Technical Reports of the Ins�tute of Cetacean Research (2022)

pp. 36–45

Technical Report (not peer reviewed)

Report and highlights of the dedicated sigh�ng surveys in thewestern North Paciﬁc Ocean in 2021
Taiki Katsumata* and Koji Matsuoka
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Contact e-mail: katsumata@cetacean.jp

ABSTRACT

Vessel-based sigh�ng surveys were conducted in 2021 by the Ins�tute of Cetacean Research to examine the
distribu�on and abundance of whales in the western North Paciﬁc Ocean. The research area was between
30°N–53°N and 150°E–155°W. The surveys were conducted between 4 August and 30 September, and two
research vessels, Yushin-Maru and Kaiyo-Maru No.7, were engaged in the surveys. A total of 3,713.8 n.miles
was searched by the passing mode in the research area. Coverage of the searching eﬀorts on the planned
cruise track line was 70.4%. In total, seven large whale species, including blue (17 schools/20 individuals), ﬁn(78/124), sei (102/156), Brydeʼs (57/72), common minke (1/1), humpback (13/16) and sperm (94/193) whales
were sighted during the research period. Photo-ID images were collected from blue (12 individuals), humpback (5 individuals) and sperm (1 individual) whales. Biopsy skin samples using a Larsen system were collectedfrom blue (n=1), ﬁn (n=5), sei (n=15) and humpback (n=3) whales. The density indices of blue and ﬁn whales
have increased notably since the last survey in the same research area 10 years ago. Furthermore, Bryde's andhumpback whales, which were not detected in the previous surveys, were sighted in the 2021 surveys.

INTRODUCTION
Dedicated cetacean sigh�ng surveys in the western North
Paciﬁc have been conducted in the summer season since
1995, as a part of the Japanese Whale Research Program
under Special Permit in the western North Paciﬁc (JARPN/
JARPNII) and the New Scien�ﬁc Whale Research Programin the western North Paciﬁc (NEWREP-NP), based on thesurvey procedures of the Interna�onal Whaling Commission/Southern Ocean Whale and Ecosystem Research(IWC/SOWER) (Anon, 2008). Based on the data collectedfrom those surveys, the distribu�on pa�erns of large
whales such as blue, ﬁn, sei, Bryde's, common minke,
humpback, North Paciﬁc right and sperm whales, andabundance es�mates of common minke, sei, and Bryde's
whales were inves�gated and reported to the IWC Scien�ﬁc Commi�ee (SC) (IWC, 2001; 2010; 2016).
The Fisheries Resources Ins�tute (FRI) has also conducted dedicated sigh�ng surveys for cetaceans in the
North Paciﬁc Ocean since the 1980s (Buckland et al.,
1992; Miyashita et al., 1995; Miyashita and Kato, 2004;
Shimada, 2004; Kanaji et al., 2012). In 2019, the Government of Japan decided to con�nue the sigh�ng surveys
in the North Paciﬁc (IWC, 2019) under the ra�onale thatthe collec�on of sigh�ng data to es�mate abundance
36

and biopsy/photo-iden�ﬁca�on data to examine stock
structure have contributed in the past to the work on the
management and conserva�on of large whales by the
IWC SC (IWC, 2016).
This paper reports the results of the latest Japanese
dedicated sigh�ng surveys conducted by the Ins�tute of
Cetacean Research (ICR) between 4 August and 30 September 2021.

SURVEY DESIGN
Research vessels
The surveys in 2021 were conducted by the research vessels Kaiyo-Maru No.7 (KY7) and Yushin-Maru (YS1). The
vessels were equipped with a top barrel pla�orm (TOP),
IO barrel pla�orm (IOP) and upper bridge. Speciﬁca�onsof these vessels are shown in Figure 1.
Research period and area
In 2021, surveys were conducted in late summer (August
to September), and the research areas were between
30°N–40°N and 150°E–180°for KY7, and between 40°N–
53°N and 180°–155°W for YS1 (Figure 2).
Track line design
The pre-determined track lines in the research area areReport and highlights of the dedicated sighting surveys in the western North Pacific Ocean in 2021

Figure 1.

