this sulcus is narrower and deeper in most specimens of B. borealis than it
is in B. physalus and B. edeni. In the Bryde's whale on the coast of Japan this sulcus
is less developed than in the sei whale (Omura, 1959). In this respect the Kizuki
specinen denotes sulcus of B. edeni type, being wide and shallow. In addition, in
B. edeni the basicranial part of the skull exposed behind the palatine is much longer
than broad (Junge, 1950). This also observed in the Kizuki specimen (Pl. I, Fig.
2). It seems that, from the above, the Kizuki specimen shows some charactersof the Bryde's whale rather than the sei whale.
There are, however, some doubts in reliability of such skeletal characters.
Mead (1977) found, in several specimens, some of the characters generally used
to separate B. borealis from B. edeni either intermediate or contradictory, particularly
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

90

OMURA AND KASUYA

the shape of the nasal bones. He examined records of sei whales from the Atlantic
coast of the United States and identified the above-mentioned Miller's specimenof the pollack whale (No. 236680, U.S. National Museum) as B. edeni. He describes that this was confirmed by an examination of the baleen, which is clearly
that of B. edeni. The most remarkable difference, however, which separates B.
edeni from B. borealis in the form of vertebrae is the strong backward inclination of
the spinous processes in the former (Anderson, 1879; Lonnberg, 1931; Junge,
1950; Omura, 1959). This inclination is observed in vertebrae from about 7th
dorsal and increases till its maximum at about 7th lumbar. In the Miller's specimen of Pablo Beach, however, no such backward inclination is observed (Pl. 12of Miller, 1924). Thus the problem is much complicated and we are not able toconclude whether the Kizuki specimen is really a Bryde's whale or a sei whale.
The sei whale on the coast of Japan, however, does not usually migrate to
the south coast of western Japan, but it moves from the Bonin Islands directly to
Sanriku and further north. The Bryde's whales, on the other hand, were takenin these regions in the days of old whaling as well as in the days of modern whaling(Omura, 1977). These facts suggest that the Kizuki specimen possibly representsa Bryde's whale, B. edeni. Size of this whale is estimated to be 12 m, assumingthat the skull is about 25% of the whale body.
Dating of the Kizuki specimen was not made, but there is a record kept at
the Japan Whaling Association that two Iwashikujira were taken at Saganoseki(see Fig. 1) in 1926. At present the name Iwashi-kujira only means the sei whale,
B. borealis, but in these days no distinction was made between the sei and Bryde's
whales. In any case this will suggest that the Bryde's whale (or sei whale) usuallycame into the Inland Sea until about 50 years ago. As far as we know a whaling. landstation was established at Saganoseki in 1926, but it was closed soon due to
unexpected scarcity of whales coming there.
ACKNOWLEDGMENTS

We are much indebted to Mr Morosuke Ono and Mr Shoichi Abe of the Kizukishiritsu Minzoku Shiryokan, who gave us all the help we needed while measuring
and photographing the specimen. Our sincere thanks are due to Mr Shiro Takamatsu of the Oita Marine Palace and Dr Teruo Tobayama of the Kamogawa Sea
World who gave us the opportunity to study this specimen.
REFERENCES.
ANDERSON, J., 1879. ,Zoological results of the two expeditions to western Yunnan in 1868 and 1875, I: 551-564.
London: B. Quaritch.
ANDREWS, R. C., 1914. Monographs of the Pacific cetacea. I. The California gray whale (Rhachianectes
glaucus Cope). Mem. Amer. Mus. Nat. Hist. (New Ser.) 1: 227-287.
JUNGE, G.C.A., 1950. On a specimen of the rare fin whale, Balaenoptera edeni Anderson, stranded on Pulu
Sugi near Singapore. ,Zoologische Verhandelingen, 9: 1-26.
Li:iNNBERG, E., 1931. The skeleton of Balaenoptera brydei 6. Olsen. Arkiv. ,Zool., 23: 1-23.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979SKULL OF BALEEN WHALE

91

MEAD, J. G., 1977. Records of sei and Bryqe's whales from the Atlantic coast of the United States, theGulf of Mexico, and the Caribean. Rep. int. Whal. Commn (special issue 1): 113-116.
MILLER, G. S., 1924. A pollock whale from Florida presented to the National Museum by the Miami
Aquarium Association. Proc. U.S. .Nat. Mus., Vol. 66, art. 9: 1-15.
OMURA, H., 1959. Bryde's whale from the coast of Japan. Sci. Rep. Whales Res. Inst., 14: 1-33.
OMURA, H., 1974. Possible migration route of the gray whale on the coast of Japan. Sci. Rep. Whales Res.
Inst., 26: 1-14.
OMURA, H., 1975. Osteological study of the minke whale from the Antarctic. Sci. Rep. Whales Res. Inst.,
27: 1-36.
OMURA, H., 1977. Review of the occurrence of Bryde's whale in the northwest Pacific. Rep. int. Whal.
Commn (special issue 1): 88-9 l.
OMURA, H., T. lcHIHARA, and T. KASUYA, 1970. Osteology of pygmy blue whale with additional information
on external and other characteristics. Sci. Rep. Whales Res. Inst., 22: 1-27.
SHINDO, N., 1975. History of whales in the Inland Sea. Hyogo Dietists' Institute. Hyogo. 89 pp.
ToMILIN, A. G., 1967 Mammals of the U.S.S.R. and adjacent countries, IX, Cetacea. Israel Program for Scientific
Translations. Jerusalem. 717 pp.

Sci. Rep. Whales Res. Inst.,.No. 31, 1979

92

OMURA AND KASUYAEXPLANATION OF PLATESPLATE I
Fig. 1.
Fig. 2.
Fig. 3.

Dorsal view of the Kizuki specimen.
Inferior view of the Kizuki specimen.
Lateral view of the Kizuki specimen.

Fig. I.

Posterior view of the Kizuki specimen.

PLATE II

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

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EPIDERMAL CYST IN THE NECK OF
A KILLER WHALE
TOSHIRO KAMIYA
Department ef Anatomy, Faculty ef Medicine, University of Tokyo, TokyoTERVO TOBAYAMA
Kamogawa Sea World, Chiba

AND
MASAHAR U NISHIW AKI
University ef the Ryukyus, Naha, Okinawa
Two killer whales with small recess in the skin on the anterior rim of the forelimbwere reported by Nishiwaki (1973)*. One killer whale in Vancouver Public
Aquarium showed a pair of recesses on the right and the left on the anterior rimof the forelimb and another one in Kamogawa Sea World, Chiba showed a single
recess on the right side of the cranio-ventral rim of the forelimb (Fig. 1).
Nishiwaki regarded these recesses as vestigial teats in view of their sites, atthe same time pointing out a high possibility of the occurrence of similar structure
in other cetacea especially killer whales. Among these two killer whales withrecess reported by Nishiwaki, the killer whale in Kamogawa Sea World died ofliver dysfunction in July 1975 (body length 533 cm, body weight 1,600 kg, male).
Autopsy performed to clarify the cause of death revealed the nature of the recess
in question as a tube shaped epithelial pocket with the diameter of 5 mm anddepth of 8 cm as shown in Fig. 2.
The recess enters vertically from the superficial layer into the corium and theoutside of the tip is surrounded by thick and firm capsule-like structure consistingof connective tissue. The shape of the tip of the aberrant epithelium appears likean ending with alveolar and ductal branching as if blocked by the thick capsulelike external wall. The lumen of the tubular recess is filled by abrased epithelium
appearing as cerumen. From the origin of the recess to the end of the surrounding
tissue, no glandular structure was found at all macroscopically and histologically,and no nerve endings were found. Within the connective tissue surrounding theterminal portion of the recess, however, melanocyte-like cells were found scattered.
Based on the present autopsy findings, the recess in the skin of the killer whales
reported by Nishiwaki was found to correspond to the pathological picture of epidermal cyst in man. Unlike the epidermal cyst in man the recess in killer whale
is characterized by the presence of melanocyte-like cells in the connective tissue
surrounding the tip of the recess. No epidermal melanocytes are found in the* Nishiwaki, M., 1973.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 93-94

Possible vestigial teats of killer whales.

Sci. Rep. Whales Res. Inst., 25: 277-278.

94

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AN AGGRESSIVE ENCOUNTER BETWEENA POD OF WHALES AND BILLFISHPETER F. MAJOR/vlarine j\Jammal Commission, rVashington, D.C.

An aggressive interaction or " battle " between a pod of large unidentified whales
and a group of billfish, also unidentified (but probably marlin in the family lstiophoridae ), was observed in August 1951, near Kahuku Point, the northern most
tip of the island of Oahu in the Hawaiian Archipelago. The interaction lasted
approximately 5-10 minutes and occurred in calm water at approximately 1230
hours local time, about 0.9 to 1.9 km due north of a position, 21°42.2'N, 158°01 'W,
on the beach, and about 2.2 to 2.4 km due west of Kahuku Point. Based oncharted (U.S. Coast and Geodetic Survey Chart No. 4110) depths, the interaction
occurred on the surface over, what is thought to be, water with depths of about
11-35 m.
Splashing, boils of water and the backs of large whales breaking the surface
were initially seen. The first evidence that billfish were involved, was the rollingto its right of a whale, such that a billfish, firmly embedded in the whale's left
flank, was lifted clear of the water to a near vertical position above the whale.
The billfish thrashed back and forth, snapped off its bill and fell into the water
as the whale turned upright and submerged. Minutes later another billfish waslifted out of the water to a position about one-half to one-quarter from the verticalabove a whale. The whale rolled back into the water with the billfish still embedded. Splashing, water boils and the backs of whales were seen for an additional
few minutes, and then abruptly stopped.
Evidence, that interactions between whales and billfish occur, has beenoccasionally reported in the literature (Ruud, 1952;Jonsgard, 1959, 1962; Nemoto,
1959; Brown, 1960; Machida, 1970; Ohsumi, 1973). The principal evidence
has been the finding of the S\,rnrds of billfish embedded in whales taken by whaling
vessels. Sonrel (1870, p. 144) and Brown (1960) recount observed interactions between whales and billfish. The present report provides additional evidence of suchencounters, and suggests how both whole and fractured swords result and become
embedded in whales.
REFERENCES
1960. Swordfish and whales. Norsk Hvaifangst-Tid., 48 (8): 345-51.
1959. New find of sword from sword-fish (Xiphias gladius) in the blue whale (Balaenoptera
musculus) in Antarctic. Norsk Hvaifangst-Tid., 48 (7): 352-60.
]ONSGARD, A., 1962. Three finds of swords from swordfish (Xiphias gladius) in the Antarctic fin whale (Balaenoptera physalus L.). Norsk Hvalfangst-Tid., 51 (7): 287-91.
MACHIDA, S., 1970. A swordfish sword found from a North Pacific sei whale. Sci. Rep. Whales Res. Inst.
BROWN, S. G.,]ONSGARD, A.,

Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 95-96

96

MAJOR

22: 163-164.
NEMOTO, T., 1959. Food of baleen whales with reference to whale movements. Sci. Rep. vVhales Res. Inst.,
14: 149-290.
0HSUMI, S., 1973. Find of marlin spears from the Antarctic minke whales. Sci. Rep. Whales Res. Inst., 25:237-239.
Ruun, J. T., 1952. Do sword-fish attack the large whales? Norsk Hvalfa11gst-Tid., 41 (4): 191-3.
SoNREL, L., 1870. The Bottom of the Sea. Sampson Low, Son, and Marston, London, 144 pp.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

CAROTENOID COLORED MINKE WHALE FROM
THE ANTARCTICHIDEHIRO KATO
T17hales Research Institute, Tokyo

On 16 February 1979, an unusual minke whale (Balaenoptera acutorostrata) which
had a strange body color was captured by the Japanese whaling fleet in Area IV of
the Antarctic. According to information from the catcher boat, this whale was
TABLE 1. BODY MEASUREMENTS AND OTHER DATAOF CAROTENOID COLORED MINKE WHALE
Serial no.
Date of catch
Position of catch
Post-mortem timeSex
Age (yrs.) (number of layers in ear plug)
Thickness of blubber (cm)Body proportion (cm)
Total length, tip of shout to notch of flukes
Tip of snout to center of blowhole
Tip of snout to center of eye
Tip of snout to ear
Length of ventral grooves (max.)
Umbilicus to end of of ventral grooves
Notch of tail flukes to center of anus
Notch of tail flukes to tip of dorsal fin
Half of the girth, at umbilicus
Half of the girth, at anus
Dorsal fin, vertical height
Flipper, tip to anterior insertion
Flipper, tip to axilla
Flipper, greatest width
Tail flukes, tip to tip
Tail flukes, notch to the nearest part of the anterior margin of the tail flukes
Half number of ventral grooves, at anterior insertion of each flipper (no.)
Skull (cm)Length, codyles to tip of premaxilla, straight
Breadth, frontal
Reproductive organs
Testis weight (right, left; g)Penis length (cm)
Stomach contents
Food item
Relative quantity
Relative freshness

Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 97-99

2241
16/Feb./1979
64°40'S, 104°08'E
1 hr 50 mins
Male

9++
5.5
740
115

142
183

402
28
205
204

225
135
39
108
83
29

211
55
29
176
96
570,530
74
Euphausiids
30%
Moderately fresh

98

KATO

swimming with one other whale in a school and the crew could easily recoginize
pinkish color on the lateral side of this whale at sea.
The whale taken was a male 7.4 m in total length (serial no. 2241) and it had
almost normal viscera, though the kidny fat of this whale was yellow in color. Body
proportions and other data from this whale are indicated in Table 1.
In general, the external coloration of minke whales in the Antarctic is graydorsally and white ventrally (Williamson, 1961; van Utrecht and van der Spoel,
1962; Kasuya and lchihara, 1965; Ohsumi et al., 1970). However in this case, theventral surface and other areas normally white in color were pink (Pl. I, Figs 1 and2), while the blubber, connective tissue and baleen plates (except the black band
portion) were flushed with a carotenoid color (Pl. I, Fig. 3). Furthermore thewhole skeleton of this whale retained a carotenoid color during Bensing, but when
dried up, it was difficult to distinguish the color from skeletons of other whale. A
whale with such a coloration as this had not seen previously by the crew of the factory ship, even though many of them had much whaling experience.
Though the cause of this unusual coloration was not apparent, judging fromthe external and internal features it was not caused by congestion or albinism. The
post-mortem time (1 hr 50 mins) might influence the coloration of this whale, but
it was not apparant too. In order to clarify the cause, pigmentary analysis is necessary as a first step. Specimens of skin, blubber and baleen plates were collected
and these were preserved frozen as well as in 10% formalin solution. Detailed results of the pigmentary analysis of these specimens will be reported later.
I wish to express deepest appreciation to Dr P. B. Best, Marine Mammal Laboratory, Sea Fisheries Branch, South Africa for his kind advice and supplying ofphotograph (Pl. I, Fig. l ).
REFERENCES
KAsuvA, T. and T. lcHIHRA, 1965. Some informations of minke whales from the Antarctic. Sci. Rep. T1lhales
Res. Inst., 19: 37-43.
0HSUMI, S., Y. MASAKI and A. KAWAMURA, 1970. Stock of the Antarctic minke whale. Sci. Rep. Whales Res.
Inst., 22: 75-125.
van UTRECHT, W. L. and S. van der SPOEL, 1962. Observations on a minke whale (Mammalia, Cetacea)
from the Antarctic. :(eitschrift fur Siiugetierkunde, 2 7 (4): 217-221.
WILLIAMSON, G. R., 1961. Two kinds of minke whale in the Antarctic. Norsk Hvalfangst-Tid., 50 (4): 113-

0141.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979CALOTENOID COLORED WHALE

EXPLANATION OF PLATE
PLATE I
Fig. 1. A comparison of body colors between unusual and normal whales (Photograph by Dr P.B. Best).
Fig. 2. Lateral view of rostrum and baleen of the unusual ~hale showing pinkishcolor and dark pigmented areas.
Fig. 3. Baleen plates and gum layer of the same whale showing carotenoid color.

