Cetacean Population Stwdies
V01日 3

DRttSEIJ1 0HSUMI MEMORIAL VOLUME
Publication Committee
for the Cetacean Population Studies

2021

CETACEAN POPULATION STUDIES
Online publication: ISSN 2434-558X
Print publication: ISSN 2434-5571
Copyright © 2021, Publication Committee for the Cetacean Population Studies
All rights reserved. Reproducing or copying this publication, in whole or in part, is prohibited without
the express written consent of the copyright holder.

Main Affiliation
Professor Emeritus, Tokyo University of Marine Science andTechnology
Motoi Y OSHIOKA, Chairman Alternate Professor, Mie University
Director General, Institute of Cetacean Research
Yoshihiro FUJISE
Former Director General, Fisheries Research Agency
Hiroshi HATANAKA
Koichi KAJI
Professor Emeritus, Tokyo University of Agriculture andTechnology
Noriyuki OHTAISHI
Professor Emeritus, Hokkaido University
Kazumi SAKURAMOTO
Professor Emeritus, Tokyo University of Marine Science andTechnology
Special Advisor, Okinawa Churashima Foundation
Senzo UCHIDA
Governing Council
Hidehiro KATO, Chairman

Editorial Board
Hidehiro KATO, Editor in Chief
Yoshihiro FUJISE, Editor
Hiroshi HATANAKA, Editor
Kazuhiko HIRAMATSU, Editor
Toshiaki ISHIBASHI, Editor
Koichi KAJI, Editor
Toshihide KITAKADO, Editor
Tomio MIYASHITA, Editor

Noriyuki OH TAISHI, Editor
Luis A. PASTENE, Editor
Kazumi SAKURAMOTO, Editor
Senzo UCHIDA, Editor

Associate Professor, Atmosphere and Ocean Research Institute,
The University of Tokyo
Chairman, Japan Aquarium Association
Professor; Tokyo University of Marine Science and Technology
Former Division Director, National Research and Development
Agency, Japan Fisheries Research and Education Agency,
Fisheries Resources InstituteHead of Science, Institute of Cetacean Research

Motoi Y OSHIOKA, Editor
Invited Editors: depending on editorial needs.
Secretariat
Gabriel GOMEZ DIAZ, Secretary
Tomoko KUBA, Editorial Officer
Kuniko TAKATAInternational Academic Publishing Co., Ltd.

Editorial correspondence shoud be sent to:
Editor, CPOPS
E-mail: cpopspaper@gmail.com
CPOPS is available online at https://cpops.jp/archive/index.html
Supporting organizations:
The Institute of Cetacean Research, TokyoJapan Aquarium Association, Tokyo

Cetacean Population Studies
Vol. 31930–2019

Volume 3, December 2021
DR.
SEIJIOHSUMIOHSUMI MEMORIAL
MEMORIAL VOLUME
DR.
SEIJI
VOLUME

Publicatiion
Committee
Publication Committee
for the Cetacean Population Studies
2021

Contents
Preface………………………………………………………………………………………………… 1
Foreword ……………………………………………………………………………………………… 3
Relevance of the scientiﬁc work on cetaceans of Dr. Seiji Ohsumi ………………………………… 5
Recollections of Dr. Seiji Ohsumi …………………………………………………………………… 9
Bibliography of the published works of Dr. Seiji Ohsumi ……………………………………………52
Collection of moments ………………………………………………………………………………83
Full paper
KATO, H., FUJISE, Y., NAKAMURA, G., HAKAMADA, T., PASTENE, L. A. and BEST, P. B.
Dwarf minke whales: Morphology, growth and life history based on samples collected from thehigher latitudes in the Southern Hemisphere …………………………………………………………93
PASTENE, L. A., GOTO, M., TAGUCHI, M. and MATSUOKA, K.
Genetic matches of southern right whales in the Indian sector of the Antarctic:
A Contribution towards understanding their movement and site-ﬁdelity ………………………… 129
OHASHI, Y., GOTO, M., TAGUCHI, M., PASTENE, L. A. and KITAKADO, T.
Evaluation of a paternity method based on microsatellite DNA genotypes for estimating
the abundance of Antarctic minke whales (Balaenoptera bonaerensis) in the Indo-Paciﬁcregion of the Antarctic …………………………………………………………………………… 139
TAGUCHI, M., GOTO, M., MILMANN, L., SICILIANO, S., TIEDEMANN, R. and PASTENE, L. A.
New insights into the genetic structure of sei whales (Balaenoptera borealis)at the inter-oceanic scale …………………………………………………………………………… 152
KATSUMATA, T., HIROSE, A., NAKAJO, K., SHIBATA, C., MURATA, H., YAMAKOSHI, T.,
NAKAMURA, G. and KATO, H.
Evidence of winter migration of humpback whales to the Hachijo island, Izu Archipelago oﬀ
the southern coast of Tokyo, Japan ………………………………………………………………… 164
TAKAHASHI, M., NAKAMURA, G. and KATO, H.
Growth-related changes in the cranium of killer whales in the western North Paciﬁc …………… 175
LOCKYER, C. and GARRIGUE, C.
Age estimation from teeth in Longman’s beaked whales (Indopacetus paciﬁcus) stranded
in New Caledonia (South Paciﬁc) ………………………………………………………………… 189

ISODA, T., MATSUOKA, K., TAMURA, T. and PASTENE, L. A.
Spatial and temporal distribution of ﬂoating marine macro debris in the Indo-Paciﬁc regionof the Antarctic …………………………………………………………………………………… 198
Short note
NAKAMURA, G., ZENITANI, R., BANDO, T., FUJISE, Y., YAMAMOTO, R., NISHIMURA, F.,
HIROSE, A., KIM, Y. and KATO, H.
Skeletal measurements on some large cetacean species done by scientists of TUMSAT and ICR…………………………………………………………………………………………………… 215
KIM, Y., NISHIMURA, F., BANDO, T., FUJISE, Y., NAKAMURA, G., MURASE, H. and KATO, H.
Fetal development in tail ﬂukes of the Antarctic minke whale …………………………………… 231
BANDO, T.
Improved estimates of some life-history parameters of the pelagic subspecies of Bryde’s whale in thewestern North Paciﬁc ……………………………………………………………………………… 239
MAEDA, H. and KATO, H.
Seasonal changes in the earplug germinal layers of North Paciﬁc common minke whales ……… 246
MATSUOKA, K., HAKAMADA, T. and MIYASHITA, T.
A note on recent surveys for right whales Eubalaena japonica in the western North Paciﬁc …… 252
DIALLO, S. T., SANE, A., NELSON, T., KATSUMATA, T. and HAKAMADA, T.
Cetaceans oﬀ Gabon based on a 2011 sighting survey, with a preliminary density estimate of the
humpback whale Megaptera novaeangliae ……………………………………………………… 258
SEKIGUCHI, K.
Historical Japanese whale sighting surveys in the Chukchi Sea…………………………………… 265
KATSUMATA, E., NARUSE, S., HOSONO, T. and KATSUMATA, H.
Sexual dimorphism in the dorsal ﬁn of Paciﬁc white-sided dolphins (Lagenorhynchus obliquidens)
from coastal waters oﬀ Japan ……………………………………………………………………… 273
KONISHI, K. and TAMURA, T.
Preliminary use of near-infrared spectroscopy to estimate the biochemical components of the musclesof the Antarctic minke whale Balaenoptera bonaerensis ………………………………………… 281
ISODA, T., TAMURA, T. and PASTENE, L. A.
Ingestion of marine debris and evidence of entanglements involving Antarctic minke whales(Balaenoptera bonaerensis) sampled in the Indo-Paciﬁc sector of the Antarctic ………………… 286

Review
AKAMATSU, T.
A short review of acoustic monitoring of large whales in Japanese waters ……………………… 297
KAJI, K.
Impact of whale resource management research on sika deer management ……………………… 301
OthersWALLØE, L.
Historical Records
An analysis of Japanese whale killing data with special emphasis on the use of the electric lance as asecondary killing method ………………………………………………………………………… 307
MIYAZAKI, N.
Remembering Dr. Seiji Ohsumi: A dream for establishing a research center of marine mammals
in the Indian Ocean ………………………………………………………………………………… 317
Archival Index …………………………………………………………………………………… 319
Subject Index ……………………………………………………………………………………… 321
Author Index ……………………………………………………………………………………… 323
Guide for Authors ………………………………………………………………………………… 326

目次

はじめに……………………………………………………………………………………………… 1
序文…………………………………………………………………………………………………… 3
大隅清治博士の歩み………………………………………………………………………………… 5
追悼メッセージ……………………………………………………………………………………… 9
大隅清治博士の業績リスト…………………………………………………………………………52
思い出グラフィー……………………………………………………………………………………83

論文
加藤秀弘、藤瀬良弘、中村玄、袴田高志、PASTENE L.A.、BEST P.B.
ドワーフ（矮小型）ミンククジラ：南半球高緯度域から得られたサンプルに基づく形態、成長および生活史特性………………………………………………………………………………93

PASTENE L.A.、後藤睦夫、田口美緒子、松岡耕二
南極海インド洋区におけるミナミセミクジラの遺伝的照合：
その移動と回帰性解明への貢献………………………………………………………………… 129
大橋優美、後藤睦夫、田口美緒子、PASTENE L.A.、北門利英
南極海のインド太平洋海域におけるクロミンククジラの資源量を推定するためのマイクロサテライトDNA遺伝子型に基づく父子鑑定法の評価 …………………………… 139
田口美緒子、後藤睦夫、MILMANN L.、SICILIANO S.、TIEDEMANN R.、PASTENE L. A.
大洋間スケールでのイワシクジラの遺伝構造に関する新しい推論………………………… 152
勝俣太貴、廣瀬亜由美、中條謙、柴田千恵理、村田陽菜、山越整、中村玄、加藤秀弘
伊豆諸島八丈島沖におけるザトウクジラの冬季回遊の証拠………………………………… 164
高橋萌、中村玄、加藤秀弘
北西太平洋産シャチ頭蓋骨の成長依存的変化………………………………………………… 175

LOCKYER C.、GARRIGUE C.
ニューカレドニアにおけるロングマンオウギハクジラの年齢査定………………………… 189
磯田辰也、松岡耕二、田村力、PASTENE L. A.
南極海のインド太平洋海域における浮遊性マリンマクロデブリの時空間的分布………… 198

短報
中村玄、銭谷亮子、坂東武治、藤瀬良弘、山本龍治、西村双葉、廣瀬亜由美 、KIM Y.、
加藤秀弘
東京海洋大学と日本鯨類研究所研究者が収集した大型鯨類の骨格計測値………………… 215
KIM Y.、西村双葉、坂東武治、藤瀬義弘、中村玄、村瀬弘人、加藤秀弘
クロミンククジラの胎児期における尾鰭の発達と変化……………………………………… 231
坂東武治
北西太平洋産沖合系ニタリクジラの生物学的特性値の改善………………………………… 239
前田ひかり、加藤秀弘
北西太平洋産ミンククジラ耳垢栓基部萌芽層の季節変化…………………………………… 246
松岡耕二、袴田高志、宮下富夫
北西太平洋における近年のセミクジラ発見状況……………………………………………… 252
DIALLO S. T.、SANE A.、NELSON T.、勝俣太貴、袴田高志
ガボン沖の2011年鯨類目視調査に基づくザトウクジラの予備的密度推定 ………………… 258
関口圭子
チュクチ海における日本の鯨類目視調査の年代的比較……………………………………… 265
勝俣悦子、成瀬紗恵子、細野透、勝俣浩
日本沿岸産カマイルカ背鰭の性的二型………………………………………………………… 273

小西健志、田村力
クロミンククジラの筋肉の生化学成分推定に向けた近赤外分光法の予備的使用………… 281
磯田辰也、田村力、PASTENE L.A.
南極海のインド太平洋海域におけるクロミンククジラのマリンデブリの取り込みと絡みつき……………………………………………………………………………… 286

レビュー
赤松友成
日本近海における大型鯨類音響モニターリングに関するショートレビュー……………… 297
梶光一
鯨類資源管理方式がニホンジカの管理に与えた影響………………………………………… 301

その他
WALLØE, L.
史料
電気ランスの使用に重点を置いた日本の調査捕鯨操業における二次的捕殺方式データの分析…………………………………………………………………… 307
宮崎信之
大隅清治博士の思い出：インド洋に海産哺乳類の研究センターを設立するという夢…… 317
著者及びタイトル索引…………………………………………………………………………… 319
件名索引…………………………………………………………………………………………… 321
著者索引…………………………………………………………………………………………… 323
執筆要領…………………………………………………………………………………………… 326

PREFACE
The ﬁrst issue of the Cetacean Population Studies (CPOPS), created with the aim of promoting cetacean research not only in Japan, but also internationally, was published in December 2018, carrying
on the spirit of the Scientiﬁc Reports of the Whales Research Institute, which had ceased publicationin 1988. The centerpiece of this eﬀort was the late Dr. Seiji Ohsumi, who unfortunately passed away
on November 2, 2019, as we previously announced in this journal. He was very keen to see this journal ﬂourish, but as it was still in the early days since publication of our ﬁrst issue, I felt truly overwhelmed when I realized that we could not show him the day.
At the “Memorial Service in Honor of the late Dr. Seiji Ohsumi” held on December 23, 2019, people from home and abroad gathered to commemorate him, and many scientists from around the world
also sent heartwarming messages. There was a spontaneous outpouring of voices from various people
present there who wanted to leave these messages as a remembrance of Dr. Ohsumi.
This CPOPS Vol. 3, in addition to the usual collection of research papers, includes such messages
and several chapters looking back at Dr. Ohsumi’s accomplishments as a memorial issue dedicated tohim. After ﬁnishing the editing, I reaﬃrmed my conviction that, while Dr. Seiji Ohsumi left many research achievements in various ﬁelds, the starting point was that of a cetacean biologist deeply rooted
in ﬁeld research. I can only hope that the foundation of this journal will remain the same. And I sincerely hope that this volume will reach Dr. Osumi in heaven.
In addition to the members of the publishing and editorial boards, many national and international
scientists have helped edit this volume. I am deeply grateful for their scientiﬁc contributions. I would
also particularly express my sincere gratitude to Dr. Gabriel Gomez Diaz, Ms. Tomoko Kuba and Ms.
Kuniko Takata of the CPOPS secretariat.
October 1, 2021

Hidehiro Kato
Chairman
Publication Committee for the Cetacean Population Studies

Cetacean Popul. Stud. (CPOPS), Preface
Vol. 3, 2021, 1

1

Foreword*
Remarkable evolution in cetacean studies in recent decades owes much to major journals that have madesigniﬁcant contribution to the development of modern cetology: Discovery Reports, published by the
National Institute of Oceanography in the United Kingdom, and Norwegian Whaling Gazette in Norway,
as well as The Scientiﬁc Reports of the Whales Research Institute in Japan.
The Scientiﬁc Reports of the Whales Research Institute was ﬁrst published in 1948, a year after the
Whales Research Institute was established. Aiming to share valuable research ﬁndings and scientiﬁcknowledge worldwide, the publication was formatted in English since its beginning, quite an ambitious
attempt in Japan still recovering from the devastation of World War II.
Since its ﬁrst publication, a total of 246 scientists contributed 419 scientiﬁc papers to The Scientiﬁc
Reports of the Whales Research Institute. It is widely acknowledged and appreciated that these scientiﬁcpapers were the foundation for the development of cetacean studies worldwide, and in today’s terms, it
was a research journal that had a signiﬁcant impact factor, or high number of citations. Regrettably, however, The Scientiﬁc Reports of the Whales Research Institute was discontinued in 1988 with the 39th
volume after the institute was reorganized into the Institute of Cetacean Research.
In the 30 years since then, various types of journals on cetacean studies have been published globally,each oﬀering diﬀerent perspectives on scientiﬁc research outcomes. As for Japan, no research journal
matching The Scientiﬁc Reports of the Whales Research Institute in its quality has been published. It is
probably because many domestic cetologists have sought to publish their papers in international research
journals based outside Japan.
As the global environment surrounding the issue of whaling became increasingly complex, we haveobserved a shift in publishing policies among these journals, rejecting papers whose ﬁndings are based on
speciﬁc research methods such as lethal sampling. Because of this, no small numbers of papers submitted by biological scientists using samples collected through lethal surveys, even just for some parts, havebeen denied proper reviews. While we agree that animal ethics should be given high priority when writinga research paper, if a paper, the research method of which is allowed under domestic and internationalrules, is rejected, it is a decision made beyond scientiﬁc judgment.
Our new journal for cetacean population studies intends to follow the scientiﬁc policy of The Scientiﬁc
Reports of the Whales Research Institute, that is, to contribute to global development of cetacean studies.
As long as submitted papers conform to scientiﬁcally-accepted animal ethics, we do not make distinctions
based on research methods. At the same time, to maintain the journal’s neutrality in the complex global
environment surrounding whaling issues, the journal will be published from a newly organized committee,
rather than as a bulletin type scientiﬁc report from a speciﬁc research institute. The title of the new journal will be Cetacean Population Studies to be abbreviated CPOPS, and we aim to keep our door wide-open
for researchers worldwide, contribute to the scientiﬁc development of resource studies for marine mammals especially focusing on cetaceans, and nurture many aspiring scientists.

December 31, 2018

Seiji Ohsumi, Ph. D.
Chairman
Publication Committee for the Cetacean Population Studies*Introductory declaration by the former Chairman of the Cetacean Population Studies Publication Committee on the occasion of the launching of this journal.

3

RELEVANCE OF THE SCIENTIFIC WORK OF SEIJI OHSUMIRELEVANCE OF THE SCIENTIFIC WORK ON
CETACEANS OF DR. SEIJI OHSUMILuis A. PASTENE and Hidehiro KATO
Institute of Cetacean Research, Toyomi-cho 4–5, Chuo-ku, Tokyo 104–0055, Japan

Dr. Seiji Ohsumi, ‘Seiji’ as he was known by colleagues and friends, passed away on 2 November
2019 at the age of 89 years. It was a sad day for his family, friends and for all of us who knew andworked with him; without a doubt it was a sad day for cetacean science as well. During his memorialservice held on 23 December 2019, many messages were received from colleagues and friends fromboth Japan and abroad. Most of those messages mentioned Seiji as a kind and true gentleman, a person that enjoyed meeting people at social events, a great cetacean scientist, and a person whose energy
and enthusiasm for research remained undiminished until the end. We agree with that characterizationof Seiji very much.
Seiji was a skilled debater with a deep command of the scientiﬁc issues. His opinions were always
based on updated knowledge and good scientiﬁc information, and he strongly defended his ideas.
During the meetings, people could have passionate discussions and disagreements with him over someissues. However, he never became angry and it was common to see Seiji outside the meetings displaying great courtesy to those same colleagues. Seiji enjoyed social events including parties very much,and saw those events as opportunities to hear and learn from people from diﬀerent research areas,
cultures or countries. At the very domestic level he saw the small parties as an opportunity for younger
people to express their opinions, knowing that they were unable to express such opinions in more formal meetings.
Here we would like to focus on the scientiﬁc work conducted by Seiji. First, we brieﬂy outline his
professional career and then we highlight some of his most relevant scientiﬁc contributions.
Brief outline of professional career• Born on 12 July 1930 in Gunma Prefecture, Japan.
• Graduated in 1948 from the Science Course at the Niigata Public High School under the former educational system.
• Completed pre-graduate studies in 1951 at the Faculty of Agriculture, the University of Tokyo.
• Published his ﬁrst study in English in 1954 in collaboration with some colleagues. The study was
titled ‘On the sexual maturity of the sei whale of the Bonin waters’ under his original name Seiji
Kimura (Nishiwaki et al., 1954).
• Completed post-graduate studies in 1958 at the Faculty of Agriculture, the University of Tokyo. The
title of his doctoral dissertation was ‘A study on age determination of the ﬁn whale’ (Ohsumi, n.d.).
• Became a member of the Whale Research Institute (WRI) in 1958. In his early days at the WRI, Seiji
was mainly engaged in ﬁeld work at numerous places where commercial whaling occurred as well inlaboratory work and analyses of samples he collected. In this period, he worked under the supervision of the late Prof. Masaharu Nishiwaki and Dr. Hideo Omura.
• Became a member of the Population Dynamics and Statistics Division of the Tokai Regional Fisheries Research Laboratory in 1966.
• Became Head of the Unit for Cetacean Population Studies at the government’s Far Sea Fisheries Research Laboratory (FSFRL) in 1967.
• Became Director General of the FSFRL between 1988 and 1991.
• Became a member of the board of directors of the Institute of Cetacean Research (ICR) in 1991.
• Became Director General of the ICR between 1995 and 2003.
Cetacean Popul. Stud. (CPOPS)
Vol. 3, 2021, 5–8

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PASTENE AND KATO

• Became a Senior Scientiﬁc Adviser of the ICR in 2004.
• Became Adviser Emeritus at the ICR from 2015 until he passed away in 2019.
Scientiﬁc contributions
Seiji was a proliﬁc researcher with over 700 scientiﬁc articles and publications on cetacean biology
and ecology, conservation and management, and whaling issues, among other subjects. He regularlypresented his work at scientiﬁc meetings as well as in public forums.
Apart from his specialized scientiﬁc publications and lectures in the ﬁeld of natural and appliedscience that targeted scientists, he considered it important that the general public was aware of cetacean conservation and management, and consequently spent considerable time preparing articles andtalking to the general public on those topics. He was especially skilled at writing and talking in a waythat was understandable for diﬀerent kinds of audiences. This is reﬂected in the large number anddiversity of his written publications and articles on cetaceans, whaling, whale conservation and management, and whale food culture, prepared during his productive life (see also his bibliography in thisissue):• Specialized papers published or presented at scientiﬁc meetings: 286• Books and book contributions: 58• Reports and booklets: 40• Geiken Tsushin (Whales Research Institute/Institute of Cetacean Research (WRI/ICR) Quarterly
Newsletter published in Japanese since 1948): 100• Miscellaneous: 257
Some relevant studies
The scientiﬁc work of Seiji was mainly focused on the assessment and management of large whales
as well as with the natural history of this group of animals.
Seiji conducted the work on assessment and management largely in the context of the work of the
Scientiﬁc Committee of the International Whaling Commission (IWC/SC), the international organization in charge of the conservation and management of the large whales. The IWC/SC is recognized as
the most skilled group of specialists in the ﬁeld of whale assessment and management, and Seiji was
one of its leading members for over ﬁve decades. Seiji was engaged in the assessment and management of several large whale species, including ﬁn (Balaenoptera physalus), sei (B. borealis), Bryde’s(B. edeni), common minke (B. acutorostrata), Antarctic minke (B. bonaerensis), and sperm (Physeter
macrocephalus) whales of both hemispheres. Seiji’s contributions to the biological knowledge andassessment of these species were enormous, and these contributions are reﬂected in many publicationsin the specialized journal of the IWC.
As in other groups of marine living resources, age and reproductive data are essential for assessment through the application of population dynamic models. Seiji not only applied models to assess
diﬀerent populations and species of large whales but also investigated the scientiﬁc basis of some ofthe essential data used in those models. One of the most remarkable examples is the work he conducted to determine the age of ﬁn whales based on their earplugs (Ohsumi, 1964).
By the time of the publication of this work, several approaches were available to estimate the ageof the ﬁn whale, namely body length, stage of growth, number of ovulations, white scars (Mackintosh and Wheeler, 1929); baleen plates (Ruud, 1940); crystalline lens (Nishiwaki, 1950), and earplugs (Purves, 1955). Seiji believed that the laminations found in the core of earplugs were the best
approach to determine age because the laminations were considered to form periodically and were
present in both males and females throughout the whale’s lifespan and earplugs are relatively easy tocollect and prepare for reading (Ohsumi, 1964).
The main scientiﬁc question at that time was on the frequency of deposition of the earplug lami-

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RELEVANCE OF THE SCIENTIFIC WORK OF SEIJI OHSUMI

nations, which was considered to be biannual (Laws and Purves, 1956). Seiji examined this matterin further detail by using biological material of a number of ﬁn whales taken in both the Antarctic
and the North Paciﬁc. He used three approaches to address the question above: examination of age
characters from recaptured whales (mark-recaptured whales), comparison of results among diﬀerent
approaches, and an examination of the population dynamics on the age composition based on earplug
laminae readings.
After detailed analyses and examination he stated the following: that ‘it will be concluded that theannual accumulation rate of earplug lamination must be less than two, probably near one, and averageannual ovulation rate will be under one, probably near 0.5, although there are individual and racial
variations. In addition, the average age at sexual maturity will be older than 5 years, probably 9–11
years. Of course, there are individual variations in the age of sexual maturity’ (Ohsumi, 1964).
The conclusions above regarding the annual deposition rate of earplug laminations had strong implications for the assessment and management not only of ﬁn whales but of several other balaenopterid species where earplugs were subsequently used for determining the age, e.g., Antarctic minke
whales. In his 1964 publication, Seiji recommended that ‘the standardization of the reading of earplug
lamination should be established….’. Subsequent work on Antarctic minke whales and other species
have beneﬁted from the early studies of Seiji, and standardization has been conducted thoroughly inrecent years. Age data based on earplugs have also been very useful in the calibration of molecularmethods being developed to determine age in the Antarctic minke whales.
In the ﬁeld of natural science there are many contributions from Seiji not only on large baleen
whales but also on odontocetes. Here we would like to highlight the investigation he made on theschool structure of sperm whales (Ohsumi, 1971).
Ohsumi (1971) studied the structure of sperm whale using biological information obtained fromthree complete schools taken in coastal waters of Japan (1) and pelagic waters of the Southern Hemisphere (2). Information examined included the number of whales forming a school, size distribution,
sex ratio, sexual maturity, physical maturity, age distribution and sexual condition of whales which
form a school.
Based on detailed analyses, Seiji proposed the following hypothesis on the formation of sperm
whale schools, in which the behavioral foundation of sperm whales is considered to be a maternalfamily group.
• The fundamental form of a sperm whale school is the ‘nursery school,’ which is composed of mature
females and calves nursed by mature females.
• Immature males and females are also nursed by mature females until the time of sexual maturity.
• The average size of school was estimated to be 27.1 whales, and half of them are mature females.
• A nursery school moves as a tightly united school and remains as a family for long time.
• Some immature whales leave the nursery school after weaning to form ‘juvenile schools.’• After attainment of puberty, all males gradually leave the nursery school. Males at puberty form
‘bachelor schools.’• Socially mature males or bulls form a small ‘bull school’ or live alone. Most bulls are considered tolive as solitary animals.
• Bulls struggle with each other to join a nursery school in the breeding season, and the winning bulland the nursery school form the so-called ‘harem.’
Seiji also estimated that the number of mature females served by a bull in a harem was 14 on average.
This study was not only important in understanding the natural history of sperm whales but it wasalso useful for their assessment. In particular, parameters important for assessment include the numberof mature females with which a bull mates and the ratio of number of males/mature females; information on both was obtained in Seiji’s study (Ohsumi, 1971).
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PASTENE AND KATO

Special awards
His scientiﬁc and dissemination work on cetaceans and whaling was recognized with numerous
awards including the following:• The Order of the Sacred Treasure, Gold Rays with Rosette (2002).
• The Royal Norwegian Order of Merit (2006).
• Special Award of the Mammal Society of Japan (2011).
Some ﬁnal thoughts
Seiji’s scientiﬁc contribution to the knowledge of cetaceans is enormous. He made contributions
not only in the ﬁeld of basic biology and ecology of cetaceans but also contributed substantially inthe assessment of several species, which was translated into appropriate policies of conservation andmanagement. He was a hard worker in the ﬁeld, in the laboratory (Fig. 1), in the analyses, and in the
preparation of scientiﬁc communications. He was very skilled at expressing his ideas and studies
through written and oral presentations, which were understandable to diﬀerent audiences. We were
fortunate not only to share with him the same institute and discuss together research plans and results,
but also share social events that Seiji enjoyed very much. In particular many colleagues and friends
with Japanese knowledge appreciated his beautiful Japanese sentence expressions. His enthusiasm forthe study of cetaceans was evident throughout his life as he was assisting the ICR until the very last
moment before his death. His enthusiasm, energy, productivity and courtesy should be an example forthe younger cetacean scientists, especially for those working at the ICR.
References
Laws, R. M. and Purves, P. E. 1956. The ear plug of the Mysticeti as an indication of age with special reference to the North
Atlantic ﬁn whale. Norsk Hvalfangst-Tid. 45 (8): 413–425.
Mackintosh, N. A. and Wheeler, J. F. G. 1929. Southern blue and ﬁn whales. Discovery Rep. 1: 257–540.
Nishiwaki, M. 1950. Determination of the age of Antarctic blue and ﬁn whales by the colour changes in crystalline lens. Sci.
Rep. Whales Res. Inst. 4: 115–161.
Nishiwaki, M., Hibiya, T. and Kimura, S. 1954. On the sexual maturity of the sei whale of the Bonin waters. Sci. Rep.
Whales Res. Inst. 9: 165–177.
Ohsumi, S., n.d. A study on age determination of the ﬁn whale. Doctoral Thesis, The University of Tokyo. UTokyo Repository. doi: 10.15083/00078951.
Ohsumi, S. 1964. Examination on age determination of the ﬁn whale. Sci. Rep. Whales Res. Inst. 18: 49–88.
Ohsumi, S. 1971. Some investigations on the school structure of sperm whales. Sci. Rep. Whales Res. Inst. 23: 1–25.
Purves, P. E. 1955. The wax plug in the external auditory meatus of the Mysticeti. Discovery Rep. 27: 293–302.
Ruud, J. T. 1940. The surface structure of the baleen plates as a possible clue to age in whales. Hvalrådets Skrifter 23: 1–24.

Fig. 1.

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Dr. Seiji Ohsumi counting growth laminae in a whale earplug at ICR (August 5, 2010).
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RECOLLECTIONS OF DR. SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMI
Yong-Rock AN
Cetacean Research Institute, National Fisheries Research and Development Institute,
139–29, Maeam-dong, Nam-gu, Ulsan, Republic of Korea

It is a great honor to remember the life of the late Dr. Oshumi. We have lost the extraordinary life of
this remarkable man who devoted his whole life to Cetology.
The ﬁrst time I met him was when we entered Ishinomaki Port after the JARPN II research cruisein 2003. My ﬁrst impression of him was that of a very gracious and gentle man, but when we talked
about whale research, his eyes were full of energy.
I understand that he and my Japanese leaders and colleagues fully supported me to prepare my
post-doctoral study on Cetology. But I gave up the great opportunity to study whales in Japan because
at about the same time I got a job as a whale researcher of the Cetacean Research Institute (CRI) in
Korea. Nevertheless, he still congratulated and encouraged me.
Dr. Oshumi was always energetic and very active when I met him at the IWC Scientiﬁc Committeeor the related workshops. He was my great teacher with more extensive experience and deeper knowledge on Cetology than anyone else. Also, he was very interested in the policies and issues of whalingin Korea as well as my research activity.
The citizens of Ulsan, the venue for the 57th IWC meeting in 2005, know him very well because heparticipated in the Whale Festival several times and gave valuable lectures on Cetology and whaling
culture. I believe their thoughts and prayers are with his bereaved family and colleagues.
Great man, great loss. I will always be grateful for his contributions to whale research and mentorship. I am missing already his smile and clapping in Kanto style.
Rest in peace Oshumi-sensei.

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RECOLLECTIONS OF SEIJI OHSUMIIN MEMORY OF DR. SEIJI OHSUMI
Arne BJØRGE and Tore HAUG
Institute of Marine Research, Nordnesgaten 50, Bergen, Norway

It was with great sadness that we received the message that Dr. Seiji Ohsumi passed away November 2, 2019. We learned to know and admire Dr. Ohsumi at the Scientiﬁc Committee (SC) of the International Whaling Commission (IWC), where he participated as a leading scientist over a period of
more than half a century and chaired the Japanese delegation in the 1990’s.
Dr. Ohsumi had an interest in, and great knowledge of, a variety of scientiﬁc aspects of the biology, ecology and management of cetaceans. He published strange details and curiosities such as theﬁnding of visible hind limbs in striped (Stenella coeruleoalba) and bottlenose (Tursiops truncatus)
dolphins (Ohsumi, 1965; Ohsumi and Kato 2008) and the virginal membrane in large rorquals(Ohsumi; 1969). But his most important achievements were on the life history, in particular age determination, of a number of species (e.g., Nishiwaki, Hibiya and Ohsumi, 1958a, 1958b; Ohsumi,
Kasuya and Nishiwaki, 1963; Ohsumi, 1964) and his revolutionary studies into the social life of the
sperm whale (Physeter macrocephalus, Ohsumi, 1971). In recent years during the special permit
whaling, his interests were also devoted to the ecological role of cetaceans, especially their feeding
habits and consumption, and their role in the ecosystem (Tamura and Ohsumi 2000; Fujise, Hatanaka,
and Ohsumi 2010). His publication record spans more than six decades and covered species from thesmall Dall’s porpoise (Phocoenoides dalli) to the great blue whale (Balaenoptera musculus).
Dr. Ohsumi was one of the most respected members of the IWC/SC. Although members of the SC
could have diﬀerent views on a number of issues, all participants listened carefully when Dr. Ohsumi
spoke. His impressive publication record and his life-long experience from surveys at sea, laboratory
work and advanced theoretical studies in the oﬃce, made him an authority within the SC. His knowledge combined with a well-developed sense of humour made him also one of the best debaters in the
SC. And we all loved his funny speeches every year at the traditional dinner party following the closing session of the SC. Dr. Ohsumi will be deeply missed.

References
Fujise, Y., Hatanaka, H. and Ohsumi, S. 2010. Changes in the Antarctic marine ecosystem as revealed by the JARPA
research: What has happened to the Antarctic minke whale stocks? Ottar (Tromsø Museum) 280: 29–34.
Nishiwaki, M., Hibiya, T. and Ohsumi (Kimura), S. 1958a. Age study of sperm whale based on reading of tooth laminations.
Sci. Rep. Whales Res. Inst. 13: 135–153.
Nishiwaki, M., Hibiya, T. and Ohsumi (Kimura), S. 1958b. Age study of ﬁn whale based on ear plug. Sci. Rep. Whales Res.
Inst. 13: 155–169.
Ohsumi, S. 1964. Examination on age determination of the ﬁn whale. Sci. Rep. Whales Res. Inst. 18: 49–88.
Ohsumi, S. 1965. A dolphin (Stenella caeruleoalba) with protruded rudimentary hind limbs. Sci. Rep. Whales Res. Inst. 19: 135–136.
Ohsumi, S. 1969. Occurrence and rupture of vaginal band in ﬁn, sei and blue whales. Sci. Rep. Whales Res. Inst. 21: 85–94.
Ohsumi, S. 1971. Some investigations on the school structure of the sperm whale. Sci. Rep. Whales Res. Inst. 23: 1–25.
Ohsumi, S., Kasuya, T. and Nishiwaki, M. 1963. The accumulation rate of dentinal growth layers in the maxillary tooth of
the sperm whale. Sci. Rep. Whales Res. Inst. 17: 15–35.
Ohsumi, S. and Kato, H. 2008. A bottlenose dolphin (Tursiops truncatus) with ﬁn-shaped hind appendages. Mar. Mamm. Sci.
24(3): 743–745.
Tamura, T. and Ohsumi, S. 2000. Regional assessments of prey consumption by marine cetaceans in the World. Paper SC/52/E6
presented to the IWC Scientiﬁc Committee, June 2000 (unpublished). 42 pp. [Paper available from the Oﬃce of the IWC].

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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI
Robert L. BROWNELL Jr.
Former Chair of the IWC Scientiﬁc Committee, Southwest Fisheries Science Center, NOAA, USA

Seiji lived a wonderful life and was a great scientist. When Dr. Omura died, I attended his service
and there were many people present, including Seiji. During the service, Seiji said to me that “I hopethat when I die this many people will attend my service ‘to pick my bones’”. As it turned out, thenumber of people at the memorial ceremony for Seiji on 23 December 2019 far exceeded the numberthat attended Omura’s service. Seiji was a great help to me when I was doctoral student at the Ocean
Research Institute, University of Tokyo. So that I could survive as a non-working student in 1974, Seiji arranged for me to be Visiting Biologist at the Far Seas Fisheries Research Laboratory in Shimizu
via a Japanese Government Research Award for Foreign Specialists.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMI
Doug BUTTERWORTH
Professor Emeritus, Department of Mathematics and Applied Mathematics, University of Cape Town,
South Africa

I ﬁrst met Seiji in late 1980 at an IWC workshop held in Seattle, during which he invited me to partake in what was my ﬁrst sushi meal. The workshop was held to discuss how best to develop estimatesof whale abundance from sighting surveys. This topic had come into prominence as a key componentof the IWC’s International Decade of Cetacean Research, whose ﬂagship programme was annual minke whale assessment surveys in the Antarctic. Seiji was co-convenor of the programme together with
my own colleague, Peter Best, and this soon led to many visits to Japan to participate in the meetings
that planned these surveys. Seiji would chair these in his customary friendly style, but also took responsibility for organising hospitality for the foreign guests outside meetings’ hours. Thus, it was Seiji
who took me on my ﬁrst “tourist trip” around Tokyo, including Tokyo Tower and the Meiji Shrine,
and the evenings would often encompass a visit to his favourite robatayaki bar in Shinjuku with its
large badger statue outside. Seiji was a great host, and when on one occasion some on my relatives
accompanied me on a visit to Tokyo, he insisted on according us the rare privilege of a visit to his own
home in Shinjuku. Fortunately, on that occasion we managed to get there without becoming lost in the
cavernous underground malls of Shinjuku station, something even Shinjuku-resident Seiji would admit had sometimes happened indeed to him.
For many decades Seiji served as the leading Japanese whale scientist, representing his views andcountry faithfully and eﬀectively in the cauldron that was the IWC Scientiﬁc Committee during thosetimes, as well as tabling the outcomes of his often-substantial studies in that forum. In debates there
he frequently clashed with arch-anti-whaler Sidney Holt on a host of issues, gamely responding ininterchanges that would play on the subtleties of the English language which, unlike for him, was themother tongue of his opponents and gave them an undue advantage.
My abiding recollection of Seiji will be of his unchanging pleasant and friendly nature. After hisretirement, he would still come through regularly to his work-space at the Institute of Cetacean Research. A visit there would always include catching up with him, when he’d enthusiastically explain
what research issue he was working on at the time. Like the late John Bannister, with whom he sharedso many IWC/SC meetings, he was the epitome of a gentleman.

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RECOLLECTIONS OF SEIJI OHSUMICONDOLENCES ON THE PASSING OF
DR. SEIJI OHSUMI
Phillip CLAPHAM
Alaska Fisheries Center, National Marine Fisheries Service, NOAA,
7600 Sand Point Way NE, Seattle, WA, USA

On behalf of my wife and myself, please accept our sincere condolences for the passing of thegreat Seiji Ohsumi. It is a very sad day. Seiji’s scientiﬁc contributions were large, but I will always
remember him for his gentle nature and his kindness. We often disagreed at the IWC, but my wife andI always enjoyed our conversations with him, and he always displayed a great courtesy to everyone.
He will be missed.
Very sincerely,
Phillip Clapham and Yulia Ivashchenko

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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI
Doug DEMASTER
Former Chair of the IWC Scientiﬁc Committee, and Director, Alaska Fisheries Science Center, NOAA, USA

In the Alaska Native culture, elders are greatly respected for their wisdom and civility. At the IWC
Scientiﬁc Committee, while I was chair, I greatly appreciated Dr. Ohsumi’s contributions to our deliberations. He was one of our elders. His comments reﬂected considerable experience and knowledge
regarding whales and whaling. He was an elder to be respected. I was very grateful to him for his consistent support of Alaska Native subsistence hunters.
With my deep regards,
Doug DeMaster

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RECOLLECTIONS OF SEIJI OHSUMICONDOLENCES ON THE PASSING OF
DR. SEIJI OHSUMIGreg DONOVAN
Former Head of Science, International Whaling Commission, Cambridge, UK

I was so sorry to hear of the news of the death of Seiji. He was a great man and one of the kindest
senior scientists as I began my cetacean career 42 years ago and remained a true gentleman throughout
the years. His knowledge of cetacean biology, especially of the large whales was unparalleled and hisenergy and enthusiasm remained undiminished until the end—an example to all of us. Please pass mysincere condolences to all my Japanese colleagues and especially those at ICR.
With best wishes
Greg

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RECOLLECTIONS OF SEIJI OHSUMIHOMAGE TO DR. SEIJI OHSUMI
Yoshihiro FUJISE
Director General, Institute of Cetacean Research, 4–5 Toyomi, Chuo-ku, Tokyo, Japan

Dr. Seiji Ohsumi joined the Institute of Cetacean Research (ICR) in 1991, and from December 1995
to January 2004 he was in charge of the operation of the Institute and the guidance of the staﬀ as its
director-general. In addition to his scientiﬁc accomplishments as a researcher with more than 700
papers, he was interested in everything related to whales, including whale culture and whales as food,and attended many relevant meetings and never stopped being interested in these things. Especiallyon the research side, he constantly inspired young researchers with various ideas. Further, the spirit oftaking good care of food has been passed on to the institute’s staﬀ with the catchphrase “You would
be scolded by Dr. Ohsumi if you leave the food you are served.” In addition to paying homage to theteacher who pursued his dream throughout his life, I think many of us would like to live such a life.
Ohsumi-sensei, I’m really thankful to you.

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RECOLLECTIONS OF SEIJI OHSUMIMEMORIES OF SEIJI OHSUMIRay GAMBELL
Former Secretary to the International Whaling Commission (1976–2000),
Green End, Landbeach, Cambridge, CB25 9FD, UK

Seiji Ohsumi was already an important ﬁgure in the world of whale research when I entered thisﬁeld in the early 1960s. It was a time of great international pressure to halt the over-catching and decline of whale populations, particularly in the Antarctic. Research on the basic biology and lives of thegreat whales had been carried out by scientists, mainly from the whaling nations, since the beginningof the Antarctic whaling industry at the beginning of the century. Thus, Japan had a history of such endeavours, and Seiji built on and expanded this knowledge base by his own research.
I was fortunate therefore to work with Seiji, and whale biologists from a rather small group of countries, to bring together the research we carried out on these fascinating and commercially valuable animals. We met at the annual meetings of the Scientiﬁc Committee of the International Whaling Commission, at special meetings and working groups around the world, to bring together our knowledge
on speciﬁc species or populations. We also socialised outside the working hours!
The new science of ﬁsheries population dynamics and the regulation of ﬁsheries was brought tobear on the whaling problem in the 1970s. This required all the available catch statistics and relevant
biological information such as growth, age and mortality of the diﬀerent species and populations to be
combined together for analysis. Seiji joined with scientists from other nations to pool these data andprepare them for mathematical analysis.
Despite the pressures of these meetings, Seiji was always a charming and approachable colleague.
We kept in touch after I retired in the year 2000 and exchanged cards and news at Christmas. His last
message to me was “I go into the oﬃce every day—I have no other interest.”

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RECOLLECTIONS OF SEIJI OHSUMISOME WORDS FOR DR. SEIJI OHSUMIJohn “Craig” GEORGE
Wildlife Biologist (retired), North Slope Borough, Department of Wildlife Management, Utqiaġvik, Alaska, USA

It is an honor to oﬀer some words for Dr. Seiji Ohsumi. Like many classically trained whale biologists of his time, Ohsumi understood whales “inside and out.” He was knowledgeable about their anatomy, physiology, population dynamics, marine ecology, whaling history and more.
While editing and writing the recently published book “The Bowhead Whale: Biology and Human
Interactions”1 I carefully reviewed the report Black Right Whales of the North Paciﬁc by Ohsumi andcolleagues2. I was astonished at the detail and sheer volume of work they did on this species. I was
also impressed that the North Paciﬁc right whales are more similar anatomically to their bowhead
cousins than I previously realized; this has important implications to the bowheads’ response to climate warming.
Equally important to being an outstanding whale biologist, Seiji Ohsumi was a gentleman. His conduct at the IWC Scientiﬁc Committee (SC) meetings was always digniﬁed and respectful even during
the many heated debates. I particularly valued his insights on the feeding ecology, reproductive biology, and health assessment of large whales.
I always enjoyed his words at the SC banquet and was impressed by his uncanny oratory skills in
English which were far better than my own. He would give a toast or tell a story usually following
John Bannister’s silly Australian “dunny” joke. He would often say, “I don’t understand British humor, but I enjoyed your story nonetheless.” Thanks for your honesty, Seiji, no one really understands
British humor!
At the IWC meeting in Anchorage he indicated that would like to taste bowhead whale. With thehelp of an Inupiat friend, we shared some agviq (bowhead) Japanese style with soy sauce and wasabi.
It was a nice moment as he expressed his impressions and reverence for the whale. I considered Seiji
a great friend and greatly miss him. I feel honored to carry on the type of work he did on large whale
biology.

George, J. C. and Thewissen, J. G. M. (Eds.), 2020. The Bowhead Whale, Balaena mysticetus: Biology and Human Interactions. 1st Edition. Elsevier/Academic Press, 668 pp.
2
Omura, H., Ohsumi, S., Nemoto, T., Nasu, K., and Kasuya, T. 1969. Black right whales in the North Paciﬁc. Sci. Rep.
Whales Res. Inst. 21: 1–78.
1

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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI
Hiroshi HATANAKA
Adviser Emeritus, Institute of Cetacean Research, 4–5 Toyomi, Chuo-ku, Tokyo, Japan

Dr. Ohsumi was a man who walked the straight and narrow path of whale research. He used to saythat “my occupation is whale research and my hobby is also whale research” and he never gave asecond thought to this path. Nearly 30 years ago, I got to work with whales under the guidance of Dr.
Ohsumi, and I was amazed at the breadth and depth of his knowledge of whales. I had the opportunity
to travel abroad with him and he was highly regarded and respected by foreign scientists as well.
In the midst of post-war food shortages, we Japanese were on the verge of starvation and, eversince, Dr. Ohsumi kept consistently conducting and leading research to promote the use of cetacean
resources to provide animal protein and establish their sustainable use on a scientiﬁc basis.
Now that Dr. Ohsumi has passed away, I am immersed in a sense of loss of an excellent leader anda feeling of loneliness for losing an unparalleled friend.

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RECOLLECTIONS OF SEIJI OHSUMIMOURNING DR. SEIJI OHSUMI
Yoshihiro HAYASHIFormer President, National Museum of Nature and Science, 7–20 Ueno Park, Taito-ku, Tokyo, Japan

Dr. Ohsumi was a person who never wavered. Although he was 16 years my senior, whenever wemet, he always had a smile on his face and spoke in a way that made me feel no age diﬀerence. The
fact that we studied at the same university, though we were in diﬀerent departments, and that ourbirthdays were on the same day, July 12, may have been the reason why I felt particularly close tohim. Likewise, Dr. Ohsumi’s doctoral dissertation was on the establishment of an age assessment
method for ﬁn whales, while my theme was the geographical variation of wild boars, and I needed an
accurate age assessment to compare wild boars from diﬀerent regions. It is said that the age of whales
can be accurately estimated even at 100 years old by the annual rings formed on their earwax plugs,
but wild boars’ age can only be read up to 10 years at most due to the annual rings formed in the
cementum of their posterior molars. However, since both ﬁn whales and wild boars are mammals, I
remember Dr. Ohsumi’s thesis being very helpful for my research.
It was only after I was dispatched to the Southern Ocean as a veterinarian during the 1978–79
whaling season, when the International Whaling Commission (IWC) asked the Fisheries Agency for“an accurate estimation of killing time of Antarctic minke whales” that I became able to talk closelywith Dr. Ohsumi. He was always present in the Japanese delegation’s waiting room at the annual IWC
meetings held at Cambridge University in the UK, Germany, St. Kitts and Nevis, Mexico, and so on.
It is thanks to our predecessors that Japan has been able to play an active role in the international community as a sound, unwavering whaling nation, and Dr. Ohsumi was undoubtedly one of our country’s
foremost ﬁgures in this ﬁeld.
May he rest in peace.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTION OF SEIJI OHSUMI
Kazuhiko HIRAMATSU
Associate Professor, Atmosphere and Ocean Research Institute, The University of Tokyo,
5–1–5 Kashiwanoha, Kashiwa, Chiba, Japan

When I got a job at the National Research Institute of Far Seas Fisheries in April 1984 and was
assigned to the High Latitudes Oceanography Section, Oceanography and Southern Ocean Resources
Division, the division leader was Dr. Seiji Ohsumi. He was my boss's boss. I did not have much opportunity to talk to him because he was promoted to the Research Planning and Coordination Division
in a little over a year, but I was impressed with his aggressive appearance. He was already in his mid50s at that time.
After that, he was the Director General of the National Research Institute of Far Seas Fisheries andthere was not much contact between an ordinary researcher and the director. But one day, I was called
into the director's oﬃce and wondered what was going on. He introduced me to a matchmaking. I declined politely because the marriage was decided just before, but it seems that there was also an aspectof taking care of staﬀ who are unlikely to get married. After he moved to the Institute of Cetacean
Research, there was a little interaction, such as attending a meeting when I was involved with researchon cetaceans for a short time, and participating in the Fisheries Resources Management Colloquium at
the Institute of Cetacean Research. In retrospect, I have had a long relationship with him since I started as a researcher.

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RECOLLECTIONS OF SEIJI OHSUMITWO MEMORIES OF DR. OHSUMI
Koichi KAJI
Professor Emeritus, Tokyo University of Agriculture and Technology,
Director of Wildlife Management Research Center, 940 Aogakicho, Sawano, Tamba, Hyogo, Japan

There are two things that left a strong impression in my memories of Dr. Ohsumi. One is a letterof compassionate encouragement and an expectation that I received from Dr. Ohsumi when I moved
from a research institute in Hokkaido to Tokyo University of Agriculture and Technology (TUAT) in
April 2006. Every time I encountered a diﬃcult situation, I was able to return to my original intension
by rereading the letter many times.
The other is the event at the whaling seminar co-hosted with Professor Hidehiro Kato of Tokyo
University of Marine Science and Technology (TUMSAT) in July 2007. In that year, I focused on thewhaling controversy in my seminar for six ﬁrst-year students. As the ﬁnal touch on the seminar, Professor Kato kindly arranged a joint seminar titled “On the Whaling Issue.” This was an exceptionalseminar in which graduate students of the TUMSAT commented on the presentation by the TUAT
ﬁrst-year students, and a scientist from the Institute of Cetacean Research (ICR) gave a summary andcomment. Dr. Ohsumi, an adviser of the ICR, also participated in the joint seminar and gave warmcomments on the three presentations on the “History of Whaling” in Part 1.
However, Dr. Ohsumi seriously argued, “I don’t think so,” in response to the opposition’s allegations in Part 2, “The Controversy over Whaling.” Participants praised the student for making such agood presentation that Dr. Ohsumi would seriously argue. I felt the sincerity of the academic discipline when I saw Dr. Ohsumi sincerely facing the presentation of the ﬁrst grader. I would like to cherish Dr. Ohsumi’s message that it is science-based words that can transcend the conﬂict of values.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTION OF SEIJI OHSUMI
Toshio KASUYA
Retired Professor, Mie University and Teikyo University of Science and Technology,
Nagayama, Tama-shi, Tokyo, Japan

In the autumn of 1960 Dr. Masaharu Nishiwaki of the Whales Research Institute (WRI; Director
Hideo Omura) invited me to pursue my graduation thesis in his laboratory, where I met Dr. Seiji
Ohsumi. The next year I joined WRI as a research staﬀ and received trainings from Ohsumi for cetacean biologists. These included photo ﬁlm development, photo printing and creating block copies forpapers. I also learned from him processing of cetacean gonads and ageing of whales. The experiencesat WRI, including two North Paciﬁc and an Antarctic pelagic whaling cruises, formed the foundationof my later activities. Before modern tools such as personal computer and word processor became
available in the early 1980s, we biologists used abacus, slide rule, table of logarithms for data analyses, and typewrote manuscript. Recent biologists have an easier work environment and tend to create aﬂood of papers often with complicated statistical analyses of value I don’t know.
After spending 5 years at WRI, I was invited by Nishiwaki to the Ocean Research Institute, University of Tokyo, and worked mainly on biology of Japanese small cetaceans and river dolphins of theworld. Then in 1983 Ohsumi invited me to the Cetacean Division of the Far Seas Fisheries ResearchLaboratory. With the cooperation of my staﬀ, I enjoyed 14 years (1983–1997) of my life in the Laboratory working on the biology and management of cetaceans around Japan. I believe that Ohsumi
worked for us during the period as a buﬀer between our cetacean group and the Fisheries Agency.
After my retirement from educational jobs at Mie (1997–2001) and Yamanashi (2001–2006), I
was fortunate to resume regular contacts with Ohsumi with drinking at a buckwheat noodle shop in
Shinjuku, usually twice a year. The last was on 10 July 2019, when we talked about inviting someelderly cetacean biologists, but it did not happen.

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RECOLLECTIONS OF SEIJI OHSUMIFOLLOWING SEIJI OVER 40 YEARS
Hidehiro KATO
Professor Emeritus, Tokyo University of Marine Science and Technology,
Advisor, Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo, JapanI ﬁrst met Dr. Seiji Ohsumi (I would refer to him hereafter as “Seiji” for the sake of friendliness)when I was a PhD student majoring in pinnipeds such as seals and sea lions. For some days 40 years
ago, Seiji chaired a session at the marine mammal symposium, and I was sitting in the backmost row
of the hall. I was intently watching him from the back of the room, and his unique way of speaking in
his later days, which you are all familiar with, was already there. Even now, when I close my eyelids,
the impressions of that time immediately come to mind. The image brings me back memories!
Although it did not occur to me at the time of the symposium, later on I was hired as a researcher
at the former Whales Research Institute, where Seiji had also worked in the past, through the intermediary of the late Dr. Hideo Omura and others, and later moved to the Far Seas Fisheries Laboratory in
Shimizu, where I followed Seiji. Even if we continued our research at diﬀerent institutions for a while,
we kept working closely together in the research itself, and after my retirement from Tokyo Universityof Marine Science and Technology in 2018, I had the honor of working with him as an advisor at ICR.
Seiji’s written Japanese was ﬂowing and elegant, beautiful, and grammatically correct. Overseas
scientists cannot imagine that one of Seiji’s articles on whale enlightenment was used in one of thechapters of a Japanese language textbook selected for junior high school. On the night before Seiji’s death, we exchanged passionate opinions as usual about the ideal whale research and their stock
management. His face was calm, but full of intelligence. Seiji’s education was diﬀerent fromthe education that we, the younger generation,
had. Seiji inherited the liberal arts principles
based on the deep philosophical insights of theold high school under the prewar education system. As well as being a preparatory course toenter the imperial university, it was the essenceof elite education that has already been lost inJapan. Seiji was from the last student generation
to graduate from the old Niigata Public HighSchool in 1949 and went on to the old Universityof Tokyo, where he met his respected supervisor,
the late Professor Masaru Nishiwaki, and Seiji
was initiated in cetacean sciences by him there.
The image of Seiji singing his favorite dormitory
song loudly at the dormitory song festival of theold high school which, like many others in Japanis now closed, is always overlapping in my mind
Fig. 1. Dr. Seiji Ohsumi at the time of the oldwith the image of him at the symposium.
Niigata Public High School, 17 or 18 years old.
Courtesy of Seiji’s family.
May he rest in peace.

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RECOLLECTIONS OF SEIJI OHSUMIMEMORIAL REMINDER OF THE LATE
DR. SEIJI OHSUMI
Akito KAWAMURA
Professor Emeritus, Mie University, 1577 Kurimamachi Yacho, Tsu, Mie, Japan
8–9–8 Nanae-cho, Kameda-gun, Hokkaido 041–1111, Japan

More than ﬁfty years ago Dr. Seiji Ohsumi initiated a bio-ecological research on the Antarctic
minke whales. During the 1967/68 whaling season a total of 597 minkes were caught by our whaling
ﬂeets, and some essentially important biological data were obtained. With these together with somepast knowledge and sighting records having been done from time to time, Dr. Ohsumi was very awareof the importance toward establishing a well-designed model for stock management. At that time Dr.
Ohsumi foresighted coming future days of minke whale ﬁsheries in the Southern Ocean and reported
one of the basic data on the stock of this species while the amount of related data and/or evidence wasstill very limited. The report was: Stock of the Antarctic Minke Whale. Sci. Rep. Whales Res. Inst.,
No. 22, (1970).
In this report he estimated the population size of the Antarctic minke whale to be 70,000, mainly
based on sighting records obtained. Although the number itself was about one tenth of the later understandings, he suggested that introduction of latitudinal and longitudinal unit areas was undoubtedly
possible an important key for stock management in the future. With hope for developing more modernized regulations for whaling ﬁsheries together with what he aimed and described in the report, thestory as a whole was full of suggestions.
As one of the younger alumni disciples of the old Whales Research Institute (WRI) I am very proudof him, having co-authored the report mentioned above. At the same time I hope that Ohsumi’s foresighted and precursory work on whale stock management and whale ﬁsheries would be remindedwidely on this occasion.
We lost a true man of whales and whale ﬁsheries. Recollections around activities and the old WRI
always accompany the late Dr. Seiji.
May his soul rest in peace.

Ohsumi, S., Masaki Y., and Kawamura, A. 1970. Stock of the Antarctic minke whale. Sci. Rep. Whales Res. Inst. 22: 75–125.

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RECOLLECTIONS OF SEIJI OHSUMIRETROSPECT OF THE LATE DR. SEIJI OHSUMI
Zang Geun KIM
Senior Scientist, Fisheries Resources Management, National Fisheries Research and Development Institute,408–1 Shirang-ri, Gijang-Up, Gijang-Gun Busan, Republic of Korea

As a person who was once in charge of cetacean research in Korea, I would like to honor the memory of the late world-renowned whale scientist, Dr. Seiji Ohsumi.
He admitted me as a trainee on cetacean research in the Far Sea Fisheries Research Institute forthree months. When I arrived at Shizuoka Station in summer 1988, he came to pick me up and guided
me to the Institute and assigned an employee apartment for my accommodation. During the training
period there, I met with Drs. Tomio Miyashita and Hidehiro Kato and other colleagues.
Since 1993, Korea and Japan have established scientiﬁc cooperation through agricultural and ﬁsheries cooperation as well as science and technology cooperation, as mandated in the Article 65 of the UNCLOS. This,in certain way led to the start of systematic cetacean research in Korea and inspired the establishment of the
Cetacean Research Institute (CRI, NFRDI) in 2004. I wish this harmonious friendship may continue (Fig. 1).
I met him for more than 20 years in multiple opportunities such as on the occasion of the IWC
meetings or social events and exchange programs (Fig. 2) until I left the Cetacean Research Instituteof Korea in 2009. One of the precious memories that comes to my mind is that he liked the Koreansoybean paste soup in my house and travelled with me to many places in Korea.
With all these memories, my family and I pray that the deceased may have a rest of peace at God’s mercy.

Fig. 1. The message of Dr. Ohsumi to the opening of CRI in 2005.

Fig. 2. Group photo at the symposium on cetacean research in the Fisheries Research and Development Institute, February 14, 2001.
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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI
Toshiya KISHIRO
Deputy Director, Highly Migratory Resources Division, Fisheries Resources Institute, National Researchand Development Agency, Japan Fisheries Research and Education Agency,
2–12–4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa, Japan

I met Dr. Ohsumi for the ﬁrst time when I joined the National Research Institute of Far Seas Fisheries after graduation in 1989. At that time, he was the director of the Institute, and I received rudimentary guidance as a researcher from him as a newcomer to the Cetacean Lab. He was engaged not onlyin pursuing research on whales, but also worked to organize research on other international ﬁsheryresources sections such as tuna and salmon and nurtured many researchers at the National Institute. In
addition, despite his busy schedule, he had written many books on whales aimed for the general publicand contributed to the dissemination of whale knowledge in Japanese society. All of us admired his
vitality and inclusive, straight personality. After his retirement in 1991, he moved to the Institute of
Cetacean Research, and continued to work and enthusiastically guide our cetacean research for many
years. He had been literally a living dictionary and a spiritual pillar for us. On behalf of our Institute,
I express sincerely respect for his achievements, and deep gratefulness for his leadership and encouragements for us. I feel that he continues to encourage the future progress of the cetacean population
studies even after he’s gone.
I pray from the bottom of my heart that his soul may rest in peace.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMI
Rebecca LENT* and Iain STANILAND***Secretary, International Whaling Commission**Secretariat Lead for Science, International Whaling Commision
The Red House, 135 Station Road, Impington, Cambridge, UK

Dr. Seiji Ohsumi was a stalwart of the IWC Scientiﬁc Committee (SC) because of his long-standing, valued and active participation in the committee. He will be remembered fondly and appreciatedfor his years of dedication to scientiﬁc research and his contributions to the IWC. Between 1967 and2010 Dr. Ohsumi authored and co-authored 182 papers3 submitted to the SC collaborating with scientists from all over the world. This impressive body of work spanned a wide range of subject areas,
including stock assessments, mathematical modelling, reproduction, feeding, and genetics, and contributed to our knowledge of baleen whales and small cetaceans alike. There are few who have contributed as much to the SC as Dr. Ohsumi.
Dr. Ohsumi was also committed to supporting early career researchers providing mentoring of theirstudies and research. His legacy lives on in the IWC as many of his former students and collaborators
continue to serve with us today. His passing is a great loss to cetacean science and he is already greatly missed by the IWC community.

3

Editor’s Note:
CPOPS received with these recollections note from the IWC Oﬃce an extensive list of works by Dr. Ohsumi related to the
Scientiﬁc Committee of the IWC. This list was collated and incorporated into Seiji Ohsumi’s bibliography presented in thefollowing section of this issue.

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RECOLLECTIONS OF SEIJI OHSUMIPERSONAL TRIBUTE TO DR. SEIJI OHSUMI
Christina LOCKYER
Research Director, Age Dynamics, Huldbergs Alle 42, Kongens Lyngby, DenmarkMy ﬁrst recollection of Seiji Ohsumi was in 1972 when I attended the IWC Scientiﬁc Committee
for the ﬁrst time. The IWC SC was a very diﬀerent body to that existing today with only about twodozen participants from Australia, Canada, Iceland, Japan, Norway, USSR, South Africa, UK, USA
and FAO. Seiji was very smart, dark suited, clean-shaven and jet-black hair. He was then in his early
40s. Then in my mid-20s, I looked up to him as a senior scientist. He seemed very inscrutable andI was a little in awe. He was very interested in my age estimation techniques in baleen whales andarranged for me to visit the Far Seas Fisheries Laboratory in Shimizu in 1977 for 3 months to readear plugs and teach some students. He organised everything for me, right down to the Japanese styleapartment. I recall being very sick during a national holiday when I lost much weight. Seiji was concerned and insisted on taking me for a sushi dinner with Suntory whisky to help me recover and lift
my spirits. It really worked, and since then he always showed great kindness and hospitality to me. We
met many times over the decades we were both active whale scientists, and I visited Japan for researchseveral times when he often invited me to his home and took me sight-seeing (Fig. 1). When working
on ear plugs in Tokyo in December 2009, he was a grand host and invited me to dine together with hiswife, herself a prominent professor (Fig. 2). In late September 2019, I visited Japan for a ﬁrst vacation
cruising around Japan. We met before I departed and enjoyed a pleasant time together (Figs. 3 and 4).
I did not know he would leave us forever some weeks later. Our last contact was by e-mail 2 days
before he died, when he wished me a good recovery from breast cancer. He was a special man, andmy recollections of him are very personal; now more as a friend and colleague than about his work
achievements which were themselves awesome. He became the respected and very kind friend that I
knew for 47 years. May he rest in peace.

Fig. 1. Seiji acting as tour guide for me on a
personal tour of Kamakura.

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Fig. 2. Dining out with Seiji and his wife in December 2009. I remember this place had a lovely
garden where we walked.

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RECOLLECTIONS OF SEIJI OHSUMI

Fig. 3. Outside a dinner venue in Tokyo, September 2019.

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Fig. 4. Seiji during a walkabout with me near the
Ginza in September 2019.

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RECOLLECTIONS OF SEIJI OHSUMIIN REMEMBRANCE OF DR. SEIJI OHSUMI
Koji MATSUOKA
Research Executive Director, Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, JapanI ﬁrst met Dr. Seiji Ohsumi when I joined the Institute of Cetacean Research (ICR) back in 1992,
while he was the Executive Director there. For the ﬁrst ten years or so of my working at the Institute,
I was constantly shuttling back and forth between the North Paciﬁc and the Antarctic Oceans. Dr.
Ohsumi never forgot to encourage us young researchers, often asserting that the ﬁeld was the basis ofwhale research and that it was important to write papers even on small topics. During those intense
day and night sessions at the annual IWC/SC meetings, we received from him sometimes harsh andsometimes warm guidance on the legitimacy of research whaling and the importance of its continuation. The International Decade of Cetacean Research Program (IDCR) which he helped to launch in
1978/1979, was succeeded by the Southern Ocean Whale and Ecosystem Research Program (IWC/
SOWER) and now by the ongoing International Whaling Commission/Paciﬁc Ocean Whale and Ecosystem Research (IWC-POWER). Since my joining ICR, I went to the Antarctic Ocean as much as 15
times, and because of that, every time I had to be away for the New Year festivities. I will never forgetthat Dr. Ohsumi invited my family to his home on each of those occasions, thus warmly guarding myhome front while I was away. I sincerely pray for the repose of his soul.

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RECOLLECTIONS OF SEIJI OHSUMIIN MEMORY OF DR. OHSUMI
Tsukasa MURAYAMA
Professor, Department of Marine Biology, School of Marine Science and Technology, Tokai University,
3–20–1 Orido, Shimizu Ward, Shizuoka City, Shizuoka, JapanI ﬁrst met Dr. Seiji Ohsumi when I was in my ﬁrst year of university, participating in a seminar on
cetaceans held in Shimizu City (now Shimizu ward), Shizuoka Prefecture. On the second day of theseminar, we visited the Far Seas Fisheries Research Laboratory, where Dr. Ohsumi talked to us about
various topics. He was still a young man, but he explained many things to us, ﬂedgling researchers,
while holding a handful of materials in front of him. While Dr. Ohsumi had already made many
achievements since the 1960s and 1970s, contributing greatly to cetacean research in Japan, at thattime I did not know anything about research nor did I know much about him. However, from that dayon, I often found the name “S. Ohsumi” in a number of international journals, and as I stumbled uponbooks written by Dr. Ohsumi in bookstores, I remember being surprised when I realized he was suchan outstanding person.
After that, I went on to pursue cetacean research, and we had more opportunities to talk, and I wasindebted to him in many ways, which did not change after he moved on to the Institute of Cetacean
Research. When I went to visit him at the Institute with my doctoral thesis after receiving my doctorate, he welcomed me with a calm expression and congratulated me.
Dr. Ohsumi also keenly tried to spread the word about his research and whales to young people andthe general public who liked natural science. For example, he often visited the activities of groups ofpeople who were interested in dolphin and whale research, and gave them advice on the ecology of cetaceans and their research. He also participated in almost every symposium I organized every year inTokyo, and gave presentations at some of them. After the symposium, he always talked to the participants, students who had just started their research, and aquarium staﬀ, not only about whales, but also
about the sea and ships, including his own experiences. He was never pompous as a great authority on
cetacean research, and the young people also entertained friendly feelings toward him.
No matter what I asked him, he always responded with an aﬀable smile and an amiable manner, andI regret and feel sad that I will never see him again.
I sincerely pray for the repose of his soul.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTION OF DR. SEIJI OHSUMITomio MIYASHITA
Associate Researcher, Fisheries Resources Institute, National Research and Development Agency,
Japan Fisheries Research and Education Agency, 5–7–1 Orido, Shimizu, Shizuoka, JapanI have been indebted to Dr. Ohsumi for his help and support in both my work and private life since I
started working at the Far Seas Fisheries Research Laboratory in 1980. When I joined the Laboratory,
Dr. Ohsumi was the head of the cetacean resources section, and he taught me about marine mammals,
starting with their scientiﬁc names, even though I had no connection with those animals. In addition,
when I saw him directly typing English documents in preparation for the IWC SC meeting that was
just around the corner, he would crack up day and night, typing away on his IBM electric typewriter,and I feel that he taught me by example how to approach my work with a strict attitude. He always
asked me “Why?” in response to my doubts. There were times when I was at a loss for an answer,
but I believe that I was taught to pursue the truth through these experiences. When I look at the many
papers and writings that Dr. Ohsumi has left behind, I am once again amazed at the scientiﬁc contributions he has made. He loved to drink, and I was invited by him to drink at many occasions in thepast. When I look at the photos, I remember those events such as ‘Hanami’ to see cherry blossoms
and ‘Imonikai’ to eat boiled taro. He was also from Gunma Prefecture, and when my wife and I were
married, he served as our matchmaker. We are very grateful to him for his help in dealing with the situation. Now, we are ﬁlled with sadness at the loss of Dr. Ohsumi. May he rest in peace.

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RECOLLECTIONS OF SEIJI OHSUMICONDOLENCES ON THE PASSING OF
DR. SEIJI OHSUMI
Sally MIZROCH
Retired Research Biologist, Alaska Fisheries Science Center, NOAA, USA

I met Seiji the very ﬁrst time I attended the meeting of the International Whaling Commission’s
Scientiﬁc Committee in 1980. I was a new member of the US delegation and Seiji was the head of
the Japanese delegation. Back in those days, even though the US and Japanese delegations had very
diﬀerent views on commercial whaling, we enjoyed spending time together after hours singing anddrinking. We developed close and long-lasting personal friendships.
I was a young female scientist, one of maybe four women in attendance during those early years,
and Seiji was always very supportive of all of us and of me personally. Seiji had an aﬃnity for many
young scientists, male and female, and his support contributed to our own growth as scientists.
Seiji and I genuinely enjoyed each other’s company each time we met. He was my thoughtful tour
guide during my many visits to Japan and we respected each other’s viewpoints even when we disagreed.
I also enjoyed Seiji’s long great friendship with my friend and long-time collaborator Dale Rice.
One of my fondest early memories was sitting with Seiji on a bus ride from Reykjavik to the Icelandic
whaling station in 1987 when he told me that he and Dale were exactly the same age. He and Dale
Rice were part of a remarkable generation of biologists whose analyses advanced our knowledge ofcetacean biology in a breathtaking fashion. Now they are together again. I miss them both very muchand was lucky to be friends and collaborators with them.
I’ve attached a photo of Seiji, Dale, and Gordon Pike from 1963 (Dale Rice’s photo collection), a
photo of Seiji with a Discovery mark logbook showing mark recovery data for a sei whale Dale hadmarked oﬀ California in 1965, and some recent photos of Seiji when I spent time with him in Tokyoand in Kamakura City.
So sadly,Your old friend Sally

Fig. 1. Seiji Ohsumi, Dale Rice and Gordon Pike
(right) having coﬀee break during the IWC Sperm
Whale Workshop in Seattle, WA (1963).

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Fig. 2. Seiji with the Discovery Mark recovery
logbook showing the recovery of a sei whale Dale
Rice’s marked oﬀ southern California in 1965(2012).

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RECOLLECTIONS OF SEIJI OHSUMI

Fig. 3. Seiji as tour guide in Kamakura City in
2012.

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Fig. 4. Seiji and I the last time we met in Tokyo.
He is wearing a souvenir hat I gave him in 2012
from my favorite baseball team, the Seattle Mariners (September 4, 2014).

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RECOLLECTIONS OF SEIJI OHSUMIMEMORIES OF DR. SEIJI OHSUMI
Joji MORISHITA
Professor, Department of Marine Policy and Culture, Tokyo University of Marine Science and Technology,
4–5–7-Konan, Minato-ku, Tokyo, Japan

When I became a government oﬃcial at the Fisheries Agency of the Government of Japan in 1982,
Dr. Ohsumi was one of the most knowledgeable scientists about whales and whaling. When I attended
my ﬁrst-time International Whaling Commission (IWC) meeting in 1992 held in Glasgow, UK, he wasalready regarded as a legendary ﬁgure in the whale/whaling community of the world. Since then, we
attended so many meetings together and travelled around and into many corners of the world (Figs. 1
and 2). Every one of them is memorable and I learned a lot from Dr. Ohsumi.
Two stories among so many remind me of who Dr. Ohsumi was.
He told me that he was criticized by Japanese whalers as anti-whaling when he, as a young scientist, reported to the IWC Scientiﬁc Committee about the poor stock status of some whale stocks andsupported whaling restrictions targeting those stocks. He was smiling when he told me of this story,
but I am sure it was not a pleasant episode for him. However, it was clear to me that his conscience asa scientist was always the most important guiding principle of his activities and statements.
Another story is very much consistent with the above. Dr. Ohsumi had held many important andresponsible positions through his professional life, including that of Director General of the National
Research Institute of Far Seas Fisheries (NRIFSF, Shimizu Laboratory), and Director General of theInstitute of Cetacean Research (ICR), to name a few. But he was most happy when he passed all these responsibilities to his successors and told me then that he ﬁnally became one simple scientist again that cancontribute to science. He actually contributed to the advancement of science till the last day of his life.
He was stubbornly a pure scientist even when the results of his research and analysis were against
the interests of whalers. While he was an excellent manager of the organizations he had led, he preferred to be a simple scientist. He hated “political scientists.” He often said to young scientists to be ascientist rather than a scientiﬁc technician.
It was my great honor and privilege to have worked with Dr. Ohsumi. His legacy will remain withall of us who met him.

Fig. 1. During a Japan-Russia scientiﬁc planningmeeting in Moscow (June 1999).

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Fig. 2. During a trip to Norway to ﬁnalize the blue
whale skeleton lease contract to Shimonoseki city
(July 1999).

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RECOLLECTIONS OF SEIJI OHSUMIONWP
Hideki MORONUKI
Director for Fisheries Negotiations, Fisheries Agency of Japan, Ministry of Forestry, Agriculture and Fisheries,
1–2–1 Kasumigaseki, Chiyoda-ku, Tokyo, Japan

Ohsumi-sensei was not just a scientist but also a man of vital spirit and warm heart. Everybody
knows that he was one of the pioneering whale scientists in Japan, who supported Japan’s whaling
industry from top to bottom. He is also well known to many of us as a “militant” pursuing the sustainable use of whale resources. However, this was not only for the beneﬁt of Japan, but also for allover the world, speciﬁcally for developing countries. He advocated his own humanitarian whaling plot
where sustainable whaling would be conducted for ample whale resources in the Antarctic Ocean andwhale products obtained therefrom would be distributed to developing countries severely suﬀeringfrom food crisis (Ohsumi’s New Whaling Plot). In order to materialize his plot, he devoted himself tothe resumption of science-based sustainable whaling and thereby encouraged young scientists, industry colleagues and Government oﬃcials to ﬁght together.
On 1 July 2019, more than 31 years after the introduction of the so-called Moratorium on Commercial Whaling, Japan resumed the sustainable whaling based on the best scientiﬁc information available. Fortunately, we were able to celebrate the resumption of the sustainable whaling together withyou, Ohsumi-sensei. However, it was not in time to materialize your plot. We still have a lot of things
to do and a lot of obstacles to overcome before your dream may become true. However, you do notneed to worry about it too much, Ohsumi-sensei. Please remember that you brought up so many pupils
and followers who will make the most of your will to meticulously seek a way to move your plot forward. Please therefore look forward to a future big news about the sustainable whaling in the Antarctic Ocean being resumed and that the food shortage in some developing countries is being mitigatedthrough ONWP: Ohsumi’s New Whaling Plot.

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RECOLLECTIONS OF SEIJI OHSUMIAPPRECIATE THAT I COULD SHARE TIME
WITH A GREAT SCIENTISTGen NAKAMURA
Assistant Professor, Laboratory of Cetacean Biology, Tokyo University of Marine Science and Technology,
4–5–7 Konan, Minato-ku, Tokyo, Japan

In my childhood, I occasionally saw the name of Dr. Seiji Ohsumi in some books. But the ﬁrst contact with him was not until 2006, when I started my Cetology studies at the university. After that, 13
years have passed. I guess it might be a very short time in his life, but it was a very meaningful period
for me. Even after he retired, he energetically attended the conferences or meetings and delivered innovative opinions to us, based on his vast knowledge. I feel very sorry that I was unable to talk anddiscuss with him, but I leverage that with his papers, books, and memories for my life as a researcher.
I really appreciate you, Ohsumi-sensei.

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RECOLLECTIONS OF SEIJI OHSUMIA FEW WORDS IN MEMORY OF DR. SEIJI OHSUMILuis A. PASTENE
Head of Science, Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo, Japan

Seiji was an important person during several stages of my life. The ﬁrst time I met him was in 1981
during a workshop on cetacean reproduction in the United States. At that time, I was a pre-graduate
student at the Concepcion University in Chile. Knowing my interest in cetacean research, he kindly
provided information on scholarships and encouraged me to carry out postgraduate studies in Japan.
Furthermore, in 1985 he helped me secure a scholarship that allowed me to travel to Japan in Octoberof that year. Then I started postgraduate studies at the Ocean Research Institute (ORI) of the Universityof Tokyo. Seiji was supportive of me both personally and professionally as I adapted to living in Japan.
In 1992, I became a member of the Institute of Cetacean Research (ICR) where Seiji was Executive
Director, and we continued to work together at ICR until he died on 2 November 2019. He always
supported my research activities in ICR and provided strict but fair criticism of my studies. I was impressed by Seiji’s enthusiasm and dedication to cetacean and whaling research, and to the ICR. Until
the very last week, he came to the institute almost every day, actively participating in our domestic
meetings and providing useful advice and suggestions. I think many colleagues and friends will agreewith me that Seiji can be characterized as a great cetacean scientist, a true gentleman and a very enthusiastic person for research and social-related activities. I feel happy that our last work interaction
in 2019—on Chilean blue whale research—was a very positive one with Seiji supporting and agreeing
with my conclusions on that particular study. I feel a deep respect and gratitude to the memory of Seiji.

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RECOLLECTIONS OF SEIJI OHSUMIMOURNING THE PASSING OF DR. SEIJI OHSUMI
Kazumi SAKURAMOTO
Professor Emeritus, Tokyo University of Marine Science and Technology,
4–5–7 Konan, Minato-ku, Tokyo, Japan

I would like to express my heartfelt condolences on the passing away of Dr. Seiji Ohsumi, whodevoted his life to the study of whales and was a world-renowned authority on whale research.
I have been fortunate enough to be involved in cetacean research since 1982, and from then until his
demise, I had the opportunity to receive guidance from Dr. Ohsumi both in private and public life. The
ﬁrst meeting of the International Whaling Commission (IWC) that I attended was the Minke Whale
Ageing Workshop held in Cambridge, England in April 1983. At that time, the only researchers who
participated from Japan were Dr. Seiji Ohsumi, Dr. Hidehiro Kato and myself, but I still remember
vividly the gentle and strict guidance I received from him even as a newcomer. Since then, we attended together many meetings of the IWC Scientiﬁc Committee while Dr. Ohsumi continued his research
activities as Director General of the Institute of Cetacean Research (ICR) and later on as Adviser
Emeritus to the ICR, and gave me much guidance until just before he became ill. I also recall withdeep emotion the many enjoyable conversations we had at social gatherings.
The image of Dr. Ohsumi that is etched in my mind is his big smile and his gentle gaze. The sadness of losing a great leader and the image of Ohsumi-sensei will never leave my heart. I sincerely
pray for the repose of his soul.

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RECOLLECTIONS OF SEIJI OHSUMICONDOLENCES ON THE PASSING OF
DR. SEIJI OHSUMI
Hawsun SOHN
Director, Cetacean Research Institute, 139–29 Maeam-dong, Nam-gu, Ulsan, Republic of Korea

First of all, please accept my deepest and heartfelt condolences.
In the face of Dr. Seiji Ohsumi’s obituary, all Korean colleagues could not hide their sorrow oflosing the great pioneer. Dr. Ohsumi’s research has been a valuable reference of information on cetacean for researchers in Korea where the study was still in its early stages but also in Northeast Asia as
well. Even after his retirement, we could feel his special aﬀection and warm kindness toward young
colleagues at the meeting room. He used to say Hello in Korean, 안녕하세요 (Annyunghaseyo)
whenever he met young Korean researchers.
On one side of the lobby in the Cetacean Research Institute, there is a letter written by him, whohopes for a joint cooperation research between Korea and Japan.
Korea remembers Dr. Ohsumi’s great achievements and warm heart.
Please rest in peace.

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RECOLLECTIONS OF SEIJI OHSUMIIN MEMORY OF DR. SEIJI OHSUMI
Tsutomu TAMURA
Head, Stock Assessment and Management Division/Ecosystem Studies and Population Division,
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo, Japan

The ﬁrst time I met Dr. Ohsumi was when I was still a graduate student about to participate in one
of Japan’s whale research program cruises, and he had just become Director General of the Instituteof Cetacean Research (ICR). I remember how nervous I was when he said, “I hope you will do yourresearch well”, while handing me the researcher’s letter of appointment.
Several years later, after completing my doctoral course, I joined the ICR and immediately foundmyself having lots of work to do. It was the task of collecting all the resource abundance information
on cetaceans in the world available then and estimating the amount of their predation. He gave meheaps of advice as I had just joined the Institute and didn’t know from my right to my left.
As a result, we were able to report that the world’s whale predation amounted to about 300 to 500
million tons, equivalent to three to ﬁve times the world’s marine ﬁsheries catch at that time. In retrospect, I think it was the inclusion in the paper of the name and essence of the renowned whale scientist
Dr. Seiji Ohsumi, that created such a big buzz around the world. Back then, there was a lot of criticism
that our whale prey consumption estimation was overrated, but Dr. Ohsumi said that this was becauseof the great interest that this ﬁeld of research was arousing worldwide. Recently, other scientists haveshown that whales may be eating even larger amounts of prey4 than our original estimations, and I am
glad that my research with Dr. Ohsumi has come back into the spotlight.
In addition, at our repeated drinking parties he would always emphasize to us that “A full-ﬂedged
researcher must be able to go into the ﬁeld, write a paper, and do both”. The last time I saw him, glowing with enthusiasm he spoke about his passion for research, and I never thought I would have to say
goodbye so suddenly.
I pray for the repose of his soul.

4

Savoca, M., Czapanskiy, M. F., Kahane-Rapport, S. R., Gough, W. T., Fahlbusch, J. A., Bierlich, K. C., Segre, P. S., Di
Clemente, J., Penry, G. S., Wiley, D. N., Calambokidis, J., Nowacek, D. P., Johnston, D. W., Pyenson, N. D., Friedlaender,
A. S., Hazen, E. L., and Goldbogen, J. A. (2021). Baleen whale prey consumption based on high-resolution foraging measurements. Nature. 599. 85–90. doi: 10.1038/s41586-021-03991-5.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTION OF SEIJI OHSUMI
Ralph TIEDEMANN
Institute of Biochemistry and Biology, University of Potsdam,
Karl-Liebknecht-Str. 24–25, 14476 Potsdam OT Golm, Germany

In the course of my fruitful collaboration with Japanese scientists, I was so lucky (and happy) tohave had the opportunity to repeatedly travel to Tokyo in order to work at ICR. At ICR, I very regularly met Seiji Ohsumi who was still doing cetacean research, despite of his age. Seiji always gave mea very warm and friendly welcome in Japan in general and at ICR in particular. It was enlightening
to discuss with him cetacean science as well as IWC matters, as he had a rare combination of several decades’ research experience, up-to-date-knowledge, and thoughtfully balanced arguments. He
was even following the latest genetic technologies in population studies, as I could witness ﬁrst-handduring a scientiﬁc lecture of mine at ICR, which Seiji attended and actively participated during discussion. Most memorable though, is a non-science moment with Seiji: I was invited to a superb sushi
restaurant in Tsukiji where I enjoyed the company of my Japanese colleagues and friends and had theprivilege to sit next to him (Fig. 1). We were chatting the whole evening about everything but science.
I will never forget his deep insights into many aspects of human life, including the history back to the
middle of the last century. Many facts and facets I was hardly aware of being within his personal experience and remembrance, and he communicated them with his unique enlightening and whole-hearted
attitude. I was deeply impressed. I will miss Seiji.

Fig. 1. A non-science moment with Seiji and colleagues.

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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI
Senzo UCHIDA
Special Advisor, Okinawa Churashima Foundation,
888 Aza Ishikawa, Motobu-cho, Kunigami-gun, Okinawa, Japan

When I was a senior member of the Ito Aquarium in the 1970s, staﬀ scientists of the Whales Research Institute (WRI), led by Director Dr. Hideo Omura including Drs. Masaharu Nishiwaki, Seiji
Ohsumi, Tadayoshi Ichihara, Keiji Nasu and some others, visited the aquarium on a comfort trip organized by WRI. At the aquarium, there was also an accommodation facility that relocated the inn
where I grew up in Ito Onsen hot spring, and everyone held a big banquet after the duties. Dr. Teruo
Tobayama, the head of the aquarium, and Uchida (myself) served as hosts as well and oﬀered a lot ofbeer and sake for them. At that time, everyone was drinking a lot and making a big fuss.
The next day at a diﬀerent high-class inn also located in Ito Onsen, it seemed that it was even morethan that, and Seiji appeared to have been very active there too. The following day, the president of theinn, an intellectual gentleman, called me and said, “I didn’t see that coming!”
It was a long time ago, a long time ago.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMI
Gísli A. VÍKINGSSONHead of Cetacean Research, Marine and Freshwater Research Institute,Fornubúðir 5 220, Hafnarfjörður, Iceland

I met Seiji Ohsumi for the ﬁrst time in 1988, at my ﬁrst annual meeting of the Scientiﬁc Committee (SC) of the International Whaling Commission (IWC). At that time, I had worked on cetacean
research for only two years, after completing my thesis on quite a diﬀerent subject, behavioural ecology of greylag geese! Although naive in this branch, I had learned enough to know the name of Dr.
Seiji Ohsumi and I felt a kind of starstruck when Seiji approached me on the ﬁrst day of the meeting
and welcomed me to the Committee with his specially charming and warm attitude. This was the ﬁrst
of many conversations I had with Seiji over the next three decades, mostly within the context of the
IWC. Despite all the tensions and politics associated with some discussions taking place within theSC, in particular those concerning the scientiﬁc activities of Japan (and sometimes also Iceland andNorway), I always sensed the great respect that Seiji had among almost all the scientists in the SC,
irrespective of their position in the often-heated debate. To outsiders, such respect for opponents ina scientiﬁc debate could seem a matter of course in a scientiﬁc forum, but this could not be taken for
granted during some periods of extreme polarization within the Committee.
Dr. Ohsumi was a remarkable scientist that continued to explore new ﬁelds in science throughout
his career. The great legacy of Seiji Ohsumi as a pioneer in whale research is evident from his large
amount of scientiﬁc works produced over 60 years, and the memories of a great colleague, and a mentor to many, will live long into the future.

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RECOLLECTIONS OF SEIJI OHSUMIREMEMBERING SEIJI OHSUMI
Lars WALLØE
Professor Emeritus, Department of Physiology, University of Oslo, Norway

I met Seiji Ohsumi for the ﬁrst time in the IWC Scientiﬁc Committee meeting in San Diego in
1988, and since then we have met at every IWC/SC meeting and every IWC Commission meeting
until quite recently. In addition, I have visited Japan more than 50 times over the last 30 years, andnearly each time I have had the opportunity to discuss whale scientiﬁc questions and the related political questions with him. Only during 2019, I met with Seiji in ICR three times, in late February, in
mid-June and in July. Every time we had interesting discussions. In the 1990s, he once accompanied
me to Taiji and showed me the whale museum there, and he travelled with me to other local communities to meet the local whalers and for them to show me their boats and whaling equipment. We travelled together in Norway also. I wanted to show him our local communities and wanted him to meet
our whalers. Together we and Masayuki Komatsu managed to establish a semi-permanent loan of ablue whale skeleton from the university museum in Tromsø to the aquarium in Shimonoseki and withﬁber-glass copies of the skeleton on display in four other places in Japan, among them Taiji.
What was my impression of Seiji Ohsumi? Seiji was eight years older than me, and when we met
in 1988, he had a life-long experience in whale science. I also had an extensive scientiﬁc background,
but whale science was new to me. My experience with the subject was about two years old. Despite
this diﬀerence in age and experience, Seiji from the ﬁrst meeting treated me as an equal and did neveruse his longer experience as an argument when we had some small disagreements. Compared to theNorwegian society, the Japanese is in general very hierarchical, but Seiji deﬁnitely did not ﬁt into thispicture of the Japanese society. He had authority based on knowledge and experience, not on his position in an administrative hierarchy. When he lacked knowledge in a particular scientiﬁc discipline, headmitted it; he did not try to bluﬀ, but listened to others who had the knowledge.
Most of the years we interacted, Seiji was head of the Japanese delegation to the IWC/SC, and I
was head of the Norwegian delegation. Since our two countries had attitudes to whaling diﬀerent frommost other countries, we had to collaborate. For me this collaboration was a great pleasure. We both
had the same attitude and opinions about whaling, and I think we learned a lot from each other. I shallmiss Seiji Ohsumi in the future, but I am very happy to have known him.

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RECOLLECTIONS OF SEIJI OHSUMIRECOLLECTIONS OF SEIJI OHSUMI
Yuri YAKOVLEV
A.V. Zhirmunsky Institute of Marine Biology National Scientiﬁc Center of Marine Biology of
the Far Eastern Branch of the Russian Academy of Sciences, 690041 Vladivostok, Russian Federation

I met Seiji Ohsumi on the voyage of the RV Akademik Oparin in 1993. This expedition was one of
the few with scientists from diﬀerent countries, mostly from Japan. The Tokyo cable TV group, TBS,
was also on board. Much attention was paid to underwater photography and video, in which I participated as a professional diver and zoologist. At that time I was not yet engaged in the study of whales,
and I saw the work of Japanese cetacean researchers for the ﬁrst time. In fact, right away I came to theconclusion that this is a very hard work, against the background of which underwater diving seemed
to me already an easy and exciting entertainment.
Having participated in many expeditions, I immediately noticed a man whose appearance indicatedthat he was a scientist with tremendous experience in ﬁeld research, so I was not at all surprised tolearn that he was the foremost expert on the whales of the Paciﬁc Ocean, Professor Ohsumi. It so happened that from the ﬁrst days of the voyage I became friends with Tsuneo Nakamura, a well-known
wildlife and sailing photographer, who taught me the peculiarities of whale photography from the
Achilles boat (Fig. 1). After work or in inclement weather, Tsuneo and I very often accepted the professor’s invitation to stop by his quarters. Such gatherings sometimes ended late. The topics of conversation were very diverse, but not whale-oriented. Unfortunately, the weather conditions on that cruise
were extremely unfavourable for whale sightings and we tried not to discuss this circumstance. I remember well as being said in the conversation that whaling in the post-war years made it possible tosupply the younger generation with animal protein and keep our countries’ populations healthy. Plans
were made to carry out regular expeditions on the then numerous ships of the Far Eastern Branch of
the Russian Academy of Sciences in subsequent years to the north, to the Arctic. However, these quite
realistic projects could not be implemented due to the inept policy of the scientiﬁc ﬂeet management.
Later, when I started studying gray whales, I had the opportunity to meet with Professor Ohsumi
only at conferences. He said that if I needed his support, I could freely turn to him. But, as they say in
Russia, the certainty of getting help from a friend is much more valuable than the help itself.

Fig. 1. Tsuneo Nakamura (Volvox Inc.), Yuri M. Yakovlev (Institute of Marine Biology, Vladivostok), Dr.
Seiji Ohsumi (ICR). North Kuril Islands, 1993. On board the RV Akademik Oparin.

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RECOLLECTIONS OF SEIJI OHSUMIIN A LAB WITHIN SIGHT OF MOUNT FUJI
Motoi YOSHIOKA
Professor, Graduate School of Bioresources, Mie University, 1577 Kurimamachiya, Tsu, Mie, Japan

Evoking the ﬁrst time I met Dr. Ohsumi, I wrote the following in a manuscript submitted to ajournal in 1990: “I went to visit Dr. Seiji Ohsumi at the Far Seas Fisheries Research Laboratory in
Shimizu to see if there was any way I could make a breakthrough in my research. Dr. Ohsumi gave
me a lot of advice in his laboratory which had a beautiful view of Mt. Fuji from the window, but hiscomment about my work on hormones being ‘quite interesting’ was a great encouragement to me
afterwards.” I was 24 years old then, and unsure whether I would be able to continue my research on
dolphin reproductive hormones in graduate school. He gave me words of encouragement for my research which I had been conducting from a viewpoint that so far had not existed in cetacean researchin Japan. However, if I had not visited Dr. Ohsumi that day, I might have given up my research on
cetaceans soon after. My encounter with Dr. Ohsumi was a major event at such a crucial moment forme. Forty years have passed since then. During this period, I received from him much scientiﬁc advice
and guidance from the viewpoint of population biology and reproductive biology, which was his ﬁeldof specialty, when I became involved in the research of Dall’s porpoises and Bryde’s whales. However, what left the greatest impression on me during my association with him is that he was very open to
students who had just started their cetacean research —just as he was to me when I visited Shimizu, at
research meetings and other occasions, and always looked at us warmly and gave us encouragement.
In the days when information on cetacean research was not readily available as it is now on the internet, his many books, translations, and articles were very valuable materials for students to learn. Dr.
Ohsumi, who devotedly made many research achievements in whale research contributing greatly tothe management of whale resources and the continuation of the whaling industry in Japan, was always
thinking about the future of cetacean research in Japan and giving light to us students who did notknow what kind of life they would lead in the future. Looking back on my current self as a university
faculty member who has been studying whales and dolphins with students for over 30 years, I wonder
to what extent I have been able to train the next generation of researchers. I hope I can spend my remaining time as a professor so that I may reduce that doubt as much as possible.
I would like to once again express my deepest gratitude to Dr. Ohsumi for his continuous interest inwhales and to young people wanting to study them, and I sincerely pray for the repose of his soul.

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RECOLLECTIONS OF SEIJI OHSUMICONDOLENCES ON THE PASSING OF
DR. SEIJI OHSUMI
Alexandre ZERBINI
Chair of the IWC Scientiﬁc Committee, Cooperative Institute for Climate, Ocean, and Ecosystem Studies,
University of Washington & Alaska Fisheries Science Center, NOAA, USA

Indeed, a rich life and major contributions to cetacean science. Our community lost one of the best
and my thoughts and prayers are with his family and friends.
Best wishes, Alex

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RECOLLECTIONS OF SEIJI OHSUMIMEMORIES OF MY FATHER, DR. SEIJI OHSUMINoriko OSUMI
Vice President, Tohoku University; Professor, Tohoku University School of Medicine,
2–1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, Japan

In my mind, I still haven’t sorted out my father’s passing. When I rushed to the hospital on November 2, 2019, he was already out of it and I didn’t get to spend his last hours with him. The last time I
saw my father before he died was on October 4, 2019, which I could trace from my Google Calendar
records. On that day, I had dinner with my high school classmates and visited my parents in Shinjuku
late, so we only exchanged a few words before my returning to Sendai the next morning. That day,he said he had plans to go to a gathering of the old Niigata High School, and he showed me his old
school cap, laughing as he told me that he was going to wear it and sing the dormitory song.
I can barely remember my childhood. My father had been working alone at the National Research Instituteof Far Seas Fisheries (formerly Far Seas Fisheries Research Laboratory) in Shimizu since my early elementary school. I used to complain that I could spend more time with my father if he took the Shinkansen when
he came back from Zushi, where we lived at the time. However, after joining the Tohoku University as aprofessor, I came to realize how diﬃcult it is, physically and ﬁnancially, for those who work alone to returnhome to their families every week. Now I understand how much he loved my mother, and me. When myfather taught me to play Go and Shogi, he would not let me win, which made me dislike those games. I thinkmy habit of reading books came from watching my father. As a scientist, my father was very strict about theuse of words, so from a young age, he would ask me, “What is the deﬁnition of that?”. Accordingly, I becamea very logical child and was rather shunned by other classmates. My mother also worked at Japan Women’s
University, so weekends were complete rest for my father and mother, while family vacations were rare.
However, there were other rare occasions when foreign researchers came to our house as guests. For me,
English was not a subject to study for exams, but a means of communication. This experience has helped me
in my current career as a neuroscientist. After entering graduate school, I learned that my father’s dissertation
was on “A study on age determination of the ﬁn whale,” and I was depressed at the diﬀerence in scale frommy own ﬁrst dissertation. I hoped that it would catch someone’s attention, so after my father passed away, I
got a copy from the National Diet Library and had it published by the University of Tokyo Repository5.
In 1992, when the International Whaling Commission annual meeting was held in Glasgow, UK, I stayedat the same hotel with my father because I also had to attend an international conference that was held at
the same time there. My father’s snoring was so bad that I didn’t want to go with him again, but I was more
shocked by the fact that anti-whaling activists were demonstrating around the hotel. I had heard about it indirectly from my father, but it meant a lot to me to know it in real life. I think this experience, in addition to
the general books written by my father, was a major factor in my developing a great interest in science communication; scientists in every ﬁeld need to communicate with the public. Before my father passed away, inAugust of 2017, I happened to bump into him at the gate of Narita Airport. He was going to visit the Faroe
Islands in Denmark, where whales are ﬁshed, with a group including Mr. Kazutaka Sangen, the mayor of
Taiji, where the Whale Museum is located; my father was the honorary director of the museum at the time.
I was going to Sweden via Copenhagen for an international meeting. My father and I never informed eachother of our business trip plans in advance, so it must have been a coincidence that God brought us together.
I really wish I could have learned more things from my father. He was blessed with the wonderful people
around him. I hope that my father's passion for sustainable whaling will lead you to take your own actions.
Rest in peace, my father.
5

Ohsumi, S., n. d. A study on age determination of the ﬁn whale. Doctoral Thesis, The University of Tokyo. UTokyo Repository. https://irdb.nii.ac.jp/00926/0004334795.

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KUBA AND GOMEZ DIAZ

BIBLIOGRAPHY OF THE PUBLISHED WORKS
OF DR. SEIJI OHSUMI
Compiled, edited and translated by

Tomoko KUBA and Gabriel GOMEZ DIAZ
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan

Abstract
The published works of the late Dr. Seiji Ohsumi (Gunma, 1930–Tokyo 2019) are presented
here as a modest contribution to the perpetuation of his memory. This bibliography was compiled so as to include both his scholarly works and other popular publications targeted towarda general audience. It is grouped into the following four categories: 1. Scientiﬁc journal papers(including unpublished works presented to the International Whaling Commission Scientiﬁc
Committee (IWC/SC)); 2. Books and book contributions (authored works, translations andother contributions such as editorial supervision, commentary, editing and editorial advice);
3. Reports and booklets, and 4. Others. The latter group comprises works published in the
Geiken Tsuushin Whales Research Institute/Institute of Cetacean Research (WRI/ICR) Quarterly Newsletter, and other miscellaneous writings such as essays and articles that appeared invarious magazines, newsletters and other organizations’ periodicals, most of them in Japanese.
Some interviews and website articles are also included as he made it a point to record themamong his written works. Scientiﬁc works are listed by year of publication and, on the same
year, alphabetically by author. Other publications are presented chronologically by group.
During a span of 65 years, he authored and coauthored the 741 works listed in this compilation. Their numbers, by category, are: 286 scientiﬁc papers, 58 books and book contributions,
40 reports and booklets, and 357 works in other categories (100 in Geiken Tsuushin and 257
miscellaneous).
Key words:

cetacean biology, cetacean ecology, resource management, whaling, whale foodculture, whale stock assessment.

1. Scientiﬁc Journal Papers (286)1954
Nishiwaki, M., Hibiya, T. and Kimura, S. 1954. On the sexual maturity of the sei whale of the Bonin waters. Sci. Rep.
Whales Res. Inst. 9: 165–177.
1955
Omura, H., Fujino, K. and Kimura, S. 1955. Beaked whale Berardius bairdi of Japan with notes on Ziphius cavirostris. Sci.
Rep. Whales Res. Inst. 10: 89–132.
1956
Kimura, S. 1956. The twinning in Southern ﬁn whales. Sci. Rep. Whales. Res. Inst. 12: 103–125.
Kimura, S. and Nemoto, T. 1956. Note on a minke whale kept alive in an aquarium. Sci. Rep. Whales Res. Inst. 11: 181–189.
Nishiwaki, M., Hibiya, T. and Kimura, S. 1956. On the sexual maturity of the sperm whale (Physeter catodon) found in the
North Paciﬁc. Sci. Rep. Whales Res. Inst. 11: 39–46.
1958
Nishiwaki, M., Hibiya, T. and Ohsumi (Kimura), S. 1958. Age study of sperm whale based on reading of tooth laminations.
Sci. Rep. Whales Res. Inst. 13: 135–153.
Nishiwaki, M., Hibiya, T. and Ohsumi（Kimura), S. 1958. Age study of ﬁn whale based on ear plug. Sci. Rep. Whales Res.
Inst. 13: 155–169.
Ohsumi（Kimura), S. 1958. A descendant of Moby Dick or a white sperm whale. Sci. Rep. Whales Res. Inst. 13: 207–209.
Ohsumi (Kimura), S., Nishiwaki, M. and Hibiya, T. 1958. Growth of ﬁn whale in the northern Paciﬁc. Sci. Rep. Whales Res.
Inst. 13: 97–133.