Figure 2.

Research vessels Kaiyo-Maru No.7 (KY7) (le�) and Yushin-Maru (YS1) (right).

Research areas of the 2021 sigh�ng survey held from August to September. KY7 covered the green area,
and YS1 covered the blue area.

shown in Figure 2. The start point of the track lines were
decided randomly using the “Distance program ver. 7.0”
(Thomas et al., 2010), and the number of the line transects was decided by considering the research scheduleand based on the IWC survey guidelines (IWC, 2012).
Sigh�ng procedures
The sigh�ng survey was conducted using (1) Normal Passing mode (NSP) and (2) Passing with Independent Observer mode (IO). Data obtained under the IO mode areuseful for future es�ma�ons of g(0). Both survey modes
followed the protocol endorsed for the SOWER surveys(e.g. Matsuoka et al., 2003; Anon, 2008; IWC, 2012).
For NSP mode, there were two primary observers
on the top barrel pla�orm (TOP) and two (captain andhelmsman) on the upper bridge. All primary observers
engaged in the searching ac�vity for cetaceans by using
angle board and scaled binoculars (7×).
For IO mode, there were two primary observers on
the TOP and two on the IO barrel pla�orm (IOP). Theseobservers conducted the searching ac�vity for cetaceans

by using angle board and scaled binoculars (7×). There
was no open communica�on between the IOP and theTOP. The observers and researchers on the upper bridge
communicated to the TOP (or IOP) independently only toclarify informa�on, and did not distract the top-men fromtheir normal searching procedure. These primary observers report sigh�ng-informa�on to researchers and otherobservers on the upper bridge for data recording.
The sigh�ng survey eﬀort began 60 minutes a�er
sunrise and ended 60 minutes before sunset, with amaximum of 12 hours per day when the weather condi�ons were acceptable for observa�ons: visibility be�erthan 2.0 n.miles and wind speed less than 21 knots. The
searching speed was planned to be 10.5 to 11.5 knots
with slight adjustments to avoid vibra�on of the vessel.
Experiments
Distance and angle experiments were conducted in the
middle of the survey period. The experiment was conducted to evaluate measurement error, and followed theprotocol of the IWC/SOWER and IWC-POWER surveys
37

Technical Reports of the Ins�tute of Cetacean Research (2022)
Table 1
Summary of the survey periods and searching eﬀort in each research area.
Research period

Planned cruise
track(n.miles)Searching eﬀort
NSP(n.miles)Searching eﬀort
IO(n.miles)Searching eﬀort
Total(n.miles)Coverage of
eﬀort
(%)

2021/08/11–08/21

1,226.1

455.1

470.7

925.8

75.5

2021/08/30–09/09

1,392.5

533.1

534.4

1,067.5

76.7

YS1

2021/08/18–09/20

2,658.6

752.3

968.2

1,720.5

64.7

Total

–

5,277.2

1,740.5

1,973.3

3,713.8

70.4

VesselKY7Table 2
Numbers of sigh�ngs of large cetaceans, by species and research vessel in the 2021 surveys.
VesselSpeciesBlue whale
Fin whale
Sei whale
Brydeʼs whale
Common minke whale
Humpback whale
Sperm whale

Transit(Including both vessels)
Prim.

Second.

KY7(150°E–180°)
Prim.

YS1
(180°–155°W)

Second.

Prim.

Total

Second.

Prim.

Second.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

0
8
1
12
0
0
32

0
13
1
20
0
0
72

0
0
0
1
0
0
3

0
0
0
1
0
0
5

0
1
0
20
0
0
34

0
1
0
25
0
0
90

0
0
0
0
0
0
0

0
0
0
0
0
0
0

17
66
98
24
1
11
24

20
107
146
26
1
13
25

0
3
3
0
0
2
1

0
3
9
0
0
3
1

17
75
99
56
1
11
90

20
121
147
71
1
13
187

0
3
3
1
0
2
4

0
3
9
1
0
3
6

Prim.: primary sigh�ng, Second.: secondary sigh�ng, Sch.: school, Ind.: individual.

