ISSN 0083-9086

THE

SCIENTIFIC REPORTS
OF
THE WHALES RESEARCH INSTITUTE
No. 35

THE WHAtES RESEARCH INSTITUTETOKYO· JAPANMARCH 1984l Sci. Rep. Whales j
~

I~

THE
SCIENTIFIC REPORTS
OF..

THE WHALES RESEARCH INSTITUTE

No. 35

THE WHALES RESEARCH INSTITUTETOKYO, JAPANMARCH, 1984

THE WHALES RESEARCH INSTITUTE
3-32-11 OHJIMA, KOTO-KU, TOKYO 136•

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE
CONTENTS OF NUMBER 35Page

LOWRY, L. F. and K.J. FROST
Foods and feeding of bowhead whales in western and northern Alaska..
I
SINGARAJAH, K. v.
Observations on the occurrence and behaviour of minke whales off thecoast of Brazil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I 7
KATO, H.
Observation of tooth scars on the head of male sperm whale, as anindication of intra-sexual fightings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
SEKI, Y.
Anatomical studies on the cell column located closely medial to the
nucleus of the spinal root of the trigeminal nerve in the sperm and thepygmy sperm whales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
KASUYA, T. and S. MATSUIAge determination and growth of the short-finned pilot whale off the
Pacific coast of Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
MIYAZAKI, N., L. L. JONES and R. BEACH
Some observations on the schools of dalli- and truei-type Dall's porpoises
in the northwestern Pacific ....................... ; . . . . . . . . . . . . . . . . 93
KASUYA, T. and L. L. JONES
Behavior and segregation of the Dall's porpoise in the northwestern
North Pacific Ocean ............................................ 107
LEATHERWOOD, S., R.R. REEVES, A. E. BowLEs, B. S. STEWART and
K. R. GOODRICH
Distribution, seasonal movements and abundance of Pacific white-sided
dolphins in the eastern North Pacific. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
FORDYCE, R. E., R.H. MATTLIN and J. M. DIXON
Second record of spectacled porpoise from subantarctic Southwest Pacific. . 159
YAMASAKI, F. and K. KITo
A morphological note on the intestine of the Boutu, with emphasis on its
length and ileo-colic transition compared with other Platanistids. . . . . . . . 165
ZHou, K., M. ZHOU and Z. ZHAOFirst discovery of a tertiary Platanistoid fossil from Asia . . . . . . . . . . . . . . 173
OMURA, H., M. SmRAKIHARA and H. ho
A pygmy sperm whale accidentally taken by drift net in the North Pacific. . 183
FURUTA, M.
Note on a gray whale found in the Ise Bay on the Pacific coast of.Japan .. 195
APPENDIX
Measurements of body proportions of the pygmy blue whale, left by The
Late Dr Tadayoshi Ichihara ...................................... 199

目次

Lowry,L.F.andK.J.Frost
アラスカ沿岸のホッキョククジラの餌と食性

S
i
時 a
rJ
a
h
,K.V.
ブラジル沖のミンククジラの行動．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

1
7

加藤秀弘
マ y コヴクジラ頭部の傷の観察．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

39

関泰志
マツコウクジラとコマツコウの三叉神経脊髄路核の内方に位置する特異な細胞柱に関する解剖学的研究．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

47

粕谷俊雄・松井進
マゴンドウの年齢査定と成長．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

57

宮崎信之・ L.L.Jones・R.Beach
北西太平洋におけるイシイルカ属の作群．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．．

93

粕谷俊雄・ L
.L
.J
o
n
e
s
北西北太平洋におけるイシイルカ類の行動と棲み分けについて.................. 1
0
7

L
e
a
t
h
e
r
w
o
o
d
,S
.
,R.R.R
e
e
v
e
s
,A
.E
.B
o
w
l
e
s
,B
.S
.S
t
e
w
a
r
tandK.R. Goodrich
東部北太平洋におけるカマイルカの分布.................................... 1
2
9

F
o
r
d
y
c
e
,R.E
.
,R.H.M
a
t
t
l
i
nandJ
.M.Dixon
南西太平洋亜南極海のメガネイノレカ（s
p
e
c
t
a
c
l
e
dp
o
r
p
o
i
s
e）の第二号標本.......... 1
5
9山崎英雄・鬼頭研二
アマゾンカワイノレカの腸，特に長さおよび団結腸の比較形態学的研究

65............ 1

Zhou,K.
,M.ZhouandZ.Zhao
アジアで初めて発見された第三紀カワイルカ類化石............................ 1
7
3
大村秀雄・白木原美紀・伊藤春香
83
流し網にかかったコマツコウについて...................................... 1古田正美
95
伊勢湾にはいったコククジラ.............................................. 1

Appendix
故市原忠義博士の測定したピグミイシロナガスクジラの外部形態測定値............ 1
9
9

FOODS AND FEEDING OF BOWHEAD WHALESIN WESTERN AND NORTHERN ALASKALLOYD F. LOWRY AND KATHRYN J. FROST
Alaska Department of Fish and Game, 1300 College Road, Fairbanks, Alaska 99701 USA
ABSTRACTSamples were collected from the gastrointestinal tracts of 20 bowhead
whales taken by Eskimo whalers at several locations on the western and northern coast of Alaska. A probable total of 56 species of prey was found, including 50 species of crustaceans, 3 molluscs, and 3 fishes. Most of the preyspecies (23) were gammarid am phi pods, which occurred in 13 of the samples
examined. Of the individual prey species, the most frequently encountered
were a euphausiid, Th_ysanoessa raschii ( 11 occurrences); a copepod, Calanus
hyperboreus (10 occurrences); and a hyperiid amphipod, Parathemisto libellula (8occurrences).
In samples from stomachs containing appreciable amounts ofrecognizable
food, copepods were the dominant prey in nine, euphausiids in six, and gammarid amphipods in one. The latter was a whale taken at Gambell in May;
the others were all taken at Barrow in May, or at Barrow or Kaktovik in
September-October. Based on volumetric composition of the samples, euphausiids were the dominant (90.3% total contents) prey at Barrow in autumn(n=2). Whales taken there in May (n=4) had eaten substantial amounts ofcopepods (30.7%), as well as euphausiids (59.1%). Copepods (66.1%) andeuphausiids (31.2%) were the dominant prey of whales taken at Kaktovik in
autumn (n=8). The organisms most commonly eaten ranged from about 3
to 30 mm in length.
Based on stomach contents and other information, two important feedingareas in Alaska can at present be identified: the area between Barter Islandand the U.S.-Canada demarcation line, and the region from Point Barrow toapproximately Pitt Point. The organisms eaten in the Beaufort Sea in autumn are extremely high in fat and caloric content when compared to otherspecies and more southern areas. Calculations indicate that prey densities
are adequate for whales to obtain their annual energy needs during a 130-day
feeding season, and that annual production in most years is probably adequate
to support populations of bowheads and other consumers of zooplankton.
Arctic cod are the major consumers of copepods and euphausiids in the area.
Aspects of feeding ecology are obviously of great importance to the recoveryof the presently reduced bowhead whale population. A major question iswhether bowheads can reoccupy portions of the Bering and Chukchi seas thatwere once used as summer feeding areas.

Sci. Rep, Whales Res. Inst.,
No. 35, 1984, 1-16

2

LOWRY AND FROSTINTRODUCTION

Bowheaci whales, Balaena mysticetus, make extensive annual migrations from wintering areas in the Bering Sea to summering grounds in Amundsen Gulf and theBeaufort and Chukchi seas (Braham et al. 1982). It has generally been assumed
that bowheads, like other mysticete cetaceans, feed principally during the summer, and that their migration therefore is undertaken in order to reach preferred
feeding areas. However, aspects of the feeding biology of bowheads are very
poorly known.
The foods of most species of baleen whales are well documented since they
have been the objects of commercial harvests in the 19th and 20th centuries andthe contents of stomachs of harvested whales have been carefully examined (e.g.,
Nemoto 1957, Tomilin 1957). Bowheads were also extensively harvested by commercial whalers in the late 1800's and early 1900's. However, since they usually
were processed only for baleen and sometimes for oil, the contents of stomachs
were rarely, if ever, examined. Tomilin (1957) concluded based on indirect evidence that copepods (Calanus finmarchicus) and pteropods (Limacina helicina) weremajor food items. MacGinitie (1955) in a report based on work done at Point
Barrow indicated that bowheads ate euphausiids, mysids, pteropods, and copepods.
Johnson et al. (1966) examined the stomachs of two bowheads taken at Point Hopein April 1960 and May 1961. One stomach was empty; in the other, they foundfragments of polychaetes, crabs, snails, crustaceans, and echinoderms. Mitchell(1975) stated that bowheads eat principally small and medium-sized zooplankton
but sometimes also eat benthic organisms such as amphipods and mysids.
Since 1976 we have obtained and examined samples of the stomach contents
of bowhead whales taken by Eskimo whalers at several locations on the westernand northern coasts of Alaska. Those samples were collected for us through thecooperation of the Alaska Eskimo Whaling Commission and the National Marine
Fisheries Service. Results of our analyses of the samples have been in part reported (Lowry et al. 1978, Lowry and Burns 1980). In this paper we will report andsummarize all our observations on stomach contents of bowheads, examine theimportance of various prey species in their diet, identify major feeding areas in
Alaskan waters, and discuss the overall feeding strategy of bowheads in the western
Arctic.
METHODS

Samples of bowhead whale foods were collected for us by a number of different
persons. All samples were from the gastrointestinal tracts, usually the forestomachs, of whales taken by Eskimo subsistence hunters and were generally obtained
within a few hours of the time the whales were killed and landed. The samples
which we obtained were usually preserved in buffered 10% formalin and rangedin volume from a few mL to over 2L. The total volume of food present in theSci. Rep. Whales Res. Inst.,
No. 35, 1984

3

FOODS OF BOWHEAD WHALES

stomach of each whale was usually estimated and recorded in the field.
In the laboratory, samples were drained and gently washed on a 1.00-mm
mesh sieve. Food material was then sorted macroscopically into major taxonomic
groups, and the water displacement volume of each group was determined. The
organisms in each group were examined microscopically when necessary and identified to species if possible. Identifications were made using appropriate keys andreference specimens in collections at the Alaska Department of Fish and Game andthe University of Alaska. The number of individuals and total volume of eachprey species were determined, and lengths of representative specimens were measured. In the case of abundant, small organisms such as copepods, the volume andnumber of the various species were estimated from subsamples.
RESULTSWe examined samples of prey items from the gastrointestinal tracts of 20 bowhead
whales. With three probable exceptions, all were collected from stomach contents. Seven of the samples were from whales taken near Point Barrow, nine fromwhales taken near Kaktovik, two from Point Hope, and one each from Shaktoolik
and Gambell (Table 1 ). All of the samples from Kaktovik and two of those from
Barrow were from whales taken in the autumn (September or October); all of theothers were from whales taken in the spring (May).
TABLE 1. BOWHEAD WHALE SPECIMENS FROM WHICH SAMPLESOF PREY ITEMS WERE OBTAINEDSpecimennumberLocation

Date ofkill

Sex

Total length(m)76-B-6F
76-B-7F
77-B-579-B-380-B-380-B-580-B-979-KK-l
79-KK-2
79-KK-3
79-KK-4
79-KK-5
80-KK-lBarrow
Barrow
Barrow
Barrow
Barrow
Barrow
Barrow
Kaktovik
Kaktovik
Kaktovik
Kaktovik
Kaktovik
Kaktovik

10 Sep 76
20 Sep 76
5 May 77
27 May 79
25 May 80
25 May 80
27 May 80
20 Sep 79
6 Oct 79
8 Oct 79
10 Oct 79
II Oct 79
14 Sep 80

femalefemale
male
male
male
male
femalemale
female
male
male
male
male

16,0
14.3
10.6
8.3
8.5
10.4
13.7
12.7
10.5
10.3
10.6
10.6
9.1-10. 7

81-KK-l
81-KK-2
82-KK-l78-H-2
79-H-380-SH-l82-G-2

Kaktovik
Kaktovik
Kaktovik
Point Hope
Point Hope
Shaktoolik
Gambell

8 Sep 8111 Sep 81
23 Sep 82
4 May 78
6 May 79
9 May 80
1 May 82

female
male
male
male
male
male
female

17.4
14.0
16.0
9.7
9.1
10.1
8.8

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

Comments
reported to be an ingutuk
killed at 1600 hrs local timesample from colon
killed at 0630 hrs local time
killed at 0616 hrs local time
killed at 1800 hrs local time
recovered on 22 September

killed at 1740 hrs local timesample probably from small
intestine
killed at 1430 hrs local time
killed at 1700 hrs local time
killed at 2100 hrs local timesample from colon
killed at 1533 hrs local time4

LOWRY AND FROST

Depending on the state of digestion of the samples, it was more or less difficult
to determine the specific identity of the prey. Some prey could be identified only
to phylum, family, or genus when only fragments occurred in the samples. Small,fragile organisms such as copepods were difficult to identify to species except incomparatively fresh stomach contents. Larger, more durable organisms such asamphipods and molluscs could generally be identified in mostly digested stomach
or intestinal samples. The presence of euphausiids was easy to detect due to thepersistent and characteristic nature of the eyes which detach from the body during
digestion. Entirely soft-bodied animals such as coelenterates, salps, chaetognaths,
and pteropods may not have been detected in some samples examined, although
they would have been readily observed in those which were in fresh condition.
Eliminating those organisms which could not be identified to species but
which probably represented species found in other samples (e.g., Calanus sp., Gammarus sp., Family Lysianassidae, and Family Crangonidae ), a probable total of 56
prey species was found in the 20 whales containing identifiable food remains (Table2). With the exception of three species each of molluscs and fishes, all identified
prey were crustaceans. The distribution of prey species among the major groupsof crustaceans was: gammarid amphipods-23; copepods-10; hyperiid amphipods-5; shrimps-3; euphausiids, mysids, and crabs-2 each; and isopods, cumaceans, and ostracods-1 each. The number of times each of the major preygroups occurred in the samples was: gammarid amphipods-13; copepods-12;
euphausiids and hyperiid amphipods-11 each; mysids and shrimps-6 each;fishes-5; molluscs--4; crabs and cumaceans-2 each; and isopods and ostracods1 each. Of the individual prey species, the most frequently encountered were
Thysanoessa raschii (11 occurrences), Calanus hyperboreus (10 occurrences), and Parathemisto libellula (8 occurrences). All the remaining prey species occurred in fewer
than five stomachs, while 41 species occurred in only one or two samples. Pebbles,
generally less than 1 cm in size, occurred in six samples.
Copepods or euphausiids were the dominant component of all except five of
the samples we examined (Table 2). Two of those were from colons and contained
shrimp fragments and small clams. Two others contained a single amphipod anda single snail. The fifth contained gammarid amphipods, cumaceans, and otherbenthic organisms. In the other 15 samples, euphausiids were the major food insix, and copepods were dominant in nine. In most of the samples, either Thysanoessa raschii or Calanus hyperboreus was the dominant prey species. At Barrow, T.
raschii was the dominant prey in both whales taken in September, while in samples
from spring T. raschii and copepods (Calanus hyperboreus, Euchaeta glacialis, and Metridea longa) each predominated in two. In samples from whales at Kaktovik, allof which were taken in late September and early October, copepods (principally
C. hyperboreus) were dominant in seven and T. raschii in two.
Eliminating the samples obtained from small intestines or colons and thosefrom stomachs which contained only a single food item, food remains were foundin the stomachs of 15 whales. One of those (82-G-2) was a whale taken in the Bering Sea near Gambell on 1 May 1982. The stomach of that whale was recorded
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

?: f{>

x

x

xx xx

<.b

r-

r-

~
J:,

i:6

r-

i:6

(!)

....

~

c;.,

x

x

x

xx

x

x

rr-

~ ai
~
r-

.,.,
r-

di

~

~

x
x

x
x
x
x

x

x
x
x

x
x

x

x

x

x

x

"';'

;.::
;.::
di
r-

xx

x

x

xx xx
x

~
;.::
di
r-

-

x

x

x
x

co

~
0

ai

x
xx xx

0co

i:6

.,.,

N

x
x

xx
x
x
xx

x

"';'
~
0
co

--------------------BARROW

x

x

x

x

xx
x
x

x

di

r-

~
;.::

....

x

x

x
xx

x

di

r-

~
;.::

.,.,

xx

;.::'
;.::
0
co

~

KAKTOVIK

co

~

~
~

co

iN

~

~

x

x

x

x

x

x

x
x
x
xx xx xxco~~

PREY IDENTIFIED FROM GASTROINTESTINAL TRACTS OF BOWHEAD
WHALES. DOMINANT PREY SPECIES ARE INDICATED BY x x....

COPEPODS
Calanus cristatus
C. finmarchic~s
C. glacialis
C. hyperboreus
Calanus sp.
Chiridius obtusifrons
Euchaeta glacialis
Heterorhabdus sp.
Metridea longa
M. lucens
Pseudocalanus sp.
EUPHAUSIIDS
Thysanoessa inermis
T. raschii
MYSIDS
Mysis litoralis
Neomysis rayi
HYPERIID AMPHIPODSHyperia galba
H. medusarum
Hyperia sp.
Hyperoche medusarum
Parathemisto abyssorum
P. libellula

TABLE 2.

~

~

~~

.....

:'"·
l>O ~
~<>,~

~

r-

co

-

co

N

Continued ...

r-

c<")

:t :trn 6
cb di 0 iN

~

::r:

OTHER AREAS

>rj

(,J1

r:n

trJ

::r:
>
t""

~

t:J

>

~trJ

0

t:C

0>rj

t:J
r:n

0
0

<:<> ~""~~;_,_, ~
Yi :0

~~

~

~

!:tl

?:

GAMMARID AMPHIPODS
Acanthostepheia behringiensis
A. incarnata
Ampelisca macrocephala
Anonyx compactus
A. nugax
Apherusa glacialis
Arylus atlassovi
A. carinatus
Bathymedon sp.
Gammaracanthus loricatus
Gammarus zaddachi
Gammarus sp.
Hippomedon denticulatus
Monoculodes zernovi
Monoculodes sp.
Munnopsis c.f. Jv!. typica
Onisimus glacialis
0. litoralis
0. nanseni
Orchonome sp.
Pontoporeia femorata
Rozinante fragilis
W eyprechtia heulgini
W. pinguis
Family Lysianassidae
Family Synopiidae

,.._

x

x

x

x

x

(J:)
'
,.._

~

,.._

00

27
~ d; ""
~
,.._
0

i:Q
'
(J:)
,.._

~

l!')

(J:)

... ...

BARROW

000

di

l!')

x

0a:>

~

o;>

TABLE 2.

x

x

en
,.._

~

~

-

x

x

x

en
,.._

~

~

CN

Continued.

x
x

x
x

x

x

x

x

)<

en
,.._

l!')

~
::4

x

x

en
,.._

~

~

..;<

x

x

""~
~
en
,.._

x

0a:>

~

~

M

KAKTOVIK

x

x

co

~
~

-

x

x

co

~
~

CN

x

00

N

~

~

x

""

~ ,.._~

,.._

CN

~
0a:>
rJJ

x

x
x

x

x

x

x

x

a:>

N

6

CN

OTHER AREAS...;_i

rJl

0

~

"rj

tl

~

-<

~

~

t"'

0

O'l

:'"·

~-

~

w

"'

~

~~
-i:.. ..