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BIBLIOGRAPHY OF THE PUBLISHED WORKS OF SEIJI OHSUMI1959
Ohsumi (Kimura), S. 1959. A deformed ﬁn whale foetus. Sci. Rep. Whales Res. Inst. 14: 145–147.
1960
Ohsumi, S. 1960. Relative growth of the ﬁn whale, Balaenoptera physalus (Linn.). Sci. Rep. Whales Res. Inst. 15: 17–84.
1961
Nishiwaki. M., Ohsumi, S. and Kasuya, T. 1961. Age characteristics in the sperm whale mandible. Norsk Hvalfangst-Tid. 50(12): 499–507.
1962
Ohsumi, S. 1962. Biological material obtained by Japanese expeditions from marked ﬁn whales. Norsk Hvalfangst-Tid. 51(5): 192–198.
1963
Nishiwaki, M., Ohsumi, S. and Maeda, T. 1963. Change of form in the sperm whale accompanied with growth. Sci. Rep.
Whales Res. Inst. 17: 1–14.
Ohsumi, S., Kasuya, T. and Nishiwaki, M. 1963. The accumulation rate of dentinal growth layers in the maxillary tooth of
the sperm whale. Sci. Rep. Whales Res. Inst. 17: 15–35.
1964
Ohsumi, S. 1964. Examination on age determination of the ﬁn whale. Sci. Rep. Whales Res. Inst. 18: 49–88.
Ohsumi, S. 1964. Comparison of maturity and accumulation rate of corpora albicantia between the left and right ovaries inCetacea. Sci. Rep. Whales Res. Inst. 18: 123–148.
Omura, H. and Ohsumi, S. 1964. A review of Japanese whale marking in the North Paciﬁc to the end of 1962, with some information on marking in the Antarctic. Norsk Hvalfangst-Tid. 53 (4): 90–112．
1965
Doi, T. and S Ohsumi. 1965. Fourth memorandum on results of Japanese stock assessment of whales in the North Paciﬁc.
Rep. int. Whal. Commn. 18: 62–65.
Doi, T., Ohsumi. S. and Nemoto, T. 1965. On diagnosis of the ﬁn whale population in the Antarctic and optimum level ofcatching. Bull. Tokai Reg. Fish. Res. Lab. 41: 1–22. (In Japanese).
Ohsumi, S. 1965. Reproduction of the sperm whale in the north-west Paciﬁc. Sci. Rep. Whales Res. Inst. 19: 1–35.
Ohsumi, S. 1965. A dolphin (Stenella caeruleoalba) with protruded rudimentary hind limbs. Sci. Rep. Whales Res. Inst. 19:
135–136.
1966
Kasuya, T. and Ohsumi, S. 1966. A secondary sexual character of the sperm whale. Sci. Rep. Whales Res. Inst. 20: 89–94.
Ohsumi, S. 1966. Allomorphosis between body length at sexual maturity and body length at birth in the Cetacea. J. Mammal.
Soc. Japan. 3 (1): 3–7.
Ohsumi, S. 1966. Sexual segregation of the sperm whale in the North Paciﬁc. Sci. Rep. Whales Res. Inst. 20: 1–16.
1967
Doi, T., Ohsumi, S. and Nemoto, T. 1967. Population assessment of sei whales in the Antarctic. Norsk Hvalfangst-Tid. 56 (2):25–41.
Doi, T., Nemoto, T. And Ohsumi, S. 1967. Third memorandum on results of Japanese stock assessment of whales in the
North Paciﬁc. Rep. int. Whal. Commn. 17: 89–92.
Doi, T., Nemoto, T. and Ohsumi, S. 1967. Memorandum on results of Japanese stock assessment of whales in the North Paciﬁc. Rep. int. Whal. Commn. 17: 111–115.
Ohsumi, S. 1967. Review of age determination of cetaceans. Bull. Jap. Soc. Fish. Sci. 33 (6): 788–798. (In Japanese).
1968
Doi, T. and Ohsumi, S. 1968. Fourth memorandum on results of Japanese stock assessment of whales in the North Paciﬁc.
Rep. int. Whal. Commn. 18: 63–66.
Doi, T. and Ohsumi, S. 1968. Memorandum of further study on population assessment of sei whales in the Antarctic. Rep.
int. Whal. Commn. 18: 67–72.
Nemoto, T., Doi, T. and Ohsumi, S. 1968. Population assessment of ﬁn whales in the North Paciﬁc Ocean—I. Catch statistics, biological parameters and natural mortality coeﬃcient. Bull. Tokai Reg. Fish. Res. Lab. 54: 5–52. (In Japanese).
1969
Doi, T. and Ohsumi, S. 1969. The present status of sei whale population in the Antarctic. Rep. int. Whal. Commn. 19: 118–
120.
Doi, T. and Ohsumi, S. 1969. Fifth memorandum on results of Japanese stock assessment of whales in the North Paciﬁc. Rep.
int. Whal. Commn. 19: 123–129.
Doi, T. and Ohsumi, S. 1969. A theoretical consideration on the maximum sustainable yield of sei whales in the Antarctic.
Bull. Tokai Reg. Fish. Res. Lab. 60: 83–93. (In Japanese).
Doi, T. and Ohsumi, S., Nasu, K. and Shimadzu, Y. 1969. Advanced assessment of ﬁn whale stock in the Antarctic. Bull. Tokai Reg. Fish. Res. Lab. 60: 95–141. (In Japanese).
Ohsumi, S. 1969. Occurrence and rupture of vaginal band in the ﬁn, sei and blue whales. Sci. Rep. Whales Res. Inst. 21:
85–94.
Ohsumi, S. 1969. Summary of sperm whale marking investigations in the North Paciﬁc. Rep. int. Whal. Commn. 19: 56–58.
Ohsumi, S. 1969. Suisan seibutsu ni taisuru teremeteori kiki souchakuhou (Method of putting telemetric instrument to marine

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KUBA AND GOMEZ DIAZ
living organisms). Kaiyou Seibutsu Teremetori Kenkyuu Kaihou 2: 11–18. (In Japanese).
Ohsumi, S. 1969. Mammals in Japan (7). Cetacea. Physeteridae. Sperm whale. Honyurui Kagaku 17: 35–48. (In Japanese).
Omura, H., Ohsumi, S., Nemoto, T., Nasu, K. and Kasuya, T. 1969. Black right whales in the North Paciﬁc. Sci. Rep. Whales
Res. Inst. 21: 1–78.
1970
Doi, T. and Ohsumi, S. 1970. On the maximum sustainable yield of sei whales in the Antarctic. Rep. int. Whal. Commn. 20:
86–96.
Doi, T. and Ohsumi, S. 1970. Sixth memorandum on results of Japanese stock assessment of whales in the North Paciﬁc.
Rep. int. Whal. Commn. 20: 97–111.
Doi, T., Ohsumi, S., Nasu, K. and Shimadzu, Y. 1970. Advanced assessment of the ﬁn whale stock in the Antarctic. Rep. int.
Whal. Commn. 20: 60–87.
Ohsumi, S. 1970. A population model for sei whale in the North Paciﬁc. Paper SC/22/22 presented to the IWC Scientiﬁc
Committee, June 1970 (unpublished). 9 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1970. A trial to get mathematical models of population for sperm whale. Paper SC/22/23 presented to the IWC
Scientiﬁc Committee, June 1970 (unpublished). 10 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1970. Some considerations on ﬁshing eﬀort and CPUE for the Antarctic ﬁn whales. Paper F/9 presented to the
Sperm Whale Biology and Stock Assessment Meeting, Honolulu, March 1970 (unpublished). 20 pp. [Paper available
from the Oﬃce of the IWC].
Ohsumi, S. 1970. Yearly change in the age and body length at sexual maturity of the Antarctic ﬁn whale. Data oﬀered in theSpecial Meeting on Antarctic Fin Whale Stock Assessment (unpublished). 3 pp. [Paper available from the Oﬃce of the
IWC].
Ohsumi, S. and Nasu, K. 1970. Range of habitat of the female sperm whale with reference to the oceanographic structure.
Paper Sp/7 presented to the Sperm Whale Biology and Stock Assessments Meeting, Honolulu, March 1970 (unpublished). 18 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S., Masaki, Y. and Kawamura, A. 1970. Stock of the Antarctic minke whale. Sci. Rep. Whales Res. Inst. 22: 75–125.
Ohsumi, S. and Shimadzu, Y. 1970. Composition of growth of ﬁn whales among various areas of the Antarctic Ocean. Paper
F/7 presented to the Antarctic Fin Whale Stock Assessment Meeting, Honolulu, March 1970 (unpublished). 16 pp. [Paper available from the Oﬃce of the IWC].
1971
Doi, T., Ohsumi, S. and Shimadzu, Y. 1971. Status of stock of baleen whales in the Antarctic 1970/71. Rep. int. Whal. Commn. 21: 90–99.
Nemoto, T., Doi, T. and Ohsumi, S. 1971. Population assessment of ﬁn whales in the North Paciﬁc—II. Fishing mortality
coeﬃcient, population number and optimum rate of exploitation on the level of sustainable yield. Bull. Tokai Reg. Fish.
Res. Lab. 67: 35–46. (In Japanese).
Ohsumi, S. 1971. Preliminary estimate of population size of the sperm whale in the Southern Hemisphere. Paper SC/23/3
presented to the IWC Scientiﬁc Committee, June 1971 (unpublished). 5 pp. [Paper available from the Oﬃce of the
IWC].
Ohsumi, S. 1971. Some investigations on the school structure of the sperm whale. Sci. Rep. Whales Res. Inst. 23: 1–25.
Ohsumi, S., Shimadzu, T. and Doi, T. 1971. Seventh memorandum on results of Japanese stock assessment of whales in the
North Paciﬁc. Rep. int. Whal. Commn. 21: 76–89.
Ohsumi, S. 1971. Biological adaptation of mammals to aquatic environment. Honyurui Kagaku 19: 1–12. (In Japanese).
Ohsumi, S. and Masaki, Y. 1971. Revised estimates of population size and MSY of the Antarctic minke whale. Paper
SC/23/4 presented to the IWC Scientiﬁc Committee, June 1971 (unpublished). 7 pp. [Paper available from the Oﬃce of
the IWC].
1972
Masaki, Y., Wada, S. and Ohsumi, S. 1972. Preliminary report on investigations of sperm whale schools oﬀ the coast of Japan. Paper Sp/72/3 presented to the Sperm Whale Assessment Meeting, Vancouver Island, May 1972 (unpublished). 29
pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1972. Exploitations of Antarctic minke whales in 1971/72. Paper SC/24/12 presented to the IWC Scientiﬁc Committee, June 1972 (unpublished). 10 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1972. Catch of marine mammals, mainly of small cetaceans, by local ﬁsheries along the coast of Japan. Bull. Far
Seas Fish. Res. Lab. 7: 137–166. (In Japanese).
Ohsumi, S. 1972. Examination of the recruitment rate of the Antarctic ﬁn whale stock by use of mathematical models. Rep.
int. Whal. Commn. 22: 69–90.
Ohsumi, S. and Fukuda, Y. 1972. Some theoretical considerations on sperm whale regulation. Paper Sp/72/2 presented to the
Sperm Whale Assessment Meeting, Vancouver Island, May 1972 (unpublished). 6 pp. [Paper available from the Oﬃceof the IWC].
Ohsumi, S. and Fukuda, Y. 1972. A population model and its application to the sperm whale in the North Paciﬁc. Rep. int.
Whal. Commn. 22: 96–110.
Ohsumi, S. and Masaki, Y. 1972. Status of stocks of baleen whales in the Antarctic 1971/72. Rep. int. Whal. Commn. 22:
60–68.
Ohsumi, S. and Masaki, Y.1972. Eighth memorandum on results of Japanese stock assessment of whales in the North Paciﬁc.

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Rep. int. Whal. Commn. 22: 91–95.
Ohsumi, S. 1972. Atarashii sougyou kuiki to geirui shigen kanri no shomondai (New operating area and issues for stock
management of cetaceans. Suisan Kaiyou Kenkyuu Kaihou. 22: 41–45. (In Japanese).
Ohsumi, S. 1972. Kaijuurui no kotaigun doutai to shigen kanri (Population dynamics and resource management of marine
mammals). Seibutsu no Kagaku. Iden. 26 (11): 43–49. (In Japanese).
Ohsumi, S. and Wada, S. 1972. Stock assessment of blue whales in the North Paciﬁc. Paper SC/24/13 presented to the IWC
Scientiﬁc Committee, June 1972 (unpublished). 20 pp. [Paper available from the Oﬃce of the IWC].
1973
Ohsumi, S. 1973. Find of marlin spear from the Antarctic minke whales. Sci. Rep. Whales Res. Inst. 25: 237–239.
Ohsumi, S. 1973. Revised estimate of recruitment rate of the Antarctic ﬁn whales. Rep. int. Whal. Commn. 23: 192–199.
Ohsumi, S. and Masaki, Y. 1973. Whale sighting and whale marking in the North Paciﬁc in winter. Paper SC/25/10 presented
to the IWC Scientiﬁc Committee, June 1973 (unpublished). 9 pp. [Paper available from the Oﬃce of the IWC].
Wada, S., Okumoto, N. and Ohsumi, S. 1973. Comparative study of genetic polymorphism in four whale species as an approach to stock identiﬁcation. Paper SC/25/13 presented to the IWC Scientiﬁc Committee, June 1973 (unpublished). 6
pp. [Paper available from the Oﬃce of the IWC].
1974
Ohsumi, S. 1974. Stock management of cetaceans. Honyurui Kagaku 28: 39–46. (In Japanese).
Ohsumi, S. and Fukuda, Y. 1974. Revised sperm whale population model and its application to the North Paciﬁc sperm
whale. Rep. int. Whal. Commn. 24: 91–101.
Ohsumi, S. and Masaki, Y. 1974. Status of whale stocks in the Antarctic 1972/73. Rep. int. Whal. Commn. 24: 102–113.
Ohsumi. S. and Wada, S. 1974. Status of whale stocks in the North Paciﬁc, 1972. Rep. int. Whal. Commn. 24: 114–126.
1975
Ohsumi, S. 1975. Review of Japanese small-type whaling. J. Fish. Res. Board Can. 32 (7): 1111–1121.
Ohsumi, S. 1975. Incidental catch on cetaceans with salmon gillnet. J. Fish. Res. Board Can. 32 (7): 1229–1235.
Ohsumi，S. and Fukuda, Y. 1975. A review on population estimates for the North Paciﬁc sei whales. Rep. int. Whal. Commn.
25: 95–101.
Ohsumi, S. and Fukuda, Y. 1975. On the estimate of exploitable population size and replacement yield for the Antarctic sei
whale by use of catch and eﬀort data. Rep. int. Whal. Commn. 25: 102–105.
Ohsumi, S. and Masaki, Y. 1975. Biological parameters of the Antarctic minke whale at the virginal population level. J. Fish.
Res. Board Can. 32 (7): 995–1004.
Ohsumi, S. and Masaki, Y. 1975. Japanese whale marking in the North Paciﬁc, 1963–1972. Bull. Far Seas Fish. Res. Lab.
12: 171–219. (In Japanese).
1976
Ohsumi, S. 1976. Conversion of sustainable yield curve by numbers into that by weight in the ﬁn and sperm whale populations. Rep. int. Whal. Commn. 26: 215–224.
Ohsumi, S. 1976. Population assessment of Californian gray whale. Rep. int. Whal. Commn. 26: 350–359.
Ohsumi, S. 1976. An attempt to standardize ﬁshing eﬀorts as applied to the stock assessment of the minke whale in the Antarctic Area IV. Rep. int. Whal. Commn. 26: 404–408.
Ohsumi, S., Masaki, Y. and Wada, S. 1976. A note on the distribution of some smaller cetaceans in the North Paciﬁc. International Whaling Commission, Subcommittee on Small Cetaceans, SC/L/20 London (unpublished). 6 p. [Paper available
from the Oﬃce of the IWC].
Okutani, T., Satake, Y., Ohsumi, S. and Kawasaki, T. 1976. Squids eaten by sperm whales caught oﬀ Jouban District, Japan,
during January–February, 1976. Bull. Tokai Reg. Fish. Res. Lab. 87: 67–113. (In Japanese).
1977
Ohsumi, S. 1977. Bryde’s whales in the pelagic whaling ground of the North Paciﬁc. Rep. int. Whal. Commn. (Special issue)
1: 140–150.
Ohsumi, S. 1977. Further assessment of population of Bryde’s whales in the North Paciﬁc. Rep. int. Whal. Commn. 27:
156–160.
Ohsumi, S. 1977. Estimation of population sizes of the Southern Hemisphere minke whale at the initial and 1976/77 levels.
Rep. int. Whal. Commn. 27: 161–163.
Ohsumi, S. 1977. Catch of minke whales in the coastal waters of Japan. Rep. int. Whal. Commn. 27: 164–166.
Ohsumi, S. 1977. A preliminary note on Japanese records on death times for whales killed by whaling harpoon. Rep. int.
Whal. Commn. 27: 204–205.
Ohsumi, S. 1977. Age-length key of the male sperm whale in the North Paciﬁc and comparison of growth curves. Rep. int.
Whal. Commn. 27: 295–300.
Ohsumi, S. 1977. Criticism on growth curves of male sperm whale by means of whale marking. Rep. int. Whal. Commn. 27:
301–304.
Ohsumi, S. 1977. Sperm whale catch eﬃciency by Japanese pelagic whaling catcher boats in the Antarctic. Rep. int. Whal.
Commn. 27: 305–307.
Ohsumi, S. 1977. Age and growth of cetaceans. Honyurui Kagaku 34: 54–65. (In Japanese).
Ohsumi, S. and Fukuda, Y. 1977. A note on the revised estimates of the Southern Hemisphere sei whale stocks. Rep. int.
Whal. Commn. 27: 236.

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Ohsumi, S. and Masaki, Y. 1977. Stocks and trends of abundance of the sperm whale in the North Paciﬁc. Rep. int. Whal.
Commn. 27: 167–175.
Ohsumi, S., Masaki, Y. and Wada, S. 1977. Seasonal distribution of sperm whales sighted by sighting boats in the North Paciﬁc and Southern Hemisphere. Rep. int. Whal. Commn. 27: 308–323.
Ohsumi, S. and Satake, Y. 1977. Provisional report on investigations of sperm whales oﬀ the coast of Japan under a special
permit. Rep. int. Whal. Commn. 27: 324–332.
1978
Ohsumi, S. 1978. A note on minke whales in the coastal waters of Japan. Rep. int. Whal. Commn. 28: 271–272.
Ohsumi, S. 1978. Assessment of population sizes of the Southern Hemisphere minke whales adding the catch data in
1976/77. Rep. int. Whal. Commn. 28: 273–276.
Ohsumi, S. 1978. Bryde’s whales in the North Paciﬁc in 1976. Rep. int. Whal. Commn. 28: 277–280.
Ohsumi, S. 1978. Provisional report on the Bryde’s whales caught under special permit in the Southern Hemisphere. Rep. int.
Whal. Commn. 28: 281–288.
Ohsumi, S. 1978. Estimation of natural mortality rate, recruitment rate and age at recruitment of Southern Hemisphere sei
whales. Rep. int. Whal. Commn. 28: 437–448.
Ohsumi, S. and Masaki, Y. 1978. Age-length keys and growth curves of the Southern Hemisphere sei whale. Rep. int. Whal.
Commn. 28: 431–436.
Ohsumi, S. and Wada, S. 1978. Provisional report on the minke whale caught under special permit in the North Paciﬁc. Rep.
int. Whal. Commn. 28: 289–292.
Ohsumi, S. and Yamamura, K. 1978. A review on catch of sei whales in the Southern Hemisphere. Rep. int. Whal. Commn.
28: 449–458.
Ohsumi, S. and Yamamura, K. 1978. Catcher’s hour’s work and its correction as a measure of ﬁshing eﬀort for sei whales in
the Antarctic. Rep. int. Whal. Commn. 28: 459–468.
1979
Ohsumi, S. 1979. Bryde’s whales in the North Paciﬁc in 1977. Rep. int. Whal. Commn. 29: 265–266.
Ohsumi, S. 1979. Provisional report on the Bryde’s whales caught under special permit in the Southern Hemisphere in
1977/78 and research programme for 1978/79. Rep. int. Whal. Commn. 29: 267–273.
Ohsumi, S. 1979. Interspecies relationships among some biological parameters in cetaceans and estimation of the natural
mortality coeﬃcient of the Southern Hemisphere minke whale. Rep. int. Whal. Commn. 29: 397–406.
Ohsumi, S. 1979. Population assessment of the Antarctic minke whale. Rep. int. Whal. Commn. 29: 407–420.
Ohsumi, S. 1979. Further examination on population assessment of Southern minke whales in Area IV. Rep. int. Whal. Commn. 29: 433–437.
Ohsumi, S. 1979. Feeding habits of the minke whale in the Antarctic. Rep. int. Whal. Commn. 29: 473–476.
Ohsumi, S. and Takagi, K. 1979. Preliminary report on Dall’s porpoises sighting by Japanese salmon research vessels in the
North Paciﬁc in 1978. INPFC Doc. 2150: 28 pp.
1980
Best, P. B., Horwood, J.W., Ohsumi, S., Clark, W., Tillman, M.F. and Mitchell, E.D. 1980. Report of the sub-committee on
sperm whales, Appendix 11. Reservations concerning the assessments made by the sperm whale sub-committee. Rep.
int. Whal. Commn. 30: 95–96.
Best, P. B. and Ohsumi, S. 1980. International Whaling Commission / International Decade of Cetacean Research (IWC /IDCR) Southern minke whale assessment cruise, 1978–79. Polar Rec. 20 (124): 52–57.
Doi, T., Ohsumi, S. and Tedori, J. 1980. Theoretical aspects analysed by introducing age-speciﬁc availability into population
analysis III. Sperm whales in the North Paciﬁc. Rep. int. Whal. Commn. (Special issue) 2: 197–204.
Doi, T., Ohsumi, S. and Tedori, J. 1980. Theoretical aspects analysed by introducing age-speciﬁc availability into population
analysis IV. Sei whales in the Antarctic. Rep. int. Whal. Commn. 30: 557–560.
Ohsumi, S. 1980. Behaviour of replacement yield accompanied with management procedures. Paper number MP 23 presented to the Special Scientiﬁc Working Group on Management Procedures, Honolulu, Hawaii, March 1980 (unpublished).
18 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1980. Reasons to oppose whale sanctuary in the Indian Ocean. Paper SC/32/O 18 presented to the IWC Scientiﬁc
Committee, 1980 (unpublished). 3 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1980. Catch of sperm whales by modern whaling in the North Paciﬁc. Rep. int. Whal. Commn. (Special issue) 2:
11–18.
Ohsumi, S. 1980. Review of Japanese ﬁshing eﬀort on sperm whales in the North Paciﬁc. Rep. int. Whal. Commn. (Special
issue) 2: 19–30.
Ohsumi, S. 1980. Population assessment of the sperm whale in the North Paciﬁc. Rep. int. Whal. Commn. (Special issue) 2:
31–42.
Ohsumi, S. 1980. Sperm whale catch by Japanese coastal whaling in the Sanriku Region. Rep. int. Whal. Commn. (Special
issue) 2: 161–168.
Ohsumi, S. 1980. Examination of the pregnancy rate of the sperm whale in the North Paciﬁc. Rep. int. Whal. Commn. (Special issue) 2: 169–176.
Ohsumi, S. 1980. Tune budgets of sperm whaling operation by Japanese whaling. Rep. int. Whal. Commn. (Special issue) 2:
177–183.

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Ohsumi, S. 1980. Index of abundance of the male sperm whale in the pelagic whaling ground of the North Paciﬁc. Rep. int.
Whal. Commn. (Special issue) 2: 185–195.
Ohsumi, S. 1980. Minke whales in the coastal waters of Japan, 1978. Rep. int. Whal. Commn. 30: 307–311.
Ohsumi, S. 1980. Bryde’s whales in the North Paciﬁc in 1978. Rep. int. Whal. Commn. 30: 315–318.
Ohsumi, S. 1980. Population study of the Bryde’s whale in the Southern Hemisphere under scientiﬁc permit in the three seasons, 1976/77–1978/79. Rep. int. Whal. Commn. 30: 319–331.
Ohsumi, S. 1980. Monitoring of ﬁn whale population in Area VI of the Southern Hemisphere. Rep. int. Whal. Commn. 30:
333–335.
Ohsumi, S. 1980. Pregnancy rate of the sperm whale in the Southern Hemisphere. Rep. int. Whal. Commn. 30: 337–338.
Ohsumi, S. and Takagi, K. 1980. Progress report on abundance survey of marine mammals, mainly Dall’s porpoise, byJapanese salmon research vessels in the North Paciﬁc in 1979. INPFC Doc. Ser. No. 2266: 56 pp.
1981
Harwood, J. W., Best, P. B. and Ohsumi, S. 1981. International Whaling Commission/International Decade of Cetacean Research (IWC/IDCR): Southern Hemisphere Minke Whale Assessment Cruise, 1979–80. Polar Rec. 20 (129): 565–569.
Kasamatsu, F. and Ohsumi, S. 1981. Yearly change in CPUE of the minke whale stocks by sexes in the Antarctic. Paper SC/
Jn81/MiS25 presented to the IWC Scientiﬁc Committee minke whale workshop, 1981 (unpublished). 13 pp. [Paper
available from the Oﬃce of the IWC].
Kasamatsu, F. and Ohsumi, S. 1981. Distribution pattern of minke whales in the Antarctic with special reference to the sex
ratio. Rep. int. Whal. Commn. 31: 345–348.
Kato, M., Ohsumi, S. and Takagi, K. 1981. Report on abundance survey of marine mammals, mainly Dall’s porpoise, byJapanese salmon research vessels in the North Paciﬁc in 1980. INPFC Doc. 2386: 45 pp.
Miyashita, T. and Ohsumi, S. 1981. Estimation of the population size of the sperm whale in the Southern Hemisphere usingsighting data. Rep. int. Whal. Commn. 31: 805–812.
Ohsumi, S. 1981. Distribution and abundance of killer whales in the Southern Hemisphere. Paper SC/Jn81/KW10 presented
to the IWC Scientiﬁc Committee, July 1981 (unpublished). 9 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1981. Estimation of the population size of the minke whale in the Antarctic Area VI by means of whale sightings.
Rep. int. Whal. Commn. 31: 323–326.
Ohsumi, S. 1981. Minke whales on the coastal waters of Japan, 1979. Rep. int. Whal. Commn. 31: 333–335.
Ohsumi, S. and Shimadzu, Y. 1981. Catch and eﬀort statistics of minke whaling: Japanese expeditions in the Antarctic,
1971/72–1979/80. Rep. int. Whal. Commn. 31: 367–370.
Ohsumi, S. 1981. Estimation of the population size of the ﬁn whale in the Antarctic Area VI using sighting data. Rep. int.
Whal. Commn. 31: 403–406.
Ohsumi, S. 1981. Further examination of population sizes of Bryde’s whales in the South Paciﬁc and Indian Oceans usingsighting data. Rep. int. Whal. Commn. 31: 407–415.
Ohsumi, S. 1981. Estimation of population size of the western North Paciﬁc Bryde’s whale using sightings data. Rep. int.
Whal. Commn. 31: 425–434.
Ohsumi, S. 1981. Pregnancy rate of the sperm whales caught by Japanese coastal whaling. Rep. int. Whal. Commn. 31:
801–804.
Ohsumi, S. 1981. Catches of sperm whales in the coastal waters of Japan. Rep. int. Whal. Commn. 31: 813–820.
Ohsumi, S. 1981. Interspecies relationships among some biological parameters related to natural mortality coeﬃcient in the
Cetacea. Rep. int. Whal. Commn. (Special issue) 3: 218. Abstract. (Part of paper published in Rep. int. Whal. Comm.
29, 1979, 397–406.)
Tillman, M. F. and Ohsumi, S. 1981. Japanese Antarctic pelagic whaling prior to World War II: review of catch data. Rep. int.
Whal. Commn. 31: 625–627.
Yamamura, K. and Ohsumi, S. 1981. Comparison of the yearly changes in CPUE for minke whales in the Antarctic based onJapanese and Soviet eﬀort data. Rep. int. Whal. Commn. 31: 327–332.
1982
Ohsumi, S. 1982. Some biological consideration on legal size limit in whaling. Paper SC/34/O 15 presented to the IWC Scientiﬁc Committee, June 1982 (unpublished). 17 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. and Kasamatsu, F. 1982. Right whale sightings in the waters south of Western Australia in summer, 1981/82. Paper SC/34/PS17 presented to the IWC Scientiﬁc Committee, June 1982 (unpublished). 13 pp. [Paper available from theOﬃce of the IWC].
Ohsumi, S. 1982. Minke whales in the coastal waters of Japan，1980 and a population assessment of the Okhotsk Sea-West
Paciﬁc stock. Rep. int. Whal. Commn. 32: 283–286.
Ohsumi, S. and Kasamatsu, F. 1982. Whale sighting eﬃciency of the crew on board ocean research vessels in BICMASS /FIBEX. Mem. Natl. Inst. Polar Res. Special issue 23: 108–119.
Ohsumi, S. and Yamamura, K. 1982. A review of the Japanese whale sightings system. Rep. int. Whal. Commn. 32: 581–586.
1983
Ohsumi, S. 1983. Yearly change in age and body length at sexual maturity of the ﬁn whale stock in the eastern North Paciﬁc.
Paper SC/A83/AW7 presented to the IWC Minke Whale Ageing Workshop, Cambridge, April 1983 (unpublished). 19
pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1983. Examination of transition phase in earplugs as a mark of sexual maturity of the Antarctic minke whale. Pa-

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per SC/A83/AW8 presented to the IWC Minke Whale Ageing Workshop, Cambridge, April 1983 (unpublished). 17 pp.
[Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1983. Parameters in sperm whale population models, needed from historical whaling record，and their sensitivity. Rep. int. Whal. Commn. (Special issue) 5: 23–28.
Ohsumi, S. 1983. Minke whales in the coastal waters of Japan in 1971, with special reference to their stock boundary. Rep.
int. Whal. Commn. 33: 365–372.
Ohsumi, S. 1983. Yearly change in the abundance index of Bryde’s whales in the western North Paciﬁc using sightings data.
Rep. int. Whal. Commn. 33: 477–480.
Ohsumi, S. 1983. Population assessment of Baird’s beaked whales in the waters adjacent to Japan. Rep. int. Whal. Commn.
33: 633–641.
Ohsumi, S. and Naito, Y. 1983. Whale sighting eﬃciency of the crew on board ocean research vessels in BICMASS/FIBEX.
JARE Data Reports 78. 49 pp.
Ohsumi, S. and Miyashita, T. 1983. Estimation of age distribution and recruitment rate of the Antarctic minke whale fromsize distribution of whales caught. Paper SC/35/Mi27 presented to the IWC Scientiﬁc Committee, June 1983 (unpublished). 19 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. and Teshima, K. 1983. Note on a newborn killer whale caught alive with trawl net. J. Mammal. Soc. Japan. 9 (4):208–210.
Shimadzu, Y., Ohsumi, S. and Katabami, Y. 1983. Revised eﬀort statistics for minke whaling by Japanese expeditions in the
Antarctic. Rep. int. Whal. Commn. 33: 383–387.
1984
Butterworth, D.S. and Ohsumi, S. 1984. Report of the Scientiﬁc Committee, Annex N. Minority statements, N4. Statement
on classiﬁcation of Southern Hemisphere minke whale stocks. Rep. int. Whal. Commn. 34: 178.
Ikeda, I. Shimadzu, Y. and Ohsumi, S. 1984. Report of the Scientiﬁc Committee, Annex N. Minority statements, N12: statement on unoﬃcial reviews of Scientiﬁc Committee deliberations. Rep. int. Whal. Commn. 34: 180.
Kasuya, T. and Ohsumi, S. 1984. Further analysis of the Baird’s beaked whale stock in the western North Paciﬁc. Rep. int.
Whal. Commn. 34: 587–596.
Ohsumi, S. 1984. Report of the sub-committee on other baleen whales, Appendix 13. Yearly change in SPUE for Dec.–Feb.
for Peruvian Bryde’s whale. Rep. int. Whal. Commn. 34: 128.
Ohsumi, S., Kasamatsu, F., Shimadzu, Y., Ikeda, I., Borodin, R. and Ivashin, M. 1984. Report of the Scientiﬁc Committee,
Annex N. Minority statements, N1. Statement on values of natural mortality rate and recruitment rate for the Antarctic
minke whales. Rep. int. Whal. Commn. 34: 175.
Ohsumi, S. 1984. Report of the Scientiﬁc Committee, Annex N. Minority statements, N5. Statement on Korean minke
whales. Rep. int. Whal. Commn. 34: 178.
Ohsumi, S. 1984. Report of the Scientiﬁc Committee, Annex N. Minority statements, Annex N11. Statement on the classiﬁcation and catch limits for the humpback whales oﬀ west Greenland. Rep. int. Whal. Commn. 34: 180.
Ohsumi, S. and Miyashita, T. 1984. Comments on the results of assessments from two simulation models for the western
North Paciﬁc sperm whale. Rep. int. Whal. Commn. 34: 265–272.
Valdivia, J. and Ohsumi, S. 1984. Report of the sub-committee on other baleen whales, Appendix 15. A note on classiﬁcation
and assignable catch limit for the Peruvian Bryde’s whales. Rep. int. Whal. Commn. 34: 129.
1985
Gunnlaugsson, T. and Ohsumi, S. 1985. Report of the Scientiﬁc Committee, Annex O. Minority statements, O2: Statementon the applicability of a safety factor to the recommended catch limit for the northeast Atlantic stock of minke whales.
Rep. int. Whal. Commn. 35: 149.
Kasamatsu, F. and Ohsumi, S. 1985. Preliminary estimation of abundance of sperm whale population in adjacent waters toJapan in summer by means of whale sightings. Rep. int. Whal. Commn. 35: 217–219.
Ohsumi, S. 1985. Estimation of the number of eﬀectively marked Southern Hemisphere minke whales. Rep. int. Whal. Commn. 35: 279–284.
Ohsumi, S. and Ikeda, I. 1985. Report of the Scientiﬁc Committee, Annex O. Minority statements, O4: Statement on the classiﬁcation of the Okhotsk Sea-West Paciﬁc stock of minke whales. Rep. int. Whal. Commn. 35: 149.
Ohsumi, S. and Miyashita, T. 1985. Report of the sub-committee on other baleen whales, Appendix 13. A method to estimate
population trajectory for the western North Paciﬁc Bryde’s whale. Rep. int. Whal. Commn. 35: 116–117.
Ohsumi, S., Miyashita, T., Sakuramoto, K., Kato, H. and Kasamatsu, F. 1985. Report of the sub-committee on other baleen
whales, Appendix 15. Population trajectory, classiﬁcation of stock and catch limit of the western North Paciﬁc Bryde’s
whale. Rep. int. Whal. Commn. 35: 117–118.
1986
Ikeda, I., Ohsumi, S., Tanaka, S., Kato, H., Kasamatsu, F. and Miyashita, T. 1986. Report of the Scientiﬁc Committee, Annex
N. Minority statements, N5: Comments on N3 by Ikeda, Ohsumi, Tanaka, Kato, Kasamatsu and Miyashita. Rep. int.
Whal. Commn. 36: 139.
Kato, H. and Ohsumi, S. 1986. Preliminary estimation of the body length at recruitment for the minke whales in the Antarctic
Areas III and IV. Paper SC/38/Mi17 presented to the IWC Scientiﬁc Committee, May 1986 (unpublished). 13 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1986. Yearly change in age and body length at sexual maturity of a ﬁn whale stock in the eastern North Paciﬁc.

58

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BIBLIOGRAPHY OF THE PUBLISHED WORKS OF SEIJI OHSUMISci. Rep. Whales Res. Inst. 37: 1–16.
Ohsumi, S. 1986. Earplug transition phase as an indicator of sexual maturity in female Antarctic minke whales. Sci. Rep.
Whales Res. Inst. 37: 17–30.
Ohsumi, S. and Kasamatsu, F. 1986. Recent oﬀ-shore distribution of the southern right whale in summer. Rep. int. Whal.
Commn. (Special lssue) 10: 177–185.
1987
Kato, H. and Ohsumi, S. 1987. Further estimation of mean size at recruitment for the southern minke whale in the Antarctic
whaling operations (Japan+USSR). Paper SC/39/Mi4 presented to the IWC Scientiﬁc Committee, June 1987 (unpublished). 12 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1987. Comments submitted by S. Ohsumi (Japan) on the research plan for the feasibility study on ‘The programfor research on the Southern Hemisphere minke whale and for preliminary research on the marine ecosystem in the
Antarctic’ by the Government of Japan. Paper SC/D87/9 presented to the IWC Scientiﬁc Committee Special Meeting
to Consider the Japanese Research Permit (Feasibility Study), Cambridge, December 1987 (unpublished). [Paper available from the Oﬃce of the IWC].
Ohsumi, S. and Miyashita, T. 1987. Report of the sub-committee on Southern Hemisphere minke whales, Appendix 10. Yearly change in density indices of minke whales in Brazilian coastal whaling. Rep. int. Whal. Commn. 37: 85–86.
1988
Ohsumi, S. 1988. A criticism on parameters of stock-recruitment model currently applied to baleen whales by the IWC/SC.
Paper SC/40/O 36 presented to the IWC Scientiﬁc Committee, May 1988 (unpublished). 8 pp. [Paper available fromthe Oﬃce of the IWC].
1990
Ohsumi, S. 1990. Some proposals related to management advice for the Antarctic minke whale. Paper SC/42/SHMi15 presented to the IWC Scientiﬁc Committee, June 1990 (unpublished). 12 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1990. Report of the Scientiﬁc Committee, Annex O. Comments on the Japanese scientiﬁc permit proposal for
1989–90, O1: Summary of the research objectives in the Japanese original programme (SC/39/O4). Rep. int. Whal.
Commn. 40: 172.
1991
Ohsumi, S. 1991. A review of population studies on the North Paciﬁc minke whale stocks. Paper SC/43/Mi26 presented to
the IWC Scientiﬁc Committee, May 1991 (unpublished). 24 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1991. Memories: Takahisa Nemoto. Mar. Mamm. Sci. 7(3）: 324–325.
1992
Ohsumi, S. 1992. Lethal and non-lethal methods for research takes of cetaceans. IBI Rep. Int. Mar. Biol. Res. Inst. 3: 9–14.
(In Japanese with English summary).
Ohsumi, S., Kato, H. and Kasuya, T. 1992. Report of the sub-committee on North Paciﬁc minke whales, Appendix 2. Review
of stock identity of western North Paciﬁc minke whales. Rep. int. Whal. Commn. 42: 163–164.
1993
Ohsumi, S. 1993. A review on population studies of the North Paciﬁc Bryde’s whale stocks. Paper SC/45/O11 presented to
the IWC Scientiﬁc Committee, April 1993 (unpublished). 31 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1993. Report of the Scientiﬁc Committee, Annex L. Sanctuaries. Annex L1. Response to ‘Suggested questions tobe put the Scientiﬁc Committee’ from IWC/44/19. Rep. int. Whal. Commn 43: 204–205.
Ohsumi, S. 1993. Stock management of cetaceans. Honyurui Kagaku 32 (2): 185–190. (In Japanese)
Sigurjónsson, J., Ohsumi, S., Sakuramoto, K. and Komatsu, M. 1993. Report of the Scientiﬁc Committee, Annex O. Minority
statements. O4: Statement on the issue of presenting the Revised Management Procedure to the Commission. Rep. int.
Whal. Commn. 43: 219.
Ohsumi, S. and Shigemune, H. 1993. A sightings survey of larger whales in lower latitudinal waters of the Paciﬁc in austral
winter, with special reference to the blue whale. Paper Blue/WP6 presented to the ad hoc Steering Group Intersessional
Meeting on Research Related to Conservation of Large Baleen Whales—Blue Whales—in the Southern Ocean, Tokyo,
October 1993 (unpublished). 23 pp. [Paper available from the Oﬃce of the IWC].
1994
Hatanaka, H., Kato, H. and Ohsumi, S. 1994. Is the sub-stock scenario for minke whale stock structure in the waters surrounding Japan plausible? Paper SC/46/NP3 presented to the IWC Scientiﬁc Committee, May 1994 (unpublished). 15
pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S., Kawasaki, M. and Nishiwaki, S. 1994. Biological results of beaked whales surveyed by Japanese whale research
programme under special permit in the Antarctic and the need of their research take. Paper SC/46/SM15 presented to
the IWC Scientiﬁc Committee, May 1994 (unpublished). 24 pp. [Paper available from the Oﬃce of the IWC].
1995
Fukui, Y., Mogoe, T., Terawaki, Y., Ishikawa, H., Fujise, Y. and Ohsumi, S. 1995. Relationships between physiological status
and serum constituent values in minke whales (Balaenoptera acutorostrata). J. Reprod. Develop. 41 (3): 203–208.
Hatanaka, H. and Ohsumi, S. 1995. A biological consideration on the sub-stock of baleen whales. Paper SC/47/Mg2 presented to the IWC Scientiﬁc Committee, May 1995 (unpublished). 8 pp. [Paper available from the Oﬃce of the IWC].
Matsuoka, K. and Ohsumi, S. 1995. Yearly trend in population density of large baleen whales in the Antarctic Areas IV and V
in recent years. Paper SC/47/SH9 presented to the IWC Scientiﬁc Committee, May 1995 (unpublished). 25 pp. [Paper

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available from the Oﬃce of the IWC].
Ohsumi, S. 1995. A review of population studies of the North Paciﬁc Bryde’s whale stocks (revised). Paper SC/47/NP14 presented to the IWC Scientiﬁc Committee, May 1995 (unpublished). 35 pp. [Paper available from the Oﬃce of the IWC].
1996
Fukui, Y., Mogoe, T., Jung, Y.G., Terawaki, Y., Miyamoto, A., Ishikawa, H., Fujise, Y. and Ohsumi, S. 1996. Relationships
among morphological status, steroid hormones, and post-thawing viability of frozen spermatozoa of male minke
whales (Balaenoptera acutorostrata). Mar. Mamm. Sci. 12 (1): 28–37.
Iga, K., Fukui, Y., Miyamoto, A., Ishikawa, H. and Ohsumi, S. 1996. Endocrinological observations of female minke whales(Balaenoptera acutorostrata). Mar. Mamm. Sci. 12 (2): 296–301.
Ohsumi, S. 1996. Report of the Scientiﬁc Committee. Annex G, Appendix 3. Comparison of length distribution of Bryde’s
whales from several regions. Rep. int. Whal. Commn. 46: 156–159.
1997
Cooke, J., Fujise, Y., Leaper, R., Ohsumi, S. and Tanaka, S. 1997. An exploratory analysis of the age distribution of minke
whales collected during JARPA expeditions 1987/88 through 1995/96. Paper SC/M97/21 presented to the IWC Intersessional Working Group to Review Data and Results from Special Permit Research on Minke whales in the Antarctic,
May 1997 (unpublished). 11 pp. [Paper available from the Oﬃce of the IWC].
Fukui, Y., Mogoe, T., Ishikawa, H. and Ohsumi, S. 1997. Factors aﬀecting in vitro maturation of minke whales(Balaenoptera acutorostrata) follicular oocytes. Biol. Reprod. 56: 523–528.
Fukui, Y., Mogoe, T., Ishikawa, H. and Ohsumi, S. 1997. In vitro matured minke whale (Balaenoptera acutorostrata) follicular oocytes. Mar. Mamm. Sci. 13 (3): 395–404.
Kato, H., Ohsumi, S. and Hatanaka, H. 1997. Some suggestions of operation parameters for implementation trials of RMP on
the western North Paciﬁc stock of Bryde’s whales. Paper SC/49/NP3 presented to the IWC Scientiﬁc Committee, September 1997, Bournemouth (unpublished). 7 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1997. Development of objectives in the Japanese Whale Research Program under Special Permit in the Antarctic(JARPA). Paper SC/M97/10 presented to the IWC Intersessional Working Group to Review Data and Results fromSpecial Permit Research on Minke whales in the Antarctic, May 1997 (unpublished). 5 pp. [Paper available from theOﬃce of the IWC].
Ohsumi, S., Fujise, Y., Ishikawa, H., Hakamada, T, Zenitani, R. and Matsuoka, K. 1997. The fattiness of the Antarctic minke
whale and its yearly change. Paper SC/M97/18 presented to the IWC Intersessional Working Group to Review Data
and Results from Special Permit Research on Minke whales in the Antarctic, May 1997 (unpublished). 21 pp. [Paper
available from the Oﬃce of the IWC].
Ohsumi, S., Tanaka, S. and Kato, H. 1997. A review of the studies on estimation of biological parameters conducted under
the Japanese Whale Research Program under Special Permit in the Antarctic (JARPA). Paper SC/M97/2 presented to
the IWC Intersessional Working Group to Review Data and Results from Special Permit Research on Minke whales in
the Antarctic, May 1997 (unpublished). 25 pp. [Paper available from the Oﬃce of the IWC].
1998
Mogoe, T., Fukui, Y., Ishikawa, H. and Ohsumi, S. 1998. Morphological observations of frozen-thawed spermatozoa ofsouthern minke whales (Balaenoptera acutorostrata). J. Reprod. Dev. 44 (1): 95–100.
Mogoe, T., Fukui, Y., Ishikawa, H. and Ohsumi S. 1998. Eﬀects of diluent composition and temperature on motility andviability after liquid storage and cryopreservation of minke whale (Balaenoptera acutorostrata) spermatozoa. Mar.
Mamm. Sci. 14 (4): 854–860.
Ohsumi, S. 1998. Review on history of Japanese regulation measures for the sperm whaling in the North Paciﬁc. 12. Paper
SC/50/CAWS12 presented to the IWC Scientiﬁc Committee June 1998 (unpublished). 12 pp. [Paper available from theOﬃce of the IWC].
Ohsumi, S. 1998. Annex D. Report of the Working Group on the RMP. Appendix 6. A review of the catch history of Bryde’s
whales by Soviet whaling in the North Paciﬁc. Rep. int. Whal. Commn. 48: 139–142.
Pastene, L.A. and Ohsumi, S. 1998. A brief review of the information on distribution and stocks identity of Bryde’s whales(Balaenoptera edeni) in the eastern South Paciﬁc. Paper SC/50/CAWS6 presented to the IWC Scientiﬁc Committee,
April 1998 (unpublished). 18 pp. [Paper available from the Oﬃce of the IWC]
1999
Brownell, R.L., Kasuya, T., Kato, H. and Ohsumi, S. 1999. Report of the Scientiﬁc Committee, Annex E. Appendix 7. Reportof the ad hoc intersessional sperm whale group meeting. J. Cetacean Res. Manag. (Supplement) 1: 147.
Fujise, Y. and Ohsumi, S. 1999. Progress of the outstanding tasks identiﬁed at the JARPA review meeting. Paper SC/51/
CAWS13 presented to the IWC Scientiﬁc Committee, May 1999 (unpublished). 5 pp. [Paper available from the Oﬃceof the IWC].
Hatanaka, H., Ohsumi, S., Kato, H. and Miyashita, T. 1999. Report of the Scientiﬁc Committee, Annex D. Appendix 11.
Consideration of the form of Bryde’s whales around oceanic/isolated islands, especially in the Leeward Hawaiian Islands area. J. Cetacean Res. Manag. (Supplement) 1: 106–107.
Miyashita, T., Hatanaka, H. and Ohsumi, S. 1999. Some considerations on within-stock structure hypothesis for the western
North Paciﬁc Bryde’s stock using CPUE data. Paper SC/51/RMP6 presented to the IWC Scientiﬁc Committee, May
1999, Grenada, WI (unpublished). 10 pp. [Paper available from the Oﬃce of the IWC].
Ohsumi, S. 1999. Signiﬁcance, history and status of cetacean research takes. IBI Int. Mar. Biol. Res. Inst. 9: 2–12. (In60

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Shigemune, H., Yamamura, K., Ohsumi, S. and Hatanaka, H. 1999. The plausibility of catch records of Bryde’s whales reported by the former USSR Government. Paper SC/51/RMP2 presented to the IWC Scientiﬁc Committee, May 1999,
Grenada, WI (unpublished). 27 pp. [Paper available from the Oﬃce of the IWC].
2000
Asada, M., Horii, M., Mogoe, T., Fukui, Y., Ishikawa, H. and Ohsumi, S. 2000. In vitro maturation and ultrastructural observation of cryopreserved minke whale (Balaenoptera acutorostrata) follicular oocytes. Biol. Reprod. 62 (2): 253–259.
Goto, M. and Ohsumi, S. 2000. Response to “Scientiﬁc Whaling Source of illegal Products for Market” by Baker et al. Science 290: 1695–1696.
Mogoe, T., Suzuki, T., Asada, M., Fukui, Y., Ishikawa, H. and Ohsumi, S. 2000. Functional reduction of the Southern minke
whale (Balaenoptera acutorostrata) testis during the feeding season. Mar. Mamm. Sci. 16 (3): 559–569.
Ohsumi, S., Hatanaka, H. and Fujise, Y. 2000. Review on the objectives of Japanese Whale Research Program under Special Permit in the north-western North Paciﬁc (JARPN). Paper SC/F2K/J29 presented to the Workshop to Review theJapanese Whale Research Programme under Special Permit for North Paciﬁc Minke Whales (JARPN), February 2000
(unpublished). 7 pp. [Paper available from the Oﬃce of the IWC].
Tamura, T. and Ohsumi, S. 2000. Regional assessments of prey consumption by marine cetaceans in the world. Paper SC/52/
E6 presented to the IWC Scientiﬁc Committee, June 2000 (unpublished). 42 pp. [Paper available from the Oﬃce of the
IWC].
Tamura, T., Ohsumi, S. and Fujise, Y. 2000. Some examinations on body fatness of the western North Paciﬁc minke whales.
Paper SC/F2K/J25 presented at the JARPN Review Meeting, Tokyo, Japan, 7–10 February 2000 (unpublished). 20 pp.
[Paper available from the Oﬃce of the IWC].
2001
Asada, M., Tetsuka, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2001. Improvement on in vitro maturation, fertilization anddevelopment of minke whale (Balaenoptera acutorostrata) oocytes. Theriogenology 56 (4): 521–533.
Masatsugu, A., Wei, H., Nagayama, R., Tetsuka, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2001. An attempt at intracytoplasmic sperm injection of frozen-thawed minke whale (Balaenoptera bonaerensis) oocytes. Zygote 9: 299–307.
Suzuki, T., Mogoe, T., Asada, M., Miyamoto, A., Tetsuka, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2001. Plasma and pituitary concentrations of gonadotropins (FSH and LH) in minke whales (Balaenoptera acutorostrata) during the feeding
season. Theriogenology 55 (5): 1127–1141.
2002
Ohsumi, S. and Tamura, T. 2002. Dietary studies on baleen whales in the North Paciﬁc. Proceedings of International Commemorative Symposium, 70th Anniversary of the Japanese Society of Fisheries Science. Fisheries Science 68 (Sup. 1):
260–263.
Miyashita, T., Kato, H., Matsuoka, K., Hakamada, T., Nishiwaki, S. and Ohsumi, S. 2002. Abundance and biomass of major
cetaceans occurring in the western North Paciﬁc particularly in sub-areas 7, 8 and 9 and biological aspects of cetacean
species to be sampled by JARPN II. Appendix 1 of SC/54/O2. (unpublished). 10 pp. [Paper available from the Oﬃce of
the IWC].
2004
Amemiya, K., Iwanami, Y., Kobayashi, T., Terao, T., Fukui, Y., Ishikawa, H., Ohsumi, S., Hirabayashi, M. and Hochi, S.
2004. Acquirement of oocyte-activating factor in Antarctic minke whale (Balaenoptera bonaerensis) spermatogenic
cells, assessed by meiosis resumption of microinseminated mouse oocytes. J. Mamm. Ova Res. 21: 149–156.
Bando, T., Zenitani, R. and Ohsumi, S. 2004. Preliminary investigation of stock structure of B-C-B bowhead whales basedon analysis of biological parameters. Paper SC/56/BRG33 presented to the IWC Scientiﬁc Committee, July 2004, Sorrento, Italy (unpublished). 13 pp. [Paper available from the Oﬃce of the IWC].
Danielsdóttir, A.K., Borodin, R., Diake, S., Diaz, E., Fujise, Y., Goodman, D., Goto, M., Gunnlaugsson, T., Hakamada, T.,
Hatanaka, H., Haug, T., Hester, F., Kanda, N., Kato, H., Kawahara, S., Kingsley, M., Kitakado, T., Lawrence, N., Magloire, A., Matsuda, H., Matsuoka, K., Miyashita, T., Morishita, J., Murase, H., Nagatomo, T., Nakatsuka, S., Nishiwaki, S., Okamura, H., Ohsumi, S., Ólafsdóttir, D., Rambally, J., Rennie, J., Shimada, H., Sigurjonsson, J., Víkingsson,
G.A., Walløe, L., Walters, H. and Yoshida, H. 2004. Report of the Scientiﬁc Committee. Annex O. Report of the Standing Working Group on Scientiﬁc Permit Proposals. Appendix 3. Response to Appendix 2 regarding scientiﬁc permits. J.
Cetacean Res. Manag. (Supplement) 6: 365–366.
Fujihira, T., Kinoshita, M., Sasaki, M., Ohnishi, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2004. Comparative studies onlipid analysis and ultrastructure in porcine and southern minke whale (Balaenoptera bonaerensis) oocytes. J. Reprod.
Develop. 50 (5): 525–532.
Fukui, Y., Togawa, M., Abe, N., Takano, Y., Asada, M., Okada, A., Iida, K., Ishikawa, H. and Ohsumi, S. 2004. Validation of
the sperm quality analyzer and the hypo-osmotic swelling test for frozen-thawed ram and minke whale (Balaenoptera
bonarensis) spermatozoa. J. Reprod. Develop. 50 (1): 147–154.
Hatanaka, H., Ohsumi, S., Kato, H., Morishita, J., Matsuoka, K., Goodman, D., Forde, H., Rennie, J., Hester, F., Diaz, E. andDiake, S. 2004. Report of the Scientiﬁc Committee. Annex P. Report of the Working Group to Review Sanctuaries andSanctuary Proposals. Appendix 3. An evaluation of the proposed South Atlantic whale sanctuary based on the instructions provided by the Commission in 2001. J. Cetacean Res. Manag. (Supplement) 6: 373–374.
Ikumi, S., Sawai, K., Takeuchi, Y., Iwayama, H., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2004. Interspecies somatic cell

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nuclear transfer for in vitro production of Antarctic minke whale (Balaenoptera bonaerensis) embryos. Cloning StemCells 6 (3): 284–293.
Iwayama, H., Hochi, S., Kato, M., Hirabayashi, M., Kuwayama, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2004. Eﬀects
of cryodevice type and donor’s sexual maturity on vitriﬁcation of minke whale (Balaenoptera bonaerensis) oocytes atgerminal vesicle-stage. Zygote 12 (4): 333–338.
Muranishi, Y., Sasaki, M., Hayashi, K., Abe, N., Fujihira, T., Ishikawa, H., Ohsumi, S., Miyamoto, A. and Fukui, Y. 2004.
Relationship between the appearance of preantral follicles in the fetal ovary of Antarctic minke whales (Balaenoptera
bonaerensis) and hormone concentrations in the fetal heart, umbilical cord and maternal blood. Zygote 12 (2): 125–132.
Tetsuka, M., Asada, M., Mogoe, T., Fukui, Y., Ishikawa, H. and Ohsumi, S. 2004. The pattern of ovarian development in the
prepubertal Antarctic minke whale (Balaenoptera bonaerensis). J. Reprod. Develop. 50 (4): 381–389.
Watanabe, H., Mogoe, T., Asada, M., Hayashi, K., Fujise, Y., Ishikawa, H., Ohsumi, S., Miyamoto, A. and Fukui, Y. 2004.
Relationship between serum sex hormone concentrations and histology of seminiferous tubules of captured baleen
whales in the western North Paciﬁc during the feeding season. J. Reprod. Develop. 50 (4): 419–427.
2005
Bando, T., Hakamada, T. and Ohsumi, S. 2005. Estimation of pregnancy rate of the western North Paciﬁc Bryde’s whale. Paper SC/O05/BWI5 presented to the First Intersessional Workshop for Western North Paciﬁc Bryde’s Whale Implementation, Tokyo, October 2005 (unpublished). 5 pp. [Paper available from the Oﬃce of the IWC].
Bando, T., Kishiro, T., Ohsumi, S., Zenitani, R. and Kato, H. 2005. Estimation of some biological parameters of western
North Paciﬁc Bryde’s whale by age distribution. Paper SC/O05/BWI7 presented to the First Intersessional Workshop
for Western North Paciﬁc Bryde’s Whale Implementation, Tokyo, October 2005 (unpublished). 10 pp. [Paper available
from the Oﬃce of the IWC].
Fukui, Y., Ishikawa, H. and Ohsumi, S. 2005. Diﬃculties in publishing research results from scientiﬁc whaling. Mar. Mamm.
Sci. 21 (4): 781–783.
Hakamada, T., Bando, T. and Ohsumi, S. 2005. Estimation of lower bound of MSYR for western North Paciﬁc Bryde’s
whale. Paper SC/O05/BWI4 presented to the First Intersessional Workshop of Western North Paciﬁc Bryde’s Whale
Implementation, Tokyo, October 2005 (unpublished). 7 pp. [Paper available from the Oﬃce of the IWC].
Hakamada, Ohsumi, S., Punt, A. E. and Butterworth, D. S. 2005. Natural mortality coeﬃcient for the Bryde’s whale estimated from commercial and JARPN II samples. Paper SC/O05/BWIWP5 presented to the First Intersessional Workshop ofWestern North Paciﬁc Bryde’s Whale Implementation, Tokyo, October 2005 (unpublished). 2 pp. [Paper available fromthe Oﬃce of the IWC].
Iwayama, H., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2005. Attempt at in vitro maturation of minke whale (Balaenoptera bonaerensis) oocytes using a portable CO2 incubator. J. Reprod. Develop. 51 (1): 69–75.
Matsuoka, K., Kiwada, H., Fujise, Y. and Ohsumi, S. 2005. Distribution pattern of sperm whales in the western North Paciﬁcbased on sighting survey data of the JARPN/JARPN II between 1994 and 2004. Paper A&D6 presented to the International Cachalot Assessment Research Planning (CARP) Workshop, Woods Hole, Massachusetts, 1–3 March 2005
(unpublished). 16 pp.
Matsuoka, K., Kiwada, H., Hakamada, T., Nishiwaki, S. and Ohsumi, S. 2005. Distribution and Abundance of Large Male
Sperm Whales in the Antarctic Areas IIIE, IV, V and VIW (35°E–145°W). Paper A&D 7 presented to the International
Cachalot Assessment Research Planning (CARP) Workshop, Woods Hole, Massachusetts, 1–3 March 2005 (unpublished). 13 pp.
Ohsumi, S. 2005. Estimation of number of western North Paciﬁc Bryde’s whales stock caught by Japanese coastal whaling
before 1946. Paper SC/M05/Br7 presented to the Workshop on the pre-implementation assessment of western North
Paciﬁc Bryde’s whales, Tokyo, Japan, 21–24 March 2005 (unpublished). 6 pp. [Paper available from the Oﬃce of the
IWC].
Ohsumi, S. and Hatanaka, H. 2005. Some considerations on the diﬀerence between pregancy rate and birth rate in the western North Paciﬁc Bryde’s whale. Paper SC/O05/BWIWP2 presented at the Bryde’s whale implementation workshop,
Tokyo, 25–29 October 2005 (unpublished). 2 pp. [Paper available from the Oﬃce of the IWC].
2006
Fujihira, T., Kobayashi, M., Hochi, S., Hirabayashi, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2006. Developmental capacity of Antarctic minke whale (Balaenoptera bonaerensis) vitriﬁed oocytes following in vitro maturation, and parthenogenetic activation or intracytoplasmic sperm injection. Zygote 14 (2): 89–95.
Fujise, Y., Hatanaka, H. and Ohsumi, S. 2006. What has happened to the Antarctic minke whale stocks? — An interpretationof results from JARPA. Paper SC/D06/J26 presented to the JARPA Review Meeting, December 2006 (unpublished). 15
pp. [Paper available from the Oﬃce of the IWC].
Hatanaka, H., Fujise, Y., Pastene, L. A. and Ohsumi, S. 2006. Review of JARPA research objectives and update of the work
related to JARPA tasks derived from the 1997 SC meeting. Paper SC/D06/J1 presented to the JARPA Review Meeting,
December 2006 (unpublished). 12 pp. [Paper available from the Oﬃce of the IWC].
Watanabe, H., Tateno, H., Kusakabe, H., Kamiguchi, Y., Fujise, Y., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2006. Fertilizability and chromosomal integrity of frozen-thawed Bryde’s whale (Balaenoptera edeni) spermatozoa intracytoplasmicallyinjected into mouse oocytes. Reprod. Fertil. Dev. 19 (1): 306–306.
2007
Asada, M., Tetsuka, M., Ishikawa, H., Ohsumi, S. and Fukui, Y. 2007. Ultrastructural changes during maturation and cryo-

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preservation of follicular oocytes of Antarctic minke whales (Balaenoptera bonaerensis). Jpn. J. Zoo. Wildl. Med. 12(1): 51–66.
Fukui, Y., Iwayama, H., Matsuoka, T., Nagai, H., Koma, N., Mogoe, T., Ishikawa, H., Fujise, Y., Hirabayashi, M., Hochi,
S., Kato, H. and Ohsumi, S. 2007. Attempt at intracytoplasmic sperm injection of in vitro matured oocytes in common
minke whales (Balaenoptera acutorostrata) captured during the Kushiro coast survey. J. Reprod. Develop. 53 (4):945–952.
Government of Japan (Compiled by Fujise, Y., Pastene, L.A., Hatanaka, H., Ohsumi, S. and Miyashita, T.), 2007. Evaluationof 2005/06 and 2006/07 feasibility study of the Second Phase of the Japanese Whale Research Program under Special
Permit in the Antarctic (JARPA II). Paper SC/59/O3 presented to the IWC Scientiﬁc Committee, May 2007 (unpublished). 23 pp. [Paper available from the Oﬃce of the IWC].
Hakamada, T., Ohsumi, S., Punt, A. and Butterworth, D. S. 2007. Western North Paciﬁc Bryde’s whale Implementation: Report of the First Intersessional Workshop, 25–29 October 2005, Shizuoka, Japan. Annex J. Natural mortality coeﬃcientfor the Bryde’s whale estimated from commercial and JARPN II samples. J. Cetacean Res. Manag. (Supplement) 9:426.
Nagai, H., Mogoe, T., Ishikawa, H., Hochi, S., Ohsumi, S. and Fukui, Y. 2007. Follicle size-dependent changes in follicularﬂuid components and oocyte diameter in Antarctic minke whales (Balaenoptera bonaerensis). J. Reprod. Develop. 53(6): 1265–1272.
Ohsumi, S., Goto, M. and Otani, S. 2007. Necessity of combining lethal and non-lethal methods for whale population research and their application in JARPA. Paper SC/59/O2 presented to the IWC Scientiﬁc Committee, May 2007 (unpublished). 7 pp. [Paper available from the Oﬃce of the IWC].
Watanabe, H., Tateno, H., Kusakabe, H., Matsuoka, T., Kamiguchi, Y., Fujise, Y., Ishikawa, H., Ohsumi, S. and Fukui, Y.
2007. Fertilizability and chromosomal integrity of frozen-thawed Bryde’s whale (Balaenoptera edeni) spermatozoa
intracytoplasmically injected into mouse oocytes. Zygote 15 (1): 9–14.
2008
Bhuiyan, M.M.U., Suzuki, Y., Watanabe, H., Hirayama, H., Matsuoka, K., Fujise, Y., Ishikawa, H., Ohsumi, S. and Fukui,
Y. 2008. Attempts at in vitro fertilization and culture of in vitro matured oocytes in sei (Balaenoptera borealis) and
Bryde’s (B. edeni) whales. Zygote 17 (1): 19–28.
Ohsumi, S. and Kato, H. 2008. A bottlenose dolphin (Tursiops truncatus) with ﬁn-shaped hind appendages. Mar. Mamm. Sci.
24 (3): 743–745.
2009
Hiwasa, M., Suzuki, Y., Watanabe, H., Bhuiyan, M.M.U., Matsuoka, K., Fujise, Y., Ishikawa, H., Ohsumi, S. and Fukui, Y.
2009. Eﬀects of semen extenders and storage temperatures on characteristics of frozen-thawed Bryde’s (Balaenoptera
edeni) whale spermatozoa. J. Reprod. Develop. 55: 599–606.
2010
Bhuiyan, M. M. U., Suzuki, Y., Watanabe, H., Lee, E., Hirayama, H., Matsuoka, K., Fujise, Y., Ishikawa, H., Ohsumi, S. andFukui, Y. 2010. Production of sei whale (Balaenoptera borealis) cloned embryos by inter- and intra-species somatic
cell nuclear transfer. J. Reprod. Develop. 56: 131–139.
Fujise, Y., Hatanaka, H. and Ohsumi, S. 2010. Changes in the Antarctic marine ecosystem as revealed by the JARPA research: What has happened to the Antarctic minke whale stocks? Ottar (Tromsø Museum) 280: 29–34. (In Norwegian).
Hatanaka, H. and Ohsumi, S. 2010. Comments on the paper by Wade and Brownell titled ‘A review of the biology of western
North Paciﬁc minke whales relevant to stock structure’ (SC/62/NPM13). Paper SC/62/NPM28 presented to the IWC
Scientiﬁc Committee, May 2010 (unpublished). 2 pp. [Paper available from the Oﬃce of the IWC].
Suzuki, Y., Umatani, M., Bhuiyan, M.M.U., Watanabe, H., Mogoe, T., Matsuoka, K., Fujise, Y., Ishikawa, H., Ohsumi, S.,
Sasaki, M. and Fukui, Y. 2010. Eﬀects of equilibration steps, type of sugars and addition of whale follicular ﬂuid on
viability and in vitro maturation of vitriﬁed whale oocytes. Jpn. J. Zoo Wildl. Med. 15 (2): 65–72.
2013
Sasaki, M., Amano, Y., Hayakawa, D., Tsubota, T., Ishikawa, H., Mogoe, T., Ohsumi, S., Tetsuka, M., Miyamoto, A., Fukui,Y., Budipitojo, T. and Kitamura, N. 2013. Structure and steroidogenesis of the placenta in the Antarctic minke whale(Balaenoptera bonaerensis). J. Reprod. Develop. 59 (2): 159–167.
2014
Mogoe, T., Bando, T., Maeda, H., Kato, H. and Ohsumi, S. 2014. Biological observations of ﬁn whales sampled by JARPAII
in the Antarctic. Paper SC/F14/J10 presented to the IWC/SC Review Workshop of the Japanese Whale Research Program under Special Permit in the Antarctic—Phase II (JARPAII), February 2014 (unpublished). 18 pp. [Paper available
from the Oﬃce of the IWC].
2015
Funasaka, N., Kirihata, T., Kato, H. and Ohsumi, S. 2015. The ﬁrst record of a true albino common bottlenose dolphin
Tursiops truncatus from Japan. Mammal Study 40 (1): 19–23.
Kanda, N., Bando, T., Matsuoka, K., Murase, H., Kishiro, T., Pastene, L.A. and Ohsumi, S. 2015. A review of the genetic andnon-genetic information provides support for a hypothesis of a single stock of sei whales in the North Paciﬁc. Paper
SC/66a/IA9 presented to the IWC Scientiﬁc Committee, May–June 2015 (unpublished). 18 pp. [Paper available fromthe Oﬃce of the IWC].
Kitayama, C., Sasaki, M., Ishikawa, H., Mogoe, T., Ohsumi, S., Fukui, Y., Budipitojo, T., Kondoh, D. and Kitamura, N.

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2015. Structure and functions of the placenta in common minke (Balaenoptera acutorostrata), Bryde’s (B. brydei) andsei (B. borealis) whales. J. Reprod. Develop. 61 (5): 415–421.
Funasaka, N., Kirihata, T., Hosono, M., Kato, H. and Ohsumi, S. 2017. Three cases of anomalously white Risso’s dolphins
Grampus griseus in Japan. Mammal Study 42 (3): 173–179.
2. Books & Book Contributions (58)1957
Ohmura, H., Nishiwaki, M., Fujino, K., Kimura, S. 1957. Kitataiheiyou san no higekujirarui no shigen ni tsuite (On thestocks of baleen whales in the North Paciﬁc Ocean). pp. 507–535. In: Suehiro, Y., Ohshima, Y. and Hiyama, Y. (eds.).
Compilations of Fisheries Science. Amemiya Ikusaku Sensei Kanreki Kinen (In commemoration of Dr. Ikusaku Amemiya’s 60th birthday). University of Tokyo Press, Tokyo. 890 pp. (In Japanese).
1974
Ohsumi, S. 1974. Nenrei keishitsu to nenrei sateihou (Age character and age determination). pp. 37–82. In: Nishiwaki, M.
(ed.). Shigen Seibutsuron (Fisheries Biology). University of Tokyo Press, Tokyo. 230 pp. (In Japanese).
Ohsumi, S. 1974. Hanshoku. (Reproduction). pp. 65–72. In: Nishiwaki, M. (ed.). Shigen Seibutsuron (Fisheries Biology).
University of Tokyo Press, Tokyo. 230 pp. (In Japanese).
Ohsumi, S. 1974. Kotaigun no saiseisan to ryouteki hendou. Kujira no shigen ni tsuite (Reproduction and quantitative variation in populations. On the whale stocks). pp. 138–146. In: Nishiwaki, M. (ed.). Shigen Seibutsuron (Fisheries Biology). University of Tokyo Press, Tokyo. 230 pp. (In Japanese).
Omura, H. and Ohsumi, S. 1974. Research on whale biology of Japan with special reference to the North Paciﬁc Stocks. pp.
196–208. In: Schevill, W. E. (ed.). The Whale Problem. A Status Report. Harvard University Press, Cambridge, Mass.
419 pp.
1976
Ohsumi, S. 1976. Suisan shigengaku no tachiba kara (From the viewpoint of ﬁsheries biology). pp. 7–22. In: Nippon Suisan
Gakkai (ed.). Suisan Shigen no Yuukou Riyou. Shigen Kanri kara Riyou Kakou made (Eﬀective Utilization of Fishery
Stocks—From Resource Management to Utilization Processing). Suisangaku Shiriizu 14 (Fisheries Science Series 14).
Koseisha-Koseikaku, Tokyo. 124 pp. (In Japanese).
1978
Ohsumi, S. 1978. Kujira. Umi no honyuurui. Shiriizu Umi 13 (Whales—Marine Mammals. Ocean Series 13). Rakuda,
Tokyo. 56 pp. (In Japanese).
1984
Ohsumi, S., (translator), 1984. Kujira to Iruka no Seitai (Ecology of Whales and Dolphins. By Gaskin, D. E., Heinemann Educational Books, 1982). University of Tokyo Press, Tokyo. 450 pp. (In Japanese).
1986
Macdonald, D. W. (editor), Ohsumi, S, (supervisor). 1986. Doubutsu daihyakka 2. Kaisei Honyuurui. (The Encyclopedia of
Animals 2: Marine Mammals). Heibonsha, Tokyo. 159 pp. (In Japanese).
Ohsumi, S. 1986. Nihon no Kaijuurui. Doubutsu Daihyakka 2. Kaiseihonyuurui (Sea Animals of Japan). pp. 20–23. In: Macdonald, D. W. (ed.), Ohsumi, S, (supervisor). The Encyclopedia of Animals 2: Marine Mammals). Heibonsha, Tokyo.
159 pp. (In Japanese).
Ohsumi, S. 1986. Umi no sachi—Kujira (Fruits of the Sea: Whales) pp. 140–141. In: Ichihara Motoi shasshinshuu. Kujira
no umi, otoko no umi. (Sea of Whales, Sea of Men. A Collection of Motoi Ichihara’s Photographs, by Motoi Ichihara).
Gyousei, Tokyo. 167 pp. (In Japanese).
1988
Ohsumi, S. 1988. Kujira wa mukashi riku wo aruiteita. Shijou saidai no doubutsu no shinpi (Whales Used to Walk on Land.
The Greatest Animal Mystery of All Time). First Edition. PHP Kenkyusho, Tokyo. 252 pp. (In Japanese).
1990
Ohsumi, S. 1990. Kaijuurui to ningen tono kyougou (Competition between marine mammals and man). pp. 254–265. In:
Miyazaki, N. and Kasuya, T. (eds.). Umi no honyuurui. Sono kako, genzai, mirai. (Biology of Marine Mammals). Scientist Inc., Tokyo. 300 pp. (In Japanese).
1991
Ohsumi, S., (supervisor), Kasamatsu, F. and Miyashita, T. 1991. Kujira to iruka no ﬁirudo gaido (Field Guide to Whales,
Dolphins and Porpoises). University of Tokyo Press, Tokyo. 148 pp. (In Japanese).
Ohsumi, S. 1991. Kokusai hogei iinnkai no katudou to geirui shigen chousa kenkyuu no hensen (Activities of the Scientiﬁc
Committee of the International Whaling Commission and the evolution of research on whale resources). pp. 1–21. In:
Sakuramoto, K., Kato, H. and S. Tanaka, S. (eds.). Geirui shigen no kenkyuu to kanri (Studies on Whale Stock Management). Koseisha-Koseikaku, Tokyo. 273 pp. (In Japanese).
Ohsumi, S. 1991. Kujira no seitai (Ecology of whales). pp. 122–129. In: Nakamura, Y. (ed.). Kujira uwotchingu ando
tatchingu. Goukaina umi no ouja tono deai. Kodansha karuchaa bukkusu (Whale and Dolphin Watching & Touching).
Encounters with the Mighty King of the Sea. Kodansha Culture Books). Kodansha, Tokyo. 144 pp. (In Japanese).
Ohsumi, S., (translator), 1991. Makkokujira rui (Sperm whales). pp. 92–99. In: Martin, A. R, Kasuya, T. (translation supervisor). Kujira Iruka Daizuukan (The Illustrated Encyclopedia of Whales and Dolphins). Heibonsha, Tokyo. 205 pp. (InJapanese).

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Ohsumi, S. 1991. Kujira wa horobiyuku no ka (Will whales be extinct?) pp. 90–94. In: Seki, T. and Koike, I. (eds.). Umi denani ga okotteiru ka (What’s Happening in the Ocean?). Iwanami Junior Series 195. Iwanami Shinshoten, Tokyo. 222
pp. (In Japanese).
1992
Ohsumi, S. 1992. Umi kara no sachi. Kujira (Food from the Sea—Whales). pp. 44–60. In: NHK Reporters (edｓ.). Umi tokawa no karibitotachi. Ningen ga nani wo tabetekita ka (Hunters of the Sea and Rivers: What have Humans been Eating?). NHK Shuppan, Tokyo. 236 pp. (In Japanese).
Ohsumi, S. 1992. Geiniku (Whale meat). pp. 20–21. In: Sugahara, T. and Inoue, S. (eds.) Shinhan genshoku shokuhin zukan(Color-Illustrated Book of Food). Kenmennsha, Tokyo. 300 pp. (In Japanese).
Ohsumi, S. (responsible editor), 1992. 4. Kujira, jugon, hoka. Doubutsutachi no chikyuu 52. Dai 9 Ken (Honyuurui II—4) (4.
Whales, Dugongs and Others. The Earth of Animals 52. Volume 9 (Mammals II) 10 Volumes (1 Combined Volume)).
Asahi Shinbunsha, Tokyo. pp. 98–128. (In Japanese).
1993
Ohsumi, S. 1993. Kujira no hanashi (Topics in Whale Research). Gihoudo Shuppan, Tokyo. 187 pp. (In Japanese).
Ohsumi, S. (supervisor), 1993. Kujira wa donna koi wo suru no ka (What Kind of Love do Whales Have?). Sekai Bunkasha,
Tokyo. 125 pp. (In Japanese).
Ohsumi, S. 1993. Kujira no riyou to hougo (Utilization and conservation of whale stocks). pp. 7–27. In: Takashima, F. andMatsuda, K. (eds.) Chikyuu ni yasahii umi no riyou—Chikyuu kankyo to suisangyou (Conservative Utilization of Global Resources—Global Environment and Fisheries). Koseisha-Koseikaku, Tokyo. 150 pp. (In Japanese).
Ohsumi, S. (Supervised). 1993. Kujira, Iruka (Whales and Dolphins). pp. 112–113. In: Nakamura, T., (ed.). Maameido
Doriimu Umi ni kaetta Doubutsutachi (The Mermaid Dream: Animals that returned to the Sea). TOTO Shuppan,
Tokyo. 120 pp. (In Japanese).
1994
Ohsumi, S. (Japanese version supervisor), Papastavrou, V. and Greenaway, F. 1994. Bijuaru hakubutsukan Dai 46 ken.
Kujira. Umi no samazamana honyuuruitachi no sekai wo saguru (Whales—Exploring the World of various Mammalsof the Sea. Visual Museum 46). Douhousha, Tokyo. 63 pp. (In Japanese).
Ohsumi, S. (supervisor), Yabuuchi M. (Author) 1994. Umi ni sumu doubutsutachi. Nihon no honyuurui II (Animals living inthe sea. Mammals of Japan II). Iwasaki Shouten, Tokyo. 48 pp. (In Japanese).
Ohsumi, S. (supervisor), 1994. Kujira no naze naze? (Chairudo kagaku ehonkan—Shizen naze naze ehon 5) (Whale’s WhyWhy-Why? (Child Science Picture Book Museum–Nature’ Why-Why-Why Picture Book 5). Chairudo Honsha, Tokyo.
30 pp. (In Japanese).
Ohsumi, S. 1994. Kujira no seitai. Kujira no shakai. Fushigina honyuurui, kujira. Kujira no gokan. Higekujira no esatorimajikku (Whale Biology. Whale society. Whales, wonderful mammals. The ﬁve senses of whales. The magic of baleen
whale feeding). pp. 22–32. In: Aruku Shuppan Kikaku (eds.). Kujira. Umi wo oyogu zunou. Shizen no techou shiriizu(Whales—The brains that swim in the sea. Nature Handbooks Series). Rippu Shobo, Tokyo. 223 pp. (In Japanese).
Ohsumi, S. (supervisor), 1994. Tokushu. Kujira—Umi ni kaetta honyuurui (Feature: Whales—The mammals that went backto the sea). Shoyon Charenji Rinji Zoukan Go. Waarudo ando Saiensu 4: 2–13. (In Japanese).
1995
Ohsumi, S. (supervisor), Setonami, T. (author), Asano, S. (illustrator), 1995. Oto de nakama to hanasu kujira, iruka: Chikyuu
no ashita wo kangaeyou. Big Chum 2 Ohanasi zukan 1 (Whales and Dolphins Talk using Sound. Big Chum 2. Storybook 1). Book Shuppan, Kobe. 17 pp. (In Japanese).
Ohsumi, S. 1995. Gaikoku de kujira wo taberu (Eating whale meat in foreign countries). pp. 56–57. In: Ohnishi, M. (ed.).
Tokuya Hiden Kujira Ryouri no Hon (Mrs. Ohnishi’s Whale Cuisine). Kodansha. Tokyo. 105 pp. (In Japanese).
1996
Ohsumi, S. 1996. Kokukujira. Shironagasukujira. Nagasukujira (Gray whale. Blue whale. Fin whale). pp. 34–45. In: Hidaka,T., Izawa, K., Kasuya, T. and Kawamichi, T. (eds.). Nihon doubutsu daihyakka 2. Honyuurui II (The Encyclopedia of
Animals in Japan. Mammals II). Heibonsha, Tokyo. 155 pp. (In Japanese).
Ohsumi, S. 1996. Kujirarui no shurui to seitai (Taxonomy and ecology of whales). pp. 1–24. In: Kitahara, T. (ed.). Kujira
ni manabu suisan shigen wo meguru kokusai jousei. Tokyo Suisan Daigaku Dai 22 kai koukai kouza (Learning from
Whales in the International Situation of Marine Resources). Seizando Shoten, Tokyo. 233. (In Japanese).
1997
Ohsumi, S. 1997. Kujira wa mukashi riku wo aruiteita (Whales Used to Walk on Land). First Paperback Edition. PHP
Kenkyusho. Tokyo. 307 pp. (In Japanese).
Ohsumi, S. (supervisor), 1997. Kujira to iruka. Naze naze kuizu Ehon 5. Chairudo kagaku ehonkan (Whales and dolphins.
Why-why-why Picture Book 5. Child Science Picture Book Museum). Chairudo Honsha, Tokyo. 30 pp. (In Japanese).
Ohsumi, S. 1997. Kujira no nomimizu. (Whale Drinking Water) pp. 32–41. In: Kanata, H. et al. (eds.). Gendai no Kokugo 1(Contemporary National Language 1). Sanseido, Tokyo. 276+34 pp. (In Japanese).
Ohsumi, S. 1997. Chouyaku. Kujira wa doushite jampusuru no ka (Leap –Why do Whales Jump?). pp. 16–29. In: Nakamura,T. (ed.). Flippers. Kujira+iruka paafekuto gaido (Flippers. Whale and Dolphin Perfect Guide. A Collection of Yasuo
Nakamura’s Photographs). Kourinsha Shuppan, Tokyo. 193 pp. (In Japanese).
Ohsumi, S. 1997. Aratana hogei no souzou wo mezashite (Creating a new style of whaling). pp. 197–205. In: Taiyo Gyogyo
Nanpyouyou Hogei Sendan no Kiroku wo Nokosu Kai (Society for Preserving the Records of the Taiyo Fisheries Co.

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Ltd. Southern Ocean Whaling Fleet (ed.). Hogei ni ikita (Living from Whaling). Seizando Shoten, Tokyo. 234 pp. (InJapanese).

1998
Ohsumi, S. (editorial advisor), Nakamura T., 1998. Iruka. Shizen Kindaabukku 8 (Dolphins. Nature Kinderbook 8). Fureberu
Kan, Tokyo. 29 pp. (In Japanese).
Ohsumi, S. (Supervision, commentary). 1998. Biijuaru Kujira Hyakka (Visual Whale Encyclopedia) pp. 58–61. In: NHK“Umi” Project (eds.) Umi—Shirazezaru Sekai. Dai 3 Ken (Visual Whale Encyclopedia. The Sea: The Unknown World.
Volume 3). NHK Shuppan, Tokyo. 136 pp. (In Japanese).
2000
Ohsumi, S. (author), Zhang L. (translator). 2000. Jing Tún Bówù Xué. Hăiyáng Zhōng de Jīng Tún Jùchăng (Cetacean Natural History. Whale and Dolphin Drama in the Ocean). Dàshù Weenhuà Shiyee Goungsii, Taipei. 270 pp. (In Chinese).
Ohsumi, S. 2000. Aratana hogei no souzou e mukete (Towards the creation of a new kind of whaling). p. 23. In: Suisan
Shokuryou Kenkyuukai Jimukyoku (ed.) Ni juu seiki no suisan, shokuryou e no yume to kitai (Dreams and expectations for Fisheries and Food in the 21st Century). Suisan Shokuryou Kenkyukai, Tokyo. 79 pp. (In Japanese).
2001
Ohsumi, S. 2001. (Dai 1 Sho) Kujira no shurui to sono seikatsu. ((Chapter 1) Species of Whales and their Lives. pp. 29–39.
In: Komatsu, M. (ed.). Kujira funsou no shinjitsu. Sono shirarezaru kako, genzai, soshite chikyuu no mirai (Facts about
the Whale Conﬂict. The Hidden Past, Present and Future of our Planet). Chikyuusha, Tokyo. 326 pp. (In Japanese).
Ohsumi, S. 2001. (Dai 7 Sho) Kujira wa dono gurai iru ka—Sekinin aru hogei wo tsuzukeru tame ni. ((Chapter 7) How many
whales are out here?—For Responsible Whaling Continuity). pp. 150–160. In: Komatsu, M. (ed.). Kujira funsou noshinjitsu. Sono shirarezaru kako, genzai, soshite chikyuu no mirai (Facts about the Whale Conﬂict. The Hidden Past,
Present and Future of our Planet). Chikyuusha, Tokyo. 326 pp. (In Japanese).
2002
Ohsumi, S. 2002. Kankou ni Atari (On the Occasion of Publication). pp. 5–6. In: Kato, H. (ed.) Geirui shigen kenkyu nosaizensen. Geirui shigen no jizokuteki riyou wa kanou ka (Frontiers of Cetacean Research: Can Whale Resources beused Sustainably?). Seibutsu Kenkyuusha, Tokyo. 212 pp. (In Japanese).
Ohsumi, S. 2002. Geirui shigen no riyou no rekishi to IWC (The History of the Utilization of Whale Resources and the
IWC). pp. 24–33. In: Kato, H. (ed.) Geirui shigen kenkyu no saizensen. Geirui shigen no jizokuteki riyou wa kanou ka(Frontiers of Cetacean Research: Can Whale Resources be used Sustainably?). Seibutsu Kenkyuusha, Tokyo. 212 pp.
(In Japanese).
Ohsumi, S. 2002. Kyokuyou Maru hokuyou hogei sendan ni yoru semikujira no tokubetsu hokaku chousa ni sankashite.
Mano Suehiro cho. Kujira no umi to tomo ni—Kyokuyou no kujiratoritachi no monogatari (Participation in the special
right whale research capture by the Kyokuyo-Maru North Sea whaling ﬂeet. pp. 110–114. In: Mano S., (ed.). Alongthe Sea of Whales: The Story of the Kyokuyo Whale Hunters). Chuuetsu Nagasaki Koujou, Nagasaki. 329 pp. (InJapanese).
2003
Ohsumi, S. 2003. Kujira to Nihonjin (Whales and the Japanese). Iwanami Shoten, Tokyo. 212 pp. (In Japanese).
Ohsumi, S. 2003. Engan iki de no kujira, irukarui no seitai chousahou (Dai 6 hen 4 shou). Takeuchi Hitoshi kanshuu.
Chikyuu kankyo chousa keisoku jiten. Dai 3 ken engan iki hen (Ecological Survey Methods for Whales and Dolphinsin Coastal Waters (Section 6, Chapter 4). pp. 743–747. In: Takeuchi Hitoshi (supervisor). Encyclopedia of Global
Environmental Surveys and Measurements, Volume 3, Coastal Areas). Fuji Tekunoshisutemu, Tokyo. 1297 pp. (InJapanese).
2006
Ohsumi, S. (supervisor), 2006. Honyuurui (Ohsumi Seiji, Uchida Senzo yaku). Shiriizu: Umi no doubutsu hyakka 1 (Mammals (Ohsumi, S. and Uchida, S., translators). Series: Encyclopedia of Sea Animals 1). Asakura Shoten, Tokyo. 77 pp.
(In Japanese).
2008
Ohsumi, S. 2008. Kujira wo otte hanseiki—Shin hogei jidai e no teigen (In Pursuit of Whales for Half a Century: Proposals
for the New Whaling Era). Seizando Shoten, Tokyo. 244 pp. (In Japanese).
2009
Barthelmess, K. and Ohsumi, S. 2009. Seiyou no hogei korekutaa ni yoru Nihon houmon ryokou kinen sasshi (Western
Whaling Collectors Visiting Japan). Schriften zur Kulturgeschichte von Mensch und Wal herausgegeben von Klaus
Barthelmess. Speckpresse, Cologne & Tokyo. Nr. 2: 43 pp. (In Japanese).
Ohsumi, S. (supervisor), Kasamatsu, F., Miyashita, T. and Yoshioka, M. 2009. Shinhan. Kujira to iruka no ﬁirudo gaido(New Edition—Field Guide to Whales, Dolphins and Porpoises in the Western North Paciﬁc and Adjacent Waters).
University of Tokyo Press, Tokyo. 148 pp. (In Japanese).
2010
Ohsumi, S. 2010. Kakuron 2. Kaisei honyuurui 2.1. Kujira moku. (Section 2: Marine Mammals 2.1. Cetacea. pp. 405–420.
In: Yasei Seibutsu Hogo Gakkai (ed.) Yasei doubutsu hogo no jiten (Encyclopedia of Wildlife Conservation). Asakura
Shoten, Tokyo. 792 pp. (In Japanese).
Ohsumi, S. 2010. Souron 19. Hogeigyou. (Topic 19: The Whaling Industry. pp. 87–89. In: Yasei Seibutsu Hogo Gakkai (ed.)
Yasei doubutsu hogo no jiten Encyclopedia of Wildlife Conservation. Asakura Shoten, Tokyo. 792 pp. (In Japanese).

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Ohsumi, S. 2010. Souron 23. Sunameri. Yasei doubutsu hogo no jiten (Topic 23: The Finless Porpoise. pp. 104–108.
In: Yasei Seibutsu Hogo Gakkai (ed.) Encyclopedia of Wildlife Conservation. Asakura Shoten, Tokyo. 792 pp. (InJapanese).
Ohsumi, S. 2015. Grundlage der japanischen Walfaorschung. pp. 140–148. In: Roder, H. (ed.) Faszination Wale - Von Menschen und Walen. TenDenZen 2015. Jahrbuch XXIII. Übersee-Museum, Bremen, Deutschland. 192 pp. (In German).
3. Reports and Booklets (40)1955
Kawakami, T., Fujino, K. and Kimura, S. 1955. 1954 Nendo hokuyou geizoku no seibutstugakuteki shigen chousa houkoku(Report on the 1954 Biological Resource Survey of the Northern Sea Cetaceans). Nihon Hogei Kyokai. 108 pp. (InJapanese).
1956
Fujino, K. and Kimura, S. 1956. 1955 Nendo hokuyou geizoku no seibutstugakuteki shigen chousa houkoku (Report on the1955 Biological Resource Survey of the Northern Sea Cetaceans). Nihon Hogei Kyokai. 74 pp. (In Japanese).
1957
Kimura, S. 1957. 1956 Nendo hokuyou geizoku no seibutstugakuteki shigen chousa houkoku (Report on the 1956 Biological
Resource Survey of the Northern Sea Cetaceans). Nihon Hogei Kyokai. 64 pp. (In Japanese).
1959
Ohsumi, S. 1959. 1958/59 Nendo nanpyouyousan geirui no seibutstugakuteki chousa houkoku (Report on the 1958/59 Biological Survey of Southern Ocean Cetaceans). Nihon Hogei Kyokai. 40 pp. (In Japanese).
Ohsumi, S. 1959. 1958/59 Nendo nanpyouyou ni okeru kujira no hyoushiki chousa. Hogei senpaku soubi kaizen iinnkai(Whale Marking Survey in the Southern Ocean 1958/59. Whaling Ship Equipment Improvement Committee). Hogei
Senpaku Soubi Kaizen Iinkai. 28 pp. (In Japanese).
Omura, H., Fujino, K., Ohsumi, S., Ichihara, T. and Nasu, K. 1959. Kitataiheiyou san nagasukujira no keituou ni kansuru
kenkyuu (Research on the North Paciﬁc Fin Whale Lineage). Geirui Kenkyujo. 24+4 pp. (In Japanese).
1962
Ohsumi, S. 1962. 1961 Nendo hokuyou geirui no seibutsugakuteki chousa houkoku (Report on the 1961 Biological Surveyof the Northern Sea Cetaceans). Geirui Kenkyujo. 52 pp. (In Japanese).
1964
Ohsumi, S. 1964. 1964 Nendo hokuyou san geirui no shigen chousa houkoku (Report on the 1964 Resource Survey of theNorthern Sea Cetaceans). Geirui Kenkyujo. 67 pp. (In Japanese).
1969
Ohsumi, S. 1969. Hogei ni okeru gyokaku doryoku to shigenryou shisuu (Fishing Eﬀort and Abundance Index in Whaling).
Geirui Kenkyusho. 32 pp. (In Japanese).
1972
Nishiwaki, M. and Ohsumi, S. 1972. Geirui no kousoshiki ni yoru nenrei satei (Age Assessment by Hard Tissues of Cetaceans). Kousoshiki Keisei Kouzou Kenkyuu Guruupu Kaiho: 12–17. (In Japanese).
1974
Ohsumi, S. 1974. Shuyou enyou gyogyou shigen II. Geirui shigen (Major Pelagic Fishery Resources II. Cetacean Resources). Suisancho Kenkyu Kaihatsubu. 40 pp. (In Japanese).
1981
Ohsumi, S. 1981. Kitataiheiyo no kaijuurui to sono gyogyou (Marine Mammals of the North Paciﬁc and their Fisheries).
Tokai-ku Suisan Kenkyujo. Houshasei Kotai Haikibutsu no Kaiyou Shobun ni tomonau Kaisan Seibutsu nado ni kansuru Chousa Houkokusho. Gyogyou oyobi Gyojou, Hai: 35–37. (In Japanese).
1985
Ohsumi, S. 1985. Geirui no bunpu to genzonryou oyobi hoshokuryo no suitei (Distribution of Cetaceans and estimates ofAbundance and Predation). Kyokuchi Kenkyujo. Nankyoku Kaiyouseibutsu Seitaikei no Kouzou to Kinou ni kansuru
Sougouteki Kenkyuu. Seika Houkokusho: 53–56. (In Japanese).
1986
Ohsumi, S. 1986. Gyogyou kougai (yuugai seibutsu jokyo) taisaku chousa itakujigyou chousa houkokusho (Showa 56–60
Nendo) (Report on the Investigation of the Commissioned Project for Fisheries Pest (Noxious Organisms’ Removal)
Control (1981–1985)). Suisancho Gyogyou Kougai Taisaku Chousa Kentouiinkai. 285 pp. (In Japanese).
1987
Ohsumi, S. 1987. Shigen doukou oyobi shigen hyouka (Resource Trends and Resource Assessment). 1984–1986
Kitataiheiyou ni okeru Sake-Masu Gyogyou ni kanrenshita Kaisanhonyuudoubutsu no Chousahoukoku. Suisancho:
91–1057. (In Japanese).
Ohsumi, S. 1987. Sono ta no kaisan honyuu doubutsu (Other Marine Mammals). 1984–1986 Kitataiheiyou ni okeru
Sake-Masu Gyogyou ni kanrenshita Kaisanhonyuudoubutsu no Chousahoukoku. Suisancho: 126–129. (In Japanese).
Ohsumi, S. 1987. Ishiiruka no seibutsugakuteki tokusei (Biological characteristics of Dall’s porpoises). 1984–1986
Kitataiheiyou ni okeru Sake-Masu Gyogyou ni kanrenshita Kaisanhonyuudoubutsu no Chousahoukoku. Suisancho:
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1989
Ohsumi, S. 1989. Hogei kichi Taiji-cho no saisei to kokusai geirui kenkyuu sentaa kousou dai 1 bu (Revitalization of Whaling Base Taiji and the Plan for an International Cetacean Research Center. Part 1). NIRA Kenkyuu Sousho 890064.
Wakayama Shakai Keizai Kenkyuusho: 9–60. (In Japanese).
1994
Ohsumi, S. 1994. Hokkyokukujira. Suisancho hen. Nihon no kishouna yasei suiseiseibutsu ni kansuru kisou shiryou (I) (The
Bowhead Whale. Basic Information on Rare and Wild Aquatic Organisms in Japan (I), ed. by Fisheries Agency. Nihon
Suisan Shigen Hogo Kyokai. 722 pp: 584–591. (In Japanese).
Ohsumi, S. 1994. Shironagasukujira. Suisancho hen. Nihon no kishouna yasei suiseiseibutsu ni kansuru kisou shiryou (I)(The Blue Whale. Basic Information on Rare and Wild Aquatic Organisms in Japan (I), ed. by Fisheries Agency. Nihon
Suisan Shigen Hogo Kyokai. 722 pp: 592–600. (In Japanese).
Ohsumi, S. 1994. Sumookingumashiin. Kujira hakase Omura Hideo san wo shinobu kai hen. Kujira hakase Omura Hideo san
wo shinobu (Smoking Machine. In Memory of Dr. Hideo Omura.). Kujira Hakase Omura Hideo san wo Shinobu Kai.
200 pp: 24–29. (In Japanese).
1995
Ohsumi, S. 1995. Geirui shigen chousa ni okeru chisiteki houhou no tekiyou no hitsuyousei. Hogei to kagaku (The Need forApplication of Lethal Methods in Cetacean Stock Research. Whaling and Science). Nihon Geirui Kenkyusho. 31 pp:
11–19. (In Japanese).
Ohsumi, S. 1995. Kokukujira. Suisancho hen. Nihon no kishouna yasei suiseiseibutsu ni kansuru kisou shiryou (II) (TheGray Whale. Basic Information on Rare and Wild Aquatic Organisms in Japan (II), ed. by Fisheries Agency. Nihon Suisan Shigen Hogo Kyokai. 751 pp: 513–520. (In Japanese).
Ohsumi, S. 1995. The necessity of employing lethal methods in the study of whale resources. Research on Whales. The Institute of Cetacean Research. 38 pp: 13–22.
1996
Ohsumi, S. 1996. Minkukujira. Suisancho hen. Nihon no kishouna yasei suiseiseibutsu ni kansuru kisou shiryou (III) (TheMinke Whale. Basic Information on Rare and Wild Aquatic Organisms in Japan (III), ed. by Fisheries Agency. Nihon
Suisan Shigen Hogo Kyokai. 582 pp: 92–104. (In Japanese).
Ohsumi, S. 1996. Nagasukujira. Suisancho hen. Nihon no kishouna yasei suiseiseibutsu ni kansuru kisou shiryou (III) (TheFin Whale. Basic Information on Rare and Wild Aquatic Organisms in Japan (III), ed. by Fisheries Agency. Nihon Suisan Shigen Hogo Kyokai. 582 pp: 306–311. (In Japanese).
1997
Ohsumi, S. 1997. Tayori ni sareru kenkyusho wo! (A Research Institute to be relied on!). Nihon Geirui Kenkyujo Juunenshi:
202–204. (In Japanese).
Ohsumi, S. 1997. Zadankai. Nichigeiken no seturitsu to hogei mondai wo meguru kokusai josei (Sono 1) (The establishmentof the ICR and the International situation regarding the Whaling Issue). Nihon Geirui Kenkyusho Juunenshi: 53–78. (InJapanese).
1999
Tamura, T. and Ohsumi, S. 1999. Estimation of Total Food Consumption by Cetaceans in the World Oceans. The Institute of
Cetacean Research. 12 pp.
2001
Ohsumi, S. 2001. Kenkyuu kara no INPFC e no kanyou. Kitataiheiyou gyogyou kaisouroku henshuuiinkai hen. Kitataiheiyou gyogyou kaisouroku (Involvement in INPFC from Research. North Paciﬁc Fishery Memoirs Editorial Board (ed.).
North Paciﬁc Fishery Memoirs). Kitataiheiyou Gyogyou Kaisouroku Henshuuiinkai. 455 pp: 88–93. (In Japanese).
2003
Ohsumi, S. 2003. Hakkan ni yosete. Dentou hogei e no hokori. Atarashii hogei no kouchiku. Nagato-shi, Nihon geirui kenkyusho hen. Dai 1 kai nihon dentou hogei chiiki samitto kaisai no kiroku (Foreword: Traditional Whaling and the Pursuitof Sustainable Whaling). Nagato City, the Institute of Cetacean Research (eds.). Report and Proceedings of the 1st
Summit of Japanese Traditional Whaling Communitites: Nagato.). Nihon Geirui Kenkyusho, Nagato-shi. 168 pp: 5. (InJapanese).
2005
Ohsumi, S. 2005. Nihon gata hogei no nanpyouyiou e no tenkai. Sono rekishi to shourai. Nihon geirui kenkyusho hen. Nanpyouyou hogei 100 shuunen kinen sinpojiumu houkokusho. Nanpyouyou hogei ni manabu koto—Nanpyouyou hogei
kaishi 100 shuunen kinen sinpojiumu kaisai no kiroku (Development of Japanese-style Whaling in the Antarctic: Its
History and Future. In “Learning from the Antarctic Whaling”. Report and Proceedings, International Symposium
Commmemorating Centennial of the Antarctic Whaling). Nihon Geirui Kenkyusho. 103 pp: 86–103. (In Japanese).
2006
Ohsumi, S. 2006. Kushiro no hogei no souki saikai wo kishite. Kushiro shi soumubu chiiki shiryoushitsu hen. Kushiro hogeishi (In Hope of an early reopening of Kushiro’s Whaling. Regional Archives, General Aﬀairs Department, Kushiro City(ed.). Kushiro Whaling History). Kushiro-shi, Hokkaido. 379 pp. (In Japanese).
Ohsumi, S. 2006. Naze nihon ga nanpyouyou hogei ni ikinokoreta ka? Nihon geirui kenkyujo, Shimonoseki-shi hen. Dai 4
kai nihon dentou hogei chiiki samitto kaisai no kiroku (Why Japan Survives in the Antarctic Whaling? In: Institute of
Cetacean Research and Shimonoseki city (eds.). Report and Proceedings of the 4th Summit of Japanese Traditional

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Whaling Communities. Shimonoseki city. Yamaguchi. Shimonoseki shi, Nihon Geirui Kenkyusho. 137 pp: 45–58. (InJapanese).

2007
Ohsumi, S. 2007. Harabire no aru bandouiruka (A Bottlenose Dolphin with Belly Fins). Taiji Chouritsu Kujira no
Hakubutsukan. Wakayama. 14 pp. (In Japanese).
2008
Ohsumi, S. 2006. Maegaki. Taiji Makoto hen. Kujira kata sounanshi. Sono shijitsu no ronkou to kenshou. (Preface. Taiji, M.
(ed.) The History of the Whalers’ Mishap: A Discussion and Veriﬁcation of Historical Facts). Shikaban. 242 pp: 1–5.
(In Japanese).
2009
Ohsumi, S. 2009. Hoeeruuotchingu to hogei wa kyouzon dekiru (Ship & Ocean Newsletter No. 189 keisai). Hito to kaiyou
no kyousei wo mezashite 150 nin no opinion IV (Whale Watching and Whaling can Coexist (Published in Ship &Ocean Newsletter No. 189). 150 Opinions on the Coexistence of Man anda the Ocean IV). Kaiyou Seisaku Kenkyu
Zaidan. 347 pp: 180–181. (In Japanese).
2011
Ohsumi, S. 2011. Chousa hogei towa. Fukuoka-shi hakubutsukan. Nihon to kujira ten jikkouiinkai hen. Nihon to kujira.
Fukuoka-shi hakubutsukan heisei ni juu san nendo tokubetsu kikakuten (What is Research Whaling? Fukuoka City
Museum, Japan and Whales Exhibition Executive Committee (ed.). Japan and Whales: Fukuoka City Museum Special
Exhibition, 2013. Nihon to Kujiraten Jikkouiinkai. 248 pp: 120. (In Japanese).
2015
Ohsumi, S. 2015. Suisen no ji. Yobuko kujira gumi no seikatsu wo tatae, honsho wo tsuyoku suisensuru. 1. Yobuko kujiragumi hen. Yobuko to kujira no hanashi (Recommendation. In praise of the activities of the Yobuyko Whale Association,
I strongly recommend this book. 1. Yobuko Kujira Gumi (ed.). A Tale of Yobuko and Whales. Yobuko Kujira Gumi. 61
pp. (In Japanese).
2019
Ohsumi, S. 2015. Kaikan 50 nen ni yosete. Kujira to ayunda 50 nen (On the 50th Anniversary of the Museum’s Opening.
Fifty Years of Working with Whales). Taiji-chouritsu Kujira no Hakubutsukankaikan 50 shuunen Kinenshashinshuu.
(In Japanese).
4. Others (357)
Geiken Tsuushin (WRI/ICR Quarterly Newsletter) (100)1956
Kimura, S. 1956. Kujira no kakouchou. Mezurashii hogei toukei (Whale Necrology Records—Precious Whaling Statistics).
Geiken Tsuushin 63: 1–7. (In Japanese).
1957
Kimura, S. 1957. 1956 nendo hokuyousan geirui no shigenchousa houkoku (Report on the 1956 Northern Ocean whale resource research). Geiken Tsuushin 65: 6–7. (In Japanese).
Kimura, S. 1957. Kujira no souseiji 1 (A Case of Whale Twins 1). Geiken Tsuushin 68: 1–4. (In Japanese).
Kimura, S. 1957. Kujira no souseiji 2 (A Case of Whale Twins 2). Geiken Tsuushin 69: 13–16. (In Japanese).
Kimura, S. 1957. Toraerareta hakugei no kouei (A Moby Dick Descendant was Captured). Geiken Tsuushin 70: 5–9. (InJapanese).
Kimura, S. (Translation) 1957. Bandouiruka no seishoku koudou 1 (Reproductive Behavior of the Bottlenose Dolphin 1).
Geiken Tsuushin 74: 1–8. (In Japanese).
Kimura, S. (Translation) 1957. Bandouiruka no seishoku koudou 2 (Reproductive Behavior of the Bottlenose Dolphin 2).
Geiken Tsuushin 75: 4–15. (In Japanese).
1958
Ohsumi, S. 1958. Kujira no shussan (Whale Parturition). Geiken Tsuushin 81: 8–14. (In Japanese).
Ohsumi, S. 1958. Kitataiheiyousan nagasukujira no nenrei to seichou (Age and Growth of North Paciﬁc Fin Whales). Geiken
Tsuushin 86: 1–16. (In Japanese).
1959
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 1 (Southern Whale. 1958/59 Tonanmaru Boarding Report 1). Geiken Tsuushin 92: 1–9. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 2 (Southern Whale. 1958/59 Tonanmaru Boarding Report 2). Geiken Tsuushin 93: 15–20. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 3 (Southern Whale. 1958/59 Tonanmaru Boarding Report 3). Geiken Tsuushin 94: 4–14. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 4 (Southern Whale. 1958/59 Tonanmaru Boarding Report 4). Geiken Tsuushin 95: 23–26. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 5 (Southern Whale. 1958/59 Tonanmaru Boarding Report 5). Geiken Tsuushin 96: 11–14. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 6 (Southern Whale. 1958/59 Tonanmaru Boarding Report 6). Geiken Tsuushin 97: 11–15. (In Japanese).