Sci. Rep. Whales Res. Inst.,
No. 31, 197999

UNUSUAL MINKE WHALE WITH DEFORMED JAW
HIDEHIRO KATO
Whales Research Institute, Tokyo

An unusual minke whale (Balaenoptera acutorostrata) was captured by the Japanesewhaling fleet on 27 January 1979 in Area IV of the Antarctic (serial no. 1645).
The rostrum of this whale was abbreviated and bent towards the lower jaw which
was rather wide compared with a normal animal (Fig. 1). There are several
TABLE 1. BODY MEASUREMENTS AND OTHER DATA OF UNUSUALMINKE WHALE COMPARED WITH TWENTY NORMAL WHALES
Twenty normal whales
Unusual whale
Range
Serial no.
Date of catch
Position of catchSex
Age (yrs.) (number of layers in ear plug)
Thickness of blubber (cm)Body proportion (cm)
Toto! length, tip of snout to notch of flukes
Tip of snout to center of blowhole
Tip of snout to center of eye
Tip of snout to ear
Tip of snout to tip of lower jaw
Length of ventral grooves (max.)
Umbilicus to end of ventral grooves
Notch of tail flukes to center of anus
Notch of tail flukes to tip of dorsal fin
Half of the girth, at umbilicus
Half of the girth, at anus
Dorsal fin, vertical height
Flipper, tip to anterior insertion
Flipper, tip to axilla
Flipper, greatest width
Tail flukes, tip to tip
Tail flukes, notch to the nearest part of the anterior
margin of the tail flukes
Half number of ventral grooves, at anterior
insertion of each flipper (no.)
Skull (cm)Length, codyles to tip of premaxilla, straight
Breadth, frontal
Reproductive organs
Mammary gland (length, width, depth ; cm)
Number of corpora lutea and albicantia (no.)
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 101-103

1645
27/Jan./1979
67°09'S, 71°48'E
Female
40+
4.5

Mean

1569-2061
24/Jan.-9/Feb./1979
Antarctic
Females
3.5-6.0

4. 7

870
100
144
181
28
461
49
261
280
186
131
33
140
105
34
219
60

860-890125-144
158-185
198-230

873.5
134.9
171.9
215.2

436-492
15-53
217-248
238-273
191-245130-156
28-40
121-151
92-11030-35
223-270
55-65

466.5
28.8
235.0
252.4
223.8
139.7
34.8
136.4
100.8
32.9
243.6
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20-28

25.0

180
116

196-223
106-120

211.8
112.4

129,22,2.9
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DEFORMED JAW

103

This whale was an old female of 8. 7 m in length and pregnant with one fetus(female, 30.3 cm long). The viscera and fetus of this whale were completely normal. A comparison of its proportions and other data with those for twenty normal
whales (all females, 8.6-8.9 m in length) is given in Table 1.
In all three measurements of the head region, namely, the length from tip of
the snout to center of blowhole, to center of eye and to ear, whale no. 1645 was
shorter than normal. There also seemed to be a significant difference in the lengthfrom the tip of the snout to the tip of the lower jaw, but no data were recorded on
this measurement for normal whales.
As shown in Table 1, whale no. 1645 has longer tail than normal. This may
be indicated that actual body length of this whale is longer than 8. 7 m if it had
normal jaw. The skull of this individual was shorter than normal, but its breadthfell within the range for whales of the same body length.
Furthermore, although the girth (half, at umbilicus) of whale no. 1645 was lessthan normal whales, the thickness of the blubber was within the range for normal
whales. This indicate that it could feed with little difficulty by such an abnormal
mouth.
I wish to express deepest appreciation to Dr P. B. Best, Marine Mammal Laboratory, Sea Fisheries Branch, South Africa for his kind advice.
REFERENCES
NAKAMURA, K. 1968. Studies on the sperm whale with deformed lower jaw with special reference to its
feeding. Bull. Kanagawa Pref. Mus., 1: 13-27.
NAsu, K. 1958. Deformed lower jaw of sperm whale. Sci. Rep. Whales Res Inst., 13: 211-212.
0HSUMI, S. 1959. A deformed fin whale fetus. Sci. Rep. Whales Res. Inst., 14: 145-147.
SPAUL, E. A. 1964. Deformity in the lower jaw of the sperm whale (Physeter catodon). Proc. :(ool. Soc. Lond.,

142 (3): 391-395.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

THE POST-BREEDING DISTRIBUTIONS OF ICE-BREEDING
HARBOUR SEAL (Phoca largha) AND RIBBON SEAL
(Phoca jasciata) IN THE SOUTHERN SEA
OF OKHOTSKYASUHIKO NAITO
National Institute of Polar Research, TokyoAND
SHIGEYUKI KONNOTokyo University of Agriculture and Technology, Tok)•O

ABSTRACTThe distribution of harbour seal (Pho ea largha) and ribbon seal (P. fasciata)
was studied. The field survey was performed from 1 May to 3 June of 1975
in the four pack ice areas along the eastern coast of Sakhalin. In theseareas harbour seal was dominant in the southern area and overcomed by
ribbon seal in northern areas. The pups of both species appeared in low
frequency. However in the southern area, the pups of ribbon seal appeared
frequently. The female adult harbour seals were dominant compared withthe adult males, and it was suspected that adult females stay longer on theice floes. In this connection ribbon seal showed the same sex ratio between
males and females through all age classes except pups. However, the different
sex ratio of subadult seals was observed between areas such as male dominantarea and female dominant area. While the group size of harbour seal wascomposed of small number of individuals (average 1.8 seals), ribbon seal did
not form the any group but appeared in solitary.
INTRODUCTION
The harbour seals (Family Phocidae, Genus and Subgenus Phoca 1758) were studied
from the point of view of taxonomy and systematics in recent years, and it was
supposedly concluded that there exist two harbour seal species in the North Pacific.
Those are, namely, ice breeding harbour seal (Phoca largha Pallass 1811) and land
breeding harbour seal (Phoca vitulina richardsi Gray 1864 ). Among these seals,
ice living harbour seal is still little known species. Especially the knowledges
concerning to their life in the ice region are quite scarce. As a consequence, knowledges on their distribution and migration are some times speculative. Similar toice breeding harbour seal, ribbon seal (Phoca fasciata Zimmermann 1783; Family
Phocidae, Genus Phoca, Subgenus Histriophoca) is also one of the most unknown
species.
The unconfirmed knowledges concerning to their distribution and migration
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 105-119

106

NAITO AND KONNO

145°E

140°E

',

\

\
\

I

,J

OKHOTSK SEA

50°N

50°N

45°N

45°N

145°E
Fig. 1. Sampling was performed in the above 4 areas in the southern Sea of
Okhotsk. The figures in each area show the date of sampling. Dotted line
shows 200 m isodepth line.

are due to the difficulties in the ice region survey. Especially the latter seal havepelagic habitat visiting coast seldom after the ice floes melt (Burns 1970). Therefore it is still more difficult for us to access to them.
Our objective here are generally to provide some informations on their distribution and migration in the ice floe region and especially to add the informations
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

HARBOUR SEAL AND RIBBON SEAL

107

on their social structures.
Our field studies were dependent on the commercial sealing which started
from the first of May continuing for about a month when the breeding season
was over and the ice floes were melting and retreating. Therefore, we missed theimportant breeding season for our purpose. The breeding season of harbour
seal was suggested from mid to end of March (Naito and Nishiwaki 1972), andthe ribbon seal was from mid March to first of April (Tikhomirov 1971). Therefore we studied the distributions of post breeding season (1-1.5 month later).
MATERIALS AND METHODS
From 1 May to 4 June in 1975, field studies were made in the eastern coast of
Sakhalin to analize the harbour seal and ribbon seal distribution. The sealing
were first operated from south to north following the retreating pack ice. The
pack ice was almost final melting stage in this season, and the pack ice showed
relatively low density and they were dispersing. However the sealing boat insome occasion did not penetrate into the pack ice to stop sealing. In this study
the areas where the sealing operated were separated into four areas in accordancewith the pack ice distribution. These areas were: area I, the south eastern partof Aniva Bay or the first operation area; area II, the mouth of Terpeniya Bay or
the second operation area; area III, the eastern mouth of Terpeniya Bay or thelast operation area; and area IV, the eastern coast of northern Sakhalin or thethird operation area (Fig. 1). Among these areas, except area III the sealing was
performed from south to north as season advances. The ice conditions, depth ofwater, date of sealing of these areas were shown in Table 1.
TABLE 1. THE ICE CONDITION, DEPTH OF WATER AND DATE OF OPERATIONOF EACH SEALING AREA. THE ICE CONDITION WAS INDICATED BY
THE DEGREES OF ICE COVERED AREA IN SIGHT AND THE ICE
COVERED AREA WAS CLASSIFIED INTO TEN DEGREES.
Area

Average amountof iceRange

Depth ofwater (m)

Date

II
III
IV

3.75/10
3.40/10
3 .10/10
1/10

3/10-4/10
1/10-7/10
1/10-4/10
1/10

100-200
60-100150-200
100-150

1-5 May
6-19 May
26 May-! June
3-4 June

Through this field work, the right lower jaws were collected from 390 harbour
seals and 761 ribbon seals, and preserved in 5-10% formalin. These collected
numbers reached at about 40% of total number of seals caught, and these canine
teeth sampling was made quite at random for the purpose of this study. In thisfield study we also made field observations from the upper bridge of the motherboat to collect the data for group size analysis.
Concerning the age determination of harbour seal, the same methods asreported by Naito and Nishiwaki (1972) was followed. However, the method of
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

108

NAITO AND KONNO

ribbon seal age determination was newly studied by using the tooth of known age
of dead seal which was kept at Kamogawa Sea World in Chiba Prefecture, Japan.
The age determinations of the ribbon seals were successfully performed by reading
both dentine layers and cementum layers (Naito and Tobayama; unpublished).
Concerning the catch selection in this study, there exist no strong selectivity
between each species, for sealing were made only on the ice floes by using the riffiewith the scope. However, in general harbour seal was more cautious than the other.
The species dealt in this study were only harbour seal and ribbon seal. There
distribute ringed seal (Phoca hispida) and bearded seal (Erignathus barbatus) in theseareas. However these seals, if identified by hunters, were not caught owing to thelow quality of their fur. Therefore, these species were not studied in this study.
SPECIES COMPOSITIONIn this study it was difficult to obtain data to evaluate catch effort such as
hunter's skill, catch difficulty by ice or weather conditions and etc., therefore inthis chapter only comparative species ratio was treated.
TABLE 2.

Area
II
III

IV
Total

SPECIES COMPOSITION AMONG HARBOUR SEAL AND
RIBBON SEAL IN EACH AREA

No. harbour
seal

122
216
39
13
390

%
80.8
33. l
18.2
9.8

No. ribbon
seal

29
437
175
120
761

%
19.2
66.9
81.8
90.2

Total
number

151
653
214
133
1, 151

Species composition of harbour seal and ribbon seal collected in each area
are shown in Table 2. The numbers collected in all 4 areas were 390 harbour
seals and 761 ribbon seals respectively. This result may indicate that ribbon
seal distributed 1.95 times as much as harbour seal in these areas and season. To
the contrary, however, each areas showed the different specific structure. As
shown in Table 2, area I was considered as a harbour seal dominant area, and area
II was possibly considered as both species mixed area. Ribbon seal highly dominant in areas III and IV, showing 81.8% and 90.2% respectively. Therefore it
was considered that ribbon seal appeared frequently in northern areas and later
season. Although the explanation for this phenomena is still uncertain, it may
related with difference of ice utilization by both species. Tikhomirov (1961) andNaito and Nishiwaki (1975) stated that in May and June harbour seal begin toappear in the coastal area coinciding with ice melting season, and Tikhomirov(1961) also reported that ribbon seal seldom descend into the water in May andJune when they are moulting. In this connection, it was quite natural that ribbon
seal was generally abundant in these areas, and being hunted in later season inareas III and IV where harbour seal was less dominant.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

109

HARBOUR SEAL AND RIBBON SEALAGE AND SEX COMPOSITIONSHarbour seal
Age composition of harbour seal is shown in Table 3 and Fig. 2. Of all age
classes the pups and one year old seals of both sexes appeared most frequently, andthe appearance frequency of older seals gradually decreased. The fem ales seemedto show less gradual decrease, and the oldest seal was 30 years old in male and 33
years old in female.
In general the standing stock of pups should be most abundant. However
AGE COMPOSITION OF 390 HARBOUR SEALSCOLLECTED FROM ALL 4 AREAS

TABLE 3.

Age

No. malesin sample% inmale sample

No. females
in sample% infemale sample

40
46
19
22
17
13
8
10
5
2
0
4
5
2
6
2

18.0
20.7
8.5
9.9
7.6
5.8
3.6
4.5
2.2
0.9
1.3
1.8
2.2
0.9
2.7
0.9
0.5
0.9
0
0.9
0.9
0
0.5
0.9
0.5
0.5
0.5
0
0
0.9
0.5
0.5
0
0.5

222

0

47
47

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

11

0
0
0

28.0
28.0
6.5
8.9
7.7
3.0
4.1
0.6
1.8
1.8
0
1.8
0.6
1.8
0
1.2
0.6
0.6
0.6
0.6
0
0
0.6
0.6
0
0
0
0
0
0
0.6
0
0
0

Total

168

rno.o

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

15
13
5
7
3
3
0
3
1
3
0
2

I

0
0

0
0
0
0
0
0
I

2
0
2
2
0
2

0
0
2

0
1

100

NAITO AND KONNO

110

in this study pups appeared in same abundance as one year old seals. According
to Natio and Nishiwaki (1975), pups are dependent on ice floe even after weaning,
and they are much dispersed by ice movements. This suggestion may explain
the above result. Concerning the sex ratio, it is very clear that both sex of pups
and 1 year old seal appeared almost same frequency and, in the most of other age
classes females were dominant. Not shown in Table 3, but the sex ratio is 52.2%
females for both pups and one year old seals and 64.8% females for other older seals.
This may suggest that the older female seals remain longer on ice floes than maleseals. To analyse more precisely, the age was classified into several classes, suchas (1) pup class, (2) immature class (1-2 years old), (3) subadult class (3-6 years

•O

30

20

10

Fig. 2. Age composition of harbour seal. Black column represents the male seal
and white column represents the female seal.

old), (4) adult class (7-10 years old) and (5) old class (11 or more years old). As
seen in Table 5, the sex ratios with 46% and 52.8% female for pup and immatureclass clearly differ from the ratio with 60%, 74.1 % and 69.8% females for subadult, adult and old classes. From these facts, it was possibly concluded that theadult female harbour seal remain longer on ice floes.

Ribbon seal
Age composition of ribbon seal is shown in Table 4 and Fig. 3. A number ofpup seals appeared in quite low level as in the case of harbour seal pup. However,after one year old, the both sexes of seal decreased gradually in almost same rate.
The oldest seal was 26 years old in male and 22 years old in female. Concerning the longevity of this seal, almost same result was obtained as reported by
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

HARBOUR SEAL AND RIBBON SEALTABLE 4.

111

AGE COMPOSITION OF 761 RIBBON SEALS COLLECTED FROM ALL 4 AREAS

Age

No. malesin sample';;~ inmale sample

No. females
in sample% infemale sample

0

18
90
71
52
49
29
14
17
6
9
7
6
2
4
3

30
96
61
47
35
31
18
16
lO
6
5
3
2
4

3
0
0
0
0
0
0
0
2
0
0
0
0
0
0
0

4.7
23.4
18.5
13.5
12.8
7.6
:3.6
4.4
l.6
2.3
1.8
1.6
0.5
1.0
0.8
0.3
0
0.3
0.8
0
0
0
0
0
0
0
0.5
0
0
0
0
0
0
0

8.0
25.5
16.2
12.5
9.3
8.2
4.8
4.2
2. 7
l.6
1.3
0.8
0.5
1.1
0.3
0.5
0.5
0.3
0.8
0
0.5
0.3
0.3
0
0
0
0
0
0
0
0
0
0
0

384

100

377

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
Total

0

2
2
3
0
()

0
0
0
0
0
0
0
0
0
0
0

100

Tikhomirov (1971). He reported that the maximum age reached by ribbon seal
in natural conditions is 22-26 years.
The low appearance frequency of harbour seal pups was considered in relation to it's ice dependent life and ice movements. In ribbon seal, though uncertain, the same reason may be considered as well. Contrary to harbour seal, sex
ratio of pups seemed to be quite abnormal. However this low representation ofmale pup in Fig. 3 seemed to be caused by small sample size. As well as harbour
seal, the difference of sex ratio was compared between several age classes such as(1) pup class, (2) immature class (1-2 years old), (3) subadult class (3-6 years old),(4) adult class (7-10 years old), (5) old class (11 or more years old). These age
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

NAITO AND KONNO

112

30

20

,0

30

AGE

Fig. 3. Age composition of ribbon seal. Black column represents the male seal
and white column represents the female seal.
TABLE 5. AGE GROUP COMPOSITION OF 390 HARBOUR SEALS (UPPER) AND
761 RIBBON SEALS (LOWER) COLLECTED FROM ALL 4 AREAS
Harbour Seal
Age class

No. malesin sample% inmale sample

No. females
in sample% infemale sample

Total No.

% intotal sample

0
1-2
3-6
7-10
11-

47
58
40
7
16

54.0
47.2
40.0
25.9
30.2

40
65
60
20
37

46.0
52.8
60.0
74.1
69.8

87
123
100
27
53

22.3
31.5
25.7
6.9
13.6

Total

168

43.1

222

56.9

390

100.0

Age class

No. malesin sample~lo inmale sample

No. females
in sample% infemale sample

Total No.

% intotal sample

0
1-2
3-6
7-10
11-

18
161
144
39
22

37.5
50.6
52.4
51.3
50.0

30
157
131
37
22

62.5
49.4
47.6
48.7
50.0

48
318
275
76
44

6.3
41.8
36. l
10.0
5.8

Total

384

50.5

377

49.5

761

100.0

Ribbon Seal

classes were settled by considering the sexual maturity data by Tikhomirov (1968).
The sex ratios of each age class are shown in Table 5. The sex ratio of 62.5%of female pup is little higher than expectation. However, the ratios of 49.4%,
Sci. Rep. Whales Res. Inst.,

No. 31, 1979

HARBOUR SEAL AND RIBBON SEAL

113

47.6%, 48.6%, 50% females for immature class, subadult class, adult class and oldclass indicate that both sexes of this seal appeared in same ratios, and this result
was quite different from the result obtained from harbour seal. The ratios for maleand female of all classes in total are 50.5% and 49.5% respectional. From thesefacts it may be concluded that sexual segregation does not occur, even in adult andsubadult classes. This result, however, was different from that indicated by Tikhomirov (1961 ). He described that in some aggregations occasionally the predominance of males and females had been observed. The above mentioned different
results may due to the surveyed area size. In this chapter, sex ratios of all seals
from all four areas were discussed. However in this study, we compared the age
and sex composition between each areas of I-IV to obtain the more detailed knowledge on distribution of these species.
Harbour seal
As seen in Table 6, of all 390 harbour seals 122 seals were collected in area
I and 216, 39 and 13 were collected in areas II, III, IV respectively. Thesesample numbers generally reflect the abundance in these areas and indicate thatharbour seal were much abundant in area I and II. Concerning the age compositions, pups appeared to distribute in all areas, with age class ratio between
15.4%-30.8% of totals, and it was presumed that pups showed the scattered distribution in all areas, even in areas III and IV where this seal was less abundant.
Immature class (1-2 year class) seals appeared in high frequency in areas I andII with ratio 46. 7 % and 28. 7 % and low frequency in areas II and IV with ratio
both 7.7%. This may indicate that the immature seals concentrate to a certain
degree in areas I and II. The subadult and adult class seals seemed to appear
randomly, and old class appeared in areas I and II less frequently with ratio 4.1 %and 11.6%, and more frequently in areas III and IVwith ratio 41.0% and 53.8%.
It may be true that the distribution of pup widely spreads out and scatters.
As already mentioned pups stay on ice floes for a while even after weaning andhave ice dependent life (Naito and Nishiwaki 1972) and as a consequence, pup
occurrs in far south water along the coast or Japan (Naito 1976). These facts
may support above result. In this study some tendency of concentrations byimmature seals occurred in southern area and it was not widely known that immature harbour seal tend to concentrate. However the fact that concentrationof young harbour seals was annually observed near St. Mathew Island in the
Bering Sea (Tikhomirov and Kosygin 1966) may support the result obtained in thisstudy. Furthermore, the imformations from hunters that the immature harbour
seals are distributed in concentration should be taken into the considerations.
However, we are still short in data to obtain the clear result.
Concerning the sex ratio, there obtained the clear result in this study thatolder female seals appeared in high frequency in southern area of I and II andboth sex of immature seals appeared almost same frequency (Fig. 4 and Table
6). However in northern areas of III and IV, such phenomena were not observed
due to shortage of data.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

~

"'

~~

<:.