....

~~~

~

~~

2

x

colon.
Sample probably from small intestine.

1 Sample fromISOPODS
Saduria entomon
SHRIMP
Eualus fabricii
E. gaimardii
Sabinea septemcarinata
Family Crangonidae
CRABS
Chionoecetes opilio
Family Paguridae]zoea)
CUMACEANS
Diastylis bidentata
Diastylis sp.
OSTRACODS
MOLLUSCS
Limacina helicina
Natica clausa
Nuculana sp.
Order Pelecypoda
FISHES
Boreogadus saida
Myoxocephalus quadricornis
Pungitius pungitius
Family Cottidae
PEBBLES

x

x

x

x

x

x
x

x

x

x

x

x

x

x

x
x

x
x

x

x

x

x

x

x
x

x

x

x

x

>rj

..,

"'

t:'j

t"'

6
~>

t:'j

~

C:l

>rj

"'0

t:I

0
0

8

LOWRY AND FROST

as full and contained an estimated 30L of food. Based on the sample we examined,
the prey was composed of 92% gammarid amphipods, 7% cumaceans, and 1 %other benthic organisms. Four small pebbles also occurred in the sample.
The quantitative composition of stomach contents samples from the remaining
14 whales is shown in Tables 3 and 4. Euphausiids dominated in the stomach
contents of whales taken at Barrow in the autumn. Whales taken at Barrow inthe spring contained principally euphausiids and copepods in variable proportions,with substantial amounts of mysids in three. Total quantities of food in whales
taken during spring were very small. In whales taken in the autumn at Kaktovik,
TABLE 3. QUANTITATIVE DATA(% OF TOTAL SAMPLE VOLUME) ON
STOMACH CONTENTS OF BOWHEAD WHALES TAKEN AT BARROW
AUTUMN 1976
Prey type

Copepod
Euphausiid
Mysid
Hyperiid amphipod
Gammarid amphipod
Other invertebrate
Sample volume (ml)Estimated total volume
of contents (liters)
1
2

SPRING 1977 AND 1980

Whale specimen Overall
numbermean%of contents 1
76-B-6F 76-B-7F
86.7

90.3

3.0
10.3
<0.1
17.5
33.0
unknown 109

2.7
6.9
<0.1

97. I
2.3
0.6

Whale specimen number
77-B-580-B-380-B-5

97.0
I.0

24.2
48.5
15.2
3.0

95.4
3.8

<0.1

2.0
20.0
3.3
unknown "a few
invertebrates"

73.4

80-B-9
1.4
91.6
5.4
1.0
0.6

Overallmean%
of contents 2
30.7
59. l
6.1
1.0
0.2
0.5

139.7
2

Calculated as the percent of combined total volume in the two samples.
Calculated as the average of the percent of total volume in each of the samples.
TABLE 4. QUANTITATIVE DATA(% OF TOTAL SAMPLE VOLUME) ON
STOMACH CONTENTS OF BOWHEAD WHALES TAKEN AT
KAKTOVIK, AUTUMN 1979-1982
Whale specimen number
Prey type
Copepod
Euphausiid
Mysid
Hyperiid amphipod
Gammarid amphipod
Other invertebrate
Fish
Sample volume (ml)Estimated total
volume of contents(liters)

1

79KK-1

79KK-2

79KK-3

79KK-4

79KK-5

81KK-1

81KK-2

82KK-1

99.7

99.0
0.3
0.3
0.1
0.1
<0.1
0.1
545.2
18

23.4
67.8
7.0
0.5
0.3

88.3
4.9

<0.1
97.9
0.8

99.0
0.7

99.0

98.7

<0.1
1.3

<0.1
0.1
<0.1
<0.1
2406.2
44

1.0
399.7
22

0.4
2.4
2.3
I. 7
131.3
18

0.1
I. I

<0.1
0.3
<0.1

1.0

357.9
36

145.5
18

19.2
95.2
3
"a few"

Overallmean%
of contents 1
66.1
31.2
1.2
0.1
0.4
0.5
0.3

Calculated based on the volume and percent composition of each sample and the estimated total
contents volume of stomachs from which samples were taken.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

FOODS OF BOWHEAD WHALESTABLE 5.

SIZES OF PREY ORGANISMS IN STOMACHS OF BOWHEAD WHALES

Copepods
Euphausiids
MysidsHyperiid amphipods
Gammarid amphipods
I so pods
Fishes1

9

Length (mm)lVolume (mL)

3.5-7.0
18-30
23-33
8-21
7-55
52-86
31-83

0.002-0.02
0.1-0.15
0.1-0.2
0.05-0.1
0.02-4.0
3.4-5. 7
0.1-2.9

Measurements are total length for all groups except copepods, which are cephalothorax length.

copepods and euphausiids in aggregate comprised 91.2-99.7% of the contents ofindividual samples and 97.3% of the overall prey in all samples combined. The
stomach contents in individual whales varied from 99.7% copepods to 97.9% euphausiids; overall, copepods comprised about twice as much of the stomach contents as did euphausiids. The total volume of stomach contents in the whales
varied from 3 to 44L, with an average of 23L.
Sizes of representative species of the major prey groups eaten by bowheads areshown in Table 5. The organisms most commonly eaten (copepods, euphausiids,
mysids, and amphipods) range from about 3 to 30 mm in length and have a volumeof 0.002 to 0.2 mL. Organisms such as isopods and fishes are considerably larger
but were rarely found in stomach contents samples. The largest item we foundin bowhead stomach contents was the shell of a snail (Natica clausa), 3.4 cm highand 2.6 cm in basal diameter, weighing 8.0 g. The smallest items were Pseudocalanus copepods, which are approximately 1.3 mm in cephalothorax length andweigh about 0.1 mg.
In addition to the whales from which samples were collected, some additional
animals were examined in the field and the presence or absence of food in theirstomachs recorded. Of whales taken in the Bering Sea in spring, two had preyin the stomach: one taken at Gambell (82-G-2) contained gammarid amphipods,
cumaceans, and other benthic organisms; the other (78-S-l) taken at Savoonga
was reported to con.lain "a few euphausiid-like creatures." Three had empty
stomachs: two of those reportedly had material in the intestines, and the third had
crustaceans in the baleen. Of four whales taken in the Chukchi Sea in spring, two
had empty stomachs, one contained a snail, the other a single gammarid amphipod.
Four whales taken at Barrow in spring have contained food remains, and sevenhave been recorded as having empty stomachs. Three of the latter had some foodresidues in the intestines. All whales that have been taken and examined in theautumn (2 at Barrow and 10 at Kaktovik) have contained substantial quantities
of food.
We examined the relationship between whale size and the principal type of
prey found in samples based on 18 animals of known length which contained recognizable prey. Whales that had eaten principally copepods ranged from 10.5
to 17.4 m, with a mean length of 13.1 m (n=7). Those that contained mostly euSci. Rep. Whales Res. Inst.,
No. 35, 1984

10

LOWRY AND FROST

phausiids ranged from 8.5 to 16.0 m, with a mean of 12.0 (n=7). Five whales
in which we found only benthic organisms were 8.3-10.1 m, with a mean lengthof 9.2 m. Only one of the whales that had eaten copepods or euphausiids was lessthan 10.3 m in length.
DISCUSSION

We identified a wide array of organisms from samples taken from the gastrointestinal tracts of bowhead whales. Most of the prey species (53/56) were invertebrates, and most of those (35/53) were primarily benthic organisms. However,with few exceptions, benthic species composed a very small proportion of the overall
stomach contents. Four of the five exceptions were whales taken in spring in the
Bering and Chukchi seas; the fifth was a whale taken at Barrow in spring whosecolon contained three small clams. The two taken in the Chukchi Sea each contained single items. One of those taken in the Bering Sea had an empty stomach
but shrimp fragments in the colon; the other had a stomach filled with benthic
invertebrates. The five whales were all small, the largest being 10.1 m long, andwere undoubtedly subadult animals (Marquette 1978). We conclude, based on
the samples we examined and field records, that some bowheads feed while passing
through the northern Bering Sea in May. The incidence of feeding during thenorthward migration appears to be less in the Chukchi Sea than in the Bering.
Feeding whales may be predominantly juveniles, and their prey are mostly benthic
invertebrates.
Four of 11 whales taken and examined at Barrow in the spring have contained
food in their stomachs, generally a few liters or less of copepods and euphausiids.
We conclude that some feeding occurs near Barrow during the spring migrationand that planktonic organisms are the main prey. However, based on the highproportion of empty stomachs and the small volumes of contents in those containing food, it appears that the main feeding season has not yet commenced.
Many bowhead whales summer in the eastern Beaufort Sea (Fraker andBockstoce 1980), where they are presumed to feed extensively (Griffiths and Buchanan 1982). Whales that have been taken and examined while moving westward
through the Alaskan Beaufort Sea in autumn have all contained food. Whales
taken at Barrow have contained mostly euphausiids, while in those taken near
Kaktovik both copepods and euphausiids occur, with copepods overall predominating in the samples. Benthic organisms are quantitatively unimportant near Kaktovik but comprised a small and perhaps significant proportion of the samples examined from Barrow. Feeding of whales in autumn is obviously directed primarily
at organisms in the water column, with benthic organisms being taken incidentally
during near-bottom feeding.
Several lines of evidence point to the existence of at least two areas of the
Alaskan Beaufort Sea where bowheads regularly feed during September-October.
First, of course, is the occurrence of substantial quantities of food in the stomachs
of all the whales taken and examined at Kaktovik and Barrow during autumn
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

FOODS OF BOWHEAD WHALES

II

hunts. Whalers from Kaktovik have indicated that they regularly find bowheads
feeding in the area to the east of Barter Island (D. Ljungblad, pers. commun.; G.
Jarrell, pers. commun.). In discussing bowheads in the area to the east of Point
Barrow, Durham (1979) stated that "the hunters sometimes encounter herds of
50 to 60 whales along the Plover Islands (Thomas Brower, pers. commun.). This
area may be a rest stop for the whales and provide an opportunity for them to feed,judging from stomach contents."
The feeding area east of Barrow appears to extend to approximately Pitt
Point. On 18 September 1974, 57 whales were counted in this area (Braham et al.
1982), while on 20 September counts ranged from 81 to 136 (Ray and Wartzok
1980). On 8 August 1976, a single whale was seen just offshore from the Plover
Islands (Lowry, unpublished). Two ringed seals (Phoca hispida) collected in theimmediate area within minutes of sighting the bowhead had been actively feedingon euphausiids (Lowry et al. 1980). On 19 August 1976, four bowheads wereseen northeast of Point Barrow, and on 21 September 47 whales were counted in
the area (Braham et al. 1982). As indicated in this report, whales taken at Barrowon 10 and 20 September 1976 had both been feeding on euphausiids. A group of
20 whales which appeared to be feeding was seen north of Point Barrow on 22
October 1978 (Braham et al. 1982).
The feeding area in the eastern Beaufort Sea extends from Barter Island east
to at least the U.S.-Canada demarcation line (141°W longitude). In 1979, 35
whales were seen milling east of Beaufort Lagoon on 24 September, and 37 wereobserved north of Demarcation Bay on 26 September (Ljungblad et al. 1980). In
1980, single whales that appeared to be feeding were sighted north of Beaufort
Lagoon on several occasions from 9 to 21 September, and a group of nine was seen
east of Barter Island on 14 September (Frost and Lowry 1981, Ljungblad 1981).
On 22 September 1982, 128 bowheads were counted in the area north of Demarcation Bay. Most of the animals were milling around near the surface (S. Johnson,
pers. commun. ).
Although bowheads may feed regularly or occasionally in other parts of the
Alaskan Beaufort Sea, such occurrences cannot be verified by observations of stomach contents since very few whales are taken elsewhere than the areas discussed
above. Ljungblad (pers. commun.) has seen bowheads engaged in behavior thatmight indicate feeding in the areas north of Flaxman Island and northeast of
Pingok Island.
The smallest organisms which are regular foods of bowheads are the copepods
Metridea spp. (cephalothorax length 2.7-3.1 mm) and Calanus glacialis (2.4-3.3 mm).
The most commonly eaten species of copepod, Calanus hyperboreus, is much larger,
ranging in length from 3.6 mm (copepodite stage IV) to 6.4 mm (adult). The
smaller copepods, Pseudocalanus sp. (1.1-1.6 mm long) and Derjuginia tolli (1.41.8 mm long), although very abundant in the Beaufort Sea (Frost and Lowry
1981 ), virtually never occur in bowhead stomach contents. It appears, therefore,that organisms smaller than about 2.5 mm are not effectively retained by bowheadbaleen. The largest prey regularly consumed appear to be about 30 mm long andSci. Rep, Whales Res. Inst.,
No. 35, 1984

12

LOWRY AND FROSTTABLE 6. CALORIC VALUES OF REPRESENTATIVE SPECIES OF ARCTICZOOPLANKTON AND BENTHOS, ARRANGED IN ORDER OF DECREASING CALORIC VALUE. ALL VALUES ARE FROM SAMPLES TAKEN
IN SEPTEMBER UNLESS OTHERWISE INDICATED.
(ADAPTED FROM PERCY AND FIFE 1980.)
Taxon
Copepod (Calanus sp.)
September
mid-late August
late July-early August
Euphausiid (Thysanoessa inermis)
Hyperiid amphipod (Parathemisto libellula)
Gammarid amphipod (Anonyx nugax)
Chaetognath (Sagitta elegans)
Isopod (Saduria ( =Mesidotea) sabini)
Pteropod ( Clione limacina)
Ctenophora (Mertensia ovum)
Cnidaria (Aglantha digitale)

Cal/g wet weight% of maximum

2,983
2,660
2,018
1,974
1,364
1,299
517
367
296
98
89

100
90
69
67
46
44
18
12
10
3
3

include euphausiids, mysids, and amphipods.
The fact that bowheads migrate several thousands of kilometers annually tosummer and feed in the Beaufort Sea implies that the quantities and kinds of foodavailable to them there are adequate, and also perhaps that feeding conditions aresuperior to those found in other areas. The abundance of copepods in the Beaufort Sea is not remarkably high (Griffiths and Buchanan 1982). The abundanceof euphausiids is extremely difficult to quantify (Brodie et al. 1978), but observations of predator stomach contents indicate that they may be locally abundant(Frost and Lowry 1981 ). One way in which arctic marine zooplankton are remarkable is their tendency to accumulate storage lipids during the summer which
are used for maintenance and reproduction during winter months (Lee 1975). In
samples of Calanus hyperboreus collected from Fletcher's Ice Island in October, lipids
comprised 64% of the dry weight (Lee 1975). In samples collected in September
at Frobisher Bay, lipids comprised 52.4% of the dry weight of Thysanoessa inermis
and 57.4% of Calanus spp. (Percy and Fife 1980). Caloric values of representative
species of arctic marine zooplankton and benthos are shown in Table 6. Values
are expressed in terms of calories per gram wet weight, which is the most appropriate consideration from the perspective of a consumer. Organisms which are
the primary foods of bowheads (copepods and euphausiids) have very high caloric
values. Those eaten with some frequency (hyperiid and gammarid amphipods)
have intermediate values. Those organisms which are rarely or never consumed
have very low caloric values. Of interest also is the fact that copepods in September contain almost 50% more calories than those sampled in late July and earlyAugust. Therefore, given equivalent prey densities, late summer feeding may beof greater value to the whales than that which occurs earlier in the year.
Although it is probably true in general that arctic zooplankton are richer incalories than those in more southern latitudes (Percy and Fife 1981), there are few
Sci. Rep. Whales Res. Inst.,

No. 35, 1984

FOODS OF BOWHEAD WHALES

13

data available with which to verify this hypothesis. Nishiyama (1977) sampledzooplankton in Bristol Bay, Alaska and determined the caloric value of Calanus andThysanoessa to be 5,512 and 5,554 cal/g ash-free dry weight. Those values are 44%
and 19% lower than comparable measurements for the same species collected at
Frobisher Bay (Percy and Fife 1980). The values for caloric content of Frobisher
Bay copepods are the highest published values for any marine organism (e.g., see
Braun et al. 1968, Tyler 1973, Laurence 1976).
Several authors have attempted to assess the relationship between availabilityof food in the marine environment and the food requirements of whales. Studies
dealing with fin whales (Balaenoptera physalus) have concluded that either whales
swim exceedingly fast, or densities of prey are much greater than those found using standard sampling techniques (Klumov 1961, Brodie et al. 1978). Similar results were derived by Brodie (1980) and Griffiths and Buchanan (1982), dealing
with bowheads. However, those studies did not take into account the energetic
richness of prey available in the Arctic.
We have made similar calculations, starting with the energetic assumptions
used by Brodie (1980), who concluded that a bowhead 13.72 m long would need toingest approximately 4,000 kg of lipids during the feeding season in order to maintain itself throughout the year. Based on data in Percy and Fife (1980), 16.8%of the wet weight of Calanus copepods collected in late July and August is lipid;
therefore, a whale would need to consume 23,810 kg of copepods during thefeeding,season. A bowhead 13.72 m long would have baleen approximately 2.4 m
long (Alaska Eskimo Whaling Commission, unpubl. data). We assume that whilefeeding the mouth opening is 2.4 m high and tapers from 2.0 m wide at the bottom
to 1.0 m at the top and a whale swims at about 4.2 km/hour (2.8-5.6 km/hr in
Ljungblad et al. 1981). Using those assumptions, 15,120 m 3 of water would be
filtered each hour. Griffiths and Buchanan (1982) observed biomasses of Calanus
ranging from 0.623-0.903 g/m 3 at certain depths in areas of the Canadian Beaufort
Sea where bowheads appeared to be feeding on organisms in the water column.
To acquire 23,810 kg of copepods would require filtering 26,367,000-38,218,000 m 3
of water (assuming the above prey densities and 100% filtering efficiency), which
would involve 1,744-2,528 hours of feeding. Frost and Lowry (1981) estimated afeeding season of 105 days in the Canadian Beaufort and 25 days in the Alaskan
Beaufort Sea, which suggests 3,120 hours available for feeding. Therefore, it appears that bowheads can obtain their annual food requirements with a 130-day
feeding season in the Beaufort Sea, if they feed for somewhat over half the timethey are on the feeding grounds and concentrate their efforts in areas where prey
are relatively abundant. Based on the above assumptions and an average weightfor copepods of 0.004 g (Bain et al. 1977), the ingestion rate of copepods would beapproximately 50,000 individuals per minute.
A further consideration with respect to the bowhead whale stock in the western Arctic is whether the total annual production of prey in the feeding areas issufficient to supply the energetic requirements of all the whales summering in thearea. Although the summer feeding range of the bowhead once included much
Sci. Rep. Whales Res. Inst.,
Na. 35, 1984

14

LOWRY AND FROSTof the Bering and Chukchi seas as well as the Beaufort Sea (Bockstoce and Botkin1980), at present the Beaufort Sea is the primary feeding area, although some lateseason feeding may occur in the Chukchi Sea (Frost and Lowry 1981). Calculations such as those done for an individual whale feeding on copepods cannot be
expanded to the entire population because euphausiids, a major prey species, havenot been quantitatively sampled properly in the Beaufort Sea (see Frost and Lowry
1981 and Griffiths and Buchanan 1982) and bowhead prey are also eaten by otherconsumers in the Beaufort Sea. Frost and Lowry (1983) estimated the quantities
of prey eaten on an annual basis by populations of major vertebrate consumers in
the Alaskan Beaufort Sea. They considered only species which feed primarily onorganisms connected to the pelagic/planktonic food web-bowhead whales, white
whales (Delphinapterus leucas), ringed seals, seabirds, and arctic cod (Boreogadus
saida). Results indicated that arctic cod are by far the major consumer of zooplankton. They were estimated to eat 97.8% of the total copepod and 65.8% of
the total euphausiid biomass consumed annually by all species of predators combined. Estimates for bowhead consumption were 2.2% of the total copepod biomass and 31.5% of the total euphausiid biomass consumed. Although these results suggest the possibility of considerable competition for food, some resource
partitioning occurs since many of the copepods eaten by arctic cod are small forms(Der}uginia and Pseudocalanus), which are not major foods of bowheads (Frost and
Lowry in press). Based on extrapolations from measurements of primary production, Frost and Lowry (1981) estimated that 0.3-4.4 million t of zooplankton are
produced annually in the Alaskan Beaufort Sea. When compared to the estimatedtotal amount ofzooplankton consumed annually (approximately 1.1 million t (Frostand Lowry in press)), this suggests that food availability may be limiting in years of
low production, while in other years a surplus of food may be available. Causesof annual variations in productivity and their effects on consumer populations arelargely unknown.
What then is the feeding strategy of western arctic bowhead whales? Bowhead whales are robust-bodied animals, possessing long baleen with fine fringes
capable of efficiently retaining very small prey. Although our study has shownthat some feeding occurs in the northern Bering and Chukchi seas during the springnorthward migration, the major known summer feeding grounds are in the Beaufort Sea. The quantities and kinds of organisms there are adequate, and the extraordinarily high fat content (and caloric value) of prey facilitates accumulation of
blubber reserves necessary to maintain the animals during periods of fasting. Extensive blubber reserves may help sustain animals through years of low summer
productivity which may occasionally occur.
Some late summer and early autumn feeding may occur in the Chukchi Sea.
There is no direct information to indicate whether bowheads feed on their wintering grounds in the Bering Sea. However, based on considerations such as theseasonal distribution and abundance of prey, and their probable caloric content,
we speculate that winter feeding in the Bering Sea, if it occurs, is of little significance in the annual nutrition of bowheads. Bowhead whales swim from the BerSci. Rep. Whales Res. Inst.,
No. 35, 1984

FOODS OF BOWHEAD WHALES

15

ing Sea to the Beaufort Sea to feed because of the high-energy foods available there,
and perhaps also because competition for food from other organisms occurs at tolerable levels. No other baleen whale penetrates northward into what is presently
the principal feeding grounds for bowheads. In years past, bowheads mingledwith other species in the Bering Sea in summer until they were eliminated by predation from commercial whalers. Whether the portions of their feeding rangethat were lost decades ago will ever be regained is a most interesting question, andone of great significance when contemplating the ability of the western arctic bowhead population to regain its former abundance.
ACKNOWLEDGMENTS

The samples which were used in this study were collected for us by a number ofpeople working for the Alaska Eskimo Whaling Commission, the North Slope
Borough, the National Marine Fisheries Service, and the Naval Arctic ResearchLaboratory. We are grateful to all who helped in the collection, preservation,and transport of specimens. Mr Robert Nelson and Mr Barry Lopez provided
invaluable help during field studies related to bowhead whale feeding. Mr
Kenneth Coyle and Mr George Mueller of the University of Alaska, Institute ofMarine Science, provided expert identifications of many prey organisms. Dr
Thomas Albert, Mr John Burns, and Dr Howard Braham assisted with manyof the financial and technical aspects of the study. Dr Paul Brodie made helpfulcomments on a draft of the manuscript. The manuscript was typed and editedby Mrs Kathleen Pearse.
REFERENCES
BAIN, H., D. THOMSON, M. Fov, and W. GRIFFITHS, 1977. Marine ecology of fast-ice-edges in Wellington
Channel and Resolute Passage, N.W.T. Report prepared for Polar Gas Project by LGL Limited,
Toronto, Ontario, Canada. 262 p.
BocKSTOCE, ]. R. and D. B. BOTKIN, 1980. The historical status and reduction of the western arctic bowhead whale (Balaena mysticetus) population by the pelagic whaling industry, 1848-1914. Final Rep.
Contract No. 03-78-M02-0212 submitted to Natl. Mar. Fish. Serv., Seattle, WA. 120 p.
BRAHAM, H. W., B. D. KROGMAN, and G. M. CARROLL, 1982. Bowhead whale (Balaena mysticetus) migration, distribution and abundance in the Bering, Chukchi and Beaufort seas, 1975-1978, with notes on
the distribution and life history of white whales (Delphinapterus leucas). NOAA Tech. Memo NMFS
SSRF-.
BRAWN, V. M., D. L. PEER, and R.J. BENTLEY, 1968. Calorific content of the standing crop ofbenthic andepibenthic invertebrates of St. Margaret's Bay, Nova Scotia. j. Fish. Res. Board Can. 25~ 1803-1811.
BRODIE, P. F., 1980. A preliminary investigation of the energetics of the bowhead whale (Balaena mysticetusL.). Rep. int. Whal. Commn., SC/32/PS 18. 7 p.
BRODIE, P. F., D. D. SAMEOTo, and R. W. SHELDON, 1978. Population densities of euphausiids off Nova
Scotia as indicated by net samples, whale stomach contents and sonar. Limnol. Oceanogr. 23: 12641267.
DURHAM, F. E., 1979. The catch of bowhead whales (Balaena mysticetus) by Eskimos, with emphasis on thewestern Arctic. Nat. Hist. Mus. Los Ang. Cty. Contrib. Sci. 314: 1-14.
FRAKER, M.A. and J. R. BocKSTOCE, 1980. Summer distribution of bowhead whales in the eastern BeauSci. Rep. Whales Res. Inst.,

No. 35, 1984

16

LOWRY AND FROST

fort Sea. Mar. Fish. Rev. 42 (9-10): 57-64.
FROST, K.J. and L. F. LOWRY, 1981. Feeding and trophic relationships ofbowhead whales and other vertebrate consumers in the Beaufort Sea. Final Rep. Contract No. 80-ABC-00160 submitted to Natl.
Marine Mammal Lab., NMFS, NOAA, Seattle, WA. 106 p.
FROST, K.J. and L. F. LOWRY. In press. Trophic relationships of vertebrate consumers in the Alaskan
Beaufort Sea. In P. W. Barnes, D. M. Schell, and E. Reimnitz, eds. The Alaska Beaufort SeaEcosystem and Environment. Academic Press, New York.
GRIFFITHS, W. B. and R. A. BucHANAN, 1982. Characteristics ofbowhead feeding areas. Pages 347-455 in
W.J. Richardson, ed. Behavior, disturbance responses and feeding of bowhead whales Balaena mysticetus in the Beaufort Sea, 1980-81. Unpubl. rep. by LGL Ecological Research Associates, Inc., Bryan,
TX, for U.S. Bur. Land Manage., Washington, DC. 456 p.
JoHNSON, M. L., C. H. Fiscus, B. T. OsTENSON, and M. L. BARBOUR, 1966. Marine mammals. Pages 897924 in N.J. Wilimovsky and J. N. Wolfe, eds. Environment of the Cape Thompson Region, Alaska.
U.S. Atomic Energy Comm., Oak Ridge, TN.
KLuMov, S. K., 1961. Plankton and the diet of baleen whales. Trudy Instituta Okeanologii 51: 142-146.
In Russian.
LAURENCE, G. C., 1976. Caloric values of some North Atlantic calanoid copepods. Fish. Bull. 74: 218220.
LEE, R. F., 1975. Lipids of arctic zooplankton. Comp. Biochem. Physiol. SIB: 263-266.
LOWRY, L. F. and.J.J. BuRNs, 1980. Foods utilized by bowhead whales near Barter Island, Alaska, autumn
1979. Mar. Fish. Rev. 42 (9-10): 88-91.
LOWRY, L. F., K.J. FROST, and J.J. BuRNs, 1978. Food of ringed seals and bowhead whales near Point
Barrow, Alaska. Can. Field-Nat. 92: 67-70.
LOWRY, L. F., K.J. FROST, and J . .J. BURNS, 1980. Variability in the diet of ringed seals, Phoca hispida, in
Alaska. Can. J. Fish. Aquat. Sci. 37: 2254-2261.
LJUNGBLAD, D. K., 1981. Aerial surveys of endangered whales in the Beaufort Sea, Chukchi Sea and northern Bering Sea. Final Report: Fall 1980. Tech. Doc. 449, Naval Ocean Systems Center, San Diego,
CA. 211 p.
LJUNGBLAD, D. K., M. F. PLATTER-REIGER, and F. S. SHIPP, Jr., 1980. Aerial surveys of bowhead whales,
North Slope, Alaska. Final Report: Fall 1979. Tech Doc. 314, Naval Oceans Systems Center, San
Diego, CA. 181 p.
MAcGINITIE, G. E., 1955. Distribution and ecology of marine invertebrates of Point Barrow, Alaska.
Smithsonian Misc. Coll. 128 (9). 201 p.
MARQ,UETTE, W. M. Bowhead whale. Pages 71-81 in D. Haley, ed. Marine Mammals of Eastern North
Pacific and Arctic WateIT. Pacific Search Press, Seattle, WA.
MITCHELL, E., 1975. Trophic relationships and competition for food in northwest Atlantic whales. Pages
123-133 in M.D.B. Burt, ed. Proceedings of the Canadian Society of Zoologists Annual Meeting, June
2-5, 1974.
NEMOTO, T., 1957. Foods of baleen whales in the northern Pacific. Sci. Rep. Whales Res. Inst. 12: 33-89.
NrsHIYAMA, T., 1977. Food-energy requirements of Bristol Bay sockeye salmon, Oncorhynchus nerka (Walbaum), during the last marine life stage. Res. Inst. N. Pac. Fish. Hokkaido Univ., Spe. Vol., 289-320.
PERCY, J. A. and F.J. FIFE, 1980. The proximate composition and caloric content of arctic marine invertebrates from Frobisher Bay. Can. Data Rep. Fish. Aquat. Sci. 214: iv+35 p.
PERCY, J. A. and F. J. FIFE, 1981. The biochemical composition and energy content of arctic marine macrozooplankton. Arctic 34: 307-313.
RAY, G. C. and D. WARTZOK, 1980. Remote sensing of marine mammals of Bering Sea. Final Rep. Con
tract No. NAS2-9300 submitted to Natl. Aeronautics and Space Admin. 77 p.
ToMILIN, A. G., 1957, Cetacea. In V. G. Heptner, ed. Mammals of the USSR and Adjacent Countries.
(Trans!. from Russian by Israel Program for Scientfic Translations, 1967 .) 717 p.
TYLER, A. V., 1973. Calorific values of some North Atlantic invertebrates. Mar. Biol. 19: 258-261.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

OBSERVATIONS ON THE OCCURRENCE AND
BEHAVIOUR OF MINKE WHALES OFF
THE COAST OF BRAZIL
K. V. SINGARAJAHLaboratory of Marine Biology & Comparative Physiology, Department of Systematics & &ology, CCEN,
Federal Universify of Paraiba, Joao Pessoa-58000, BRAZIL
ABSTRACT

Field observations on minke whale morphology and physiology, the hydrography and topography of the Brazilian whaling ground and catch statistics from 1963 to 1982 are presented.
In the past 20 years, 12,494 minke whales have been taken off Brazil;
only 3 were taken prior to 1963. Of those animals thought to be mature,
females predominate in the catch (sex ratio, 2 females: 1 male). The population appears to remain at an exploitable level, although other species in thearea have been considerably reduced.
The most important environmental conditions associated with the arrivalof the minke whale in these tropical breeding grounds appear to be an optimum temperature of 26-27°C, day-length, reduced turbulence and an amiablesurface current.
The behaviour of minke whales in response to various stimuli is described,
and in particular their escape reactions, normal swimming speeds, co-ordinated swimming, affinity for mates and response to electric shocks.
INTRODUCTION

The minke whale, Balaenoptera acutorostrata (Plate I), is one of the most valuable
marine mammals and is now the most common species of baleen whales in the
Antarctic. Perhaps, due to its high yield of meat, relative to the rest of the components (Table 1), this species has become an important natural food resource andthus making the commercial whaling economically viable. Despite the claims thatthe minke whales are increasing in the Antarctic and now considerably more abundant as they were in 1910 (FAO, 1982), the exploitation of this species is regulated
by IWC.
The minke whales taken off Brazil are considered as a part of the Area II
management stock as defined by the IWC (0°-60°W) although there is some controversy over the applicability of these Areas (originally developed for blue and fin
whales) to minke whales (IWC, 1981; 1982). However, much of the whaling
would depend on natural population which varies both geographically and seasonally due to fluctuations in the rate of recruitment, mortality, including level of exploitation, growth rate, supply of planktonic krill as food (Ohsumi, Masaki and
Kawamura, 1970; Ohsumi, 1979) and other causes of environmental factors. The
catch statistics and catch per unit effort (CPUE) values over the past 20 years have
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 17-38

18

SINGARAJAHTABLE 1.

PRIMARY MATERIALS DERIVED FROM MINKE WHALES BASED ON
ACCUMULATED FACTORY DATA

Primary Products

1.
2,
3.
4.
5.

6.
7.
8.

Mean Weight (Kg/Whale)

%

Meat
Bone
Cartilage
Baleen plates
Viscera: Tongue
Lungs
Heart
Kidneys
Liver
StomachIntestine
Blubber : Dorsal
VentralFins
Lost Materials: Blood etc at sea & factory

3,500
l,260
7
35
70
56
21
14
63
14
63
980
280
42
595

50.00
18.00
0.10
0.50
l.00
0.80
0.30
0.20
0.90
0.20
0.90
14.00
4.00
0.60
8.50

Total

7,000

100.00

shown that the recruitment of this species in this area has remained very constant(Singarajah, 1983). With the advent of their breeding seasons, the minke whales
arriving off Brazil are characteristically migratory, but the reasons to select thisarea as their breeding ground with such regularity are little understood.
Previous work on Brazilian minke whales is scanty (Williamson, 1975) and in
this paper some aspects of minke whale biology are examined and the feasibility ofcontinuing to exploit this species, together with some of the factors which may
influence their migratory behaviour to the breeding ground off Brazil, are discussed.
MATERIALS AND METHODS

Field observations were made on board the catcher boat Caho Branco. The normal
operation pattern is that the boat leaves port at about 0330-0400 hours and returns to the factory with its catch at about 2230-2300 hours. Samples were taken
both on board the catcher and at the factory though most measurements were madeat the latter.
Past data on catches, lengths, reproductive state of the whales and information on stomach contents were kindly provided by SUDEPE (Superintendencia Do
Desenvolvimento Da Pesca) but some of the early data were missing or consideredunreliable. The selected data, covering the whole period of minke whaling, werethen transferred to an IBM computer for processing. Blood counts were made on
board the catcher; most observations on behaviour patterns were confirmed byphotographs, 35 mm colour slides and "Super 8" cine films. Where necessary,
appropriate parts of the whale, including entire baleen series, were transported to
the laboratory for confirmation.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF MINKE WHALES

19

RESULTS
MORPHOLOGY

General appearance:

The minke whales are the smallest of the rorqual whales which
are well adapted for exclusively marine life. The body is somewhat less streamlined with triangular and dorsoventrally compressed head with a strong central
ridge (see Plate I). The paired nostrils or "blow holes" are situated at thesummit of the head about a metre from behind the tip of the snout which isabout 8 cm shorter than the lower jaw. The blow holes are highly dilatable, especially when the animal gasps for breath, which otherwise remain closed by valvelike muscular folds of skin. The blow holes lead to a common median tubular
canal about 50 cm long and 8 cm in diameter before leading to the tracheae.
The eyes are small, when compared to the huge body, and dorsolaterally
placed. The eye-ball, on dissecting out, measures about 10 cm in diameter andwell controlled by the powerful eye muscles and the optic nerve.
No external ear is visible, but the external ear aperture is a horizontal slit ofextremely small size, about 5 mm long; normally remains closed by valvular folds
within a narrow groove about 9 mm wide and 9 cm long. The centre of theaperture lies about 44 cm behind and on the same level as the eye. The external
aperture leads into a complicated tubular canal which is about 6 mm in diameterand its inner surface is lined by fine longitudinal grooves and ridges and having
the same colour as the skin, perhaps due to invagination of the skin. The canal,
after running about 8 cm towards the tympanic bulla, leads into a "gizzard-like"structure which is often filled with bone marrow-like substance. The canal is now
continued from the centre of one side of the muscular gizzard structure and extends
until it establishes contact with the ear plug. The conical ear plug (Plate II) fitsclosely over a membranous, but strong, teat-like structure or "glove finger" (Plate
III) and similarity in ear aperture was noticed in fin whales (Laws & Purves, 1956).
The broad margin of the glove finger is attached to the hollow part and surroundedby the bony elements in the posterior-ventral region of the tympanic bulla. The
canal, connecting the gizzard-like structure and the ear plug, is smooth and devoidof any ridge or groove and the grey colour is generally lacking. The ear bones or
tympanic bullae are kidney-shaped, each about 9 cm long and 6 cm broad andweighing 450 g wet and 250 g dry weight. It is perhaps the hardest part of thewhole body and is located just anteriodorsal to the foramen magnum and is separated from the external aperture by about 50 cm, on each side.
Ventral grooves: The ventral grooves run lengthwise and parallel to one anotherreaching anteriorly the chin and posteriorly close to the umbilicus, and extend
laterally to a line between the eye and the flipper insertion. The median groove
extends from the posterior end of the mandibular symphysis to just short of theumbilicus. This distance between the end of the median groove and the umbilicus has a mean of 84.9 cm, though it varies in the different sexes. However,
the minimum distance between the umbilicus and the nearest 6th groove, on either
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SINGARAJAH

20

side of the median groove, remains constant in both sexes at 40.7 cm. This observation is in close agreement with measurement given by Ohsumi et al. (1970) to
the Antarctic minke whales.
The number of ventral grooves of 660 animals (223 males and 437 females)
were counted in 1979 and the mean number in both males and females was 47 (8).
Da Rocha (1980) examined 220 males and 452 females and her values (for half thetotal number) were 21 for males (range 16-35) and 22 for females (range 15-31 ).
The difference in the values may be due to differences in the method of counting; in da Rocha's study, the grooves were counted while the whales were lying
in their sides on the flensing platform; while in the present study the grooves werecounted while the whale was tied by its tail alongside the vessel, which facilitatedthe counting.
Skin and colour pattern: The skin is about 3 mm thick, smooth and slippery, supported by a thick layer of panniculus adiposus or the "blubber" from below(Fig. 1). The colour of the skin changes from dark grey on the dorsal aspect of
the body to creamy white ventrally. The dark grey colour continues from tip of
the snout to the dorsal surface of the caudal fluke, but dips down just below theeye and the dorsal end of the flipper insertion to form a small arch and again midway between the flipper and the caudal fluke thus forming a wider arch; the end
6

5

E

0

Cl)
Cl)

0
... ....
'

4

UJ

z

@
..... ....

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

~

0

®

.... .....

-.....

:c

~

a:

UJ

3

@

@

0

..... d-- ------------

@

@

G3)

@

@

@

J

A

s

0

N

D

CD
CD

:::>

...J
CD

MONTH
Fig. 1. Blubber thickness of males and females of the same whaling season.
bers shown within circles represent mean sample.

Num-

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF MINKE WHALES

21of this second arch then curves up, like a broad inverted dorsal fin, to a medianlateral line to merge with the dorsal surface of the fluke, on each side. The cream
colour extends from chin to the caudal end, including the ventral surface of the
fluke though the margins of the latter are usually edged with dark grey. The
creamy bracket marks above the flipper are usually inconspicuous.
These colour patterns are essential in identifying the Antarctic stocks of minke
whales, and seem to be of adaptive value. Usually with the slightest tilt of the
body in the water, these peculiar colour patterns cause to reflect a bright bluishgreen light, particularly when the whales swim up side down, which enables them
to be easily recognized from a distance of about 800 meters.
Jaws: The two jaws are symmetrical, but the lower jaw is about 8 cm longer
than, and protrudes beyond, the upper jaw (see Plate I). The upper jaw on eachside measures, on an average, 186 cm between the tip of the snout and the gape ofthe mouth. But, beyond this point, the baleen laminae are carried in by a shortsegment, about 28 cm long, which curves inward and terminates bluntly as a triangular end. It is along this rear end that the greatest number of smaller baleen
laminae are arranged in multiple rows.
Baleen plates: The strongly keratinized horny structures though called baleen
plates, all are not truly plates. These horny structures are fused together attheir top ends by interlaminar cement-like substance to form the " baleen series "(Plate IV) and suspended from each side of the upper jaw. The cemented part,which apparently represents the "gum", varies in height and width according to
the size of the plates inserted.
On the basic characteristics of size, shape and position, the plates could begrouped into mainly four categories:
1. The smallest rod-like structures in the anterior segment of the jaw, usually
8 in number, are arranged in double rows fairly close to each other. Each ofthese rod-like structures measures about one cm from below the line of fusionand provided with usually 4 very stiff filaments (Plate VA).
2. These are followed by the transitional plates which are small rectangularlaminae and variable in number (Plate V B).
3. Next in series, occupying the major part of the jaw, are the larger plates, on
an average 237 of them, arranged transversely at intervals of 0.4--1 cm between laminae. They are inserted by the smallest side and run undivided
between lingual and labial margins in a single row (see Plate IV). However,the size of the individual plates varies and the largest plates are always confined to the mid-region while others, in gradually diminishing order of size,
run towards both extremities of the jaw until they merge with the transitionallaminae. These laminae are not typically triangular as commonly described,
but rather combinations of inverted triangles and rectangles; the triangularpart increases in size at the expense of rectangular part as the plates reach the
mid-region of the jaw. The labial side of the largest plates measures about
40 cm and is smooth and devoid of any filaments, but on the lingual side only
the hypotenuse, just below the rectangualr part, is frayed out into fine flexible
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

22

SINGARAJAH

filaments (see Plate IV). The filaments also vary in number and length; thelargest plate on the average consists of 380 filaments and the longest of thesebeing 10 cm.
4. By contrast, the " plates " on the rear end of the baleen series are very much
reduced in size, about 2 cm tall and rectangular type of laminae which aredisproportionally numerous and grossly overlap and relatively difficult tocount, unless the series is cut into segments. The bristles are less stiff andvary between 4 and 12 per plate (Plate V C).
Perhaps for this reason, Williamson (1973) concluded that for rorquals, it was
too difficult to accurately count the rear plates and he called them, including theanterior rod-like plates, as "hairs". Previous studies (van Utrech et al. 1978;
Ohsumi et al. 1970; da Rocha, 1980) have clearly not included all the "hairs"in their counts. Best (1978) followed the procedure followed by Williamson (1983).
During the 1981 season, the baleen plates from 26 whales, 13 males and 13
females, were examined. Except for the colour pattern, no asymmetry was observed between the right and the left hand side of the blaeen series. The baleen
laminae can be further divided into 3 on the basis of colour: (i) creamy white;(ii) creamy white with black edge and (iii) black (see Plates IV & V). The results
are given in Table 2. The baleen series on the right side comprised an average of
111 all white plates, including the rod-like "plates" or "hairs", at the anterior
end, covering about 50 cm of the jaw. The plates in the mid-region comprised
an average of 127 white/black plates. The posterior all black laminae include
about 87 plates and about 2,050 smaller laminae. The pattern on the left handside is the same but the proportion of all white plates is lower; on average there are
only 63 all white plates covering 20 cm.
While the function of the colour difference on the two sides remains curious,
but the enormous number of the smaller laminae, though look vestigeal in form,
are adaptations that are functionally more evolved to increase the efficiency andrapidity perhaps during filter-feeding.
Flippers: Between 1979 and 1981, 1,745 animals, 619 males and 1126 females,
were examined for flipper colouration. The flippers are elongated and more winglike. There appeared to be no difference between the sexes; the flippers are about
1 m in length (Plate VI) and 30 cm wide, being light grey apart from a dark grey
calyx shaped on the dorsal surface next to the body. No white stripes were observed in Brazilian minke stock, but the under margins turn out to be slightly
TABLE 2.

MEAN NUMBER OF BALEEN LAMINAE FOR MINKE WHALES FROM BRAZIL
Colour pattern

Males
Females

right
left
right
left

(i)

(ii)

(iii)*

106.6

128.3

73.7

156.7

116.0
51.8

126.3

2131.5
1913.02051.02112.0187.5* posterior black laminae are from approximate estimates.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

23

BEHAVIOUR OF MINKE WHALES

whitish.
Flukes: In 1980, the flukes from 49 animals, 20 males and 29 females, were examined. The flukes were on average about 118 cm in length, and narrower inmales than in females. The notch was about 7 cm deep and 4 cm at its widest
part. A considerable strength is centered just anterior to the fluke, the tail-stock(Pl. VII).
Dorsal fin: A fleshy dorsal fin about 38 cm in height is situated about two thirdsof the length of the body, more proximal to the flukes, and neatly curved (Pl.
VIII) pointing caudally. Both dorsal fins and caudal flukes are devoid of any
bony elements.

.,.
Fig. 2. Positions of minke whales caught during 1980 season, superimposed on tract
chart. The broken line represents the continental edge of Brazil and the discrete
numbers indicate depths in meters.
Sci. Rep, Whales Res. Inst.,
No. 35, 1984

24

SINGARAJAH

Hairs: Very few hairs were seen; usually on the rostrum and on the sides of themandible. The hairs, particularly from the latter, arise from 7 small pits (each*0//......_____... ,,..

40

/

/

cTP
~

80

tsO

40

20

0

20

Fig. 3. Surface currents and an isothermic stretch of the whaling area off Brazil, in
the Southwest Atlantic. Surface temperature distributions are based on 20 years
daily recordings during each whaling season.
* Since this paper going to the press, asymmetrical disposition and variation of number of pits, particularly
in a few females had been observed.

Sci. Rep. Whales Res. Inst.
No. 35, 1984

BEHAVIOUR OF MINKE WHALES

25side). The hairs are creamy colour and about 4 cm tall and can be easily pulled out.
External sexual characteristics: As in the other whale species, the vaginal orifice lies
immediately anterior to the anus whereas the penal slit is clearly separated fromthe anus. In many females a creamy yellow substance was found in the vagina;
which may have meant that they had recently copulated. Histological analysis
is required to confirm this ..
WHALING AREA

Topography and hydrography: The tract records of the whaling boats over several
years reveal the whaling grounds off Brazil, which extend from 6°-8°lO'S and
32°20'-35°00'W, to have remained very constant. The continental shelf extends to about 20 miles from the coast where it drops abruptly from 60 m to
3-4,000 m (Fig. 2). The sea floor in the shelf area is irregular and rocky. The
most important hydrographic feature of the area is its proximity to the equatorial
current systems. The south equatorial current flows westwards near the equator
towards South America. On reaching the Brazilian coast it divides into two:most of the warm water moves northwards towards the Caribbean while theremainder turns south forming the weak Brazil current. This meets the cold
Falkland current (Fig. 3). The whaling area is largely under the influence of thesouth equatorial current. From June, when it is particularly strong, to September,
TABLE 3. MONTHLY MEAN TMPERATURES (°C) BASED ON DAILY RECORDINGSFROM JUNE TO DECEMBER EACH YEAR OF THE WHALING AREA, LAT.
6°S-8°10'S AND LONG. 32°20'W-35°00'W.
Year
July
June
26.10
1963
*25.00
27.12
27.23
1964
26.98
1965
27.35
27.14
1966
27.70
26.70
1967
27.45
26.41
1968
26.10
26.42
1969
27.73
26.80
1970
27.20
27.10
1971
27.80
27.60
1972
28.00
27.60
1973
28.10
27.60
1974
27.80
27.50
1975
27.90
26.90
1976
27.30
1977
28.30
28.30
1978
1979
27.40
27.80
1980
28.50
1981
27.62
1982
27.89
* Based on only 4 days recordings.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

August
26.05
27.74
26.26
26.64
26.16
26.01
26.77
26.40
26.50
27 .10
26.40
26.40
26.70
26.60
28.00
26.90
27.50
27.70
26.86
27.38

September
27.74
27.00
26.97
26.15
26.13
26.01
26.80
26.40
26.40
26.90
26.80
26.80
26.60
26.60
26.60
27.00
27.70
27.40
26.91
27.25

October
26.35
26.35
26.71
27.01
26.95
26.80
26.74
26.90
26.50
27.00
27.00
27.00
27.10
27.00
26.90
27.40
27.80
27.60
27.77
27.53

November

26.71
26.42
27.02
27.03
27.90
26.90
27.30
27.90
27.90
27.60
27.40
27.70
27.70
28.00
27.90
27.84
27.70

December

27.56
27.00
27.80
27.80
27.80
27.80
27.80
27.80
28.40
28.10
27.83

SINGARAJAH

26

TABLE 4. SOME ENVIRONMENTAL PARAMETERS OF THE WHALING AREA OFF THE
COAST OF BRAZIL (LAT. 6°S-8°10'S AND LONG. 32°20'W-35°00'W), AVERAGE BASEDON *DAILY AND **MONTHLY RECORDINGS DURING 4 YEARS 1979-1982.
Month

Current velocity*
Knot/Hr

Salinity**%0

Oxygen**ml/I

Extinction**
Coefficient

June
July
AugustSeptember
OctoberNovember
December

1.04
0.97
0.83
0.98
0.74
0.60
0.60

34.60
34.82
35.00
35.00
35.40
35.50
35.50

7.80
8.04
7.60
8.20
7.90
8.00
8.20

0.15
0.90
0.11
0.09
0.10
0.14
0.17

there is a strong southerly wind, which from mid-September until December becomes easterly.
Measurements of temperature, current velocity and salinity (Tables 3 and 4)
reveal that the temperature and salinity remain fairly constant throughout theyear. The velocity of the current decreases from 1.04 knots in June to 0.60 in
December. Visibility under water improves considerably after July partly due todecrease in precipitation.
Biotic factors: Flying fish, Exocoetus sp., are very common in the whaling grounds
and schools of dolphins (12-20 animals) are also often seen. The whale louse,
Ovamus balaenopterae, is- found on minke whales (Ohsumi et al., 1970). As thewhales move into warmer waters, these ectoparasites fall off, probably in response to the warmer water, leaving small oval shaped scars which are about
5 cm X 4 cm X 4 cm. The large white shark, Carchardon carcharias and the hammerhead shark, Spkvrna zvgaena are quite common in the whaling area, and often tear
chunks of meat from the ventral side of dead, buoyed whales. Occasionally, Remoras or suckerfish and lampreys were seen to be attached towards the ventral
side of the buoyed whales.
BEHAVIOUR

Behaviour during the hunt: Off Brazil, minke whales are commonly seen in small
groups, 2-6 animals, and only rarely as singles or in larger groups, about 10-14
animals. The animals in pairs swim fairly close to one another (10-12 m) andsometimes very close. Undisturbed minke whales swam at about 8-10 knots;
estimated by comparison with the velocity of the boat. Some authors (Kasuya
et al, 1965; Mitchell, 1978) have reported "ship seeking" behaviour for minke
whales although no such evidence was found in tropical waters and the minke
whales off Brazil appeared to be indifferent to the presence of the vessels.
Absence of" ship seeking" behaviour in the Antarctic minke whales also has beenreported particularly during the last IWC/IDCR cruise (IWC, 1982).
During chasing, the whales can swim faster than the boat (17 knots) for shortperiods. However, after about 10-12 n miles they surface regularly and more
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF MINKE WHALES

27

frequently, often cutting right across the bow of the ship, when, of course, they areeasy to harpoon. When hit with the harpoon some animals attempt to escapewith such force that they break the loop encl of the whale line and swim rapidly(estimated at about 24 knots) away, usually following a fairly straight course andprofusely bleeding which was traceable for more than a killometer. In all harpooned whales, it was noticed that the spray of water during blowing was mixed
with blood. Direct evidence indicated that this was due largely to rupture ofblood vessesls, even though an explosive charge in the lungs could not be ruled out.
Epimeletic behaviour: On one occasion, a pod of three whales, later found to be
two females and one male, were pursued at full speed. A female was harpooned
and was eventually brought to the ship, during which time the other two whales
remained with the female, swimming in large circles around her. Within anhour the second female was harpooned and took out the full 700 m whale line,
diving and circling in an attempt to escape. During this time the male swam close
to the female, diving and blowing in synchrony. This continued for some 13
minutes before the female was brought to the side of the boat and killed by electricution. Even then the male made no attempt to escape and fell easy prey tothe gunner.
Electric shocks: Most of the harpooned whales do not die instantly and are
frequently winched back and shot a second or even a third time after which an
TABLE 5. COMPARISON OF CATCHES, SEX RATIOS AND PERCENTAGESOF MINKE WHALES FOR THE PERIOD FROM 1963 TO 1982.
Year

Male

Female

1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
Total

16
26
119
154
151
204
227
330
231
210
246
380
279
330
225
242
315
244
288
4,217

2
28
42
233
334
305
413
474
570
470
440
515
658
497
664
463
496
587
504
566
8,261

* Due to loss
Sci. Rep. Whales Res. Inst.,

No. 35, 1981

In determinate*

4

6
2

16

Total

Sex Ratio
Male : Female

CHI Square/P
Values

2
44
68
352
488
456
617
701
900
702
650
765
1,309
776
1,000
690
739
902
749
854
12,494

1 : 1. 75
1 : 1.62
I : 1.96
1 : 2.17
1 : 2.02
1 : 2.02
1 : 2.09
1 : I. 70
l : 2.03
l : 2.10
l : 2.09
I : I. 73
l : I. 78
I : 2.01
l : 2.05
1 : 2.05
1 : 1.86
I : 2.25
I : 1.96
1 : 1.95

0.06<0.8
0. 73>0.5
0.04<0.9
0.69<0.5
0.01>0.9
0.02<0.9
0.28<0. 7
4.01<0.5
0.33>0.5
0.15<0. 7
0.87>0.5
5.21<0.l
2.04>0.2
0.01>0.9
0.92<0.8
0.09<0.8
1.03<0.3
0.17<0.7
0.06<0.9

SINGARAJAH

28

electric shock is applied. Initially intermittent shocks are applied to which thewhales respond violently. After these, a continuous current is applied for threeminutes during which even the strongest whale becomes restrained, apart fromsome lashing of the flukes. This is soon followed by the drooping of the lower jaw.
Perhaps, it might be safest for the crew to wait until the lower jaw droops before
tying the whale to the ship.
CATCH STATISTICS FOR BRAZIL

Paiva (1961) and Williamson (1975) gave some details of catches from Brazil forthe period of 1910, when whaling began, to 1974, but these include mostly thelarger species. Prior to 1966, larger whales (humpbacks up to 1928 and then sei
and Bryde's whales and occasional blue, fin and sperm whales) dominated the
1963
1965
1967
1969
1971
1973
1975=---~.:...:,-:-_:_~-'-"r'-=--~...:...:;-::_:__~---.
197'7
1979
1981
1800 r---.~~-r~~-.~~--.~~~-'--'--~---'-'-i-'----'--~_:_:_r,

~

•I

,'''

.

' ',

1600

,
,
/

'

,,di
;"

1200

• •, ••-•, -- • •, •• J

J•I••••',\•-04-:-.-:0.'". • • • • •

,..

..

9....

'

:

: .

I

'

I

·I

\

I

/

1

••',II•,

~

•

•

0

•

•

•

;' ...

I

-·

"'•

I

.\/.

•

Q

•

•

••

,.\.

,,,

''

,I ' • • •

\\. /
•

0• •••

0

I

I

\

,J:>

'\\

/I

\

/

~

/

ft,

l

\

l

b',

I

1000

:

'

1400

,.
,' '.

?.

"

; \

I

.... .dQ.-"'','O', ....

,/

~000~-~"--·~~~-9~'/_·~--~~~~,______,,_~--~-1-~~~~---1~~-1-~---'.---+~--"1
~

lJ..

0

a: 600

~

::>

z

400

200

'

100 ~~~~-~~~~~~~~~~~~~~~~~~~--'--~~--'-~~--'--~~---'---"'
1964

\9 66

1968

1970

1972

1974

1976

1978

1980

1982

Fig. 4. The relationship between catch (e) and sighting (O); the pattern of minke
whales caught fluctuates almost correspondingly with changes in population sighted.
M indicates means.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF MINKE WHALES

29

catch. Only 3 minke whales were taken prior to 1963. However, catches of minke
whales increased only during the last 20 years (Singarajah, 1983) while most of
the others are now protected.
Table 5 gives details of Brazilian catches between 1963 and 1982. The season
generally lasts from June to December but for a variety of reasons no whaling occurred in either of those months in 1967, 1968, 1971, 1976, 1978, 1979 or 1981.
During the period 1963-1982, 12,494 minke whales have been caught: prior to1963 3 were caught making a total for the area of 12,497.
Fig. 4 shows the number of minke whales sighted and the number of minke
whales caught between 1963-1982.
SEX RATIO

Fig. 5 shows the catch composition by year and month for the greater period ofminke whaling and the average lengths of males and females. There is a significant difference between .the number of males and females in the catches and theoverall ratio is 1 male: 1.95 females; not significantly different from 1: 2. Thisremains fairly constant by month although the percentage of females is lowest at
the beginning of the season (Fig. 5). This factor, along with the sex ratio in
captured schools, often 1 male: 2 females or 2 males: 3 +females, may suggestthat minke whale are not monogamous.
DISCUSSION

Although a comprehensive anatomical description of southern minke whales has
been given by Ohsumi et al., (1970), the present study has provided additional information with respect to the whales off Brazil. Despite somewhat vestigeal inform and character, the omission by previous workers (Williamson, 1961; van
Utrecht et al, 1962; Ohsumi et al, 1970; da Rocha, 1980) to include in the countof the very large number of the baleen plates of the posterior segment was perhaps
solely due to their size. Nevertheless, these are true baleen plates and they could
not be justifiable excluded.
Variation in flipper colour patterns have been described by several authors(Taylor, 1957; Williamson, 1959; Ohsumi et al, 1970; Doroshenkho, 1975; Best,1978). Data from Brazilian operations show that a single flipper type, devoid ofa white stripe, predominates. However, on rare occasions (e.g. in 1980 and 1981,
about 0.2% of the annual catch) a second type, with a white stripe, was recorded.
The animals were small, about 7 m, and Best (pers. commun.) informed me that" they might be a diminutive form of the species ".
The morphology of minke whales off Brazil and in the Antarctic and the temporal distribution of the whales strongly suggest that the whales migrate between
these two areas. Data collected over several years on the distribution of minke
whales off Brazil clearly show that they generally occur in a relatively small area(< 15,000 n. miles 2 ). Their high density in this tropical habitat is further confirmed by the CPUE estimates.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

~.:~

~~

...v-i ~"'~ "'t;:i

~
~
~ 1"'

~

:::i

0

U-

20

40 -

60

80

100

12 0 -

140

160 -

18 0

200

220

240

260

J J

I

:

:

'

'

!\
':

1974

/\,

"

;;

/\

NDIJJASQND
1975\\
AS Q N D lJ J AS 0 N D IJ J A S 0 N 0 IJ J
1976
1977
1978

!\
'"

]\
!\

/\
/ \

AS 0 N 0
1979

r·

!\
f\

""

!:

j\
!\
i '

0

4

10

M

19 60

1981

1982

iJ J AS 0 N DI JJ A S ON O IJ J AS 0 ND

Fig. 5. Relationship between numbers of males (solid line) and females (brokenline) minke whales taken monthly. Open histograms compare the mean lengthsof males and females on yearly basis.

197.3

!(\
;I
}

''

""

A S 0 N D 1J J A S 0 N D IJ J
1971
1972

'

~ ~ ~J ~ ~~ ~~ j~ ~~ ~~. ~~ ~ ~~

iJ ~

~

~

i'::I

rJJ.

zg;

""0

BEHAVIOUR OF MINKE WHALES

31

The concentration of the minke whales into this area for breeding is presumably a result of the physical and biotic characteristics of the environment. Temperature and perhaps day length seem likely to be important factors influencing
the migrations of whales. Minke whales begin to arrive in the region in the latterpart of June, although the peak months are September, October and November bywhich time:1) precipitation has considerably diminished;2) the strong SE wind has changed to a moderate E wind concomitant with
reduced turbulence;3) the water is more transparent;4) the temperature has dropped very slightly (perhaps to an optimal level);5) the surface current is less strong;
and these factors may influence the minke whales. However, it must be remembered that the first three points also have the practical effect on making the whales
easier to see and so the increase in sightings may to some extent be due to this. In
addition, the increasing numbers of whales from June to September may in fact
have more to do with the conditions in the Antarctic which affect the rate of leaving there rather than the prevalent conditions on arrival off Brazil.
It is interesting to note that the testes from males which were caught in thepeak period are generally larger than those taken earlier (Table 6 and Fig. 6). A
similar trend is seen in ovary weights although the range is greater.
As yet, we have not found a satisfactory technique for estimating the age ofthe minke whales taken off Brazil: Christensen's (1980) method using the tympanic bullae was tried but found to be too tedious for routine samples; problems
were also found with the reading of ear plugs, particularly of younger animals, andoften the counts of the left and the right plugs were different. As a result of thiswe have no estimate of age at sexual maturity for the animals off Brazil.
Masaki (1979) examined age at sexual maturity in minke whales taken by
Japanese expeditions in the Antarctic using four techniques: (i) the age (from ear
plugs) at which 50% of the animals are sexually mature, i.e. have either at least
one corpus luteum or albicans, or have one testis of at least 0.4 kg; (ii) the relationship between age (from ear plugs) and the number of ovulations; (iii) using
length at sexual maturity and the growth curve (age from ear plug); (iv) from thetransition phase of the ear plug. The results from all four methods suggested afemale age at sexual maturity of about 6-7 years. Direct evidence for males wasmore limited due to the scarcity of immature animals in the catches and the need forfurther histological analyses to confirm to 0.04 kg criterion of Ohsumi et al. (1970).
However, assuming that the transition phase in the ear plug was formed at sexual
maturity then the age at sexual maturity for males was about 6 years. If the 0.4 kg
criterion is true then almost all the males caught in Brazilia:n waters are mature(Table 6). Using the maturity criterion of technique 1, da Rocha (1980) estimated the lengths at maturity of males and females off Brazil to be about 25 ft and26.5 ft respectively. This is slightly higher than Masaki's Area II values of 23.3 ft
and 26.1 ft.
Sci. Rep. Whales Res. Inst.,
No. 38, 1984

32

SINGARAJAHTABLE 6.
Weight
(g)
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1,000
1, 100
1,200
1,300
1,400
1,500
1,600
1,700
1,800
1,900
2,000
2,100
2,200
2,300
2,400
2,500
2,600
2,700
2,800
2,900
3,000
3,200
3,400
3,600
3,800
4,000'
4,200
4,400
4,600
~
Mean
Combined Mean
Overall Mean=FREQUENCY DISTRIBUTIONS OF WEIGHTS OF TESTES
August

July
Left

Right

1
2

I
I

1

2

September

Left

Right

1
1
3
I
I
4
3

1
3

Left

Right

2
I
1

1

2
4
2

2
I

3

2
1
4
I
2

4
2
3

2
2
I
2

1
2

3

1

2
2

1

2
1

2
2

3
1

2
2
2
1
1
1
2
2
1

1
4
2
3
2
1
2
1
2
1

1

1

8
1
1
3
1
1

1
1
1

3
1
2

4

3
1

2

2
1
2

20
1,052.5
1,076.320
1,100.043
42*
1,296.5 1,207.5
1,252.4
1,428.53

41*
1,237.8
1,240.4

42
1,242.9* 1 lost during !lensing.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVlQUR OF MINKE WHALES

33

OF BRAZILIAN MINKE WHALES BASED ON 1979 SEASON
OctoberNovember

Left

Right

2

2

December

Left

Right

2
2

2
2
I
2
2
3

Left

Right

I

2

2
4
2
I
3
I
4
II
3
2
6
2
2
6
I
3
2
I
1

I
I
3
I

3
I
4
I
I

ti
12
3
2
8
I
2
2
2
6
2
4
I
2

I
1
2
1
1

75

75

1,386.7
1,408.0

1,429.3

Sci, Rep. Whales Res. Inst.,
N. 35, 1984

I

2
I
2
4
4
3
6
3
3
2
2

2

2
I
I

2
2
I

2
I

1
2

14
1,877 .4
1,867 .9

14
1,864.3

8
3
4
I
5
2
1

2
3
2

2
3

47
1,839.4
1,836.147
1,833.3

SINGARAJAH

34
JULY

Ali GUSTSEPTEMBEROCTOBER!o:oo_

2500

20.oO

! ooo -

50 0

10 0

,

r

-~,,~~-,;--~--.',,r-~-,,-~~~,,,--~~o:--~-.,,~~~-,c--~--,>--~----0~~~,<5~--,;--~--,.,,NUMBERQF

TESTES

EXAMINED

Fig. 6. Weight frequency histogram for the testes of minke whales caught off thecoast of Brazil during the 1980 season.

Masaki (1979) estimated the gestation period for minke whales to be about 9
l /2 months, with the peak mating period in early to mid-October and the peakcalving period in late July using the method of Laws (1959), and data from thewhole Antarctic. If this is true, then if the waters off Brazil were calving grounds,
one might expect to see large numbers of calves in the area. However this is not
the case. This may be because the females calve elsewhere or because calving occurs much later in the season. If the latter is true then one might expect to finda high proportion of pregnant (near term) females in the catch in the early part ofthe season, decreasing as the season progresses. Unfortunately, there are few reliable records on pregnancy off Brazil to date.
Population estimates of minke whales in southern hemisphere is far fromcomplete at the present; and there is no close agreement among previous estimates(Ohsumi et al, 1970; Williamson, 1975; Best, 1979; Chapman, 1979; Holt, 1980).
Although minke whales in the Antarctic are claimed to be increasing (FAO, 1982),
Watson & Riche (1981) place the population of southern minke whales at
150,000-300,000. However, the minke whales arriving off the coast of Brazil tobreed are variations of the southern stock (Williamson, 1975), but no estimates on
absolute population for the Southwest Atlantic has been worked out. Recent
Sci. Rep. Whales Res. Inst.,
No. 35, 1981-

BEHAVIOUR OF MINKE WHALES
30.17

34.51

38. 84

43. 184 7. 52

56. 2051 .86

35
60.53

64.87

69. 211975 •

61 18. 00

5732. 30
•

!977

1982
1980-

5346. 60

4960.90
1978

•

1976

;;;

"z 4575. 20
;;\

1979
1974

:0

~
!::; 4243.95'\

"'z

•1901

1972

4189.50
.1971

g

=:

... 3803. 80
"'
!ii

1969

"'

3418.103032.402646. 70.
2539,33..J:

2261. 00

•1968

196 6

20~.-oo--''--3-z.~34~'--=,-s~.6-8~-4-,~.0~1--'---,-4~5.~35~----:-4~9.~ss=--~5~4~.o-3~-5~0~.3~7~-:c62~.1~0~----=-6~1.~04-;---"--:;1~1.38
G /~Fig. 7. Correlation between the catch per unit effort (C/E) and the abundance ofminke whales. Regression line calculated from 17 years consistent data.

marking experiments to relate stock identity and estimates of its population have
met with only limited success; of the 29 minke whales marked off the coast of
Brazil (Butterworth & Best, 1982) none so far has been recaptured.
The regression line (Fig. 7) for the more consistent peak seasons, covering
almost the entire minke whaling period from t.he Brazilian whaling ground, showsthat the relationship between catch per unit effort and abundance is fairly constant with a few exceptions. The significant variablity in abundance particularly
during 1966, 1971, 1977 and 1981 might be due to a variety of causes, the chief
being operational and other factors peculiar to Brazil, including the quota system
imposed by IWC.
Sex data, throughout the whaling period, both monthly and annual catch,show characteristically that the females far out number the males, and these observations are quite contrary to those reported in the Antarctic (Kasuya & Ichihara, 1965; Ohsumi et al, 1970). The reversal of the sex ratio of the same species
in varying geographical conditions perhaps suggests the segregation of the sexuallymature whales which may be associated with hormonal state of the individuals.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

36

SINGARAJAH

In respect of the sex ratio, the Brazilian minke whales resemble the population of
the Arctic pattern where Jonsgard (1951) noted that the females numerically dominated the males.
Several lines of evidence indicate that the Brazilian minke whales could be
regarded as spatial and temporal stock in a transient habitat, but their biotic potential or capacity to increase in population will very much depend on the limiting
factors which prevail in their native relatively stable Antarctic habitat.
ACKNOWLEDGEMENTS

The majority of this work was carried out on board the catcher boat Caho Brancoand at Costinha Whale Factory and it is a pleasure to acknowledge the hospitality
and assistance of the Captain, A. Sato, and his crew, and the factory manager, Mr
S. M. Saito.
I also wish to thank Dr G. Rabay of COPESBRA and Mr R. Sampaia of
SUDEPE for their interests; the former supplied me with many original IWC
reports on minke whales.
This work was carried out during the tenure of a Senior Research Fellowshipfrom the National Council for Development of Science and Technology (CNPq),
REFERENCES
BEST, P. B., 1978. External character5 of minke whales landed at Durban. SI, 25 pp., Document submitted to special meeting on southern hemisphere minke whales, IWC. Seattle.
BEsT, P. B., and D.S. Butterworth 1980. Report on the southern hemisphere minke whales assessment
eruise, 1978/1979. Rep. int. Whal. Commn., 30: 257-283.
BUTTERWORTH, D.S. & BEsT, P. B., 1982. Assessment of minke whales stocks in Antarctic Area II. Prog.
Report. MI 24: 1-12.
CHAPMAN, D. G., 1979. Stratified estimate of Area IV series B minke whale population from sightings dataof assessment cruise 1978/1979 and estimate varience. IWC/31/4, Annex G, Appendix I: 13-15.
CHRISTENSEN, I., 1980. Age determination of minke whales Balaenoptera acutorostrata, from laminated structures in the tympanic bullae. Rep. int. Whal. Commn., 31: 245-253.
DA RocHA, J., 1980. Progress report on Brazilian minke whaling. Rep. int. Whal. Commn., 30: 379-384.
DoROSHENKO, N. V., 1975. Body proportions of the minke whales from the Antarctic. In marine mammals. Mater 6, Vses. Soveshch. po izuc. morsh. mlekopitayushchikh. Kiev. Naukova Dumka. I: 108110.
F.A.O., 1981. Review of the state of world fishery resources. COFI/81/INF., 5: 19-21.
HOLT, S., 1980. Southern minke whales, stock assessments, replacement yield and management procedures.
IWC/Sc/32/Mi4 48 pp.
IWC., 1981. Report of the planning meeting for the IWC/IDCR minke whale assessment cruise, 1981/
1982.
IWC., 1982. Cruise report of the 1980/1981 minke whale assessment cruise.
.JoNSGARD, A., 1951. Studies on the little picked minke whale (Balaenoptera acutorostrata Lacepede). Reporton the Norwegian investigations carried out in the years 1943-1950. Norsk Havalfangst-Tid. 40 (3):209-2,'32.
KAsuYA, T. & T. lcHIHARA, 1965. Some informations on minke whales from the Antarctic. Sci. Rep.
Whales Res. Inst., 19: 37-43.
LAws, R. M., 1959. The foetal growth rates of whales with special reference to the fin whale, Balaenoptera
Sci. Rep. Whales Res. Inst.,
No. 35, 198~

BEHAVIOUR OF MINKE WHALES

37

physalus Linn. Discovery Rep., 29: 281-308.
LAws, R. M. & P. E. PuRvEs, 1956. The ear plug of the Mysticeti as an indication of age with special reference to the North Atlantic Fin whale (Balaenoptera physalus Linn.). Norsk. Havaifangst-Tid. 45 (8):413-425.
MASAKI, Y., 1979. Yearly change of biological parameters for the Antarctic minke whales. Rep. int. Whal.
Commn., 29: 375-395.
MITCHELL, E., 1978. Minority statement of southern minke stock assessment. Rep. int. Whal. Commn.,
28, 84-85.
0HSUMI, S., Y. Masaki, & A. Kawamura, 1970. Stock of the Antarctic minke whales. Sci. Rep. Whales
Res. Inst., 22: 75-125.
OHsUMI, S., 1979. Feeding habits of the minke whales in Antarctic. Rep. int. Whal. Commn., 29: 473-476.
PAIVA, M. P., 1961. Recursos basicos da pesca maritima no nordeste Brasileiro. Bol. Est. Biol. Mar. Univ.
Ceara, 3: 1-10.
SINGARAJAH, K. V., 1983. Behavioural observations and estimates of relative abundance of minke whales
based at Costinha land station-Brazil. Proceeding Sympos. Marine Mammals. Colombo, Feb. 1983. (inpress).
TAYLOR, R.J.F., 1957. An annual record of three species of whale being restricted to pools in Antarctic
sea-ice. Proc. Z,ool. Soc. Lond., 1929: 325-331.
VAN UTRECHT, W. L. & S. VAN DER sPOEL, 1962. Observations on a minke whale (Mammalia, Cetacea)
from Antarctic. Z,eith.fur Sudnertierk. 27 (4): 217-221.
WATSON, L. & T. RITCHE, 1981. Whales of the world. 302 p. Hutchinson, London.
WILLIAMSON, G. R., 1959. Three unusual rorqual whales from the Antarctic. Proc. Z,ool. Soc. Lond., 133:
135-144.
WILLIAMSON, G. R., 1961. Two kinds of minke whales in the Antarctic. Norsk. Hvalfangst-Tid., 50 (4):133-141.
WILLIAMSON, G. R., 1973. Counting and measuring baleen and ventral grooves of whales. Sci. Rep.
Whales Res. Inst., 25: 279-292.
WILLIAMtoN, G. R., 1975. Minke whales off Brazil. Sci. Rep. Whales. Res. Inst., 27: 37-59.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

38

SINGARAJAH

EXPLANATION OF PLATESPLATE I
Breathing and escape reaction of a female minke whale for harpoon shot. Also, notethe difference of length between the lower and upper jaw and the triangular rostrum
with the strong central ridge.
PLATE II
The ear-plugs which fit snugly upon the conical end of the "glove-finger"; the rightand the left side plugs often vary considerably in size.
PLATF III-A & B
The pair of ear bones or tympanic bullae of the same female whale measuring 9.20 m
body length. Macrophotography; the marker represents 1 cm. The surface viewof the photograph is actually the vertical plane of the tympanic bullae, facing eachother in the natural position, with their membranous "glove finger" pointing posterior and ventrally. A: inner aspect. B: outer aspect.
PLATE IV
A small segment of the baleen series just anterior to mid-region of the jaw. Note thecolour pattern (black/white); the lingual margin of the hypotenuse of the triangularpart of the plate is frayed out into fine flexible filaments. Note also the height ofthe cementation.
PLATE VThe different types of reduced baleen plates. A; anterior rod-like plates ("hairs"),
B ; the transitional rectangular laminae, C ; the posterior reduced rectangularlaminae (see text).
PLATE VI
The flipper, more like a wing and a calyx shaped mark on the dorsal surface next
to the body. Note the distinct absence of stripes or patches on the flipper of theBrazilian minke whales.
PLATE VII
The fluke of a male which is usually narrower than that of the female. The whale
strikes the tailstock in response to harpoon shot and in an atttempt to escape.
PLATE VIII
The dorsal fin; situated more toward the caudal end of the body.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

し予8GT ￡［；＇ON

1
s
1
1
1・
ロH 叫 V
l
/
J
l
t
l・
r
/
3
y PS

(
I
I'
I
d)

"
!c
l)
(
I'
HV f°V"~VONIS

I
T'
I'
.
I
二
LV'ld

3
1‑A & 1
1
PLATE 1NGARAJAH
SI

3
・
t
s
1
i
s.I
sRe
e
川/
／
ノ
l
.I
1
/
e
.R
i
Sc

J
.
8
9
,1
5
No.3

V1d
LL
八＇. ＼I:

句V
C・
I
!
6l'
8
r
f
S
＂
.
・

H
a
f
<
1・
.1
f
t
V
}
J
HS
a
s
j・
l
t
s
ε1
・

1)
c
1
.＼［ ・
（
S
VUVDNI
'
lf
1¥
1

I
I
'
.¥
l
.ATE ¥'lP

i'¥GARAJAII