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Ohsumi, S. 1959. 1958/59 nendo nanpyouyou hogei ryouki ni okeru geirui shigenchousa no gaiyou (Outline of Whale Research in the 1958/59 Southern Ocean Whaling Season). Geiken Tsuushin 98: 8–12. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 7 (Southern Whale. 1958/59 Tonanmaru Boarding Report 7). Geiken Tsuushin 98: 16–20. (In Japanese).
Ohsumi, S. 1959. Minamikujira. 1958/59 nen Tounanmaru jousenki 8 (Southern Whale. 1958/59 Tonanmaru Boarding Report 8). Geiken Tsuushin 99: 19–24. (In Japanese).
Ohsumi, S. 1959. Nanpyouyousan geirui hokakudaichou wo seirishinagara (While organizing the Southern Ocean whale
Catch Ledger). Geiken Tsuushin 100: 21–22. (In Japanese).
1960
Ohsumi, S. 1960. Minamikujira. 1958/59 nen Tounanmaru jousenki 9 (Southern Whale. 1958/59 Tonanmaru Boarding Report 9). Geiken Tsuushin 101: 21–26. (In Japanese).
Ohsumi, S. 1960. Minamikujira. 1958/59 nen Tounanmaru jousenki 10 (Southern Whale. 1958/59 Tonanmaru Boarding Report 10). Geiken Tsuushin 102: 27–32. (In Japanese).
Ohsumi, S. 1960. Hyoushiki chousa ni yoru nagasukujira no nenrei to seichou no kentou (Examination of the Age and
Growth of Fin Whales using Tag Surveys). Geiken Tsuushin 105: 1–14. (In Japanese).
Ohsumi, S. 1960. Nagasukujira no hanshokuki (The Fin Whale Breeding Season). Geiken Tsuushin 111: 1–9. (In Japanese).
Ohsumi, S. 1960. Honnendo engan de saihosareta hyoushikikujira (Marked Whales recaptured from the Coast this Year).
Geiken Tsuushin 112: 11–12. (In Japanese).
1961
Ohsumi, S. 1961. 1959/60 Nendo nanpyouyou hogei ryouki ni saihosareta hyoushikikujira ni tsuite (Marked Whales recaptured during the 1959/60 Southern Ocean Whaling Season). Geiken Tsuushin 114: 31–32. (In Japanese).
Ohsumi, S. 1961. Kujira hyoushiki nyuusu (Whale Tagging News). Geiken Tsuushin 116: 12. (In Japanese).
Ohsumi, S. 1961. Nagasukujira no seichou ni tomonau gaikei no henka (Changes with Growth of the Fin Whale externalMorphology). Geiken Tsuushin 117: 1–13. (In Japanese).
Ohsumi, S. 1961. Hokuyou san semikujira no chousa ni tsuite (On the North Sea Right Whale Research). Geiken Tsuushin
122: 1–27. (In Japanese).
Ohsumi, S. 1961. 1961 Nendo kitataiheiyou ni okeru saiho hyoushikikujira ichiran (List of Marked Whales Recaptured in the
North Paciﬁc in 1961). Geiken Tsuushin 124: 18. (In Japanese).
1962
Ohsumi, S. 1962. Iruka no kaiwa (Dolphin Conversation). Geiken Tsuushin 126: 19–26. (In Japanese).
Ohsumi, S. 1962. 1961 Nendo hokuyou hogei ni okeru geirui shigen chousa no gaiyou (Outline of Whale Resources Research in the 1961 Northern Sea Whaling). Geiken Tsuushin 127: 16–20. (In Japanese).
Ohsumi, S. 1962. Kujira no kougan juuryou banzuke (Whale Testis Weight Ranking List). Geiken Tsuushin 134: 18. (InJapanese).
1963
Ohsumi, S. 1963. Makkoukujira no ha no hanashi (On the Teeth of Sperm Whales). Geiken Tsuushin 141: 1–16. (InJapanese).
Ohsumi, S. 1963. Geirui no taichoutaijuu kankeishiki (Length-Weight relationship Formula for Cetaceans). Geiken Tsuushin
141: 16. (In Japanese).
Ohsumi, S. 1963. Geikendayori (WRI News). Geiken Tsuushin 142: 22. (In Japanese).
Ohsumi, S. 1963. Dai 29 kai geiken danwakai kirouku (Record of the 29th WRI Colloquium). Geiken Tsuushin 145: 5. (InJapanese).
1964
Ohsumi, S. 1964. Geirui ni okeru hairan no fusoushousei (Asymmetry of Ovulation in Cetaceans). Geiken Tsuushin 153: 1–6.
(In Japanese).
Ohsumi, S. 1964. Makkoukujira no saiseisan ni kanrenshite (In Relation to the Reproduction of Sperm whales). Geiken
Tsuushin 158: 1–8. (In Japanese).
1965
Ohsumi, S. 1965. Hyoushiki ni yoru ougatakujira no idousokudo no suitei (Estimation of Migration Speed of Large Whales
by Marking). Geiken Tsuushin 163: 1–10. (In Japanese).
Ohsumi, S. (Translation) 1965. Gaiyou ni hanasigaisareta iruka (Trained Porpoise released in the Open Sea). Geiken Tsuushin 168: 63–65. (In Japanese).
Ohsumi, S. 1965. Makkoukujiragun tokubetsu hokaku chousa (Sperm Whale Pod Special Research Take). Geiken Tsuushin
172: 1–14. (In Japanese).
1966
Nemoto, T., Ohsumi, S., Ichihara, T. and Nasu, K. 1966. Tansei-maru ni yoru Sanriku Hokkaidou oki no geirui seitai kansatsu oyobi hyoushiki chousa (Whale Observation and Whale Marking with R/V Tansei-Maru in the Waters oﬀ Sanriku
and Hokkaido). Geiken Tsuushin 173: 1–10. (In Japanese).
Ohsumi, S. (Abridged translation) 1966. Makkoukujira no koudou (Behavior of the sperm whale Physeter catodon L. by
Caldwell, D.K., Caldwell, M.C. and Rice, D.W. (1966)). Geiken Tsuushin 182: 1–10. (In Japanese).
1967
Ohsumi, S. 1967. Kitataiheiyou ni okeru kujira shigen no doukou (Trends of Whale Stocks in the North Paciﬁc). Geiken

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Tsuushin 188: 1–9. (In Japanese).
1968
Ohsumi, S. (Translation) 1968. Makkoukujira no ousu no mure no kouzou (Tarasevich, M. N. 1968. On the structure of ceteacean groupings 1. Structure of the grouping of Physeter catodon males. Zool. Zh. 46: 124–131). Geiken Tsuushin
198: 1–7. (In Japanese).
Ohsumi, S. (Translation) 1968. Nanpyouyou geirui shigen no kanri (Gulland, J.A. 1968. The management of Antaractic
whaling resources. J. Cons. Perm. Int. Explor. Mer 31 (3): 330–341). Geiken Tsuushin 206: 1–9. (In Japanese).
1969
Ohsumi, S. 1969. Nanpyouyousan minku no hakkan ritsu (BWU Conversion Rate for the Southern Ocean Minke Whale).
Geiken Tsuushin 211: 1–4. (In Japanese).
Doi, N. and Ohsumi, S. 1969. Nanpyouyousan nagasukujira no shigen hyouka no souten (The Southern Ocean Fin Whale
Stock Assessment Points at Issue). Geiken Tsuushin 216: 1–11. (In Japanese).
1970
Ohsumi, S. 1970. Sujiiruka no seichou ni tomonau gaibu keitai no henka (Changes in External Morphology during the
Growth of the Striped Dolphin). Geiken Tsuushin 228: 5. (In Japanese).
1971
Ohsumi, S. 1971. Beikoku ni okeru kujira shigen kenkyuu kikou no kaihen (Reformation of the Whale Research Organizations in the United States). Geiken Tsuushin 233: 9–10. (In Japanese).
Ohsumi, S. 1971. Nihon ni okeru kujira seihin no jukyuu (Supply and Demand of Whale Products in Japan). Geiken Tsuushin
240: 65–73. (In Japanese).
Ohsumi, S. 1971. Oogata geirui no shiiku wo seikousaseyou (Raising of Large Whales—Let’s make it a Success). Geiken
Tsuushin 242: 85–91. (In Japanese).
1972
Ohsumi, S. 1972. Kokusaiteki hogeigyou no kanri (International Management of the Whaling Industry). Geiken Tsuushin
259: 121–126. (In Japanese).
1974
Ohsumi, S. and Masaki, Y. 1974. Kitataiheiyou ni okeru Nihon no geirui hyoushiki chousa 1963–1972 nen (Japanese Cetacean Marking Survey in the North Paciﬁc, 1963–1972). Geiken Tsuushin 271: 17–24. (In Japanese).
Ohsumi, S. 1974. Makkintosshu hakase no shi wo itamu (Mourning the Death of Dr. Neil Alison Mackintosh). Geiken
Tsuushin 273: 39–41. (In Japanese).
1979
Ohsumi, S. 1979. Zatoukujira no setsujihou ni tsuite no shinsetsu to okiami kihoumou gyohou no kanousei (New Theory
on the Feeding Methods of Humpback Whales and the possibility of Krill Bubble-net Fishing). Geiken Tsuushin 323:
13–14. (In Japanese).
Ohsumi, S. 1979. Hawai ni okeru zatoukujira no hogo (Humpback Whale Conservation in Hawaii). Geiken Tsuushin 327:
48–52. (In Japanese).
1980
Ohsumi, S. 1980. Geirui no gakumei no imi (Meaning of the Scientiﬁc Names of Cetaceans). Geiken Tsuushin 336: 41–44.
(In Japanese).
1981
Ohsumi, S. 1981. Habbusu sensei no koto (About Professor Carl L. Hubbs). Geiken Tsuushin 337: 7–8. (In Japanese).
Ohsumi, S. 1981. Geirui no shizen hyoushiki (Natural Marks in Cetaceans). Geiken Tsuushin 341: 37–43. (In Japanese).
1982
Ohsumi, S. 1982. Kokusai hogei torishimari jouyaku no kameikoku to sono hensen (Signatories to the International Convention for the Regulation of Whaling and their Transition). Geiken Tsuushin 346: 27–38. (In Japanese).
1983
Ohsumi, S. 1983. “Handouiruka” ka “Bandouiruka” ka (On the Bottlenose Dolphin Japanese Name). Geiken Tsuushin 348:
5–6. (In Japanese).
1986
Ohsumi, S. 1986. “Toukaidouchuu Hizakurige” to kujira shokubunka (“Travels on Foot on the Tokaido” and Whale Eating
Culture). Geiken Tsuushin 365: 56–57. (In Japanese).
1987
Ohsumi, S. 1987. Nihon kaigun to kujira (The Japanese Navy and Whales). Geiken Tsuushin 370: 97–101. (In Japanese).
1994
Ohsumi, S. 1994. Nankyokukai de akaboukujiraka geirui wo hokakusuru hitsuyousei (On the Need to take Beaked Whales in
the Antarctic Ocean). Geiken Tsuushin 383: 1–7. (In Japanese).
Ookinakujira (pseudonym, Ohsumi, S.) 1994. Kindai no yona wa jitsuzaishita ka? (Did modern Jonah exist?). Geiken
Tsuushin 383: 7–11. (In Japanese).
Ohsumi, S. 1994. Meion de kujira no koudou wo saguru (Exploring Whale Behavior using their Vocalizations). Geiken
Tsuushin 384: 9–14. (In Japanese).
1995
Ohsumi, S. 1995. Noruwee no kogata hogei (The Norwegian Small Whale Fishery). Geiken Tsuushin 385: 8–15. (InCetacean Popul. Stud. (CPOPS)
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Japanese).
Ohsumi, S. 1995. 47 Kai IWC nenji kaigi kagaku shouiinkai no gaiyou to kameikoku no geirui shigen kenkyu no doukou(Overview of the Scientiﬁc Committee on the 47th IWC Annual Meeting and trends in whale research by Member
States). Geiken Tsuushin 386: 6–11. (In Japanese).
Ohsumi, S. 1995. Kujira ni totte himan towa nani ka (What is Obesity for Whales?). Geiken Tsuushin 387: 7–13. (InJapanese).
1996
Ohsumi, S. 1996. Dai 48 Kai IWC/SC kaigi ni sankashite kanjita koto (Impressions from the 48th IWC/SC Meeting). Geiken
Tsuushin 391: 16–20. (In Japanese).
Ohsumi, S. 1996. Futari no IWC/SC iin no shi wo itamu (Mourning the death of two IWC/SC Members. Alfred Antonovich
Berzin (Russia) and Douglas George Clapham (USA)). Geiken Tsuushin 392: 16–20. (In Japanese).
1997
Ohsumi, S. 1997. Kujira no meishi to nengajou (Whale business cards and New Year’s cards). Geiken Tsuushin 395: 20–23.
(In Japanese).
Ohsumi, S. 1997. Nihon geirui kenkyusho no souritsu 10 shuunen wo mukaete (Celebrating the 10th Anniversary of theICR). Geiken Tsuushin 396: 1–5. (In Japanese).
1998
Ohsumi, S. 1998. “Geiken Tsuushin” 50 nen 400 go no shuppan katsudou wo furikaette (Looking back on the 50 year and
400 issues publishing activities of the Geiken Tsuushin”). Geiken Tsuushin 400: 1–5. (In Japanese).
1999
Tamura, T. and Ohsumi, S. 1999. Sekai ni okeru geirui no shokumotsu nenkan shouhiryou (Annual Food Consumption of
Cetaceans in the World). Geiken Tsuushin 402: 10–22. (In Japanese).
2000
Ohsumi, S. 2000. 21 seiki no kujira no yume (Whale Dreams for the 21st Century). Geiken Tsuushin 408: 1–7. (In Japanese).
2002
Ohsumi, S. 2002. Chukouto no hogei (Chukotka Whaling). Geiken Tsuushin 416: 1–8. (In Japanese).
2003
Ookinakujira (pseudonym, Ohsumi, S.) 2003. Kujira kenkyuu no “Tokiwa-sou” jidai (The “Tokiwa-so” era of Whale Research). Geiken Tsuushin 420: 6–16. (In Japanese).
2004
Ohsumi, S. 2004. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 421: 14. (In Japanese).
Ohsumi, S. 2004. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 422: 20. (In Japanese).
Ohsumi, S. 2004. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 423: 18. (In Japanese).
Ohsumi, S. 2004. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 424: 19–20. (In Japanese).
2005
Ohsumi, S. 2005. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 425: 20. (In Japanese).
Ohsumi, S. 2005. Nihon geirui kenkyusho no kakubu shoukai (V). Fuzoku shisetstu tou (Introduction to the ICR Departments V. Ancillary facilities, etc.). Geiken Tsuushin 426: 13–18. (In Japanese).
Ohsumi, S. 2005. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 426: 20. (In Japanese).
Ohsumi, S. 2005. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 427: 24. (In Japanese).
2005
Ohsumi, S. 2006. Ookina sakana (Henshuu kouki) (Big Fish (Editorial Note). Geiken Tsuushin 432: 18. (In Japanese).
2012
Ohsumi, S. 2012. Taiji-chou no “Moriura wan kujira no umi” kousou (Moriura Bay “Whale Sea” Plan in Taiji Town). Geiken
Tsuushin 455: 11–13. (In Japanese).
2013
Ohsumi, S. 2013. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (I). Senzen no kokusai hogei kisei
to kagaku no kanyou (The Transition of the International Whaling Commission / Scientiﬁc Committee and its relationship with Japan (I). Pre-war International Whaling Regulations and Scientiﬁc Involvement). Geiken Tsuushin 458: 1–7.
(In Japanese).
Ohsumi, S. 2013. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (II). Senzen no kokusai hogei
kisei to kagaku no kanyou (The Transition of the International Whaling Commission / Scientiﬁc Committee and its
relationship with Japan (II). Pre-war International Whaling Regulations and Scientiﬁc Involvement). Geiken Tsuushin
459: 1–9. (In Japanese).
2014
Ohsumi, S. 2014. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (III). San nin iinkai (The Transition of the International Whaling Commission / Scientiﬁc Committee and its relationship with Japan (III). The
Three-member Committee). Geiken Tsuushin 463: 1–7. (In Japanese).
2015
Ohsumi, S. 2015. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (IV). Shin kanri houshiki (NMP)
siritsu zenya (The Transition of the International Whaling Commission / Scientiﬁc Committee and its relationship withJapan (IV). The eve of the New Management Procedure (NMP) Approval). Geiken Tsuushin 465: 9–19. (In Japanese).

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BIBLIOGRAPHY OF THE PUBLISHED WORKS OF SEIJI OHSUMI
Ohsumi, S. 2015. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (V). Kitataiheiyou geirui shigen
no kanri mondai (Sono 1) (The Transition of the International Whaling Commission / Scientiﬁc Committee and its relationship with Japan (V). Management Issues for North Paciﬁc Cetacean Resources (Part 1). Geiken Tsuushin 467: 1–9.
(In Japanese).
2016
Ohsumi, S. 2016. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (V). Kitataiheiyou geirui shigen
no kanri mondai (Sono 2) (The Transition of the International Whaling Commission / Scientiﬁc Committee and its
relationship with Japan (V). Management Issues for North Paciﬁc Cetacean Resources (Part 2). Geiken Tsuushin 468:
1–15. (In Japanese).
Ohsumi, S. 2016. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (VI). IDCR/SOWER minami
hankyuusan minkukujira shigen hyouka koukai (Sono 1) (The Transition of the International Whaling Commission /Scientiﬁc Committee and its relationship with Japan (VI). IDCR/SOWER Southern Hemisphere Minke Whale Stock
Assessment Voyage (Part 1). Geiken Tsuushin 469: 12–21. (In Japanese).
Ohsumi, S. 2016. Tanaka Shouichi hakase no shi wo itami, gyouseki wo tataeru (Mourning the Death of Dr. Shoichi Tanaka
and Celebrating his Achievements). Geiken Tsuushin 470: 6–9. (In Japanese).
Ohsumi, S. 2016. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (VI). IDCR/SOWER minami
hankyuusan minkukujira shigen hyouka koukai (Sono 2) (The Transition of the International Whaling Commission /Scientiﬁc Committee and its relationship with Japan (VI). IDCR/SOWER Southern Hemisphere Minke Whale Stock
Assessment Voyage (Part 2). Geiken Tsuushin 471: 1–15. (In Japanese).
Ohsumi, S. 2016. Kokusai hogeiiinkai / kagakushouiinkai no hensen to Nihon tono kankei (VII). IWC/SC e no Nihon no
taiou soushiki no hensen (The Transition of the International Whaling Commission / Scientiﬁc Committee and its relationship with Japan (VII). Changes in the Japan’s Response to IWC/SC). Geiken Tsuushin 472: 1–5. (In Japanese).
2017
Ohsumi, S. 2017. Ferou shotou ni okeru gondoukujira no oikomi ryou (The Faroe Islands Pilot Whale Drive Fishery). Geiken
Tsuushin 476: 7–19. (In Japanese).
Miscellaneous (257)1957
Kimura, S. 1957. Makkouyuu (Sperm Whale Oil). Yuushi 10 (7): 32–33. (In Japanese).
1959
Ohsumi, S. 1959. Bikachouzoku (Uxorious Gang). Shisuikai Kaihou Showa 34 Nendo: 28–30. (In Japanese).
1965
Ohsumi, S. 1965. Hogeihou no hensen 1 (Whaling Method Transition 1). Shuryoukai 9 (3): 124–127. (In Japanese).
Ohsumi, S. 1965. Hogeihou no hensen 2 (Whaling Method Transition 2). Shuryoukai 9 (4): 100–104. (In Japanese).
Ohsumi, S. 1965. Hogeihou no hensen 3 (Whaling Method Transition 3). Shuryoukai 9 (5): 129–133. (In Japanese).
Ohsumi, S. 1965. Kaiyou no romansu (Romance of the Oceans). Shuryoukai 9 (8): 124–128. (In Japanese)
Ohsumi, S. 1965. Geiniku. Ganbari no kiku aiken no shokuji (Whale Meat—An Enduring Pet Dog’s Diet). Shuryoukai 9(10): 83. (In Japanese).
1966
Ohsumi, S. 1966. Shohyou. “Kujira” (Whales. Book Review). Nourin Suisan Tousho Shiryou Geppou 17 (1): 22–23. (InJapanese).
1967
Ohsumi, S. 1967. Sousetsu. Geirui no nenrei satei (Synopsis. Age Assessment of Cetaceans). Nissuishi 33 (8): 788–798. (InJapanese).
1970
Ohsumi, S. 1970. Kenkyuushitsu shoukai. Sokouo kaiju shigenbu geirui shigen kenkyuushitsu (Laboratory Introduction.
Laboratory of Cetacean Resources, Department of Demersal Fish and Marine Mammal Resources). Enyou 6: 4–5. (InJapanese).
1971
Ohsumi, S. 1971. Shigen toshite no geirui to sono kanri (Cetaceans as a Resource and their Management). Doubutsu to Shizen 1 (6). (In Japanese).
1972
Nishiwaki, M. and Ohsumi, S. 1972. Geirui no kousoshiki ni yoru nenrei satei (Age Assessment of Cetaceans by Hard Tissue). Kousoshiki Keisei Kouzou Kenkyuu Guruupu Kaihou 22: 12–17. (In Japanese).
Ohsumi, S. 1972. Minkukujira shigen no kaihatsu (Exploitation of Minke Whale Resources). Suisan Hyouron 39: 72–77. (InJapanese).
Ohsumi, S. 1972. Kaijuurui no kotaigun doutai to shigen kanri (Population Dynamics and Resource Management in Marine
Mammals). Iden 26 (11): 43–49. (In Japanese).
Ohsumi, S. 1972. Koiwashikujira (The minke whale). Animaru Raifu 53: 1484. (In Japanese).
Ohsumi, S. 1972. Kokukujira (The gray whale). Animaru Raifu 55: 1533–1534. (In Japanese).
Ohsumi, S. 1972. Zatoukujira (The humpback whale). Animaru Raifu 66: 1732–1733. (In Japanese).

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1973
Ohsumi, S. 1973. Shizen hozon to shigen riyou (Nature conservation and resource utilization). Enyou 15: 2–6. (In Japanese).
Ohsumi, S. 1973. Hokkyokukujira (The bowhead whale). Animaru Raifu 122: 3405. (In Japanese).
Ohsumi, S. 1973. Makkoukujira (The sperm whale). Animaru Raifu 125: 3485–3487. (In Japanese).
1974
Ohsumi, S. 1974. Geirui shigen no kaiseki. Sono rekishiteki kousatsu (Analysis of cetacean stocks: Historical considerations). Kaiyoukagaku 6 (8):56–60. (In Japanese).
Ohsumi, S. 1974. Kujira shigen wo meguru mittsu no tokubetsu kokusai kaigi (Three Special International Conferences on
whale resources). Enyou 18: 5–7. (In Japanese).
Ohsumi, S. 1974. Dai 26 kai IWC nenji kaigi ni okeru kagaku shouiinkai no rongi (Discussions of the Scientiﬁc Subcommittee at the 26th IWC Annual Meeting). Enyou 19: 4–6. (In Japanese).
Ohsumi, S. 1974. Kujira wa hontou ni horobiru ka (Will the whales really die out?). Umi no Sekai 21 (1): 124–131. (InJapanese).
Ohsumi, S. 1974. Kujira wa koudaina umi no bokujou ni hanatareta ushi de aru (Whales are cattle set loose on a vast ocean
ranch). Anima 13: 50–55. (In Japanese).
Ohsumi, S. 1974. Shohyou. Omura Hideo cho: Kujira no seitai. (Book Review. Hideo Omura: The Ecology of Whales). Shizen 7: 108–109. (In Japanese).
1975
Ohsumi, S. 1975. Kujira no shigen wo handansuru (Diagnosing whale stocks). Ocean Age 1975 (10): 28–31. (In Japanese).
1976
Ohsumi, S. 1976. Geirui wa zetsumetsu ni hinshiteiruka? (Are cetaceans on the verge of extinction?). Iden 30 (1): 79–83. (InJapanese).
1978
Ohsumi, S. 1978. Hogeigyou to kujira shigen (The whaling industry and whale resources). Toukei 29 (2): 30–32. (InJapanese).
Ohsumi, S. 1978. Shigen riyou wa kaifukuryoku no han’i nai de (Resource utilization within the limits of resilience). Kagaku
Asahi 1978 (12): 52–56. (In Japanese).
1979
Ohsumi, S. 1979. Kujira bungakukou (Essay on whale literature). Za Amejisuto 2: 10–11. (In Japanese).
Ohsumi, S. 1979. Kujira shigen to hogei moratoriamu (Whale stocks and the moratorium on whaling). Suisan Kagaku 24 (2):30–38. (In Japanese).
1980
Ohsumi, S. 1980. Nankyoku chiiki no honyuurui (Mammals of the Antarctic Region). Doubutsu to Shizen 10 (14): 6–11. (InJapanese).
Ohsumi, S. 1980. Kujira wa shigen toshite no tenbou ga aru ka (Do whales have prospects as a resource?). Anima 87: 87–89.
(In Japanese).
1981
Ohsumi, S. 1981. Makkoukujira no sensui nouryoku to setsuji (Diving capacity and feeding of sperm whales). Kaiyou to
Seibutsu 15 (3): 240–241. (In Japanese).
Ohsumi, S. 1981. Kurosuwaado pazuru to hameji asobi (Crossword puzzles and ﬁtted character play). Za Amejisuto. 9:
12–13. (In Japanese).
Ohsumi, S. 1981. Waga kin’en ki (My non-smoking diary). Shisuikai Dousoudayori Shouwa 56 Nendo: 65–66. (In Japanese).
Ohsumi, S. 1981. Kaijuurui to gyogyou (Marine Mammals and Fisheries). Suisan Shiryou Shikihou 7 (3): 3–13. (InJapanese).
1982
Ohsumi, S. 1982. Sekai no kujira shigen. Rifujinna moratoriamu wo abaku (Global whale resources—Exposing the unreasonable moratorium). Suisan Sekai 31 (6): 82–86. (In Japanese).
Ohsumi, S. 1982. Kujira to Nihonjin (Whales and the Japanese). Shuukan Asahi Hyakka. Sekai no Tabemono 103: 11–84. (InJapanese).
1983
Ohsumi, S. 1983. Kaijuu wo taberu minzoku (Marine-mammal eating peoples). Shuukan Asahi Hyakka. Sekai no Tabemono
124: 13–112. (In Japanese).
Ohsumi, S. 1983. Jishin hakubutsukan kouzou (Earthquake Museum Concept). Numagoe 31: 3. (In Japanese).
Ohsumi, S. 1983. Hontou ni kujira wo tottewa ikenai ka (Shouldn’t we really catch whales?). Jiji Kaisetsu 9148: 5–6. (InJapanese).
1984
Ohsumi, S. 1984. Nishiwaki Masaharu Kaichou no shi wo itamu (Mourning the death of Chairman Masaharu Nishiwaki).
Honyuudoubutsugaku Zasshi 10 (2): 111–114. (In Japanese).
Ohsumi, S. 1984. Kouhai no nai dousoukai (An alumni association with no juniors). Rikka Kai Kaihou 32: 39–42. (InJapanese).
Ohsumi, S. 1984. Dai 36 kai kokusai hogei iinkai kagaku shouiinkai de no tatakai wo oete (After the conﬂict at the International Whaling Commission 36th Scientiﬁc Subcommittee Meeting). Enyou 53: 5. (In Japanese).

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Ohsumi, S. 1984. Yama ni agaru kurushimi wa ko wo umu kurushimi ni niru (The pain of climbing a mountain is like thepain of giving birth to a child). Yamanami 66: 4. (In Japanese).
1985
Ohsumi, S. 1985. Umi ni hanashigaisareata ushi (Cattle free-ranging in the sea). UP 151: 5–8. (In Japanese).
Ohsumi, S. 1985. Honyakusho wo shuppanshite kanjita koto (What I felt publishing a translation of a book). Kaiyou to
Seibutsu 7 (2): 115. (In Japanese).
Ohsumi, S. 1985. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 56: 14. (InJapanese).
Ohsumi, S. 1985. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 58: 16. (InJapanese).
Ohsumi, S. 1985. Za Kujira (Hara cho dai 2 han) shohyou (Review of “Whales” (Hara, T., 2nd ed.). Nourin Suisan Tousho
Shiryou Geppou 36 (6): 13. (In Japanese).
1986
Ohsumi, S. 1986. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 59: 24. (InJapanese).
Ohsumi, S. 1986. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 60: 16. (InJapanese).
Ohsumi, S. 1986. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 61: 15–16. (InJapanese).
Ohsumi, S. 1986. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 62: 16. (InJapanese).
1987
Ohsumi, S. 1987. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 63: 16. (InJapanese).
Ohsumi, S. 1987. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 65: 16. (InJapanese).
Ohsumi, S. 1987. Ooku no hitobito no goshien wo ete (With the support of many people). Enyou. 20 Shuunen Tokushuu Gou:
15–16. (In Japanese).
Ohsumi, S. and Honma, M. 1987. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou.
20 Shuunen Tokushuu Gou: 26–27. (In Japanese).
Ohsumi, S. 1987. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 66: 16. (InJapanese).
Ohsumi, S. 1987. Kujira no kachikuka no kanousei wo saguru. Kujira shokubunka wo keishou suru tame ni (Exploring thepossibility of domesticating whales—To preserve the whale eating culture). Saishuu to Shiiku 49 (12): 514–518. (InJapanese).
Ohsumi, S. 1987. Geirui no suichuu seikatsu e no teiou to shinka (Adaptation and evolution of cetaceans to underwater life).
WAVE 13: 180–188. (In Japanese).
1988
Ohsumi, S. 1988. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 67: 16. (InJapanese).
Ohsumi, S. 1988. Soredemo chikyuu wa ugoiteiru. Henshuu kouki (Eppur si muove. Editorial Note). Enyou 68: 16. (InJapanese).
Ohsumi, S. 1988. Ningen to kujira no atarashii kankei wo. Enyou gyogyou wo sasaeru chikara (New relationship between
humans and whales—Power to support far-sea ﬁsheries). Suisan Sekai 11 Gatsu Gou: 23. (In Japanese).
Ohsumi, S., Komatsu R. and Munetake, A. 1988. Zadankai. Kujira to ningen: Atarashii kyouzon wo megutte (Round-table
Talk. Whales and Humans: A new coexistence). Yuurin 252: 1–3. (In Japanese).
Ohsumi, S. 1988. Kujira wa shigen desu ka (Are whales a resource?). Oikos 4: 28–30. (In Japanese).
Ohsumi, S. 1988. Fuyou jouhou sentaa to kujira kenkyuu. Fuyou jouhou sentaa sougou kenkyuusho (Fuyo Information Center and whale research. Fuyo Information Center Research Institute). What’s FRI: 65–67. (In Japanese).
1989
Ohsumi, S. 1989. Utakata no kujira kenkyuu no ba (An ephemeral place for whale research). Tsukishima—Toukaiku Suisan
Kenkyuusho Kaisetshu 40 Shuunen Tokushuu Gou. 48–51. (In Japanese).
Ohsumi, S. 1989. Showa, Showa, Showa no kodomo yo, bokutachi wa (Yo! Showa, Showa, Showa lads, that’s us!). Numagoe 104: 3. (In Japanese).
Ohsumi, S. 1989. Izu no iruka ryou (The Izu dolphin ﬁshery). Numagoe 105: 1. (In Japanese).
Ohsumi, S. 1989. “Kujira wa doko made chiisakunaru ka” nit suite (On “How small can a whale get?”). Kagaku 58 (4): 270.
(In Japanese).
Ohsumi, S. 1989. Kujira shokubunka (Whale food culture). Aoi. 99: 4–8. (In Japanese).
Ohsumi, S. 1989. Shohyou. Kujira no Bunkajinruigaku (Book Review. Cultural Anthropology of Whales). Bunka Kaigi 245:
34–36. (In Japanese).
1990
Ohsumi, S. 1990. Kaiyou houboku no “kachiku” kujira (Whales, “livestock” that graze in the ocean). Suisan Sekai 39 (6): 41.

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(In Japanese).
Ohsumi, S. 1990. Umi to kujira to ningen to (The sea, the whales, and man). Sumai to Machi 6 (6): 64–67. (In Japanese).
Ohsumi, S. 1990. Hiroi senmon bunya ni wataru kaiyouseibutsu kenkyuusha no kakuhou (Securement of marine biology researchers across a wide range of disciplines). Suisan no Kenkyuu 9 (5): 13. (In Japanese).
Ohsumi, S. 1990. Kujira no seitaigaku. Tokushuu: Kujira. Part 2 (Whale Ecology. Special Issue on Whales. Part 2). FRONT 3(2): 4–5. (In Japanese).
Ohsumi, S. 1990. Dai 42 kai kokusai hogei iinkai nenji kaigi ni okeru houkatsuteki shigen hyouka (Comprehensive stock assessment at the 42nd Annual Meeting of the International Whaling Commission). Enyou 78: 1–4. (In Japanese).
1991
Ohsumi, S. 1991. Kujira wa umi ni hanashigaisareta ushi de aru (Whales are like free-ranging cattle in the sea). Nishinihon
Kujira Kenkyuukaihou 5: 2–5. (In Japanese).
Ohsumi, S. 1991. Chousa hogei. Nihon ga nankyokukai de jisshishiteiru geirui no hokaku chousa (Research whaling—
Japan’s whale research program in the Antarctic Ocean). Suisan Shinkou 288: 27. (In Japanese).
1992
Ohsumi, S. 1992. Seibutsu shigen toshite no kujira (Whales as living resources). Iden 46 (5): 4–5. (In Japanese).
Ohsumi, S. 1992. Niigata no kujira shokubunka (Niigata’s whale food culture). Sanmago 11: 9–10. (In Japanese).
Ohsumi, S. 1992. Mizu (Water). Numagoe 144: 9. (In Japanese).
Ohsumi, S. 1992. Katamichi 6000 kiro no nagai tabi. Kokukujira (Gray whales. A long journey of 6,000 kilometers oneway). Doubutsutachi no Chikyuu 52 (9): 104–107. (In Japanese).
1993
Ohsumi, S. 1993. Kokusai hogei iinkai no genjou to kongo (Jou) (Current status and future of the International Whaling
Commission (1)). Suisan no Kenkyuu 12 (5): 41–45. (In Japanese).
Ohsumi, S. 1993. Kokusai hogei iinkai no genjou to kongo (Ge) (Current status and future of the International Whaling Commission (2)). Suisan no Kenkyuu 12 (6): 33–37. (In Japanese).
Ohsumi, S. 1993. Kujira no ai no motomekata (The whale’s way of seeking love). Imaago 4 (13): 134–139. (In Japanese).
Ohsumi, S. 1993. Kujira to ningen no kakawariai—Kako, genzai, mirai (Whale and human interaction: Past, present and future). Imaago 4 (8): 68–79. (In Japanese).
Ohsumi, S. 1993. Nihon ni mo kakko taru bunka ga aru no da. Ekisentorikkuna hogei kinshi no oshitsuke ni gimon ari (Japan
has a strong culture too. Questionning the imposition of an eccentric ban on whaling). Ru Kuuru. 8: 23. (In Japanese).
Ohsumi, S. 1993. Soukan!! Nihon rettou kujira wotchingu (Spectacular! Whale watching in the Japanese Archipelago). Daiyamondo Fiirudo 3: 1–2. (In Japanese).
1994
Ohsumi, S. 1994. Ichi nen no kei (The whole year’s plans). Numagoe 163: 4. (In Japanese).
Ohsumi, S. 1994. Hoeeru wotchingu ni tsuite kangaeru (Considerations about whale watching). Hyougo Kyouiku 46 (9):48–51. (In Japanese).
Ohsumi, S. 1994. Kujira no chinou to shakai seikatsu (The intelligence and social life of whales). Rabo no Sekai 180: 2–4.
(In Japanese).
Ohsumi, S. 1994. Kujira no mimiaka (Whale’s earwax). Chichi 6: 77–78. (In Japanese).
Ohsumi, S. 1994. Kyogei wotchingu (Huge whale watching). Beans 9: 1–2. (In Japanese).
Ohsumi, S. 1994. Nankyokukai de Nihon ga jisshishiteiru geirui no hokaku chousa (Japan’s whale research in the Antarctic
Ocean). Kyokuchi 58: 11–13. (In Japanese).
Ohsumi, S. 1994. Nankyokukai no shironagasukujira shigen wa naze kaifuku shinai no ka (Why the blue whale stock in the
Antarctic Ocean is not recovering). Isana 10: 5–7. (In Japanese).
Ohsumi, S. (translation supervisor) 1994. Kujiratachi no jidai. Ningen to kujira no atarashii kankei (The Age of Whales—A
New Relationship between Man and Whales). GEO 1 (3): 16–41. (In Japanese).
Ohsumi, S. 1994. Nihon ni okeru kujira bunka (Whale culture in Japan). GEO 1 (3): 42–43. (In Japanese).
Ohsumi, S. 1994. Umi no honyuurui (Sea mammals). Kyouzai Nyuusu 1665: 1–4. (In Japanese).
Ohsumi, S. and Hori, Y. 1994. Taidan. Kujira to jinrui no kyousei (Conversation: Whales and human coexistence). Kikan Dajian 13: 20–22. (In Japanese).
Ohsumi, S. and Nakamura, T. 1994. Taidan. Ochaa no jikan. Doubutsu 6 Kujira (Tea time. Animals 6. Whales). Kurowassan
94–97. (In Japanese).
Ohsumi, S. 1994. ʻSanctuaryʼ is not a solution. The Japan Times Weekly 34（44）: 6–7.
Ohsumi, S. 1994. Kujira no fuchakuseibutsu (Whale epibionts). Dai Ni Umiushi Tsuushin 5: 4–7. (In Japanese).
Ohsumi, S. (supervisor) 1994. Tokushuu kujira: Umi ni kaetta honyuurui (Feature—Whales: Mammals that returned to thesea). Shouyon Charenji Rinji Zoukan Gou: 2–13. (In Japanese).
1995
Ohsumi, S. 1995. Dokken dokugo 21 seiki wo misoete gyogyou sonzoku wo (Soliloquies. Looking ahead to the 21st century
and the survival of the ﬁshing industry). Suisan Shuuhou 1379: 3. (In Japanese).
Ohsumi, S. 1995. Kokukujira wa ichi man 5 sen kiro no nagai tabi wo kurikaesu (Gray whales are making 15,000 km long
journeys). Kyouzai Nyuusu (Furoku). 1713: 1–4. (In Japanese).
Ohsumi, S. 1995. Kokukujira (Gray whale). Save our Nature 15. Toba Super Aquarium 14: 14–15. (In Japanese).

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1996
Ohsumi, S. 1996. Geirui shigen no gouritekiriyou wo mezashite (Towards the rational utilization of whale resources). Isana
14: 1. (In Japanese).
Ohsumi, S. 1996. Geirui hokaku chousa no igi (Signiﬁcance of the whale research programs). Suisan Jaanarisuto no Kai
Kaihou 44: 37 pp. (In Japanese).
Ohsumi, S. 1996. Intabyuu yuugaku sanpou. Kujira wa umi no sachi wo yobiyoseru Ebisu sama (Interview—Studying Promenade. Whales are Ebisu, who bring in the riches of the sea). Dental Diamond 21 (275): 170–175. (In Japanese).
Ohsumi, S. 1996. Kantou zuisou. Kindai hogei 100 shuunen ni atatte (Introduction Essay. On the 100th anniversary of modern whaling). Suisankai 7. (In Japanese).
Ohsumi, S. 1996. Kihon shisei wo tsuranuki kizen to taiou (Act up resolutely to the basic stance). Suisan Sekai 45: 36–39.
(In Japanese).
Ohsumi, S. 1996. Kuwashii hito ni kiita besuto 3 kujira no hon (The best 3 books on whales, according to people who know
about them). SINRA 36 (12): 164. (In Japanese).
1997
Ohsumi, S. 1997. Atarashii hogei wo souzousuru tame ni chousakenkyuu wo suishin (Promoting research to create a newkind of whaling). Osakana Tsuushin Gyo! 2: 13. (In Japanese).
Ohsumi, S. 1997. Juunenme wo mukaeta “geirui hokaku chousa”. Ningen ga genshousaseta kujira no seitaikei wa ningen no
chikara de shuufuku subeki de aru (Our whale research program is in its tenth year. The whale ecosystem that humans
have reduced should be restored by them). Gyokyou Shinyou Jigyou Suishin Jouhou 50: 6–8. (In Japanese).
Ohsumi, S. 1997. Kujira to himan (Whales and obesity). Gekkan Kenkou 468: 50–51. (In Japanese).
Ohsumi, S. 1997. Kujira to hito tono aratana kyouzon no katachi wo mezashite (Taidan) (Towards a new type of coexistence
between people and whales (Conversation)). News Letter Sakanakana 15: 1–3. (In Japanese).
Ohsumi, S. 1997. Souseiki kara hattenki e (From the ﬁrst century to the development period). Suisan Sekai 46 (12): 18–20.
(In Japanese).
Ohsumi, S. 1997. Tokushuu—Zuisou 1. Kagaku kyouzai toshite no kujira (Special Feature—Essay 1. Whales as a scientiﬁcteaching material. Gekkan Kokugou Kyoiku 17 (9): 14–17. (In Japanese).
1998
Ohsumi, S. 1998. Airurando dakkyouan wo meguri, sen’eika shita hogei, hanhogei no tairitsu. Konmei no uchi ni owatta dai
50 kai IWC nenji kaigi (Whaling and anti-whaling conﬂict escalates over Irish Compromise proposal—The 50th IWC
Annual Meeting ended in turmoil). Foto 45 (13): 44–46. (In Japanese).
Ohsumi, S. 1998. Hito to kujira ga shokuryou soudatsusen. Sekai gyokakudaka no 6 bai wo hoshoku (Humans and whales
compete for food. Feeding on six times the global catch). Shuukan Sekai to Nippon 1998.10.19. (In Japanese).
Ohsumi, S. 1998. Hyouhon saishuusen no daisen kenzou ga hitsuyou (We need to build a replacement for the whale sampling
vessels). Ashita ni Nozomu: 344–350. (In Japanese).
Ohsumi, S. 1998. Seibutsu shigen toshite no kujira (Whales as biological resources). Ashita no Shokuhin Sangyou 289:
32–37. (In Japanese).
Ohsumi, S. 1998. Shin hogei kousou wo souki ni teian (Propose new whaling concept as soon as possible). Suisan Shuhou
1448: 17. (In Japanese).
Ohsumi, S. 1998. Umi no tora. Shachi (Orca—Tigers of the sea). Umi Okishiitekku Nyuusuretaa 17: 13–14. (In Japanese).
Ohsumi, S. 1998. Yuushin-Maru no katasuyou ni oukina kitai (Great expectations for the success of Yushin-Maru). Suisan
Sekai 47 (11):63. (In Japanese).
1999
Ohsumi, S. 1999. Iron hanron. Dokusha kara 8 gatsu go “Kantou Zuisou” ni mono mousu (Objection Argument—Reader
makes a statement on the August issue “Introduction Essay”). Suisankai 1377: 16. (In Japanese).
Ohsumi, S. 1999. Soukai aisatsu (General Assembly Address). Geiyuukai Kaihou 33: 9–11. (In Japanese)
Ohsumi, S. 1999. “Zeikin dorobou” to “Akutoku bengoshi” (The “Tax Thief” and “Rogue Lawyer”). Enyou Suiken OB
Kaidayori 3: 6–7. (In Japanese).
Ohsumi, S. (Supervision) 1999. Kujira no fushigi wo sagutte miyou (Let’s explore the wonders of whales). Pipoparu 4 (3):
4–10. (In Japanese).
Ohsumi, S. 1999. Shimbun no koramu wo tantousuru (Writing a newspaper column). Numagoe 232: 163. (In Japanese).
2000
Ohsumi, S. 2000. Kujira shokubunka to sono sonchou (Whale food culture and its respect). Umi 3: 2. (In Japanese).
Ohsumi, S. 2000. Geirui no seitai ni kansuru goshinkou no ei ni yokushite. Tennou Heika gosokui juunen houshuku iinkaihen (Lecture on the ecology of whales in the presence of His Majesty. Edited by His Majesty the Emperor’s Enthronement Ten Years Celebration Committee). Gosokui Juunen Kinen. Gosokui Juunen wo Kotohogite: 69–70. (In Japanese).
Ohsumi, S. 2000. Hogei mondai no jittai (The actual situation of the whaling issue). Tsubasa 62: 123–128. (In Japanese).
Ohsumi, S. 2000. Intabyuu. (Zai) Nihon Geirui Kenkyuusho. Ohsumi Seiji Rijichou. Geirui no koukatekina hozon to gouriteki riyou wo kangaeru (Interview with Dr. Seiji Ohsumi, Director-General of the Institute of Cetacean Research. Eﬀective conservation and rational utilization of cetaceans). SEIKAI: 7. (In Japanese).
Ohsumi, S. 2000. Korekara no hogei (Whaling in the future). Gyosen 346: 118–125. (In Japanese).
Ohsumi, S. 2000. Kujira no riyou ni kansuru futatsu no kitai. 21 seiki no kaiyou kaihatsu to kaisanken 30 nen no ayumi (Twoexpectations on the use of whales. Ocean development in the 21st Century and 30 years of the Research Institute for

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Ocean Economics). Kaiyousangyou Kenkyuukai 48–49. (In Japanese).
Ohsumi, S. 2000. Nihon-jin to kujira no kakawariai (Relationship between the Japanese and whales). Chouryuu 20. (InJapanese).
Ohsumi, S. 2000. Nihonkai setorojii kenkyuukai komon shuunin ni saishite. Kenkyuukai no saranaru hatten wo kitaisuru (Onbecoming an advisor of the Sea of Japan Cetology Research Association. I hope for the future development of the Association). Setoken Nyuuzuretaa 17. (In Japanese).
Ohsumi, S. 2000. Atarashii hogeizou no sekai e no hasshin wo (A new image of whaling to the world). Gyoson 66 (1): 1–15.
(In Japanese).
2001
Ohsumi, S. 2001. Geirui wo fukumeta jizoku kanouna gyogyou wo mezasu beki desu (We should aim for sustainable ﬁsheries, including whales). Sarai 13 (6): 15. (In Japanese).
Ohsumi, S. 2001. Kujira wa unabara wo dono you ni riyoushiteiru ka. Jinkoueisei wo riyoushita kujira no seitai, koudou kaiseki (How do whales use the ocean? Ecological and behavioral analysis of whales using satellites). Earthian 192: 8–13.
(In Japanese).
Ohsumi, S. 2001. Kujira wa unabara wo dono you ni riyoushiteiru ka. Jinkoueisei wo riyoushita kujira no seitai, koudou kaiseki (How do whales use the ocean? Ecological and behavioral analysis of whales using satellites). Nature Interface 6:
22–23. (In Japanese).
Ohsumi, S. 2001. Kujira no sanma hoshoku chousa ni kitaisuru. Miyagi-ken sanma shutsuryousen no chousa, kyouryoku ni
kansha (We look forward to the whale saury predation survey. Gratitude for the survey and cooperation of the Paciﬁcsaury ﬁshing boats in Miyagi Prefecture). Suisan Sekai 50 (9): 34–35. (In Japanese).
Ohsumi, S. 2001. Kujira no kakochou (Whale register of deaths). Shima e 1 (1): 70. (In Japanese).
Ohsumi, S. 2001. Shironagasukujira no kokkaku hyouhon no tenji wo iwatte. Shimonoseki Kaiyoukagaku Akademii hen.
Shironagasukujira zenshin kokkaku. Nihon, Noruwee kyoudou purojekuto no ayumi. 1 (Celebrating the display of theblue whale skeleton specimen. Shimonoseki Academy of Marine Sciences. Blue whale whole body skeleton—Historyof Japan–Norway joint project. 1). Shimonoseki Kagaku Akademii. (In Japanese).
Ohsumi, S. 2001. Tokubetsu kikou. Naze Nihon wa hogei saikai wo shuchou suru no ka? (Special Contribution: Why does
Japan insist on resuming whaling?). Seikai 23 (8): 104–106. (In Japanese)
Ohsumi, S. (supervisor) 2001. Umi no champion. Kujira no nakama (Whales - Champions of the sea). Kindaabukku 56 (4):
2–11. (In Japanese).
2002
Ohsumi, S. 2002. Dai ni Yuushin-Maru no youyoutaru zento wo shukusu (Congratulating the Yushin Maru No. 2 on its great
voyage). Suisankai 51 (11): 55. (In Japanese).
Ohsumi, S. 2002. Geirui wo fukumu kaiyou shigen no jizokuteki riyou wo (Sustainable use of marine resources including
whales). Suisan Shuuhou 1569: 4–7. (In Japanese).
Ohsumi, S. 2002. GHQ no shiji de hogei saikai “san-nin iinkai” to no o-goudou kaigi ni sanka. Kagaku dewanaku hyouketsu
de gouru no nai haadoru kyousou. “Hogei mondai” to Nihon gaikou. Dai 6-kai intabyuu naiyou (Whaling resumed at
the behest of GHQ. Participating in a joint meeting with the “Committee of Three”. Not science, but a vote, a hurdle
race without a goal. The “Whaling Issue” and Japan’s Diplomacy—Interview No. 6). Seiji Kenkyuuin Seisaku Kenkyuu
Daigakuin Daigaku: 163–187. (In Japanese).
Ohsumi, S. 2002. Hogei kanren de osewa ni natta Fujinami Tokuo-san. Fujinami Tokuo shi tsuitou kinen kankou sewanin-kaihen (Mr. Tokuo Fujinami, who helped me with whaling matters. Tokuo Fujinami Memorial Publication Caretaker Association (ed.)). Fujinami Tokuo-san wo Shinobu 137–139. (In Japanese).
Ohsumi, S. 2002. IWC Shimonoseki kaigi no shouten (Focus of IWC Shimonoseki Conference). Gekkan Seikai Politico 24(6): 72. (In Japanese).
Ohsumi, S. 2002. Korekara no kujira tono tsukiaikata (How to deal with whales in the future). Kuriamarin Fukushima Kikakuten Kujira Arawaru—Yomigaeru Kujira Bunka: 17–19. (In Japanese).
Ohsumi, S. 2002. Kujira no zasshou ni tsuite kangaeru (Considerations about whale strandings). Ship & Ocean Newsletter
53: 6–7. (In Japanese).
Ohsumi, S. 2002. Nichigeiken no katsudou to IWC Shimonoseki kaigi e no kitai (Expectations for the ICR activities and the
IWC Shimonoseki Meeting). Kaiin: 24–27. (In Japanese).
Ohsumi, S. 2002. Ronsetsu. Nihon no bunka toshite no geishoku wo kangaeru (Editorial. On whale eating as part of Japaneseculture). Kikan Nihon-jin to Sakana 2002 Fuyu: 19–27. (In Japanese).
Ohsumi, S. and Ikeda Y. 2002. (2002 Nen shinshun tokubetsu taidan) Fueru kujira, heru maguro ((New Year’s Special Interview 2002) More Whales, Fewer Tuna). Suisan Sekai 51 (1): 52–29. (In Japanese).
Ohsumi, S. and Yoshimura S. 2002. (Taidan) Geishoku kenbi 6. Kujira taidan—“Geishoku Kenbi” (Interview—Whale foodand beauty (6): A conversation about “Whale Food and Beauty”). IWC Shimonoseki Kaigi Suishin Kyougikai: 57–72.
(In Japanese).
2003
Ohsumi, S. 2003. Goaisatsu (Salutation). Geiyuukai Kaihou 41: 19–20. (In Japanese).
Ohsumi, S. 2003. Korekara no hogei (Future whaling). Kanda Shuuhou 39 (29): 1. (In Japanese).
Ohsumi, S. 2003. Nourinshou. Kongo no IWC taiou shiken (MAFF: Personal opinion on future dealing with IWC). Shuukan
Nourin 1858. (In Japanese).

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Ohsumi, S. 2003. Suisan dantai toppu kaiken. Dai 2 ki nanpyouyou chousa ni zenryoku. Ohsumi nichigeiken rijichou kaiken(Press conference by ﬁsheries organizations’ heads. We will do our best to carry out the second phase of the Southern
Ocean whale research. A press conference by Seiji Ohsumi, the Institute of Cetacean Research Director-General).
Suisankai: 25–26. (In Japanese).
Ohsumi, S. 2003. Suisan shuyou dantai toppu “2003 nen no houfu” jiki nanpyouyou chousa keikaku ni torikumu. Nihon geirui kenkyuusho Ohsumi Seiji rijichou (Top of ﬁshery organization “Aspirations for 2003”. Working on the next Southern Ocean survey plan. Seiji Ohsumi, Director-General of the Institute of Cetacean Research. NEWS Umi no Sachi. (InJapanese).
Ohsumi, S. 2003. Zuiso. Nihon ni okeru geiruigaku no kako, genzai soshite mirai (Essay: Past, present and future of cetology
in Japan). Kahaku Kokuritsu Kagaku Hakubutsukan Nyuusu: 3. (In Japanese).
2004
Ohsumi, S. 2004. Kujira kenkyuu no “Tokiwa Sou” jidai (The “Tokiwa-so” era of whale research). Yuushin 40: 74–81. (InJapanese).
Ohsumi, S. 2004. Kujira no Shinshu (A new species of whale) Nihon-jin to Sakana 14: 40–42. (In Japanese).
Ohsumi, S. 2004. Kurashi no jouhou. Abashiri no iki iki 7 chin “Tsuchikujira” (Information on daily life. Abashiri’s lively
and quintessential 7 dainty bits—Baird’s beaked whale). Kouhou Abashiri: 16. (In Japanese).
Ohsumi, S. 2004. (Zadankai) Kujiratori to hyouryuumin ((Round-table discussion) Whale hunters and castaways). Yuurin
445: 1–3. (In Japanese).
Ohsumi, S. (supervisor) 2004. Kujira omoshiro kuizu (Whale funny quiz). Chairudo Bukku Kangaeru 20 (5): 1–10. (InJapanese).
2005
Ohsumi, S. 2005. Kono hito wo kataru. Kujira wo tomo ni 50 nen (Talk about this person. 50 years with whales as friends).
Kikan Nihon-jin to Sakana 2005 Natsu: 78–80. (In Japanese).
Ohsumi, S. 2005. Geirui to gyogyou no kyougou mondai (Competition between whales and ﬁsheries). Shoku no Kagaku 327:
34–40. (In Japanese).
Ohsumi, S. 2005. Nanpyouyou hogei no sara naru hatten wo mezashite (Towards the further development of Southern Ocean
whaling). Kaiin 57 (7): 20–24. (In Japanese).
Ohsumi, S. 2005. Shachi koukai 1-shuu nen kinen kouen. Kujira to ningen shakai (A lecture commemorating the ﬁrst anniversary of the orca exhibition. Whales and human society). Nagoya Minato Shinkou Zaidan Nyuusureetaa “Sakanakana” 46: 5–6. (In Japanese).
Ohsumi, S. 2005. Development of Japanese-style whaling to the Antarctic. Its history and future. Learning from the Antarctic
Whaling: 82–99.
2006
Ohsumi, S. 2006. Hinpatsu suru kujira to fune no shoutotsu (Frequent collisions between whales and ships). Ship & Ocean
Newsletter 139: 4–5. (In Japanese).
2007
Ohsumi, S. 2007. Kujira to hito. Taiko kara tuzuku kankei no ashiato (Whales and people. Footprints of a relationship that
goes back to ancient times). Bunka Isan no Sekai 24: 2–3. (In Japanese).
2008
Ohsumi, S. 2008. Hoeeru uwotchingu to hogei wa kyouzon dekiru (Whale watching and whaling can coexist). Ship & Ocean
Newsletter 189: 6–7. (In Japanese).
Ohsumi, S. 2008. Kujirahige no bunkashi (Baleen cultural history). Isana 49: 3–10. (In Japanese).
Ohsumi, S. 2008. Kujira shiryoushitsu ni kitaisuru koto (What to expect from the Whale Library and Museum). Shimonoseki
Shiritsu Daigaku Kujira Shiryoushitsudayori 1: 1. (In Japanese).
Ohsumi, S. 2008. Makkoukujira no choujikan sensui no kijo (kaitou) (Mechanism of long-term diving of sperm whales (Reply)). Nihon Iji Shinpou 4417: 101–102. (In Japanese).
Ohsumi, S. 2008. Geirui shigen chousa ni okeru chishiteki chousa to hichishiteki chousa (Letal and non-lethal reseach in cetacean stock surveys). Geiron-Touron. Kujira Poutaru Saito. (In Japanese).
Ohsumi, S. 2008. Nankyoku kai de geirui no chousa wo suru hitsuyousei to shin hogei kousou (The need for whale researchin the Antarctic and the new whaling initiative). Geiron-Touron. Kujira Poutaru Saito. (In Japanese).
Ohsumi, S. 2008. Semarikuru shokuryou kiki to hogei mondai (The looming food crisis and the whaling issue). Isana 10: 13.
(In Japanese).
2009
Ohsumi, S. 2009. Ebisu toshite no kujira (Whales as Ebisu). Chuuo Suiken Dousoukai Renraku Jouhou Nyuusu H 20-2:
4–12. (In Japanese).
Ohsumi, S. 2009. “Semi-nagare” no haikei ni kansuru ichikousatsu. Kumano chihou kenkyuukai (A study on the backgroundof the “semi-nagare” incident. Kumano Local History Study Group). Kumanoshi 56: 100–111. (In Japanese).
Ohsumi, S. 2009. Shironagasukujira no taikei zakki “Shinpan—Kujira to iruka no ﬁirudogaido” ni yosete (Miscellaneousnotes on the blue whale body shape—The “Field Guide to Whales and Dolphins, New Edition”). UP 440: 1–5. (InJapanese).
2010
Ohsumi, S. 2010. Harabire wo motsu bandouiruka—Sono gakujutsuteki kachi towa (A bottlenose dolphin with pelvic ﬁns—

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What is its scientiﬁc value?). Kikan Bioﬁria 6 (4): 65–68. (In Japanese).
Ohsumi, S. 2010. Hichishiteki chousa dake dewa nankyokukai no geirui chousa wa seikou shinai kotoga shoumeisareta(Results prove that whale research in the Antarctic would not succeed with non-lethal survey methods alone). Geiron
Touron. Kujira Poutaru Saito. (In Japanese).
Ohsumi, S. 2010. Kagaku ga kouyougo ni naranai IWC (IWC, where science is not the oﬃcial language). Suisan Jaanarisutono Kai Kaihou. 109: 4. (In Japanese).
Ohsumi, S. 2010. Kujira to tomo ni han seiki (Half a century with the whales). Koujun Zasshi 546: 24–39. (In Japanese).
Ohsumi, S. 2010. Toukyou to kujira (Tokyo and whales). Suisan Shinkou 515: 1–57. (In Japanese).
2012
Ohsumi, S. 2012. Nishiwaki Masaharu hakase (Dr. Masaharu Nishiwaki). Isana 56: 2–17. (In Japanese).
2013
Ohsumi, S. 2013. Kujira shokubunka (1). Ko senryuu kara ukagaeru Edo no kujira shokubunka (Whale food culture (1). The
whale eating culture of the Edo period as seen in old senryuu). Kujira Shokubunka wo Mamoru Kai. Kikan Kujira-gumi
1: 3. (In Japanese).
Ohsumi, S. 2013. Kujira kankei no shoseki shoukai (Books about whales). Kujira Shokubunka wo Mamoru Kai. Kikan
Kujira-gumi 1: 3. (In Japanese).
2014
Ohsumi, S. 2014. Kujira shokubunka (2). Kitamaebune ni yoru kujira shokubunka no denpan (Whale food culture (2). Propagation of whale food culture by “kitamaebune”, cargo ships that sailed the Japan Sea during the Edo Period). Kujira
Shokubunka wo Mamoru Kai. Kikan Kujira-gumi 2: 3. (In Japanese).
Ohsumi, S. 2014. Kujira shokubunka (3). Obake (Whale food culture (3). Whale tail). Kujira Shokubunka wo Mamoru Kai.
Kikan Kujira-gumi 3: 2. (In Japanese).
Ohsumi, S. 2014. Kujira shokubunka (4). Meiji kouki ni Nihon kujira shokubunka wo sekai ni shoukaishita gaikokujin(Whale food culture (4). Foreigners who introduced Japanese whale food culture to the world in the latter half of the
Meiji era). Kujira Shokubunka wo Mamoru Kai. Kikan Kujira-gumi 5: 4. (In Japanese).
Ohsumi, S. 2014. Kujira shokubunka (5). Kujira no kanzume (Whale food culture (5). Canned whale). Kujira Shokubunka
wo Mamoru Kai. Kikan Kujira-gumi 5: 4. (In Japanese).
Ohsumi, S. 2014. Zuihitsu. Kujira no hanshoku ni kanrenshite (Essay. In relation to the breeding of whales). Kyoudou Seminaa 389: 6–7. (In Japanese).
2015
Ohsumi, S. 2015. Bosei intabyuu. Kono hito no “Jikkan” wo kikitai. Ohsumi Seiji-san (Bosei Interview: Listening to the the“reality” of this man—Seiji Ohsumi). Bosei 559: 72–80. (In Japanese).
Ohsumi, S. 2015. Kujira shokubunka (6). Kaburabone (Whale food culture (6). Whale head cartilage). Kujira Shokubunka
wo Mamoru Kai. Kikan Kujira-gumi 6: 4. (In Japanese).
Ohsumi, S. 2015. Kujira shokubunka (7). Nihon de kujira shokubunka ga hattatsushita youin (Whale food culture (7).
Factors that led to the development of whale eating culture in Japan). Kujira Shokubunka wo Mamoru Kai. Kikan
Kujira-gumi 7: 4. (In Japanese).
Ohsumi, S. 2015. Kujira shokubunka (8). Haguki (Whale food culture (8). The gums). Kujira Shokubunka wo Mamoru Kai.
Kikan Kujira-gumi 8: 4. (In Japanese).
Ohsumi, S. 2015. Kujira shokubunka (9). Karada no bubun no meishou no oosa ga shokubunka no hattatsu wo arawasu(Whale food culture (9). The plethora of names for body parts represents the development of whale food culture).
Kujira Shokubunka wo Mamoru Kai. Kikan Kujira-gumi 9: 4. (In Japanese).
Ohsumi, S. 2015. Nihon no kaisei honyuudoubutsugaku no kiso wo kizuita ijintachi 2. Omura Hideo Hakase (The foundersof Marine Mammalogy in Japan 2. Dr. Hideo Omura). Isana 63: 2–16. (In Japanese).
2016
Ohsumi, S. 2016. Kujira shokubunka (10). Zenkoku no kujira wo taberareru ryouriten no kazu (Whale food culture (10). The
number of restaurants that serve whale across the country). Kujira Shokubunka wo Mamoru Kai. Kikan Kujira-gumi
10: 4. (In Japanese).
Ohsumi, S. 2016. Kujira shokubunka (11). Saezuri (Whale food culture (12). Whale’s tongue). Kujira Shokubunka wo Mamoru Kai. Kikan Kujira-gumi 11: 4. (In Japanese).
Ohsumi, S. 2016. Kujira shokubunka (12). Nihon no kujira shokubunka no hattatsu to keishou wo kangaeru (Whale foodculture (12). Considering the development and legacy of Japan’s whale food culture). Kujira Shokubunka wo Mamoru
Kai. Kikan Kujira-gumi 12: 4. (In Japanese).
Ohsumi, S. 2016. Kujira shokubunka (13). Tare (Whale food culture (13). Tare (dried whale meat)). Kujira Shokubunka wo
Mamoru Kai. Kikan Kujira-gumi 13: 4. (In Japanese).
Ohsumi, S. 2016. Ano hi, ano aji 166. Kujira no “tare” (The taste of that day 166. “Tare”, dried whale meat). Bosei 4: 68–69.
(In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 1. Tokubetsuna gochisou (A story of whales and Japanese culture 1. Special treats). Bosei 566: 82–83. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 2. Yon meetoru no ue to shita (A story of whales and Japanese culture 2.
Above and below four meters). Bosei 567: 84–85. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 3. Gei’in bashoku (A story of whales and Japanese culture 3. Drinking

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like a whale and eating like a horse). Bosei 568: 90–91. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 4. Shokuryou kiki to kujira (A story of whales and Japanese culture 4.
Food crisis and whales). Bosei 569: 92–93. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 5. Ebisu toshite no kujira (A story of whales and Japanese culture 5.
Whales as Ebisu). Bosei 570: 94–95. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 6. Choujabanzuke ni notta hogeigumi nushi (A story of whales andJapanese culture 6. Whaling group owners listed in the ranking of the wealthy). Bosei 571: 94–95. (In Japanese).
Ohsumi, S. 2016. Kujira to Nihon bunka no hanashi 7. Kujira shaku (A story of whales and Japanese culture 7. The cloth
measure “kujira-jaku”). Bosei 572: 88–89. (In Japanese).
2017
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 8. Geigei no ago ni kaku (A story of whales and Japanese culture 8. On
the chin of the whale). Bosei 573: 88–89. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 9. Hokuzen sen ga hirogeta kujira shokubunka (A story of whales andJapanese culture 9. Whale eating culture spread by cargo ships that sailed the Japan Sea during the Edo period). Bosei
574: 88–89. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 10. Mekujira to iigakari (A story of whales and Japanese culture 10.
Whale’s eye (the corner of one’s eye) and pretext). Bosei 575: 88–89. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 11. “Geishoku” wa sekai ni hokoru bunka (A story of whales andJapanese culture 11. “Whale eating” is a world-class culture). Bosei 576: 92–93. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 12. Kujira uta (A story of whales and Japanese culture 12. Whaling
songs). Bosei 577: 92–93. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 13. Emakimono ni egakareta koshiki hogei (A story of whales andJapanese culture 13. Old-style whaling depicted in picture scrolls). Bosei 578: 82–83. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 14. Nagato no hogei bunka wo “Nihon isan” ni (A story of whales andJapanese culture 14. Make Nagato’s whaling culture a “Japan Heritage”). Bosei 579: 84–85. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 15. Nishiki-e ni mo egakareta kujira (A story of whales and Japaneseculture 15. Whales, too were depicted in woodblock prints). Bosei 580: 84–85. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 16. Hachijuu hachi mono bui ni na ga aru (A story of whales andJapanese culture 16. Eighty-eight parts of the whale are named). Bosei 581: 86–88. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 17. Hogei ga kyokasareru jouken towa (A story of whales and Japaneseculture 17. What are the conditions under which whaling is permitted?). Bosei 582: 84–88. (In Japanese).
Ohsumi, S. 2017. Kujira to Nihon bunka no hanashi 18. Ferou shotou no oikomi ryou (A story about whales and Japaneseculture 18. The Faroe Islands drive ﬁshery). Bosei 583: 86–87. (In Japanese).
Ohsumi, S. 2017. Kujira shokubunka (14). Yaji-Kita mo kujira wo tabeta (Whale food culture (14). Yaji and Kita too had
whale). Kikan Kujira Gumi 14: 4. (In Japanese).
Ohsumi, S. 2017. Kujira shokubunka (15). Mamewata (Whale food culture (15). Kidneys). Kikan Kujira Gumi 15: 4. (InJapanese).
Ohsumi, S. 2017. Kujira shokubunka (16). Hyakuhiro to sensuji (Whale food culture (16). Small intestine and tendons). Kikan Kujira Gumi 16: 4. (In Japanese).
Ohsumi, S. 2017. Kujira shokubunka (17). Kujira no niku wa naze kuroi (Whale food culture (17). Why is whale meat so
black?). Kikan Kujira Gumi 17: 4. (In Japanese).
Ohsumi, S. 2017. Hayashi Shigeichi san wo itami, kouseki wo tataeru (Mourning and honoring the achievements of Shigeichi Hayashi). Suisancho Kenkyushochou OB-kai Nyuusu 5: 9–10. (In Japanese).
Ohsumi, S. 2017. Taidan. Ayukawa no fukkou wa kujira kara (Conversation: The Reconstruction of Ayukawa starts withwhales). Ishinomaki Gaku 3: 24–33. (In Japanese).
2018
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 19. Nihon-jin no umi no ikimono tono ittaikan (A story about whales
and Japanese culture 19. The Japanese sense of oneness with sea life). Bosei 584: 86–87. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 20. Chousen Tsuushinshi to kujira shokubunka (A story about whales
and Japanese culture 20. The Korean Emissary and whale culture). Bosei 585: 88–89. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 21. Hogei ni miru wakon yousai (A story about whales and Japanese culture 21. Japanese spirit and Western learning in whaling). Bosei 586: 80–81. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 22. Choumin no myouji ga shimesu hogei bunka (A story aboutwhales and Japanese culture 22. The culture of whaling indicated by townspeople’s surnames). Bosei 587: 80–81. (InJapanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 23. Kujira shigen no tadashii riyou houhou (A story about whales andJapanese culture 23. Proper user of whale resources). Bosei 588: 78–79. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 24. Genpei Gassen to kujira (A story about whales and Japanese culture
24. The Gempei War and whales). Bosei 589: 78–79. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 25. Ikei no shinboru toshite no kujira (A story about whales andJapanese culture 25. Whales as a symbol of reverence). Bosei 590: 78–79. (In Japanese).
Ohsumi, S. 2018. Kujira to Nihon bunka no hanashi 26. San-bon no dokyumentarii eiga (A story about whales and Japanese

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culture 26. Three documentary ﬁlms). Bosei 591: 78–79. (In Japanese).
Ohsumi, S. 2018. Kujira shokubunka (18). Kujira Fes 2017 (Whale Food Culture (18). Whale Fest 2017). Kikan Kujira Gumi
18: 4. (In Japanese).
Ohsumi, S. 2018. Kujira shokubunka (19). Sekai no kujira shokuhin no dentouteki hozonhou (Whale Food Culture (19). Traditional preservation of whale foods in the world). Kikan Kujira Gumi 19: 4 (In Japanese).
Ohsumi, S. 2018. Kujira shokubunka (20). Kokumin shoku toshite no ise-ebi to kujira (Whale Food Culture (20). Spiny lobsters and whales as national foods). Kikan Kujira Gumi 20: 4. (In Japanese).
Ohsumi, S. 2018. Kujira shokubunka (21). Kujira no kashi (Whale Food Culture (21). Whale sweets). Kikan Kujira Gumi 21:
4. (In Japanese).
Ohsumi, S. 2018. Otona no kujira seitai gaku. Ni kai Kujira-juuku—Asakusa “Komagata Dozeu” de kaisai (Whale Ecology
for Adults. “Whale cram school” held twice at Komagata Dozeu, Asakusa). Kikan Kujira Gumi 19: 2. (In Japanese).
Ohsumi, S. 2018. Sougyo hyaku shuu nen wo o-iwaishi sara naru hatten kinen shimasu. Maruho sougyou hyaku shuu nenshi (Celebrating Maruho’s 100th anniversary and praying for further growth. Maruho’s Centennial History: 9–10. (InJapanese).
Ohsumi, S. 2018. Shin hogei bousen no kenzou ni yotte hogei saikai e no Nihon no futaiten no ketsu’i wo sekai e! (Building
a new whaling mothership will show the world Japan’s unwavering determination to resume whaling). Isana 20. Kujira
Shokubunka wo Mamoru Kai: 13. (In Japanese).
Ohsumi, S. 2019. Kujira shokubunka (22). Geiyu no himan boushi shokuhin toshite no kouyo (Whale Food Culture (22).
Beneﬁts of whale oil as an anti-obesity food). Kikan Kujira Gumi 22: 4. (In Japanese).
2019
Ohsumi, S. 2019. Kujira shokubunka (23). Geishoku PR shite saikaisuru hogei wo sasaeyo (Whale Food Culture (23). Let’s
support the resumption of whaling by promoting whale eating). Kikan Kujira Gumi 23: 4. (In Japanese).
Ohsumi, S. 2019. Nihon ga korekara kaishisuru hogei ni kitaisuru (Expectations for Japan’s future whaling). Gekkan Gyogyou to Gyokyou 648: 18–21. (In Japanese).
2020
Ohsumi, S. 2020. Hakkan ni yosete (4–5). Senzenki nanpyouyou hogei no kouseki. Maruha sogyousha, Nakabe-ke shiryou kara (On the occasion of publication (4–5). In Mitsuhiro Kishimoto (ed.) The Wake of Pre-war Southern Ocean
Whaling. From the documents of the founder of Maruha and the Nakabe Family). Karansha. Fukuoka: 215 pp. (InJapanese).

Acknowledgements

We would like to extend our thanks to Dr. Rebecca Lent, IWC Executive Secretary, Dr. Iain Stainland, Lead of Science,and Mrs. Stella Duﬀ, Senior Executive Assistant at the IWC Secretariat, for compiling and sending us a list of 182 papers
authored/co-authored by Dr. Seiji Ohsumi and presented to the IWC meetings and published by the IWC. Almost half of thepapers in their list were lacking from our original records and much helped to make this bibliography a more detailed one.

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COLLECTION OF MOMENTS
Compiled by Gabriel GOMEZ DIAZ

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83Fig. 1. In 1954 Seiji went for the ﬁrst time on a Mothership whaling operation: the Kinjo-Maru western North
Paciﬁc whaling ground exploratory survey. At the time he was a master’s degree student and was hired as atemporary employee of the Fisheries Agency to work as a junior ﬁsheries supervisor, also participating in biological research of captured whales. He was 23.

Fig. 2. Seiji on the deck of the whaling Mothership Tonan-Maru
before departure (1950s).

Fig. 3.

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On a whale catcher boat in the Antarctic (1972).
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Fig. 4. Dr. Seiji Ohsumi (right end, front row) posing with Dr. Hideo Omura (right end, back row), Prof.
Masaru Nishiwaki (fourth from the right end, back row) and fellows during a Whales Research Institute(WRI) member trip to Yugawara Onsen hot spring resort facility (1960s).

Fig. 5. In Tsukishima at the entrance of the WRI during a visit by Dr. David E. Gaskin (center, front row). Dr.
Ohsumi is second from left, back row. We can see also Drs. Hideo Omura, Keiji Nasu, Toshio Kasuya andTadayoshi Ichihara among other WRI staﬀs.
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Fig. 6. At the Mombetsu (Hokkaido) ﬂensing platform. Right whale special permit sampling personnel. Fromleft to right: Drs. Hideo Omura, Seiji Ohsumi, Saburo Machida, Akito Kawamura and Toshio Kasuya (1961).

Fig. 7. Special Meeting of the IWC/SC in La Jolla, CA. Seiji (9th from left) posing together with Drs. Roy
Chapman, Edward D. Mitchell, Michael Tillman, Åage Jonsgaard, Ray Gambell, John Bannister, Hideo Omura, James G. Mead, Mikhail V. Ivashin and other important members at the time (December 1974).

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Fig. 8.

Seiji with Dr. Omura at a gathering.

Fig. 9.

During a meeting in the United States.

Fig. 10. With Prof. Doug Butterworth and other colleagues, 1994 IWC/SC meeting.

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Fig. 11. A gathering during the Aging Seminar by Dr. Christina Lockyer (center, front) with many scientists
and students at Tokyo University of Marine Science and Technology, December 2009.

Fig. 12. 2010 POWER planning meeting in Tokyo. Posing with colleagues next to the right whale skeleton
originally sampled by Seiji in 1961, on display at the Marine Science Museum, Tokyo University of Marine
Science and Technology.

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Fig. 13. 2010 POWER planning meeting in Tokyo. Next to Seiji is Dr. Bob Brownell. We can see Drs. Greg
Donovan, Phil Clapham, Yulia Ivashchenko, Sharon Hedley, Toshihide Kitakado, Rock An, Yoshihiro Fujise,
Koji Matsuoka, Tomio Miyashita, Toshiya Kishiro and Hidehiro Kato among other relevant participants.

Fig. 14. Memorial party to pay tribute to the memory of Peter Best. Front row, from left to right: Keiko Sekiguchi, Greg Donovan, Seiji Ohsumi, John Bannister, Hidehiro Kato, Kazuo Yamamura and Tomio Miyashita(2015).
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Fig. 15. Memorial party to remember and honor the late John Bannister, held at Hotel Fukuracia Harumi,
Tokyo, in October 2018.

Fig. 16. Dr. Seiji Ohsumi having a normal working day—like on this 19 February 2019 morning, we often
found him perusing some of the IWC/SC working documents kept at the Institute of Cetacean Research(ICR).
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A blue whale just after blowing, Antarctic.

J-STAGE Advance published date: December 23, 2021

MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALESDWARF MINKE WHALES: MORPHOLOGY,GROWTH AND LIFE HISTORY BASED ON
SAMPLES COLLECTED FROM THE HIGHERLATITUDES IN THE SOUTHERN HEMISPHERE
Hidehiro KATO1, 2*, Yoshihiro FUJISE2, Gen NAKAMURA1,
Takashi HAKAMADA2, Luis A. PASTENE2, 3 and Peter B. BEST4†Tokyo University of Marine Science and Technology, 5–7–1 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
3
Project Microbiome as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia, Centro deEstudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile
4
Mammal Research Institute, University of Pretoria, c/o Iziko South Africa Museum,
P. O. Box 61, Cape Town, 8000 South Africa†
deceased on April 22, 2015.
*Corresponding author: katohide@kaiyodai.ac.jp

1

Abstract
This study examined the morphology, growth and life history of dwarf minke whales to
identify and conﬁrm any diﬀerences from other minke whale species and subspecies. The
study was based on biological samples and data obtained from 16 whales (3 males and 13
females) collected through the 1987/88 to 1992/93 austral summer seasons by the Japanese
Whale Research Program under Special Permit in the Antarctic (JARPA). The whales werecollected between latitudes 58°23′S and 65°04′S in the Antarctic area between 90°E and 180°.
Mean body length at physical maturity was estimated to be 7.16 m for females, approximately
1.5 m to 2.0 m smaller than equivalent values of Antarctic minke whales and North Paciﬁc
common minke whales. The characteristic feature of a white shoulder/ﬂipper patch was conﬁrmed and some variations in the overall color pattern was found. Skeletal observations conﬁrmed the previously reported characteristic features on the vertex of the skull. In addition,
this study found a longer rostrum, deeply curved mandible, and narrower nasal bone in dwarf
minke whales in comparison with other minke whales. All pregnant females had conceived
in mid-austral winter (middle of June to early August). Females are likely to attain sexual
maturation at 6–6.5 m and at around 7–10 years of age. Stomach contents indicated that dwarf
minke whales mainly fed on lantern ﬁshes around the Antarctic Convergence in summer. Analyses by ANCOV revealed signiﬁcant diﬀerences in both external body and skull morphology
among diﬀerent species and subspecies. Furthermore, cluster analyses on the skull morphology revealed diﬀerentiation between dwarf minke whales and other common minke whales but
they are more closely related to North Atlantic common minke whales. These analyses concurred with previous genetic analyses results. The results of this study provided support for the
proposed subspeciﬁc status of dwarf minke whales.
Key words:

dwarf minke whale, diminutive minke whale, minke whale clade, morphology,
life history parameters.

Introduction
Early reports suggested the existence of a diﬀerent form of minke whale from the typical southern
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KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

minke whale (now known as the Antarctic minke whale, Balaenoptera bonaerensis) in the Southern
Hemisphere (Kasuya and Ichihara, 1965; Gaskin, 1976; Wada and Numachi, 1979; Best, 1982; Baker,
1983; Singrajah, 1983). Subsequently, Best (1985) described two morphological forms of southernminke whale as being the ordinary and the small (diminutive) forms based on material collected fromboth the South African coast and the Antarctic. He also documented diﬀerences in shoulder/ﬂipper
coloration, type of baleen as well as other diﬀering external morphological features between the twoforms: the smaller (‘dwarf’ or diminutive) and the larger ordinary (B. bonaerensis) forms.
Arnold et al. (1987) further examined the morphology of the small form of minke whales in theAustralian coastal area which he called ‘diminutive’ minke whales. They conducted some preliminary
osteological examination and found some characteristic skull features and distinctive pigmentation
which were additional to those reported in Best (1985). However, their sample sizes were too small
and geographically restricted to reach any deﬁnitive conclusions on their taxonomic status. Subsequently some additional studies were conducted on the Australian diminutive form e.g., Arnold et al.
(2005).
The Japanese Whale Research Program under Special Permit (JARPA) started in the 1987/88 austral summer season and continued until the 2004/05 season. The target species for the sampling was
the southern ‘ordinary’ minke whale. However, at the end of the ﬁrst survey in 1987/88, a minke
whale, having a noticeably clear white patch on the shoulder (Fig. 1) was sampled on 23 March 1988.
Fifteen additional whales with a similar characteristic were sampled in subsequent JARPA surveys
until the 1992/93 season. Those whales were associated with the dwarf minke whales reported byBest (1985) and Arnold et al. (1987). The total 16 dwarf minke whales were examined by two of theauthors (Kato and Fujise) on the deck of the research base vessel. Materials from these dwarf minke
whales were ﬁrst reported by Kato and Fujise (2000), and some of the biological data from their report
was used in Perrin and Brownell (2002, 2009) for their description of diﬀerent types of minke whales.
Wada et al. (1991) and Pastene et al. (1994) conducted the ﬁrst genetic analyses of dwarf minke
whales sampled by the JARPA, based on mitochondrial DNA. They found substantial diﬀerencesamong southern ‘ordinary,’ North Paciﬁc and dwarf minke whales. Their phylogenetic analyses suggested that dwarf minke whales were closer to the North Paciﬁc minke whale than to the southern
ordinary minke whale. North Atlantic minke whale samples were not available for genetic analysis atthat time and the authors recommended additional genetic and non-genetic analyses to elucidate thetaxonomy of the minke whale. Based on the genetic and non-genetic studies summarized above andthe recompilation of Rice (1998), the Committee of Taxonomy of the Society for Marine Mammalogy(SMM, marinemammalscience.org) listed the following species and subspecies of minke whale:
Antarctic minke whale, Balaenoptera bonaerensis Burmeister, 1867 also known as ordinary southern minke whale, Southern Hemisphere minke whale, ordinary form of minke whale, dark shoulder

Fig. 1. A dwarf minke whale (88/89-013) sampled under the JARPA program in the Antarctic, in the 1988/89
season.

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

form of minke whale.
Common minke whale, B. acutorostrata Lacépède, 1804 having three separate subspecies as below:
North Atlantic minke whale, B. a. acutorostrata Lacépède, 1804.
North Paciﬁc minke whale, B. a. scammoni, Deméré, 1986.
Dwarf minke whale, B. a. un-named subsp. [Rice, 1998] also known as diminutive minke
whale, dwarf form of minke whale.
More recent genetic analyses using samples of minke whale worldwide provided further evidence
for the separation of the two species, and at least three subspecies of the common minke whale using
mtDNA sequences (Pastene et al., 2007, 2010) and microsatellite DNA (Glover et al., 2013). Thesestudies indicated that dwarf minke whales are more closely related to the North Atlantic common minke whale (see also relevant sections in Murase et al., 2020).
The biological samples and data of dwarf minke whales taken by the JARPA were further analyzed
in the present study following the initial analyses conducted by Kato and Fujise (2000) while it is stilla small sample size. The aim of the study is to compare the biological features, including external andskeletal morphologies, with those of other species and sub-species of minke whales in an attempt toelucidate the taxonomic status of the dwarf minke whale. Also, the study provided an opportunity totest the hypothesis derived from recent genetic studies that dwarf minke whales are more closely related to the North Atlantic common minke whale.

Materials and methods
The present paper examined biological features of the dwarf minke whales taken by the Japanese
Whale Research Program under Special Permit in the Antarctic (JARPA). Preliminary results of theprevious analyses of these samples were presented to the IWC Scientiﬁc Committee meeting in 2000
(Kato and Fujise, 2000). The biological features, including external and skeletal morphologies, werecompared in the present study with those of other species and sub-species of minke whales in an attempt to elucidate the taxonomic status of the dwarf minke whale.
Biological materials
The present study primarily used biological samples and information collected from the 16 dwarf
minke whales (3 males and 13 females) sampled under JARPA through 1987/88 to 1992/93, at whichtime the dwarf minke whale was not recognized as a diﬀerent taxon from the Antarctic minke whale,at least at the species level. No dwarf minke whales were sampled after the seasons of 1992/1993. Table 1 summarizes primary biological information used in the present study. The following data werecollected onboard the research base vessel according to the ﬁeld and laboratory protocols provided in
Kato et al. (1989): body length to the nearest cm, sex, number and length of fetus, testes weight, number of corpora in both ovaries, thickness of blubber, and stomach contents.
Sexual maturity was examined by standard methods based on ovary and testis examination. Females were determined as sexually mature animals by the presence of at least one corpus albicans or a
corpus luteum in both ovaries.
Sexual maturity in males was determined by histological examination of the testis. Tissues werecollected from the center of the heavier testis by cutting out a 5 mm square sample. After ﬁxation with
10% neutral buﬀered formalin solution, the tissues were sliced to a thickness of 3 µm. Subsequently
they were stained by Eosin Hematoxylin solution and examined under a light microscope with 400×
magniﬁcation scale. Taking account of the timing of samplings, which were conducted outside of thelikely breeding season, sexual maturity was determined by the presence of spermatids in addition tosperm. If there were neither sperm nor spermatids in the seminiferous tubules, size of the open lumen(minor axis) in the seminiferous tubules was considered, as in other studies for balaenopterids (North
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95

96

5.41
6.6
7.01

89/90-199
88/89-014
87/88-273

2.05
2.95
4.66

0.65
0.7
0.85
1
2.25
4.3
5.05
4.2
4
3.79
4.55
5.5
4.45

Male
Male
Male

FemaleFemaleFemaleFemaleFemaleFemaleFemaleFemaleFemaleFemaleFemaleFemaleFemale

Sex

Fish
Fish
Fish

—
Eu
Fish
—
Fish
Fish
Fish
Fish
Fish
—
Fish
Fish
Fish
1
2
1

0
1
1
0
1
1
1
1
1
0
2
1
1
—
—
—

—
S
—
—
—
—
—
—
—
—
—
—
—
F
F
M
F
M
F
M

0
0
0
0
0
1
1
1
1
1
1
1

Age

—
10
21

1
1
3
—
7
98.6
19
111.7
22
119
23
Lost***
10
83.8+**** 17
115
—
169.6
19
102.8
26

Length(cm)

FoetusType Volume Size no. Sex

Stomach contents**: Recorded according to BIWS (Bureau of International Whaling Statistics) format. Eu: Euphasiids.
**: Tp represents age at sexual maturity.
***: Left ovary and foetus lost by harpoon.
****: Ovaries and foetus partly damaged by harpoon.

3.53
3.83
4.29
4.45
5.94
6.61
6.82
6.99
7.02
7.04
7.07
7.17
7.47

Body Body
length weight
(m)
(t)

11

6
6

9
5
11
4
9

Tp

Age and at
its transition
phase (Tp**)

57
195
540

53
182
530

Left Right

Testis wt.
(g)

0
0
10
6
—

0
0
1
1
—

?**** 5+****
1
10
1
4
1
13

0
0

CL+CA

0
0

CL

no. ovulation,
corpus luteum(CL) and
albicans (CA)

Immature
MatureMatureImmature
Immature
Immature
Immature
Immature
MatureMatureMatureMatureMatureMatureMatureMatureSexual status
after present
examination

3.3
3.6
3.7

3.3
3.1
3
3.3
2.4
4.1
4.6
3.7
5.6
4
3.6
5.4
3.1

153
165
201

92
114
115
126
150
204
214
203
192
178
196
214
189

Blubberthickness at
Girth atlateral side umbilicus
below dorsal(cm)
ﬁn (cm)Primary biological information of the sixteen dwarf minke whales which were examined in the present study, listed by order of their body lengths.

92/93-108
90/91-002
89/90-002
88/89-005
88/89-070
90/91-014
90/91-118
88/89-013
88/89-227
92/93-107
89/90-215
92/93-330
90/91-012

SampleNo.

Table 1.

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

Paciﬁc sei whale, Masaki, 1976; Antarctic minke whale, Kato, 1986; Inoue et al., 2014). The measurements on the minor axis of the respective seminiferous tubules using the ocular micrometer weretaken by randomly choosing 25 tubules from the respective samples.
Age was determined by counting growth layers on the bisected core surfaces in earplugs under astereoscopic microscope, as detailed by Lockyer (1984), under the assumption that one growth layer(a pair of pale and dark laminae) was deposited per year, as well as establishing the position of a transition phase in the earplug (Locker, 1972; Kato, 1985).
In addition, external measurements (76 points), were obtained according to the protocol of Kato etal. (1992), and comparison of sexually mature individuals was carried out among 10 dwarf minke, 704
Antarctic minke and 161 North Paciﬁc common minke whales (from the ICR data base for JARPA
and the Japanese Whale Research Program under Special Permit in the North Paciﬁc (JARPN).
Skeletal measurements were compared among dwarf, Antarctic minke and North Paciﬁc common
minke whales. Skeletal measurements (21 points) from eight dwarf minke whales and ﬁve Antarctic
minke whales were made based on the protocol of Omura (1975). For North Paciﬁc common minke
whales, skeletal measurements from Nakamura (2012), which followed the same principal method of
Omura (1975), were used.
To compare biological aspects of the dwarf minke whales with other minke whale species andsub-species, published biological information with equivalent quality was used. Details are given in
the relevant sections.
Sighting information of sampled whales
While sighting information was available from 1987/88 onwards under the JARPA program, for thepresent study, only sightings of the dwarf minke whales sampled from 1987/88 to 1992/93 were used.
All dwarf minke whales sighted and recorded during the shipboard surveys were identiﬁed from theircharacteristic white shoulder/ﬂipper patches, which could be easily observed during closing mode surveys (also see Kato et al., in press).
Table 2.

Sighting information of the dwarf minke whales used in the present study.
Location

Year/Month/
Date sighted

SchoolID no.

Sightingtime

Schoolsize

Estimated
B.L. at sea

Sample no.

1988/3/23

5002

14.47

58

23

S

111

26

E

2

6.8, 6.0

87/88-273

1989/1/13
1989/1/17
1989/1/17
1989/2/4
1989/3/19

8014
5001
8003
5004
1001

14.24
10.27
11.42
8.43
8.13

55
62
62
60
61

22
4
7
38
54

S
S
S
S
S

178
177
177
175
177

10
28
2
7
55

E
E
E
E
E

1
1
1
1
1

5.5
6.2
6.1
5.0
6.0

88/89-005
88/89-013
88/89-014
88/89-070
88/89-227

1989/12/6
1990/1/12
1990/1/15

8004
1001
1002

17.24
7.4
9.41

55
61
60

59
30
59

S
S
S

97
128
116

17
6
6

E
E
E

1
1
1

5.0
6.0
8.3

89/90-002
89/90-199
89/90-215

1990/12/29
1991/1/3
1991/1/3
1991/1/26

1001
1001
5003
8001

6.16
8.13
11.5
9.08

65
61
60
60

4
9
40
34

S
S
S
S

178
175
176
146

12
21
34
49

E
W
W
E

1
1
1
1

4.5
7.0
8.5
7.5

90/91-002
90/91-012
90/91-014
90/91-118

1993/1/10
1993/1/11
1993/3/22

1004
8001
8003

18.00
15.02
15.28

60
60
61

51
31
49

S
S
S

167
166
143

42
5
16

E
E
E

1
1
1

6.5
3.0
6.5

92/93-107
92/93-108
92/93-330

Latitude

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Longitude97

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Results
Sighting position of sampled whales
Table 2 indicates relevant sighting information regarding the dwarf minke whales sampled during
the present study.
Fig. 2 plots the 16 dwarf minke whales sampled based on locations of their sightings during the
JARPA surveys from 1987/88 to 1992/93, and by reproductive category. No speciﬁc diﬀerence inlocation between reproductive categories was observed. In the longitudinal sector, searched between
97°17′E and 173°33′W, dwarf minke whales occurred from 48°42′ to 65°04′S. Most animals (75%;n=12 animals) were seen around latitudes 60° to 62°S, but it should be noted that there was limited
sighting eﬀort north of 60°S. Therefore, this result does not necessarily mean they were rare north of
60°S. Rather, these records should be interpreted to represent the likely southern limit for dwarf minke whale distribution in summer. Within the area surveyed there were three regions of relatively highconcentration: 125°–128°E, 141°–146°E, and 177°–179°E at 60–62°S. These areas were located oﬀ theconcaved continental coastlines of Antarctica such as the Ross Sea.
In terms of segregation from Antarctic minke whales, it is noticeable that dwarf minke whales were
distributed in more northern waters than the Antarctic minke whales in summer (Fig. 1). Sightings ofAntarctic minke whales by JARPA surveys from the early 1990s to the present were distributed southof 60°S with their density much higher from 63°S to the ice edge zone (e.g., Hakamada et al., 2005).
Throughout the surveys of the IDCR/SOWER1 programmes, a total of 54 dwarf minke whales,
comprised of two pairs and 50 singletons, were sighted (Kato et al., in press). These sightings were
only 0.13% of the total number of Antarctic minke whale (B. bonaerensis) sightings (41,854 individuals) made during the same searching eﬀort.
Body size and growthAs summarized in Table 1, the 16 dwarf minke whales collected from 1987/88 to 1992/93 comprised three males and 13 females. The smallest (3.53 m) and largest (7.47 m) individuals were both
females. Of the three males, two were sexually mature and their mean body length was 6.81 m. Of theFig. 2. Sighting locations of the dwarf minke whales sampled during JARPA surveys from 1987/88 to 1992/93
and showing the approximate range of Antarctic minke whale in summer (hatched, with darker area indicating
higher sighting density). Immature male (○), mature male (●), immature female (□), mature female (■).
1
International Whaling Commission International Decade for Cetacean Research (IDCR), Southern Ocean Whale and Ecosystem Research (SOWER).

98

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

13 females, eight individuals were sexually mature with a mean body length of 7.02 m (SD: 0.249).
Of the 16 animals, the age was successfully determined for 13 (two males and 11 females). Resultant age readabilities were 0.67 (2/3) and 0.85 (11/13) for males and females, respectively. The mean
growth curve of the dwarf minke whales together with that of Antarctic minke whales (Zenitani etal., 1997) and North Paciﬁc common minke whales (Maeda, 2012) are shown in Fig. 3 for both sexes.
Female dwarf minke whales appeared to grow to 3.5–3.7 m at age one and then rapidly reach 6 m atage 10, with an asymptote at around 7.0 m (or slightly more) in body length at about age 20.
Fitting the von Bertalanﬀy growth model to the available data produced the following formula forfemale dwarf minke whales:

Lt = 7.16(1 − e( − 0.19 ( t+2.69)) )(1)

where Lt is body length in meters at age (t).
If the asymptotic length from the equation is taken as a proxy for the mean body length at physicalmaturity, then an interim value of 7.16 m for female dwarf minke whales is obtained. Allowing forpossible errors due to the characteristics of the growth formulae used here and the limitations of thedata (especially small sample size among older animals), a comparison with Antarctic minke whales(Zenitani et al., 1997; Bando et al., 2006) and North Paciﬁc common minke whales (Maeda, 2012)
was carried out using von Bertalanﬀy growth formulae as below:
Lt = 9.16(1 − e( − 0.23( t +2.13)) ) Antarctic minke whale – Female(2)

Lt = 8.61(1  e(  0.27 ( t + 2.00 )) ) Antarctic minke whale – Male(3)

Lt = 8.66(1  e(  0.11( t+ 7.60 )) ) North Pacific common minke whale – Female(4)

Lt = 7.49(1  e(  0.41( t + 0.90 )) ) North Pacific common minke whale – Male

(5)

From the above equations as well as from Fig. 3, it is concluded that dwarf minke whales are signiﬁcantly smaller in body length at least in females than both Antarctic minke whales and North Pacific common minke whales throughout all age classes. The mean asymptotic lengths estimated from thegrowth formulae above indicated that fully grown female dwarf minkes were about 2.0 m shorter than
Antarctic minke whales (Zenitani et al., 1997; Bando et al., 2006) and about 1.5 m shorter than North
Paciﬁc common minke whales (Maeda, 2012). Thus far, under the present analysis, those diﬀerenceswere statistically signiﬁcant (t-test; p<0.001).
Due to the small sample size in all age classes, it was not possible to estimate the mean asymptotic

Fig. 3. Plots of body length at age and growth curves of dwarf minke whales by sex (closed circle, dottedline), in comparison with mean growth curves (length at age) of Antarctic minke whales (solid line) from
Zenitani et al. (1997) and of North Paciﬁc common minke whales (broken line) from Maeda (2012). All the
resultant growth curves were ﬁtted by the von Bertalanﬀy growth formulae.
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KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

length or the length at physical maturity of males under the present study.
Under such limitation of the data, an attempt was made to obtain the range of body length at physical maturity for males by using values from other minke whales. The ratios of asymptotic body lengthof males to those of females are 0.94 (8.61/9.16 m) and 0.86 (7.49/8.66 m) in the Antarctic minke
whales and the North Paciﬁc common minke whales, respectively. These ratios were applied to thedwarf minke whales using the value for females (7.16 m), and the values of 6.73 m and 6.16 m wereobtained from the Antarctic minke whales and the North Paciﬁc common minke whales, respectively.
It is considered inappropriate to narrow down these values further given the limitations of the data.
Thus, mean body length at physical maturity for males in the dwarf minke whales is likely to bearound 6.2–6.7 m.
Body length-weight relationship
Two male and 13 female dwarf minke whales were weighed both before and after ﬂensing(Table 3). Whole body weights before ﬂensing varied from 0.650 tons (3.53 m) to 5.50 tons (7.47 m).
For females, the relationship was examined by ﬁtting an exponential regression of whole-body weight
on body length, as follows:

W = 0.01235 L3.007 ( r = 0.9922, n = 13)(6)where W is whole-body weight in tons and L is body length in meters.
The slope of the regression provides an indication of the relative fatness of the animal shape. The
body weight-length relationship for female Antarctic minke whales (Fujise et al., unpublished), obtained through the same procedure as the present study using whole body weight during the feeding
season, was as follows:

W = 0.019304 L2.792 (r = 0.9741, n = 1,113)(7)

The coeﬃcient for the slope (2.792) was signiﬁcantly smaller than that for dwarf minke whales
Table 3. Body weights of dwarf minke whales by weighing their whole body before ﬂensing and in parts after
ﬂensing.
SampleNo.

Body Body
Foetuslength weight* Sex
number(m)(t)

Blubber**

Muscle**

(kg)

(%)

(kg)

(%) (kg) (%) (kg) (%) (kg) (%)

(kg)

(%)

92/93-108
90/91-002
89/90-002
88/89-005
88/89-070
90/91-014
90/91-118
88/89-013
88/89-227
92/93-107
89/90-215
92/93-330
90/91-012

3.53
3.83
4.29
4.45
5.94
6.61
6.82
6.99
7.02
7.04
7.07
7.17
7.47

0.65
0.70
0.85
1.00
2.25
4.30
5.05
4.20
4.00
3.79
4.55
5.50
4.45

F
F
F
F
F
F
F
F
F
F
F
F
F

146
174
212
225
401
967
1,054
950
984
834
975
1,149
957

26.3
25.7
25.8
21.2
19.1
23.0
21.7
21.9
24.9
22.5
22.0
21.3
21.9

234
333
391
599
1,264
2,350
2,816
2,505
2,278
2,142
2,452
3,073
2,378

42.4
49.3
47.4
56.6
60.2
55.9
58.0
57.8
57.7
57.8
55.2
56.9
54.4

552
676
823
1,057
2,098
4,201
4,857
4,331
3,948
3,705
4,442
5,397
4,368

100
100
100
100
100
100
100
100
100
100
100
100
100

89/90-199
88/89-014
87/88-273

5.41
6.60
7.01

2.05
2.95
—

M
M
M

22 1.1 1,952
47 1.6 2,922
26 0.5 4,684

100
100
100

None
None
None
None
None
1
1
1
Lost
1
1
1
1

Bone**

94
92
112
133
277
447
463
403
411
435
478
511
562

17.0
13.7
13.7
12.6
13.2
10.6
9.5
9.3
10.4
11.8
10.8
9.5
12.9

Viscera**

72
68
90
91
150
392
495
401
263
284
454
517
409

399 20.4 1,156 59.2 211 10.8 165
662 22.6 1,652 56.5 327 11.2 234
960 20.5 2,897 61.9 495 10.6 306

Other**

13.0
7 1.3
10.0
9 1.3
11.0 17 2.1
8.6 10 0.9
7.1
6 0.3
9.3 45 1.1
10.2 30 0.6
9.3 73 1.7
6.7 13 0.3
7.7 10 0.3
10.2 84 1.9
9.6 148 2.7
9.4 62 1.4
8.4
8.0
6.5

Total***: Whole body weighted using a large scale before ﬂensing.
**: Percentage ﬁgures are the proportions to the sums of all parts after ﬂensing.