(IWC, 2012).
When large cetaceans such as blue and humpback
whales were found, photo-ID images were obtained using
Canon EOS 7D Mark II (with 100–400 mm lens) from thebow or upper deck. Further, biopsy skin sampling using
the Larsen system (Larsen, 1998) was conducted when
blue, ﬁn, sei, humpback whales were sighted. A satellite
tagging experiment using the Air Rocket Transmi�er System (LK-ARTS) was also conducted for ﬁn and sei whales.

RESULTS
Brief narra�ve of the surveys
KY7 departed Shiogama, Miyagi, Japan on 4 August, andstarted the transit survey on 5 August. KY7 began the survey in the research area from the east on 11 August. KY7
paused the survey at 170°E on 21 August for a scheduled
port call, and entered Kushiro, Hokkaido, Japan, on 26
August for refueling and disembarka�on of researchers.
On 27 August, KY7 departed Kushiro, and reached theresume point at 170°E on 30 August. The survey was completed on 9 September. KY7 arrived in Shiogama, Miyagi
on 17 September.
YS1 departed Shimonoseki, Yamaguchi, Japan on 4
38

August, and started the transit survey on 6 August. On
18 August, YS1 reached the start point at 155°W, andcompleted the survey on 20 September. YS1 and arrived
in Shiogama, Miyagi, on 30 September.
Searching eﬀort
A summary of searching eﬀort and coverage by eachresearch vessel is shown in Table 1. A total of 3,713.8 n.
miles (6,878.0 km) were searched. The total searching effort by KY7 was 925.8 n.miles (1,714.6 km) (75.5% coverage) in the eastern part, and 1,067.5 n.miles (1,977.0 km)(76.7% coverage) in the western part. The total searchingeﬀort by YS1 was 1,720.5 n.miles (3,186.4 km) (64.7%
coverage).
Sigh�ngs
OverallSigh�ngs were summarized by each research vessel inTable 2 for large cetaceans and in Table 3 for small cetaceans.
There was a total of 349 schools sighted of seven large
whale species, involving 560 individual whales. The largest number of sigh�ngs was for sperm whales (in terms ofReport and highlights of the dedicated sighting surveys in the western North Pacific Ocean in 2021
Table 3
Numbers of sigh�ngs of small cetaceans, by species and research vessel in the 2021 surveys.
VesselSpecies
Killer whale
Melon-headed whale
Rissoʼs dolphin
Striped dolphin
Common dolphin
Paciﬁc white-sided dolphin
Northern right whale dolphin
True type Dallʼs porpoise
Dalli type Dallʼs porpoise
Unid. type Dallʼs porpoise
Ziphiidae
Mesoplodon spp.

Transit(Including both vessels)
Prim.

Second.

KY7(150°E–180°)
Prim.

YS1
(180°–155°W)

Second.

Prim.

Total

Second.

Prim.

Second.

Sch. Ind. Sch. Ind. Sch. Ind. Sch. Ind. Sch. Ind. Sch. Ind. Sch. Ind. Sch. Ind.
0
0
3
11
0
1
3
0
0
0
4
1

0
0
45
1,549
0
12
14
0
0
0
16
1

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

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

0
1
3
3
1
0
0
0
0
0
21
2

0
105
21
225
6
0
0
0
0
0
44
3

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

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

7
0
1
0
7
14
2
2
11
7
3
1

18
0
3
0
288
392
223
4
74
27
4
3

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

0
0
0
0
0
13
0
0
0
0
0
0

7
18 0
1
105 0
7
69 0
14 1,774 0
8
294 0
15
404 1
5
237 0
2
4 0
11
74 0
7
27 0
28
64 0
4
7 0

0
0
0
0
0
13
0
0
0
0
0
0

Prim.: primary sigh�ng, Second.: secondary sigh�ng, Sch.: school, Ind.: individual.

Figure 3.