Sl

. Yl)
L
P
(

1)
Pし ＼ .1
(

,
.
l
f
.
1
1
.1
s
e
sR
e
l
a
h
'
l
.J
J
/
.Re
i
c
S

.35,1984
o
λr

wh ．
♂ 1
︑ −
也
可
ミ
n
・弘︑
旬 ︑u句
＝q・E Nh h
﹃
・
と三Fニ

oz

︿ HH
．
︿
ヱ︿ ︷

−凶

OBSERVATION OF TOOTH SCARS ON THE HEAD OF
MALE SPERM WHALE, AS AN INDICATION OF
INTRA-SEXUAL FIGHTINGSHIDEHIRO KATO
Whales Research Institute, Tokyo

ABSTRACT

In order to examine the relation between intra-sexual fightings and sexual
maturity, observations of tooth scars on the head of sperm whales (Physetercatodon) were made collected in South Pacific Oceans during 10 to 18
March 1979 on the Nisshin maru No. 3. Tooth scars on the head were observed on 48 males based on the following four relative stages; none, indistinct, distinct and heavy. Distinct tooth scars including "pallarel scar"
which suggest intra-sexual fightings occurred among whales over 43 ft, andscars of most heavey stage were observed among whales over 46 ft in bodylength. Whales having relatively heavier scars were taken in solitary or a pairin either high latitudes (>40°S) or northern parts of females's range. Although no whales was directly taken from mixed school, three solitary large
males taken around the mixed school had scars of most heavy stage. From theinformations of body length, school size and catch position, most of thesewhales having relatively heavy scars were classified to large bachelor, thesesuggest intra-sexual fightings took place among large bachelors.
The relation between tooth scar stage and testes weight were also examined. Mean weights of single testis (heavier) for males were 4.88 kg(combined both sides, 9.26kg) and 2.68kg (4.70kg) at scar stages of heavy
and distinct, respectively. Comparing testis weights among the whales ofsame body length, whales with heavier scar tend to have heavier testis.
In conclusion, it can be said that sexual maturity rate tend to increase
with increasing of body length and with development of scar stages. Thissuggests that tooth scars indicate one of the evidences of sexual maturity.
INTRODUCTION
Polygyny is the most characteristic behaviour among the social structure of sperm
whale, Phvseter catodon. Ohsumi (1971) estimated that a school master may serve
up to 14 mature females in a breeding season, and Best (1970) gave an estimation of
10-20 females.
Although there is sexual unbalance in the adult population of the sperm whale
due to the male's slower attainment of sexual maturity, it is only such a low magnitude as 2.6: 1 (Best, 1979). However, as suggested by Ohsumi (1966) and Best
(1979) only 10-25% of mature males can become school master and join breeding
school in a year. There has to be expected large surplus males and serious intraSci. Rep. Whales Res. Inst ...
No. 35, 1984, 39-46

40

K八TO

s
e
xua
lcompe
t
i
ti
oni
nt
h
emalepopul
a
t
i
o
n.
Although 1
10 d
i
r
e
c
to
b
s
er
vat
ion on t
hei
n
t
r
a
‑
s
e
x
u
a
lcomp
e
t
it
i
o
n was ma
d
e
,
J971
)
,Be
s
t(
1
979)an
dGa
sk
i
n(
1
9
8
2)s
ug
g
e
st
e
dt
hepr
e
s
enc
eoft
o
ot
hs
c
ar
s
Ohs
umi(
ont
h
ehe
adand/
orthebodymightbeoneoft
hee
v
i
denc
e
soft
h
ef
i
g
h
t
i時 among
ooths
car
shavenotbeendonepre
v
i
ous
l
y
.
ma
t
ur
emal
e
s. Noanal
y
si
son t
hぞ t
Ihadanoppor
t
u
n
i
t
yt
oobs
er
vet
o
o
t
hs
c
ar
sonca
r
c
a
s
e
so
fs
p
ermwhaleon
boar
dofawhal
i
ngf
a
ct
o
rys
h
i
pi
nt
he1978/
79A
n
t
a
r
c
t
i
cwhal
i
ngs
e
a
s
on,and t
o
anal
y
z
ei
nr
e
l
a
ti
ont
ot
hegr
owths
t
a
g
e.
MATERIALSAND MET
HOD
I
nt
he1
978/
7
9A
n
t
a
r
c
t
i
cwhal
i
ngs
e
as
on,N
i
s
s
h
i
nmaruNo.3f
l
ee
t
,onwh
ichIwasonboard,mainlycaughts
permwhalesi
npre(
2
5Nov.
‑3Dec.1
978,southernareas
ofIndianOcean)andpostminkewhal
i
ngs
e
a
s
on(1
0‑1
8March1979,SouthPa
ci
f
ic

F
i
g
.I
. Ty
p
i
c
a
lapp
ear
a
n
c
e
soft
o
o
t
hs
c
a
r
sont
h
eheadofspermwhalei
neachs
c
a
1
・
s
r
alels
c
ar＼
s
t
a
g
e
,ar
rowsshowexample
sof paI: Stage0,photographfromNorthPac
i
日c
. (
i
nt
h
e po
s
s
e
s
s
i
on o
fWRI)
、
r
om A
n
t
a
r
c
t
ic. (
WR!)
2
: StageI,I
WRI)
3: StagelI,fromNorthPaci日c. (
4: SlagcI
lI
,f
1
om 1
hcAntar
c
ti
c. (
W RT)
sRe
s.I
n
s
/
.
,
S
c
i
.Re
/
J.W，／悶 ／e
λ匂 35
,1
98
.
/

SPERM WHALE TOOTH SCARSTABLE I.

CRITERIA OF TOOTH SCAR ST AGES ON THE HEAD OF SPERM WHALES

Tooth scar stage

0
II

III

41

None
Indistinct
Distinct
Heavy

Criterion
No tooth scar present on the head.
Small number of indistinct and sparse scars present.
Scars distinct, at least a pair of "parallel scars" present.
Tooth scars including "parallel scar" are more frequent thanprevious stages.

Ocean). The catches were 43 (all males) and 157 whales (70 males and 89 females), respectively.
I observed tooth scars on 48 males out of 70 males caught in the latter periods,
the approximate position of catch of those samples were on a line connecting two
points; 41°S, 154°E and 26°S, 173°E. Tooth scars on the head region were observed on the flensing deck. Scars presumably caused by sucker and hooks on
cephalopod tentacles or by some other accidental scratchers were excluded. The
density of tooth scars was classified into following four relative categories; none
" 0 ", indistinct " I ", distinct " II " and heavy " III " (Fig. 1 and Table 1).
Both testes were weighed to nearest 50 g on the deck, school size and position
caught for each whale were taken from the operation report of respective catcher
boats.
RESULTS AND DISCUSSION

Gaskin (1970) and Ohsumi (1971) recognized six types of school as the principallysocial units of sperm whale school; nursely school, harem school, juvenile school,
bachelor school, bulls school and lone bull. While Best ( 1979) proposed somewhat different interpretation of the social structure. He considered the mixed
school, which was composed of adult females, their calves and juveniles of both sex
as a basic social unit. This school changes into breeding school in breeding season.
Furthermore, he classified mature males into three developmental stages; small
bachelor (31-39 ft in body length), medium-sized bachelor (40-45 ft) and large bachelor(over 46ft). Best (1979) considered that, in a breeding season large bachelors will
join mixed school to serve as a school master only for short periods. For the convenience of the analyses, above three male body length criteria were adopted below
without further consideration. Furthermore, although the term of" social maturity " has recently been used for male's sexual maturity mainly by International
Whaling Commission (1979) due to unique social breeding behaviour of this species,
the term of" sexual maturity" was adopted in the present study.
Tooth scars were abundant on the side and front portions of the head, butsometimes few were seen even on the back of body. None of them were new.
This suggests that the intra-sexual fighting did not take place considerably before
the season of the present observation (March).

Body length
Table 2 shows relationship between body length and tooth scar stage in 48 male
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

42

KATO
TABLE 2.

Length
(ft)
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Total
Mean length (ft)

LENGTH DISTRIBUTIONS OF OBSERVED WHALESBY EACH STAGE OF TOOTH SCAR
Stage of tooth scar
Total
0

II

III

2
2
2

2
2
4
4
9
6
3

2
3
8
6
3
3
2

2

2

2
2

8
33.71

28
36.72

6
45.67

6
47.83

3
3
2
1
48

sperm whales. Mean body lengths for scar stages " 0 ", " I ", " II " and " III "were 33.71, 36.72, 45.67 and 47.83 ft, respectively. The difference between stagesof" I" and" II" was significant (t-test, 0.005<P<O.Ol). Itis clear that magnitude of scars on the head increase with increasing body length.
Best (1979) reported that the presence of" parallel scar" (Fig. I), which heconsidered as attributable to attack of another sperm whale, is one of the evidence
of intra-sexual fightings. This type of scars were peculiar to whales classified tothe scar density stages of " II " and " III " (Fig. I), and observed among whales
at 43 ft in body length or more (Table 2). This result coincides with the result
obtained off the west coast of South Africa (Best, 1979). The heaviest scars(" III ") were observed only whales over 46 ft in body length.

School size and position of catch
Best (1979) and Gaskin (1982) showed that males segregate latitudinally by
growth stages (or by groups mentioned above) in Southern Hemisphere, the southern limits of migration for small and medium-sized bachelors are about 35 °S and 45 °S,
respectively, and large bachelors migrate to the Antarctic region.
The mean size of bachelor schools relates to the above mentioned growthstage, i.e. 15 whales, 4-6 whales and solitary (or sometimes a pair) for small, mediumsized and large bachelor, respectively (Best, 1979). Table 3 shows the relationshipSci. Rep. Whales Res. Inst.,
No. 35, 1984

SPERM WHALE TOOTH SCARSTABLE 3.

43

SCHOOL SIZES OF OBSERVED WHALES RECORED BY RESPECTIVE
CATCHER BOATS IN EACH TOOTH SCARS STAGES
Tooth scars stage

School size0
1.0
1.1-1.5
1.6-2.0
2.1-2.5
2.6-3.0
3.1-3.5
3.6-4.0;;::4.1
Unknown
Total

I

II

III

7
6
5

1
4

4
2

6

6

3

3

2

1
6

8

28

between tooth scar stage of whales and school size of those whales. Mean school
sizes decreased with increasing scar stage, 3.27 (stage "0 "), 2.58 ("I "), 1.30("II ") and 1.13 ("III "). However, since the school size tended to be recorded
after disruption of the original school by chasing, these school sizes might be underestimated, and the actual value of group size would be less important rather than
the trend. It is notable that whales having the relatively heavier scars ("II" and" III ") were mainly taken from solitary whales or those in a pair.
Fig. 2 shows the latitude of catch positions of present materials (males) together those of females which were not analysed in the present study. Whales
having relatively heavier scars (" II " and " III ") were mainly caught either inhigher latitudes ( >40°S) outside of females range or in northern parts of the range
20°S,,. ...

.'

30°S

''

~

''
'•

0

~~ \'

0

'

0

'

f
''
'

.

'
'

~

'

00

,'

,'

Ill

ffi

40°S

..

.. ..
.......

'
•

~@

@@

@

50°8---------------

Fig. 2. Latitudinal catch positions of male sperm whales in each tooth scar stage
and females (unobserved).
O: Stage 0
Stage I
Stage II(!): Stage III

e:Sci. Rep. Whales Res. Inst.,
No. 35, 1984

e:

44

KATO
TABLE 4. NUMBER OF MALES IN THE PRESENT MATERIALS CLASSIFIED BY TYPE
OF GROUP, SCARS STAGE AND KINDS OF SCHOOLS TAKEN FROM

Scars stage

Type of group0

Small bachelor{Small bachelor
Medium-size bachelor{Medium-size bachelor
Large bachelor
Large bachelor

II
III

From bachelor school

From mixed school

n (%)

5
23
3
5
6

( o2.5)( 78.5)( 10. 7)
( 16. 7)
( 83.3)(100. 0)n (%)

3(37 .5)( 7. 2)( 3.6)(Fig. 3). Although three solitary males having scars of stage "III" were notcaught from the mixed school, they were found relatively near a mixed school(26°44'S, 165°04'E) from which five resting females and one pregnant female
were taken. Their positions were 27°2l'S, 163°57'E; 27°14'S, 164°27'E; 27°13'S,164°24'E. Distances from the mixed schools ranged from 44.7 to 70.5 nautical
miles. There is no observation on the social relationship between these males andthe mixed school above.

Male group type
Table 4 was constructed using male growth stage criteria mentioned above (Best,1979) and information of schools recorded by the catcher boats. All the six whalesat scar stage " III " and five of six whales at scar stage " II " belonged to bodylength stage of large bachelor. Although the presence of " parallel scars " are notrecorded for all individuals, as mentioned previously, only stages of " II " and" III " had "parallel scars " which indicate possible intrasexual fighting (Best,1979), therefore, it can be said that most of intrasexual fightings take place between large bachelor whales.
Testes weight
Best (1969) reported that rapid increase of testes weight relative to body length
start at around 43-46 ft, which almost coincides with the length where 50% of individuals are sexual mature by his histological criteria. Furthermore, Gambell(1972) found on sperm whales off Durban that the increase in growth rate of testes
weight start at a body length of 45.4 ft or at a combined weight of both testes of
4.85 kg. They concluded that mean body length at sexual maturity is about 4545 ft, and Gambell (1972) suggested whales having combined weight of testes of
4.85 kg are sexual mature.
Fig. 3 shows the relation between weight of testis, body length and tooth scarstages. It is apparent that testis weight increases with increasing body length. And
if compared among the whales of same body length, the whales having heavier
testes tend to have heavier scars on the head. This trend is more evident among
the whales over 43 ft in body length. Mean weight of single testis (heavier in bothside) for males at scar stage" III" were 4.88 kg (range, 2.75-7.50 kg), which wasmuch larger than 2.68 kg (range, 1.45-3.80 kg) for males at the stage " II ". The
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SPERM WHALE TOOTH SCARS
8.0

15.0

@

o, Stage 0• , Stage I..,..., Stage I I@, Stage Ill

6.0

@

@

..."'
..."'
~

2.0

• •

Q)

·:;

"'
Q)

•• •

• •
• 0
.t.

~

.!:

0 1.0

...

0

Ol
Q)

•

...

_._

0

@
@...._......

Q)

.!:

@

@

~ 5.0

.c

,._

...

.!:
Ol

::

"O

0 •

Q)

c

Ol

Ci

.::' 0.5

0

_J

35
(Log)

~

0

u

0

30

0

E

0

Body

40
length

45
in

50

...

.•

~

Q)

ii
0

•

•• •

...

0

::

@

Q)

0

••

@

@, Stage III

..."'
..."'

@

+

Q)

•, Stage I+, Stage I I.::10.0Ol-"' 4.0c@o, Stage 0

Ol

-"'
@

45

0

0

1.0
30

feet

40

35
(Log I Body

length

45
in

50

feet

Fig. 3. Relationship between body length (in logalithmic scale), tooth scar stage
and weight (in logalithmic scale) of heavier testis (left) or combined weight of bothtestes (right).

difference of above two weights was statistically significant (t-test, 0.01 <P<0.05).
The combined weights of testes for whales ranged 5.30-14.80 kg (x=9.26 kg) for
scar stage" III" and 2.85-6.60 kg (x=4.70 kg) for stage "II". The differenceof two mean values was also statistically significant (t-test, 0.01 <P<0.05).
Adopting the criterion of sexual maturity of the combined testes weight of 4.85
kg (Gambell, 1972), all males at stage "III", three of six males at stage "II" andone of27 males at stage" I" can be sexually mature (Table 5). On the other hand,comparing with body length criteria of male's group type and adopting the above
mentioned criterion of testes weight as sexual maturity, eight of 12 males in large
bachelor, two of four males in medium size bachelor can be sexually mature (Table 5 ).
TABLE 5.

RELATIONSHIP BETWEEN BODY LENGTH (FT), TOOTH SCAR STAGESAND SEXUAL STATUS OF SPERM WHALES
Tooth scar stage

Type of group(length)Sexual status

Small bachelor(31-39 ft)
Medium-size bachelor(40-45 ft)
Large bachelor(46 ft){Immature
MatureTotal{1mmature
MatureSci. Rep. Whales Res. Inst.,
No. 35, 1984

Total

0
8

II

III

25
2

{Immature
Mature{1mmature
Mature

8
0

27

1
3
2
3
3

6
0
6

33
0
2
2
3
8
38
10

46

KATO

Judging from testes weight, among the large bachelors all males having scars of stage
III are sexually mature, while three of five males of stage " II " are sexually immature (Table 5 ). Among four medium-size bachelors two sexually matured males
also exist; one from tooth scar stage "I" and the other from stage "II" (Table
5). But it's doubtful whether males having scar of stage "I" actually contributeto reproduction of this species or not.
Summarizing the above, judging from testes weight of the present materials,
it can be said that sexual maturity rate tends to increase with increasing of bodylength and with development of scar stages. Moreover, even in males of the large
bachelors, although all males attained sexual maturity in the tooth scar stage" III",
both of sexually matured and immature males coexist in stage " II ". These suggest that magnitude of tooth scar closely relate to sexual maturity.
In conclusion, tooth scars on the head of sperm whales seem to increase
with growth and presumably indicate the experience of intra-sexual fighting. For
the further examination of this point, individual age information should be takenin account. It will be examined in future study.
ACKNOWLEDGMENTMy sincere thanks are due to Dr T. Kasuya, Far Seas Fisheries Research Laboratory, who kindly reviewed the draft manuscript and made valuable suggestions to
the present paper. I would also like to express my thanks to Dr S. Ohsumi, Far
Seas Fisheries Research Laboratory, who gave valuable suggestions in earlier stageof the present work, and to Dr H. Omura, director of my institute who allowed
me to use the facilities during the course of the present work. Finally I was notable to carry out field observation without the co-operation of staffs and crew ofNisshin maru No. 3, especially Mr K. Yamaguchi (chief staff of £lensing and meatproduction), Nippon Kyodo Hogei Co. Ltd. Ms T. Shirai assisted in typing anddrawing of the manuscript.
REFERENCES
BEsT, P. B., 1969. The sperm whale (Physeter catodon) off the west coast of South Africa 3. Reproductionin the male. S. Afr. Div. Sea. Fish. Invest. Rep. 72: 1-20.
BEST, P. B., 1970. The sperm whale (Physeter catodon) off the west coast of South Africa 5. Age, growth andmortality. S. 4fr. Div. Sea. Fish. Invest. Rep. 79: 1-12.
BEST, P. B., 1979. Social organization in sperm whales, Physeter macrocephalus. pp. 227-89. In H. E.
Winn and B. L. Olla (eds.), Behavior of Marine Animals-current prespective in research. Vol. 3: Cetacean.,
Plenum Press, Newyork, 438 pp.
GAMBELL, R., 1972. Sperm whales off Durban. Discovery Rep., 35: 199-358.
GASKIN, D. E., 1970. Composition of schools of sperm whales Physeter catodon Linn, east of New Zealand,
N . ..(:'.].Mar. Freshwater Res. 4: 456-471.
GASKIN, D. E., 1982. The ecology qfwhales and dolphins. Heinemann, London, 459 pp.
0HSUMI, S., 1966. Sexual segregation of the sperm whales in the North Pacific. Sci. Rep. Whales Res. Inst.
20: 1-16.
0HsUMI, S., 1971. Some investigations on the school structure of sperm whale. Sci. Rep, Whales Res. Inst.
23: 1-25.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

ANATOMICAL STUDIES ON THE CELL COLUMNLOCATED CLOSELY MEDIAL TO THE NUCLEUS OF
THE SPINAL ROOT OF THE TRIGEMINAL NERVE
IN THE SPERM AND THE PYGMY SPERM WHALESYASUSHI SEKI
Department qf Anatonry, Kanazawa Medical University, Ishikawa

ABSTRACTA specific cell column was examined anatomically, which was locatedclosely medial to the nucleus of the spinal root of the trigeminal nerve of the
medulla oblongata in two sperm whales and a pygmy sperm whale.
This cell column was observed extending at the level from the obex tothe uppermost medulla in the sperm whale and at the level of the middle one
third of the medulla oblongata in the pygmy sperm whale.
After the precise comparative anatomical and histological investigations,the author has come to the conclusion that the cell column is thought to be
the structure corresponding to the lateral cervical nucleus which has highly
developed in the level of the medulla oblongata.
INTRODUCTION

In the previous report (1977) of a noteworthy cell group located closely medial to
the nucleus of the spinal root of the trigeminal nerve in the sperm whale, the author
pointed out the high possibility that the cell group might belong to the spino-bulbothalamic relay system because of the striking similarity between the characteristicsof the cell group and those of the lateral cervical nucleus.
While Matsumoto (1953) described a specific cell group situated closely medial to the nucleus of the spinal root of the trigeminal nerve in the pygmy sperm
whale. He thought the cell group might belong to the sensory trigeminal nucleus
because of the partial continuance of the gray substance at the oral level of thecell group to that of the spinal trigeminal nucleus.
In this research, the author investigated comparative anatomically and histologically the specimens of two sperm whales and a pygmy sperm whale, andfound out that the cell group Matsumoto described in the pygmy sperm whale
showed just the same characteristics as those of the cell group reported by theauthor in the sperm whales.
MATERIALS AND METHODS

Two adult sperm whales (Physeter catodon Linnaeus) were parts of those which
had been collected by Dr T. Kojima when he was on a whaling expedition in theSci. Rep. Whales Res. Inst.,

No. 35, 1984, 47-56

SEKI

48

Antarctic Ocean in 1949-50. The first sperm specimen was the portion covering
almost full length of the medulla oblongata and the first cervical cord, and thesecond sperm was the part, extending from the level 10 mm above the obex to thatpart which included the first cervical cord. Both materials, after having been preserved in formalin, cut off to meet the purpose, and refixed in Muller's solution in
37°0 for 2 to 3 weeks and mounted in celloidin through the usual manner. Serial
sections of 30 to 45 µm in thickness, along the transverse plane for the first sperm,
and the horizontal plane for the second sperm, were made. Each 5th sections(the first and sixth and so forth with the last order of each figure being 1 and 6)ML3.,.....-

4
~

*

.·
ML
Fig. 1. Approximate location and size of the cell column in question projectedfrom transverse sections on the horizontal plane (dorsal view) in the lst sperm
whale, Kliiver-Barrera, X 3, Arrows show levels: 1 =Plate 1, Fig. 1, 2 =Plate 1,
Fig. 2, 3=Plate 2, Fig. 3, 4=Plate 2, Fig. 4, 5=cranial end of the nucleus of theposterior funiculi, 6=caudal end of the inferior olive, 7=level of the obex, 8=
cranial limit of the dorsal roots. *: Cranial extension of the lateral cervicalnucleus. ML: Midline, FRh: Fossa rhomboidea.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

49

SPECIFIC CELL COLUMN IN PHYSETERIDAE

were stained by the Kltiver-Barrera's method and each 10 sections (lOth, 20th,
30th-etc.) were treated by the Weigert-Pal's or Kultschitzky's method for myelin staining. Silver impregnation method was also applied sporadically on some
sections according to needs.
The pygmy sperm (Kogia breviceps Blainville) whale specimen was a casewhich had been collected by Dr T. Ogawa in 1937 at Shiogama, and the wholebrain stem was treated into the serial section preparates stained by the Pal carmin
method at the Brain Research Institute of the University of Tokyo.

ML

---1

**

..
..

·! •

..

-~:

-

2

ML
Fig. 2. Approximate location and size of the cell column in question superimposedfrom horizontal sections on the horizontal plane (dorsal view) in the 2nd sperm
whale, Kluver-Barrera, X 4, Arrows show levels: 1=level of the obex, 2=cranial
limit of the dorsal roots. *: Artificial cleft, **: Cranial extension of the lateralcervical nucleus, ML: Midline, FRh: Fossa rhomboidea.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

50

SEKI

RESULTSIn the sperm whales, the cell group in question was found as an evident cell column
extending longitudinally from the level of the obex to the uppermost medulla andlocated closely medial to the nucleus of the spinal root of the trigeminal nerve(Plate 1 and 2).
This cell column was surrounded by the coarse myelinated fibers of the lateralfuniculus and seemed oval, fusiform or club shape in appearance at the transverse
sections, and measured 4.0-3.2 mm in dorso-ventral direction, 1.5-1.2 mm in width
at the midmost level of the column, and extended 21 mm on the left side and23 mm on the right side in rostrocaudal direction (Figs 1 and 2).
Inside the cell column, it was filled by rather dense net of fine myelinatedfibers, and some of small bundles of coarse fibers were seen penetrating longitudinally through the gray substance of the column. Such penetrating fiber bundles
were observed numerous in the caudal levels and decreased in number graduallyin the higher levels of the column (Plates 1, 2 and 5, Fig. 9).
Nerve cells contained in the column were thought to be classified in two
types; one was quite numerous and middle sized, somewhat rounded polygonal orsometimes spindle shaped, measured 60-40 µm in long diameter and 40-20 µm in
short one, enclosed fine Nissl granules and stained in light colour, the other one wasless in number and a little smaller in size, measured 50-30 µm in long diameterand 25-18 µm in short one, triangle or multipolar in shape, usually stained darkly.
These cells were disseminated almost evenly in the cell column and they scarcely
made crusters or groups of cells inside the gray substance of the column (Plate 6,
Fig. 11).
These structures noted above were quite characteristic to the cell column inquestion, and made it easy to discriminate from certain other structures in theneighbourhood, i.e. nucleus of the spinal root of the trigeminal nerve, nucleus
ambiguus, nucleus reticularis lateralis etc. (Plates 1, 2, 5 and 6, Figs 11-14).
At the level near the rostral end of the column, although the gray substanceof the column was observed contacting partly with that of the nucleus of the spinal
root of the trigeminal nerve (Plate 1, Fig. 1), identification of both structures was
easily recognized as the characteristics of the nerve cells were different from eachother (Plate 6, Figs 11 and 12).
In the sperm whales, a small lateral cervical nucleus was able to recognize at
the uppermost cervical segment, though less distinct. This nucleus, slender andreticular in appearance, was observed continuous farther cranialwards to the medulla oblongata and finally reaching and fused with the cell column in question at
the level of the obex (Figs I and 2).
In the pygmy sperm whale, the cell group Matsumoto described was observed
as a conspicuous cell column extending longitudinally at the level of the middle
one third of the medulla oblongata and located closely medial to the nucleus of the
spinal root of the trigeminal nerve (Plates 3 and 4 ).
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SPECIFIC CELL COLUMN IN PHYSETERIDAE

51

ML

--

-

1

2
3

--4

-

5

6

7

8

ML
Fig. 3. Approximate location and size of the cell column in question projectedfrom tranverse sections on the horizontal plane (dorsal view) in the pygmy sperm
whale, Pal carmin, X 4, Arrows show levels: l =Plate 3, Fig. 5, 2 =Plate 3, Fig. 6,
3=Plate 4, Fig. 7, 4=Plate 4, Fig. 8, 5=caudal end of the lateral recessus, 6=level of the obex, 7=caudal end of the inferior olive B=rostral limit of the dorsal
roots. ML: Midline, FRh: Fossa rhomboidea.

This cell column was surrounded by the coarse myelinated fibers of the lateralfuniculus and seemed oval, fusiform or club shape in appearance at the transverse
sections, and measured 4.2-3.8 mm in dorso-ventral direction, 1.3-1.0 mm inwidth at the level of the obex, and extended 8.8 mm on the left side and 7.3 mm
on the right side in rostro-caudal direction (Fig. 3).
Inside the cell column, it was filled by rather dense net of fine myelinatedfibers, and some of small bundles of coarse fibers were seen penetrating longitudinally through the gray substance of the column. Such penetrating fiber bundles
were observed numerous in the caudal levels and decreased in number graduallyin the higher levels of the column (Plates 3 and 4 ).
Two types of nerve cells were investigated in the column; one was numerous
and middle sized, somewhat rounded polygonal or sometimes spindle shaped,
measured 40-30 µm in long diameter and 30-20 µm in short one, stained in lightcolour, the other one was less in number and a little smaller in size, measured 3020 µm in long diameter and 25-15 µm in short one, triangle or multipolar in shape,
usually stained darkly by the carmin. These cells were disseminated almost evenly
in the cell column and they scarcely made crusters or groups of cells inside theSci. Rep. Whales Res. Inst.,
No. 35, 1984

52

SEKI

gray substance of the column.
These structures noted above were quite characteristic to the cell column inquestion in the pygmy sperm whale, and made it easy to discriminate from certain
other structures in the neighbourhood, i.e. nucleus of the spinal root of the trigeminal nerve, nucleus ambiguus, nucleus reticularis lateralis etc. (Plates 3 and 4).
At the level near the rostral end of the column, although the gray substance ofthe column was observed contacting partly with that of the nucleus of the spinal
root of the trigeminal nerve, identification of both structures was easily recognized
as the characteristics of the nerve cells were different from each other.
In the pygmy sperm whale, the lateral cervical nucleus was hardly recognizedat the uppermost cervical segment or the lower medulla in the Pal carmin stained
sections.
DISCUSSION

Dr Matsumoto was the earliest researcher who described the cell column in question. In his anatomical studies on the brain stem of the pygmy sperm whale(1953), he made precise and accurate descriptions on the cell column. Although
he paid attention to the fact that the cells were observed disseminating in the cellcolumn, he thought this column might belong to the sensory trigeminal nucleus
because of the partial continuance of the gray substance at the oral level of thecell column to that of the nucleus of the spinal root of the trigeminal nerve. He
also emphasized that the cell column is a quite exceptional structure to thepygmy sperm whale, and denied such a structure in the dolphin, Sei and Beaked
whales.
In the previous report (1977), present author described a noteworthy cellgroup observed at the level from the obex to the uppermost medulla and locatedclosely medial to the nucleus of the spinal root of the trigeminal nerve, and pointed
out the high possibility that the cell group might belong to the spino-bulbo-thalamic relay system because of the striking similarity between the characteristics ofthe cell group and those of the lateral cervical nucleus.
In this research, specimens of the sperm whales were examined carefully, andfurther, with the permission of the Institute of the Brain Research, University ofTokyo, the serial section preparate of the specimen of the pygmy sperm whale wasinvestigated, which was the case Dr Matsumoto examined before. After the precise comparative anatomical and histological investigations, the author found outthat the noteworthy cell group in question in the sperm whales showed quite thesame characteristics as those of the specific cell group in the pygmy sperm whale
described by Dr Matsumoto, with the exception of the levels of location of thesecell groups; the former was higher in the medulla and the latter was lower and at
the level almost middle one third of the medulla oblongata.
In the previous study on the comparative anatomy of the lateral cervicalnucleus (1965), present author reported that the nucleus was observed at the uppermost cervical segment in the common dolphin (Delphinus delphis Linnaeus), andSci. Rep. Whales Res. Inst.,
No. 35, 1984

SPECIFIC CELL COLUMN IN PHYSETERIDAE

53

pointed out an interesting fact that the nucleus was extended farther cranialwards
to the lower medulla up to the level of the obex as the gray substances arranged
longitudinally in stepping stone pattern. From the findings of the present investigation, the cell column in question was thought to be locating on the upwards
elongated line of the lateral cervical nucleus, and moreover, in the sperm whales,
the lateral cervical nucleus was found also in the uppermost cervical segment,
though less distinct, and the nucleus was observed continuous farther cranialwards
to the medulla oblongata, as islands-like cell collections in appearance, and finallyreaching and fused with the cell column in question at the level of the obex.
According to these findings noted above, the cell column in question, foundin the sperm whales and a pygmy sperm whale, was considered to be the structure
corresponding to the cell group highly developed in the level of the medulla oblongata showing just the same characteristics as those of the lateral cervical nucleus.
Matsumoto (1953) noted certain degree of asymmetrical development of thecell column in question; the left side column being larger than the right side one,and he thought it might be some relation with the asymmetrical structure of thenasal meatus in the pygmy sperm whale, without an explanation of the reason on
this fact. From the present examination, Matsumoto's finding about the asymmetrical development of the column was reconfirmed distinctly. Ogawa (1949, aand b ), in the pygmy sperm whale, described the striking development of the facial
nucleus of the right side than that of the left side, and suggested that there shouldbe certain relation with the asymmetrical structure of the nasal meatus in thiswhale. Hosokawa (1950) reported some asymmetrical structure of the larynx inthe sperm whale. In spite of the extraordinarily asymmetrical nasal passage, after
the present examination, as far as the extent of the gray substance is concerned,
the cell column in question in the sperm whale was hardly recognized the significant asymmetry. At the present stage of the research, it is thought to be difficult
to say something on the relation between the difference of the largeness of the cellcolumn in each side and the asymmetrical structures of the nasal meatus or thelarynx in these whales.
Matsumoto (1953) stated that the partial continuance of the gray substanceat the oral level of the cell column in question with that of the nucleus of the spinal
root of the trigeminal nerve, and accordingly he thought that the cell column
might belong to the sensory trigeminal nucleus. In the present examination of thespecimen of the pygmy sperm whale, the characteristics of the cell column in question was observed different from those of the nucleus of the spinal root of the trigeminal nerve, and the situation was interpreted as the gray substance of the cellcolumn being in contact with that of the trigeminal nucleus. Concerning this matter, in this research, the structural difference of both gray substances was reconfirmed clearly in the first specimen of the sperm whale, after the examination of
the additional sections treated by the Kluver-Barrera's and silver impregnation
methods.
In the cat or in certain other mammals, it is well known that the lateral cervical nucleus receives afferent fibers originating from the lower levels (Broda! andSci. Rep. Whales Res. Inst.,
No. 35, 1984

54

SEKI

Rexed 1953, Morin 1955, Ha and Liu 1966, Craig 1978, etc.). Craig (1978) reported medullary input of the lateral cervical nucleus originating from the nucleusof the posterior funiculi and the nucleus of the spinal root of the trigeminal nerve.
Similar relationships, referring the findings of the present examination, could besuggested also in the whales, such as the possibility that a certain amount of fibersof the lateral funiculus might terminate in the cell column.
Although holding a different opinion from that of Dr Matsumoto as to themeaning of the cell column in question, the present author should like to make aproposal, in memory of his first description, to name the cell column as " the nucleus of Matsumoto ", at least for some time until it receives an adequate nomenclature in the future.
SUMMARY

A specific cell column was examined anatomically, which was located closely medial to the nucleus of the spinal root of the trigeminal nerve of the medulla oblongata in two adult sperm whales and an adult pygmy sperm whale.
This cell column was observed extending at the level from the obex to theuppermost medulla in the sperm whales and at the level of the middle one third of
the medulla oblongata in the pygmy sperm whale.
The cell column was surrounded by the coarse myelinated fibers of the lateralfuniculus and bordered in an oval, fusiform or club shape in appearance at thetransverse sections and seemed considerably outstanding from the neighbouring
structures.
Inside the cell column, two types of nerve cells were contained; one was middle sized and polygonal, somewhat rounded or spindle shaped, palely stained, andthe other one was a little smaller in size, triangle or multipolar, stained darkly.
The characteristics of these cells contained seemed very similar to those of thelateral cervical nucleus.
This cell column was thought to be located on the upwards elongated line of
the lateral cervical nucleus and moreover, in the sperm whales, the direct continuance was recognized between the lateral cervical nucleus and the cell column
at the level of the obex.
According to these findings noted above, the cell column in question wasconsidered to be the structure corresponding to cell group highly developed in
the level of the medulla oblongata showing just the same characteristics as thoseof the lateral cervical nucleus.
Although none of the definite finding about the fiber connection of the cellcolumn was obtained, at the present stage of research, it seems there is a high possibility that the cell column belongs to the spino-bulbo-thalamic relay system.
ACKNOWLEDGEMENTS

I should like to express my sincere gratitude to Dr T. Kojima, Professor of
Anatomy, Nihon University School of Medicine, for his kind offering to me theSci. Rep. Whales Res. Inst.,
No. 35, 1984

SPECIFIC CELL COLUMN IN PHYSETERIDAE

55

precious materials (Sperm 1 and 2) for this study. Many thanks are due to Dr
T. Ogawa and Dr T. Kusama, formerly directors of the Brain Research Institute,
University of Tokyo, for their kind permission to my investigation of the researchmaterial (Kogia). Throughout my study on the Kogia, good assistance of Dr T.
Kamiya, formerly a staff of the Department of Anatomy, School of Medicine,
University of Tokyo, is also acknowledged.
REFERENCE
BRoDAL, A. and B. REXED, 1953. Spinal afferents to the lateral cervical nucleus. An experimental study.
]. comp. Neural., 98; 179-212.
CRAIG, A. D., 1978. Spinal and medullary input to the lateral cervical nucleus. ]. comp. Neural., 181;729-744.
HA, H. and C. N. Lru, 1966. Organization of spino-cervico-thalamic system. ]. comp. Neural., 128; 445470.
HosoKAWA, H., 1950. On the Cetacean larynx, with special remarks on the laryngeal sack of the Sei whale
and the arytenoepiglottideal tube of the Sperm whale. Sci. Rep. Whales Res. Inst., 3: 23-62.
MATSUMOTO, Y., 1953. Contributions to the study on the internal structure of the Cetacean brainstem.
Acta Anat. Nippon., 28; 167-177 (in Japanese).
MORIN, F., 1955. A new spinal pathway for cutaneous impulses. Amer.]. Physiol., 183; 245-252.
OGAWA, T., 1949a. Results in recent years in the Cetacean anatomy. Sogo lgaku, 6; 6-11 (in Japanese).
OGAWA, T., 1949b. On the Cetacean brain. Brain and Nerve, 3; 159-165 (in Japanese).
SEKI, Y., 1965. Comparative anatomical studies on the lateral cervical nucleus. Acta Anat. Nippon., 40;(5), Suppl., p. 4 (abstract in Japanese).
SEKI, Y., 1977. On a noteworthy cell group situated medial to the nucleus of the spinal root of the trigeminal nerve in the Sperm whale. Acta Anat. Nippon., 52: 70 (abstract in Japanese).

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

56

SEKI

EXPLANATION OF PLATES I-VI
PLATES I AND II
Figs I and 2 and Figs 3 and 4: Transverse sections of the medulla oblongata in the
lst Sperm, arranged from cranial to caudal, Kultschitzky, x 6.
PLATES III AND IV
Figs 5 and 6 and Figs 7 and 8: Transverse sections of the medulla oblongata in the
Pygmy sperm, arranged from cranial to caudal, Pal carmin, X 8.
PLATE V
Fig. 9: The same section as Plate I, Fig. 2, a little enlarged (X 10), left side; note thelocation and shape of the cell column in question and neighbouring structures.
Fig. 10: The section very near to that of Fig. 9, x20, silver impregnation; note thestructural difference of the cell column and the neighbouring nuclei.
PLATE VI
Nerve cells in high magnification ( x 100), Kluver-Barrera.
Fig. I I: The cell column in question.
Fig. 12: Nucleus of the spinal root of the trigeminal nerve.
Fig. 13: Nucleus reticularis lateralis.
Fig. 14: Nucleus ambiguus.

ABBREVIATIONS IN PLATES
FL
FLM
FP
NA
NFP

NQ
NRL
NSV
NXII

OL
RX
RXII

s
TSV

Funiculus lateralis
Fasciculus longitudinalis medialis
Funiculus posterior
Nucleus ambiguus
Nucleus funiculi posterioris
The cell column in question
Nucleus reticularis lateralis
Nucleus tractus spinalis nervi trigemini
Nucleus nervi hypoglossi
Nucleus olivaris inferior
Radix nervi vagi
Radix nervi hypoglossi
Fasciculus solitarius
Tractus spinalis nervi trigemini

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

げ 6f＇~r; '
ON
"JSI
ザ.SJ
U S
l
/
V
l
(
1
1
1・
q
3
y.
f
3
S

・
z・.8!.:f・，..8!.:f

I.
'I
J入l
"
l
d

DE
I
S

くI
SEI

l
八TET
Pし

. 3.
g
Fi

I
;
'
ア
，
・
。
唱
ー
．
．
1

訴
号

e

Fig.4.
,
.
t
s
n
s.I
sRe
e
l
a
h
l
t
p.J
.Re
i
Sc
984
,1
.35
No

r＇~c ・OJ\(
6
u
t
S
'
t
・
ザ.SJU S~／IJl(. 11 ・t/Jy .
./SI.

'f_＇＞~; ·~1丘
(
.

S
I
)E
l

＇ムV1d
.
1］
1
1

PL八TE I
V

SEKI

F
i
g
.7
.

F
i
g
.8
.
Sc
i
.Re
p
.J
l
l
h
a
l
e
sRe
s.J
/
1
s
l
.
,
j＼
＇
匂.3
5
,1
9
8
1
:

f86l §
［
； ＇
ON
'
・
1口ザ.S
J
US
3
/
V
l
f
1
M ・r
f
a
u'!JS

・
01 ・
l
JI
.
'
J
:

・
6・
E
iJ

八百よV
'
l
c
l

DI3"S

SEKL

PしATE Vl

．
ノ

論

.
)

．量

F
ig.1
1
.

F
i
g.1
2
.

Fi
g.1
4
.
S
c
i
.Re
p.J
l
!
h
a
l
e
sRe
s
.I
n
s
t
.
,
No.3
5
,1
9
8
‑
1

AGE DETERMINATION AND GROWTH OF THE SHORTFINNED PILOT WHALE OFF THE PACIFIC
COAST OF JAPANTOSHIO KASUYA *Ocean Research Institute, University of Tokyo, Minamidai, Nakano-ku Tokyo, 164 JapanAND

SUSUMU MATSUI
Taiji Whale Museum, Taiji, Higashimuro-gun, Wakayama-ken, 649-51 Japan

ABSTRACTThis study is based on data and specimens from 373 female and 170 male
Globicephala macrorhynchus collected off the Pacific coast of central Japan andcovering eight months of the year. The deposition rate of dentinal growthlayers was annual, the haematoxylin-stainable layer being formed from May
to October and the unstainable from December to February. The annual
deposition of cementa! layers continued after dentine deposition ceased, thus
enabling the age of old individuals to be determined.
The maximum age
attained by females was 62 years, that of males 45 years. Females almost
ceased growth at sexual maturity (nine years) and reached the asymptotic
length of 364.0 cm at age 22 years. Male growth was similar to that of females until age nine years, when the secondary male growth spurt started.
Males attained an asymptotic length of 473.5 cm at 27 years. Body length
could be converted into age with an accuracy of ±2 years, up to a bodylength of 280 cm (females; equivalent to age 5 years) or 320 cm (males; age
8 years). The relationship between body weight 0/V, kg) and body length(L, cm) of fetal and postnatal individuals of both sexes was described bylog W=2.8873 log L+log (2.377x 10-5).
INTRODUCTION

Sergeant (1959) examined the dentinal growth layers in the tooth of long-finned
pilot whale, Globicephala melaena (Traill, 1809), and suggested that these layers
might be used to estimate absolute age. He used this technique in his analysis of
the life history of G. melaena in Newfoundland waters (Sergeant, 1962). Sergeantalso observed cementa! growth layers in this species and suggested that they might
be used to age animals in which dentine deposition had ceased. However, he did
not use the technique, presumably because of technical difficulties.
Dentinal layer counts have subsequently been used in the study of the life

* Present address:

Far Seas Fisheries Research Laboratory, 5--7-1, Orido, Shimizushi, Shizuokaken, 424

Japan.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 57-91

KASUYA AND MATSUI

58

history of several odontocetes as reviewed by Scheffer and Myrick (1980), despite
the limitations of the technique for determining the age of old individuals. In
recent years, however, the methods of preparing teeth for cementa! and dentinal
layer counts have been greatly improved (Perrin and Myrick, 1980).
The improved age determination techniques have been used to study the life
history of the short-finned pilot whale Globicephala macrorhvnchus Gray, 1846. We
report on age determination and growth in G. macrorhvnchus in this paper. Related
studies on the life history and reproduction of this species (Kasuya and Marsh, inpress) and on fundamental anatomy of the ovaries (Marsh and Kasuya, in press)
will be published elsewhere.
MATERIALS AND METHOD

Data source
Most of the data and specimen materials were collected between 1965 and 1980
inclusive from 24 schools of G. macrorhvnchus (Schools I through 24 in Table 1)caught on the Pacific coast of Japan by the driving fishery at Taiji (33°34'N,
135°54'E), Futo (34°54'N, 139°09'E), or Arari (34°49'N, 138°46'E), and from one
school stranded at Choshi (35°43'N, 140°52'E) in the Chiba prefecture. The
TABLE 1.
School
no.

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

MATERIALS USED IN THIS STUDY
Date ofNo. of individuals

Locality
Arari
Choshi
Arari
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji
Fu to
Futo
Taiji
Fu to
Fu to
Taiji
Taiji
Taiji
Taiji
Taiji
Taiji

catch

data collection

drivenexamined

aged

lost

20 Oct. '65
13 Dec. '66- June '67
22 July '69
27 July '69
24 Feb. '71
17 Jan. '75
21 Jan. '75
24 June '75
22 July '75
13 Jan. '76
4 Feb. '76
7 Oct. '76
20 Dec. '77
24 Dec. '77
20 Feb. '78
4 Dec. '78
13 Dec. '78
6 Jan. '80
17 Jan. '80
2 Feb. '80
20 Feb. '80
21 Feb. '80
30 May '80

21 Cct. '65
15 Dec. '66
27, 28 June '67
July-Aug. '69
July-Aug. '69
24 Feb. '71
18, 19 Jan. '75
21, 22 Jan. '75
25 June-4 Jul.
22-24 July '75
13-17 Jan. '76
5, 6 Feb. '76
8, 9 Oct. '76
21 Dec. '77
25 Dec. '77
20, 21 Feb. '78
5 Dec. '78
13, 14 Dec. '78
6 Jan. '80
17, 18 Jan. '80
2 Feb. '80
23 Feb. '80
24 Feb. '80
31 May-3 June33
ea. 90
>30
31
46
24
28
52
ea. 230
33
28.
20
38
25
48
27
52
28
26
14
19
15
23
38

18
9
14
9
23
12
28
47
173
32
26
20
38
25
48
27
52
28
23
14
17
15
23
38

8
3
4
2
10
0
26
0
125
18
21
18
38
22
45
27
49
28
0
7
0
15
23
38

15
80
16
22
23
12
0
5
57
1
2
0
0
0
0
0
0
0
3
0
2
0
0
0

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

59

linear distance between the southernmost location, Taiji, and the northernmost,
Choshi is about 500 km.
The quality and quantity of data and samples varied between the schools.
In the early period of the study (Schools 1 to 6), effort was directed to the collection of materials for taxonomy, and the data obtained for the present analyses
were limited and biased to adult individuals. Information from four schools(schools 8, 19, 20 and 21) examined by volunteers was usually limited to sex andbody length. The 14 schools (Schools 7, 9 through 18, 22, 23 and 24) caught inthe seven years from 1975 to 1980 and examined by Kasuya constituted the major
source of data used for the study.
Field procedures
The information and samples listed below were collected by Kasuya, volunteers or
both, when the fishermen were flensing. At this stage each pilot whales was assigned a sample number which is a hyphonated combination of the school number
followed by the number of the animal within the school.
1. Sex
2. Bodv length Measured to the nearest 1 cm on a straight line parallel to thelong axis of the body from the anteriormost point to the bottom of the tail fluke
notch. Although the tip of the upper jaw is the anteriormost point of the bodyof juveniles, it lies posterior to the front end of the melon after the whale is about
240 cm long and becomes difficult to distinguish (Yonekura, Matsui, and Kasuya,1980). Thus the measurement of body length is not exactly comparable for adults
and calves less than one year old.
3. Teeth One to three contiguous teeth were collected from the center of thelower tooth row with a hammer and chisel and preserved in 10% buffered formalin.
The largest available teeth were selected.
4. Other specimens Mammary gland, testis, epididymises, ovaries, uteri andstomach contents were collected as detailed in Kasuya and Marsh (in press).
Laboratory procedures
1. Tooth preparation The age determination was done by Kasuya who counted
the annual growth layers in dentine or cementum. (One growth layer is equivalent to an annual Growth Layer Group of Perrin and Myrick (1980)). The bone
and connective tissue surrounding tooth selected were removed with a knife. The
tooth was then cut longitudinally with a low speed diamond saw. The cut surface was then polished with coarse (about 1,200 mesh) and fine (about 3,000 mesh)whetstones to expose the center of the tooth. The polished surface was dried andglued on a clear perspex plate (1 mm thick) with cyanoacrilate monomer. Afterthe glue had hardened, the other side of the tooth was similarly sawed off leaving
a 0.3 to 0.5 mm thick section on the perspex slide. This section was polished withthe whetstones to a thickness of 30 to 40 µm. The polished section was then decalcified in 5% formic acid for about 24 hours at room temperature, rinsed in running water for 5 to 12 hours, stained with Mayer's haematoxylin for 30 minutes,
Sci. Rep. Whales Res. Inst.,.No. 35, 1984

60

KASUYA AND MATSUI

rinsed in running water for several hours and mounted in Canadian balsam. (Acomplete removal of acid by long rinse or ammonia after staining prevent fading.)
2. Reading growth lavers The counting of annual growth layers was done undertransmitted light with a compound microscope (20 to IOOx) using the following
procedure. An ontogenetic series of 20 slides was initially prepared for each sex.
Factors taken into account in the selection of these slides included the quality of
preparation and the relative age suggested by the thickness of dentine and by thesize of the pulp cavity. The dentinal and cemental growth layers in the slide ofthese 40 teeth were counted. In most cases, there was reasonable coincidence between the number of growth layers in both tissues.
However, there were a few cases where the reading did not correspond. These
slides were re-examined for indication that dentine deposition had ceased. All
counts were then plotted against body length and sexual maturity for males andfemales separately. The pattern of increase suggested that the growth layer counts
were a reliable index of absolute age.
The age of the other whales were then determined based on the standard
established above but without reference to biological data. First the cementum
was read three or more times. The medium count was then taken as the true value.
Then the dentinal layers were counted three times without referring to the cementa! counts. The medium value was again used. If the deposition of dentine wasconsidered to have been continuing on at least part of the wall of the pulp cavity,
the dentinal count was used. In a few cases the range of dentinal and cemental
counts differed on a tooth with open pulp cavity. In these cases the growth layers
in both tissues were repeatedly checked until a good agreement was reached between the counts for both tissues. Kasuya used this method to train himself tobe able to make accurate cemental layer counts, enabling him to age whales withclosed pulp cavities, the age of these animals being determined from cemental layercount only.
The age of each individual was principally expressed as the number of growthlayer cycles, which was equivalent to years (see below). The age of individuals
below 10 years was roughly estimated to the nearest 1/4 year by considering the
thickness and nature of the first and last postnatal dentinal layers of incomplete
thickness. For whales over 10 years, the age was grouped into the nearest n+0.5
years (n=integer).
3. Other procedures The method used to determine the reproductive status ofeach whale are detailed in Kasuya and Marsh (in press) and Marsh and Kasuya(in press).
AGE DETERMINATION

Description of dentinal growth layers (Plates I to III)The prenatal dentine is capped by an enamel layer, which dissolves in the
decalcification reagent. In decalcified and haematoxylin stained sections, theprenatal dentine appears as either a moderately or strongly-stained layer in which
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

61

10 to 20 indistinct short cycle layers can be detected with careful study. The
proximal border of the prenatal dentine is lined with a thin unstainable layer inmost postnatal animals. This is the neonatal line (Fig. 2 in Plate I). The thickness of the neonatal line ranges from 16 to 64 µm (X.=38 µm; n=25). The neonatal line could not be distinguished in four newborn individuals ranging from
136 to 142 cm in body length. Two of these whales (males 136 cm and 142 cmlong), had an erect dorsal fin, an indication that birth had occurred not less thanseveral hours before (Kasuya, Miyazaki and Dawbin, 1974). In contrast, theneonatal line was clearly seen in the teeth of five individuals from 154 to 190 cm
in body length and aged between 0.1 to 0.5 year (estimated from body length).
This indicates that the neonatal line in G. macrorhynchus is identifiable only after
the deposition of ordinary more stainable postnatal dentine.
4

7

2

3

4

5

6

7

8

Age in years
Fig. I. Thickness of postnatal dentine of G. macrorhynchus. The ranges, means andsample sizes are indicated. Open circles and dotted line represent females, closed
circles and solid line males.

In decalcified and stained sections, the growth layers in postnatal dentine areseen as layers of alternating stainability. The thickness of the annual growthlayers is about 0.5 to 0.6 mm in both the first and second complete layers (measured
at the level of the base of the prenatal dentine). This thickness decreases to about
0.1 mm at the 30th and subsequent layers (measured at the midlength of the pulp
cavity). No sexual dimorphism was observed in dentine thickness of young whales(Fig. 1). Within one annual growth layer, short cycle layers are usually detectable.
These tend to be conspicuous where the growth layers are wide, i.e. in the dentine
laid down near the tooth apex while the whale is young. Occasionally some ofthese short cycle layers are as prominent as ordinary annual growth layers.
The appearance of dentinal growth layers is variable within a tooth. The
layers deposited in the juvenile stage in the root of the tooth are composed of wide
stainable and narrow unstainable layers (Fig. 4 in Plate I). However if a stainable
layer is traced to the tip of the tooth its outer border gradually looses stainability,
Sci. Rep. Whales Res. Inst.,
N. 35, 1984

62

KASUYA AND MATSUI

while the stainability of its inner border increases. Furthermore, an accessory layer(Hohn, 1980) of strong stainability may appear in the unstainable layer near the tip.
Thus the pattern of stainability of these layers often appears to be reversed with aresultant apparent lag of about half a growth layer cycle between the cusp and theroot portions of the tooth. This feature is usually absent or negligible in subsequent layers. The annual growth layer deposited in the root of the tooth in adultwhales is usually composed of a narrow stainable layer and a wide unstainable
layer (Figs 2 and 3 in Plate II). Although accessory layers are still common mthese layers, they are less conspicuous than in the apex.
100

56

68

J

F

107

29

7

117

33

80

.....

c. 60
([/

u

....
([/

a.. 40
20
0

M

A

M

J

J

A

s

0

N

D

Month
Fig. 2. Seasonal change in the nature of the last incomplete deritinal layer of G.
macrorhynchus. Numerals at. the top indicate sample size. Thin horizontal lines:
wide unstainable layer. Stippling: thin unstainable layer. Black: wide stainable layer. Thick vertical lines: thin stainable layer.

Deposition rate of dentinal growth layers
Seasonality of stainability: Data were obtained from 270 females and 147 males inwhich the deposition of dentine was certainly continuing. The nature of the lastincomplete dentinal layer in the root of the tooth was classified as either a thin ora thick, stainable or unstinable layer. The thickness was judged by eye in comparison with the corresponding tissue in the previous cycle. Fig. 2 shows the seasonality of stainability of the last deposited dentine. In May/June most of the 29
individuals (86.2%) have started depositing stainable dentine. This continues inmost individuals until October. The number of individuals depositing an unstainable layer increases from 12.2% in December to 82.4% in February. Althoughdata are lacking from March to early May, we suspect that deposition of the unstainable layer peaks in February and March, and suggest that the alternations ofdentinal layers from unstainable to stainable and from stainable to unstainable may
occur in April to early May and in November, respectively. Thus each of the two
major components of a dentinal layer seems to represent approximately six months.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE
FemaleMale

Female

63
Male

20
16

~ 12

m

::J
'U 8

>

4

'U

c

0

0 12
I...

8

OJ

..0

E 4
::J

z

0
/

4

0

DecemberJanuary

Fig. 3. Age and sex differences in the season when the stainable and unstainable
layers within a dentinal growth layer alternate in G. macrorhynchus. Thin horizontal lines: wide unstainable layer. Stippling: thin unstainable layer. Black: wide
stainable layer. Thick vertical lines: thin stainable layer.

Approximately 10 to 20% of our sample was not depositing dentine in accordance with this pattern. This may have been due to (1) exceptional individuals(2) errors in layer-identification due to the short cycle layers or (3) sex or age differences in dentine deposition. To test the last possibility the data for each month
were subdivided according to sex arid then into three age groups (1) below 15 years,(2) from 15 to 30 years and (3) over 30 years (Fig. 3). Age/sex differences in
the relative frequency of the four deposition stages was then statistically tested foreach month (Chi-square test). A statistically-significant difference (P<0.05) was
found only for samples obtained in December and January. The only combination where a significant difference was obtained between sexes was in intermediate age class (15-30 years) in January (P<0.01). Although this result indicates that males of intermediate age were more likely to deposit a stainable layer
than females, we consider this is probably an error caused by small sample size
because a similar trend was not observed in December (Fig. 3). A significant difference in the proportion of animals of the same sex laying down a stainble layer
was also found for the following age combinations in December:
Females young: intermediate, P<0.01intermediate: old, 0.02<P<0.05
old: young, P<0.001
Malesyoung: intermediate, P<0.01
Sci. Rep. Whales Res. Inst.,

No. 35, 1984

64

KASUYA AND MATSUI

Thus as the whales get older, proportionately fewer females tend to be accumulating a stainable layer in December. Although not always statistically-significant,the same trend is also observed in the male. The change in the deposition pattern from stainable to unstainable dentine seems to occur slightly later in younger
individuals possibly due to the larger relative width of the stainable dentine inyoung animals (see" Description of dentinal growth layers").

1.4
1.3

I
I
I

1.2

-

-1.1
N

t
I

:

l

I

'9"

:

I

I
I
I

1
I
I

:

:

I

I

1
\

~0.9

t
I
I
I

I
I
I
J

0.8

I

:

I
I

I

I
'

:

0.7
0.60

l!

I
I

:-A<---'"~----:0::"'.........]: .,.. ........ l------t::.?; 1.0
o.

a::

I
I

l'
·5

10

15

20

I
'

:

:

'

I

25

30

35

40

Age in years
Fig. 4. Rate of decrease in the width of dentinal growth layers indicated by the
thickness of the last complete layer (Y) and penultimate layer (Z) in G. macrorhynchus. The ranges and means for males (closed circles and solid line) and females (open circles and dotted line) are indicated.

Seasonal changes in dentine thickness: The thickness of dentinal growth layers wasmeasured with an ocular micrometer. The measurement was taken from thecenter of one stainable layer to the center of the next, except in the case of the lastincomplete set, the width of which was measured from the center of the last complete stainable layer to the predentine-dentine boundary near the edge of thepulp cavity (irrespective of nature of dentine being laid down). This latter measurement was often thicker than that of the penultimate measurement because
each stainable layer was defined only after the next unstainable layer had been
deposited. The uncorrected degree of deposition of the last growth layer (Rn)can be defined as;

Rn=~=where Xn is the thickness of the last (incomplete) growth layer of an n-year old
whale and Yn is the thickness of the (complete) penultimate growth layer of thesame individual. As the thickness of a dentinal growth layer varies with thewhales's age, Rn has to be corrected for this variation. The correction factor Cn
for an n-year old whale can be defined as;Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

Cn =

65

(f Zn+i,j
Yn+i,j) .__!__mi=lwhere m is the number of whales aged (n+ 1)-years and Z is the thickness of thelayer one cycle prior to r. Then the corrected deposition rate for the last incomplete layer of an n-years old individual can be defined as Rn/Cn. This method
is only applicable for whales older than two years.
2.0 ---------------------- ----- ------- -------------------- ----Ul
Ul

~

1.5

~

-~

....

..c

(])"

....c

~ 0.5
0

0

J

F

M

A

M

J

J

A

s

0

N

D

J

Month
Fig. 5. Seasonal change in the relative thickness of the last incomplete dentinal
layer in G. macrorhynchus. The dotted line joins the monthly means (open circles).
Black squares represent individuals depositing a stainable layer; white squares
those depositing an unstainable layer. The shaded areas indicate indiviuals thatare moved back (January) or forward (June/July-December) for one cycle inorder to correct for the individual variation in the seasonality of dentine deposition.

The relationship between age (n) and Yn/Zn is shown in Fig. 4. The meansof the five-year age classes increase until the whales are about 15-years old, andstays almost constant thereafter. The values for males are slightly higher than thecorresponding values for females indicating that the decline of growth layer thickness with age is slower in males. This may relate to the earlier cease of dentine
deposition in males mentioned below (see "Pulp cavity"). Because Yn/Zn showssuch large individual variation, it is not practical to calculate Cn for each age classand sex. Therefore, we have calculated Cn for both sexes and for four age classes
as follows;
2-5 yrs
Cn=0.8045-10 yrs
Cn=0.902
10-15 yrs
Cn=0.963;;::15 yrs
Cn=0.922
The resultant corrected values of the relative thickness of the dentinal layer
being deposited at the time of death in various months are shown in Fig. 5. In
January, about 40% of the individuals are still depositing stainable dentine while
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

KASUYA AND MATSUI

66

Pulp cavity

80
60
40
~· 20
c 0

l!l!l closing, female•

closed , female[J closing, male

1111 closed , mcile

Cellular dentine

>o 80
cu 60

~ 40

O" 20

~

LL' 0
.Secondary
dentine

80
60
40
20
00

10

20

30

40

50

55 58 61

Age ·in years
Fig. 6. Growth of G. macrorhynchus teeth. Top: condition of pulp cavity. Middle: deposition of cellular dentine. The boxes represent four males whose pulp
wall was completely covered by cellular dentine. Bottom: deposition of secondary
dentine. The open circles and dotted line represent females, and closed circles
and solid line males.

the remainder have already started to deposit unstainable dentine. Therefore thevalues of the former individuals need to be moved backward for one cycle. In thesame way, the values for individuals depositing an unstainable layer after Julyneed to be moved forward one cycle. The mean monthly values of the corrected
thickness of the last dentinal layer thus calculated are shown by the open circles
in Fig. 5. The values increase from 0.3 in January to 1.3 in December. The increase is 1.0/year, and indicates that the deposition of the dentinal growth layers
is annual.
Growth of dentine
The postnatal growth of dentine is shown in Fig. 1. The thickness is measured
on the convex ramus of the tooth section from the proximal end of the prenatal
dentine to the pulp wall. Because the apex of the pulp cavity reaches the level ofthe base of the fetal dentine, this measurement is not possible on some males after
8.5 years of age or on some females after 6.5 years. The deposition of dentine is
rapid between 0.25 and 0.5 year of age. This period may correspond with thetime of tooth eruption and more indirectly with the start of taking solid food (seeKasuya and Marsh, in press). After 0.5 year of age the thickness increases at aslightly decreasing rate. The mean annual increment of the dentine in the juvenilestage is calculated from Fig. 1 as about 0.95 mm in the first year, 0.40 mm in thesecond year, 0.33 mm in the 3rd year, and 0.30 mm in the 4th year.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

67

The deposition of secondary dentine starts in some pilot whales of both sexes
at the age of seven years, and in most individuals by 16 years of age (Fig. 6). Although secondary dentine starts to form during the years when pilot whales mature
sexually, there is no correlation between the two phenomena in individual whales
and the age at which secondary dentine first forms varies between different teeth
in the same jaw (Table 3). Secondary dentine deposition starts at several points
on the pulp cavity wall as discussed by Sergeant (1962), and comprises increasingly
more of the tooth tissues as the whale ages. It appears translucent on thin undecalcified sections and is less stainable in the decalcified and stained sections(Plate II, Figs I, 2, 3, and 6). The annual growth layers in secondary dentine areless regular than in ordinary dentine and the contrast between stainable and unstainable layers is usually less pronounced (Plate II, Fig. 2). However, we consider that secondary dentine is not a real obstacle to age determination in G. macrorhynchus, because (I) even in old individuals some small areas of ordinary dentine
are usually evident along the wall of the pulp cavity and (2) reading the layers insecondary dentine is not very difficult in the decalcified and stained sections (Plate
II, Figs 2 and 3).
Another characteristic of the short-finned pilot whale tooth is the depositionof a tissue on the wall of the pulp cavity that we have tentatively called " cellulardentine " (Plate III, Figs 3 to 7). In decalcified and stained sections, this tissue
looks rather like cementum. Although the " cellular dentine " contains minute
growth layers, the spacings are irregular making counting almost impossible. The
deposition of "cellular dentine" starts at the base of the pulp cavity, but progresses further along the cavity in some individuals 10 years or more in age. The
boundary between the "cellular dentine" and cementum is less obvious than between this tissue and both other types of dentine.
While preparing teeth for age determination, it was noted that " cellulardentine " tended to be laid down by unusually fibrous pulp which adhered closely
to the wall of the pulp cavity. In few exceptional males, the entire wall of the(still open) pulp cavity was lined with " cellular dentine" making it impossible tocount the dentinal growth layers (Fig. 6).
Pulp cavity
We classified the condition of the pulp cavity as follows:
1. Open pulp cavity All dentinal growth layers continuous in a longitudinal tooth
section, dentine being deposited along the entire pulp cavity wall. Similar
numbers of dentinal and cemental growth layers.
2. Closing pulp cavity Some of the dentinal growth layers (at least the latest one)
discontinuous in a longitudinally sectioned tooth. Growth layers depositedalong a limited portion of the pulp cavity wall only, the remainder being
lined with a strongly-stainable thin layer of uniform structure, which does notcontain cells in it. The number of dentinal growth layers may coincide with
the number of cementa! layers within the range of reasonable error if the best
portion of the pulp wall is used for counting.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

68

KASUYA AND MATSUITABLE 2.

LIST OF WHALES WITH CLOSED PULP CAVITVAge (yrs)
ReproSampIe - - - - - - Gonad* ductive B.L.
dentine cement
status (cm)
no.
Male
9- 1
9-23
9-75
13-16
15- 8
Female
1-16
5-N3

7- 2
7- 4
9- 3
9-38
9-47
9-55
12- 4
12-11
12-18
13-10
15- 2
15- 4
15- 5
15-13
15-18

26.5+
30.5+
34.5+
28.5+
35.5+

30.5
42.5
41.5
34.5
39.5

33.5+
22.5+
22.5+
22.5+
34.5+
35.5+
29.5+
29.5+
33.5+
32.5+
22.5+
42.5+
38.5+
35.5+
40.5+
42.5+
22.5+

52.5
38.5
26.5
32.5
38.5
38.5
45.5
34.5
48.5
43.5
37.5
42.5
42.5
55.5
47.5
51.5
25.5

2235
1475
2150
2010
1570

l+
13
9

7
10
12
13
6
4+
10
8
10

Mat.
Mat.
Mat.
Mat.

510
478
491
479
438

Mat. 378
Preg. 340
Preg. 335
Preg. 354
Rest. 360
Rest. 364
Lact. 381
Rest. 368
Mat. 354
Lact. 376
Rest. 368
Lact. 381
Rest. 350
Rest. 382
Rest. 352
Rest. 355
Rest. 371

Sample
no.
Male
16- 5
18- 1
18- 3
18-49
Female
15-33
15-37
16- 8
16-19
17-20
17-41
20- 7
22- 2
22- 7

22- 9
23- 8
24-12
24-14
24-19
24-24
25- 3
25-30
26-12

Age (yrs)

Repro- B L
Gonad* ductive (;m·)
dentine cement
status

30.5+
31.5+
40.5+
40.5+

33.5
45.5
45.5
41.5

1850
1360
1750

46.5+
29.5+
47.5+
38.5+
33.5+
35.5+
25.5+
30.5+
34.5+
40.5+
32.5+
37 .5+
38.5+
41.5+
24.5+
37 .5+
38.5+
34.5+

57 .5
35.5
62.5
43.5
38.5
47 .5
36.5
55.5
43.5
44.5
47.5
45.5
50.5
46.5
35.5
39.5
45.5
48.5

12
8

Mat.
Mat.
Mat.
Mat.

473
431
463
444

16
5
7

Rest.
Lact.
Rest.
Lact.
Rest.
Lact.

13
14
9
14
8
13
6
15
17
12
12

358
339
363
353
368
353
375
381
382
380
363
365
382
377
372

Rest.
Rest.
Rest.
Rest.
Rest.
Lact.
Rest.
Lact.
Rest.
Rest. 352
Lact. 348

880

* Weight of one testis in gram or number of corpora in ovaries (Data from Kasuya and Marsh (inpress) and Marsh and Kasuya (in press)).
Abbreviations : B.L. : body length ; Mat. : mature ; Preg : pregnant; Rest. : resting; Lact. : lactating.

Closed pulp cavity Dentinal growth layers discontinuous in a longitudinallysectioned tooth. The wall of the pulp cavity entirely covered by a thin uniform layer of stainable dentine. The number of cemental layers equal to or
greater than the number of dentinal layers irrespective of where the dentinal
layers counted.
A closing pulp cavity may occur in males over 21.5-years old and in females over
24.5-years old, and the closed pulp cavity in males over 31.5-years old and in females over 24.5-years old (Table 2). At ages between 20 and 45 years, the proportion of closing or closed pulp cavities is higher in males than in females suggesting that dentine deposition tends to cease earlier in males. About 25 to 50%
of females over the age of 40 years still have an open pulp cavity (Fig. 6).
Figure 7 documents the changes in the (maximum) diameter of the pulp
cavity that occur with increasing age. The diameter of the pulp cavity tends to begreatest at the proximal end in animals less than a year old and in the middle
region in older whales. There is no sexual dimorphism in this character. The
diameter of the pulp cavity decreases from about 10 mm for whales less than two3.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

69

SHORT-FINNED PILOT WHALE

12
8

E
E 4
c

-

0

~

Closing·

'

Cl>
Cl> 4

&

l

E

.!! 2
c

t\

/I\
I

l:

:

1

\

1

I

I

+.

1

I

I

I

I

I

I

I

l

I

"~·~<l'fy •, IJ...- .. •+- '9---4'' I '-i>--4-.-l-Y
\

\T

:

I

I

I

I

I

I

I

.....

I

I

0
Closed

.1
00

10

20

30

40

50

5558 61

Age in years
Fig. 7. The mean and range of the diameter of the pulp cavity in G. macrorhynchus.
Open circles and dotted line represent females, and closed circles and solid line
males.

1.5
6744413

E

0

2

E
1.0
c
Ill
Ill

Cb

c

13 0.5
:.c
I-

10

20

30

40

50

55 58 61

Age in years
Fig. 8. Thickness of cementum in G. macrorhynchus showing means, ranges, andsample sizes. Open circles and dotted line represent females and closed circles
and solid line males.

years old to about 3 mm in whales over 20-years old when the cavity starts to close.
" Closing" pulp cavities tend to have a relatively constant mean diameter of about
1 mm while the mean diameter of a "closed" pulp cavity ranges from 0.5 to
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

KASUYA AND MATSUI

70

30

Pulp, closed

5'-o. •

'

--o.,

0
~
0

c

60

4

ffe.
I
'

Pulp, closing

'I
I
I

:a·
'

30

I

•

0

~

u

60

3

Pulp, open
>30 yrs

cCl> 30
::J

~ 6g

2

Pulp, openL.

15-30 yrs

LL 30
0

60

Pulp, open
<15 yrs

30
0

0

0.5

1.0

1.5

Ratio
Fig. 9. Ratio of the number of cementa! growth layers to the number of dentinal
growth layers in G. macrorhynchus. 95% confidence interval for the mean (box)and 2 X SD range (bar) are indicated on each side of the mean. Open circles anddotted line indicate females, and closed circles and solid line males. I : 68 males
and 61 females below 15 years of age. 2 : 53 males and 121 females between 15
and 30 years of age. 3: six males and 45 females over 30 years of age. 4: 22
males (20-40 years) and 46 females (25-52 years). 5: nine males (30-45 years)
and 32 females (25-63 years).

1.0 mm and shows no decline with age. These observations are consistent withdentine being deposited only along limited parts of the pulp cavity wall in the" closing" stage and deposition ceasing in the "closed" stage.
Cementa! growth layers
Figure 8 shows the maximum cementum thickness plotted against age. Cementum
is absent from the teeth of very young postnatal whales. The largest individual
without cementum was a male 154 cm long and aged about 1.5 months (age estimated from body length). The smallest individual with a cementa! layer was a
163 cm long female (estimated from its length to be two or three-months old).
Seven whales less than 200 cm long had tooth cementum. Therefore, we conclude that the deposition of cementa! layers starts in G. macrorhvnchus at a few
months of age. Cementa! growth is rapid between two and four years of age (Fig.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

718). After that the thickness increases at a lower rate, but continues throughout
life. After two years of age, males tend to have thicker cementum than females(Fig. 8).
Although the cemental growth layers are much narrower than the dentinal
growth layers, the accessory layers are less conspicuous and we consider that thereadability of both tissues is about the same (compare figures in Plates I, II, and
III). When reading the cemental growth layers it is important to remember that(1) the first or second layer is usually limited to the distal portion of a tooth and(2) in older whales the later layers are usually very thin or absent in the distal
part of the tooth. Therefore a whole set of cementa! growth layers of an old
individual cannot be seen in one cross section of the tooth. It is necessary to readthe layers from the inner distal layers to the outer proximal layers as in Berardius
bairdii (Kasuya, 1977).
Figure 9 shows the number of cemental growth layers expressed as a proportion of the number of dentinal layers. In young whales there is a tendency tounderestimate the number of cemental growth layers compared with the numberof dentinal growth layers.
For most whales with an open or closing pulp cavity, the counts of dentinal
and cemental growth layers were very close. The mean difference from parity of
the ratio of cementa! layer count: dentinal layer count was only 3.4%, even though
