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 toward a 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 Scientific journal papers (including unpublished works presented to the International Whaling Commission Scientific Committee (IWC/SC)); 2.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 and other 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 in various 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 them among 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).

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 were collected 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.

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 and four 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 for males 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 on site fidelity and movement ranges will require a large number of biopsy samples genotyped, from both south and north of 60°S.

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 total abundance 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 both methods was slightly different. Additionally, the geographical locations of mother/fetus–father pairs provided the opportunity to evaluate the current hypothesis on population structure of this 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 distant areas. 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.

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 of samples (n=39 in NP and n=4 in SH). The haplotype (h) and nucleotide (π) diversities were higher 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 F_ST estimates support the difference between NA and the other two populations. Furthermore, except for one haplotype, there were no other shared haplotypes among the three oceanic regions, suggesting contemporary migration and gene flow 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. Based on a comparison of the inter-oceanic genetic structure and phylogeny of the sei whales with those of fin whales, which is another cosmopolitan baleen whale species, it is suggested that the genetic structure of sei whales reflects occasional gene flow between the Northern and Southern hemispheres and/or incomplete lineage sorting, similar to the case of fin whales.

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 Japan for 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 the island 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 in the first season and from November to April in the second season, and a total of sightings of respectively 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 the second 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 composition of 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 around this island.

One of the crucial questions for using the skull morphology for classification purposes in cetaceans is whether the skull features have growth-dependent differences. This question was addressed by examining cranial specimens collected from killer whales in different localities of 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 kinds of 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 these analyses, an allometric equation was used. The relationship between BL and CBL showed a negative growth pattern, consistent with previous studies in delphinid species. The length of the 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, the zygomatic process and the space where the temporal muscle passes became proportionally larger 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.

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 the wafer at 10–25 µm and staining with Ehrlich’s acid haematoxylin. GLGs were investigated in both 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.

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 the floating 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, the marine macro debris data were divided into IWC management Areas IIIE, IV, V and VIW as well as 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 most frequent 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 macro debris 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 the number of fisheries and tourist activities in the Antarctic.

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).

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 qualitative in 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) and retained 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.

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 L_t=12.65 (1−e^{−0.189 (t+5.250)}) and L_t=13.30 (1−e^{−0.170 (t+4.929)}) for males and females, respectively. The mean age at sexual maturity was estimated 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.

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 for age 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 pale lamina accumulated during an approximately six-month period from spring to autumn in their feeding 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.

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) and the 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 Pacific right whales were distributed north of 42°N in the western North Pacific, including 10 mother and 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 increase since 1990’s, but it is necessary to carefully monitor this population in the future to check the trend. Further surveys, analysis and international collaboration are required to improve our understanding of this species.

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 species of 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 transect lines (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).

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 Maru data 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.

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 the ratios 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 of the dorsal fin.

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 calorimetric data 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 that the 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.

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 total of 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.

Passive acoustic monitoring studies of large whales in the Japanese EEZ are reviewed in this 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 were observed in the waters off Kushiro in the northern part of Japan. A scientific submarine cable in 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.

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 Conservation and 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.

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 the electric lance was 40 s and for the cold harpoon 4.7 minutes. The analyses showed that the electric 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 have been changed, and today the use of a shot from a rifle through the brain of the whale is the preferred secondary killing method.