<c ~~

"tc; ~......... ~;_,, ::0

Total

11-

7-10

~

12
(41.4)

17(58 .6)

29

0

1

3

58.6

17

1-2

27.6

8

100.0

0

3.5

10.3

% in
total
sample2
6(25 .0) (75 .0)
89(52.9) (47 .1)
2
l(33. 3) (67. 7)l0(100. 0)(0)0
0

- - - ·- ----- ----

0

Area I

Total
No.

3-6

~

100.0

No. of No. ofmales females
(%)
(%)

::0

:-'·

122

4.1

3.3

4

5

19.7

46.7

26.2

24

57

32

89
(41. 2)24(53.3)
28(45.2)
31(46.3)
4(23.5)
2(8.0)
127(58.8)

21(46. 7)34(54.8)
36(53. 7)
1::1(76.5)
23(92 .0)No. of No. ofmales females
(%)
(%)

216

25

17

67

62

45

Total
N
o.

Area II

100.0

11.6

7 .9

31.0

28. 7

20.8

% in
total
sample24(61. 5)

5(83.3)
3(100.0)3(37 .5)3(50.0)
10(62 .5)15(38.5)

1(16. 7)0(0)5(62.5)
3(50. 0)6(37. 5)

No. of No. ofmales females
(%)
(%)

39

16

6

8

3

6

Total
No.

Area III

100.0

41.0

15.4

20.5

7.7

15.4

% in
total
sample6(46. 2)

7(53.8)

2
2(50 .0) (50.0)01(0)(100.0)01(0)(100.0)
0
0
(0)
(0)
4
3
(57 .1) (42. 9)

No. of No. ofmales females
(%)
(%)

13

7

0

1

1

4

Total
N
o.

Area IV17(58.6)
99(49. 7)60(37 .5)16(45. 7)7(50.0)
199(45. 5)12(41.4)
100(50.3)
100(62. 5)19(54.3)
7(50.0)
238(54 . .5)

No. of No. ofmales females
(%)
(%)

90
(51.4)

100.0
437

14

35

3.2

8.0

36.6

45.5

199
160

4
(66. 7)26(54.2)
34(48. 5)15(50.0)
11(52 .4)85(48.6)

2(33. 3)22(45.8)
36(51.5)
15(50.0)
10(47 .6)

17.5

21

30

100.0

12.0

17.2

40.0

27.4

48
70

3.4

% in
total
sample---------- ---

6

Total
No.

Area IIINo. of No. ofmales females
(%)
(%)

6. 7

% in
total
sample-------~----

29

Total
No.

-~-------··--------------·

Area II

100.0

53.8

0

7.7

7.7

30.8

% in
total
sample44(:{6. 7)76
(63.3)

05(0)(100.0)26
28(48. l) (51.9)933(21.4) (78.6)
55(50.0) (50.0)
4
5(44.4) (55 .6)

No. of No, of
males females
(%)
(%)

120

9

10

42

54

5

Total
No.

100.0

7.5

8.3

35.0

45.0

4.2

% in
total
sample------- ----- ---------· · - - - - - -Area IVAGE CLASS COMPOSITION AND SEX RATIOS OF EACH AGE CLASS RIBBON SEAL IN EACH AREA

73
(59.8)TABLE 7.

49
(40.2)

16
16(50.0) (50.0)
2730(47.4) (52.6)
18
6(25.J) (75 .0)
40(0)(100.0)50(100.0)
(0)

% in
total
sample

Age
class

Total

11-

7-10

3-6

1-2

0

TJtal
o.

Area I

AGE CLASS COMPOSITION AND SEX RATIOS OF EACH AGE CLASS HARBOUR SEAL IN EACH AREA

Age No. of No. ofclass males females(%)(%)

TABLE 6.

z

z0z

0

~

zt:I

;i..

0

......
t-"'I

;i..

-....

HARBOUR SEAL AND RIBBON SEAL

age
group

Area ll

Area I
males

115

N.(49)

femalesN (73)

males

femalesN(89)

N(127)

11-

23

7-10

3-6

31

1-2

27

0

16

24

1CQ 80 60 40 20 0

20 40 60 80 100('/,)

Area lll

age
group

males

100 80 60 40 20 0 20 40 60

eo 100(%)

Area IVN(24)females

N(15)

males

femcilesN(G)N( 7 )

117-103-6

100 80 60 40 20 0

20 40 60 80 100(%)

100 80 60 40 20 0

20 40 60 80 100('!.)

Fig. 4. Sex ratios for age groups of harbour seal in each area, 0: pup class, 1-2:
immature class, 3-6: subadult class, 7-10: adult class and 11-: old classArea nArea I

age
group

males

N(12)

females

N(17)

mates

N(238)

femalesN(199)

117-10

3-6

I)()

1-2
0
100 80 60 40 20 0204060 eo 100

100 80 60 40 20 0 20 40 60 In 1<f.1,)

Area IllArea IV

('!.)

age
group

males

N(90)

N(8S)

females

11-

lO

7 -10

15

3-6

mates

N(44)

females

N(76)

36

-2

22

0
100 80 60 40 20 0

20 40 60 80 100('!.)

Fig. 5. Sex ratios for age groups of ribbon seal in each area, 0: pup class, 1-2:
immature class, 3-6: subadult class, 7-10: adult class and 11-: old class

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

116

NAITO AND KONNO

According to Tikhomirov and Kosygin (1966), south ofNunivak Island in the
Bering Sea they found every spring aggregations of female which had recently
given birth to their pups. In our study, pups had been weaned almost 1.5-2month before and such female agregations were not observed. Although our result
may indicate that adult females keep some aggregation to a certain degree evenafter weaning, it may be more reasonable to understand that the female adultseals remain longer in ice floe region while adult male seals shift their habitate fromice region to the coastal region.

Ribbon seal
In the case of ribbon seal, the relative larger number of samples (761 seals)
were obtained. Out of 761 seals, 29 seals were collected from area I and 437,
175, 120 seals were from areas II, III, IV respectively. And in area II ribbon
seal was most abundant and least abundant in area I (Table 7). Concerning theage composition in each area, as seen in Table 7 appearance frequencies of pupclass and immature class were relatively high in area I compared with other threeareas. Especially pup class seals appeared high frequency in area I. On the contrary subadult class, adult class and old class seals appeared less frequently in arae
I and more frequently in other 3 areas, especially in area III.
From above, it was supposed that the southern area of area I was less abundant area and young seals were predominant like as harbour seal. The area II
was the most abundant area and immature and subadult seals were dominant.
The area III was relatively abundant and older seals were dominant. The area
IV was widely operated area (Fig. 1) and the seals was not abundant, while similar
age composition as in the area II of the most abundant area was observed.
At this stage of study, we could not obtain any reasonable explanation forabove phenomena.
Concerning the sex ratio, as seen in Fig. 5, ratios for all age classes in area
I were fluctuated very much due to the small sample size. From same reason,sex ratio for pup class also fluctuated among each area.
The male and female seals of immature, adult and old adult classes appearedin similar ratio among areas except area I showing the ratios of about 50% forboth sexes. However, only subadult seals showed the different ratio among areas
II, III and IV. In area II, sex ratio with 37.5% for females were observed, on
the other hand, in area IV females were dominant, and ratio of 78.6% for females
was observed. Being still uncertain, it was possibly considered that ribbon sealshows sexual segregation of some certain degree. It is necessary to obtain the datafrom much smaller areas in order to analyze the above problems. In this study,
the several hunting boats operated in wide spreaded areas. These hunting boats
made operations about twice a day, from 4 AM to noon and from 13 PM to 18 PM.
After operation, the seals were boarded on the mother boat where we collected
specimens. Therefore we could not make any more detailed analysis for ribbon
seal distribution.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

HARBOUR SEAL AND RIBBON SELL

117

GROUP SIZEIn this study we also performed the observations on group size of both species.
The group size was estimated by the number of seals laying themselves on the sameice floe. The size of ice floes showed much variations. The largest size was about150-200 m in diameter.
Harbour seal
The group size of the two species was studied in order to know the social
structure of each species. The observations were performed from the top of themother boat bridge while the hunting boats were out from it. As shown in Table
8, 58.9% of the harbour seal groups was composed of a single seal, and 22.3%
was composed of two seals. The larger the group size, the frequency gradually
decreased so far, and the maximum group size was 8 individuals. The averagegroup was composed of 1.8 seals.
TABLE 8. GROUP SIZE AND FREQUENCY OF EACH GROUP SIZE OF HARBOUR SEAL
AND RIBBON SEAL. TOTAL NUMBER OF INDIVIDUALS OF EACH GROUP SIZEWAS ALSO SHOWN IN THIS TABLE. GROUP SIZE WAS ESTIMATED BY THE
NUMBER OF INDIVIDUALS THAT HAULED OUT ON THE SAME ICE FLOE
No. of individuals

No. of sighting
Group size---------·

Harbour seal

Ribbon seal

Harbour seal

Ribbon seal

(%)

(%)

(%)

(%)

2
3
4
5
6
7
8

66(58.9)25 (22. 3)
10 ( 8.9)
5 ( 4. 5)
2 ( 1.8)2 ( 1.8)
1 ( 0.9)l ( 0.9)90 (97 .8)
2 ( 2.2)
0
0
0
0
0
0

66 (32 .5)
50 (24 .6)30(14.8)
20 ( 9 .9)10 ( 4 .9)
12 ( 5 .9)
7 ( 3.4)
8 ( 3.9)90(95. 7)
4 ( 4. 3)
0
0
0
0
0
0

Total

112(100)

92 (100)

203 (100)

94 (100)

The group size observed in this study seemed to be rather small than what
it was under the natural condition, because we obtained the data from the area
where some hunting boats operated around and more or less the seals were disturbed. As the matter of fact, the largest group size was smaller than the groupsize of 12 young seals obtained in the same season and same area in 1971 (Naito
and Nishiwaki 1975). From above result, unfortunately, we could not analyze
the group size from the point of view of sex, age or areas in this study.
Ribbon seal
The ribbon seal showed the distinguishable aspect from the point of view ofgroup size. The group of this seal was composed of a single seal in 97.8% frequency, and only twice a couple of seals laying themselves on same ice floe wasobserved (Table 8). Even in these two cases, it was not supposed that they were
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

118

NAITO AND KONNO

either associated each other or located close together, but observed laying themselves apart on the ice floe.
From these facts, we can conclude that ribbon seal does not form the groupbut keep a distance each other on ice floes in this season. Thikhomirov (1961)
also reported that ribbon seal appear solitary on ice floe.
DISCUSSION

It is generally said that ribbon seal and harbour seal occupy almost similar ice
region. However Burns (1970) reported that in the ice edge zone of the central
Bering Sea, ribbon seal had been most numerous along the inner (northern) edgeof the zone and gradually outcomed by harbour seal towards the southern edge.
In the same sense, we also attained the similar result. However, in our study theseason was different from the above suggestion as already mentioned high frequency of ribbon seal in northern area may be only due to the longer staying
on ice floes compared with harbour seal as suggested by Tikhomirov (1961). We
need the much more data for long period in order to obtain the reasonable conclusions.
Concerning the age and sex ratios, we obtained the result that female adultharbour seals occurred in high frequency and to a certain degree age and sexual
segregation were observed. On the other hand ribbon seals showed no age andsexual segregation as a whole. However, in some areas, sexual segregation wasobserved in subadult class. Burns (1978) described that he had seldom seen maleand female ribbon seal together. We also observed same as he described. Our
above result was based on the data from relatively larger area and the degrees ofsexual segregation seemed to be lower estimation than what it was, because wesometimes observed the adult males dominant zone and adult female dominantzone separately in smaller areas. This sexual segregation seems to occur even in
breeding season (Tikhomirov, 1961). In Nemuro Strait of eastern Hokkaido, sex
ratio offemale adult seal exceeded 70% (Itoh unpublished data) in breeding season.
Burns (1978) also reported that in breeding season both sex of ribbon seal seldom
appear together. The reason why these segregation may occur on ribbon seal isstill uncertain. The peculiar pelage pattern of ribbon seal may play some role
between both sex as some communication like as reported in harp seal (Phoca
groenlandicus) (Evans and Bastian 1969). However, we found that not only matured
ribbon seal, but also immatured seal appeared in solitary. Probably this seal isecologically adapted and specialized as pelagic seal. In this study we were quite
uncertain on this problems.
ACKNOWLEDGMENT

We are very much grateful to Mr Kazuyuki Shibuta, the president of Shibuta sealing
company who kindly permitted us to go on board for collecting samples. We werealso much indebted to Captain T. Ono and his crew who kindly helped us in
Sci. Rep. Whales Res. Inst.,.No. 31, 1979

HARBOUR SEAL AND RIBBON SELL

119

the field work.
REFERENCESBURNS, J. J., 1970. Remarks on the distribution and natural history of pagophilic Pinipeds in the Beringand Chukchi seas. J. Mamm. 5 (3); 445-454.
BuRNs, J.J., 1978. Ice seals. pp. 192-205. In: D. Haley (ed.) Marine Mammals. Pacific Search Press,
Seattle.
EVANS, W. E. and J. BASTIAN, 1969. Marine mammal communication: Social and ecological factors.
pp. 425-476. Jn; H. T. Anderson (ed.) The biology ef marine mammals. Academic Press, New York.
NAITO, Y., 1976. The variation in the development of pelage of ribbon seal with refference to the systematics. Sci. Rep. Whales Res. Inst. 28: 187-197.
NAITO, Y. and M. NISHIWAKI, 1972. The growth of two species of the harbour seal in the adjacent watersof Hokkaido. Sci. Rep. Whales Res. Inst. 24: 127-144.
NAITO, Y. and M. NisHIWAKI, 1975. Ecology and morphology of Phoca vitluina largha and Phoca kurilensis
in the southern Seas of Okhotsk and north east of Hokkaido. Rapp. p.-v. Reum. Cons. int. Expor. Mer.,
169: 379-386.
TIKHOMIROV, E. A., 1961. Distribution and migration of seals in waters of the far east. The ichthyological
Commission ef The Academy of Sciences of the U.S.S.R. (Reports of Conference). Vol. 12. (translated
into English by U.S. Fish and Wildlife Service).
TIKHOMIROV, E. A. and G. M. KosYGIN, 1966. Prospects for commercial sealing in the Bering Sea. Rybnovo
Khozyaistvo, 8: 25-28 (translated into English by F. H. Fay).
TIKHOMIROV, E. A., 1971. Body growth and development of reproductive organs of the North Pacific Phocids.
213-241. In: V. A. Arsenev and K. I. Panin (ed.) Pinnipeds of the North Pacific. Israel Program for
Scientific Translation, Keter Press, Jerusalem (English translation).

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

A RECORD OF THE BEARDED SEAL WANDERING WITH
SPECIAL REFERENCE TO THE WANDERING SPEED
YASUHIKO NAITO
National Institute of Polar Research, Tokyo

The south and north bound wandering around the Boso Peninsula of the bearded
seal (Erignathus barbatus) was recorded in 1977. Many examples of the seal wandering had been reported in many places where so far apart from normal habitat(Richardson, 1975; King, 1975; Naito, 1976; etc.), and the wandering of seal itself
is not so much worth of special mention. However, this record might be of someinterest to report here due to the most far south record in the western North Pacificand its consequent observation made possible an estimation of wandering speed.
One seal was first observed by fishermen in the Amatsu fisheries harbor at
4: 00 PM, 6 September 1977 (Table 1). At this time I could fortunately observe
the seal at 20 meters distance. It was easily identified as the bearded seal fromits outer looking such as characteristic profusion of moustachial whiskers, andanterior insertion of the foreflippers. The sex was also identified as male fromexistence of opening of male genital organ. The seal was roughly estimated to be
as large as 1.5 m and its age was supposed as a young animal. The body color
was muddy on dorsal side and brownish yellow on ventral side. The seal disappeared after about one hour stray in the harbor. On the next morning a fisherman found the seal occurred in the Chikura harbor at nine in the morning. I
visited Chikura harbor as quickly as possible, however, the seal was already outof the harbor before my arrival. According to the fisherman's information on
the body size and color, it was supposed that this seal was the same as I saw theday before. Following informations on the seal were brought from Kisarazu andthen from Funabashi in a few days. Therefore, the wandering way of this seal
was recorded as shown in Fig. 1 and in Table l. However, after sighting at Funabashi, the seal was missed and no information was received.
According to Naito (1976), 16 examples of seal wandering were recorded along
the coast of Japan (except Hokkaido) since 1949, and only two out of 16 examples
were the bearded seals. One was recorded at Tennou-cho Akita Prefecture(39°53'N, 139°57'£) and the other was at Niigata City (38°13'N, 139°24'£). Bothwere recorded at Japan Sea coast. Therefore, this is the first time for the recordof the bearded seal wandering along the Pacific coast of Japan. Futhermore, thisobservation (Chikura; 34°37'N, 139°58'£) seems to be confirmed as the most far
south record in the western North Pacific. However, according to Wang ZheMao(personal communication), one specimen of this species was collected in China.
Therefore, being still uncertain where it was collected in China, this collection
may be the most far south record. Since the seal was observed at four locations
during its wandering as mentioned above, the wandering speed was roughly esSci. Rep. Whales Res. Inst.,
No. 31, 1979, 121-123

122

NAITO
140°E
Funabashi
0N

TOKYO BAY
/.•

/
/

/

/
/

I
I
I

BOSO PENINSULA

kl

I
I
I
I

I

I
I

I

I
I
I
I
I

35°N

I
\

35°N

I

\
~

''

