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, JapanFisheries 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
12Abstract
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 of45°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 southeastof 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 ofthe 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) fromApril 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 PaciﬁcSch.

Ind.

CalfMss

SST (°C)

Photo-ID

Biopsy sample

19941995
1997
1998
2001
2002
2003
2004
2005
2006
2007
2008
2009
2011
2012
2013
2014
2015

12
2
4
2
2
5
2
2
11
15
1132
1
1
3

2
2
3
6
3
2
6
4
4
15
1
6
120
2
1
14

100
2
10
10
2
00
10
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
2.3–2.42115304321104118211
10000001222040
14
1002

Total

60

83

101.38

2.3–17.060

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 Augustbetween 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.
YearSea of Okhotsk and western North PaciﬁcSch.

Ind.

MssSST

1984
1990
1991
1992
2003

22
1
17134
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 theprimary 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.
Year1998
2000
2003
2009
2010
2011

254

Sea of Okhotsk
Sch.

Ind.

CalfMss

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

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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 theSea 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 afterApril 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 the1960’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.
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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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Cetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 252–257A NOTE ON RECENT SURVEYS FOR RIGHT WHALESAcknowledgements

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 toDr. 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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