100

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES(3.007), which suggests that dwarf minke whales tended to be stockier than other minke whale types,
despite both being sampled at the peak of their feeding seasons. This is also endorsed by nature in Fig.
6, which indicates proportion to body length of the dwarf minke whales is higher than of other minkes
at the measurement point P17 of girth at umbilicus.
The proportion of the sum of parts to the whole-body weight before ﬂensing ranged from 0.851 to
1.0582 with a mean of 0.973, indicating an average of only 2.7% weight loss during ﬂensing. Muscle
occupies almost half or more of the sum of parts (mean: 54.58%), with the proportion being higher inthe larger animals, while the proportions of blubber (mean: 22.87%) and bone (mean: 11.92%) werehigher among the smaller animals.
Morphology
External appearance in terms of discriminating the dwarf minke whale from other species andsubspecies of minke whales
Previous authors have reported that dwarf minke whales have distinctive external characteristics,
primarily a white shoulder patch. This distinguishes dwarf minke whales from all other types of minke whales at sea (Best, 1985; Arnold et al., 1987, Kato and Fujise, 2000). Additional features havebeen described for dwarf minke whales such as the dark throat patch and a thorax blaze (Arnold etal., 2005).
From ﬁeld examinations during this study, the following three points by which dwarf minke whales
can be easily distinguished from other types of minke whales were identiﬁed (Fig. 4A and additional
images given in Fig. 4B):
Characteristic (a): A dark throat patch usually extends ventrally as a peninsula of pigmentation on

Fig. 4A. Lateral views of diﬀerent types of minke whales scaled down to the same size; upper: dwarf minke
whale (DWM); middle: North Paciﬁc common minke whale (NPM); bottom: Antarctic minke whale (ATM).
Alphabetical symbols in the upper picture correspond to the explanation of characteristics above.
2

It is unlikely that the value exceeds 1.0, which may be due to logistic errors during the measurement.

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101

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Fig. 4B. Variation of shoulder/ﬂipper coloration on the body surface for 15 of the 16 dwarf minke whales
examined in the present study. No photography was taken of 90/91–118 (see also Table 2).

the ventral grooves restricted to the region between the ﬂipper insertion and the angle of the gape. In
the samples for the present study, this dark patch was symmetrically arranged on both sides.
Characteristic (b): Fig. 4B shows the variation in shoulder/ﬂipper pigmentation among the 16 specimens. Best (1985) reported that dwarf minke whales have an entire white patch on the shoulder/ﬂipper
regions. On the other hand, Arnold et al. (1987) found an elongated dark oval patch within it and hidden
when the ﬂipper is held against the body, which they called the “ﬂipper oval.” However, there is muchvariation in this pattern as illustrated in Fig. 4B. The ﬂipper ovals certainly existed in their approximate
position in all specimens, but the ‘arch like white bands’ surrounding the dorsal margin of the ﬂipper
oval were sometimes incomplete so that the white patch on the shoulder region was cut into two in all
but one case. Only one animal (90/91–118) had a complete white patch above the ﬂipper oval on theshoulder region. Unfortunately, no photograph was available in Fig. 4B for this animal.
Characteristic (c): The thorax blaze/patches were principally located above the white patch on the102

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

ﬂippers, usually in a somewhat triangular shape. As in Fig. 4B, there were some variations in the pattern of connection between the ﬂipper oval and the thorax blaze/patches being totally connected or
separated by splashed pigmentations.
The present study conﬁrmed the three characteristics noted above as consistent keys to distinguishing dwarf minke whales from other minke whales (Fig. 4A). In addition, the present samples provided
some additional information on blowhole streaks, which Best (1985) reported in a small dwarf minke
whale (about 4 m) from South Africa but were not seen in any dwarf minke whales oﬀ Australia (Arnold et al., 1987, 2005). In the specimens examined in the present study, the blowhole streaks wereabsent or obscure. However, all of the six fetuses larger than 98.6 cm listed in Table 1 had very distinctive parallel streaks in the posterior region of the blowhole. This may indicate changes in coloration
with respect to age that is more distinct in younger stages, or possibly more visible in living animals
or when underwater (Arnold et al., 2005).
Baleen plate coloration
Fig. 5 (A and B) shows a typical baleen plate coloration of dwarf minke whales, which was sharedby all the specimens in the present study. As both Best (1985) and Arnold et al. (1987) noted, the outside view of the baleen plate series is two-tone, being creamy white anteriorly and dark gray or brown
posteriorly. The darker coloration in the posterior portion of the series is due to a thin dark outer border of the plates. As in Fig. 5(B), this baleen plate coloration is diﬀerent from the other minke whales.
The external view of the baleen plate series of Antarctic minke whales is predominantly black on theleft side and creamy white in 1/3 of the anterior portion and black in 2/3 of the posterior portion on theright side while it is usually entirely creamy white for North Paciﬁc common minke whales (though
there are rare cases where animals have plates with a thin dark outer border in the posterior parts ofthe series). Thus, it is evident that the dark outer border is much wider in Antarctic minke whales thanin dwarf minke whales (Best, 1985).
Kato et al. (1992) suggested that the occurrence of a dark outer border to the baleen had some
growth-speciﬁc nature in North Paciﬁc common minke whales, therefore the proportion of anterior
creamy white plates and posterior black outer margined plate in dwarf minke whales was examined.
According to similar statistics (Table 4), the length of the creamy white portion varied from 24 to
115 cm (mean: 67.29, SD: 21.15) and 28–94 cm (mean: 63.21, SD: 16.98) on right and left sides respectively, or 31–85% (mean 53, SD: 13) and 36–85% (mean: 50, SD: 12) of the total length of thebaleen plate series, respectively. The ratio of right side to the left side was 1.06 (SD: 0.13), thus thecreamy white portion of the right side was slightly longer than that of the left, but not signiﬁcantly so.
As to growth speciﬁc changes in proportion of the plates having black outer margin, the samples were
not clear enough for detecting such nature.
In summary, the external view of a baleen plate series of dwarf minke whales is mostly bilaterally
symmetrical in coloration with a creamy white anterior portion that extends for almost half of the en-

Fig. 5. A: Lateral view of left side of dwarf minke whale head showing baleen plates exposed in its slightly
opened mouth. B: Labial view of the baleen plate series removed from both sides of the upper jaw.
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Table 4. Baleen plate series of the dwarf minke whales having measured data, especially the proportion of baleenseries of the plate with creamy white coloured outer margin to the total length of baleen. See also Fig. 5B.
Baleen plate series, length (cm) at outer margin

Sample no.

Samplingdate

Body
length(cm)

Sex

87/88-273
88/89-005
88/89-013
88/89-014
88/89-070
88/89-227
89/90-002
89/90-199
89/90-215
90/91-002
90/91-012
90/91-014
92/93-118
92/93-107

1988/3/23
1989/1/13
1989/1/17
1989/1/17
1989/2/4
1989/3/19
1989/12/6
1990/1/12
1990/1/15
1990/12/29
1991/1/3
1991/1/3
1991/1/26
1993/1/10

701
445
699
66
594
702
429
541
707
383
747
661
682
704

Male
FemaleFemaleMale
FemaleFemaleFemaleMale
FemaleFemaleFemaleFemaleFemaleFemale% of Right sideof creamy
white margin
creamycreamyTotal
R (w/t)* Total
L (w/t)* R (w/t)/L (w/t)
white
white
Right side series

Left side series

145 7288 41
147 65
134 45
118 73148 7986 73
112 60152 8677 24
163 115142 83
139 65
135 61

0.50
0.47
0.44
0.34
0.62
0.53
0.85
0.54
0.57
0.31
0.71
0.58
0.47
0.45

142
89
148
130
118
148
86
112
152
78
166
141
139
135

72
37
78
48
71
71
73
59
76
28
94
70
51
57

0.51
0.42
0.53
0.37
0.60
0.48
0.85
0.53
0.50
0.36
0.57
0.50
0.37
0.42

0.98
1.12
0.84
0.91
1.03
1.11
1.00
1.02
1.13
0.87
1.25
1.18
1.27
1.07

Mean 67.29
S.D. 21.15

0.53
0.13

S.D.

63.21
16.98

0.50
0.12

1.06
0.13

*: Proportion of creamy white length per total length of baleen plate row in each side.

tire length of the baleen plates. With this characteristic, they diﬀer from both Antarctic minke whales(bilaterally asymmetric baleen coloration) and North Paciﬁc common minke whales (usually all
creamy white baleen). In comparison, dwarf minke whales have an intermediate coloration.
External body proportion
Prior to the statistical analyses, the general characteristics of the external body proportions of dwarf
minke whales were examined in comparison with Antarctic minke whales (n=507) and North Paciﬁc
common minke whales (n=91). Fig. 6 shows the body proportions (expressed as a percentage of the
body length from tip of snout to notch of tail ﬂukes) for dwarf minke whales, Antarctic minke whales
and North Paciﬁc common minke whales. The rostrum of the dwarf minke whale is elongated in a
V shape, typical of minke whales. On average the head (P19) comprised 22.90% (min. 21.20–max.
24.10) of the body length. The average length from the tip of snout to the center of the blowhole (P2)comprised 14.50% (12.80–15.60); to the center of the eye (P3) 17.60% (15.50–17.60); and to the external auditory meatus (P4) 22.70% (20.20–24.10) of the body length. The average length from the tipof snout to the posterior end of the ventral grooves (P6) comprised 51.00% (49.10–53.10), to the umbilicus (P7) 54.90% (53.10–56.00), the center of the genital aperture (P8) 71.00% (67.00–72.60), andto the anus (P9) 74.80% (73.80–75.70) of the body length.
The pectoral ﬁn is also an elongated oval shape with tapering tip typical of balaenopterids and its
length (P12, tip to anterior insertion) and breadth (P14) were 16.10% (15.00–17.50) and 4.10% (3.60–
4.30), respectively. The dorsal ﬁn is falcate with a tapering tip of which the height (P11) was 4.30%(3.30–4.30). The tail ﬂukes are leaf-like in shape with a rather straight posterior margin and tapering
tips at both ends, while their width (P16) was relatively broad at 28.10% (24.90–31.10) and depth(P15) was 7.00% (6.40–7.50).

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Fig. 6. Mean external measurements (P2–P20) of sexually mature dwarf (closed circle), Antarctic (open circle)
and North Paciﬁc minke whales (gray colored circle), expressed as respective proportion to the body length.
Abbreviations of respective measurement points correspond to the numbered locations in the illustration.

All the body proportion measurements in the anterior half of the body were highest for Antarctic
minke whales and lowest for North Paciﬁc common minke whales, with dwarf minke whales being
intermediate between the two but somewhat closer to Antarctic minke whales. On the other hand, therelative proportions of the appendages were remarkably close to each other among the three types ofminke whales. Those aspects are further examined by statistical analyses in the later section.
Skeletal features
Skeletal observations were taken from all 16 animals collected, but data from eight sexually mature
animals were to be the base for the present analyses especially on skull, to minimize possible growthdependent changes. Those observations were appropriately compared and veriﬁed with other type ofminke whales in some cases.
1. SkullFirstly, before the statistical analyses, general aspects of the skeleton are presented in this section.
See also details of the skeleton in Appendix 1.
Fig. 7 shows the dorsal view of the skull of a dwarf minke whale as compared to those of North
Paciﬁc common minke whales and Antarctic minke whales. The diagnostic diﬀerences in skull morCetacean Popul. Stud. (CPOPS), Full paper
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Fig. 7. Dorsal view of skulls by photographing (upper) and corresponding contour drawings (bottom) of thedwarf (a: 87/88-273), the North Paciﬁc (b: 08NPCK-M030) and the Antarctic minke whale (c: 93/94-AM287)
showing the principal diﬀerences in morphology among the three diﬀerent types of minke whales of whichwere fully grown animals. The attached bar on the photos is 1.0 m long with a 10 cm scale interval.

phology can be seen among them. As an example of the skeletal specimens, multidimensional viewsof the entire skeleton, including skull and other skeletal parts of a male dwarf minke whale of 7.10 m
in body length registered as specimen MTUM-DW273, are shown in Appendix 1. Details of the skull
measurements are given in Appendix 2.
The vertex of the skull is considered an important taxonomic trait. A distinct interparietal bone
was present in dwarf minke whales (Arnold et al., 1987; Kato and Fujise, 2000). This characteristic
has been identiﬁed in North Paciﬁc common minke whales and in Antarctic minke whales (Nakamura, 2012). Further, the presence of the interparietal in the vertex has also been identiﬁed in North
Atlantic minke whales (Fig. 8). In dwarf minke whales, the posterior end of the nasal bone and theposterior end of the premaxilla are more extended toward the vertex compared with those of North Paciﬁc common minke whales. As a result, the nasal bone of dwarf minke whales is more elongated thanin North Paciﬁc common minke whales, resulting in a signiﬁcantly larger ratio of the length of thenasal bone relative to the anterior width of the nasal bone. In dwarf minke whales, proportional lengthof maxilla and premaxilla to the skull were signiﬁcantly larger than those in North Paciﬁc common
minke whales. On the other hand, the width of the orbit, width and height of the occipital condyle, andthe length and width of the palatine relative to the skull length were all smaller than in North Paciﬁc
common minke whales.
In terms of absolute measurement values, the maximum length and maximum width of the tympanic bullae of dwarf minke whales (7.9±0.3 cm and 6.1±0.2 cm, respectively) were approximately 10%
smaller than in North Paciﬁc common minke whales (9.0±0.4 cm and 6.9±0.3 cm, respectively) andAntarctic minke whales (9.2±0.6 cm and 7.1±0.3 cm, respectively), whereas their maximum width
was close to North Atlantic common minke whales (8.2±0.2 cm).

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Fig. 8. Morphological comparison of the vertex region on the skulls among dwarf, North Paciﬁc, North Atlantic common minke whales and the Antarctic minke whales. Abbreviations represent: Fr, frontal; Int, interparietal; Ma, ascending process of maxilla; Na, nasal; Pa, parietal; Pm, premaxilla.

Fig. 9. Lateral view of mounted complete skeleton of the dwarf minke whale (museum specimen No. MTUM
DW273; ﬁeld sample ID No. 87/88-273). The specimen was mounted under supervision by Kato and is displayed at the Museum of Marine Science, Tokyo University of Marine Science and Technology, Tokyo.

An entire lateral view of the dwarf minke whale skeleton (87/88-273) is shown in Fig. 9.
2. Vertebral number
The total number of vertebrae in the dwarf minke whales examined ranged from 47 to 50 with amean of 48.6 (SD: 0.9). The ranges were 47–51 with a mean of 49 (SD: 0.9) and 47–51 with a meanof 48.8 (SD: 0.80) in Antarctic minke whales and North Paciﬁc common minke whales, respectively.
Thus, the total number of vertebrae is virtually identical in all three minke whale species or sub-species(Table 5).
The vertebral formula for the dwarf minke whale was C7＋D10–11＋L11–14＋Ca18–20=47–50,
and for the mean values C7＋D10.6＋L11.7＋Ca19.2=48.6 (SD: 0.9). Again, this formation is thesame, or within the known range, to those of other minke whale species and sub-species.

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Table 5. Mean and range of number of vertebrae in each section of the vertebral colum by diﬀerent type ofminke whales.
Dwarf (n=16)

Antarctic (n=42)

North Paciﬁc (n=200) North Atlantic (n=1)

Cervical (C)
Mean
SD
Range

7
0
7

7
0
7

7
0
7

7
0
7

Dorsal (D)
Mean
SD
Range

10.6
0.5
10–11

10.7
0.5
10–12

10.5
0.5
10–11

11
0
11

Lumbar (L)
Mean
SD
Range

11.7
0.9
11–14

11.8
0.8
10–14

12.1
0.6
11–13

12
0
12

Caudal (Ca)
Mean
SD
Range

19.2
0.8
18–20

19.4
0.9
17–22

19.3
0.8
17–23

18
0
18

Total
Mean
SD
Range

48.6
0.9
47–50

49.0
0.9
47–51

48.8
0.8
47–51

48
0
48

3. Number of ribs
For the dwarf minke whales examined, the ribs are relatively thin and broad, and their numbers are
10–11 on each side, with the mean number of ribs being identical on each side as 10.7 (SD: 0.48).
These are slightly fewer than in the Antarctic minke whales (10–12, mean 11.1 (SD: 0.45)) and North
Paciﬁc common minke whale (10–12, mean 10.8 (SD: 0.4)), but not signiﬁcantly so. No ﬂoating rib
was found among the present specimens of dwarf minke whales.
4. Shape of sternum
Three types of sternum shape are observed in species and sub-species of minke whales: Y-shape(looks like a ginkgo leaf), T-shape and an intermediate shape (Fig. 10). The T-shape sternum is common among dwarf minke whales, Antarctic minke whales and North Paciﬁc common minke whales;
the manubrium parts were rather larger in the North Paciﬁc common minke whales. The Y-shape wasonly conﬁrmed in dwarf minke whales with the presence of a hole in the center of the sternum in somewhales. The Y-shape sternum is likely to be rare among balaenopterids and is possibly exhibited onlyin dwarf minke whales and must be closely related to the shape of the associated ribs. This characteristic may suggest some diﬀerences in feeding behavior, but more samples and further examinations
are required to conﬁrm this.
Life history parameters
Females
1. Reproductive status
While ovaries were unfortunately lost from the three females, six of the 13 females of dwarf minke whales were ﬁrstly conﬁrmed to be sexually mature and four were conﬁrmed as immature based

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Fig. 10. Variations in shape of the sternum among dwarf, Antarctic and North Paciﬁc common minke whales
based on contours of the actual sternums in each type of minke whale.

on gonad examination. Of the remaining three females one (88/89-013) was to be mature because of
having a fetus, another (88/89-227) was thought to be mature given its size (7.02 m) and age (10 years
old) as well as the presence of a transition phase as a mark of attainment of sexual maturity in the earplug, and the third (89/90-002) likely to be immature from its size (4.29 m) and age (3 years old), assummarized in Table 1. Resultant sexual status of the present samples was ﬁve sexually immature versus eight mature. All sexually mature females excepting one missing the uterine horns were conﬁrmed
to be pregnant, apparently indicating a 100% pregnancy rate. This ﬁgure should be, however, treatedwith caution because of the small sample size and possible segregation or timings of migration associated with reproduction.
The transition phase in the earplug was used as an indicator of age at sexual maturity while an annual rate of growth layer deposition was assumed (Lockyer, 1972; Kato, 1982). The mean annual ovulation rate after attainment of sexual maturity was estimated as follows:
no. corpora /(total age – transition phase)(8)

Values from four females having both transition phase and number of corpora ranged from 0.31 to
1.00 with a mean of 0.58, which are understood to be annual ovulation rate leading to maximum value of annual pregnancy rate. This result suggests that the apparent 100% pregnancy rate might be toohigh as an annua1 pregnancy rate (true pregnancy rate) and this high value was possibly due to reproductive segregation in relation to latitude, i.e., pregnant females migrate further south as in the case of
Antarctic minke whales (Masaki, 1979; Kato, 1982).
None of the mature females was lactating, but possible milk remnants consisting of transparent yellowish liquid were found in the mammary gland of one female (sample ID number: 92/93-107), suggesting this animal was sampled just after weaning her calf.
2. Fetus and breeding season
The sex ratio in the fetus samples was 3 males to 4 females, and the mean litter size was 1.0 (n=7).
The lengths of the fetuses were relatively similar, ranging from 98.6 to 119 cm with one at 169.6 cm(Table 6).
To investigate the timing and duration of the breeding season, conception dates were estimated byback-calculating from fetus length and date of capture, and applying the fetal growth rate formula for
Antarctic minke whales (Kato and Miyashita, 1991; Kato, 1995), as follows:t = 1.622 L0.892 + 74

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Table 6. Estimated conception date for the pregnant dwarf minke whales based on back-calculating by thefetal growth curve estimated by Kato (1995).
SeasonSpecimen no.

Date

Fetal length (cm)

90/91
90/91
92/93
89/90
88/89
90/91
92/93

012
014
107
215
013
118
330

3 Jan, 1991
3 Jan, 1991
10 Jan, 1993
15 Jan, 1990
17 Jan, 1989
26 Jan, 1991
22 Mar, 1993

102.8
98.6
84.0
115.0
119.0
111.7
169.6

Days after concept. Estimated concept. date*
175
171
158
186
189
183
232

13 Jul, 1990
17 Jul, 1990
6 Aug, 1992
14 Jul, 1989
13 Jul, 1988
28 Jul, 1990
3 Aug, 1992*: Mean=22 July.

where t is time (days) passed since conception and L is fetal body length in cm (Table 6).
Estimated conception dates were concentrated in a very narrow band from the middle of July to early August, that is, over a 25-day period. Thus, provided that southbound migration is not dependent on
reproductive segregation, even with the small sample size, it appears that the breeding season of thedwarf minke whale likely occurs over a few weeks in mid-winter with a peak in middle to late July.
This contrasts with the case of Antarctic minke whales where the breeding season extends over six
months with a weak peak in September/October (Kato, 1995).
3. Body Length and age at sexual maturity
With the present small sample size, it was diﬃcult to estimate lengths or ages at sexual maturity
with accuracy, especially for males.
For females, the smallest mature individual was 6.61 m and the largest immature individual was
5.94 m in length (Table 1), from which body length at sexual maturity is likely to be around these values or around 6.0–6.5 m. In a separate study, Kato (1987) examined the density dependent nature of
temporal changes for parameters related to sexual maturity in Antarctic minke whales and concluded
that the length at sexual maturity remained constant over time, while age at sexual maturity declinedwith density dependence. Thus, length at sexual maturity is a reliable threshold parameter for speciesor subspecies-speciﬁc sexual maturity. For other minke whales, estimates are:
North Paciﬁc common minke whales, female, 7.1 m (Kato, 1992),
North Atlantic common minke whales, female, 7.1–7.5 m (Jonsgard, 1951; Christensen, 1981;
Larsen and Kaple, 1982),
Antarctic minke whales, female, 8.1 m (Best, 1982; Kato, 1982; Zenitani et al., 1997; Bando etal., 2006).
In females, values for dwarf minke whales were much smaller (approximately 1.0–2.0 m smaller)
than the those for Antarctic and North Paciﬁc common minke whales.
The age of the youngest sexually mature female was 10 years and that of the oldest immature female was 7 years. Therefore, their average age at sexual maturity is likely in the range of 7–10 years(Table 1). This result is consistent with the age at sexual maturity estimated from the transition phase(Table 1), which was 4–11 years with a mean of 7.14 years (SD: 1.05).
4. Maximum life span
The oldest whale in the sample was a 26-year-old female (Table 1). This is most likely to be anunder-estimate of longevity due to the small sample size. This parameter can be estimated using theequation of Ohsumi (1979) which was derived from ﬁtting both baleen and toothed whales as below:

T = 31.277e0.05480 L

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where T is maximum life span in years and L is body length at physical maturity in meters.
The above equation was applied to the estimated length at physical maturity (asymptotic length forfemales, 7.16 m) in the present study to estimate the approximate value of the maximum life span. The
result was 47 years. This is not so diﬀerent from those of other minke whale species and sub-species
derived from the same equation, e.g., 50 years for the Antarctic minke whale and 48 years for the
North Paciﬁc common minke whale. It is emphasized here that this is an interim value.
Males
It was diﬃcult to estimate any life history parameters in males because of the limited number of
specimens (Table 1). It was considered that the 5.41 m dwarf minke whale with testes weighing 53
and 57 g was an immature animal. The other two whales, a 7.01 m male (age 21) with testes weighing
530 and 540 g (hereafter 87/88–273) and a 6.6 m male (age 10) with testes of 182 and 195 g (hereafter
88/89-014) were presumed to be mature animals. For these two cases, additional analyses based on
histological examinations of the testes were conducted.
Histological sections for those testes are shown in Fig. 11. It was conﬁrmed that numerous spermatocytes were present in most of the seminiferous tubules of both males, but no sperm was present
in both males. The reason why there were no sperm among almost all of the seminiferous tubules is
not a surprising event even for fully sexually mature males. It is thought to be due to timing of thesamplings of the testes (January to March which did not overlap with the likely breeding season in
July–August inferred from conception timing calculated backward from the fetus frequencies in theabove section.
However, it was further noted that some spermatids existed in the seminiferous tubules of the larger male. Some examples of these are shown by the arrows in Fig. 11(B). This suggests the male wasFig. 11. Histological section images of the seminiferous tubules for the males examined. Bars in all three images represent 100 μm. A: large male (87/88-273), body length 7.01 m and age 21 years. B: magniﬁed view of
the 87/88-273 seminiferous tubules indicating spermatids with arrows. C: the second large male (88/89-014)
whose body length was 6.60 m and age 6 years.
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KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BESTin a somewhat sexually active status even if out of the main breeding season. Thus, the larger male
(87/88-273) was deﬁnitely a mature animal. For the second larger male (88/89-014), spermatids could
not be conﬁrmed in any of its seminiferous tubules during the present microscopic observation.
Another measure of male sexual maturity was the size of the seminiferous tubules. Masaki (1976)
examined the diameter (minor axis) of seminiferous tubules in sei whales and found signiﬁcant correlation in relation to sexual maturity. Kato (1986) also found a similar relationship between the diameter and sexual maturity in Antarctic minke whales. The threshold value for sexual maturity was
mostly 100 μm. Inoue et al. (2018) examined the minor axis of the seminiferous tubules in North
Paciﬁc common minke whales and found that over 100 μm would be enough to determine sexual
maturity even when the samples were collected in the non-breeding season. According to the present
measurement of seminiferous tubules, those were 177.6 μm (n=25, SD: 29.49) and 124.4 μm (n=25,
SD: 13.71) for the larger male (87/88-273) and the second larger male (88/89-014) respectively. They
were wider than the threshold value of 100 μm of sexual maturity in other minke whale types even in
non-breeding season. Another measure for sexual maturity in males is the presence of the open lumen
within the respective seminiferous tubules. Masaki (1976) reported that the presence of the open lumen could be used as a criterion for sexual maturity in North Paciﬁc sei whales. In our analyses, asevident in Fig. 11(B), the open lumen can be seen in the majority of the seminiferous tubules for thetwo males.
From the above examinations, it can be conﬁrmed that the two large males (87/88-273, 88/89-014)
were sexually mature.
Food and feeding habits
The stomach contents of 16 dwarf minke whales were examined. 13 individuals contained food,
while the remainder were empty or contained only traces of food (Table 7).
Table 7. Stomach contents, weights and prey species eaten by dwarf minke whales in relation to sampling
location and time.
Location
Sample no.
87/88-273
88/89-005
88/89-013
88/89-014
88/89-070
88/89-227
89/90-002
89/90-199
89/90-215
90/91-002
90/91-012
90/91-014
90/91-118
92/93-107
92/93-108
92/93-330

Latitude
58
55
62
62
60
61
55
61
60
65
61
60
60
60
60
61

23
22
4
7
38
54
59
30
59
4
9
40
34
51
31
49

Longitude
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S
S

111
178
177
177
175
177
97
128
116
178
175
176
146
167
166
143

26
10
28
2
7
55
17
6
6
12
21
34
49
42
5
16

E
E
E
E
E
E
E
E
E
E
W
W
E
E
E
E

BIWS stomach record Content
Sampling
Prey species
weight in
Relativetime
identiﬁed
Item
Size
kg**
richness*
15.24
14.55
10.54
12.50
9.00
8.40
18.23
9.20
10.51
7.29
8.38
12.36
9.43
18.26
16.16
15.53

Fish
—
Fish
Fish
Fish
Fish
Fish
Fish
Fish
Eu
Fish
Fish
Fish
—
—
Fish

1
0
1
2
1
1
1
1
2
1
1
1
1
0
0
1

—
—
—
—
—
—
—
—
—
small
—
—
—
—
—
—

22.7
4.9
38.3
33.9
5.6
6.8
15.6
14.0
47.3
3.4
29.1
20.7
2.6
0.0
2.5
35.7

Myctophidae
Myctophidae
Myctophidae
Myctophidae
Myctophidae
Myctophidae
Myctophidae
Myctophidae
Euphausiids
Myctophidae
Myctophidae
Myctophidae

Kreﬀtichthys
anderssoni*: Relative richness by the BIWS format: 0, empty; 1, 25%; 2, 26–50%; 3, 51–75%; 4, 76–100%.
**: Combined value for the ﬁrst (fore) and second (main) stomachs.

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

Stomach contents weighed between 2.6 kg and 47.3 kg (n=13) and the contents were partially digested. The species composition of the contents was mainly uniform within each stomach, thus thefood in the stomachs would have been representative of food organisms typically consumed by dwarf
minke whales.
Sampling locations were spread out latitudinally and longitudinally. Except for one sampled further
north from the Antarctic Convergence (with empty stomach), the majority of dwarf minke whales
were sampled in the vicinity of the Antarctic convergence (58–62°S). The species identiﬁcation offood organisms was referred to Mr. Hiromasa Furuhashi (Hokkaido University) a specialist of morphology and taxonomy of myctophid ﬁsh. Observations were made by placing the photophore patternover the ﬁsh body surface, a method which is widely used for species identiﬁcation of myctophid ﬁshes. The specialist inferred that there were remnants of myctophids, including Kreﬀtichthys anderssoni.
This clariﬁed that these dwarf minke whales fed mainly on small ﬁsh in the vicinity of the Antarctic
Convergence.
On the other hand, euphausiids (probably Euphausia superba) were found in the stomach of one
dwarf minke whale sampled at 65°S, which is further south of the Antarctic Convergence and where
dwarf minke whales are known not commonly occur (Kato et al., in press). Euphausiids such as E.
superba are known to be abundant in this region. Thus, it cannot be automatically determined that the
dwarf minke whale is a ﬁsh-feeder. It appears that the dwarf minke whale is more of an opportunistic
feeder and utilizes organisms which are available in abundance as food.
From the above, it can be summarized that dwarf minke whales feed mainly on small gregarious
ﬁsh species such as myctophids in their normal summer habitat, while dwarf minke whales in lower
latitudes oﬀ Brazil feed on euphausiids (Secchi et al., 2003) on an opportunistic basis.
Morphometric analysis
External body proportions
A total of 21 external measurements collected from 16 dwarf minke whales were compared statistically with those from 507 Antarctic minke whales and 91 North Paciﬁc common minke whales. All
measurements were log-transformed prior to the analysis.
The morphometric comparison for the three species and sub-species of minke whales was carriedout using three methods. The ﬁrst was the analysis of covariance (ANCOV). This assumes that theallometric relationship between body length (V01) and each of the remaining measurements holds
irrespective of age, while body length was used as a covariate to the other measurements (Jover, 1992;
Tanaka and Tarumi, 1986). Secondly, measurements showing no signiﬁcant regression with bodylength were also used for the multivariate analysis of variance (MANOVA) (Jover, 1992; Tanaka etal., 1990). The third method was the canonical discriminant analysis (DA) using component scoresfrom a principal component analysis (PCA) (Tanaka et al., 1984a, 1984b; Christensen et al., 1990).
To evaluate morphometric diﬀerences between males and females, 14 measurements of the dwarf
minke whales were analyzed using MANOVA, and a signiﬁcant diﬀerence (Wilks’ Λ=0.17026,
p<0.01) was detected. ANCOV was also carried out using 20 measurements (V02-V09, V11-V20 and
V31-V32) of the dwarf minke whales with body length as a covariate. The analysis indicated no sexual diﬀerence except for one characteristic (V08: from tip of snout to sexual aperture), which is known
to be sexually dimorphic.
To evaluate diﬀerences in external body proportion for dwarf minke whales, Antarctic minke
whales and North Paciﬁc common minke whales, MANOVA was carried out using the 14 measurements, and a signiﬁcant diﬀerence was detected (females: Wilks’ Λ=0.17026, p<0.01; males: Wilks’Λ=0.24714, p<0.01). ANCOV was conducted using 20 measurements from females. The analysis
revealed that 14 of the measurements were signiﬁcantly correlated with body length (Table 8) whilesome of the measurements diﬀered signiﬁcantly in that dwarf minke whales showed larger values in
the posterior parts of the body (V08 and V09), ﬂipper, and dorsal ﬁn (V11 and V12). Antarctic minke
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113

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Table 8. Results of ANCOV of body proportion with body length (V01) as a covariate for three types of minke whale: dwarf (DWM), Antarctic (ATM) and North Paciﬁc (NPM) minke whales. Upper, for female; bottom for male.
FemaleSample size

V02
V03
V04
V05
V06*
V07*
V08
V09
V11
V12
V13*
V14*
V15
V16
V17*
V18*
V19
V20
V31
V32

Estimated value at mean covariate with 95% CF

DWM

ATM

NPM

n

n

n

13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
13
11
12

270
270
268
257
270
269
267
270
259
264
267
269
270
266
270
270
265
264
216
247

40
34
9
40
33
33
18
43
30
36
18
33
25
21
29
14
17

Result of
ANCOV
p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01
P<0.01p<0.01p<0.01p<0.01p<0.01p<0.05p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.05

DWM

ATM

NPM

Mean+95%

Mean+95%

Mean+95%

4.732+0.035
4.940+0.031
5.188+0.023
5.856+0.018

4.761+0.007
5.024+0.006
5.258+0.005
5.866+0.004

4.665+0.020
4.847+0.018
5.113+0.027
5.795+0.010

6.345+0.009
6.369+0.008
3.461+0.067
4.850+0.051

6.328+0.002
6.357+0.002
3.362+0.014
4.732+0.011

6.311+0.007
6.348+0.005
3.402+0.042
4.681+0.029

4.038+0.043
5.405+0.039

4.052+0.009
5.384+0.008

4.013+0.029
5.440+0.029

5.192+0.022
4.607+0.025
5.128+0.027
5.120+0.035

5.243+0.005
4.635+0.005
5.169+0.006
5.164+0.007

5.084+0.022
4.460+0.023

Male
Sample size

V02
V03
V04
V05
V06
V07*
V08
V09
V11
V12
V13*
V14
V15
V16
V17
V18*
V19
V20
V31
V32

Estimated value at mean covariate with 95% CF
Result of
ANCOV

DWM

ATM

NPM

n

n

n

3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3

236
235
233
229
237
237
237
237
229
231
232
235
237
236
237
237
236
233
199
218

48
41
15
45
36
36
30
48
40
41
9
41
40
33

p<0.0144
19
20

p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.01p<0.05p<0.01p<0.01p<0.01

DWM

ATM

NPM

Mean+95%

Mean+95%

Mean+95%

4.723+0.082
4.931+0.055
5.170+0.042
5.837+0.043
5.969+0.041

4.725+0.009
4.986+0.006
5.220+0.005
5.832+0.005
5.955+0.005

4.654+0.021
4.859+0.015
5.072+0.021
5.758+0.012
5.857+0.012

6.266+0.019
6.352+0.016
3.525+0.134
4.849+0.078

6.253+0.002
6.344+0.002
3.370+0.015
4.728+0.009

6.255+0.006
6.335+0.004
3.411+0.038
4.774+0.022

3.450+0.063
3.973+0.075
5.382+0.068
5.327+0.066

3.330+0.007
4.012+0.008
5.365+0.008
5.334+0.007

3.360+0.018
3.994+0.022
5.412+0.021

5.156+0.041
4.572+0.048
5.098+0.043
5.095+0.045

5.210+0.005
4.613+0.005
5.136+0.005
5.138+0.005

5.078+0.018
4.401+0.021*：As the results showed no correlation with body length as a covariate, a multivariated analysis of variance was adopted.

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

whales showed larger values in measurements related to head proportion (V03, V04, V19, V31, V32).
North Paciﬁc common minke whales showed wider ﬂukes (V16). In spite of the small sample size,
similar results were observed for males (Table 8).
The result of PCA showed that the ﬁrst Principal Component (PC1) is related to growth, with apositive value observed for all variables. The PC2 seems to be correlated to body appendages such as
ﬂipper, dorsal ﬁn, and ﬂukes. The values were positive for girth (V11) and ﬂukes (V15 and V16) while
negative values were observed in anterior parts of the body (from V02 to V09). Principal componentscores from PCA were examined using the canonical discriminant analysis (DA). Eigenvalues andeigenvectors derived from DA are shown in Table 9 by each canonical variate (CAN) with and without PC1. Plots of the ﬁrst two variates are shown in Fig. 12 for both sexes. For males, irrespective ofwhether PC1 was included or not, the three forms are visibly separate from each other. These results
indicate signiﬁcant diﬀerences in external morphology among the three types of minke whale.
Skull measurements
1. ANCOV analyses
Comparative skull morphology analyses were carried out based on 76 skull measurements from
15 dwarf minke whales, 33 Antarctic minke whales, 27 North Atlantic common minke whales and 29
North Paciﬁc common minke whales. The measurements were log-transformed prior to the analyses.
Because of the small sample size, the analysis was conducted by combining data of both sexes.
The same methods of analysis as those for external morphometry were conducted: MANOVA,ANCOV, PCA, and DA. In ANCOV, condylo-premaxillary length (SK01) was used as the covariate.
Table 10 shows the results of ANCOV. Fifty-nine measurements indicated a signiﬁcant regression
with the SK01. Of these, 46 were signiﬁcantly diﬀerent among the four species and sub-species ofminke whales. For ﬁve measurements (indicated by ** in Table 10) that had no signiﬁcant slope in the
regression line taking the SK01 as a covariate, MANOVA were applied instead of ANCOV, indicating that measurements related to rostrum (SK03, SK05, SK06, SK07, SK08, SK09, SK19, SK21) are
Table 9. Eigenvectors and eigenvalues derived from the canonical discriminant analysis using the PC scoresof PCA for each sex.
FemalePrincipal
Component
PC1
PC2
PC3
PC4
PC5
PC6
PC7
PC8
PC9
PC10
PC11
PC12
PC13
PC14
EigenvalueMale
PC1-PC14
CAN1

CAN2

PC2-PC14
CAN1

CAN2

−1.0647 1.0367
5.8434 −1.8680 4.5469
3.9497
14.1278 −0.6006 12.4648
5.69951.7539 6.3519 3.9619 −5.6118
4.9272 3.2111 5.6326 −1.3752−4.7839 −4.6171 −6.0319
2.8102−2.0632 0.9634 −1.4914 −1.6930
1.0791 −8.8291 −2.3480
9.071915.2995 3.0035 14.8688
2.573216.0063 28.5834 25.1179 −22.3201
14.2007 13.2371 17.7122 −7.9283
11.7966 21.5350 18.7129 −16.8394−13.6419 35.3312 1.0133 −39.6776−12.6909 15.0742 −5.6906 −19.3782
2.08100.90491.6351

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Principal
Component
PC1
PC2
PC3
PC4
PC5
PC6
PC7
PC8
PC9
PC10
PC11
PC12
PC13
PC14

0.5091 Eigenvalue

PC1-PC14
CAN1

CAN2

PC2-PC14
CAN1

CAN2

1.2805 −0.7460−5.8619
1.87795.41622.5298−13.4996 −1.0185 12.7377
0.18220.7162 −6.3630 −0.3579 −6.7861
5.3022 −2.4817 −4.8601 −3.1148
8.53200.8708 −8.0618
0.1251−2.2883
0.1613
2.14210.38360.83909.7660 −1.2719 10.2354−19.5342 −4.2379 18.5691 −2.6552−13.2718 −18.5866 13.3946 −18.3927−2.2114 14.2976
1.3674 15.3041
18.7030
4.3906 −17.7983
2.892912.6217 −30.3189 −10.3333 −33.1692−14.0194 −2.3797 −13.3009 −1.2024
2.46710.16711.75340.1430115

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Fig. 12. Scatter plots of scores on the ﬁrst and second canonical variates derived from external body proportions of dwarf minke whales (DWM), Antarctic minke whales (ATM) and North Paciﬁc common minke
whales (NPM), for females (upper) and males (lower).

smaller in Antarctic minke whales, i.e., Antarctic minke whales seem to possess a relatively shorterand narrower rostrum, and a larger mouth cavity. The analysis also shows that Antarctic minke whales
have a somewhat larger occipital portion of skull (SK30, SK32, and SK63).
From the results of PCA, eigenvalues and eigenvectors were calculated using DA for each canonical covariate CAN (Table 11) with and without PC1. Plots of the ﬁrst two CANs are shown in Fig.
13. Irrespective of whether PC1 was included or not, skull morphology diﬀered among dwarf minke
whales, Antarctic minke whales and North Paciﬁc common minke whales.
CLUSTER analyses for skull morphology
Although the following analysis is not necessarily the most eﬀective approach to advance the investigation on diﬀerences in skull morphology among taxa, cluster type analyses were carried out using
skull data of sexually mature whales, comprising eight dwarf minke whales (present study), 14 North
Atlantic common minke whales (present study and from Tomilin (1967)), ﬁve Antarctic minke whales(from Nakamura, 2012), and 47 North Paciﬁc common minke whales (from Nakamura, 2012).
In earlier analyses, statistical diﬀerences were identiﬁed in 29 of 44 proportions among minke
whale taxa. Furthermore, reliable measurements, which are potentially less subject to technical measuring error, were extracted. These included (1) CBL (condylobasal length), (2) length of tympanic
bulla, (3) pre-maxilla length as proportion of CBL, (4) maxillary length as proportion of CBL, (5)mandible length along its outer margin as proportion of CBL, (6) occipital length as proportion of
CBL.
Among the six variables chosen, (3), (4) and (5) had growth dependent changes in relative values.
For this comparison, only the data obtained from sexually mature animals or those from animals witha CBL >145 cm, which were known to be independent of growth dependent changes, were used. The
values of the respective variants are given in Appendix 2.
In the next step to evaluate degree of similarity among the diﬀerent taxa, the parameter S was esti-

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

Table 10. Results of ANCOV of skull measurements with skull length (SK01) as a covariate for minke whales infour types: dwarf form (DWM), North Atlantic (NA), North Paciﬁc (NPM) and Antarctic (ATM) minke whales.
Sample size
Item

SK02
SK03
SK04
SK05
SK06
SK07
SK08
SK09
SK10
SK11
SK12
SK13
SK14*
SK15*
SK16*
SK17*
SK18
SK19
SK20*
SK21
SK22
SK23*
SK24
SK25
SK26*
SK27
SK28*
SK29*
SK30
SK31
SK32
SK33
SK34*
SK35
SK36**
SK37**
SK38**
SK39**
SK40**
SK41
SK42
SK43
SK44*
SK45
SK46
SK47
SK48
SK49*
SK50*
SK51*
SK52
SK53
SK54
SK55
SK56*

Estimated value at mean covariate with SE

DWM

NA

NPM

ATM

n

n

n

n

15
13
13
12
12
13
13
14
15
12
12
15
13
15
14
15
14
15
15
14
13
13
14
13
13
13
14
14
14
13
15
14
14
11
11
10
10
10
14
12
14
14
14
14
13
13
14
14
13
13
14
13
13
12
15

5
8
1
5
2
1
1
1
7
1
1
4
27
1
5
9
5
11
11
—
—
8
3
—
5
5
3
—
—
3
4
—
—
1
1
1
1
1
6
2
—
—
2
—
—

29
25
26
25
24
27
27
29
29
23
23
28
28
26
26
28
25
28
28
25
11
25
24
20
27
28
27
28
28
28
27
28
28
20
22
20
19
19
28
23
26
24
26
25
24
24
28
28
28
21
29
25
26
21
29

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

21
21
3
3
2
2
4
4
2

Result of
ANCOVCetacean Popul. Stud. (CPOPS), Full paper
Vol. 3, 2021, 93–128

DWM

NA

NPM

ATM

Mean+SE

Mean+SE

Mean+SE

Mean+SE

0.450
0.000
0.000
0.000
0.000
0.000
0.000
0.000

4.715+0.009
4.845+0.008
4.857+0.008
4.802+0.008
4.804+0.080
4.851+0.009
4.857+0.009
4.872+0.008

4.703+0.014
4.845+0.009
4.835+0.026
4.818+0.012
4.814+0.019
4.876+0.027
4.891+0.026
4.908+0.024

4.700+0.006
4.831+0.005
4.842+0.006
4.793+0.005
4.795+0.005
4.841+0.006
4.844+0.006
4.865+0.005

4.696+0.007
4.785+0.006
4.797+0.006
4.748+0.006
4.749+0.007
4.799+0.007
4.796+0.007
4.810+0.006

0.048
0.000
0.041

2.098+0.047
2.152+0.043
4.204+0.017

2.370+0.135
2.551+0.122
4.163+0.029

2.204+0.032
2.236+0.028
4.233+0.012

2.127+0.037
2.079+0.034
4.194+0.013

0.045
0.000

4.432+0.028
4.110+0.017

4.439+0.038
4.033+0.017

4.412+0.019
4.052+0.011

4.333+0.022
3.975+0.013

0.000
0.527

2.727+0.068
2.211+0.055

2.838+0.044
2.284+0.054

2.271+0.056
2.235+0.040

0.967
0.244

2.728+0.030
0.991+0.150

2.750+0.054

2.731+0.020
0.987+0.107

2.743+0.023
0.678+0.122

0.000

2.815+0.028

3.025+0.042

2.851+0.018

2.917+0.021

0.000
0.009
0.000
0.000

2.328+0.019
2.834+0.051
3.695+0.017
2.085+0.026

2.679+0.101
3.842+0.030

2.421+0.013
2.650+0.033
3.763+0.012
2.148+0.018

2.479+0.015
2.633+0.039
3.830+0.014
1.913+0.021

0.000
0.000
0.000
0.000
0.000
0.004
0.001
0.000
0.000

2.096+0.019
1.793+0.017
2.040+0.018
1.808+0.016
1.808+0.016
3.316+0.070
2.595+0.039
4.967+0.005
4.926+0.005

2.239+0.014
1.945+0.012
2.220+0.013
1.952+0.011
1.952+0.011
3.325+0.049
2.581+0.026
4.946+0.003
4.908+0.003

2.200+0.015
1.965+0.011
2.235+0.011
1.973+0.010
1.973+0.010
3.475+0.050
2.767+0.029
4.966+0.004
4.927+0.004

0.000
0.000
0.000
0.159

4.927+0.006
4.637+0.010
4.640+0.010
3.692+0.069

3.525+0.058

4.900+0.004
4.571+0.006
4.582+0.006
3.658+0.046

4.919+0.005
4.640+0.008
4.650+0.008
3.667+0.061

0.000
0.000
0.010
0.010

4.696+0.008
4.702+0.008
4.991+0.006
4.994+0.005

4.698+0.018
4.711+0.016
5.006+0.009
5.010+0.007

4.655+0.005
4.653+0.005
4.978+0.004
4.980+0.003

4.712+0.007
4.706+0.006
4.990+0.004
4.991+0.004

2.181+0.051
1.758+0.057
2.140+0.057
1.705+0.049
1.705+0.049
3.056+0.106
2.736+0.078

117

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Table 10. Results of ANCOV of skull measurements with skull length (SK01) as a covariate for minke whales infour types:
dwarf form (DWM), North Atlantic (NA), North Paciﬁc (NPM) and Antarctic (ATM) minke whales.
Table
10. Continued.
Sample size
Item

SK57
SK58
SK59
SK60
SK61
SK62
SK63
SK64
SK65
SK66
SK67
SK68
SK69
SK70
SK71
SK72
SK73
SK74
SK75
SK76

Estimated value at mean covariate with SE

DWM

NA

NPM

ATM

n

n

n

n

14
14
15
15
15
15
14
14
14
14
8
8
6
6
6
6
7
7
6
6

4
6
3
5
3
2
6
2
5
—
—
—
—
—
—
—
—
—
—

28
28
27
28
27
28
28
29
29
28
27
25
23
25
25
26
26
24
26
25

28
32
32
32
32
32
31
30
31
31
22
22
24
24
25
25
26
26
25
25

Result of
ANCOV
0.224
0.050
0.000
0.095
0.011
0.093
0.000
0.000
0.708
0.576
0.027
0.035
0.002
0.006
0.000
0.000
0.004
0.009
0.136
0.058

DWM

NA

NPM

ATM

Mean+SE

Mean+SE

Mean+SE

Mean+SE

2.871+0.029
3.028+0.027
5.150+0.008
5.147+0.013
5.111+0.007
5.107+0.010
3.103+0.010
3.103+0.010
2.802+0.017
2.793+0.018
2.589+0.020
2.586+0.021
2.750+0.045
2.759+0.037
2.186+0.037
2.177+0.031
3.044+0.015
3.051+0.016
0.931+0.034
0.928+0.033

2.788+0.036
2.894+0.032
5.143+0.009
5.120+0.015
5.091+0.008
5.076+0.012
3.195+0.012
3.184+0.012
2.828+0.021
2.819+0.021
2.481+0.028
2.482+0.029
2.927+0.050
2.890+0.043
2.031+0.043
2.036+0.037
2.946+0.018
2.960+0.019
1.052+0.042
1.071+0.040

2.899+0.044
3.018+0.040
5.179+0.011
5.164+0.019
5.125+0.010
5.111+0.015
3.129+0.015
3.131+0.015
2.821+0.026
2.829+0.026
2.571+0.038
2.551+0.040
2.506+0.084
2.573+0.071
1.870+0.072
1.883+0.061
3.039+0.032
3.057+0.033
0.957+0.076
0.952+0.075

3.032+0.070
5.215+0.015
5.238+0.040
5.148+0.015
5.168+0.031
3.170+0.037
3.117+0.021
2.770+0.062
2.810+0.040*: Parallel test indicated no signiﬁcance.
**: As the result showed no correlation with skull length as a covariate, a multivariated analysis of variance was adopted.

Table 11. Eigenvectors and eigenvalues derived from the canonical discriminant analysis using the PC scoresof PCA.
PC1-PC5

PC2-PC5

Principal
Component

CAN1

CAN2

CAN1

CAN2

PC1
PC2
PC3
PC4
PC5

−1.5129
1.1734−0.05170.60070.08590.41020.76070.8427−0.3278−0.3668

1.24130.59240.1062−0.18700.3346−0.6666
0.70680.5102

Eigenvalue

3.24170.78541.03650.3831

Fig. 13. Scatter plots of scores on the ﬁrst and second canonical variates derived from skull measurements ofdwarf (DWM), North Atlantic (NA), North Paciﬁc (NPM) and Antarctic minke whales (ATM).

118

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Table 12. Estimated value of correction coeﬃcient r and degree of similarity S in the cluster analysis on theskull between diﬀerent types of minke whales.
Type

Estimated (r/S)
Antarctic

North Paciﬁc

Dwarf

North Atlantic

Antarctic
North Paciﬁc

0.99220.0078Dwarf

0.98330.01670.99830.0017

North Atlantic

0.98250.01750.99720.00280.99830.0017

Fig. 14. Dendrogram showing the degree of similarity among the minke whale clade based on cluster analyses
on the skull morphology. ANT, Antarctic minke whale; NPM, North Paciﬁc common minke whale; NA, North
Atlantic common minke whale; DWM, dwarf minke whale. S, see below.

mated as deﬁned below:

S =1 − r(11)where S represents the degree of similarity, r being the correlation coeﬃcient on the variants between
diﬀerent types of minke whales.
Table 12 gives the estimated values for correlation coeﬃcient and degree of similarity for each pairwise comparison. A dendrogram was produced through cluster analyses using the values from the groupaverage method. These represent the interrelationships in diﬀerent minke whale taxa by weighing thedegree of similarity (Fig. 14). From this dendrogram it was clear that the Antarctic minke whales weremost distant, and secondly, the North Paciﬁc common minke whales were relatively distant from theNorth Atlantic common minke whales and dwarf minke whales. In conclusion, in the present cluster
analysis, the dwarf minke whales were closest morphologically to the North Atlantic common minke
whales. This was also genetically supported by the previous analyses such as Pastene et al. (2007).

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Discussion
First of all, throughout this study, the scarcity of available samples has become an issue, however,as it is almost impossible to obtain further samples of the same quality, we had to proceed with theanalyses, bearing in mind this sample limitation. Thus, the shortage of an adequate number of samples
should be recognized as a potential problem in all analyses during this study.
There are currently many reports on the occurrence of dwarf minke whales from coastal waters
in low and middle latitudes in the Southern Hemisphere, mainly Brazil and Australia (Zerbini etal., 1996; Acevedo et al., 2006; Meirells et al., 2011, etc.). In higher latitudes, data on dwarf minke whales has only been from sightings (Kato and Fujise, 2000, Acevedo et al., 2011, Kato et al. inpress). Until the present study there was no information on the biology of dwarf minke whales in higher latitudes. Arnold et al. (1987) reported a considerable number of the dwarf minke whale strandings
and sporadic sightings in the austral winter. The 80% of sightings were in the waters oﬀ Queensland,
Australia, in June and July (Arnold, 1997), which would be consistent with the north-south seasonal
movements exhibited by other austral balaenopterids. However, there have also been mid-summer
strandings of dwarf minke whales on the southeast coast of Australia (Arnold et al., 1987; Zerbini etal., 1996; Kemper, pers. comm.) and sightings oﬀ Brazil (at 23°S) during the month of January (Hassel et al., 2003). Therefore, it is possible that migrations are dispersed seasonally but not undertaken
by all individuals.
The relative distributions of dwarf minke whales and Antarctic minke whales in winter are not wellknown, although dwarf minke whales were found closer inshore than Antarctic minke whales in thewaters oﬀ both Brazil as well as the east coast of South Africa (Best, 1985; Zerbini et al., 1996). Published information (Arnold, 1997; Arnold et al., 2005) suggested that a large proportion of dwarf minke whales remain in lower to mid-latitudes during summer, even though they can be found as far south
as the Antarctic Convergence. Kato et al. (in press) examined all of dwarf minke whale sightings
made during the 1994/95 to 2003/04 IDCR/SOWER cruises and reached almost the same conclusionas the present study in terms of sighting distribution. Further sighting information, combined with experiments such as photo-identiﬁcations, will provide a clearer understanding on their distributions andmovements.
The migration of dwarf minke whales as far south as the Antarctic Convergence in summer is latitudinally of a much wider range than generally expected, as dwarf minke whales are thought to prefercoastal zones in low and middle latitudes. However, this may not be unnatural when considered as an
adaptive radiation process of the minke whale clade.
In both hemispheres, minke whales are widely distributed from the ice edge to tropical waters whiledeveloping or dividing into closely related species or subspecies. In this interpretation, they might
further adapt this cline along the allopatric speciation. The minke whale is one of the most cosmopolitan groups and has a clear morphological cline from North Paciﬁc or North Atlantic common minke
whales to Antarctic minke whales. Dwarf minke whales may have evolved in an ecological niche
between Northern Hemisphere common minke whales and Antarctic minke whales. Inferring fromthis relationship, it can be said that the same interpretation is also true morphologically and perhaps
behaviorally for food and feeding habits. Those of the dwarf minke whales are somewhere between
North Paciﬁc or North Atlantic common minke whales and Antarctic minke whales. Both Best (1985)
and Arnold et al. (1987) indicated dwarf minke whales have distinct morphological features and they
bear a closer morphological resemblance to Northern Hemisphere common minke whales rather thanto Antarctic minke whales. The present study also identiﬁed these characteristics in-depth with a larger
sample size and the use of morphometric analyses.
Pastene et al. (2007) provided mtDNA sequence evidence for the separation of the two species, theAntarctic minke whale and the common minke whale, and at least three sub-species of the common
minke whale. They hypothesized that the two species diverged in the Southern Hemisphere less than120

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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

5 million years ago, and that the current subspecies of the common minke whale diverged after the
Pliocene some 1.5 million years ago. Furthermore, Pastene et al. (2010) provided mtDNA sequenceevidence for the genetic separation of the dwarf minke whale in the Southern Hemisphere. The study
used samples from JARPA in the western South Paciﬁc sector of the Antarctic, Tonga and New Zealand (western South Paciﬁc: WSP), as well as from Brazil, Chilean Patagonia and Antarctic Peninsula(western South Atlantic: WSA). They found phylogenetic diﬀerences between dwarf minke whales in
the WSP and WSA, with dwarf minke whales from the WSA being closer to North Atlantic common
minke whales than to dwarf minke whales from the WSP. Glover et al. (2013) provided microsatellite
DNA evidence for the separation of the two species and three subspecies of the common minke whale.
These genetic analyses used the dwarf minke whale specimens from this study.
Nakamura et al., (2018) showed that there were clear morphological diﬀerences in the white patchof the ﬂipper between North Paciﬁc and North Atlantic common minke whales, which have been recently recognized as two distinctively separate subspecies. Further, the length between the tip of ﬂipper to the proximal border of white patch relative to the total ﬂipper length was signiﬁcantly larger in
the North Atlantic (74.31%) as compared to the North Paciﬁc (63.62%) common minke whales. Also,
the mean angle between the proximal boundary line of the white patch and the longitudinal axis of theﬂipper was signiﬁcantly diﬀerent between the North Atlantic (70.05 degrees) and the North Paciﬁc(92.29 degrees) common minke whales. Therefore, a numerical comparison of the white patch on theﬂipper/shoulder should be conducted in the future for the three sub-species of common minke whales.
Morphometric analyses on both the body proportion and the skull revealed at least three types ofcommon minke whale clade can be distinguished. Also, the ﬂipper/shoulder portion is a consistent andreliable characteristic for distinguishing the three types. As examined by Nakamura et al. (2018), thewhite patch of the ﬂipper/shoulder portion is wider in the following order; dwarf minke whale>North
Atlantic common minke whale> North Paciﬁc common minke whale. This is an additional indicationthat the dwarf minke whale is closer to the North Atlantic common minke whale. While it is still inconclusive due to small sample size, the cluster analyses on body proportion and skull morphometry(Fig. 12) in the present study supports this hypothesis. Before reaching the ﬁnal conclusion on thetaxonomic status of dwarf minke whales, there are some outstanding issues to be pursued. Numericalcomparison of the white patch between the dwarf minke whale and the North Atlantic common minke
whale needs to be conducted. In addition, in light of the genetic diﬀerences suggested by several studies, morphological and morphometric comparative analyses among dwarf minke whales from diﬀerent
locations of the Southern Hemisphere should be carried out.
However, there is little doubt that the dwarf minke whales have diverged from other common minke
whales, at least at the subspecies level. Morphometric comparison in both external body and skull proportions in the present study provided reliable evidence to identify and conﬁrm the diﬀerences among
the minke whale clade. The separation of dwarf minke whales from other common minke whale
sub-species is further supported by genetic evidence. Based on such convincing evidence, dwarf minke whales from the Indo-Paciﬁc sector of the Antarctic examined in this study should be formally described as an independent sub-species or species from other common minke whales.
Acknowledgements

During the course of the present study, our co-author, the late Dr. Peter Barrington Best sadly passed away on 22 April
2015. The present study had been initiated by him. His initiative inspired our present study, and he agreed to be one of theco-authors of this study. Further, he undertook the supervision of senior author Kato during the present study and had previously co-authored with the latter (Kato et al., 2015). Also, the late Dr. Seiji Ohsumi, former Director General of the Instituteof Cetacean Research (ICR), sadly passed away on 2 November 2019. He greatly encouraged us to conduct the present study.
We would like to express our sincere gratitude for the work and involvement of these two remarkable scientists. May they
rest in peace. The late Dr. Peter W. Arnold (James Cook University at that time) and Dr. Catherin Kemper (South AustralianMuseum at that time) kindly provided information and great assistance to us regarding dwarf minke whales in the coastalzone of Australia.
We also wish to express our deep appreciation to the many researchers and crew during our study on board of Nisshin-

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KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST
Maru No. 3 and Nisshin-Maru as well as to program leaders under the JARPA program from 1987/88 to 1992/93, especiallythe late Drs. Ikuo Ikeda and Fukuzo Nagasaki who always oﬀered generous support. The present study was technically supported by Drs. Ryoko Zenitani (ex-ICR scientist), Takeharu Bando (ICR), Hikari Maeda, Tomio Miyashita, Toshiya Kishiroand Hideyoshi Yoshida (National Research Institute of Far Seas Fisheries; NRIFSF). Mr. Hiromasa Furuhashi, Hokkaido
University (at that time) kindly identiﬁed prey species from the stomach contents. Dr. Satoko Inoue supported histologicalexamination on the testes collected from the male whales. Ms. Ritsuko Shige (ex-NRISFS staﬀ) and Ms. Yumi Hosone (exICR staﬀ) assisted with the drafting of ﬁgures and tables. Professor Kazumi Sakuramoto (TUMSAT) kindly took charge ofhandling the present paper for the CPOPS journal. Dr. Gabriel Gomez Diaz (CPOPS) coordinated adjusting style format of
the ﬁnal version of the manuscript, as well as English proofreading. Ms. Saemi Baba kindly took charge of English proofreading on the pre-ﬁnal version.
Finally, we wish to express our deep gratitude to Drs. Toshio Kasuya, Robert L. Brownell Jr. and Koichi Kaji who provided critical and highly insightful reviews.

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Tomilin, A. G. 1967. Mammals of the U.S.S.R. and Adjacent Countries. Vol. IX. Cetacea. Israel Program for Scientiﬁc Translations. Jerusalem. 717 pp.
Wada, S. and Numachi, K. 1979. External and biochemical characters as an approach to stock identiﬁcation for the Antarctic
minke whales. Rep. int. Whal. Commn. 29: 421–432.
Wada, S., Kobayashi, T. and Numachi, K. 1991. Genetic variability and diﬀerentiation of mitochondrial DNA in minke
whales. Rep. int. Whal. Commn. (Special issue) 13: 203–215.
Zenitani, R., Fujise, Y. and Kato. H. 1997. Biological parameters of Southern minke whales based on materials collected by
the JARPA survey under special permit in 1987/88 to 1995/96. Paper SC/M97/12 presented to the IWC Intersessional
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Zerbini A. N., Secchi E. R., Siciliano S, Simões-Lopes P. C. 1996. The dwarf form of the minke whale, Balaenoptera acutorostrata Lacépède, 1804, in Brazil. Rep. Int. Whal. Commn. 46: 333–340.

Received: January 31, 2021
Accepted: August 19, 2021
Published online: December 23, 2021

124

Cetacean Popul. Stud. (CPOPS), Full paper
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MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALESAppendices
Appendix 1. Upper: Skull and mandible of the dwarf minke whale (MTUM-DW273); a) skull
dorsal view, b) skull ventral view, c) skull lateral view, d) mandibles dorsal view, e) skull frontal view,f) backward view. Bottom: other bones of the same skeleton; a) cervical, b) dorsal, c) lumber, d) caudal vertebrae, e) chevron, f, g) left and right ribs with lateral surface and h, i) coastal surface of rightand left scapula, j) sternum, k) pelvic bone, l) hyoid, m) humerus, radius, ulna and manus on the left
ﬂipper. Scale bars are 1.00 m size marked with 0.1 m intervals.

Cetacean Popul. Stud. (CPOPS), Full paper
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125

126

Condylobasal length
Length of rostrum
Length of premaxillary (L)Length of premaxillary (R)Length of maxillary (L)Length of maxillary (R)Tip of premaxillary to tip of maxillary (L)Tip of premaxillary to tip of maxillary (R)Tip of premaxillary to nares, anterior
Tip of premaxillary to vertex
Tip of premaxillary to palatine, anterior (L)Tip of premaxillary to palatine, anterior (R)Tip of premaxillary to palatine, posterior (L)Tip of premaxillary to palatine, posterior (R)Tip of premaxillary to pterygoid process (L)Tip of premaxillary to pterygoid process (R)Tip of premaxilla to posterior edge of occipitalbone (L)Tip of premaxilla to posterior edge of occipitalbone (R)
Tip of premaxilla to posterior edge of temporalbone (L)Tip of premaxilla to posterior edge of temporalbone (R)
Breadth of maxillary, posterior edge
Breadth of premaxillary, posterior edge
Tip of premaxillary to anterior end of vomer,
medianLength of vomer
Breadth of rostrum at base
Breadth of premaxillary at base
Breadth of rostrum at middle
Breadth of premaxillary at middle
Greatest breadth of premaxillary
Breadth of cranium, maxillaries

Specimen ID
Body length (m)
Sex

106.1
102.8
103.2
11.9
1.9
13.3
76.6 131.3
34.5
50.7
10.8
15.4
19.7
30.7
7.9
12.7
13.9
20.2
49.5
76.0

169.4
164.2
164.8
19.0
3.0
21.2
122.4
55.1
17.3
31.4
12.6
22.2
79.1

14.2
3.4
17.7

171.2

168.7

166.1

165.7

163.4
106.0
119.4
121.3
114.3
114.8
8.4
9.8
106.2
126.5
102.3
105.2
137.4
139.2
146.3

63.5
74.7
75.1
73.4
73.5
2.8
3.1
68.3
77.5
62.3
62.5
84.2
84.2
90.2
90.0
106.4

159.7
101.4
119.3
120.0
117.2
117.3
4.5
4.9
109.0
123.7
99.5
99.8
134.5
134.5
144.0
143.8
170.0

cm

14.3
3.2
18.3

152.2

153.5

155.9

80.4 116.2
31.0
51.2
9.4
12.8
18.8
30.5
7.8
12.7
12.4
19.2
46.5
73.8

8.7
2.1
10.8

104.8

103.2

101.7

14.0
2.1
19.3

136.5

136.5

138.7

133.1
83.4
97.9
98.5
94.3
94.1
8.7
5.7
85.9
103.7
85.8
86.9
111.7
111.7
119.7
119.3
139.1

cm

cm

80.4
37.0
8.8
21.6
8.9
13.1
49.5

10.5
1.6
14.5

102.6

102.6

104.2

93.7
43.8
11.3
23.7
9.8
15.9
57.6

11.6
1.3
17.9

124.0

127.4

19.0
4.8
21.7

168.2

169.4

172.0

173.4

164.7
111.0
120.0
120.8
115.2
115.4
10.7
10.7
109.1
128.3
108.2
107.6
142.2
141.3
150.3

cm

cm

15.3
3.2
18.5

170.7

172.2

176.8

77.5 136.5
32.7
59.3
8.3
12.8
20.8
36.4
9.2
16.5
13.5
22.0
47.8
82.8

11.5
2.9
13.2

102.1

102.9

104.4

17.9
3.0
16.3

162.7

162.7

165.3

156.1
106.8
119.8
120.2
111.4
112.8
10.3
10.5
104.2
125.5
100.2
100.1
135.2
135.5
143.1
143.3
165.3

cm

80.8
37.3
8.5
22.3
9.9
14.6
51.6

11.5
1.9
10.4

104.2

104.2

105.9

68.4
76.7
77.0
71.4
72.3
6.6
6.7
66.8
80.4
64.2
64.1
86.6
86.8
91.7
91.8
105.9

%

92/93 3307.17
F

80.7 126.1
35.0
58.2
7.6
13.2
21.5
34.8
9.8
15.4
13.0
22.8
48.9
80.5

9.0
1.9
10.9

100.9

101.8

104.5

66.2
72.6
72.3
70.5
70.5
5.7
4.9
65.2
77.8
63.8
64.0
85.9
84.6
90.9
90.0
105.1

%

89/90 215
7.07
F

169.2
112.0
122.8
122.4
119.3
119.3
9.6
8.3
110.4
131.7
108.0
108.3
145.3
143.2
153.8
152.3
105.3 177.8
67.4
72.9
73.3
69.9
70.1
6.5
6.5
66.2
77.9
65.7
65.3
86.3
85.8
91.3

%

88/89 227
7.02
F

76.6 127.6
35.8
53.8
9.2
13.7
19.4
34.2
8.0
15.2
13.0
22.3
47.1
78.7

9.5
1.1
14.6

101.4

104.2

88.6

84.1

64.3

67.2
78.7

75.2

66.7

%

89/90 199
5.41
M

122.3
62.7
81.6
73.6
74.0
92.0
70.8
70.7
6.5
4.3
64.5
82.2
77.9
96.3
64.5
65.3
78.7
83.9
83.9 102.8
89.9
89.6 108.4
104.5

%

88/89 070
5.94
F

78.0 107.0
34.4
49.2
8.6
11.7
20.5
28.7
8.5
11.8
12.9
17.4
49.5
65.9

9.6
2.1
12.3

102.1

103.0

104.6

65.6
73.7
73.4
70.8
70.5
5.6
6.2
65.0
77.9
65.6
65.6
86.0
85.6
90.3
90.5
105.2

%

88/89 014
6.6
M

149.0
97.7
109.8
109.3
105.5
105.0
8.3
9.2
96.8
116.0
97.8
97.8
128.1
127.6
134.6
134.8
101.4 156.8
64.9
73.1
74.2
70.0
70.3
5.1
6.0
65.0
77.4
62.6
64.4
84.1
85.2
89.5

%

cm

cm

%

88/89 013
6.99
F

87/88 273
7.01
M

List of skeletal measurements by the standard measuring method for all dwarf minke whales examined in the present skeletal analysis.

Measurement points

Appendix 2.

78.9±1.86
34.7±2.1
8.9±0.97
20.6±1.21
8.7±0.83
13.3±0.7
48.8±1.62

10.3±1.24
1.9±0.52
12.5±1.65

102.7±1.34102.9±0.74

104.4±1.35

65.7±1.94
73.9±1.4474.3±1.44
71±1.1871.1±1.26
5.5±1.33
5.4±1.34
66±1.3178.2±0.98
64.1±1.33
64.5±185.3±1.16
85±1.0190.5±0.76
90.1±1.04
104.8±1.63

Mean±S.D. %KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

Cetacean Popul. Stud. (CPOPS), Full paper
Vol. 3, 2021, 93–128

Breadth of cranium, anterior edge of zygomatic
process
Breadth of cranium, middle of orbital foramen
Breadth of occipital bone
Breadth of cranium, middle of zygomatic
process
Length from upper ridge of foramen magnum tosuperior part of occipital bone
Greatest breadth of palatine
Length of palatine (L)Length of palatine (R)Breadth of palatine, posterior
Breadth across hamular processes of pterygoid
Length of orbit (L)Length of orbit (R)Height of cranium
Length of nasals
Breadth of nasal, posterior
Breadth of nasal at middle
Minimum breadth of parietal bones
Height of foramen magnum
Breadth of foramen magnum
Breadth across occipital condyles
Breadth of occipital condyle (L)Breadth of occipital condyle (R)Height of occipital condyle (L)Height of occipital condyle (R)Length of tympanic bulla (L)Minimum breadth of tympanic bulla (L)Greatest breadth of tympanic bulla (L)Thickness of tympanic bulla at middle (L)Skull height
Minimum width of the skull at squamous
temporalMeasurement points

Specimen ID
Body length (m)
Sex

55.8
50.2
43.5
55.9
25.3
15.5
23.0
23.2
15.8
8.1
10.6
10.3
9.3
0.7
2.8
11.6
4.0
5.1
10.6
4.3
4.3
6.8
7.0
5.2
3.0
3.8

89.1
80.1
69.5
89.3
40.4
24.8
36.8
37.1
25.3
12.9
17.0
16.5
14.9
1.1
4.4
18.5
6.4
8.2
17.0
6.8
6.9
10.9
11.1
8.3
4.8
6.1

14.3
22.9
22.1
14.0
7.8
9.2
9.8
30.6
10.0
1.2
3.5
10.0
3.6
4.8
10.2
4.3
4.3
6.0
6.1
5.0
3.1
3.9
30.6
10.6

50.0
17.4

24.7

47.4
38.7
50.2

51.7

23.3
37.4
36.1
22.8
12.7
15.0
16.0
50.0
16.3
2.0
5.8
16.4
5.9
7.8
16.7
7.0
7.0
9.8
10.0
8.2
5.1
6.3

40.4

77.5
63.3
82.1

84.5

%

cm

cm

%

88/89 013
6.99
F

87/88 273
7.01
M

23.8
32.3
32.3
23.1
11.7
16.5
15.5
45.1
14.5
1.3
4.9
15.3
7.3
6.0
15.7
6.2
6.5
10.1
10.0
7.9
4.9
6.1
4.3
45.1
15.8

36.4

72.3
59.3
79.4

80.8

cm

16.0
21.7
21.7
15.5
7.9
11.1
10.4
30.3
9.7
0.9
3.3
10.3
4.9
4.0
10.5
4.2
4.4
6.8
6.7
5.3
3.3
4.1
2.9
30.3
10.6

24.4

48.5
39.8
53.3

54.2

%

88/89 014
6.6
M

21.8
28.3
27.3
21.3
11.3
15.5
15.5
34.3
14.0
1.1
4.5
16.5
6.6
7.3
15.8
6.6
6.2
9.2
9.2
8.2
5.2
6.2
4.5
34.3
14.9

31.4

66.7
51.2
71.8

72.8

cm

16.4
21.3
20.5
16.0
8.5
11.6
11.6
25.8
10.5
0.8
3.4
12.4
5.0
5.5
11.9
5.0
4.7
6.9
6.9
6.2
3.9
4.7
3.4
25.8
11.2

23.6

50.1
38.5
53.9

54.7

%

88/89 070
5.94
F

18.5
26.6
27.0
21.7
11.6
14.5
14.0
37.2
10.8
0.8
3.3
12.8
6.3
7.4
13.3
5.3
5.3
8.6
8.4
7.3
4.5
5.7
3.8
37.2
13.6

27.7

58.6
49.4
64.6

64.7

cm

15.1
21.7
22.1
17.7
9.5
11.9
11.4
30.4
8.8
0.7
2.7
10.5
5.2
6.1
10.9
4.3
4.3
7.0
6.9
6.0
3.7
4.7
3.1
30.4
11.1

22.6

47.9
40.4
52.8

52.9

%

89/90 199
5.41
M

22.7
36.2
35.8
27.3
13.8
16.5
17.0
49.4
17.8
2.6
7.1
20.1
6.3
7.1
14.3
6.8
6.3
8.8
8.9
7.7
5.1
5.9
4.3
49.4
17.1

40.2

77.7
66.4
85.3

86.3

cm

13.8
22.0
21.7
16.6
8.4
10.0
10.3
30.0
10.8
1.6
4.3
12.2
3.8
4.3
8.7
4.1
3.8
5.3
5.4
4.7
3.1
3.6
2.6
30.0
10.4

24.4

47.2
40.3
51.8

52.4

%

88/89 227
7.02
F

15.7
22.3
21.5
16.4
8.5
9.8
9.5
30.4
11.1
0.7
3.8
11.5
3.7
3.8
9.9
4.0
3.8
5.9
5.9
4.9

2.5
30.4
8.7

4.2
51.5
14.8

25.5

49.1
37.0
52.3

54.1

%

26.5
37.8
36.4
27.7
14.4
16.5
16.0
51.5
18.7
1.2
6.5
19.4
6.3
6.5
16.8
6.7
6.5
10.0
10.0
8.3

43.2

83.0
62.6
88.5

91.5

cm

89/90 215
7.07
F

25.3
37.7
37.1
26.7
12.8
16.5
16.5
53.4
17.8
1.9
5.3
20.0
6.7
7.3
17.2
6.3
6.8
9.8
9.8
7.6
4.8
5.9
4.0
56.4
17.2

37.3

80.4
61.7
87.7

89.4

cm

16.2
24.2
23.8
17.1
8.2
10.6
10.6
34.2
11.4
1.2
3.4
12.8
4.3
4.7
11.0
4.0
4.4
6.3
6.3
4.9
3.1
3.8
2.6
36.1
11.0

23.9

51.5
39.5
56.2

57.3

%

92/93 330
7.17
F

Appendix 2. (Continued.)
List of skeletal measurements by the standard measuring method for all dwarf minke whales examined in the present skeletal analysis.

15.4±0.93
22.4±0.94
22.1±1.02
16.1±1.14
8.3±0.54
10.6±0.92
10.5±0.74
30.2±2.45
10.2±0.89
1±0.333.4±0.53
11.4±1.05
4.3±0.61
4.8±0.75
10.5±0.93
4.3±0.31
4.2±0.28
6.4±0.6
6.4±0.56
5.3±0.53
3.3±0.35
4.1±0.43
2.8±0.3530.5±3.01
10.5±0.84

24.3±0.93

49±1.5139.7±1.953.3±2.01

54.1±1.82

Mean±S.D. %MORPHOLOGY, GROWTH AND LIFE HISTORY OF DWARF MINKE WHALES

Cetacean Popul. Stud. (CPOPS), Full paper
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127

128

Occipital bone width at jugal process
Length of mandible, straight (L)Length of mandible, straight (R)Length of mandible, curved (L)Length of mandible, curved (R)Breadth of mandible at middle (L)Breadth of mandible at middle (R)Height of mandible at middle (L)Height of mandible at middle (R)Height of mandible at coronoid process (L)Height of mandible at coronoid process (R)Height of mandible at coronoid (L)Height of mandible at coronoid (R)Breadth of mandible at coronoid (L)Breadth of mandible at coronoid (R)Specimen ID
Body length (m)Sex

164.5 103.0
155.4
97.3
156.2
97.8
164.5 103.0
7.0
4.4
7.0
4.4
10.4
6.5
10.5
6.6
21.5
13.5
21.4
13.4
16.8
10.5
16.4
10.3
10.2
6.4
11.0
6.9

36.8
22.5
167.0 102.2
157.4
96.3
158.0
96.7
166.4 101.8
6.8
4.2
7.1
4.3
10.0
6.1
10.3
6.3
21.0
12.9
21.2
13.0
16.1
9.9
16.1
9.9
10.0
6.1
9.9
6.1

%

cm

cm

%

88/89 013
6.99
F

87/88 273
7.01
M
%

36.2
24.3
155.0 104.0
146.0
98.0
145.8
97.9
154.0 103.4
6.4
4.3
6.5
4.4
9.8
6.6
10.2
6.8
19.3
13.0
19.4
13.0
14.3
9.6
14.8
9.9
9.4
6.3
9.3
6.2

cm

88/89 014
6.6
M

36.2
140.0
133.5
133.5
139.9
6.0
6.2
9.7
9.5
18.4
18.5
14.4
14.4
9.3
9.1

cm
27.2
105.2
100.3
100.3
105.1
4.5
4.7
7.3
7.1
13.8
13.9
10.8
10.8
7.0
6.8

%

88/89 070
5.94
F
%

21.7
17.7
127.0 103.8
120.7
98.7
121.5
99.3
126.0 103.0
4.7
3.8
4.7
3.8
7.6
6.2
7.7
6.3
16.0
13.1
16.3
13.3
12.1
9.9
12.3
10.1
7.7
6.3
8.0
6.5

cm

89/90 199
5.41
M
%

cm

98.7
99.0
4.0
4.0
7.0
7.1
13.7
14.0
10.2
10.8
6.8
6.7

25.6

%

89/90 215
7.07
F

46.6
28.3
43.3
170.8 103.7
161.0
97.8
162.0
98.4 167.0
170.8 103.7 167.5
7.5
4.6
6.8
7.3
4.4
6.8
11.1
6.7
11.8
11.2
6.8
12.0
23.3
14.1
23.2
23.2
14.1
23.7
18.3
11.1
17.3
18.5
11.2
18.3
10.7
6.5
11.5
10.7
6.5
11.3

cm

88/89 227
7.02
F

%

Mean±S.D. %

41.3
26.5 24.6±3.56
165.0 105.7
104±1.2
154.8
99.2 98.2±1.3
154.5
99.0 98.5±1.1
165.5 106.0 103.1±2.126.84.4
4.3±0.24
7.0
4.5
4.3±0.26
10.6
6.8
6.7±0.38
10.7
6.9
6.7±0.32
21.4
13.7 13.5±0.46
21.6
13.8 13.6±0.4417.7
11.3 10.4±0.63
17.3
11.1 10.5±0.5411.77.5
6.6±0.46
11.2
7.2
6.6±0.36cm

92/93 330
7.17
F

List of skeletal measurements by the standard measuring method for all dwarf minke whales examined in the present skeletal analysis.
(Continued.)

Measurement points

Appendix 2.

KATO, FUJISE, NAKAMURA, HAKAMADA, PASTENE AND BEST

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J-STAGE Advance published date: November 9, 2021

GENETIC MATCHES OF SOUTHERN RIGHT WHALESGENETIC MATCHES OF SOUTHERN RIGHT WHALESIN THE INDIAN SECTOR OF THE ANTARCTIC:A CONTRIBUTION TOWARDS UNDERSTANDING
THEIR MOVEMENT AND SITE-FIDELITY
Luis A. PASTENE1, 2*, Mutsuo GOTO1, Mioko TAGUCHI1
and Koji MATSUOKA1
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
Project Microbiomes as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia,
Centro de Estudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile*Corresponding author: pastene@cetacean.jp
12

Abstract
Genetic analyses were conducted to investigate the individual identiﬁcation (and matching)of southern right whales (Eubalaena australis) from samples collected in the austral summer
in the Indian Ocean sector of the Antarctic (between 80°–135°E, south of 60°S). The study was
conducted to evaluate the utility of this approach for studies on site ﬁdelity and range. In total,
157 skin biopsy samples were collected from free-ranging whales during fourteen summer surveys. The DNA was extracted from each biopsy sample, genotyped at fourteen microsatellite
loci, sequenced for 381 nucleotides of the mtDNA control region, and the sex determined by
the presence of a Y-chromosome speciﬁc locus. Eight matches were detected (four males andfour females) using individual matching by multi-locus genotypes supported by mtDNA haplotype and sex determination. Where photographs were available, two matches were conﬁrmed
by photo-identiﬁcation. These eight re-samples show that at least some males and females
returned to the same feeding grounds across years. The average longitudinal dispersal ranges,
latitudinal dispersal ranges and average direct distances between marks and recaptures were:
13°06′ and 7°15′; 1°23′ and 0°47′; and 361 n.miles and 199 n.miles for males and females,
respectively. The time spans ranged from 3–13 years with an average of 6.7 and 7.8 years formales and females, respectively. Sampling and matching occurred in an area where visual surveys showed aggregations of southern right whales associated with high krill concentration.
The study conﬁrms the feasibility of the genetic approach, but more deﬁnitive inferences onsite ﬁdelity and movement ranges will require a large number of biopsy samples genotyped,
from both south and north of 60°S.
Key words:

southern right whales, Antarctic, genetic tagging, site ﬁdelity, movement, distribution.

Introduction
Baleen whales are important components of the Antarctic marine ecosystem as top predators. Substantial changes in their abundance and distribution, for example due to past whaling or more recently
climate change, aﬀects the entire ecosystem. For this reason, systematic monitoring of baleen whale
abundance, pattern of movement and distribution in Antarctic waters is important.
A substantial amount of biological and ecological information on large whales and their environment was obtained in the Indo-Paciﬁc sector of the Antarctic (35°E–145°W) by the ‘Japanese Whale
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PASTENE, GOTO, TAGUCHI AND MATSUOKA

Research Program under Special Permit in the Antarctic’ Phases I and II (JARPA, JARPAII) and thesubsequent ‘New Whale Research Program in the Antarctic’ (NEWREP-A). These were conductedannually under the auspices of the Government of Japan between the 1987/88 and 2018/19 australsummer seasons under Article VIII of the International Convention for the Regulation of Whaling(ICRW). Most of the demographic and ecological analyses conducted under these research programs
targeted the Antarctic minke whale (Balaenoptera bonaerensis) and other Balaenopterid species (seesummaries of results in Murase et al. (2020) and Fujise and Pastene (2021)). In the context of thispaper, southern right whale (Eubalaena australis) sightings were recorded and where possible, photo-identiﬁcation and genetic samples were collected.
A further important source of information from Antarctic waters is the sightings, photo-identiﬁcation and biopsy data collected at the circumpolar level by the International Whaling Commission-International Decade for Cetacean Research/Southern Ocean Whale and Ecosystem Research (hereafter
IWC-IDCR/SOWER) surveys conducted between the 1978/79 and 2009/10 austral summer seasons.
Photo-identiﬁcation data and biopsy samples of species including southern right whales were collected
opportunistically during the IDCR/SOWER.
This study focuses on the southern right whales. The species has a circumpolar distribution. They
spend the austral winter in inshore waters of South America, South Africa and Australasia; in springwhales move south to spend the austral summer feeding in waters around Antarctic before returning
north in the autumn (Reeves et al., 2002). They can reach a maximum body length of 17 m and the
body length at birth is 4–4.6 m. They are believed to live more than 70 years and calves are produced
every 3–5 years (Reeves et al., 2002). The primary breeding grounds are located at South Africa,
South West Australia, Argentina, and New Zealand Sub-Antarctic (IWC, 2001; 2013; Carroll etal., 2016). Research eﬀort to investigate stock structure, distribution and abundance trend has focused
mainly on the breeding grounds, and limited information exists on the distribution, site ﬁdelity andmovements in the feeding grounds, and on the connection between breeding grounds in low latitude
waters and higher latitude feeding grounds.
Migration patterns, movements and feeding ground destinations have been studied using direct
approaches including photo-identiﬁcation and more recently, telemetry as well as indirect approaches
such as visual surveys and historic whaling records. Telemetry has been used to investigate movement
patterns of South African right whales (Mate et al., 2011) and western South Atlantic right whales(Zerbini et al., 2016; 2018). The telemetry and photo-identiﬁcation (e.g., Best et al., 1993) studies in
the Argentina and South African breeding grounds show that southern right whales are found throughout large areas of the South Atlantic Ocean and visit several potential feeding areas each season.
The focus of the present paper is the Indian Ocean sector of the Antarctic, between 80°–135°E,
south of 60°S. Previous studies have shown that animals from that sector are associated with breeding
grounds in the Australasian region (e.g., IWC, 2001; 2013). For example, Bannister (2001) reviewed
the distribution and movement of ‘Australian’ southern right whales based on historical whaling data,
recent sighting surveys, 1960s Soviet catch data and photo-identiﬁcation data. The review conﬁrmed
the traditional view of seasonal movements to and from coastal breeding grounds in warm waters andfeeding grounds in colder waters. In terms of direct evidence, he presented two photo-identiﬁcation
matches, the ﬁrst made between whales identiﬁed of either Western Australia or South Australia in
winter/spring and waters around 40°–44°S; 116°–125°E where a sighting of 35 animals had been madein December–January 1995–96 (Bannister et al., 1997). The other evidence was a southern right whale
photographed at 64°26′S; 114°54′E in February 1996, which had been identiﬁed over a period of 18
years on the coast of Western Australia (Bannister et al., 1999). These data suggest that at least someof the summer feeding aggregation of southern right whales in the Antarctic Indian Ocean sector belong to the South West Australian population.
Most recently, Mackay et al. (2020) presented telemetry information of six animals tagged in Australasian wintering grounds. They suggested at least three probable foraging grounds: to the southwest

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GENETIC MATCHES OF SOUTHERN RIGHT WHALES

of Western Australia, the Subtropical Front and Antarctic waters—the Subtropical Front appearing to
be a feeding ground for animals from both New Zealand and Australian waters. They also suggested
that the observed variable population growth rates between wintering grounds in Australasia might
reﬂect ﬁdelity to diﬀerent quality feeding grounds. Thus, similar to results from the South African andArgentina breeding grounds, Australasian animals appear to visit multiple potential feeding areas eachseason.
A high concentration of sightings of southern right whales was observed in the Indian sector (80°–135°E) of the Antarctic Ocean during various austral summer season cruises of JARPA and JARPAII(Matsuoka and Hakamada, 2020) and the IWC-IDCR/SOWER cruises. Biopsy samples collected
opportunistically during the IDCR/SOWER and JARPA/JARPAII surveys in that sector were used in
the present study on genetic matching based on microsatellite DNA (msDNA). The main objective of
the individual identiﬁcation based on genetic matching was to evaluate the utility of this approach to
study site ﬁdelity and ranges in this species. The use of genetic markers (‘tags’) has long been shown
to represent a viable alternative/supplement to photographic methods of individual recognition—suchmarkers are permanent in all individuals (Palsbøll et al., 1997a).

Materials and methods
Samples
A total of 157 skin/blubber biopsy samples were obtained opportunistically from free-ranging
southern right whales along the sighting surveys of JARPA/JARPAII (n=108) and IWC-IDCR/SOWER (n=49) in the Antarctic Indian sector (80°–135°E), south of 60°S from the 1993/94 to 2015/16
austral summer seasons. A variety of collection systems was used including crossbows, air guns andmodiﬁed shot guns, all using modiﬁed collection darts that took a small sample of skin and blubber.
The geographical distribution of the southern right whales sampled is shown in Fig. 1.
DNA extraction
Genomic DNA was extracted from approximately 0.05g of the outer epidermal layer of the skin tissue using standard phenol/chloroform protocols (Sambrook et al., 1989) or using Gentra Puregene kits
(QIAGEN). Extracted DNA was stored in TE buﬀer (10mM Tris-HCl, 1mM EDTA, pH 8.0).

Fig. 1. Geographical distribution of southern right whales in the Indian Ocean sector of the Antarctic examined in this study. Red: females; Blue: males. SWA: South West Australia. Light blue shading shows the ice
conﬁguration.
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PASTENE, GOTO, TAGUCHI AND MATSUOKA

Laboratory procedure for msDNA
Genetic variation was examined at 14 msDNA loci: EV1, EV14, EV21, EV37, EV94 (Valsecchi
and Amos, 1996), GT23, GT211, GT310 (Bérubé et al., 2000), GAT A28 (Palsbøll et al., 1997b), DlrFCB17 (Buchanan et al., 1996), TR3G2, TR2G5, TR2F3 and TR3F2 (Frasier et al., 2006). Details of
the laboratory work for msDNA are provided in Pastene and Goto (2016).
Laboratory procedure for mtDNA
Mitochondrial DNA (mtDNA) control region sequences were used as one way to conﬁrm individual
identiﬁcation by nuclear markers. Samples sharing a same genotype should also share a same haplotype.
The ﬁrst 470 base pairs (bp) at the 5′ end of the mtDNA control region were ampliﬁed by polymerase chain reaction (PCR). Details of the laboratory work for mtDNA sequencing are provided in
Pastene and Goto (2016).
Laboratory procedure for sex determination
Sex determination is important both to examine potential sex-speciﬁc patterns of movement as wellas an additional way to conﬁrm individual msDNA matching. Samples sharing the same genotype
should be of the same sex. The SRY locus located on the Y chromosome was used for sex determination following the method of Abe et al. (2001) with a slight modiﬁcation (see Milmann et al., 2021).
Analytical procedure
MtDNA
Variable sites and unique sequences (haplotypes) were identiﬁed using the program MacClade(Maddison and Maddison, 1989).
MsDNA
The computer program MICRO-CHECKER (van Oosterhout et al., 2004) was used to check fornull alleles and reading/typing errors. The probability that two unrelated individuals have identicalgenotype (i.e., an identical genetic ‘tag’) is negatively correlated with the number of loci analysed andthe degree of variation at each locus (Palsbøll, 1999). For this reason, it is important the estimationsof the nuclear DNA diversity of southern right whales at each msDNA locus, as well the probability ofidentity (I). The latter is the probability that two unrelated individuals from the same panmictic population have an identical composite genotype (see Paetkau and Strobeck, 1994). The I was estimatedper locus and across loci. The number of alleles per locus, inbreeding coeﬃcient (FIS) and expected
heterozygosity (HE) per locus was calculated using FSTAT 2.9.3 (Goudet, 1995). Statistical tests forthe deviations from expected Hardy–Weinberg genotypic proportions were conducted using GENEPOP 4.0 (Rousset, 2008), both by each locus and for all loci combined. Individuals with identicalmulti-locus genotypes sampled during the same sighting (duplicates) were investigated, and one fromeach duplicate was removed for subsequent analyses.

Results
Final dataset
There were four cases of biopsies with identical multi-locus genotypes sampled during the samesighting (duplicates). There were two cases of mother-oﬀspring pairs, which were deduced from observations at the ﬁeld and from genetic data. After removing four duplicates, the sample sizes for the
msDNA analyses on individual identiﬁcation was 153 (76 males and 77 females).

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Level of msDNA diversity and probability of identity
No evidence of null alleles and typing/reading errors was found. Table 1 shows the estimated msDNA diversity indices. The number of alleles per locus ranged from 2 to 14 (average 7.5), and the HE
ranged from 0.07 to 0.89 (average 0.65). The FIS in each locus ranged from −0.035 to 0.162 (average
0.007). There was no signiﬁcant deviation from the Hardy–Weinberg genotypic proportion. I for eachlocus ranged from 0.022 at DlrFCB17 to 0.861 at EV21, which was estimated to be 1.95×10−10 when
all loci were combined.
Genetic matching
As shown in Table 2, eight matches were detected (four males and four females). The multi-locus
genotype matches were supported by mtDNA (same haplotype), sex determination (same sex), and, inthe two cases where pictures were available, by photo-identiﬁcation matches (Fig. 2).
Site-ﬁdelity and movement range
Figs. 3A–B show the geographical distribution of the matches of female and male southern rightwhales, respectively. Table 2 summarises the matches and associated data. The elapsed time between
sample and re-sample ranged between 3 and 13 years (average 7.25 years). In the case of females, therange was 3–11 years (average 7.75 years) and, in the case of males 4–13 years (average 6.75 years).
The average longitudinal dispersal ranges were 13°06′ and 7°15′ in males and females, respectively.
The average latitudinal dispersal ranges were 1°23′ and 0°47′ in males and females, respectively (Table 2). The average direct distances between sample and re-sample positions were 361 n.miles and
199 n.miles for males and females, respectively (Table 2). A statistical test showed no signiﬁcant differences between females and males in the direct distances between samples and re-samples (W=14,
Mann-Whitney, p=0.114).

Table 1. Indices of microsatellite DNA diversity in southern right whales from the Indian sector of the Antarctic: A: number of alleles; HE: expected heterozygosity; HW: P-value for the test of Hardy-Weinberg equilibrium; FIS: inbreeding coeﬃcient; and I: probability of identity.
Microsatellite loci

A

HE

HW

FIS

I

EV1
GT310
GT23
EV94
EV14
GT211
EV37
GATA28EV21
DlrFCB17
TR2F3
TR3G2
TR2G5
TR3F2

14
6
8
5
10
10
11
10
3
13
2
8
2
3

0.87
0.62
0.81
0.41
0.76
0.82
0.82
0.77
0.07
0.89
0.49
0.77
0.50
0.48

0.25
0.05
0.96
0.78
0.14
0.08
0.95
0.28
0.10
0.54
0.62
0.52
0.14
0.68

0.010
0.057
0.024
−0.0210.006
0.077−0.0170.006
0.162−0.0190.044−0.035−0.123
0.055

0.025
0.205
0.059
0.401
0.076
0.055
0.046
0.090
0.861
0.022
0.379
0.093
0.376
0.361

0.65

0.21

0.007

1.95e-10

Overall

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Table 2. Cases of sample/re-sample in southern right whales from the Indian sector of the Antarctic determined by microsatellite DNA genotyping. All genotype matches were supported by the mtDNA analysis(same haplotypes) and by the results of sex determination (same sex). Cases 2 and 3 (the only ones for whichphotographs were available) were conﬁrmed by photo-identiﬁcation, SR: sample/resample; ID: label of thewhale; S: sex; BL: body length determined visually by researchers from the vessels (in meters); ET: elapsed
time (year) between samples and re-samples; DD: direct distance between the positions of samples andre-samples (in n. miles); LAR: latitudinal dispersal range between samples and re-samples; LOR: longitudinal
dispersal range between samples and re-samples.
SR

ID

S

BL Date (D/M/Y)

Position

ET

DD

LAR

LOR

1

Sample93IVR004
Re-sample 98SWR046

M
M

14.3
14.3

05/03/1994
31/01/1999

64°14′S
62°40′

113°04′E99°30′

5377

1°34′ 13°34′2Sample97IVR007
Re-sample 01IVR023

M
M

11.9
12.9

15/01/1998
15/02/2002

62°55′
64°36′

100°28′92°15′

4

241

1°41′

3

Sample99IVR012
Re-sample 07IVR56

F
F

16.4
15.3

10/02/2000
01/03/2008

64°35′
64°54′

114°31′126°17′8

303

0°19′ 11°46′

4Sample98SWR140
Re-sample 01IVR018

F
F

13.4
13.3

05/02/1999
14/02/2002

63°19′
64°30′

103°28′93°50′

3

265

1°11′

5

Sample01IVR024
Re-sample 14AJ4R036

M
M

13.2
13.7

15/02/2002
28/02/2015

64°36′
64°05′

92°15′
111°02′13490

0°31′ 18°47′

6Sample98SWR137
Re-sample 07IVR49

F
F

13.1
12.8

02/02/1999
22/02/2008

63°00′
64°03′

100°50′95°29′

9

157

1°03′

5°21′

7

Sample98SWR141
Re-sample 09SWR011

F
F

12.8
13.2

07/02/1999
29/01/2010

63°55′
64°31′

105°42′107°58′

11

69

0°36′

2°16′

8

Sample09SWR008
Re-sample 14AJ4R004

M
M

13.2
12.7

24/01/2010
22/02/2015

64°27′
62°40′

111°38′99°47′

5335

1°47′ 11°51′

8°13′

9°38′

Discussion
Previously Carrol et al. (2016) carried out successfully a genetic matching study in southern rightwhales of the New Zealand nursery ground. The study presented here is the ﬁrst of such kind in southern right whales of the Indian sector of the Antarctic. Results of the Hardy–Weinberg equilibrium test
suggest that whales in this sector belong to the single putative ‘South Western Australia’ population
earlier identiﬁed by the IWC Scientiﬁc Committee (IWC, 2001; 2013) based upon inter alia resultsof photo-identiﬁcation matches (Bannister et al., 1999; Bannister, 2001). Individual identiﬁcation by
genetic matching has the potential to contribute to studies on movement and site ﬁdelity in this population. Here, some relevant aspects of this approach and its utility for southern right whales are discussed.
Utility of genetic matching for individual identiﬁcation of southern right whales
The number (n=14) of msDNA loci used in the present study and the degree of polymorphism(see Table 1) proved to be appropriate for the purpose of individual identiﬁcation in southern rightwhales. There was a very low estimated probability of identity i.e., two unrelated individuals having
an identical composite genotype. The eight cases of genotyping matching were supported by the mtDNA analyses (same haplotype) and sex determination (same sex). In addition, for the two cases where
photographs were available, genotyping matching was supported by photo-identiﬁcation. The authors
conclude that the eight cases of genotyping matching corresponded to matching of the same individual whales and thus conﬁrms the utility of genetic matching to identify individuals (see also Carrol etal., 2016).

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Fig. 2 A: A southern right whale sighted in the Indian sector of the Antarctic on 15 January 1998 (left) andre-sighted in the same sector on 15 February 2002 (right) (Matching No. 2 in Table 2). B: A southern rightwhale sighted in the Indian sector of the Antarctic on 10 February 2000 (left) and re-sighted in the same sector
on 1 March 2008 (right) (Matching No. 3 in Table 2).

Fig. 3. Maps showing sample/re-sample positions referred to in the text. A: females–note that match 2002–
2008 was also conﬁrmed by photographs. B: males–note that match 1998–2002 was also conﬁrmed by photographs. Light blue shading shows the ice conﬁguration.

Utility for studies on site ﬁdelity and movement ranges of southern right whales
The eight matches here show that at least some females and males visit the same feeding groundin the Indian sector of the Antarctic south of 60°S in summer. The total samples and the matches bothwere close to 1 : 1 males and females. Although the direct distances between sample and re-sample
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PASTENE, GOTO, TAGUCHI AND MATSUOKA

by sex were statistically non-signiﬁcant, this probably relates to the small sample size. Qualitatively(Table 2 and Fig. 3), the results are not in conﬂict with the ﬁndings of Carroll et al. (2011) that males
are more mobile than females.
As explained earlier, telemetry data from southern right whales tagged in breeding grounds inAustralasia (Mackay et al., 2020), South Africa (Mate et al., 2011) and Argentina (Zerbini et al.,2016; 2018) suggested that individuals may visit several feeding grounds within the same season e.g.,
in middle latitudes and high latitudes, and this aspect of southern right whale’s ecology should beconsidered when discussing site ﬁdelity. The abundance of southern right whales in the Indian sectorof the Antarctic was estimated as 910 in 1988/89 from sightings data (95% CI: 409–2,026) (Matsuoka
and Hakamada, in press) and the number of individuals identiﬁed in this study was 145 (153 minus
eight individuals re-sampled). This corresponds to about 16% (range between about 1–36% of the estimated total population). The low number of matches limits the applicability of inferences on relativesite ﬁdelity and the pattern of longitudinal dispersal to the total population. The comparison above
should be seen with caution. The 1988/89 estimate has wide conﬁdence intervals and the biopsy sampling is pretty wide and carried out after the abundance estimates.
Whilst the present study conﬁrms the feasibility of the approach, it is clear that more deﬁnitive inferences on site ﬁdelity and movement ranges will require a larger number of biopsy samples, fromboth south and north of 60°S (all the samples in this study were obtained south of this latitude).
Food availability in the area of genetic matching
Recognizing the limited number (and sampling distribution) of samples, the present results allow
the formulation of the following ecological inferences for further investigation. The Indian Ocean
sector of Antarctic waters south of 60°S represents one of the several possible feeding grounds for theSouth West Australia population (e.g., see Mackay et al., 2020). Our results show that at least somesouthern right whales of both sexes return to the same sector at some point in their lives, presumably
for feeding. Matches were found in a broad area that has shown consistent annual aggregations ofsouthern right whales (e.g., Matsuoka and Hakamada, 2020) and that were seen in areas of high krill
concentrations (e.g., Murase et al, 2002; Matsuoka et al., 2003; Nicol, 2006).
Qualitative analyses of food consumption of southern right whales in the Antarctic Indian sector
could be investigated by stable isotope analyses of the same biopsy samples used in the present study.
Information on prey species consumed by southern right whales will assist in conﬁrming the ecological inference aforementioned.
Finally, genotyping data in this study can be used for other purposes, for example to estimate abundance and other demographic parameters (e.g., survival rates) of this species within a mark-recapture
context (e.g., Wade et al., 2010).
Acknowledgements

We thank Japanese and international researchers that participated in the JARPA/JARPAII and IDCR/SOWER research
programs for their eﬀort in collecting biopsy samples and for obtaining the ancillary data used in this study. Our gratitude
to Naohisa Kanda for his work on msDNA genotyping. We also thank Shigetoshi Nishiwaki (ICR) for starting the biopsy
sampling of this species in the Antarctic, and for useful comments on southern right whale ecology. Our gratitude to Tatsuya
Isoda (ICR) for his assistance in ﬁgure drawing and Kenji Konishi (ICR) for statistical assistance. Finally, we thank the anonymous reviewers and Greg P. Donovan for their comments and suggestions that improved substantially previous versions of
this paper.