______ .....
' '':>..-~..;-PACIFIC OCEAN
10

20

30km

140°E

Fig. 1. The bearded seal first appeared at Amatsu and was successfully tracked
at Chikura, Kisarazu and Funabashi.

timated. The minimum distance between each location, time lag of occurrencesin each location, and the calculated wandering speed are shown in Table 2. The
wandering speed between Amatsu and Chikura, and between Chikura and Kisarazu are almost the same, however, between Kisarazu and Funabashi it took about
three times longer than that of the former. This difference in the wandering speed
may be resulted from the undesirable environmental condition that may caused
the unsmooth wandering between Kisarazu and Funabashi e.g. the artificiallycomplicated channels, dirty waters, numerous numbers of ships and a lot of piers.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

WANDERING OF THE BEARED SEAL

123

TABLE I. THE OBSERVED LOCALITY AND TIME OF APPEARANCE AND
DISAPPEARANCE WHILE THE BEARDED SEAL WONDERED
AROUND THE BOSO PENINSULA IN 1977
Locality

Date

Time

AmatsuChikuraKisarazu
Funabashi

6 September
7 September
9 September
13 September

16: 00-18: 00
9:00-11:00
16: 00-18: 00
13: 00TABLE 2. MINIMUM DISTANCE BETWEEN EACH LOCATION AND TIMESPENT TO REACH EACH LOCATION WERE CALCULATEDTO INDUCE THE WONDERING SPEED
Location

Minimum
distance

Wonderinghours

Wonderingspeed

Amatsu-Chikura
Chikura-Kisarazu
Kisarazu-Funabashi
Amatsu-Funabashi (total)

26.1 km
79.1
36.9
14:U

16 hours
53
91
160

1.63 kmjhr
1.49
0.41
0.88

On the other hand, the areas between Amatsu and Chikura, and between Chikura
and Kisarazu are all or partly facing to the Pacific Ocean, and it seems to be clean
enough for the seal to make smooth wandering. Therefore, it may be possible topresume that the minimum distance was followed between Amatsu and Kisarazu
which is 105.2 km, and the average speed was 1.52 km per hour. This average
speed is comparable to neither the swimming speed nor the migration speed, but
as a whole it means the minimum moving speed during wandering. The seal may
not swim directly on the minimum distance route but may stray here and there
during locomotion from location to location. Futhermore the seal may take restoccasionally. Therefore, it is likely that normal swimming speed itself may be
several times faster than the wandering speed.
In this study, I was very much indebted to the staff of the Kamogawa Sea
World to pursue the seal. They kindly provided me the informations I needed.
REFERENCERICHARDSON, D. T., 1975. Hooded seal whelps at South Brocksville, Maine. J. Mamm., 56 (2): 698-699.
KING, J.E., 1975. Leopared seals on Lord Howe Island. J. Mamm., 56 (1): 251-252.
NAITO, Y., 1976. The occurrence of the phocid seals along the coast of Japan and possible dispersal of pups.
Sci. Rep. Whales Res. Inst., 28: 175-185.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

METALS AND ORGANOCHLORINE COMPOUNDS IN THE
MUSCLE OF DU GONG FROM SULAWESI ISLANDNOBUYUKI MIYAZAKI
National Science Museum, TokyoKAZUOMI ITANO, MINORU FUKUSHIMA, SHIN-ICHIRO KAWAIThe Osaka Ciry Institute of Public Health and Environmental Sciences, OsakaAND
KATSUHISA HONDA
Ehime Universiry, Matsuyama

ABSTRACTThe muscle of two dugongs from Sulawesi Island were analyzed of metals
and organochlorine compounds. Total mercury in the adult female was
0.005 ppm and 0.002 ppm in the immature female. The ratio of total mercury to the selenium was higher in the older individual. Metal concentrations, except for arsenic, were higher in the adult female. PCB, DDT and
BHC were not detected in both dugongs. Concentrations of mercury andorganochlorine compounds in the dugong were compared with those of othermarine mammals.
INTRODUCTION

In recent years the presence of significant concentration of metals and organochlorine compounds has been reported in seals and dolphins which are high-ordercarnivores. As the dugong, Dugong dugon (Muller), are hervivorous, comparison of
metals and organochlorine residues in the dugong with those in other marine
mammals appears to throw some light on concentrations through the food chain.
On this problem very few study has been made chiefly due to difficulty of collecting
the fresh samples. Present study was undertaken to investigate the accumulationof metals and organochlorine compounds in the muscle of dugong, and to compare
the data with those of other marine mammals.
MATERIALS AND METHODS

The muscle samples analyzed here were obtained from two dugongs caught in1975 in Laikang Bay, Sulawesi Island and preserved for the Okinawa Exposition.
These animals were kept alive for about 20 days at the Exposition. The biological informations of two individuals are shown in Table 1 and age of them is citedfrom Kasuya and Nishiwaki (1978), who made age determination of dugongs basing
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 125-128

MIYAZAKI, ET AL.

126

on the dentinal growth layers in the larger tusk. Samples (about 2 kilogram per
individual) were kept frozen to about -20°C after death until the analyses in 1979.
In order to protect against dryness they were glazed twice during cold storage by
Dr T. Kasuya. All substance data described here were expressed in wet weightbasis.
Mercury: Total mercury was determined directly by a semiautomated flamelessatomic absorption spectrophotometer (Itano et al., 1977).
1Uethylmercury: Methylmercury was analyzed by the gas chromatographic
method based on the procedure of West06 (1967).
TABLE 1.

LIST OF MATERIALSSpecimenNo.

Captured
Date

Captured
Place

Death
Date

Death
Place

Sex

Body
Length(cm)

MaturityAge*

RRMOOl
RRM00225 July, '75
26 Aug. '75

Sulawesi Is.
Sulawesi Is.

20 Oct. '75
21 Oct. '75

Okinawa
Okinawa

FemaleFemale

254
204

Adult
Immature18
7* cited from Kasuya and Nishiwaki (1978).

Arsenic, selenium and other metals: Arsenic, selenium and other metals were determined using silver diethyldithiocarbamate method, a fluorometric spectrophotometer (Itano et al., 1977) and an atomic absorption spectrometer, respectively.
Organochlorine compounds: Muscle was ground with anhydrous sodium sulfate,and extracted by blending with n-hexane. The extracted fat was removed byflorisil dry column method. Then the sample was cleaned up by silicagel column
chromatography and determined by GC-ECD.
TABLE 2.

CONCENTRATIONS OF TOTAL MERCURY, METHYLMERCURY
AND SELENIUM IN THE MUSCLE OF DUGONGS

SpecimenNo.

Total mercury
ppm

Methylmercury
ppm

Seleniumppm

Total mercury

RRMOOl
RRM002

0.005
0.002

0.004
ND

0.087
0.074

0.057
0.027

Selenium

The tissue weights used for the determination of total mercury, methylmercury and selenium were
0.2 g, 10 g and 3 g, respectively.

RESULTS AND DISCUSSION

Concentrations of total mercury, methylmercury and selenium m the muscle oftwo dugongs are shown in Table 2. This Table indicates that total mercury concentrations in the adult female (RRMOOl) was 2.5 times as much as that in the immature female (RRM002). As the values of total mercury in dugongs were rather
close to 0.001 ppm of the detectable limit of this method, these data might be notadequate for a strict analysis. However, it can be definitely said that contamination by mercury in the dugong is lower than that of grey, harbour, hood and harp
seals (Sergeant and Armstrong 1973), harbour porpoise (Gaskin et al., 1972), striped
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

POLLUTANTS IN DUGONG

127

dolphin, spotted dolphin, short-finned pilot whale, bottlenose dolphin and finless
porpoise (Arima and Nagakura 1979). Concentration of methylmercury of theadult individual was 0.004ppm and that of the immature was lower than 0.001 ppmof the detectable limit of this method. Ratio of total mercury to selenium in twodugongs was conspicuously lower than that in the ringed seal (Kari and Kauranen1978), striped dolphin, spotted dolphin, short-finned pilot whale, bottlenose dolphin
and finless porpoise (Arima and Nagakura 1979).
Concentrations of nine metals are shown in Table 3. Metal concentration,
except for arsenic, were higher in the older individual. On the contrary arsenic
showed higher concentration in the immature individual. Denton (personal communication) also obtained the similar result on the North Queensland dugong
whose tissue concentrations of metals varied with the age.
TABLE 3.

METAL CONCENTRATIONS IN THE MUSCLE OF DUGONGS IN PPM

Specimen
No.

Fe

Mn

Zn

Cu

Pb

Ni

Co

Cd

As

RRMOOl
RRM002

32.0
18.0

0.094
0.031

29.5
14.8

0.97
0.74

0.25
0.20

1.25
0.55

0.043
0.040

0.120
0.031

0.015
0.050

The tissue weights used for the determination of arsenic and the other elements were 20 g and 10 g,
respectively.

Fat contents in the muscle of the adult female and the immature were 0.084%
and 0.065%, respectively. These were remarkably lower than those of harbour
seal, ranging 0.45 to 5.80% (Gaskin et al., 1973). Since the organochlorine compounds are expected to be most concentrated in the fat of animal tissues, fat was
extracted from a large amount of muscle (240 g) for the analyses. However,
PCB, DDT and BHC were not detected. The detectable limits of PCB, a-BHC,,8-BHC, r-BHC, p, P'-DDE, p, P'-DDD and p, P'-DDT were 0.001, 0.0005, 0.001,
0.001, 0.0001, 0.001 and 0.001 ppm, respectively. The concentration of organochlorine compounds in the dugong might be extremely lower than in harbour
seal (Gaskin et al., 1973). Heinsohn and Brich (1972) reported that stomach contents of dugongs were almost exclusively sea grasses and no animal matter was
found. Marine mammals accumulate various pollutants from their environment
mostly through food unlike fihes which concentrate pollutants through both foodand water. Therefore it is concluded that the difference in contamination by
mercury and organochlorine compounds between dugongs and other marine carnivorous mammals is mainly due to the difference of their food.
ACKNOWLEDGMENTS

The present specimens were collected by Dr T. Kasuya of Ocean Research Institute of Tokyo University through the cooperation of the Okinawa Aquarium of
the Okinawa Ocean Exposition and Professor M. Nishiwaki of University of the
Ryukyus. Professors M. Nishiwaki and T. Fujiyama of University of Ryukyus,
and Professor R. Tatsukawa of Ehime University are acknowledged for their kind
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

128

MIYAZAKI, ET AL.

help through this work. Our sincere thanks are due to Dr T. Kasuya for his kindreading and criticizing the draft. We also thank to Dr G. Denton of James Cook
University for his permission to refer the abstract from his major paper which has
been submitted to Marine Biology for publication.
REFERENCESARIMA, S. and K. NAGAKURA, 1979. Mercury and selenium content of Odontoceti. Bul~. Japan Soc. Sci.
Fish. 45 (5): 623--626.
GASKIN, D. E., K. lsHIDA and R. FRANK, 1972. Mercury in harbour porpoises (Phocoena phocoena) from the
Bay of Fundy Region. J. Fish. Res. Board Can., 29: 1644-1646.
GASKIN, D. E., R. FRANK, M. NoLDRINET, K. lsHIDA, C.J. WALTON and M. SMITH, 1973. Mercury, DDT
and PCB in harbour seals (Plwca vitulina) from the Bay of Fundy and Gulf of Maine. J. Fish. Res. Board
Can., 30: 471-475.
HEINSOH, G. E. and W.R. BRicH, 1972. Foods and feeding habits of the dugong Dugong dugon (Erxleben),in northern Queensland, Australia. 1Vfammalia, 36 : 414-422.
lTANO, K., K. SASAKI, K. OKAMURA and R. TATSUKAWA, 1977. Selenium and mercury in marine organisms(1). Distribution of selenium and mercury in the tissues of marine fish. J. Food Hyg. Soc. Japan, 18:547-552.
KARI, T. and P. KAURANEN, 1978. Mercury and selenium contents of seals from fresh and brackish waterin Finland. Bull. Environ. Contam. Toxicol., 76: 273-280.
KAsUYA, T. and M. NrsmWAKr, 1978. On the age characteristics and anatomy of the tusk of Dugong dugon.
Sci. Rep. Whales Res. Inst., 30: 301-311.
SERGEANT, D. E. and F. A. ARMSTRONG, 1973. Mercury in seals from Eastern Canada. J. Fish. Res. Board
Can., 30: 843-846.
WESTOO, G., 1967. Determination of methylmercury compounds in foodstuffs. Acta Chem. Scand., 21:
1790-1800.

Sci. Rep. Whales Res. Inst.,

No. 31, 1979

ORGAN WEIGHTS OF DUGONG DUGONTOSHIRO KAMIYA
Department of Anatomy, Faculty of Medicine, University of Tokyo, TokyoSENZO UCHIDA
Okinawa Expo Memorial Park Aquarium, Motobu, Okinawa

AND
TERUO KATAOKA
Toba Aquarium, Toba, Mie

When the International Ocean Exposition (1975) took place in Okinawa, two dugongs (Dugong dugon) were donated from Indonesian Government to Japanese
Government, but these died within a short period of 22 and 23 days after arrival.
With the permission of Philippine Government, three more dugongs were subsequently imported to Japan until recently and attempts were made to maintainthem. While two of these dugongs died, the remaining one still remains healthy in
Toba Aquarium, after two years record history of maintenance in May 1979, daily
renewing the record of maintenance of dugong in Ja pan. Apart from these, adugong cadaver was brought to Ja pan from Philippine for scientific studies. In
January 1979, moreover, a female infant dugong was caught by a fishing net in
the suburbs of Nago, Okinawa (26°32'N, 128°07'E) and an attempt was made tomaintain it, but death occurred 33 days later.
TABLE I. BODY AND INTESTINE LENGTHS AND THEIRRATIOS IN SIX SPECIMENS OF DUGONG DUGONSpecimennumberBody
length(m)

Smallintestine
(m)

Large
intestine
(m)

Ratio

D-1
D-2
D-3
D-4
D-5
D-6

1.38
1.55
1.58
1.69
2.04
2.54

5.40
5.85
7.30
6.66
7 .13
9.60

8.80
7.45
12.46
12.70
12.25
14.50

10.3
8.6
12.5
11.5
9.5
9.5

We have conducted a biological survey and investigation on the cause of deathin these six animals. In the present paper, the organ weights in these six dugongs
and the ratio of each value to body weight was summarized in Table 2. Most of
the organs were weighed fresh at autopsy, but some of them were weighed after
fixation in 10% formalin solution.
In addition, the length of the intestine (Table 1), and the photographs of
external appearance of main organs (Pl. I-IV) were given. The body length was
Sci. Rep. Whales Res. Inst.,
No. 31, 1979, 129-132

130

KAMIYA, UCHIDA AND KATAOKATABLE 2.
Specimen number
Body length
Sex
Body weight (at autopsy)
Body weight (at capture)
Locality
Brain
Spinal cordHeart
SpleenLung
StomachSmall intestine
Large intestine
Liver
Pancreas
Parotis

BODY LENGTH, BODY WEIGHT AND ORGAN

D-1
135.0cm
M
47.0kgD-2
155.0cm
M
52.2kgPhilippines(Luzon Isl.)

Philippines(Luzon Isl.)

160.0g (0.340)
107.0(0. 228)} 625.0(1.330)

675.0
18.0
50.0
55.0

(l .436)(0.038)(0.106)(0.117)

KidneyAdrenal160.0g (0.306)
9.0 (0. 0172)
425.0 (0.814)
495.0 (0 .948)

755.0
16.0

(1. 466)(0 .0306)

150.0
150.0
1.0
0.8

(0. 287)(0.287)(0.00191)(0.00153)

Thyroid
Thymus
Pituitary
TestisEpididymis

0.6* (0.000127)
3 . O* (0. 00638)
2. O* (0. 00426)

Ovary
Integument=(Blubber)

13,000.0 (27 .66)

* calculated from the value after preservation in 10% formalin solution.
Figures in parentheses indicate percentages of body weight.
defined as the length from the tip of the head to the tail base. The body weight
was recorded at the time of death. Since body weight undergone a considerable
variation according to the condition of maintenance, the body weight at the timeof capture was also described together. The detailed anatomical findings of theseinternal organs currently under investigation will be reported elsewhere in a morphological research journal.
ACKNOWLEDGMENTS

vVe wish to express our thanks to the Directors and staffs of the Kamogawa Sea
Sci. Rep. Whales Res. Inst.,
No. 31, 1.979

ORGAN WEIGHT OF DUGONG

131

WEIGHT OF SIX SPECIMENS OF DUGONG DUGON
D-3
158.5 cmF
76.5 kg

D-4
169.7cmM
80. l kg
Philippines(Luzon Is!.)

D-5
204.0 cmF
120.5 kg
155 .0 kg
Indonesia(Sulawesi Is!.)D-6
254.0 cmF
220.5kg
262.0kg
Indonesia(Sulawesi Is!.)