The sigh�ng distribu�on of blue whales (blue circle) with the searching track of KY7 (blue line) and YS1(red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 was observed by MODIS-Aqua (Original data: Ocean color web, from h�ps://oceancolor.gsfc.nasa.gov/ (Accessed2022-7-18)).

number of individuals) and the smallest was for common
minke whales. The largest number of sigh�ngs in baleen
whales was for sei whales (Table 2).
In terms of small cetaceans, seven species were iden�ﬁed in the family Delphinidae, and one species wasiden�ﬁed in the family Phocoenidae. No species wereiden�ﬁed in the family Ziphiidae because of their elusive
behavior. The most common species sighted were striped
dolphins (14/1,774), followed by Paciﬁc white-sided dolphins (16/417) (Table 3).

Geographical distribution of sightings by cetacean species
Blue whale
The geographical distribu�on of the sigh�ngs is shown in
Figure 3 together with sea surface temperature. In total,
one mother and calf pair was sighted at posi�on 44°45ʹN,
174°43ʹW. The mean school size was 1.2 and the rangeof sea surface temperature (SST) at the sigh�ng posi�ons
was 11.5–19.7°C (mean SST: 16.3°C).
The density index (DI: schools sighted/100 n.miles
searching distance) based on primary sigh�ngs in the research area for YS1 was 0.99. The DIs were 0.15 and 0.48
39

Technical Reports of the Ins�tute of Cetacean Research (2022)

in the 2010 and 2011 IWC-POWER cruises, respec�vely,
which were conducted north of 40°N. The longitudinalranges of those cruises were 170°E–170°W and 170°W–
150°W, respec�vely (Matsuoka et al., 2011; 2012). It
should be noted that the survey period in 2021 was about

Figure 4.

40

A blue whale observed in the research area on 10
September 2021.

one month later than in the previous IWC-POWER surveys. The DIs suggest that the popula�on of blue whalesin the North Paciﬁc is increasing. A photograph of a blue
whale is shown in Figure 4.
Fin whale
The geographical distribu�on of the sigh�ngs is shown in
Figure 5 together with sea surface temperature. In total,
one mother and calf pair was sighted at posi�on 45°53ʹN,
174°00'W. Fin whales were distributed mainly throughout the research area surveyed by the YS1. The observed
mean school size was 1.6 and the range of SST at thesigh�ng posi�ons was 11.0–20.3°C (mean SST: 14.9°C).
The DI of YS1 was 3.84. The DI in the previous 2010 and2011 IWC-POWER surveys were 0.53 and 1.79, respec�vely (Matsuoka et al., 2011; 2012). As in the case of blue
whales, the DIs suggest that the ﬁn whale popula�on in
the North Paciﬁc is increasing.

Figure 5.

The sigh�ng distribu�on of ﬁn whales (red circle) with the searching track of KY7 (blue line) and YS1 (redline). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 was observedby MODIS-Aqua.

Figure 6.

The sigh�ng distribu�on of sei whales (orange circle) with the searching track of KY7 (blue line) and YS1(red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 wasobserved by MODIS-Aqua.

Report and highlights of the dedicated sighting surveys in the western North Pacific Ocean in 2021

Figure 7.

The sigh�ng distribu�on of Brydeʼs whales (green circle) with the searching track of KY7 (blue line) andYS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 wasobserved by MODIS-Aqua.

Figure 8.

The sigh�ng distribu�on of common minke whales (pink circle) with the searching track of KY7 (blue line)
and YS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021
was observed by MODIS-Aqua.

Sei whale
The geographical distribu�on of the sigh�ngs is shownin Figure 6 together with sea surface temperature. This
species was sighted north of 42°N in the survey area of
the YS1. No mother and calf pairs were observed. Highdensity was observed in the la�tudinal band between
47°N and 49°N (Figure 6). The observed mean school size
was 1.5 and the range of SST at the sigh�ng posi�ons was
10.9–17.4°C (mean SST: 12.6°C).
The DI of YS1 was 5.70. The DIs of the 2010 and 2011
IWC-POWER surveys were 3.55 and 2.21, respec�vely(Matsuoka et al., 2011; 2012). These values were smaller
than those found in the 2021 surveys.
Bryde's whale
The geographical distribu�on of the sigh�ngs is shownin Figure 7 together with sea surface temperature. One
mother and calf pair was observed at posi�on 41°03ʹN,
178°18'W. Bryde's whales were widely distributed lon-