there were some exceptional individuals in which the ratio was as high as 1.8 (Fig.
9). We therefore conclude that the deposition of cementa! layers is also annual.
Even though we have not otherwise calibrated the cementa! layer deposition
rate, we consider that cementa! layers continue to be deposited after dentine deposition has ceased, for the following reasons. (1) The age at which dentine deposition ceases is very variable and the cessation occurs concomitant with redutionof pulp cavity after the transitional " closing" stage. Thus there is no evidence tosuspect that cessation is caused by a physiological change which would also affectcementum deposition. (2) The thickness of cementa! growth layers decreases constantly throughout life with no indications of an abrupt decline. (3) The technique of reading cementa! growth layers was repeatedly standardized by checking
young teeth.
Errors in age determination
Errors due to the position of the teeth used for age determination: Hui (1980) reported
that in Tursiops truncatus the deposition of dentinal growth layers ceases earlier inteeth near the anterior and posterior ends of the row than in the other teeth. Inorder to test whether this was also true in G. macrorhvnchus, we counted the growthlayers in a series of teeth from five jaws from three whales. Each of the growthlayer counts shown in Table 3 is the middle value of three repeat counts. Even
though the pulp cavities of all the teeth of the youngest whale (No. 17-7, estimatedage 19.5 years) were open, the dentinal growth layer counts of the teeth at the endsof the row were significantly less than those of the other teeth probably because theposterior teeth were smaller and tended to have irregular growth layers. In conSci. Rep. Whales Res. Inst.,
No. 35, 1984

72

KASUYA AND MATSUITABLE 3.

Sample no.
BL, SexCOMPARISON OF GROWTH LAYER COUNTS OF SEVERALTEETH FROM THE SAME WHALE

17-7
437 cm, male

c

D

23-5
366 cm, femalescUpper teeth (numbered from anterior to posterior)
20
13
11
1
2
20
20
11
3
20
18
13
4
17
19
13
5
17
17
9
19
6
19
11
7
19
16
11
Lower teeth (numbered from anterior to posterior)
1
21
17
11
29
2
20
20
9
30
19
20
29
3
14
20
20
13
29
4
5
21
20
13
28
20
20
11
6
30
20
12
7
19
30
19
17
12
25
8
9
19
17
14
20
10
15+

D

30
29
30
30
31
30
31
28+

18-3
463 cm, male

s

12
13
9
7
8
9
9
10+

c

D

s

44
47
44
44+
45+
45+
45+

20
32+
31
27+
28+
22+
19+

11
11

46
46
46
47
46
48
46
42

32+
34+
41
41
35
46
40+
22+

17
7+
12+
13+

12+
15+
13
15
14
13
13+
9+

Code: C: No. of cementa! layers; D: No. of dentinal layers; S : Age (no. of layers) when secondary
dentine first deposited ; + : Neonatal line or first cementa! layer lost by abrasion; BL: Body
length.

trast, similar differences were not observed in the 29.5-year old female (No. 23-5).
All the teeth of the oldest animal (No. 18-3, 45.5 years) had closed pulp cavities
with the exception of the 6th tooth of the lower jaw which had a " closing " pulp
cavity. Dentine probably ceased to be deposited in this animal when it had laid
down between 36 and 46 dentinal layers. However, only 20 dentinal layers werecounted in the anterior teeth.
In contrast, no significant differences were observed between the cementa!
growth layer counts of different teeth from the same whale except for the two
smallest teeth of No. 18-3 (Table 3).
These results suggest that errors in age determination due to tooth position
will not occur if the largest tooth near the center of the row is used.

Calibration errors: Errors can occur when the growth layer count is converted into
absolute age. The age of G. macrorhynchus older than 10 years was expressed as
the nearest n minus 0.5 years where n was the number of stainable layers counted(Any incomplete stainable layers in the first or last cycle were regarded as complete
and unstainable layers were ignored). As each complete stainable or unstainable
layer represents about six months, the true age of an individual with n stainable
layers is between n-1.5 and n+0.5 years i.e. a mximum error of± 1.0 year. For
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

73

TABLE 4. INDEX OF ERROR IN AGE ESTIMATION (I, %) : DIFFERENCE BETWEEN
THE MIDDLE COUNT AND ITS CLOSEST COUNT IN THREE READINGS OF
THE SAME TOOTH EXPRESSED AS PERCENTAGE
OF THE MIDDLE COUNT
Age (yr) and Tissue usedll
Error (/)
0-15 (D)15-30 (D)>30 (D)>30 (C)

1.2
0.0
95.1
2.5
1.2
100.0
81
+0.07
1.22

4.5
7.6
87.9
0.0
0.0
100.0
66
-0.52
1.57

0.0
7 .1
85.8
0.0
7 .1
100.0
14
+0.27
1.93

0.0
0.0
55.6
44.4
0
100.0
9
-1.97
2.04

1.9
0.0
97.2
0.0
0.9
100.0
107
-0.10
1.38

3.1 2 l
6.2
80.6
7.0
3.1
100.0
129
+0.10
2.18

3.4
5.7
78.3
11.5
1.1
100.0
87
+0.02
2.24

0.0
6.5
80.6
9.7
3.2
100.0
31
+0.60
1.88

Males
<-5.0
-5.0--2.5-2.5-+2.5+2.5-+5.o;:::+5.oTotal, %No. of whales
Mean
SD
Females<-5.0-5.0--2.5-2.5-+2.5+2.5-+5.0;:::+5.oTotal, %No. of whales
MeanSD

Age based on counts of growth layers in dentine (D) (teeth with open or closing pulp cavities) or
cementum (C) (teeth with closed pulp cavities).
2l One reading of cementa! layer included.
ll

G. macrorhvnchus less than 10 years of age, the number of growth layers was counted
to the nearest 0.25 deposition cycle by estimating the thickness of the first and lastincomplete layers. The maximum error of this is 0.5 cycle (=year).
Counting errors: Since three repeat counts were done by the same reader for bothcementum and dentine with the middle value considered the best, the index oferror (/, %) is calculated by the following formula:where M indicates the middle reading and C the reading closest to the middle
reading. The result is shown in Table 4 arranged by sex, age, and tissue type.
The standard deviation of the index or error increases with the age of animals fromless than 1.4% to over 2.2%. The error expected for repeat counts done by thesame person has a standard deviation of about 2%, giving a 95% confidence rangeof about 2%X2=4% of the middle reading.
If the errors due to calibration and counting are added together, the 95%
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

Fig. 10. Conversion of body length into age in G. macrorhynchus. Means and 95%
confidence intervals are indicated. Open circles represent females and closed
circles males.

confidence range for the age estimates at ages 10, 20, 40 and 60 years are estimatedto be ±0.9, ± 1.8, ±2.6, ±3.4 years respectively. The confidence range for the
youngest ages may be slightly narrower than indicated, because the value of I
tends to be overestimated in this instance.
Conversion of body length into age
The ages of juveniles from which teeth for age determination were not available
were estimated from their body lengths as follows. For whales in each 10 cm
size-class below 400 cm (males) and 320 cm (females), the mean and coefficient ofvariation of the ages were calculated. (For whales less than 230 cm long, data for
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

75

both sexes were combined). As these mean ages fluctuated due to sampling error
they were smoothed by eye as in Fig. 10. For females, the coefficients of variation
were nearly constant and had a mean of 0.234. In the male, the coefficients ofvariation tended to decrease with increasing age (because males tend to be larger)
and had a mean of 0.182. The 95% confidence interval of the age corresponding
to each size class was calculated (assuming that age was normally distributed foreach size class and that the coefficient of variation was constant) as:(smoothed age)±(smoothed age)X (coefficient ofvariation)X2
The results are shown as squares in Fig. 10. In females and males less than
330 cm long, the confidence interval approximately coincides with the range of
observed values. In larger males the observed range tends to be smaller thanthe confidence interval, probably because the coefficient of variation was actually
decreasing not constant as assumed.
Using this technique it is possible to estimate age within two years for females
below 280 cm (mean converted age about 5 years) or for males below 320 cm(mean age about 8 years).
GROWTH CUR VE AND BODY WEIGHT
Body length frequencies
The body length frequencies in Fig. 11 are based on the data from 18 schools(Schools 7 through 24). The frequencies are biased, because the catch of a driving fishery may under-represent the juveniles in the population (see Kasuya andMarsh, in press) and because the whales below length 320 cm are missing fromone large school (School 9) (see Kasuya and Marsh, loc. cit.).
The largest of the 449 females was 405 cm long. The next longest females
were two animals of 400 cm. The adult female length frequency has a single mode
at about 360 cm (Fig. 11 ).
The maximum male body length measured in the present study was 580 cm(No. 9-171 ), which was followed by much smaller males of 525 and 520 cm. The
largest individual, which was measured by Ms C. Goebel, had testes weighing 1. 7
and 1.8 kg but no other biological data were collected. We consider that thisindividual was exceptional among the 201 males examined and may have belonged
to the larger of the two types of pilot whale recently recorded from Ayukawa*,
and that the maximum body size expected for males of the form usually taken off
central Japan will be 525 cm. The male length frequency is more diffuse than

* Since completing this study, Miyazaki and Kasuya (unpublished) have observed two types of pilot whales
off Ayukawa (38°20'N) on the Pacific coast of northern Japan in November. This is near the northernboundary of the range of G. macrorhynchus at this time of year. Both types have skull feature characteristicof G. macrorhynchus as described by Bree (1971). The smaller type is identical to those taken off central
Japan and studied in this paper. The other type is possibly a boreal form. It is from one to two meterslarger, and has more pronounced saddle mark. The forehead of the adult male is roundish rather thansquare as in the smaller type. The two forms are presumably geographical races corresponding to thosereported by Polisini (1980) from the eastern North Pacific.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

76

KASUYA AND MATSUI

80

Ill

[=::J IMMATURE
IIIIllIIlID EARLY-MATURING
fBilill LATE-MATURING
MATURE
Q ] UNKNOWN

60

Ill

::J
"O

:> 4o
:a
.£
0

449 females

20

z

0
10

200 males
200

300

400

500

Body length in cm
Fig. 11. Frequency histogram of body lengths and growth stages in G. macrorhynchus. All data from schools 7 to 24 are included. In school 9, individuals
below 320 cm are underrepresented. " Early-maturing " stage represent maleswith testes where more than 0 but less than 50% of tubules are mature, " latematuring" those males with testes where from 50% to 100% (exclusive) of tubules
are mature, and " mature " those males whose seminiferous tubules are all mature(equivalent to social maturity) (Kasuya and Marsh, in press). For further description of the stages of sexual maturity see Kasuya and Marsh (in press).

that of the female with a possible adult mode at about 4 70 cm body length. Boththe maximum and modal lengths of males are about 110 to 120 cm larger than thecorresponding figures for females.
Growth curve
In Fig. 12, the mean body length of each age group is plotted against the corresponding age for each sex. The mean growth curve between the mean birthlength of 139.5 cm (Kasuya and Marsh, in press) and asymptotic length has beendrawn by eye for each sex as an indication of the general growth trend. The
coefficients of variation of body length for each age group for each sex are shown at
the bottom. Age-length keys for the samples have been included as Appendices
1 and 2.
The mean growth curves are divided into the four phases; (1) a phase of rapid
neonatal growth, (2) a juvenile phase of less rapid but almost linear growth, (3)growth between puberty and mean asymptotic length, and (4) a phase of no increase in body length.
The first phase, in both sexes, is similar and seems to end at about 1.25 yearsof age. The mean growth in this period (mean length at 1.25 years (230 cm)mean length at birth (139.5 cm)=90.5 cm) represents a mean annual growth rateof 72.4 cm, slightly smaller than that in the first year after birth (225 cmSci. Rep. Whales Res. Inst.,
No. 35, 1984

77

SHORT-FINNED PILOT WHALE

5.0

..

4.5
MatureE
c: 4.0

Early- maturing

o 0

~

-

"'c:
C!>

-

o

00

0

--o-~<t-o--o- _2, 'ag_ -- - U SJ_o_o_ - .Q_o_ -0-0.. - - - - - - - - - - - - - - - - - - - - -2-

~;-o

o

o

o

o

o

Oo

oo

o

o_. ... o3.5• o ......o ...

Sex. maturity • o'.

---:----------

3.0

»
"'O
Sz.5

v

o

I

''
,'' ':'
''

:'
'''
''
''

'
''

2.0
1.5
0

10

30

40.

50

60

Age in years
Fig. 12. Mean growth curve of G. macrorhynchus. Open circles and dotted line represent females, and closed circles and solid line males. The mean ages and bodylengths at the onset of sexual maturity (females), of the "early-maturing" stage(male), and of the 'mature" stage (male) are indicated. Curves between birthand asymptotic length are fitted by eye. For description of the stages of sexual
maturity see Fig. 11.

139.5 cm=85.5 cm or 62.l % of the neonatal length). This phase may last slightly
longer in males because by the age of 2.5 years, males average 254 cm long, 6 cm
longer than females.
The second growth phase lasts, in females, until about the mean age of firstovulation (9.0 years, see Kasuya and Marsh, in press). During this phase the bodylengths of females tend to be several centimeters smaller than those of males ofsimilar age. The mean growth rate for females between 2.5 and 9 years is 11.4 cm
per year ((322-248) cm/6.5 years). In males, this second growth phase lasts
slightly longer until about 10 years of age but the mean growth rate is fairly similar,
about 12 cm per year ((344-254) cm/7.5 years).
The third growth phase ends, in females, at about 22 years when the growth
curve reaches the mean asymptotic length. The mean growth rate for females
during this phase is (364-322) cm/(22-9) years=3.2 cm per year. In males, thecorresponding growth phase begins at about 10 years of age with slightly accelerated prepubertal growth followed by a gradual decrease in the growth rate until
the growth curve reaches the asymptote at about 27 years. Under these circumSci. Rep. Whales Res. Inst.,

No. 35, 1984

78

KASUYA AND MATSUI

750
500
250

i

,,
I/
//

I/

'1

,,/1

100
75

'I

/1

I/
I

50

I

Ol 25

:::e.
c

-

10

..c.

Ol

•

5

(1)

~

>-

'U

0
CD

1
.75
.50
.25
.10
.05
10

15 20

30

50

70

100

150 200

300

500

Body length in cm
Fig. 13. Relationship between body length and body weight in G. macrorhynchus
plotted on a double logarithmic scale. Open circles indicate females, closed circles
males, and circle with bar individuals which died in an aquarium.

stances, calculation of a mean growth rate over this entire period is not meaningful.
The mean growth rate for males between ten years and fourteen years of age is(397-344) cm/4years=13.3 cm per year while that of males between 23 years and27 years of age is (473.5-461) cm/4 years=3.l cm/year.
The last phase starts at 22 years in females and at 27 years in males, when all
individuals stop growing. Presumably some individuals will cease growing at a
younger age and the proportion of individuals ceasing growth will increase withage until the ages mentioned above. The " mean asymptotic lengths " (in thesense usually accepted for cetaceans) for G. macrorhynchus are as follows :Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

Number ofsamples
181
35

Sex
FemaleMale

Mean asymptotic
length.
364.0 cm
473.5 cm

79

95% confidence
interval of mean
±1.9 cm±9.1 cm

These figures are close to the modal lengths in the body length frequencies.
TABLE 5. BODY WEIGHT OF G. MACRORHYNCHUS
No.
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

Body length
(cm)
12.5
23.3
30.6
36.5
52.0
59.5
65.5
6ti.5
69.5
72.0
95.0
123
144
275
275
285
286
290
310
330
335
340
400
260
263
265
281
290
291
335
355

Body weight(kg)
0.03280.21120.500
0. 750
2.20
2.94
3.97
4.15
4.75
6.40
10.70
24.50
40.20
275
250
285
245
325
410
520
380
530
650
255
237 .19377 .90348
406
379.22484.60751.90

Sex

6
6
Q

6
Q
Q
Q

6
Q

6
Q
Q

6
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q
Q

6
6
6
Q
Q

Remarks
Fetus

"
"
"
"
"
"
"
"
"
"
At capture
"
"
"
"
"
"
"
At death
after 547 days in captivity
"
"
"
"
"

270
225
311
362
192
11

228

"
"
"
"
"
"

Body weight
Table 5 shows the intact body weights of 13 fetuses and 18 postnatal individuals.
As shown in Fig. 13, whales weighed at death after being kept in the museum tend
to be heavier than those measured at capture. We considered this to be the resultof over-feeding and/or lack of exercise, and excluded those data from the following
analyses.
Figure 13 shows the relationship between body length (L, cm) and body
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

80

KASUYA:AND MATSUITABLE 6. BODY WEIGHT OF G. MACRORHYNCHUS AT SEVERAL GROWTH STAGESCALCULATED FROM BODY LENGTH-BODY WEIGHT RELATIONSHIP
Growth stage and sex

Mean body length(cm)

Body weight
(kg)

Birth
( ~ d')
Sexual maturity(~)
Asymptotic length(~)
Early-maturing stage* (d')
Mature stage*(d')
Asymptotic length
( d')

139.5
315.6
364.7
401.1
422.1
473.5

37.0
391
593
781
904
1260

* For definitions see Fig. 11, and for detailed descriptions of these stages see Kasuya and Marsh (in press).

weight (W, kg) of specimens of G. macrorhynchus plotted on logarithmic scales. The
least squares regression of 10 postnatal females is,log W = 2.6642xlog L+log (8.403x I0- 5 )275:S:L:S:400
r = 0.93
The similar relationship of 13 fetuses of both sexes is,log W = 2.8772xlog L+log (2.432x 10-5 )
12.5:S:L:S: 144
r = 0.99
The gradients of these equations are not significantly different (T-test, P>0.3). Although a larger sample may provide evidence of significantly different
gradients for the fetal and postnatal stages, we consider that a single equation
fitted to fetal and postnatal individuals is more appropriate with the present sample size. This equation is,log W = 2.8873xlog L+log (2.377x 10-5 )
12.5:S:L:S:400
r = 0.85
This equation does not include postnatal males, which as adults develop a bulbous
melon larger than that of females (Yonekura, Matsui, and Kasuya, 1980). Yonekura et al (1980) described the changes in shape which occur in G. macrorhynchus
from a slender head with a pointed rostrum during early postnatal life to the moderately bulbous head of adult females or subadult males. This change does not
significantly affect the body length-body weight relationship mentioned above.
Therefore, we suspect that the above equation will approximately describe the bodylength-body weight relationship throughout life for both sexes and have accordingly used it in calculating the body weights shown in Table 6.

DISCUSSION

Our technique of determining the age of G. macrohynchus by counting dentinal and/or cemental growth layers in haematoxylin-stained longitudinal tooth sections proved
very satisfactory. We were able to age all 543 animals in our, sample using thisSci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

81

technique.
In contrast Perrin and Myrick (1980, p. 19) recommended that cemental
layers in G. macrorhynchus should be counted in transverse tooth sections. Even
though they appreciated that it was possible to lose the first cementa! layer using
this technique, Perrin and Myrick (1980) considered that transverse sections weresuperior to longitudinal sections because they were both easier to prepare and to
read.
However, our study indicates that, even when the position of the section was
carefully selected, more than one cemental layer (either the earliest or latest layers)
could be missed from the transverse section of a relatively old tooth (Plates I to
III). We consider that the cemental layers are easier to read in longitudinal sections. A wider range of tissue can be scanned in longitudinal sections thus enabling us to eliminate the accessory layers from the count. The variability of
repeated cementa! layer counts was similar to that of dentinal layers. The difficulty of preparation was minimal by using the method we have developed. In
addition, if transverse sections are used for counting dentinal layers, the count isoften difficult in older teeth in which secondary dentine is being deposited (Perrinand Myrick, 1980). However, using longitudinal sections enabled us to observe
whole pulp cavity and to choose the most readable portion of the tooth (Plates II
and III).
Our result indicated that the stainable growth layers in dentine was formedin spring to fall and unstainable dentine in winter to spring, although the time ofalternation of dentinal layers was not precisely defined. This seasonality of dentine
deposition in G. macrorhynchus coincides with that of Tursipos truncatus studied bySergeant (1959) and Pontopori blainvillei studied by Kasuya and Brownell (1979),
but differs from that of Stenella attenuata in the western North Pacific reported by
Kasuya (1976). The seasonality of deposition of haematoxylin stainable dentine
and/or correspondence of the stainability with optical density can be different between species.
Ogden, Lee and Conlogue (Ms.) listed body lengths of 46 male and I 08
female G. macrorhynchus stranded on the east coast of the North America. In males,
the highest body length frequencies were in the ranges 470 to 480 cm (three individuals) and 480 to 489 cm (three individuals). The largest male had a bodylength of 535 cm, while the next largest was 525 cm long. In females, the highest
body length frequency was in the 360 to 369 cm range (18 individuals). The
largest female was 397 cm long and the next largest 392 cm long. These figures
are identical to our results from central Japanese coastal waters. Alagarswami,
Bensam, Rajapandian and Fernando (1973) reported the body length frequencyof 77 whales in a mass stranding of 147 G. macrorhynchus in the Gulf of Manar on
the southeast coast of India. The identification of the species was based on theskull, teeth and flipper length. The body lengths ranged from 220 to 575 cm (sexwas not given). There were two modes in the length frequency, one at 375 to
425 cm, the other at 525 to 550 cm. We suspect that the smaller and larger modes
may correspond to the asymptotic lengths of females and males respectively. BeSci. Rep. Whales Res. Inst.,
No. 35, 1984

82

KASUYA AND MATSUI

cause these body lengths are larger than those of known G. macrorhynchus but almost
identical with those of G. melaena as reported by Sergeant (1962), we initially suspected that the method of measuring body length (not detailed in the report) differed from ours. However Alagarswami (pers. comm.) has since confirmed thatthe body lengths were measured on a straight line from the tip of upper jaw to thenotch of flukes. Thus there exists a possibility that the body length of G. macrorhynchus in the Indian Ocean may be intermediate between the two geographicalforms in the western North Pacific (see footnote on page 75 ).
Kasuya (1972, 1976) showed that the increase in body length in the first year
after birth is between 55 and 65% of neonatal length in several odontoceti i.e.,
Stenella coeruleoalba, 64%; S. attenuata, 60%; Tursiops truncatus, 55 % . Collet (1981)
obtained a corresponding value of 61.3% for Delphinus delphis. Thus the value weestimated for G. macrorhynchus, 61.2%, is in good agreement with the results forother species.
Perrin, Coe, and Zweifel (1976) found for several odontocetes the following
relationship between body length at birth (X, cm) and the difference between the
fetal growth rate during the linear phase and the average growth rate during an
initial postnatal period equal to the gestation period (Y, cm/month),log Y = -1.33+0.997 (log X)
Substituting the appropriate values for G. macrorhynchus (i.e., gestation time 452
days, neonatal length 139.5, and fetal growth rate in the linear phase 10.3 cm/
month (for values see Kasuya and Marsh, in press), the above equation predicts abody length of 197.4 cm, 452 days after birth. The corresponding figure, roughly
estimated from the growth curve (Fig. 12), is 228 cm.
Ralls, Brownell and Ballou (1980) concluded that males of polygynous
cetacean species will have larger body size and higher natural mortality rate compared with the females of the same species. The result of present study (males
growing 1.30 times larger than females and living 17 years shorter) and the polygynous social structure of the the species reported by Kasuya and Marsh (in press)
agree with their conclusion.
Sergeant (1962) obtained for G. melaena the following body length (L, cm)body weight (W, kg) relationship,
W=0.000025 L 2 •895
using fetuses and juveniles below 235 cm in body length. This relationship isalmost identical with the corresponding equation that we have obtained for G.
macrorhynchus.
ACKNOWLEDGEMENTS
We wish to extend our sincere thanks to all who helped in this study. The cooperation of the dolphin hunting teams at Taiji, Futo, Kawana and Arari made thework possible by allowing the senior author to examine whale carcasses, and to
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

83

collect the necessary samples. The hunters also provided information on theschools which they had driven.
The Taiji Whale Museum provided laboratory facilities. Dr N. Miyazakicollected the body-length frequency data for one school. The field study was donewith the help of many biologists including Dr R. L. Brownell Jr., Dr S. Ohsumi,
Mr K. Kureha, Dr N. Miyazaki, Dr T. Otake, Ms E. Miyahara, Mr S. Shiraga,
Dr T. Kajihara, Dr K. Hirose and Dr S. Tanaka. Dr D. E. Sergeant kindly
cooperated in the cross-reading of several tooth slides of G. macrorhvnchus. We
thank Ms C. Goebel for her collaboration. This study was initially prepared for
the Report of the International Whaling Commission (special issue on cetacean
reproduction) as a part of a paper on the life history and reproduction of the species, but it had to be split by the financial difficulties. We wish to express ourthanks to the two anonymous referees and editor of the IWC volume for theirsuggestions and criticism. Dr H. Marsh critically read the manuscript and corrected the English. Their cooperation largely improved this paper.
The histology slides were prepared by Ms M. Oya. Ms T. Shirai, Ms M.
Nakagiri, Ms Y. Oka and Ms S. Wada assisted in data analyses, typing anddrawing.
REFERENCESALAGARSWAMI, K., P. BENSAM, M. E. RAJAPANDIAN and A. B. FERNANDO, 1973. Mass stranding of pilot
whales in the GulfofManar. Indian]. Fish. 20 (2): 269-279.
BREE, P.J.H. VAN, 1971. On Globicephala sieboldii Gray, 1846, and other species of pilot whale (notes on
Cetacea, Delphinoidea III). Beaufortia 19 (249): 79-87.
COLLET, A. S., 1981. Biology of the common dolphin Delphinus delphis L. in the NE Atlantic. Doctoral
thesis, Univ. Poitiers. 156 pp. (in French).
HoHN, A. A., 1980. Age determination and age related factors in the teeth of western North Atlantic bottlenose dolphins. Sci. Rep. Whales Res. Inst. 32: 39-66.
Hur, C. A., 1980. Variability of dentine deposits in Tursiops truncatus. Can J. Fish. Aquat. Sci. 37 (4): 712-

716.
KAsuvA, T., 1972. Growth and reproduction of Stenella caeruleoalba based on the age determination bymeans of dentinal growth layers. Sci. Rep. Whales Res. Inst. 24: 57-79.
KAsuvA, T., 1976. Reconsideration oflife history parameters of the spotted and striped dolphins based on
cementa! layers. Sci. Rep. Whales Res. Inst. (Tokyo) 28: 73-106.
KAsuvA, 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.
KAsuvA, T. and R. L. BROWNELL, jR., 1979. Age determination, reproduction, and growth of Franciscana
dolphin Pontoporia blainvillei. Sci. Rep. Whales Res. Inst. 31: 45-67.
KAsuvA, T. and H. MARSH (in press). Life history and reproductive biology of the short-finned pilot whale,
Globicephala macrorhynchus, off the Pacific coast of Japan. Rep. int. Whal. Commn. (Special Issue On Cetacean Reproduction)
KAsuvA, T., N. MIYAZAKI and W. F. DAWBIN, 1974. Growth and reproduction of Stenella attenuata in the
Pacific coast of Japan. Sci. Rep. Whales Res. Inst. 26: 157-226.
MARsH, H. and T. KAsuvA (in press). Changes in the ovaries of the short-finned pilot whale, Globicephalamacrorhynchus, with age and reproductive activity. Rep. int. Whal. Commn. (Special Issue On Cetacean
Reproduction).
OGDEN, J. A., K. E. LEE and G.J. CONLOGUE (Ms). Flipper development in Globicephala macrorhyncha I.
Sci. Rep. Whales Res. Inst.,

No. 35, 1984

84

KASUYA AND MATSUI

Growth of flippers. 22 pp.
PERRIN, W. F., CoE, J.M. 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. and A. C. MYRICK, jR, (eds), 1980. Age determination of toothed whales and sirenians.
Rep. int. Whal. Commn. (special issue 3). 229 pp.
PousINI, J.M., 1980. A comparison of Globicephala macrorhyncha (Gray, 1946) with the pilot whale of theNorth Pacific Ocean: an analysis of the skull of the broad-rostrum pilot whales of the genus Globicephala.
Doctoral thesis Univ. Southern California. 299 pp'.
RALLS, K., R. L. BROWNELL jR andJ. BALLOU, 1980. Differential mortality by sex and age in mammals,with specific reference to the sperm whale. pp. 233-243. Jn: Sperm whales. Rep. int. Whal. Commn.
(special issue 2). 275 pp.
ScHEFFER V. B. and A. C. MYRICK,jR, 1980. A review of studies to 1970 of growth layers in the teeth ofmarine mammals. pp. 51--63. In: W. F. Perrin and A. C. Myrick (eds.) Age determination of
toothed whales and sirenians. Rep. int. Whal. Commn. (special issue 3). 229 pp.
SERGEANT, D. E., 1959. Age determination in odontocete whales from dentinal growth layers. Norsk
Hvaifangst-Tid. 48 (6): 273-288.
SERGEANT, D. E., 1962. The biology of the pilot or pothead whale, Globicephala melaena (Traill) in Newfoundland waters. Bull. Fish. Res. Bd Can. 132: 1--84.
YoNEKURA, M., S. MATSUI and T. KAsUYA, 1980. On the external characters of Globicephala macrorhynchus
off Taiji, Pacific coast of Japan. Sci. Rep. Whales Res. Inst. 32: 67-95.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

APPENDIX TABLES""~>{:.. ~

~~

~~

"
~~

~

~

;,:,

~

19
20
21
22
23
24
25
26
27
28
29
30
31

18

12
13
14
15
16
17

11

n
0
1
2
3
4
5
6
7
8
9
10

Age

1

13 14 15 16 17 18 19 20 21l
l l l 4 2 l
1

l

3
2
1
l

2
3
2
1

1
1
2
1
l

1
1
3
l
l
1
l
1

1

1

1
l

1

1
1
1

l

1
1

2
4

l

22 23 24 25 26 27 28 29 30 31

Body length

1

1

1
1

3
1
1
1
2

1
2

1

2
1
2
3
1
1

3
3
3

2

3
1

2
1
1
2

1
2
4
1
1
1
4

2

1

1
3
1
4
3
1
7
5
2
3
1
3
2
1
1

3
1

4

1

4

1
4
4
2
2

2
2

1

1

1
3

1
2

3
4
1
1
4
4
2

1

2
1
2
1
3

4
5
5
4
1
1

6
4
15

11

11

1
1

1

1

2

1

1

1

9
4
5
12
5
9
8
13
10
6
10
9

11
11

3
8
7
9
5
3
2
8

11

32 33 34 35 36 37 38 39 40 No.

APPENDIX TABLE I. AGE-LENGTH KEY OF G. MACRORH'YNCHUS, FEMALE
Mean
185.45231.00245.50262.00264.00282.60294.33281.50317.50325.27332.81
343.33328.75340.22346.58350.00352.66345.00359.30354.10370.66355.60363.55369.00364.33363.00359.46363.81360.25367.20360.80366.50

S.D.

19.26
3.26
15.61
12.07
12.85
20.71
6.01
6.50
13.81
13.18
17.33
12.25
11.29
18.90
20.27
16.67
12.78
14.73
10.36
8.87
12.53
8.74
10.32
10.15
10.97
20.59
16.74
16.23
13.53
8.42
13.80
10.57

rJJ

rJJ

......

c:

~

tl

~

~

;;

c:

~
;i:..

en

00

N.

~~

<:)

;:;.

;;;-.

;->

"'
f;?

"""'1;;-

~""~
.....
~~

<.,,:::,,

Age: n:s;Age in years<n+ !. Body length: lOnsBody length in cmsl0n+9.
SD of this table=[I;(x-x)2/n]o.s

32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
1

1

1

1

1

1

1

1

3
2

1
1

3
2
1

1
2
2
1

1

1
1
1

1

4

1

1

1

1
1
4
3
2
3
3
1
1
1
1
2
3
2
2
2

1

1

1

1
1

1
1

1

1
1

2
2
1
3

2
1

2

1

1
1
1
1
1
2

1
1

1

1

1

8
3
8
8
7
6
8
2
4
4
5
7
5
5
4
6
2
1
3
1
3
0
0
4
0
1
0
0
0
0
2
369.00358.00373.25358.12373.66357 .12360.75365.00367.33367 .37348.50367.25369.75359.40363.85365.40371.40375.75356.83354.50373.00373.33355.00361.33

6.00

9.62

12.39

6.94

10.79
6.34
6.75
10. 75
10.92
11. 79
13.04
12.50
15.78
10.70
11. 72
11.30
9.62
8.21
13.32
6.84
0.50

::r:

~

-..J

trl

>
t""

~

>-l

0

"O
,.....
t""

t1

zz
l"'.I

>rj
,.....

~

0

rJl

88

KASUYA AND MATSUIAPPENDIX TABLE 2.

AGE-LENGTH

Age

Body

n

13 14 15 16 17 18 19 20 21

02

22 23 24 25 26 27 28 29 30 31 32 33 34

2
2

2

2

3

2

3

4
5
6
7
8
9
10
11

2

3
2

3
2
3

2
2

12
13
14
15
16
17
18
19
20
21
22

23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
Age: n:=:;;Age in years<n+ I.

Body length: lOn:=:;;Body length in cm:=:;; 10n+9.

SD of this table=[~ (x-Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SHORT-FINNED PILOT WHALE

89

KEY OF G. MACRORHTNCHUS, MALE
length35 36 37 38 39 40 41

42 43 44 45 46 47 48 49 50 51

52

I
3
4
4

I
2
2

2

2
2
3

2

2

2
I

2
2

2
2
2
2
2

2

No.

Mean

S.D.

8
3
5
6
I
7
2
7
5
7
8
6
2
7
6
6
6
6
7

161.62229.00258.00265.50271. 00
296.00294.00314.28328.00337.42339.37366.50379.50393. 14406.50420.00417.16451. 33
430.00519.00455.80447.75452.75468.33456.20490.50474.50473.60522.50470.80463.50427.00488.50470.00489.00

26.31
8.52
12.29
8.51

5
8
4
3
5
2
2
5
2
5
4
2
2
4
0
I
0
I
2
2
0
0
2

x)z 1o.5.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

20.06
13.00
14.52
8.85
10.67
15.91
I I. 91
1.50
15. 18
16.89
19.85
25.85
31 .95
25.16
37.64
25.66
28.64
10.20
12.79
0.50
15.50
19.94
2.50
8.54
41 .65
15.50
3.00
18.31

477.00509.00448.50448.00474.50478.00447.00

10.50
16.50

16.00

90

KASUYA AND MATSUIEXPLANATION OF PLATESPLATE IAll scale bars represent 0.1 mm.
FIG. I. Decalcified and haematoxylin-stained section from a newborn female G.
macrorhynchus (No. 17-46, 163 cm, 0.25-year old, tooth length 22 mm). N indicates the neonatal line in the dentine, and 2 and 3 the positions enlarged in Figs 2
and 3 (this plate) respectively.
Fig. 2. Higher magnification of position 2 in Fig. I (this plate). Arrow indicatesneonatal line in dentine, and E, cast of dissolved enamel.
Fig. 3. Higher magnification of the position 3 in Fig. I (this plate). Arrow andcircle indicate a stainable cementa! layer (annual layer).
Fig. 4. Decalcified and stained tooth section of an immature male G. macrorhynchus(No. 9-73, 326 cm, 5.25 years old with five annual stainable layers of full thickness and 6th (last) stainable layer of incomplete thickness (circles), tooth length
38.4 mm). N indicates the neonatal line, and 5 through 7 the positions enlarged
in Figs 5 through 7 of this plate.
Fig. 5. Higher magnification of position 5 in Fig. 4 (this plate), showing cementa!
growth layers near the neck of the tooth. Circles and arrow indicate lst to 4th
annual stainable layers.
Fig. 6. Cementa! layers at position 6 in Fig. 4 (this plate). The 2nd to 5th annual
stainable layers are indicated by circles.
Fig. 7. Cementa! layer at position 7 in Fig. 4 (this plate). Circles indicate the 3rd
to 6th annual stainable layers.
PLATE IIAll scale bars represent 0.1 mm.
Decalcified and haematoxylin-stained tooth section from a lactating female
G. macrorhynchus (No. 24-22, 366 cm, 27.5-years old, tooth length 42.8 mm). Dentine is still being deposited along the entire pulp cavity wall. C indicates cementum, E cast of dissolved enamel, N neonatal line in dentine, and the numerals the
positions enlarged in Figs 2 through 4 of this plate. The dots indicate the annual
stainable layers in dentine.
Fig. 2. Higher magnification of position 2 in Fig. I (this plate). Annual growthlayers are clearer in ordinary dentine (circles) than in secondary dentine. P indicates predentine.
Fig. 3. Higher magnification of position 3 in Fig. I of this plate. Anm1al growthlayers are clear in secondary dentine (circles). P indicates predentine.
Fig. 4. Cementa! layers at position 4 in Fig. I (this plate). Dots indicate lst to
28th annual cementa! layers.
Fig. 5. Cementa! layers at position 5 in Fig. 6. (this plate). Dots indicate 2nd to
36th annual cementa! layers.
Fig. 6. Decalcified and stained section of a tooth from a resting female G. macrorhynchus (No. 17-36, 35.5-years old, tooth length 39.5 mm). Deposition of dentine
is about to cease. C indicates cementum, E cast of decalcified enamel, N neonatalline, 5 the position shown in Fig. 5 of this plate.
Fig. I.

PLATE IIIAll scale bars represent 0.1 mm,
Fig. I. Higher magnification of pulp of the tooth in PLATE II Fig. 6. P indicates
predentine. Deposition of dentine is limited to this portion of the pulp wall.
Sci. Rep. Whales Res. Inst.,

No. 35, 1984

SHORT-FINNED PILOT WHALE
Fig. 2. Cementa! layers at position 2 in Fig. 7 (this plate). Dots indicate lst to
Sith annual growth layers.
Fig. 3. Top of the pulp cavity of tooth in Fig. 7 (this plate). A strongly-stainableuniform thin layer of dentine (S) indicates the cessation of dentine deposition
along most of the wall of the pulp cavity, but thin predentine (P) is still visible atthe top and an irregular thin unreadable layer of" cellular dentine" (C) is being
deposited. Formation of the cellular dentine has started secondarily on the pulp
wall.
Fig. 4. Middle portion of the pulp of tooth in Fig. 7 (this plate). The last two
dentinal layers merge in the pulp wall cavity which is covered by thin stronglystainable uniform dentine (S). Secondary deposition of" cellular dentine" (C)is also visible.
Fig. 5. Base of the pulp cavity of tooth in Fig. 7 (this plate). The last readable
dentinal growth layer was deposited as indicated by the arrow. " Cellular dentine " ( C) is still being deposited.
Fig. 6. Higher magnification of position 6 in Fig. 7 (this plate). Thick " cellulardentine " is being deposited.
Fig. 7. Decalcified and stained section of a tooth of a lactating female G. macrorhynchus (No. 24-14, 382 cm, 50.5-years old, tooth length 38.3 mm). There are 39
annual stainable layers in the dentine and 51 in the cementum. C indicates
cementum, E cast of dissolved enamel, N neonatal line in dentine, and 2 and 6 thepositions shown in Figs 2 and 6 of this plate respectively.

Sci. Rep. Whales Res. Inst.,

No. 35, 1984

91

争8
6f §
￡ ・oN
・
s
aySJ/V可
t
ヤ
1・
i
f
a
u・
口S

／
＇S
i
i
/

LV

Inb

fフ
ぺ CTNVV人
，
口SV){
I
flS
.
L
VJ

IO
.
'
UV'lcIPLAn:JI

KASUYA AND 恥1.ATSUI

S
c
i
.Re
戸
. 1ノ'
h
a
l
e
sRe
s
.I
n
s
t.
,
λr
o
.3
5
,1
984

lT:LLV~lcl
T

N
O
￡'
§
f86f'
S
'
!
u・
／a
＜
l・
.1
(
υ1
1
a
ls
l
a
r
t・

l
"/f

sv河
JV V人n、？
可〈！
IOS.LVJI

SOME OBSERVATIONS ON THE SCHOOLS OF
DALL/- AND TRUEI-TYPE DALL'S PORPOISESIN THE NORTHWESTERN PACIFICNOBUYUKI MIYAZAKI
Department of Zoology, National Science Museum, Tokyo

LINDA L. JONES
National Marine Fisheries Service, Seattle

AND
RICHARD BEACH
Washington Department of Game, 01,ympia

ABSTRACTDuring 349 hours of sighting surveys conducted from late June to earlyAugust 1979 in the northwestern North Pacific Ocean and the southern Bering Sea, 167 schools of Phocoenoides dalli were sighted. Three kinds of schools(dalli-type, truei-type and mixed schools composed of both types) were observed in the southern areas surveyed while only dalli-type schools were seenin the northern areas. School size of dalli-type schools was smaller thanthat of the truei-type or mixed schools. Truei-type as well as mixed schools
tended to occur in warmer waters (above l3°C) than dalli-type schools during
the second part of the survey. Behavior of animals in mixed schools was notapparently different than in the segregated schools. Mixed schools were composed of all sizes of animals including an adult-calf pair. The relationshipbetween the two color types is discussed.
INTRODUCTION

Phocoenoides dalli (True, 1885) is widely distributed in the cold waters of the north-western North Pacific (Nishiwaki, 1972; Ohsumi, 1975; Kasuya, 1976; Kasuya,1978). Two major color types exist but little is known concerning the systematic
relationship of the two types. Based on five external morphological differences
Andrews (1911) described them as two species: P. truei and P. dalli. Kuroda (1954)
described them as two subspecies. He concluded based upon sighting records of
mixed schools of the truei-type and the dalli-type, and the presence of a truei-type
fetus in a dalli-type pregnant female, that the truei-type is a small population (race)
evolved in the Japanese waters by a dominant mutation from the dalli-type distributed in the North Pacific Ocean, the Okhotsk Sea and Sea of Japan. However
Kasuya (1978) questioned whether the fetus in the dalli-type female was a trueior dalli-type. Houck (1976) observed a mixed school of the two color forms off
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 93-105

94

MIYAZAKI, JONES AND BEACH

northern Honshu, Japan. Based on the ecological and morphological considerations of the genus, he concluded that P. dalli is polymorphic in color pattern withtwo major color morphs, the dalli- and the truei-types, and that there are not separate
geographical races or subspecies.
From sighting records of P. dalli and an analysis of the school structure, Kasuya (1978) concluded that the school formation is to some degree dependent oncolor pattern and that all the dalli-type individuals found off the Pacific coast ofJapan may not be from the Japanese coastal population, but that at least some ofthem, especially those in the schools not containing the truei-type, migrate from theoffshore population in the northwestern North Pacific and the western Bering Sea
or from the Sea of Japan-Okhotsk Sea population. He considered that interbreeding between the populations would be less frequent than expected on the basis of
the apparent coexistence of the two color types.
The discussion above makes it clear that the taxonomic problem of the twocolor forms of P. dalli has not been completely resolved. This report provides additional information on school composition and distribution for two color types of
Dall's porpoises and a discussion on their relationship, including the possibility ofinterbreeding between the two color types.
METHODS

A Japanese salmon research vessel, the R/V Hoyomaru No. 67 (size: 299 grosstons; cruising speed: 10 knots), was chartered by the Ja pan Fisheries Agency fora US-Japan cooperative Dall's porpoise research project. A marine mammalsighting survey was conducted on board this vessel in the northwestern North
Pacific Ocean and the Bering Sea from 29 June to 9 August, 1979. The cruise trackis shown in Fig. 1. Total observation time was 349 hours. Observations weremade by Miyazaki and Beach from the upper bridge except during night time,
heavy rain and heavy fog. Since the main objectives of this cruise were experimental salmon gillnetting and study of the incidental catch of Dall's porpoises,
most of the survey effort was spent during the transits between the coast of Japanand the western Bering Sea.
For each sighting, data were recorded on estimated body size, color type andnumber of porpoise and surface water temperature. Estimates of body size weremade for Dall's porpoises coming close to the bow of the vessel, within about 20 m.
Animals were classified as small (less than 150 cm in body length), medium (150180 cm) or large (more than 180 cm). Calves were distinguished by their small
size and continued association with a larger animal.
RESULTS

Distribution
During this survey, 655 Dall's porpoises were sighted in 167 schools. There
were 68 schools of the dalli-type, 24 schools of the truei-type and 7 mixed schools
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

!'"'·

::-..

"'

~

"'

......
~~
";;-

Yi~

""::ti

~

~~

,
'

,IL

~-(8.5)r((6.y,/1(6.sJ

2(7.y/

150°E

160°E

170°E

5(6.5)

.

.•
•'·

180°

·~ • ••••

170°W

·"

,,,
.... ........"'-..

13

I

I

40°N

45N

.

0

so N

0

ss N

,GO•N

Fig. 1. The cruising course of the R/V 67th-Hoyomaru during 29 June and 9 August, 1979. Numbers indicate dates, closed circles,
noon position; solid lines, sighting course; and broken lines, course passed in darkness. Figures in parentheses indicate the surface
water temperatures (°C) at noon. The temperatures of noon positions during 7 July and 30 July range from 6.2° to 8.6°C.

_,,_/9(19.6),e.',,..,...,7(14.1)/7(,,.e........-B(~~.4)

Jun.29(7 .9)/"~12.6),,,../July1(6.Lil•• , __ /3;(7.3)

f T

~-"'

.
3

~

(6.7~',,..-~ ~,,..;r")<'~,/4(8.9)~:-,.:::~5(9.2)

•••

,

.,

4

,,."' q"",/~6.4)31(8~, _,,-~

Aug.1(8.~/,,;-;L 20 24

23~( 6.2 - 8.6)

July 7-30

,,

(.J1

r.o

rJJ

t::<:I

rJJ

0

-

~
"d

"d

0

r)5

~

~

0>rj

rJJ

t"'

:i::
0
0

rJJ

0

96

MIYAZAKI, JONES AND BEACHTABLE 1. SIGHTING RECORDS OF THE SCHOOLS OF DALL'S PORPOISES IN THE
NORTHWESTERN NORTH PACIFIC AND THE BERING SEA IN 5° BY 10° AREAS
Schools of color typeAreasdalli-type

truei-type

mixed

unknown

Total
No.

No.

%

No.

%

No.

%

No.

40°-45°N
140°-l50°E

4

25.0

10

62.5

2

12.5

8

24

II

40°-45°N
150°-l60°E

4

21.1

13

68.4

2

10.5

11

30

Ill

45°-50°N
150°-l60°E

7

77.8

I I. I

918

IV 45°-50°N
160°-170°E

4

100

0

0

0

0

0

4

v

50°-55°N
160°-170°E

11

84.6

0

0

2

15.4

3

16

VI

50°-55°N
l 70°E-J80°

5

100

0

0

0

0

5

10

VII

55°-60°N
170°E-180°

13

100

0

0

0

0

8

21

VIII 55°-60°N
180°-170°W

20

100

0

0

0

0

24

44

68

68.7

24

24.2

7

7 .1

68

167

Total

11.1

of the two types. The remaining 68 schools could not be identified as to color type.
The sighting records were grouped into eight areas of 5° latitude by 10°
longitude (Table 1). All three kinds of schools, dalli-type, truei-type and mixed,
were sighted in areas I, II and III, while only schools of the dalli-type were observed in areas IV, VI, VII and VIII. The ratio of the dalli-type schools to total
identified schools was about 21-25% in the southern areas (I and II), increased
to 78% in area III, and to 84% or more in the remaining northeast areas. The
ratio of mixed schools to total identified schools was 10-12% in the areas where
both the dalli-type and the truei-type schools were sighted.
As shown in Fig. 2, the truei-type schools were sighted more frequently inthe southern part of the northwestern North Pacific than in the northern region.
The area where the truei-type schools were sighted was south of 45°46'N and westof 153°39'E, while dalli-type schools were observed north of 42°52'N and east of
144 °32' E. All mixed schools of the two col or types were observed in the area between 41°09'N to 50°56'N and 147°55'E to 163°58'E. Three of them were sightd
in the area where the dalli-type schools were predominant (Fig. 2, Areas III andV), and four in the area where the truei-type schools were predominant (Fig. 2,
Areas I and II).
Table 2 shows a comparison of the density and school structure of P. dalli in
the North Pacific and the Bering Sea areas. Although the total number of Dall's
porpoises per observation hour is the same in the two areas, the number of schools
per observation hour is somewhat larger in the Bering Sea. Especially, the numberof dalli-type schools per observation hour in the Bering Sea is about twice as large
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

""~

~

~

>!>."'~~~~""'::ti

~·

~~

;:i

.11'0 II

.A

<Si

I
000

..~
of'

0

IV

.A

VI

0

~

...
8

'

Aoo

VIII

~4'1'

0 0

"'1

1so·E

0

1so E

170°E

180°

_ _ _ _ _......__ _ _ _ _ __.__ _ _ _ _ __.__ _ _ _ _ ___._ ___,

116flf" ...

"
0elP~

III

•

()

,..

I

"l •'

c9 .A
ooc9J!

\

0--.l<:JP l(JA

U<DD.A A 8Fig. 2. Sighting records of the school of Phocoenoides in the northwestem North Pacific. Open circles indicate the schools of the dallitype; closed circles, the schools of the truei-type; half closed circles, the mixed schools of the dalli-type and the truei-type; and closed
triangles of the schools of unknown color type of Phocoenoides. For I, II, III, IV, V, VI, VII and VIII see text and Table 2.

4~N.__

45°N

so·N

55°N i-----------;---~

#'

VII

a'

1JJ

....,
"'

1JJ

trj

1JJ

6
......

6:;d

1JJ

t::

~

0
>'l'j

1JJ

t""'

0
0

@

98

MIYAZAKI, JONES AND BEACHTABLE 2.

COMPARISON OF RELATIVE DENSITY OF DALL'S PORPOISES
Pacific area

Areas and color types
No. of schools
No. of porpoises
Mean school size
Observation hours
No. of school/hour
No. of porpoises/hour

T

D

M

u

Total

24
133
5.5

30
114
3.8

7
38
5.4

33
128
3.9

0.11
0.61

0.14
0.52

0.03
0.17

0.15
0.58

94
413
4.4
220
0.43
1.88

T indicates a school of truei-type ; D, a school of dalli-type ; M, mixed school of two color types; andas that in the North Pacific.
School size
Table 3 shows the school size of the various types of P. dalli. School size
ranged from 1 to 16 individuals. Schools of 10 or less individuals were 91. 7 %(22 out of24 schools) of the truei-type schools and 98.5% (67 out of68) of the dallitype. About 60% of all the schools were composed of two to four individuals.
The range in school size was similar in the three types of schools (truei, dalli, andmixed schools). The mean school size of the dalli-type was about 3.8 individuals
in both the Bering Sea and the Pacific (Table 2). The mean school size of thetruei-type was 5.5 individuals and was significantly larger than that of the dallitype in both areas (t-test, p<0.01 ). The mean school size of the mixed schools
was 5.4 individuals, and was not significantly different from either the truei-type
or the dalli-type (t-test, p>0.8), however, the sample size is small (n=7).
TABLE 3.

SCHOOL SIZE OF DALL'S PORPOISES IN THE NORTHWESTERNNORTH PACIFIC AND THE BERING SEA
School type

School size
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Total

Total
truei-type

dalli-type

mixed

unknown type

0
3
5
3
4
2
3
0

11
8
19
9
6
9
2
3
0
0

0
3

7
22
17
8
7

1
0
1
0
0
0
1
24

0
0
0
0
0
68

0
0
0

0
0
0
0
0
1
0
0
7

2
1
0
2
0
0
0
1
0
0
68

18
36
42
20
17
12
8
5
1
3
1
0
2
0
1
167

Sci. Rep. Whales Res. Inst.,
No. 35, 1984SCHOOLS OF DALL'S PORPOISES99

BETWEEN THE NORTHWESTERN NORTH PACIFIC AND THE BERING SEA
Total

Bering Sea
T

D

M

u

Total

T

D

M

u

Total

0
0
0

38
139
3.7

0
0
0

35
103
2.9

24
133
5.5

68
253
3.7

7
38
5.4

68
231
3.4

0
0

0.29
1.08

0
0

0.27
0.80

73
242
3.3
129
0.57
L.88

0.07
0.38

0.19
0.72

0.02
0.11

0.19
0.66

167
655
3.9
349
0.48
1.88

U, a school of unknown color type.

Table 4 shows the observed percentages of each school type for each school
size in the area between 41°N and 51°N, and between 144°E and 166°E, where thethree school types were observed in the present survey. Of the 247 Dall's porpoises
in 52 schools sighted in this area, 157 individuals (63.6%) were the truei-type and 90(36.4%) were the dalli-type. The probability of these two color types for eachschool size was calculated using this proportion, assuming random combination of
two color types. The calculated percentages for the mixed schools were higher
than those actually observed. These data suggest that the schools of P. dalli arenot formed by the random combination of the two color types, but that school
formation of the species is related to color type. This is the same conclusion reached by Kasuya (1978) based on observations off Sanriku coast of Japan during
January, February, May and June.

TABLE 4. THE OBSERVED AND CALCULATED PERCENTAGES OF EACH COLOR
TYPE FOR EACH SCHOOL SIZE OF DALL'S PORPOISES IN THE SOUTH
OF 51°N, WHERE THREE COLOR TYPES ARE DISTRIBUTED
School
size
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Total

Observed
truei

3
10
11
6
6
3
4
4

0
1
0
0
1
52

Sci. Rep. Whales Res. Inst.,

No. 35, 1984

Calculated

No.
mixed

dalli

0
30.0
45.5
50.0
66. 7
66.7
75.0
0
100
100

0
30.0
9.0
0
0
0
25.0
25.0
0
0

100
40.0
45.5
50.0
33.3
33.3
0
75.0
0
0

100

0

0

100

0

0

100
46.2

0
13.5

0
40.4

truei

63.6
40.4
25.7
16.3
10.4
6.6
4.2
2.7
1. 7
1.1
0.7
0.4
0.3
0.2
0.1
0.1
20.9

mixed

dalli

46.3
69.3
81.9
89.0
93.2
95.7
97.3
98.3
98.9
99.3
99.6
99.7
99.8
99.9
99.9
73.0

36.4
13.3
4.8
1.8
0.6
0.2
0.1
0
0
0
0
0
0
0
0
0
6.0

MIYAZAKI, JONES AND BEACH

100
TABLE 5.

SURFACE WATER TEMPERATURE OF THE SIGHTING POSITIONS OF
SchoolSurface watertemperature
(°C)
5
6
7
8
9
10
11
12
13
14
15
16
17
Total

truei-type

dalli-type

J to B

B to JBe

T

J to B

B to J

Be

T

0
1
4
0
0
0
0
0
0
0
0
0
0
5

0
0
0
0
0
0
0
0
3
7
0
6
2
18

0
0
0
0
0
0
0
0
0
0
0
0
0
0

0

1
6
2
1
0
0
0
0
0
0
0
0
0
10

0
0
0
7
6
0
0
2
0
0

0
7
16
6
0
0
0
0
0
0
0
0
0
29

13
18
14
6
0
0
2
0
0
1
0
0
55

4
0
0
0
0
0
3
7
0
6
2
23

0
0
16

J to B indicates transit from Japan to the Bering Sea; B to .J transit from the Bering Sea to Japan;

Surface water temperature
The frequency of sightings of each school type and surface water temperatures
is shown in Table 5. The temperature for the dalli-type ranged from 5.9° to
15.8°C, similar to that for the truei-type (6.5° to 17.1°C). On the way from Japanto the Bering Sea (late June to early July), the number of sightings is low and thetemperature ranges of the two types overlap, however the mean surface watertemperature of the 5 truei-type schools was 7.4°C (range: 6.0°-7.9°C) while themean for the 10 dalli-type schools was slightly lower, 6.8°C (range: 5.0°-8.9°C).
On the return from the Bering Sea (early August), the mean temperature of thesightings of the 18 truei-type schools was 15.3°C (range: 13.6°-17.7°C) and washigher than the mean temperature of 9.8°C for the 16 dalli-type schools (range:
8.0°-l5.8°C) which were predominantly in waters below l0°C (13 out of 16
schools). These results indicate that the truei-type school tends to be distributed
in relatively warmer waters than the dalli-type school. The water temperaturesduring sightings of the mixed schools were from 5.9° to 16.4°C (mean: ll.7°C)
and therefore were within the range of both the truei-type and dalli-type. During
the return to Japan from the Bering Sea, the mixed schools tended to be in thewarmer waters (4 out of 5 schools).
Observations of the mixed schools
Seven mixed schools (two in July and five in August) were observed in thissurvey (Table 6).
At 1215 hour (Japanese standard time) of 7 August, a mixed school of 14
porpoises were sighted. A mixed group of 12 porpoises among them firstly approached the vessel and rode the bow wave. Several minutes later, a mixed pair
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

101

SCHOOLS OF DALL'S PORPOISESDALL'S PORPOISES IN THE NORTHWESTERN NORTH PACIFIC AND THE BERING SEA
type

J to B B to J
1

0
0
0

I

0
0
0
0
0
0
0
0
0
0
0
2

0
0
0
0
0
2
0
2
0
5

Total

unknown

mixed
Be

T

0
0
0
0
0
0
0
0
0
0
0
0
0
0

J to B B to J
0
4

0
1
0
0
0
0
0
2
0
2
0
7

0
0
0
2
0
0
0
1
4
5
1
1
0
14

I

3
0
0
0
0
0
0
0
0
0
8

Be

T

J to B

B to J

Be

T

0
3
14
3
0
0
0
0
0
0
0
0
0
20

0
7
15
8
0
0
0

2
12
7
4
0
0
0
0
0
0
0
0
0
25

0
0
0
10
6
0
0
3
7
14
2
9
2
53

0
10
30
9
0
0
0
0
0
0
0
0
0
49

2
22
37
23
6
0
0
3
7
14
2
9
2
127

I

4
5

0
42

Be, the Bering Sea; and T, Total.

of large truei- and dalli-type porpoises joined the first group. In this mixed pair,
one swam slightly ahead of the other (Plate 1, Figs 1 and 2), alternating the leadand these two porpoises behaved similarly swimming side by side, keeping a direction and surfacing simultaneously to breathe (Plate 1, Figs 3 and 4). This may
indicate that there is no dominant-recessive relationship in social status between
them. The mixed pair left the bow after several minutes but the other 12 porpoises remained without apparent change in their behavior. In the other 12 porpoises, one dalli-type and two truei-type small porpoises (about 1.5 m in body
TABLE 6.

Schoolno.

Date

COMPOSITION OF MIXED SCHOOLS OF DALL'S PORPOISE SIGHTED
IN 1979 IN THE WESTERN NORTH PACIFIC OCEAN
Time

Total
group
dze

Truei-type
Size

No.

2 July

0805

7

large

2
3
4

3 July2 August
7 August

1540
1045
1215

3
2
14

mediummedium5

7 August

1700

8

6
7

8 August
8 August

1545
1700

2
2

Sci. Rep. Whales Res. Inst.,
No. 35, 198411r

Dalli-type
No.

Size
large

2

3
small;
9 medium
and/or large
5 2 large;
1 large with a calf;
1 medium
large
large

r

mediumlarge

small;
2 medium
and/or large
large

large
large

Unknown
type
5

0
0
0

2

0
0

Comments
pair
mixed
some
moved
distance fromother porpoises

102

MIYAZAKI, JONES AND BEACH

length) were found. As these three young porpoises were not accompanied bylarge porpoises, they seem to be at the stage after the weaning.
Later in the day (1700 hour) a mixed school of 8 porpoises was observed in an
apparent feeding behavior, swimming in a circle, making frequent dives. Five ofthem came to the bow in three groups (a pair of truei-type of adult size; an adult
truei-type with a calf of truei-type and an adult dalli-type; and a medium truei-type).
These two adult porpoises with the calf swam together throughout the 30-minute
observation period.
From these observations, we conclude that the two color types of different
growth stages, including adults with a calf, can form a single group and there were
no apparent differences in the behavior of the mixed school compared to schoolsof uniform color type.
Formation of mixed schools
Only three mixed schools of the truei-type and the dalli-type have been studied
off Hokkaido on 13 July 1954 (Kuroda, 1954), off northern Honshu in February(Houck, 1976) and off Sanriku in winter (Kasuya, 1978). However, presentsightings of seven mixed schools and Miyazaki's observations of other two mixed
schools off the Sanriku coast of Japan on 27 March 1972 and on 8 March 1979
(unpublished data) suggest that the mixed school is not necessarily rare in theoverlapped area of two color types. There is no trend in the sighting time of themixed school during the observation time (0500-0900 hour) (Table 6). The
mixed school was sighted not only in the coastal waters (Kasuya, 1978; Miyazaki,
unpublished data) but also during the present cruise in the waters up to approximately 180 nautical miles offshore. From these informations it can be safely said
that in the overlapped area of two color types the mixed school seems to be formed
in any time in the day, throughout most of the year and in both coastal andoffshore waters.
Composition of seven mixed schools sighted in the present cruise (Table 6)
suggests that there are three types of mixed schools, Type I: Combination of
single truei-type porpoise with single dalli-type porpoise; Type II: Combinationof single porpoise of one color type with two or more porpoises of other color type;Type III: School containing two or more porpoises of truei-type and two or more
porpoises of dalli-type. Three mixed schools (school nos 3, 6 and 7 in Table 6)
and one mixed school (school no. 2) belonged to Type I and II, respectively. The
mixed school no. 4 (11 truei-type and 3 dalli-type porpoises) belonged to Type III.
This was sighted in the higher density area, where 52 porpoises in 6 schools weresighted in the 51 minute-observation (1215 to 1306 hour on 7 August) corresponding to approximately 3 X 105 m 2 research areas. Two mixed schools (school nos
1 and 5) should be classified into Type II or III when several individuals of unknown color type are considered.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984SCHOOLS OF DALL'S PORPOISES103

DISCUSSION

Based on information on P. dalli in the northwestern North Pacific Ocean off theKuril Islands, Ohsumi (1975) indicated that the northern limit of the truei-type
was 48°N and the eastern limit was 167°E. Kasuya (1978) reported that thetruei-type seemed to be distributed in the summer season from 42° to 54°N andfrom the east coast of the Kuril Islands to l 68°E. Sightings of the truei-type havebeen made subsequently to 180° (NMML, unpublished data). The sighting positions of the truei-type obtained in the present study are distributed within thelimits of these studies. Most of the truei-type were distributed in the southern areas
off the Pacific coast of Japan whereas the dalli-type were less in number in thisarea.
During the present survey, P. dalli were sighted in surface water temperaturesfrom 5.8° to 17.1°C. Within this range, there is no significant difference in thetemperature preference between the two color forms. However, in August during
the transit from the Bering Sea to Ja pan, the truei-type schools were usually sighted
in warmer waters than the dalli-type. Mixed schools also tended to be in warmer
waters at this time (4 out of 5 schools).
In the winter season, P. dalli (mostly truei-type) migrates into the waters off
the Sanriku region (Pacific coast of Japan) where the surface water temperature is
5° to 8°C (Miyazaki, unpublished data). Few dalli-type schools are reported thereat this season (Kasuya, 1978). Small numbers of mixed schools are seen during
the same season (Kasuya, 1978; Miyazaki, unpublished data). From February to
March, the southern range of the truei-type schools reaches off Choshi (34°44'N,
140°50'E) where the surface water temperature is about 14°-l 7°C (Kasuya, 1978;
Miyazaki, unpublished data). Thus, most of the truei-type schools appear not to
migrate into areas warmer than 18°C. On the contrary, the water temperatureof the truei-type in the northern range certainly overlaps that of the dalli-type.
From these informations it can be said that the northern range of the truei-type
schools may not be limited by the surface water temperature only but also byother factors such as competition with the dalli type.
Sightings of the mixed school of the large dalli- and truei-types porpoises (bodylength~ 180 cm) in the present cruise during 29 June to 9 August suggest that thetwo color types may interbreed because of the beginning of the breeding season for
P. dalli in early to mid-August (Mizue et al., 1966; Kasuya, 1978). Kuroda (1954)
reported a dalli-type female having a truei-type fetus, although Kasuya (1978)
questioned whether the fetus was a truei-type because of his belief on the difficultyof separating two color types in the fetal stage. Newby (1982) also reported thata dalli-type fetus was found in a truei-type female and the reverse case, and a dallitype fetus was found in a black variant female. These evidences support the hypothesis that the two color types may interbreed.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

104

MIYAZAKI, JONES AND BEACH

ACKNOWLEDGEMENTS

We thank the captain and crew of Hoyomaru No. 67 for their cooperation, and Mr
0. Sano and Dr S. Ohsumi of the Far Seas Fisheries Research Laboratory for giving us chance for this study. Drs H. Ogi and D. Ainely, and Mr M. Narita are
acknowledged for their kind help during this survey. We are indebted to Dr T.
Kasuya of the Far Seas Fisheries Research Laboratory who gave us valuable suggestions.
REFERENCES
ANDREWS, R. C., 1911. A new porpoise from Japan. Bull. Amer. Mus. Nat. Hist. 30: 31.
HoucK, W. J., 1976. The taxonomic status of the porpoises genus Phocoenoides. Paper ACMRR/MM/
SC/114, FAO Scientific Consultation on Marine Mammals, Bergen.
KAsUYA, T., 1976. Preliminary report on the biology, catch and populations of Phocoenoides in the western
North Pacific. Mammals in the seas. FAO Fisheries Series No. 5, Vol. IV, 3-19.
KASUYA, T., 1978. The life history of Dall's porpoises with special reference to the stock of the Pacificcoast of Japan. Sci. Rep. Whales Res. Inst., 30: 1-63.
KURODA, N., 1954. On the affiinity of the Dall's and True's porpoises. Bu//. Yamashina Ornithol. Res. Inst.,
5: 44-46.
MrzuE, K., K. Yoshida, and A. Takemura, 1966. On the ecology of the Dall's porpoise in Bering Sea andthe North Pacific Ocean. Bull. Faculty Fish. Nagasaki Univ., 21: 1-21. (in Japanese, with English summary)
NEWBY, T., 1982. Life history of Dall's porpoise (Phocoenoides dalli, True 1885) incidentally taken by theJapanese high seas salmon mothership fishery in the northwestern North Pacific and western Bering Sea,
1978 to 1980. Ph.D. dissertation. University of Washington, 1982. 155 p.
NrsHIWAKI, M., 1972. General biolog_y. pp. 3-204. In: S. H. Ridgway (ed.), Mammal of the Sea. Charles
C Thomas Publisher Illinois. 812 pp.
0HsuMr, S., 1975. Incidental catch of cetaceans with salmon gillnet. J. Fish. Res. Board Can., 32 (7): 12291235.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984SCHOOLS OF DALL'S PORPOISESEXPLANATION OF PLATE
PLATE I
A portion of a mixed school (no. 4 in Table 6) composed of 11 truei-type and 3 dallitype porpoises sighted at 42°48'N, 153°05'E, 1215 hour, 7 August 1979.
Fig. 1. A pair of adult truei-type and adult dalli-type (the left two porpoises) werecoming close to the bow of the research vessel.
Fig. 2. The dalli-type was swimming behind the truei-type in a line with a characteristic splash of water.
Fig. 3. A pair of the truei-type and the dalli-type were surfacing simultaneously tobreathe with turning their heads to a direction.
Fig. 4. A pair of the truei-type and the dalli-type were just diving into water after
breathing.

Sci. Rep. Whales Res. Inst.,
No. 35, 1981:

105

I宜.LV
寸d

t86T'
i
;
r
;・
ON
・
1
s
1
ザ
・s
a
Ns
a
7
m
1
1
1・
r
f
a
N・
"S

6

H:
)
V
3
8
"GNV S3NOf 'rnvzvλn可BEHAVIOR AND SEGREGATION OF THE DALL'SPORPOISE IN THE NORTHWESTERN NORTHPACIFIC OCEANTOSHIO KASUYA 1
Ocean Research Institute, University of Tokyo, Minamidai, Nakano-ku Tokyo, 164 JapanAND
LINDA L. JONES
National Marine Mammal Laboratory, National Marine Fisheries Service, Seattle, Washington

ABSTRACT

To improve knowledge of the life history of Dall's porpoise, Phocoenoides
dalli (True, 1885) that are incidentally caught by the Japanese salmon mothership fishery in the northwestern North Pacific, a 34-day cruise was conductedduring August-September, 1982, after the fishing season. A total of 710 Dall's
porpoise were sighted and 80 were caught using hand-held harpoons. The
species' southern limit was at 41°N latitude, at a surface water temperature of
l8°-l9°C, and overlapped the range of Lissodelphis and Lagenorhynchus. Distribution of the truei-type was limited to the Japanese coastal waters and thenumber sighted was negligible east of 155°E. Density of Dall's porpoise washigher in the western and northern parts of the research area, and somewhat
lower in the southeast. More Dall's porpoise rode the ship's bow wave during mid-day than in the morning or evening, and in areas where the surface
water temperature was 11°C or above. In areas with a surface water temperature of 11°C or below, most of the Dall's porpoise avoided the ship. The
latter areas had a high number of mother-calf pairs and calves possibly
weaned, none of which rode the bow wave. Adults not accompanying calves
were sighted in both areas. School size was not different between the twoareas. Most of the specimens were taken in the southern part of the study
area. Males predominated and most were 2 to 6 years old, around the ageof attainment of sexual maturity. Lactating individuals were significantly
scarce in the sample. The dalli-type reached sexual maturity at a smaller
body length than the truei-type.
Based upon comparisons of results from this cruise with those obtained
from the salmon mothership fishery since 1978, we conclude that, during theseason from June through September, (I) females in the state of late pregnancy, lactation, or pregnancy and simultaneous lactation are mainly distributed in the northern area, and (2) the southern area is mainly occupied bymales and some females not accompanied by calves.

1

Present address:
Japan.

Far Seas Fisheries Research Laboratory, 5-7-1 Orido, Shirnizu-shi, Shizuoka-ken 424,

Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 107-128

108

KASUYA AND JONESINTRODUCTION

Dall's porpoise, Phocoenoides dalli (True, 1885 ), was first reported by Mizue andYoshida (1965) to be taken incidentally in the northwestern North Pacific Ocean
by the Japanese salmon drift net fisheries that started offshore operation in 1952.
Little information was available on the magnitude of the incidental take or on the
biology of Dall's porpoise prior to the implementation in 1978 of the U.S.-Japan
cooperative research program under the auspices of the International Convention
for the High Seas Fisheries of the North Pacific Ocean. Beginning in 1978, biological samples were collected from Dall's porpoise captured in gillnets and returned to the salmon motherships for examination and dissection by U.S. biologists
onboard. The specimens were analyzed to obtain information on the life history
parameters. However, since the biological data were collected in the salmon
mothership gillnets during the limited annual fishing season (June-July) and in alimited portion of the porpoise geographic range (Nishiwaki, 1967), there wasconcern about the representativeness of the sample and whether there was any
bias in the data. To address these questions the Japanese Government, in 1982,
conducted a cruise to observe and catch porpoise outside the fishing area andseason. This paper reports information obtained through this cruise on the life
history of the Dall's porpoise.
MATERIALS AND METHOD

Outline of Cruise
The vessel was the Hoyomaru No. 12 (overall length: 42 m, gross tonnage:299), chartered by the Fisheries Agency of Japan. The research period was 34 days,
sailing from the port of Kesennuma on 17 August 1982, and returning on 17 September 1982. The research was conducted in the northwestern North Pacific between 140°E and 174°E, and between 40°N and 50°N outside the US and USSR
Fishery Conservation Zones (FCZ) (Fig. 1).
During the study period, there were two days (8 and 11 September) when
research was not conducted due to rough seas (Beaufort wind scale 6 or higher).
On September 16, the ship was in the USSR FCZ, and no Dall's porpoise werechased or captured although there were sightings.
1.

2.

Method of Sighting
Sighting surveys were conducted from the upper wheel deck, from which theobservers' eye height was 8.5 to 9 m above the sea level. A small cabin on theport side limited observations somewhat in the area from 45° to 90°. Sighting
surveys were conducted continuously from sunrise to sunset when visibility was
greater than 50 m and Beaufort wind scale was less than 5 or 6.
The observation range was 180° in the direction of travel (90° port and starboard). Any changes of weather, visibility and wind force were recorded, regardless of sighting of marine mammals. The surface water temperature was recorded
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE

109

Fig. 1. Cruise track of the Hoyomaru No. 12 (solid lines), noon position (closed
circle, JST), surface water temperature, and number of Dall's porpoises sighted andcaught during the cruise. The dotted lines indicate area where the sighting survey
was not conducted. There was no chase or catch of porpoise on 16 September.

every hour from the auto-thermorecorder placed on the ship's hull. A differenceof about 0.5°C was observed between the temperature of the thermorecorder andsampled surface water. Ship's position calculated by the navigation system was
imprecise during the interval between satellite overflights (about 1 to 4 hours) if
ship's speed was frequently changed for chase, catch and retrieval of Dall's porpoise. Hand held binoculars (7 X or 10 X ) were used.
Two to eight observers conducted surveys, including ship's crew, up to threemarine mammal biologists (T. Kasuya, Y. Fujise and C. Thomson), and one or
two harpooners (T. Fukushi, experienced in Dall's porpoise hunting and Mr Y.
Ishida experienced in sightings on a whale catcher boat). The senior author observed all cetacean schools.
Each time marine mammals were sighted, time (Japan Standard Time),
direction, radial distance, sighting cue, species, number, and estimates of growthstages were recorded. Ship's position was calculated later. The radial distanceto the animals was estimated visually when the school was close, or if the distance
was large, was calculated based on the ship's speed (10 knots, or 300 m per min.)and the time interval between sighting and approach to the school.

3.

Capture and Shipboard Processing of Porpoise

With rare exceptions, whenever Dall's porpoise was sighted, the ship was
directed towards the school. When the porpoises rode the bow wave, the ship's
speed was decreased to 5 knots or less and the harpooners used hand-held harpoons
to catch them. Some porposes were caught while they rode the ship's side wave.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

110

KASUYA AND JONES

In most cases, harpoons equipped with an electric shocker (50 volt, 60 Hz) wereused and death occurred within 2 to 3 minutes. When Dall's porpoise did not
ride the ship's wave, they were followed as long as possible to record behavioral
observations and to approach closely enough for harpooning. The catch consisted
of80 Dall's porpoises (dalli-type 72; truei-type 8), 3 Lagenorhynchus obliquidens, 3 Lissodelphis borealis, 2 Delphinus de/phis and 2 Stene/la coeruleoalba.
Body weight (to nearest 1 kg), body length (to nearest 1 cm) and externalmeasurements of most porpoises were obtained on ship. However the bodylength of 6 Dall's porpoises were calculated from the body weight. Reproductive
status of females was determined and teeth and gonads were collected from all individuals. The teeth were taken from the lower jaw or from both upper andlower jaws and fixed with 10% formalin or 70% ethanol solution. The left testis
with the epididymis was collected, cut transversely at the midlength for better fixation, and fixed in 10% formalin solution. For the mammary glands, color wasrecorded, thickness was measured at the center, and a sample for histological examination was collected and fixed in formalin. The width of the left and rightuterine horns was measured, and a small piece of endometrium was fixed in formalin with the ovaries. If an ovary had a corpus luteum and the uterus was small,
10% formalin solution was injected into both uterine horns after measurement, andthe whole uteri and ovaries were placed in formalin. Some skeletons, stomachs,
and various tissue samples were also collected for other researchers.

4.

Laboratory Procedures
After weighing the testis, smears were taken from all testis and epididymis
samples and stained in toluidine blue. Presence and relative quantity of spermatozoa were recorded. The sperm density in the smear was recorded in 5 categories(from none to abundant). Histological sections were made from testis tissue atthe center of aforementioned cut surface and epididymis in the same area andstained with haematoxylin and eosin for permanent preparations. Sexual maturity
for each male was determined from these preparations, mainly based upon thetestis tissue.
The weight of the left and right ovary was measured separately, and the number of corpora albicantia (CA) and corpora lutea (CL) were counted. In two females, a fetus (4.4 cm and 13.l cm) was observed on board the ship. For the otherseven females, although a CL was present in the ovary, pregnancy was not apparent. These uteri were opened in the laboratory, washed in water, and both
the wash and uteri were examined for small embryos.
Tooth preparations for age determination were made using two methods.
The method used by Kasuya (1978), was used for all females, and males of a bodylength up to 180 cm (aged by TK and LJ). In the remaining samples, the whole
tooth was decalcified in 5% formic acid for two to three days, embedded in paraffin and sectioned in the usual method (15 µm), and stained in haematoxylin (agedby TK only). For age determination, the number of haematoxylin stainable layers
in the cementum was counted. Conversion of these values into ages was done acSci, Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE

111

cording to Kasuya (1978), assuming deposition of haematoxylin stainable layers