Okinawa
218. 0 g (0. 286)
40.0 (0.0528)

225.0 g (0. 280)

250. 0 g (0. 207)

250.0 g (0.113)

19.0(0.0362)29.0(0.0362)910.0
1,440.0
1,900.0
1,125.0
45.0(l .194)(l.889)(2.493)(I. 476)(0. 0591)

1, 780.0
40.0(2. 222)(0.0499)

263.0
260.0
I. 7
1.5
7.0

(0 .328)(0. 324)(0.00212)(0.00187)(0.00873)

25.5
45.5
49.0
0.6

(0.0335)(0.0597)(0.0643)(0.000787)

2.1(0.00262)

I. 2(0.00149)

265.0
18.0
900.0
950.0
l,950.01,800.02,600.0
1,650.0
50.0(0. 220)(0.015)(0. 747)(0. 788)(1.618)(l .494)(2.158)(I. 369)(0.041)500.0
28.0
1,650.01.450.0
4,250.0
4,000.0
4,450.0
3,150.0
45.0(0.227)(0.0127)(0. 748)(0.658)(l .927)(l .814)(2.018)(l .429)(0.0204)

350.0
320.0

(0. 290)(0.266)11.5(0.0095)

600.0
500.0
3.5
3.4
16.0

(0.272)(0.227)(0.00159)(0.00154)(0.00726)

0.9(0 .00075)

0.9(0.000408)

12.0* (0.00544)
18,600.0 (24.41)

World, Toba Aquarium, Okinawa Marine Park Centre and Sunshine International
Aquarium for giving chance for material examination and to Prof. M. Nishiwaki
of University of the Ryukyus for his valuable advice.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

132

KAMIYA, UCHIDA AND KATAOKAEXPLANATION OF PLATESPLATE I
Fig. 1. Ventral dissection of the thracoabdominal viscera. Female, 204 cm length.
D: duodenal diverticulum G: gallbladder H: heart S: stomach
Fig. 2. Ventral aspect of the thoracic viscera. Male, 158.5 cm length. Arrowshows the left superior vena cava. A: arch of the aorta.
Fig. 3. Hemisection of heart of a 254 cm length, female. The deep interventricular sulcus is indicated by the arrow.
PLATE II
Fig. l. Stomach and proximal duodenum. Female, 204 cm length. Cg: cardiac
gland DI: left duodenal diverticulum Dr: right duodenal diverticulum 0:
oesophagus
Fig. 2. Visceral aspect of the liver. Female, 204 cm length. R: right lobe G:
gallbladderFig. 3. Ventral aspect of intact pancreas. Male, 169. 7 cm length. C: cauda ofpancreas
Fig. 4. Digestive tract. Female, 158.5 cm length. C: cecum D: duodenal
diverticulum I: small intestine K: kidney L: liver LI: large intestine S:
stomachFig. 5. Dorsal aspect of the spleen. Female, 204 cm length.
PLATE III
Fig. !. Ventral aspect of the right kidney. Female, 204 cm length. U: ureter
Fig. 2. Posterior view of the male reproductive tract and urinary bladder of a
135 cm length. B: urinary bladder E: epididymis S: seminal vesicle T:
testis U : ureter
Fig. 3. Ventral aspect of the adrenal gland. Male, 155 cm length.
Fig. 4. Visceral aspect of the right ovary of 254 cm length. The ovarian follicle
indicated by the arrow.
Fig. 5. Ventral aspect of the pituitary gland. Female, 204 cm length. X 5.5
PLATE IV
Fig. 1. Dorsal aspect of the brain.
Female, 254 cm length.
Fig. 2. Lateral aspect of the brain. Female, 254 cm length.
Fig. 3. Ventral aspect of the brain. Female, 254 cm length.
Fig. 4. Dorsal aspect of the spinal cord. Male, 135 cm length. C 1 ~Th 3 (left)
and Th4 -Th8 (right).
Fig. 5. Dorsal aspect of the spinal cord. Male, 135 cm length. Th 9 -Th13 (left),
Th14 -Th18 (middle) and Th19 -L 4 (right).

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

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PRESENT DISTRIBUTION OF THE DUGONGIN THE WORLDMASAHARU NISHIWAKI
University of the Ryukyus, Naha, Okinawa

TOSHIO KASUYA
Ocean Research Institute, University ef Tokyo, TokyoNOBUYUKI MIYAZAKI
National Science Museum, TokyoTERVO TOBAYAMA
Kamogawa Sea World, Kamogawa, Chiba

AND
TERVO KATAOKA
Toba Aquarium, Toba, Mie

ABSTRACTThis is a result of hearing surveys on dugong distribution in the past 10
years. The species is distributed widely in the Indo-Pacific Ocean, between
the longitude of 30°E and l 70°E, and between the latitude of 30°N and 30°S.
Although nothing is known on movement and seasonal migration of thespecies, discontinuity of distribution or of density suggests the presence of atleast five populations. They are (1) east Australian and east Papua New
Guinean group, (2) west Australia-Molucca-Philippine group, (3) SumaturaMalaysia-Andaman group, (4) Indo-Sri Lanka group and (5) east Africanand Madagascar group. Their range might have been continuous before
depletion by human activities, and the first three populations may still be
continuous dispersely. The forth and fifth group seems to be on the vergeof extinction. The total population of 30,000 individuals is roughly presumed
by Nishiwaki.

INTRODUCTION

Since the Human Environment Conference of the United Nations held at
Stockholm in 1972, conservation of marine mammals has been called loudly.
Particularly calls were concentrated on cetaceans. Then conservation on sirenians
followed as a matter of concern. Studies on the dugong and the species of manatees have progressed at the same time (Bertram, 1976).
The first step needed for conservation is to clarify the habitat, range of disSci. Rep. Whales Res. Inst.,
No. 31, 1979, 133-141

134

NISHIWAKI ET AL.

tribution, and abundance. The present study will throw a light on the actual
status of the distribution of Dugong dugon (Muller 1776) in the world.
HEARING SURVEY OVER THE INDO-PACIFIC REGION

Method and area covered
The data are collected from the information through the two expeditions to
the Indo-Pacific region in 1977 and 1978, and of that collected by some of theauthors individually in recent 10 years.
In 1977, Nishiwaki and Tobayama travelled to Indonesia, Sri Lanka, south
India, Kenya, Tanzania, and Madagascar including the Comoro Islands. And in
1978, Nishiwaki, Kasuya, Miyazaki, and Kataoka surveyed Micronesia, Melanesia,
Fiji, Indonesia, and Australia. The latter put stress on to know the eastern limitof distribution. Information was collected from local scientists, fishermen andother people who were expected to know the species. Our inquiry consisted ofthree questions by showing three photographs of dugong. They were, 1: "Haveyou ever seen or heard of the animals in this area? ", if answer was " Yes ",2: " Where and when did you do it", and " How many? ", and 3: " Do you
think dugongs are still there? ". If possible, our effort was made to confirm thefragments of skeleton, record in market, or hunting instruments. Palau Islands
was not surveyed in the trip, because existence of dugong on the islands was known
since long time before (Asano, 1935; Hirasaka, 1933; R. L. Brownell Jr, pers.
comm.) and Nishiwaki investigated the islands in 1973 and 1974. In all throughthe surveys, our best effort was made to eliminate the confusion of other marine
animals with dugong.
Result of hearing survey
The information of the dugong distribution obtained in the present study is
as follows.
(I) Absence of dugong was concluded on: Johnston I., Saipan, Caroline Islands(Truk Is., Ponape I., Ulithi Atoll, Ngulu Atoll, Nama I., Lukunor Atoll,
Satawan Atoll), Marshall Islands (Majuro Atoll, Kusaie I.), Gilbert Islands,
Nauru Island, Ellice Islands, Fiji, Surabaja (Java), Borneo (northern andeastern coast), Chon Buri (Bangkok Bay), Chittagong, Dacca, Khulna, Calcutta, Madras, Karachi, Bahrain, Seychelles.
(2) Constant distribution was proven on: Palau Islands, Solomon Islands,
New Hebrides, New Caledonia, Papua New Guinea (Lae, Port Moresby),Townsville, Thursday Island, Friday Island, Mulgrave Island, Philippines(Manila, Palawan, Iloilo, Cebu, Tacloban, Polillo Is., Zamboanga), Borneo(west coast), Sulawesi, Bali, Java (Denpasar, Banjuwangi, Serang), Bangka
Island, east coast of Malay Peninsula (Songkhla, Surat Thani), west coast of
Malay Peninsula (Pinang, Phuket ), Rangoon, Ramree Island, Sri Lanka(Colombo, Jaffna), Adams Bridge, Trivandrum, Calicut, Bombay, Madagascar (Tananarive, Nossi-Be I., Majunga), Comoro Islands, Dar-es-Salaam,
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

PRESENT DISTRIBUTIOI'\ OF THE DUGONG

135

Mombassa, Zanzibar, Juddah
Places of rare occurences or of doubtful information taken:(a) On Guam Island, we met five fishermen or sport divers. A friend of
one of the divers, who was also a sport diver, told his encounter underwater an animal looks like a sea lion. The sea lion is not distributed in theisland. Another information was obtained from a fisherman. He told that
he had observed, from a boat, a large animal submerged under water near
the southern tip of Guam Island. In the next day he found a long grazing
traces in the sea grass at that position. Though the two information may
possiblly be a dugong, we consider that further confirmation is necessary
before its conclusion.
(b) Among 20 people we met at Yap Island in 1978, only 9 persons knew
the dugong. One dugong was captured by a turtle hunter about 15 years
ago, and the animal was sold at the market. This information was confirmed
individually by eight persons including the hunter and a manager of themarket. Another invididual was sighted in 1977 while staying at the bottom
by the turtle hunter who witnessed the previous catch at the market. The
information suggests that the species occurs in Yap coast very seldom.
The above information are summerized in Fig. 1, together with various pastrecords of the species. Among the descriptions on dugong distribution ever published, that of Husar (1975) is closest to the present result. The important clifferences are as follows.
In her map, this species occurs in Marshall Is., Gilbert Is., and Ellice Is.
Only one doubtfully supported it was a steward of a hotel at Majuro Island.
He told us that he had seen an animal looked like dugong in Maloelap Island.
However no other information in this region agreed the presence of the species, andwe concluded that the species does not inhabit the islands. This conclusion fit
to the opinion of Mr B. Puleloa, a District Fisheries Officer of Marshall Islands.
The distribution of the species in Micronesia seems to be limited geographically.
All information obtained by us certainly deny the distribution of the species in
Micronesia except Palau, Yap and Guam Is., and constant inhabitation was onlyin the Palau Islands.
Dugong does not seem to be distributed in the Laccadive and Maldive Islands(S. Jones, pers. comm.). Though our survey denyed the presence of the dugong
at Bahrain, it was recently documented by Gallagher (1976).
Although there has been no study on the diving depth of dugongs, they do
not seem to dive so deep as cetaceans do. It may be safe to say that dugongs
inhabit the waters not far from shore, namely limited usually within the depthof about 20 meters, however, they will be able to stray or to migrate across theopen sea. Distribution of the dugong is parallel to that of the sea grasses, genera<,ostera, Cymodocea, Thalassia, or Thlassodendron (Heinsohn et al., 1977), though thesegrasses do not always invite dugongs. At Ponape and Truk Islands in Micronesia,
there are abundant sea grasses but people said without exception that they had
never seen dugong there. Another example is in the southern districts of Japan(3)

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

i\ISHIWAKI ET AL.

136

40°E

60°E

80°E

100°E

ASIA

20°N

AFRICA
oo

Cocos

OCEAN

2o·s

Amsterdam()
I·St. Paul4o·s-wT~~~~-~-t--~~~~~~-+--~~~~~~__L_~~~~~~-+--

40°E
Fig. l.

'

60°E

so·E

l00°E

A map indicating the present distribution of the dugong (Dugong dugon) in the world.

Sci. Rep. Whales Res. Inst.,
No. 31, 1979

PRESEiNT DISTRIB UTIOl\" OF THE DUGONG

100°E

120°E

140°E

137

160°E I--+---.~ 40'N

China

20'N

....
Nauru

o·

Chri~trnas

20'5

AUSTRALIA
S0 UTH

~)=
140°E
120'E
. route only.
·lOO'Er connectmg~rare 0=scarce,~lll!lill abundant, ~Sci. Rep. Whales Res. Inst.,
No. 31, 1979

·Norfolk

PlCIFIC
OCEAN

138

NISHIWAKI ET AL.

proper. There are abundant Z,ostera spp. to form a good shelter for various fishes,
but no dugong has ever been found in the waters north of 30°N.
Another factor influences the dugong distribution may be the water temperature. The northern limit of the species is at Amami Oshima Islands in thesouthern Japan or at the latitude of about 29°N. These range nearly coincides with the mean surface water temperature of 23°C. The dugong seems to
be sedentary and may not make long seasonal migration affected by the seasonalchange of the water temperature. Accordingly, if there is any record of the occurrence of the dugong in the waters below the above mentioned temperature, weshall investigate most carefully whether or not the animal belongs to species ofcetacean genera Orcaella or Neophocaena. In March 1979, an animal belonging to
the latter genus was misidentified by local people in western Kyushu as a deaddugong.
The third factor influences dugong distribution may be the ocean current.
In the wide area of Micronesia, the Palau Islands situated at the western part, isthe only place of constant dugong inhabitation. Though, as mentioned above,
Ponape and Truk Islands can be a good habitat of the dugong, there is no evidenceof dugong distribution. The North Equatorial Current may be a reason of this
distribution pattern. If there found some strayed individuals migrating from
Melanesia to Micronesia in the north, they were drifted to the west by the current
and eventually, unable to reach to central or eastern Micronesia, but arrived at
Palau or other nearby islands. This hypothesis suggests that the dugong population in Palau Islands recruited from the population of Melanesia and Papua
New Guinea.

Discreteness ef the populations
Little have been known about the discreteness of the dugong population.
Following is a tentative separation of populations based on geographical differencesin density or hiatus of distribution. It is reasonable to consider that there aresmaller local breeding units in each population as it is already indicated in thepresence of geographical differences in growth rate observed between the populations on the eastern and northern coasts of Australia (Marsh, in press).
Population 1 seems to be distributed widely and densely along the east coastof Australia from about 30°S to Papua New Guinea. It ranges from west of
l 70°E, and includes the islands of Melanesia, Solomon Is., New Hebrides and
New Caledonia. The southern limit of distribution is at Moreton Bay on the east
coast of Australia, or at about 30°S. The western boundary of this population,
may presumably be at around l 40°E.
Population 2 is considered to range from northwest coast of Australia to
Amami Oshima at 29°N which is the northern limit in the Pacific, through west
coast of Papua New Guinea and the Philippines. The boundary between the
populations 1 and 2, especially on the northern coast of Australia, is not distinct.
They are possibly of one continued population.
Population 3 is distributed from the west coast of Borneo and west Java to
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

PRESENT DISTRIBUTION OF THE DUGO~G139

the both coasts of Malay Peninsula, and from the northern coast of Sumatra Island
to the Nicobar and the Andaman Islands, and as north as to Ramree Island.
There is no distribution of the species in the Bangkok Bay, which may possibly
be related to the muddy bottom and poor sea grass. However the occasional
catch along the coast of the Gulf of Thailand was reported by Thiemmedh (1961 ).
Although the distribution along the coast of Cambodia and Viet Nam is unknown,
we have heard that some marine mammals were in the lagoon of Cotin China(Viet Name and Cambodia). Presumably they were Neophocaena or Orcaella.
Further investigation in the area is desirable. This population is separated from
population 2 by a dispersed distribution area near Borneo and Java or along thelongitude of l l0°E (Nishiwaki, 1977).
Population 4 ranges from Sri Lanka to the northwest coast of India. The
boundary between populations 3 and 4 may be along the longitude of 90°E. This
population seems to have had wider distribution in the past, but is apparently
decreasing (Bertram and Bertram, 1970; Jones, 1976).
Population 5 ranges from the Red Sea (Gohar, 1957), through east coast of
Africa, and Madagascar, to Mauritius. Though dugongs were abundant in formerdays in the area, they have decreased drastically through the long history of hunting(Gallagher, 1976; Bertram pers. comm., 1979). It was heard that there had been
few recent sightings along the coasts of Kenya, Tanzania and the northwest Madagascar (Ligon, 1976), and hunting seems to be still continued. At the Seychelles
Islands, a scientist said that there had been some dugongs at the Praslin Islands
group in the past but there is no sighting now. At Mauritius, they told us that they
seldom saw dugongs. It was told that the species was most abundant, among theeast African and Madagascar region, at the Comoro Islands. In the Museum of
Tananarive, there was a series of whole skeletons of the dugong collected at thenorthwest coast of Madagascar. The western limit of the distribution is at thenorthern part of Red Sea and the northern limit is in the Indian Ocean region is
also there.