gitudinally north of 30°N, which is similar to the pa�ern
found in previous surveys (Shimada, 2004; Hakamada
et al., 2017). Based on sigh�ng data by KY7, the observed
mean school size was 1.3, and the range of SST at thesigh�ng posi�ons was 21.4–29.7°C (mean SST: 27.2°C).
Based on sigh�ng data by YS1, the observed mean school
size was 1.1, and the range of SST at the sigh�ng posi�ons
was 17.5–20.7°C (mean SST: 20.1°C).
The DIs were 1.00 and 1.39 by the KY7 and YS1, respec�vely. Brydeʼs whales were not sighted north of 40°N
in the previous IWC-POWER surveys (Matsuoka et al.,2011; 2012), however in the 2021 surveys some sigh�ngs
were made north of that la�tude (Figure 7) The northern
most sigh�ng posi�on in these surveys was 42°36ʹN.
Common minke whale
The geographical distribu�on of the sigh�ngs is shown in
Figure 8 together with sea surface temperature. Only one
school (one individual) was sighted at 48°07ʹN, 161°34'W
41

Technical Reports of the Ins�tute of Cetacean Research (2022)

Figure 9.

The sigh�ng distribu�on of humpback whales (black circle) with the searching track of KY7 (blue line) andYS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 wasobserved by MODIS-Aqua.

in Figure 11 together with sea surface temperature. This
species was distributed widely in the research areas (Figure 11). The observed mean school size diﬀered markedly
between the research areas covered by the two vessels:
2.6 in the area covered by KY7 and 1.0 by the area covered by YS1.

Figure 10.

A humpback whale sighted at 40°N on 18
September, 2021.

in calm weather condi�ons. The SST at the sigh�ng posi�on was 12.5°C. Common minke whales are hard to ﬁnd
under harsh sea surface condi�ons because their small
blows are diﬃcult to detect in such condi�ons.
Humpback whale
The geographical distribu�on of the sigh�ngs is shownin Figure 9 together with sea surface temperature. No
mother and calf pair of this species were sighted. Sightings were made north of 40°N only in the area surveyed
by YS1 (Figure 9). The range of SST at the sigh�ng posi�ons was 10.7–20.7°C (mean SST: 13.8°C).
The DI based on primary sigh�ngs of YS1 was 0.64. In
previous surveys, humpback whales were not sighted
south of 47°N (Matsuoka et al., 2011; 2012). In the 2021
surveys, two schools were sighted around 40°N, and one
individual was photographed (Figure 10). A biopsy sample
was collected from this individual.
Sperm whale
The geographical distribu�on of the sigh�ngs is shown
42

Small cetaceans
The geographical distribu�on of the sigh�ngs of small
cetaceans is shown in Figures 12a and 12b together withsea surface temperature. Killer whales, Paciﬁc whitesided dolphins and Dall's porpoises were mainly sighted
north of 42°N, while common dolphins were sighted
primarily in the 40°N–42°N la�tudinal band. Striped dolphins were not sighted north of 40°N. These distribu�onpa�erns of small cetaceans were consistent with thosefound in the previous IWC-POWER surveys conducted ten
years ago (Matsuoka et al., 2011; 2012).
Duplicate sightings
A total of 31 and 96 duplicates of large cetaceans wererecorded during IO mode surveys by KY7 and YS1, respec�vely.
Experiments
Sighting distance and angle experiment
The Es�mated Angle and Distance Training Exercise wasconducted during the surveys using a buoy that resembles
a blow with a reﬂector. During the exercise, the observers
familiarized themselves with distance es�mates from theTOP, IO and Upper Bridge. The Es�mated Angle and Distance Experiment was conducted on 23 September by YS1
on 14 August by KY7. The results of this experiment will be
used for the calcula�on of abundance es�mates.

Report and highlights of the dedicated sighting surveys in the western North Pacific Ocean in 2021

Figure 11.

The sigh�ng distribu�on of sperm whales (inverted brown triangle) with the searching track of KY7 (blueline) and YS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September
2021 was observed by MODIS-Aqua.

Figure 12.

