Technical Reports of the Institute of Cetacean Research (2019)

pp. 41–51

Technical Report (not peer reviewed)

Distribution of blue, ﬁn, humpback and North Paciﬁc right whalesin the western North Paciﬁc based on JARPN and JARPNII surveys(1994–2014)
Koji Matsuoka* and Takashi Hakamada
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Contact e-mail: matsuoka@cetacean.jp

ABSTRACTThis paper examines the geographical and temporal patterns of distribution of blue, ﬁn, humpback and North
Paciﬁc right whales in the western North Paciﬁc. The analyses were based on sighting data collected systematically by JARPN and JARPNII surveys during May to September in the years 1994–2014. A total of 269,728.1 n.
miles was surveyed in the entire research period. The Density Index (No. of individual whales sighted/100 n.
miles) was calculated and its geographical and temporal (monthly) distribution plotted for each individual species. Fin whale was the species most frequently sighted, followed by humpback, blue and right whales. The
geographical and temporal pattern of distribution was described for each whale species. The large sighting
data set collected systematically by JARPN and JARPNII has made a substantial contribution to understanding
the pattern of geographical distribution and habitat use of whales in the western North Paciﬁc ecosystem.

INTRODUCTION
One of the main sources of sighting data for assessing the
population status of whale species in the western North
Paciﬁc was the JARPN, which was conducted between
1994 and 1999, and its second phase JARPNII conducted
between 2000 and 2014.
The sighting data collected by JARPN and JARPNII havebeen used for studying the distribution pattern and abundance estimation of several large whale species in thewestern North Paciﬁc (Okamura et al., 2001; Matsuoka
et al., 2009). Details of the sighting survey proceduresin JARPN and JARPNII are available in Fujise (2000) andTamura et al. (2009), respectively.
This technical report summarizes the Institute of
Cetacean Research (ICR)ʼs investigation of the pattern of geographical and temporal distribution of blue
(Balaenoptera musculus), ﬁn (B. physalus), humpback(Megaptera novaeangliae) and North Paciﬁc right(Eubalaena japonica) whales in the western North Paciﬁc.
The investigation was based on sighting data collected
systematically by JARPN and JARPNII surveys in the period
1994–2014.

MATERIALS AND METHODS
Research area
The research area comprised the western part of theNorth Paciﬁc, speciﬁcally the International Whaling
Commission (IWC) management sub-areas 7, 8, 9 and
11 (used for management of the common minke whale),north of 35°N, excepting the 200 n.mile EEZʼs of foreigncountries (Figure 1).
Sighting data
Primary sighting and eﬀort data were collected by JARPN(1994–1999) and JARPNII (2000–2014) systematic surveys. Surveys were conducted by sighting and sampling
vessels (SSV) (vessels engaged in sighting and sampling ofwhales) and dedicated sighting vessels (SV) (vessels engaged only in sighting of whales). Sighting data obtainedby SSVs and SVs were combined for the calculation of theDensity Index (see below).
Sighting procedures
The sighting procedures for SSVs and SVs in JARPNII(2000–2014) was not signiﬁcantly changed with regard the procedures in JARPN (1994–1999) with only
some minor changes made (see details in Matsuoka
et al., 2016). The research vessels were equipped with a
top barrel, where three top men conducted sightings. On
the upper bridge, a captain, a gunner, a helmsman anda researcher also conducted the sightings. The sighting
activity was conducted under acceptable weather conditions (see below), from 60 minutes after sunrise to 60
41

Technical Reports of the Institute of Cetacean Research (2019)

Figure 1.

Research area in the western North Paciﬁc indicating the sub-areas used for management of common
minke whale.

minutes before the sunset.
Survey modes
SSV
Searching was conducted under two survey modes: NSC(Normal Search Closing) mode and NSS (Normal Search
Closing Special). The NSC mode corresponds to ʻclosingmodeʼ conducted under the normal weather conditions
deﬁned as visibility of 2 n.miles or more and wind velocity 4 or below. The NSS corresponds to ʻclosing modeʼ
conducted under more unfavorable weather conditions
but under which, the collection of whale samples was
possible (Tamura et al., 2009).
SV
Searching was conducted under two survey modes: ASP
and NSP modes. The ASP mode corresponds to ʻclosingmodeʼ conducted under normal weather conditions deﬁned as visibility of 2 n.miles or more and wind velocity 4
or below. The NSP mode corresponds to ʻpassing modeʼ
conducted under the normal weather conditions deﬁned
above (Matsuoka et al. 2016).
Cruise track design
For the main survey, the zigzag-shaped track line wasestablished to cover the survey area. Furthermore, theʻSpecial Monitoring Survey (SMS)ʼ was adopted in areas
where the density of whales was expected to be high (seeFujise, 2000; Tamura et al., 2009). The vessels conducted
sighting surveys 6 and 4 n.miles apart from each other in42