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Received: September 25, 2020
Accepted: August 5, 2021
Published online: November 9, 2021

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J-STAGE Advance published date: January 31, 2021

EVALUATION OF A PATERNITY METHODEVALUATION OF A PATERNITY METHOD BASED ON
MICROSATELLITE DNA GENOTYPES FOR
ESTIMATING THE ABUNDANCE OF ANTARCTICMINKE WHALES (BALAENOPTERA BONAERENSIS) IN
THE INDO-PACIFIC REGION OF THE ANTARCTIC
Yumi OHASHI1, Mutsuo GOTO2, Mioko TAGUCHI2,
Luis A. PASTENE2, 3 and Toshihide KITAKADO1*
1

Tokyo University of Marine Science and Technology, 4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
3
Project Microbiomes as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia,
Centro de Estudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA),
Punta Arenas, Chile*Corresponding author: kitakado@kaiyodai.ac.jp

Abstract
This study describes a paternity method based on microsatellite DNA genotypes to estimate the abundance of mature male Antarctic minke whales (Balaenoptera bonaerensis) in
the Indo-Paciﬁc region of the Antarctic using a maximum likelihood approach. The analyses
were based on biological and genetic (microsatellite DNA at 12 loci) data from Antarctic
minke whales collected by surveys of the Japanese Whale Research Program under Special
Permit in the Antarctic-Phase II (JARPAII) in the Indo-Paciﬁc region of the Antarctic. A total of 2,126 Antarctic minke whales taken in the austral summer seasons 2006/07, 2008/09,
2009/10, 2010/11 and 2011/12 from locations 35°E to 145°W were used in the analyses. The
abundance of mature males estimated by this method was then extrapolated to estimate totalabundance for comparison with results for abundance obtained using conventional line transect methods in the research area. The total abundance derived from the paternity method(ca. 210,000–220,000) was generally lower than that obtained by the line-transect method(ca. 260,000–410,000), although the ﬁgure from the line-transect method was within the 90%
conﬁdence interval of the estimates by the paternity method, and the area covered by bothmethods was slightly diﬀerent. Additionally, the geographical locations of mother/fetus–father
pairs provided the opportunity to evaluate the current hypothesis on population structure ofthis species in the Indo-Paciﬁc region. Results for the geographical distribution of mother/fetus–father pairs were generally consistent with the hypothesis of separate Eastern Indian
Ocean and Western South Paciﬁc Ocean populations, because 8 of 10 pairs were found in the
expected areas of distribution of either populations. However, two pairs were found in distantareas. As a whole, the results from the present study demonstrated the utility of the paternity
method for estimating the abundance of Antarctic minke whales and for assisting the interpretation of population structure hypotheses.
Key words:

Antarctic minke whale, paternity analysis, population structure, microsatellite DNA.

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Introduction
Population abundance and trajectories provide key information required for eﬀective conservationand management of wildlife. In the case of whaling, the International Whaling Commission (IWC)
developed and adopted the Revised Management Procedure (RMP), a single-species management
procedure1 for calculating commercial catch limits for whaling of baleen whales (Anon, 1994; Punt
and Donovan, 2007). The RMP consists of a series of rules to manage whaling (including multi-stock
scenarios), based largely upon catches determined by a simple generic Catch Limit Algorithm (CLA),
that requires two kinds of information: a time series of abundance estimates and catch-history data.
The key to the approach is that the CLA was rigorously tested by simulation to ensure that it is robust to inevitable scientiﬁc uncertainty, while the implementation of the RMP in speciﬁc multi-stock
situations is also tested by simulation to ensure robustness to evaluate uncertainty in key parameters(known as Implementation Simulation Trials, ISTs). The catch limits set by the CLA take into accountthe uncertainty in the abundance estimates and thus it is important to obtain abundance estimates withgood precision. Abundance information about whales is also required for the development of ecosystem models and multi-species management procedures.
In recent decades, visual surveys using ‘Distance sampling’ approaches (e.g., Buckland et al., 2001)
have been the most common method for estimating the abundance of cetacean species. Amongst otherassumptions, this approach depends upon an assumption that all animals on the trackline are seen (orcan be corrected for the actual detection probability on the trackline—the so-called g(0) value). It isalso assumed that, for estimating trends in a population (rather than trends within a geographical area),
the full population is surveyed each time (diﬃcult for wide-ranging species such as cetaceans). A good
example of the complexity in the use of the line-transect method was the assessment of Antarctic minke whales by the IWC Scientiﬁc Committee (SC), based on three Antarctic circumpolar surveys conducted under the International Decade of Cetacean Research and Southern Ocean Whale and Ecosystem Research (IDCR/SOWER) programs. Obtaining robust abundance estimates from these surveys
and then interpreting the results triggered a decade-long discussion in the IWC SC about the methodof estimating g(0) and possible distributional shifts of whales over time e.g. to unsurveyed areas beyond the ice-edge of the survey region that prevents vessels entering (IWC, 2013).
Mark–recapture methods based on internal marks (Discovery type, e.g., see Buckland andDuﬀ, 1989) or individual identiﬁcation by photographic matching (e.g., Hammond et al., 1990) canbe used to estimate some marine mammal population sizes (Sobtzick, 2010). However, in the case of
Antarctic minke whales the former method is not possible because there are no current catches of thisspecies. Obtaining suﬃcient photographs for photographic identiﬁcation and then matching them isconsiderably more diﬃcult for Antarctic minke whales than say, humpback, right and blue whales.
Given the limitations mentioned above, alternative methods are being investigated for estimating
the abundance of whales. Mark–recapture approaches based on genetic individual identiﬁcation frombiopsy samples have been used to estimate population abundance and to examine the migration patterns of whales (e.g., Palsbøll, 1999). Whilst valuable for smaller populations, the logistics of obtaining a suﬃciently large sample size make it often impractical for large populations.
The most promising recent technique involves paternity testing. For paternity analyses, DNA proﬁles of mother/fetus, usually from a set of microsatellite loci, are used to look for potential fathers of
the fetuses within the sample population. If their fathers are found, the number of matches can be usedin traditional mark–recapture analyses (e.g., see Skaug and Øien, 2004). Paternity analysis and closekin mark–recapture methods based on genetic data have been used to estimate the abundance of North
Atlantic humpback whales (Palsbøll et al., 1997; Nielsen et al., 2001).
This study describes a paternity method based on microsatellite DNA genotypes to estimate the abun1

Sometimes in ﬁsheries the term ‘management strategy’ is used.

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dance of mature male Antarctic minke whales in the Indo-Paciﬁc region of the Antarctic using a maximum
likelihood approach. Mature male abundance is extrapolated to total abundance and the estimates compared with those obtained from conventional line-transect methods in the same research area. The paper
also identiﬁes additional research required to improve the precision of the paternity method for abundance
estimate purposes. Finally, the geographical locations of mother/fetus–father pairs are used to evaluate thecurrent hypothesis on population structure of this species in the Indo-Paciﬁc region of the Antarctic.

Materials and methods
Samples
Samples from a total of 2,126 Antarctic minke whales were available from the surveys of theJapanese Whale Research Program under Special Permit in the Antarctic-Phase II (JARPAII) in the
austral summer seasons 2006/07, 2008/09, 2009/10, 2010/11 and 2011/12. The surveys were conducted in the Indo-Paciﬁc region of the Antarctic, in the IWC Management Areas (see Donovan, 1991)
IIIE (35°–70°E), IV (70°–130°E), V (130°E–170°W) and VIW (170°–145°W) (Fig. 1). For each sampled whale, the following information was available: sample ID, sampling date, sampling location(latitude and longitude), sex and maturity, occurrence of fetus, age and the quality of the age estimation.
The details of the samples used in the analyses are presented in Table 1.
Microsatellite DNA
Each sample (including fetuses) was genotyped using 12 microsatellite DNA loci: EV1, EV104,
GT211, DlrFB14, GT195, GT23, AC045, AC082, AC087, AC137, CA234 and GT129. The details of
the laboratory work for DNA extraction and microsatellite DNA genotyping were reported by Pastene
and Goto (2016). Loci CA234 and GT129 were excluded from the present analyses because of theexistence of null alleles and genotyping errors. Individuals with missing allele data on some loci (576
animals) and some mother/fetus pairs that had mismatching alleles (37 animals) were also excluded
from the statistical analysis.

Fig. 1. IWC management Areas IIIE, IV, V and VIW where the study was conducted. The ﬁgure also shows aschematic representation of the hypothesis of population structure of Antarctic minke whale in the Indo-Pacific region of the Antarctic. At least two populations occur in this region, the Eastern Indian Ocean Population(I) and the Western South Paciﬁc Ocean Population (P), which overlap in a transition area.
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Table 1. Number of sampled individuals used in the analysis. Individuals which had missing data for one ormore loci were excluded from the analysis.

FemaleArea

2006/07

2008/09

2009/102010/112011/12

With fetus(Mother/fetus pair)

IIIE–VW
VE–VIW

0
242

0
43

156
0

0
78

12
79

Immature or mature but
without fetus

IIIE–VW
VE–VIW

0
106

3
63

71
0

0
30

38
38

IIIE–VW
VE–VIW

1331
2651

IIIE–VW
VE–VIW
Mature male
Male

1502
1452

IIIE–VW
VE–VIW

1513
793

IIIE–VW
VE–VIW

Immature male

334
834

IIIE–VW
VE–VIW

0
128

5
71

120
0

0
46

36
37

IIIE–VW
VE–VIW

0
24

5
31

46
0

0
16

13
13

The total number of mature males aged ≥6 years in 2006/07; 2 The total number of mature males aged ≥6 years in 2008/09; 3 The total
number of mature males aged ≥6 years in 2009/10; 4 The total number of mature males aged ≥6 years in 2010/11.
1

Assumptions on population structure
Abundance estimates developed using the paternity method are presented here under two assumptions: (i) no population structure; and (ii) population structure based on the hypothesis proposed by
Pastene and Goto (2016). Regarding (ii), the IWC SC (IWC, 2008) has agreed that there are at least
two genetically distinct populations in this region, one in the east (Paciﬁc or P-population) and theother in the west (Indian or I-population) with a ‘soft’ boundary between these populations in Areas
IVE and VW, which changed by year and sex. For practical purposes, the present study assumes that
the I-population is distributed from Area IIIE to Area VW, and the P-population from Area VE to Area
VIW. Fig. 1 shows a schematic representation of the population structure of Antarctic minke whales in
the Indo-Paciﬁc region, and its relation with IWC Management Areas.
Identiﬁcation of father from mother/fetus genotype proﬁles
The ﬁrst step in the process of using the paternity method to estimate abundance is to examine themicrosatellite DNA proﬁles of the mother/fetus pairs to look for potential fathers within the total sample. The probability of the fetus’s genotype at each locus, given the mother’s and potential father’s
genotype, was calculated following Marshall et al. (1998). Table 2 shows the conditional probabilities
for all compatible mother/fetus–potential father pairs. The possibility of a male being the true father isrejected when the probability of the fetus’s genotype is 0. In this study, 10 loci were used for the estimation, and the 10 probabilities for the fetus’s genotype multiplied. When the results are greater than0, the potential father is considered the true father.
To aid interpretation, the sexual maturity of the males was considered. Males aged six years old orolder were deﬁned as mature males (Tamura and Konishi, 2014; Murase et al., 2020) and the sensitivity of the results to using deﬁnitions of seven and eight years old was also examined.
The geographical positions of mother/fetus and true father pairs were mapped using Generic Map-

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Table 2.

Conditional probabilities for all compatible mother/fetus–potential father pairs.

Fetus’s
genotype (go)Potential father’s
genotype (gp)

Mother’s
genotype (gm)Pr(go|gm,gp)

Pr(go|gm)

BB
BB
BB
BB
BC
BC
BC
BC
BC
BC
BC

BB
BX
BB
BX
BB
BX
BB
BX
BB
BY
BC

BB
BB
BX
BX
CC
CC
CY
CY
BC
BC
BC

1
1/2
1/2
1/4
1
1/2
1/2
1/4
1/2
1/4
1/2

b
b
b/2
b/2
b
b
b/2
b/2
(b+c)/2(b+c)/2(b+c)/2

X represents any allele other than B; Y represents any allele that is neither B nor C. The frequencies of alleles B and C are denoted b and c.
Pr(go|gm,gp) is the probability of the fetus’s genotype given the mother’s and alleged father’s genotypes and Pr(go|gm) is the probability of
the fetus’s genotype given the mother’s genotype (Marshall et al., 1998).

ping Tools (GMT2) (Fig. 2).
Likelihood function for estimating the number of mature males
The likelihood function for the abundance of mature males was obtained as described by Nielsen
et al. (2001). Assuming Ij (i) is the event that the jth potential father is the true father of the ith fetus,
I0 (i) is the event that the potential father is not in the samples, Mi is the ith maternal genotype, Oi is
ith associated genotype of the fetus, Fj is the genotype of the jth potential father, A is the matrix ofallelic frequencies for all loci, N is the abundance of mature males in the area and n is the number ofsampled mature males, then the likelihood function for N is expressed as:
L(N ) ∝

∏ Pr (O | M , F , A, N )
i

i

i

=

∏
i

=

∏
i

 (N − n)

1 n
Pr
(
|
,
)
Pr (Oi | M i , F j ) 
+
O
M
A

i
i
 N

N j=1


n
 (N − n)1
Pr ( Oi |M i , A, I 0 (i ) ) +Pr ( Oi | M i , F j , I j (i ), A, N )  for N > n.

 N

N j=1







(1)

Here, ∑nj=1 Pr (Oi|Mi,Fj) refers to the sum of the probabilities that the father of the ith fetus is the jthpotential father when the ith maternal genotype and the jth potential father are given, and Pr (Oi|Mi,A)
refers to the probability of the ith fetus’s genotype given the ith mother’s genotype. The point estimateof N was computed by maximizing the logarithm of L(N), and the 90% conﬁdence interval of N was
calculated by the likelihood proﬁle as {N; log L(N)≥log L(N̂)−0.5χ 2 (0.10)}, where χ 2 (0.10) is the10th upper percentile of chi-square distribution with the degree of freedom 1.
To estimate the total abundance of Antarctic minke whales, the total was prorated based upon the
proportions of males and females, and immature and mature whales, from the sampled data, under theassumption that the sample was representative of the true population (by assuming an equal selectivity
from the population(s)). The proportion of male whales was 0.436 for the case of a single population,and 0.491 and 0.407 for I- and P-populations, respectively. Also, the proportion of immature whales
2

https://www.generic-mapping-tools.org/

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Fig. 2A. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2006/07
and the triangle indicates a male caught in 2006/07. The red and blue boxed numbers are the ages of female
and male, respectively.

Fig. 2B. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2006/07
and the triangle a male caught in 2008/09.

Fig. 2C. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2006/07
and the triangle a male caught in 2010/11.

under the assumption of knife-edge maturity-at-age six years old was 0.254 for a single population,and 0.299 and 0.225 for I- and P-populations, respectively. For a sensitivity test, eight years old wasused as the maturity age. In this case the immature proportion was 0.317 for a single population, and
0.366 and 0.286 for I- and P-populations, respectively.

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Fig. 2D. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2006/07
and the triangle a male caught in 2011/12.

Fig. 2E. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2006/07
and the triangle a male caught in 2011/12.

Fig. 2F. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2009/10
and the triangle a male caught in 2009/10.

Results
Mother/fetus and mature male pairs
A total of 10 mother/fetus–father pairs were identiﬁed under the assumption of a maturity age of six
years old. There were no cases of multiple fathers for one fetus. True fathers were found for ﬁve mothers/fetuses caught in 2006/07 and ﬁve mothers/fetuses caught in 2009/10.
The location of the matching pairs is shown in Figs. 2A–J. Eight pairs occurred in nearby geographical locations (Figs. 2A–H) while two pairs occurred in distant locations (Figs. 2I, J).
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Fig. 2G. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2009/10
and the triangle a male caught in 2009/10.

Fig. 2H. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2009/10
and the triangle a male caught in 2009/10.

Fig. 2I. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2009/10 andthe triangle a male caught in 2011/12.

The abundance of mature males (population structure information not considered)
Combining data for all years, N̂mature male was estimated to be 68,874 (90%CI=42,625–122,779).
The likelihood proﬁle is shown in Fig. 3. Using the ratios of males to females and immature to mature whales to estimate the total population, the total population size, N̂, was estimated as 211,600(90%CI=130,954–377,210).
The abundance of mature males (population structure information considered)
For the I-population and using data from the two relevant years (2009/10 and 2011/12), the estimat-

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Fig. 2J. Positions of a mother-fetus pair and its true father. The circle indicates a female caught in 2009/10
and the triangle a male caught in 2011/12.

Fig. 3. The likelihood proﬁle for N̂mature male using 10 loci and ﬁve years of mother-fetus pairs and mature males
for analysis without considering population structure (assumption of single population).

ed abundance of mature males N̂mature male was 10,478 (90%CI=4,662–32,212), and the total populationN̂ was 30,432 (90%CI=13,540–93,556). The likelihood proﬁle is shown in Fig. 4A.
For the P-population (2006/07, 2008/09, 2010/11 and 2011/12), the estimated abundance of mature males N̂mature male was 59,961 (90%CI=28,853–161,155), and N̂ was 189,946(90%CI=91,401–510,506). The likelihood proﬁle is shown in Fig. 4B.
There were 9 pairs when the age of sexual maturity in males was changed from six to eight years
old. Therefore, six years old was used for the subsequent analysis of abundance. Comparison of abundance estimates are summarized in Table 3.

Discussion
The main objective of this study was to apply a new paternity method based on maximum likelihood to estimate the abundance of the Antarctic minke whale in the Indo-Paciﬁc region of the Antarctic, and to evaluate this method by comparing the results with those obtained by line-transect methods
in the same region.
Estimates from the paternity methods
There are some technical issues that need to be considered with respect to the paternity method estimates presented here. A key factor relates to the issues that resulted in the exclusion of a considerable
amount of data due to the following reasons:Cetacean Popul. Stud. (CPOPS), Full paper
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Fig. 4A. The likelihood proﬁle for N̂mature male using 10 loci in Areas IIIE, IV and VW using ﬁve years of mother-fetus pairs and mature males for analysis (I-population under the assumption of two populations).

Fig. 4B. The likelihood proﬁle for N̂mature male using 10 loci in Areas VE and VIW using ﬁve years of motherfetus pairs and mature males for analysis (P-population under the assumption of two populations).

(1) genotyping errors indicated by mother/fetus pairs with clearly diﬀerent genotypes (37 pairs);(2) missing allele information for some loci (576 individuals), indicating a genotyping error; and(3) two loci with a high null allele frequency.
Presence of such genotyping errors and null alleles could cause reduction of matching cases, andtherefore the estimated abundance tends to be positively biased. Such errors and allelic dropout can beconsidered in statistical models. However, such technical drawbacks in the DNA experiment should
also be examined and, where possible, corrected so that updated data can be used in future analyses.
Data collected after the 2011/12 austral summer season should be also used.
For practical reasons, the assumption of population structure considered a hard boundary between
the I and P-populations. Reﬁned analyses should consider the probability of assignment of each individual to each population in the overlap area.
Finally, this method considered only the relationship between mother/fetus and father. If other relative categories such as siblings are incorporated into the analyses, then the estimation performance(precision and accuracy) could be improved (Bravington et al., 2016a; b).
Comparison with estimates from line-transect surveys
The preliminary results on abundance can be summarized as follows: i) there were no substantial
diﬀerences in abundance under the two assumptions on population structure; ii) there was a slight
diﬀerence in I-population estimate depending on the assumption for maturity age used, which gave an
impact on the candidate fathers and successful pairs; and iii) the abundance derived from the paternity

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Assumption/Data

JARPA/JARPAII(1989/90–2008/09,
Hakamada andMatsuoka 2014)

93,215(CV=0.35)

III–W III–E

Area III
V–W

56,699*(30,585–95,725)

55,237(CV=0.49)

30,432(90%CI=13,540–93,556)
45,637(90%CI=17,359–192,539)

VI–W

Area IV

207,012*(132,431–299,433)

183,915(CV=0.36)

VI–E

80,835(CV=0.37)

189,946(90%CI=91,401–510,506)
182,458(90%CI=87,924–488,166)

V–E

Area V

211,600(90%CI=130,954–377,210)
228,478(90%CI=137,936–422,368)

Area IV*An average (and the range in brackets) of a series of abundance estimates in Hakamada and Matsuoka (2014).

Line transect
methodIDCR/SOWER(1992/93–2003/04,
IWC 2013)

Paternity analysis Base casewith I- andP-populations
Sensitivity casePaternity analysis Base casewith single
population
Sensitivity case

MethodIWC Management Area

All the estimates were correctedby g(0)estimates. The interval inbrackets is a range of time series
estimates.

All the estimates were correctedby g(0) estimates. The CVs include the additional variance.

Maturity age=8 yrs old

Maturity age=6 yrs old

Maturity age=8 yrs old

Maturity age=6 yrs old

Remarks

Table 3. Results of abundance estimates for the Antarctic minke whales derived from the paternity analysis (in this paper) and a comparison with the estimates obtainedusing the line-transect method from the IWC SOWER programme (IWC, 2013, p.27) and JARPA/JARPAII (Hakamada and Matsuoka, 2014).

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method was similar or somewhat lower than that obtained by the line-transect method (Table 3). It
should be noted that this comparison was not straightforward because the research areas covered by
the two methods are not identical (for example, the western part of Area III and eastern part of Area
VI were not covered by the paternity method). The ﬁgure from the line-transect method, however,tends to be within the 90% conﬁdence interval of the estimates by the paternity method.
Possible advantage of the paternity analysis over the line transect method is a less demanding requirement of the coverage of the habitat area. In the line transect method, the survey is assumed tocover the whole habitat area while the genetic tagging does not require this condition strongly as far
as the sampling is randomly conducted. However, in the paternity analysis, false positive and/or false
negative in matching between mother/fetus and father is crucial, and therefore the method is subject
to over- or under-estimation depending on the quality of matching. Also, if the number of matchingis quite low and the population size is large, “recapture probability” and “actual number of recapture”
might be so low and it could cause a large extent of uncertainty in the abundance estimation. In fact,in our analyses, the matching occurred only in 10 pairs for hundreds of thousands of population size,and hence the 90% CI tends to be wide. To increase the recapture probability, other kinship deﬁnitions
such as half-sibling can be used for improving estimation performance. This warrants further extension of methods to simultaneously account for diﬀerent kinship types and population structure.
Inference of results for population structure hypotheses
The study oﬀered the opportunity to compare the information obtained from this study with the current population structure hypotheses for the Indo-Paciﬁc region. The geographical positions of mother/fetus–true father pairs are broadly consistent with the hypothesis of separate I- and P-populations. A
total of 8/10 pairs was found in the expected areas of distribution of either I- or P-population. For example, ﬁve pairs were found in the expected area of distribution of the P-population while three pairs
were found in the expected area of distribution of the I-population. In two cases, however, mother/fetus–true father pairs were found in quite diﬀerent feeding areas. In the ﬁrst case, the mother/fetus
was caught in the expected area of I population while the true father was found in the expected areaof the P-population. In the second case, the mother/fetus was caught in the expected feeding area of
the I-population while the true father was found in the expected area of the P-population. These two
examples are not inconsistent with the hypothesis of I- and P-populations, because it is expected thatsome whales move longitudinally within the feeding grounds, wherever they breed, and that such
movements are more marked in males (Kitakado et al., 2014; Murase et al., 2020).

Conclusion
The results from this study have demonstrated the utility of the paternity method for obtaining
abundance estimates of the Antarctic minke whale because the estimates are compatible with thoseobtained using the line-transect method. A number of ways to improve the estimates have been identiﬁed.
Acknowledgements

We thank the researchers and crew members who participated in the JARPAII surveys for collecting the data used in theanalyses. We also thank T. Bando (ICR) for facilitating age information for the Antarctic minke whales used in this study
and N. Kanda (Japan NUS, formerly ICR) for his laboratory work for microsatellite DNA genotyping. We acknowledge twoanonymous reviewers for comments and particularly Greg P. Donovan (IWC) for useful suggestions and editorial corrections
that improved this paper substantially.

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Received: March 25, 2020
Accepted: September 23, 2020
Published online: January 31, 2021

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J-STAGE Advance published date: May 24, 2021

TAGUCHI, GOTO, MILMANN, SICILIANO, TIEDEMANN AND PASTENENEW INSIGHTS INTO THE GENETIC STRUCTURE OF
SEI WHALES (BALAENOPTERA BOREALIS)
AT THE INTER-OCEANIC SCALE
Mioko TAGUCHI1*, Mutsuo GOTO1, Lucas MILMANN2, 3,
Salvatore SICILIANO4, Ralph TIEDEMANN5 and Luis A. PASTENE1, 6
Institute of Cetacean Research, Toyomi-cho 4–5, Chuo-ku, Tokyo 104–0055, Japan2
Grupo de Estudos de Mamíferos Aquáticos do Rio Grande do Sul (GEMARS),
Rua Bento Gonçalves 165, sala 1002, Torres, RS, 95560–000, Brazil
3
Applied Ecology and Conservation Lab, Programa de Pos-graduação em Ecologia e Conservação da
Biodiversidade, Departamento de Ciencias Biológicas, Universidade Estadual de Santa Cruz (UESC),
Rodovia Jorge Amado, km 16, Ilhéus, BA, 45662–900, Brazil
4
Fundação Oswaldo Cruz/Fiocruz, Av. Brasil, 4.365 & Grupo de Estudos de Mamíferos Marinhos daRegião dos Lagos (GEMM-Lagos), Rio de Janeiro, RJ 21040–900, Brazil
5
Unit of Evolutionary Biology/Systematic Zoology, Institute of Biochemistry and Biology, University of
Potsdam, Karl-Liebknecht-Str. 24–25, Haus 26, 14476 Potsdam, Germany
6
Project Microbiomes as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia, Centro deEstudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile*Corresponding author: taguchi@cetacean.jp
1

Abstract
To describe global genetic diversities and genetic structure of sei whales, population genetic
and phylogenetic analyses were performed using mitochondrial DNA (mtDNA) control region
sequence (480 bp) data from specimens collected in three oceanic regions: North Paciﬁc (NP:n=39), North Atlantic (NA: n=84) and Southern Hemisphere (SH: n=6). Microsatellite DNA(msDNA) analyses were also performed using genotype data at seventeen loci in a sub-set ofsamples (n=39 in NP and n=4 in SH). The haplotype (h) and nucleotide (π) diversities werehigher in NP (h=0.92 and π=0.009) and SH (h=1.00 and π=0.012) than in NA (h=0.68
and π=0.002). The haplotype frequency was signiﬁcantly diﬀerent among the three oceanic
regions, and the conventional pairwise FST estimates support the diﬀerence between NA andthe other two populations. Furthermore, except for one haplotype, there were no other shared
haplotypes among the three oceanic regions, suggesting contemporary migration and geneﬂow would be strongly restricted at inter-oceanic scales. This inference was also supported by
the msDNA analyses. The haplotype genealogy reconstructed by the maximum-likelihood approach strongly supported two clusters, the ﬁrst consisting of NA haplotypes, and the second
consisting of NP and SH haplotypes. This genealogy was supported by the statistical parsimony haplotype network. These results indicated hierarchical genetic structuring of sei whales
globally, in which whales in SH are genetically closer to NP whales than to NA whales. Basedon a comparison of the inter-oceanic genetic structure and phylogeny of the sei whales withthose of ﬁn whales, which is another cosmopolitan baleen whale species, it is suggested thatthe genetic structure of sei whales reﬂects occasional gene ﬂow between the Northern andSouthern hemispheres and/or incomplete lineage sorting, similar to the case of ﬁn whales.
Key words:

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Introduction
The sei whale, Balaenoptera borealis, is one of the large baleen whales inhabiting all the major
open oceans, except the northern Indian Ocean (Horwood, 1987; Rice, 1998). Sei whales live up to
sixty years and their body length reaches up to 20 m. It is believed that they migrate from low-latitudes
winter breeding grounds to summer feeding grounds in high-latitudes, although little is known about
the migratory routes and the exact location of breeding grounds of this species. This migration pattern,coupled with asynchronous seasonal breeding cycles between the Northern and Southern hemispheres,should favor reproductive isolation and resultant genetic divergence of sei whales between the hemispheres, as observed in other cosmopolitan baleen whales, e.g., ﬁn whale, Balaenoptera physalus (Archer et al., 2013) and humpback whale, Megaptera novaeangliae (Jackson et al., 2014). Furthermore,
the continental masses separating the North Atlantic from the North Paciﬁc have probably prevented
gene ﬂow of sei whales between the two oceans since the closure of the Panama Seaway, which is believed to have occurred during the Pliocene (Coates et al., 1992).
Previous published population genetic work of sei whales is limited, despite their global distribution. Pioneering work was carried out by Wada and Numachi (1991) based on allozymes. This study
revealed allele frequencies of three polymorphic allozymes to be signiﬁcantly diﬀerent between Antarctic and North Paciﬁc sei whales, without any further diﬀerentiation within the oceans. The genetic
homogeneity within the western North Paciﬁc was supported by the subsequent work by Kanda et al.
(2006) using microsatellite DNA (msDNA) polymorphisms at seventeen loci. The most recent study
used mitochondrial DNA (mtDNA) control region sequences and msDNA genotypes. The study foundevidence of genetic structuring between North Paciﬁc and North Atlantic sei whales, but not within
the North Atlantic (Huijser et al., 2018). Taking these previous ﬁndings together, it is highly possible that sei whales are genetically diﬀerentiated among North Paciﬁc (NP), North Atlantic (NA) andoceans of the Southern Hemisphere (SH).
The objective of this study was to describe global genetic diversities and genetic structure of sei
whales using mtDNA control region sequences and msDNA genotype data of this species worldwide.
This is the ﬁrst study to incorporate sei whale samples from the NP, NA and SH.

Materials and Methods
Laboratory procedures
Samples and DNA extraction
A total of 44 tissue samples of sei whales (Fig. 1) was collected from three sources: (1) whaling
under the second phase of the Japanese Whale Research Program under Special Permit in the western
North Paciﬁc (JARPNII) in 2002 (n=39); (2) biopsy sampling under the Japanese Whale Research
Program under Special Permit in the Antarctic (JARPA) in 2000/01 (n=3) and 2002/03 (n=1); (3)stranding at southern Brazil in 2015 (n=1, export and import CITES permits 18BR030112/DF and
18JP000006/TI, respectively). Note that the 39 samples collected in the western North Paciﬁc were
the same as those used in the previous msDNA analyses (Kanda et al., 2006), but their nucleotide sequences at mtDNA control region were determined for the ﬁrst time in the present study.
Sampled skin tissues were preserved in 99% ethanol or stored frozen at −20°C until use. Total
genomic DNA was extracted from 0.05 g of skin tissue using either the standard phenol-chloroform
method (Sambrook et al., 1989) or the Gentra Puregene kits (QIAGEN). Extracted DNA was stored in
TE buﬀer (10mM Tris-HCl, 1mM EDTA, pH 8.0).
MtDNA sequencing
For all samples subjected to the DNA extraction, 534 base pairs (bp) of the mtDNA control region
were ampliﬁed by the polymerase chain reaction (PCR) using the set of primers MT4 (Árnason etCetacean Popul. Stud. (CPOPS), Full paper
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Fig. 1. Geographical position of samples newly sequenced and/or genotyped in the present study. Symbol
shape indicates sample population: circle (NP, n=39), triangle (SH, n=5).

al., 1993) and Dlp5R (5′-CCA TCG AGA TGT CTT ATT TAA GGG GAA C-3′). PCR was carried out ina 25 µL reaction mixture containing 10–100 ng of template DNA, 0.2 mM of dNTPs, 0.1 mM of eachprimer, 0.5 units of EX Taq DNA polymerase (TaKaRa), and 1× PCR buﬀer. Each reaction was performed with an initial denaturation step at 95°C for 5 minutes, followed by 30 cycles of 30 seconds at
94°C, 30 seconds at 50°C and 30 seconds at 72°C, with a ﬁnal extension step at 72°C for 10 minutes.
PCR products were puriﬁed using MicroSpin S-400HR columns (Pharmacia Biotech). Cycle sequencing was performed using BigDye terminator cycle sequence Kit (Applied Biosystems) and the PCRprimers, following the protocols of the manufacturer. The cycle sequencing products were puriﬁed using AutoSeq G-50 spin Columns (Pharmacia Biotech). The labeled sequencing fragments from tissue
samples from JARPNII and JARPA were resolved using an ABI PRISM 377, while the fragment of
the stranding sample was sequenced with ABI3500 Genetic Analyzers (Applied Biosystems).
MsDNA genotyping
Three samples collected under the JARPA in 2000/01 and one stranding sample collected in southern Brazil in 2015 were genotyped at 17 nuclear msDNA loci, i.e., EV1, EV14, EV21, EV94, EV104(Valsecchi and Amos, 1996), GT011 (Bérubé et al., 1998), GT23, GT211, GT271, GT310, GT575(Bérubé et al., 2000), GAT A28, GAT A53, GAT A98, GAT A417, GGAA520 (Palsbøll et al., 1997),
and DlrFCB17 (Buchanan et al., 1996), in three multiplex ﬂuorescent PCRs. Each of the multiplex
PCRs was carried out in a 10 µL reaction mixture, containing 10–100 ng of template DNA, 5 µL of 2×
Type-it Multiplex PCR master mix (QIAGEN), and 1 µL of primer mix (2 μM each primer), at 95°C
for 5 minutes, followed by 28 cycles at 95°C for 30 seconds/54, 58 or 59.5°C for 90 seconds/72°C for
30 seconds, and a post-cycling extension at 60°C for 30 minutes. PCR products were electrophoresedon an ABI3500 DNA Analyzer (Applied Biosystems), and allele sizes were determined using a 600
LIZ size standard (Applied Biosystems) and GeneMapper v. 4.0 (Applied Biosystems).
DatasetIn order to investigate the global genetic structure, mtDNA and msDNA data were divided into
three oceanic regions: (1) North Paciﬁc (NP); (2) North Atlantic (NA); (3) Southern Hemisphere (SH).

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MtDNACombining the 44 mtDNA control region sequences newly sequenced in this study with the 85
sequences generated in the previous studies (of which, 84 were from the Gulf of Maine, Iceland andAzores (Huijser et al., 2018) and one from the Antarctic Ocean (Sasaki et al., 2005)) resulted in a totalof 129 mtDNA sequences of sei whales from NP (n=39), NA (n=84) and SH (n=6) (Table 1).
MsDNA
Combining msDNA genotypes of the four new individuals from SH (three from the Antarctic andone from Brazil), with a subset of genotype data in NP generated by Kanda et al. (2006), resulted in a
total of 43 genotype set of sei whales from NP (n=39) and SH (n=4) (Table 1). The newly obtained
msDNA scores were standardized to the previous scores, which Kanda et al. (2006) generated using
the BaseStation100 DNA fragment analyzer (Bio-Rad), by comparing the scores of the same samples
between the present and previous platforms.
Data analyses
MtDNA
Haplotype (h) and nucleotide (π) diversities with sample standard deviations (Nei, 1987) were estimated using the program ARLEQUIN v. 3.5.2.2 (Excoﬃer and Lischer, 2010).
The diﬀerence in mtDNA haplotype frequency among oceanic regions was tested using the Monte Carlo simulation-based chi-square test of independence with 10,000 replicates (Roﬀ and Bentzen, 1989) in R (R Core Team, 2016). The conventional FST estimates between oceanic regions were
calculated using 10,000 random permutations of the original dataset, as implemented in ARLEQUIN.
The FDR correction (Benjamini and Hochberg, 1995) was used to adjust the statistical signiﬁcancelevel in the pairwise estimates.
The mtDNA haplotype genealogy of sei whales was reconstructed using the maximum-likelihood
approach (ML-tree) with 10,000 bootstrap resampling in the program MEGA ver. 10.0.5 (Kumar etal., 2018). The best-ﬁt nucleotide substitution model was determined based on the Bayesian Information Criterion using MEGA, and Tamura 3-parameter model (Tamura, 1992) with G=0.487 and
I=0.747 was selected. Two sequences of Balaenoptera edeni (GenBank accession number: X72196)
and Balaenoptera brydei (unpublished data) were used as outgroups in the analysis. The statisticalparsimony network (Clement et al., 2000) of mtDNA control region haplotypes was also depictedusing the program PopART (Leigh and Bryant, 2015).
MsDNA
The departure from Hardy–Weinberg equilibrium (HWE) was tested and the inbreeding coeﬃcient(FIS; Weir and Cockerham, 1984) was estimated, using GENEPOP (Raymond and Rousset, 1995;
Rousset, 2008). The number of alleles (A), allelic richness (AR) and expected heterozygosity (HE)
Table 1. Numbers of mitochondrial (mt) and microsatellite (ms) DNA data used in this study. The mtDNA
nucleotide sequences in NP were newly obtained from the same samples used for msDNA analyses in Kanda
et al. (2006).

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Table 2. Summary of mtDNA variations of sei whales and haplotype frequency in each of and across the oceanic regions. Numbers in ‘Variable site’ represent nucleotide positions corresponding to ‘H01’ deposited in DDBJ under the accession no. LC629100. See Table 1 for abbreviations of the oceanic region.
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were estimated using the program FSTAT ver. 2.9.3.2 (Goudet, 1995).
Bayesian clustering analysis was performed to infer the most likely number of clusters using
STRUCTURE 2.3.4 (Pritchard et al., 2000). The analysis was conducted with ten independent runs
for K=2–3. All runs were performed with 100,000 Markov chain Monte Carlo repetitions and 10,000
burn-in length using the admixture model with correlated allele frequencies. The web-based program
STRUCTURE HARVESTER (Earl and von Holdt, 2012) was used to estimate the mean posterior
probability of the data. Additionally, principal component analysis (PCA) was performed in R using
the ‘dudi.pca’ function in the ade4 package (Chessel et al., 2004; Dray et al., 2007).

Results
Genetic variations
MtDNA
The mtDNA control region sequences (480 bp) of 129 sei whales from the three oceanic regions
contained 31 variable nucleotide sites and a single indel (1 bp) deﬁning 31 haplotypes, of which 23
were novel (deposited in GenBank with accession numbers: LC629100–LC629122) (Table 2). Apartfrom haplotype ‘NA6’, none of the haplotypes were shared among oceanic regions. Haplotype ‘NA6’
was shared between NA and SH (Table 2). The h and π for the total samples were 0.86 and 0.013,
respectively (Table 2). These estimates were higher in SH (1.00 and 0.012) and NP (0.92 and 0.009)
than in NA (0.68 and 0.002).
MsDNA
All 17 msDNA loci were polymorphic in a total of 43 sei whales in NP and SH, with locus-speciﬁcallele numbers from 3 alleles at GAT A53 and GT271 to 17 alleles at DlrFCB17 (Table 3). The AR
was higher in SH than in NP. No signiﬁcant deviations from HWE were observed in each locus or
across the loci of NP and SH (Table 3). Although the signiﬁcant departure from HWE was detected at
GAT A417 when the two populations were combined (Table 3), the global test did not support the statistical signiﬁcance.

Table 3. Summary statistics of 17 msDNA loci of sei whales: A, the number of alleles; AR, allelic richness; HE,
expected heterozygosity; FIS, inbreeding coeﬃcient; HWE, p-value of the Hardy-Weinberg equilibrium test.
FIS and HWE at GT011 in SH were incomputable since one of two alleles was represented by only one copy.
See Table 1 for abbreviations of the oceanic region. Bold text indicates the statistical signiﬁcance at α=0.05.

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Table 4. Conventional pairwise FST estimates between oceanic regions for mtDNA. Asterisks show the statistical signiﬁcance after FDR correction: *p<0.05, **p<0.01, ***p<0.001. See Table 1 for abbreviations of
the oceanic regions.

Table 5. Summary of STRUCTURE analyses showing the average ln Pr(X|K) for each of K, and respective
probability.

Genetic diﬀerentiation and structure
MtDNA
The haplotype frequency was signiﬁcantly diﬀerent among the three oceanic regions (χ 2=246.48,
p<0.001). Conventional pairwise FST estimates were signiﬁcantly diﬀerent from zero in the pairs of NP
and NA as well as SH and NA, but no signiﬁcant diﬀerence was seen between SH and NP (Table 4).
MsDNA
The STRUCTURE analyses conducted for diﬀerent sampling partitions without information on
their geographic origins presented the highest probability at K=1 (Table 5). However, the four sei
whales from the SH were distinguishable from NP whales by high posterior probabilities (q>0.8) of
belonging to a particular cluster at K=2 (Fig. 2).
In PCA analysis, the ﬁrst (PC1) and second (PC2) principal components explained 9.81% and6.95% of the total variation, respectively. This analysis suggests that the 43 sei whales could be divided into two distinct clusters (NP and SH) along the PC1 axis (Fig. 3).
Phylogenetic analyses
The ML-tree showed two clusters supported by high bootstrap values (Fig. 4a), one which consistedof haplotypes found in NA and the other of haplotypes found in NP and SH. Within the NP/SH cluster,
the ML-tree also showed a sub-cluster containing four of the six haplotypes found in SH, i.e., ‘NA6’,‘H87’, ‘H88’ and ‘H90’. However, this cluster had a low bootstrap value (Fig. 4a).
The statistical parsimony network showed the two clusters were separated by six mutational steps,
which consisted of a star-like genealogy of haplotypes found in NA, and more complex structures in
NP and SH (Fig. 4b). The haplotype network also showed that all haplotypes found in SH were separated from those in NP by several mutational steps.
The haplotype ‘NA6’ found in both NA and SH was located in the NP/ SH cluster in each topology(Fig. 4).

Discussion
This is the ﬁrst population genetic study of sei whales worldwide. In particular, analyses using
msDNA has never been reported in SH sei whales. Notwithstanding the small number of samples usedfrom SH, the preliminary ﬁndings of this study provide some new insights into the genetic structure
and phylogeography of this species.

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Fig. 2. Bar plot of posterior probabilities in STRUCTURE analyses for sei whales in oceans of the Southern
Hemisphere (SH) and the North Paciﬁc (NP): (a) K=2 and (b) K=3. Each individual is characterized by athin vertical line, which is divided into K colored segments on the basis of the individual’s membership fractions in K clusters.

Genetic structure
The haplotype frequency of sei whales was signiﬁcantly diﬀerent among the three oceanic regions,and the conventional pairwise FST estimates suggested the genetic diﬀerentiation of this species between NA and the other two oceanic regions. This observation is consistent with the pattern of genetic
diﬀerentiation of sei whales between NP and NA presented by Huijser et al. (2018). Although the
FST estimates did not support a genetic diﬀerence between NP and SH, given no haplotype sharing,the insigniﬁcant result was likely to be caused by the small sample size in SH. In fact, Wada and Numachi (1991) using a larger number of samples demonstrated the signiﬁcant genetic diﬀerentiation
between NP and SH sei whales. Furthermore, this inference was supported by the msDNA analyses.
The STRUCTURE analysis suggested that the most likely number of populations at Hardy-Weinberg/
linkage equilibrium in the data set consisting of sei whales in SH and NP was one, which was consistent with no deviations from HWE in each of and across populations. However, despite the small
sample size in SH, the four SH sei whales were distinguishable from the NP whales by high posterior
probabilities (q>0.8) when K=2 was assumed. This was also supported by the result of multivariable
analysis, i.e., PCA, separating the four sei whales from other NP whales along the ﬁrst PC axis.
The PCA analysis also showed a large genetic variation of SH cluster consisting of samples collected across the vast oceanic region, i.e., the western South Atlantic and the Antarctic Ocean. This,
coupled with high h in SH, might be suggestive of an inclusion of samples derived from multiple
breeding populations in a single sample population. Given the genetic structuring shown in other SH
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Fig. 3. Result of PCA analysis on genotypes at seventeen msDNA loci. See Table 1 for abbreviations of theoceanic regions.

Fig. 4. Genealogy reconstructed by the maximum-likelihood approach (a), and statistical parsimony network(b) of mtDNA control region haplotypes of sei whales. The phylogenetic tree was rooted by outgroup of B.
brydei and B. edeni, which was drawn to scale with branch lengths measured in the number of substitutions
per site. Only bootstrap values above 60% are shown. Asterisk shows haplotypes shared among oceanic regions. Circles of the haplotype network represent diﬀerent haplotypes. The colors and sizes of circles refer tothe geographical origin and abundance of haplotypes, respectively. Small black circles indicate intermediate
haplotypes not found in this study. See Tables 1 and 2 for abbreviations of the geographical origin of haplotypes and haplotype information, respectively.

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baleen whales (e.g., humpback whales, Olavarría et al., 2007; Antarctic minke whales, Pastene andGoto, 2016), that possibility could not be excluded at this stage.
The haplotype network and ML-tree strongly supported the divergence of haplotypes found in NA
from those in NP and SH, as shown by Huijser et al. (2018). The haplotype network further showedthat all haplotypes found in SH were separated from those in NP by several mutational steps. The MLtree revealed a sub-cluster containing most of the haplotypes found in SH, however, there was no signiﬁcant bootstrap support. These results are indicative of ocean-speciﬁc mitochondrial lineages, which
are compatible with the observed diﬀerence in the degrees of the pairwise FST estimates among sei
whales from the three oceanic regions.
Taking all the present and previous ﬁndings together, sei whales appear to be signiﬁcantly diﬀerentiated among oceanic regions hierarchically, and whales in SH are more closely related to whales
in NP than to whales in NA. Except for haplotype ‘NA6’, there were no other haplotypes that wereshared among the three oceanic regions, which suggests that contemporary migration and gene ﬂow
would be strongly restricted at inter-oceanic scales.
Interestingly, the pattern of inter-oceanic genetic structuring observed in the present study was similar
to that in ﬁn whales with the lower FST estimates between NP and SH (mtDNA, 0.005–0.106; singlenucleotide polymorphisms (SNPs), 0.098) than between NA and NP (mtDNA, 0.018–0.198; SNPs,
0.1668) as well as between NA and SH (mtDNA, 0.017–0.121; SNPs, 0.1447) (Archer et al., 2019). This,
coupled with genealogical concordance between ﬁn and sei whales described below, suggests that the pattern of genetic structuring in sei whales could be attributed to historical events, i.e., recent occasional geneﬂow between the Northern and Southern hemispheres and/or incomplete lineage sorting (ILS).
Phylogeographic inferences
The ML-tree found no evidence of divergence of SH haplotypes from NP ones, despite the inference of genetic diﬀerentiation between the two oceanic regions. ILS and/or recent occasional geneﬂow may explain this observation, because they can be the cause of shared genetic variations among
populations after their divergence. The mtDNA phylogenetic study of ﬁn whales demonstrated a polyphyletic pattern of NP and SH haplotypes (Archer et al., 2013), which was similar to that of the sei
whale. The study also suggests the possibilities of a relatively recent introgression between the twooceans and/or retention of ancestral polymorphisms due to ILS of the large whale species.
Huijser et al. (2018) inferred that an expansion of the North Atlantic sei whale population occurred
after the last glacial maximum (LGM, 26.5–19 thousand years ago; Clark et al., 2009) based on phylogeographic analyses. The star-like genealogy of haplotypes and lower genetic diversities observed in
NA in the present study would be attributed to this historical event in the case of the NA sei whales.
On the other hand, SH and NP haplotypes showed more complex structures with a high number of
haplotypes of intermediate frequency on the network. Given the inferences of ILS with high h in NP
and SH, the result could reﬂect ancestral polymorphisms of NP and SH whales in a large long term
eﬀective population size. It seems that they have been separated long enough to be void of shared
haplotypes, but not long enough to have evolved reciprocal mitochondrial monophyly. Such reciprocalmonophyly is indeed observed among NA and the combined NP/SH cluster, suggesting a considerably
more ancient divergence.
In the present study, there are also signs of recent or contemporary occasional inter-oceanic migration/dispersal events, one from SH to NA (NA6) and one from NP to SH (SH1). This inference
is compatible with the restricted but rare inter-equatorial gene ﬂow inferred in humpback whales(e.g., Jackson et al., 2014) and ﬁn whales (Cabrera et al., 2019). So far, there is no direct evidence
for trans-equatorial gene ﬂow in sei whales. However, this seems probable in this species, given its
high mobility as demonstrated by tagging studies (e.g., Olsen et al., 2009) and continuous distribution
across the equatorial waters inferred from stranding records along the northern coast of Brazil (e.g.,
Costa et al., 2017; Mayorga et al., 2020; Milmann et al., 2020).
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Conclusion
Notwithstanding the small sample size used from SH, the present study demonstrated the hierarchical genetic structuring of sei whales globally for the ﬁrst time, with high genetic diversity in SH/NP,
in which whales in SH are genetically closer to NP whales than to NA whales. These ﬁndings, coupledwith the previous ﬁndings in sei whales as well as in other cosmopolitan baleen whales, suggested thefollowing phylogeographical scenarios of this species: (1) a shorter history of divergence among SH
and NP, leading to retention of ancestral polymorphisms due to ILS in SH and NP, (2) occasional geneﬂow between the Northern and Southern hemispheres.
Extended genetic analyses using larger sample sizes across the oceans and more genetic loci haveto be conducted in this species to investigate ﬁner genetic structure and demographic estimates, e.g.,
migration rate and eﬀective population size.
Acknowledgements

We thank all researchers, crew members and colleagues who contributed to the collection of genetic samples used in thisstudy. We are grateful to Hiroyuki Oikawa (ICR) for his assistance in the laboratory work, and to Naohisa Kanda (JANUS)
for preparing the msDNA data used in this study. We would also like to thank the anonymous reviewers for their helpfulcomments on the manuscript.

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Received: November 18, 2020
Accepted: March 22, 2021
Published online: May 24, 2021

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J-STAGE Advance published date: November 8, 2021

KATSUMATA, HIROSE, NAKAJO, SHIBATA, MURATA, YAMAKOSHI, NAKAMURA AND KATOEVIDENCE OF WINTER MIGRATION OFHUMPBACK WHALES TO THE HACHIJO ISLAND,IZU ARCHIPELAGO OFF THE SOUTHERN COAST
OF TOKYO, JAPANTaiki KATSUMATA1, 2*, Ayumi HIROSE1, Ken NAKAJO1,
Chieri SHIBATA1, Haruna MURATA1, Tadashi YAMAKOSHI3,
Gen NAKAMURA1 and Hidehiro KATO1, 2
1

Tokyo University of Marine Science and Technology, 4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
3
Hachijo Town Oﬃce, 2551–2, Oogago, Hachijo Town, Tokyo, 100–1401, Japan*Corresponding author: katsumata@cetacean.jp

Abstract
In the western North Paciﬁc Ocean, humpback whales (Megaptera novaeangliae) migrate
to the Okinawa (26°13′N, 127°41′E) and Ogasawara (27°04′N, 142°13′E) islands of Japanfor breeding. The Hachijo Island (33°06′N, 139°47′E) is located in the Izu Archipelago —further north from known wintering grounds of those whales. In the 2015–16 winter, humpback
whales were sighted around the Hachijo Island in signiﬁcant numbers. This led to a monitoring project of whales around the island that was initiated from the 2016–17 winter to elucidate
their migration. Here, we report the results of monitoring over two subsequent winter seasons(2016–17 and 2017–18). A survey was conducted within 5 nautical miles of the coast of theisland using a dedicated vessel (12GT) for respectively 32 and 34 days in the ﬁrst and second
season from November to April. Humpback whales were sighted from November to March inthe ﬁrst season and from November to April in the second season, and a total of sightings ofrespectively 205 and 397 whales were recorded in the 2016–17 and 2017–18 seasons. Characteristic behaviors in the wintering grounds, such as singing and forming competitive groups,
were conﬁrmed in both seasons. Moreover, around 15% of the whales were repeatedly sighted
during the same season, and six individuals observed in the ﬁrst season were resighted in thesecond season. These results suggest that waters around the Hachijo Island are part of the winter migration grounds of humpback whales, and their migration to waters oﬀ the Hachijo area
is expected to continue in the future. Long-term monitoring focusing on the social compositionof groups is necessary, and additional photo-identiﬁcation and genetic data should be collected
to shed light on the habitat use and causes of sudden occurrence of humpback whales aroundthis island.
Key words:

Hachijo Island, humpback whale, wintering ground, Photo-ID, residency, site
ﬁdelity.

Introduction
Humpback whales (Megaptera novaeangliae) belong to the family Balaenopteridae of the suborder
Mysticeti (Fig. 1). They undergo seasonal migration, staying in highly productive feeding grounds
at high latitudes during the summer and autumn and migrating to breeding grounds at temperate low
latitudes in winter (Dawbin, 1966; Baker et al., 1986; Clapham, 2000). In the North Paciﬁc Ocean,

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HUMPBACK WHALES OFF THE HACHIJO ISLAND, TOKYOFig 1.

Humpback whale. This Photo was taken in 22 January, 2017 at Hachijo Island.

Fig. 2.

Map of Hachijo Island and two other major wintering grounds of humpback whales known in Japan.

some wintering grounds have been reported, namely the coasts of Mexico, Revillagigedo Archipelago(Urbán and Aguayo, 1987), Hawaii (Baker and Herman, 1981), the Philippines (Acebes et al., 2007),
Ogasawara Islands (Darling and Mori, 1993), Okinawa (Nishiwaki, 1959; Kobayashi et al., 2016), andMariana Archipelago (Hill et al., 2020). The occurrence peak of humpback whales in the wintering
ground of the North Paciﬁc Ocean generally lasts from February to March (Urbán and Aguayo, 1987;
Mobley et al., 1999; Kobayashi et al., 2016). In the wintering grounds, some behaviors related to themating of humpback whales were observed. Male humpback whales sing long complex songs (Payne
and McVay, 1971; Baker and Herman, 1984), and males compete physically among multiple male
whales for mating opportunities with females (Tyack and Whitehead, 1983; Baker and Herman, 1984;
Clapham, 2000).
In November 2015, we received a report from diving companies that an unusually large numberof humpback whales appeared around the Hachijo Island (Kono E. and Yamakoshi, pers. comm.).
The Hachijo Island is located south of Tokyo in the southern part of the Izu Archipelago (33°06′N,
139°47′E), approximately 700 km north of the Ogasawara Islands, which is one of the known primary
wintering grounds of humpback whales in Japan (Fig. 2). According to Uda (1954), the waters around
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the Hachijo Island have not been previously reported as the whaling grounds of humpback whales. Furthermore, there has been no scientiﬁc monitoring of large whales in this region. Therefore, there are not
any previous formal records which mention whether humpback whales migrated to this region seasonally or not. Before this sudden migration in 2015, only ﬁve sporadic sightings of humpback whales aroundthis island were reported, including once each in April 2005 and May 2010 and thrice in March 2013
(Tokyo Metropolitan Government Park Association Hachijo Visitor Center, pers. comm.).
Therefore, on December 23, 2015, the Japan Broadcasting Corporation (NHK) and the Laboratoryof Cetacean Biology, Tokyo University of Marine Science and Technology (TUMSAT) collaborated tovisually survey the coastal area of Hachijo Island. In this preliminary survey, 37.4 nautical miles weresearched along the coast of the island and at least 10 humpback whales belonging to ﬁve social groups
were sighted in the southwest part of the island in water depths less than 200 m. Moreover, a song was
conﬁrmed and recorded.
To examine whether the migration of a signiﬁcant number of whales around the Hachijo Island is
temporary and to collect photo-identiﬁcation data for investigating the migratory connections to otherareas, a shipboard survey has been conducted around the island by the local government and TUMSAT throughout the breeding season (November to April) since 2016. The present study reports the results of monitoring over two subsequent seasons (2016–17 and 2017–18) and explores the importanceof waters around the Hachijo Island as wintering grounds of western North Paciﬁc humpback whales
based on occurrence, behavior, and photo-identiﬁcation data.

Materials and Methods
Field Survey
We conducted surveys within ﬁve nautical miles of the coast of the Hachijo Island, departing fromand arriving at the Yaene Port (33°06′N, 139°46′E). In the ﬁeld the Aki-Maru, a small dedicated research vessel of 12 GT (length, aprox. 15 m; width, 2.5 m) with a single inboard diesel-powered engine was used. Three researchers on board visually searched for whales with the naked eye from theobservation platform (3 m above sea level). The survey was conducted from 9:00 to 15:00, and thesearch speed of the vessel was set at 8–9 knots. When whales were sighted, one researcher recorded
the time and position of the vessel (latitude and longitude) using a global positioning system (Garmin
eTrex10J). When the vessel reached the estimated location at which the whales were spotted, one
researcher recorded the time, position, and sea surface temperature (SST), and two other researchersattempted to take photographs for identiﬁcation. In addition, the behavior and group size of the whales
were observed and recorded. The researchers lowered a hydrophone (OKI Whalephone II) at least
once per day to evaluate whether the whales were singing.
Photo-identiﬁcation
Humpback whales can be identiﬁed based on the pattern of pigmentation on the ventral ﬂuke andthe shape of its edge (Katona and Whitehead, 1981). When humpback whales were sighted, the vessel
immediately followed the target group, and the researchers took photographs for identiﬁcation using a
NIKON D7000 camera with a 55–300 mm lens (AF-S DX NIKKOR 55–300 mm f/4.5–5.6 GED) anda NIKON D7500 camera with a 19–300 mm lens (AF-S DX NIKKOR 18–300 mm f/3.5–5.6 GED).
Two types of surveys were conducted—one was circling around the island, and the other was staying
in the waters where sightings were expected. In both types of surveys, we attempted to take as many
photographs as possible.
After the surveys were completed in each season, the resightings were compiled to assess the residency around the island during a season. In the present study, the good-quality photographs that werein focus and clearly showing the pattern of pigmentations on the ventral ﬂuke and the shape of its

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HUMPBACK WHALES OFF THE HACHIJO ISLAND, TOKYOedge were used. We printed the photographs obtained during each season and sequentially comparedthem by visual examination to identify the individuals. Each of the three researchers performed theabove steps, and the ﬁnal identiﬁcation results were compiled as resightings. The individuals re-photographed at intervals of 1 or more days within the same season were considered resightings. Moreover,photographs were compared between the 2016–17 and 2017–18 seasons to assess whether the same
individuals migrated to areas around the Hachijo Island in the following season.

Results and Discussion
Survey eﬀort and sightings
Table 1 summarizes the results of the survey eﬀort and sightings during the 2016–17 and 2017–18
seasons. The survey was conducted for respectively 32 and 34 days from November to April in the
2016–17 and 2017–18 seasons. Table 2 summarizes the monthly survey eﬀort for each season. In bothseasons, a large amount of eﬀort was devoted to February and March when the occurrences of whales
were generally expected to be high in order to obtain more Photo-ID (Urbán and Aguayo, 1987; Moriet al., 1998; Mobley et al., 1999; Kobayashi et al., 2016). The survey area and track lines during eachseason are illustrated in Fig. 3. In the 2016–17 season, we covered 986.0 nautical miles in total, andthe ﬁrst sighting of a humpback whale in the season was recorded on November 20, 2016. From thatday until March 19, 2017, 205 whales belonging to 136 social groups were sighted. In the 2017–18
season, we covered 835.6 nautical miles in total and sighted 397 whales belonging to 232 socialgroups from November 28, 2017, to April 9, 2018. The mean sighting rate in the 2017–18 season (11.7
whales per day) was approximately two times the rate in the 2016–17 season (6.4 whales per day).
Fig. 4 presents the monthly changes in sighting per unit eﬀort (SPUE; number of whales sighted perday) in both seasons. The temporal trend of occurrences in a season is one of the critical indicators toclarify the habitat use of humpback whales during the winter. In Okinawa (Kobayashi et al., 2016)
and Ogasawara (Mori et al., 1998), the period of the most frequent occurrence of whales was fromFebruary to March, with a single peak. The trend observed in eastern Australia, which is considereda migration corridor, frequently occurs in the early stages of the season; this is followed by a decline
and then an increase in number of whales at the end of the season (Burns, 2010).
Table 1. Survey period, survey eﬀort (number of days surveyed and total search distance in nautical miles),
total number of sightings, and sightings per unit eﬀort (SPUE) in each winter season.
SeasonStart survey
Finish survey(yyyy/mm/dd) (yyyy/mm/dd)

2016/172017/18

2016/11/18
2017/11/28

2017/04/24
2018/04/23

Survey eﬀort Survey eﬀort
Sightings
SPUE(days)(nautical miles) (groups/whales) (whales/days)
32
34

986.0
835.6

136/205
232/397

6.4
11.7

Table 2. The number of survey days and searching distance per month in each season. The study was
designed to increase survey eﬀorts in February and March as the frequency of humpback whale occurrence inthe wintering ground was expected to be high.
SeasonSurvey eﬀort
Unit

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

Total

2016/17

Days
Nautical miles

3
134.4

5
169.5

4
103.1

7
182.3

9
233.5

4
163.2

32
986.0

2017/18

Days
Nautical miles

2
61.5

6
137.3

5
127.3

9
214.3

8
192.1

4
103.2

34
835.6

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Fig. 3. Survey track lines in the 2016–17 (left) and 2017–18 (right) winter seasons. The survey was conductedwithin 5 nautical miles from the coast of Hachijo Island in both seasons.

Fig. 4. Monthly sightings per day from November to April in the 2016–17 and 2017–18 seasons. SPUE:
Sightings per unit of eﬀort.

In the ﬁrst season, a single peak of occurrences around the Hachijo Island was recorded in February; however, in the second season, SPUE decreased after a peak in December and then increased in
March. The Kuroshio Current path is one of the possible reasons for these diﬀerences in the temporal
trends of whale occurrence between the two seasons. The Kuroshio large meander was underway
since August 2017, and the current path around the Hachijo Island (around 140°E) signiﬁcantly differed between the ﬁrst and second seasons (Qiu, 2019). In the Southern Hemisphere Madagascar
wintering grounds in, humpback whales swim along strong currents during non-migratory oﬀshore
movements (e.g., travel between breeding sites or short-term oﬀshore travel) (Trudelle et al., 2016).
Assuming that humpback whales behave in the same manner around the Hachijo Island, they mightswim near the island or oﬀshore depending on the Kuroshio Current path. This may have also aﬀected the number of annual sightings in the survey area. However, detailed investigation to elucidate theabove is not possible with data collected for only 2 winter season surveys. In addition, the unevenness in the amount of eﬀort in each month of the season raises the possibility that the SPUE of somemonths does not adequately reﬂect the relative abundance of whales. Based on the above, the present
study results do not allow us to determine when the peak in the number of migrating whales to Hachijo Island occurs, and it is not possible to conclude whether the use of the area by humpback whales issimilar to that of Okinawa and Ogasawara. Therefore, continuous ﬁeld surveys and long-term monitoring of individuals through satellite telemetry are necessary to understand the trend of occurrence of
humpback whales around Hachijo Island. However, as humpback whales were continuously sighted
around Hachijo Island from November to March for the two consecutive seasons, it is reasonable toassume that this species uses this area for winter migration.

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Characteristic behaviors
Humpback whale singing behavior was conﬁrmed from mid-January to late March in 2016–17
and from late November to late March in 2017–18. Singing behavior is considered to play speciﬁcroles; as such, songs serve as an acoustic display to attract females, a threat behavior during intrasexual competition, and a spacing function among males (Clapham, 2000). Furthermore, on March 5,2017, a group of four whales and another group of two whales merged to form a six-whale group. The
whales of this group swam violently. For instance, one individual hit its head on the water surface,
while another pushed other whales with its head. These behaviors were consistent with the competitive behaviors reported in the wintering grounds by Tyack and Whitehead (1983) as well as by Baker
and Herman (1984). Such competitive behaviors were observed respectively two and three times in
the 2016–17 and 2017–18 seasons. Based on the observations of singing and competitive behaviors,
humpback whales likely use the areas around the Hachijo Island as a mating ground.
Photo-identiﬁcation
A total of 203 individuals were identiﬁed during both seasons. Respectively 58 and 151 individuals were identiﬁed in the 2016–17 and 2017–18 seasons, and six individuals were identiﬁed in bothseasons. Table 3 summarizes the results of photo-identiﬁcation in the same season, and Tables 4a and4b summarize the survey dates and the dates when individuals were resighted for each season. In the
2016–17 season, 10 of the 58 individuals (17.2%) were resighted within the same season. Nine of ten
individuals were resighted once, while one individual was resighted twice, and the period between theﬁrst and the last sighting (or occupancy) ranged from 1 to 40 days (mean: 9.5 days; SD: 13.7 days).
In the 2017–18 season, 21 of the 151 individuals (13.9%) were resighted within the same season.
Thirteen of the 21individuals were resighted once, six were resighted twice, and one individual was
resighted each three and four times, respectively; and the occupancy ranged from 1 to 52 days (mean:
10.6 days; SD: 15.4 days). Thus, in both seasons, most of the individuals were not resighted andaround 15% were resighted within the same season.
The proportion of individuals resighted during a season provides basic information on the residencyof humpback whales. For instance, a high proportion indicates that individuals are likely to be resighted in a certain area and tend to stay there for a long period, whereas a low proportion indicates that individuals are less likely to be sighted in a certain area and tend to move around instead of staying. The
frequency of resighting in the Hawaiian waters (oﬀ Kauai) was 5%–14% (Cerchio, 1998), and similarvalues have also been reported in Silver Bank (9.1%) (Mattila et al., 1989), Samana Bay (15.8%)(Mattila et al., 1994), Ecuador (12.9%) (Scheidat et al., 2000), and Abrolhos Bank (13%) (Wedekin
et al., 2010). Values of approximately 10%–15% indicate that individuals do not stay in the same
area for a long period and tend to move widely within each wintering ground. This observation is also
supported by the reports using satellite telemetry of extensive local movements in Hawaii (Mate etal., 1998), Silver Bank (Kennedy et al., 2014), and Ecuador (Guzmán and Félix, 2017). In contrast,
the frequency of resighting in the feeding grounds has been reported to be as high as 77.3% in the
Gulf of Maine (Clapham et al., 1993) and as low as 2.1% along the east coast of Australia, which isbelieved to be a migration corridor (Burns, 2010). Of note, these proportions depend on the survey
Table 3. Number of individuals photo-identiﬁed and resighted in each season, and the minimum and maximum period between the ﬁrst and last sighting of the resighted individuals in the same season.
Number of
Photo-IDs
2016/172017/18

58
151

The maximum period
Number of individ- The minimum period between
between ﬁrst and last sighting
uals resighted (%) ﬁrst and last sighting (days)(days)
10 (17.2%)
21 (13.9%)

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1
1

40
52

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Table 4a. The survey dates and dates when individuals were resighted in the 2016–17 season. Black circle indicates the date an individual was sighted.
ID #

Month

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

Number of
Day 18 20 29 3 12 13 25 26 17 18 20 22 4 5 8 25 26 27 4 5 8 9 17 18 19 20 23 5 6 23 24 resighting

IH-004
IH-007
IH-008
IH-025
IH-029
IH-037
IH-039IH-043
IH-059IH-061

1
2
1
1
1
1
1
1
1
1

● ●
● ●
● ●

●
●
●

●
●
● ●
● ●
● ●
● ●
● ●

Table 4b. The survey dates and the dates when individuals were resighted in the 2017–18 season.
ID #Month Nov.

Dec.

● ●

IH-101●

IH-049●

IH-127
IH-159

Mar.

Apr.

2

●

1

●

2

● ●
●

1

●
● ●

2

●

1

● ●

IH-166●

IH-169●

IH-176

Feb.

Number of
Day 28 29 9 10 18 20 21 23 7 8 20 21 22 8 9 10 17 18 19 20 21 22 3 4 13 14 15 26 27 28 9 10 22 23 resightings

IH-108

IH-117

Jan.

● ●

●

4

●

1

●

1

● ●

IH-200●●

IH-201●●

1
1

IH-203●●

1

IH-207● ●●2

IH-212● ●IH-2371●

1●

IH-265● ● ●2

IH-276● ●1

IH-279● ●IH-281● ●IH-282● ● ●IH-303

1
2

●
● ●

●

3
1

eﬀort and population size. In the present study, since 80% of the resighted individuals were sighted
within three days of their ﬁrst sighting, the proportion of resighting may have been underestimateddue to 1–2 weeks interval between the survey dates. However, considering the short gap between resighting and the rare sighting of individuals, such as IH-166, for two months, possibly few individuals
remain in the vicinity of Hachijo Island for an extended period, suggesting that the residency of humpback whales around Hachijo Island is comparable to that in other wintering grounds.
Interestingly, 6 of the 58 individuals identiﬁed in the ﬁrst season returned to the waters around theHachijo Island in the subsequent season (Fig. 5). According to Calambokidis et al. (2001), few individuals migrate to diﬀerent wintering grounds every year, and each population has a speciﬁc wintering
ground.

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Fig. 5. Tail photographs of whales that were observed around the Hachijo Island in two consecutive seasons.
Dates indicate the day on which each individual was photographed in each season (all copyrights are reserved
to TUMSAT).

Calambokidis et al. (2001) assessed the site ﬁdelity for North Paciﬁc wintering grounds using the
Match index (Equation 1), which reﬂects the size of the overall population sampled and the degree ofsite ﬁdelity.
The Match index is expressed by the following:
Ii → j = [ mi / ( ai n j )] ×1,000(1)where,
ai =number of marked releases at time 1 in region i (i=1, …, R)
nj =number examined for marks at time 2 in region j
mi=marked recaptures in region j, originally marked in region i
The frequency of identiﬁcation of the same individual in diﬀerent wintering grounds during diﬀerent years was low, and the Match index was 0.015 between Mexico and Hawaii, 0.010 between Hawaii and Japan (Okinawa and Ogasawara), and 0.000 between Mexico and Japan; however, frequency
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of reidentiﬁcation of the same individual in the same wintering grounds but during diﬀerent years was
relatively high, and the Match index was 0.257 for Hawaii, 0.518 for Mexico, and 2.365 for Japan(Calambokidis et al., 2001). Around the Hachijo Island, 58 individuals were marked in the ﬁrst season(ai), 151 individuals were examined for marks in the subsequent season (nj), and 6 individuals wererecaptured (mi). Based on these counts, the Match index was 0.685, indicating that site ﬁdelity for the
Hachijo Island is similar to that reported for Hawaii and Mexico.
Considering that the residency and site ﬁdelity for the Hachijo Island were comparable to those forthe other wintering grounds, the same population likely migrates to the areas around the island annually and uses it as some parts of their wintering grounds. In other words, this area is as important as other wintering grounds for the migration of humpback whales, and migration to waters oﬀ the Hachijoarea is expected to continue in the future.
Absence of mother–calf pairs
Newborn calves (typically approximately 4 m long) were not sighted in both seasons. In Okinawa and Ogasawara, mother–calf pairs have been observed during winter (Darling and Mori, 1993;
Kobayashi et al., 2016). Generally, the SST at the wintering grounds of humpback whales is above
21.0°C (Rasmussen et al., 2007). However, according to daily measurements near the Yaene Port
(33°06′N, 139°50′E) by the Tokyo Metropolitan Islands Area Research and Development Center for
Agriculture, Forestry and Fisheries, the mean SST from November to April was 19.0°C (SD: 3.1°C;
range: 13.6–25.8°C) in the 2016–17 season and 19.9°C (SD: 1.9°C; range: 15.4–24.1°C) in the 2017–18 season. This relatively low SST may be unsuitable for nursing. However, based on a personal communication (Kato, H., Akama, N. and Kono, E., pers. comm.) a mother-calf pair was observed in thesoutheastern part of the island in March 2016, which may have been missed in our survey.
The results of the present study provide novel insights into the annual migration of humpback
whales to the waters around the Hachijo Island and their distinct breeding behavior in winter. However, we cannot conclude whether the waters around the Hachijo Island indeed serve as a breeding
ground for these whales, similar to Okinawa and Ogasawara, given the absence of newborn calves.
The objective of migration to the areas around the Hachijo Island remains debatable, and several
hypotheses have been put forth, such as these areas being part of a migration corridor or this beinga temporary migration. If the waters around the Hachijo Island are established as a breeding groundin the future, mother–calf pairs should be sighted frequently around the island. Therefore, long-termmonitoring focusing on the composition of the social groups should be conducted to reveal the habitatuse. Moreover, in humpback whales, the timing of migration to wintering ground varies depending on
the sex and reproductive status (Dawbin, 1966; Brown et al., 1995) of individuals. Therefore, the sex
and sexual maturity of whales sighted around the Hachijo Islands should be determined and comparedwith those of whales reported in other wintering grounds to clarify the habitat use of the waters aroundthis island.
Causes of sudden appearance
The abundance of humpback whales in the North Paciﬁc Ocean declined from approximately 15,000 in 1905 to 1,000 in 1965 because of catch in commercial whaling (Johnson and Wolman, 1984). Following the prohibition of commercial whaling of this species in 1966 by the International Whaling Commission, the number of humpback whales increased. More recently, theabundance of humpback whales in the North Paciﬁc Ocean was estimated to be 21,063, which isgreater than the estimates of pre-whaling abundance (Barlow et al., 2011). This explosive increase in
the number of humpback whales in the North Paciﬁc Ocean may be one of the reasons for the sudden
appearance of these whales around the Hachijo Island in winter. In fact, the expansion of the wintering
grounds of humpback whales with the recovery of their population in the Hawaiian waters has beenreported (Mobley et al., 1999). Similarly, expansion of the wintering grounds was conﬁrmed near

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Peru (Guidino et al., 2014). However, there are no data on the abundance of humpback whales in thewestern North Paciﬁc Ocean after the “Structure of Populations, Levels of Abundance, and Status of
Humpbacks” (SPLASH) study (Barlow et al., 2011). Further, the population dynamics around 2015,
when humpback whales appeared around Hachijo Island, must be clariﬁed to prove this hypothesis. Currently, the stock structure of the population migrating to the Hachijo Island remains unclear.
Therefore, the migratory connections between the Hachijo Island and other wintering grounds in the
North Paciﬁc Ocean and feeding grounds at high latitudes must be established based on photo-identiﬁcation and genetic data. To clarify the cause of the sudden appearance of humpback whales aroundthe Hachijo Island, continuous monitoring at a local scale around the island, and at a broader scale, isimperative.
Acknowledgements

The ﬁeld survey was ﬁnancially supported by the Hachijo Town Oﬃce. The authors express their deep gratitude to Hachijo Town government. We would like to thank the citizens and tourists of Hachijo Island and Hachijo Branch, Tokyo Metropolitan Islands Area Research and Development Center of Agriculture, Forestry and Fisheries for providing helpful sighting
information and the Hachijojima Tourist Information Center for summarizing the sighting information. The authors thank Y.
Yamamoto and E. Kono of Japan Broadcasting Corporation (NHK) for enabling the ﬁrst investigation on the Hachijo Island.
The authors would like to thank the Captain of the research vessel, N. Akama. The authors are also grateful to M. Yamaguchi, Y. Kim, and all other researchers of Tokyo University of Marine Science and Technology for their assistance with thepresent surveys. Finally, we would like to express our sincere thanks to the anonymous reviewers.

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Received: January 26, 2021
Accepted: July 7, 2021
Published online: November 8, 2021

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J-STAGE Advance published date: December 22, 2021

WESTERN NORTH PACIFIC KILLER WHALE CRANIUM GROWTHGROWTH-RELATED CHANGES IN CRANIUM OF
KILLER WHALES IN THE WESTERN NORTH PACIFIC
Megumi TAKAHASHI1*, Gen NAKAMURA2 and Hidehiro KATO1, 2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, JapanTokyo University of Marine Science and Technology, 4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan*Corresponding author: takahashi@cetacean.jp
12

Abstract
One of the crucial questions for using the skull morphology for classiﬁcation purposes incetaceans is whether the skull features have growth-dependent diﬀerences. This question wasaddressed by examining cranial specimens collected from killer whales in diﬀerent localitiesof the western North Paciﬁc. The present study is the ﬁrst to investigate developmental change
in the skull morphology of western North Paciﬁc killer whales. A total of 24 cranial measurement characters were examined from 22 animals collected between 1937 and 2011. Two kindsof analyses were conducted 1) the relationships between body length (BL) and cranium length(condylobasal length CBL), and 2) between CBL and each measurement character. For theseanalyses, an allometric equation was used. The relationship between BL and CBL showed anegative growth pattern, consistent with previous studies in delphinid species. The length ofthe lacrimal bone and the width of the internal nasal cavity showed isometric change. Therefore, these characters can be used as criteria for sex and/or species/subspecies classiﬁcation as
their proportions are free from relative change with respect to skull growth in CBL. Regarding
ontogenic growth, this study showed that the anteroposterior length of the temporal fossa, thezygomatic process and the space where the temporal muscle passes became proportionallylarger as their skull grows. The development and activity of temporal muscles would produce
these changes. On the morphometric features involved in the generation and modiﬁcation of
acoustic signals, this study found the following changes: the width of the posterior regions of
the rostrum and preorbital bone became wider; the ventral surface of the preorbital process
became thick and sturdy, and the maxillary crest became more apparent with the skull growth.
Therefore, these morphometric features might be used to characterize species/subspecies of
the killer whales, which have highly divergent foraging behavior and vocalization.
Key words:

killer whale, skull morphology, growth-related change, western North Paciﬁc.

Introduction
The skull is an anatomical feature that consistently and compellingly displays species-speciﬁc characteristics and is an essential tool to study morphological diﬀerentiation (Miyazaki, 1994). Hence, theskull size and shape can be essential as classiﬁcation criteria. Studies on small cetaceans showed thatthe shape and size of the skull could provide information on geographical distribution of the species,
intraspeciﬁc subpopulations with diﬀerent ecological characteristics such as feeding ecology andacoustic properties, and social behavior, e.g., Van Waerebeek (1993), Yoshida et al. (1995), Galatius
and Gol’din (2011), Costa et al. (2016). Kitchener et al. (1990) studied the skull morphology of false
killer whale Pseudorca crassidens from three ocean basins, Australia (n=34), Scotland (n=58), andSouth Africa (n=53), showing considerable divergence among localities, including sexual dimorphism in the skull morphology. They considered this helpful information for the conservation andCetacean Popul. Stud. (CPOPS), Full paper
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management of the species.
Comparative analyses of skull morphology require large sample sizes; however, the availabilityof samples and data for such studies is limited for most cetacean species, including the killer whales
Orcinus orca. Killer whales are distributed throughout all oceans and contiguous seas, from equatorial
regions to the polar pack-ice zones. Still, they are most numerous in coastal waters and cooler areas
where productivity is high (Rice, 1998). Their wildly divergent diet preferences, cultural practices,and external morphological characteristics seem incongruent with their current categorization as asingle taxon (Heyning and Dahlheim, 1988; Pitman and Ensor, 2003; Foote et al., 2009; Morin et al.,2010; Pitman et al., 2011). Resident, transient and oﬀshore killer whale ecotypes have been well characterized since the 1980s in the eastern North Paciﬁc (Bigg et al., 1990).
Further west of the North Paciﬁc, a report identiﬁed multiple killer whale subpopulations throughout the Aleutian Islands: one subpopulation in the eastern and one in the central Aleutian Islands, anda third subpopulation ranging from the western Aleutians to Kamchatka and the Kuril Islands, Russia (Parsons et al., 2013). Recent colonization/re-colonization of the western North Paciﬁc by small
groups of killer whales originating from the central/eastern North Paciﬁc has been suggested (Filatova
et al., 2018). Although the information on this species around Japan is limited, catch records between
1948 and 1957 indicated killer whales were distributed in the coastal waters oﬀ Japan from Hokkaido
to the Okinawan islands. Researches in diﬀerent oceans have revealed the existence of sympatric populations displaying morphological, dietary, and genetic diversiﬁcation e.g., in the Antarctic (Pitman
and Ensor, 2003; LeDuc et al., 2008) and the North Atlantic oceans (Foote et al., 2009, 2010; Morinet al., 2010). Currently, the taxonomic status of killer whales is undergoing scrutiny and possible revision (Krahn et al., 2004; LeDuc et al., 2008; Morin, 2010; Bruyn et al., 2013).
One important question for using the skull morphology for classiﬁcation purposes is whether theskull features have a nature of growth-dependent diﬀerences. In the present study, this question wasaddressed by examining cranial specimens of killer whales collected from diﬀerent localities in thewestern North Paciﬁc. This study is the ﬁrst one to investigate a developmental change in the skull
morphology of killer whales.

Materials and methods
Samples
The list of samples used in the present study is shown in Table 1. Skull samples of killer whales
were available from diﬀerent museums, aquariums and other institutions in Japan. Killer whales werefrom diﬀerent localities of the Paciﬁc coast of Japan, the Okhotsk Sea, and around the Okinawan Islands. A total of 22 skulls of killer whales (seven females, eight males, and seven individuals with nosex information) were available. Body length information was available for 14 whales.
Morphometric feature
Cranial measurements are given in Table 2. Crania were measured in a straight line using an anthropometer to the nearest 0.1 cm. We did not include the mandible bone in this study because it was lostin several individuals. A total of 24 measurements was used in the statistical analysis (Table 2, Fig. 1).
Most of those measurements have been used previously in taxonomic and population identity studies
of Delphinidae species (Perrin, 1975; Kitchener et al., 1990). In this study the measurements wereidentiﬁed using the preﬁx ‘Vx’ (see Table 2). The body length and sex information were obtained fromeach museum, aquarium or university storing a specimen when possible. The observation of genitalorgans determined sex.

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Fig. 1. Killer whale Orcinus orca cranial measurement points. A: Dorsal view of the cranium, B: ventral view,
C: lateral view, and D: posterior view. Measurement points were determined following Perrin (1975) andKitchener et al. (1990) and are abbreviated according to Table 2.

Statistical analysis
The relationships between body length and skull length, and between skull length and each length
measurement were examined using the following allometric equation:y = βxα(1)

where x is body/skull length, y is skull length/each length measurement, β is the intercept of the lineon the y-axis, and α is the slope of the line, also known as the allometric coeﬃcient. The allometriccoeﬃcients (α) at each measurement site were examined using a t-test for classiﬁcation of three different growth patterns: positive allometry (α signiﬁcantly greater than 1), isometric allometry, andnegative allometry (α signiﬁcantly smaller than 1). Analyses by sex were not conducted because of thelimited number of whales with identiﬁed gender. Although the range of sampling years was vast, we
treated them as one sample collection because of the limited number of specimens available.

Results
Relationship between body length (BL) and skull length (condylobasal length CBL)
The relationship between BL and CBL (Fig. 1) was examined in a subset of 14 killer whale samples
for which body length data were available. The BLs in these whales ranged from 218 cm to 785 cm,
which had CBLs of 43.8 cm and 121.7 cm, respectively (samples No. 15 and 8, respectively in Table 1). The CBL showed a negative growth pattern (y=−0.37x0.78, P<0.001) (Fig. 2), indicating that
CBL growth is relatively slower than that of BL.
Relationship between skull length (CBL) and other cranial measurements
Table 2 shows the results of the allometric analyses for the relationship between CBL and each cranial measurement (see also Appendix).
Skull width, rostral length and width
Four of the ﬁve skull width characters (V5, V6, V12, and V13 in Fig. 1 and Table 2) showed a positive growth pattern, though the width at the tip of the antorbital process of the maxilla (V18) was isometric. The rostral width characters (V2–4 and V19) also exhibited positive allometry with the growthof CBL (Table 2). These results showed the braincase becoming relatively shorter, the rostral length
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Table 1. List of specimens of the killer whales from western North Paciﬁc examined in this study, by sex, age,and locality of sampling. Body length (BL) and skull (condylobasal) length (CBL) are also shown.
Sample
no.

Sex

BL
(cm)

CBL
(cm)

Age

LocationYearobtained

Sample ID

Sample holder

1
2
3

F
F
F

547
600
654

98.5
99.2
108.6

—
17*
29*

East China Sea, Okinawa
Nemuro Strait, Rausu
Nemuro Strait, Rausu

1988
2005
2005

M67 (nago-B)
kaitaku-AKW6
rakuno-AKW9

4

F

614

103.8

—

2008

1.2.7

5

F

589

99.7

>28**

2011

Taiji-6

6

F

563

98.3

13*

Paciﬁc Ocean,Kii Peninsula, Taiji
Paciﬁc Ocean,Kii Peninsula, Taiji
Nemuro Strait, Rausu

Nago Museum
Hokkaido Museum
Rakuno Gakuen
University
Port of Nagoya Public
Aquarium
Taiji Whale Museum

2005

7

F

550

99.8

—

Okinawan Island, Japan

1994

AMP-R20AKW2
SUM071

8
9
10
11

M
M
M
M

785
700
704
660

121.7
110.7
118.2
107.9

—
—
—
—

1957
1988
2010
1978

Suma-K01
M66 (nago-A)
SNH10057
Taiji-2

12

M

—

122.0

—

1937

13

M

690

120.6

—

KPMNF1002979
Taiji-1

Kanagawa Prefectural
Museum of Natural History
Taiji Whale Museum

14

M

410

85.1

—

Seto Inland Sea, Hyogo
East China Sea, Okinawa
Soya Strait, Wakkanai
Paciﬁc Ocean,Kii Peninsula, Taiji
Okhotsk, Sakhalin Island,
Gulf of Patience
Paciﬁc Ocean,Kii Peninsula, Taiji
Boso Peninsula, Japan

Ashoro Museum ofPaleontology
Okinawa Churashima
Foundation
Suma Aqualife Park
Nago Museum
Okhotsk Museum Esashi
Taiji Whale Museum

O-15

15

M

218

43.8

—

Boso Peninsula, Japan

16

Uk

—

96.5

—

17

Uk

—

96.2

—

18

Uk

—

104.2

—

Toyokoro-cho,
Hokkaido, Japan
Taiki-cho,
Hokkaido, Japan
Japan

19
20
21
22

Uk
Uk
Uk
Uk

—
—
—
—

106.8
104.9
103.4
104.6

—
—
—
—

Kii Peninsula, JapanKii Peninsula, JapanKii Peninsula, Japan
Okinawan Island, Japan

Tobayama’s CetaceanCollection/TUMSAT***
Tobayama’s CetaceanCollection/TUMSAT***
Ashoro Museum ofPaleontology
Ashoro Museum ofPaleontology
Institute of Cetacean
Research
Taiji Whale Museum
Taiji Whale Museum
Taiji Whale Museum
Okinawa Churashima
Foundation

1966

O-11
2005

AMP-R26

2005

AMP-R27
ICR-001
Taiji-3
Taiji-4
Taiji-5
Okinawa-1*: Age information quoted from Amano et al. (2011).
**: Rearing period.
***: Tokyo University of Marine Science and Technology.

(V1) somewhat longer, and the braincase width relatively more comprehensive (Fig. 3). The zygomatic process of the squamosal bone became laterally more protrusive with CBL growth, in qualitative
observation, as the space where the temporal muscle passes (the ventrolateral opening of the temporal
fossa) was getting more enlarged compared to those of the newborn calf (Fig. 4).
BraincaseIn this study, the braincase was deﬁned as the regions directly covering the brain, including thefrontal, maxilla, premaxilla, ethmoid, sphenoid, squamosal, parietal, interparietal and occipital bones(Uekusa et al., 2018). The measurements indirectly describing the braincase size (V22, V23, and V24)
showed negative allometry or isometry, though the length of squamosal (V14), which is not directly

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WESTERN NORTH PACIFIC KILLER WHALE CRANIUM GROWTH

Table 2.

Relative growth coeﬃcients and growth patterns of each killer whale skull region.

RegionSiteno.

Measurement characternBased oncondylobasal
Plength (CBL) value†αlnβ

Relative
Adj. R
growthsquarepattern

Skull width

V13 Greatest width of skull
V5
Greatest preorbital width
V6
Least supraorbital width
V12 Greatest width of maxillaries
V18 Width at tip of anterior process of maxilla

22
22
22
21
21

1.13
1.18
1.24
1.34
1.31

−1.04
−1.44
−1.75
−2.19
−2.14

**
**
**
**
0.075

positive
positive
positive
positiveisometry

0.99
0.97
0.98
0.91
0.76

Rostral length
and width

V1
V2
V3

22
22
21

1.13
1.28
1.35

−1.23
−2.49
−2.78

*
**
**

positive
positive
positive

0.98
0.98
0.89

22
20

1.59
1.91

−4.93
−5.81

**
**

positive
positive

0.91
0.93

Greatest parietal width at the posterior section of 21
the frontal
V23 Greatest occipital width within temporal fossa
20
V24 Height of skull
11
V14 Length of zygomatic process of squamosal (right) 22

0.75

0.14

*

negative

0.75

0.95
1.15
1.28

−0.76
−1.52
−2.95

0.795
0.458
**

isometry
isometry
positive

0.54
0.79
0.98

V8

22

1.20

−2.01

**

positive

0.97

21

1.07

−1.91

0.744

isometry

0.57

20

1.35

−3.37

*

positive

0.87

21

1.40

−3.60

0.054

isometry

0.72

Braincase

Temporal fossa

Length of rostrum
Width of rostrum at baseWidth of rostrum at 60 mm anterior to the base of
rostrum
V4
Width of premaxillaries at midlength of rostrum
V19 Width of rostrum at 3/4 length, measured fromposterior end
V22

Greatest length of right temporal fossa, measured
to external margin of raised suture
V9Greatest width of right temporal fossa at right angles to greatest length
V15 Anteroposterior diameter of the ventrolateral
opening of the right temporal fossa
V16 Lateral diameter of the ventrolateral opening of
the right temporal fossa

Nasal area

V7
V20
V21

Greatest width of external nares
21
Greatest width of internal nares
20
Distance from foremost end of junction between 19
nasals to hindmost point of margin of supraoccipital crest

0.85
0.95
0.76

−1.27
−1.52
−1.19

0.398
0.32
0.08

isometry
isometry
isometry

0.55
0.95
0.65

Orbital region

V10

Length of right orbit from apex of preorbital pro- 22
cess of frontal to apex of postorbital process
Length of antorbital process of right lacrimal
22
The antorbital process thickness: the distance 21
from the ventral surface of the lacrimal to thedorsal surface of the maxilla (right-side)

0.53

0.08

**

negative

0.70

1.17
1.84

−3.12
−5.90

0.307
**

isometry
positive

0.72
0.79

V11
V17

: The signiﬁcance of deviation of each relative coeﬃcient from a value of 1 (*: P<0.05, **: P<0.01).

†

related to the braincase size, showed positive allometry (Table 2). According to qualitative observations, the parietal bones in the newborn calf’s temporal crest were laterally curved convex in posteriorview, and the greatest parietal width within the temporal fossa was wide as long as the greatest widthof the skull (Fig. 3). However, the temporal surface of the parietal bones concavely curved with CBL
growth and development of the temporal crest.
Temporal fossa
The anteroposterior length (V8) and the dorsoventral width (V9) of the temporal fossa showed
positive allometry and isometry, respectively (Table 2). Hence, the temporal fossa size became relaCetacean Popul. Stud. (CPOPS), Full paper
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Fig. 2. Relationship between body length and condylobasal length (CBL). Black and white circles indicate
males and females, respectively. The solid line indicates the prediction line from allometry analysis.

tively broader with CBL growth (i.e., horizontally with a long, elliptic shape) (Fig. 4). In qualitative
observations, the dorsal and lateral views of the skulls showed that the posterior ends of the temporal
crest are located far anterior to the posterior end of the occipital condyles in the newborn calf (Fig. 3).
However, along with the growth of the CBL, the posterior ends of the temporal crest were extended ina posterior direction, and the crest of the temporal fossa clearly developed, becoming thick and conspicuously ridged.
The anteroposterior diameter (V15) and the lateral diameter (V16) of the ventrolateral opening border of the temporal fossa showed positive allometry and isometry, respectively. These growth patterns
represented an extension of the space where the temporal muscle passes (Fig. 4). The posterior viewof the skull clearly showed the development of the temporal crests and an exoccipital and squamosal
extension with CBL growth (Fig. 3).

Fig. 3. Dorsal (upper) and posterior (lower) view of four male killer whale crania. Condylobasal length (CBL)and width of these crania scaled to the actual length.

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Fig. 4. Ventral (upper), diagonally right rear (middle) and lateral (lower) views of the newborn calf and adultkiller whale cranium. Orange arrows show the measurement points of the ventrolateral opening border of thetemporal fossa, which consists of the zygomatic process of the squamosal bone posteriorly and the postorbital
process of the frontal bone anteriorly (V15 and V16 in Table 2 and Fig. 1). Orange shades cover the estimatedarea where the temporal muscle is attached.

Nasal area
The width of the nares (V7 and V20) and the anterior junction of nasal to posterior margin of supraoccipital crest length (V21) displayed isometry (Table 2). According to qualitative observations,the adult animals’ nasal and surrounding areas (frontal, parietal, and occipital bones) were particularly
protruded in a dorsal direction, which diﬀered from those of the newborn calf (Fig. 4). Frontal and intraparietal bones were hardly visible as they were covered by maxillary and supraoccipital bones.
Orbital region
The orbit length from the apex of the preorbital process of the frontal bone to the apex of the
postorbital process, represented by V10, exhibited negative allometry (Table 2). The antorbital process
thickness deﬁned as the distance from the ventral surface of the lacrimal to the dorsal surface of themaxilla (V17) indicated positive allometry (Table 2). The relative length of the antorbital process of
the lacrimal bone (V11) showed isometry with CBL growth, and it was thick and sturdy throughout
the growth of a newborn into an adult whale (Fig. 4). The surface of the antorbital process, represented by the maxilla bone, remarkably developed in a dorsal direction.

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Discussion
Relationship between CBL and BL
The ratio of CBL to BL of killer whales declined with growth, and negative allometry was detected (Fig. 2). According to previous studies, the growth rate of some delphinid species’ skull decreases
with growth, and they stop growing when their BL reaches a plateau at a certain age (Perrin, 1975;
Ito and Miyazaki, 1990; Kitchener et al., 1990; Miyazaki and Amano, 1994). Therefore, the results ofthe present study agree with those previous studies. Diﬀerences in physical maturity of BL between
sexes are known in some whale species (e.g., short-ﬁnned pilot whale Globicephala macroryhnchus(Miyazaki, 1990), false killer whale Pseudorca crassidens (Baird, 2002; Ferreira et al., 2014)). Killer
whales exhibit a diﬀerence in size according to sex (adult males are longer than females). Sexual dimorphism (especially in external morphology) is evident in the killer whales. For example, profoundsexual dimorphism was observed in the dorsal ﬁn and ﬂipper size (males have larger structures)(Heyning and Dahlheim, 1988). Therefore it is expected that such sex diﬀerences in the relationshipbetween CBL and BL also occur in the killer whales, and future studies should consider comparisons
between females and males.
Utility of skull measurements as classiﬁcation criteria
Isometric changes in some particular skull measurements mean that such measurements can be employed as criteria for sex and/or species/subspecies classiﬁcation as they are not aﬀected by changes
in the skull size. While other measurements also showed an isometric character, the authors consider
that the best candidates to be used as taxonomical classiﬁcation criteria are the lacrimal bone length(V11) and the width of the internal nasal cavity (V20) because these measurements showed isometry(Table 2).
Lacrimal bone length (V11)
The proportion of V11 to the CBL did not change from newborn calf to adult, thus showing thatit might be helpful for sex prediction analysis in all age stages. A previous study that used only adultkiller whales from the western North Paciﬁc reported that the lacrimal bone length was useful for sex
prediction in this species (Takahashi et al., 2019). The study used linear discriminant analysis and a
Random forest algorithm. However, the authors recommended caution in interpreting their results as
the true sexual dimorphism for the population because the number of samples used in the study was
limited. The present study used a comparatively larger sample size, adding calf killer whales and gaining results to support this measurement character’s utility for classiﬁcation criteria: e.g., sex classiﬁcation. Kitchener et al. (1990) reported a signiﬁcant diﬀerence in this measurement between sexes in thefalse killer whale P. crassidens. This would be collateral evidence supporting our results. Therefore,
we conclude that the killer whale lacrimal bone length might be useful for sex prediction regardless of
specimen age.
Width of the internal nasal cavity (V20)
The width of the internal nasal cavity presented an isometry pattern with a high adjusted R squarevalue (>95%). This measurement character might be used as novel criterion to discriminate species
and subspecies of killer whales because 1) the measurement presented a low individual variance,and 2) the proportion of the measurement never changes with growth. Point 2) makes possible that allavailable samples can be used for discriminatory purposes. With larger sample sizes, this measurement
character might be helpful to discriminate between sexes as well.
Maturity and sex information are usually used in studies on taxonomy based on morphometry. The
body shape (not only the skull shape) of immature animals usually diﬀers from that of mature animals.
Such studies require a considerable number of samples to deal with several factors (e.g., sex, maturi-

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WESTERN NORTH PACIFIC KILLER WHALE CRANIUM GROWTHty). However, materials of this kind are hard to obtain in cetaceans. For this reason, the information on
growth-independent changes of some skull measurements in the present study is essential for future
taxonomical studies of the killer whales.
Eﬀect of ontogenetic growth on cranial shape
The allometry of the cranium of the killer whale was examined to clarify the eﬀects of size (i.e.,
ontogenic growth) on cranium shape. Only the width at the posterior section of the frontal bone (V22)
showed clearly negative allometry, although other features related to skull width (e.g., V13) showed
positive allometry. The analyses suggest that the upper maxillaries width (V12) indicates negative allometry while it represents the dorsal part of the braincase, i.e., it is restricted by the brain size. In contrast, the skull width (V13) and the horizontal diameter of temporal fossa proper (V16), which are notdetermined by brain size, showed positive allometry, creating space for the temporal muscle to pass.
In other words, the temporal muscle can be developed with CBL growth.
The temporal muscle is a fan-shaped muscle situated within the temporal fossa of the skull. The
primary function of this muscle is to produce the movements of the mandible at the temporomandibular joint and thus facilitate the act of mastication. In the case of cetaceans, the temporal muscle is also
known as one of the most developed muscles for mouth-closing (Seagars, 1982; Herring, 2007; Kimet al., 2018). A site of origin for the temporal muscle is the temporal fossa represented by V8 and V9
in our study. Although the width of the temporal fossa in a dorsoventral direction (V9) had no positive allometry, the length in an anteroposterior direction (V8) showed a high development with CBL
growth without being limited in a space produced by brain size. By qualitative observation, the posterior ends of these bones consisted of the temporal fossa extending in a posterior direction, over theposterior end of the braincase. These results indicate an extension of the surface and the crest where
the temporal muscle originates (Fig. 4). In addition, the results showed that the space where the temporal muscle passes were expanded with positive allometry and isometry (V15, 16; Fig. 4). Therefore,
the temporal fossa and temporal crest expansion may be caused by the development of muscle thickness. Especially, the posterior extension of the temporal crest might also increase the length of themuscle itself and increase the area of temporal muscle attachment. In the case of the bottlenose dolphin, the allometry of the temporal fossa implies the development of the temporal muscle with CBL
growth, and similar trends in the allometry of these characters between mature and immature specimens indicate that the development of temporal muscle occurs not only in ontogeny but also in larger
specimens among mature individuals (Kurihara and Oda, 2009). In other words, the feeding habit
aﬀects this morphological feature during both the immature and mature stages. This previous study
speculated that the same tendency might occur in the killer whales since they have a habit of catchingand shearing/biting prey (Ford, 2018). Therefore, if this tendency also occurs in mature killer whales
having diﬀerent feeding habits (i.e., ecotype), this morphological feature should be further examined
for a more sophisticated understanding and increased application in taxonomy.
Killer whale’s rostral length and width characteristics showed positive allometry in this study,
which appears to be related to the development of the feeding apparatus. Several studies using a sufﬁcient number of skull samples, e.g., bottlenose dolphin (Kurihara and Oda, 2009), baleen whales(Nakamura et al., 2012), have concluded that the positive allometry of rostral length is related to thefeeding apparatus, i.e., it reﬂects the growth for extension of the range for prey catching (Costa etal., 2016). For the rostral width, it might have been aﬀected by the development of the lateral rostral
muscles inserted at the lateral side at the rostrum. Mead and Fordyce (2009) concluded that the posterior areas of the rostrum (V2 and V3 in this study) and its attached rostral muscles are involved in thefeeding apparatus. Hence these features can reﬂect diﬀerences in feeding habits between populations.
In addition to the width of the rostrum, the present study results suggested that the width from theventral surface of the lacrimal bone (i.e., ventral surface) to the top of the maxillae bone showed positive allometry. Also, the surrounding area, i.e., the antorbital process of the maxillae bone and the
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preorbital process of the frontal bone, became thick, tough, sturdy, and the maxillary crest became
more remarkable with CBL growth. The posterior areas of the rostrum and the area surrounding theantorbital process of the maxilla are suggested that it is involved in the generation and modiﬁcation of
acoustic signals (Mead, 1975; Huggenberger et al., 2009). These portions are covered by the anterointernus muscle and M. maxillonasolabialis anteroexternus, relating the nasal apparatus structure (Huggenberger et al., 2009). Huggenberger et al. (2009) concluded that these muscles might exert a pulling
force on the connective tissue dorsal to the anterior nasofrontal sac and the rostral bursa cantantis. The
lateral region of the M. maxillonasolabialis anterointernus attaches to connective tissue dorsal to theangle and the inferior vestibulum and may control air movement and pressure in the angle and the nasofrontal sac.
Moreover, Cranford et al. (2011) concluded that all extant toothed whales generate sonar signals
using phonic lips and these muscles and tissues. In the killer whales, various and high-frequency
acoustic behaviors are known, and they can be considered as one of the survival strategies or habits by
population/ecotype (Miller and Bain, 2000; Deecke et al., 2005, 2011; Simon et al., 2006). Therefore,
the apparent developmental change in this area might be considered one of the crucial features of eachkiller whale population/ecotypes, and combining previous studies and our morphological report could
provide valuable evidence on taxonomic studies.
Acknowledgements

The authors thank Dr. Kazutoshi Arai, Mr. Hiromi Saeki, Dr. Hiroshi Katsumata, Dr. Etsuko Katsumata and the othermembers of the Kamogawa Sea World; Dr. Hiroshi Sawamura, Director of the Ashoro Museum of Paleontology; Mr. TairaUsui, Curator of the Okhotsk Museum of Art; Dr. Hajime Taru, Chief Curator of the Kanagawa Prefectural Museum of Natural History; Ms. Kiyomi Nakamura, Curator of the Kobe City Suma Marine Aquarium; Mr. Katsuki Hayashi, Director and
Ms. Tamaki Nakae, Curator of the Whale Museum, Taiji Town; Ms. Haruna Okabe and Dr. Nozomi Kobayashi and the othermembers of the Okinawa Churashima Foundation; Mr. Naofumi Murata, Curator of the Nago Museum; Mr. Makoto Soichi,
former Director, Nagoya Port Aquarium; Dr. Miki Mizushima, Curator, Hokkaido Museum; and Dr. Yoshikazu Sato, Professor, Rakunogakuen University and Dr. Takeharu Bando and Dr. Satoko Inoue of the Institute of Cetacean Research. Comments from anonymous reviewers signiﬁcantly improved this manuscript.

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Received: January 31, 2021
Accepted: August 5, 2021
Published online: December 22, 2021

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Appendix
Changes in the proportion of each measured character to the CBL of killer whales in the western
North Paciﬁc. Black, white, and gray indicate male, female, and sex-unknown, respectively. The solidline indicates the prediction line from allometry analyses. Skull morphometric feature measurements
are abbreviated according to Table 2.

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Appendix (Continued).