A presumption on abundance
Following comment on the population abundance was made by M. Nishiwaki.
For conservation of marine mammals, it is necessary to study status of population as well as distribution of them. Because it is nearly impossible to countprecise number of marine mammals in the water, estimation of number of animals
has to be done based on biological knowledge and statistical records of animal
catch. Nishiwaki heard that about 500 animals are killed annually in Torres Strait
and York Peninsula area, but there is no statistical record, only scarce data havebeen collected from the remains of dugong carcasses. In many places protection
laws on paper spread, but local people continue to catch dugongs secretly. Secretcatch can do nothing for collection of data.
Heinsohn et al. (1976), Heinsohn (1978), and Ligon (1976) reported about
their aerial countings but they have not published on the population number yet.
Some of the present authors were able to join in aerial survey by the thoughtful
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

140

NISHIWAKI ET AL.

cooperation of Dr Heinsohn. We counted dugongs as ten individuals per hourfrom 900 feet altitude and speed of 100 miles per hour at Halifax Bay area.
Though data was scarce and accumulation of experiences were little, Nishiwaki
dared to make rough presumption over the five populations. His presumption ismerely a milestone to future estimations, but he would like to invite opinions andcorrections on this presumtion. He estimates the number of dugongs as 5,000
in the east coast of Australia, 6,000 for the Torres Strait and York Peninsula area,and 7,000 in Melanesia. This lead to the total of 18,000 in population 1.
Number of dogongs in population 2 is 4,000 in the southern latitude area and 3,000in the northern latitude area. The population size will be about 2,500 in population 3, 1,000 in population 4, 1,000 in population 5 north of equator, and 500 in
the same population south of equator. The number of dugongs all over thelndo-Pacific region may be roughly 30,000 animals. populations 4 and 5 seemto be near to desperation.
It should be emphasized that the accumulation of statistical records of dugong
catch and biological knowledge on the species are fundamental matter for conservation of the dugong population.
ACKNOWLEDGMENTCountless number of scientists, fishermen and laymen helped us and offered theinformation to us during our travel around the coasts and islands of lndo-Pacificregion for hearing survey. vVe would like to mention some unforgettable names;
these people are Mr C. Raticliffe of Seychelles, Mr John Handley of Fiji, Mr Martin
Cristian of Ponape, Mr T. Johes of Honiala, Mrs Lymde Tranter of Tarawa, Mr
S. Mori of Dar-es-Salaan, Tanzania, and Mr Kazuo Uemura of Toshoku Ltd.,
Tananarive, Malagasy Republic.
Scientists with whom we met during our survey and exchanged opinions, or
those who helped us in collecting data were Mr Skiman Hendrokusumo and Mr
Tas' An of Jaya Ancol Oceanarium, Indonesia, Mr Chandima de Alwis of the
National Zoological Garden, Sri Lanka, Dr R. L. Brownell Jr of Smithsonian
Institution.
While Seminar Workshop on Dugong was held at James Cook University,
Townsville, Australia, we were able to meet many distinguished specialists on thedugong and learned latest and reliable knowledge. Especially, our gratitudes
are to Drs G. E. Heinsohn, Helen Marsh and David Blair ofJames Cook University,
Dr P. K. Anderson of University of Calgary, Canada, Mr Ephraim Bani of University of Queensland, Dr G.C.L. Bertram of St.John's College, U. K., Mr Murray
Elliott of Territory Parks and Wildlife Commission N. T., Mrs Bryget Hudsonof Wildlife Division, P.N.G., Drs S. Jones and E. G. Silas of the Central Marine
Fisheries Research Institute, India.
Our study was financially supported by the Grant of Overseas Scientific Survey
offered by the Ministry of Education.
Sci. Rep. Whales Res. Inst.,
No. 31, 1979

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THE SCIENTIFIC REPORTS OF THE WHALES RESEARCHINSTITUTE, TOKYO, JAPANNUMBER 1, JUNE 1948
Akiya, S. and S. Tejima. Studies on digestive enzyme in whale. 3-7
Akiya, S., Y. Ishikawa, S. Tejima, and T. Tanzawa. Studies on tryptase from a whale (Balaenoptera borealisL.). 8-10
Akiya, S., S. Tejima, and Y. Ishikawa. Studies on the utilization of whale meat by the use of pancreatic
tryptase of whales. 11-14
Akiya, S. and F. Kobo. 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 meat andbeef on deterioration of freshness and autolysis. 27-30
Tawara, T. On the simultaneous extraction of vitamin A-D and vitamin B2 complex from the liver of afin whale (Nagasu-Kujira, Balaenoptera physalus L.). 31-37
Tawara, T. Studies on whale blood. I. On the separation of histidine from whale blood. 38-40
Nakai,.J. and T. Shida. Sinus-hairs of the sei-whale (Balaenoptera borealis). 41-47

NUMBER 2, DECEMBER 1948
Ogawa, T. and S. Arifuku. On the acoustic system in the cetacean brains. 1-20
Yamada, M. Auditory organ of the whalebone whales. (Preliminary report). 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 2C0 2 • 31-34
Ishikawa, S., Y. Omote, and Y. Soma. Analytical distillation of vitamin A in the whale liver oil. 35-41
Ishikawa, S., Y. Omote, and H. Kanno. Molecular distillation of sperm whale blubber oil. 42-45
Kaneko, A. Molecular distillation of fin whale liver oil. 4&--50
Akiya, S. and K. Takahashi. Determination oftryptophane in whale meat. 51-54
Ishikawa, Y. and S. Tejima. 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 T. Shida. On the sensory tubercles oflips 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 cetacean larynx, with special remarks on the laryngeal sack of the sei whale andthe aryteno-epiglottideal tube of the sperm whale. 23-62
Akiba, T., T. Tsuchiya, M. Umehara, and Y. Natsume. 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 M. Saiki. Properties of.fats and oils contained in various parts of a sperm whale body. 7984
Tawara, T. and R. Fukazawa. Studies on kitol. I. Preparation ofkitol from whal~ liver oil. 85-ml
Tawara, T. and R. Fukazawa. Studies on kitol. II. Influence of kitol fraction on the determination of
the International Unit of Vitamin A. 89-91
Tawawa, T. and R. Fukazawa. Studies on kitol. III. The effect of sunlight, air and heat on the vitamin
A and kitol fractions. 92-95

ii
Tawara, T. On the respiratory pigments of whale (Studies on whale blood II.). 96-101
Yoshida, M. Research on methionine in whale. 102-105
Mizue, K. Factory ship whaling around Bonin Islands in 1948. 106-118
Mizue, K. and H. Jimbo. Statistic study of foetuses of whales. 119-131
Nishiwaki, M. and K. Hayashi. 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 ofJapan. 27-113
Nishiwaki, M. Determination of the age of Antarctic blue and fin whales by the colour changes in crystalline 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., M. Umehara and Y. Natsume. 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
Ohe, T. Iconography on the abdominal cavity and viscera of the Balaenoptera, with special remarks upon
the peritoneal coverings. 17-39
Akiya, S. and 0. Hoshino. Isolation of histidine from whale blood using 3,4-dichlorobenzene sulfonic acid.
41-47
Tawara, T. and R. Fukazawa. Studies on kitol. IV. Purification of kitol by chromatographic. 49-5 l
Ishikawa, S., Y. Omote and H. Okuda. Substances related to vitamin A in the whale liver oil. 53-59
Ishikawa, S., Y. Omote, M. Kijima and H. Okuda. Thermal decomposition ofkitol. 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 T. Ohe. Biological investigation on blue whales (Balaenoptera musculus) and fin whales(Balaenoptera p.11.)salus) 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 innervation andfunction of the musculus retractor bulbi. 1-33
Murata, T. Histological studies on the respiratory portions of the lungs of cetacea. 35-4 7
Kojima, T. On the brain of the sperm whale (Physeter catodon L.). 49-72
Mizue, K. and T. Murata. 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 T. Hibiya. On the sexual maturity of the sperm whales (Ph_yseter catodon) found in theadjacent 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 H. Ono. The effects of electric shock and fatigue on post-mortem changes in muscle. 177185

iii
Omote, Y. Complete recovery of vitamin A from molecular distillation residue of whale-liver oil. 187191
Omote, Y. Chemical structure ofkitol (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 those of Berardius bairdii
Stejneger. 1-22
Akiya, S., 0. Hoshino and N. Motohashi. On an attempt to preserve whale meat freshness with 5-nitrofurfuriden aminoguanidine from decay. 23-30
Akiya, S. and R. Sawamura. Colorimetric determination of 5-nitro-2-furfuridene aminoguanidine. 31-36
Tomiyama, S. and M. Takao. Studies on utilization of higher fatty alcohol from sperm whale oil. 37-46
Omote, Y. A rapid method for the separate determination of vitamin A and kitol in the whale-liver oil.
47-50
Arai, Y. and S. Sakai. Whale meat in nutrition. 51-67
Yamaguchi, K. and K. Fujino. On the serological constitution of striped dolphin (Prodelphinus caeruleoalbus(Meyen)) (I). 67-77
Nishimoto, S., M. Tozawa and T. Kawakami, Food ofsei 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 T. Hibiya. On the sexual maturity of the sperm whales (Physeter catodon) found in theadjacent waters of Japan (II). 121-124
Ohno, M. and K. Fujino. Biological investigation on the whales caught by the Japanese Antarctic whaling
fleets, season 1950/51. 125-183

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 T. Yagi. On the age and the growth of teeth in a dolphin (Prodelphinuscaeruleo-albus).
(I). 133-146
Kakuwa, Z., T. Kawakami and K. Iguchi. 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 (Prodelphinuscaeruleo-albus). 215-218

NUMBER 9, JUNE 1954
Akiya, S., 0. Hoshino and N. Motohashi. Attempt to preserve 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 ofa rare porpoise, Feresa Gray from Japan. 59-88
Omura, H. and K. Fujino. Sei whales in the adjacent waters of Japan. II. Further studies on the external
characters. 89-103
Fujino, K. On the serological constitution of the sperm- and Baird beaked-whales (I) Blood groups ofthe sperm- and Baird beaked-whales. 105-120

iv
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., T. Hibiya and S. Kimura. On the sexual maturity of the sei whale of the Bonin waters.
165-177
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 T. Nemoto. Sei whales in the adjacent waters of Japan. III. Relation between movement and water temperature of the sea. 79-87
Omura, H., K. Fujino and S. Kimura. Beaked whale Berardius bairdi of Japan, with notes of Z,iphiuscavirostris. 89-132
Fujino, K. On the body weight of the sei whales located in the adjacent waters ofJapan (II.) 133-141
Nishiwaki, M. On the sexual maturity of the Antarctic male sperm whale (Physeter catodon L.). 143-149
Ohta, K., T. Watarai, T. Oishi, Y. Ueshiba, S. Hirose, T. Yoshizawa, Y. Akikusa, M. Sato and K. Okano,Composition of fin whale milk. 151-167

NUMBER 11, JUNE 1956
Omura, H. and H. Sakiura. Studies on the little piked whale from the coast of Japan. 1-37
Nishiwaki, M., T. Hibiya and S. Kimura. On the sexual maturity of the sperm whale (Physeter catodon)
found in the North Pacific. 39-46
Fujino, K. On the body proportions of the sperm whales (P/>,yseter catodon). 47-83
Fujino, K. On the serological constitution of the fin whales II. Further studies on blood groups. 85-98
Nemoto, T. On the diatoms of the skin film of whales in the northern Pacific. 99-132
Hoshina, T. and Y. Sugiura. 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
I wai, E. Descriptions on unidentified species of dibranchiate cephalopods. II. A cranchiidae squid of thegenus Taonius. 153--161
Uda, M. and K. Nasu. Studies of the whaling grounds in the northern sea-region of the Pacific Ocean inrelation to the meteorological and oceanographic conditions. (Part I). 163-179
Kimura, S. and T. Nemoto. 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 the absorption 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 andthe Bering Sea in summer of 1955. 91-101
Kimura, S. The twinning in southern fin whales. 103--125
Ichihara, T. An application of linear discriminant function to external measurements of fin whale. 127189

v
Nishiwaki, M. Very small embryo of cetacea. 191-192
Nishiwaki, M. One-eyed monster of fin whale. 193-195
Ogawa, T. and T. Kamiya. A case of the cachalot with protruded rudimentary hind limbs. 197-208
Uda, M. and A. Dairokuno. 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 boundaryof 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 new 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 T. Kamiya. A beaked whale Mesoplodon stranded at Oiso Beach, Japan. 53-83
Nishiwaki, M. and C. Handa. Killer whales caught in the coastal waters off Japan for recent JO years.
85-96
Ohsumi, S. (Kimura), M. Nishiwaki and T. Hibiya. Growth of fin whale in the northern Pacific. 97133
Nishiwaki, M., T. Hibiya and S. Ohsumi (Kimura). Age study of sperm whale based on reading of
tooth laminations. 135-153
Nishiwaki, M., T. lchihara and S. Ohsumi (Kimura). Age studies of fin whale based on ear plug. 155169
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 K. Nasu. 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. 213-214
Uda, M. and N. Suzuki. 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 of theright whale. 253-267
Hosokawa, H. and T. Sekino. Comparison of the size of cells and some histological formations between
whales and man. 269-301
Ogawa, T., T. Tsunoda and M. Osawa. Amino acid composition of whale meat. 303-307
Ishikawa, Y. A characteristic property of whale oils concerning the absorption of gases. II. On the absorption 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 ofJapan. 1-33
Nishiwaki, M. and T. Kamiya. Mesoplodon stejenegeri from the coast ofJapan. 35-48
Nishiwaki, M. Humpback whales in Ryukyuan waters. 49-87
Cushing, John E., K. Fujino and K. Takahashi. Glycerol-freezing technique as an aid in blood typingof whales. 89-100

vi
Fujino, K. and John E. Cushing. Blood typing of dried whale erythrocytes with 1311 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 movements. 149-290
Yamada, M. and F. Yoshizaki. 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 ph_ysalus (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., M. Nishiwaki, T. lchihara and T. Kasuya. Osteological note of a sperm whale. 35-45
lchihara, 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 Mesoplodon. 79-82
Sinclair, John. An early dolphin embryo (Stenella caeruleoalbres) 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., S. Ohsumi and T. Maeda. Change of form in the sperm whale accompanied with growth.
1-14
Ohsumi, S., T. Kasuya and M. Nishiwaki. 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 T. Suzuki. 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., K. Fujino and N. Calaprice. The Ju blood typing system of the sperm whale and specificsoluble substances. 67-77
Nemoto, T. New records of sperm whales with protruded rudimentary hind limbs. 79-81
Nemoto, T. and K. Nasu. 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
Nasu, K. Oceanography and whaling ground in the subarctic region of the Pacific Ocean. 105-155

vii
Nemoto, T. Some aspects of the distribution of Ca/anus cristatus and C. plumchrus in the Bering and its neighbouring waters, with reference to the feeding of baleen whales. 157-170
Tsuyuki, H. and U. Naruse. Studies on the oil of black right whale in the northern Pacific Ocean. 171190
Yagi, T., M. Nishiwaki and M. Nakajima. A preliminary study on the method of time marking withleadsal t 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 badeen 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 U. Naruse. 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 T. Ichihara. Some informations on minke whales from the Antarctic. 37-43
Nemoto, T. and T. Kasuya. Foods of baleen whales in the Gulf of Alaska of the North Pacific. 45-51
Nishiwaki, M., M. Nakajima and T. Kamiya. A rare species of dolphin (Stenella attenuata) from Arari,Japan. 53-64
Nishiwaki, M., T. Kasuya, T. Tobayama, T. Kamiya and M. Nakajima. Feresa attenuata captured at the
Pacific Coast of Japan in 1963. 65-90
Nakajima, M. and M. Nishiwaki. The first occurrence ofa porpoise (Electra electra) in Japan. 91-104
Hosokawa, H. and T. Kamiya. Sections of the dolphin's head (Stene/la caeruleoalba). 105-133
Ohsumi, S. A dolphin (Stenella caeruleoalba) with protruded rudimentary hind limbs. 135-136

NUMBER 20, SEPTEMBER 1966
Ohsumi, S. SC"xual 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. 1782
Kasuya, T. Caryotype of a sei whale. 83-88
Kasuya, T. and S. Ohsumi. A secondary sexual character of the sperm whale. 89-94
Nishiwaki, M. and K. S. Norris. A new genus, Peponocephala, for the odontoceti cetacean species Electra
electra. 95-100
Nishiwaki, M., M. Nakajima and T. Tobayama. Preliminary experiments for dolphin marking. 101107
Nemoto, T. Thysanoessa euphausiids, comparative morphology, allomorphosis and ecology. 109-155
Nasu, K. Fishery oceanographic study on the baleen whaling grounds. 157-210
lchihara, T. and M. Nishiwaki. External measurements and weight of a southern elephant seal. 211-212

viii
Tsuyuki, H. and S. Itoh.

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

213-221

NUMBER 21, JUNE 1969
Omura, H., S. Ohsumi, T. Nemoto, K. Nasu and T. Kasuya.. Black right whales in the North Pacific.
1-78
Nishiwaki, M. and Y. Hasegawa. 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., S. lgarashi. T. Kamiya and K. Hirosawa. Morphological characteristics and myelinization of acoustic system in the dolphins (Stenella caeruleoalba). 95-123
Mo!, T. and P.J.H. van Bree. A short contribution to the history of whaling in Japan during the l 7th
century. 125-129
Tsuyuki, H. and S. Itoh. Fatty acid composition offinless porpoise oil. 131-135;
Tsuyuki, H. and S. Itoh. Fatty acid composition of many toothed pilot whale oil. 137-141

NUMBER 22, JUNE 1970
Omura, H., T. lchihara and T. Kasuya. Osteology of pygmy blue whale with additional information on
external and other characteristics. 1-27
Nishiwaki, M. and T. Kasuya. Recent record of gray whale in the adjacent waters of Japan and a consideration on its migration. 29-37
Kasuya, T. and D. W. Rice. Note on baleen plates and on arrangement of parasitic barnacles of graywhale. 39-43
Nishiwaki, M. and T. Kasuya. A Greenland right whale caught at Osaka Bay. 45-62
Nasu, K. and Y. Masaki. Some biological parameters for stock assessment of the Antarctic sei whale.
63-74
Ohsumi, S., Y. Masaki and A. Kawamura, Stock of the Antarctic minke whale. 75-125
Kawamura, A. Food ofsei whale taken by Japanese whaling expeditions in the Antarctic season 1967/68.
127-152
Nemoto, T. and K. I. Yoo. An amphipod, Parathemisto gaudichaudii as a food of the Antarctic sei whale.
153-158
Tobayama, T., S. Uchida and M. Nishiwaki. Twin foetuses from a blue white dolphin. 159-162
Machida, S. A sword-fish sword found from a North Pacific sei whale. 163-164
Tsuyuki, H. and S. Itoh. Fatty acid components of black right whale oil by gas chromatography. 165-170