the main and SMS surveys, respectively. These data werecombined for the analyses.
Conﬁrmation of the sightings
When a sighting was made, the vessels closed the school
immediately in order to identify the species, estimate theschool size and get other biological information such as
the number of calves, estimated body length, etc. Surface temperatures were recorded at the location of eachwhale sighting.
Density Index of Whales
The Density Index of Whales (DIW) (the number of individual whales sighted by 100 n.miles) was calculated
by each Lat.1°× Long.1°grid squares, for each species.
Calculations were made for the entire research period(1994–2014) as well by month. For the calculation sighting data collected by the SSV and SV were combined.

RESULTS AND DISCUSSION
Searching eﬀorts
A total of 269,728.1 n.miles were surveyed in sub-areas
7, 8, 9 and 11 (Figure 1) between 1994 and 2014 (including transit surveys in the Sea of Japan). Figure 2 show the
research area and the primary searching eﬀort (n. miles)
by Lat.1°×Long.1° grid square.
Geographical and temporal distribution pattern ofwhalesTable 1 shows the summary of all primary whale sightings

Distribution of blue, fin, humpback and North Pacific right whales in the western North Pacific based on JARPN and JARPNII surveys (1994–2014)

Figure 2.

The searching eﬀort by each Lat.1°× Long.1° grid square by JARPN and JARPNII surveys during 1994 to 2014
(including transit surveys in the Sea of Japan).

Table 1
Summary of all primary sightings of blue, ﬁn, humpback and North Paciﬁc right whales during the JARPN and JARPNII in the entire
period (1994–2014) including transit surveys to and from the research areas.
SpeciesBlue whale
Fin whale
Humpback whale
N.P. right whale

Indices
Sch.

Ind.

Calf

Mss

DIS

DIW

WT

374
799
492
48

508
1,125
685
68

23
37
42
9

1.36
1.41
1.39
1.42

0.14
0.30
0.18
0.02

0.19
0.42
0.25
0.03

3.0–25.8°C
2.9–26.9°C
2.8–24.1°C
2.7–17.0°C

Sch.: number of the primary sightings of schools; Ind.: number of the primary sightings of individuals; Calf: number of calves;
Mss: mean school size (Ind./Sch.); DIS: Density Index of Schools (schools/100 n.miles); DIW: Density Index of Whales (individual
whales/100 n.miles); WT: range of surface temperature of the species sighting positions.

for blue, ﬁn, humpback and North Paciﬁc right whales inthe entire period (1994–2014), including transit survey in
the Sea of Japan. Fin whale (799 schools/1,125 individuals including 37 calves) was the species most frequently
sighted (DIW: 0.42). Next was the humpback whale (492schools/685 individuals including 42 calves) (DIW: 0.25).
It was followed by the blue whale (374 schools/508 individuals including 23 calves) (DIW: 0.19) and North Paciﬁcright whale (48 schools/68 individuals including 9 calves)(DIW: 0.03).

Pattern of geographical distribution
Figures 3a, 3b, 3c and 3d show the geographical distribution of the DIW of blue, ﬁn, humpback and North
Paciﬁc right whales, respectively, for the entire period(1994–2014).
Blue whale (Figure 3a)Blue whales were widely distributed mainly north of 35°N
in sub-areas 8 and 9 from May to September. Surface
temperature ranged from 3.0°C to 25.8°C (Table 1). A
high-density area was observed north of 45°N, southeast
oﬀ the Kamchatka Peninsula in sub-area 9.
43

Technical Reports of the Institute of Cetacean Research (2019)44

Figure 3a.

Distribution of DIW of blue whales by Lat.1°× Long.1° grid squares. The DIW was calculated using JARPN
and JARPNII sighting data in the entire period (1994 to 2014).

Figure 3b.

Distribution of DIW of ﬁn whales by Lat.1°× Long.1° grid squares. The DIW was calculated using JARPN
and JARPNII sighting data in the entire period (1994 to 2014).

Distribution of blue, fin, humpback and North Pacific right whales in the western North Pacific based on JARPN and JARPNII surveys (1994–2014)

Figure 3c.