occurs from fall to winter. Therefore, for the samples collected in the present
cruise, the number of stainable layers coincides with the approximate age of the
porpoise.
RESULTS

Segregation between Dall's Porpoise and Other Delphinids
During the cruise, Dall's porpoises were sighted during the period from 20
August to 18 September, with the exception of 6 days (17-19 August, 1, 6 and 19
September) when the ship cruised south of 41°N (Table 1 and Fig. 1). Therefore
it is concluded that the southern limit of this species in the northwestern North
Pacific Ocean during this season is about 41°N.
To determine the distribution of the species, it is desirable to analyse thesegregation between Dall's porpoise and other delphinids. As shown in Tables 1,
2 and 3, nine delphinid species were observed during the cruise. There was a correlation between surface water temperature and the occurrence of certain species.
Sightings of Dall's porpoise were limited to surface water temperatures below 20°0.
Warm water delphinids, such as Delphinus, Tursiops, Globicephala, and Stenella,
were sighted in waters above 17°0. Dall's porpoise accounted for about half ofall the schools sighted in surface water temperatures of 18°0 to 19°0, and since
the size of Dall's porpoise schools was small, we conclude this species will bedominant in August-September in the waters below 18°0. This temperature isslightly higher than the figure obtained by Kasuya (1982) but agrees with dataobtained by Ohsumi and Takaki (unpublished manuscript) for this season. The
lower limit of the water temperature for Dall's porpoise was not determined in thepresent study. They have been sighted in this area in temperatures to 2°0 (NMML
unpublished data).
Two boreal species, Lissodelphis and Lagenorhynchus, were sighted at surface
water temperatures between 12°0 and 19°0. Near the southern limit of the rangeof the Dall's porpoise, the distribution of these three species overlaps. Although
Phocoena phocoena also occur in this temperature range, they inhabit coastal waters,
and were only sighted on the continental shelf off the east coast of Hokkaido.
1.

2.

Segregation between the Two Colour Types
The two major colour types, dalli-type and truei-type, are not currently distinguishable by characteristics other than pigmentation. Geographically dalli-type
lives in the northern North Pacific and waters adjacent to it, and the truei-type lives
off the Pacific coast of the southern Kuril Islands and northern Japan. Although
it is clear that there are at least two stocks of Dall's porpoise in the northwestern
North Pacific (Kasuya, 1978), little is known about the taxonomic relationship of
the two color types or about the variation in color pattern in these stocks.
On the northbound offshore route, Dall's porpoise first appeared at 43°20'N
and 155°54'E, and were the truei-type. On the return, the truei-type appeared at
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

112

KASUYA AND JONESTABLE 1. SIGHTINGS OF DALL'S PORPOISE DURING THE
CRUISE ABOARD HO'YOMARU NO. 12

Date

Noon position

Trueitype

Dallitype

Aug. 17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Sept. 01
02
03
04
05
06
07
08
09
10

Lv. Kesennuma
39°27'N, 146°30'E
40°36'N, 151°31 1E
43°32 1N, 155°54'E
45°17 1N, 158°2l'E
45°59'N, !59°15'E
46°49'N, 160°00'E
48°37'N, rti2°22'E
49°4l'N, 163°58'E
49°461N, 166°55'E
49°13'N, 169°221E
48°381N, l 72°4l'E
46°58'N, 174°02 1E
44°55'N, 173°47'E
43°08'N, l 73°3l'E
40059'N, !72°01'E
43°09 1N, 169°37 1 E
44°05'N, 167°44'E
45°10'N, 165°13'E
42°20'N, 167°48'E
40°00 1N, !68°49'E
42°48'N, 165°23'E
43°581N, 163°37 1 E
44°14'N, 161°4l'E
44°50'N, 161°27 1 E
43°52'N, 161°30'E
41°29'N, 163°54'E
41°3l'N, 163°50'E
42°50'N, 158°52'E
42°56'N, 155°03'E
43°021N, 149°5l'E
42°461 N, 144°521 E
42°l41 N, 143°53'E
Ar. Kesennuma

0
0
0
4
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0

0
0
0
0
27
23
43
24
10
12
15
22
15
13
7
0
17
31
7

11
12
13
14
15
!62 >
17
18
19
Total

Type Motherunicalf
dentified pairs

0
0
0
0
0
0
0
0
0
0
0
33
I
41
0
8
0
28
12
3
12
4
34
20
II
8
3
0
0
0
0
2
0
7
I
2
0
0
0
0
0
0
4
0
0
2s>
0
0
23
2
0
59
25
0
No sighting surveys conducted
0
2
2
0
0
0
2
0
0
7
5
0
0
0
0
5
17
12
15
16
2
31
0
13
0
0
0
0
0
380
275
42
55

Rode
ship'sll
wave,.

%

50
82
32
87
63
5
4
7
0
0
6
71
100
45
22
100
100
100
85
76
50
0
58
22
63
30

Surfacetemperature(oC)4l20.8-23.4
20.9-22.6
20.2-23.7
18.5-19.6
17 .5-18. 7
16.6-17.8
12.5-16.6
11.8-12.5
9.8-10.2
9.1- 9.5
9.2- 9.9
9.5-10.0
9.7-11.1
11.6-12.8
12.1-16. 7
16.0-18.0
13.7-17.6
13.1-14.0
13.7-14.1
15.0-18.9
19.4-19.8
15.8-18.4
14.4-15.4
14.6-17.1
14.8-16.8
14.1-16.8
16.7-18.2
18.0-20.6
14.4-18.3
16.0-17.6
13.8-17.6
14.1-18.0
15.0-18.5
19.1-20.1

46

Porpoise came to the ship's wave, either at bow or side.
2J No porpoises were chased or caught by the vessel.
sJ Porpoise were sighted on bow, but sighting survey was not conducted due to rough weather.
4J Temperature ranges during sighting surveys, or during the day if surveys were not conducted.
1laround 43°N and 151°E, and the proportion increased as the ship moved toward
the southwest, reaching about 50% on the edge of the continental shelf off Oehlishizaki to Daikokujima, Hokkaido (42°46'N and 144°52'E). Slightly south of thisarea, all the Dall's porpoises sighted were of the truei-type (18 September).
Surface water temperature at the boundary of the two types was about l8°C
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE
TABLE 2.

Date

113

OTHER DELPHINOID SPECIES SIGHTED DURING THE
HO'YOMARU NO. 12 CRUISE, 1982

Position

Delphinus delphis
39°-40°N, 146°-l48°E
8.18
8.19
40°-41°N, 150°-l52°E
9.01
40°18'N, l 72°50'E
Stenella coeruleoalba
8.19
39°-4l°N, 150°151°E
Orcinus area
8.20
43°45'N, 156°10'E
8.21
44°58'N, 157°53'E
8.25
49°50'N, 164°35'E
44°58'N, 161°18'E
9.10
9.18
42°42'N, 145°07'E
Lagenorhynchus obliquidens
8.21
45°27'N, 158°43'E
44°43'N, l 73°43 1 E
8.30
9.03
43°-45°N, 167°-168°E
44°-45°N, 166°-167°E
9.04
43°44°N, 163°-164°E
9.08
42°43°N, 159°-l60°E
9.14
9.15
43°08'N, 155°58'E
42°02'N, 143°22'E
9.18
Lissodelphis borealis
8.30
44°43'N, l 73°47'E
9.03
43°45'N, 167°-l68°E
9.08
43°-44°N, 163°-l64°E
Phocoena phocoena
9.17
42°-43°N, 144°-145°E
9.18
41°-42°N, 143°-l44°E
T ursiops truncatus
41°36'N, 143°16'E
9.18
39°l 7'N, 142°081 E
9.19
Globicephala macrorhynchus
41°36'N, 143°16'E
9.18
9.19
39°17'N, 142°08'E
Unidentified

No.
No.
indischools viduals

Surfacewatertemperature(°C)

Remarks

2
4

143
245
25

22.2-22.4
20. 7-23.4
17.5

Two schools with Stenella

4160

23.0-23.7

Two schools with Delphinus

35
35
4

18.5
18. 7
9.8
15. l
18.2

15

500
1565
39
450
8
30
50

17.5
12.3
13.5-13.9
13.7
14.6-15.4
16.5
16.0
18.3

With P. dalliWith Lissodelphis
Three schools with Lissodelphis

150
1210
450

12.3
13.5-13.9
14.6-15.4

Found with Lagenorhynchus

3
2
6
3

12
13

16.5
18.5

40
15

18.3
19.6

Found with Globicephala

50
25
6+

18.3
19.6

Found with Tursiops

1
4
4
2
2

1
4

With Lissodelphis

"
"

"
"

in the offshore waters and 14°0-15°0 off Hokkaido. In the area east of 160°E,
however, only the dalli-type was observed even in waters of 14°0-18°0. The proportion of the truei-type sighted became lower in the eastern area, regardless ofwater temperature. This indicates that surface water temperature was not thedetermining factor for habitat selection of the two color types.
Mixed schools in which both the dalli-type and truei-type were present weresighted on five occasions (one school each on 21 August, and 9, 10, 16 and 17 September). Mixed schools were sighted each day when both color types appeared. During
these five days 38 schools were sighted in which all identified individuals were dalliSci. Rep. Whales Res. Inst.,
No. 35, 1984

114

KASUYA AND JONESTABLE 3. NUMBER OF SCHOOLS OF DELPHINOID SPECIES OBSERVEDAT SURFACE WATER TEMPERATURES FROM 9°-24°C DURING
THE H01'0MARU NO. 12 CRUISE, 17 AUG. TO 19 SEPT. 1982
Surface water temperature (°C)

o;
°'I
°'

Species

Plwcoenoides:

dalli-type
truei-type
unidentified
Lissodelphis borealis
Lagenorhynchus obliquidens
Orcinus area
Phocoena plwcoena
Delphinus delphis
Tursiops truncatus
Globicephala macrorhynchus
Stenella coeruleoalba
Total

19
26

o;

o;

o;

o;

N

c<'J

I

I
c<'J

-- -- - -0
0

I

I

N

6

3

8

27

8

2

3

10
3
8

°'

0:

:!I
:!

~

10
3
10

7

I

~

8

"'

--

o;

<.o

......

I<.o

I......

16
9
16

12
2
6

°'
co

I

~

o; o;
0
N

8I
8

0
N

I

0:

o;

0:

N

N
N

N

N
N

c<'J
N

2

2

2

4
6

I

I

c<'J
N
I

8
2

3
3
3

6

2
45

14

5

13

48

25

18

50

22

20

3

TABLE 4. EFFECT OF WEATHER CONDITIONS ON SIGHTINGOF DALL'S PORPOISE 20 AUG. TO 18 SEPT., 1982 AND
CORRECTION FACTOR FOR WEATHER
Beaufort scale

2
3
4
5
6
Total

Sighting Effort(hours)No. porpoisesightedNo./sighting
hour

Effortcorrection factor

16.25
112.90
87.94
50.64
15.57
2.l:i8285.98

88
279
155
152
20
4
705

5.41
2.47
I. 76
3.00
1.28
1.49
2.46

1.252
I .OOO
0.798
0.637
0.508
0.406

type, and four schools were all truei-type. The number of schools in which bothtypes were present accounted for about 11 % of the total number of identified
schools. On 16 and 17 September, when the numbers of individuals of the two
types were about equal (16: 17), the number of mixed schools was two out of nineschools. This is not higher than the frequency of mixed schools of other dolphin
species observed in the cruise. In other words, we sighted a total of 27 schools of
Lagenorhynchus, Lissodelphis, Delphinus, Stenella, Tursiops, and Globicephala, out of which
mixed schools were sighted on 10 occasions (37%). Of the five mixed schools of
Dall's porpoise we encountered, composition was recorded for four. The proportions of dalli-type to truei-type to unidentified type for each school were 1: I: 0,
3: I: 0, 1: I: 0, and 3: 1: 0.
As shown in Table 1, the number of truei-type porpoises was only seven individuals out of a total of 371 Dall's porpoises (2%) sighted and identified during
the 27 days from 20 August to 15 September. In the following analyses, we reSci. Rep. Whales Res. Inst.,
No. 35, 1984

115

BEHAVIOUR OF DALL'S PORPOISE

garded all the unidentified Dall's porpoises sighted in the period as the dalli-type.

Geographical Difference in Dall' s Porpoise Density
As described earlier, Dall's porpoises were sighted mostly in surface watertemperatures of 18°C or below, with only a few sightings between 18°C and 19°C.
Within the temperature range, the number of individuals sighted daily varied from
5 to 85. There was a tendency that more were sighted in the western and northernparts of the ,research area and fewer in the south western part (Fig. 1). Such an
apparent geographical difference in sightings may occur if there is (1) a geographical difference in porpoise density, (2) a difference in sightability due to geographical differences in porpoise behavior, or (3) a geographical difference insighting rate due to differences in weather conditions such as wind force, winddirection and visibility. The second factor is analyzed below. We attempted tocorrect for weather conditions. We consider that difference in visibility was nota key factor since it changed often during daily sighting hours. Wind direction
affected sightings in that, even with the same wind force, sighting was easier ina tail wind than in a head wind. However, this factor was also ignored since
there were no wind direction data adequate for use in the analysis.
3.

6
i....
.s::. 5

Ul

(!)

•

4

Ul

·5 3
0..
i....
0
0..

2

0

z

2

3

4

5

6

Beaufort scaleFig. 2. The relationship between the number of Dall's porpoise sighted per sighting hour (y) and Beaufort wind force (x) during cruise of Hoyomaru No. 12. The
y-axis is in a logarithmic scale. The solid line is the least squares regression, In y=
In 4.98-2.253x, r=0.8.

Table 4 shows the time of initial sighting and number of sighted Dall's porpoises for each Beaufort wind scale. The numbers in this table are limited tothose observed during sighting surveys, and, therefore, do not correspond to values
in Table 1. Beaufort wind scale 2 was the most frequent, accounting for 39% of
the total sighting hours, and 40% of Dall's porpoise sightings. The number ofsighted individuals per survey hour decreased exponentially as the wind force increased (Fig. 2). The least squares regression between the number of sightd Dall's
porpoises per hour (y) and the Beaufort wind scale (x) is:ln y = -2.253x+ln 4.98, r = 0.8
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

116

KASUYA AND JONES

Fig. 3. Number of Dall's porpoise sighted per sighting hour with the correction forwind force, during cruise of Hoyomaru No. 12 (17 August-19 September, 1982).
The closed circles are noon positions (JST). The solid lines are the ship's trackand dotted lines are tracks on which there was no sighting effort.

In this equation the number of sighted individuals does not become zero even if
the wind force increases. This agrees with our observations of porpoise approaching the vessel even in rough weather. The value of Yx~n/Yx~ 2 was calculatedusing the above equation, and used as the effort correction factor for wind scale n(Table 4 ). In other words, sighting effort is standardized to that in the state of
Beaufort wind scale 2, which was the most frequent during the cruise.
Fig. 3 shows the density of Dall's porpoise per hour of sighting, after correction for the wind force. The trend in the density distribution discussed above remains unchanged after this wind force correction. The density is highest in acomparatively narrow area centering at 45°N and 160°E. During the cruise there
was an intrusion of a warm water mass with surface temperatures of 14°C to 16°C
in this area (Japan Meteorological Agency, 1982) and this may be related to theconcentration of Dall's porpoise in the area. Presumably there was a shift ofthe high density area of 22-23 August to the area of high sightings on 9 September(Fig. 3 ). This is supported by the meteorological data. The concentration ofdelphinids in areas of particular oceanographic conditions is also documented forStenella coeruleoalba (Miyazaki, Kasuya and Nishiwaki, 1974) and baleen whales(Gaskin, 1982).
The next highest density of Dall's porpoise was found between 48°N and 50°N
(Fig. 3). The surface water temperature was about l0°C, and the same oceanographic conditions extended over a wide area, including further north. Therefore,
this density may continue further north. Also, as discussed in the next section,sightability of Dall's porpoise in this area may have been less than in the south,
and therefore density in the north may have been higher than observed. Dall's
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE

117

TABLE 5. DIURNAL CHANGE OF SHIP'S WAVE RIDING BEHAVIOROF DALL'S PORPOISE OBSERVED DURING THE HOYOMARU NO. 12 CRUISE 1982

Dalli-type (20 Aug.-15 Sept.)
Time Period

NumbersightedNumber that rodewave(%)

NumbersightedNumber that rodewave(%)

207
221
166

69 (33.3)
125 (56.5)
55 (33.1)

55
53

18 (32. 7)
20 (37. 7)
2 (100.0)

Morningll
Day time 2 l
EveningsJ
1l

Truei-type (16-18 Sept)

Before 1000 hr (local time);

2>

From 1000 hr to 1400 hr;

2sJ After 1400 hr.

porpoise density off the east coast of Hokkaido was also high (Fig. 3 ). To summarize, Dall's porpoise density was high in the western and northern parts of thestudy area.

Geographical Difference in the Wave Riding Behavior
Dall's porpoises ride waves created by vessels. They usually ride the bow
wave, but will also ride side or stern waves. In most cases they alternately ridethese various waves once they have approached a ship. During the cruise, when
they did not approach the ship, they were chased to attempt to get them to ride
the ship's waves in order to harpoon them, and whether they rode the ship's waves
was recorded.
Table 5 shows the relationship between time of day and number of Dall's
porpoises that rode the ship's wave. In the offshore waters (20 August to 15 September) where the dalli-type was predominant, wave riding was about twice as
frequent during mid day as in the morning and late afternoon (Chi-square test, p<0.001 ). This may be related to their habit offeeding during the night time (Morejohn, 1979).
Among 202 Dall's porpoises sighted from 20 to 24 August off the easternboundary of USSR FCZ, 136 (67%) porpoises rode the ship's wave. On 24
August, 63% of the sighted individuals rode the wave, but the catch was low. Thisis probably attributable to the unfavorable weather conditions.
From 25 to 29 August, in the area off the southern boundary of US FCZ,
where the surface water temperature was around 11 °C, only six individuals (3%) of
187 Dall's porpoises sighted rode the ship's wave. In addition, 25 out of 56 schoolssighted in this area were not resighted, even though we attempted to approachthem after sighting the schools. The remaining 31 schools were chased for various
lengths of time, from two to 48 minutes (average 12 minutes). When chased inthis area, Dall's porpoise escaped by swimming faster than the ship's speed andthen rolled slowly after gaining a distance of 300 to 500 m. When the ship approached again, they resumed running, and repeated the behavior sequence. The
ship could not approach within 50 m to 100 m. Except for three schools, the Dall's
porpoise in this area eventually escaped by swimming at high speed.
The period from 31 August to 15 September was spent mainly south of the4.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

118

KASUYA AND JONESTABLE 6. RELATIONSHIP BETWEEN SURFACE WATER TEMPERATURE
AND PROPORTION OF DALL'S PORPOISE THAT RODE
SHIP'S WAVE, 20 AUG.-18 SEPT., 1982
Water
temperature(oC)
9- 9.910-10.9
11-11.9
12-12.9
13-13.9
14-14.9
15-15.9
16-16.9
17-17.9
18-18.9
19-19.9
Total

Dalli-type (20 Aug.-15 Sept.)

Truei-type (16-18) Sept.

----··~--·-----

NumbersightedNumber that rodewave(%)

132
39
12
36
119
51
55
76
45
25
4
594

3 (2.3)1 (2.6)5 (41.6)
16 (44.4)
73 (61. 3)
46 (90.2)
18 (32. 7)
42 (55.3)
25 (55. 6)
18 (72. 0)
2 (50.0)249 (41.9)

NumbersightedNumber that rodewave(%)

0
22
0
71
10
7

0
4 (18.2)
024 (33.8)
6 (60.0)
6 (85. 7)110

40 (36.4)

l 4°C surface isotherm. In this area, the number of Dall's porpoises that rode theship's wave increased and 146 out of209 Dall's porpoises (70%) rode the bow wave.
This proportion was about the same as that in the period of 21 to 24 August.
Table 6 shows the relationship between the proportion of the Dall's porpoisethat rode the ships wave and surface water temperature. In the offshore area
where the dalli-type was predominant (20 August to 15 September), less than 3%of the Dall's porpoises sighted north of the 11 °C isotherm rode the wave. As thetemperature increased above 13°C, the percentage increased to exceed 60%. The
difference in behaviour in the two temperature ranges was conspicuous. Off theeast coast of Hokkaido (16-17 September), where the truei-type was abundant, thedata are limited and the situation is not completely clear. However, in general,the number of individuals that rode the bow or side wave increased as the surface
water temperature rose. In this coastal area, the number of Dall's porpoises thatrode the wave exceeded 60%, in surface water temperatures greater than l 7°C.
The difference in temperatures between two areas reflects the distribution patternof the truei-type.
We conclude there is a marked difference in the behavioral response to ships
between dalli-type porpoise that live north of 11 °C surface isotherm and those thatlive south in the Subarctic Convergence at temperatures of 11 °C to 19°C.
5.

Segregation of Mother-Calf Pairs
Although it is difficult to estimate body lengths of Dall's porpoise in the water,
it is not difficult to identify mother-calf pairs if observed at a close distance (lessthan 100 m). In the present study we identified mother-calf pairs using thedifference in body length or splash size of two individuals swimming together atclose distance (Table l and Fig. 4 ).
Out of 41 mother-calf pairs sighted in the offshore area where dalli-type
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUROFDALLSPORPOISE

9
1
1

'
3
5
。
,48
t1982
s
ugu
,28A
18
.1
o
lN
o
o
h
c
S
l(
o
o
h
c
es
s
i
o
p
r
o
sp
'
l
l
a
. D
.4
g
i
F
s
r
i
a
fp
al
c
‑
r
e
h
t
f2mo
do
e
t
s
i
s
n
o
pc
u
o
r
sg
i
h
,t
)
T
S
J
t0352(
ya
l
l
a
i
t
ni
di
e
t
h
g
i
ns
lε
'
¥
¥
e
h
dt
e
n
i
o
rj
i
a
fp
al
c
‑
r
e
h
ermot
h
t
o
n
,a
t0403)
a
e(
s
a
h
ec
h
gt
n
i
r
u
td
u
,b
s
t
l
du
d2a
n
a
.
c
p
y
t
‑
i
l
/
a
ed
h
ft
eo
r
e
. Al8w
l
e
s
s
e
hev
mt
o
r
df
e
p
a
y回 c
e
h
,t
t0405
.A
p
u
o
r
g
'
f
l
a
:
.
:C
:
.
,C
r
leMothe
b
a
b
o
r
:p
I
v
'
,i
t
l
u
d
:A
A

、

.
t
o30Augus
eperiod仕om26t
h
nt
edi
ht
g
i
s(86%)weres
dominant,36pair
waspre) outofsr
20 pais(
vidualt. Forty indiynotable day was 28 Augus
l
r
a
l
u
c
i
t
r
a
Ap
‑
. Through
s
r
fpai
al
c
‑
s mother
da
ie
if
t
n
e
d
duals encountered were i
vi
i
d
n
e56 i
h
t
s
i
s
i
h
T
.
e
v
a
w
s
p
i
h
s
e
h
t
e
d
o
r
r
i
a
p
f
l
a
c
‑
r
e
h
t
mo
, no
d
o
i
r
e
ep
is
u
recr
i
outtheentnhert
he nornt
ei
rofporpoisog behavinidie infrequent wave rhrtoason fe
oner
nce
ie explanation,st
he comples not tisih,t
. Howevero 30 August)
5t
2
ea (
ar
n・
87i
tof1
)ou
s
r
i
a
6p
3
s(
vidual
2indi
y7
ronl
o
saccountedf
riafp
motherand cal
eadditional
er
巴、v
her
ft
. Even i
d
o
i
eper
is
u
ecr
h
nt
di
te
h
g
i
es
twer
a
h
st
dividual
s
ual
d
i
v
i
d
n
e wereobviously many i
r
e
h
,t
d
e
d
ecor
enotr
hatwer
st
r
i
a
lfp
a
c
‑
mother
s.
e
v
al
・c
s
er
han mothrttheoon thenorthern area from 25 t
ghtedi
i
ss
chool
es
s
i
o
s porpAmongtheDal'
e 29
s
he
. Among t
e
s
a
h
ec
h
yobserved during telsoswereclchool
30August, 29s
d
e
t
s
i
s
n
o
ec
s
he
enoft
v
e
,ands
r
i
a
fp
cal
‑
tonemothersaeshad atl
3school
,1
s
chool
s
:
olows
sf
)a
s
randcalfpair(ymothe
ofonl
ls
o
o
ch
r: 2s
i
a
fp
lmother‑cal
ls
o
o
ch
: 2s
s
r
i
a
fp
l
a
c
3mother‑
s
chool
: 2s
s
r
i
a
fp
l
a
c
her‑
4 mot
・
chool
s: ls
fpair
l
a
rc
e
.
h
t
o
7m
e
e
hr
oupsofteparategrs巴d oftwos
choolwas compo
ts
s
a
hel
ghted, titssVVhen日rour mother
d「
,
;
sa
r
i
a
fp
rcal
the
mo
proached.
:
f
do
e
t
s
i
s
n
o
r )c
fpai
l
a
hmoth巴rc
swit
chool
xs
i
inings
The1ema
s
chool
: 3s
t
randladul
Imother‑calfpai
chool
: 1s
t
sand Iadul
r
i
a
fp
l
a
‑c
r
the
O
l
τ
2l
司 −

司

.,
l
s
1
1
.l
s
sRe
e
.Whal
p
i.Re
Sc
1
‑
8
9
,1
5
No.3

0
2
1

UYAANDJONES
KAS

l
o
o
h
c
S
e(
z
i
amcs
es
h
tt
u
o
b
fa
s白 o
i
o
p
r
o
ep
p
y
t
‑
i
/
/
a
f4d
go
n
i
t
s
i
s
n
o
lc
o
o
h
c
. As
.5
g
i
F
2
4
.1
o
lN
o
o
h
c
dS
ne
i
o
lj
o
o
h
c
ss
i
h
.T
)
6E
5
°
， げ3
N
'
5
5
。
5
4
2,
8
9
t1
s
u
g
0Au
,3
3
4
.1
o
J
)
o
0t
3
7
凸om0
s（
e
t
u
n
i
6m
r4
e
t
f
)a
l
um+Smaarge+Medi
口： L
s
i
o
p
r
o
3dalli‑typep
(
t
h
g
u
a
sc
a
dw
n
ea
v
a
oww
heb
det
o
r,Ir
u
o
ef
h
. Oft
2
4
l1
o
o
h
c
gS
n
i
w
o
l
l
o
ff
8)o
1
8
0
r
to
n
a
n
g
e
r
tp
o
sn
a
dw
n
,a
d
l
so
ar
e
Oy
,J
e
l
a
m
e
gf
n
o
4cml
7
sa1
a
tw
. I
)
o.31
N
(
.
s
e
i
r
a
v
eo
h
nt
ai
i
nt
a
c
i
b
l
aa
r
o
p
ot
d2c
n
uma
c
t
u
sl
u
p
r
o
dIc
a
th
u
gb
n
i
t
a
t
ac
l
chool
,1adultandUnknown: 1s
s
fpair
‑cal
2mother
l
o
cho
: 1s
s
h2adultt
3mother‑calfpairswi
tandone medium
e wasoneadul
r
e
h
,t
s
eindividualerhoupsoft
Inoneofthegr. Thiscould have2)4f(SchoolNo. 1
rcal
malle
d by a s
we
o
l
l
o
lf
ividua
d
n
di
ze
i
s
.
r
a
e
foftheprecedingy
d byacalefpairaccompani‑calherbeenamotr ofuo. In f
s
r
i
a
p
f
l
a
c
‑
r
e
h
t
mo
o
n
e
r
we
e
r
e
h
t
,
s
l
o
o
h
c
s
6
1
g
n
i
n
i
a
m
e
er
In th
:
s
a
d
e
t
a
m
i
t
s
e
s
a
w
s
l
a
u
d
i
v
i
d
n
i
e
h
t
f
o
e
g
a
t
hegrowths
,t
s
chool
es
s
e
h
t
s
chool
: 2s
ls
a
u
d
i
v
i
d
n
li
mal
3s
chool
: 1s
s
l
a
u
d
ivi
d
n
mali
5s
)
ig.5
F
chool(
s: 1s
l
a
u
d
i
v
i
d
n
argei
4l
scanbedrawnfromtheabovedata:
ence
r
e
f
n
ngi
i
w
o
l
l
o
Thef
.
l
o
o
ch
ormas
of
et
) Severalmother‑calfpairsmayaggregat
1
(
.
s
t
otheradul
e
r
o
m
r
o
e
n
o
h
t
i
w
l
o
o
h
c
s
a
m
r
o
f
y
a
m
)
s
(
r
i
a
p
f
l
a
c
‑
r
e
h
t
o
M
)
2
(
.
s
l
o
o
h
c
s
m
r
o
f
y
ma
m
山
即
im
r
o
s
e
v
) Weanedcal
3
(
s
chool
quently,othersresappearf
r
i
a
fp
al
c
‑
ther
emo
r
e
awh
e
4) Inthenorthernar
(
nt.
e
s
opre
s
l
area
lwith mother仁eta1%) were not associ4s(ividualdn, 45 ishoolche 29 sntIhem
ytwoofthipswave. Sinceonly rodetheselra
ividualsr
d
n
e45i
s
. The
rs
i
a
p
0years,age3and 1
s
e
i
r
a
v
ntheo
hCAandCL itswieingfemal
t
s
e
2r
ught(
eca
wer
,ageandreproduc‑
x
e
rs
i
e
h
ectinformationontrisnotenoughd
ei
er
,th
)
y
l
e
v
i
t
c
pe
s
e
r
.,
t
s
n
s.I
sRe
e
l
a
h
.W
p
Re
i.
c
S
,1984
No.35

BEHAVIOUR OF DALL'S PORPOISE

121

tive status. However, it is likely that adult males were also with these oestrus
females (see School structure). In this northern area, the proportion of mother-calfpairs out of the total number of individuals sighted per day fluctuated as follows
during the interval from 25 to 30 August: 0%, 25%, 30%, 71 %, 72% and 13%(Table 1). Therefore, among the areas studied in this cruise, mother-calf pairs
were highest north of 46 °N and east of 165 °E (Table 1).

School Structure
In the offshore area where the dalli-type was predominant, schools were composed of one to 14 individuals (Table 7). The mode was two individuals, and theaverage was about 3.5 to 3.8 individuals. This is similar to values for dalli-type
reported by Kasuya (1978) and Bouchet, Braham and Tsunoda (1983 ms). No
significant difference was detected between the school sizes in the northern andsouthern parts of the offshore area. Kasuya (1978) reported that the truei-type
formed larger schools than the dalli-type. The reason for the apparent larger
school size off Hokkaido (16 to 18 September) may be attributable to the presenceof truei-type. The sizes of 13 schools in which only truei-type were identified are
as follows: 20 August: 4; 16 September: 1 and 3; 17 September: 1, 6, and 7;
18 September: 2, 3, 4, 5, 6, 6 and 10.
Sighting information on school structure of Dall's porpoise distributed southof the 11 °C isotherm indicates that there were very small numbers of mother-calfpairs and small individuals that could be considered as weaned.
Information on the composition of Dall's porpoise schools was obtained frommultiple collections of animals from schools that came to the bow of the vessel.
6.

TABLE 7. SCHOOL SIZE FREQUENCY OF DALL'S PORPOISE FOR SURFACEWATER TEMPERATURES ABOVE AND BELOW J1°C. DATA FOR BOTH
COLOUR TYPES ARE POOLED. DATA FOR 16-18 SEPTEMBER
ARE PREDOMINANTLY TRUEI-TYPE
Above JJ°C

Below ll°C
School size
25-29 Aug.

J
2

3
4
5

6
7
8
9
JO
12
14
Total
Mean

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

8
14
5
9
2
5
3

20-24 Aug.
30 Aug.-J5 Sept.
4
29
25
2J

8
JO
4
1

J6-J8 Sept.
2
4
6
6
3
3

J
2
47
3.51

J06
3.77

27
4.07

122

KASUYA AND JONESOf the 70 dalli-type porpoise collected during this cruise, 54 (77%) were collectedwith one or more additional porpoise from the school. These animals were takenfrom at least 19 different schools. Interpretation of the results is complicated because more than one school was probably present during some collections.
Trends with respect to age, sex and reproductive status in the school composition were not clear. The composition of the samples from individual schools was:Composition
All immature males
Mature malesl\!Iature and immature males
Males and a female

No. of schools

4

2
7
6

School numbers
35, 48, 50, 218
219, 226
43, 49, 197, 206, 208,
209, 215
24, 39, 202, 204+205,
243

A mature female was present in four of the five schools containing both males
and females. In two of these (school 24 and 243) there was a mature male, andin one case the female was pregnant and lactating (fetal length 4.4 cm), and in theother the female had a corpus luteus and possible fetal membrane in the uterus.
In school 204+205 a resting female and a mature male were collected from a groupof six individuals. In school 39, four out of six individuals came to the bow, andan immature female, immature male and a mature male were collected. The final
mixed sex sample (school 202) was collected from a large group of animals thatprobably comprised several schools. Eleven individuals were taken, including a
resting female with a corpus luteum, immature and mature dalli-type males andan immature truei-type male. These data indicate that schools with mature
females without calves often contain mature males. Schools comprised of immature animals also exist.

7.

Ana{yses of the Catch
Eight truei-type Dall's porpoises were caught during the cruise, seven of whichwere males, and one, an immature female (Table 9).
Of the dalli-type, 72 individuals, including 12 females, were caught. Of thefemales, 2 mature females were caught in the northern area where the surface watertemperature was 11 °C or less (see School structure and Fig. 5 ). The body lengthsof the 12 females were 164 cm to 215 cm, and the ages from 2 to 10 years. Two
were sexually immature and 10 were mature. Of the 10 mature females, two werepregnant (fetus lengths of 1.4 cm and 13.1 cm) and one was pregnant and simultaneously lactating (fetus length: 4.4 cm). These three had total corpora countsof2, 12 and 5 respectively. Two females had a CL (and no CA) and a tissue (about
3 cm and 4 cm in the length) in the uterus that appeared to be embryonic membrane. The remaining five females had CL in various developmental stages in theovary, but no embryonic tissue was observed in the uterus. Their corpora numbers
were 1, 1, 3, 4 and 6 respectively. The seven mature females in which pregnancy
was not confirmed were not lactating. These findings add three interesting points
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE
TABLE 8.

BODY LENGTH FREQUENCIES AND SEXUAL MATURITY OF DALL'SPORPOISE CAUGHT IN THE HOYOMARU NO. 12 CRUISE, 1982

Dalli-type

Colour type
Sex
Body length(cm)
164-167
168-171
172-175
176-179180-183
184-187
188-191
192-195
196-199200-203204-207
208-211212-215
216-219
Total

123

Truei-type

Male
E
3
4
7
3
7

Female
M

L

Total

8
4
4
4

3
4
9
6
11
8
6
4
5

29

1
60

1
3
3

26

I

3

I : Sexually immature,2

E : Early maturing,

Male
Total

M

FemaleM

22

L : Late maturing,

2
2

2
2

2

10

12

6

M : Sexually mature

TABLE 9. AGE FREQUENCIES OF DALL'S PORPOISE CAUGHT IN THE
HOYOMARU NO. 12 CRUISE, AUGUST TO SEPTEMBER 1982

Dalli-type

Colour type
Male

Sex
E

Age (yr)
2
3
4
5
6
7
8
9
10
17
Total

Truei-type

L

9
6
6
3

26

I : Sexually immature,2

2

E : Early maturing,

Female

Male

M

Total

M

Total

2
5
5
6
3

11
11
12

2
3

2
4

25

55

8

10

Female

I

II

5
2

2

L : Late maturing,

M: Sexually mature

to our knowledge of adult female behavior. The first point is that while mothers
accompanied by calves do not ride the ship's wave (described previously), female
individuals that are not lactating (that is, they are probably not accompanied bya calf) do so. This is what Kasuya (1978) assumed with the truei-type. The second point is that most of these non-lactating mature females seem to be segregatedin the southern area where the water temperature is comparatively high. The
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

124

KASUYA AND JONES

third point is that the ovulation rate of non-lactating mature females is very high.
It is probable since the research was conducted in the mating season that most of
the females with CL in the ovaries were in a very early stage of pregnancy that
could not be confirmed visually. Therefore, the pregnancy rate of these nonlactating adult females in the sample may have been underestimated.
The body lengths of the 60 dalli-type males ranged from 164 cm to 219 cm,
and the ages from 2 to 17 years. As in the case of females, no male shorter than164 cm or younger than 2 years was caught. This indicates that the young
individuals are either (1) segregated in the northern area, or (2) are in the southernarea with surface water temperatures above 11°C, but do not approach ships. In
either case, since individuals below 2 years of age did not ride the ship's wave, they
could not be sampled. The same is true for the truei-type in the Japanese coastal
waters (Kasuya, 1978).
Male sexual maturity was determined from histological examination of thetestis. If no spermatozoa, spermatid or spermatocyte was observed in the testis
tissue (usually 0.5 X 0.5 cm taken from the center ), the indidividual was determined
to be " immature ". " Early maturing " stage indicates males in which the proportion of seminiferous tubules containing any one of these stages was between
0 and 50%; "late maturing" are those with these stages present in 50% to less
100% of the tubules. Individuals in which all tubules had any of these stages
present were determined to be " mature ". Even in the individuals which were
determined to be " mature " using this classification, some showed active spertogenesis and some did not. Also, some individuals did not have one or two ofthese spermatogenetic stages. This may indicate that the male mating peak is nottotally synchronized. This will be studied separately.
These maturity criteria were compared with the sperm density in the epididymal smears. The results indicate that two out of the 31 males that were determined to be " mature " did not have sperm in the epididymis, and in another 3
males the sperm density was " scanty" (1 sperm in several fields). The sperm
density of the other "mature" males was "common" (one to three sperm in one
field) or higher. Only three males of the 34 which were classified "immature"
had "scanty" sperm present and no sperm was observed in the epididymis of theothers. As shown in Fig. 6, the correlations between maturity and testis weightand between maturity and body length are reasonable. Therefore, we conclude
that these classifications of male sexual maturity are appropriate. Generally, thetestis weight of 40 gm could be used as the threshold between "immature" and" mature ".
As shown in Table 8, male dalli-type attain sexual maturity at body length
between 172 cm and 199 cm. The body length where half of the males are mature
is assumed to be somewhere in the range of 176 cm to 187 cm. The corresponding
body length of mature females is between 172 cm and 183 cm. These body lengths
are 10 to 15 cm smaller than the values for truei-type in the Japanese waters obtained
from the samples caught by the same method (Kasuya, 1978).
For male dalli-type, the ages of the youngest mature individual and oldest
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE
I

I

360--

I

125
I

-

0

320

Ol

c 280--

000.....(/) 240.....(l)..... 200......

-

0
0

0

0
0

0

0

(l)

0

0

0

0

160-

-

0
0

-

120-

0

0
0

-

d

0

0

40

0
tl 0

•

170

0

0

0

80

0

-

cf

t:.
••

•

180

190

•
200

210

220

Body length 1n cm
Fig. 6. Relationship between body lengths an.d left testis weights of Dall's porpoisecaught with hand harpoons during the cruise of Hoyomaru No. 12 (17 August19 September, 1982). Open circle without bar: Mature. Open circle with bar:
Late maturing. Closed circle with bar: Early maturing. Closed circle withoutbar: Immature.

immature individual are 2 years and 7 respectively. For females, although thesample is small, it is 3 years and 4 years respectively (Table 9). These values
agree with the corresponding figures obtained from the salmon gillnet fishery in1967 (Kasuya, 1978) and in 1978 to 1980 (Newby, 1982).
The proportion of mature males does not significantly change from 4 to 7
years of age. If the sample is not biased, one expects the proportion of matureindividuals to increase with age. Another interesting point is that the age freSci. Rep. Whales Res. Inst.,
No. 35, 1984

126

KASUY A AND JONES

quency does not change between 2 and 5 years, but abruptly drops at ages over 6
years. We interpret this to mean, as is the case for truei-type off the Japanese coast(Kasuya, 1978), that the proportion of individuals available for sampling by hand
harpoon increases as maturity approaches and decreases after individuals havereached maturity. Since the majority of the mother and calf pairs were distributedin the northern area, almost none of Dall's porpoises in that area rode the ship's
wave, and about 70% of the individuals in the southern area rode the ship's wave,
we conclude that wave riding behavior of Dall's porpoise is common in only certain
growth or reproductive stages (especially in females).
The data on the dalli-type obtained in the present study was biased towards
males (male 60: female 12). In the southern area, the proportion of individuals
that did not ride the ship's wave was 30% of the total number of Dall's porpoises
sighted. If all of them are assumed to be females, the sex ratio of Dall's porpoisein the area would be (12+72x0.3+0.7)/(12+72x0.3+0.7+60)=0.42. Even
with such an extreme assumption, it is difficult to explain the unbalanced sex ratioof the catch. One interpretation is that more males live in the southern area.
The fact that there are fewer females than males in all age groups (Table 9) may
indicate that sexual segregation is present in all age groups over 2 years.
DISCUSSION
Since 1978, a large number of samples and data have been collected from Dall's
porpoise killed incidentally by the Japanese salmon mothership gillnet fishery(Anon. 1981 ). The majority of these samples were collected annually in June andJuly, in the area between 46°N-58°N latitude and 168°-l 75°E longitude. There
are three major differences in the sampling between the present study and theprevious. In the present study, although there was some areal overlap (27-29
August), emphasis was placed on collections south of the mothership fishing area,in the Subarctic Convergence. In this study, samples were collected during themating season (August-October) rather than the parturition season (June-July).
The third difference is that samples were obtained using a hand-held harpoon as
animals rode the ship's wave rather than from gillnets as in the previous collections.
In the sample collected from the mothership fishery, body length frequency ischaracterized by the presence of some newbornes (about 100 cm) and juveniles(130-160 cm) which correspond to an age of about 1 gear are abundant (Kasuya,
1978; Newby, 1982). This corresponds to the presence of mother and calf pairs
and presumably weaned juveniles sighted in this study in August-September northof the Subarctic Convergence.
The age of individuals obtained in the Subarctic Convergence was 2 years orolder. This indicates that the bow wave riding behavior does not necessarily startat the time of weaning. Therefore, Kasuya's estimate (1978) of the suckling periodof the truei-type off the Japanese coast might have been an overestimation. In
the present study no estimation of the weaning period has been obtained.
The female ratio in all the Dall's porpoise caught by the salmon gillnet fishery
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

BEHAVIOUR OF DALL'S PORPOISE

127

was about 63%, and that in the adult individuals 76% (Anon., 1981). In thissample, twelve out of 72 Dall's porpoise (17%) were female and 23% of the mature
animals were female. This supports our conclusion that more males are distributedin the Subarctic Convergence and more females are distributed north of the Convergence. Dall's porpoise have also been collected in the western North Pacificnear Monterey Bay, California (36°48'N and 121°47'W) in the southern portion of
the species range from strandings and by hand-held harpoons (Loeb, 1972; Morejohn, 1979). Although the sample sizes are small, the proportion of females taken
by harpoon was 19% (4 out of 21 animals), similar to the percentage in the present
study. However, in stranded animals from the Montery Bay area, the sex ratio
was about 1: 1 (n=9) (Loeb, 1972). Data on maturity or age were not presented.
In the finless porpoise, possibly reflecting the age specific mortality rate, most of
the strandings were juveniles below 2 growth layers and adults over 8 layers (Kasuya
and Kureha, 1979). If this is true for Dall's porpoise, additional biological data
will be required for further analysis of the stranded individuals.
In the samples collected in the gillnets, 690 out of 752 mature females (92%)
were pregnant. This corresponds to the observation of large numbers of mothercalf pairs north of the Subarctic Convergence in August-September, after the peakof the parturition season. The high pregnancy rate in the sample collected during the parturition season CJ une-J uly) indicates an annual pregnancy for thisspecies. For this to be true, almost all of the adult females of this species would
have to ovulate within a month or so after parturition and enter the next gestation.
Therefore, the majority of adult females must be lactating and simultaneously inthe early stage of pregnancy in August-September. To clarify this point, we expected to obtain mother-calf pairs in this cruise, but it was not possible becauseof their behavior of avoiding the vessel. However, in this study, we are able toclarify these points: (1) some of the mature females are distributed in the Subarctic
Convergence, and all of these have recently ovulated since all had a CL present, andonly one was lactating; and (2) a few nonlactating mature females may occur
north of the Subarctic Convergence during this time of year. This indicates thatmany of them may become pregnant every year but some individuals do not, andmost of these are segregated in the Subarctic Convergence.
The present study clarified that the Dall's porpoise is geographically segregated by growth stage, sex and reproductive status and that their reaction to vessels
is not uniform. This suggests that the sighting rate of Dall's porpoise from ships
may vary by the areas and seasons. Care must be paid to this point when estimating the Dall's porpoise population by sighting.
ACKNOWLEDGEMENTS

In conducting the dolphin sightings and capturing and processing of Dall's porpoiseon the Hoyomaru No. 12, we were given the full cooperation of Mr Y. Ishida, Mr
T. Fukushi, Mr Y. Fujise, Ms C. Thomson, Captain T. Itoh and all the crew ofthe ship. Ms T. Shirai and Ms M. Oya prepared the histology slides and drawSci. Rep. Whales Res. Inst.,
No. 35, 1984

128

KASUYA AND JONES

ings, performed data analysis and typed the draft manuscript. M. Wood and B.
Lander also typed drafts of the manuscript. The Fisheries Agency of Japan and
Dr S. Odate and his colleagues of the Far Seas Fisheries Research Laboratory
arranged the cruise and provided us the opportunity of the study. We would liketo express our sincere appreciation to all for their kind and eager cooperation.
REFERENCES
ANON. 1981. Report on studies of the incidental take of marine mammals particularly Dall's porpoise,
Phocoenoides dalli, in the Japanese salmon fishery. Inter. North Pac. Fish. Commn. Doc. No. 2387, 70 pp.
BoucHET, G. C., H. W. BRAHAM, and L. M. TsuNODA, 1983 (ms). Investigation of Dall's porpoise (Phocoenoides dalli) response to a survey vessel: Preliminary assessment. Inter. Whal. Commn. SCf34/SM13, 7 pp.
JAPAN METEOROLOGICAL AGENCY 1982. The ten day marine report, Nos. 1291-1294.
GASKIN, D. E. 1982. Ecology of Whales and Dolphins. London and Exeter, New Hampshire. 459 pp.
KASUYA, T. 1978. The life history ofDall's porpoise with special reference to the stock off the Pacific coastof Japan. Sci. Rep. Whales Res. Inst., 30: 1-63.
KAsUYA, T. 1982. Preliminary report of the biology, catch and populations of Phocoenoides in the western
North Pacific. pp. 3-19. In: Mammals in the Seas, Vol. 4, FAO, Rome, 531 pp.
KASUYA, T., and K. KuREHA, 1979. The population of finless porpoise in the Inland Sea of Japan. Sci.
Rep. Whales Res. Inst., 31: 1-44.
LoEB, V.J. 1972. A study of the distribution and feeding habits of the Dall porpoise in Monterey Bay,
California. Ma, thesis, San Jose State University California. 62 pp.
MIYAZAKI, N., T. KAsUYA, and M. NrnmwAKI, 1974. Distribution and migration of two species of Stenellain the Pacific coast of Japan. Sci. Rep. Whales Res. Inst., 26: 227-243.
M1zuE, K. and K. YosHrnA, 1965. On the porpoise caught by the salmon gillnet in Bering Sea and theNorth Pacific Ocean. Bull. Fae. Fish. Nagasaki Univ., 19: 1-36. (in Japanese with English summary).
MoREJOHN, G. V. 1979. The natural history of Dall's porpoise in the North Pacific Ocean. in Winn.
H. E. and B. L. Oda (eds), Behavior of marine animals, 3: 45-83.
NEWBY, T. C. 1982. Life history of Dall porpoise (Phocoenoides dalli, True 1885) incidentally taken by Japanese high seas salmon mothership fishery in the north western North Pacific and western Bering Sea,
1978 and 1980. Doctoral thesis, University of Washington, 155 pp.
NrsmwAKI, M. 1967. Distribution and migration of marine mammals in the North Pacific area. Bull.
Ocean Res. Inst. I: 1-64.
OHsuMr, S. and K. TAKAGI 1979 (ms). Preliminary report on Dall's porpoise sighted by Japanese salmon
research vessels in the North Pacific in 1978. Inter. North Pac. Fish. Commn. Doc. No. 2150. 28 pp.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

DISTRIBUTION, SEASONAL MOVEMENTS, AND
ABUNDANCE OF PACIFIC WHITE-SIDED DOLPHINSIN THE EASTERN NORTH PACIFIC*STEPHEN LEATHERWOOD, RANDALL R. REEVES,
ANN E. BOWLES, BRENT S. STEWART, AND
KIMBERLEY R. GOODRICH
Hubbs-Sea World Research Institute, 1700 South Shores Road, San Diego, CA 92109, U.S.A.

ABSTRACTAll relevant data available through 1979 on Pacific white-sided dolphins,
Lagenorhynchus obliquidens, in the eastern North Pacific were examined for patterns of distribution, movements, and abundance. In waters east oflongitude180° white-sided dolphins occur from about latitude 20°N to latitude 61°N,
on the continental shelf and offshore. They are present in the mouth of the
Gulf of California and in inland marine waters of Washington, British Columbia, and Southeast Alaska, but apparently they do not usually enter the Bering Sea or regularly penetrate Prince William Sound. They appear to becontinuously distributed across the temperate North Pacific. Seasonal movements cannot be unequivocally demonstrated in any area, although observed
peaks in numbers suggest regular seasonal influxes into waters north oflatitude
40°N in spring and summer and between latitudes 25°N and 30°N in fall.
Evidence for seasonal presence is most convincing off Southern California,
between latitudes 30°N and 35°N, where peak numbers occur inshore in
November through April. No population estimate is possible with currently
available data. On aerial surveys in the well-studied Southern California
Bight, Pacific white-sided dolphins were observed to occur at a peak frequencyof 1.42 individuals per nm flown; because perpendicular sighting distanceswere not recorded consistently for these sightings, we are unable to estimate
survey strip-width or translate the frequency of individuals sighted into an
estimate of density. In a region off Baja California, Pacific white-sided dolphins have been estimated to occur in densities up to 0.06 individuals per
nm 2 • They appear to be the second or third most abundant delphinid inSouthern California waters in winter, after common dolphins and northern
right whale dolphins. The Pacific white-sided dolphin may be the mostabundant delphinid in the temperate eastern Pacific. The 1300 herds sighted
averaged 88 individuals (s= 366). Herds were significantly larger in southern* Information in this report was assembled for the U.S. National Marine Fisheries Service, Southwest Fisheries Center, La Jolla, California under Contract NOAA/79-ABC-00201 and was originally released as
Leatherwood, S. and W. A. Walker. 1982. Population biology and ecology of the Pacific white-sided
dolphin, Lagenorhynchus obliquidens, in the Northeastern Pacific. Part I. Distribution, seasonal movements
and abundance, with a bibliography and summary of specimen materials. NOAA, NMFS, SWFC
Administrative Report LJ-82-18C. 76 p.
Sci. Rep. Whales Res. Inst.,

No. 35, 1984, 129-157

30
1

CH
,REEVES,BOWLES,STEWARTANDGOODRILEATHERWOOD
e
h
ft
nso
o
i
t
r
o
)p
¥
'
l
55。
−
0。
3
l(
a
r
t
en
nc
hani
N)t
N)and northern (>55°
<30°
(
.
)
1
0
.
0
<
P
,
9
6
.
3
=
F
,
8
6
2
1
=
n
,
a
v
wayAno
‑
one
ange(
r

NTRODUCT10N
1hesone oft
,i
)
ig.J
F
s(
n
e
d
i
u
q
i
l
b
so
w
l
c
n
v
h
r
o
n
e
g
ded dolphin,Laise‑t
ic whif
i
ThePacc‑・. Ithas been l
c
i
f
i
c
a
n North P
r
e
t
s
a
ee
h
nt
d delphinidsi
e
but
i
r
t
is
delyd
stwi
mo
LeatherN (de 23。
utiatween about l
s bet
巴r
ewat
at
om temp巴r
r
ted f
por
1~N
tude 6tiad Evans, 1982)andl, Perrin,ansev, 1978;Leatherwood, Ree
s
e
v
e
Re
hecon‑
heedgeoft
tt
s
a
e
tl
oa
can coasttireNorthA me,from th
)
0
5
9
,1
r
e
f
(Schef.
fhel
nentalsitsided dolphinsare a‑c whiteifici自crange, Pa
crnNorthPa
e
st
a
re
i
e
h
Withint‑s. An esnvariousway
si
e
i
t
vi
ti
c
nteractingwithhumana
,i
ource
s
e
er
l
b
i
s
i
yv
l
high
search
e
ayorr
l
p
s
i
cd
i
rpubl
o
redf
u
capt
‑
e
v
i
shavebeenllvidua
15indio1
timated80t
角

f
ho
t
ou
ls
e
s
s
e
gv
n
hi
ea自s
d
i
s
e
g b
n
i
s
i
o
p
r
o
p
s・
n
i
h
p
ddol
e
d
i
s
‑
e
it
h
cw
i
f
i
c
a
.P
.I
g
i
F
d
e
t
a
c
r
a
m
e
ld
l
e
faw
eo
c
n
e
s
b
l日n,a
a
s
r
o
dd
c
r
o
ol
c
i
tb
n
e
n
i
m
o
r
. Thep
a
k
s
a
l
,A
k
a
d
A
s
n
i
h
p
ol
ed
s
e
h
smaket
g
n
i
k
emar
t
dwhi
n
,a
y
a
r
g
k,
c
a
l
fb
no
r
e
gpau
n
i
k
dst•i
n
,a
k
a
e
b
l
neMamma
i
r
lMa
a
n
o
i
,Nat
S
F
l
.
‑
r
fN
yo
s
e
t
ur
o
oc
t
o
h
P
a[
e
ts
日ea
gn
o
c
e
yto r
s
a
e
.
]
)
y(NMML
r
o
t
a
r
bo
La
円

,
.
t
s
l
l
.f
s
sRe
e
l
a
h
V
.I
p
.Re
i
c
S

4
8
9
,1
5
.3
o
N

PACIFIC WHITE-SIDED DOLPHIN

131

since 1966 (Walker, 1975; National Marine Fisheries Service (NMFS), Washington, D. C., 1982, unpublished records; Reeves and Leatherwood, 1984). Small
numbers have been taken incidentally in fishing operations for tuna, anchovy, andsalmon in subtropical, midtemperate and northern temperate waters, respectively(U.S. Dept. of Commerce, 1981 ). These dolphins prey on commercially valuable
fish and squid (Jones, 1981; Stroud, Fiscus, and Kajimura, 1981).
In 1979, under contract from the Southwest Fisheries Center, NMFS, a study
was begun on the population biology and ecology of Pacific white-sided dolphinsin the eastern North Pacific. This paper reports on distribution, seasonal movements, and abundance of the species in North Pacific waters east of longitude
180°, as surmised from all data available through 1979. Results of the remainder of the NMFS-sponsored study, addressing morphology, geographic variation,and general biology, will be published elsewhere by Leatherwood, William A.
Walker and William F. Perrin.
BACKGROUND AND PREVIOUS LITERATURE

Gill (1865) initially described L. ohliquidens from two specimens (U.S. National
Museum Numbers 1963 and 3886) taken off the California coast. Scammon (1874),
referring to those dolphins with which he had become acquainted while whaling in
the eastern North Pacific, reported that "this species has a wider range and congregates in larger numbers than any other of the dolphin family." True (1889)
gave the Pacific white-sided dolphin's distribution as the North Pacific Ocean,
Puget Sound, and the coast of California. Subsequent accounts have added limited
regional and seasonal information while restating the more generalized descriptionsof range made by these early authors.
In the eastern North Pacific, individuals of L. obliquidens have been reported
from the southern tip of Baja California (about latitude 23°N) northward along thecoasts of California, Oregon, Washington, British Columbia, and Alaska to 61°N
(Scheffer, 1950) and westward through the Gulf of Alaska and North Pacific to
Amchitka Island (Scheffer and Slipp, 1948; Cowan and Guiguet, 1956; Brown and
Norris, 1956; Pike, 1956, 1960; Norris and Prescott, 1961; Brownell, 1964; Fiscus
and Niggol, 1965; Walker, 1975; Wahl, 1977; Barham, 1978; Leatherwood andReeves, 1978; Everitt, Fiscus, and DeLong, 1979; Dohl, Norris, Guess, Bryant, andHonig, 1980; Consiglieri and Braham, 1982).
In the western North Pacific these dolphins have been reported to occur from
Taiwan northward along the coasts of Japan and Asia to the Kurile and Commander Islands (Okada and Hanaoka, 1939; Tomilin, 1957; Sleptsov, 1961; Nishiwaki, 1967; Mitchell, 1975). They have not been reported reliably from the Bering Sea (Nishiwaki, 1967; Consiglieri and Braham, 1982).
The statement that L. obliquidens "can be seen in the center of the North
Pacific including the Hawaiian Islands" (Nishiwaki, 1967) has not been substantiated, although recent sightings at about latitude 40°N, longitude 180° (G. Naftel,
Honolulu, Hawaii, personal communication) indicate that they do occur in theSci. Rep. Whales Res. Inst.,
No. 35, 1984

132

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

pelagic mid-Pacific at temperate latitudes. Nishiwaki (1967) also claimed that
Pacific white-sided dolphins are known from as far south as Panama in the eastern
Pacific, but we are not aware of any confirmed records from south of 20°N. Theiroccurrence in partially enclosed areas, such as Osaka Bay (Kuroda, 1953), Puget
Sound (Scheffer and Slipp, 1948), and the Inside Passage along the coast of British
Columbia (Pike and MacAskie, 1969) is well documented. They have been reported to penetrate the Gulf of California to as far north as Gorda Bank (23°00'N,
109°30'W) (Leatherwood and Reeves, 1978; Leatherwood et al., 1982). Althougha skeleton was collected from Valdez, Alaska, in Prince William Sound (latitude
61°N) in 1901 (Scheffer, 1950), no Pacific white-sided dolphins were seen inside theSound during recent extensive aerial and ship surveys (Hall, 1979).
Seasonal shifts in distribution have been reported. Pacific white-sided dolphins are said to be more common in coastal waters during fall and winter, moving
offshore during spring and summer (Brown and Norris, 1956; Cowan and Guiguet,
1956; Norris and Prescott, 1961 ; Brownell, 1964; Pike and MacAskie, 1969; Barham, 1978; Leatherwood and Reeves, 1978; Everitt et al., 1979; Dohl et al., 1980).
They are thought to occur only in warmer seasons in the northeastern Gulf of
Alaska (Consiglieri and Braham, 1982) and to be more numerous in cooler seasons
south of Point Conception, California (Leatherwood and Reeves, 1978). It has
been suggested that such movements are related to changes in prey distribution(Norris and Prescott, 1961; Brownell, 1964; Barham, 1978) and water temperature(Leatherwood and Reeves, 1978; Dohl et al., 1980).
Since Scheffer's (1950) summary of records along the North American coast,
no comprehensive review of the Pacific white-sided dolphin's distribution and movements in the northeastern Pacific has appeared in the literature. The only published estimates of popluation size are Nishiwaki's (1972) statement that there are
30,000 to 50,000 in Japanese waters and Fox's (1977) estimate that about 24,000
inhabit an approximately 1.5 million km 2 area off California and Baja California.
Leatherwood and Walker (1979) considered L. obliquidens one of the three mostabundant delphinids, along with Delphinus delphis and Lissodelphis borealis, in Southern California waters during midwinter.
In this report we examine information available through 1979, from sightingsand collections made north of latitude 15°S and east of longitude 180°, for patterns of distribution, movements, and abundance of the species in the eastern North
Pacific.
MATERIALS AND METHODS

Records of sightings of Pacific white-sided dolphins in the eastern North Pacific forthe years 1949 through 1979 were available from the literature and various unpublished sources. A complete file containing all the distribution data obtained
for this report has been deposited with the Southwest Fisheries Center. Principal
contributors are listed in Table 1, and their approximate areas of coverage areshown in Fig. 2. As in three previous efforts of this kind to investigate otherSci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN133

TABLE I. PRINCIPAL SOURCES OF UNPUBLISHED RECORDS OF SIGHTINGS OF PACIFIC
WHITE-SIDED DOLPHINS IN THE EASTERN NORTH PACIFIC (MODIFIED FROMDAHLHEIM, LEATHERWOOD AND PERRIN, 1982). THE NOTATIONS IN THE MIDDLE
COLUMN INDICATE WHETHER, FOR PURPOSES OF THIS REPORT, THE LISTEDPROGRAM'S SURVEY EFFORT HAS BEEN CHARACTERIZED SUBJECTIVELY(*),
QUANTITATIVELY(+) OR NOT AT ALL (Q) .

Institution/Activity

Principal Area(s) Covered.......

~

Period(s) and Effort~

U.S. National Marine
Fisheries Service
A. Southwest Fisheries
Center
1. Dolphin-tuna observer
program and associatedresearch cruises, 1968
through 1973.

421

I.

Dolphin-tuna observer
program and associatedresearch cruises, 1974
through 1979.
3. Albacore observer
program and associatedresearch cruises, 1971
through 1979.
B. National Marine Mamma! Laboratory
I. Pelagic fur seal programa. 1958 through 1979
2.

Total
No.
Used

Latitudes 35°N to l 5°S, coast
to approximately longitude
160°W.

*

Latitudes 35°N to l 5°S, coast
to approximately longitude
160°W.

+

Latitudes 25°N to 46°N,
within 250 nm of coast.

*

Heavy effort nearshore JanFeb declining and moving
seaward March throughremainder of year. Somecoastward research Qtr. 4.
Same as above, but effort
data available as number ofship survey hours per 5°square (see Fig. 3).
33 vessels, May throughSeptember, generally moving
south to north through season.
410

Latitudes 32°N to 62°N, eastof USA/USSR Convention
line in Bering Sea, east of
longitude 180° in remainderof Gulf of Alaska and N.
Pacific.

0b.

1960's

Latitudes 21°N to 35°N,
within 150 nm offshore andoffshore Baja California as
far as Islas Revillagigedos.

02.

Dall porpoise program
1978 and 1979

Southern Bering Sea andnorthern Pacific Ocean, near
Aleutian Islands. Somecruises in Gulf of Alaska.

03.

Platforms of opportunity All areas.

0

Sporadic coverage, largely insummer, principally searching for and collecting fur
seals. (See various reports ofNorth Pacific Fur Seal Commission ; Kajimura et al.,
1980; Stroud et al., 1981).
Effort characterized but summary unavailable in useable
format.
Cruises working north tosouth in winter and spring,
January through April(Fiscus and Niggol, 1965;
Rice 1963a, b; 1974). Effort
characterized subjectively but
summary unavailable in useable format for this report.
Observers aboard motherships and research vessels
much of summer. Sighting
conditions often poor. Effort
summaries described by
Bouchet (1981) but unavailable in useable format for
present report.
Coverage opportunistic, noeffort data available.
Continued ..•Sci. Rep. Whales Res. Inst.,
No. 35, 1984

134

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICHTABLE 1.

Institution/Activity

II.

Naval Ocean Systems
Center

A.

Ship surveys 1965
through 1975

B.

Aerial surveys 1968
through 1975

III.

University of California

A.

Scripps Institution of
Oceanography-La Jolla

B.

Coastal Marine Laboratory Santa Cruz

1.

Ship surveys

2.

Aerial surveys

IV.

Smithsonian Institution
Pacific Ocean Biological
SurveyContinued.

Principal Area(s) Covered...,....

til>t:iPeriod(s) and Effort

140
Within 150 nm of coast fromlatitudes 22°N to 35°N ineluding Gulf of California.
Some cruises north to Kodiak,
Alaska in spring.
Continental Shelf waters(Shore to longitude 121°W)
between latitudes 31°30'N
and 34°N (Southern California Bight).

0Effort data not consistently
recorded. Cruises conducted
all seasons, but principal
effort winter and spring.

+

Total 29,000 nm surveyed, allmonths. Effort data retained
as transect lines by month(see Fig. 4).

Principally within 100 nm ofcoast of California and Baja
Calif. and in Gulf of California.

01950-1979-miscellaneous
cruises with no indication ofsurvey effort by area orseason.

Continental Shelf waters
between latitudes 31°N and
34°N (Southern California
Bight).
Continental Shelf waters
between latitudes 31°N and
34°N (Southern California
Bight).

+

Effort available as total nm
surveyed by month.

+

Effort available as total nm
surveyed by month.

Latitudes 27°N to 35°N, coast
to longitude 120°W.

01967-1968-unable toquantify effort by area orseason.

54

Additional sources include: The University of Southern California, the Natural History
Museum of Los Angeles County, San Diego Museum of Natural History, Marineland of
the Pacific, Sea World, and numerous colleagues.
* unpublished.

Total
No.
Used

47

33*
196**

** published.

small cetaceans of the eastern North Pacific (Leatherwood and Walker, 1979;
Leatherwood, Perrin, Kirby, Hubbs, and Dahlheim, 1980; Dahlheim et al., 1982),
we pooled all acceptable data to describe overall distribution and to search fortrends in distribution and abundance by season and latitude. Many of the sightings represented incidental observations from programs for which no measure ofsurvey effort was available; such records were of limited value. Other incidental
records came from programs for which survey effort could be subjectively described,
e.g., in terms of general periods and areas of coverage. These records were somewhat more useful. The most important records, however, were those obtained
from the following three programs which provided quantitative data on survey
effort.
Southwest Fisheries Center (SWFC), NMFS
Scientific observers aboard American tuna vessels and U.S. government reSci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

135

U

NOS.C and
BLM /UCSC PROGRAMSSWFC DOLPHIN -TUNA OBSERVER PROGRAM.
SWFC ALBACORE OBSERVER PROGRAM
SMITHSONIAN SURVEY
NMML PROGRAMS

I
I
I.. . .. ..

..

United States... . ·r
I
I

Fig. 2. Approximate areas covered by the principal programs providing sightingsof Pacific white-sided dolphins (modified from Leatherwood et al., 1980).

search vessels operating in the eastern tropical Pacific have supplied sightings madein the area from about latitudes 15°S to 35°N, between the shore and about longitude l 60°W (Table 1). Sightings from this program were subjected to critical
scrutiny using methods explained in detail by Leatherwood (1978). Unverifiable
sightings were discarded. Effort (time during which a NMFS marine mammal
observer was on watch) was calculated as number of hours of watch within each5-degree block (Fig. 3). All minutes in a watch series were assigned to the 5degree block in which the watch series began. Additional information concerning
the protocol for data collection in this program is available in the NMFS Observer's
Handbook (unpubl. manuscr., SWFC, La Jolla).

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

~ i"'"~ a-,,.'--1 ~;_,_,"' "'~

~~

~

~

?:
::ti

120°

110°

s•s1

I

150°

I

I

140°

I

130°

I

120°

I . 'I
I

1100

I

I

100°

90°

80°

I'.· I ·:. f' :J rl I

120°

110°

15°
160°W

s•sl

100°

90°

ao 0

I 'I I

I

I

150°

1400

1300

I

1200

I

I ·1 · L :f:•· k<::~<~<~<~>'l<<~<~'ll(OCT-DEC)

I I I

I I

I

I

...... I 1..... . · 'f'"~.. :. <~).?.:l<'.~~ ... l '=i-, I I

I

I II I

110°

100°

90°

aoo

.·:·

F'"'l·····r···+'>>IY\'L::
FOURTH QUARTER I I I I r ' l f'''f'a I
I

I

~

I

dl\I.\ If'.?rFig. 3. Ship survey effort by NMFS dolphin-tuna observer program, 1974 to 1979,by quarter.

I

I

s•NI

I "''l ·' l'' ~}'j.'>~f) >J>.>I .'' '£'(-~;:<:f'"':::t;··•:·Y:'.'.:.·:f:=·=·=:=t:l I

I

I

I

s•NI

I

I I I I

I

is•I

I I I

l"'t.:·:::-i:·:::.J ..... 1,,li:\":J,:·.··;:tt·:,·'.~.:::::J.'·:l:"?P.>.... l --=t-, I I

I .. k.l . ·y···~'••. ., I

s•1

1

I
I

I

zs•1

'

I

1300

·oTnTn@~i'T...,....or--'I"'--140°

I 'I I

I

35

150°

I

·oTnrrTn~,....,~...,.....---

140°

2s•1

35

150°

0

::I!

::0

tj

0
0

Q

~
~
tj

::>

::;;

;l

1fJ

!7'

i:'j

t'"'

::;;

0

b:I

!7'

~

i:'j
i:'j

::0

_tj

0

0

::;;

::0

i:'j

~

O'l

(.>O

-

f

~

~

"""'~

~~

·'"" ~'"'°!:I)~·'.;?; ~

;:>

I

330

120°

I ~

34°

119°

11s 0

1-;r~~~~~~~~ttt

120°[I>-=:::::::

Is.

...

Son Nicholas

11 ......

119°

1!6°

~n-~!'tLRttnlr

Point Mugu

r= . . \:::?i:e '<>"' ·~.

Santo Roso ls,

ISon Miguel !s.

32°1

330

34°

Fig. 4. Area covered by Naval Ocean Systems Center (NOSC) aerial surveys, 1968
through 1976. The lower left figure shows principal transects flown.

\:

I f'-:?--r=-.

SCA = SANTA CATALINA IS.
SCI =SAN CLEMENTE IS.
SNI =SAN NICHOLAS IS.

117°

I '1

116°

35°,---,~~~~~~~~~~~~~~~~~~~~~~---,(JO-....,

z

9l

t""

0

6t:'l
u
u

::i
t:'l
u,

~

0

~

0
......
"l......

~~

~~

..""~
~ ~

~~

~

~

?:::;,

/I'

120°

i

Son~Borbora

"

119°

e:t _

h

IV

10

6 2 5 15 I!}' ~~~1 l2 12 ~Los
Angeles

tt ..

118°

'9'

r

117°

1 1 I 4 3 1v

v

1 1 1 2 5¥ 7 1/ 5 3/ 6 6 1 1 / 3 3 1 15/ 6 1
1 1 2 ' 4 2
3 2
4 4/4 6 1 2 / 3 3 1 1
1 1 1 1 1 1 1 3 3 3 3 3 1
1 h 2 3 3 2 w 2 1'<6\

4/4 1 3 6 11 V6 2 1 5 10 A 10 11' 7 10 /J
3 9/ 4 2 2 6 V5 3 5 9
1 4 3 1 2 7 10 8 5 3 4 9 /7 1 4 ro\. .
2 1 5 ,"!/ 3 1 2 5 A 4 3
1 3 2 18 "5 v 5 3 1 LA 6 3 1 1 /,i1 1 3 2 2 1
4 1 1 -0 ,.
o/ 10 5 5 3 8 /g 5San
2 2
1 2 o/ 9 5
5//7 2 1 JA 6 1
1~ 7 2 2 1 /7 7 e,_ Diego
3 7 1o 5 2
2-< 6 2 3 4. 7 v5 5 5 3 5/ 6 2
1
2 2
,1, 7
5 6 3 27 7\~ 1.S.A.
.. -··/6 6 1 1 / 6 6 1
3
7 5 2 7,; 11 5 2 3 o/ 7
1/ 6 5/~...,_Mexico
4 !y 5 7 10 4 !V 7
-3 4 1 1 )! 7 6 1 1 /4 3 2 2 1/ 6 3µ-aFig. 5. Aerial survey effort by UCSC, May 1975 through March 1976. Numbers
in 5-degree blocks denote number of times that area was surveyed by air during
the study period. The blocked area corresponds to the area covered by NOSC
aerial surveys, 1968 to 1976 (see Fig. 3). The diagonal lines are the UCSC
transects (from Dohl et al., 1980).

1

1 2 3 3 ;3' 1 3 3 3 V5 3 3 2 5 I/I 2 2 1 ¥
2 4 /. 1 3 1 6/ 4 1 3 2 7
3 4 4 IA 6 2
4 l:Y 1165723
1 6 }<! 9 5 3 4 15' 11 10 12 ~ ,,1 1 1 4 4 3 ~ 5 1 2 2 7 ;f 3 3 45
1 1
2 6 ,?/ 6 3 2 3 5 /5 3 2 4 A 6 3 3 7,4 ~ ..!.! 6 5 lJ 8 2 3 9i}-,
1 l;6 3 2 3 9
1 1 1
1 1 3 33 5 7 4 2
6 12 11 '8 ~ 7 4 4 9 ~ 6 9 7''i-,.,'l1
5 ,1, 1 2 4 12 ~ 4 2 2 15 ... "13 4 6 9~ 5 2 4 19' 1] )\1 1 4 6 81
2 1 2 8 )f 6 6 2 8 ~ 2 1 2 7,1 6 3 51
1 5 111 1 1 3 3 6 5 V2 ~,> 6 '5
~"~
1 1
1
1 4 4 < 1 2 5 V5 1 1 3 12 110 2 3 4 12 J1 4 3 1 a,.-1 2 1 1 7,1 4 2 3 6
4 /5 2 2 3 9 l/7
2 4 3
1 4 9 IJi5 7. 3 2 8 ,,-;
1 1 1
1 3 7/ 3 1 3 6 rY 10 4\'<

3 f 4 2 2 3 A 6 4 4 5 ~ 6 r~
2 1/:3 1!~ 5 1 2 1 5/ 4 3 3 51~~
1 A 3
;J 2
1 2 5/ 4 1 1 2 4 V7 5 v
3 /:2
1 ,/ 2 2
2)3 1 1 2 V4 3 1 3 5 /7 3 3 3 3 9/ 7 3 4 4 7 /9 4 4 4
f2 3 2 3 "5 4 2 2 7 V9 ;;>ll~"f'""'-.j Ji~ 9 3_ 8 V7 8 6 ~rr- "8'l>
2 3 /3 2
2/ 5 3 4 2~
71"'5"~ 9 12 9 9 ~ 4 4 3 6 19' 5 2 1 1/ 1\./-< 2 3 2 2 6 li .Sa 6 5 o/ 4 3 1 4 ,-5 3 4 2 5 o/ 3 6 6 o/ 5 2 \2 3 4 ~ 2 2 3 4 o/' 2 3 2 5 [,'.5 2 3 2 4 ¥2 2 3 o/ 9 10 12 r

lt R

Pt.
1 / "- '!u;onception ~21!.l' 1 4 4,_..
4 .arT.J....._

2 2 l;3

121°

33°

34°

~
~

::r::

0

>-<

~

0
0
tl

Q

tl

z>-

~

~

~

>--3

rn

Y'

~

t-<

0
~

tlj

Y'

~

<

~

0
,tl

~0

~

::r::

~

~

t-<

cc

-""

""'"'~~~[·"'..... .g.
.
~~""'::i:i':->.?: ~~·1<...I'--.

I

Pt .
~

l~once 'tion-,.....

120°.............
1

""

2 2

2 2
2

~!

San!E._ Barbara

\

119°

Los
Angeles

118°

l

l

l

""v 1
1 1 2 11 1 1 1 2 1

i 1\...

1 1 1 1 1 1 1 1 1 1

1 1
1 1

1 1

l

0-

1 1

'

4 6 4
1 1

6 1 8

l
1 l 1 11 1

2
l 9 3 6 ~4 2 3

1 3 3 4 9 4 ~

l 2

l 2 l

l 5 4 3 2 l 2 4 2
l l \.
l l
1 2 1 2 2 2 4 2
1 1
l 1
J 4, 8 I J J J 2 2 J 1 3 3 3 2 1 2 \l 1 1 l ,, 2 1
1 2 1 1 4 4 4 2 2 1
l 1

1 2 1
1 1 l

J

l l 2

1 1 l
1 1

2
1 1 1

l

~1

,,,..._

Fig. 6. Ship survey effort by University of California, Santa Cruz (UCSC), April
1975 to March 1976. Numbers in 5-degree blocks denote number of times thatarea was surveyed by ship during the study period (Doh! et al., 1980).

1 1

l
l 1 l

1 1 2 3 3 2
1 2 2 1 1 2
1 1 2
1l 1 4 3 1

'It:-.
1 1 1 3 5 5 3 1
2 4 6 ii!-~
1 10 3 '\,l 1
1 1 4 5 2 3 2 3 3 6 6 8 4 6 2 11"-...
1 1 1 l l 1 l 4 6 8 6 2 ·2 4 2 2 1 3 4 l 3 2'l 1 l 1 1 l 4 2 1 l 3 6 ~~ 1 3 1
5 4
3 i"- ....
l 1'r--..
4 2
3 2 5 3 2 2 2 2 2 2 4 4 4 4 ,j 3 5 ) ' 4 2 J
J l
3 4 5 Js 2 2 .] l 4 2
l l
l 1

f::" 111~ 2_~ "'"'""U""> 2 3_ 2'-2 1 lj'-n1 1 1
1 2 2 2 3 3 :}.
l4 2 ~rB' 3 4 7 7 4 1 1 1\
1 1
2 2 4~ 8 5 4 4 l 1 l 2 5 5 2 l 1 1 1 1\
1 1 1 2 1
1 1 1 3 4 3 1 1 3 3 2 3 2 5 5 2 1

1 2 2 l

121°

\

'

\

Mexico1u.S.A.
r-··-··

San
Diego

117°

33°

34°

~

-

z

~

t"

tl

0

~tl

"'

>-3
~

~......

0......

>'!j~0......

140

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

Naval Ocean Systems Center (NOSC)
Aerial surveys were conducted regularly by the Naval Undersea Center (now
NOSC) from January 1968 through April 1976 over the California continental
shelf, principally between latitudes 32°N and 34°N (Table 1; Fig. 4). The
methods employed in these surveys were described in detail by Leatherwood (1974),
Evans (1975), Leatherwood and Walker (1979), and Leatherwood et al. (1980).
Sightings were critically evaluated using the review procedures of the SWFC system referred to above, and unverifiable sightings were discarded. Effort was given
as plots of transect lines (Fig. 4) and estimates of nautical miles (nm) flown.
University of California, Santa Cruz ( UCSC)
Shipboard and aerial surveys sponsored by the U.S. Department of the Interior, Bureau of Land Management (BLM), were conducted in the Southern
California Bight during 1975 and 1976 by the Coastal Marine Laboratory, University of California, Santa Cruz (Dohl et al., 1980) (Table 1). Transects were
designed to provide uniform coverage of the entire study area throughout the year.
Methods of quality control on sightings data were not reported. Therefore, because original data entries were unavailable to us for review, we have simply accepted sightings on the assumption that they were subjected to adequate quality
control by the program's internal review process. Effort was characterized as thenumber of times each 5-minute block was surveyed (Figs 5 and 6) and as thenumber of nautical miles covered (Table4). Note the substantial overlap in aerial
coverage between NOSC and UCSC surveys (Figs 4, 5, 6).
Other Sources
In addition to the unpublished sources of data, we examined scientific publications and extracted sighting records from them. For all these records, we collected, as available, date, location, number of animals, and information source.
We assembled a total of 1300 reliable records, 1104 unpublished accounts from various programs and 196 previously published. Except for obvious misidentifications
or obscure references with irreconcilable disparities, we assumed published records
reflected correct identification. Sightings published twice or more were only
entered in the data base once. Each known at-sea collection for which date, location, and number of animals was available was also considered to represent asighting of a herd. For each map and analysis we used all appropriate sightings.
For those sightings in which herd size was recorded as a range (e.g., 45-50 animals),
we used the midpoint rounded to the lowest integer (e.g., 47).
Data were grouped by various combinations of quarter, 1- and 5-degree latitude belts, and depth zones (inside or outside the approximately 1,000 fm isobath).
Maps, histograms, descriptive statistics, and frequency distributions were prepared,
and grouped or paired samples were compared to detect patterns of occurrence(Table 2). For numbers of herds and numbers of animals, we determined sample
sizes (N), sum, mean (x), standard deviation (s ), standard error (sx) and range(Table 3).
Sci. Rep. Whales Res. Inst.,.No. 35, 1984

PACIFIC WHITE'-SIDED DOLPHIN141

TABLE 2. THE VARIOUS COMBINATIONS IN WHICH AVAILABLE SIGHTINGSDATA WERE EXAMINED
Quarterly
OverallNo. Herds
No. Individuals
Herd size

MM

1° belt
H
H

D
D

F

M
M

D
D

Depth zone
by 5° belt
and quarter5° belt
H
H

D
D

H
H

D
D

H
H

D

M=maps
H=histograms
D =descriptive statistics
F=frequency distribution

TABLE 3. NUMBER OF HERDS, TOTAL NUMBER OF ANIMALS, AND HERDSIZES FOR PACIFIC WHITE-SIDED DOLPHINS, BY QUARTER AND
5° LATITUDE BELT, FROM LATITUDE 20°N TO 60°N
Latitude
belt
20-25
20-25
20-25
20-25
25-30
25-30
25-30
25-30
30-35
30-35
30-35
30-35
35-40
35-40
35-40
35-40
40-45
40-45
40-45
40-45
45-50
45-50
45-50
45-50
50-55
50-55
50-55
50-55
55-60
55-60
55-60
55-60

Quarter
I

No.
Herds
23

II
III

IV
I

II
III

IV
II
III

IV
I

II
III

IV

7
3
4

99
85
105
55
87
49
38
66
154
119
38
16

I

8

II
III

28
56

IV

8

II
III

17
47
39

IV
I

II
III

IV

6
9
8

15
11

Total no. Mean herdsize
animals269.396, 196
30
210
35
105
11.50
46
91.88
9,096
65.22
5,544
292.0530,665
119.456,570
100.25
8,722
88.24
4,324
142.76
5,425
48.67
3,217
23.15
3,565
20.54
2,444
22.39
851
62.25
996
65.25
522
61.82
1, 731
39.64
2,220
8.88
71
10.82
184
83.28
3,914
68.15
2,658
80.67
484
59.44
535
174.88
1,399
204
13.60
68
748

St. dev.

St. error

682.28
44.99
35
9.95
466.24250.72936.48321.03217.41209.02417.03115.84
59.57
64.20
49.31
125.10112.68160.69
61.58
14.67
10.31
210. 74
163.6894.09
43.41
337.8315.32
107142.27
17.00
4.98
46.86
27 .19
91.39
43.29
13.31
29.86
67.65
14.26
4.80
5.89
8.00
31.28
39.84
30.37
8.23
5.19
2.50
30.74
26.21
38.41
14.47
119.443.96
32.26

572.17258.15280.31

165.17
66.ti5161.84

Min. herd Max. herd
size
size
3,000
125
10
75
20
3,500
2,000
6,000
1, 750
1
1,000
1
1,000
2,500
750
500
500
300
450
2
300
725
1
275
2
45
30
1,000
900
2
250
250
5
3
100
1,000
50

I
111

12
I5

IV

3

II

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

2,215
2,057
529

184.58137 .13176.33

2

12

2,000
1,000
500

142

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

For analysis of latitudinal effects, only groupings by 5-degree latitude belt
resulted in adequate sample sizes. One-degree belts were retained for mapping.
Maps were produced showing number of herds (Figs 7 and 8) and number ofanimals (Figs 9 and 10), by one-degree blocks for all samples combined. Charts
were made on a DEC-PDP 11/34 using the AMPS Mapping Package (Analytical
Software, Inc.). Densities for each block on the sighting charts were calculated bysumming the number of herds and number of animals sighted in each block eachquarter. For example, all the animals sighted from longitudes 117°00'W tol 17°59'W and from latitudes 32°00'N to 32°59'N were counted as being in the block
32°N by 117°W.
The following problems with data ruled out the use of significance tests on
any of the data sets: (a) sightings were not collected at random; (b) sightings could
not be assumed to be independent of one another, because of the animals' tendency
to aggregate and variability among observers in defining and scoring groups as

Fig. 7. Number of sightings (herds) of Pacific white-sided dolphins by I-degree
block from all seasons and all sources, 1949 to 1979. The inset illustrates the
species' probable range.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

~~

¥

:0

~

~"'
~

~~

....

,;.» '?

~·
<Jo ~

:>

20

30

40

170

180

180

170

N=32/

,,,,,,-

170

Ill!

"+20

160

IIl"

.

rn

150

160

lllrn

m

140

140

140

rn

130

'

130

130

\-

~

'

''

120

'

'r

120

120

~

-'

0

110

E)

20

30

40

50

60

20

30

40

50

60

20

20

40

50

60

30

40

50

60

~ 30

_...

'~

110

110

_..

~

110

-~\

1
ill

\-

120

180

~· -'-~· -'-

I

180

180

m

1

~

180

170

N=/77

,,,,,,

170

170

N=357

,,,,,,

170

160

160

160

.. .,"

150

150

140

140

III

ffi
lllllII III

Fig. 8. Number of sightings (herds) of Pacific white-sided dolphins by I-degree
block, by quarter, from all sources, 1949 to 1979.

150

rn mm

150

!SO

160

N= 407180'l~III~60

20•mm " 10-20

lllll " 5-10!/~

on " 2-5,,,,,,

160

m"I.......,, ..A-

F'O

~

il

180

30 HI

40

50

60

\-

130

130

III

120

E)

~

110

''

e

120

110

I

50

60

20

20

H-130

In 40

_.. i

~

110

110

\~:'

'

120

120

30

IH<10

~ 50

• 60

'\~ ~

~~

130

""

:;;:

z

::r:
...,

"d

t"

0

l:j

l:j
t'1
l:j

~....

~.......,

0

'":rj
....

~
0
...,