(a) The sigh�ng distribu�on of killer whales, Dallʼs porpoise, uniden�ﬁed Mesoplodon spp., and Ziphiidae
with the searching track of KY7 (blue line) and YS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 was observed by MODIS-Aqua. (b) The sigh�ng distribu�onof striped, common, Paciﬁc white-sided, northern right whale, Rissoʼs dolphin and melon-headed whalewith the searching track of KY7 (blue line) and YS1 (red line). Rolling 32 days average sea surface temperature from 13 August to 13 September 2021 was observed by MODIS-Aqua.

43

Technical Reports of the Ins�tute of Cetacean Research (2022)

Photo-ID
Photographs were taken of blue (n=12), humpback (n=5)
and sperm (n=1) whales. All photographs were stored in
the ICR catalog and will be used for inves�ga�ng stock
structure and movement of these species in the future.
Biopsy sampling
A total of 24 biopsy samples were collected from blue(n=1), ﬁn (n=5), sei (n=15) and humpback (n=3) whales.
All samples were stored at the ICR laboratory and will be
used in gene�c analyses to inves�gate stock structure ofthese species in the future.
Satellite tagging
Two ﬁn and nine sei whales were successfully tagged andtracked. Results of this experiment are shown in Konishi
and Isoda (2022).

HIGHLIGHTS OF THE SURVEY
The sigh�ng surveys conducted in 2021 were completed
successfully. They provided unique data for summer
months, as informa�on on cetacean distribu�on andabundance during summer have been very scarce. Somemain characteris�cs of the surveys are summarized
below.
The surveys in August–September covered the northern part of the central Paciﬁc, and provided importantsummer sigh�ng data for, ﬁn, sei, Brydeʼs and sperm
whales. These data will be used for the abundance es�ma�on of those species. At the same �me, it was conﬁrmed that blue, humpback and common minke whales
were also distributed in these areas, although in small
numbers.
The DI of blue, ﬁn and sei whales increased signiﬁcantly compared with previous IWC-POWER surveys conducted ten years ago. The distribu�on pa�ern of thesethree species overlapped in terms of the la�tudinal band
and SSTs (Figures 3, 5 and 6). The distribu�on pa�ern ofthese three species were consistent with those in theprevious surveys from ten years ago. On the other hand,the distribu�on of Brydeʼs and humpback whales were
diﬀerent. Ten years ago, Brydeʼs whales were not sighted
and humpback whales were sighted only north of 47°N.
The result of the 2021 surveys showed that Brydeʼs whale
distribu�on either expanded or shi�ed northward, andhumpback whale distribu�on expanded or shi�ed southward.
As with the previous surveys, the 2021 surveys collected data on small cetaceans in the same way as large
cetaceans. The analyses of these data will provide valu44

able informa�on on the distribu�on and abundance ofsmall cetaceans in diﬀerent seasons.

ACKNOWLEDGEMENTS
We thank Captains Chikamasa Okoshi, Yasuaki Sasaki,
and their oﬃcers and crew of the Yushin-Maru and KaiyoMaru No.7 for their hard work and dedica�on that led
to the successful implementa�on of these surveys. We
express our gra�tude to Takashi Hakamada and Megumi
Takahashi (ICR) for their assistance in survey design. We
thank Yoshihiro Fujise and Tsutomu Tamura and the staﬀ
of the ICR and Kyodo Senpaku Co. Ltd. for their arrangements and support for the survey. We also thank Kenji
Konishi (ICR) for satellite tagging and Mioko Taguchi (ICR)
for the management of biopsy samples. We thank Luis A.
Pastene (ICR) for his assistance in preparing this report.
We also thank the Editorial Team of TEREP-ICR for theeditorial work on this manuscript.

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Buckland, S.T., Ca�anach, K.L. and Miyashita, T. 1992. Minke
whale abundance in the northwest Paciﬁc and the Okhotsk
Sea, es�mated from 1989 and 1990 sigh�ng surveys. Rep. int.
Whal. Commn 42: 387–392.
Hakamada, T., Takahashi, M., Matsuoka, K. and Miyashita, T.
2017. Abundance es�mate for western North Paciﬁc Bryde's
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