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J-STAGE Advance published date: May 12, 2021

AGE ESTIMATION FROM TEETH IN LONGMAN’S BEAKED WHALESAGE ESTIMATION FROM TEETH IN LONGMAN’SBEAKED WHALES (INDOPACETUS PACIFICUS)STRANDED IN NEW CALEDONIA (SOUTH PACIFIC)
Christina LOCKYER1* and Claire GARRIGUE2, 3
Age Dynamics, Huldbergs Alle 42, 2800 Kongens Lyngby, Denmark
Institut de Recherche pour le Développement UMR9220 ENTROPIE (IRD, Université de La Réunion,
CNRS, Université de la Nouvelle-Calédonie, IFREMER, Laboratoire d’Excellence–CORAIL,
BPA5, 98848 Noumea, New Caledonia)
3
Opération Cétacés, BP12827, 98802 Noumea, New Caledonia*Corresponding author: agedynamics@mail.dk
1

2

Abstract
Seven Longman’s beaked whales mass stranded in New Caledonia in November 2013, of
which 4 ultimately died, in a ﬁrst worldwide event reported for this poorly known Ziphioid
species. Teeth were extracted, collected and thoroughly cleaned of gum tissue from 3 females
ranging from juvenile to adult and one adult male. These were sectioned (crown-root) and prepared using two diﬀerent methods and examined under microscope magniﬁcation when Growth
Layer Groups (GLGs) in both dentine and cement were successfully identiﬁed. The methods
employed for aging included 1) sectioning centrally at approx. 150 µm through crown and root
on an Isomet circular diamond saw and examining under a microscope using both transmitted
polarised light and plain light; and, 2) thick sectioning (wafering) at approx. 2.5 mm and subsequent decalciﬁation in RDO™ (a proprietory brand, Illinois, USA) and then thin sectioning thewafer at 10–25 µm and staining with Ehrlich’s acid haematoxylin. GLGs were investigated inboth dentine (25 micron) and cementum (10–15 µm). Layering was evident in both tissues but
higher counts were more evident in thin stained sections of cementum. Although dentinal GLGs
in untreated tooth sections have been used successfully for aging in Ziphioid species Hyperoodon ampullatus (Christensen 1973, Feyrer et al., 2020), it is believed this is the ﬁrst time that
teeth have been used for estimating age from GLGs in this tropical species.
Key words:

Age estimation, Ziphioid whales, Indopacetus paciﬁcus, teeth.

Introduction
Longman’s beaked whale (Indopacetus paciﬁcus), ﬁrst described as a large species of the genus Mesoplodon (Longman, 1926) from a beachcast skull found in northern Queensland, Australia, was later
assigned to its own genus, Indopacetus, after comprehensive morphological evaluation (Moore, 1968)
and the discovery of a second skull in Somalia (Azzaroli, 1968). This species has long been considered one of the rarest and least known of all whales. Groups of Indopacetus are encountered withsome regularity in the tropical Indian and Paciﬁc Oceans (Anderson et al., 2006; Afsal et al., 2009;
Yamada et al., 2012), and there have been occasional reports of strandings (<20 stranded animals todate, Yamada et al., 2012) most of which have been singletons, with the exception of a cow-calf pairin Taiwan (Yao et al., 2012). More recently, a stranding was reported oﬀ the Phillipines (Acebes etal., 2019), and two separate strandings were reported oﬀ Okinawa, Japan, including a neonate (Kobayashi et al., 2021, 2021a).
This paper focuses on tooth material and relevant data from a mass stranding of Longman’s beaked
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whales in New Caledonia in the southwest Paciﬁc Ocean, and describes the details of the aging methods used, which may be helpful for researchers investigating more precise age in other beaked whales.
Among the samples collected from three females ranging from juvenile to adult and one adult male,
were the paired teeth, extracted and thoroughly cleaned of gum tissue. The details of the stranding
event are described by Garrigue et al. (2016) when seven animals came ashore together on the south
coast of the Grande Terre on 16 November 2013, four of which ultimately died. Only a brief accountof the age estimation was reported at this time. This is believed to be the ﬁrst worldwide mass stranding event for this poorly known species, and the ﬁrst time tooth layering has been investigated forLongman’s beaked whale.

Methods
Age was estimated using a single tooth from each of the four animals examined and was determined
without other detailed biological information apart from sex and body length. The remaining tooth
was retained untouched for other analyses. Two methods of aging were applied to investigate whichmight be more informative, and are detailed here. Although aging methods have been detailed for other beaked whales—Northern Bottlenose whale Hyperoodon ampullatus (Christensen, 1973; Feyrer etal., 2020)—Longman’s beaked whale is a tropical species, and in general little is known about aging
in beaked whales.
Fig. 1 shows the size and shape of a tooth. Each tooth was thoroughly cleaned of gum tissue and 2–3
sections, ca. 150 µm thick, were cut centrally through the crown and root of each tooth, using an Isomet

Fig. 1. The series of photos shows the size and dimensions of a tooth from specimen #4: a) and b) the lengthof the tooth in diﬀerent aspects; c) the greatest width of the tooth; d) the elliptical open pulp cavity at the root.
Only the top 10 mm of the tooth crown are exposed above the gum line which is clearly visible from the darker colour.

Fig. 2. Buehler Isomet low-speed diamond saw for sectioning teeth. The chuck and wood block mount for
the tooth are shown. The tooth is aﬃxed to the wood block using a standard hobby glue gun employing glue
sticks. The glue is easily removed after cutting and can be made easier by soaking the tooth sections and blockin water for some minutes.

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slow-speed circular diamond saw (see Fig. 2).
These thin sections were examined under a binocular dissecting microscope at magniﬁcationx7–x40 using alternately transmitted plain lightand polarized light, focusing on Growth LayerGroups (GLGs) in both dentine and cementum(see Perrin and Myrick Jr., 1980; Lockyer et al.,2016 for GLG deﬁnition). Each GLG observed
was assumed to have been deposited over a
1-year period as validated in other odontocetes
e.g. Physeter macrocephalus (Gambell, 1977),
Globicephala melas (Lockyer, 1993), Tursiops
truncatus (Hohn et al., 1999), Delphinapterus
leucas (Lockyer et al., 2016), and various mamFig. 3. A portable benchtop freezing microtome
mal species (Read et al., 2018). In addition,used for sectioning decalciﬁed teeth. Note the horia thicker central section (wafer) (2–2.5 mm)
zontal cutting plane, the ﬁxed freezing stage and thewas removed from each tooth, again throughmobile blade. The specimen is frozen by means of acrown-root axis adjacent to the ﬁrst thin section,
Peltier device with ﬂowing water in counter current.
and decalciﬁed in a rapid decalcifying solution
The blade is not cooled and the microtome is operRDO™ (a proprietory brand, Illinois, USA) for
ated at room temperature. The temperature of thefreezing stage is generally around −12°C and canup to 15 h. Thin sections of (10–25 µm) of thisbe adjusted by altering the water ﬂow to the device.
central wafer were then made using a freezing
microtome (see Fig. 3) and stained with Ehrlich’s
Acid Hæmatoxylin (EAH) as described for other species (Lockyer, 1993; Lockyer and Braulik 2014;
Read et al., 2018). The thinnest sections were destined for cemental examination and the thicker sections
for dentinal study. In this instance, the thin decalciﬁed sections were placed in large histo-cassettes in an
agitated ripe solution of EAH for up to 45 min until stain uptake was deemed optimal. The sections werethen transferred to water in the histo-cassettes and rinsed thoroughly of excess stain for several minutes.
Subsequently, the sections were transferred into a weak ammonia solution (just a few drops of ammonia
in the solution enough to turn the pH alkaline) and soaked here for about 3 min. until the sections hadturned uniformly from deep red to purple-blue. After a second rinsing in water, the sections were thenexamined wet under a microscope and the best sections were removed for mounting. Sections used forage estimation were ﬂoated onto 5% gelatin-coated microscope slides under water and arranged with amaximum of 2 sections per slide. The slides were then carefully blotted, section downwards, on absorbent paper (a type that does not shed ﬁbres) and then air-dried in a fume cupboard for about 30 min. andpermanently mounted under glass cover slips with DPX, a fast drying mixture of distyrine (a plasticizer)
and xylene. The slides were then allowed to completely dry in the fume cupboard for several days before
examination. Plain transmitted light was then used for examination under a microscope as for the unstained thick sections. Age data estimated from both preparation methods were recorded in both dentine
and cement.

Results
The ages estimated from the diﬀerent sections are presented in Table 1 where both stained anduntreated sections are recorded as well as GLGs in both the dentine and cementum. The ﬁrst point tonote is that for all specimens, the stained sections are generally providing higher GLG counts in both
dentine and cementum, with the exception of the dentine in specimen #6 where no identiﬁable GLGs
could be seen in the stained section. The other point is that cementum is generally providing higher
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counts and greater clarity than the dentine. The most consistent ages for both the adult female #6 andadult male #2 were estimated as 20–22 and >20–26 GLGs respectively, which by analogy with GLG
deposition rate in other cetaceans may be equivalent to years (see review in the Methods). Ages ofthe sub-adult females #4 and #5 were less clear, but #4 was estimated as 8–9 GLGs and #5 as 14–17
GLGs. Figs. 5–7 incl. show the untreated and stained sections of cementum for specimens #2, #5 and#6, respectively. In each case, more GLGs appear to be visible in the stained than in the untreatedsections. The GLGs identiﬁed are those that fall in the range shown for cementum in Table 1. At thisstage when the method of age estimation is experimental, it is unclear whether some of the identiﬁed
Table 1. Age estimates for four whales based on the examination of dentinal and cementum Growth LayerGroups (GLGs) under two diﬀerent treatments (After Garrigue et al., 2016).
SpecimennumberAge-sex classTreatment#2aAdult M,
length 590 cm#4b

No of GLGs2 observed

Overall Age1 Estimate(GLGs)2

DentineCementumunstained
stained

7+++3
20

20+
26

Sub adult F,
length 564 cm

unstained
stained

8
9–12

5++3
8+3

#5c

Sub adult F,
length 590 cm

unstained
stained

8++3
12+3

14
173

14–17 (range 8++ to 17)#6dAdult F,
length 618 cm

unstained
stained12++3
no GLGs
visible20
22

20–22 (range 12++ to 22)

20–26 (range 7++ to 26)
8–9 (range 5++ to 12)

Overall age was based on the modal age from several counts.
One GLG is assumed to be equal to one year but this requires future validation.
3
Addition symbol (+) indicates that more GLGs were present, but were too indistinct to be counted, and multiple+symbols reﬂect therelative amount of indistinct GLGs. In addition, the following comments relate to individual teeth.
aCrown worn down. Some GLGs may be missing. Dentinal resorption in root.
b
The presence of pulp stones interfered with the GLG pattern in the dentine such that it was diﬃcult to count at the base. Cement poorly
stained and ill-deﬁned. Dentinal resorption or decay in the root.
c
GLGs had poor deﬁnition, including double laminae. Dentinal resorption, or decay in root.
d
No dentinal resorption in root.
1
2

Fig. 4. Untreated section 150 microns thickness, of specimen #4: a) complete section examined under plaintransmitted light showing central dentine, surrounding cementum, and large areas of resorption at the dentine-cementum junction in the root; b) dentine examined under polarised ﬁlters, showing GLGs; c) close up of
the resorption area from a) examined under polarised ﬁlters showing pulp stones in the dentine root.

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Fig. 5.

Comparison of cementum in untreated and decalciﬁed stained sections of specimen #2.

Fig. 6.

Comparison of cementum in untreated and decalciﬁed stained sections of specimen #5.

GLGs might actually be accessory lines. Figs. 5–7 all show identiﬁed GLGs in the decalciﬁed andstained cementum, but it is clear that some are darkly stained and others paler; in addition, sometimes
the spacing between layers is not regular but very close appearing double (for example, see GLGs 19
and 21, Fig. 7) suggesting possible accessory lines. The untreated cementum in Fig. 7 shows identiﬁes
only 20 GLGs, indicating that staining may highlight other ultrastructures in addition to GLGs. Readet al. (2018) discuss the signiﬁcance and possible causes of accessory lines in marine mammalianteeth under the topic of tooth anomalies, including periodic changes in nutrition, hormonal levels andenvironmental factors. Presently it is diﬃcult to identify likely factors for this tropical species, notknowing much about the life history.
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Fig. 7.

Comparison of cementum in untreated and decalciﬁed stained sections of specimen #6.

Fig. 8.

Dentinal GLGs in an untreated section of a tooth of Hyperoodon ampullatus.

tum junction in the root region (Fig. 4a, c), while #6 had no such condition.

Discussion and conclusions
Both methods of preparation detailed here were adequate for identifying GLGs in cementum, withslightly higher counts in stained sections. Generally, GLGs were diﬃcult to identify in the dentine which
presented a lower age count than cementum. Thus cemental GLGs would appear to be the preferredtissue for age estimation in Longman’s beaked whale. Stained sections tended to produce higher GLG
counts, but at the moment it is unclear whether accessory lines may be highlighted and what time period

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AGE ESTIMATION FROM TEETH IN LONGMAN’S BEAKED WHALESa GLG represents. However, as suggested above, the norm in most mammals is an annual deposition of
GLGs (Gambell, 1977; Lockyer 1993; Hohn et al., 1999; Lockyer et al., 2016; Read et al., 2018). In thisstudy, the dentine did not provide clear diﬀerentiation of GLGs so that this tissue must be regarded as
unreliable for total age estimation in this species, based on this limited investigation.
Generally, dentinal GLGs are preferred for aging in cetacean teeth (Stewart and Stewart 2014;
Read et al., 2018). In Hyperoodon ampullatus, the dentinal GLGs in untreated tooth sections are thepreferred aging tool, as noted earlier (Christensen, 1972; Feyrer et al., 2020). This is demonstrated inFig. 8 where an untreated section (prepared in the same manner as Indopacetus teeth) shows up to 40
dentinal GLGs. There is no wear at the crown so that all GLGs are represented. There is limited information about aging in Ziphioid whales, and the authors note that teeth of Ziphius cavirostris (prepared

Fig. 9. Comparison of dentinal GLGs in a) untreated and b) decalciﬁed stained sections of teeth of Ziphiuscavirostris.
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in a similar manner as Indopacetus paciﬁcus teeth) presented good GLG resolution in both untreated
and decalciﬁed stained sections of dentine (Fig. 9). It should be noted however, that the cementum inboth Ziphius and Hyperoodon is thinner and less conspicuous than in Indopacetus (compare Fig. 4).
Additionally, unlike Ziphius and Hyperoodon, for which there have been past ﬁsheries (Japan, Norway) when some life history information was learned, there is almost nothing known about Indopacetus, including the extent of its distribution outside tropical waters, if at all. All that can be drawn fromthe methods tried presently is that cementum appears to be the best tissue to use for aging, and decalciﬁying and staining the tissue tends to reveal more detail and thus higher counts than the untreatedsections.
With respect to the presence of mineral resorption in the roots of the teeth of Indopacetus, the cause
is unknown (Fig. 4a, c). It is reported that high levels of cadmium (Cd) in the body can lead to interference in bone mineral structure, speciﬁcally calcium (Kazantsis, 2004; Sughis et al., 2011). Garrigue
et al. (2016) reported high concentrations of Cd in the kidneys and liver of #4, #5 and #6, but coincidentally noted that the lowest concentration was observed in #6, the only animal with no resorption.
In addition #4 had many pulp stones present in the dentine (Fig. 4b, c), the cause of which is again unknown. However, the presence of these structures made reading the dentinal GLGs very diﬃcult. Suchinclusions do not occur in cementum.
It is believed this is the ﬁrst time that teeth have been used for estimating age from GLGs in thisspecies, Indopacetus. These initial results are very promising and may be helpful to others who may
encounter similar specimens. The method may also be helpful in investigating some other beaked
whale species.

References
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beaked whale (Indopacetus paciﬁcus) in the Philippines. Proceedings of the Twenty-Third (World) Biennial Conference
on the Biology of Marine Mammals, Barcelona, Spain.
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whales (Indopacetus paciﬁcus) in the western Indian Ocean. Aquat. Mamm. 32(2): 223–231.
Afsal, V.V., Manojkumara, P.P., Yousufa, K.S.S.M., Anoopa, B. and Vivekanandana, E. 2009. The ﬁrst sighting of Longman’s beaked whale, Indopacetus paciﬁcus in the southern Bay of Bengal. Mar. Biodiv. Rec. 2: e133. doi: 10.1017/
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Azzaroli, M.L. 1968. Second specimen of Mesoplodon paciﬁcus, the rarest living beaked whale. Monit. Zool. Ital. (N. S.) 2(Supplement): 67–79.
Christensen, I. 1973. Age determination, age distribution and growth of bottlenose whales, Hyperoodon ampullatus (Forster),in the Labrador Sea. Norw. J. Zool. 21: 331–340.
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whales alters our understanding of beaked whale reproductive life history. PLoS ONE 15(6): e0235114. doi: 10.1371/
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Gambell, R. 1977. Dentinal layer formation in sperm whale teeth. p. 583–590 In: Angel, M. (ed.) A Voyage of Discovery.
Pergamon Press, Oxford, 696 pp.
Garrigue, C., Oremus, M., Dodémont, R., Bustamante, P., Kwiatek, O., Libeau, G., Lockyer, C., Vivier, J.C. and Dalebout,
M. L. 2016. A mass stranding of seven Longman’s beaked whales (Indopacetus paciﬁcus) in New Caledonia, South Paciﬁc. Mar. Mamm. Sci. doi: 10.1111/mms.12304.
Hohn, A., Scott, M.D., Wells, R.S., Sweeney, J.C. and Irvine, A.B. 1989. Growth layers in teeth from known-age, free ranging bottlenose dolphins. Mar. Mamm. Sci. 5: 315–342.
Kazantsis, G. 2004. Cadmium, osteoporosis and calcium metabolism. Biometals 17: 493–498.
Kobayashi, N., Tokutake, K., Yoshida, H., Okabe, H., Miyamoto, K., Ito, H., Higashi, N., Fukada, S., Yamazaki, K., Higa,
S., Kawazu, I. and Ueda, K. 2021. The First Stranding Record of Longman’s Beaked Whale (Indopacetus paciﬁcus) in
Okinawa, Japan. Aquat. Mamm. 47(2), 153–174. doi: 10.1578/AM.47.2.2021.153
Kobayashi, N., Ozawa, S., Hanahara, N., Tokutake, K., Kaneshi, T., Inoue, K., Okabe, H., Miyamoto, K. and Ueda, K.
2021a. The ﬁrst record of a Longman’s beaked whale (Indopacetus paciﬁcus) newborn neonate found on Miyako Island, Okinawa, Japan. Mar. Biodivers. Rec. 14:4 1–12. doi: 10.1186/s41200-021-00201-z
Lockyer, C.H. 1993. A report on patterns of deposition of dentine and cement in teeth of pilot whales, genus Globicephala.

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Lockyer, C.H. and Braulik, G.T. 2014. An evaluation of age estimation using teeth from South Asian River dolphins (Platanistidae). NAMMCO Sci. Publ., doi: 10.7557/3.3268.
Lockyer, C., Hohn, A.A., Hobbs, R. and Stewart, R.E.A. 2016. Report on the workshop on age estimation in beluga. Beaufort, North Carolina, US, 5–9 December 2011. NAMMCO Sci. Publ. 10. doi: 10.7557/3.3731.
Longman, H.A. 1926. New records of Cetacea, with a list of Queensland species. Mem. Queensl. Mus. 8: 226–278.
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Read, F.L., Hohn, A.A. and Lockyer, C.H. 2018. A review of age estimation methods in marine mammals with special reference to monodontids. NAMMCO Sci. Publ. 10. doi: 10.7557/3.4474.
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cadmium in children: A cross-sectional study. Environ. Health 10: 104. doi: 10.1186/1476-069X-10-104.
Yamada, T.K., Tajima, Y., Yatabe, A., Pitman, R. and Brownell, R.L. Jr., 2012. Review of current knowledge on Indopacetus
paciﬁcus including identiﬁcation of knowledge gaps and suggestions for future research. Report to the Scientiﬁc Committee of the International Whaling Commission, SC/64/SM/26 (unpublished). 10 pp. [Available from the Oﬃce of the
IWC].
Yao, C.J., Yang, W.C., Chen, Y.J., Lin, J.T., Brownell, R.L. Jr., and Chou, L.S. 2012. Two Longman’s beaked whales (Indopacetus paciﬁcus) from Taiwan. Report to the Scientiﬁc Committee of the International Whaling Commission,
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Received: November 1, 2020
Accepted: March 5, 2021
Published online: May 12, 2021

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J-STAGE Advance published date: December 8, 2021

ISODA, MATSUOKA, TAMURA AND PASTENESPATIAL AND TEMPORAL DISTRIBUTION OF
FLOATING MARINE MACRO DEBRIS IN
THE INDO-PACIFIC REGION OF THE ANTARCTIC
Tatsuya ISODA1*, Koji MATSUOKA1, Tsutomu TAMURA1 andLuis A. PASTENE1, 2
2

1
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
Project Microbiomes as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia, Centro deEstudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile*Corresponding author: isoda@cetacean.jp

Abstract
Marine debris can aﬀect marine species including whales through ingestion and entanglements.
Surveys of marine debris in the Antarctic waters are very limited. This study investigated theﬂoating marine macro debris occurring in the Indo-Paciﬁc sector of the Antarctic (35°E–145°W),
south of 60°S, based on Japanese sighting surveys conducted between the austral summer seasons
1991/92 and 2018/19. In order to examine the spatial diﬀerences in distribution and density, themarine macro debris data were divided into IWC management Areas IIIE, IV, V and VIW as wellas into CCAMLR Convention Areas. Furthermore, to investigate temporal diﬀerences, the data
were divided into two periods: 1991/92–2004/05 and 2005/06–2018/19. A total of 175 objects
were found, consisting mainly of metal and polymer products. Buoys/ﬂoats constituted the mostfrequent sightings, representing 67% of all marine macro debris found. The density indices (number of marine macro debris observed by 100 n.miles) increased from the ﬁrst to the second period
in all Areas. The increase in the number of marine macro debris between the ﬁrst and second periods was statistically signiﬁcant in Areas IV and V. The larger number of marine macro debris in
the second period (represented predominantly by buoys/ﬂoats) coincides with an increase in ﬁshing activities in the surveyed area. However, the overall number of ﬂoating marine macro debris
in the Indo-Paciﬁc sector of the Antarctic is low and much lower than that reported for the North
Paciﬁc and North Atlantic, and this result is consistent with the low incidence of marine macrodebris found in the stomach of Antarctic minke whales reported for the same sector. Continued
monitoring of ﬂoating marine macro debris is recommended given the increasing trend in thenumber of ﬁsheries and tourist activities in the Antarctic.
Key words:

Antarctic, Japanese sighting survey, marine macro debris, ﬁshing buoy.

Introduction
Marine pollution is deﬁned as the introduction by man, directly or indirectly, of substance or energy into the marine environment (including estuaries) resulting in such deleterious eﬀects as harm toliving resources, hazards to human health, hindrance to marine activities including ﬁshing, impairment of quality for use of sea water and reduction of amenities (GESAMP, 1991). Marine debris, also
known as marine litter, is a kind of pollutant including, among many others, man-made objects suchas polymer bags, buoys, rope, lost ﬁshing lines and nets. Once in the sea, such debris becomes mobile
and their movement, distribution and accumulation pattern depend on oceanic currents and gyres.
A workshop of the International Whaling Commission Scientiﬁc Committee (IWC/SC) agreed that

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FLOATING MARINE MACRO DEBRIS IN THE ANTARCTIC

marine debris, and its contributions to entanglements, exposures including ingestions, and associatedimpacts, including toxicity, is both a welfare and a conservation issue for cetaceans on a global scale(IWC, 2014). Naturally, marine debris can aﬀect other pelagic species as well.
The problem of pollution by marine debris is more frequent and critical in populated areas. Evidence from remote oceanic islands suggests a southward-decreasing, strong latitudinal gradient inlitter densities from subtropical and temperate waters through the subtropical convergence to the Antarctic Polar Front and beyond. That is, there is a clear decreasing trend in marine debris accumulation
with latitude (Gregory and Ryan, 1997; Barnes, 2005). However, in recent years, marine debris has
been recorded in remote places such as sub-Antarctic and Antarctic regions (Barnes et al., 2010; Ivar
do Sul et al., 2011). The sources of this pollutant in the Antarctic could be global oceanic debris drifting across the Antarctic Polar Front or debris from tourism and ﬁsheries activities, which have been
increasing in sub-Antarctic and Antarctic areas (Lamers et al., 2008; CCAMLR, 2012).
As indicated above, ﬂoating marine debris could be a threat aﬀecting the welfare and conservationof large whales migrating to the Antarctic each austral summer for feeding. Such threats could bethrough entanglements, ingestions, and associated impacts, including toxicity (IWC, 2014; Baulch andPerry, 2014). For this reason, it is important to monitor the type, number and distribution of ﬂoating
marine debris in the Antarctic feeding grounds. Unfortunately, previous studies of this kind are very
scarce in the Antarctic. Suaria et al. (2020) investigated the abundance of ﬂoating plastics aroundthe Southern Ocean from a survey conducted during the Antarctic Circumnavigation Expedition in
2016/17, and the authors conﬁrmed the Southern Ocean as the region with the lowest concentrationof plastic globally. The IWC International Decade for Cetacean Research-Southern Ocean Whale andEcosystem Research (IDCR-SOWER) conducted observations on ﬂoating macro debris in 1987/88(Matsuoka et al., 2003) and up to 2009/10 when the survey was completed (Murase et al., 2020). Although a brief summary was presented in Murase et al. (2020), analyses of the data collected are yet tobe conducted. The authors found low occurrence of marine macro debris in the Antarctic.
The main objective of this study was the investigation of the spatial and temporal distribution of
ﬂoating marine macro debris in the Indo-Paciﬁc sector of the Antarctic. The study is based on observations conducted from systematic vessel-based sighting surveys of the former research programs
JARPA/JARPAII (Japanese Whale Research Program under Special Permit in the Antarctic, Phases I
and II) (Government of Japan, 1987, 1989, 2005) and NEWREP-A (New Scientiﬁc Whale Research
Program in the Antarctic Ocean) (Government of Japan, 2015), over a period of 28 years. Outputs
from this study could provide valuable information for the development of conservation policies ofwhales and the Antarctic ecosystem.

Materials and methods
Research area
The marine macro debris observations were conducted along the surveys of the JARPA, JARPAII
and NEWREP-A, which had as the main objective the systematic collection of sighting and biological
data of whales in IWC Antarctic management Areas III (0°–70°E), IV (70°–130°E), V (130°E–170°W)
and VI (170°–120°W). The marine macro debris data analyzed in this study were from the eastern partof Area III (IIIE) (35°–70°E), Area IV, Area V and the western part of Area VI (VIW) (170°–145°W),
from 60°S to the ice edge, from where data for a longer period were available (Figs. 1A and 1B). The
marine macro debris data were also summarized according to the Convention Areas of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Figs. 1A and 1B show
the geographical boundaries of the IWC and CCAMLR management areas used for the analyses inthis study. IWC Area IIIE overlaps partially with CCAMLR Divisions 58.4.2–4; Area IV with Divisions 58.4.1–3; Area V with Division 58.4.1 and Sub-area 88.1; and Area VIW with Sub-area 88.2. In
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Fig. 1A. The sighting eﬀort (n.miles surveyed by Lat. 1°×Long. 1° square) of the JARPA survey in the
Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1995/96 to 2004/05 (ﬁrst period, a totalof 50,476 n.miles surveyed). The ﬁgure also shows the geographical boundaries of the IWC and CCAMLR
management areas used for the analyses in this study.

Fig. 1B. The sighting eﬀort (n.miles surveyed by Lat. 1°×Long. 1° square) of the JARPAII and NEWREP-A
surveys in the Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 2005/06 to 2018/19 (second period, a total of 52,328 n.miles surveyed). The ﬁgure also shows the geographical boundaries of the IWC
and CCAMLR management areas used for the analyses in this study.

this regard, the data of marine macro debris collected in the Indo-Paciﬁc sector of the Antarctic can be
useful for these two international organizations. CCAMLR management areas involve the terminology‘Areas,’ ‘Divisions’ and ‘Sub-areas.’ For practical purposes, in this study these are referred simply as
CCAMLR ‘Areas.’
As the surveys were limited to waters south of 60°S, i.e., south of the Antarctic Polar Front, whichacts as a barrier of debris movement from lower latitude waters to the Antarctic (see above), the emphasis of this study was on longitudinal diﬀerences in the distribution of marine macro debris, given
the wide longitudinal span of the surveys in the Indo-Paciﬁc sector.
Research period
Marine macro debris surveys were conducted mainly during January–February, in the austral summer seasons between 1991/92 and 2018/19.
Survey procedure
Observation of marine macro debris was carried out from the platform of sighting vessels participating in JARPA, JARPAII and NEWREP-A. The main objective of the sighting vessels was the200

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collection of sighting data of whales for abundance estimation purposes. Although the protocol of thesurveys included the observation of ﬂoating marine macro debris along the track-lines, they could not
be considered as dedicated marine macro debris surveys. Details of the general sighting survey procedures can be found in Nishiwaki et al. (2006) and Nishiwaki et al. (2014). Basically, the sighting
vessels followed a pre-determined zig-zag track-line at a speed of 11.5 knots. The sighting surveys
involved two observers on the top platform (19 m high from the sea level) and ﬁve observers on theupper bridge platform (11 m high from the sea level). Sighting surveys, including the observationsof marine macro debris on the sea surface, were carried out from the platforms using a scaled binocular developed by the Institute of Cetacean Research and FUJINON (FUJINON 7×50 FMT-SX;
7×50 mm, ICR model). The vessel did not deviate from the track-line when an item of marine macrodebris was sighted.
Marine macro debris data were recorded separately for sighting surveys conducted ‘on eﬀort’ (primary observers were present at the relevant observation platforms) and ‘oﬀ eﬀort’ (marine macro debris recorded during drifting, transit and experiments). For each observation, the type of marine macrodebris, the sighting date and the geographical position were recorded. When feasible, pictures weretaken.
The surveys focused on marine macro debris objects of sizes approximately 300 mm or larger (estimated visually by experienced observers). It should be noted that the sighting probability of small objects decreases with distance from the vessels. As a consequence, some small objects occurring at long
distances could have been missed. However, the survey procedures were exactly the same for each annual survey in the 28-year period, so the comparison of density indices (see below) between temporal
strata is still a valid approach in relative terms.
Data analysis
To examine geographical diﬀerences in distribution, marine macro debris data were grouped by
IWC management Area and CCAMLR Convention Areas. To investigate temporal trends in the Areas, marine macro debris data were grouped into two periods: 1991/92–2004/05 (ﬁrst period) and2005/06–2018/19 (second period). This temporal division was made so that the sighting eﬀort (searching nautical miles) was evenly distributed between the two periods. In making this temporal division
it was also considered that ﬁshery and tourist activities in the Antarctic had increased from the 2000’s(see Fig. 1 in Lamers et al., 2008 and Figs. 6 and 7 in CCAMLR, 2012), and therefore an increase in
the number of marine macro debris was expected for the second period.
No sighting survey was conducted in the seasons 2010/11, 2011/12 and 2013/14. Observations ofmarine macro debris between the seasons 1991/92 and 1994/95 were made under both ‘on eﬀort’ and‘oﬀ eﬀort,’ however, the type of eﬀort was not recorded. Therefore data in this period were not used
when the density indices (see below) were calculated.
The density index (the number of marine macro debris observed per 100 n.miles) was calculated foreach management Area in each of the two periods, based on the marine macro debris data collectedunder ‘on eﬀort’ mode. The number of marine macro debris per unit area is an alternative method toassess its geographical and temporal distribution. Given the number and complexity of each IWC andCCAMLR area examined, the density index was selected for practical purposes.
A chi-square test was used to assess the diﬀerences in the number of marine macro debris between
periods based on the expected frequency of 50 : 50.

Results
Sighting eﬀort
Figs. 1A and 1B show the sighting eﬀort expressed in nautical miles, surveyed in the ﬁrst andCetacean Popul. Stud. (CPOPS), Full paper
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second periods, respectively. The searching eﬀort was similar in both periods, 50,476 n.miles and52,328 n.miles in the ﬁrst and second periods, respectively.
Floating marine macro debris
Tables 1A–1C show the number of marine macro debris in the whole (A), ﬁrst (B) and second (C)periods, respectively, grouped by the IWC Areas. A total of 175 observations of marine macro debris
were recorded between 1991/92 and 2018/19 (15 metallic objects, 159 polymer products and one
object of unknown material). Buoys/ﬂoats made of polymer (Fig. 2) accounted for 67% of all marine
macro debris. Most buoys/ﬂoats observed were single objects. The total numbers of marine macro
Table 1A. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPA, JARPAII and NEWREP-A between the austral summer
seasons 1991/92 and 2018/19, by IWC Area and eﬀort (on and oﬀ).

*Observed on the surface as single objects, however, at least in eight cases, several objects were observed; those cases were counted as a single observation. Material ofbuoys/ﬂoats was considered to be polymer, in addition to Styrofoam and rubber.
**Two ropes, two tanks, one ball, one sheet, and two unknown products.
***A squared box of unknown material.

Table 1B. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPA, between the austral summer seasons 1991/92 and 2004/05(ﬁrst period), by IWC Area and eﬀort (on and oﬀ).

Table 1C. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPAII and NEWREP-A, between the austral summer seasons
2005/06 and 2018/19 (second period), by IWC Area and eﬀort (on and oﬀ).

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Fig. 2. Example of a single ﬂoating marine macro debris observed at two distances from the vessel at position
67°S, 179°W (IWC Area V; CCAMLR Sub-area 88.1) during the 2013/14 austral summer season. Picture by
one of the authors (KM).
Table 2A. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPA, JARPAII and NEWREP-A between the austral summer
seasons 1991/92 and 2018/19, by CCAMLR Area and eﬀort (on and oﬀ).

Table 2B. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPA, between the austral summer seasons 1991/92 and 2004/05(ﬁrst period), by CCAMLR Area and eﬀort (on and oﬀ).

Table 2C. Summary of ﬂoating marine macro debris recorded during systematic sighting surveys in the
Indo-Paciﬁc sector of the Antarctic by JARPAII and NEWREP-A, between the austral summer seasons
2005/06 and 2018/19 (second period), by CCAMLR Area and eﬀort (on and oﬀ).

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debris were 48 and 127 in the ﬁrst and second periods, respectively. The buoys/ﬂoats were the main
marine macro debris in both periods but its percentage was higher in the second period (52% and 73%
in the ﬁrst and second period, respectively).
A similar pattern was observed when the data were grouped by CCAMLR Areas (Tables 2A–2C).
Geographical distribution of marine macro debris
Figs. 3A and 3B show the geographical distribution of marine macro debris in the ﬁrst and second
periods, respectively, in both IWC and CCAMLR Areas. In the ﬁrst period, the marine macro debris(mainly buoys/ﬂoats) were concentrated near the borders between IWC Areas but they were more
widely distributed through the CCAMLR Areas. In the second period, the distribution of marine macro debris (mainly buoys/ﬂoats) was notably wider in both IWC and CCAMLR Areas, and they wereconcentrated mainly in Areas IV (CCAMLR Areas 58.4.1–3) and V (CCAMLR Areas 58.4.1 and88.1), reﬂecting perhaps the larger searching eﬀort spent in those Areas.
The most southerly marine macro debris sighting was a buoy in the Ross Sea, at position 76°S,
171°W (IWC Area V, CCAMLR Area 88.1).
Density index
Tables 3A–3C show the density indices in the whole (A), ﬁrst (B) and second (C) periods, respec-

Fig. 3A. Distribution of marine macro debris sighted by JARPA survey in the Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1991/92 to 2004/05 (ﬁrst period) (on and oﬀ eﬀort), by IWC andCCAMLR management areas.

Fig. 3B. Distribution of marine macro debris sighted by JARPAII and NEWREP-A surveys in the Indo-Paciﬁc
sector of the Antarctic during the austral summer seasons 2005/06 to 2018/19 (second period) (on and oﬀ
eﬀort), by IWC and CCAMLR management areas.

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tively, grouped by the IWC Areas. The index for all Areas and period was 0.12. The largest index wasin Area V and the smallest in Area IIIE. The density indices increased between the ﬁrst and second
period in all Areas. A chi-square test resulted in signiﬁcant temporal diﬀerences in the number of marine macro debris in Areas IV (chi-square=7.36, df=1, p=0.007) and V (chi-square=20.25, df=1,
p＜0.001). However no signiﬁcant diﬀerences were found between periods when the density indiceswere used. It is likely that the values of density are too low to detect any diﬀerence. No signiﬁcantdiﬀerences were found in the number of marine macro debris between the ﬁrst and second periods inAreas IIIE (chi-square=0.50, df=1, p=0.480) and VIW (chi-square=0.33, df=1, p=0.564).
Tables 4A–4C show the density indices in the whole (A), ﬁrst (B) and second (C) periods, respectively, grouped by the CCAMLR Areas. The pattern found is very similar to the analysis of IWC
Areas. The largest index was in Area 58.4.1 and the smallest in Area 58.4.2–4. The density indicesincreased between the ﬁrst and second periods in all Areas. A chi-square test resulted in signiﬁcanttemporal diﬀerences in the number of marine macro debris in Area 58.4.1 (chi-square=19.93, df=1,
p＜0.001) and 88.1 (chi-square=9.26, df=1, P=0.002). However no signiﬁcant diﬀerences were
found between the two periods when the density indices were used. No signiﬁcant diﬀerences in the
Table 3A. The searching distance (n.miles), number of marine macro debris and density indices (numberof marine macro debris observed per 100 n.miles) during JARPA, JARPAII and NEWREP-A surveys in the
Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1995/96 to 2018/19, by IWC Area (datafor the period 1991/92–1994/95 were not used for the reasons explained in the ‘Data analysis’ section).

Table 3B. The searching distance (n.miles), number of marine macro debris and density indices (number ofmarine macro debris observed per 100 n.miles) during JARPA survey in the Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1995/96 to 2004/05 (ﬁrst period), by IWC Area (data for the period
1991/92–1994/95 were not used for the reasons explained in the ‘Data analysis’ section).

Table 3C. The searching distance (n.miles), number of marine macro debris and density indices (number ofmarine macro debris observed per 100 n.miles) during JARPAII and NEWREP-A surveys in the Indo-Paciﬁc
sector of the Antarctic during the austral summer seasons 2005/06 to 2018/19 (second period), by IWC Area.

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Table 4A. The searching distance (n.miles), number of marine macro debris and density indices (numberof marine macro debris observed per 100 n.miles) during JARPA, JARPAII and NEWREP-A surveys in the
Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1995/96 to 2018/19, by CCAMLR Area
(data for the period 1991/92–1994/95 were not used for the reasons explained in the ‘Data analysis’ section).

Table 4B. The searching distance (n.miles), number of marine macro debris and density indices (number ofmarine macro debris observed per 100 n.miles) during JARPA survey in the Indo-Paciﬁc sector of the Antarctic during the austral summer seasons 1995/96 to 2004/05 (ﬁrst period), by CCAMLR Area (data for the period 1991/92–1994/95 were not used for the reasons explained in the ‘Data analysis’ section).

Table 4C. The searching distance (n.miles), number of marine macro debris and density indices (number of marine macro debris observed per 100 n.miles) during JARPAII and NEWREP-A surveys in the Indo-Paciﬁc sectorof the Antarctic during the austral summer seasons 2005/06 to 2018/19 (second period), by CCAMLR Area.

number of marine macro debris were found between the ﬁrst and second periods in Areas 58.4.2–4(chi-square=0.47, df=1, p=0.491) and 88.2 (chi-square=0.33, df=1, p=0.564).

Discussion
The present study summarized the spatial and temporal distribution of marine macro debris in
the Indo-Paciﬁc sector of the Antarctic based on data collected systematically over a period of 28
years. The data were organized based on the management areas of two international organizations incharge of the conservation and management of Antarctic marine living resources, the IWC and the
CCAMLR. Although similar surveys have been conducted previously in the Antarctic (e.g., Matsuoka
et al., 2003; Suaria et al., 2020), the present study is the ﬁrst to report marine macro debris information which were collected along systematic sighting surveys in the same region (Indo-Paciﬁc sector of
the Antarctic) over a long period of time (28 years).

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Marine debris has been increasing worldwide and one of the main concerns is the negative eﬀect of
this kind of pollutant on marine species through ingestion and entanglements (see reviews by Panti etal., 2019; IWC, 2020). Emphasizing the importance of this subject, two international workshops were
held recently to discuss the interaction between marine mammal and marine debris, and to deﬁne future research plans (Panti et al., 2019; IWC, 2020).
The main results of the present study can be summarized as follows: i) the occurrence of ﬂoating
marine macro debris in the Indo-Paciﬁc sector of the Antarctic is low, and much lower in comparison
with the occurrence in other oceans of the world; ii) buoys/ﬂoats made of polymer were the main marine macro debris found in this sector of the Antarctic, comprising 67% of all marine macro debris observed; iii) the largest density indices were found in IWC Areas IV and V (and CCAMLR Areas 58.4.1
and 88.1); and iv) there is an increasing temporal trend of marine macro debris (particularly buoys/
ﬂoats) in all Areas, which was statistically signiﬁcant in IWC Areas IV and V (and CCAMLR Areas
58.4.1 and 88.1).
Regarding i) above, the results of low occurrence of marine macro debris in the Antarctic are consistent with the results of Suaria et al., (2020) and the preliminary results of IWC/IDCR-SOWER(Murase et al., 2020). Matsumura and Nasu (1997) reported ﬂoating marine macro debris in the North
Paciﬁc Ocean and its adjacent waters for the period 1987–1991. Their surveys covered approximately 926,000 n.miles and recorded 136,338 pieces of marine macro debris (including natural objects).
About 60% of marine macro debris were polymer products (e.g., ﬁshing gear, Styrofoam products,
and other polymer products). Total densities expressed in number of objects observed per 1 n.mile2
were 20–40 in coastal waters, 0.2 in the north equatorial current area (5°–15°N, across the central Paciﬁc), and 1–3 in the subarctic boundary area (35°–45°N). Barnes and Milner (2005) reported the results of ﬂoating marine macro debris across the entire latitudinal range from the Antarctic to the North
Atlantic. Densities of marine macro debris ranged from 0 to 5 items/km2 in sub-Antarctic and Antarctic waters. Marine macro debris density values have a peak of 10 to 100+ items/km2 in the North Atlantic (English Channel). Clearly, the number of marine macro debris in the Indo-Paciﬁc sector of the
Antarctic is much lower than those observed in the North Paciﬁc and North Atlantic oceans, although
it should be noted that the density index used in the present study is not directly comparable with thedensities reported in other studies.
Points ii), iii) and iv) above are related with the occurrence of buoys/ﬂoats, the main marine macrodebris observed in the Indo-Paciﬁc sector of the Antarctic. Buoys/ﬂoats accounted for about 67% of
all sighted ﬂoating marine macro debris and its density indices increased between the ﬁrst and second
periods. It should be noted that Barnes et al. (2010) recorded three pieces of marine macro debris (apolymer cup and two ﬁshing buoys) in the Dumont d’Urville and Davis Seas (i.e. Areas IV and V)
during a survey conducted in the 2007/08 austral summer season. Figs. 4A and 4B show the annual
trend of the density indices for buoys/ﬂoats in each of the management Areas of IWC and CCAMLR,
respectively. An increasing trend is observed, particularly in IWC Area IV and V (Fig. 4A); and in
CCAMLR Areas 58.4.1 and 88.1 (Fig. 4B), after the 2005/06 austral summer season. It is important toinvestigate the source of the buoys/ﬂoats observed and the reasons for the increasing trend in density
after this season.
Oceanic fronts, such as the subtropical Convergence and Antarctic Polar Front, act as barriers forthe movement of marine debris from low latitude waters to polar areas (Gregory and Ryan, 1997).
Although these barriers are considered permeable by some authors (e.g. Gregory, 2009), the hypothesis that all buoys/ﬂoats observed in the Indo-Paciﬁc sector of the Antarctic were transported fromlower latitudes has a low plausibility. Since the season 2004/05, licensed longline vessels have conducted exploratory ﬁshery for Antarctic toothﬁsh (Dissostichus mawsoni) in CCAMLR Area 58.4.1,
which overlaps partially with IWC management Areas IV and V. The number of licensed vessels in
Area 58.4.1 was four to seven in 2004/05 to 2007/08 seasons, however it decreased to one to three in
2008/09 to 2014/15 seasons (SC-CAMLR, 2012a; CCAMLR, 2013, 2014, 2015). In Area 88.1, which
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Fig. 4A. The trend of the density indices of sighted buoys/ﬂoats by austral summer season and IWC Area,
between 1995/96 and 2018/19 (data for the period 1991/92–1994/95 were not used for the reasons explainedin the ‘Data analysis’ section).

Fig. 4B. The trend of the density indices of sighted buoys/ﬂoats by austral summer season and CCAMLR
Area, between 1995/96 and 2018/19 (data for the period 1991/92–1994/95 were not used for the reasons
explained in the ‘Data analysis’ section).

overlaps partially with IWC management Areas V, one to three licensed longline vessels ﬁshed in the
exploratory ﬁshery for Dissostichus spp. from 1996/97 to 2001/02 (except 10 vessels in 2000/01).
This number increased to more than 10 in 2002/03 to 2011/12 (SC-CAMLR, 2012b), 16 in 2016/17
and 25 in 2017/18 (CCAMLR, 2017, 2018). The number of sighted buoys/ﬂoats increased signiﬁcantly in Areas IV and V after the 2005/06 season, peaked in the 2007/08 season, and then decreased.
However, the decrease in Area V was less prominent than in Area IV (Fig. 4A). The pattern exhibitedin Figs. 4A and 4B mimics the ﬂuctuations of longline ﬁshing operations in these Areas. In addition
to this, operations by IUU (illegal, unreported and unregulated) vessels have been reported in theseareas (SC-CAMLR, 2012a, 2012b). Therefore, it is likely that the buoys/ﬂoats debris observed in the

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present study come from ﬁshing vessels operating in Areas 58.4.1 and 88.1. Although not statisticallysigniﬁcant, the density index increased between the ﬁrst and second period in Area 88.2, where ﬁshingactivities were also reported (see Fig. 1 in Brooks et al., 2020). It should be noted that a loss of ﬁshinggears from bottom longline ﬁsheries targeting Antarctic toothﬁsh operating in Areas 88.1 and 88.2 wasreported in Webber and Parker (2012).
Fishing operations are a source of marine macro debris in the Antarctic, contributing not only to
direct ﬁshing-related debris but also miscellaneous debris items (Ivar do Sul et al., 2011). Webberand Parker (2012) recommended that ﬁshing vessels and/or the CCAMLR observers should record
detailed information on gear loss, in order to estimate unaccounted ﬁshing mortality and to reduce theloss of ﬁshing gear. Such information is also essential to understanding the interaction among whales,ﬁsheries and marine debris.
Despite the increasing trend observed in some areas, the overall number of ﬂoating marine macrodebris in the Indo-Paciﬁc sector of the Antarctic is very low, and this result is consistent with the low
incidence of marine macro debris and entanglements found in the stomach of Antarctic minke whalesin the same sector of the Antarctic (see Isoda et al., this issue).

Conclusions
This study provided the results of the ﬁrst systematic and comprehensive surveys of ﬂoating marine
macro debris in the Indo-Paciﬁc sector of the Antarctic conducted for a period of 28 years. The occurrence of ﬂoating marine macro debris (metal and polymer products mainly) was generally low. The
level of occurrence was substantially lower in comparison with the information reported for other oceanic basins, and this result is consistent with the low incidence of marine macro debris and entanglements found in the stomach of Antarctic minke whales in the same sector of the Antarctic. The main
ﬂoating marine macro debris was ﬁshing buoys/ﬂoats, which increased during the second half of thesurvey period. The probable source of the buoys/ﬂoats are ﬁshing vessels operating in the Antarctic.
Long-term surveys (e.g., JARPA, JARPAII and NEWREP-A) proved to be very useful for collecting
information of marine debris in the Antarctic. This monitoring of marine macro debris is continuing inthe same region under the Japanese Abundance and Stock-structure Surveys in the Antarctic (JASS-A)
program (Government of Japan, 2019) since the 2019/20 season. It is recommended that periodical
analyses of marine macro debris are conducted and reported in the future.
Acknowledgements

We would like to thank all of the captains, crew members, cruise leaders and researchers onboard the research vessels of
JARPA, JARPAII and NEWREP-A surveys for their contributions in collecting the data used in this study. We also thank theanonymous reviewers for useful comments that improved the manuscript notably.

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Res. Manage. (Suppl.) 15: 519–541.
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(unpublished). 38 pp. [Paper available from the Oﬃce of the IWC].
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Matsuoka, K., Ensor, P., Hakamada, T., Shimada, H., Nishiwaki, S., Kasamatsu, F. and Kato, H. 2003. Overview of minke
whale sightings surveys conducted on IWC/IDCR and SOWER Antarctic cruises from 1978/79 to 2000/01. J. Cetacean. Res. Manage. 5(2): 173–201.
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Nishiwaki, S., Ishikawa, H. and Fujise, Y. 2006. Review of general methodology and survey procedure under the JARPA. Paper SC/D06/J2 presented to the IWC JARPA review meeting, December 2006, (unpublished). 47 pp. [Paper available
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Nishiwaki, S., Ishikawa, H., Goto, M., Matsuoka, K. and Tamura, T. 2014. Review of general methodology and survey procedure under the JARPAII. Paper SC/F14/J2 presented to the IWC JARPAII review meeting, February 2014, (unpublished). 34 pp. [Paper available from the Oﬃce of the IWC].
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P. 2019. Marine litter: One of the major threats for marine mammals. Outcomes from the European Cetacean Society

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workshop. Environ. Pollut. 247: 72–79. doi: 10.1016/j.envpol.2019.01.029.
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Received: December 12, 2020
Accepted: September 29, 2021
Published online: December 8, 2021

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211

Short note

Surface feeding of a sei whale, North Paciﬁc.

J-STAGE Advance published date: January 31, 2021

SKELETAL MEASUREMENTS OF LARGE CETACEANSSKELETAL MEASUREMENTS ON SOME LARGECETACEAN SPECIES DONE BY SCIENTISTS OFTUMSAT AND ICR
Gen NAKAMURA1*, Ryoko ZENITANI1, 2†, Takeharu BANDO2,
Yoshihiro FUJISE2, Ryuji YAMAMOTO1, 3, Futaba NISHIMURA1,
Ayumi HIROSE1, Yujin KIM1 and Hidehiro KATO1, 2
Laboratory of Cetacean Biology, Tokyo University of Marine Science and Technology,
4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, Toyomi Shinko Building 5F,
4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
3
Association of Ayukawa Town Planning,
43–1 Ayukawahama minami, Ishinomaki city, Miyagi 986–2523, Japan†
Current address: 7–22–303 Akineshinmachi, Shimonoseki city, Yamaguchi 751–0874, Japan*Corresponding author: gnakam1@kaiyodai.ac.jp
1

Abstract
In the present paper, detailed measurements of the cranium and mandible of the following
large cetacean species and subspecies have been assembled: Antarctic minke whale (Balaenoptera bonaerensis; n=7), dwarf minke whale (B. acutorostrata subsp.; n=8), North Paciﬁc
common minke whale (B. a. scammoni; n=15), sei whale (B. borealis; n=1), Bryde’s whale(B. edeni; n=1) and gray whale (Eschrichtius robustus; n=5).
Key words:

skeletal measurement, Balaenopteridae, Eschrichtiidae, morphometric, large
whale.

The head of an animal contains indispensable organs for survival, such as the feeding apparatus,
sensory and respiratory organs. Because the skeleton supports and protects these organs, its shapeprovides a lot of information about the lifestyle of an animal. Furthermore, the skeleton remains as afossil for hundreds of millions of years and can be used for phylogenetic studies. Therefore, the characteristics of the skeleton, particularly the cranial skeleton, are very important for taxonomical, morphological, anatomical, and paleobiological studies (Miyazaki, 1994). However, skeletal specimensof large whales are quite scarce globally owing to diﬃculties in acquiring the dead bodies of large
whales, high cost and longtime involved in their preservation compared with other mammals, and thelarge space required for their preservation and storage. In addition, the skeletal specimens of large
whales that are available are often assembled and hung in very high places in museums, such as in exhibition halls, making it diﬃcult for scientists to gain access to them for observation.
Dr. Hideo Omura, ex-director of the Whales Research Institute (WRI), vigorously collected skeletal specimens of large whales from the 1950s onward and published many papers on his ﬁndings(e.g., Omura and Sakiura, 1956; Omura, 1957, 1975; Omura et al., 1962, 1969, 1970, 1981). The
authors of this paper inherited his techniques of skeletal measurements that were directly or indirectly
adapted from those he had developed and would like to make the datasets on the skeletal measurements of the following large whale species and subspecies available to others: Antarctic minke whale(Balaenoptera bonaerensis; n=7), dwarf minke whale (B. acutorostrata subsp.; n=8), North Paciﬁc
common minke whale (B. acutorostrata scammoni; n=15), sei whale (B. borealis; n=1), Bryde’s
whale (B. edeni; n=1) and gray whale (Eschrichtius robustus; n=5).
The Antarctic and dwarf minke whales were collected from the Japanese Whale Research ProCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

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NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

gram under Special Permit in the Antarctic (JARPA), which was conducted in the Antarctic Ocean(35°E–145°W) between 1987/88 and 2004/05. The common minke and sei whales were collected fromthe Japanese Whale Research Program under Special Permit in the Western North Paciﬁc (JARPN)
and the Japanese Whale Research Program under Special Permit in the Western North Paciﬁc-Phase
II (JARPN II), which were conducted in the North Paciﬁc during 1994–2016. These surveys wereconducted in accordance with Article VIII of the International Convention for the Regulation of Whaling and all relevant Japanese regulations, and the study protocol was approved by the Governmentof Japan (2004). The surveys were planned and conducted by the Institute of Cetacean Research, theNational Research Institute of Far Seas Fisheries, and the Fisheries Research Agency (IWC, 2001;
2008; 2017).
After external measurements and predetermined observations had been made, the carcasses wereburied in the ground for approximately 2–3 years for the removal of the soft tissues attached to theskeletons. Subsequently, skeleton was dug out and washed to remove any soil and remaining soft
tissues on it. It was then dried, ﬁxed with stainless steel straps, and impregnated with resin to prevent
it from curving. Then, measurements were made, and the methodology and measurement points determined by Omura (1975) as well as some additional points (Figs. 1, 2) were utilized for further assessments. The cranium was oriented so that the tip of the premaxilla and the right and left squamosals
touched the ground, as shown in Fig. 1f, and the straight length of the mandible was measured withthe mandible set ﬂat. Measurements were taken as the distance from point to point down to the nearest
millimeter scale. A stainless-steel caliper was used for straight distances <50 cm, a large 3.5 m anthropometer was used for straight distances >50 cm, and a measuring tape was used for curved lengths.
We provided the measurements of the craniums and mandibles of the Antarctic minke whales,
dwarf minke whales, common minke whales, sei whale and gray whales (Tables 1–5). In each table,
the specimen ID is the number that was assigned to the specimen by the institute or museum storing
the skeleton and the body length is the distance from the tip of the snout to the notch of the ﬂukes.
Skeletal measurements of the gray whales were collected from the animals, stranded or bycaught
around the Japanese coast. These measurements were cited from Nakamura and Kato (2014) withsome minor corrections.
Acknowledgements

We would like to thank the captains, crews, and researchers who were involved in the JARPA, JARPN, and JARPN II
surveys. We also express our gratitude to the staﬀ of Nishio Biological Models Co. Ltd and the members of the laboratory of
Cetacean Biology of Tokyo University of Marine Science and Technology for their assistance in measuring the whale skeletons. The authors would like to express our sincerely thanks to the anonymous reviewers.

References
Government of Japan. 2004. Revised research plan for cetacean studies in the western North Paciﬁc under special permit(JARPN II). Paper SC/56/O1 submitted to the 56th IWC Scientiﬁc Committee, 2004 Jun 29–Jul 12. Sorrento, Italy. 14 p.
International Whaling Commission. 2001. Report of the workshop to review the Japanese Whale Research Programme under Special Permit for North Paciﬁc Minke Whales (JARPN), Tokyo, 7–10 February 2000. J. Cetacean Res. Manage.
3 (Suppl.): 375–413.
International Whaling Commission. 2008. Report of the Intersessional workshop to review data and results from special
permit research on minke whales in the Antarctic, Tokyo, 7–8 December 2006. J. Cetacean Res. Manage. 10 (Suppl.):411–445.
International Whaling Commission. 2017. Report of the expert panel of the ﬁnal review on the Western North Paciﬁc Japanese Special Permit Programme (JARPN II). J. Cetacean Res. Manage. 18 (Suppl.): 529–592.
Miyazaki, N. 1994. Skull morphology of small cetacea. A consideration of taxonomic problems in the Short-ﬁnned Pilot
Whale, Globicephala macrorhynchus, in Japanese waters. Honyurui Kagaku [Mammalian Science] 34: 31–42 (in Japanese with English abstract).
Nakamura, G. and Kato, H. 2014. Osteological characteristics of gray whales Eschrichtius robustus collected from the coastof Japan (1990–2005) and possible population mixing with eastern gray whales in the western North Paciﬁc. Honyurui

216

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

SKELETAL MEASUREMENTS OF LARGE CETACEANS
Kagaku [Mammalian Science] 54: 73–88 (in Japanese with English abstract).
Omura, H. and Sakiura, H. 1956. Studies on the little piked whale from the coast of Japan. Sci. Rep. Whales Res. Inst. 11:
1–37.
Omura, H. 1957. Osteological study of the little piked whale from the coast of Japan. Sci. Rep. Whales Res. Inst. 12: 1–21.
Omura, H. 1975. Osteological study of the minke whale from the Antarctic. Sci. Rep. Whales Res. Inst., 27: 1–36.
Omura, H., Nishiwaki, M., Ichihara, T. and Kasuya, T. 1962. Osteological note of a sperm whale. Sci. Rep. Whales Res. Inst.,
8: 35–45.
Omura, H., Ohsumi, S., Nemoto, T., Nasu, K. and Kasuya, T. 1969. Black right whales in the North Paciﬁc. Sci. Rep. Whales
Res. Inst., 21: 1–78.
Omura, H., Ichihara, T. and Kasuya, T. 1970. Osteology of pygmy blue whale with additional information on external andother characteristics. Sci. Rep. Whales Res. Inst., 22: 1–27.
Omura, H., Kasuya, T., Kato, H. and Wada, S. 1981. Osteological study of the Bryde’s whale from the central South Paciﬁcand eastern Indian Ocean. Sci. Rep. Whales Res. Inst., 33: 1–26.

Received: October 5, 2020
Accepted: November 6, 2020
Published online: January 31, 2021

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NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Fig. 1. Measurement points of the cranium and mandible of balaenopterid species. a) dorsal view of cranium,b) vertex of cranium, c) caudal view of cranium, d) ventral view of cranium, e) tympanic bullae, f) lateralview of cranium, g) dorsal view of mandible, h) lateral view of mandible, i) caudal view of mandible.

Fig. 2. Measurement points of the cranium and mandible of gray whales. a) dorsal view of cranium, b) vertex
of cranium, c) caudal view of cranium, d) ventral view of cranium, e) tympanic bullae, f) lateral view of cranium, g) dorsal view of mandible, h) lateral view of mandible, i) caudal view of mandible.

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SKELETAL MEASUREMENTS OF LARGE CETACEANS

Table 1. Measurements on cranium and mandible with some biological information on Antarctic minke
whales.
Scientiﬁc name

Balaenoptera bonaerensis

Locality

Antarctic

Body length (m)

8.88

8.05

8.53

9.38

9.08

9.28

Sex
Current aﬃliation*

M

M

M

M

M

F

8.97
F

ICR

ICR

ICR

NA

ICR

NA

ICR

Specimen number 87/88 053 87/88 102 87/88 229 89/90 272 93/94 287 89/90 292 01/02 039
1. Condylobasal length

217.8

186.3

213.6

226.4

208.2

223.7

216.3

2. Length of rostrum

146.0

115.6

136.9

152.4

135.0

145.2

143.4

3. Length of premaxillary (L)

159.0

135.3

151.3

165.3

149.7

161.7

155.0

4. Length of premaxillary (R)

159.2

133.6

151.9

166.0

148.3

162.5

155.5

5. Length of maxillary (L)

149.4

130.6

144.8

139.9

148.9

147.0

6. Length of maxillary (R)

148.1

131.8

142.3

138.0

152.6

144.1

7. Tip of premaxillary to tip of maxillary (L)

11.7

7.3

8.7

12.3

10.7

11.6

8. Tip of premaxillary to tip of maxillary (R)

8.9

158.2

8.7

13.0

10.3

10.1

13.8

9. Tip of premaxillary to nares, anterior

148.2

118.2

134.9

151.0

132.6

143.0

136.8

10. Tip of premaxillary to vertex

157.8

135.6

153.9

169.2

150.8

167.1

157.9

11. Tip of premaxillary to palatine, anterior (L)

154.2

119.3

142.6

148.0

140.3

151.7

146.2

12. Tip of premaxillary to palatine, anterior (R)

154.3

121.6

143.2

146.9

139.2

151.4

146.4

13. Tip of premaxillary to palatine, posterior (L)

191.5

160.8

184.9

196.2

178.8

198.1

188.4

14. Tip of premaxillary to palatine, posterior (R)

191.8

160.2

185.2

196.1

177.0

198.4

189.0

15. Tip of premaxillary to pterygoid process (L)

198.6

168.0

193.6

205.6

187.5

206.0

196.0

16. Tip of premaxillary to pterygoid process (R)

198.6

169.0

193.8

205.3

185.4

205.7

195.7

17. Tip of premaxilla to posterior edge of occipital bone (L)

216.0

224.5

18. Tip of premaxilla to posterior edge of occipital bone (R)

214.2

224.3

19. Tip of premaxilla to posterior edge of temporal bone (L)

207.0

216.5

20. Tip of premaxilla to posterior edge of temporal bone (R)205.3

21. Breadth of maxillary, posterior edge
22. Breadth of premaxillary, posterior edge

4.6

23. Tip of premaxillary to anterior end of vomer, median

21.6

17.4

19.1

16.5

3.6

3.5

2.7

5.3

24.9

30.6

28.2

25.3

24. Length of vomer

216.2
21.2

17.0

21.5

30.9

3.7

167.6

170.9

25. Breadth of rostrum at base

64.7

65.7

63.6

69.7

67.4

68.5

64.7

26. Breadth of premaxillary at base

11.3

14.0

13.1

18.9

14.4

18.5

12.7

27. Breadth of rostrum at middle

38.5

44.2

41.6

44.2

43.3

46.8

39.2

28. Breadth of premaxillary at middle

16.6

16.4

15.9

19.1

19.5

17.8

17.6

29. Greatest breadth of premaxillary

25.7

25.8

24.8

26.1

25.8

25.5

24.2

30. Breadth of cranium, maxillaries

98.9

97.6

101.7

105.6

103.3

107.6

98.3

31. Breadth of cranium, anterior edge of zygomatic process

110.5

106.6

108.5

119.5

116.6

114.9

109.3

32. Breadth of cranium, middle of orbital foramen

101.4

100.1

104.0

108.9

107.3

106.9

99.4

33. Breadth of occipital bone

91.3

81.6

85.9

101.8

90.3

81.9

81.8

34. Breadth of cranium, middle of zygomatic process

111.1

108.9

110.8

121.4

114.7

118.3

111.7

35. Length from upper ridge of foramen magnum to superior part of occipital bone

60.0

53.9

61.2

63.6

62.4

37. Length of palatine (L)

42.3

46.1

46.4

43.0

49.5

47.4

38. Length of palatine (R)

41.7

45.6

46.6

42.8

49.0

47.9

39. Breadth of palatine, posterior

31.8

35.1

33.3

34.4

32.6

30.4

40. Breadth across hamular processes of pterygoid

18.4

19.2

14.3

18.8

21.9

22.0

19.8

41. Length of orbit (L)

19.3

19.6

18.8

18.7

21.5

20.9

20.0

42. Length of orbit (R)

19.0

19.3

19.1

19.0

20.5

20.8

20.0

36. Greatest breadth of palatine

61.1

28.2

43. Height of cranium

27.7

60.8

59.6

44. Length of nasals

14.0

17.7

16.3

14.8

19.5

20.3

20.7

45. Breadth of nasal, posterior

4.6

3.5

3.4

2.7

1.8

1.1

1.5

46. Breadth of nasal at middle

8.6

6.8

5.7

8.4

8.0

7.3

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NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Table 1.

Continued.
Specimen number 87/88 053 87/88 102 87/88 229 89/90 272 93/94 287 89/90 292 01/02 039

47. Minimum breadth of parietal bones

24.6

22.4

20.6

16.3

48. Height of foramen magnum

8.6

6.6

9.3

8.5

49. Breadth of foramen magnum

9.0

6.9

8.6

8.1

50. Breadth across occipital condyles

21.5

19.6

22.8

23.0

22.7

51. Breadth of occipital condyle (L)

8.1

9.9

8.9

52. Breadth of occipital condyle (R)

8.7

10.2

9.5

22.2

18.7
9.0
6.6

20.3

21.4
9.8
9.5

53. Height of occipital condyle (L)

14.9

11.8

12.7

12.6

12.8

14.1

14.5

54. Height of occipital condyle (R)

14.5

12.2

12.0

13.3

13.0

12.9

14.4

55. Length of tympanic bullae (L)

10.2

9.1

8.4

9.7

8.9

9.3

9.4

56. Minimum breadth of tympanic bullae (L)57. Greatest breadth of tympanic bullae (L)

5.5
7.4

7.6

6.9

7.5

58. Thickness of tympanic bullae at middle (L)59. Length of mandible, straight (L)

6.8

5.7
7.5

6.8

4.8

4.9

222.0

195.0

218.5

231.1

215.5

227.0

217.0

60. Length of mandible, straight (R)

211.0

184.7

206.4

212.0

201.6

220.0

206.0

61. Length of mandible, curved (L)

210.8

185.1

207.2

215.6

200.0

219.2

206.5

62. Length of mandible, curved (R)

218.8

192.8

217.4

227.9

213.5

228.3

216.0

63. Breadth of mandible at middle (L)

8.0

8.0

8.8

8.1

8.3

7.6

64. Breadth of mandible at middle (R)

8.1

8.2

8.9

8.3

8.3

7.6

65. Height of mandible at middle (L)

16.2

15.8

16.9

17.7

16.0

16.1

66. Height of mandible at middle (R)

15.8

16.7

17.4

17.7

16.4

15.6

67. Height of mandible at coronoid process (L)

26.4

29.3

30.4

30.7

29.3

31.6

28.8

68. Height of mandible at coronoid process (R)

27.7

29.4

30.5

31.1

29.2

30.9

29.1

69. Height of mandible at coronoid (L)

19.6

18.9

20.8

20.2

19.4

22.4

21.3

70. Height of mandible at coronoid (R)

20.1

19.3

20.9

19.5

19.1

21.5

21.3

71. Breadth of mandible at coronoid (L)

14.5

14.3

14.2

14.8

14.7

15.1

16.1

72. Breadth of mandible at coronoid (R)

15.3

13.9

15.3

16.2

14.0

14.5

15.2

* ICR: Institute of Cetacean Research, NA: Nagoya Public Aquarium

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SKELETAL MEASUREMENTS OF LARGE CETACEANS

Table 2.

Measurements on cranium and mandible with some biological information on dwarf minke whales.
Scientiﬁc name

B. acutorostrata subsp.

Locality
Body length (m)Antarctic
7.01

Sex
M
Current aﬃliation* TUMSAT

6.60

5.41

6.99

7.02

5.94

7.07

M

M

F

F

F

F

7.17
F

ICR

ICR

ICR

ICR

ICR

ICR

ICR

Specimen number 87/88 273 88/89 014 89/90 199 88/89 013 88/89 227 88/89 070 89/90 215 92/93 330
1. Condylobasal length

159.7

149.0

122.3

163.4

164.7

133.1

169.2

156.1

2. Length of rostrum

101.4

97.7

81.6

106.0

111.0

83.4

112.0

106.8

3. Length of premaxillary (L)

119.3

109.8

119.4

120.0

97.9

122.8

119.8

4. Length of premaxillary (R)

120.0

109.3

121.3

120.8

98.5

122.4

120.2

5. Length of maxillary (L)

117.2

105.5

114.3

115.2

94.3

119.3

111.4

6. Length of maxillary (R)

117.3

105.0

114.8

115.4

94.1

119.3

112.8

7. Tip of premaxillary to tip of maxillary (L)

4.5

8.3

8.4

10.7

8.7

9.6

10.3

8. Tip of premaxillary to tip of maxillary (R)

4.9

9.2

9.8

10.7

5.7

8.3

10.5

9. Tip of premaxillary to nares, anterior

109.0

96.8

82.2

106.2

109.1

85.9

110.4

104.2

10. Tip of premaxillary to vertex

123.7

116.0

96.3

126.5

128.3

103.7

131.7

125.5

11. Tip of premaxillary to palatine, anterior (L)

99.5

97.8

102.3

108.2

85.8

108.0

100.2

12. Tip of premaxillary to palatine, anterior (R)

99.8

97.8

105.2

107.6

86.9

108.3

100.1

13. Tip of premaxillary to palatine, posterior (L)

134.5

128.1

137.4

142.2

111.7

145.3

135.2

14. Tip of premaxillary to palatine, posterior (R)

134.5

127.6

139.2

141.3

111.7

143.2

135.5

15. Tip of premaxillary to pterygoid process (L)

144.0

134.6

146.3

150.3

119.7

153.8

143.1

16. Tip of premaxillary to pterygoid process (R)

143.8

134.8

119.3

152.3

143.3

17. Tip of premaxilla to posterior edge ofoccipital bone (L)

170.0

156.8

18. Tip of premaxilla to posterior edge ofoccipital bone (R)

169.4

155.9

19. Tip of premaxilla to posterior edge of
temporal bone (L)

164.2

153.5

20. Tip of premaxilla to posterior edge of
temporal bone (R)

164.8

152.2

21. Breadth of maxillary, posterior edge

19.0

22. Breadth of premaxillary, posterior edge

3.0

23. Tip of premaxillary to anterior end ofvomer, median

92.0

78.7
102.8
108.4

165.7

173.4

139.1

177.8

165.3

166.1

172.0

138.7

176.8

165.3

168.7

169.4

136.5

172.2

162.7

124.0

171.2

168.2

136.5

170.7

162.7

14.3

11.6

14.2

19.0

14.0

15.3

17.9

3.2

1.3

3.4

4.8

2.1

3.2

3.0

21.2

18.3

17.9

17.7

21.7

19.3

18.5

16.3

24. Length of vomer

122.4

116.2

93.7

131.3

127.6

107.0

136.5

126.1

25. Breadth of rostrum at base

55.1

51.2

43.8

50.7

53.8

49.2

59.3

58.2

26. Breadth of premaxillary at base

17.3

12.8

11.3

15.4

13.7

11.7

12.8

13.2

27. Breadth of rostrum at middle

31.4

30.5

23.7

30.7

34.2

28.7

36.4

34.8

28. Breadth of premaxillary at middle

12.6

12.7

9.8

12.7

15.2

11.8

16.5

15.4

29. Greatest breadth of premaxillary

22.2

19.2

15.9

20.2

22.3

17.4

22.0

22.8

30. Breadth of cranium, maxillaries

79.1

73.8

57.6

76.0

78.7

65.9

82.8

80.5

31. Breadth of cranium, anterior edge of zygomatic process

89.1

80.8

64.7

84.5

86.3

72.8

91.5

89.4

32. Breadth of cranium, middle of orbital
foramen

80.1

72.3

58.6

77.5

77.7

66.7

83.0

80.4

33. Breadth of occipital bone

69.5

59.3

49.4

63.3

66.4

51.2

62.6

61.7

34. Breadth of cranium, middle of zygomatic
process

89.3

79.4

64.6

82.1

85.3

71.8

88.5

87.7

35. Length from upper ridge of foramen magnum to superior part of occipital bone

40.4

36.4

27.7

40.4

40.2

31.4

43.2

37.3

36. Greatest breadth of palatine

24.8

23.8

18.5

23.3

22.7

21.8

26.5

25.3

37. Length of palatine (L)

36.8

32.3

26.6

37.4

36.2

28.3

37.8

37.7

38. Length of palatine (R)

37.1

32.3

27.0

36.1

35.8

27.3

36.4

37.1

39. Breadth of palatine, posterior

25.3

23.1

21.7

22.8

27.3

21.3

27.7

26.7

40. Breadth across hamular processes ofpterygoid

12.9

11.7

11.6

12.7

13.8

11.3

14.4

12.8

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

127.4

221

NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Table 2.

Continued.
Specimen number 87/88 273 88/89 014 89/90 199 88/89 013 88/89 227 88/89 070 89/90 215 92/93 330

41. Length of orbit (L)

17.0

16.5

14.5

15.0

16.5

15.5

16.5

16.5

42. Length of orbit (R)

16.5

15.5

14.0

16.0

17.0

15.5

16.0

16.5

45.1

37.2

50.0

49.4

34.3

51.5

53.4

43. Height of cranium
44. Length of nasals

14.9

14.5

10.8

16.3

17.8

14.0

18.7

17.8

45. Breadth of nasal, posterior

1.1

1.3

0.8

2.0

2.6

1.1

1.2

1.9

46. Breadth of nasal at middle

4.4

4.9

3.3

5.8

7.1

4.5

6.5

5.3

47. Minimum breadth of parietal bones

18.5

15.3

12.8

16.4

20.1

16.5

19.4

20.0

48. Height of foramen magnum

6.4

7.3

6.3

5.9

6.3

6.6

6.3

6.7

49. Breadth of foramen magnum

8.2

6.0

7.4

7.8

7.1

7.3

6.5

7.3

50. Breadth across occipital condyles

17.0

15.7

13.3

16.7

14.3

15.8

16.8

17.2

51. Breadth of occipital condyle (L)

6.8

6.2

5.3

7.0

6.8

6.6

6.7

6.3

52. Breadth of occipital condyle (R)

6.9

6.5

5.3

7.0

6.3

6.2

6.5

6.8

53. Height of occipital condyle (L)

10.9

10.1

8.6

9.8

8.8

9.2

10.0

9.8

54. Height of occipital condyle (R)

11.1

10.0

8.4

10.0

8.9

9.2

10.0

9.8

55. Length of tympanic bullae (L)

8.3

7.9

7.3

8.2

7.7

8.2

8.3

7.6

56. Minimum breadth of tympanic bullae (L)

4.8

4.9

4.5

5.1

5.1

5.2

57. Greatest breadth of tympanic bullae (L)

6.1

6.1

5.7

6.3

5.9

6.2

4.3

3.8

4.3

4.5

58. Thickness of tympanic bullae at middle (L)

4.8
5.9
4.2

4.0

59. Length of mandible, straight (L)

164.5

155.0

127.0

167.0

170.8

140.0

165.0

60. Length of mandible, straight (R)

155.4

146.0

120.7

157.4

161.0

133.5

61. Length of mandible, curved (L)

156.2

145.8

121.5

158.0

162.0

133.5

167.0

154.5

62. Length of mandible, curved (R)

164.5

154.0

126.0

166.4

170.8

139.9

167.5

165.5

63. Breadth of mandible at middle (L)

7.0

6.4

4.7

6.8

7.5

6.0

6.8

6.8

64. Breadth of mandible at middle (R)

7.0

6.5

4.7

7.1

7.3

6.2

6.8

7.0

65. Height of mandible at middle (L)

10.4

9.8

7.6

10.0

11.1

9.7

11.8

10.6

66. Height of mandible at middle (R)

10.5

10.2

7.7

10.3

11.2

9.5

12.0

10.7

67. Height of mandible at coronoid process (L)

21.5

19.3

16.0

21.0

23.3

18.4

23.2

21.4

68. Height of mandible at coronoid process (R)

21.4

19.4

16.3

21.2

23.2

18.5

23.7

21.6

69. Height of mandible at coronoid (L)

16.8

14.3

12.1

16.1

18.3

14.4

17.3

17.7

70. Height of mandible at coronoid (R)

16.4

14.8

12.3

16.1

18.5

14.4

18.3

17.3

71. Breadth of mandible at coronoid (L)

10.2

9.4

7.7

10.0

10.7

9.3

11.5

11.7

72. Breadth of mandible at coronoid (R)

11.0

9.3

8.0

9.9

10.7

9.1

11.3

11.2

154.8

* ICR: Institute of Cetacean Research, TUMSAT: Tokyo University of Marine Science and Technology

222

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

SKELETAL MEASUREMENTS OF LARGE CETACEANS

Table 3. Measurements on cranium and mandible with some biological information on common minke
whales from the North Paciﬁc.
Scientiﬁc name

B. a. scammoni

Locality

North PaciﬁcBody length (m)

7.31

7.38

7.25

7.53

7.65

7.52

7.51

7.70

Sex
Current aﬃliation*

M

M

M

M

M

M

M

M

M

ICR

ICR

ICR

ICR

ICR

KCM

HM

AMP

AMP

94NP
011

94NP
009

94NP
012

97NP
068

97NP
070

05NPCK 08NPCK 10NPCK 10NPCK
M001
M030
M047
M054

1. Condylobasal length

145.3

149.8

154.3

160.0

156.7

154.5

152.4

160.2

95.9

2. Length of rostrum

90.7

93.5

88.4

104.4

99.3

96.8

97.0

108.4

59.0

3. Length of premaxillary (L)

107.0

106.8

105.2

116.8

113.9

109.8

109.7

119.3

64.4

4. Length of premaxillary (R)

107.0

106.9

103.9

116.2

113.1

109.9

109.5

119.2

64.0

5. Length of maxillary (L)

101.3

100.7

111.3

103.5

104.3

113.2

63.4

98.4

112.3

108.3

103.4

105.5

114.5

63.0

11.6

10.1

10.6

9.3

9.6

8.7

5.2

9.0

9.5

9.0

9.2

8.2

7.7

6.2

106.3

103.2

95.6

97.8

107.5

57.2

Specimen number

6. Length of maxillary (R)
7. Tip of premaxillary to tip of maxillary (L)

8.3

8. Tip of premaxillary to tip of maxillary (R)

4.49

9. Tip of premaxillary to nares, anterior

94.2

95.2

91.3

10. Tip of premaxillary to vertex

113.0

113.0

110.5

122.0

119.3

114.0

117.1

125.0

70.9

11. Tip of premaxillary to palatine, anterior (L)

87.2

94.3

90.6

100.9

99.8

93.4

93.0

98.6

55.3

12. Tip of premaxillary to palatine, anterior (R)

88.7

92.8

92.0

101.3

99.4

93.8

93.0

99.4

55.0

13. Tip of premaxillary to palatine, posterior (L)

120.6

125.4

127.2

135.7

133.0

129.4

127.2

134.6

76.0

14. Tip of premaxillary to palatine, posterior (R) 121.1

125.0

128.0

135.4

133.1

129.6

126.9

136.0

76.0

134.9

142.0

140.6

137.3

135.1

143.2

82.0

140.5

138.3

15. Tip of premaxillary to pterygoid process (L)

128.1

16. Tip of premaxillary to pterygoid process (R) 128.8

135.0

140.0

81.6

17. Tip of premaxilla to posterior edge ofoccipital bone (L)

154.0

157.1

136.0
167.6

166.4

162.7

171.9

98.4

18. Tip of premaxilla to posterior edge ofoccipital bone (R)

155.7

157.6

166.8

166.0

161.4

172.8

98.0

19. Tip of premaxilla to posterior edge of
temporal bone (L)

150.0

153.4

163.7

162.3

159.0

167.0

96.2

20. Tip of premaxilla to posterior edge of
temporal bone (R)

151.5

153.6

162.4

162.3

158.0

167.9

95.4

21. Breadth of maxillary, posterior edge

18.7

15.9

15.5

19.4

14.7

22.0

17.0

7.2

22. Breadth of premaxillary, posterior edge

5.7

2.8

3.2

4.3

3.8

2.3

2.9

3.0

2.1

23. Tip of premaxillary to anterior end ofvomer, median

23.9

19.3

20.3

34.7

27.7

23.3

31.4

33.3

15.8

24. Length of vomer

108.5

116.3

111.8

114.9

108.6

112.5

69.5

25. Breadth of rostrum at base

50.7

51.1

47.8

54.6

48.6

49.6

50.1

55.0

30.5

26. Breadth of premaxillary at base

17.2

16.7

16.7

16.7

14.8

16.6

17.2

12.8

7.3

27. Breadth of rostrum at middle

29.0

28.7

29.4

29.2

28.3

24.5

33.5

32.3

18.4

28. Breadth of premaxillary at middle

12.3

12.3

15.7

12.5

12.4

29. Greatest breadth of premaxillary

20.9

21.3

21.1

21.7

20.2

20.2

22.0

21.6

13.0

30. Breadth of cranium, maxillaries

75.2

71.8

73.9

79.4

72.5

71.6

77.7

80.9

44.0

31. Breadth of cranium, anterior edge ofzygomatic process

87.3

83.2

85.9

89.6

83.8

80.7

89.0

50.5

32. Breadth of cranium, middle of orbital
foramen

77.6

75.3

77.8

80.9

76.7

74.0

82.5

44.5

14.9

80.4

8.7

33. Breadth of occipital bone

68.8

63.7

66.7

62.7

67.3

63.1

66.7

70.0

39.2

34. Breadth of cranium, middle of zygomatic
process

87.4

83.4

84.7

89.3

84.7

82.8

86.6

87.9

49.5

35. Length from upper ridge of foramen
magnum to superior part of occipital
bone

41.3

37.8

43.0

41.6

39.8

40.5

39.2

42.1

26.0

36. Greatest breadth of palatine

24.7

20.7

23.6

24.8

24.0

22.4

23.3

24.4

14.0

37. Length of palatine (L)

37.4

34.4

39.0

37.0

36.8

39.1

36.8

38.6

21.7

38. Length of palatine (R)

36.6

35.0

37.5

36.2

37.2

37.7

35.9

38.5

22.6

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

223

NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Table 3.

Continued.
Specimen number

94NP
011

94NP
009

94NP
012

97NP
068

97NP
070

05NPCK 08NPCK 10NPCK 10NPCK
M001
M030
M047
M054

39. Breadth of palatine, posterior

28.7

27.6

28.9

25.7

26.9

30.9

40. Breadth across hamular processes ofpterygoid

13.0

14.3

12.9

41. Length of orbit (L)

18.0

16.0

17.4

17.7

19.5

17.1

42. Length of orbit (R)

18.0

16.0

17.6

17.5

19.0

17.9

16.5

43. Height of cranium

49.8

44.4

48.5

45.9

44. Length of nasals

13.8

12.8

14.3

11.4

11.8

13.2

45. Breadth of nasal, posterior

3.5

1.3

2.5

2.4

2.0

1.4

46. Breadth of nasal at middle

7.1

5.4

6.0

7.8

5.9

47. Minimum breadth of parietal bones

19.8

19.3

17.2

21.6

17.7

48. Height of foramen magnum

7.3

7.1

9.7

7.7

49. Breadth of foramen magnum

7.6

7.3

8.0

7.0

50. Breadth across occipital condyles

18.3

18.3

18.5

17.7

16.7

51. Breadth of occipital condyle (L)

7.1

6.9

7.6

7.0

52. Breadth of occipital condyle (R)

6.7

7.1

7.5

7.2

53. Height of occipital condyle (L)

10.3

10.7

11.0

54. Height of occipital condyle (R)

10.3

10.8

55. Length of tympanic bullae (L)

8.7

9.1

56. Minimum breadth of tympanic bullae (L)

5.3

57. Greatest breadth of tympanic bullae (L)58. Thickness of tympanic bullae at middle (L)

32.7

16.6

17.9

13.4

17.9

13.4

13.0

14.5

7.7

1.8

2.1

1.0

5.9

8.7

6.5

3.8

15.2

24.2

19.5

10.4

6.7

6.4

7.2

5.5

7.0

8.0

7.4

6.9

17.9

20.1

18.0

13.7

6.3

7.9

8.1

7.7

5.2

6.7

7.6

7.8

7.6

5.5

10.9

9.5

10.4

10.9

11.2

8.7

10.9

10.7

9.7

10.7

10.7

10.8

9.0

9.3

9.2

8.8

8.9

9.1

9.2

5.8

5.7

5.6

5.8

5.7

6.5

6.9

6.2

6.7

6.9

7.0

7.1

4.9

5.0

4.8

4.8

59. Length of mandible, straight (L)

148.0

152.5

148.8

160.0

159.4

154.5

155.0

161.5

96.0

60. Length of mandible, straight (R)

142.0

145.8

149.0

151.8

153.2

152.0

148.7

155.0

92.6

61. Length of mandible, curved (L)

142.2

146.0

155.4

152.4

152.8

151.5

149.8

154.0

92.2

62. Length of mandible, curved (R)

149.0

152.6

153.2

160.4

158.8

156.0

154.6

162.5

95.6

63. Breadth of mandible at middle (L)

6.2

6.3

6.3

7.0

6.2

6.3

6.4

7.1

4.2

64. Breadth of mandible at middle (R)

6.1

6.1

6.9

7.0

6.3

6.3

6.6

7.2

4.1

65. Height of mandible at middle (L)

11.4

10.3

10.8

11.2

10.2

11.4

11.3

11.7

6.4

10.5

28.5

66. Height of mandible at middle (R)

11.7

10.3

10.3

11.2

10.3

11.5

11.5

11.8

6.5

67. Height of mandible at coronoid process (L)

20.7

19.0

20.2

21.0

21.0

20.2

22.0

20.4

13.4

68. Height of mandible at coronoid process (R)

20.1

18.6

20.6

20.7

21.2

20.9

22.1

20.1

13.3

69. Height of mandible at coronoid (L)

14.6

15.3

15.4

14.4

14.6

13.3

15.7

14.7

8.9

70. Height of mandible at coronoid (R)

14.2

15.5

15.6

14.7

14.8

13.7

15.5

14.0

9.3

71. Breadth of mandible at coronoid (L)

11.3

10.6

11.5

10.3

9.8

10.3

10.3

10.4

6.8

72. Breadth of mandible at coronoid (R)

11.3

10.7

11.2

10.0

10.2

10.8

10.3

10.4

6.8

* ICR: Institute of Cetacean Research, HM: The Hagi Museum, AMP: Ashoro Museum of Paleontology

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SKELETAL MEASUREMENTS OF LARGE CETACEANS

Table 4. Measurements on cranium and mandible with some biological information on common minke, sei
and Bryde’s whale from the North Paciﬁc.
Scientiﬁc name

B. a. scammoni

Locality

North PaciﬁcB. borealis B. edeni
North PaciﬁcBody length (m)

8.09

7.60

7.75

7.31

7.30

7.11

13.37

Sex
Current aﬃliation *

F

F

F

F

F

F

M

F

ICR

ICR

ICR

ICR

ICR

ICR

MBIK

MBIK

94NP
021

95NP
048

97NP
078

99NP
063

99NP
073

99NP
098

03NP
SE045

00NP
B006

Specimen number

12.41

1. Condylobasal length

167.3

156.7

166.8

161.4

161.5

151.9

306.5

297.6

2. Length of rostrum

101.4

105.7

107.5

103.0

102.8

95.8

203.9

195.8

112.1

233.8

118.7

113.0

3. Length of premaxillary (L)

119.5

119.2

123.1

117.8

4. Length of premaxillary (R)

119.7

119.8

122.3

118.7

5. Length of maxillary (L)

115.2

112.6

6. Length of maxillary (R)

115.0

112.6

117.2

110.5

113.3

106.3

226.3

225.2

111.6

112.0

106.5

224.3

225.0

9.3

17.3

8.2

9.3

16.7

7. Tip of premaxillary to tip of maxillary (L)

7.9

10.2

10.4

8. Tip of premaxillary to tip of maxillary (R)

8.1

10.6

10.2

9.0
104.6

98.8

213.5

212.2

123.8

123.8

117.3

238.3

235.3

92.7

213.1

207.8

100.8

92.1

211.0

207.6

126.9

267.7

256.4

135.8

127.7

266.2

257.4

134.0

281.5

275.0

144.5

134.7

279.9

274.9

27.8

24.0

9. Tip of premaxillary to nares, anterior

107.6

104.4

111.6

10. Tip of premaxillary to vertex

123.2

125.3

129.8

11. Tip of premaxillary to palatine, anterior (L)

104.0

98.4

103.8

99.8

12. Tip of premaxillary to palatine, anterior (R)

104.7

98.0

104.9

101.4

13. Tip of premaxillary to palatine, posterior (L)

142.4

135.3

139.0

136.3

14. Tip of premaxillary to palatine, posterior (R)

143.3

135.4

139.3

137.3

15. Tip of premaxillary to pterygoid process (L)

150.6

143.3

146.6

143.8

16. Tip of premaxillary to pterygoid process (R)

150.7

143.6

147.1

144.3

17. Tip of premaxilla to posterior edge of occipital bone (L)

170.6

173.6

170.1

18. Tip of premaxilla to posterior edge of occipital bone (R)

170.9

172.6

170.7

19. Tip of premaxilla to posterior edge of temporal bone (L)

168.9

169.9

164.8

20. Tip of premaxilla to posterior edge of temporal bone (R)

169.0

168.3

165.2

163.2

159.0

14.3

16.4

21. Breadth of maxillary, posterior edge

17.6

13.3

18.7

15.2

22. Breadth of premaxillary, posterior edge

5.4

3.2

5.2

2.4

23. Tip of premaxillary to anterior end of vomer, median

24.6

24. Length of vomer

154.3
167.2

154.3
158.6

3.1

24.6

27.6

25.8

30.0

29.4

22.8

33.4

119.7

123.8

119.0

118.2

108.1

265.3

241.3

25. Breadth of rostrum at base

53.3

60.3

53.1

53.4

50.3

48.3

92.2

94.2

26. Breadth of premaxillary at base

22.3

14.5

21.6

17.6

15.3

17.2

27.9

22.1

27. Breadth of rostrum at middle

32.2

34.7

32.1

32.7

29.2

26.7

51.9

55.8

28. Breadth of premaxillary at middle

13.8

14.8

14.9

15.0

12.3

10.7

28.4

17.6

29. Greatest breadth of premaxillary

25.8

24.6

25.3

22.7

21.3

20.3

34.5

24.0

30. Breadth of cranium, maxillaries

80.1

85.4

77.7

79.4

75.8

73.7

130.0

128.8

31. Breadth of cranium, anterior edge of zygomatic
process

92.8

96.5

90.5

87.7

83.4

83.0

148.9

136.6

32. Breadth of cranium, middle of orbital foramen

85.9

89.3

81.4

80.8

76.0

74.4

134.4

131.2

33. Breadth of occipital bone

65.5

72.4

67.3

68.6

61.7

61.8

105.6

100.3

83.3

81.4

154.1

142.6

36.3

78.4

67.5

34. Breadth of cranium, middle of zygomatic process

92.4

94.6

91.8

86.5

35. Length from upper ridge of foramen magnum to superior part of occipital bone

44.6

39.3

42.9

39.2

36. Greatest breadth of palatine

28.0

27.4

26.8

23.8

37. Length of palatine (L)

41.1

40.2

37.8

38.8

38. Length of palatine (R)

41.6

39.7

36.7

38.4

39. Breadth of palatine, posterior

30.2

29.4

29.5

28.4

22.6
36.8

21.8

31.7

37.4

37.3

62.5

52.5

38.2

63.3

53.0

25.8

41.9

41.4

40. Breadth across hamular processes of pterygoid

13.4

14.3

14.3

13.1

14.8

13.8

26.3

23.0

41. Length of orbit (L)

17.9

16.0

17.5

17.5

17.0

16.0

23.9

23.8

42. Length of orbit (R)

18.4

16.5

17.5

17.5

17.0

16.0

24.8

23.0

54.4

52.2

51.4

48.5

47.8

43. Height of cranium
44. Length of nasals

13.7

16.0

13.9

13.1

14.7

13.8

22.4

45. Breadth of nasal, posterior

3.9

1.3

1.3

1.5

1.8

0.8

2.6

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NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Table 4.

Continued.
Specimen number

94NP
021

95NP
048

97NP
078

99NP
063

99NP
073

99NP
098

03NP
SE045

00NP
B006

46. Breadth of nasal at middle

8.3

5.7

8.1

5.5

5.3

6.0

10.6

47. Minimum breadth of parietal bones

21.5

16.4

21.5

17.2

16.5

19.4

29.7

48. Height of foramen magnum

12.0

6.6

6.3

6.6

6.7

7.0

7.5

6.5

49. Breadth of foramen magnum

10.0

6.8

6.7

7.3

7.1

7.8

7.0

5.9
26.5

26.3

50. Breadth across occipital condyles

19.6

16.6

18.3

17.5

16.2

17.0

28.0

51. Breadth of occipital condyle (L)

7.7

6.8

7.0

7.1

7.3

6.4

13.6

11.7

52. Breadth of occipital condyle (R)

7.7

6.7

7.0

7.1

7.3

6.4

13.2

11.1

53. Height of occipital condyle (L)

11.3

10.5

10.9

10.7

10.7

9.8

16.7

18.1

54. Height of occipital condyle (R)

11.2

10.4

10.8

10.8

10.7

9.9

17.0

17.9

55. Length of tympanic bullae (L)

9.3

12.1

56. Minimum breadth of tympanic bullae (L)57. Greatest breadth of tympanic bullae (L)

7.3

58. Thickness of tympanic bullae at middle (L)

9.0

9.3

9.3

12.1

5.8

5.2

5.8

7.1

7.0

6.8

7.0

9.0

4.7

5.3

5.2

5.8

7.9

59. Length of mandible, straight (L)

164.6

168.5

168.0

163.5

160.4

155.0

302.0

287.5

60. Length of mandible, straight (R)

164.0

161.6

159.0

158.0

153.0

147.5

292.3

286.9

61. Length of mandible, curved (L)

170.4

163.0

159.5

158.0

154.5

148.0

293.3

305.5

62. Length of mandible, curved (R)

170.0

167.5

167.8

164.5

159.5

154.0

301.0

306.5

63. Breadth of mandible at middle (L)

7.1

7.1

6.7

7.1

6.3

6.2

12.3

13.6

64. Breadth of mandible at middle (R)

7.2

7.1

6.7

7.0

6.4

6.3

12.2

14.8

65. Height of mandible at middle (L)

12.5

13.5

11.1

11.7

10.3

10.0

23.3

21.0

66. Height of mandible at middle (R)

12.6

13.7

11.2

11.6

10.7

10.2

23.1

19.8

67. Height of mandible at coronoid process (L)

21.2

23.3

20.2

21.4

20.0

20.5

38.2

34.6

68. Height of mandible at coronoid process (R)

21.2

23.3

20.3

21.8

20.6

20.1

38.6

35.4

69. Height of mandible at coronoid (L)

15.0

15.4

16.5

16.0

16.0

15.8

27.4

25.0

70. Height of mandible at coronoid (R)

16.1

17.4

16.1

15.3

16.3

15.4

27.3

24.7

71. Breadth of mandible at coronoid (L)

13.6

12.0

11.9

10.2

10.7

10.3

22.5

18.4

72. Breadth of mandible at coronoid (R)

12.0

11.9

11.6

10.0

10.6

10.3

22.1

18.4

* ICR: Institute of Cetacean Research, KCM: Kushiro City Museum, MBIK: Marine Biodiversity Institute of Korea

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SKELETAL MEASUREMENTS OF LARGE CETACEANS

Table 5.

Measurements on cranium and mandible with some biological information on gray whales.
Scientiﬁc nameEschrichtius robustus

Toyokoro,
Kohzu,
Miyazaki beach,
Obihiro,Kanagawa pref. Miyazaki pref.
Hokkaido
Sex
F
F
F
M
UNK
Body length (m) 12.79
7.75
9.50
8.00
Est. 7.7
Current aﬃliation* TUMSAT Ishinomaki city AMP
KPM
NZM
ID M804A
M804B
AMP-R9 KPM-NF1001969
NZM-159
Locality

1. Condylo-basal length
2. Length of rostrum (median)
3. Length of premaxillary (L)4. Length of premaxillary (R)
5. Length of maxillary (L)6. Length of maxillary (R)
7. Tip of premaxillary to tip of maxillary (L)8. Tip of premaxillary to tip of maxillary (R)
9. Tip of premaxillary to nares, anterior
10. Tip of premaxillary to palatine, anterior (L)
11. Tip of premaxillary to palatine, anterior (R)
12. Tip of premaxillary to palatine, posterior (L)
13. Tip of premaxillary to palatine, posterior (R)
14. Tip of premaxillary to pterygoid process (L)
15. Tip of premaxillary to pterygoid process (R)
16. Length of vomer
17. Breath of rostrum at base
18. Breath of rostrum at middle
19. Breath of premaxillary at middle
20. Greatest width of premaxilla
21. Breadth of cranium, maxillaries
22. Breadth of cranium, anterior edge of zygomatic process
23. Breadth of cranium, middle of orbital foramen
24. Breadth of occipital bone
25. Length from upper ridge of foramen magnum to superior partof occipital bone
26. Greatest breadth of palatine
27. Length of palatine (L)28. Length of palatine (R)29. Length of orbit (L)30. Length of orbit (R)
31. Length of nasals, curved
32. Breadth of nasal at middle
33. Breadth of nasal, anterior
34. Minimum breadth of parietal bones
40. Height of foramen magnum
41. Breadth of foramen magnum
42. Breadth across occipital condyles
43. Height of occipital condyle (L)44. Height of occipital condyle (R)45. Length of tympanic bullae (L)46. Minimum breadth of tympanic bullae (L)47. Greatest breadth of tympanic bullae (L)48. Length of mandible, straight (L)49. Length of mandible, straight (R)50. Length of mandible, curved (L)51. Length of mandible, curved (R)52. Breadth of mandible at middle (L)53. Breadth of mandible at middle (R)54. Height of mandible at middle (L)55. Height of mandible at middle (R)56. Height of mandible at coronoid (L)57. Height of mandible at coronoid (R)58. Breadth of mandible at coronoid (L)59. Breadth of mandible at coronoid (R)Enoshima, Onagawa,Miyagi pref.

259.5
181.9
213.4
212.4
190.0
192.8
11.7
10.1
179.4
180.5
182.3
219.3
220.4
231.2
230.2
177.0
61.5
39.7
15.6
34.8
87.6
120.5
96.8
87.6
53.6

146.1
91.1
112.1
111.7
98.3
98.4
6.0
5.8
94.3
91.0
90.7
116.5
117.5
124.8
124.1
91.3
34.7
20.2
12.3
20.4
50.7
72.2
50.8
51.0
34.7

187.5
125.3
146.2
149.5
137.9
135.4
6.0
7.4
126.5
126.6
125.9
157.8
158.3
166.2
166.0
128.5
42.9
26.2
11.6
27.3
64.1
83.4
67.8
63.7
43.7

145.8
89.3
105.0
103.8

36.0
43.9
41.8
17.5
17.1
34.0
18.2
18.9
24.7
10.4
10.4
30.5
20.9
21.0
10.5
7.8
9.8
249.8
246.6
253.6
254.0
10.4
12.3
33.8
33.3
44.3
45.4
20.9
21.3

22.6
28.9
28.4
13.5
13.0
16.8
7.7
10.8

26.1
36.6
36.6
15.6
15.7
24.4
11.2
16.8
22.6
12.0
9.9
25.2
17.8
17.4
9.5

25.1
27.2
27.0
13.8
14.6
20.3
11.6
17.1
8.1
6.9
19.5
14.9
14.5
9.1

13.8

8.3
173.2
173.7

8.3
138.4
139.5
138.5
139.8
5.3
5.1
15.3
15.3
21.5
22.1
10.4
10.8

9.2
156.5
158.9
157.2
155.6
6.9
6.8
17.6
16.7
26.2
26.5
11.8
12.0

7.7
9.0
20.5
15.4
15.6
9.0
8.4
133.5
131.5
136.0
136.0
5.8
5.6
13.8
14.1
23.2
23.4
10.1
10.2

7.3
6.9
18.5
18.0
31.4
30.8
14.7
15.3

4.2
2.5
88.8
89.1
90.9
117.4
117.8
123.0
122.6
35.0
22.8
13.1
22.4
52.0
71.2
55.7
50.6
34.7

80.3
65.3
57.9
38.8

33.9
14.7

9.9
8.9
23.3
17.8
18.2
10.8

*TUMSAT: Tokyo University of Marine Science and Technology, AMP: Ashoro Museum of Paleontology, KPM: Kanagawa Prefectural
Museum of Natural History, NZM: Miyazaki Prefectural Museum of Natural History

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NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Appendix 1. Photographs of the cranium and mandible of Antarctic minke whale (93/94–287).
a) dorsal view of cranium, b) ventral view of cranium, c) dorsal view of mandibles, d) caudal view of
cranium, e) lateral view of cranium and f) frontal view of cranium. Scale bar indicates one meter.

Appendix 2. Photographs of the cranium and mandible of dwarf minke whale (87/88–273). a) dorsal view of cranium, b) ventral view of cranium, c) dorsal view of mandibles, d) caudal view of cranium, e) lateral view of cranium and f) frontal view of cranium. Scale bar indicates one meter.

228

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

SKELETAL MEASUREMENTS OF LARGE CETACEANS

Appendix 3. Photographs of the cranium and mandible of common minke whale from the North
Paciﬁc (05NPCK-M001). a) dorsal view of cranium, b) ventral view of cranium, c) dorsal view ofmandibles, d) caudal view of cranium, e) lateral view of cranium and f) frontal view of cranium. Scalebar indicates one meter.

Appendix 4. Photographs of the cranium and mandible of sei whale from the North Paciﬁc (03NPSE045). a) dorsal view of cranium, b) ventral view of cranium, c) dorsal view of mandibles, d) caudal
view of cranium, e) lateral view of cranium and f) frontal view of cranium. Scale bar indicates one
meter.

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229

NAKAMURA, ZENITANI, BANDO, FUJISE, YAMAMOTO, NISHIMURA, HIROSE, KIM AND KATO

Appendix 5. Photographs of the cranium and mandible of Bryde’s whale from the North Paciﬁc(00NP-B006). a) dorsal view of cranium, b) ventral view of cranium, c) dorsal view of mandibles, d)caudal view of cranium, e) lateral view of cranium and f) frontal view of cranium. Scale bar indicates
one meter.

Appendix 6. Photographs of the cranium and mandible of gray whale (M804A). a) dorsal view of
cranium, b) ventral view of cranium, c) dorsal view of mandibles, d) caudal view of cranium, e) lateralview of cranium and f) frontal view of cranium. Scale bar indicates one meter.