~~~

~~

--~ ~

~~

~~

~

~

~

?:

180

20

180

30 Hl

40 ~

50 Hl

50 111

.,_,~

-

[]]

[Il

170

•<:>

"'-

140

[Il

mm ill[!]J [!]J

II

[]]

\-

ITll

[]]

~

lllil

™

-

Number

•

.

.&,,.

~

>1001

110

../

IDlll 501-1000[Il] 11-100
lIIIl 101-500[[] 1-10

:A

p---

I

110

SIGHTINGS KEY

I

I

~

'

120

130

120
130
140
150
150
Fig. 9. Total number of Pacific white-sided dolphins observed by I-degree block,from all sources, 1949 to 1979.

,o

N = 1121 138 Individuals

,.

..A-

;?.P

1

L ihiifiilffii i11\1i1 llliirtillit

150
3'

I
I

150
C3 \

I

0

170

20

30

40

50

hi 50

t-'

~

>-3

:i:::

""'
0

:;>::l

tl

0
0

tl
C'l

>
z

>-3

~:;>::l

i:rj

rJJ.

i:rj
~w.

t-'

~

0

t:C

~w.

<
i:rj

i:rj
i:rj

:;>::l~tl

00:;>::l

i:rj

:i:::

>
>-3

i:rj

:E

~-

!"'"

~

~

"'~

~"
1'"

~~

.....

""'~
~""~

~

~~

180

Ill"'

20

180

30 ~

40

Iii

o.,,

[]]

170

160

....."'
140

\-

~-

130

~

,,

130

130

130

p-

110

110

~

::>1001

120·110"IDlll!t_~\•lllII 101-500[]] 11-100

Number(]] 1-10.

SIGHTINGS KEY

p-

110

120

.J

120

rrlllHll\,\~

nm 101-500

aa 11-100

Number(]] 1-10

SIGHTINGS KEY

120

40

20

20
180

30 ~

~ 30

180

180

IB

~

180

.1

50

60

20

3o

40

50

60

I,,

50

60

20

~30

~

50

60

M_.A...

e

M_.A...

0

160

150

170

,,,.P

170

N

lSO

lSO

140

140

01

140

160

150

140

=12, 656 Individuals

160

160

·--" .. <>=21, 780 Individuals

170

N,,,,,,-

170

Iii

1111

Iii

~

Fig. 10. Total number of Pacific white-sided dolphins observed by I-degree block,by quarter, from all sources, 1949 to 1979.

150[]] []]Il]

140

l!Ill!Il

140

150

140

lSO

N• 44,186 Individuals

,.

160

,,,,,,-

160

170

M_.A...

150=28,818 Individuals

170

N,,,...-

160

180

e

M..A-

0

170

180

so ~

60

20

30 ~

4J

so

60

uo

130

130

am

m

130

UJ.U
IUl-::>UU(]] 1-10

NumberSIGHTINGS KEY

p-

110

p-

110

110

l:?O

t:\

c-

~

110

.J

lllII 101-500[ill 11-100(]] 1-10

NumberSIGHTINGS KEY

120

120

.,~,

~"-

\-

120

so

60

20

30

20

~ 30

~ 40

ii

~

~ 40

~so

60

::;
(JI

z

::i::
,_.

'tl

t""

0

"'
u
ti::I
u
u

t;l
,_.

t-l

~,_.

0

~
0
,_.
""'.!
,_.

146

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

separate small herds or "superherds "; and (c) pooled effort was impossible toquantify. We feel that even if statistical significance were demonstrated, it would
not be possible to ascribe any biological significance to the results. Therefore, todefine patterns for the area overall, we depended solely on direct examination ofgraphic presentations of the data.
Data from the Southern California Bight were examined in somewhat greater
detail. For the NOSC aerial surveys, we calculated number of herds per hundred
nautical miles and number of dolphins per nautical mile flown (Table 5, I 1 and I 2,
TABLE 4. SUMMARY OF EFFORT AND SIGHTINGS OF PACIFIC WHITE-SIDEDDOLPHINS BETWEEN LATITUDES 32°N AND 35°N AND A CALCULATED INDEXOF DENSITY FROM UCSC AERIAL SURVEYS, MAY 1975-MARCH 1976
PeriodNauticalmiles flown

Number ofanimals seen

I2
Number of dolphins
per n.m.

May
July
AugustSeptember
OctoberNovember
DecemberJanuary
February
March

954
2,080
1,383
765
1,935
2,034
934
3,255
2,520
1,800

2,024
2,540
70
100
292
1,892
0
12
7
768

2.120
1.220
0.050
0.140
0.150
0.930
0.000
0.003
0.003
0.043

TABLE 5. INDICES OF DENSITY OF PACIFIC WHITE-SIDED DOLPHINS (L.o.) IN THE
SOUTHERN CALIFORNIA BIGHT (32°N TO 34°N), 1968-1976, FROM NOSC AERIALSURVEYS. THE TOT AL NUMBER OF HERDS SEEN IS FOLLOWED IN PARENTHESES
BY THE NUMBER OF HERDS FOR WHICH ESTIMATES OF NUMBERS WEREAVAILABLE. ALSO SHOWN ARE INDICES OF DENSITY FOR NORTHERNRIGHT WHALE DOLPHINS (L.b.) FOR THE SAME AREA (FROM
LEATHERWOOD AND WALKER, 1979)

Month

Effort flown
in n.m.

Total no.
of herds
L.o.

January
February
March
April
May
June
July
AugustSeptember
OctoberNovember
December
Totals

1,890
2,005
2,645
4,475
2, 1501,390
2, 1202,267
1,470
1, 795550
2,025
24,76216 (15)12 (18)7
23 (15)
3
1
4
3
3 (2)
3 (2)
19 (13)95 (72)

Ii-Herds per
100 n.m.
L.o.

L.b.

0.85
0.60
0.26
0.51
0.14
0.07
0.19
0.04
0.20
0.17
0.55
0.94
0.384

3.30
11.48
1.38
2.04
0.39
0
0
0
0
0.36
0.54
I. 77

Total no.
of indiv.
L.o.

I 2-Dolphins
per n.m.

2,687
1,626
766
3,626
90
50
268
6
68
296
159
2, 12311, 766

1.42
0.81
0.29
0.81
0.04
0.04
0.13
<0.01
0.05
0.16
0.29
1.05
0.48

L.o.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

147

PACIFIC WHITE-SIDED DOLPHIN

respectively). Because herd size was not estimated for each sighting, in calculating
the 12 values we: (a) found that no significant variability in herd sizes among months
could be demonstrated and (b) assumed that those for which herd size estimates
were available (72) were representative of all 95 herds. Therefore, in estimating
number of animals seen per month, each empty cell was filled with the overall

1
1.40

1.40

1.20

1.20

N'
II
z
c

~
~

z
0
0

1.00

1.00

0

en
a::

'TI

0

J:

CD
l'T1

;:o

.....
w

s:

z

0.80 0

0.80

<
0

u.
0

c

a::

l>

w

r

lil

(/)

0.60 z.....

~

0.60:::::>

z

s:

II

D
0.40

0.40

0.20

0
Fig. 11. Indices of abundance of Pacific white-sided dolphins off Southern California 1968 through 1976, based on NOSC aerial surveys. The * indicates 12
values calculated from Doh! et al., 1980, Table III-93, for aerial surveys of thesame area, May 1975 to March 1976.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

148

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

mean (x= 145.7, s=271.2).
For comparison, we converted indices of density for northern right whale
dolphins in the same area, reported by Leatherwood and Walker (1979) as thenumber of herds or animals per square nautical mile, to 11 and 12 values and presented those in Table 5. For the UCSC aerial survey data (Dohl et al., 1980), we
also calculated monthly 12 values (Table 4).* Trends indicated by the two programs (NOSC and UCSC) were compared graphically (Fig. 11 ), but no attempt
was made at a rigorous analysis of observed patterns.
RESULTS AND DISCUSSION

Overall Pattern of Distribution
Herds of Pacific white-sided dolphins were seen in all 5-degree latitude belts
between latitudes 20°N and 60°N in all quarters of the year, except for latitudes
55°-60°N in quarter I, January-March. The 1,300 herds (112,138 individuals)
included in the analysis were widely distributed from the continental shelf throughout the pelagic temperate eastern North Pacific, although records were more abundant within the few coastal I-degree blocks in each latitude belt (Figs 7 through10). The apparent coastward concentration as well as the areas of higher density
observed north to south along the coast probably reflect levels and centers of observational effort (Fig. 12), with sightings clustered near Seattle, near the Monterey/ Santa Cruz area, and within the 35° to 30°N and 30°N to 25°N latitudebelts.
The steady decreases in number of sighting records throughout the year, from407 herds in the first quarter to 177 herds in the fourth quarter, also probably reflect effort. In fact, for all the data combined, there were no detected trends indistribution of herds which could not be explained readily on the basis of the survey effort alone. It is only when records are examined regionally, with emphasison the three programs permitting quantitative analysis, that any patterns can bediscerned which might be considered biologically meaningful.
The probable North Pacific range of white-sided dolphins, inferred fromrecords presented herein and published records from the western North Pacific, isshown in the inset to Fig. 7. Available data suggest a continuous range acrossthe North Pacific. In the area covered by this paper, sightings decrease in thearea west of longitude 135°W and south of latitude 45°N, but there has been insufficient observational effort in pelagic areas to confirm the existence of a hiatus
between eastern and western North Pacific " populations ".
Distribution North of Latitude 40°N
Sample sizes are small and effort unquantifiable north of latitude 40°N.
Sightings do occur there throughout the year, although almost all the more north-* Estimates of density and indices of density from previous programs are presented in the units reported.
Original data were unavailable to us; so, we were unable to translate to common units.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

50

VitlJ 50° N - 60°N

n = 73 herds~ 30°N - 35°N

n = 240 herds[/=I 25°N - 30°N

n = 344 herds

149

I-

z

w

(..)

a: 40
w

a_

>(..)
z

w

:::::>

0

30

w

a:

.l.L.

w

>

j:: 20

<{

_J

w

a:
10

QUARTER
Fig. 12. Relative distribution of sightings by quarter within the three areas ofgreatest interest. The number of herds comprising each class interval is shown.

ern records refer to quarters II and III (spring through fall), and almost all thesightings for quarters IV and I are in coastal regions. In the Gulf of Alaska, theseasons when Pacific white-sided dolphins are reported most frequently and widely
are also the periods of most intensive fishing and research activity. We have no
way of determining whether this apparent seasonal pattern in dolphin distribution
is real or an artifact of observational effort. Based on opportunistic sightings of 3,8, 50, and 15 herds in quarters I through IV, respectively, Consiglieri and Braham(1982) concluded that this species, indeed, occurs seasonally in the Gulf of Alaska.
They further concluded, based on the same set of sightings, that in southeasternand southern Alaskan waters Pacific white-sided dolphins occur principally on thecontinental shelf. Further evidence that Pacific white-sided dolphins are present
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

150

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

seasonally off southern Alaska is provided by Hall and Tillman (1977) and Hall
(1979), who reported that despite extensive year-round aerial and ship surveys in
Prince William Sound and immediately adjacent to its entrances, Pacific whitesided dolphins were observed only once-in October just outside Montague Strait.
Currently available data are opportunistic in nature or limited in region, andtherefore inconclusive. The question of seasonality of occurrence of Pacific whitesided dolphins in the Gulf of Alaska and North Pacific north of latitude 40°N,
particularly in pelagic regions, cannot be resolved without systematic seasonal
sampling over a broader area than has been surveyed to date (1982).
From available data, we are unable to verify the reported occurrence of Pacificwhite-sided dolphins in the Bering Sea (Clark, 1945 ). The various programs of
NMML (see Table 1), the sources of incidental sightings used by Consiglieri andBraham (1982), and 8 one-hundred hour aerial surveys of the eastern Bering Sea
conducted between March 1982 and April 1983 (Leatherwood, 1983) likely provided adequate coverage of the waters north of the Aleutians to judge whether
these dolphins occur regularly in the Bering Sea. The absence of records is taken
to mean that they do not.

Distribution South of Latitude 23°N
Similarly, we regard the evidence that Pacific white-sided dolphins do notoccur regularly south of about latitude 23°N to be convincing (see Figs 7 and
9). Coverage of the waters south of Baja California has been extensive in botharea and season.
Although observational effort in the NMFS dolphin-tuna program generally
decreased from quarter I to quarter IV according to the fishing schedule of thetuna fleet, there was some effort in a broad area south of latitude 30°N year-round(Figs 2 and 3). In addition to the shipboard observations, three extensive aerial
surveys of the eastern tropical Pacific tuna grounds have been conducted by NMFS
(Smith, 197 5; Barham, Evans and Coe, 197 5; Barham and Powers, 1977; Powers
and Barham, 1977; Holt and Powers, 1982). Therefore, we consider the low number of sightings there-five confirmed south of latitude 23°N, the southernmost at
20°N-to be biologically meaningful. If appreciable numbers of Pacific whitesided dolphins had been present, there undoubtedly would be more records.
Depth Preferences
Northern and southern limits of the species' range are more readily defined
than are its inshore-offshore limits. There have been a few sightings in water as
shallow as 20 fathoms (Consiglieri and Braham, 1982; NOSC unpublished records;
Leatherwood, personal observations) though these appear exceptional excursions
into shallow water. Otherwise, these dolphins are encountered widely in continental shelf, continental slope, and offshore zones. Because of uncertainty inposition records, we cannot report the maximum depth of water where Pacificwhite-sided dolphins have been seen. However, the westernmost records in the
study area were plotted at locations in which surrounding water for a radius of at
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

151

least 100 nm was more than 3000 fms deep.
Little can be said about the relative frequency of occurrence of Pacific whitesided dolphins in waters of different depth. The fact that, overall, most sightings
were made inshore of the approximately 1000 fm isobath probably reflects effort
patterns rather than an aspect of dolphin distribution.
There does appear, however, to be a tendency for Pacific white-sided dolphins
to occur nearer to the coast south of about latitude 30°N. The effort in pelagic
waters between latitudes 20°N and 30°N was appreciable and the encounters withPacific white-sided dolphins few.

Seasonal Trends in Distribution
The only two portions of the study area in which observed distribution patterns are not likely an artifact of sampling effort are the waters off Baja California
and in the Southern California Bight. Off Baja California, the effort is tied tofishing and research activities of the tuna fishery, essentially declining steadily
throughout the calendar year with a slight increase in the fourth quarter associatedwith research cruises and early departures from San Diego by fishing vessels boundfor the eastern tropical Pacific (Fig. 3 ). Despite this declining trend in effort,
the number of sightings and number of animals per quarter off Baja California did
not decline consistently through the calendar year (Figs 8 and 10, Table 6).
In fact, for the area between latitudes 25°N and 30°N, the number of sightings andtotal number of animals observed in the third quarter were substantially greaterthan the number observed during the previous two quarters (Table 3). This sharp
increase in numbers during a period of relatively low sampling effort is of interest.
It suggests an influx of animals to this area during late summer and early fall.
There is no reason to believe such an influx would consist of animals moving inshore from the west. Rather, judging by published accounts about the seasonal
movements of Pacific white-sided dolphins south of Point Conception (e.g. Brown
and Norris, 1956; Leatherwood and Reeves, 1978; Leatherwood et al., 1982), it
seems most reasonable to us that these are dolphins moving southward from thearea off Southern California between latitudes 30°N and 35°N.
The monthly indices of density from the NOSC aerial surveys indicate that
Pacific white-sided dolphins are at their peak density and peak number off Southern
California from November through April, and are less common from late spring
TABLE 6. DETAILS OF EFFORT AND SIGHTINGS OF PACIFIC WHITE-SIDED DOLPHINS,
25°N AND 30°N, FROM NMFS DOLPHIN-TUNA PROGRAM, 1974 THROUGH 1979.
I 1 AND 12 VALUES ARE NUMBER OF HERDS AND NUMBER OFINDIVIDUALS PER SURVEY HOUR, RESPECTIVELY.
QuarterApproximate
number ofsurvey hours

Number ofsightings

11

Number ofanimals12

Meanherd size

I
II
III
IV

>375
565
250
190

99
85
105
55

<0.27
o. 15
0.44
0.29

9,096
5,544
30,6656,570<24.26
9.83
3,738.66
34.58

92
65
292
119

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

ii

152

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

through late fall (Fig. 11, Table 5 ). This seasonal pattern is consistent withthat reported for the area by previous investigators, based on subjective impressions (e.g., Norris and Prescott, 1961; Leatherwood et al., 1972) or on preliminary
analysis of the NOSC data (Leatherwood and Reeves, 1978; Leatherwood et al.,1982). It is also very similar to the seasonal pattern reported by Leatherwood andWalker (1979) for the northern right whale dolphin, a sympatric species with which
Pacific white-sided dolphins have a strong affinity in coastal waters (Table 5 ).
From these data, Pacific white-sided dolphins appear to reach their lowest densities off Southern California during the periods discussed above, when they areapparently at their highest densities off Baja California. We emphasize that theargument for a relationship between these two phenomena is only circumstantial;
there is no direct evidence of a coast-wise migration. The origin of the apparent"immigrants " to Baja California waters in quarter III and the destination of the"emigrants" from Southern California in quarters II and III remain unknown.
The peak density off Southern California is 1.42 individuals per nm (Fig. 11); off
Baja California it is reported to be 0.06 individuals per nm 2 (Fox, 1977).
The trends indicated by the UCSC aerial surveys are slightly inconsistent withthose indicated by the NOSC program; the latter covered a slightly more coastal
area. Densities derived from data collected in the 10-month UCSC programfluctuate considerably, with about 1-2 individuals per nm 2 in May, July, and

198

II

I 86

169

l~il ~l i

150
Ul
0

0:::

w

::i:

u..
0

100

0:::

w

iliiiiil!