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., M. Nishiwaki and T. Kasuya. Further studies on two skeletons of the black right whale in
the North Pacific. 71-81
Nishiwaki, M. and T. Kasuya. Osteological note of an Antarctic sei whale. 83-89
Hosokawa, H. and T. Kamiya. Some observations on the cetacean stomachs, with special considerations
on the feeding habits of whales. 91-101
Lugassy, A. A., E. Korostoff and J. L. Rabinowits. Influence of incremental lines upon the compressive
strength of sperm whale dentin. 103-110

ix
Nishiwaki, M. and N. Oguro. Baird's beaked whales caught on the coast of Japan in recent 10 years.
111-122
Mizue, K., M. Nishiwaki and A. Takemura. The underwater sound of Ganges river dolphins (Platanista
gangetica). 123-128
Kasuya, T. and M. Nishiwaki. First record of Mesoplodon densirostris from Formosa. 129-137
Kawamura, A. and K. Kashita. A rare double monster of dolphin, Stenella caeruleoalba. 139-140
Tsuyuki, H. and S. Itoh. 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 N. Oguro. Catch of the Cuvier's beaked whales off Japan in recent years. 35-41
Nishiwaki, M., T. Kasuya, K. Kureha and N. Oguro. Further comments of Mesoplodon gingkodens. 43-56
Kasuya, T. Growth and reproduction of Stenella caeruleoalba based on the age determination by means ofdentinal growth layers. 57-79
Kasuya, T. and N. Oguro. 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.
87-108Kasuya, T. and A.K.M. Aminul Haque. Some informations on the distribution and seasonal movementof the Ganges dolphin. 109-115
Tsuyuki, H. and S. Itoh. Fatty acid component of various blubber oil of Ganges River dolphin. 117-125
Naito, Y. and M. Nishiwaki. The growth of two species of the harbour seal in the adjacent waters of
Hokkaido. 127-144
Ichihara, T. and K. Yoshida. Diving depth 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
Omurn, H. A review of pelagic whaling operations in the Antarctic based on the effort and catch data in
10° squares of latitude and longitude. 105-203
Nasu, K. Results of whale sighting by Chiyoda Maru 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 dorasl vagal nucleus to the upper cervical
cord in the sperm whale. 241-249
Tobayama, T., M. Nishiwaki and H. C. Yang. Records of the Fraser's Sarawak dolphin (Lagmodelphis
hosei) in the western North Pacific. 251-263
Miyazaki, N., T. Kusaya and M. Nishiwaki. 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 S. Itoh. 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. Po>sible migration route of the gray whale on the coast ofJapan. 1-14
Sa take, Y. and H. Omura. A txonomic study of the minke whale in the Antarctic by means of hyoid bone.
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., N. Miyazaki and W. H. Dawbin. Growth and reproduction of Stenella attenuata in the Pacificcoast of Japan. 157-226
Miyazaki, N., T. Kasuya and M. Nishiwaki. Distribution and migration of two species of Stenella in the
Pacific coast of Japan. 227-243
Kamiya, T. and P. Pirlot. Brain morphogenesis in Stenella coeruleoalba. 245-253
Castello, H.P., A. P. Torno and J. S. Panizza. First Antarctic record of a killer whale stranding. 255258
Kamiya, T. and N. Miyazaki. A malformed embryo of Stenella coeruleoalba. 259-263
Kamiya, T. and F. Yamasaki. 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
ltoh, S. and H. Tsuyuki. Fatty acid component of different blubber oil of finless porpoise. 303-306
Itoh, S. and H. Tsuyuki. 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 M. Nishiwaki. Recent status of the population of lndus 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 K. Kureha. 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 Y. Satake. Preliminary report on the geographical distribution of the Bryde's whalein 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 T. Kasuya. Additional information on skeleton of the minke whale from the Antarctic.
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 based on cemental layers. 73-106
McCann, C. Notes on the foetal skull of Mesoplodon stejnegeri. 107-117
Gianuca, N. M. and H. P. Castello. First record of the southern bottlenose whale, Hyperoodon planifrons
from Brazil. 119-126
Brownell, R. L. Jr., L. A. Aguayo and N. D. Torres. A Shepherd's beaked whale, Tasmacetus shepherdi, fromthe eastern South Pacific. 127-128
Brownell, R. L. Jr. and R. Praderi. Records of the delphinid genus Stenella in western South Atlantic

xiwaters. 129-135
Yamasaki, F., H. Satomi and T. Kamiya. An observation on the papillary projections at the lingual
margin in the striped dolphin. 137-140
Kasuya, T. and N. Miyazaki. An observation of epimeletic behavior of Lagenorhyncus obliquidens. 141143
Kawakami, T. Squids found in the stomach of sperm whales in the northwestern Pacific. 145-151
Leung, Y. M. Life cycle of (!vamus scammoni (Amphipoda: Cyamidae), ectoparasite of gray whale, witha remark on the associated species. 153-160
Kagei, N., T. Tobayama and Y. Nagasaki. On the helminthum of Franciscana, Pontoporia blainvillei.
161-166
Tsuyuki, H. and S. Itoh. Fatty acid component oflipid of Euphausia superba. 167-174
Naito, Y. The occurrence of the phocid seals along the coast ofJapan and possible dispersal of pups. 175185
Naito, Y. and M. Oshima. The variation in the development of pelage of the ribbon seal with reference
to the systematics. 187-197

NUMBER 29, DECEMBER 1977
Kasuya, T. Age determination and growth of the Baird's beaked whale with a comment on the feta!
growth rate. 1-20
Miyazaki, N. On the growth and reproduction of Stene/la coeruleoalbh off the Pacific coast of Japan. 21-48
Kawamura, A. On the food of Bryde's whales caught in the South Pacific and Indian Oceans. 49-58
Herman, L. M. and R. C. Antinoja. Humpback whales in the Hawaiian breeding waters: population andpod characteristics. 59-85
Aminul Haque, A.K.M., M. Nishiwaki, T. Kasuya and T. Tobayama. Observations on the behaviourand other biological aspects of the Ganges susu, Platanista gangetica. 87-94
Yamasaki, F., S. Komatsu and T. Kamiya. A comparative morphology of anal tonsils in Platanistidae.
95-100
Nemoto, T., R. L. Brownell, Jr. and T. Ishimaru. Coconeis diatom on the skin of Franciscana. 101-105
Castello, H.P. Food of a killer whale: Eagle sting-ray, Myliobatis found in the stomach of a stranded
Orcinus orca. 107-111
Nishiwaki, M. and A. Sasao. Human activities disturbing natural migration routes of whales. 113-120
Yoshida, K., N. Baba, M. Oya and K. Mizue. On the formation and regression of corpus luteum in thenorthern fur seal ovaries. 121-128
Abe, H., Y. Hasegawa and K. Wada. A note on the air-sac of ribbon seal. 129-135
Kawamura, A. and T. Furuno. On the northern extremes of pack ice observed by whaling vessels in thesummer of"the Antarctic seasons 1957/58-1962/63. 137-141

NUMBER 30 DECEMBER 1978
Kasuya, T. The life history of Dall's porpoise with special reference to the stock off the Pacific coast ofJapan. 1-64
Miyazaki, N. and M. Nishiwaki. School structure of the striped dolphin off the Pacific coast of Japan.
65-116
Clarke, R., A. Aguayo L. and S. B. del Campo. Whale observation and whale marking off the coast of
Chile in 1964. 117-178
Miyazaki, N. and S. Wada. Observation of cetacea during whale marking cruise in the western tropical
Pacific, 1976. 179-196
Goodall, R. N. P. Report on the small cetaceans stranded on the coasts of Tierra de! Fuego. 197-232
Miyazaki, N. and S. Wada. Fraser's dolphin, Lagenodelphis hosei in the western North Pacific. 231-244
Nemoto, T. Humpback whales observed within the continental shelf waters of the eastern Bering Sea.

xii

245-247
Yamamoto, Y. and H. Hiruta. Stranding of a black right whale at Kumomi, southwestern coast of Izu
Peninsula. 249-251
Klima, M. Comparison of early development of sternum and clavicle in striped dolphin and in humpback
whale. 253-269
Omura, H. Preliminary report on morphological study of pelvic bones of the minke whale from theAntarctic. 271-279
Kamiya, T., F. Yamasaki and S. Komatsu. A note on the parathyroid glands ol Ganges susu. 281-284
Yamasaki, F., S. Komatsu and T. Kamiya. Taste buds in the pits at the posterior dorsum of the tongueof Stenella coeruleoalba. 285-290
Kawamura, A. On the baleen filter area in the South Pacific Bryde's whales. 291-300
Kasuya, T. and M. Nishiwaki. On the age characteristics and anatomy of the tusk ol Dugong dugon.
301-310
Kagei, N., K. Asano and M. Kihata. On the examination against the parasites of Antarctic krill, Euphausia
superba. 311-313

NUMBER 31, DECEMBER 1979
Kasuya, T. and K. Kureha. The population of finless porpoise in the Inland Sea of Japan. 1-44
Kasuya, T. and R. L. Brownell Jr. Age determination, reproduction, and growth of Frnaciscana dolphin,
Pontoporia blainvillei. 45-67
Jurasz, C. M. and V. P. Jurasz. Feeding modes of the humpback whale, Megaptera novaeangliae, insoutheast Alaska. 69-83
Omura, H. and T. Kasuya. A skull of baleen whale dredged from the Inland Sea of Japan. 85-92
Kamiya, T., T. Tobayama and M. Nishiwaki. Epidermal cyst in the neck of a killer whale. 93-94
Major, P. F. An aggressive encounter between a pod of whales and billfish. 95-96
Kato, H. Carotenoid colored minke whale from the Antarctic. 97-99
Kato, H. Unusual minke whale with deformed jaw. 101-103
Naito, Y. and S. Konno. The post breeding distributions of ice-breeding harbour seal (Phoca largha)
and ribbon seal (Phoca fasciata) in the southern sea of Okhotsk. 105-119
Naito, Y. A record of the bearded seal wandering with special reference to the wandering speed.
121-123
Miyazaki, N., K. Itano, M. Fukushima, S. Kawai and K. Honda. Metals and organochlorine compounds in the muscle of dugong from Sulawesi Island. 125-128
Kamiya, T., S. Uchida and T. Kataoka. Organ weights of Dugong dugon. 129-132
Nishiwaki, M., T. Kasuya, N. Miyazaki, T. Tobayama and T. Kataoka. Present ditribution of the dugong
in the world. 133-141

SUBJECT INDEX

Taxonomy, Body proportionand Osteology
Balaena mysticetus 22 : 45-62
Eubalaena glacialis 13: 1-52, 21: 1-78, 21: 79-84,
23:71-81, 30:249-251
Eschrichtius robustus 22: 29-37, 26: 1-14
Balaenoptera musculus 7: 125-183
B. musculus brevicauda 22: 1-27
B. physalus 7: 125-183, 9: 121-163, 12: 127-189,
15: 17-84, 16: 29-34
B. borealis 9: 89-103, 14: 1-33, 23: 83-89
B. edeni 9: 89-103, ·14: 1-33, 16: 1-5, 16: 7-18,
31: 85-92
B. acutorostrata 11: 1-37, 12: 1-21, 19: 37-43, 22:75-125, 27: 1-36, 28: 57-68, 28: 69-72
Megaptera novaeangliae 7: 125-183, 14: 49-87
Physeter catodon 7: 125-183, 11:47-83, 16:35-45,
17: 1-14
Kogia sp. 9: 37-58
Tasmacetus shepherdi 28: 127-128
Mesoplodon ginkgodens 13: 53-83, 24: 43-56
M. densirostris 23: 129-137
M. stejnegeri 14: 35-48, 28: 107-117
M. bowdoini 16: 61-77
M. sp. 16: 79-82.<:Jphius cavirostris 24: 1-34
Berardius 27: 111-137
B. bairdii JO: 89-132
Hyperoodon planifrons 28: 119-126
Peponocephala electra 19: 91-104, 20: 95-100
Feressa attenuata 9: 59-88, 19: 65-90
Orcinus orca 26: 255-258
Globicephala macrorkynchus and G. melaena 27: 95110
Lagenodelphis hosei 25: 251-263, 30: 231-244
Stenella attenuata l 9: 53-64
S. spp. 28: 129-135
Platanista gangetica 24: 87-108
Small cetaceans; Tierra de! Fuego 30: 197-230
Mirounga leonina 20: 211-212
Systematic study
Pelvic bone 5: 5-15, 30: 271-279
Hyoid bone, baleen whales 18: 149-170
Balaenoptera acutorostrata 26: 15-24
Phoca 26: 313-320
Sternum and clevicle
Stene/la coeruleoalba 30: 253-269

Megaptera novaeangliae 30: 253-269
Tympano-periotic bone, toothed whales 25: 1-103
Vertebrae, baleen whales 23: 61-69
Skull and other characteristics, delphinidae 17:

93-103, 18: 171-172
Secondary sexual character
Balaenoptera physalus 16: 29-34
Physeter catodon 20: 89-94
Karyotype
Balaenoptera borealis 20: 83-88

Anatomical and Histological study
Brain, Physeter 6: 49-72
Stenella 26: 245-253
Spinal cord, Eubalaena 13: 231-251
Dorsal vagal nucleus, Physeter 25: 241-249
Acoustic system 2: 1-20, 21: 95-123
Organ of hearing 2: 21-30, 8: 1-79
Labyrinth 14: 291-304
Sinus hair, Balaenoptera borealis 1: 41-47
Sensory tubercle, lip 3: 1-16
Lingual margin 28: 137-140
Taste buds, Stenella 30: 285-290
Head section, Stenella 19: 105-133
Extrinsic eye muscle 6: 1-33
Masseter, Megaptera 17: 49-52
Heart, conducting system 9: 11-35
cardiac nerve, Berardius 7: 1-22
Larynx 3: 23-62
Air-sac, Histriophoca and Phoca 29: 129-135
Lung 6: 35-47
Parathyroid, Platanista 30: 281-284
Abdominal cavity, iconography 5: 17-39
Stomach 23: 91-101
Renculi 13: 253-267
Anal tonssil, Platanistidae 29: 95-100
Corpus luteum, Callorhinus 29: 121-128
Red bone marrow, B. physalus 3: 17-22
Embryo, Stenella 10: 1-68, 16: 83-87
Size of cell 13: 269-301
Epidermal cyst 31: 93-94

Body and organ weight
Eubalaena glacialis 13: 1-52, 21: 1-78
Balaenoptera musculus 3: 132-190, 4: 184-209, 7:
125-183
B. musculus brevicauda 22: 1-27
B. physalus 3: 132-190, 4: 184-209, 7: 125-183

ii
B. horealis 4: 1-13
B. edeni 10: !33-141
B. acutorostrata 22 : 75-12 5
Megaptera noveangliae 7: 125-183, 14: 49-87
Physeter catodon 4: 1-13, 7: 125-183
Mesoplodon ginkgodens 24: 43-56
Lagenodelphis hosei 25: 251-263
Stenella attenuata 26: 157-226
Platanista gangetica 24: 87-108, 26: 265-270
Pontoporia hlainvillei 26: 265-270
Mirounga leonina 20: 211-212
Dugong dugon 31: 129-132

Age determination
Crystalline lens 3: 132-190, 4: 115-161
Baleen plates 4: 162-183, 6: 133-152
Ear plug 12: 23-32, 14: 107-135, 17: 37-48, 18:
29-48
Baleen whales 7: 87-119
Balaenoptera physalus 13: 155-169, 18: 49-88, 20:
17-82
Physeter catodon 13: 135-153, 17: 15-35, 20: 1-16
Berardius bairdii 29: 1-20
Stenella coeruleoalha 8: 133-1461 24: 57-79, 28: 73106, 29: 21-48
S. attenuata 26: 157-226, 28: 73-106
Platanista gangetica 24: 87-108
Pontoporia hlainvillei 31 : 45-67
Callorhinus ursinus 17: 191-195
Dugong dugon 30: 301-310

Population study
Euhalaena glacialis 13: 1-52, 21 : 1-78
Eschrichtius robustus 5: 71-79, 13: 201-205, 22: 2937, 22: 39-43, 26: 1-14
Balaenoptera musculus 3: 132-190, 4: 27-113, 5: 91167, 6: 73-131, 7: 125-183, 8: 147-213
B.physalus 3: 119-131, 3: 132-190, 4: 27-113, 5:
91-167, 6: 73-131, 7: 125-183, 8: 147-213, 11:85-98, 12: 103-125, 13: 97-133, 13: 155-169, 15:
85-142, 17: 53-65, 18: 1-27, 18: 49-88
B. horealis 3: 119-131, 4: 27-113, 9: 89-103, 22:
63-74
B. edeni 3: 106-118, 3: 119-131, 9:89-103, 9:
165-177, 10: 79-87, 14: 1-33, 16: 7-18, 28: 135, 30: 291-300
B. acutorostrata 11: l-37, 11: 181-189, 19: 37-43,
22: 75-125, 37-59
Megaptera novaeangliae 4: 27-113, 6: 73-131, 7:
125-183, 8: 81-102, 8: 147-213, 14: 49-87, 15:
1-16, 16: 19-28, 29: 59-85, 30: 245-247
Physeter catodon 3: 106-118, 3: 119-131, 4: 27-113,

6: 153-165, 7: 121-124, 7: 125-183, 8: 147-213,
10: 143-149, 11: 39-46, 13: 135-153, 17: 15-35,
19: 1-35, 20: 1-16, 23: 1-25:(,iphius cavirostris 10: 89-132, 24: 35-41
Berardius 27: 111-137
B. hairdii 10: 89-132, 13: 213-214, 23: 111-122,
29: 1-20
Orcinus orca 13 : 85-96
Glohicephala macrorhynchus and G. melaena 27: 95110
Stenella coeruleoalba 12: 191-192, 22: 159-162, 24:
57-79, 26: 227-243, 28: 73-106, 29: 21-48, 30:
65-115S. attenuata 26: 157-226, 26: 227-243, 28: 73-106
Lagenodelphis hosei 30: 231-244
Phocoenoides dalli 30: 1-64
Neophocaena phocaenoides 31 : 1-44
Platanista gangetica 24: 87-108, 24: 109-115, 27:
81-94, 29: 87-94
Pontoporia blainvillei 31 : 45-67
School, baleen whales 18: 89-110
Corpora albicantia 18: 123-148
Virginal band 21 : 85-94
Counting and measuring, baleen and ventral grooves
25: 279-292
Baleen, function 28: 37-55
Underwater sound 23: 123-128
Epimeletic behavior 28: 141-143
Marking dolphin 20: 101-107, 24: 81-85
Human activity disturbing whales 29: 113-120
History, whaling 21: 125-129
Colar pattern, Phoca 25: 301-310
Growth, Phoca 24: 127-144
Pelage, Historiophoca 28: 187-197
Occurrence, phocid seals 28: 17 5-185
Distribution, Phoca 31: 105-119
Dugong 31: 133-141
Diving depth, Callorhinus 24: 145-148
Wandering speed, Erignathus 31: 121-123
Serology 7: 69-77, 8: 103-125, 9: 105-120, 11:85-98. 13: 171-184, 14: 89-100, 14: 101-106, 15:
85-142, 17: 53-65, 17: 67-77, 18: 1-27

Food and feeding(See also population study)
Baleen whales 5: 81-90, 12: 33-89, 13: 193-199,
14: 149-290, 16: 89-103, 17: 157-170, 19: 45-51,
20: 109-155
Balaenoptera horealis 22: 127-152, 22: 153-158, 25:
219-236, 26: 25-144
B. edeni 7: 79-85, 29: 49-58
Megaptera novaeangliae 31 : 69-83

iii

Eschrichtius robustus 22: 39-43
Physeter catodon 5: 81-90, 11: 139-151, 11: 153161, 18: 111-122, 28: 145-151
Orcinus orca 29: 107-111
Stenella coeruleoalba 25: 265-275
Antarctic fish from stomach 12: 225-233
Stone and alien from stomach 17: 83-91
Stomach content in relation to chasing time 23:
27-36
Energy budget 27: 61-79