230

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 215–230

J-STAGE Advance published date: March 3, 2021

FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALEFETAL DEVELOPMENT IN TAIL FLUKES OF
THE ANTARCTIC MINKE WHALE
Yujin KIM1*, Futaba NISHIMURA1, Takeharu BANDO2, Yoshihiro FUJISE2,Gen NAKAMURA1, Hiroto MURASE1 and Hidehiro KATO1, 2
1

Laboratory of Cetacean Biology, Tokyo University of Marine Science and Technology,
4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Corresponding author: 0101leonxd@gmail.com

Abstract
Tail ﬂukes of the Antarctic minke whale fetuses were studied to expand the available knowledge on fetal development, which is relatively understudied, as previous studies are qualitativein nature. Seven measurement points on the tail ﬂukes of 122 fetuses (after conception 12.9
to 259.5 days) were recorded. We quantitatively deﬁned the developmental stages based on
the measurements. Tail ﬂukes formed after an estimated fetal age of 57.8 days (9.4 cm) andretained almost the same shape as postnatal at 124.6 days (47.3 cm). The results also revealed
that the growth rates diﬀered at each measurement point and each developmental stage.
Key words:

Antarctic minke whale, Balaenopteridae, embryology, fetus, ﬂuke, ontogeny.

Several descriptive studies on the morphological changes in tail ﬂukes (hereafter, ﬂukes) during
intrauterine development were conducted on mysticetes (Ogawa, 1953; Ohsumi, 1960; Roston etal., 2013) and odontocetes (Ogawa, 1953; Nishiwaki et al., 1963; Amano and Miyazaki, 1993; Štěrba
et al., 2000; Thewissen, 2018). However, quantitative studies—measurements and statistical analysis—on the developmental changes of ﬂukes which is one of the most attractive and drastic changes
are expected during the intrauterine period, are limited as obtaining a suﬃcient number of fetal samples for such an analysis is diﬃcult.
This paper provides such quantitative information as above on the development of fetal ﬂukes incetaceans using the Antarctic minke whales (Balaenoptera bonaerensis) and measurements obtained
from the New Scientiﬁc Whale Research Program in the Antarctic Ocean (NEWREP-A) operation in
2017/18 under the special permit issued by Government of Japan in accordance with the International
Convention for Regulation of Whaling (ICRW) (Bando et al., 2018). Samples were collected from the
Paciﬁc sector of the Antarctic area bounded by 170°W, 120°W, 60°S, and sea ice edge (or coastline),
which corresponds to Area VI as deﬁned by the International Whaling Commission (IWC).
NEWREP-A commenced in the austral summer of 2017/18 and the seasons after with the ﬁrst author, Kim Y. as well as Bando T. and Nishimura F., on board the research base R/V Nisshin Maru inthat year (8,030 GT). Through the sampling exercises, 122 fetuses from 122 pregnant females were
examined by Kim alongside Bando and Nishimura.
Measurements, including the body length and ﬂuke morphometrics with ﬁve measurement points,
namely, total span (TS), maximum span (MS), depth of ﬂukes (DF), anterior length (AL), and posterior
length (PL) as deﬁned in Fig. 1, derived from Ohsumi (1960) for ﬁn whales (B. physalus) and Amanoand Miyazaki (1993) for Dall’s porpoises (Phocoenoides dalli), were made during the ﬁeld survey. TS
and MS were treated as the same for fetuses with less than 47.3 cm in body length because the fetal
ﬂukes have indistinguishable tips during the initial developmental stages as their skin lobes are rounded. The body length was measured parallel to the body axis, from the tip of the upper jaw to the notchof the ﬂukes to the nearest 0.1 cm. Body lengths of small fetuses with bent heads and tails were meaCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 231–238

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Fig. 1. Measurement points of ﬂukes from the Antarctic minke whale fetuses: total span (TS), from left tip toright tip; maximum span (MS), from left ridge to right ridge; depth of ﬂukes (DF), from anterior insertion, themost anterior point of skin lobes which was visually determined by the ﬁrst author, to notch; anterior length(AL), from anterior insertion to tip; posterior length (PL), from notch to tip; distance to notch (DN), from theleft anterior insertion and right anterior insertion lines to the notch; and distance to total span (DT), from left
anterior insertion and right anterior insertion lines to TS.

Fig. 2. Developmental stages of the ﬂukes as the Antarctic minke whale fetuses develop: Stage (0), tail shape;
Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

sured along the curved body axis. These measurement points were measured to three decimal places
along a straight line from point to point using 30 or 40 cm vernier calipers. Two additional measurement points, namely, distance to notch (DN) and distance to total span (DT), were measured. Because
the ﬂukes’ tips are curved ventrally and both points could not be measured accurately in the ﬁeld, bothmeasurement points were measured to three decimal places using digital photographs of ﬂukes in thelaboratory using the ImageJ software developed by Schneider et al. (2012). Fetal age (number of days
after conception) was estimated from the body length of the Antarctic minke whale using methods
devised by Kato and Miyashita (1991) and seconded by Bando (2017) (see Appendix for the details).
The developmental stages of the fetal ﬂukes were categorized based on Ohsumi (1960) and wereconventionally deﬁned as follows (Fig. 2): Stage (0), tail shape, with a completely tail-like shape withno skin lobes on both sides; Stage (1), diamond shape, when skin lobes form on both sides and ﬂukes
have a diamond-like shape (DT is less than or equal to half of DN); Stage (2), triangle shape, when
ﬂukes become triangular in shape (DT is more than half of DN); and Stage (3), boomerang shape,
when both of the ﬂukes’ tips are pointed and the ﬂukes take a boomerang-like shape (DT is more than
DN). The typical shapes of the Antarctic minke whale ﬂukes during their developmental stages [(0)–(3)] are exempliﬁed as in Fig. 3. We also incorporated the allometric equation (Huxley, 1950). Growth
pattern analyses were evaluated using t-test. Mean values of the ratios of each measurement point to232

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FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALE

Fig. 3. Photographs of the ﬂukes of the Antarctic minke whale fetuses at each developmental stage. Stage (0),tail shape (4.3 cm, 26.4 days, sex unknown); Stage (1), diamond shape (17.1 cm, 94.4 days, male); Stage (2),triangle shape (34.5 cm, 112.2 days, female); and Stage (3), boomerang shape (53.1 cm, 130.1 days, female).
Black scale bar indicates 1.0 cm, respectively.

the body length at each developmental stage were evaluated using Mann–Whitney U test. Signiﬁcantlevels of both statistical tests were set at 0.05.
The MS/DF and AL/PL ratios indicate the ﬂukes’ aspect and diagonal ratios, respectively. These ratios increased as fetuses develop with the following results (Fig. 4): Stage (1), the MS/DF and AL/PL
ratios increased from 1.0 to 1.4 and from 0.4 to 0.9, respectively; Stage (2), MS/DF increased from
1.7 to 2.9, and AL/PL increased from 0.8 to 1.3; and Stage (3), MS/DF leveled and increased from 2.2
to 3.2, and AL/PL increased from 1.2 to 1.7. At the beginning of Stage (1), MS and DF were almost
the same. However, MS became larger than DF as the fetal ﬂukes developed and elongated along thetransverse axis direction. Meanwhile, at this stage, AL was less than half of PL. This changed late inStage (2) when AL became larger than PL. This means that the anterior edge of ﬂukes grows fasterthan their posterior part.
The result of this study showed that fetal age which corresponded to the developmental stages were
12.9–41.8 days in Stage (0), 57.8–96.0 days in Stage (1), 99.0–118.0 days in Stage (2), and 124.6–
259.5 days in Stage (3) (Table 1). The ﬂukes started developing skin lobes 57.8 days after conception.
The growth patterns of each measurement point to body length are shown in Table 2. In Stage (1),four measurement points showed positive growth patterns relative to the body length. These were TS,
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Fig. 4. The relationship between two ratios of fetal ﬂukes (y axis) and estimated fetal age (x axis) at developmental stages of the Antarctic minke whale. The aspect ratio of the ﬂukes, MS/DF (a), and the diagonal ratioof the outer edges, AL/PL (b). The dotted lines indicate the starting point of each developmental stage of fetal
ﬂukes, from the left to the right: (0), (1), (2), and (3). Stage (0), tail shape; Stage (1), diamond shape; Stage(2), triangle shape; and Stage (3), boomerang shape.
Table 1. The body length and estimated fetal age of the Antarctic minke whale at each developmental stage offetal ﬂukes.
Developmental
stage

N

(0)
(1)
(2)
(3)

3
9
14
96

Body length (cm)

Estimated fetal age (days)

Range

Mean (SD)

Range

Mean (SD)

2.1–6.8
9.4–18.6
21.5–40.5
47.3–203.0

4.4 (2.4)
14.5 (3.0)
33.1 (5.8)
105.1 (35.3)

12.9–41.8
57.8–96.0
99.0–118.0
124.6–259.5

27.0 (14.5)
84.7 (13.3)
110.8 (5.8)
176.6 (30.8)

Stage (0), tail shape; Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

MS, AL, and PL (P<0.01). Isometric growth patterns were found in the other three points—DF, DN,
and DT (P>0.05). Positive growth patterns were observed in TS, MS, AL, PL, and DT in Stage (2)(P<0.05), while DF and DN showed isometric growth patterns to body length (P>0.05). In Stage(3), AL, PL, and DT showed positive growth patterns (P<0.01), and isometric growth patterns were
produced at MS, DF, and DN (P>0.05). Negative growth pattern to body length were observed at
TS (P<0.05). In all developmental stages, positive patterns were observed at AL and PL, while DF
and DN showed isometric patterns. As the ﬂukes developed from Stage (2) to (3), the growth patternsof TS and MS changed. In Stage (2), the growth patterns to body length of both measurement points
were positive, but in Stage (3), those two measurement points were diﬀerent. In Stage (3), a negative
growth pattern was observed at TS, and an isometric growth pattern was observed at MS. The growth
pattern of the DT changed from isometric in Stage (1) to positive in Stage (2).
The changes in ratios of each measurement point of the fetal ﬂukes relative to their body length ateach developmental stage are as follows (Table 3, Fig. 5). Each ratio was compared using the average values, and the standard deviations were shown with the average values. TS and MS ratios were
11.1±4.0% in Stage (1) and increased to 22.4±2.6% in Stage (2) (P<0.01). In Stage (3), while TS isconstant at 22.0±2.5% (P>0.05), MS increased to 24.3±1.9% (P<0.01). The DF ratio ranged from
9.7±0.6% to 10.8±1.0% for Stage (1) and (2) (P>0.05). In Stage (3), DF decreased to 9.2±0.5%(P<0.01). The AL and PL ratios increased with the developmental stages. AL increased from5.8±2.1% to 11.7±1.9% when the developmental stage became from Stage (1) to Stage (2) (P<0.01).

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Table 2. The growth patterns of fetal ﬂukes at developmental stages of the Antarctic minke whale.
Developmental
stage

Measurement
point

N

α1

ln β 1

Growthpattern2

r2

P-value

(1)

TS
MS
DF
AL
PL
DN
DT

7
7
4
6
6
7
7

2.605
2.605
0.883
2.341
1.423
0.787
0.937

0.001
0.001
0.149
0.002
0.028
0.178
0.049

Positive
Positive
Isometric
Positive
Positive
Isometric
Isometric

0.980
0.980
0.319
0.934
0.995
0.902
0.778

**
**
n.s.
**
**
n.s.
n.s.

(2)

TS
MS
DF
AL
PL
DN
DT

14
14
14
14
14
13
14

1.544
1.544
0.940
1.737
1.366
1.068
1.970

0.033
0.033
0.120
0.009
0.032
0.079
0.003

Positive
Positive
Isometric
Positive
Positive
Isometric
Positive

0.956
0.956
0.889
0.921
0.904
0.944
0.884

**
**
n.s.
**
*
n.s.
**

(3)

TS
MS
DF
AL
PL
DN
DT

79
92
96
92
91
65
65

0.921
1.034
0.982
1.176
1.095
0.990
1.316

0.313
0.208
0.100
0.076
0.080
0.102
0.036

Negative
Isometric
Isometric
Positive
Positive
Isometric
Positive

0.882
0.957
0.973
0.974
0.949
0.931
0.944

*
n.s.
n.s.
**
**
n.s.
**

α and ln β are the allometric coeﬃcient and constant, respectively. The asterisk indicates the signiﬁcance levels of each allometric coefﬁcient from a value of 1 (t-test: *, P<0.05; **, P<0.01, n.s., no signiﬁcant diﬀerence). Stage (0), tail shape; Stage (1), diamond shape;
Stage (2), triangle shape; and Stage (3), boomerang shape.
2
The allometric equation y=βx α was used to determine the growth curves and patterns in each developmental stage, where x is the bodylength (cm), y is the length of the measurement point (cm), α is the allometric coeﬃcient, and β is the allometric constant. The growth
patterns of each measurement point were classiﬁed into three based on the signiﬁcance (t-test) of the allometric coeﬃcients applied:
positive when the allometric coeﬃcient was signiﬁcantly larger than 1, isometric when the allometric coeﬃcient was not signiﬁcantly
diﬀerent from 1, and negative when the allometric coeﬃcient was signiﬁcantly smaller than 1. All statistical analyses were made using R version 3.5.1 (R Core Team, 2018) running on RStudio version 1.1.456 (RStudio Team, 2016). Since no signiﬁcant diﬀerences(ANCOVA, P>0.05) were observed in the growth patterns of all measurement points (results are not shown here) between males andfemales, they were not separated in our analysis.
1

In Stage (3), AL showed 17.2±1.5% (P<0.01). On the other hand, PL increased from 8.7±1.0% inStage (1) to 11.5±1.2% in Stage (2) and to 12.4±1.2% in Stage (3) (P<0.05). The DN ratio ranged
from 9.8±0.8% to 10.2±0.8% for all the developmental stages (P>0.05). The DT ratio increased
through all the stages and ranged 4.2±0.5% in Stage (1), 7.7±1.6% in Stage (2), and 15.3±2.1% inStage (3) (P<0.01). The ratios of each measurement point to body length varied depending on thedevelopmental stage. Exceptionally, DN stayed within a certain range regardless of the developmental
stages. As the ﬂukes developed, the measurement points with increasing ratios were MS, AL, PL, andDT. The ratios of the other measurement points (TS and DF) changed with developmental stages.
Several authors have examined the fetal development of ﬂukes, including Štěrba et al. (2000) for
common dolphins (Delphinus delphis), pantropical spotted dolphins (Stenella attenuata), spinner dolphins (S. longirostris), and harbor porpoises (Phocoena phocoena), Nishiwaki et al. (1963) for sperm
whales (Physeter macrocephalus), and Ohsumi (1960) for ﬁn whales. This paper is the ﬁrst attempt toincorporate a quantitative measure of fetal growth into drawing the morphological development of fetal ﬂukes of the Antarctic minke whale.
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KIM, NISHIMURA, BANDO, FUJISE, NAKAMURA, MURASE AND KATO

Table 3. The ratios of fetal ﬂukes to body length of the Antarctic minke whale at the developmental stages.
Measurement
point

N

(1)

TS
MS
DF
AL
PL
DN
DT

Developmental stage

The ratios of fetal ﬂukes tobody length (%)

P-value

Range

Mean (SD)

(2)

7
7
4
6
6
7
7

5.3–15.5
5.3–15.5
9.5–11.8
3.1–8.6
7.1–9.7
9.2–11.7
3.5–4.7

11.1 (4.0)
11.1 (4.0)
10.8 (1.0)
5.8 (2.1)
8.7 (1.0)
10.2 (0.8)
4.2 (0.5)

**
**
n.s.
**
**
n.s.
**

(2)

TS
MS
DF
AL
PL
DN
DT

14
14
14
14
14
13
14

17.9–26.6
17.9–26.6
8.8–10.6
8.3–15.3
9.4–13.6
9.3–11.2
5.1–10.3

22.4 (2.6)
22.4 (2.6)
9.7 (0.6)
11.7 (1.9)
11.5 (1.2)
10.1 (0.5)
7.7 (1.6)

(3)

TS
MS
DF
AL
PL
DN
DT

79
92
96
92
91
65
65

16.7–28.0
20.4–30.1
8.1–10.9
13.3–20.7
9.9–15.8
7.5–12.0
10.5–20.2

22.0 (2.5)
24.3 (1.9)
9.2 (0.5)
17.2 (1.5)
12.4 (1.2)
9.8 (0.8)
15.3 (2.1)

(3)

n.s.
**
**
**
*
n.s.
**

The asterisk indicates the signiﬁcance levels of diﬀerence to the average value of each ratio between the consecutive developmental stages (Mann–Whitney U test: *, P<0.05; **, P<0.01, n.s., no signiﬁcant diﬀerence). Stage (0), tail shape; Stage (1), diamond shape; Stage(2), triangle shape; and Stage (3), boomerang shape.

Ohsumi (1960) showed the growth patterns of ﬁn whale fetal ﬂukes (DF and PL in our study) tobody length. Their DF changed from a negative growth pattern to a positive one as the fetuses developed. This positive growth pattern was observed at the PL. Nishiwaki et al. (1963) observed the ratios
to body length of three measurement points of sperm whale’s fetal ﬂukes, which correspond to theTS, DF, and PL in our study. They found that the TS and PL/body length ratios increased, while DF
decreased. The growth patterns and ratios of the fetal ﬂukes of the Antarctic minke whale indicated a
rapid growth along the transverse axis direction during the fetal development. The results suggest thatthe growth rates of cetacean fetal ﬂukes at these measurement points vary from species to species.
Štěrba et al. (2000) compared the fetal age development of ﬂukes of four dolphin species: thecommon dolphin, the pantropical spotted dolphin, the spinner dolphin, and the harbor porpoise. They
found that the ﬂukes from each species started developing 32–42 days after conception, while wefound that the Antarctic minke whale ﬂukes began to develop at fetal age of 57.8 days. These results
are evidence that the development of the Antarctic minke whale ﬂukes begins about 15 days later thanthat of the dolphins, which would be key for comparing relative ratio to total gestation period and themethodological diﬀerences between previous studies and this study, which we plan to do in future investigations.

236

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FETAL DEVELOPMENT IN TAIL FLUKES OF THE ANTARCTIC MINKE WHALE

Fig. 5. The relationship between ratios of fetal ﬂukes to body length (y axis) and estimated fetal age (x axis)of the Antarctic minke whale. TS (a), MS (b), DF (c), AL (d), PL (e), DN (f), DT (g). The dotted lines indicate
the starting points of each developmental stage of fetal ﬂukes, from the left to the right: (0), (1), (2), and (3).
Stage (0), tail shape; Stage (1), diamond shape; Stage (2), triangle shape; Stage (3), boomerang shape.

Acknowledgements

We are grateful to all the crew members, researchers, and relevant organizations involved in the 2017/18 NEWREP-A
that was conducted in a harsh environment to collect samples for this study. Yujin Kim’s work was partially supported by agrant from The Korean Scholarship Foundation (2018–2019) and the Monbukagaku-Sho Honors Scholarship for Privately
Financed International Students (2017 and 2019).

References
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Bando, T. 2017. Hokuseitaiheiyou niokeru nitarikujira Balaenoptera edeni brydei to iwashikujira B. borealis no keitai oyobi
seibutsugakutekitokuseichi no hikakukentou [Comparison of the morphological and biological characters of Bryde’s
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Tokyo University of Marine Science and Technology, Tokyo. 149 pp.
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H., Kominami, T., Eguchi, H., Mogoe, T. and and Tamura, T. 2018. Results of the third biological ﬁeld survey of NEWREP-A during the 2017/18 austral summer season. Paper SC/67B/SCSP/08 of the Scientiﬁc Committee of the International Whaling Commission. 17 pp. [Available from the secretariat of IWC]
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Soc. B. 137 (889): 465–469.
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Received: September 19, 2020
Accepted: December 4, 2020
Published online: March 3, 2021

Appendix
Formulas for estimating fetal age of the Antarctic minke whale
We used formula (1) based on Kato and Miyashita (1991) to estimate the fetal age (t, expressed indays) when the body length was 15 cm or more. The growth rate of the fetus changes with the formation of the placenta (Laws, 1961). The placenta of this species is formed when the body length is
15 cm (Kato and Miyashita, 1991). Bando (2017) studied Bryde’s (B. edeni brydei) and sei whales (B.
borealis) fetuses, and assumed that days after conception (i.e., fetal age) of fetuses with a body lengthof less than 15 cm were proportional to their body length. This study made a similar assumption. First,
we calculated the fetal age at 15 cm in body length using formula (1) and estimated it at 92.2 days.
Subsequently, we adapted t=aL to estimate the growth coeﬃcients (a), which we calculated as 6.147.
Formula (2) was used when the body length was less than 15 cm.

238

t = 1.622 L0.892 +74(1)

t = 6.147 L(2)

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 231–238

J-STAGE Advance published date: January 31, 2021

IMPROVED ESTIMATES OF LIFE-HISTORY PARAMETERS FOR BRYDE’S WHALESIMPROVED ESTIMATES OF SOME LIFE-HISTORYPARAMETERS OF THE PELAGIC SUBSPECIES OF
BRYDE’S WHALE IN THE
WESTERN NORTH PACIFIC
Takeharu BANDO
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
Corresponding author: bando@cetacean.jp

Abstract
Estimates of several life-history parameters of the pelagic subspecies of Bryde’s whale(Balaenoptera edeni brydei) in the western North Paciﬁc were made based on samples collected from the second phase of the Japanese Whale Research Program under Special Permit
in the Western North Paciﬁc (JARPNII) from 2000 to 2016. A total of 730 individuals were
sampled in the western North Paciﬁc, between the Japanese coast and 170°E and between
35°N and approximately 42°N. Age information was obtained from earplugs of 475 individuals (65.2%). The growth curves were estimated as Lt=12.65 (1−e−0.189 (t+5.250)) and Lt=13.30(1−e−0.170 (t+4.929)) for males and females, respectively. The mean age at sexual maturity wasestimated as 7.72 (SE=0.49) and 8.56 (SE=0.39) years, and the mean body length at sexual
maturity was estimated as 11.41 m (SE=0.25) and 11.75 m (SE=0 .23) for males and females,
respectively. The annual ovulation rate was estimated as 0.526/year. Increased readability of
earplug age in the JARPNII resulted in improved estimates of age-related life-history parameters for the western North Paciﬁc Bryde’s whale compared with those based on samples collected during the past commercial whaling period.
Key words:

life-history parameter, Bryde’s whale, earplugs, western North Paciﬁc.

Bryde’s whale is widely distributed throughout the world, especially in waters with temperaturesof 20°C or more (Kato and Perrin, 2017). Two types of Bryde’s whale are found around Japan, one
along the coast of the southwestern part of Japan and the other on pelagic waters in the Paciﬁc side ofJapan (Kishiro, 1996; Yoshida and Kato, 1999). Some authors (e.g., Wada et al., 2003) recognize these
two types as separate species, a smaller coastal species Balaenoptera edeni Anderson, 1879 (Eden’s
whale) and a larger pelagic species B. brydei Olsen, 1913 (Bryde’s whale). Other authors (e.g., Kershaw et al. 2013; Kato and Perrin, 2017) assign these species a subspeciﬁc status: B. edeni edeni andB. edeni brydei. This study focused on the larger, pelagic subspecies of Bryde’s whale (Fig. 1).
The second phase of the Japanese Whale Research Program under Special Permit in the Western
North Paciﬁc (JARPNII) started in 2000, under a permit issued by the Government of Japan. The pelagic subspecies of Bryde’s whale was selected as one of the target species for sampling. Biologicalinvestigations, such as body length measurements and sampling of reproductive organs and earplugs,
were conducted on whole animals in order to estimate life-history parameters. The JARPNII was completed in 2016, and a total of 730 Bryde’s whales (314 males and 416 females) were sampled during
the 17 year survey period.
Age data are important for assessment of stock and management of large whales. Age estimation
based on the number of growth layers accumulated in the earplugs is considered the most reliable tool
for age determination in baleen whales (Lockyer, 1984a; Maeda et al., 2016). During the JARPNII,
Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 239–245

239

BANDO

Fig. 1. Pelagic subspecies of Bryde’s whale in the western North Paciﬁc. Note the three distinct ridges in thehead, which are characteristic of this species.

Fig. 2. Research area of the second phase of the Japanese Whale Research Program under Special Permit in
the Western North Paciﬁc (JARPNII) and location of sightings of Bryde’s whales sampled during 2000–2016
surveys.

earplugs were collected carefully from each whale by experienced biologists.
Age-related life-history parameters are important for monitoring the status of stocks and can beused in various analyses, including population dynamics models (e.g., the statistical catch-at age model; Punt et al., 2014). Previous estimates of life-history parameters of Bryde’s whale were based on
samples collected during the commercial whaling period (Kato and Yoshioka, 1995; Ohsumi, 1977).
However, samples from commercial whaling are not representative of the stock, as whaling operations
targeted large individuals and a legal size limit was imposed in some operations. Therefore, somelife-history parameters estimated from these samples, such as age at sexual maturity are thought to bebiased (Kato, 1982; Kato and Yoshioka, 1995; Ohsumi, 1977). JARPNII collected samples randomly,
regardless of body length or age, resulting in less biased estimates (Bando et al., 2016).
This article summarizes the results of estimation of several life-history parameters in the pelagic
subspecies of Bryde’s whale in the western North Paciﬁc based on randomly collected samples, which

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should be more representative than those obtained in past commercial whaling.
Whales were sampled between the Japanese coast and 170°E, and between 35°N and approximately
42°N (Fig. 2). Two biological stocks of the pelagic subspecies of Bryde’s whale have been suggested
for the western North Paciﬁc, one between the Japanese coast and approximately 165°E and the othereast of 180°, with a transition area between 165°E and 180° (IWC, 2018). Analyses were conducted on
the assumption that all samples were from the western stock because it is diﬃcult to identify stocks
for each individual and the number of samples from east of 165°E was not large (Fig. 2) (IWC, 2018).
Body length was measured to the nearest 1 cm in a straight line from the tip of the snout to the notchof the ﬂukes using stainless steel measuring tapes. Sexual maturity in males was determined by examination of a histological sample from the testis. Males with seminiferous tubules over 100 µm diameterand spermatid or open lumen in the tubules were considered to be sexually mature (Nishiwaki et al.,1954; Lockyer, 1984b). Sexual maturity in females was determined by the presence or absence of corpora lutea and albicantia in the ovaries. If there was at least one corpus luteum or corpus albicans in
the ovaries, the female was considered to be sexually mature (Nishiwaki et al., 1954; Lockyer, 1984b).
Earplugs were collected from all sampled animals, following the method developed for baleen
whales (Omura, 1963; Maeda et al., 2016). The left and right earplugs were collected carefully and
immediately ﬁxed in 10% formalin. In the laboratory, the surface along the central axis of the earplug
was cut using a sharp blade, and was placed on a wet stone to expose the growth layers. The growthlayers were counted under water using a stereoscopic microscope. A growth layer group was deﬁned
as one pair of light and dark laminae in the core and was considered to indicate 1 year of age. All earplugs were read by the author.
To estimate the growth curve, the von Bertalanﬀy growth model was ﬁtted to body length and age
asLt = L∞ (1 − e− K (t − t0 ) )(1)

where Lt is the body length at age t, L∞ is the asymptotic length, K is the growth rate coeﬃcient and t0
is the theoretical time at zero length.
Age at sexual maturity (tm) was estimated by the following equation (Cooke, 1984):

Tm = g − 0.5 +var (tm ) =hh Ia 

a= ga  N 
M a Ia N ( N − 1)
a=g

2
a

a

(2)
(3)

where
Ma is the number of mature animals of age a,
Ia is the number of immature animals of age a,
Na is the total number of animals of age a,
g is the age of the youngest mature animal in the sample, andh is the age of the oldest immature animal in the sample.
Body length at sexual maturity (lm) was estimated by the following equation (Cooke, 1984;
Kato, 1992) (body length was rounded to 0.1 m):

Lm = j − 0.05 + 0.1
kk Ib b= jb

  N 
M b Ib N (N − 1)var (lm ) = 0.1

b= j

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 239–245

2
b

b

(4)
(5)

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BANDO

where
Mb is the number of mature animals of body length b,
Ib is the number of immature animals of body length b,
Nb is the total number of animals of body length b,j is the body length of the smallest mature animal in the sample, andk is the body length of the largest immature animal in the sample.
The annual ovulation rate was estimated by applying linear regression analysis between age and thetotal number of corpora (corpora lutea and corpora albicantia). The regression line was ﬁtted to ages
10 years and older because almost all animals were mature at the age of 10 years.
The readability of earplugs varied depending on the maturity status of the individual. The readability of earplugs of sexually immature individuals was 43.8% for males and 40.8% for females. The
readability of earplugs of sexually mature individuals was higher than that of immature individuals:
74.0% for males and 76.4% for females. The readability of all samples was 65.2% (Table 1). Although
the proportion of immature individuals with lower earplug readability was higher in JARPNII samples
than in commercial whaling samples from the 1970s (30.9% vs. 14.3%) (Ohsumi, 1977), the proportion of samples from which age could be determined increased drastically from commercial whaling
samples (17.4%; Ohsumi, 1977) to JARPNII samples.
The relationship between age and body length is shown in Fig. 3. For both sexes, the growth rate
was high at younger ages and stabilized after the age of 20 years. The following von Bertalanﬀygrowth curves were estimated:
Male :
Female :Lt = 12.65 (1 – e – 0.189 ( t+5.250 ) )Lt = 13.30 (1 – e –0.170 (t + 4.929 ) ) .

Table 1. Readability of earplugs of Bryde’s whales for determination of age according to sex and sexual
maturity status.

Fig. 3. Relationship between body length and age in Bryde’s whale. The solid lines show the von Bertalanﬀygrowth curves.

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IMPROVED ESTIMATES OF LIFE-HISTORY PARAMETERS FOR BRYDE’S WHALES

Fig. 4. Sexual maturity status by age and sex in Bryde’s whale. Numbers in the bars are the numbers of samples examined.

Fig. 5. Sexual maturity status by body length and sex in Bryde’s whale. Numbers in the bars are the numbersof samples examined. Body length values were rounded to 0.1 m.

Figs. 4 and 5 show sexual maturity status by age and body length. Males ﬁrst reached sexual maturity at the age of 6 years, and all males were sexually mature by the age of 11 years (Fig. 4). The mean
age at sexual maturity (tm) for males was estimated as 7.72 years (SE=0.49). Females ﬁrst reachedsexual maturity at the age of 7 years, and all females were sexually mature by the age of 11 years. Tm
was estimated as 8.56 years (SE=0.39).
Males ﬁrst reached sexual maturity at a body length of 10.4 m, and all males with a body length of
12.9 m or greater were sexually mature (Fig. 5). The mean body length at sexual maturity (lm) was estimated as 11.41 m (SE=0.25). Females ﬁrst reached sexual maturity at a body length of 11.2 m, and all femaleswith a body length of 12.5 m or greater were sexually mature. Lm was estimated as 11.75 m (SE=0.23).
The corpora lutea and corpora albicantia ﬁrst appeared at the age of 7 years and the number of corpora increased linearly after the age of 10 years (Fig. 6). The annual ovulation rate was estimated as 0.526.
The life-history parameters of the western North Paciﬁc Bryde’s whale have been estimated byseveral authors using commercial whaling samples. Ohsumi (1977) estimated the growth curves ofBryde’s whales based on commercial whaling samples from the western North Paciﬁc in the 1970s.
The results were preliminary because of the small numbers of younger individuals in the samples
due to the small numbers of young individuals in the catch and diﬃculty in collecting, preparing, andcounting the number of layers in the earplugs of young animals (Ohsumi, 1977).
Ohsumi (1977) reported the age at sexual maturity of Bryde’s whales collected by commercial whaling in the western North Paciﬁc as 10 years for males and 8 years for females. Although the estimatedCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 239–245

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BANDO

Fig. 6. Jitter plot showing the relationship between age and number of corpora lutea and corpora albicantia in
Bryde’s whale. The linear regression line was ﬁtted to ages 10 years and more.

values in the present study are similar to the estimates from commercial whaling, consideration should
be given to the possibility of bias arising from legal size limits and the selection of large animals duringcommercial whaling. Large whales were preferred and individuals of the same age but large bodylength, which has high probability of maturity, are caught among the younger whales during commercial
whaling, which leads to overestimation of the sexual maturity rate of younger individuals and underestimation of the age at sexual maturity. Further analysis including other parameters that are free from bias,
such as age at ﬁrst ovulation, is needed to determine whether any changes in the age at sexual maturity
have occurred between the period of commercial whaling and the period of the JARPNII program.
Kato and Yoshioka (1995) reported body length at sexual maturity of Bryde’s whales collected by
the commercial whaling in the coastal region of the western North Paciﬁc in the 1970s as 11.4 m and11.8 m for males and females. These results are comparable to the results of the present study. In Katoand Yoshioka’s study, testis weight was used as a criterion of male sexual maturity. The present study
used histological examination of the testis, which is more desirable than testis weight as a criterion ofmale sexual maturity (Lockyer, 1984b), and which would enhance the credibility of the estimated value.
The annual ovulation rate was estimated as 0.455 from the 1970s commercial whaling samples(Ohsumi, 1977), which was lower than the value estimated in this study (0.526). As in the case ofage at sexual maturity, there may be an underestimation bias in estimates from commercial whaling
samples. In commercial whaling, whales with the same age but large body length, which would growand reached sexual maturity faster and have more corpora lutea and albicantia, are caught among theyounger whales, which leads to underestimation of the annual ovulation rate.
In conclusion, in this study improved estimates of some life-history parameters are derived for the
pelagic subspecies of Bryde’s whale in the western North Paciﬁc from randomly collected samples ofanimals with a wide range of ages and body lengths. Further analysis, including examination of yearly
trends will contribute to understanding and management of this whale stock.
Acknowledgements

My sincere thanks are due to all researchers and crews that collected data and samples during the JARPNII surveys. I also
thank Dr. Tsutomu Tamura and colleagues of the Institute of Cetacean Research for useful suggestions and help in conducting laboratory work. Dr. Yoshihiro Fujise, director-general of the Institute of Cetacean Research, provided the original idea
for this analysis. Dr. Hidehiro Kato, Professor Emeritus of Tokyo University of Marine Science and Technology gave me theopportunity to conduct this study. Finally, I greatly appreciate the anonymous reviewers for their valuable suggestions.

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References
Bando, T., Yasunaga, G., Tamura, T., Matsuoka, K., Murase, H., Kishiro, T. and Miyashita, T. 2016. Methodology and survey
procedures under the JARPNII—oﬀshore component—during 2008 to 2014 with special emphasis on whale sampling
procedures. Paper SC/F16/JR4 presented to the JARPNII special permit expert panel review workshop, Tokyo, February 2016 (unpublished). 14 pp. [Available from the secretariat of IWC].
Cooke, J.C. 1984. The estimation of mean ages at sexual maturity from age sample. Paper SC/36/O22 presented to IWC Scientiﬁc Committee, 1984 (unpublished). 8 pp. [Available from the IWC Secretariat].
Government of Japan. 2000. Research plan for cetacean studies in the western North Paciﬁc under special permit (JARPNII)(Feasibility study plan for 2000 and 2001). Paper SC/52/O1 presented to the IWC Scientiﬁc Committee, 2000 (unpublished). 68 pp. [Available from the secretariat of IWC].
International Whaling Commission. 2018. Report of the Workshop on the Implementation Review of western North Paciﬁc
Bryde’s whales. J. Cetacean Res. Manage. (Suppl.) 19: 561–593.
Kato, H. 1982. Some biological parameters for the Antarctic minke whale. Rep. Int. Whal. Commn. 32: 935–945.
Kato, H. 1987. Density dependent changes in growth parameters of the southern minke whale. Sci. Rep. Whales Res. Inst. 38:
47–73.
Kato, H. 1992. Body length, reproduction and stock separation of minke whales oﬀ northern Japan. Rep. Int. Whal. Commn.
42: 443–453.
Kato, H. and Perrin, W.F. 2017. Bryde’s whales Balaenoptera edeni/brydei. pp. 158–163. In: B. Würsig, J.G.M. Thewissen
and K. Kovacs (eds.) Encyclopedia of marine mammals, Third Edition. Academic Press, San Diego. 1190 pp.
Kato, H. and Yoshioka, M. 1995. Biological parameters and morphology of Bryde’s whales in the western North Paciﬁc, withreference to stock identiﬁcation. Paper SC/47/NP11 presented to the IWC Scientiﬁc Committee, 19 pp. (unpublished).
19 pp. [Available from the secretariat of IWC].
Kershaw, F., Leslie, M.S., Collins, T., Mansur, R.M., Smith, B.D., Minton, G., Baldwin, R., LeDuc, R.G., Anderson, R.C.,
Brownell, R.L. and Rosenbaum, H.C. 2013. Population diﬀerentiation of 2 forms of Bryde’s whales in the Indian and
Paciﬁc Oceans. J. Hered. 104 (6): 755–764.
Kishiro, T. 1996. Movements of marked Bryde’s whales in the western North Paciﬁc. Rep. Int. Whal. Commn. 46: 421–428.
Lockyer, C. 1984a. Age determination by means of the earplug in baleen whales. Rep. Int. Whal. Commn. 34: 692–696.
Lockyer, C. 1984b. Review of baleen whale (Mysticeti) reproduction and implications for management. Rep. Int. Whal.
Commn. (Special Issue 6): 27–50.
Maeda, H., Bando, T., Kishiro, T., Kitakado, T. and Kato, H. 2016. Basic information of earplug as age character of common
minke whales in western North Paciﬁc. Paper SC/F16/JR53 presented to the JARPNII special permit expert panel review workshop, Tokyo, February 2016 (unpublished). 10 pp. [Available from the secretariat of IWC].
Nishiwaki, M., Hibiya, T. and Kimura, S. 1954. On the sexual maturity of the sei whales of the Bonin waters. Sci. Rep.
Whales Res. Inst. 8: 165–177.
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Received: October 31, 2019
Accepted: September 16, 2020
Published online: January 31, 2021

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J-STAGE Advance published date: September 30, 2021

MAEDA AND KATOSEASONAL CHANGES IN THE EARPLUGGERMINAL LAYERS OF NORTH PACIFIC COMMONMINKE WHALES
Hikari MAEDA1* and Hidehiro KATO2, 3
Fisheries Resources Institute, Japan Fisheries Research and Education Agency,
2–12–4 Fukuura, Kanazawa, Yokohama, Kanagawa 236–8648, Japan
2
Tokyo University of Marine Science and Technology, 4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
3
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Corresponding author: hikarim@aﬀrc.go.jp
1

Abstract
We investigated the annual accumulation rate of the most recently formed layer of earplugs,
the germinal layer (GL), of the North Paciﬁc common minke whales, which is important forage estimation. The pale GLs from Kushiro in September and October were found to be signiﬁcantly thicker than those from Ayukawa in April and May. The results suggest that the palelamina accumulated during an approximately six-month period from spring to autumn in theirfeeding season. This was consistent with the hypothesis that one pale and one dark lamina,
comprising one growth layer group, are formed annually in this species.
Key words:

earplug, common minke whale, age determination, germinal layer, accumulation
rate.

The earplugs of baleen whales were ﬁrst considered to show aging characteristics by Purves (1955).
The external auditory meatus lumen is ﬂattened dorso-ventrally, so that the dorsal and ventral epidermis walls are in apposition forming a “blind” section (Purves, 1955). Because of this, the earplug will
never fall out throughout a whale’s life. The earplug is composed of a “core” and an “outer covering”(Fig. 1). The core of the earplug (b in Fig. 2), where the growth layer group (dark lamina and palelamina) is formed, is composed of exfoliated and keratinized epidermis of a ﬁnger-sack-like tissue
called the glove ﬁnger (Fig. 1). It is surrounded by a layer of wax-like material from the external auditory canal membrane (outer covering, a in Fig. 2).
Currently, earplugs are used in age estimation for several species of baleen whales (Lockyer, 1984a;
Gabriele et al., 2010; Nielsen et al., 2012; Kitakado et al., 2013; Maeda et al., 2016). Many baleen
whales are known to migrate seasonally, breeding in low-latitude waters in winter and feeding in
high-latitude waters in summer. It is thought that this annual cycle is reﬂected in earplug growth layers, with a pale lamina forming during the summer feeding season and a dark lamina forming during
the winter breeding season (Fig. 2); therefore, one growth layer group represents one year (Roe, 1967;

Fig. 1. Diagram showing the anatomical position of the earplug in a typical baleen whale. After Purves (1955).

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Fig. 2. Bisected surface of an earplug of a common minke whale. a: (outside the dotted line), outer covering;b: (inside the dotted line), core with growth layers. Scale bar represents: 5 mm.

Lockyer, 1972, 1984b). Fat content tends to be lower in the dark lamina and higher in the pale lamina
according to histological observations of ﬁn whale (Balaenoptera physalus) earplugs (Roe, 1967).
Many other studies have examined whale earplugs; for example, Ohsumi (1964) investigated the annual accumulation rate of earplugs in southern-hemisphere ﬁn whales using the mark-recapture method, and Gabriele et al. (2010) conducted a comparative study of the earplug growth layer and longterm individual identiﬁcation in North Paciﬁc humpback whales (Megaptera novaeangliae).
Previously, age estimation from the earplugs of the common minke whale (B. acutorostrata) was
generally thought to be diﬃcult and impractical because of the softness of the earplugs and the poor
formation of growth layers (Sergeant, 1963; Mitchell and Kozicki, 1975; Christensen, 1981; Larsen
and Kapel, 1983; Christensen et al., 1990; Kato, 1992; Auðunsson et al., 2013). Under the Japanese
Research Program and a special permit in the Western North Paciﬁc (JARPNII), common minke
whale earplugs were carefully collected using the gelatinized extraction method (Maeda et al., 2013)
and attempts were made to read the growth layer groups. Maeda et al. (2016) reported age readability
and age estimation errors in common minke whales and concluded that the earplugs of this species canbe used as a valid age estimation tool.
However, the annual accumulation rate of growth layers has not been analyzed for North Paciﬁc
common minke whales, and age estimation was conducted on the assumption that one growth layergroup is formed per year as in other baleen species. In the case of the common minke whale, it is important to understand the periodicity of growth layer formation for age estimation. In this study, we
focused on the recently formed layer, the germinal layer (GL), of the earplug and aimed to determine
the periodicity of growth layer formation based on seasonal changes in the GL (Fig. 2).
Earplugs obtained from JARPNII Coastal Components from 2003 to 2016 were used. These surveys were conducted oﬀ Ayukawa (the Paciﬁc coast of northern Honshu; within a 50-mile radius of
Ayukawa Port 38°17′N, 141°30′E) in April and May and oﬀ Kushiro (the Paciﬁc coast of eastern
Hokkaido; within a 50-mile radius of Kushiro Port 42°59′N, 144°22′E) in September and October(Fig. 3).
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Fig. 3. Survey areas oﬀ Ayukawa (the Paciﬁc coast of northern Honshu; within a 50-mile radius of Ayukawa
Port 38°17′N, 141°30′E) in April and May, and oﬀ Kushiro (the Paciﬁc coast of eastern Hokkaido; within a
50-mile radius of Kushiro Port 42°59′N, 144°22′E) in September and October.
Table 1. Pale and dark ratio of germinal layer (GL) of the earplug of common minke whales in Ayukawa
and Kushiro.

The earplugs were preserved in 10% neutral buﬀered formalin solution. In the laboratory, after
cutting ﬂat along the central axis of the earplug by using a sharp blade, the earplug was ground on awet stone under running water to expose the neonatal line and growth layers (Fig. 2). Growth layers
were counted underwater using a stereoscopic microscope (magniﬁcation: 3.2–31.5). The age in years
was deﬁned as one growth layer group comprising a pair of pale and dark laminae in the core. The
earplugs of 360 individuals with clear growth layers from the neonatal line to the GL were selected
and observed to determine whether the GL was pale or dark (Ayukawa: 175 individuals; Kushiro: 185
individuals; age range: 1 to 44 years). For 204 of these individuals, the thickness of the pale GL wasmeasured using an image analysis software (ImageJ, a public domain, Java-based image processing
program, National Institute of Health, USA).
Pale GLs were observed in 63.4% of the earplugs from Ayukawa in April and May and in 100%from Kushiro in September and October (Table 1). For the pale GLs, the mean thickness from Ayukawa was 0.21 mm, while that from Kushiro was 0.40 mm (Fig. 4A). The pale GLs from Kushiro weresigniﬁcantly thicker than those from Ayukawa (t-test; p<0.05).
Since the thickness of the GL is expected to compress as the number of growth layers increases, thethicknesses of the pale GLs from Ayukawa and Kushiro were compared with the number of growthlayers. The GL thickness from both Ayukawa and Kushiro decreased as the number of growth layers
increased, but the Kushiro GLs were thicker than the Ayukawa GLs in all growth layer number classes(Fig. 4B). In growth-layer classes 1–5, 6–10 and 11–15, the pale GLs from Kushiro were signiﬁcantly
thicker than those from Ayukawa (t-test; p<0.05).

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Fig. 4. A: Comparison of mean thickness of the pale GL (mm) between Ayukawa in April to May and Kushiroin September to October. B: Comparison of mean pale GL thickness (mm) between Ayukawa in April to May
and Kushiro in September to October by type of growth layers.

Maeda et al. (2013) measured the length of earplugs in the North Paciﬁc common minke whale andexamined the growth of the earplug (the core and the outer covering) with age, and found that the outer covering that covers the core was not present in younger earplugs, but it became thicker with age.
In younger individuals (with fewer layers), the outer covering has not yet formed and there is more
space in the ear canal; the wax pushed out of the glove ﬁnger is not compressed and forms a thicker
layer (although younger individuals have a better metabolism). However, as the number of layers increases, it was considered that the outer covering developed and the core of the earplug becomes larger; there is less space in the ear canal and the thickness of the GL formed by extrusion from the glove
ﬁnger becomes thinner.
Lockyer (1972) examined ﬁn whales from the southern hemisphere and observed a distinctly
spaced growth layer that diminished suddenly, which was called the transition phase. The transition
phase in the earplug, where widely spaced growth layers abruptly become much closer together, indicates the age at sexual maturity. Maeda et al. (2017) reported the transition phase could be identiﬁedin the North Paciﬁc common minke whale and the mean age at transition phase was about 7 years oldfor both males and females. While some individuals showed the transition phase (rapid narrowing of
the layer interval) as early as 4 years of age (Maeda et al., 2017), the large number of young individuals with relatively wide stratum widths suggests that the SD were greater in the 1–5 years old group.
Hatanaka and Miyashita (1997) reported that immature minke whale individuals are distributed
along the northern Paciﬁc coast in early summer; mature females are abundant in high-latitude waters(Sea of Okhotsk) in summer; and mature males are distributed south of mature females in summer,
mainly east of the Kuril Islands, and are abundant oﬀ eastern Hokkaido at the end of summer. To examine seasonal changes in the accumulation of the growth layers, the feeding season migration routeof minke whales was assumed to be as follows. In early summer, minke whales migrate northward
along the northern Paciﬁc coast to feed, then migrate to Sanriku oﬀ Ayukawa in April and May, whichis the early feeding season, and then further northward to their main feeding grounds. They then migrate southward to the waters oﬀ Kushiro in September and October, which is the latter half of thefeeding season.
While individuals with dark GLs were observed in the early feeding season in Ayukawa, no individuals with dark GLs were observed in the late feeding season in Kushiro. The pale GL was signiﬁcantCetacean Popul. Stud. (CPOPS), Short paper
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ly thicker in Kushiro than in Ayukawa, suggesting that a pale layer accumulated during the feeding
season from spring to autumn, which lasts approximately six months. This was consistent with the
hypothesis that the growth layer (one pair of pale and dark laminae) is accumulated once a year incommon minke whales, as in ﬁn whales and other species.
In this study, earplugs with clear growth layers were used. However, Maeda et al. (2016) reported
that age readability of North Paciﬁc common minke whale was 45.2% for male, 41.2% for female, andmost of unreadable earplugs of mature animals had growth layers with unclear formation such as irregular lamination and partially-formed growth layers. Individuals with irregular growth layer groups
may not have a clear seasonal migration, and this point requires further investigation.
Acknowledgements

We would like to express our gratitude to all survey leaders, researchers, crew, and staﬀ of the research station that participated in JARPNII coastal surveys. We also would like to express our sincere appreciation to the anonymous reviewers who
reviewed this paper and provided useful suggestions and advice.

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Received: 31 January, 2021
Accepted: 18 May, 2021
Published online: September 30, 2021

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J-STAGE Advance published date: December 10, 2021

MATSUOKA, HAKAMADA AND MIYASHITAA NOTE ON RECENT SURVEYS FOR RIGHT WHALESEUBALAENA JAPONICA IN THE WESTERN NORTHPACIFIC
Koji MATSUOKA1*, Takashi HAKAMADA1 and Tomio MIYASHITA2
Institute of Cetacean Research, 4–5 Toyomi, Chuo-ku, Tokyo 104–0055, Japan
Fisheries Resources Institute of Far Seas Fisheries, Japan Fisheries Research and Education Agency,
5–7–1 Orido, Shimizu-ku, Shizuoka-shi, Shizuoka 424–8633, Japan*Corresponding author: matsuoka@cetacean.jp
12

Abstract
The information of the North Paciﬁc right whale in the western North Paciﬁc was summarized based on the data collected by the Institute of Cetacean Research (ICR: 1994–2016) andthe Fisheries Resources Institute (NRIFSF: 1982–2011 including recent Japanese and Russian
joint cruise data) with a total of 599,596.7 nautical miles of research distance. North Paciﬁcright whales were distributed north of 42°N in the western North Paciﬁc, including 10 motherand calf pairs during April to September. Two main high-density areas were observed north of
45°N in the area to the far oﬀshore southeast of Kamchatka Peninsula (north of 45°N to 51°N,
between 158°E and 168°E) and the central part in the Sea of Okhotsk. There were no sightings
in the Sea of Japan during 1982 to 2016. A total of 60 individuals were photographed and 28
biopsy samples were collected. It appears that this species has been showing signs of increasesince 1990’s, but it is necessary to carefully monitor this population in the future to check thetrend. Further surveys, analysis and international collaboration are required to improve our understanding of this species.
Key words:

western North Paciﬁc, sighting survey, distribution, North Paciﬁc right whale,
Eubalaena japonica.

The North Paciﬁc right whale (Eubalaena japonica) mainly feeds on copepods and other small invertebrates, such as krill and copepods and they migrate annually between low-latitude winter breeding
grounds and colder summer feeding grounds (Nishiwaki, 1966; Kawamura, 1982). In the western North
Paciﬁc, according to the plotted spatial distribution of American whaling, based mainly on the original
data in the studies of Maury (1852) and Townsend (1935), the right whales were concentrated on eitherside of the North Paciﬁc, and there were also seasonal changes in distribution, with whales occurring on
both sides of the North Paciﬁc in the periods March–May and June–August (Smith et al., 2012). Because
they are a slow-swimming whale that ﬂoats after death and provided considerable quantities of commercially valuable whale oil and baleen, they were a highly desirable target species (Omura et al., 1969;
Omura, 1986). For this reason, they were taken extensively by whaling in the 19th and 20th centuries.
Additionally, this species was targeted by illegal Soviet whaling in the 1960’s (Ivashchenko et al., 2017).
In the Sea of Okhotsk, according to earlier studies in the 1980’s–90’s, right whales occurredin small numbers in the central and northeastern parts, and also in few sightings to the southeast
of Sakhalin Island and by the Sea of Okhotsk side of the central Kuril Islands (Berzin and Vladimirov, 1986). There have been no observations of right whales in the northern Sea of Japan by Russian vessels since the early the 1960’s (Vladimirov, 1993).
In the western North Paciﬁc outside of the Sea of Okhotsk, it was also noted that the Kuril Islands,
the Kamchatka coasts and oﬀshore areas are likely to be major summer feeding areas, based on his-252

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A NOTE ON RECENT SURVEYS FOR RIGHT WHALES

Fig. 1. Schematic map of oceanographic conditions around western North Paciﬁc. The northern part of
the ICR survey area is under the inﬂuence of the Oyashio (a subarctic western boundary current with cold,
low-salinity water) whereas the southern part is under the inﬂuence of the Kuroshio and its extension (the subtropical western boundary current with warm, high-salinity water) (after Okazaki et al., 2016).
Table 1. Summary of North Paciﬁc right whale sightings during the JARPN/JARPNII (1994–2016) from
April to September, describing the year in which the right whale was sighted. Sch.: Number of the primarysightings of schools. Ind.: Number of the primary sightings of individuals. Calf: Number of calves includingInd. Mss: observed mean school size (Ind./Sch.). SST: Range of surface temperature of the sighting position.
Photo-ID: number of individuals, Biopsy sample: number of samples.
Year

Western North Paciﬁc
Sch.

Ind.

Calf

Mss

SST (°C)

Photo-ID

Biopsy sample

1994
1995
1997
1998
2001
2002
2003
2004
2005
2006
2007
2008
2009
2011
2012
2013
2014
2015

1
2
2
4
2
2
5
2
2
11
1
5
1
13
2
1
1
3

2
2
3
6
3
2
6
4
4
15
1
6
1
20
2
1
1
4

1
0
0
2
1
0
1
0
2
0
0
1
0
2
0
0
0
0

2.00
1.00
1.50
1.50
1.50
1.00
1.20
2.00
2.00
1.40
1.00
1.20
1.00
1.54
1.00
1.00
1.00
1.33

17.0
6.8–13.2
3.5–7.5
3.3–13.3
12.0–16.9
13.4–16.0
3.0–15.7
10.3–12.7
12.3–16.6
7.8–10.3
13.3
8.8–15.1
7.5
2.7–4.2
8.3–13.9
13.4
13.5
2.3–2.4

2
1
1
5
3
0
4
3
2
11
0
4
1
18
2
1
1
1

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

Total

60

83

10

1.38

2.3–17.0

60

28

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MATSUOKA, HAKAMADA AND MIYASHITA

torical records (e.g., Omura, 1986; Vladimirov, 1993; Brownell et al., 2001; Clapham et al., 2004;
Josephson et al., 2008). The distribution pattern was reported using the Japanese Scouting Vessel(JSV) data (5°×5° square analyses), and there were no sightings outside the Sea of Okhotsk in August
between 1964 and 1990 (Miyashita et al., 1995). Recent sighting information has been limited (e.g.,
Matsuoka et al., 2016). The R/V Oshoro-Maru also reported few sightings in the east of the Kurile
Islands in June in 2012 and 2013 (Sekiguchi et al., 2014). In this note, we examined the North Pacific right whale distribution pattern using a combination of two major sighting datasets in the western
North Paciﬁc and the Sea of Okhotsk covering the years 1982 to 2016.
The Institute of Cetacean Research (ICR) conducted the Japanese Whale Research Program under special Permit in the North Paciﬁc (JARPN: 1994–1999), and JARPN Phase II (2000–2016) which included
systematic whale sighting surveys with and without sampling activity. The research areas of this program
were the western North Paciﬁc waters north of 35°N (Fig. 1). All whale species were recorded during thesighting surveys. When a school that seemed to be of large cetacean was sighted, the ship approached tothe school to identify the species, estimate the school size, and obtain other information (e.g., the numberof calves, sea surface temperature at sighting position etc., and conducted opportunistically photo-ID andbiopsy sampling). As for the results, North Paciﬁc right whale is the rarest baleen whale sighted. Table 1
summarizes the primary whale sightings during the JARPN/JARPNII surveys from April to September. A
total of 213,425.4 n.miles were surveyed and 60 schools (83 individuals including 10 calves, 16.6% of theschools were mother & calf pair during 23 years) were observed. The observed mean school size was 1.38
individuals (n=60). The surface temperature ranged from 2.3°C to 17.0°C.
The National Research Institute of Far Seas Fisheries (NRIFSF; formerly Far Seas Fisheries ReTable 2. Summary of North Paciﬁc right whale sightings during the NRIFSF sighting surveys (1984–2003),
describing the year in which the right whale was sighted. Sch.: Number of the primary sightings of schools.
Ind.: Number of the primary sightings of individuals. Mss: observed mean school size (Ind./Sch.). SST: Rangeof surface water temperature of the sighting position. Data after 2004 are undergoing analysis.
Year

Sea of Okhotsk and western North Paciﬁc
Sch.

Ind.

Mss

SST

1984
1990
1991
1992
2003

2
2
1
17
13

4
5
1
26
16

2.00
2.50
1.00
1.53
1.23

16.9–17.3
8–12.917.0
8.9–11.8
3.8–13.4

Total

35

52

1.49

3.8–17.3

Table 3. Summary of North Paciﬁc right whale sightings during Japanese–Russian cruises listing the year the survey was conducted between 1998 and 2011 in the Sea of Okhotsk during May to September. Sch.: Number of the
primary sightings of schools. Ind.: Number of the primary sightings of individuals. Calf: Number of calves including Ind. Mss: observed mean school size (Ind./Sch.). SST: Range of surface temperature of the sighting position.
Year
1998
2000
2003
2009
2010
2011

254

Sea of Okhotsk
Sch.

Ind.

Calf

Mss

SST

2
3
16
17
3
1

2
3
20
29
4
1

—
—
—
0
1
0

1.00
1.00
1.25
1.71
1.33
1.00

—
—
—
7.4–15.7
8.4–14.3
5.8

Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 252–257

A NOTE ON RECENT SURVEYS FOR RIGHT WHALES

search Laboratory) started dedicated whale sighting surveys in the North Paciﬁc in the early 1980’s
from July to September (1982–2012) including the Japanese–Russian cruises (1998–2011) in the
Sea of Okhotsk (Tables 2 and 3). The sighting method and procedure were based on the International
Whaling Commission (IWC) Southern Hemisphere cetacean sighting surveys (e.g., Miyashita andKato, 1998). These procedures are almost the same as the JARPN/JARPNII II surveys describedabove, except that some vessels did not have a top barrel. A total of 386,171.3 miles were surveyed.
Generally, right whales were distributed north of 50°N in the central part of the Sea of Okhotsk after
April when the sea ice disappears, although there was not enough eﬀort in the northern part for logistical reasons. The observed mean school size was 1.49 individual (n=35). The surface temperature
ranged from 3.8°C to 17.3°C.
As a result, Fig. 2 shows the combined density index (by Lat.1°×Long.1°square analyses; numberof primary sightings of individuals/100 n.miles) of North Paciﬁc right whales by the JARPN/JARPNII
and NRIFSF data (1982–2016) during April to October. A total of 599,596.7 n.miles were surveyed.
New sightings conﬁrm that there are two high-density areas observed north of 45°N in the far oﬀshore
southeast of the Kamchatka Peninsula (from north of 45°N to 51°N, between 158°E and 168°E), andnorth of 50°N in the Sea of Okhotsk. These high-density areas seemed to be their feeding grounds andcoincided with previous large-scale distribution patterns based on catches (Smith et al., 2012) andsightings (Miyashita et al., 1995). On the other hand, there were no sightings in the Sea of Japan, although there were two migration routes along both sides of the main Japanese island, based on historical whaling data (Omura, 1986).
The low number of sightings compared to other baleen whales conﬁrms the rarity of this species
in the western North Paciﬁc, and reinforces the belief that both historical and illegal whaling in the
1960’s devastated the population. It appears that this species has been showing signs of recovery sincethe 1990’s, but it is necessary to continue monitoring this population to assess its trend in the future.
Photo-ID data and biopsy samples were collected opportunistically during JARPN/JARPNII surveys

Fig. 2. The map shows combined Density Index (primary sightings of individuals/100 n.miles) of North Paciﬁcright whales comprising the whole ICR (1994–2016) and NRIFSF (1982–2003) datasets from April to Octoberby Lat.1°×Long.1°square, including the Japanese and Russian joint cruises (1998–2011) in the Sea of Okhotsk.
Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 252–257

255

MATSUOKA, HAKAMADA AND MIYASHITA(Table 1, Figs. 3a–3c). Sixty individuals were photographed, and matching work is ongoing. Also, a
total of 28 biopsy samples were collected and analyzed including the samples collected in the easternside of the Paciﬁc under international collaboration (Pastene et al., in review). Further survey, analysis
and international collaboration are required to improve our understanding on the seasonal distribution,
migration pattern and abundance estimation of this rare species.

Fig. 3a. A head of North Paciﬁc right whale sighted in the western North Paciﬁc on 2 August 2006 (left), anda long white scars on the caudal peduncle keel of a right whale sighted in the western North Paciﬁc on 1 August 2006 (right).

Fig. 3b. A North Paciﬁc right whale mother and calf pair sighted in the western North Paciﬁc on 2 August
2008 (left), and surfacing individual, sighted in the western North Paciﬁc on 31 May 2012 (right).

Fig. 3c. A white spot on the right side of the lower jaw of a right whale sighted in the western North Paciﬁc on 29
May 2011 (left), and scars on the back of an individual sighted in the western North Paciﬁc on 6 June 2012 (right).

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A NOTE ON RECENT SURVEYS FOR RIGHT WHALES

Acknowledgements

We would like to express our thanks to all cruise leaders, captains, oﬃcers, crew, and researchers involved in the NRIFSF
and the ICR surveys and marine mammal researchers of VNIRO and TINRO-Center (Russian Federation). Special thanks to
Dr. Kirill Zharikov for the preparation of an earlier document which was submitted to the IWC/SC (SC/67a/NH07). We also
thank Drs. Hidehiro Kato, Yoshihiro Fujise and Luis A. Pastene for their help in the preparation of this paper. We are gratefulfor the fair and constructive reviews by anonymous reviewers. Finally, we thank the late Dr. Seiji Ohsumi for his endorsement of the Japanese–Russian joint cruise cooperation project and for his suggestions on preparing this paper.

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Received: December 25, 2020
Accepted: September 21, 2021
Published online: December 10, 2021
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J-STAGE Advance published date: December 8, 2021

DIALLO, SANE, NELSON, KATSUMATA AND HAKAMADACETACEANS OFF GABON BASED ON
A 2011 SIGHTING SURVEY, WITH A PRELIMINARYDENSITY ESTIMATE OF THE HUMPBACK WHALE
MEGAPTERA NOVAEANGLIAE
Samba T. DIALLO1, Aboubacar SANE1, Thomas NELSON2,
Taiki KATSUMATA3 and Takashi HAKAMADA3*Centre National des Sciences Halieutiques de Boussoura (CNSHB),
814 Rue MA 500, Corniche Sud Madina, Boussoura Port, Conakry 224, Guinea
2
Department of Fisheries (DOF). Ministry of Agriculture, Fisheries, Physical Planning, Natural Resources
and Co-operatives (MAFPPNRC) Conway Post Oﬃce, Castries, LC04 30, Saint Lucia
3
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Corresponding author: hakamada@cetacean.jp
1

Abstract
Results of a cetacean sighting survey in coastal Gabon waters from September 4 to 9, 2011
are reported. Four whale species humpback (30 schools/191 individuals), Bryde’s (1 school/
2 individuals), sei (1 school/6 individuals), and sperm (2 schools/2 individuals), and 3 speciesof dolphin (pantropical spotted (1 school/150 individuals), Atlantic spotted (1 school/40 individuals) and bottlenose (1 school/25 individuals)) were observed over 232.1 nm of transectlines (26% of planned transects, covering 878.0 nm). Based on these survey data, using distance sampling methods, we estimate the density of humpback whales in this region to be
0.481 individuals/nm2 (CV=0.477).
Key words:

Gabon, humpback whale, distance sampling, density estimation, line transect.

Humpback whales Megaptera novaeangliae occur worldwide in all major oceans (Clapham, 2018).
The Scientiﬁc Committee of the International Whaling Commission (IWC/SC) identiﬁed seven breeding stocks (A–G) of this species in the Southern Hemisphere (IWC, 2005), with waters oﬀ Gabon
including part of stock B. From 1912–1930, 7,883 humpback whales were landed at whaling stations
in Gabon (Harmer, 1928; Best, 1994), and a further 7,080 animals were landed in 9 whaling seasons
between 1934 and 1959 (Budker and Collignon 1952; Budker 1952, 1953; Budker and Roux 1968;
Weir, 2010). While commercial humpback whaling in the Southern Hemisphere was banned by the
IWC in 1963 (IWC, 2011), after more than 50 years it is thought that stocks of this species may haverecovered. A comprehensive assessment of Southern Hemisphere humpback whales was completed in2015. An assessment model was conducted then using abundance estimates by mark-recapture methods provided in Collins et al. (2010); the depletion level (i.e., abundance per initial population size) of
the humpback whale breeding stock oﬀ Gabon was estimated to be 74% in 2015 (IWC, 2016).
Three cetacean sighting surveys have been completed in COMHAFAT (La Conférence Ministérielle
sur la Coopération Halieutique entre les Etats Africains Riverains de l’Océan Atlantique) coastal zone
waters. The ﬁrst cetacean sighting survey in Gabon coastal waters occurred in 2011; a second survey
took place in the Gulf of Guinea in 2013, covering the Côte d’Ivoire, Ghana, Togo and Benin (Diallo
and Bamy, 2013). A third survey was conducted in coastal waters of Guinea, Sierra Leone and Liberia
in 2018 (Diallo et al., 2018). A fourth proposed (2019) survey was scheduled for coastal waters oﬀ
Guinea, but it has yet to be done. During the 2019 IWC/SC68a meeting in Nairobi, Kenya, the planfor this fourth survey in the COMHAFAT coastal zone was presented. The IWC Standing Working

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CETACEANS OFF GABON BASED ON A 2011 SIGHTING SURVEY

Group on Abundance Estimates, Status of Stocks, and International Cruises (ASI) encouraged thatabundance estimates of cetacean species sighted in the COMHAFAT coastal zone be presented to the
future IWC/SC meeting to determine how they could be used for the Revised Management Procedure(RMP) or for other cetacean studies in this region (IWC, 2020). For this reason, we report hitherto unpublished estimates of humpback whale abundance data from the 2011 survey oﬀ Gabon.
The 2011 survey was conducted during the dry season in waters oﬀ Gabon (when rain is scarceand wind is weak). Because many cetacean species migrate into waters oﬀ Gabon during the austral
winter (Weir, 2010), we performed this survey during this period. The main objective was to obtain
information on the abundance and distribution of cetaceans in the coastal zone of Gabon (Diallo andBamy, 2013). The survey was performed by the Centre National des Sciences Halieutiques of Boussoura (CNSHB) under the auspices of COMHAFAT, with collaboration from some African ﬁsheries
institutions and ﬁsheries research centers, such as the Direction Générale des Pêches (DGP) in Gabon,Centre de Recherches Océanologiques (CRO) of Abidjan in Côte d’Ivoire, Institut Mauritanien deRecherche Océanographique et des Pêches (IMROP) of Nouadhibou in Mauritania, Centre de Recherche Océanographique de Dakar Thiaroye (CRODT) of Dakar in Senegal, Direction des Pêches (DP)of Cotonou in Benin, Marine Fisheries Research Division (MFRD) of Tema in Ghana, Fisheries andOceanography Research Station (SRHOL IRAD) of Limbé in Cameroon, and the Center for Applied
Fisheries Research (CIPA) of Bissau in Guinea-Bissau.
The N/O General Lansana Conté, a research vessel of Guinean nationality, 29.93 m in length,3.25 m in draught, of 1400 CV horsepower and 198 GRT (Fig. 1), was used for the survey. Further
survey details are provided in Diallo and Bamy (2013). A 10-day survey period was scheduled in September 2011, as per the itinerary shown in Table 1.
The study area was in the Gabonese EEZ including the isobaths from 200 m to 1,000 km, and excluded shallow waters and areas around oil ﬁelds. Six survey blocks were identiﬁed (left panel, Fig. 2)
comprising three oﬀshore (ON, OM, OS) and three coastal (CN, CM, CS) blocks. Within blocks, zigzag track lines of 878.0 nm total length were set (right panel, Fig. 2). Survey participants included 10
vessel crew and 9 research staﬀ; 2 Guinean researchers conducted the survey, with researchers fromeach of 6 African countries (1 from each of Mauritania, Senegal, Ghana, Benin, and Togo, and 2 from
Gabon) also participating. The cruise leader, Samba Diallo, entered data onto a computer during thesurvey; other scientists helped identify schools of cetaceans and count numbers of individuals.
The survey used a line-transect method (Burnham et al., 1980) authorized by the Scientiﬁc Com-

Fig. 1. The N/O General Lansana Conté used for COMHAFAT cetacean sighting surveys.
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DIALLO, SANE, NELSON, KATSUMATA AND HAKAMADA

Table 1.

Itinerary of the 2011 cetacean sighting survey in Gabon coastal waters.
Date
August 29
August 28–30
August 31
September 2
September 3
September 4
September 9
September 10
September 11
September 12
September 13–14
September 14

Event
Vessel left Conakry to LibrevilleParticipants arrived in LibrevillePre-survey meeting was held in Libreville
Vessel arrived at Libreville
Vessel left Libreville to survey area
Survey was started
End of the survey
Vessel arrived in Libreville
Vessel left Libreville to Conakry
Post-survey meeting was held in LibrevilleParticipants left Libreville
Vessel arrived at Conakry

Fig. 2. Gabon coastal water research areas: 2011 survey blocks conducted by COMHAFAT (left panel) andsurvey zig-zag track lines of 878.0 nm length set in survey blocks (right panel) (after Diallo and Bamy, 2013).

mittee of the IWC, following procedures and protocols in the requirement and guidelines for sighting
surveys (IWC, 2012). Surveys occurred during daylight from 30 min after sunrise to 30 min before
sunset, in good weather conditions (Beaufort scale ≤4, visibility >2 nm). A normal closing mode survey was performed for all encountered cetacean species; for further details of sighting procedures see
Diallo and Bamy (2013). Angles to sightings were measured using angle boards situated in front ofobservers. To calibrate the distances to and angle measurements of sightings, distance and angle measurement experiments were performed during the survey (to adjust measurement error if necessary).
During the survey, sighting eﬀort and weather data were recorded. All data, including photographs
belong to the COMHAFAT, with copies stored at the CNSHB in Guinea, and the Fisheries Resources
Institute, Japan Fisheries Research and Education Agency, in Japan.
To estimate humpback whale density, we used data for 13 primary (ship on-eﬀort) sightings for thisspecies, and eﬀort data. For detection function estimation, conventional distance-sampling methods
were used, including multi-covariate distance sampling, where detection on the track line is assumed
as certain (i.e. g(0)=1). The covariate to be considered for possible inclusion in the detection function

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CETACEANS OFF GABON BASED ON A 2011 SIGHTING SURVEY

is school size. Missing values for other candidate covariates (such as Beaufort scale and visibility)
precluded our considering them in detection functions.
We used the Multiple Covariate Distance Sampling (MCDS) Engine in the mrds package in R for
calculations (Thomas et al., 2010). The Hazard rate and Half normal models are ﬁtted as candidate
models for the detection function. The full model of the detection function is provided by:

{

}

−b


Hazard rate: g ( x, z ) =1 − exp  − x
a exp( Size) 



(1)

2

Half normal: g ( x, z ) = exp  − x
2a 2 exp{2( Size)}(2)

where x is the perpendicular distance from the track line to the sighting, z is a vector of covariates(i.e., Size), a (a>0) and b (b≥1) are coeﬃcients to be estimated, and Size is observed school size.
Density estimation is the second step used in the distance-sampling method. The analytical method
follows that of Buckland et al. (2015). For analysis we assumed that all schools of cetaceans on the
track line were detected. Density and its variance were estimated based on a Horvitz–Thompson likeestimator of abundance, as expressed in equations (3) and (4), respectively:
D=

1 n
si
2WL i= 1 p ( xi , zi )(3)where D is the density estimate, W is the truncation distance, L is the searching eﬀort, si is the size forith school, and p(xi, zi) is the probability of detection at a perpendicular distance xi and covariate zi.
2
2
K
r
r
1
PC PC 1 
 1  
 PCk PC +l
H jm (θ ) var( D ) = kθ j θm
L 
 2WL   L( K  1) k= 1  lk
j= 1 m= 1






(4)

where K is the number of transect, lk is searching distance in kth transect, PCk is the abundance estimate in the covered region on the kth transect, PC is the abundance estimate in the covered region, andH −1
jm (θ) is the jmth element of the inverse of the Hessian matrix of detection function with respect tothe vector of the coeﬃcients θ.
Akaike information criterion (AIC) values were compared to select the best model to estimate theprobability of a school being detected p(zi) given the covariate zi, which is expressed by the following
equation (5) using the detection function g(x, zi) (see equations (1) and (2)). The detection function
with the minimum AIC is selected as the best model among the candidate models.
p ( zi ) =

1
W

W

1

 g( x, z ) dx = W fˆ ( 0|z )
0

i

i

(5)

The 2011 survey in coastal waters of Gabon covered 232.1 nm over 6 days—only 26% of theplanned searching distance. Although 10 survey days had been initially scheduled, only the ON, CN
and CM blocks out of 6 blocks could be covered within available time (Fig. 3). During this survey, 30
schools of humpback whales (191 individuals), 2 schools of sperm whales (Physeter macrocephalus)(both with 1 ind.), and 1 school of each of Bryde’s (Balaenoptera edeni) (2 ind.) and sei (B. borealis)(6 ind.) whales, and 1 school of pantropical spotted (Stenella attenuata) (150 ind.), 1 school of Atlantic
spotted (S. frontalis) (40 ind.), and 1 school of bottlenose (Tursiops truncatus) (25 ind.) dolphins weredetected (Table 2). Sighting positions for (a) humpback whales, (b) Bryde’s, sei, and sperm whales,and (c) dolphins are shown in Fig. 3. No feeding behavior was observed during the survey.
The best model of estimated detection function ﬁtted to the relative frequency of detected schools
by perpendicular distance intervals as a function of perpendicular distance from the track line toa humpback whale sighting using 2011 survey data is depicted in Fig. 4. A density estimate of
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DIALLO, SANE, NELSON, KATSUMATA AND HAKAMADA

Fig. 3. Map of the 2011 survey area, blocks, line transects, and sighted schools of humpback whales (upper
left panel), Bryde’s, sei and sperm whales (upper right panel), and dolphins (lower panel).
Table 2.

Primary and secondary sightings during the 2011 cetacean sighting survey.
Species nameHumpback whale
Sperm whale
Sei Whale
Bryde’s whale
Pantropical spoted dolphin
Atlantic spotted dolphin
Bottlenose dolphin
Unidentiﬁed whale
Unidentiﬁed dolphin

262

Primary

Secondary

Total

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

13
1
0
1
0
1
1
2
3

50
1
0
2
0
40
25
2
15

17
1
1
0
1
0
0
6
1

141
1
6
0
150
0
0
13
10

30
2
1
1
1
1
1
8
4

191
2
6
2
150
40
25
15
25

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CETACEANS OFF GABON BASED ON A 2011 SIGHTING SURVEY

Fig. 4. Plot of the best model of estimated detection function ﬁtted to relative frequency of schools as a function of perpendicular distance (nm) from the track line to a humpback whale sighting based on 2011 survey
data. Cdf in the caption for the right panel is the abbreviation for cumulative distribution function.

0.481 ind./nm2 (CV=0.477) from this model has a low AIC of 11.437. Branch (2011) estimated humpback whale abundances in feeding grounds in Antarctic waters south of 60°S during the austral summer to be 4.36×10−5 ind./nm2 (CV=0.53) in 1992/93 between 0° and 40°E, and 2.55×10−4 ind./nm2(CV=0.75) in 1996/97 between 30°W and 0°. Branch (2011) considered that estimates of abundancein breeding stock B were greater than in the assumed corresponding feeding area (20°W–10°E) in
Antarctic waters because humpback whales in their southern migration migrated to waters north of
60°S. It is therefore likely that most humpback whales from this breeding stock do not migrate as far
south as 60°S to reach that area covered by the International Decade of Cetacean Research/Southern
Ocean Whale and Ecosystem Research Programme (IDCR/SOWER) surveys. Japanese Sighting Vessel (JSV) data identify a high density area north of 60°S (Miyashita et al., 1995), with many sightingsof this species in 2005/06 during the IWC SOWER survey (Ensor et al., 2006). Another possibility
is that animals in breeding stock B migrate to a diﬀerent longitudinal sector, supported by genetic
evidence that breeding stock B does not diﬀer signiﬁcantly in Areas II and III, in longitudinal sectors
60°W–70°E (Loo et al., 2011).
Because more humpback whales were sighted in CN and CM than in ON blocks, more survey eﬀort
could be allocated to coastal as opposed to oﬀshore blocks in future surveys (to more accurately estimate humpback whale abundance). Buckland et al. (2015) and the IWC (2012) suggested allocating
increased eﬀort to known high density strata. If more primary sightings occur in future COMHAFAT
surveys, further analyses of abundance estimates could be performed for other species from the 2011
survey data (i.e., sei, Bryde’s and sperm whales, and pantropical spotted, Atlantic spotted, and bottlenose dolphins).
Acknowledgements

The authors thank Drs. Koji Matsuoka, Megumi Takahashi and Luis A. Pastene of the Institute of Cetacean Research forkindly providing useful programs, valuable advice for data analysis, and for their kind attention to us during the workshop ofabundance estimates. Mr. Hideki Moronuki (Fisheries Agency of Japan) is also graciously thanked for providing the authorsan opportunity to estimate the abundances of cetaceans in sighting surveys in the COMHAFAT coastal zone. We hope that
this kind of collaboration will continue so that we can more accurately estimate the abundances of all cetacean species insurveys. We would also like to thank Dr. Hideyoshi Yoshida, from the Fisheries Resources Institute, Japan Fisheries Researchand Education Agency, for kindly providing scientiﬁc advice and instructions for conducting cetacean sighting surveys in
the COMHAFAT coastal zone. Thanks also to the captain, crew and researchers aboard the N/O General Lassana Conté who
participated in the survey. We would like to thank anonymous reviewers for their valuable suggestions and comments to improve this paper.

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DIALLO, SANE, NELSON, KATSUMATA AND HAKAMADA

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Received: January 15, 2021
Accepted: August 19, 2021
Published online: December 8, 2021

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J-STAGE Advance published date: December 8, 2021

JAPANESE WHALE SIGHTING SURVEYS IN THE CHUKCHI SEA

HISTORICAL JAPANESE WHALE SIGHTING SURVEYS
IN THE CHUKCHI SEA
Keiko SEKIGUCHI
Iruka Lab, 3–10–15 Tamagawa, Chofu, Tokyo 182–0025, Japan
Corresponding author: keiko.the.dolphin@gmail.com

Abstract
Before the T/S Oshoro Maru surveys in 2007 and 2008, three Japanese research vessels had
conducted whale sighting surveys in the Chukchi Sea, in 1937 (R/V Kaihou Maru and Yūki
Maru) and 1958 (R/V Fumi Maru No.16). However, their results are not well-known. The author found four references about these voyages and compared the results with T/S Oshoro Marudata from the 2007 and 2008 voyages. Despite the long period separating these surveys (about
20 years and then 50 years), the whale distributions in this region were somewhat similar.
Key words:

Chukchi Sea, Japanese whale sighting survey, large whale species.

Despite its biological importance, the Chukchi Sea is one of the least surveyed regions. This region is closed down for a long period by winter ice, and often covered by deep fog during summer.
However, at least three Japanese research vessels managed to conduct oceanographic and biologicalsurveys in the Chukchi Sea, including shipboard cetacean sighting surveys. R/V Kaihou Maru (theMinistry of Agriculture and Forestry, 1064 gross tonnage) and Yūki Maru (Hokuyou-Hokei Co., 350
gross tonnage) carried out surveys from the end of July to the beginning of August, 1937, and the
R/V Fumi Maru No.16 (Taiyo Fisheries Co., 598 gross tonnage) survey was conducted in the summerof 1958. This author found four cruise reports in Japanese about these cruises (Nasu, 1960a, 1960b;
Yamaguchi, 1961; Tatou, 1985). The cruise report of R/V Yūki Maru has not been found, and thus its
data were extracted from Nasu (1960a) and Tatou (1985). The author had an opportunity to conductcetacean sighing surveys in the Chukchi Sea from T/S Oshoro Maru (Hokkaido University, Japan;
72.8 m length and 1,779 gross tonnage) as a part of the International Polar Year (IPY) special researchin summer 2007 and 2008. It seems that these historical cruises did not have systematically organized
track lines in the way our Oshoro Maru cruises did; however, their data are very important for describing the distribution of whales in this region in the past. In this Short Note, the author would like tocompare sighting results among those historical cruises and the T/S Oshoro Maru cruises, in order toinvestigate any change in whale occurrence in the Chukchi Sea.
R/V Kaihou Maru and Yūki Maru survey in summer 1936
The R/V Kaihou Maru entered the Chukchi Sea on 26 July, 1937 and reached the furthest northpoint (71°12′N, 174°50′W) by a Japanese vessel in 29 July. The vessel continued its survey westward
along the ice edge and then on 1st August headed back along the Russian coast line. Their survey covered the entire western part of the Chukchi Sea (Fig. 1) and Table 1 shows the summary of their cetacean sightings extracted from Yamaguchi (1961). Six species of large whales were sighted: blue whale
Balaenoptera musculus, ﬁn whale B. physalus, humpback whale Megaptera novaeangliae, right whale
Eubalaena japonica, minke whale B. acutorostrata and sperm whale Physeter macrocephalus.
On the other hand, the R/V Yūki Maru sailed along the entire coast line of the Chukchi Sea in about
the same period (26 July to 3 August, 1937) (Fig. 2, from Nasu, 1960a). The main purpose of the R/VYūki Maru voyage was the investigation of possible new whaling grounds and thus it is presumed thatthe vessel had professional observers. Unfortunately, no detailed data could be found for this Yūki
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SEKIGUCHI

Fig. 1. The track line and whale sighting locations of R/V Kaihou Maru in summer 1937 (the ﬁgure wasconverted from Fig. 2 in Yamaguchi, 1961). Sighting location data are from Table 1.
Table 1. Sighting summary for R/V Kaihou Maru survey in summer 1937. Data were extracted from Table 1
in Tatou (1985).
Species
Sighting location

Blue
whale

66°36′N, 169°43′W

Fin
whale

Humpback
whale

Sperm
whale

Right
whale

15–16

66°42′N, 169°49′W

167°20′N, 170°08′W

11

70°00′N, 173°05′W

1

69°50′N, 179E50′W
67°05′N, 171°05′W

6
15–16

67°00′N, 170°55′W

866°50′N, 170°35′W

about 200

66°42′N, 170°35′W

Minke
whale

11

about 10050

66°38′N, 170°15′W

about 100

66°25′N, 169°52′W

2Maru survey (Table 2), but Nasu (1960b) described that “many” ﬁn whales were sighted near the coastof Siberia (66°40′N, 170°W), at least one humpback whale, and a rather unusual sighting of a rightwhale and a sperm whale.

266

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JAPANESE WHALE SIGHTING SURVEYS IN THE CHUKCHI SEA

Fig. 2. The track line and sighting positions by R/V Yūki Maru in 1937 summer (from Fig. 5 in Nasu, 1960a).
Symbols explanation: sperm whale (closed circle); ﬁn whale (hatched circle); humpback whale (crossed circle);right whale (circle with a big black dot). Circles with a small dot indicate vessel position at noon.
Table 2. Sighting summary from R/V Yūki Maru during the 1937 summer cruise, based on data from Nasu,
1960a and Tatou, 1985.
Species

Total no. of animals

Approximate sighting location

Fin whale
Humpback whale
Right whale
Sperm whale“many”
1?
1?
?

66°40′N, 170°W
66°40′N, 170°W
66°30′N, 170°W
66°30′N, 170°W

R/V Fumi Maru No.16 survey in summer 1958
The R/V Fumi Maru No.16 surveyed the Chukchi Sea between 16 and 20 August 1958. Fig. 3
shows the track line and Fig. 4 indicates whale sighting locations (ﬁgures from Nasu, 1960a). A totalof 86 animals were sighted. Most were gray whales Eschrichtius robustus (82 animals), but there werealso two right whales, one ﬁn whale, and one unidentiﬁed whale (Table 3; data from Nasu, 1960a).
T/S Oshoro Maru survey in summer 2007 and 2008
The T/S Oshoro Maru conducted two IPY oceanographic and biological research cruises in the
Chukchi Sea. In 2007, the survey started from 5 August and ended on 15 August at Nome, AK. In
2008, the cruise schedule was a month earlier, starting from Nome on 6 July and ending at Dutch Harbor, AK on 17 August. Details of course lines and oceanographic observations are available in data
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SEKIGUCHI

Fig. 3. The track line of R/V Fumi Maru No.16 survey in summer 1958 (from Fig. 1 in Nasu, 1960a).

books from Hokkaido University (Faculty of Fisheries Sciences, Graduate School of Fisheries Sciences, School of Fisheries Sciences, Hokkaido University 2008, 2009). Table 4 summarizes sighting
results in the Chukchi Sea and Fig. 5 shows track lines and cetacean sighting positions. A total of six
cetacean species were identiﬁed: bowhead whale Balaena mysticetus (30 animals in 2007), humpback
whale (three in 2007 and one in 2008), minke whale (three in 2007 and nine in 2008), gray whale (212
in 2007 and 16 in 2008), killer whale Orcinus orca (ﬁve in 2007) and harbor porpoise Phocoena phocoena (one in 2007 and six in 2008).
These ﬁve relevant cetacean surveys were done a long time apart (about 20 years, then 50 years respectively); however, sighting locations are rather similar, the main locations being just after the Bering Strait and oﬀ Point Hope. Russian–American aerial and shipboard surveys between 1968 and 1982
also indicated gray whale aggregations just after the Bering Strait (Berzin, 1984). It seems these large
whale species utilized the Chukchi Sea region as their summer feeding area, well before the area was
widely freed from ice because of “global warming”.
Table 5 summarizes the presence/absence of large whale species sighted in the Chukchi Sea survey areas by the ﬁve cruises. Only R/V Kaihou Maru sighted six species of large whales, blue, ﬁn,humpback, right, minke and sperm whales, but not gray whales, in the Chukchi Sea surveyed area
(also see Table 1). Nasu (1960a) assumed poor sightings from R/V Fumi Maru No.16 were caused bybad visibility (dense fog) and the whale migration period. The second year (2008) of the T/S Oshoro
Maru Chukchi Sea survey also encountered very poor visibility condition and thus the total sighting
was much less than in the previous year (Table 4). Poor visibility for the R/V Fumi Maru No.16 survey
might have caused a lack of humpback whale sightings as well. Humpback whales were sighted inlarge numbers (about 120? animals in total, Table 1) by R/V Kaihou Maru, at least one animal by R/VYūki Maru (Table 2) and one school in each of the T/S Oshoro Maru 2007 and 2008 surveys (Table 4).
Although no ﬁn whales were sighted by the T/S Oshoro Maru 2007 and 2008 surveys, animals weresighted in the three surveys in 1936 and 1958 (Tables 1, 2, 3 and 5; Figs. 1, 2, and 4). Fin whales were

268

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JAPANESE WHALE SIGHTING SURVEYS IN THE CHUKCHI SEA

Fig. 4. Whale sighting positions during the R/V Fumi Maru No.16 survey in summer 1958 (from Fig. 4 in
Nasu, 1960a).
Table 3. Sighting summary from R/V Fumi Maru No. 16 during the 1958 summer cruise, based on data fromNasu, 1960a and Tatou, 1985.
Species
Fin whale
Right whale
Gray whale

UnID whale

Total no. of animals

Approximate sighting location

1
2
78
2
2
1

50 nm oﬀ Point Hopeoﬀ Point Hope?
67°N, 170°W
oﬀ Point Hope?
?

sighted oﬀ the Bering Strait and Point Hope, and even at the far north ice edge (66°36′N, 169°43′W;
Table 1; Fig. 1). Fin whales were often sighted in the Bering Sea during the T/S Oshoro Maru 10-year
cruises (a total of 399 ﬁn whales in 174 groups, Table 1 in Sekiguchi, 2015). Before the North Paciﬁc
ﬁn whaling ban in 1976, the ﬁn whale summer geographical distribution might have extended further
into the Chukchi Sea. Berzin and Rovnin (1966) and Tomilin (1967) also noted the occurrence of ﬁnwhales in the Chukchi summer.
Sightings of right whales by R/V Kaihou Maru, Yūki Maru and Fumi Maru No.16 were rather unusual. Tomilin (1967) reported the record at Cape Prince of Wales and the possible further north distriCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 265–272

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SEKIGUCHI

Table 4.

Sighting summary from the T/S Oshoro Maru IPY surveys in summer 2007 and 2008.

Species

2007

2008

Total numbers of

Total numbers of

SchoolIndividuals

SchoolIndividuals

Bowhead whale
Humpback and like-humpback whale
Minke and like-minke whale
Gray and like-gray whale
Killer whale
Harbor porpoise
UnID large baleen whale
UnID large whale
UnID small whale
UnID whale
UnID dolphin
Dead whale

1
1
2
12
1
1
9
1
2
1
1
1

30
3
3
212
5
1
35
2
2
2
1
1

0
1
6
5
0
3
2
1
2
5
0
1

0
1
9
16
0
6
2
1
2
5
0
1

Total

33

297

26

43

Fig. 5.

270

Cetacean sighting positions by the T/S Oshoro Maru in summer 2007 and 2008.

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JAPANESE WHALE SIGHTING SURVEYS IN THE CHUKCHI SEA

Table 5. The summary of sighted whale species for each survey in the Chukchi Sea (present (✓) or absent (abs)).
Survey year

1937

1937

1958

2007

2008

Research vessel

Kaihou Maru

Yūki Maru

Fumi Maru

Oshoro Maru

Oshoro Maru

Bowhead/NP right whale
Blue whale
Fin whale
Humpback whale
Minke whale
Gray whale
Sperm whale

✓
✓
✓
✓
✓
abs.
✓

✓
abs.
✓
✓
abs.
abs.
✓

✓
abs.
✓
abs.
abs.
✓
abs.

✓
abs.
abs.
✓
✓
✓
abs.

abs.
abs.
abs.
✓
✓
✓
abs.

bution, but at present no other record of right whales in the Chukchi Sea has been found. The T/S Oshoro Maru 2007 survey encountered a school of bowhead whales oﬀ Point Hope, where R/V Kaihou
Maru and Fumi Maru No.16 sighted right whales. It is possible that they might have mistaken rightwhales for bowhead whales.
Gray whales have been known to be abundant in the Chukchi Sea for years (Nikulin, 1946; Berzin
and Rovnin, 1966; Tomilin, 1967; Berzin, 1984; Sekiguchi, 2015), however, no sightings were reported from the 1937 cruises (Table 5). This might be related to the migration period of gray whales, since
their cruise period was a bit earlier than those of the R/V Fumi Maru and T/S Oshoro Maru.
The two 1937 cruises had sightings of sperm whales (Tables 1, 2, and 5). There is no oﬃcial recordof sperm whales in the Chukchi Sea, although Berzin and Rovnin (1966) wrote about sighting reportsof this species. Sperm whale sightings could be due to a misidentiﬁcation, but it is hard to believe
whaling professionals made such a mistake for sperm whales. If there is an original cruise report for
the R/V Yūki Maru voyage, it may provide the answer.
To conclude, these old Japanese whale sighting survey data are important for investigating thechange in whale distribution in the Chukchi Sea over the years. It is necessary to look for the detailed
sighting data for the R/V Yūki Maru, which are missing from this study.
Acknowledgements

The author thanks all crews of T/S Oshoro Maru and research participants during the 2007 and 2008 IPY summer cruises
for their help. Professor Seiichi Saito, Hokkaido University, invited the author on the T/S Oshoro Maru cruises. Very special
acknowledgement goes to the late Dr. Seiji Ohsumi, the Institute of Cetacean Research, who brought the R/V Yūki Maru andother Japanese voyages to the Chukchi Sea to my attention. Without his deep knowledge of the history of Japanese whale
surveys, the author would never have noticed these important works as presented in this Short Note. Dr. John W. Menzies,
South Africa Astronomical Observatory, kindly checked the English. The comments of reviewers helped to improve thismanuscript.

References
Berzin, A. A. 1984. Soviet studies on the distribution and numbers of the gray whales in the Bering and Chukchi Seasfrom 1968 to 1982. pp. 409–419. In: Jones, M. L., Swartz, S. and Leatherwood, S. (eds.). The Gray Whale: Eschrichtius Robustus. Academic Press, Inc., San Diego. 600 pp.
Berzin, A.A. and Rovnin, A.A. 1966. The distribution and migrations of whales in the northeastern part of the Paciﬁc, Chukchi and Bering Seas. Izv. TINRO 58: 179–207.
Faculty of Fisheries Sciences, Graduate School of Fisheries Sciences, School of Fisheries Sciences, Hokkaido University.
2008. Data Record of Oceanographic Observations and Exploratory Fishing. No. 51. Hokkaido University, Hakodate.
218 pp.
Faculty of Fisheries Sciences, Graduate School of Fisheries Sciences, School of Fisheries Sciences, Hokkaido University.
2009. Data Record of Oceanographic Observations and Exploratory Fishing. No. 52. Hokkaido University, Hakodate.
235 pp. Available here: http://hdl.handle.net/2115/76719. (In Japanese).

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Nasu, K. 1960a. Hoppyouyou no chousa (Surveys in the North Sea). Geiken Tsuushin 104: 75–84. (In Japanese).
Nasu, K. 1960b. Oceanographic investigation in the Chukchi Sea during the summer of 1958. Sci. Rep. Whales Res. Inst. 15:
143–158.
Nikulin, P.G. 1946. On the distribution of cetaceans in the seas adjacent to the Chukchi Peninsula. Izv. TINRO 22.
Sekiguchi, K. 2015. Whales in the northern oceans—10-year surveys by T/S Oshoro Maru. pp. 163–179. In: Murayama, T.,
Suzuki, M. and Yoshioka, M. (eds.). The Second Dolphin and Whale Studies. Tokai University Press, Hatano. 201 pp.
(In Japanese).
Tatou, S. 1985. Chapter 3. Surveys and Data. pp. 108–117. In: Tatou, S. (ed.) Hogei no Rekishi to Shiryo (History and Statistics of Whaling). Suisansha, Tokyo. 202 pp. (In Japanese).
Tomilin, A.G. 1967. Mammals of the USSR and Adjacent Countries. Vol. IX. Cetacea. Israel Program for Scientiﬁc Translation, Jerusalem. 717 pp.
Yamaguchi, Y. 1961. Kaihou Maru ni yoru hoppyouyou chousa (The North Sea survey by R/V Kaihou Maru). Geiken Tsushin
123: 209–212. (In Japanese).

Received: January 31, 2021
Accepted: April 28, 2021
Published online: December 8, 2021

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J-STAGE Advance published date: December 2, 2021

DORSAL FIN SHAPE OF PACIFIC WHITE-SIDED DOLPHINSSEXUAL DIMORPHISM IN
THE DORSAL FIN OF PACIFIC WHITE-SIDEDDOLPHINS (LAGENORHYNCHUS OBLIQUIDENS)FROM COASTAL WATERS OFF JAPAN
Etsuko KATSUMATA*, Saeko NARUSE, Toru HOSONO andHiroshi KATSUMATA
Kamogawa Sea World, 1464–18 Higashicho, Kamogawa-shi, Chiba 296–0041, Japan*Corresponding author: etsuko_katsumata@granvista.co.jp

Abstract
Records of external measurements of 35 male and 40 female Paciﬁc white-sided dolphins
collected from 1970 to 2020 were examined for the shape change of the dorsal ﬁn and the difference between males and females. For mature individuals based on a body length of 200 cm,
which is an approximate guideline for maturity, a signiﬁcant diﬀerence was detected in theratios of the front edge length and the tip height which were 3.8 on average with a maximum
value of 5.6 in males, and 2.8 (average) and 3.1 (maximum value) in females, respectively. It
was concluded that sexually mature males could be distinguished by measuring the shape ofthe dorsal ﬁn.
Key words:

allometry, dorsal ﬁn, growth, morphology, Paciﬁc white-sided dolphin.

The Paciﬁc white-sided dolphin (Lagenorhynchus obliquidens) is an endemic species of the North
Paciﬁc Ocean, and even a mature individual is relatively small, with a body length of 2.5 m or less.
Length at birth is reported to be about 80–95 cm. The distribution area on the western side of the
Paciﬁc Ocean is along the Sea of Japan and the Paciﬁc coast of Japan on the western Paciﬁc Ocean(Leatherwood and Reeves, 1982, Brownell et al., 1999). Hayano et al. (2004) identiﬁed a distribution
gap around the longitude of 150°E or between Japanese coastal waters and the oﬀshore western andcentral North Paciﬁc, and concluded that samples from these two geographical areas came from diﬀerent populations. The authors suggested that the low genetic diﬀerence could be due to the short timesince reproductive isolation between the two geographical populations oﬀ Japan. The origin of theJapanese name “Kama-iruka” is that the dorsal ﬁn resembles a “sickle” (Kasuya, 2017).
Regarding individual identiﬁcation of dolphins and whales, the dorsal ﬁn is one of the most obvious traits to consider whether in the wild or in captivity. The dorsal ﬁn shape, size, color, scratches,and cuts are used to identify an individual. Killer whales (Orcinus orca) are known as an example
where individual identiﬁcation and identiﬁcation by sex and maturity status is possible by observing
the dorsal ﬁn. The male dorsal ﬁn (height to width ratio) could be readily distinguished from that ofa female, and a height to width ratio of 1.4 or greater was indicative of a mature male (Olesiuk et al.,1990, 2005).
In the case of the Paciﬁc white-sided dolphin dorsal ﬁn morphology, it has been found that sexuallymature males have a pronouncedly curved and round dorsal ﬁn (Walker et al., 1986). Furthermore,Kasuya and Yoshida (1990) and Kasuya (2017) clariﬁed that the tip of the dorsal ﬁn hangs down inmature males from the point of measurement of the height of the tip of the dorsal ﬁn and the overall
height. Attempts have been made to identify sexually mature males from photographs of the dorsal
ﬁns of wild Paciﬁc white-sided dolphin herds using this method (Morton, 2006). However, there are
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KATSUMATA E., NARUSE, HOSONO AND KATSUMATA H.

no studies that have examined the body length and dorsal ﬁn measurements of this species in comparison with the sex.
In this study, we investigated changes in dorsal ﬁn shape and curvature using proportion measurements of Paciﬁc white-sided dolphins collected in the waters of both the Paciﬁc Ocean side and the
Sea of Japan side of Honshu, Japan, over the past 50 years from 1970 to 2020. The purpose of thisstudy was to clarify the diﬀerence in dorsal ﬁn shape between males and females with changes inbody length, and to contribute to the biological database of Paciﬁc white-sided dolphins.
The measurements used in this study are shown in Fig. 1. The proportion measurement records of
35 males and 40 females were used. These measurement records include post-mortem measurements(bycatch or after death in captivity) and live individuals’ latest measurements data at Kamogawa Sea
World (KSW). It is a characteristic of Paciﬁc white-sided dolphins distributed in the coastal watersof Japan that individual diﬀerences in body length are large in all age ranges. The range shared bysexually mature and immature individuals was 180–234 cm for males and 195–209 cm for females(Kasuya, 2017). From this, the guideline for sexually mature body length was roughly set to 200 cm inthis paper.
The following allometric equation was used to extract growth patterns at each point:y = βxα
where x deﬁnes the body length; y, the length (cm) of the measurement points; α, the allometric coeﬃcient; and β is a constant. The t-test was conducted using allometric coeﬃcients to reveal growth
patterns at each measurement point, and the data were grouped into three diﬀerent growth patterns:
positive allometry (hyperallometry) when the allometric coeﬃcient was signiﬁcantly greater than 1,
isometric allometry and negative allometry (hypoallometry) when the allometric coeﬃcient was lessthan 1. These statistical analyses were conducted by using the packaged tools in the statistical software R (R Core Team, 2021). Fig. 2 shows the obtained body length plotted against each measurement point of dorsal ﬁns for males and females. The body length (measurement point No. 1, Fig. 1)
ranged from 71 cm (fetus) to 231 cm for males and 70.5 cm (fetus) to 225 cm for females. As the bodylength increased, each measured value also increased, and the slope of the graph increased. For differences between males and females in each graph, the length of dorsal ﬁn base (measurement point
No. 2, Fig. 1) diﬀered between males and females. The maximum value was 49.0 cm for males and41.0 cm for females. However, the height of the dorsal ﬁn tip (measurement No. 3) was conspicuously
narrower in individuals of body length 200 cm or more for both males and females (Fig. 2). In otherwords, the tip of the dorsal ﬁn tended to hang down as individuals sexually matured in both males andFig. 1. External measurement points of Paciﬁc white-sided dolphin used in the present study: No. 1, from thetip of the upper jaw to notch in the tail ﬂuke (body length); No. 2, length of dorsal ﬁn base; No. 3, height of
dorsal ﬁn tip; No. 4, length from the front edge to ﬁn tip and No. 5, length from ﬁn tip to trailing edge.

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DORSAL FIN SHAPE OF PACIFIC WHITE-SIDED DOLPHINS

Fig. 2. Relative growth of measured points in dorsal ﬁn and body length of the Paciﬁc white-sided dolphin.
Closed circles (left) represent males and open circles (right) represent females, respectively. The dotted line
indicates the approximate body length of a sexually mature (200 cm) individual.
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KATSUMATA E., NARUSE, HOSONO AND KATSUMATA H.

females. The front edge length (measurement point No. 4, Fig. 1) was also diﬀerent between males
and females. For individuals with a body length over 200 cm, dorsal ﬁns grew longer in males than infemales. The maximum value was 59.4 cm for males and 47.5 cm for females. The dorsal ﬁn trailingedge length (measurement point No. 5) values varied widely for both males and females. This may be
due to the variety of trailing edge shapes. The maximum value was 39.0 cm for males and 29.6 cm forfemales.
Table 1. Allometry of the length of dorsal ﬁn measurement points and body length of Paciﬁc white-sided dolphin males and females.
Male

Measurement points

α

β

R2

Growth patternP-value

No. 2
No. 3
No. 4
No. 5

Length of dorsal ﬁn base
Tip height
Front edge length
Trailing edge length

1.06
0.63
1.09
0.87

0.14
0.56
0.15
0.25

0.96
0.50
0.93
0.72

isometric allometry
negative allometry
isometric allometry
isometric allometry

0.135
0.003**
0.097
0.204

FemaleMeasurement points

α

β

R2

Growth patternP-value

No. 2
No. 3
No. 4
No. 5

Length of dorsal ﬁn base
Tip height
Front edge length
Trailing edge length

1.01
0.45
0.92
0.66

0.16
1.55
0.32
0.72

0.93
0.32
0.91
0.47

isometric allometry
negative allometry
isometric allometry
negative allometry

0.782
0.000**
0.137
0.010**** indicates a statistically signiﬁcant diﬀerence (p<0.01) between sexes in the length of dorsal ﬁn measurement points
and body length (see also Fig. 2).