N = 1269

x = 88161

s = 366
1.11·11,

~~~~I

I 14

I
I ~I I
83

CD

74

~

64

:::>

z

50

63

30 '

;:1111111

"''

"'

I/)

I'-

I

I

<;!"

<£>

~

~

I

I

a:>

~

j;;

0

I

I

0

I/)

"' "'"'

<£>

"'
I

0
<D

(j)
(j)

I

!'-

"'

0I/)
,._I
;;;

a:>

(j)

I/)

I/)
(j)

I'-

~

~

<;!"
I

"'0
I/)

I

I

I/)
(j)

(j)
I/)

,._

~

"'~

0

0
0
0

"'<£>

I/)

I

I

<£>

(j)
(j)

<£>

"'

~

"'

0

HERD SIZE {LOG TRANSFORM)

I

I/)

Fig. 13. Log transform of sizes of herds of Pacific white-sided dolphins observed in
the eastern North Pacific, 1949 to 1979. Number of herds comprising each classinterval is shown. The log transform was performed strictly for presentation. No
analysis was conducted on logs of data.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

153

November, and much lower densities in all other months (Table 4 ). The differences may be due to small sample sizes and the short period of coverage in the
UCSC program. However, if they are not, then the results may indicate a shiftof the Southern California portion of the population offshore and northwestward
in quarters II and Ill.
Hubbs (1961) described a major transition zone for marine fauna along theouter coast of Baja California at about 24°N latitude, in the vicinity of Magdalena
Bay. Au, Perryman and Perrin (1979) noted another water-mass change at themouth of the Gulf of California, where the fauna tends to change from temperate
to tropical. As a temperate-zone species, the Pacific white-sided dolphin probably
is influenced by these oceanographic changes. In the areas of most intensive observational effort, between latitudes 20°N and 30°N, it was observed mainly shoreward of the outer margin of the California current (Owen, 1974), suggesting that
it is principally an inhabitant of rich upwelling waters.
Trends in Herd Size
The overall distribution of herd sizes is shown in log-transform as Fig. 13.

200 . . . . - - - - - - - - - - - - - - - - - - - - - - ,N=/268

177

w 150
N

(/)

Cl

0:::

w
:r: 100
w
(!)

cl:

0::

w

>
cl:

50

N=

0

AREA

~

C)
IY)
01

~

~

lC)

~
0

I

~ ~

'\t0

~

JC)
'\t-

~

C)

~

:g

~

C)
~

? J 01
0

lC)

'\t-

C)
lC)

~

Fig. 14. Mean herd sizes by 5-degree latitude belts, from all sources, 1949 to 1979.
Mean values are shown above each class interval. Number of herds comprisingeach class interval is shown.

Sci. Rep. Whales Res.Inst.,
No. 35, 1984

154

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

The number of animals in the 1,269 sightings for which "group" size estimates wereavailable ranged from 1 to 6,000, about a mean of 88. Above about 20 individuals,
the apparent " pulses " in group size are probably spurious, being caused by thetendency of observers to classify estimates into rounded units. Herd sizes varied
over the entire geographic range of the sightings (Fig. 14 ). Those north oflatitude 55°N and south of latitude 30°N were significantly larger than those between 30°N and 55°N (n= 1,268, F=3.69, p<0.01 ). In the northernmost area
(north of 55°N), where sea-surface conditions are consistently inhospitable to cetacean surveys, it is possible that bad weather and observer bias resulted in a tendency to see and record only large herds. In the other two areas (south of 30°N
and between 30°N and 55°N), we assume that observers could detect herds of various sizes and that most participants were able to estimate herd size in a relatively
accurate and consistent manner. Therefore, we do not believe the observed differences are artifactual. It is unclear why herds would be larger off Baja California than elsewhere. Perhaps there are inherent differences in herd-size estimationfrom aircraft (the principal platform used for observations between latitudes 30°N
and 35°N) and ships (the platform used almost exclusively south of 30°N).
ACKNOWLEDGEMENTS

This work was sponsored by the National Marine Fisheries Service, Southwest
Fisheries Center, La Jolla, California under contract NOAA/79-ABC-00201 to S.
Leatherwood and William A. Walker. We thank Dr William F. Perrin (contracttechnical representative) and Mr Walker for invaluable help with this phase of
the study. Further, we thank them and Dr Douglas DeMaster for review of thecontract report. The Inter-American Tropical Tuna Commission kindly aided in
the analysis and preparation of figures. Chick Hayashi prepared the figures.
Angela Rowley typed the manuscript.
REFERENCES
Au, D. K., W. L. PERRYMAN and W. F. PERRIN, 1979. Dolphin distribution and the relationship to environmental features in the eastern tropical Pacific. SWFC Admin. Rep. LJ-79-43. 59 pp.
BARHAM, E., 1978. Historical marine mammal sightings in Monterey Bay. (Unpubl. manuscr., SWFC, La
Jolla). 18 pp.
BARHAM, E. G., W. E. EVANS and J.M. CoE, 1975. Aerial survey of eastern Pacific porpoise populations:
methods and impressions. p. 8 In: Abstracts: Conference on the Biology and Conservation of Marine
Mammals, Dec. 4--7, 1975, Univ. Calif., Santa Cruz. 62 pp.
BARHAM, E. and J. POWERS, 1977. Aerial survey of porpoise populations in the eastern tropical Pacific:
equipment, method, procedures. p. 5 In: Proceedings (Abstracts): 2nd Conference on the Biology ofMarine Mammals, Dec. 12-15, 1977, San Diego. 88 pp.
BouCHET, G. C., 1981. Estimation of the abundance of Dall's porpoise (Phocoenoides dalli) in the North
Pacific Ocean and Bering Sea. Northwest and Alaska FisheJies Center Processed Report 81-1. 25 p.
BROWN, D. H. and K. S. NORRIS, 1956. Observations of captive and wild cetaceans. J. Mamm. 37 (3):311-326.
BROWNELL, R. L., ]R., 1964. Observations of odontocetes in central Californian waters. Norsk HvalfangstSci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

155

Tid. 53 (3): 60-66.
CLARK, A. H., 1945. Animal life in the Aleutian Islands. pp. 31-61 In: H. B. Collins, A. H. Clark andE. H. Walker (eds). The Aleutian Islands: their people and natural history (with keys Jar the identification of thebirds and plants). Smithsonian Institution, War Background Studies 21: 1-131.
CoNSIGLIERI, L. and H. W. BRAHAM, 1982. Seasonal distribution and relative abundance of marine mammals in the Gulf of Alaska. NOAA Techn. Memor. (in preparation).
COWAN, I. McT. and C.J. GuIGUET, 1956. pp. 256-257 In: The mammals of British Columbia. British
Columbia Provincial Museum, Victoria, B. C. 414 pp.
DAI-ILHEIM, M. E., S. LEATHERWOOD and W. F. PERRIN, 1982. Distribution of killer whales in the warm
temperate and tropical eastern Pacific. Rep. int. Whal. Commn 32: 647-653.
DoHL, T. P., K. S. NORRIS, R. C. GuEss,J. D. BRYANT and M. W. HONIG, 1980. Summary of marine mammal and seabird surveys of the Southern California Bight area 1975-1978, Vol. III (2), Cetacea of theSouthern California Bight. NTIS PB81-248189. 414 pp.
EVANS, W. E., 1975. Distribution, differentiation of populations, and other aspects of the natural history ofDelphinus delphis Linnaeus in the northeastern Pacific. Ph.D. Thesis, U.C.L.A. 145 pp.
EVERITT, R. D., C. H. Fiscus and R. L. DELONG, 1979. Marine mammals of northern Puget Sound andthe Strait of Juan de Fuca. NOAA Techn. Memor. ERL MESA-41: 117-118.
Fiscus, C. H. and K. NmGoL, 1965. Observations of cetaceans off California, Oregon, and Washington.
U.S. Fish. & Wild!. Serv., Spee. Sci. Rep.-Fish. #498. 27 pp.
Fox, W., ]R., 1977. Supplemental statement of Dr. William W. Fox, Jr., at the public hearing beginningin August 22, 1977 on proposed 1978 regulations for taking marine mammals incidental to commercial
fishing for tuna. Docket No. MMPAH-1-1977. pp. 41-49 In: Southwest Fisheries Center Staff.
Prepared testimony submitted by SWFC staff at hearing to consider the amendment of regulations
governing incidental taking of marine mammals in the course of commercial fishing operations, Aug.
22-29, 1977, San Diego. SWFC Admin. Rep. LJ-77-27. 199 pp.
GILL, T., 1865. On two species of Delphinidae, from California, in the Smithsonian Institution. Proc.
Acad•. Nat. Sci. Phil. 17: 177-178.
HALL, J. D., 1979. A survey of cetaceans of Prince William Sound and adjacent vicinity-their numbers
and seasonal movements. Envir. Assess. Alaskan Continental Shelf, Final Reports, Biological Studies
6: 631-726.
HALL,]. D. and M. F. TILLMAN, 1977. A survey of cetaceans of Prince William Sound and adjacent vcinitytheir numbers and seasonal movements. Envir. Assess. Alaskan Continental Shelf, Annual Reports 1:
681-708.
HoLT, R. S. and]. E. PowERs, 1982. Abundance estimation of dolphin stocks involved in the eastern tropical Pacific yellowfin tuna fishery determined from aerial and shipboard surveys. NOAA-TM-NMESSWFC-23.
HUBBS, C. L., 1961. The marine vertebrates of the outer coast. Syst. Z,ool. 9 (3-4): 134-147.
joNEs, R. E., 1981. Food habits of smaller marine mammals from northern California. Proc. Calij. Adad.
Sci. 42 (16): 409-433.
KAJIMuRA, H., C. H. Fiscus and R. K. STROUD, 1980. Food of the Pacific white-sided dolphin Lagerwrhynchus obliquidens, Dall's porpoise, Phocoenoides dalli, and northern fur seal, Callorhinus ursinus, off California and Washington; with appendices on size and food of Dall's porpoise from Alaskan waters.
NOAA Techn. Memor., NMFS, F/NWC-2. 30 pp.
KURODA, N., 1953. (Japanese mammals.) Sogen-sha. 177 pp. (In Japanese).
LEATHERWOOD, S., 1974. A note on gray whale behavioral interactions with other marine mammals.
Mar. Fish. Rev. 36 (4): 50-51.
LEATHERWOOD, S., 1978. Verifying accuracy of marine mammal identification in tuna-porpoise observers
logs; a manual for data editors. (Unpubl. contract report, NOSC, purch. order 01-7-208-13970).
36pp.+12figs+1 table.
LEATHERWOOD, S. (editor), 1983. Marine mammals of the eastern Bering Sea; Results of aerial surveys
March 1982-March 1983. Final Report to NOAA, OMPA, Juneau Alaska on contract NA82RAC-

00039.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

156

LEATHERWOOD, REEVES, BOWLES, STEWART AND GOODRICH

LEATHERWOOD, S., W. E. EVANS and D. W. RICE, 1972. Whales, dolphins and porpoises of the eastern North
Pacific: a guide to theirirkntification in the water. NUC TP-282. 176 pp.
LEATHERWOOD, S., W. F. PERRIN, V. L. KIRBY, C. L. HUBBS and M. E. DAHLHEIM., 1980. Distribution
and movements of Risso's dolphin, Grampus griseus, in the eastern North Pacific. Fish. Bull. 77 (4):951-963.
LEATHERWOOD, S. and R.R. REEVES, 1978. Porpoises and dolphins. pp. 96-111 In: D. Haley (ed.).
Marine mammals of eastern North Pacific and Arctic waters. Pacific Search Press, Seattle. 256 pp.
LEATHERWOOD, S, R.R. REEVES, W. F. Perrin and W. E. Evans, 1982. Whales, dolphins, and porpoises of theeastern North Pacific and Arctic adjecent waters; a guide to their identification. NOAA Techn. Rep. NMFS
Gire. 444. 245 pp.
LEATHERWOOD, S. and W. A. WALKER, 1979. The northern right whale dolphin, Lissodelphis borealis Peale,in the eastern North Pacific. pp. 85-141 In: H. E. Winn and B. L. Olla (eds). Behavior ef marine animals, current perspectives in research, Vol. 3: Cetaeeans. Plenum Press, New York. 438 pp.
MITCHELL, E. (ed.), 1975. Review of biology and fisheries for smaller cetaceans. Report and papers
from a meeting of the Subcommittee on Smaller Cetaceans, International Whaling Commission, in
Montreal, April 1-11, 1974. J. Fish. Res. Board Can. 32 (7): 887-983.
NrsHIWAKI, M., 1967. Distribution and migration of marine mammals in the North Pacific area. Bull.
Ocean. Res. Inst., Univ. Tokyo 1: 1-64.
NrsHIWAKI, M., 1972. General biology. pp. 3-204 In: S. H. Ridgway (ed.). Mammals of the sea: biolog;•
and medicine. Charles C Thomas, Springfield, IL. 812 pp.
NORRIS, K. S. and J. H. PRESCOTT, 1961. Observations on Pacific cetaceans of Californian and Mexican
waters. Univ. Calij. Puhl. ,<:,ool. 63 (4): 291-402.
OKADA, Y. and T. HANAOKA, 1939. A study of Japanese Delphinidae (III). Lagenorhynchus obliquidens Gill.
"Kama-iruka ". Sci. Rep. Tokyo Bunrika Daigaku, Sect. B. 4 (72): 139-157 +3 plates.
OWEN, R. W., jR., 1974. Distribution of primary production plant pigments and secchi depth in the California current region, 1969. CalCOFI Atlas 20: xi-xiv+charts 98-117.
PIKE, G. C., 1956. Guide to whales, porpoises and dolphins of the northeast Pacific and Arctic waters of
Canada and Alaska. Fish. Res. Board Can. Gire. 32. 14 pp.
PIKE, G. C., 1960. Pacific striped dolphin, Lagenorhynchus obliquidens, off the coast of British Columbia. J.
Fish. Res. Board Can. 17 (1): 123-124.
PIKE, G. C. and I. B. MAcAsKIE, 1969. Marine mammals of British Columbia. Bull. Fish. Res. Board Can.
171: 1-54.
PoWERS, J.E. and E. G. BARHAM, 1977. Aerial survey of porpoise populations in the eastern tropical Pacific: analytical procedures and results. p. 12 In: Proceedings (Abstracts): 2nd Conference on the
Biology of Marine Mammals, Dec. 12-15, 1977, San Diego. 88 pp.
REEVES, R.R. and S. LEATHERWOOD, 1984. Live-capture fisheries for cetaceans in U.S. and Canadianwaters, 1973-1982. Rep. int. Whal Commn. 34 (in press).
RrcE, D. W., 1963a. Pacific coast whaling and whale research. Trans. N. Amer. Wild!. Natur. Resource
Conf., 28: 327-335.
RrcE, D. W., 1963b. The whale marking cruise of the Sioux City off California and Baja California.
Norsk Hvalfangst-Tid. 6: 153-160.
RICE, D. W., 1974. Whales and whale research in the eastern North Pacific. pp. 170-195 In: W. E.
Schevill (ed.). The whale problem; a status report. Harvard Univ. Press, Cambridge. 419 pp.
ScAMMON, C. M., 1874. The marine mammals of the north-western coast of North American together with an accountof the American whale-fishery. J. H. Carmany & Co., San Francisco. (Dover Pub!., Inc., New York.
1968. 319 pp.).
SCHEFFER, V. B., 1950. The striped dolphin, Lagenorhynchus obliquidens Gill 1865, on the coast of North
America. Amer. Midl. Nat. 44 (3): 750-758.
SCHEFFER, V. B. and J. W. SLIPP, 1948. The whales and dolphins of Washington state with a key to thecetaceans of the west coast of North America. Amer. Midl. Nat. 39 (2): 257-337.
SLEPTSOV, M. M., 1961. Observations of small cetaceans in far eastern seas and northwest Pacific. Trudy
Instituta Mosfologii Z,hivotnykh 34: 136-143.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

PACIFIC WHITE-SIDED DOLPHIN

157

SMITH, T. D., 1975. Estimates of sizes of two populations of porpoises (Stenella) in the eastern tropical Pacific Ocean. SWFC Admin. Rep. LJ-75-67. 55 pp.
STROUD, R. K., C. H. Fiscus and H. KAJIMURA, 1981. Food of the Pacific white-sided dolphin, Lagenorhychus obliquidens, Dall's porpoise, Phocoenoides dalli, and northern fur seal, CallorMnus ursinus, off California
and Washington. Fish. Bull. 78 (4): 951-959.
ToMILIN, A. G., 1957. Mammals of the U.S.S.R. and adjacent countries, Vol. IX, Cetacea. 717 pp. (Translation:
Israel Prag. Sci. Trans., Jerusalem, 1967.
TRUE, F. W., 1889. Contributions to the natural history of the cetaceans; a review of the family Delphinidae. U.S. Natl Mus. Bull. 36: 1-191+47 plates.
U.S. Department of Commerce, 1981. The Marine Mammal Protection Act of 1972; Annual Report April
1, 1980 to March 31, 1981. NOAA/NMFS. 143 pp.
WAHL, J. R., 1977. Sight records of some marine mammals offshore from Westport, Washington. Murrelet 58 (1): 21-23.
WALKER, W. A., 1975. Review of the live-capture fishery for smaller cetaceans taken in Southern California waters for public display, 1966-73. J. Fish. Res. Board Can. 32 (7): 1197-1211.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SECOND RECORD OF SPECTACLED PORPOISE
FROM SUBANTARCTIC SOUTHWEST PACIFIC
R. EWAN FORDYCE
Department of Geology, University of Otago, P, 0. Box 56,
Dunedin, New Zealand

ROBERT H. MATTLIN
Fisheries Research Division, Ministry of Agriculture and Fisheries,
P. 0. Box 297, Wellington, New Zealand

JOAN M. DIXON
National Museum of Victoria, 285-321 Russell Street,
Melbourne, Victoria 3000, Australia

ABSTRACTAn incomplete skull of unknown sex of a sub-adult spectacled porpoise(Phocoena dioptrica Lahille, 1912) was collected at Macquarie Island (54°30'S,
159°00'E) in July 1957. Cranial measurements are given, and the specimen
is compared with other phocoenids. This is the second specimen of P. dioptrica
reported from the subantarctic southwest Pacific, and this record adds support to the suggestion that the species may have a circumpolar distribution insubantarctic latitudes.
INTRODUCTION

The spectacled porpoise (Phocoena dioptrica Lahille, 1912) is a little-studied austral
species of the Family Phocoenidae. It is known primarily on the basis of specimens from the southwest Atlantic Ocean (Brownell, 1975), particularly Tierra delFuego (Goodall, 1978; Goodall and Cameron, 1979). Hitherto, the only specimen collected outside South American waters was National Museum of New
Zealand (NMNZ) Mal670, from Auckland Islands, southwest Pacific (Baker,
1977). The species apparently has been sighted alive near New Zealand (Cawthorn, 1977), and possibly Kerguelen (Frost and Best, 1976). Here we report details of a second specimen of P. dioptrica from the subantarctic southwest Pacific.
DESCRIPTION OF SPECIMEN

The specimen is an incomplete skull (Plates I and II, Figs 1-4) of unknown sex,
collection number Cl0323, in the National Museum of Victoria (NMV), Melbourne,
Victoria, Australia. It was collected at Aerial Cove, Cataline Point, Macquarie
Island (latitude 54°30'S, longitude 159°00'E) by S. Csordas (Australian National
Antarctic Research Expedition) on 24 July 1957. The skull is damaged, and lacks
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 159-164

160

FORDYCE, MATTLIN AND DIXONTABLE 1.

CRANIAL MEASUREMENTS OF PHOCOENA DIOPTRICA,NMV Cl0323, TO NEAREST MILLIMETRE

Measurement

Millimetres

Condylobasal length
Length of rostrum
Width of rostrum at baseWidth of rostrum at mid-length
Width of premaxillae at mid-length
Width of rostrum at 60 mm anterior to rostrum baseWidth of rostrum at three-quarters length, measured from posterior end
Distance from tip of rostrum to external nares
Distance from tip of rostrum to broken anterior border of right internal naris
Preorbital width at level of most ventrally-produced portion of frontal
Supraorbital width, level with anterior border of right external naris
Greatest postorbital widthGreatest width of external nares (immediately posterior to broken tips ofpremaxillae)
Greatest width of premaxillae (level with anterior edge of right external naris)
Greatest parietal width (at parietal-squamosal-exoccipital suture)
Vertical external height of braincase from mid-line of basisphenoid to summitof supraoccipitalInternal length of braincase from hindmost limit of condyles to foremost limitof cranial cavity along mid-line
Greatest length of left temporal fossa
Minor diameter of left temporal fossa
Projection of premaxillae beyond maxillae at tip of rostrum
Distance from foremost end of junction between nasals to estimated hindmost
point of margin of supraoccipital crest
Length of right orbit, from most ventrally produced preorbital portion of frontal
to broken anterior edge of postorbital process
Length of antorbital process of right lacrimal
Greatest width of internal nares estimated (width of right internal naris, 28)
Length of upper right alveolar groove
Deviation of skull from symmetry in dorsal view

283
111
81

54
28

52
43
153

154
127
136

159
34

46
138

107

107

>59
30
3

41
45
32

56
89
ea. 4 degrees

teeth, posterior ends of the premaxillae, part of the left supraorbital process of thefrontal, the apices of both postorbital processes, lateral portions of the supraoccipital,
both squamosals, all but a fragment ofleft pterygoid, the hamulus and outer lamina
ofright pterygoid, and the left and partial right paroccipital processes. The vertex
and the apices of the rostrum and right supraorbital process are abraded. The
specimen exhibits no noteworthy differences from previously described individualsof P. dioptrica.
The absolute age of the specimen cannot be determined, as teeth, which might
exhibit incremental growth lines, are absent. Other cranial features suggest thatthe animal is sub-adult. Traces of the frontoparietal suture remain, and the basisphenoid-presphenoid suture was not fused, which suggest immaturity, but the fusion of interparietal and parietal indicates that the specimen is at least older thanthe equivalent of age-class III of Stenella attenuata as defined by Perrin (1975).
Measurements of NMV 010323 (after Perrin, 1975: Table 2) to the nearest
1 mm are given in Table 1.
Sci. Rep. Whales Res. Ints.,
No. 35, 1981:

SPECTACLED PORPOISE FROM SOUTHWEST PACIFIC

161

DISCUSSION

Extant species of phocoenid are generally differentiated on the basis of external
morphology, and the only comparative description of the skulls of species of Phocoenathat we are aware of is that of Norris and McFarland (1958). Only two phocoenid
skulls (P. phocoena, NMV C24749; P. dioptrica, NMNZ Mal670) were available tous for comparison with the Macquarie Island specimen. Thus, we base our identification of NMV C10323 primarily on descriptions and/or illustrations of phocoenid
skulls given by Norris and McFarland (1958), and other authors, as follows:
Phocoena phocoena, Hamilton (1941), Norris and McFarland (1958), Van Bree et al.
(1977); P. dioptrica, Marelli (1922), Hamilton (1941), Praderi (1971), Brownell(1975), Baker (1977), Goodall (1978), Goodall and Cameron (1979); P. sinus,
Norris and McFarland (1958); P. spinipinnis, Allen (1925), Praderi (1971 ), Goodall(1978); Phocoenoides dalli, True (1885), Andrews (1911), Miller (1930); and Neophocaena phocaenoides, Allen (1923), Shaw (1938), Pilleri and Gihr (1975).
On the basis of information provided in the above literature, it appears that
adult specimens of P. dioptrica differ from those of P. phocoena, P. sinus, and P.
spinipinnis in that the dorsal surfaces of the rostrum and supraoccipital are in thesame plane, the dorsal surface of the rostrum is more flattened, the premaxillae
are elevated less above the maxillae, the dorsal and ventral surfaces of the rostrum
are more nearly parallel, the apex of the rostrum is attenuated more abruptly(dorsal and lateral views), the face slopes more steeply from the vertex to the external nares (note vertex wear in Cl0323), and particularly from the vertex to thenasal tubercules, the nasals are placed more ventrally, the vertex is longer, thepostorbital portion of the cranium and temporal fossa are shorter and deeper, thepostorbital process of the frontal is more robust and has an elongate base, the zygomatic processes are exposed less in dorsal view, and the teeth are smaller, andmore loosely inserted in less prominent alveolar grooves. P. dioptrica differs also
from P. phocoena in its longer, broader skull, and convex maxillary portion of thepalate, and from P. sinus in the larger skull, posterior margin of palate with broad
W shape indentation, convex maxillary portion of the palate, and relatively less exposure of frontal on the dorsolateral portion of braincase.
Phocoena dioptrica appears to differ from Neophocaena phocaenoides in all cranialfeatures listed above except possibly the structure of the postorbital and zygomatic
process. Also, the skull of P. dioptrica is relatively larger, the rostrum is relatively
longer, and the rostrum is bent less relative to the basicranial axis. Cranial clifferences between Phocoena dioptrica and Phocoenoides da!li are not clear from a perusalof literature, and these species appear to be similar in that, for example, the dorsal
surfaces of the rostrum and flat-topped supraoccipital are in the same plane, thedorsal surface of the rostrum is relatively flat, the face slopes steeply from the vertex to the external nares (noted by Brownell, 1975; although in the specimen of
Phocoenoides dalli figured by Miller 1930, this appears more shallow), the nasals areplaced relatively ventrally, the postorbital process is robust with a relatively long
base, the zygomatic process is poorly exposed to dorsal view, and the teeth are
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

162

FORDYCE, MATTLIN AND DIXON

relatively small, and inserted in a poorly developed alveolar groove. The main
cranial differences between these species (discerned from published figures) appear
to be that the postorbital part of the cranium and the temporal fossae are relatively
shorter and deeper in P. dioptrica. The postcranial skeletons of Phocoena dioptrica
and Phocoenoides dalli are, however, very different (compare Brownell, 1975: fig. I
and Goodall and Cameron, 1979: fig. 5, with Miller, 1930: plate I). Phocoena
dioptrica is similar to other species of Phocoena while Phocoenoides dalli possesses verytall, anteroposteriorly narrow neural spines with reduced zygapophyses and anteroposteriorly narrow centra.
We identify NMV Cl0323 as Phocoena dioptrica because it exhibits features
which can be used to separate positively-identified specimens of P. dioptrica fromother species of phocoenid. However, limited information on the comparative
cranial osteology of phocoenids, as well as our limited access to specimens, makes
the above comparisons provisional and the former indicates the need for a generalreview of phocoenid osteology.
The Macquarie Island record, which is only the second positive occurrence
outside southern South American waters, certainly indicates that P. dioptrica has awider distribution than was known only a few years ago (e.g. Brownell, 1975).
This record, and sightings apparently of P. dioptrica near New Zealand (Cawthorn,1977) and Kerguelen (Frost and Best, 1976), support Barker's (1977) suggestionthat the species may have a circumpolar distribution in subantarctic latitudes. Undoubtedly, much new information on the species will result from the recent workof Goodall (1978; Goodall and Cameron, 1979) in Tierra del Fuego. Whereas
Brownell (1975) observed that only ten occurrences then were known of P. dioptrica, Goodall (1978) listed 112 specimens, and mentioned another 29, from Tierradel Fuego alone. These beach collections suggest that the spectacled porpoise is
the most common small cetacean in inshore waters around Tierra del Fuego, but
the absence of sightings of live animals even in areas of high stranding densities
attests to the cryptic behaviour of the species. It is likely that strandings, rather
than sightings of live animals, will constitute further records of the species from thesubantarctic southwest Pacific and, in view of the northward distribution of the
porpoise into temperate South American waters (Brownell, 1975), strandings might
be expected in New Zealand.
ACKNOWLEDGEMENTS

We thank Alan Baker and Martin Cawthorn for discussion, and James G. Meadfor reading the manuscript. R. E. Fordyce's contribution was produced during
the tenure of a postdoctoral fellowship in the Department of Earth Sciences, Monash
University, Clayton, Victoria, with the assistance of facilities of the National Museum of Victoria, Melbourne, Victoria, Australia.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

SPECTACLED PORPOISE FROM SOUTHWEST PACIFIC163

REFERENCES
ALLEN, G. M., 1923. The black finless porpoise Neomeris. Bull. Jov!us. Comp. Zool., 65: 233-256.
ALLEN, G. M., 1925. Burmeister's porpoise (Phocaena spinipinnis). Bull. Mus. Comp. Zool., 67: 251-261.
ANDREWS, R. C., 1911. A new porpoise from Japan. Bull. Amer. Mus. Nat. Hist., 30: 31-51.
BAKER, A. N., 1977. Spectacled porpoise, Phocoena dioptrica, new to the Subantarctic Pacific Ocean. N.z.J.
Mar. Freshw. Res., I I: 401-406.
BROWNELL, R. L., 1975. Phocoena dioptrica. Mamm. species, 66: 1-3.
CAWTHORN, M., 1977. Whale identification (guide for New Zealand whales). Mimeo (not seen; cited by Goodall, 1978).
FROST, P.G.M., and P. B. BEST 1976. Design and application of a coded format for recording observationsof cetaceans at sea. S. Afr. J. Antarct. Res., 6: 9-14.
GooDALL, R.N.P., 1978. Report on the small cetaceans stranded on the coasts of Tierra de! Fuego. Sci.
Rep. Whales Res. Inst., 30: 197-230.
GooDALL, R.N.P., and I. S. CAMERON, 1979. Phocoena dioptrica, una nueva especie para aguas Chilenas.
Rev. Mus. Arg. Cienc. Nat., Buenos Aires, :(ool., 12: 143-152.
HAMILTON, J.E., 1941. A rare porpoise of the South Atlantic, Phocaena dioptrica (Lahille, 1912). Discovery
Rep., 21: 227-234.
LAHILLE F., 1912. Nota preliminar sobre una nueva especie de Marsopa de! Rio de La Plata. An. Mus.
Hist. Nat., Buenos Aires, 23: 269-278.
MARELLI, C. A., 1922. Phocaena stornii sp. n., una especie de marsopa de! mar austral Argentino. An. Soc.
Cient. Argent., 94: 229-240.
MILLER, G. S., 1930. A note on the skeletons of two Alaskan porpoises. Smiths. Misc. Coll., 82 (13): 1-2.
NoRRis, K. S., and W. N. McFARLAND, 1958. A new harbor porpoise of the genus Phocoena from the Gulf
of California. J. Mamm., 39: 22-39.
PERRIN, W. F., 1975. Variation of spotted and spinner porpoise (Genus Stenella) in the Eastern Tropical
Pacific and Hawaii. Bull. Scripps Inst. Oceanogr., 21: 1-206.
PrLLERI, G., and M. GrnR, 1975. On the taxonomy and ecology of the finless black porpoise, Neophocaena(Cetacea, De!phinidae). Mammalia, 39: 657-673.
PRADERI, R., 1971. Contribucion al conocimiento de! genero "Phocoena (Cetacea, Phocoenidae) ". Rev.
Mus. Arg. Cienc. Nat., Buenos Aires, Zool., 7: 251-266.
SHAW, T. H., 1938. The skull of Chinese finless porpoise. Bull. Fan. Inst. Biol. Peking, Zool., 8: 373-385.
TRUE, F. W., 1885. On a new species of porpoise, Phocaena dalli, from Alaska. Proc. U.S. Nat. Mus., 8:
95-98.
VAN BREE, P.J.H., D. E. SERGEANT, and W. HOEK, 1977. A harbour porpoise Phocoena phocoena (Linnaeus,
1758), from the Mackenzie River delta, Northwest Territories, Canada (Notes on Cetacea, Delphinoides
VIII). Beaufortia, 26: 99-105.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

164

FORDYCE, MATTLIN AND DIXONEXPLANATION OF PLATESPLATES I AND II
Skull of Phocoena dioptrica, NMV C10323.
Fig. 1. Dorsal view.
Fig. 2. Left lateral view.
Fig. 3. Anterior view.
Fig. 4. Ventral view.

Skull length 283 mm.

Sci. Rep. Whales Res. Inst.,

No. 35, 1984

f
l
l
O
￡ ・
6T＇
f8

S
'
!
ysa1011111 ・t/•y .
as／SU/ ‑
・zz·.S！ ~T
;
・

T
.
c
!
S
1・
・

0入mIOJfヨ¥VJ
τーLL
G α KV KT
トO XI
；

Vld
U.
'
I.

FORDYCE,~ l ATTLIN AND DIX ON

1PLATE 1

.
.3
g
i
F

.
.4
g
i
F
,
.
t
s
n
.I
s
sRe
e
l
a
t
/
V
.I
>
/
.Re
i
c
S

4
8
9
,1
5
No.3

A MORPHOLOGICAL NOTE ON THE INTESTINE OF
THE BOUTU WITH EMPHASIS ON ITS LENGTH AND!LEO-COLIC TRANSITION COMPARED WITH
OTHER PLATANISTIDSFUSAO YAMASAKI AND KENJI KITO
Department of Biology, Sapporo Medical College, Sapporo

ABSTRACTThe intestine of the Boutu, Inia geoffrensis (body length 204 cm, female),
was examined macroscopically and light microscopically. The intestine of
the Inia examined was grossly divided into three portions: the small intestine,
the smooth-walled portion, and the colon. The lengths of these parts wereapproximately 4150 cm, 80 cm, and 40 cm, respectively. The total intestinal
length of the lnia, including the 5 cm long rectum and 3 cm long anal canal,
was 4278 cm. Therefore, the intestine was nearly 21 times as long as the
body length. In the interior of the small intestine, except for the proximal
half of the duodenum, a single distinct longitudinal fold involving both themucosa and submucosa could be seen. The smooth-walled portion was thicker
than the small intestine, and had no fold, but its inner surface became fiat andsmooth. The colon, which had several longitudinal folds in its interior, wasthinner than the smooth-walled portion in the initial one-third and thicker
in the remaining portion. Histological differences between the small intestineand the smooth-walled portion and the colon could not be clearly distinguished in our specimen, except for the abundance of goblet cells in the latter
two portions. The ileo-colic transition of the lnia observed was unclear andthis region was compared with other kinds of platanistids.
INTRODUCTION

Morphological investigation of the internal organs, as well as of other body features,is very important in order to clarify the phylogenetic relationship among the fresh
water dolphins of the family Platanistidae, Platanista, Pontoporia, Lipotes, and Inia.
Concerning the morphology of the intestine, there are some observations previously
reported on Platanista (Anderson, 1879; Slijper, 1962/1979; Takahashi and Yamasaki, 1972), Pontoporia (Burmeister, 1869; Yamasaki, Takahashi and Kamiya, 1975),
Lipotes (Chen and Chen, 197 5; Zhou and Li, 1981 ), and Inia (Zhou, Li and Pilleri,1982). However, our morphological knowledge of the Inia's intestine is still insufficient because the investigation by Zhou et al. (1982) treated only Inia boliviensis,
and no detailed description on the intestine of Jnia geojfrensis has so far been reported except for a partial reference to the morphology of the intestine (Yamasaki
et al., 1975). The present paper, as the second report on the morphological study
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 165-172

166

YAMASAKI AND KITO

of the digestive tract of I. ge~ffrensis (cf. Yamasaki and Kamiya, 1981, on the stomach), deals with the macroscopical characteristics of the intestine, some of whichwere not observed by Zhou et al. (1982) in I. boliviensis, and discusses the intestinal
length and the ileo-colic transition as compared with other platanistids.
MATERIAL AND METHODS

The intestine of the Bou tu (Amazonian dolphin), Inia geoffrensis (body length 204 cm,
female) used for this study was provided by the Kamogawa Sea World, Chiba,
Japan, after death from unidentified disease. The intestine taken from the abdominal cavity was preserved in 10% formalin solution and transported to ourlaboratory. After macroscopical observations, small pieces for the light microscopy were taken from several parts of the intestine, and were embedded in paraffin.
Sections were stained with hematoxylin and eosin.
OBSERVATIONS (PLATE I AND II)

The intestine of I. geojfrensis was observed to be grossly divided into three portions:the small intestine, the colon, and the portion which was located between thesetwo. The intermediate portion was thicker than the small intestine and was alsocharacterized by its smooth interior. It was difficult to determine whether thisportion belonged to the last part of the small intestine or the initial part of thelarge intestine; therefore, for convenience, we called it a "smooth-walled portion"of the intestine in this study.
The initial part of the small intestine, the duodenum, consisted of the duodenal ampulla and the duodenum proper. The former was continuous with thepyloric stomach with a small opening 2 mm in diameter. It was funnel-shaped,
approximately 2.5 cm in diameter at the widest proximal part, about 3 cm in length,
and continued to the duodenum proper. The hepato-pancreatic duct opened in
the duodenal lumen about 9 cm away from the commencement of the duodenum
proper and formed a distinct plica longitudinalis duodeni about 1.5 cm long and0.6 cm wide. Although the border between the duodenum and the jejunum was
unclear, and fairly difficult to determine, the length of the duodenum proper appeared to be roughly 20 cm. The small intestine, except for the proximal half ofthe duodenum, formed a number of coiled loops suspended by a broad mesentery,which was 7-12 cm in width. The small intestine was approximately 0.7-0.8 cm
in diameter but in several parts there was a slight dilation, about 1 cm in diameter,
extending over a length of about 5-10 cm. The length of the small intestine, fromthe initial part of the duodenum to the beginning of the smooth-walled portion,measured nearly 4,150 cm. No circular folds could be seen in the interior of any
parts of the small intestine. The inner surface of the duodenal ampulla exhibitedseveral folds, which might be not present in the living state, being slightly irregular;
and at about 5 cm from the opening of the hepato-pancreatic duct one single distinct
longitudinal fold began and continued throughout almost the whole interior of theSci. Rep. Whales Res. Inst.,
No. 35, 1984INTESTINE OF INIA GEOFFRENSJS

167

small intestine (Fig. 1). This single fold projected into the intestinal lumen beyond a half diameter of the lumen and was generally found on the antimesentericborder (Fig. 6). The fold became slightly smaller and irregular in the several
dilated parts of the small intestine mentioned above, and also near the smoothwalled portion (Fig. 2). The smooth-walled portion of the intestine measured
about 80 cm long. This portion, about 1 cm or more in diameter, was clearly
thicker than the small intestine. The longitudinal folds could not be seen in thisportion and the inner surface became flat and smooth (Fig. 3). However, from
one to three short longitudinal folds, 2-5 cm long, were seen in some places of thisportion. The smooth-walled portion formed an intestinal loop but its mesentery
was shorter than in the small intestine. The vessels in the mesentery made an
acade and many vasa recta reached the smooth-walled portion as seen in the small
intestine, though this pattern tended to become irregular in the distal part. The
last part of this portion ran upwards and flexed dorsal, and continued to the nextcolon.
The colon descended straightly and continued to the rectum. The mesenteryof the colon was short, about 5-6 cm wide, and gradually reduced in width analwards, disappearing in the anal part. The initial one-third of the colon was somewhat thinner than the smooth-walled portion, with a width of approximately 1 cm
or less, and the last two-thirds became thicker, being about 1.5 cm in diameter. In
the interior of the colon there could be seen from two to five distinct folds runninglongitudinally (Fig. 4 ), which became more marked in the last two-thirds (Fig. 5 ).
These folds were broader than those in the small intestine. Most folds continued
throughout the entire length of the colon, but short ones, 2-3 cm long, were present
in some places. The colon was approximately 40 cm long, and the rectum andthe anal canal were 5 cm and 3 cm long, respectively.
The thickness of the mucosa of the duodenal ampulla was 0.6-0.7 mm, andthat of the rest was slightly thinner, being 0.4-0.5 mm in thickness. Since thespecimen observed was in poor condition for histological examinations, typical villi
could not be clearly observed in the small intestine (Fig. 7) and it could not be
determined whether villi were present or not in the smooth-walled portion (Fig. 8).
Intestinal glands were mucous in the duodenal ampulla. Those of the rest of theintestine morphologically resembled each other. But the glands of the smoothwalled portion and colon showed some tertuous courses and goblet cells became
abundant, especially in the bottom of the glands (Figs 8-10). Musclaris of thewhole intestine, consisting of thick inner circular and thin outer longitudinal layers,
was 0.3-0.5 mm thick in the small intestine (Fig. 6) and smooth-walled portion,and 0.5-0.8 mm thick in the colon. The inner muscular layer was 4-5 times as
thick as the outer one. The sphincteric structure could not be seen at either theborder between the small intestine and the smooth-walled portion or between thisportion and the colon. The folds observed in the whole intestinal tract involved
both the mucosa and the submucosa (Fig. 6). Some accumulations of lymphoidtissue were found in the lamina propria of the colon but well-developed lymphatic
nodules could not be seen in any portion of the intestinal tract of the observed
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

168

YAMASAKI AND KITO

specimen.
DISCUSSION

The total length of the whole intestine of the I. geojfrensis (body length 204 cm) was
4,278 cm; thus the ratio of the intestinal length to the body length is nearly 21 to 1.
This agrees well with the ratios, 19 and 20 to 1, obtained in I. boliviensis (bodylengths 145 cm and 174 cm, respectively, Zhou et al., 1982). The ratios in otherfresh water dolphins reported by previous investigators are shown in Table 1 *.
Platanista's ratio is notably low and Pontoporia's is higher by far than that of otherdolphins. Since there appears to be a tendency for the intestinal length to increase
with age in our collected specimens of Platanista and Pontoporia (cf. Takahashi andYamasaki, 1972; Yamasaki et al., 1975), the ratio becomes slightly higher when
specimens are limited to adults.
TABLE I.
SpeciesInia
bo!iviensis
geoffrensis
Platanista
gangetica

THE RATIO OF THE INTESTINAL LENGTH TO THE
BODY LENGTH IN PLATANISTIDS
Ratio

19.0-20.0
21.0

Zhou et al. (1982)
Yamasaki et al. (1975) and present study (1983)

4.1-4.4
7.3

Anderson (1879)
Slijper (1962/1979), no descriptions on the length of bodyand intestine
Takahashi & Yamasaki (1972)

3.6-4.9

Pontoporia
blainvillei

Lipotes
vexillifer

Authors and Remarks

32.0
24.0-37.0

Burmeister (1869)
Yamasaki et al. (1975), examined in unfixed state in most
cases

15.0

Chen & Chen (1975), ratio of whole length of the digestiv~ tract, from mouth to anus, to the body length
Zhou & Li (1981)

12.5-14.9

In the small intestine of the Inia observed there are no circular folds, but asingle distinct longitudinal fold projecting into its lumen can be seen as in Pontoporia (Yamasaki et al., 1975). Although Zhou et al. (1982) did not mention thisfold in I. boliviensis, the fold in I. geojfrensis is plainly visible as a permanent structure and can also be easily felt through the wall of the intestine when the intestineis grasped between the fingers. In Platanista, well-developed circular folds are present on the inner surface of the small intestine but the surface of about the last
50 cm of the ileum becomes fiat and smooth, and a distinct longitudinal fold, about
30 cm long, is present at this portion (Takahashi and Yamasaki, 1972). The presence of the circular or longitudinal folds in the small intestine is due to the struc-* The ratios of Platanista, Pontoporia, and Inia misquoted in our previous paper (1981) are corrected as shownin Table 1.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984INTESTINE OF !NIA GEOFFRENSIS

169

tural specializations that serve to increase the area of the surface exposed to thelumen. It is assumed that numerous well-developed circular folds are a much
more effective means of augmenting the surface area of the mucosa than a single
longitudinal fold. This fact may have some relation to the short intestine of Platanista and to the long intestine of lnia and Pontoporia. In the reports of the intestine of Lipotes (Chen and Chen, 1975; Zhou and Li, 1981) there are no macroscopical descriptions of its internal structure, and therefore it is unclear whether
Lipotes' intestine has such longitudinal folds or not.
In cetaceans it is generally known that there is no clear external transition between the small and the large intestines; except for Platanista and mysticetes whichhave a short caecum. In Pontoporia the external appearance of the transition between the small and the large intestines was not so difficult to determine because of
the differences in thickness, the supply of the mesenteric vessels, and the interior
equipped with a single longitudinal fold in the small intestine while there were two
folds in the large intestine (Yamasaki et al., 197 5 ). However, in the case of ourInia, it was very difficult to determine the transition between the small and thelarge intestines. In the smooth-walled portion the single longitudinal fold disappears and the inner surface becomes flat and smooth. Nevertheless, the pattern ofthe blood supply, the vasa recta, seen in the small intestine was observed until the
distal part of the smooth-walled portion. Since our specimen was, unfortunately,in poor condition for histological examination, neither the presence of typical villi,
which is one of the most important characteristic features of the small intestine,
nor the disappearance of the villi in the large intestine could be observed. In addition, other histological findings generally found in each small and large intestinein mammals in general could not be observed, so that we did not confirm thetransition region from the small to the large intestine. However, goblet cells of
the intestinal glands of our lnia were abundantly observed in the smooth-walled
portion and the colon, unlike in the small intestine. This distribution of the goblet
cells in the smooth-walled portion and colon in lnia appears to correspond well tothat in the ascending and descending colons in Pontoporia.
Zhou et al. (1982) did not mention this smooth-walled portion, and they considered the colon to be only the portion, about 35 cm long, which ran caudally
connecting with the rectum, and they described the presence of villi in the small
intestine. The length of the large intestine of Pontoporia was 80 cm or more (Yamasaki et al., 1975) and in Lipotes it is about 100 cm (Zhou and Li, 1981). As the
structure of the intestine of our lnia resembles that of Pontoporia, and probably
Lipotes, rather than that of Platanista, the 35 cm long colon of I. boliviensis seems tobe proportionally too short. Although in our previous paper (Yamasaki et al., 1975)
the smooth-walled portion was considered as ascending colon, there are no conclusive characteristics to determine whether the smooth-walled portion belongs to
the small or the large intestines, as is discussed in this study. In order to clarify
the subject of the ileo-colic transition, it is necessary to investigate cetacean species
having no caecum from comparative morphological viewpoints.
Zhou et al. (1982) observed no goblet cells in the intestinal glands in I. boliviSci. Rep. Whales Res. Inst.,
No. 35, 1984

170

YAMASAKI AND KITO

ensis and also stated that this is one of the characters common to Inia and Platanista.
We found abundant goblet cells in /. geojfrensis, as in Pontoporia and Lipotes (cf.
Yamasaki et al., 1975; Zhou and Li, 1981). Though present, the cells were muchless abundant in Platanista (Takahashi and Yamasaki, 1972). Therefore, the absence of the goblet cells may be peculiar to I. boliviensis among the fresh water dolphins previously reported.
Although well-developed lymphatic nodules in the lamina propria were present from the last part of the ileum to the initial part of the colon in Platanista(Takahashi and Yamasaki, 1972) and in Pontoporia (Yamasaki et al., 197 5 ), development of lymphatic tissues of the intestinal tract was very poor in our Inia. Zhou
et al. (1982) described numerous lymphatic nodules aggregating from the last partof the ileum (probably corresponding to the last part of the smooth-walled portionin our case) to the anal part, and well-developed anal tonsils. Since the anal
tonsils in our Inia were poorly developed (Yamasaki, Komatsu and Kamiya, 1977),
poorly developed lymphatic tissue in the intestinal tract seems due to individual
characteristics; well-developed lymphatic nodules could not be seen anywhere in
the intestinal tract.
Pilleri and Gihr (1977, 1980) and Pilleri, Marcussi and Pilleri (1982) statedthat there were clear morphological and morphometric differences between the
Bolivian and Amazonian Inia, based on the observations of their brains and teeth.
The stomachs of both I. geojfrensis and /. boliviensis quite resemble each other instructure (cf. Yamasaki and Kamiya, 1981; Zhou et al., 1982). However, as mentioned above, there are some remarkable macroscopical differences in their intestines. It remains a problem whether such differences in the intestine were interspecific or not, because the present observations on Inia were based on one case.
Therefore, further observations of this subject, based on the sufficient materials,
should be done in order to compare with each other.
ACKNOWLEDGEMENTS

We wish to thank Dr T. Tobayama, Kamogawa Sea World, Chiba, for kindly supplying the specimen for this study.
REFERENCES
ANDERSON, J., 1879. Anatomical and zoological researches: comprising an account of the zoological results of the two
expeditions to Western Yunnan 1869 and 1875; and a monograph of the two cetacean genera, Platanista and Orcella.
2 vols. Qurritch, London.
BURMEISTER, H., 1869. Pontoporia blainvillii Gray. In: Descripcion de cuatro especies de de!finides de la costa
Argentina en el Ocifano Atltintico. Anal. Mus. Publico Buenos Aires, 1: 384---445.
CHEN, I. and W. CHEN, 1975. Notes on some morphological and anatomical features of the white-flag dolphin, Lipotes vexillifer. Acta Hydrobiol. Sinica, 5: 360-368. (in Chinese with English summary).
PrLLERI, G. and M. GrnR, 1977. Observations on the Bolivian (Inia boliviensis d'ORBIGNY, 1834) and the
Amazonian Bufeo (Inia geoffrensis de BLAINVILLE, 1817) with description of a new subspecies (Iniage~ffrensis humboldtiana). Investigations on cetacea 8: 11-76.
PrLLERI, G. and M. GrnR, 1980. Checklist of the cetacean genera Platanista, Inia, Lipotes, Pontoporia, Sousa
Sci. Rep. Whales Res. Inst.,
No. 35, 1984INTESTINE OF !NIA GEOFFRENSIS

171

and Neophocaena. Investigations on cetacea, 11: 33-36.
P1LLERI, G., G. MARCUZZI and 0. PILLER!, 1982. Speciation in the Platanistoidea. Systematic, zoogeographical and ecological observations on recent species. Investigations on cetacea, 14: 15-46.
SLIJPER, E.J., 1962/1979. Whales. Hutchinson, London. (English translation).
TAKAHASH., K. and F. YAMASAKI, 1972. Digestive tract of Ganges dolphin, Platanista gangetica. II. small
and large intestines. Okajimas Fol. anat.jap., 48: 427-452.
YAMASAKI, F., K. TAKAHASHI and T. KAMIYA, 1975. Digestive tract of La Plata dolphin, Pontoporia blainvillei. II. small and large intestines. Okajimas Fol. anat.jap., 52: 1-26.
YAMASAKI, F., S. KOMATSU and T. KAMIYA, 1977. A comparative morphology of anal tonsils in Platanistidae. Sci. Rep. Whales Res. Inst., 29: 95-100.
YAMASAKI, F. and T. KAMIYA, 1981. The stomach of the Boutu, Inia geoffrensis: comparison with those ofother platanistids. Sci. Rep. Whales Res. Inst., 33: 69-81.
ZHou, K. and Y. LI, 1981. On the intestine of the Baiji, Lipotes vexillifer. Acta :(,ool. Sinica, 27: 248-253. (inChinese with English summary).
ZHou, K., Y. LI and G. PILLER!, 1982. The digestive tract of Inia boliviensis (D'ORBIGNY, 1834). Investigations on cetacea, 13: 125-133.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

172

YAMASAKI AND KITO

EXPLANATION OF PLATESPLATES I AND II
Inner views of several parts of the intestine of Inia geoffrensis (1-5). The intestine is
opened wide to show its interior at the mesenteric border. Figs 1-5, actual size.
Fig. 1. Inner surface of the ileum at about 5 m proximal to the smooth-walled portion. Note that a single distinct longitudinal fold can be seen and no circularfolds are present in the small intestine.
Fig. 2. The transitional part between the small intestine (left) and the smooth-walled
portion (right). The longitudinal fold becomes slightly irregular in the last part ofthe small intestine and the inner surface becomes smooth in the smooth-walled
portion.
Fig. 3. Mid-part of the smooth-walled portion, which is thicker than the small intestine. Short longitudinal folds are seen in some places in this portion.
Fig. 4. The last part of the smooth-walled portion (left) and the initial part of thecolon (right). Two or three longitudinal folds are present in the initial part of thecolon.
Fig. 5. Mid-part of the colon. Marked longitudinal folds can be seen in the surface.
Fig. 6. Cross section of the mid-part of the small intestine. A prominent longitudinalfold, involving both the mucosa and the submucosa, projects into the lumen fromnear the antimesenteric borders. x 11.
Fig. 7-10. Same magnification photomicrographs of the mucosa of the several partsof the intestinal tract. x 10. Mid-part of the small intestine (Fig. 7), mid-part ofthe smooth-walled portion (Fig. 8), initial part of the colon (Fig. 9), and mid-partof the colon (Fig. 10). Typical villi could not be seen in the small intestine in our
specimen. The intestinal glands of the small and the large intestines are rather
straight. Goblet cells become abundant in the smooth-walled portion and thecolon.

Sci. Rep. Whales Res. Inst.,

No. 35, 1984

T.
'
:
l
ムV1d

v

昨961'
f
;
f
i・
0
・

'
'
l
>
U
J・
s
a
y f勾V
I
J
ン
1・
!
f
a
y・
！
＇S

0ムI
予iGN V 1
)
1
¥
'
SVt
吋Vλ

ぬ6！ §
￡・
ON
し1
s
1
1
1・
s
a
l
ls
a
1
m
1
1
M・
!
f
a
l
l.
・
1
3
S

0ムJ)! GNV T:IV
SVWV
人

I
I'
1
.
L¥
rl
d

FIRST DISCOVERY OF A TERTIARY PLATANISTOID
FOSSIL FROM ASIAZHOU KAIYA
Department of Biolog_y, Nanjing Normal College

ZHOU MINGZHEN
Institute of Vertebrate Paleontology and Paleoanthropology

ZHAO ZHONGRU
ivfuseum of Guangxi

ABSTRACTA new genus and species of Lipotidae, Prolipotes yujiangensis collected fromthe bank of Yujiang River and considered roughly as Miocene in age, is thefirst discovery of Platanistoid fossil from Asia. The holotype is a fragment ofmandible with teeth, including posterior part of symphysial portion and initial part of free portion of mandibular rami. Comparison of the new specimen with the mandible of Lipotes and Kampholophos indicates that Prolipotes
yujiangensis is the fossil odontocetes species most closely related to Lipotes known
thus far.

The superfamily Platanistoidea is a declining group consisting four modern
families which are found in areas far away from each other. Lipotidae occurs in
China. Platanistidae is found in the Indian subcontinent. Another two live inSouth America: Iniidae lives in Amazon and Orinoco river basins and Pontoporiidae occurs in coastal central Atlantic waters of South America. In each family only one or two species restricted to very narrow areas are living. Our knowledge concerning the history of the Platanistoids is still scanty. Fossil studies indicate that they were widely distributed in America, Europe and Africa during
Miocene and Pliocene. No Platanistoid fossil from Asia, however, has been reported so far. A fragment of mandible belonging to Lipotidae collected from thebank ofYujiang River in Guiping County, Guangxi in 1981 and considered roughly as Miocene in age is the first discovery of Platanistoid fossil from Asia.
SYSTEMATICS

Order CETACEA Brisson, 1762
Superfami.ly PLATANISTOIDEA Simpson, 1945
Family LIPOTIDAE Zhou, Qi.an et Li., 1978
Prolipotes, new genus
Type species: Prolipotes yujiangensis
Diagnosis: See diagnosis of Prolipotes yujiangensis (generic type).
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 173-181

174

ZHOU, ZHOU AND ZHAO

Prolipotes yujiangensis, new species(Figs 1-3, Plates I-II)
Holotype: A fragment of mandible with teeth, including posterior part of symphysial portion and initial part of free portion of mandibular rami.
Type locality: Bank of Yujiang River 500 m SE of Oucun village in Mengwei
Commune, Guiping County, Guangxi Zhuang Autonomous Region, People's Republic of China. Coordinates of the type locality are 23°l 7'20"N latitude,
110°3'30"E longitude.
Age: The specimen was collected from "Yongning Group" (upper part?) of
Tertiary age. At first the " Yongning Group " was considered to be as new Tertiary (Pliocene ?) in age according to the molluscs discovered. Later the geological age of this Group was revised on the basis of a large number of fossils of reptiles(crocodiles) and mammals found successively from Yongning Group beds or corresponding beds in Baise and Yangle Basins (Tiandong and Tianyang County), assigned Early Tertiary and further determined Late Eocene to Early Oligocene inage (Tang et al., 1974). Our Platanistoid fossil was found from the upper part ofthis Group and is oflater age. Its differences from the extant species are not very
big. The phylogenetic history of the superfamily indicates that they probably
arose at the end of Early Tertiary. At present, in the light of the general stratigraphic condition of the type locality and data for the geohistorical distribution of
Platanistoidea, we suggest that the new specimen is of Miocene age.
Diagnosis: Mandibular symphysis long, its posterior end very thick; deep longitudinal furrow between two tooth rows; anterior part of two rami in shape of acurve where they join symphysial portion; teeth closely spaced; crowns of teeth
slightly compressed antero-posteriorly, their upper half recurved interiorly, cingulum rounded and broad; enamel of crowns ornamented with irregular verticalstriae and ridges; tip of roots not widen to form an anterior and posterior projection.
Description: The mandibular symphysis is very long, its preserved posterior partmeasures 80 mm in length. A deep broad longitudinal furrow extending gently
to the posterior end is found between the two tooth rows of the symphysial portionof the mandible. The posterior end of mandibular symphysis is slightly thinner than
the anterior break (seven teeth from the posterior end of mandibular symphysis ),about half of the height of the lingual side of the anterior end of the free portion of
the ramus. The preserved free portion of the two rami is very short. The anterior part of the two rami is in the shape of a curve where they join the symphysial
portion. The angle between the two lines extending from the anterior end of thetwo rami is about 37.5°. Several mental foramens located below the lst, 3rd and6th-7th teeth respectively before the hind extremity of the mandibular symphysis,
are found at the labial side of the lower jaw.
Additional one is found on the left mandible below the 5th tooth situated before the posterior end of the symphysis. A faint groove runs longitudinally below
the mental foramens near the lower rim of the mandible.
Eight teeth (two broken) and two alveolus are found on the preserved right
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

Fig. 1.

Sci. Rep. Whales Res. Inst.

No. 35, 1981

Prolipotes yujiangensis, holotype, occlusal view of mandible, X 1.5.

175

176

ZHOU, ZHOU AND ZHAOTABLE 1.

MEASUREMENTS (MM) OF MANDIBLE, HOLOTYPE
Left

Right

Length of mandible as preserved
100.0
Length of free portion of ramus as preserved
13.7
Height of labial side of anterior end of ramus
27.0
21.5 1>Height of labial side of anterior break of mandible
Thickness of mandibular symphysis at posterior end
Thickness of mandibular symphysis at anterior breakTransverse diameter of mandible at posterior end of symphysial portion
Transverse diameter of mandible at front edge of the 3rd tooth before
posterior end of symphysis
Transverse diameter of mandible at front edge of the 6th tooth before
post!"rior end of symphysis
Length of tooth row of last six teeth of symphysial portion
57.5
ll

•>

Symphysial
portion

111.6
27.7
27.0
23.8 2 >
15.0
18.3
51.0
40.0
32.0
55.6

Eight teeth from posterior end ofsymphysial portion.
Six teeth from posterior end of symphysial portion.

mandible, of which three are located on the free portion of the ramus. Only thelower half of the anteriormost part of the free portion of the left ramus has beenpreserved and all of the preserved nine teeth (four broken) of the left mandible aresituated on the symphysial portion. The alveoli are transversely elliptical in outline, about 7 mm in antero-posterior and 6 mm in labio-lingual diameter. They
are located on the mid-line of the mandible of the symphysial portion. The position of the three teeth on the anterior part of the free portion of the right ram us isslightly lateral to the lingual side.
The teeth are closely spaced. The intervals are about 3 mm between theanterior teeth and 4 mm between the hinder ones. In the posterior part of thesymphysial portion, there are as an average one tooth per 9.2 mm on the rightmandible and one per 9.6 mm on the left. The crown of the teeth is inclined
labially conspicuously and slightly compressed anterior-posteriorly. Its upper half
is recurved interiorly and places the apices of the mandibular teeth which areslightly worn in an upward direction. The lower half of the lingual side of thecrowns is a broad, rounded cingulum where the largest diameter of the crown cross.
The enamel of the whole crown is ornamented with irregular vertical striae andridges. The bases of the crowns constrict to join the roots. The exposed portion
TABLE 2.

MEASUREMENTS (MM) OF RIGHT MANDIBULAR TEETH, HOLOTYPE
01>

2

3

4

5

Length of labial side of root above alveolus
3.5
3.7
4.2
3.5
3.9
Length of lingual side of root above alveolus
3.1
3.3
3.6
3.6
3.2
3.5
Greatest anteroposterior diameter of exposed portion of root 6.2
6.2
6.0
6.2
6.4
6.5
Greatest labio-lingual diameter of exposed portion of root
5.8
5.9
6.1
6.0
5.9
4.6
Greatest anteroposterior diameter of crown
4.3
4.5
4.5
4.4
4.3
6.3
Greatest labio-lingual diameter of crown
6.3
6.4
6.3
6.2
6.0
7.8
Length of crown
7.8
7.7
7.5
7.4
7.2
1) Counting ahead from the lst tooth behind the symphysis, the Nos. are 0, 1, 2, 3, 4, 5 in proper order.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

177

An
A

8

c
Fig. 2. Lateral view of part of teeth of right mandible, trace over radiographs, x I.
Arrow indicating posterior end of mandibular symphysis. An : anterior.
A. Prolipotes yujiangensis, holotype
B. Lipotes vexillifer, NNC (Nanjing Normal College) 7909
C. Lipotes vexillifer, NNC 7405

of the roots is larger in diameter than the crowns and the anterior-posterior diameter of the former is larger than its labiolingual diameter. The radiograph of themandibular teeth shows that the base of the roots is not widen to form an anterior