Whaling ground, environmental
9: 179-187, 11: 163~179, 12: 91-101, 12: 209-224,
13: 215-229, 14: 137-143, 15: 143-158, 16: 105119, 17: 105-155, 20: 157-210, 26: 271-287, 27:
141-157
Statistical review 25: 105-203
Pack-ice limit 29: 137-141
Sighting
By boat 25: 205-217, 26: 289-302, 30: 117-178,
30: 179-195
By air 23: 37-60

Parasite, scar and skin disease
Diatom 4: 14-26, 11: 99-132, 13: 185-191, 29:
101-105
Cyamus 28: 153-160
Barnacle 22 : 39-43
White scar 10: 69-77, 26: 145-155
Skin disease 11 : 133-138
Helminthes II: 133-138, 28: 161-166
Marlin spear 14: 149-290 (p. 252), 22: 163-164,
25: 237-239
Aggressive encounter 31: 95-96
Parasite, Euphausia 30: 311-313

Chemical study
Enzyme, stomach I : 3- 7
pancreas 1:8-10, I: 11-14, 2:55-60, 3:
71-78
Whale meat, peptone l: 15-16
freshness 1:17-26, 1:27-30, 2:3134, 3: 63-70, 5: 1-4, 6: 167-176,
7: 23-30, 7: 31-36, 9: 1-10
tryptophane 2 : 51-54

digestion 2: 61-66
nutrition 7: 51-67
amino acid
13: 303-31 7, 14: 305326
methionine 3: 102-105
Whale blood I: 38-40, 3: 96-101, 5: 41-47
Whale milk 10: 151-167
Vitamin I: 31-37, 2: 35-41, 5: 53-59, 6: 187-191,
7:47-50
Kitol 3: 85-88, 3: 89-91, 3: 92-95, 5: 49-51, 5:
61-69, 6: 193-198, 7: 47-50
Oil, gas absorption 11: 191-213, 13: 309-321
molecular distillation 2: 42-45, 2: 46-50
Oil, Eubalaena 17: 171-190
Physeter 3: 79-84, 7: 37-46
Mirounga 12: 235-240, 13: 323-332, 20: 213221
Lipid, Eubalaena 18: 173-180
Fatty acid composition of oil,
Eubalaena 22: 165-170
Neophocaena 21 : 131-135, 26: 303-306
Peponocephala 21: 137-141
Platanista 23: 141-147, 24: 117-125
lnia 25: 293-299
Trichechus 26: 307-311
Krill 28: 167-174
Metal, Dugong 31: 125-128
Organochlorine compounds, Dugong 31: 125-128

Miscellaneous
Hind limb 8: 127-132, 12: 197-208, 17: 79-81,
19: 135-136
Hermaphroditism 8: 215-218
Prenatal dead fetus 16: 47-60
Malformed fetus 12: 193-195, 14: 145-147, 23:
139-140, 26: 259-263
Albino 13:207-209
Carotinoid body color 31: 97-99
Deformed jaw 13: 211-212, 31: 101-103
Vestigial teat 25: 277-278
Strange organ 27: 139-140
Electrocardiogram, Tursiops 15: 159-165
Electric shock 6: 177-185
Compressive strength, den tin 23: 103-110
Flattened head harpoon 6: 199-207

AUTHOR INDEX

A

Abe, H. 29: 129-135
Abe, T. 12: 225-233
Aguayo L., A. 28: 127-128, 30: 117-177
Akiba, T. 3: 63-70, 5: 1-4
Akikusa, S. 10: 151-167
Akiya, S. I: 3-7, I: 8-10, I: I 1-14, I: 15-16, 2:
51-54, 5: 41-47, 7: 23-30, 7: 31-36
Aminul Haque, A.K.M. 24: 109-115, 29: 87-94
Antinoja, R. C. 29: 59-85
Arai, Y. 7: 51-67
Arifuku, S. 2: 1-20
Asano, K. 30: 311-313
BBaba, N. 29: 121-128
Brownell, R.L.Jr. 28: 127-128, 28: 129-135, 29:
101-105, 31: 45-67c
Calaprice, N. 17: 67-77
Castello, H.P. 26: 255-258, 28: 119-126, 29:
107-111
Clarke, R. 30: 11 7-1 77
Cushing, John E. 14: 89-100, 14: 101-106, 17:
67-77
DDairokuno, A. 12: 209-224
Dawbin, W. H. 26: 157-226
de! Campo, S. B. 30: 117-177
E

ECG Research Group

15: 159-165
F

Fujino, K. 7: 67-77, 7: 125-183, 8: 103-125, 9:
89-103, 9: 105-120, 9: 121-163, 10: 89-132, 10:
133-141, 11: 47-83, 11: 85-98, 13: 171-184, 14:
89-100, 14: 101-106, 15: 85-142, 17: 53-65, 17:
67-77, 18: 1-27
Fukazawa, R. 3: 85-88, 3: 89-91, 3: 92-95, 5:
49-51
Fukushima, M. 31: 125-128
Furuno, T. 29: 137-141

G

Gianuca, N. M. 28: 119-126
Goodall, R.N.P. 30: 197-232
H

Handa, C. 13: 85-96
Hasegawa, Y. 21: 79-84, 29: 129-135
Hayashi, K. 3: 132-190
Herman, L. M. 29: 59-85
Hibiya, T. 6: 1.53-165, 7: 121-124, 9: 165-177,
22: 39-46, 13: 97-133, 13: 135-136
Hirata, M. 6: 199-207
Hirosawa, K. 21 : 95-123
Hirose, S. 10: 151-167
Hiruta, H. 30: 249-151
Honda, K. 31: 125-128
Hoshina, T. 11: 133-138
Hoshino, 0. 5: 41-47, 7: 23-30, 9: 1-10
Hosokawa, H. 3: 23-62, 5: 5-15, 6: 1-33, 10: 168, 13: 269-301, 19: 105-133, 21: 95-123, 23:
91-101
I

Ichihara, T. 12: 127-189, 13: 155-169, 13: 201205, 14: 107-135, 16: 47-60, 17: 37-48, 18: 2948, 19: 37-43, 20: 17-82, 20: 211-212, 22: 1-27,
24: 145-148
Igarashi, S. 21: 95-123
lguchi, K. 8: 147-213
Ishikawa, S. I: 11-14, 2:35-41, 2:42-45, 2:5560, 3: 71-78, 5: 53-59, 5: 61-69, 11: 191-213,
13: 309-321
Ishimaru, T. 29: 101-105
Itano, K. 31: 125-128
Itoh, S. 20: 213-221, 21: 131-135, 22: 165-170,
23: 141-147, 24: 117-125, 25: 293-299, 26: 303306, 26: 307-311, 28: 167-174
Iwai, E. 11: 139-151, 11: 153-161

J
Jimbo, H. 3: 119-131
Jurasz, C. M. 31: 69-83
Jurasz, V. P. 31: 69-83
K

Kagei, N. 28: 161-166, 30: 311-313
Kakuwa, Z. 8: 147-213

iv

v
Kamiya, T. 12: 197-208, 13: 53-83, 13: 253-267,
14: 35-48, 19: 53-64, 19: J05-133, 21: 95-123,
23: 91-JOl, 26: 245-253, 26: 259-263, 26: 265270, 28: 137-140, 29: 95-100, 30: 281-284, 30:
285-290, 31: 93-94, 31: 129-132
Kaneko, A. 2 : 46-50
Kanno, H. 2: 42-45
Kashita, K. 23: 139-140
Kasuya, T. 16: 35-45, 17: 15-35, 19: 37-43, 19:45-51, 19: 65-90, 20: 83-88, 20: 89-94, 21: l-27,
22: 1-27, 22: 29-37, 22: 39-43, 22: 45-62, 23:
37-60, 23: 71-81, 23: 83-89, 23: 129-137, 24:
43-56, 24:57-79, 24:81-85, 24:87-108, 24:
J09-115, 25: l-J03, 25: 265-275, 26: 157-226,
26: 227-243, 27: 81-94, 27:95-108, 28: 57-68,
28: 73-J06, 28: 141-143, 29: 1-20, 29: 87-94, 30:
1-63, 30: 301-3JO, 31: 1-44, 31: 45-67, 31: 8592, 31: 133-141
Kataoka, T. 31: 129-132, 31: 133-141
Kato, H. 31: 97-99, 3I: JOI-J03
Kawai, S. 3I: 125-I28
Kawakami, T. 7: 79-85, 8: 147-2I3, 28: I45-15I
Kawamura, A. 22: 75-I25, 22: I27-I52, 23: 2736, 23: 139-140, 25:219-236, 26: 25-144, 27:
6I-79, 28: I-35, 29: 49-58, 29: 137-141, 30:
291-303
Kihata, M. 30: 3I 1-313
Kimura, S. 9: 165-177, 10: 89-132, 11: 39-46,
II: 181-189, 12: 103-125
Kijima, M. 5: 61-69
Klima, M. 30: 253-269
Kobo, F. I: 15-16
Kojima, T. 6: 49-72
Komatsu, S. 29: 95-IOO, 30: 281-284, 30: 285290
Konno, S. 31: 105-109
Korostoff, E. 23: 103-I 10
Kureha, K. 24: 43-56, 27: 139-I40, 31: I-44
L

Leung, Y. M. 28: I53-160
Lugassy, A. A. 23: 103-IIO
M

Machida, S. 22: I63-I64, 26: 27I-287, 26: 289302, 27: I4I-159
Maeda, T. 17: 1-14
Major, P. F. 3I: 95-96
Masaki, Y. 22: 63-74, 22: 75-125
McCann, C. 26: 145-I55, 27: IlI-I37, 28: J07I 17
Mizue, K. 3: 106-II8, 3: Il9-I3I, 5: 7I-79, 5:

8I-90, 6: 73-131, 23: 123-128, 29: 121-128
Miyazaki, N. 25: 265-275, 26: 157-226, 26: 227243, 26: 259-263, 28: 141-143, 29: 21-48, 30:
65-115, 30: 179-195, 30: 231-244, 31: 125-128,
31: 133-141
Mol, T. 21: 125-129
Mori, T. 3: 79-84
Motohashi, N. 7: 23-30, 9: 1-10
Murata, T. 6: 35-47, 6: 73-131
N

Nagasaki, Y. 28: 161-166
Naito, Y. 24: 127-144, 25: 301-310, 26: 313-320,
28: 175-185, 28: 187-197, 31: 105-119, 3I: 12II23
Nakai, T. I: 17-26, I: 27-30, I: 4I-47, 2: 31-34,
6: 167-I76, 6: 177-185, 14: 305-326
Nakajima, M. I7: I9I-I95, I9: 65-90, 19: 9II04, 20: JOl-107
Naruse, U. I7: 17I-I90, I8: I73-180
Nasu, K. II: I63-I79, 12: 9I-IOI, 13: 193-199,
I3: 2Il-2I2, I4: I37-143, I5: I43-158, I7: 8391, I7: I05-I55, 20: I57-210, 22: 63-74, 25:
205-2I7
Natsume, Y. 3: 63-70, 5: I-4
Nemoto, T. IO: 67-77, JO: 79-87, lI: 99-I32, I I:
181-189, I2: 33-89, 13: 97-133, 13: 185-I91, 13:
193-199, 14: 149-290, 16: 29-34, 16: 89-103, 17:79-81, 17: 83-91, 17: 191-195, 18: 89-110, 18:
111-122, 19:45-51, 20: 109-155, 21: 1-78, 22:
153-158, 23: 129-137, 27: 8I-94, 29: JOl-J05,
30: 245-247
Nishimoto, S. 7: 79-85
Nishiwaki, M. 3: 132-190, 4: 1 I5-161, 4: 162183, 4: 184-209, 5: 91-167, 6: 133-152, 6: 153165, 7: 87-119, 7: 121-124, 8: 133-146, 8: 215218, 9: 165-177, JO: 143-149, II: 39-46, 12: 2332, 12: 191-192, 12: 193-195, 13: 53-83, 13: 8596, 13: 97-133, 13: I35-153, 13: 155-169, 14:35-48, 14: 49-87, 15: 1-16, 16: 19-28, I6: 3546, 16: 61-77, 16: 79-82, 17: 1-14, 17: 15-35,
17: 93-103, 17: 191-195, 18: 171-172, 19: 53-64,
19: 65-90, 19: 91-104, 20: 95-100, 20: IOl-J07,
20:211-212, 21: 79-84, 22:29-37, 22:45-62,
22: 159-162; 23: 71-81, 23: 83-89, 23: 111-122,
23: 123-128, 23: 129-137, 24: 35-41, 24: 43-56,
24: 127-144, 25: 251-263, 25: 265-275, 25: 277278, 26: 227-243, 27: 81-94, 27: I39-140, 29:
87-94, 29: 113-120, 30: 65-115, 30: 301-3JO, 3I:
93-94, 3I: 133-I4I
Norris, K. S. 20: 95-100

vi
0

Ogawa, T. 2: 1-20, 3: 1-16, 7: 1-22, 8: 127-132,
9: 11-35, 12: 197-208, 13: 303-307
Oguro, N. 23: 111-122, 24: 43-56, 24: 81-85
Ohe, T. 3: 17-22, 5: 17-39, 5: 91-107
Ohno, M. 7: 125-183
Oshima, M. 28: 187-197
Ohsumi, S. (Kimura) 13: 97-133, 13: 135-153, 13:
155-169, 13: 207-209, 14: 145-147, 15: 17-84,
17: 1-14, 17: 15-35, 18: 49-88, 18: 123-148, 19:
1-35, 19: 135-136, 20: 1-16, 20: 89-94, 21: 1-78,
21: 85-94, 22: 75-125, 23: 1-25, 25: 237-239
Ohta, K. 10: 151-167
Oishi, Y. 10: 151-167
Okano, K. 10: 151-167
Okuda, H. 5: 53-59
Okutani, T. 18: 111-122
Omote, Y. 2: 35-41, 2: 42-45, 5: 53-59, 5: 6169, 6: 187-191, 6: 193-198, 7: 47-50
Omura, H. 4: 1-13, 4: 14--26, 4: 27-113, 8: 81102, 9: 89-103, 10: 79-87, 10: 89-132, I I: 1-37,
12: 1-21, 13: 1-52, 13: 213-214, 14: 1-33, 16:
1-5, 16: 7-18, 16: 35-45, 18: 149-170, 21: 1-78,
22: i-27, 23: 61-69, 23: 71-81, 24: 1-34, 25:
105-203, 26: 1-14, 26: 15-24, 27: 1-36, 28: 5768, 28: 69-72, 30: 271-279, 31: 85-92
Ono, H. 6: 177-185
Osawa, M. 13: 303-307
Oya, M. 29: 121-128p

Panizza, J. S. 26: 255-258
Pirlot, P. 26: 245-253
Pivorunas, A. 28: 37-55
Praderi, R. 28: 129-135
R

Rabinowits, J. L. 23: 103-110
Rice, D. W. 22: 39-43s
Saiki, M. 3: 79-84
Sakai, S. 7: 51-67
Sakiura, H. I I: 1-37
Sasao, A. 29: 113-120
Satake, Y. 26: 15-24, 28: 1-35
Sato, M. 10: 151-167
Satomi, M. 28: 137-140
Sawamura, R. 7: 31-36
Seki, Y. 13: 231-251, 25: 241-249
Sekino, T. 13: 269-301

Shida, T. 1: 41-47, 3: 1-16
Soma, Y. 2: 35-41
Sugiura, Y. II: 133-138
Suzuki, T. 13: 215-229, 17: 49-52
T

Takahashi, K. 2: 51-54, 14: 89-100
Takao, M. 7: 37-46
Takemura, A. 23: 123-128
Tanzawa, T. 1: 8-10
Tawara, T. 1: 31-37, 1: 38-40, 3: 85-88, 3: 8991, 3: 92-95, 3: 96-101, 5: 49-51
Tejima, S. I: 3-7, I: 8-10, I: 11-14, 2: 55-60
Tobayama, T. 19: 65-90, 20: 101-107, 22: 159162, 25: 251-263, 28: 161-166, 29: 87-94, 31:
93-94, 31: 113-141
Tokita, K. 15: 159-165
Torno, A. P. 26: 255-258
Torres, N. D. 28: 127-128
Tozawa, H. 7: 79-85
Tsuchiya, T. 3: 63-70
Tsukamoto, S. 2 : 61-66
Tsunoda, T. 13: 303-307
Tsuyuki, H. 12: 235-240, 13: 323-332, 17: 171190, 18: 173-180, 20: 213-221, 21: 131-135, 21:
137-141, 22: 165-170, 23: 141-147, 24: 117-125,
25: 293-299, 26: 303-306, 26: 307-31 I, 28: 167174

uUchida, S. 22: 159-162, 31: 129-132
Ueshiba, Y. 10: 151-167
Uda, M. 9: 179-187, 11: 163-179, 12:209-224,
13: 215-229, 16: 105-119
Umehara, M. 3: 63-70, 5: 1-4v
van Bree, P.J.H.

21: 125-129

w
Wada, K. 29: 129-135
Wada, S. 30: 179-195, 30: 233-246
Watari, T. 10: 151-167
Williamson, G. R. 25: 279-292, 27: 37-59
yYagi, T. 8: 133-146, 17: 191-195
Yamada, M. 2: 21-30, 8: 1-79, 9: 37-58, 9: 5988, 14: 291-304
Yamaguchi, K. 7: 69-77
Yamamoto, Y. 30: 249-251
Yamasaki, F. 26: 265-270, 28: 137-140, 29: 95-

vii
JOO, 30: 283-286, 30:289-292
Yang, H. C. 25: 251-263
Yoo, K. I. 22: 153-158
Yoshida, K. 24: 145-148, 29: 121-128

Yoshida, M. 3: 102-105
Yoshizaki, F. 14: 291-304
Yoshikawa, T. 10: 151-167, 17: 49-.52

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