Fig. 3. Paciﬁc white-sided dolphin dorsal ﬁn growth-related ratio change No. 4/No. 3 shows front edge length
to tip height ratio and No. 5/No. 3 shows trailing edge length to tip height ratio. Closed circles (left) represent
males and open circles (right) represent females, respectively. The dotted line indicates the approximate bodylength of a sexually mature (200 cm) individual.

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Table 1 shows the values applied to the relative growth curve (relationship between the length of
dorsal ﬁn measurement points and body length) for males and females. Tip height in males, and tipheight and front edge length in females showed negative allometry.
Fig. 3 shows front edge length to tip height (No. 4/No. 3) and trailing edge length to tip height (No.
5/No. 3) ratios by body length for males and females. The ratio rises sharply after a body length of
200 cm in males, while on the other hand such a change is not observed in females.
Fig. 4 shows the front edge length to tip height (No. 4/No. 3) and the trailing edge length to tipheight (No. 5/No. 3) ratios of individuals over 200 cm in body length. The ratios of front edge length
to tip height were signiﬁcantly higher in males (3.8±0.2, mean±SE, n=12) than in females (2.8±0.1,n=10) (t-test, p<0.01). No signiﬁcant diﬀerence was found in the trailing edge length to tip heightratios.
This study found that the dorsal ﬁns of Paciﬁc white-sided dolphins inhabiting the coastal waters ofJapan diﬀer in shape and size between males and females. Especially in length of dorsal ﬁn base (measurement point No. 2) and front edge length (measurement point No. 4), males clearly grew more thanfemales. When the ratio of dorsal ﬁn was examined using these measurements (Fig. 1), a signiﬁcantdiﬀerence was found in the front edge length to tip height ratio (No. 4/No. 3). This diﬀerence in the
shape of the dorsal ﬁns of males and females was eﬀective for individual identiﬁcation of wild Paciﬁcwhite-sided dolphins and identiﬁcation of sexually mature males. Suzuki et al. (2020) suggested that
there are at least two forms on the coastal waters of Japan, and from the result of genetic structural
analysis of 64 Paciﬁc white-sided dolphins kept at aquariums in Japan, they concluded that in the Japanese coastal waters, genetic exchange between populations with diﬀerent genetic backgrounds seems

Fig. 4. Comparison of the dorsal ﬁn ratios between mature males and females. No. 4/No. 3 shows front edge
length to tip height and No. 5/No. 3 shows trailing edge length to tip height. The vertical black bars indicate
the average error and * indicates a statistically signiﬁcant diﬀerence (p<0.01) between sexes.
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KATSUMATA E., NARUSE, HOSONO AND KATSUMATA H.

to occur in the wild. In the future, it is hoped that diﬀerences in body length and external morphology
between individuals of the forms identiﬁed by genetic structural analysis will be investigated.
As a conclusion, we compared the measured values of the dorsal ﬁn for the Paciﬁc white-sided dolphin using records from the coastal waters of Japan. It was shown that the ratio of the dorsal ﬁn canbe used to identify sexually mature males. Their dorsal ﬁn (front edge length to tip height ratio) could
be readily distinguished from that of females, and a ratio of 3.8 or greater was indicative of a sexuallymature male.
Acknowledgements

We would like to express our deep gratitude to all the staﬀ who have been involved in the continuous care of dolphins,
and the measurement of proportions and the storage of records for over 50 years at Kamogawa Sea World. We would like tothank Masayuki Muramatsu and Naoko Suhara for their cooperation in preparing the ﬁgures and the signiﬁcance test. Finally,
we deeply appreciate the anonymous reviewers for their helpful suggestions.

References
Brownell, R.L. Jr., Walker, W. and Forney, K.A. 1999. Paciﬁc white-sided dolphin, Lagenorhynchus obliquidens. pp. 57–84.
In Ridgway S. H. and Harrison, R. (eds.). Handbook of Marine Mammals. Vol. 6: The Second Book of Dolphins and the
Porpoises. Academic press, San Diego. 486 pp.
Hayano, A., Yoshioka, M., Tanaka, M., and Amano, M. 2004. Population diﬀerentiation in the Paciﬁc white-sided dolphin
Lagenorhynchus obliquidens inferred from mitochondrial DNA and microsatellite analyses. Zool. Sci. 21(9): 989–999.
doi: 10.2108/zsj.21.989.
Kasuya, T. 2017. Paciﬁc white-sided dolphin. pp. 437–443. In: Kasuya, T. and Perrin, W.F. (eds.). Small Cetaceans of Japan:
Exploitation and Biology. CRC Press, New York. 475 pp.
Kasuya, T. and Yoshida, S. 1990. Secondary sexual characteristics of the Paciﬁc white-sided dolphin. Abstracts of the Spring
Meeting of the Japanese Society of Scientiﬁc Fisheries, Tokyo, Japan, 2–5 April 1990.
Leatherwood, S. and Reeves, R.R. 1982. Paciﬁc White-sided Dolphin pp. 204–207. In: The Sierra Club Handbook of Whales
and Dolphins. The Sierra Club Books, San Francisco. 302 pp.
Morton, A. 2006. Occurrence, photo-identiﬁcation and prey of Paciﬁc white-sided dolphins (Lagenorhynchus obliquidens) inthe Broughton Archipelago, Canada 1984–1998. Mar. Mam. Sci. 16: 80–93. doi: 10.1111/j.1748-7692.2000.tb00905.x.
Olesiuk, P.F., Bigg, M. A. and Ellis, G.M. 1990. Life history and population dynamics of resident killer whales (Orcinusorca) in the coastal waters of British Columbia and Washington State. Rep. int. Whal. Comm. (Special issue) 12:
209–242.
Olesiuk, P.F., Ellis, G.M. and Ford, J.K.B. 2005. Life History and Population Dynamics of Northern Resident Killer
Whales (Orcinus orca) in British Columbia. Canadian Science Advisory Secretariat, Fisheries & Oceans, Canada.
Research document 2005/045, 75 pp.
R Core Team 2021. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing,
Vienna.
Suzuki, M., Morinaga, M., Sawayama, E., Matsumoto, T. and Kato, H. 2020. Preliminary analysis of the genetic population
structure of Paciﬁc white-sided dolphins kept in Japan. Abst. Spring Meeting of the Japanese Society of Fisheries Science. p. 56 (in Japanese).
Walker, W.A., Leatherwood, S., Goodrich, K.R., Perrin, W.F. and Stroud, R.K. 1986. Geographical variation and biology of
the Paciﬁc white-sided dolphin, Lagenorhynchus obliquidens. pp. 441–465. In: Bryden, M.M. and Harrison, R. (eds.).
Research on Dolphins. Oxford Science Publications, Oxford. 478 pp.

Received: January 21, 2021
Accepted: August 19, 2021
Published online: December 2, 2021

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Appendix
Dorsal ﬁn shape photos; ID, sex, sexual status, body length.
The photos are shown based on body length left to right, from top to bottom by male (this page) andfemale (next page). The individuals in the photos have been kept at KSW and conﬁrmed to be matureand immature by reproductive history, sex hormones, and semen collection in the case of males.

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Appendix (Continued.)280

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J-STAGE Advance published date: October 20, 2021

MINKE WHALE MUSCLE COMPOSITION ASSESSMENT BY NIR SPECTROSCOPYPRELIMINARY USE OF NEAR-INFRARED
SPECTROSCOPY TO ESTIMATE THE BIOCHEMICALCOMPONENTS OF THE MUSCLESOF THE ANTARCTIC MINKE WHALE
BALAENOPTERA BONAERENSIS
Kenji KONISHI* and Tsutomu TAMURA
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Corresponding author: konishi@cetacean.jp

Abstract
The energetic condition of whales is an important information to understand their energy
demand to sustain their migration and reproductive success. However, basic energetic information based on biochemical components (protein, lipid, sugar, and water) and calorimetricdata are limited, particularly in small baleen whales such as the minke whale. This study
reports the biochemical components of the muscle tissues of 61 Antarctic minke whales (Balaenoptera bonaerensis) of diﬀerent sexes and sexual maturity using near-infrared (NIR) spectroscopy. Prior to sample analysis, a calibration curve based on a standard chemical analysis
was installed in the NIR analytical equipment. The dorsal muscle tissues from Antarctic minke
whales contain approximately 0.5%–0.6% lipid, 26% protein, and 73% water, suggesting thatthe dorsal muscle contains a small amount of lipid and a high proportion of water. These proportions were similar between sexes and sexual classes. The proportions of lipids in the dorsal
muscle of Antarctic minke whales are likely to be lower than those of other baleen whales,such as sei (B. borealis) and ﬁn (B. physalus) whales, and this requires further investigation.
Key words:

lipid contents, nutritional condition, muscle tissue, Antarctic minke whale.

The information about the nutritional indices of baleen whales is important to evaluate their energetic conditions and energy demand to sustain their migration and reproductive success. The information on their biochemical components, such as protein, lipid, sugar, and water, and calorimetricdata are necessary to estimate the total energy deposit of individuals and evaluate their nutritional
indices. The biochemical components of large whales, such as ﬁn (Balaenoptera physalus) and sei(B. borealis) whales, were previously reported (Arai and Sakai, 1952; Lockyer et al., 1984, 1985;
Aguilar and Borrell, 1990).
This biochemical composition diﬀers among whale species, and it also varies with the season,
body size, reproductive status, and organs (Lockyer et al., 1984, 1985; Aguilar and Borrell, 1990).
Therefore, species-speciﬁc biochemical information is needed to estimate their energy deposits using
tissues that function as a lipid deposit. However, little information is available for Antarctic minke
whales (B. bonaerensis). The biochemical components and lipid contents of Antarctic minke whales
were previously reported from the aspect of food nutrition (Ito et al., 1993, 1998; Iida et al., 1998).
The biochemical components of the “red meat” from three Antarctic minke whales (a mature male, animmature female, and a >30-year-old female) were reported by Iida et al. (1998). The lipid contentsof the dorsal muscle at the level of the dorsal ﬁn (regarded as red meat) and tail (regarded as lipid-rich“tail meat”) were examined in 29 males and 23 females (Ito et al., 1998). Although fat tissue suchas blubber function as lipid deposit, muscle mass represents a greater proportion in terms of weight
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KONISHI AND TAMURA

Fig. 1. Near-infrared spectrometer CA-HM (Joy World Paciﬁc Co. ltd.) and a terminal PC. The solid muscle
samples were homogenized using a food processor and a portion the (approximately 25 g) was set for analysis
on a saucer at the lower right slot.

(Gunnlaugsson et al., 2020). Therefore, it is important to determine the biochemical components of
their muscle tissues to calculate the total energy contents and their function for energy storage.
In this study, near-infrared (NIR) spectroscopy was used to determine the biochemical componentsof the muscle tissues of Antarctic minke whales. While conventional methods analyze the samples
only for a single component, NIR spectroscopy allows simultaneous measurements of multiple biochemical components, optimizing the use of samples. However, this NIR technique needs a calibration
based on a regression model to predict the biochemical properties based on spectral data (Prieto etal., 2017).
The NIR technique was used to estimate the biochemical components of the muscle tissues from61 Antarctic minke whales sampled during the austral summer of 2016/17 under NEWREP-A (NewScientiﬁc Whale Research Program in the Antarctic Ocean). Muscle tissues were sampled from thedorsolateral muscle at the level of the dorsal ﬁn. To reduce the seasonal eﬀect on the analyses of thebiochemical components during the summer feeding period, the samples from a limited time period in
the survey season were used (December 15–January 5). The samples involved 25 immature males, 14
mature males, 17 immature females, and ﬁve pregnant females.
The muscle samples were scanned using an NIR spectrometer, CA-HM (Joy World Paciﬁc Co.,
Ltd.; Fig. 1). Before the analysis, a calibration curve set for whale muscles was prepared (Fig. 2). Thisﬁgure shows the plots of the values of protein, lipid, and water components from conventional chemical analyses and NIR spectroscopy. The muscle tissues from Antarctic minke whales and North Paciﬁc
sei whales were used for this calibration. This calibration curve was ﬁt using these values and installedin the spectrometer.
The muscle samples were homogenized using a food processor, and a sub-sample (approximately
25 g) was set on a saucer dedicated for NIR spectroscopy (Fig. 3). In both conventional chemical analyses and NIR spectroscopy, the white ﬁbrous parts, such as perimysium, were not removed from themuscle sample since these are muscle components. However, the results were expected to vary slightly by homogenizing the muscle samples.
The summary of the NIR analysis of the dorsal muscle at the level of the dorsal ﬁn of Antarctic

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MINKE WHALE MUSCLE COMPOSITION ASSESSMENT BY NIR SPECTROSCOPY

Fig. 2. Comparisons of biochemical components between laboratory-based and near-infrared (NIR) analyses
to set a standard curve of the whale muscles for NIR spectroscopy. Left, protein; center, lipid; right, water.
The muscle samples from Antarctic minke and North Paciﬁc sei whales were used. The gray bands represent
the 95% conﬁdence intervals.

Fig. 3. Homogenized muscle of an Antarctic minke whale set on a saucer before analysis on the near-infrared
spectrometer. The white ﬁbrous parts were included in the analysis.

minke whales is listed in Table 1. On average, the muscle tissues contain approximately 0.5%–0.6%
lipid, 26% protein, and 73% water, showing that the muscle consists of a very small amount of lipid
and a high percentage of water in all maturity stages. The lipid compositions are similar among sexes
and sexual maturity/classes. The results of Iida et al. (1998) are similar to the results of this study (Table 1). Ito et al. (1998) also showed that the lipid content of the dorsal muscle at the level of the dorsal
ﬁn was approximately 1.1% in Antarctic minke whales sampled in the austral summer of 1990/91 (Table 1). This lipid content in muscle tissues was slightly higher compared to the results of the present
study. However, the energy storage diﬀers among years and seasons (Konishi et al., 2008; Konishi andCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 281–285

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284

107.05
25.58
0.48
0.10
72.84
—
3.41

Calorie (kcal)
106.03
3.54
Protein (g)
25.08
0.45
Lipid (g)0.59
0.22
Sugar (g)0.10
0.00
Water (g)
73.23
0.63
Ash
—
—
Lateral blubber thickness at
3.33
0.61
the level of dorsal ﬁn (cm)Half girth at the level of
163.28 18.27
umbilicus (cm)Sample size
25
14

212.00

mean

SD

mean

10.70

6.22
0.82
0.37
0.00
1.13
—
0.44

SD

Mature male

Immature male

2.28
0.35
0.15
0.00
0.43
—
0.47

SD

17

166.29 19.14

104.18
24.82
0.50
0.10
73.58
—
3.22

mean

214.20107.61
25.45
0.60
0.10
72.85
—
3.10

mean

5

9.91

3.33
0.47
0.17
0.00
0.63
—
0.66

SD

Immature female Pregnant female

1

—

—
24.10
0.70
0.15
74.40
0.92
—

1

—

—
24.00
0.30
0.36
74.60
1.65
—

1

—

—
24.40
0.36
0.14
74.50
0.90
—

Mature Immature Maturemale
female female

Iida et al. (1998)

—

—
—
1.14
—
—
—
—

Male

29

—

—
—
0.57
—
—
—
—

SD

—

—
—
1.11
—
—
—
—

23

FemaleIto et al. (1998)

—

—
—
0.5
—
—
—
—

SD

Table 1. Summary of the calorie content and biochemical components (per 100 g) of the muscles of Antarctic minke whales. For comparative purposes, the data fromthe results of Iida et al. (1998) and Ito et al. (1998) based on conventional analyses are also indicated.

KONISHI AND TAMURA

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MINKE WHALE MUSCLE COMPOSITION ASSESSMENT BY NIR SPECTROSCOPY

Walløe, 2015), and this diﬀerence may suggest a possible seasonal and yearly variation of lipid contents in the muscles of Antarctic minke whales.
The lipid contents of the dorsal muscles of ﬁn and sei whales exceeded 3% on average. The musclesin the anterior body part at the level of the ﬂippers have less accumulated lipids compared to those in
the middle and posterior parts of the body (Lockyer et al., 1985). Given this, the muscles of Antarctic
minke whales seem to have less lipid contents than those of large baleen whales. However, to conﬁrm
this, further comparative analyses among baleen whale species should be conducted using the same
methodology while strictly considering the body parts from where the muscle samples are obtained.
The application of NIR spectroscopy to estimate the biochemical components of whale tissues isuseful and practical to determine the basic information about the energetics of baleen whales. The useof techniques, such as NIR, which allows analysis of multiple components from a single sample, is ofparticular utility in the case of baleen whale samples, which are limited and diﬃcult to access.
Acknowledgements

We are most grateful to the researchers on board of Nisshin-Maru for their assistance in biological sampling during the
2016/17 NEWREP-A survey. We also would like to thank two anonymous reviewers for their useful comments to improve
this paper. The NEWREP-A program was conducted with permission from the Fisheries Agency, Government of Japan.

References
Aguilar, A. and Borrell, A. 1990. Patterns of lipid content and stratiﬁcation in the blubber of ﬁn whales (Balaenoptera physalus). J. Mammal. 71: 544–554. doi: 10.2307/1381793.
Arai, Y. and Sakai, S. 1952. Whale meat in nutrition. Sci. Rep. Whales Res. Inst. 7: 51–67.
Gunnlaugsson, T., Víkingsson, G. A., Halldórsson, S. D., Elvarsson, B., Haug, T. and Lydersen, C. 2020. Body mass, muscle,
blubber and visceral fat content and their seasonal, spatial and temporal variability in North Atlantic common minke
whales. J. Cetacean Res. Manage. 21: 59–70.
Iida, H., Murata, Y., Matsumoto, G., Toda, S., Yamashita, Y. and Yokoyama, M. 1998. Chemical composition of the edible
parts of minke whale Balaenoptera acutorostrata. Bull. Natl. Res. Inst. Fish. Sci. 11: 27–36. (In Japanese).
Ito, S., Takenaga, F. and Tsuyuki, H. 1993. Studies on lipids of the minke whale. II The fatty acid compositions of the blubber oils of minke whale and dwarf minke whale caught on 1988/89 and1989/90 seasons. J. Japan Oil Chemist’s Soc.
42: 1007–1011. (In Japanese).
Ito, S., Takenaga, F. and Tsuyuki, H. 1998. Lipids in Antarctic minke whales. III Site and sexual diﬀerences of muscle lipids.
J. Japan Oil Chemist’s Soc. 47: 191–194. (In Japanese).
Konishi, K., Tamura, T., Zenitani, R., Bando, T., Kato, H. and Walløe, L. 2008. Decline in energy storage in the Antarctic
minke whale (Balaenoptera bonaerensis) in the Southern Ocean. Polar Biol. 31: 1509–1520. doi: 10.1007/s00300-0080491-3.
Konishi, K. and Walløe, L. 2015. Substantial decline in energy storage and stomach fullness in Antarctic minke whales(Balaenoptera bonaerensis) during the 1990s. J. Cetacean Res. Manage. 15: 77–92.
Lockyer, C., McConnell, L. and Waters, T. 1984. The biochemical composition of ﬁn whale blubber. Can. J. Zool. 62: 2553–
2562. doi: 10.1139/z84-373.
Lockyer, C., McConnell, L. and Waters, T. 1985. Body condition in terms of anatomical and biochemical assessment of body
fat in North Atlantic ﬁn and sei whales. Can. J. Zool. 63: 2328–2338. doi: 10.1139/z85-345.
Prieto, N., Pawluczyk, O., Dugan, M. E. R. and Aalhus, J. L. 2017. A review of the principles and applications ofnear-infrared spectroscopy to characterize meat, fat, and meat products. Appl. Spectrosc. 71: 1403–1426. doi:
10.1177/0003702817709299.

Received: January 28, 2021
Accepted: June 30, 2021
Published online: October 20, 2021

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285

J-STAGE Advance published date: December 8, 2021

ISODA, TAMURA AND PASTENEINGESTION OF MARINE DEBRIS AND EVIDENCE OFENTANGLEMENTS INVOLVING ANTARCTIC MINKEWHALES (BALAENOPTERA BONAERENSIS) SAMPLED
IN THE INDO-PACIFIC SECTOR OF THE ANTARCTIC
Tatsuya ISODA1*, Tsutomu TAMURA1 and Luis A. PASTENE1, 2
2

1
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
Project Microbiomes as Bioindicators of the Aquatic Ecosystem Health in Chilean Patagonia, Centro deEstudios del Cuaternario de Fuego-Patagonia y Antártica (CEQUA), Punta Arenas, Chile*Corresponding author: isoda@cetacean.jp

Abstract
This study presents the results of an examination of marine macro debris ingested by Antarctic minke whales (Balaenoptera bonaerensis) in the Indo-Paciﬁc sector of the Antarctic in
the period 1987/88–2018/19. Whales used in this study were sampled by surveys of the former
Japanese whale research programs under special permit in the Antarctic. Also, this study examines evidence of past and present entanglements around the body of the animals. Of a totalof 11,992 whales examined, 19 had ingested macro debris (0.16%) such as polymer products
and wood. Only four cases of entanglements were recorded in the 11,992 whales examined(0.03%). Of 5,215 whales examined from the period of 2005/06 onward, six whales presented
body marks associated with past entanglements (0.12%). It was concluded that the frequency
of macro debris ingested as well as the number of entanglement cases involving Antarctic minke whales sampled in the Indo-Paciﬁc sector of the Antarctic are extremely low in comparison
with whales in the North Atlantic. These low frequencies of ingested debris and entanglements
are unlikely to have a negative eﬀect on the conservation of the Antarctic minke whale populations in this sector of the Antarctic.
Key words:

Antarctic, Antarctic minke whale, marine macro debris, ingestion, entanglements.

Marine debris is a kind of pollutant aﬀecting marine wildlife. Among the marine debris types,
plastics have a more negative impact on marine wildlife than others. Plastics include microplastic
particles (with a diameter <5 mm, Arthur et al., 2009) and macroplastic particles (>20 mm, Barnes
et al., 2009). Such marine debris could cause disease or be ingested and lead to starvation (Gregory, 2009). Recently, two workshops (Panti et al., 2019; IWC, 2020) were held to discuss the current
status of the interaction between marine debris and marine mammals. The objectives of the workshops
were to identify negative eﬀects on the animals; to identify possible areas of research to assess the impact of marine debris on this group of animals; and to propose ways to alleviate the problem. So far,detection of debris interactions in cetaceans has largely depended on data collected from small sample
sizes provided by stranded animals. Therefore it has been diﬃcult to determine the implications of debris interactions at a population level (Baulch and Perry, 2014).
The present study focuses on the Antarctic, one of the most isolated places on earth where the eﬀectof human activities and the occurrence of marine debris are assumed to be limited (see also Isoda etal., this issue). There is limited information regarding interaction between marine debris and whalesin the Antarctic. This study investigates the occurrence of marine macro debris ingested by Antarctic
minke whales (Balaenoptera bonaerensis) based on whales sampled over a period of more than 30
years in the Indo-Paciﬁc sector of the Antarctic by surveys of the former JARPA/JARPAII (Japanese

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MARINE DEBRIS AND EVIDENCE OF ENTANGLEMENTS OF ANTARCTIC MINKE WHALES

Table 1. Number of macro debris ingested by Antarctic minke whales and frequencies (number of whales
with debris ingestion per 100 Antarctic minke whales) in the Indo-Paciﬁc sector of the Antarctic in the australsummer seasons 1987/88–2018/19 (JARPA, JARPAII and NEWREP-A). In parentheses are the numbers ofmarine debris found in the forestomach and main stomach when only those two compartments were examinedin the 2005/06–2013/14 seasons (JARPAII).

* All items found in stomach and duodenal ampulla except one polymer product found in the anus of one whale. Category‘others’ includes one small black piece of carbonized object (research season: 2002/03) and one small rubber piece (research season: 2003/04).

Research Program under Special Permit in the Antarctic, Phases I and II) and NEWREP-A (NewScientiﬁc Whale Research Program in the Antarctic Ocean). The Antarctic minke whale is a smallbaleen whale species, which migrates between low latitude winter breeding grounds and high latitude
summer feeding grounds in the Antarctic where it is widely distributed (Kasamatsu et al., 1995). The
species feed mainly on Antarctic krill (Euphausia superba) but also on ice krill (E. crystallorophias)
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Fig. 1. A piece of polymer product found in the stomach of an Antarctic minke whale sampled during the
2002/03 austral summer season at position 76°S; 175°E (IWC Area V; CCAMLR sub-area 88.1).
Table 2. Ingestion of macro debris by Antarctic minke whales by sex and sexual maturity in the Indo-Paciﬁc
sector of the Antarctic in the austral summer seasons 1987/88–2018/19 (JARPA, JARPAII and NEWREP-A).
In parentheses are the sample sizes examined by sex and sexual maturity.

* Includes one male and one female of unknown sexual maturity status.

in some areas of the Antarctic (Ichii and Kato, 1991; Tamura and Konishi, 2009). It has been assumed
that these whales ingested debris mixed in with food during the austral summer feeding period in the
Antarctic waters.
This study also examines the body surface of the whales to identify entanglements, i.e., objects
attached to the body (from the period of JARPA, JARPAII and NEWREP-A) or evidence from scars
and marks of past entanglement events (from the period of JARPAII and NEWREP-A when more detailed photographic records were available). This is a unique study because it examines ingestion andentanglements in the Antarctic minke whale based on a series of surveys conducted over 31 years, and
it is the ﬁrst study to provide a summary of information regarding interaction between marine macrodebris and whales in the Antarctic.
The surveys were conducted during the austral summer seasons from 1987/88 to 2018/19. Table
1 shows the details of the survey years and the number of samples for each year. The research area
comprised the Indo-Paciﬁc sector of the Antarctic, speciﬁcally the International Whaling Commission(IWC) Antarctic Management Areas III East (IIIE) (35°–70°E), IV (70°–130°E), V (130°E–170°W)
and VI West (VIW) (170°–145°W), south of 60°S (JARPA and NEWREP-A) and south of 62°S (JAR-

288

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MARINE DEBRIS AND EVIDENCE OF ENTANGLEMENTS OF ANTARCTIC MINKE WHALES

Fig. 2. Size of marine debris ingested by Antarctic minke whales in the Indo-Paciﬁc sector of the Antarctic(1987/88–2004/05). The sample size of debris in this ﬁgure is diﬀerent from that in Table 1 (no size information was available for two polymer products and three wood pieces).

PAII). These areas overlap partially with the Convention Areas of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR): Area IIIE with Divisions 58.4.2–4, Area IVwith Divisions 58.4.1–3, Area V with Division 58.4.1 and sub-area 88.1, and Area VIW with sub-area
88.2.
In order to obtain samples representative of the populations, Antarctic minke whales were sampled
randomly on predetermined track-lines (Nishiwaki et al., 2006; Nishiwaki et al., 2014). Sampledwhales were examined onboard of the research base vessel where several biological measurements
and samples were collected. Body length was measured to the nearest 1 cm from the tip of snout to thedeepest part of the notch of the ﬂukes along a straight line parallel to the body axis. Body weight was
obtained using a large weighing scale installed on the ﬂensing deck. Sex of the whales was determinedby researchers on board. Sexual maturity in females was determined by the presence of at least one
corpus luteum or albicans in the ovaries and for males a single testis weight of 400 g or more was used
as a criterion (Kato, 1982).
The stomachs of 11,992 Antarctic minke whales were examined. Examination of macro debris was
conducted during the routine analysis of stomach contents following established protocols (Tamura
and Konishi, 2009). The three stomach chambers and the duodenal ampulla were examined macroscopically during the period 1987/88–2004/05 (JARPA) and 2015/16–2018/19 (NEWREP-A). Only
the fore and main stomachs were examined during the period 2005/06–2013/14 (JARPAII). Macro debris and objects other than preys were recorded. The sizes of solid objects were estimated from scaled
photographic records.
Out of the 11,992 Antarctic minke whales examined, a total of 19 whales had ingested macro debris(Table 1). None of the whales had multiple marine debris in their stomachs. Fig. 1 shows an example
of marine debris (polymer product) found in the stomach of an Antarctic minke whale. There werenine cases of polymer product ingestion and eight cases of wood ingestion. Macro debris ingestion
was not observed after the 2005/06 season and there was no temporal increasing trend over the reCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 286–294

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ISODA, TAMURA AND PASTENE

Table 3. List of entanglement cases in the Antarctic minke whales in the Indo-Paciﬁc sector of the Antarctic in
the austral summer seasons 1987/88–2018/19 (JARPA, JARPAII and NEWREP-A) (see Fig. 3).

Fig. 3. Four cases of entanglement in the Antarctic minke whales in the Indo-Paciﬁc sector of the Antarctic in the austral summer seasons 1987/88–2018/19 (JARPA, JARPAII and NEWREP-A). a: ﬁshing hook;b: monoﬁlament ﬁshing line; c: rope; d: packing band (the band was lost when the whale was transported to
the research base vessel).

search period. The frequency of stomachs with debris per 100 Antarctic minke whales examined wasvery low (0.16%) and the frequency of polymer products was 0.08%. Around 68.4% of all macro debris was ingested by mature males (Table 2). Most macro debris (75.0%) was less than 100 mm in size
(Fig. 2). There were three debris, one polymer bag and two small wood pieces with sizes of more than
100×100 mm. Apart from debris, stones were found in six whales (in six austral seasons) and feathers
in 37 whales (in thirteen austral seasons).
The frequency of ingested debris per 100 Antarctic minke whales was very low in comparison withdebris found in whales from the North Atlantic. For example, six of 82 Icelandic ﬁn whales (B. physalus) examined had debris in their stomachs while on the eastern coast of the United States, three of
19 mysticetes examined contained synthetic objects in their gut (Sadove and Morreale, 1990). The
frequencies of marine debris ingestion obtained from stranded animals in the UK were 2.2% in the
harbour porpoise (Phocoena phocoena) and 2.3% in the short-beaked common dolphin (Delphinusdelphis) (Deaville and Jepson, 2010). For the Indo-Paciﬁc sector of the Antarctic, our study found that
only 19 Antarctic minke whales out of 11,992 examined had macro debris in their stomachs (0.16%).
The Antarctic minke whale is a ﬁlter feeder species with swallowing behavior (Nemoto, 1970), and290

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MARINE DEBRIS AND EVIDENCE OF ENTANGLEMENTS OF ANTARCTIC MINKE WHALES

Fig. 4. Six cases of Antarctic minke whales in the austral summer seasons 2005/06–2018/19 (JARPAII and
NEWREP-A) presenting marks and scars possibly produced by past entanglements. a: healed injury of ﬂukes;
b: healed injury of snout; c: healed injury of ﬂukes; d: healed injury of ﬂukes (rope used in the whale processing is also shown); e: healed injury of dorsal ﬁn; f: unhealed injury of head.

this foraging behavior of Antarctic minke whales is associated with shallow waters (less than 100 m indepth) (Friedlaender et al., 2014), which increases the chance of ingesting debris ﬂoating on the surface or in layers just under the surface.
Regarding entanglements, only four cases were found in the total sample of 11,992 whales (0.03%)(Table 3, Fig. 3). These included a ﬁshing hook, a monoﬁlament ﬁshing line, a rope and a packing
band. Six out of 5,215 Antarctic minke whales examined from the period of 2005/06 onward presented scars and marks likely to be associated with past entanglements (0.12%) (Fig. 4). It was assumed
that scars were healed injuries (ﬁve cases) while unhealed marks were considered as injuries (onecase). The unhealed injury was observed during the most recent survey under NEWREP-A. The possibility of these scars being produced by attacks from killer whales (Orcinus orca) is low. Scars observed in the present study were not consistent with the dentition of killer whales which comprise linear, parallel scars spaced 2.5–5.0 cm apart (Naessig and Lanyon, 2004). As in the case of debris, casesof entanglements with dangerous objects were extremely low in the Antarctic minke whales fromthe Indo-Paciﬁc sector of the Antarctic when compared to the North Atlantic. For example, along theeastern coast of the United States and Canada during 2002–2006, 27 and 77 cases of entanglements
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ISODA, TAMURA AND PASTENE

Fig. 5. Relationship between body length and body weight in the Antarctic minke whales (n=10,037) including whales ingesting debris and cases of entanglement. The sample size in this ﬁgure is diﬀerent from those in
Tables 1 and 3 (no body weight was available for one animal that ingested polymer product and two entangled
animals).

were reported for common minke whales (B. acutorostrata) and humpback whales (Megaptera novaeangliae), respectively (Glass et al., 2008). In Iceland, ﬁve of 95 ﬁn whales examined showed signs ofprevious entanglements (Sadove and Morreale, 1990). It was reported that entanglement of Antarctic
fur seals (Arctocephalus gazella) was caused mostly by loop shaped debris such as packing bands(Croxall et al., 1990; Arnould and Croxall, 1995). Similar cases were reported for common minke
whales in the Atlantic (Gill et al. 2000). In the present study, one of the four cases of entanglement in
the Antarctic minke whale was from a packing band (Fig. 3d). CCAMLR has prohibited the dischargeof plastics and restricted the use of packing bands on ﬁshing vessels through Conservation Measure
26–01 (CCAMLR, 2006). Fishing gear is the most signiﬁcant source of entanglements for whales
and such entanglements have been reported in various waters (Laist, 1997; Simmonds, 2012). In the
Antarctic, reports of mortality of whales attributed to entanglements related to ﬁsheries operations are
rare. One of those reports informed of the mortality of a sperm whale and another one possibly of an
Antarctic minke whale (SC-CAMLR 2004; 2012). In the present study, only three cases of entanglements occurred, possibly from ﬁshing gears (derelict or active) (Fig. 3).
In the cases involving both macro debris ingested and entanglements, it was shown that whales
were not emaciated according to the usual body-length-weight relationship (Fig. 5). In conclusion thefrequencies of marine macro debris ingested as well the cases of entanglements involving Antarctic
minke whales in the Indo-Paciﬁc sector of the Antarctic are extremely low, and much lower in comparison with cases reported in the North Atlantic. These low frequencies of ingested debris and entanglements are unlikely to have a negative eﬀect on the conservation of the populations of Antarctic
minke whales in the Indo-Paciﬁc sector of the Antarctic.
Acknowledgements

We would like to thank all of the captains, crew members, cruise leaders and researchers onboard the research vessels of292

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MARINE DEBRIS AND EVIDENCE OF ENTANGLEMENTS OF ANTARCTIC MINKE WHALESJARPA, JARPAII and NEWREP-A for their contributions in collecting the data used in this study. Also, we are grateful tothe anonymous reviewers for their helpful comments.

References
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Arthur, C.A., Baker, J. and Bamford, H. 2009. Proceedings of the International Research Workshop on the Occurrence, Effects, and fate of Microplastic Marine Debris. September 9–11. NOAA Technical Memorandum NOS-OR&R-30, 2009,
Washington.
Barnes, D.K.A., Galgani, F., Thompson, R.C. and Barlaz, M. 2009. Accumulation and fragmentation of plastic debris inglobal environments. Philos. Trans. R. Soc. B 364: 1985–1998. doi: 10.1098/rstb.2008.0205.
Baulch, S. and Perry, C. 2014. Evaluating the impacts of marine debris on cetaceans. Mar. Poll. Bull. 80(1–2): 210–221.
CCAMLR. 2006. Schedule of Conservation Measures in Force in 2006/07 season. CCAMLR, Hobart, Australia: 192 pp.
Croxall, J.P., Rodwell, S. and Boyd, I.L. 1990. Entanglement in man-made debris of Antarctic fur seals at Bird Island, South
Georgia. Mar. Mamm. Sci. 6: 221–233. doi: 10.1111/j.1748-7692.1990.tb00246.x.
Deaville, R. and Jepson, P.D. (eds.). 2010. UK Cetacean Strandings Investigation Programme (CSIP)—Final Report for theperiod 1st January 2005–31st December 2010. CSIP, Institute of Zoology, Zoological Society of London, UK. 98 pp.
Friedlaender, A.S., Goldbogen, J.A., Nowacek, D.P., Read, A.J., Johnston, D. and Gales, N. 2014. Feeding rates and under-ice foraging strategies of the smallest lunge ﬁlter feeder, the Antarctic minke whale (Balaenoptera bonaerensis). J.
Exp. Biol. 217(16): 2851–2854. doi: 10.1242/jeb.106682.
Gill, A., Fairbairns, B. and Fairbairns, R. 2000. Photo-identiﬁcation of the minke whale (Balaenoptera acutorostrata) aroundthe Isle of Mull, Scotland. Report to the Hebridean Whale and Dolphin Trust. 88 pp.
Glass, A.H., Cole, T.V.N., Garron, M., Merrick, R.L. and Pace III, R.M. 2008. Mortality and serious injury determinations forbaleen whale stocks along the United States eastern seaboard and adjacent Canadian Maritimes, 2002–2006. U.S. Dept.
Commerce., Northeast Fish. Sci. Cent. Ref. Doc. 08–04. 18 pp.
Gregory, M.R. 2009. Environmental implications of plastic debris in marine settings-entanglement, ingestion, smothering,hangers-on, hitch-hiking and alien invasions. Philos. Trans. R. Soc. B 364: 2013–2025. doi: 10.1098/rstb.2008.0265.
Ichii, T. and Kato, H. 1991. Food and daily food consumption of southern minke whales in the Antarctic. Polar Biol. 11:
479–487. doi: 10.1007/BF00233083.
International Whaling Commission. 2020. Report of the IWC Workshop on Marine Debris: The Way Forward, 3–5 December 2019, La Garriga, Catalonia, Spain. Paper SC/68B/REP/03 presented to the IWC Scientiﬁc Committee, May 2020
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Kato, H. 1982. Some biological parameters for the Antarctic minke whale. Rep. int. Whal. Commn. 32: 935–945.
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Tamura, T. and Konishi, K. 2009. Feeding habits and prey consumption of Antarctic minke whale (Balaenoptera bonaerensis) in the Southern Ocean. J. Northwest Atl. Fish. Sci. 42: 13–25. doi: 10.2960/J.v42.m652.

Received: December 25, 2020
Accepted: June 10, 2021
Published online: December 8, 2021

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Review

Blowing of a juvenile ﬁn whale, North Paciﬁc.

J-STAGE Advance published date: October 8, 2021

ACOUSTIC MONITORING OF LARGE WHALES IN JAPANESE WATERSA SHORT REVIEW OF ACOUSTIC MONITORING OF
LARGE WHALES IN JAPANESE WATERS
Tomonari AKAMATSU
Ocean Policy Research Institute, the Sasakawa Peace Foundation,
1–15–16 Toranomon, Minato-ku, Tokyo 105–8524, Japan
Corresponding author: t-akamatsu@spf.or.jp

Abstract
Passive acoustic monitoring studies of large whales in the Japanese EEZ are reviewed inthis paper. Submarine cables to monitor seismic events have been installed on the Paciﬁc
Ocean side of Japan because of the risk of earthquake strikes. Low frequency ﬁn whale Balaenoptera physalus calls have been detected mostly in winter time. Many ﬁn whale calls wereobserved in the waters oﬀ Kushiro in the northern part of Japan. A scientiﬁc submarine cablein Sagami Bay, 100 km west of Tokyo, revealed frequent presence of sperm whales Physeter
macrocephalus year around. In the Ogasawara and Okinawa archipelagos, known as breeding
grounds of humpback whales Megaptera novaeangliae, songs were recorded using stationed
or boat-based recordings.
Key words:

passive acoustic monitoring, ﬁn whale, sperm whale, humpback whale, underwater sound.

Introduction
As is well known, baleen whales produce low frequency sounds during the breeding season. For
example, blue whales produce frequency modulated sounds as low as 15.3 Hz (Staﬀord et al., 2001),
which is similar to the frequency range of earthquake vibrations. In the early 90’s, underwater sounddata received by military submarine cables was made available for scientiﬁc purposes to monitor baleen whales passively. Earlier, Dr. Ohsumi suggested application of passive acoustic monitoring fora survey of baleen whales (Ohsumi, 1994), referring to SOSUS and SURTASS systems (Nishimura
and Conlon, 1994). Passive acoustic monitoring is the method of observing animals by receiving their
vocalizations. Especially in the ocean, passive acoustic monitoring is a powerful method to identify
presence, location, and movement of phonating animals in the water.
However, the passive acoustic method was not widely used in Japanese waters until recent years.
Most of the Japanese studies are not accessible from outside of Japan or not yet published. As thosestudies are not well known internationally, there is the mistaken impression of a “vacuum zone” ofpassive acoustic monitoring of large whales in the western Paciﬁc Ocean. This paper brieﬂy introducespassive acoustic monitoring studies of large whales in Japanese waters. In contrast, passive acoustic
monitoring of small odontocetes has been extensively conducted in Japanese and Asian waters. Manyof these scientiﬁc papers appeared in international journals, which can be found by searching “A-tag”
and “porpoise”:
https://scholar.google.com/scholar?hl=0%2C5&q=A-tag+porpoise.

Review
Japan is located at the edge of the Paciﬁc Rim and has suﬀered severe earthquake strikes many
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Fig. 1. Location of submarine cables in the Japanese EEZ and two breeding grounds of humpback whales(Okinawa and Ogasawara). Hatsushima cable is for scientiﬁc research purposes. The other four cables(Kushiro-Tokachi, DONET1, DONET2 and S-net) are deployed to observe seismic events nearby the trenchshafts. The S-net shown in dotted line has seismometers, which provides water acceleration associated withlow frequency sounds; no hydrophone data is available.

times. To monitor seismic events, submarine cables have been installed in the Japanese EEZ (exclusive economic zone), as shown in Fig. 1. For example, the Kushiro-Tokachi cable oﬀ Hokkaido was
deployed in 1999 (Hirata et al., 2002). S-net is the newly installed 5,500 km submarine cable in operation since 2016, which covers the eastern side of Honshu Island from oﬀ Hokkaido, Aomori, Sanriku
and the Boso Peninsula (https://www.seaﬂoor.bosai.go.jp/S-net/). The installation of DONET1 (Dense
Ocean Floor Network System for Earthquakes and Tsunamis) observational equipment on 20 stationsat Kumano-Nada was completed in 2011 (https://www.jamstec.go.jp/donet/e/cable/). In addition,
DONET2 was deployed oﬀ Cape Muroto. DONET systems are currently operated by the National Research Institute for Earth Science and Disaster Resilience (https://www.seaﬂoor.bosai.go.jp/). Hatsushima cable in Sagami Bay has recorded a human audible range of underwater sounds since 1993
(Iwase et al., 2001). These cable systems have hydrophones or seismometers to record underwatersound pressure or water acceleration.
Passive acoustic monitoring of ﬁn whales Balaenoptera physalus
Low frequency calls of ﬁn whales were detected in winter time oﬀ Hokkaido by the Kushiro-Tokachi
cable (Matsuo et al., 2017). Four stations (DSO, OBS1, OBS2, OBS3) with hydrophones are locatedbetween 41°40.050′N–42°15.168′N, 144°20.454′E–145°3.372′E and 2,124 m–3,428 m in depth. Overa total of 2,981 recording days, 2,865,403 calls were identiﬁed by an automatic detector designed forthis study. Clear seasonal diﬀerences were observed, being high during October and February, and low
in the summertime. The number of calls received in a month showed a double peak structure in October
and January. Call detection did not show a diurnal pattern. Nishida et al. (2018) developed a web system to visualize detections of ﬁn whale calls. Yoshida (2017) independently analyzed Kushiro-Tokachi
cable data and reached a similar conclusion of the seasonal presence of ﬁn whales.
Ocean bottom seismometer data of S-net well supported the above results. Using 150 points of
S-net observatory data, Nakamura (2020) documented the frequent call detections during October to298

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April. In areas oﬀ Kushiro and Aomori, the number of detections were high during December to January. After January, the area of the highest reception shifted to the south-west, in waters oﬀ Aomori andSanriku. In addition, calls were detected on the shore side of the trench shaft, approximately 200 km
oﬀ Honshu Island. The seismometers in the southern part of S-net located oﬀ Boso Peninsula received
ﬁn whale calls in winter time, although the number of received calls was far smaller compared withthose observed oﬀ Kushiro.
According to the DONET1 data, no ﬁn whale calls were identiﬁed year round (Ikuo Matsuo, pers.
comm.). The location of DONET1 is approximately 400 km southwest of Boso Peninsula. This area
might not be a breeding ground of ﬁn whales. For DONET2, data analysis of baleen whale sounds has
not been conducted.
Passive acoustic monitoring of sperm whales Physeter macrocephalus
Hatsushima Island Cabled Observatory (Hatsushima cable) is located on the seaﬂoor at a depth of
1,175 m about 7 km southeast oﬀ Hatsushima Island in the western part of Sagami Bay, which is approximately 90 km southwest of Tokyo. Iwase (2012) retrieved audio sounds recorded from the soundtrackof videotape, which was received by the hydrophone of this observatory. Sperm whale clicks including
creaks (series of very rapid clicks, inter-click intervals less than about 0.2 second) were observed. Iwase(2012) reported that no seasonality of the detections of sperm whale clicks was observed during the
1994–2012 period. The data suggested that sperm whales appeared around Hatsushima cable all year.
Amano et al. (2014) recorded sperm whale sounds by towed or suspended hydrophone oﬀ theKumano-Nada coast and Ogasawara waters. Statistical diﬀerences in the number of clicks andinter-click intervals were identiﬁed. They suggested diﬀerent vocal clans in the two study sites.
Passive acoustic monitoring of humpback whales Megaptera novaeangliae
Since Payne and McVay (1971) reported the songs of humpback whales, song structure of baleen
whales produced in the breeding season is one of the major subjects of underwater bioacoustics.
Maeda’s (2002) doctoral dissertation at Nagasaki University gives a systematic description of the song
structure of humpback whales in Okinawa waters. Using boat-based recordings during 1991–1998,
unit structure and unit sequence in a phrase were analyzed. Individual variations and year-by-yearchange of song structure were reported. In addition, Maeda (2002) compared song recordings between
Okinawa and Ogasawara waters during 1992–1995 and found no signiﬁcant diﬀerence in song structures of humpback whales. As Darling and Mori (1993) reported, the same humpback whales wereidentiﬁed in both waters, consistent with the comparisons of acoustic features.
In recent years, singing behavior and the location of humpback whales in Ogasawara waters were
examined to assess the eﬀect of ship noise (Tsujii et al., 2018). They installed two ﬁxed underwater recorders separated by 3.0 km. Recorders were exchanged every two or three weeks before their batteries
ran out. Each recorder had a stereo hydrophone. This monitoring method enabled localization of singers by triangulation from the two locations, simultaneously with the recording of song structure. Fewer
whales sang nearby, within 500 m, of the shipping lane. Humpback whales reduced sound production
after a ship passed, when the minimum distance to the whale from the ship trajectory was 1,200 m.

Discussion
Passive acoustic monitoring is a powerful method to observe presence, location, and movementsof cetaceans. Even density can be estimated when phonating intervals, directionality, and source level
are available. In Japanese waters, several already-existing submarine cables are available. Most of thedata is available for research purposes judged to be conducive to the management of baleen whales in
the Japanese EEZ. To accelerate passive acoustic studies of large whales, several future directions can
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be suggested.
1. Encourage open data policy of underwater sounds. Data classiﬁcation and masking will be needed
to avoid conﬂict with national security in the low frequency range. For high frequency sounds ofsperm whales and other large odontocetes, this constraint will be relaxed.
2. For automatic detection and classiﬁcation of species or families, collections of species’ annotatedsounds are required to ensure acceptable performance of machine learning applications.
3. Improvement of density estimation models will serve for abundance estimation of oﬀshore baleen
whale populations. In the winter time when survey vessels are diﬃcult to operate, the area of breeding
grounds of large baleen whales will be an appropriate target for passive acoustic monitoring studies.

References
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Darling, J.D. and Mori, K. 1993. Recent observations of humpback whales (Megaptera novaeangliae) in Japanese waters oﬀ
Ogasawara and Okinawa. Can. J. Zool. 71(2): 325–333. doi: 10.1139/z93-045.
Hirata, K., Aoyagi, M., Mikada, H., Kawaguchi, K., Kaiho, Y., Iwase, R., Morita, S., Fujisawa, I., Sugioka, H., Mitsuzawa,
K., Suyehiro, K., Kinoshita, H. and Fujisawa, N. 2002. Real-time geophysical measurements on the deep seaﬂoor
using submarine cable in the southern Kurile subduction zone. IEEE J. Ocean. Eng. 27(2): 170–181. doi: 10.1109/
JOE.2002.1002471.
Iwase, R. 2012. Sperm whale click sounds recorded on videotapes of a deep seaﬂoor cabled observatory in Sagami Bay,
Japan. Proc. Mtgs. Acoust. 17: 070042. doi: 10.1121/1.4772737.
Iwase, R., Mitsuzawa, K., Hirata, K., Kaiho, Y., Kawaguchi, K., Fujie, G. and Mikada, H. 2001. Renewal of “real-time deep
seaﬂoor observatory oﬀ Hatsushima Island in Sagami Bay”—Toward the development of “next-generational” real-time
deep seaﬂoor observatory. JAMSTEC J. Deep Sea Res. 18: 185–192. (In Japanese with English abstract).
Maeda, H. 2002. Acoustic characteristics of vocalization of humpback whale Megaptera novaeangliae in the Ryukyu region.
Doctoral dissertation, Nagasaki University. Available here: https://hdl.handle.net/10069/7300. (In Japanese).
Matsuo, I., Akamatsu, T., Iwase, R. and Kawaguchi, K. 2017. Seasonality of ﬁn whale calls detected from the deep sea ﬂoor
observatory oﬀ Kushiro-Tokachi. J. Marine Acoust. Soc. Jpn. 44(1): 13–22. doi: 10.3135/jmasj.44.13. (In Japanesewith English abstract).
Nakamura, T. 2020. Kaitei jishinkei no “noizu” deta kara suiteisareta nagasukujira no jikuukan bunpu. Kokuritsu Kenkyu
Kaihatsu Houjin Bosai Kagaku Gijutsu Kenkyusho. Reiwa Gannendo Seika Happyoukai 2020.2.13. (Time-spatial
distribution of ﬁn whales estimated by “noise” data obtained by submarine seismometer. National Institute for Earth
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on&c=1610086751. (In Japanese).
Nishida, S., Matsuo, I., Iwase, R. and Kawaguchi, K. 2018. Visualization of large whales’ calls with submarine cable observatory. J. Marine Acoust. Soc. Jpn. 45(3): 131–135. (In Japanese).
Nishimura, C.E. and Conlon, D.M. 1994. IUSS dual use: monitoring whales and earthquakes using SOSUS. Mar. Technol.
Soc. J. 27(4): 13–21.
Ohsumi, S. 1994. Meion de kujira no koudou wo saguru (Exploring whale behavior using their vocalizations). Geiken
Tsuushin 384: 9–14. (In Japanese).
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Paciﬁc. J. Cetacean Res. Manag. 3(1): 65–76.
Tsujii, K., Akamatsu, T., Okamoto, R., Mori, K., Mitani, Y. and Umeda, N. 2018. Change in singing behavior of humpback
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Yoshida, R. 2017. Kushiro oki ni setchisareta kaitei jinkei kara erareta geirui meion bunseki (Analysis of cetacean vocalizations obtained by ocean bottom seismometer oﬀ Kushiro). Master’s thesis, Tokyo University of Marine Science andTechnology. Available here: http://id.nii.ac.jp/1342/00001397/. (In Japanese).

Received: January 31, 2021
Accepted: May 24, 2021
Published online: October 8, 2021

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J-STAGE Advance published date: May 6, 2021

IMPACT OF WHALE RESOURCE MANAGEMENT RESEARCH ON SIKA

IMPACT OF WHALE RESOURCE MANAGEMENTRESEARCH ON SIKA DEER MANAGEMENT
Koichi KAJI1, 2
Tokyo University of Agriculture and Technology
Wildlife Management Research Center, Hyogo,
940 Aogakicho Sawano, Tamba, Hyogo 669–3842, Japan
Corresponding author: kkaji@cc.tuat.ac.jp
12

Abstract
Sika deer population management in Hokkaido has been strongly inﬂuenced by whale resource management research in monitoring frameworks and management approaches. The
whale survey consisted of ﬁve pillars: catch statistics, visual observations, tag-recovery surveys, biological surveys from whaling, and special catch surveys. In references to the whale
monitoring, sika deer monitoring was constructed involving capture information (SPUE,
CPUE), visual observations (spotlight census, aircraft survey), radio telemetry surveys, genetic
surveys, and biological surveys from hunting and culling for assessing age structure and the
reproductive characteristics of female deer. We adopted the Revised Management Procedure(RMP）for whaling to Hokkaido sika deer population as feedback management because there
was uncertainty in estimating population size. Feedback management incorporated into deer
management in the eastern part of Hokkaido became the pioneer of science-based wildlife
management in Japan. It inﬂuenced the establishment of the Speciﬁed Wildlife Conservationand Management Plan by amending the Wildlife Protection and Hunting Act in 1999. Feedback management is almost synonymous with adaptive management in a broad sense. The
large-scale feedback management of sika deer in Hokkaido is a practical example of adaptive
management of deer ahead of the world.
Key words:

Adaptive management, feedback management, revised management procedure,
sika deer, monitoring, whale.

Introduction
Hokkaido Government established the Hokkaido Institute of Environmental Sciences (HIES) in
1991, when I started to work as a researcher for sika deer (Cervus nippon) management. Until then,monitoring of terrestrial large animals was not carried out except for Japanese serow (Capricornis
crispus), a species designated as a nation’s Special Natural Monument. Sika deer population management in Hokkaido has been strongly inﬂuenced by whale resource management research in monitoring
frameworks and management approaches. As a result, it has played a leading role in science-based
wildlife management in Japan.

Review
Monitoring
In 1991, when I was planning sika deer monitoring all over Hokkaido, Dr. Hidehiro Kato kindly
sent me a book entitled “Study on Whale Stock Management” (Sakuramoto et al., ed. 1991). This
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book, covering all aspects of whale resource management involving theory and practice, attracted mevery much. The whale resource management research was ideal for researchers on large mammal population dynamics. Dr. Seiji Ohsumi reviewed the method and its system in Chapter 1 (Ohsumi, 1991),
which was particularly useful for constructing the baseline of sika deer monitoring.
The whale survey consisted of ﬁve pillars: catch statistics, visual observations, tag-recovery surveys, biological surveys from whaling, and special catch surveys. The biological surveys were conducted for three purposes: genetic analysis for separation of lineages, estimation of biological parameters, and elucidation of cetaceans’ ecosystems.
In references to the whale monitoring, I constructed sika deer monitoring using capture information(SPUE: Sighting per Unit Eﬀort, CPUE: Catch per Unit Eﬀort) per each 5 km×5 km grid, and visualobservations (spotlight census, aircraft survey) over a wide area to grasp the rough population trend.
To determine the management unit for sika deer, my research team and I conducted radio telemetry
surveys and genetic surveys in Eastern Hokkaido. We also worked on age determination from the individuals captured by hunting and culling and analyzed the reproductive characteristics of female deer.
Seasonal migration, the genetic structure of populations
To determine management units for sika deer population, we examined seasonal migration andhabitat use by installing dozens of VHS radio transmitters in the deer population in eastern Hokkaido(Uno and Kaji, 2000, Igota et al., 2004). We also studied changes in the populations’ genetic structure
in recovering the distribution from near extinction (Nagata et al., 1998) and expanding the distribution
to the saturation period (Ou et al., 2014). These ﬁndings were signiﬁcant for considering the management unit for developing sika populations in Hokkaido.
Population dynamics: its processes and mechanisms
As model survey sites for closed habitats, I chose Nakanoshima Island in Lake Toya, where deer
have been artiﬁcially introduced, and Cape Shiretoko, where deer colonized. I set up two places foran open environment: Onbetsu town and Ashoro town in Eastern Hokkaido. The population survey
method depended on the region; drive count method on Nakanoshima Island, aerial survey at Cape
Shiretoko, spotlight count at Onbetsu town, and cohort analysis by age determination of a total of
17,549 individuals captured in Ashoro town over 12 years. Then, we analyzed the process and patternof population ﬂuctuation and its mechanism.
These studies revealed that the natural increase rate of sika deer was around 20% without harvesting or predator, that explosive increases occur, even when they are introduced into the island or naturally colonizing, and even in settled populations with original habitat. Large-scale population crashrepeatedly occurred in closed habitat (Nakanoshima Island and Cape Shiretoko) (Kaji, 2018). Thus, inthe absence of predators and harvesting, the populations would not be in equilibrium with plants andsubstantially impacted the vegetation. These clearly showed that aggressive culling for female deer
was necessary to reduce the overabundant sika deer population.
Feedback Management
From the hunting season in 1994, female deer hunting was allowed in Hokkaido for the ﬁrst time in
72 years. However, there were many objections in fear that overharvesting in the Meiji era would leadto extinction. We recognized the increasing trends of the deer population in eastern Hokkaido. However, there was uncertainty in estimating population size, so it was impossible to determine how many
deer we should harvest at that time.
We invited Dr. Hiroyuki Matsuda, an expert in mathematical ecology and ﬁshery resource management, as a lecturer and held a resource management study session for sika deer to consider breakthrough measures. Dr. Matsuda proposed feedback management of sika deer (Matsuda et al., 1999)
following the Revised Management Procedure (RMP) for whaling (Tanaka, 1982). Feedback man-

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agement incorporated into deer management in the eastern part of Hokkaido became the pioneer ofscience-based wildlife management in Japan. It inﬂuenced the establishment of the Speciﬁed Wildlife
Conservation and Management Plan by amending the Wildlife Protection and Hunting Act in 1999.
The Ministry of the Environment adopted a Feedback management approach in the deer management
manual.
Towards adaptive management
Adaptive management is suitable for managing wildlife populations and natural resources thatobtain insuﬃcient and uncertain data and continuously improves management policies and practices
through adaptive learning and feedback management (Walters, 1986). On the other hand, feedback
management is a management policy for sustainable use at the optimum level based on uncertain
information on natural resources (Tanaka, 1982), which is almost synonymous with adaptive management in a broad sense.
Adaptive management is considered the best way to solve the biological and policy dilemma of
deer management in US national parks; however, there are limited cases in practice (Porter and Underwood, 1999). In France, adaptive management using indicators of ecological change is adopted for the
management of small scale and well-deﬁned population of roe deer (Morellet et al., 2007). Therefore,
the large-scale feedback management of sika deer in Hokkaido is a practical example of adaptive management of deer ahead of the world.

Conclusion
On October 25, 2001, I had the opportunity to report on the feedback management of sika deer in
Hokkaido at the Institute of Cetacean Research seminar. Dr. Shoichi Tanaka, who advocated feedback
management, and Dr. Ohsumi, the Institute of Cetacean Research director, attended the venue.
In the seminar, I explained that the deer management goal in Europe and the United States wasmaintaining maximum sustain yield (MSY) by managing the population around K/2 of the MSY
curve. However, K/2 was too high to prevent damages to agriculture and forestry and ecosystem of
cervid populations with weak density dependence like sika deer (Kaji et al., 2010). Avoiding severe
deer damages, maintaining the population considerably lower than the carrying capacity was required.
The sika deer management goals of our program were: (1) to keep the population at moderate density
levels preventing population irruption, (2) to reduce damage to crops and forests, and (3) to sustain areasonable yield of hunting without endangering the population. We developed a threshold harvesting
approach as feedback management involving three threshold levels of relative population size, fourlevels of hunting pressure, with a choice of four corresponding management actions by sex-speciﬁchunting, based on the estimates of relative population size (Matsuda et al., 1999).
I concluded that harvesting was the only operational experiment, essential for population abundance
estimation and density dependency detection. Hunting was a large-scale ecological experiment since
it was impossible to conduct repetitive experiments in nature and manipulate the natural environment.
Drs. Ohsumi and Tanaka were pleased to listen to my presentation, which encouraged me to progressscience-based wildlife management for sika deer.

References
Igota, H., Sakuragi, M., Uno, H., Kaji, K., Kaneko, M., Akamatsu, R., and Maekawa, K. 2004. Seasonal migration patternsof female sika deer in eastern Hokkaido, Japan. Ecol. Res. 19: 169–178.
Kaji, K., Saitoh, T., Uno, H., Matsuda, H., and Yamamura, K. 2010. Adaptive management of sika deer populations in

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Hokkaido, Japan: Theory and practice. Popul. Ecol. 52: 373–387.
Kaji, K. 2018. Toward science-based wildlife management: irruption and management of the sika deer population on
Hokkaido. Honyurui Kagaku (Mammalian Science) 58: 125–134. (In Japanese).
Matsuda, H., Kaji, K., Uno, H., Hirakawa, H., and Saitoh, T. 1999. A management policy for sika deer based on sex-speciﬁchunting. Res. Popul. Ecol. 41: 139–149.
Morellet, N., Gaillard, J.M., Hewison, A.J.M., Ballon, P., Boscardin, Y., Duncan, P., Klein, F., and Maillard, D. 2007. Indicators of ecological change: New tools for managing populations of large herbivores. J. Appl. Ecol. 44: 634–643.
Nagata, J., Masuda, R, Kaji, K., Kaneko, M. and Yoshida, M.C. 1998. Genetic variation and population structure of theJapanese sika deer (Cervus nippon) in Hokkaido Island, based on mitochondrial D-loop sequences. Mol. Ecol. 7:
871–877.
Ohsumi S. 1991. Review of activities of the IWC Scientiﬁc Committee, p. 1–21. In: Studies of Whale Stock Management (ed.
by Sakuramoto, K., Kato, H. and Tanaka, S.) Koseisha Koseikaku, Tokyo, 273 pp. (In Japanese).
Ou, W., Takekawa, S., Yamada, T., Terada, C., Uno, H., Nagata, J., Masuda, R., Kaji, K., and Saitoh, T. 2014. Temporalchange in spatial genetic structure of a sika deer population with an expanding distribution range over a 15 years period. Popul. Ecol. 56: 311–325.
Porter, W.F., and Underwood, H.B. 1999. Of elephants and blind men: Deer management in the US National Parks. Ecol.
Appl. 9(1): 3–9.
Sakuramoto, K., Kato, H., and Tanaka, S. (eds.) 1991. Studies on Whale Stock Management. Koseisha Koseikaku, Tokyo.
273 pp. (In Japanese).
Tanaka, S. 1982. The management of a stock-ﬁshery system by manipulating the catch quota based on the diﬀerence between
present and target stock level. Bull. Japan Soc. Sci. Fish. 48: 1725–1729.
Uno, H. and Kaji, K. 2000. Seasonal movements of female sika deer in eastern Hokkaido, Japan. Mamm. Study 25: 45–57.
Walters, C.J. 1986. Adaptive Management of Renewable Resources. MacMillan Publishing Company, New York, 374 pp.

Received: January 13, 2021
Accepted: February 15, 2021
Published online: May 6, 2021

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Others

Snouting of an old Bryde’s whale, North Paciﬁc.

AN ANALYSIS OF JAPANESE WHALE KILLING DATA (1996)

Historical Records

AN ANALYSIS OF JAPANESE WHALE KILLING DATAWITH SPECIAL EMPHASIS ON THE USE
OF THE ELECTRIC LANCE AS
A SECONDARY KILLING METHOD1)
Lars WALLØE2)
Abstract
During the IWC Workshops on whale killing methods in 1992 and 1995 Japanese whalers
were criticized for the use of the electric lance as a secondary killing method. It was claimed,
especially by Australian scientists, that the use of the electric lance resulted in long survival
times and much suﬀering. The times to death for 891 whales were analysed by logistic regression and Cox regression. For 560 of these a secondary killing method was used; the electric
lance was used in 326 cases, and a cold harpoon in 234 cases. The median killing time for theelectric lance was 40 s and for the cold harpoon 4.7 minutes. The analyses showed that theelectric lance killed the whales much faster than the cold harpoon. At the time, Japanese laws
did not allow the crew to keep ﬁrearms on board ﬁshing or whaling vessels. These laws havebeen changed, and today the use of a shot from a riﬂe through the brain of the whale is the preferred secondary killing method.
(This abstract was prepared in August 2021 in accordance with request from the Publication
Committee for the Cetacean Population Studies (CPOPS)).
Key words:

electric lance, whale killing methods, minke whales, Kaplan-Meier plots, Cox
regression.

Preamble
The present paper was prepared for the IWC Commission meeting in Aberdeen in 1996. The work
was supported by the late Seiji Ohsumi, who was head of the Japanese delegation to the IWC Scientiﬁc Committee, and Mr. Kazuo Shima, the Japanese Commissioner to the IWC at the time. Although
the main results were presented orally and discussed during the Commission meeting, and copies ofthe manuscript were distributed to the participants, the article was never properly published. Killing
methods for whales were not considered part of the terms of reference for the IWC Scientiﬁc Committee, and the manuscript could therefore not be published in its series of scientiﬁc papers. On the occasion of publication of the memorial volume for the late Seiji Ohsumi, we have now tried to retrieve it.

The present scientiﬁc article was originally prepared for the IWC Commission meeting as document (IWC/48/WK
2—1996) in Aberdeen, Scotland, in 1996. The paper is reproduced here in accordance with the request from the CPOPS
Publication Committee, to commemorate the days when Dr. Seiji Ohsumi was active at the IWC Scientiﬁc Committee.
2)
Professor Emeritus, Department of Physiology,University of Oslo, Norway
Corresponding author: lars.walloe@medisin.uio.no1)

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IWC/48/WK 2—1996

AN ANALYSIS OF RECENT JAPANESE WHALEKILLING DATA WITH SPECIAL EMPHASISON THE USE OF THE ELECTRIC LANCE AS
A SECONDARY KILLING METHOD
Lars Walløe
Departments of Physiology and Informatics University of Oslo
P.O. Box 1103 Blindern, 0317 Oslo, Norway

Introduction
Killing methods for minke whales have improved considerably during the past 15 years(IWC/47/18-1995). The IWC held its first workshop on the topic in 1980 (‘Workshop on humane killing techniques for whales’ —IWC/33/15). The workshop made a number of recommendations for future research and development, and also recommended a set of criteria
which should be used to measure time to death in whales. These were the time “taken forthe mouth to slacken, the flipper to slacken and all movement to cease.” The workshop recognised that these criteria probably overestimated the time to death, since work on dolphins
had shown that these animals, like other mammals, may have agonal reflex movements.
Workshops on whale killing methods in 1992 (IWC/44/REPHK) and 1995 (IWC/47/18) evaluated the progress made since 1980 and made new recommendations. Although a wide rangeof views was expressed at these workshops, the data presented seemed to indicate that thekilling methods currently being used for minke whales by Japanese and Norwegian whalers
compared favourably in efficiency with those used in the hunting of large terrestrial animals in
Europe and North America (Lockyer –IWC/47/WK1; Øen and Walløe—IWC/47/WK9).
However, some of the participants at these two workshops, especially in 1995, strongly criticised the use of the ‘electric lance’ as a secondary killing method (e.g. Blackmore
IWC/47/WK2). On the other hand, the Japanese Government presented a paper to the1995 workshop which appeared to indicate that the electric lance killed whales very rapidly(IWC/47/WK 11). Unfortunately, the paper did not give much information except for the meantimes to death for some subgroups.
During the workshop, I received the impression that the participants did not understand thecontent of the paper properly, and that its claim that the mean time to death was only 44 seconds when the lance was used was not believed. I therefore proposed to my Japanese colleagues that I should reanalyse the Japanese data on killing times, using statistical methods
which I had previously used on similar data from Norwegian whaling operations (Øen and
Walløe 1995). The present paper contains the main results of this analysis.

Materials and Methods
The primary data for the present analysis consist of the killing times and a number of covariates for all whales included in the Japanese scientific catches of minke whales in theSouthern Ocean and in the North Pacific respectively during the last two hunting seasons.

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In all 891 minke whales were taken: 330 in 1994–95 and 440 in 1995–96 in the Antarctic
Ocean, and 21 in 1994 and 100 in 1995 in the North Pacific. All whales were taken by thesame whaling vessel and by and large by the same crew of whalers. Only 6 different gunners
operated the harpoon gun during these two years.
The killing time, i.e. the time from a strike by the penthrite grenade harpoon until the whale
was declared dead according to the criteria established by the IWC (IWC/33/15 1980), wasrecorded using a stop-watch. If a whale died instantaneously or within a few minutes, nosecondary killing method was used. But if the whale showed signs of life after the first hit, thecrew prepared to use one of the two available secondary killing methods. The first of these
was to shoot a second (cold) harpoon into the whale. This operation could be repeated. The
second method available was to use electrical stunning.
The following is a short description of electrical stunning as carried out by Japanese minke
whalers. The whale is pulled up to the catcher boat and two electrodes (‘electric lances’) are
inserted through the blubber into the muscular tissue underneath, one in front of the heartand one behind. The whale is killed by sending alternating current between the electrodes.
The mechanism responsible for the death of the animal is probably fibrillation of the heart,causing complete cessation of circulation. When the current is switched on, the animal bodyusually undergoes convulsive muscular contractions, and it is not possible to apply the IWC
death criteria. The current is therefore switched off at regular intervals. The duration of eachbout of current is reported to be about 10 seconds.
The electric lance was sometimes used in addition to a cold harpoon if the first (or second)
cold harpoon failed to kill the animal.
In most cases the whalers chose the secondary killing method they considered most suitable in the circumstances. If, for instance, the whalers considered that the first harpoon wasin danger of being pulled out, a second harpoon was used. On the other hand, if the whale
was close to the boat, it was often not possible to shoot it with a second harpoon, but theelectric lance could conveniently be applied.
In some cases either secondary killing method could be used with an equal chance of success as judged by the whalers. During the Antarctic whaling operations, the use of the cold
harpoon or electric lance as the secondary killing method was randomised for 123 of theseanimals, 61 during the 1994–95 season and 62 during the 1995–96 season. This group ofwhales is designated the ‘experimental’ group.
In addition to the time to death the data file contained the following covariates for eachwhale: a letter identifying the gunner, the body weight, the body length, ‘experimental’ or not,(first) secondary method (none, harpoon, lance), number of cold harpoons, voltage and amperage of electric current, time to firing of (first) cold harpoon, time to use of lance, loss/recapture, and in addition a serial number which could be used to obtain additional information
about individual whales if desired. All 891 records were complete.
The data were analysed by conventional statistical methods. Since many of the variables
have empirical statistical distributions with long tails to large values (e.g. time to death), nonparametric tests and estimation methods were used. Most of the results are presented as
survival plots. For some variables, survival analysis with censoring was used, and the survival distributions were estimated by product-limit (Kaplan-Meier) methods (BMDP1L). The
influence of covariates on time to death was investigated by Cox regression (proportional
hazard) and by a combination of logistic regression for whales killed instantaneously (<10 s)
and Cox regression for whales surviving more than IOs (BMDP2L+BMDPLR). To investigate
possible differences between gunners and seasons, a general mixed model analysis of variance including gunners as a random variable was used (BMDP3V).

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Results
Fig. 1 presents the distribution of times to death for all 891 whales which are included in
the analysis. Two whales which were first lost and later recaptured survived for 96 and 130
minutes respectively and are not represented on this graph (but are included in the statistics). 26% of the whales died instantaneously. The median survival time was 4.8 minutes,
9.5% of the whales lived for more than 10 minutes, and 3.1% for more than 15 minutes. Thirty five whales were lost and later recaptured using grenade or cold harpoons, 32 because
the harpoon pulled out and 3 because the fore-runner broke. All whales with survival times
longer than 20 minutes were from this group of 35 lost and recaptured whales.
Fig. 2 shows that there were only minor differences between the results obtained from dif-

Fig. 1. Survival plot for all 891 minke whales caught during Japanese scientific whaling in the twoyear period from April 1994 to April 1996. Abscissa: Time in minutes after the whale was hit by agrenade harpoon. Ordinate: Fraction of whales still showing signs of life. Each dot represents thetime of death of one or more whales. Two whales which were lost and recaptured survived for 96
and 130 minutes, respectively and are excluded from the graph (but not from the statistical calculations). Median survival time: 4.8 minutes.95% confidence interval for the median: (4.5–5.0) minutes.

Fig. 2. Survival plots for whales caught in the North Pacific in 1995 (100—triangles), in the Antarctic
Ocean in 1994–95 (330—circles), and in the Antarctic Ocean in 1995–96 (440—squares). Axes as
in Fig. 1.

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ferent oceans and years.
In addition to the 233 whales which died instantaneously, 98 whales died before a secondary killing method could be used. The survival plot for these 331 whales is shown in Fig. 3.
The death rate for whales which were not killed instantaneously was 1.8% per minute whenno secondary killing method was used.
For the remaining 560 whales (63%), a secondary killing method was used; the electric lance
was used in 326 cases, and a cold harpoon in 234 cases. Only 111 of the 234 whales for whichcold harpoons were chosen as the secondary killing method actually died as a result of being hit
by this harpoon. The remaining 123 were finally killed by the electric lance. Thus, 449 whales inall were killed by the electric lance. In 326 cases the electric lance was used immediately after the
grenade harpoon, and in 123 cases after one or more cold harpoons had failed to kill the animal.
Fig. 4 presents the distribution of total times to death for whales for which secondary killing
methods were used, divided into two groups: 326 whales which were stunned with the elec-

Fig. 3. Survival plot for the 331 whales which were killed by the grenade harpoon alone. Axes andsymbols as in Fig. 1.

Fig. 4. Survival plots for whales for which the electric lance was used as the only secondary killing
method (squares—n=326), and for whales which were shot with a cold harpoon (triangles, lost/
recaptured excluded—n=199). The later were censored if and when the electric lance was used
(53% censored). Median survival time for lanced whales: 5.3 (5.2–5.5) minutes, for whales thatwere cold harpooned 10.4 (9.3–12.5) minutes.
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tric lance after being hit by a penthrite grenade, and 199 whales which were shot with a cold
harpoon. Whales were censored from this plot if and when the electric lance was used after
a cold harpoon. The 35 lost and recaptured whales have been excluded from this plot. Ifthey had been included, the tail of the cold harpoon curve would have been lifted somewhat(so that survival at 15 minutes would have been 37.5% instead of 29.4% as in Fig. 4). Bothcurves in Fig. 4 display a plateau during the first few minutes due to the delay between thehit of the grenade harpoon and the use of the secondary killing method. The median delay
was 5.8 minutes for harpooning and 4.3 minutes for lancing.
Fig. 5 presents a similar comparison between the two secondary killing methods, but only
for the 123 whales which were randomised between the two methods. The median survival
time for the harpooned whales was 8.4 minutes and for the lanced whales 6.1 minutes. The
difference is statistically significant at the 1% level.
Fig. 6 shows the survival curve after application of the electric lance in the lanced group

Fig. 5. Survival plots comparing the harpoon and lance as secondary killing methods as in Fig. 4, but
only for the 123 whales which were randomised between the two methods. Median survival time for the
harpooned group (n=58): 8.4 (7.5–9.3) minutes, for the lanced group (n=65): 6.1 (5.5–6.7). The difference between the two survival curves is statistically significant (p=0.002, Mantel-Cox test, two-sided).

Fig. 6. Survival plots displaying the killing times for the two secondary killing methods. The abscissa isthe time after the application of the secondary killing method. The median survival time for the lance was
0.7 (0.5–0.7) minutes (n=326). The median survival time for the cold harpoon was 4.7 (3.5–5.2) minutes(n=234). Harpoon whales were censored if and when the electric lance was applied (53 censored).

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and the survival curve after being hit by the cold harpoon for the harpooned group. Harpooned whales were censored if and when the electric lance was used. The median killing
time for the electric lance was 40 seconds. The cold harpoon killed 32% of the whales instantaneously, but even so the median killing time was 4.7 minutes. Removal of lost andrecaptured whales from the harpooned group (35 whales) or addition of killing times in cases
where the lance was used following one or more cold harpoons (123 whales) did not change
the median survival times or their 95% confidence intervals, nor were there any noticeablechanges in the survival plots.
Fig. 7 is identical to Fig. 6, except that only times to death for the 123 randomised whales
are plotted. Results from the same 123 whales are also plotted in Fig. 8, the only difference
being that harpooned whales which were later stunned by the lance have not been cen-Fig. 7. Survival plots comparing the killing times for harpoon and lance as in Fig. 6, but only for the
123 whales which were randomised between the two methods. Harpooned whales were censoredas in Fig. 6 (17 whales—29%). Median killing time for the cold harpoon was 1.6 (0.3–4.7) minutes(n=58), and for the electric lance 1.0 (0.7–1.5) minutes. The difference between the two survival
curves is statistically significant (p=0.01, Mantel-Cox test, two-sided).

Fig. 8. Survival plots comparing harpoon and lance as in Fig. 7, but without censoring. Some of thewhales in the harpooned group were therefore in reality killed by the electric lance after the cold
harpoon had been used. Median killing time for the cold harpoon was 1.5 (0.3–2.3) minutes (n=58),
and for the lance 1.0 (0.7–1.5) minutes (as in Fig. 7). The difference between the two survival
curves is statistically significant (p=0.02, Mantel-Cox test, two-sided).
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Fig. 9. Estimated survival curves after the onset of electrical stunning based on Cox regression for
selected values of three covariates (whale length, voltage and amperage).
Solid line: 5 m, 110 V, 5 A.
Long dash: 5 m, 110 V, 10 A.
Dot—dash: 5 m, 220 V, 5 A.
Short dash: 10 m, 110 V, 5 A.

sored, but contribute the actual times of death to the statistics. This comparison corresponds
to what is known as ‘intention to treat’ in medical applications of statistics. ­The differences
displayed in both figures are statistically significant at the 1% level.
Whale length was the only covariate which influenced both the time to death from a hit bya grenade harpoon and the time to death from either a hit by a cold harpoon or from the onset of electrical stunning. The strength of this influence was similar in all subgroups and forboth secondary killing methods, and is illustrated in Fig. 9. This figure also reveals the effectof voltage and amperage on the time to death from the onset of stunning. None of the other covariates recorded had any influence on the time to death, or on the fraction of whales
which were killed instantaneously by a grenade harpoon. Nor were there any significant differences in killing efficiency between the six gunners.

Discussion
About one quarter of the whales taken in Japanese scientific whaling operations during thelast two years died instantaneously from a hit by a grenade harpoon. Most of the remaining
whales died within 15 minutes, either from injuries caused by the grenade or after the use of
one of the two secondary killing methods available to the whalers, i.e. to shoot a cold harpoon into the whale or to use the electric lance.
The percentage of whales killed instantaneously is certainly an underestimate. There is
general agreement that the death criteria for whales agreed in 1980 (IWC/33/15) are toostrict (IWC/47/18), since there is no reason to believe that minke whales do not show agonal
movements caused by spinal reflexes, seizures and convulsions similar to those in othermammals. Thus, some whales may very well have been dead or at least unconscious before
a secondary killing method was used.
The similarity between the results obtained in different seasons and regions (Fig. 2) showsthat the efficiency of Japanese killing methods is not much affected by differences in hunting
conditions and environment.

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Fig. 3 suggests that the death rate for whales which survived the first hit would have beenvery low if no secondary killing method had been employed.
Fig. 4 clearly shows that given the way the secondary killing used by the whalers, thelance kills whales much faster than the cold harpoon. However, the difference between thetwo curves may be caused entirely or partly by selection bias. In Fig. 5 the difference issmaller, but it is still present and statistically significant. In this ‘experimental’ group of whales
the animals were randomised between the two secondary killing methods. We may therefore
safely conclude that the lance kills the whales faster than the cold harpoon.
The lance curve in Fig. 5 (‘experimental’ group) is very similar to the lance curve in Fig. 4,
but delayed by about one minute. This may be because whales which were too close to theboat could not be shot with a cold harpoon and were therefore excluded from the experimental (randomised) group.
A clear difference between the two methods is also revealed in Figs. 6, 7 and 8, whichshow plots of survival against the time from firing the cold harpoon or switching on the current. Again, the plots show that the electric lance kills the whales faster than the cold harpoon.
The most interesting result presented in these figures, however, is how fast the electric
lance kills whales. The median time to death is about 40 s, and only some 5% of the animals
survive more than 3 minutes (n=326, but n=449 gives the same result). The Japanese Government reported a mean time to death of 44 s based on 92 of these whales (IWC/47/WK11),
which is in full agreement with the results from the present analysis.
The effect of covariates on the time to death from the onset of electrical stunning is illustrated in Fig. 9. The figure shows that the expected median killing time for a 10 m minke
whale is about twice that for a 5 m whale, if the values of the other covariates are the same.
This dependence on the size of the whale is not unexpected.
The electric lance operates as a constant voltage system, which means that the amperage
is mainly determined by the resistance between the two electrodes. Fig. 9 shows that thekilling time decreases as the voltage increases. The effect of amperage is perhaps more unexpected, as the killing time increases with increasing current between the electrodes. A possible explanation is that a high amperage is a result of current shunts between the electrodesin the seawater on the outside of the whale (or in seawater in the thorax and abdomen),which cause less current to flow through the tissues.
In last year’s Workshop on Whale Killing Methods, Blackmore claimed that the electric
lance could not “cause cardiac fibrillation except in a small minority of cases” (IWC/47/WK
2 and IWC/47/18), and recently New Zealand and the United Kingdom have repeated thisclaim in a note to IWC commissioners (1996) and in a summary (IWC/48/WK 1) of a paper
in press (Blackmore et al. 1996), which refers to another paper in press by the same groupof authors (Barnes et al. 1996). Although Blackmore’s electrical measurements on carcasses
and theoretical calculations may be of interest in some contexts, they are not relevant to an
analysis of the effectiveness of the electric lance. The empirical evidence that the lance kills
quickly is overwhelming.
Acknowledgements

All data used in the analysis were provided by the Fisheries Agency, Government of Japan, under a research
agreement between the author and the Fisheries Agency. Thanks are due to Mr. Masayuki Komatsu and Mr.
Nobuyuki Yagi, Fisheries Agency, Government of Japan, who were instrumental in arranging this joint investigation, and to Ms. Maki Watabe, Institute for Cetacean Research, Japan, who was extremely helpful in preparing
the data files according to my instructions. Mr. Nobuyuki Yagi, Mr. Hajime Ishikawa and Dr. Egil Øen all provided
valuable feedback on an early version of the manuscript.

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References
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United Kingdom: Review of progress on the implementation of the Action Plan addressing humane killing (Prepared and presented by C. Lockyer), 1995, IWC/47/WK1.
Barnes, G.R.G., Madie, P. and Blackmore, D. K.: Further investigations relevant to the use of the electric lance inwhaling, 1995, IWC/47/WK2.
Øen, E.O. and Walløe, L.: Hunting methods for minke whales in Norway—Results of scientific and traditional
whaling in 1994, 1995, IWC/47/WK9.
IWC/47/WK11 Government of Japan: Report on killing method for the 1994/95 Antarctic minke whale research
operations, 1995.
New Zealand and United Kingdom: Note on The electric lance, 1996.
Blackmore, D.K., Madie, P. and Barnes, G.R.G.: “Summary of the paper “Observations on the electric lance andthe welfare of whales: New facts and a critical appraisal,” 1996, IWC/48/WK1.
Blackmore, D. K., Madie, P. and Barnes, G.R.G.: “Observations on the electric lance and the welfare of whales:
New facts and a critical appraisal,” Animal Welfare, in press, 1996.
Barnes, G.R. G., Madie, P. and Blackmore, D.K.: “An assessment of the humane aspects of the electric lancingof whales by measurements of current densities in the heart and brain,” Medical & Biological Engineering &Computing, in press, 1996.
Dixon, W.J. “BMDP statistical software manual,” Vol 1 & 2, University of California press, Berkeley, 1990.

Received: November 26, 2020

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REMEMBERING DR. SEIJI OHSUMIREMEMBERING DR. SEIJI OHSUMI:A DREAM FOR ESTABLISHING A RESEARCH CENTER
OF MARINE MAMMALS IN THE INDIAN OCEAN
Nobuyuki MIYAZAKI1
Atmosphere and Ocean Research Institute, The University of Tokyo,
5–1–5 Kashiwanoha, Kashiwa, Chiba 277–0882, Japan
Corresponding author: nmiyazaki2184@gmail.com

Dr. Hiran Wasantha Jayewardene, adviser to the Minister of Strategic Planning and Development in
the Democratic Socialist Republic of Sri Lanka invited me and Dr. Seiji Ohsumi to the International
Workshop of Marine Mammals to be held at Colombo in Sri Lanka during 5–9 April 2003. He, thenephew of Mr. Junius Richard Jayewardene who was the second President of Sri Lanka, had a chal-Fig. 1. International Workshop of Marine Mammals held in Colombo, Sri Lanka during 5–9 April
2003.

Fig. 2. Group photo taken with staﬀ of the Sri
Lanka National Aquatic Resources Research andDevelopment Agency (NARA).

Fig. 3. Photo taken with Mr. Tyronne Fernando,
Minister Foreign Aﬀairs of Sri Lanka: Author,
Minister of Foreign Aﬀairs of Sri Lanka, Dr. Ohsumi, and Dr. Jayewardene (left to right).

Fig. 4. Photo taken with Sir Arthur Charles Clarke:
Dr. Ohsumi, Sir Clarke, and Author (left to right).

1

Professor Emeritus, AORI/UT.

Cetacean Popul. Stud. (CPOPS), Others
Vol. 3, 2021, 317–318

317

MIYAZAKI

lenging idea to improve the economy through ecotourism such as whale watching and to establish
peace and stability at Trincomalee in the northeastern Sri Lanka, where a lot of refugees had illegally
moved from neighboring India.
Sri Lanka is located in one of the most valuable and important areas for geopolitical and scientiﬁcstudy in the Indian Ocean. Thus the establishment of a “Research Center of Marine Mammals in the
Indian Ocean” would be very useful for mutual collaboration in marine science between Japan and Sri
Lanka. In the workshop, we exchanged signiﬁcant scientiﬁc information on the behavior of marine
mammals and their environmental condition and discussed a cooperative research plan and education
system for young scientists between Japan and Sri Lanka (Fig. 1).
Since the Conference on the Treaty of Peace with Japan was held in San Francisco on 4 September
1951, Japan has had a close relationship with the Democratic Socialist Republic of Sri Lanka (thenknown as Ceylon). In spite of attack by the Japanese navy to Colombo and Trincomalee in 1942, Mr.
Junius Richard Jayewardene, who participated in the conference as a representative of Ceylon, madea historically impressive speech including the following words: “Hatred ceases not by hatred but bylove” and “Sri Lanka didn’t receive any war reparation from Japan”, and did not oﬃcially request to
Japan for the World War II Reparations. Up to this day, the Japanese government has been continuing
strong support Sri Lanka through the program of Oﬃcial Development Assistance (ODA).
After the workshop on marine mammals, Dr. Hiran W. Jayewardene took us on a trip to Trincomalee, where many species of marine mammals such as sperm whales and blue whales often cameclose to the coast of this area and the people enjoyed whale watching from the cliﬀ on a hill. In addition, as this place is close to the naval station of Sri Lanka, this area is considered to be the best
location for improving marine science including whales’ observation and their environmental study in
the Indian Ocean. This area is also a memorial place for us, where the late Professor Masaharu Nishiwaki, Director of the Ocean Research Institute of the University of Tokyo, attended the International
Conference of Dugong dugon in 1972. On the way back to Colombo, we visited the National Aquatic
Resources Research and Development Agency (NARA), where a lot of skull and skeleton samples ofthe stranded marine mammals were preserved and discussed future research of marine science there(Fig. 2).
In order to encourage research activity of marine science with mutual collaboration between Japanand Sri Lanka, Dr. Ohsumi, Dr. Jayewardene and I oﬃcially met Mr. Tyonne Fernando, the Ministerof Foreign Aﬀairs at the time (Fig. 3). Through fruitful discussion with him, we obtained a good feeling for the future research plan on marine mammals with mutual collaboration of both countries. As
the support program of ODA was one of the most useful ways for establishing our plan, Mr. Seiichiro
Otsuka, Ambassador of Japan, advised us to submit our research plan to the Japanese government
through the government of Sri Lanka. However, in 2005 the government of Sri Lanka started to ﬁercely ﬁght again against the anti-government group of Tamil (LTTE), thus our plan had to be stopped
unfortunately. Now, as the Democratic Socialist Republic of Sri Lanka becomes a peaceful and politically stable country, it is just time for establishing the cooperative research plan on marine mammals
between Japan and Sri Lanka.
Finally, we met the late Sir Arthur Charles Clarke, a famous writer of science ﬁction and fantasy,
and talked about our dream (Fig. 4). He had great interest in the “Biologging Science”, through which
we can obtain wonderful knowledge of marine mammals and their environmental condition without
killing animals. He strongly recommended that we should improve the new science and supply the
fantastic knowledge to the public people in not only both countries but also all over the world. Now, it
is just time to realize our dream of establishing a “Research Center of Marine Mammals in the Indian
Ocean” under the brilliant spirit of the late Dr. Seiji Ohsumi.
Press hands in prayer.

318

Cetacean Popul. Stud. (CPOPS), Others
Vol. 3, 2021, 317–318

ARCHIVAL INDEXCETACEAN POPULATION STUDIES, TOKYO, JAPAN
Volume 3, December 2021
Kato, H., Fujise, Y., Nakamura, G., Hakamada, T., Pastene, L. A. and Best, P. B. Dwarf minke whales:
Morphology, growth and life history based on samples collected from the higher latitudes in theSouthern Hemisphere 93–128.
Pastene, L. A., Goto, M., Taguchi, M. and Matsuoka, K. Genetic matches of southern right whalesin the Indian sector of the Antarctic: A Contribution towards understanding their movement andsite-ﬁdelity 129–138.
Ohashi, Y., Goto, M., Taguchi, M., Pastene, L. A. and Kitakado, T. Evaluation of a paternity method
based on microsatellite DNA genotypes for estimating the abundance of Antarctic minke whales(Balaenoptera bonaerensis) in the Indo-Paciﬁc region of the Antarctic 139–151.
Taguchi, M., Goto, M., Milmann, L., Siciliano, S., Tiedemann, R. and Pastene, L. A. New insights into
the genetic structure of sei whales (Balaenoptera borealis) at the inter-oceanic scale 152–163.
Katsumata, T., Hirose, A., Nakajo, K., Shibata, C., Murata, H., Yamakoshi, T., Nakamura, G. andKato, H. Evidence of winter migration of humpback whales to the Hachijo island, Izu Archipelagooﬀ the southern coast of Tokyo, Japan 164–174.
Takahashi, M., Nakamura, G. and Kato, H. Growth-related changes in the cranium of killer whales in
the western North Paciﬁc 175–188.
Lockyer, C. and Garrigue, C. Age estimation from teeth in Longman’s beaked whales (Indopacetus
paciﬁcus) stranded in New Caledonia (South Paciﬁc) 189–197.
Isoda, T., Matsuoka, K., Tamura, T. and Pastene, L. A. Spatial and temporal distribution of ﬂoating
marine macro debris in the Indo-Paciﬁc region of the Antarctic 198–211.
Nakamura, G., Zenitani, R., Bando, T., Fujise, Y., Yamamoto, R., Nishimura, F., Hirose, A., Kim, Y.
and Kato, H. Skeletal measurements on some large cetacean species done by scientists of TUMSAT
and ICR 215–230.
Kim, Y., Nishimura, F., Bando, T., Fujise, Y., Nakamura, G., Murase, H. and Kato, H. Fetal development in tail ﬂukes of the Antarctic minke whale 231–238.
Bando, T. Improved estimates of some life-history parameters of the pelagic subspecies of Bryde’s
whale in the western North Paciﬁc 239–245.
Maeda, H. and Kato, H. Seasonal changes in the earplug germinal layers of North Paciﬁc common
minke whales 246–251.
Matsuoka, K., Hakamada, T. and Miyashita, T. A note on recent surveys for right whales Eubalaena
japonica in the western North Paciﬁc 252–257.
Diallo, S. T., Sane, A., Nelson, T., Katsumata, T. and Hakamada, T. Cetaceans oﬀ Gabon based on a2011 sighting survey, with a preliminary density estimate of the humpback whale Megaptera novaeangliae 258–264.
Sekiguchi, K. Historical Japanese whale sighting surveys in the Chukchi Sea 265–272.
Katsumata, E., Naruse, S., Hosono, T. and Katsumata, H. Sexual dimorphism in the dorsal ﬁn of
Paciﬁc white-sided dolphins (Lagenorhynchus obliquidens) from coastal waters oﬀ Japan 273–280.
Konishi, K. and Tamura, T. Preliminary use of near-infrared spectroscopy to estimate the biochemicalcomponents of the muscles of the Antarctic minke whale Balaenoptera bonaerensis 281–285.
Isoda, T., Tamura, T. and Pastene, L. A. Ingestion of marine debris and evidence of entanglements involving Antarctic minke whales (Balaenoptera bonaerensis) sampled in the Indo-Paciﬁc sector of
Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 319–320

the Antarctic 286–294.
Akamatsu, T. A short review of acoustic monitoring of large whales in Japanese waters 297–300.
Kaji, K. Impact of whale resource management research on sika deer management 301–304.
Walløe, L. An analysis of Japanese whale killing data with special emphasis on the use of the electric
lance as a secondary killing method 307–316.
Miyazaki, N. Remembering Dr. Seiji Ohsumi: A dream for establishing a research center of marine
mammals in the Indian Ocean 317–318.

Volume 2, June 2020
Goto, M., Kitakado, T., and Pastene, L. A. A preliminary study of epigenetic estimation of age of the
Antarctic minke whale Balaenoptera bonaerensis 5–14.
Matsuoka, K., and Hakamada, T. Density distribution of several major whale species in the Indo-Paciﬁc region of Antarctic using JARPA and JARPAII sighting data obtained through 1987/88–
2008/09 seasons 15–38.
Yasunaga, G., and Fujise Y. Concentration of persistent organic pollutants (POPs) in three species ofbaleen whales in the western North Paciﬁc 39–53.

Volume 1, December 2018
Kishiro, T. Satellite tracking of coastal Bryde’s whales Balaenoptera edeni along the southwest coastof Japan 3–13.
Nakamura, G., Ryeng, K. A., Kadowaki, I., Hayashi, R., Nagatsuka, S., Hirose, A., Fujise, Y., andHaug, T. Comparison of shapes of the white ﬂipper patch between two sub-species of common minke whales (Balaenoptera acutorostrata) 15–24.
Hirose, A., Kishida, T., and Nakamura, G. Nasal mucosa resembling an olfactory system in the common minke whale (Balaenoptera acutorostrata) 25–28.

Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 319–320

SUBJECT INDEX

accumulation rate 3: 246–251
adaptive management 3: 301–304
age determination 3: 246–251
age estimation 2: 5–14, 3: 189–197
allometry 3: 273–280
Antarctic 2: 15–38, 3: 129–138, 3: 198–211, 3: 286–294
Antarctic minke whale 2: 5–14, 2: 15–38, 3: 139–151, 3: 231–238, 3: 281–285, 3: 286–294
Balaenoptera acutorostrata 1: 15–24
Balaenopteridae 3: 215–230, 3: 231–238
baleen whale(s) 1: 25–28, 2: 15–38
blue whale 2: 15–38
Bryde’s whales 2: 39–53, 3: 239–245
Chukchi Sea 3: 265–272
coastal Bryde’s whale 1: 3–13
Cox regression 3: 307–316
common minke whale 1: 15–24, 2: 39–53, 3: 246–251
control region 3: 152–163
density estimation 3: 258–264
diminutive minke whale 3: 93–128
distance sampling 3: 258–264
distribution 2: 15–38, 3: 129–138, 3: 252–257
DNA methylation 2: 5–14
dorsal ﬁn 3: 273–280
dwarf minke whale 3: 93–128
earplug 3: 239–245, 3: 246–251
electric lance 3: 307–316
embryology 3: 231–238
entanglements 3: 286–294
epigenetics 2: 5–14
Eschrichtiidae 3: 215–230
Eubalaena japonica 3: 252–257
feedback management 3: 301–304
fetus 3: 231–238
ﬁshing buoy 3: 198–211
ﬁn whale 2: 15–38, 3: 297–300
ﬂipper 1: 15–24
ﬂuke 3: 231–238
Gabon 3: 258–264
genetic tagging 3: 129–138
germinal layer 3: 246–251
growth 3: 273–280
growth-related change 3: 175–188
Hachijo Island 3: 164–174
histology 1: 25–28
humpback whale 2: 15–38, 3: 164–174, 3: 258–264, 3: 297–300
Indopacetus paciﬁcus 3: 189–197
ingestion 3: 286–294
Japanese sighting survey 3: 198–211
Japanese whale sighting survey 3: 265–272
Kaplan–Meier plots 3: 307–316
killer whale 2: 15–38, 3: 175–188
Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 321–322

large whale 3: 215–230
large whale species 3: 265–272
life history parameter 3: 93–128, 3: 239–245
line transect 3: 258–264
lipid contents 3: 281–285
marine macro debris 3: 198–211, 3: 286–294
microsatellite DNA 3: 139–151
minke whale clade 3: 93–128
minke whales 3: 307–316
monitoring 3: 301–304
morphology 3: 93–128, 3: 273–280
morphometric 3: 215–230
movement 1: 3–13, 3: 129–138
muscle tissue 3: 281–285
nasal cavity 1: 25–28
North Paciﬁc 2: 39–53
North Paciﬁc right whale 3: 252–257
nutritional condition 3: 281–285
olfaction 1: 25–28
olfactory epithelium 1: 25–28
ontogeny 3: 231–238
organic pollutants 2: 39–53
Paciﬁc white-sided dolphin 3: 273–280
passive acoustic monitoring 3: 297–300
paternity analysis 3: 139–151
photo-ID 3: 164–174
phylogeography 3: 152–163
POPs 2: 39–53
population structure 3: 139–151
proxy of earplugs 2: 5–14
residency 3: 164–174
revised management procedure 3: 301–304
satellite tracking 1: 3–13
sei whale 2: 39–53, 3: 152–163
sighting survey 3: 252–257
sika deer 3: 301–304
site ﬁdelity 3: 129–138, 3: 164–174
skeletal measurement 3: 215–230
skull morphology 3: 175–188
subspecies 1: 15–24
southern bottlenose whale 2: 15–38
southern right whale 2: 15–38, 3: 129–138
sperm whale 2: 15–38, 3: 297–300
stock structure 3: 152–163
taxonomy 1: 15–24
teeth 3: 189–197
toothed whales 2: 15–38
underwater sound 3: 297–300
western North Paciﬁc 3: 175–188, 3: 239–245, 3: 252–257
whale 3: 301–304
whale killing methods 3: 307–316
white patch morphology 1: 15–24
wintering ground 3: 164–174
worldwide 3: 152–163
ziphioid whales 3: 189–197
Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 321–322

AUTHOR INDEXA
Akamatsu, T.

3: 297–300

B
Bando, T. 3: 215–230, 3: 231–238, 3: 239–245
Best, P. B. 3: 93–128

D
Diallo, S. T.

3: 258–264

F
Fujise, Y.

1: 15–24, 2: 39–53, 3: 93–128, 3: 215–230, 3: 231–238

G
Goto, M. 2: 5–14, 3: 129–138, 3: 139–151, 3: 152–163
Garrigue, C. 3: 189–197

H
Hakamada, T. 2: 15–38, 3: 93–128, 3: 252–257, 3: 258–264
Haug, T. 1: 15–24
Hayashi, R. 1: 15–24
Hirose, A. 1: 15–24, 1: 25–28, 3: 164–174, 3: 215–230
Hosono, T. 3: 273–280

I
Isoda, T.

3: 198–211, 3: 286–294

KKaji, K. 3: 301–304
Katsumata, E. 3. 273–280
Katsumata, H. 3: 273–280
Katsumata, T. 3: 164–174, 3: 258–264
Kadowaki, I. 1: 15–24
Kato, H. 3: 93–128, 3: 164–174, 3: 175–188, 3: 215–230, 3: 231–238, 3: 246–251
Kim, Y. 3: 215–230, 3: 231–238
Kishida, T. 1: 25–28
Kishiro, T. 1: 3–13
Kitakado, T. 2: 5–14, 3: 139–151
Konishi, K. 3: 281–285

Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 323–325

L
Lockyer, C.

3: 189–197

M
Maeda, H. 3: 246–251
Matsuoka, K. 2: 15–38, 3: 129–138, 3: 198–211, 3: 252–257
Milmann, L. 3: 152–163
Miyashita, T. 3: 252–257
Miyazaki, N. 3: 317–318
Murase, H. 3: 231–238
Murata, H. 3: 164–174

N
Nagatsuka, S. 1: 15–24
Nakajo, K. 3: 164–174
Nakamura, G. 1: 15–24, 1: 25–28, 3: 93–128, 3: 164–174, 3: 175–188, 3: 215–230, 3: 231–238
Naruse, S. 3: 273–280
Nelson, T. 3: 258–264
Nishimura, F. 3: 215–230, 3: 231–238

O
Ohashi, Y.

3: 139–151

P
Pastene, L. A.

2: 5–14, 3: 93–128, 3: 129–138, 3: 139–151, 3: 152–163, 3: 198–211, 3: 286–294

R
Ryeng, K. A.

1: 15–24

S
Sane, A. 3: 258–264
Sekiguchi, K. 3: 265–272
Shibata C. 3: 164–174
Siciliano, S. 3: 152–163

T
Taguchi, M. 3: 129–138, 3: 139–151, 3: 152–163
Takahashi, M. 3: 175–188
Tamura, T. 3: 198–211, 3: 281–285, 3: 286–294
Tiedemann, R. 3: 152–163

W
Walløe, L.

3: 307–316

Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 323–325

Y
Yamakoshi, T. 3: 164–174
Yamamoto, R. 3: 215–230
Yasunaga, G. 2: 39–53

Z
Zenitani, R.

3: 215–230

Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 323–325

Guide for Authors
CETACEAN POPULATION STUDIES (CPOPS) is an English peer reviewed on-line journal which
publishes scientiﬁc articles on cetaceans and other marine mammals in the form of (1) Original study– Full paper, (2) Original study – Short note, (3) Review of studies, (4) Photo gallery with explanatory note as well as (5) Others, subject to authorization by the Editor-in-Chief in advance of formal
submission. CPOPS welcomes contributions from accredited scientists in any country. Copyright forarticles published in CPOPS is transferred to CPOPS when the article is accepted for publication. Articles published in CPOPS may not be reproduced, in whole or in part, without written permission fromCPOPS. CPOPS does not charge any submission or publication fee.
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A Short note should be composed of important information or analyses which are also scientiﬁcallyorganized, but it is not necessary that the information is based on a suﬃcient number of samples orobservations. The short note contents do not need to be subdivided by sections as in the case of a full
paper. It should include an appropriate abstract (less than 100 words) and key words. The short noteshould not exceed 6 printed pages in length and include some thoughtfully selected tables and ﬁgures.
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When contributors are requested to revise their manuscripts, they can resubmit, within 30 days, therevised manuscript incorporating comments and suggestions by referees, together with an attachednote describing how the revision has been carried out. The ﬁnal decision on acceptance or rejection for
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Cetacean Popul. Stud. (CPOPS),
Vol. 3, 2021, 326