and posterior projection.
Comparison: In the Yujiang specimen, the hind part of the mandibular symphysis as preserved is rather long. The intervals between the teeth are relatively
short, as an average there is one per 9.3 mm (right) or 9.6 mm (left) on the hindpart of the mandibular symphysis. The crowns are ornamented with vertical irregular striae and ridges, recurved interiorly and with a well developed cingulumon the lower half. The above mentioned characters resemble those of the Lipotes
vexillifer. Rensberger (1969) has concluded that among the described fossil odontocetes only the Miocene Kampholophos serrulus is related to Lipotes vexillifer. But
the teeth of the former are widely spaced, only one per 21.3 mm on the posterior
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

178

ZHOU, ZHOU AND ZHAO

A~'r;';);~!
fj I,'V-J /
,c;;:; /

·~ ,/

~/

1I '

/f,' ,/I It/
I 1, t

I

I

I

/ ft
lo
"

I

"

i/

f

"

f d
II

I''
I

'I

I

/ ,'I
ff

f

I
I

,I

•I

I

1,

I ,f/;
I
I

If

I

'/

:I

ff

I/

I II
1 ': I:
I

!If
'.I
,,
/J ;Y
I

'

(~--~·1--.__/

I

\

\

\\~Ii
\

\~

\ \\\

\\\,

\)\ \

'\1 \
\

\ \

\,

\
I\ \
I\ I

\I,, \\

..,,

11

\\

I
\

\
I

I'

\

\\

\

q

'

\\•\ \

,.

\

'I

1'

11

I

I

of

"\I

II
I

\I

~

\\

I\_

I

\\ ~
\ \ \

\ t \

\f \

,I

'
\ '-----"..":.;,'-..... ___ ,.,..,..

Fig. 3. Comparison of (A) restored mandible of Prolipotes yujiangensis with (B)mandible of Lipotes vexillifer, about X 1/ 3•

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

179

part of the right mandible. In an old adult of Lipotes vexillifer (NNC 7405), theteeth along the posterior part of symphysial portion are closely spaced, or one per
9.3 mm (right) or 9.8 mm (left). The posteriormost teeth of Kampholophos serrulus
bear a prominent-based accessory cusp which is absent on the anterior teeth.
Their crowns are laterally compressed with vertical striae· and ridges which aremost prominent on the lower two-thirds of each crown. They are coarsest on thelabial and anterior sides (Rensberger, 1969). The structure of all the teeth of
Lipotes vexillifer is alike. The crowns are slight antero-posteriorly compressed withvertical striae and ridges which are most prominent on the upper two-thirds ofeach crown. They are coarsest on the lingual side. Since the differences of theteeth between Kampholophos and Lipotes are more than those between the Yujiang
specimen and Lipotes, it is beyond all doubt that the new specimen is the fossil
odontocetes species which is most closely related to Lipotes known thus far andshould be placed in the family Lipotidae.
Five mandibles of different ages of young and adult of Lipotes (NNC 5601,
7808, 7909, 7907, 7405) were examined for comparison. The longitudinal furrow
between the tooth rows of the symphysial portion is shallow and narrow in theanterior part and descends abruptly to form a valley-like steep depression at about
last 3-4 mm of the posterior end of the mandibular symphysis. The posterior endof the mandibular symphysis is very thin, inferior to half of the thickness of thesymphysis at the 7th tooth before its posterior end (corresponds to the anterior
break of the Yujiang specimen), or less than one-third of the lingual height of thefront end of the free portion of the rami. The anterior part of the two rami is in
the shape of an acute angle where they join the symphysial portion. The verticalstriae and ridges of the crowns are relatively shallow and are fewer at anterior andposterior side. The base of the labial side of the crowns is comparatively smooth.
The tip of the roots widens to form an anterior and posterior projection. On thebasis of the above mentioned differences between the Yujiang specimen and Lipotes,
we therefore proposed to name the former as a new genus and new species.
Because of the paucity of the available material, which is confined to a fragment of lower jaw with corresponding teeth, the finding of the skulls and postcranial skeletons of this new species for the further studies of the characters of thegenus and species is expected.
We thank Wang Zhefu of the Institute of Vertebrate Paleontology and Paleoanthropology for took the photographs and Xu Xinrong of the Nanjing Normal
college for drawings.
REFERENCESBROWNELL, R. L. jR. and E. S. HERALD, 1972. Lipotes vexillifer. Mamm. species, 10: 1-4
FORDYCE, R. E., 1982. A review of Australian fossil cetacea. Mem. Nat. Mus. Viet. 43: 43-58.
GINGERICH, P. D., N. A. WELLS, D. E. RussELL and S. M. IBRAHIM SHAH, 1983. Origin of whales in epicontinental remnant seas: New evidence from the early Eocene of Pakistan. Science, 220 (4595): 403--406.
RENSBERGER, J.M., 1969. A new iniid cetacean from the Miocene of California. Univ. Calif. Puhl. Giol.
Sci., 82: 1-43.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

180

ZHOU, ZHOU AND ZHAOTANG Y., Y. You, Q. Xu, Z. Qru and Y. Hu, 1974. The lower Tertiary of the Baise and Yungle Basins,
Kwangsi. Vertebrata PalAsiatica, 12 (4): 279-293.
ZHou, K., W. QIAN and Y. Lr, 1978. Recent advances in the study of the Baiji, Lipotes vexillifCr. J. Nanjing
Normal Coll. (nat. Sci.), (1): 8-13.
ZHou, K., W. QIAN and Y. Lr, 1979. The osteology and the systematic position of the Baiji, Lipotes vexillifCr.
Acta ,<::,ool. Sinica, 25: 58-7 4.
ZHou, K., 1982. Classification and phylogeny of the superfamily Platanistoidea, with notes on evidence ofthe monophyly of the cetacea. Sci. Rep. whales Res. Inst., 34: 93-108.

Sci. Rep. Whales Res. Inst.,
No. 35, I984

FIRST DISCOVERY OF A TERTIARY PLATANISTOID FOSSIL FROM ASIA

EXPLANATION OF PLATESPLATE I

Prolipotes yujiangensis, holotype, X 1.
A, occlusal view; B, ventral view; C. lateral view.
PLATE II

Prolipotes yujiangensis, holotype, x 3.
lst tooth on the right mandible behind the posterior end of the mandibular symphysis, left,labial view; middle, lingual view; right, posterior view.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

181

I3.LV寸d

f86f'
[
; '
￡
O
J
{
<
f
a
l
l'?3S

・
J
S
l
l[・
S
3
°
HS
3
/
V
l
f
/
1＼・

g

OVHZm、!V O O
HZ'
OOHZ

ド
しATE1
1

ZHOU,ZHOU A
.
:
¥
DZHAO

Sc
i.Re
p.l
l
'
h
a
l
e
sRe
s.i
n
s
t.
,
No.3
5
,1
9
8
4

A PYGMY SPERM WHALE ACCIDENTALLY TAKENBY DRIFT NET IN THE NORTH PACIFICHIDEO OMURA
Whales Research Institute

MIKI SHIRAKIHARA
Shimonoseki-shi, Yamaguchi-ken

HARUKAITO
National Science Museum

A pygmy sperm whale was accidentally taken by drift net called Omenagashi on 1
December 1981 at a position 34°0l'N, l 76°17'E, during an experimental fishing
operation for tunas.
This whale was frozen on the spot and kept in an ice-chamber of about-20°C until towards the end of March of the following year. Then it was transported to Whales Research Institute for identification of the species. On 6 April
1982 we made observation and dissection of the carcass after melting the body.
Dr Toshio Kasuya of the Ocean Research Institute, Dr Nobuyuki Miyazaki of
the National Science Museum and Mr Hidehiro Kato of the WRI have cooperated
in the works. We are very grateful for all of them.
This whale was a femele calf of 1, 731 mm in length. It was said that several
other whales of the same species were concurrently taken. They were larger than
this specimen, but the smallest was selected for the sake of convenience. Thereremains no record of the number, size and sex of these animals, but presumably
included among them the female which was accompanied by the calf.
This whale has a robust body with a small but distinctively shaped head anda narrow tail stock. The tail flukes were cut off on the spot, but they were preserved separately and we could connect them when measuring the body length.
The head is conical viewed from above and also conical viewed in profile (Fig.
1). The forehead overhangs noticeably. The lower jaw is small and narrow,and superficially resembles to a shark's jaw. The dorsal fin is small, falcate, andpositioned behind midback. The flippers are located well forward on the body.
The color of the body is dark gray on the back, shading to lighter gray on the
belly. Between eye and flipper there was present a so-called " bracket mark" or"false gill" on each side of the body (Fig. 2). This mark was first described by
Hubbs (1951) and followed several subsequent authors, e.g. Caldwell et al. (1960),
Hale (1963), Roest (1970) and Ross (1979). It appears to be characteristic of theGenus (Ross, 1979).
Yamada (1954) also noted similar mark was present in two Kogia taken at
Taiji, Ja pan, and in one specimen obtained from Tamashima, Okayama-ken.
This pattern of his specimens, however, different in shape from the " bracket-like "Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 183-193

84
1

A KIHARAANDITOOMURA,SHIR

heimenoft
c
pe
ts
n
e
s
e
epr
h
koft
n
u
r
ewofheadand t
lvi
a
r
e
t
a
yl
l
e
u
q
i
. Obl
.1
g
i
F
e.
m whal
r
e
p
gmys
py

er
t
f
k a
cketmar
a
al br
ic
yp
et
h
howingt
men,s
i
c
pe
ts
n
白 e
hepr
adoft
. He
.2
g
Fi
.
eye

.
e
.
,i
imens
c
e
p
rs
e
h
eo[ot
s
ho
ot
rt
la
i
m
i
tes
i
u
sq
ki
r
sma
hi
no[t
o
i
t
i
s
k. Thepo
r
ma
d
e
t
s
i
s
n
o
sc
nwa
r
te
. Thispat
r
pe
p
i
l
hef
ft
to
n
o
r
nf
eandi
y
ee
h
edbehindt
t
a
oc
sl
ti
i
onand
egi
kr
c
a
l
lb
a
s
r
o
hed
ot
t
n
rupwardsi
o
l
cco
t
i
l'h
a
r
t
en
ev
h
s巴so[t
s
e
oc
r
wop
ft
o
m.
e
h
t
n
e
e
w
t
e
b
d
n
a
l
s
i
k
ac
sformingbl
uh,teoearholngt
it
in
bothpo
.
n
ime
c
e
p
es
s
Japane
e.
h
εoft
n
i
k
r
isma
h
ht
t
swi
al
n no paperde
e
h
et
c
n
i
S
d巴datTokai‑
n
a
r
t
es
rmwhalpe
edapygmys
t
r
o
p
e
1)r
8
9
1
hi(
s
OmuraandTakaha
mur
l
a
c
i
p
y
lyt
r
a
e
l
sc
emarkingi
h
nt
ime
c
pe
ts
n
e
s
e
r
hep
. Int
ed
v
r
e
s
ingwasob
k
r
noma
,
.
t
s
n
s.I
sRe
e
al
t
/
V
.I
i.Rψ
c
S

4
,198
.35
o
N

185

PYGMY SPERM WHALE
TABLE I.

BODY PROPORTION OF THE PRSENT SPECIMEN
Measurements

I.

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.

Tip of snout to notch of flukes (Total length)
Tip of snout to center of eye
Tip of snout to ear
Center of eye to ear
Tip of snout to blowhole
Tip of snout to ant. insertion of flipper
Tip of snout to ant. insertion of dorsal fin
Tip of snout to tip of dorsal fin
Length of gape
Length of blowhole
Width of blowhole
Length of eye
Tip of snout to Ull!bilicus
Tip of snout to midpoint of genital slit
Tip of snout to anus
Projection of snout beyond lower jaw
Half girth on transverse plane at eye
Half girth on transverse plane at axilla
Half girth on transverse plane at ant. insertion of dorsal fin
Half girth on transverse plane at umbilicus
Half girth on transverse plane at anus
Length of flipper, ant. insertion to tip
Length of flipper, axilla to tip
Maximum width of flipper
Width, base of flipper
Height of dorsal fin
Length of dorsal fiin
Width of flukes, tip to tip
Noteh of flukes to tip, right, leftAnterior insertion of flukes to notch
Anterior insertion of flukes to tip(r)in mm% of Total

1,731
215
283
54
185
360
902
1,050
109
15
42
26
859
1, 151
1, 168
69
402
505
556
570
350
275
203
105
123
67
166
444
228
220
183
349

100.0
12.4
16.3
3.1
10.7
20.8
52.1
60.7
6.3
1.0
2.4
1.5
49.6
66.5
67.5
4.0
23.2
29.2
32.1
32.9
20.2
15.9
11. 7
6.1
7 .1
3.9
9.6
25.6
13.2
12.7
10.6
20.2

length" bracket mark" or "false gill" (Fig. 2), but this specimen was obtained from thehigh seas of the North Pacific and not from the coast of Japan. Yamada's opinion(1954) was that "kogiids from the Japanese waters differ to a certain extent fromthose from the American coasts both Pacific and Atlantic." To our regret sincethen this has not been proved or disproved yet.
In Table 1 the body proportions of this specimen and in Table 2 the weights
of various parts of the body are shown. The dorsal fin starts from about midpointof the body and its height is 3.9% of the body length, which is in the ranges of thevalue for K. breviceps given by Ross (1979).
This whale was identified as Kogia breviceps because there was present nocreases on throat, and a falcated dorsal fin was small and situated behind midback
as stated above. Further it had 25 small teeth in all on lower jaw and none on
upper jaw. Later this was confirmed by examination of the skull.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984

OMURA, SHIRAKIHARA AND ITO

186

TABLE 2.

BODY AND ORGAN WEIGHTS OF THE PRESENT SPECIMEN

Item
MuscleBlubber
Bones
Skull
Ribs
Vertebrae
OthersInternal organs
Brain
Heart
SpleenLung
StomachIntestine
Liver
KidneyUterus and ovary
OthersOthers
Total

Weight in gr.

% of the total

32,79531,580
7,050

39.8
38.3
8.5

8,191

9.9

3,845
82.461

3,5
100

1,410
1,350
3,970
320
685
840
22
1, 135
755
1,660
2,330
450
64
250

Skull and postcranial bones were obtained by boiling the carcass about one
month later from the dissection, during which period they were soaked in water.
Skull of this specimen is shown in Fig. 3 and mandibles in Fig. 4. The bones
which consisted of the skull are very loosely fused each other and very easily beseparated. Handley (1966) listed up distinguishing characteristics of Kogia breviceps and K. simus in his Table 1. The majority of these differences refer to features of the cranium and mandible. The most distinctive cranial characters are
the shape of the dorsal sagittal septum and the dorsal cranial fossae. These wereconfirmed by Ross (1979) who studied a considerable number of specimens. In
K. breviceps the dorsal sagittal septum near vertex is broad, whereas in K. simus it isnarrow.
This breadth of the present specimen of a calf is 22 mm, as seen in Table 3.
Accroding to Handley (1966) this breadth is 20-38 mm in K. breviceps, whereas in
K. simus it is only 6-14mm (both in adult specimens). In K. simus the dorsal cranial
fossa is cupped posteriorly and sub-symetrical, but in the present specimen eachfossa slopes gradually from the dorsal rim of the skull and giving no cupped appearance. These two are the most conspicuous character which separates the two
species. We concluded, therefore, that the present specimen is K. breviceps.
The measurements of the skull of this specimen are shown in Table 3. In
this table the measurement numbers are the same to those used by Ross (1979).
From these measurements, excepting above stated, no definite conclusion will bedrawn at present and further collection of material is needed. There are rather
wide range of variation in measurements presented by Ross (1979).
The seven cervical vertebrae are ankylosed into a single unit (Fig. 5 ), but theSci. Rep. Whales Res. Inst.,
No. 35, 1984

PYG~ I Y SPER~ I¥¥'HALE

87
1

.
n
e
im
c
e
p
ls
n
四 e
r
cp
h
f1
. Skulo
.3
g
i
F
.
w
e
i
lv
a
r
t
n
e
. V
b
.
w
e
i
lv
a
s
r
. Do
a
.
w
e
i
lv
a
r
e
t
. La
c
w.
e
i
rv
ro
i
e
st
o
. P
d

notherentrum. I
sc
t
oi
ed t
us
snotf
ebrai
t
th ver
en
v
e
hes
soft
si
y
iorepiph
er
t
s
po
c52
ear
r
he
lt
a. Inal
r
ent
re
hei
ot
ed t
us
swerenotf
e
s
iphy
p
hee
loft
eal
a
r
b
e
t
r
ve
al
s
. Thedor.6)giF
sC7,Dl2,L9,Ca24,Total52 (heformula iaeandt
r
b
e
rt
e
v
r
a
b
m
u
l
e
Th
.
b
i
r
d
e
i
n
a
mp
o
c
c
a
e
r
a
h
c
i
ewh
a
r
b
e
t
h巴 ver
et
aear
br
e
t
r
e
cv
horaci
ort
c
h
t
m
o
r
f
d
e
t
a
epar
ss
tlumbari
s
a
hel
bandt
i
har
t
pwi
hi
ns
o
ti
la
e
ehavenor
a
r
b
e
t
ver
4
l1
n al
. I
r end
o
ri
e
sl
po
‑
o
r
tsventon bone ali
e ofchevr
enc
lby abstcaudas
自renaeweramitlfeghtand l
i
her
hem t
neachoft,and ientsvronboneswerepre
che
r
hei
・and tn Table4
hown iesrebraeat
sofverurement
ass. Mesntoa ma
ed i
us
f
.
ig.6
nF
phi
photogralccrea
aehasnotbeen elbret
henumberofverlem oft
b
o
r
ep
h
tt
a
h
emst
e
Its
t.
s
n
.I
s
sRe
e
l
a
h
'
l
.l
p
Re
.
i
Sc
/
.
8
9
,1
J~匂 . 35

1
88

Ol'vlURA,SHTR
八KIHARA AND IT
O

Fig.4. Mandible
soft
h
ep
r
e
s
e
n
ts
pecim
e
n
.

TA
BLE3
. SKULL MEASUREMENTS OFTHE PRESEN
T SPECIMEN
Measurements
I
. To
t
a
l(
c
o
n
dy
l
o
b
a
s
a
l
)l
e
n
g
t
h
2
. Rostrum l
e
n
g
t
h本
3
. Rostrum,b
a
s
a
lwidt
h本
4
. Ro
s
trum
,wi
dth a
ti
t
s middle本5. Breadt
ha
cr
os
sp
r
e
‑
o
r
bi
t
a
la
n
g
l
e
so
fs
u
p
r
a
‑
o
r
b
i
t
a
l pro
c
e
s
s
e
s
6
. Br
ea
dth a
c
r
o
s
spo
s
t
‑
o
r
bi
t
a
lpr
o
c
e
s
s
e
s
7
. Zygomaticwid
t
h
8
. He
i
g
h
t to v
e
r
t
e
x
i
d
th o
fv
er
t
e
x
9 V
1
0
. Widt
ho
fs
upra‑
occi
p
i
t
a
la
t nar
r
o
w
e
s
tp
a
r
tbetween po
s
t
er
i
o
r
marginso
ftemporalf
o
s
s
a
e
1
1
. Tiprostrum ‑l
e
f
tn
a
r
i
s
1
2
. Heightorv
e
n
t
r
a
lborderofforamen magnum
1
5. Widthouter marginso
c
c
i
p
i
t
a
lcondylcs
1
6. Tip rostrum‑hi
nd margin p
t
cryg
oi
d
s
1
7
. Length ofmandible20. Height mandible at coronoid
2
1. Length mandibulars
y
n
p
h
y
s
i
s
2
4
. He
i
g
h
td
o
r
s
a
l bordero
fforamen magnumt
ov
e
r
t
e
x

、，

。

m mm

~ f
To
t l
e
n
g
th

247
96
1
02
84
1
9
0
1
9
6
1
9
7
1
5
1
22
1
5
3

1
0
0
38.8
41.3
34.0
76.9
79.3
79.8
61I
9.0
62.3

1
0
6
46
6
4
1
4
2
2
0
1
5
1
3
1
6
7

42.9
1
8
.
6
25.
5
5
7.
5
81.4
20.6
1
2.
6
2
7.I

本ル!
c
a
s
u
r
ed v
en
tr
a
l
l
y
.
S
c
i
.R司
'
f
l
. Hノ'
h
a
l
e
sRe
s
.I
n
s
t
.
,

λr
o
.35,1984

981

PYGMYSPER MWHAL8

a

b

.
n
ime
c
e
p
ts
n
e
s
e
r
ep
h
ft
eo
a
r
b
e
t
r
e
lv
a
ic
v
r
e
.S. C
g
i
F
.
w
e
i
lv
a
r
e
t
. La
b
.
w
e
i
rv
o
i
r
e
t
n
.A
a

ed
s
s
cu
s
)di
9
7
9
1
s(
s
)andRo6691ey(hHandl
. Bot
s
u
m
i
.s
sandK
p
e
c
i
v
e
r
.b
rK
o
tf
e
y
he
t
e
t
a
r
a
p
e
s
o
t
r
e
t
c
a
r
a
h
c
l
a
i
t
n
e
s
s
e
n
a
e
b
t
h
g
i
m
s
i
h
,thought
r
e
smatt
hi
ingont
h
t
o
n
)
4
5
9
1
(
a
d
ma
a
) and Y
9
5
9
,l
7
4
9
1
e(
, Hal
)
9
3
9
,1
7
3
‑
6
3
9
1
s. Ogawa (
e
ci
e
p
two s
e
h
dwithter
ccompa. ThesearaigaeofgenusKo
br
e
t
r
e
enumberofv
h
dt
e
t
n
cou
nTable5.
imeni
c
pe
ents
s
e
r
ep
h
noft
o
i
t
a
l
u
c
cul
t
s
e
g
r
a
hel
2 andt
s5
ei
a
r
b
te
er
tnumbero[v
es
l
l
a
m
es
h
le5 t
nTab
eni
e
Ass
‑
rofverlnumbe
a
t
o
het
nt
ime
c
pe
ts
en
s
re
9)andp3
91. InOgawasspecimen(
7
5
ed
t
uppor
ss
si
. Thi
s
p
e
c
i
v
e
r
ab
i
g
sKo
cimena
e
p
iss
h
dt
e
i
f
i
dent
s52. Ogawai
ei
a
r
b
e
t
ar
e
n
m
u
t
p
e
s
l
a
t
t
i
g
a
s
l
a
s
r
o
d
e
). Th
s
i
s
he
st
i
g.2ofh
Fi
l(
l
u
k
hes
aphoftrgbyphoto
t
n
e
s
e
r
p
e
Th
.
y
l
r
o
i
r
e
t
s
dpo
tcuppe
o
sn
ai
s
s
o
ialC
an
r
lc
a
s
r
o
hed
sbroadandt
xi
e
t
ver
)made
4
5
9
1
dy. Yamada(
ea
r
dal
e
t
a
t
ss
,a
s
p
e
c
i
v
e
r
.b
tK
swithoutdoub
meni
i
pec
s
,how‑
1)
8
9
l
shi(
aha
ndTak
. Omuは a
ns
cime
e
p
iss
fh
so
e
ci
pe
es
h
ono[t
i
t
nc
ti
s
nodi
,and6
,5
sandNos.2
u
m
i
.s
obeK
,and4t,3
cimenNos.I
pe
iss
dh
e
ur
t
c
e
j
,con
er
v
e
,
s
u
m
i
.s
ly K
b
si
s
o
sp
) wa
e
ung maloy959) (
1pecimen (
ess
l
. Ha
ψs
c
i
v
e
r
.b
o beK
t
s
e
c
n
e
m
m
o
c
d
n
a
r
e
g
r
a
l
h
c
mu
s
i
n
自
l
a
s
r
o
d
e
t
a
c
l
a
f
e
h
t
t
a
h
dt
e
b
i
cr
s
e
e h巴 d
s
u
a
c
e
b
l
.
ma
i
n
a
e
h
t
f
o
h
t
g
n
e
l
l
a
t
o
t
e
h
emiddleoft
h
ot
rt
o
i
r
te
yan
l
ght
i
l
s
is
h
dt
e
i
f
i
dent
cimen)h巴 ipeisNo.2s
h
)(
7
‑3
936
1
pecimen(heOgawaSs
ot
Ast
‑
o
c
iwho l
a
r
oMrA
ng t
i
d
or
c
c
ta
a
h
dt
e
b
i
r
c
s
e
,buthed
s
p
e
c
i
v
e
r
.b
obeK
ciment
e
p
s
.
p
i
owerl
hel
sneartelwrinkl
a
n
di
u
t
ongi
tl
en
s
re
ewerep
r
he
nt
me
ci
e
p
hes
dt
e
ct
e
l
t
ti
a
o
r
h
sont
e
s
a
e
r
ec
h
anst
sme
hi
ft
ti
u
,b
ear
l
tc
o
sn
nJapanesei
oni
i
anat
Thisexpl
.
)
2
8
9
,l
l.
ta
rwoode
the
a
Le
s(
u
m
i
.s
taK
c
a
nf
menwasi
ci
pe
ss
i
h
tt
a
h
et
l
b
i
s
s
o
sp
i
l
a
s
hedo1
nwhichtographi
sphot
i
om h
r
gedf
menwasjudcipe
Yamada'sNo.5s
e
v
a
h
o
t
s
m
e
e
s
a
s
s
o
f
l
a
i
n
a
r
c
l
a
s
r
o
d
t
u
b
,
emsbroadexset
ptumnearver
e
ls
a
tt
i
g
a
s
,
.
t
s
n
.I
s
sRe
e
l
w
/
'
1
.1
p
.R司
i
c
S

,1984
5
No.3

1
9
0

01¥!URA,SトllR
八KIH
ARAAND JTO

F
i
g
.6
. V
e
r
t
e
b
r
a
eoft
hepr
e
s
e
n
ts
pe
cime
n
.
a
. 1
‑1
2d
o
r
s
alv
c
r
t
c
b
i
a
e
.
b
. 1
‑9lumba1veneb
i
a
e
.
c
. I8c
a
u
d
a
lv
e
r
t
e
b
r
a
e
d. 9‑24r
n
u
d
a
lv
e
r
t
e
b
r
a
e
.
目

Sc
i
.Re
/
1
.I
V
/
t
a
l
e
sRe
s.J
l
l
S
I
.
,

N
o
.3
5
,1
9
8
4

PYGMY SPERM WHALE
TABLE 4.

SerialNo.

Vertebral
No.

191

MEASUREMENTS OF VERTEBRAE OF THE PRESENTSPECIMEN (IN MM)
Centrum

Greatest
breadthGreatestheight74

29
44(posterior)

35(inferior)

27(anterior)
27
38
29
28
29
28
27
29
29
27
27
30
34
28
37
28
38
29
31
38
38
31
41
34
41
39
42
43
43
39
42
43
43
42
42
45
42
45
46
43
43
43
39
43
40
43
41
39
37
40
37
39
37
39
36
38
36
36
35
36
35
33
33
33
31
30
27
30
22
27
26
20
24
16
22
15
19
14
12
18
16
10
14
9
12
7
II
6

18

1
2
3
4
5
6
7
8

~J

82

DI

73

60

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
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52

2
3
4
5
6
7
8
9
10
11
12
LI
2
3
4
5
6
7
8
9
Ca 1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24

70
66
61
58
56
54
67
73
77
78
80
81
81
81
82
83
85
86
89
86
84
82
78
74
66
60
55
49
43
38

69
73
76
78
79
81
81
83
85
87
87
90
91
93
93
94
95
95
93
92
80
74
71
64
61
59
55
52
49
45
40
38
30
28

BreadthHeightNote
LengthellSci. Rep. Whales Res. Inst.,
No. 35, 1984

35

20
23
25
26
27
28
29
29
30
31
31
32
33
34
34
35
35
36
36
35
35
35
34
33
33
31
31
29
28
28
25
25
23
19
16
12
12
12
12
II
10
9
8
6

all fused in to a
mass, but pasterior epi physisof No. 7 is not
fused to centra.

anterior epiphysis
missingboth epiphyses
missing

1
92

OMURA,SHlR
A KIH八R八 八 NDI
TO

?

ぽ

山崎
・

i
w

H
J

s
i
m
u
s?
b
r
e
v
i
c
e
p
s
M M ．れか目白

﹃

︽
UA

Remar
k
s

56*
52
55

PRψ S
S51
山
St
tt
t
tt Nt
t
J
m
mtm u
明m 四
︐ ．

phJFO

t

F O A守
内d q L nJLAn 守t︐
n
ゐ
の
︐ι

L Eln

Total

戸472
7z J7
︑︐
︑JFhJ
︑d phJ︐
・

a736
C222

i l lu − −
内

L9ω 9

4

︐
︐
吋同
﹃
︐
︐
﹃
︐︐
︐
︐
句 ﹃

・1守ワ1
quq
un
an
r
−
l
1
Il

J
v

C777

AuthorOgawa(
1
93
6‑
3
7
)
Ogawa(1
9
3
9
)
Hal
e(
1
9
4
7)
Yamada(
1
9
5
4
)
No.3
N
o
.4
No.5
.
'
l
o
.6
I
fal
e(1
959
)
P
1c
s
ent

︐
−
のi
︑
C l内
l
の
︐
︑︑

'
/
UMBER OF VERTTABLE5. .
EBRAE IN G巳NUSKOGIA COUNTEDBY ¥'ARIOUS AUTHORS*Sectext.

F
ig
.7
. Rib
soft
hep
r
e
s
e
n
ts
p
e
ci
me
n
.

S
c
i
.Re
戸
.J
l
l
h
a
l
e
sRe
s
.!
1
1
s
t.
,
No.3
5
,1
9
8
・
1

193

PYGMY SPERM WHALE
TABLE 6.

LENGTH OF THE RIBS OF THE PRESENT SPECIMEN (IN MM)

No.

Right*

Left*

1
2

131
194
215
222
230
234
224
217
201
192
178
157

137
197
217
235
224
223
226
212
202
192
179
159

3
4
5

6

7
8
9

10
11

12
Measured in straight line.
* In which 7 ribs are double headed.

cupped appearance.
From the above it will be concluded that the total number of vertebrae would
be 52-54 in K. brevicJps and 55-57 in K. simus, pending further studies in futurewith more samples.
In the present specimen 12 pairs of ribs are present (Fig. 7). Their straightlengths are shown in Table 6.
REFERENCESCALDWELL, D. K., A. INGLIS, and J.B. SIEBENALER, 1960. Sperm and pygmy sperm whales stranded in
the Gulf of Mexico. ]. Mamm. 41 (!): 136-138.
HANDLEY, C. 0. JR., 1966. A synopsis of the genus Kogia (pygmy sperm whale). pp. 62-69. In: K. S.
Norris (ed.), Whales, dolphins and porpoises. Univ. California Press, Berkeley and Los Angeles. 789 pp.
HALE, H. M., 1947. The pygmy sperm whale (Kogia breviceps, Blainville) on South Australian coast. Ree.
S. Aust. Mus. 8: 531-546.
HALE, R. M., 1959. The pygmy sperm whale on South Australian coasts.-continued. Ree. S. Aust. Mus.

13: 333-338.
HALE, H. M., 1963. Young female pygmy sperm whale (Kogia breviceps) from Western and South Australia.
Ree. S. Aust. Mus. 14 (3): 561-577.
HUBBS, C. L., 19.51. Eastern Pacific records and general distribution of the pygmy sperm whale. J.
Mamm. 32 (4): 403-410.
LEATHERWOOD, S., R.R. REEVES, \'V. F. PERRIN and \'\'.E. EVANS, 1982. Whales, dolphins, and porpoisesof the Eastern North Pacific and adjacent Arctic waters. A guide to their identification. NOAA
Technical Report NMHS Circular 444. 245 pp.
OGAWA, T., 1936-37. Studien iiber die Zahnwale in Japan. VI. Cogia. Botany and Zoology, 4: 20172024, 5: 25-28. (in Japanese).
OGAWA, T., 1939. Hakujira Cogia oyobi Steno ni kansuru Chiken tsuika (Additional knowledge of Cogia andSteno). Botany and Zoology. 7: 1173-1180. (in Japanese).
OMURA, H. and Y. TAKAHASHI, 1981. A pygmy sperm whale stranded at Tokaimura, Ibaragi, Japan.
Sci. Rep. Whales Res. Inst., 33: 119-124.
RoEsT, A. I., 1970. Kogia simus and other cetaceans from San Luis Obispo County, California. J. Mamm.,

51(2):410-417.
Ross, G.J.B., 1979. Records of pygmy and dwarf sperm whales, genus Kogia, from southern Africa, withbiological notes and some comparisons. Ann. Cape Prov. Mus. (nat. Hist.) 11 (14): 259-327.
YAMADA, M., 1954. Some remarks on the pygmy sperm whale, Kogia. Sci. Rep. Whales Res. Inst. 9: 37-58.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

NOTE ON A GRAY WHALE FOUND IN THE ISE BAY ON
THE PACIFIC COAST OF JAPANMASAMI FURUTA
Toba Aquarium, Toba, Mie-ken, 517 Japan

A gray whale, Eschrichtius robustus (Lilljeborg, 1861 ), was sighted at 1245 hour of
27 March 1982 within a few hundreds meters from the shore of the Mikimoto
Pearl Island at Toba (34°28'N, 136°53'E; water depth 8 to 15 m), which locates in
the Shima Archipelago near the entrance of the Ise Bay on the Pacific coast ofcentral Japan (Fig. 1). The species was identified by the shape of rostrum (Fig. 2)
and about 10 dorsal humps (Fig. 3). The body lengh was estimated at about
12 m. Most of its body surface was covered by barnacles and white/yellow fallingskin presumably covering healing scars (Figs 2 and 3). Remaining portion of the
body was dark gray. Several parallel scars present on the right side of head (Fig.
2) were presumably caused by screw propeller of a small boat. This whale wasswimming toward the Ise Bay, and disappeared at 1700 hour (27 March).
On 12 April, 16 days after the first sighting, the same whale (identified by thescars) was sighted in a shallow water in the Ise Bay off Tsu City. After this date,
the whale was sighted frequently by the flights of the press and television companies, and some shipboard observation was done. All the confirmed records being in the same area, it was suspected that the whale had settled down the place.
The last sighting was recorded by the Chunichi Press on 31 May at the same location, and the whale was considered to have left the Ise Bay thereafter. The minimum duration of the stay in the coast was 64 days since 27 March.
Since the sea was shallow (7 to 15 m), the whale's movement off the coast of
Tsu city was traced easily by the cloud of mud along its passage. The interval ofdives was 5 to 6 seconds (short dives) or 3 to 4 minutes (long dives). The blow
was heart shaped. The spyhopping posture was once observed.
Omura (1974) indicated in his review that there was a low level of constantcatch of the gray whale by the Japanese net-whaling along the Pacific coast till
the end of the last century. However, the gray whale re'cords have been extremely
limited in the Pacific coast in recent years (Nishiwaki and Kasuya, 1970). The
present record is the third one known to science off the Pacific coast after the startof complete protection in 193 7.
I wish to express my thanks to all the people who helped me in collecting theinformation and to Dr T. Kasuya for his critical reading of the draft.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 195-197

196

FURUTA

REFERENCES
NrsHIWAKI, M. and T. KAsuvA, 1970. Recent record of gray whale in the adjacent waters of Japan and aconsideration on its migration. Sci. Rep. Whales Res. Inst., 22: 29-37.
OMURA, H., 1974. Possible migration route of the gray whale on the coast of Japan. Sci. Rep. Whales Res.
Inst., 26: 1-14.

z

th
M

Ise Bay

(J

0

M
0

....:tM

Pacific Ocean

136°30'Fig. I. Map of Toba and the Ise Bay region. I: Mikimoto Pearl Island where thewhale was first sighted; 2: off Tsu city where the whale stayed for minimum of
45 days.

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

l
6
!

'
Al
!
:
)ns
エ上JO勺！
El｛ 川 凱[
1JOS
d山 nq]
BS
I
.Oα

f
o
86l f;fi '
O
N
1口I
[・
s
a
uS
a
/
V
l
f
;
M・
r
f
a
u・
lJ
S
・
i
:
;'
i
l
!
d

'
A
l
!
:
)ns
.
ilJO勺IBl{M~ tp JOUO!
lb.Ip官;
Jl
{JO:
:
i
p!
S1l
[
i
l！沼田 Z'
i
i
！
丘

.
'
T1VHN¥ 人V‑UD V NO 3.LON

Appendix
MEASUREMENTS OF BODY PROPORTIONS OF
THE PYGMY BLUE WHALE, LEFT BY THE LATEDR TADAYOSHI ICHIHARAINTRODUCTION BY EDITOR

One of the most prominent works of The Late Dr T. Ichihara is the discovery of the" Pygmy Blue Whale ". The name pygmy blue whale was first given by Ichihara( 1961) on blue whales inhabiting the waters around Kerguelen Island, recognizing
differences in the external characteristics from the blue whales elsewhere in the
Antarctic. Since then researches on this population have been carried out by
various authors i.e. Ichihara, 1963 and 1966; Gambell, 1964; Ichihara and Doi,
1964; Zemsky and Boronin, 1964; Omura, Ichihara and Kasuya, 1970.
The subspecies Balaenoptera musculus brevicauda was proposed by Ichihara in apaper read in 1963 at the First Symposium on Cetacean Research held in Washington, D. C. His paper was not published until 1966, due to delay in printing.
Meanwhile the name brebicauda was published by Zemsky and Boronin (1964).
This is a nomen nudum according to van Bree, pers. comun.; and the first valid
publication of the name was by Ichihara 1966 (Rice, 1977).
His conclmion is mainly based on the differences in the external morphology
between the ordinary and pygmy blue whales. To our regret the basic data ofthe measurements of body proportions of each whale he measured (Table 1) were
not appended to this important thesis. Accordingly these valuable data could not
be used by researchers who desire to use them. This is the reason why we publish
them here at this moment. (H.0.)
REFERENCESGAMBELL, R., 1964. A pygmy blue whale at Durban. Norsk Hvalfangst-Tid., 53 (3): 66-68.
lcHIHARA, T., 1961. Blue whales in the waters around Kerguelen Island. Norsk Hvalfangst-Tid., 50 (l);1-20.
lcHIHARA, T., 1963. Identification of the pygmy blue whales in the Antarctic. Norsk Hvalfangst-Tid., 52(5): 128-130.
lcHIHARA, T., 1966. The pygmy blue whale, Balaenoptera musculus brevicauda, a new subspecies from theAntarctic. pp. 79-113. In: K. S. Norris (ed) Whales, dolphins and porpoises. Univ. Calif. Press. Berkley and Los Angeles. 789 pp.
lcHIHARA, T. and T. Doi, 1964. Stock assessment of pygmy blue whales in the Antarctic. Norsk HvalfangstTid., 53 (6): 145-167.
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.
RICE, D. W., 1977. A list of the marine mammals of the world. NOAA Tech. Rep. NMFS SSRF-711.
15 p.
ZEMSKY, V. A. and V. A. BoRONIN, 1964. On the question of the pygmy blue whale taxonomic position.
Norsk Hvalfangst- Tid., 53 ( 11): 306-311.
Sci. Rep. Whales Res. Inst.,
No. 35, 1984, 199-203

200

APPENDIXTABLE !.

MEASUREMENTS OF BODY PROPORTIONS OF THE PYGMY(Measurement of 1 are in metres and other!. Total length, tip of snout to notch of flukes
3. Tip of suout to blow-holeof snout to anterior end of flipper
7. Eye to ear, centres
8. Notch of
11. Notch of flukes to umbilicus
12. Notch of flukes to end of system ofvertical height
15. Dorsal fin, length of base
16. Flipper, tip to axilla
21. Skull, greatest width
22. Skull length, condyle to tip of premaxilla

Serial no.
602NOOOO
612K0974
60K J 1025
612K0987
612K0960
60K J 0876
60K J 0795
612K0938
613N 1334
60K J 0878
60K.J 1149
602T 1216
612K0954
613Kl876
613K 1875
60KJ 1116
602T 1578
60KJ 0619
613Kl863
60K J 0640
60KJ 1261
60K J 1015
612T0845
60K J 1022
60KJ 0941
60KJ 0875
60K J 0796
60KJ 0912
60KJ 1117
602N0924
60KJ 0770
602T 1231
tiOK J 0944
602T 1656
602T 1212
60K.J 0914
602N0848
602N0804
60KJ 0858
613N 1326
613N 1845

1
3[MALE]
18.00
17.67
18.05
19.67
19.30
19.30
16.58
18.59
19.90
20.00
20.50
20.00
19.50
20.40
18.48
21.00
21. 5019. 53
21.60
15.28
21.30
16.67
21.30
21.30
22.00
18.18
22.10
18.55
22.20
22.10
18.55
23.10
23.10
[FEMALE]
18.60
19.10
19.90
20.30
20.50
20.80
21.00
21.10
21.30
18.31
21.30
17.37
21.30
16.43
21.30
17 .84
21.40
19.16
21.40
19.63
21.50
16.28
21.60
21. 7018.89
21. 70
18.66
21.80
20.18
21.25
17.88
21.30
20.33

5

6

6'

7

8

10

19.39
20.78
21.24
19.27
19.10
19.75
20.49
21.25
20.74
21.90
20.00

44.88
47.09
43.52

33.67
35.46

5.50
5.26
3.63
5.38
6.53
5.25
4.39
5.25
5.44
4.77
5.58

21.56
24.10
19.17
22.79
22.61
22.00
20.49
21.00
23.04
20.95
21.40
23.15
28.09
19.72
21.60
20.45
23.98
20.36
23.53

27.50
28.25
27.98
27.05
25.63
26.00
25.37
26.00
26.86
27.62
25.12
25.00
27.46
25.35
24.41
23.64

24.73
21.62
21.67
22.44
22.60
22.86
22.27
22.54
24.55
23.47
23.00
20.09
22.43
23.26

26.88
27.23
27.09
26.83
27.88
27.62
27.01
25.82
25.96
24.88
25.35
26.17
27 .10
30.23
28.70
27.88
25.99
26.15
25.65
24.13

18.07
20.66
20.19
21.27
20.27
23.98
18.61
19.91
18.28
22.25
21.92
20.00
20.43
20.95
22.27
19. 72
19.01
20.19
19.72
20.56
22.36
20.14
21.01
20.05
21.10
20.14
21.64

29.53
34.17
42.00
45.37
46.50
44.80
42.86
42.33
44.44
42.72
39.44
43.18
43.69
38.91

40.32
46.07
43.34
43.41
42.31
42.86
42.18
40.85
42.25
44.39

35.75

32.56
28.64
31.46
29.58
35.45
31.22
34.68
29.86

35.60

33.33
31.46
32.39
32.39
34.11
36.45

42.79
43.52

44.04
41.88
43.66

33.18
31.34
33.49

6.81
4.69
4.69

4.96

4.03
4.87
3.20
4.39
5.29
6.19
2.85
6.10
5.07
4.69
5.16
6.54
5.14
3.70
2.95
4.83
5.51
5 .13
5.26

25.35
21.01
21. 56
20.71

24.77
26.70
24.67
27.27

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

201

PYGMY BLUE WHALE
BLUE WHALE, LEFT BY THE LATE DR TADAYOSHI ICHIHARA.
are percentages against the total length)

5. Tip of snout to centre of eye
6. Tip of snout to tip of flipper
6'. Tip
flukes to posterior emargination of dorsal fin
10. Notch of flukes to anus
ventral grooves
14. Dorsal fin,
13. Anus to reproductive aperture, centres
17. Flipper, tip to anterior end of lower border
19. Flipper, greatest width(23). Flukes, greatest width
II

12

13

14

15

42.89
44.88
44.04
45.08
42.21
44.00
43.90
40.00
42.65
44.76
40.93
41.67
42.96
40.85
39.91
40.91

41.00
43.21

7.22
6.65
8.29
7.89

0.89
0.66

3.28
2.49

I. 24

2.85

31.48
38.97
37.09
38.03
39.09

8.50
6.83
6.30
6.96
6.19
6.97
7.87
5.87
7.04
7.51
8.18

40.54
43.89

37.39
42.08

6.76
8.60

41.93
42.15
43.84
44.39
44.71
42.86
43.13
41. 78
41.60
45.07
42.25
40.65
42.99
45.12
42.13
44.47
43.09
42.66
42.82
41.55

40.41
37 .19

39.00
36.76

43.36

36.62
38.31
42.72
37.56
38.32
40.65
42. 79
43.09
38.57
38.07
38.21
37.55

2.68
3.14
2.96
3.41
2.89
2.86
2.85
2.35
3.48
2.35
2.82
2.33
1.87
2.79
3.24
3.46
3.04
2.29
2.59
5.07

1.15
0.98

16

17

19

12.18

15.13

3.74

9.50
11.22

12.25
13.66

3.40
3.66

10.48

13.10

3.90

9.68

12.90

3.12

10.04
10.54
9.62
10.00
9.48

12.81
13.71
12.74
12.86
11.80

3.89
3.95
3.65
3.57
3.51

21

22

12.44

26.00

12.04

25.92

(23)

3.00
3. 77

I. 06

1.13
0.99
0.85
0. 77
0.90
0.81
1.09

2.58
3.05
2.82
3.18
3.17
2.25
2.49

1.10

5.08

0.89
0.66
0.99
0.70
0.98
1.12
1.26

2.35
3.66
2.82
2.11
3.27
2.10
2.05

I.38
0.92
0.87
0.75

4.06
4.10
2.75
3.67

25.35
24.88
26.17

10.19

12.96

3.61

26.15

Continued ...

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

APPENDIX202
TABLE I.

Continued

Serial no.
613Kl884
613Kl859
613Nl324
613Nl328
613Kl858
60KJ 0581
602N0897
60K J 0808
602T 1723
602Tl767
602TI275
602Tl591
60K J 0801
60K j 0798
602Tl693
602Tl612
602N0896
602N0907
602N0805
60KJ 0897
60K J 0624
60K J 0912
60K J 0946
602N0924
602T0805
60K J 0945
602T0772
60K J 0941
60K J 0889
60K J 0858
602T0736
602T0771
60KJ0875
602T0769
60K J 1040
602N0896
60K J 0872
60K J 0801
602T0816

1
3
5
21.03
21.40
17.29
21.50
19.53
19.25
21.82
15.99
21.90
17.58
19.95
21.90
19.18
23.74
22.00
15.91
19.09
22.10
18.78
17.65
22.10
20.81
22.10
20.81
19.00
22.10
21.27
19.00
22.30
18.83
19.73
22.30
16.59
20.18
22.30
20.18
18.83
22.50
20.44
20.35
22.60
17.26
22.57
22.60
16.81
21.32
19.82
22.70
22.80
18.95
17.06
20.04
17.98
22.80
21.20
23.00
24.20
19.42
[FOETUS, MALE]
15.82
2.52
17 .15
2.70
16.31
3.25
14.15
17.09
3.57
14.00
16.44
3.65
18.32
4.15
14.46
17.26
4.52
15.77
4. 70
18.10
13.81
6.30
[FOETUS, FEMALE]
15.22
2.30
16.09
13.48
2.30
2.70
17.04
3.15
14.92
17 .14
4.35
15.86
4.73
15.22
17.97
4.81
17.05
5.20
14.42
16.35
5.36
14.93
17 .16

6

6'

42.33
42.67
43.38
42.46

5.04
4.79
32.27
32.13

42.53

43.05
42.22

7

32.13
34.39
32.29
32.74
32.74
34.51
37 .17
34.10
31.45
30.26

44.57

40.79
44.44
32.62
33.89

5.00
4.84
4.98
4.97
4.49
6. 73
5.38
5.78
5.31
5.20
4.38
5.18
3.90

7.99
6.92
6.46
8.77

43.84
35.42
45.13
42.13
44.44

32.22

8.18
7.21
5.56

35.65
9.63

45.56
33.65
44.14
33.62
44.91
45.58

33.08
32.46

8.97
5.29
8.11
6.16

8
20.09
23.26
22.91
21.37
21.92
20.00
22.35
21. 72
22.62
21. 72
22.42
23.32
21.97
22.67
23.45
20.80
22.91
23.90
20.18
21.20

10
24.77
27.91
27.27
27.58
27.40
24.09
24.38
27.60
26.70
25.79
29.15
25.11
26.91
28.44
27.43
22.57
27.31
22.63
23.90
28.13
26.86

23.81
24.81
22.46
22.97
27.40
24.10
23.67
25.53
25.08

30.16
29.63
28.92
29.41
31.51
30.12
27.88
31.06
30.63

23.91
23.04
24.44
25.08
26.67
25.37
25.57
24.04
24.25

29.57
29.13
30.37
29.21
29.66
29.61
27.03
29.85

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

203

PYGMY BLUE WHALE

II

46.51
44.63
45.16
42.01
40.91
41.18
42.99
42.53
42.08
45.29
41. 7042.15
41. 78
42.48
44.69
43.52
44.12
40.39
42.84

46.03
44.44
42.46
45.94
47.67
45.30
45.80
47.23
46.98
45.22
46.09
47.41
43.81
44.60
47.36
40.96
46.27

12
39.25
44.19
39.92
38.36
40.64
39.09
36.92
40. 72
40.27
40.36
38.16
39.46
39.82
42.48
39.47
34.21
36.75

46.46
43.98
42.65

43.17

43.48
41.27
44.40

45.90

13
2.80
2.79
2.43
2.51
2.28
2.27
2 54
3.17
1.81
3.17
2.69
0.91
2.24
2.64
2.22
4.86
2.65
4.12
4.17
3.03

7.94
7.41
7.70
6.85
6.27
8.40
6.39
7.47
2.17
2.61
2.59
2.22
1.83
2.74
1.66
2.24

Sci. Rep. Whales Res. Inst.,
No. 35, 1984

0.70
0.51
0.78
0.87
0.82
0.82
0.77

14

15
1.87
2.28
4.22
3.70
2.97
5.91
3.35

1.00
1.18
1.12
0.99
0.94

2.94
2.26
2.02
2.24
2.02

0.88

1.99

1.37
1.05
0.70

3.52
3.46
3.73

I. 54
I. 68

5.54
4.34

1.69

4.82

I. 59

4.13

I. 74
1.30

3.48
4.35

1.59

16

17

19

9.28

12.22

3.39

9.33

11.78

3.56

10.39

12. 77

3.50

11.11
11.52

15.48
15.56

4.37
4.44

13 .15

17.81

4.38

12.83
13.19

17.26
16.38

5.09
4.38

12.22

16.67

4.81

12.64

16.32

4.37

5.07

2.31
1.31

4.81
3.17

12.46

16.22

4.57

22

(23)

25.56

27.39

3.44

1.90

21

22.22
14.25

THE SCIENTIFIC REPORTS OF THE WHALES RESEARCHINSTITUTE, TOKYO, JAPANNUMBER l, 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 2 C0 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. 46-50
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. 85-88
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. Ill. 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 of Japan. 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. 49-51
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 physalus) caught by the Japanese Antarctic whaling fleets. 91-167

NUMBER 6, DECEMBER 1951
Hosokawa, H. On the extrinsic eye muscles of the whale. with special remarks upon the innervation andfunction of the musculus retractor bulbi. 1-33
Murata, T. Histological studies on the respiratory portions of the lungs of cetacea. 35-47
Kojima, T. On the brain of the sperm whale (Physeter catodon L.). 49-72
Mizue, K. and 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 l 950/51. 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 ai;id 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 of a rare porpoise, Feresa Gray from Japan. 59-88
Omura, H. and K. Fujino. Sei whales in the adjacent waters ofJapan. 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 ofa 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 .('_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 (Pr.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
Iwai, E. Descriptions on unidentified species ofdibranchiate 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 10 years.

85-96
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. Ichihara 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
Ohsumi, S. (Kimura), M. Nishiwaki and T. Hibiya.

NUMBER 14, SEPTEMBER 1959
Omura, H. Bryde's whale from the coast of Japan. 1-33
Nishiwaki, M. and T. Kamiya. Mesoplodon stejenegeri from the coast of Japan. 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 131 1 labelled antibody.

101-106
Ichihara, 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_vsalus (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. Ichihara and T. Kasuya. Osteological note of a sperm whale. 35-45
Ichihara, T. Prenatal dead foetus of baleen whales. 47-60
Nishiwaki, M. Mesoplodon bowdoini stranded at Akita Beach, Sea ofJapan. 61-77
Nishiwaki, M. Observation on two mandibles of Mesoplodon. 79-82
Sinclair, John. An early dolphin embryo (Stenella caeruleoalbus) in serial sections. 83-87
Nemoto, T. Food of baleen whales collected in recent Japanese Antarctic whaling expeditions. 89-103
Uda, M. Subarctic oceanography in relation to whaling and salmon fisheries. 105-119

NUMBER 17, FEBRUARY 1963
Nishiwaki, M., 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
lchihara, 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, l\-1. 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 (Stene/la 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 (Stene/la caeruleoalba) with protruded rudimentary hind limbs. 135-136

NUMBER 20, SEPTEMBER 1966
Ohsumi, S. Se-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
Ichihara, 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 ofvarginal 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 of finless 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. 1-2 7
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 .Efaudichaudii 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. I toh. 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 den tin. 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 Ind us 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 hai:bour 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
Omura, 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 I 966/67 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 Stene/la 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. PoJsible migration route of the gray whale on the coast of Japan. 1-14
Satake, Y. and H. Omura. A txonomic study of the minke whale in the Antarctic by means ofhyoid 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 allenuata 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 Stene/la coeruleoalba. 259-263
Kamiya, T. and F. Yamasaki. Organ weights of Pontoporia blainviUei and Platanista gangetica (Platanistidae).
265-270
Machida, S. Surface temperature field in the Crozet and Kerguelen whaling grounds. 271-287
Machida, S. The voyage of the Konan Maru No. 16 to the Antarctic whaling grounds. 289-302
Itoh, S. and 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. Tht> 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 Indus dolphin. 81-94
Kasuya, T. Past occurrence of Globicephala melaena in the western North Pacific. 95-108
McCann, C. A study of the genus Berardius Duvernoy. 111-137
Nishiwaki, M. and 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 cementa\ 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 Stene/la in western South Atlantic

Xlwaters. 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 north western Pacific. 145-151
Leung, Y. M. Life cycle of qvamus 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 of lipid 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 Stenella coeruleoalba 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
Orci11us orca, 107-111
Nishiwaki, M. and A. Sasao. Human activities disturbing natural migration routes of whales. 113-120
Yoshida, K., N. Baba, J\1. 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, Lage11odelphis 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 of 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 of Dugong dugon.
301-310
Kagei, N., K. Asano and M. Kihata.
superba. 311-313

On the examination against the parasites of Antarctic krill,

Euphausia

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,
Po11toporia 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-l 19
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

NUMBER 32, DECEMBER 1980
Kawamura, A. Food habits of the Bryde's whales taken in the South Pacific and Indian oceans. 1-23
Omura, H. Morphological study of pelvic bones of the minke whale from the Antarctic. 25-37
Hohn, A. A. Age determination and age related factors in the teeth of western North Atlantic bottlenose
dolphins. 39-66
Yonekura, M., S. Matsui and T. Kasuya. On the external characters of Globicephala macror!!)mchus off Taiji,
Pacific coast of Japan. 67-95
Nemoto, T., P. B. Best, K. Ishimaru and H. Takano. Diatom films on whales in South African waters.
97-103Kamiya, T. and P. Pirlot. Brain organization in Platanista gangetica. 105-126
Yamasaki, F., S. Komatsu and T. Kamiya. A comparative morphological study on the tongues ofmanatee and dugong (Sirenia). 127-144

xiii
Casinos, A. and ]. Bou. On a massive stranding of short-finned pilot whale, Globicephala macrorhynchus
Gray, 1846, on Margarita Island (Venezuela). 145-148
Mermoz, ]. F. A brief report on the behavior of commerson's dolphin, Cephalorhynchus commersonii, in
Patagonian shores. 149-154
Kawamura, A. A review of food of balaenopterid whales. 155-198
Kawakami, T. A review of sperm whale food. 199-218

NUMBER 33, DECEMBER 1981
Omura, H., T. Kasuya, H. Kato and S. Wada. Osteological study of the Bryde's whale from the central
South Pacific and eastern Indian Ocean. 1-26
Miyazaki, N., Y. Fujise and T. Fujiyama. Body and organ weight of striped and spotted dolphins off
the Pacific coast of Japan. 27-67
Yamasaki, F. and T. Kamiya. The stomach of the Boutu, Inia geoffrensis: comparison with those of other
Platanistids. 69-81
Watkins, W. A. Activities and underwater sounds of fin whales. 83-117
Omura, H. and Y. Takahashi. A pygmy sperm whale stranded at Tokaimura, Ibaragi, Japan. 119-124
Aguilar, A., L. Jover and E. Grau. Some anomalous dispositions of the Jacobson's organ in the fin
whale. 125-126
Kamiya, T., N. Miyazaki and S. Shiraga. First case of dicephaly in Odontoceti. 127-129
Ohtaishi, N. and M. Yoneda. A thirty four years old male Kuril seal from Shiretoko Pen., Hokkaido.

131-135

NUMBER 34, DECEMBER 1982
Sergeant, D. E. Mass strandings of toothed whales (Odontoceti) as a population phenomenon. 1-47
Nishiwaki, M. The mandible of bowhead in Kathmandu. 49-57
Kawamura, A. Food habits and prey distributions of three rorqual species in the North Pacific Ocean.

59-91
Zhou, K. Classification and phylogeny of the superfamily Platanistoidea, with notes on evidence of themonophyly of the cetacea. 93-108
Nishiwaki, M. and T. Tobayama. Morphological study of the hybrid between tursiops and pseudorca.

109-121
Kato, H. Food habits of largha seal pups in the pack ice area. 123-136
Nishiwaki, M., M. Yamaguchi, S. Shokita, S. Uchida and T. Kataoka. Recent survey on the distributionof the African manatee. 137-147

NUMBER 35, MARCH 1984
Lowry, L. F. and K. J. Frost. Foods and feeding of bowhead whales in western and northern Alaska. 1-16
Singarajah, K. V. Observations on the occurrence and behaviour of minke whales off the coast of Brazil.

17-38
Kato, H. Observation of tooth scars on the head of male sprem whale, as an indication of intra-sexual
fightings. 39-46
Seki, Y. Anatomical studies on the cell column located closely medial to the nucleus of the spinal root of thetrigeminal nerve in the sperm and the pygmy sperm whales. 47-56
Kasuya, T. and S. Matsui. Age determination and growth of the short-finned pilot whale off the Pacificcoast of Japan. 57-91
Miyazaki, N., L. L. Jones and R. Beach. Some observations on the schools of dalli- and truei-type Dall's
porpoise in the northwestern Pacific. 93-105

xiv
Kasuya, T. and L. L. Jones. Behaviour and segregation of the Dall's porpoise in the northwestern North
Pacific. 107-128
Leatherwood, S., R. R. Reeves, A. E. Bowles, B. S. Stewart and K. R. Goodrich. Distribution, seasonal
movements and abundance of Pacific white-sided dolphins in the eastern North Pacific. 129-157
Fordyce, R. E., R.H. Mattlin and J.M. Dixon. Second record of spectacled porpoise from subantarctic
Southwest Pacific. 159-164
Yamasaki, F. and K. Kito. A morphological note of the intestine of the Boutu, with emphasis on its lengthand ileo-colic transition compared with other Platanistids. 165-172
Zhou, K., M. Zhou and Z. Zhao. First discovery of a tertiary Platanistoid fossil from Asia. 173-181
Omura, H., M. Shirakihara and H. Ito. A pygmy sperm whale accidentally taken by drift net in the North
Pacific. 183-193
Furuta, M. Note on a gray whale found in the Ise Bay on the Pacific coast of Japan. 195-197
Appendix
Measurements of body proportion of the pygmy blue whale, left by The Late Dr Tadayoshi
Ichihara. 199-203

SUBJECT INDEX

Taxonomy, Body proportionand Osteology
Balaena mysticelus 22: 45-62, 34: 49-5 7
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, 35: 195197
Balaenoptera musculus 7: 125-183
B. musculus brevicauda 22: 1-27, 35: 199-203
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, 33: 1-26
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
Physetercatodon 7: 125-183, 11: 47-83, 16: 35-45,
17: 1-14
Kogia sp. 9: 37-58
K. breviceps 33: 119-124, 35: 183-193
Tasmacelus 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:(:,iphius cavirostris 24: 1-34
BrBerardius 27: 111-137
B. bairdii 10: 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 macrorhynchus and G. melaena 27: 95110
Globicephala macrorhynchus 32: 67-95, 32: 145-148
Lagenodelphis hosei 25: 251-263, 30: 231-244
Stene/la attenuata 19: 53-64
S. spp. 28: 129-135
Phocoena dioptrica 35: 159-164
Platanistoidea 34: 93-108, 35: 173-181
Platanisla 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, 32: 25-37
Hyoid bone, baleen whales 18: 149-170

Balaenoptera acutorostrata 26: 15-24
Phoca 26: 313-320
Sternum and clevicle
Stenella coruleoalba 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
Platanista 32: 105-126
Spinal cord, Eubalaena 13: 231-251
Physeteridae 35: 47-56
Trigeminal nerve, Physeteridae 35: 47-56
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 I: 41-47
Sensory tubercle, lip 3: 1-16
Lingual margin 28: 137-140
Taste buds, Stenella 30: 285-290
Tongue, Sirenia 32: 127-144
Head section, Stene/la 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, lnia 33: 69-81
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

ii

Body and organ weight
Eubalaenaglacialis 13: 1-52, 21: 1-78
Balaenoptera musculus 3: 132-190, 4: 184-209, 125183
B. musculus brevicauda 22: 1-27
B.physalus 3: 132-190, 4: 184-209, 7: 125-183
B. borealis 4: 1-13
B. edeni 10: 133-141
B. acutorostrata 22: 75-125
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
S. coruleoalba 33 : 2 7-6 7
Platanista gangetica 24: 87-108, 26: 265-270
Pontoporia blainvillei 26: 265-270
Mirounga leomina 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
Physetercatodon 13: 135-153, 17: 15-35, 20: 1-16
Berardius bairdii 29: 1-20
Globicephala macrorhynchus 35: 57-91
Tursiops truncatus 32: 39-66
Stene/la ceruleoalba 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 blainvillei 31 : 45-67
Collorhinus ursinus 17: 191-195
Dugong dugon 30: 301-310
Phoca kurilensis 33: 131-135

Population study
Balaena mysticetus 35: 1-16
Eubalaena 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, II:
85-98, 12: 103-125, 13: 97-133, 13: 145-169, 15:

85-142, 17: 53-65, 18: 1-27, 18: 49-88, 34: 59-91
B. borealis 3: 119-131, 4: 27-113, 9: 89-103, 22:
63-74, 34: 59-91
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, 34: 59-91
B. acutorostrata 11: 1-37, 11: 181-189, 19: 37-43,
22: 75-125, 37-59, 35: 17-38
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,
1.9: 1-35, 20: 1-16, 23: 1-25, 35: 39-46:(,iphius cavirostris 10: 89-132, 24: 35-41
Berardius 27: 111-137
B. bairdii 10: 89-132, 13: 213-214, 23: 111-122,
29: 1-20
Odontoceti 34: 1-4 7
Oreinus area 13 : 85-96
Globicephala macrorhynchus 35 : 57-91
Globicephala 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:
65-115
S. aitenuata 26: 157-226, 26: 227-243, 28: 73-106
Lagenorhynchus obliquidens 35: 129-157
Lagenodelphis hosei 30: 231-244
Phocoenoides dalli 30: 1-64, 35: 93-105, 35: 107128
Neophocaena phocaenoides 31 : 1-44
Cephalorhynchus commersonii 32: 149-154
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, 33: 83-117
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
Color pattern, Phoca 25: 301-3.10
Growth, Phoca 24: 127-144
Foods, Phoca 34: 123-136
Pelage, Historiophoca 28: 187-197

iii
Occurrence, phocid seals 28: 175-185
Distribution, Phoca 31: 105-119
Dugong 31: 133-141
Trichechus 34: 137-147
Diving depth, Callorhinus 24: 145-148
Wandering speed, Erignathus 31: 121-123
Gerology 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: 4551, 20: 109-155, 34: 59-91
Balaena mysticetus 35: i-16
Balaenoptera borealis 22: 127-152, 22: 153-158, 25:
219-236, 25-144
B. edeni 7: 79-85, 29: 49-58, 32: 1-23
Megaptera novaeangliae 31 : 69-83
Eschrichtius robustus 22 : 39-43
Physetercatodon 5:81-90, 11: 139-151, 11: 153-161,
18: 111-122, 28: 145-151, 32: 199-218
Orcinus orca 29: 107-111
Stenella coeruleoalba 25: 265-275
Balaenopterids 32: 155-198, 34: 59-91
Largha Seal 34: 123-136
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 budge 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
4: 14-26, 11: 99-132, 13: 185-191, 29:
101-105, 32: 97-103
Cyamus 28: 153-160
Barnacle 22 : 39-43
White scar 10: 69-77, 26: 145-155
Skin di;ease 11 : 133-138
DiatomHelminthes 11: 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 1: 3-7
pancreas l: 8-10, 1: 11-14, 2: 55-60, 3:

71-78
Whale meat, peptone I: 15-16
freshness 1: 17-26, l: 28-30, 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 l: 38-40, 3: 96-101, 5: 41-47
Wale milk 10: 151-167
Vitamin 1: 31-37, 2: 35-41, 5: 53-59, 6: 187-191,

7:47-50
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: 213-221
Lipid, Eubalaena 18: 173-180
Fatty acid composition of oil,
Eubalaena 22: 165-170
Neopocaena 21: 131-135, 26: 303-306
Peponocephala 21: 137-141
Platanista 23: 141-147, 24: 117-125
Inia 25: 293-299
Trichechus 26: 307-311
Krill 28: 167-174
Metal, Dugong 31: 125-128
Organochlorine compounds, Dugong 31: 125-126
Kitol

MiscellaneousHybrid 34: 109-121
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
Jacobson's organ 33: 125-126
Dicephaly fetus 33: 127-129

iv
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
Aguilar, A. 33: 125-126
Akiba, T. 3: 63-70, 5: 1-4
Akikusa, S. 10: 151-167
Akiya, S. I: 3-7, I: 8-10, I: 11-14, 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
Beach, R. 35: 93-105
Best, P. B. 32: 97-103
Bou,J. 32: 145-148
Bowles, A. E. 35: 129-157
Brownell, R. L.Jr. 28: 127-128, 28: 129-129-135,
29: 101-105, 31: 45-67c
Calaprice, N. 17: 67-77
Casinos, A. 32: 145-148
Castello, H.P. 26: 255-258, 28: 119-126, 29:
107-111
Clarke, R. 30: 117-177
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
Dixon,J. M. 35: 159-164
E

ECG Research Group

15: 159-165
F

Fordyce, R. E. 35: 159-164
Frost, K.J. 35: 1-16
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
Fujise, Y. 33: 27-67
Fujiyama, T. 33: 27-67
Fukazawa, R. 3: 85-88, 3: 89-91, 3: 92-95, 5:
49-51
Furuta, M. 35: 195-197
G

Gianuca, N. M. 28: 119-126
Goodall, R.N.P. 30: 197-232
Goodrich, K. R. 35: 129-157
Grau, E. 33: 125-126
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: 153-165, 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
Hohn, A. A. 32: 39-66
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, (35: 199-203)
lgarashi, S. 21: 95-123
Iguchi, 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, II: 191-213,
13: 309-321
Ishimaru, K. 32: 97-103
Ishimaru, T. 29: 101-105
Itano, K. 31: 125-128
Ito, H. 35: 183-193
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: 167-174v

vi
Iwai, E.

11: 139-151, 11: 153-161

J
Jimbo, H. 3: 119-131
Jones, L. L. 35: 93-105, 35: 107-128
Jover, L. 33: 125-126
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
Kamiya, T. 12: 197-208, 13: 53-83, 13: 253-267,
14: 35-48, 19: 53-64, 19: 105-133, 21: 95-123,
23: 91-101, 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, 32: 105-126,
32: 127-144, 33: 69-81, 33: 127-129
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, 19:65-90.20:83-88,20:89-91,21: 1-27,
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:
109-115, 25: 1-103, 25: 265-275, ?6: 157-226,
26: 227-243, 27: 81-94, 27. 95-108, 28: 57--68,
28: 73-106, 28: 141-143, 29: 1-20, 29: 87-94, 30:
1-63, 30: 301-310, 31: 1-44, 31: 45-67, 31: 8592, 31: 133-141, 32: 67-95, 33: 1-26, 35: 57-91,
35: 107-128
Kataoka, T. 31: 129-132, 31: 133-141, 34: 137147
Kato, H. 31: 97-99, 31: 101-103, 33: 1-26, 34:
123-136, 35: 39-46
Kawai, S. 31: 125-128
Kawakami, T. 7: 79-85, 8: 147-213, 28: 145-151,
32: 199-218
Kawamura, A. 22: 75-125, 22: 127-152, 23: 2736, 23: 139-140, 25: 219-236, 26: 25-144, 27:
61-79, 28: 1-35, 29: 49-58, 29: 137-141, 30:
291-303, 32: 1-23, 32: 155-198, 34: 59-91
Kihata, M. 30: 311-313
Kimura, S. 9: 165-177, 10: 89-132, II: 39-46,
11: 181-189, 12: 103-125
Kijima, M. 5: 61-69
Kito, K. 35: 165-172
Klima, M. 30: 253-269
Kobo, F. 1: 15-16
Kojima, T. 6: 49-72
Komatsu, S. 29: 95-100, 30: 281-284, 30: 285-

290, 32: 127-144
Konno, S. 31: 105-109
Korostoff, E. 23: 103-110
Kureha, K. 24: 43-56, 27: 139-140, 31: 1-44
L

Leatherwood, S. 35: 129-157
Leung, Y. M. 28: 153-160
Lowry, L. F. 35: 1-16
Lugassy, A. A. 23: 103-110
M

Machida, S. 22: 163-164, 26: 271-287, 26: 289302, 27: 141-159
Maeda, T. 17: 1-14
Major, P. F. 31: 95-96
Masaki, Y. 22: 63-74, 22: 75-125
Matsui, S. 32: 67-95, 35: 57-91
Mattlin, R.H. 35: 159-164
McCann, C. 26: 145-155, 27: 111-137, 28: 107117
Mermoz, J. F. 32: 149-154
Mizue, K. 3: 106-118, 3: 119-131, 5: 71-79, 5:
81-90, 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, 33: 27-67, 33: 127-129, 35: 93-105
Mo!, 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, 31: 121123
Nakai, T. I: 17-26, I: 27-40, 1: 41-47, 2: 31-34,
6: 167-176, 6: 177-185, 14: 305-326
Nakajima, M. 17: 191-195, 19: 65-90, 19: 91104, 20: 101-107
Naruse, U. 17: 171-190, 18: 173-180
Nasu, K. 11: 163-179, 12: 91-101, 13: 193-199,
13: 211-212, 14: 137-143, 15: 143-158, 17: 8391, 17: 105-155, 20: 157-270, 22: 63-74, 25:
205-217
Natsume, Y. 3: 63-70, 5: 1-4
Nemoto, T. 10: 67-77, 10: 79-87, 11: 132, II:
181-189, 12: 33-89, 13: 97-133, 13: 185-191, 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:

vii
111-122, 19: 45-51, 20: 109-155, 21: 1-78, 22:
153-158, 23: 129-137, 27: 81-94, 29: 101-105,
30: 245-247, 32: 97-103
Nishimoto, S. 7: 79-85
Nishiwaki, M. 3: 132-190, 4: 115-161, 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, 11: 39-46, 12: 2332, 12: 191-192, 12: 193-195, 13: 53-83, 13: 8596, 13: 97-133, 13: 135-153, 13: 155-169, 14:35-48, 14: 49-87, 15: 1-16, 16: 19-28, 16: 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: 101-107,
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: 139-140, 29:
87-94, 29: 113-120, 30: 65-115, 30: 301-310, 31:
93-94, 31: 133-141, 34: 49-57, 34: 109-121, 34:
137-147
Norris, K. S. 20: 95-1000Ogawa, 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: 1784, 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: 1-2!1, 25: 237239
Ohta, K. _10: 151-167
Ohtaishi, N. 33: 131-135
Oishi, Y. 10: 15q-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, II: 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: 1-27, 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, 32: 25-37,

33: 1-26, 33: 119-124, 35: 183-193
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, 32: 105-126
Pivorunas, A. 28: 37-55
Praderi, R. 28: 129-135
R

Rabinowits, J. L. 23: 103-110
Reeves, R.R. 35: 129-157
Rice, D. W. 22: 39-43s
Saiki, M. 3: 79-84
Sakai, S. 7: 51-67
Sakiura, H. 11: 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, 35: 47-57
Sekino, T. 13: 269-301
Sergeant, D. E. 34: 1-47
Shida, T. I: 41-47, 3: 1-16
Shiraga, S. 33: 127-129
Shirakihara, M. 35: 183-193
Shokita, S. 34: 137-147
Singarajah, K. V. 35: 17-38
Soma, Y. 2: 35-41
Stewart, B. S. 35: 129-157
Sugiura, Y. 11: 133-138
Suzuki, T. 13: 215-229, 17: 49-52
T

Takahashi, K. 2: 51-54, 14: 89-100
Takahashi, Y. (Satake) 33: 119-124
Takano, H. 32: 97-103
Takao, M. 7: 37-46
Takemura, A. 23: 123-128
Tanzawa, T. I : 8-10
Tawara, T. I: 31-37, I: 38-40, 3: 85-88, 3:8991, 3: 92-95, 3: 96-101, 5: 49-51
Tejima, S. 1: 3-7, I: 8-10, 1: 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, 34: 109-121
Tokita, K. 15: 159-165

viii
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: 307-311, 28: 167174

uUchida, S. 22: 159-162, 31: 129-132, 34: 137-147
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, 33: 1· 26
Watar'., T. 10: 151-167

Watkins, W. A. 33: 83-117
Williamson, G. R. 25: 279-292, 27: 37-59
yYagi, T. 8: 133-146, 17: 191-195, 32: 127-144
Yamada, M. 2: 21-30, 8: 1-79, 9: 37-58, 9: 5988, 14: 291-304
Yamaguchi, K. 7: 69-77
Yamaguchi, M. 34: 137-147
Yamamoto, Y. 30: 249-251
Yamasaki, F. 26: 265-270, 28: 137-140, 29: 95100, 30: 283-286, 30: 289--292, 32: 127--144, 33:
69-81, 35: 165-172
Yang, H. C. 25: 251-·263
Yoneda, M. 33: 131--135
Yonekura, M. 32: 67-·95
Yoo, Y. 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: 49-52zZhao, Z. 35: 173-181
Zhou, K. 34: 93-108, 35: 173-181
Zhou, M. 35: 173-181

THE SCIENTIFIC REPORTS OF THE WHALESRESEARCH INSTITUTE

Editorial Board
HmEo OMURA; Editorial Director
MASAHARU NISHIWAKISEIJI OHSUMI
Tosmo KASUYA
TosmRo KAMIYAy ASUHIKO NAITO
General Secretary
HIDEHIRO KATOag ffl 59 ff. 3 A 15 a FP Ajllj
RH fll 59 ff. 3 A 30 a 56 :ff
ll:fEH~.A*mma tit .®l\ ~~1iJf 5"C*ffi'l!iliIJl't IK* .\¥; 3 T § 32 ii: 11 %t~*

1iJf 5"C t± FP Xi\IJ ~ :i:t ~ t±
J!'tffi'l!l\*1i-11'11Kt$~!0Cl T§ 2ji:fili

Printed by
Kenkyusha Printing Co.
Shinjuku-ku, Tokyo 162~lilli

Obtainable from Japan Publication Trading Co. Ltd.,
Sarugakucho, Chiyoda-ku, 1-2-1, Tokyo 101

4,000 F9