Distribution of DIW of humpback whales by Lat.1°×Long.1° grid squares. The DIW was calculated using
JARPN and JARPNII sighting data in the entire period (1994 to 2014).

Figure 3d.

Distribution of DIW of North Paciﬁc right whales by Lat.1°×Long.1° grid squares. The DIW was calculatedusing JARPN and JARPNII sighting data in the entire period (1994 to 2014).

45

Technical Reports of the Institute of Cetacean Research (2019)Blue whales were caught in the past around the rim of
the western North Paciﬁc. In summer, they concentrated
along the edge of the continental shelf and along thesouth side of the Aleutian Archipelago. The catch data
showed a distribution gap between sub-areas 7 and 9
in summer (Nishiwaki, 1966). However, JARPNII data
showed no such gap. The previous gap may have beencaused by regulation of the whaling operations between
coastal (land base type) and oﬀshore (mother ship type)whaling. Further, according to sighting data collected by
the Japanese Scouting Vessel (JSV) between 1966 and1990, blue whales were not sighted in sub-areas 7, 8 and
9 in June. However, JARPN and JARPNII sighting data suggested that this species was widely distributed in thosesub-areas in June in the period 1994–2014.
The design-based abundance of this species in subareas 7, 8 and 9 was estimated as 38 whales during May
to June (2009) and as 958 whales during July to August(2008) (Hakamada and Matsuoka, 2016).
Fin whale (Figure 3b)
Fin whale was the most frequently sighted species. This
species was mainly sighted in sub-areas 8 and 9, and the
distribution pattern was similar to that of the blue whale.
They were mainly distributed north of 37°N in sub-areas
7, 8 and 9 from May to September. Surface temperature
ranged from 2.9°C to 26.9°C (Table 1). A high-density area
was observed north of 45°N in sub-area 9.
Fin whales were caught in the past along the outer
shelf and south of the Aleutian Islands. A distribution gap
between sub-areas 7 and 9 was previously observed forthis species in summer (Nishiwaki, 1966). However, as in
the case of the blue whale, the present results showedno such gap. The previous gap may have been causedby regulation of the whaling operations between coastal(land base type) and oﬀshore (mother ship type) whaling.
The design-based abundance of this species in subareas 7, 8 and 9 was estimated as 413 whales during May
to June (2009) and as 3,958 whales during July to August(in 2008) (Hakamada and Matsuoka, 2016).
Humpback whale (Figure 3c)
Humpback whales were mainly distributed north of 37°N
in sub-areas 7, 8 and 9 from May to September. Surface
temperature ranged from 2.8°C to 24.1°C (Table 1). Highdensity areas were observed north of 35°N in sub-areas 7
and 8, and north of 45°N in sub-area 9.
The design-based abundance of this species in subareas 7, 8 and 9 was estimated as 1,136 whales during
May–June (2009) and as 392 whales during July–August46(2008) (Hakamada and Matsuoka, 2016).
North Paciﬁc right whale (Figure 3d)
North Paciﬁc right whale was the least frequently sighted
species. This species was mainly distributed north of 37°N
in sub-areas 7, 8 and 9 from May to September. Surface
temperature ranged from 2.7°C to 17.0°C (Table 1).
According to Miyashita et al. (1995), there were nosightings in waters outside of the Okhotsk Sea, north of
40°N. However, present results conﬁrmed the existenceof this species in the oﬀshore region during 1994–2014
from May to September.
The design-based abundance of this species in subareas 7, 8 and 9 was estimated as 1,147 whales during
May–June (2011–2012) and 416 whales during July–August (2008) (Hakamada and Matsuoka, 2016).
Pattern of temporal distribution
A more detailed description of the monthly distributionof the species is presented here based on Figures 4a, 4b,4c and 4d, which show the monthly changes in the density index of blue, ﬁn, humpback and North Paciﬁc rightwhales, respectively. As a whole, the main distribution ofblue, ﬁn, humpback and North Paciﬁc right whales moved
northward from 35°N to 45°N from May–August, whichcoincided with the results of previous large-scale distribution pattern reported by Miyashita et al. (1995).
Blue whale (Figure 4a)
A northward migration pattern was observed for this species. The main distribution from 35°N to 40°N in May toJune moved north of 40°N in July to August in sub-areas
8 and 9.
Fin whale (Figure 4b)
A northward migration pattern of ﬁn whale was also observed. The main distribution from 35°N to 40°N during
May–June moved north of 40°N during July–August in
sub-areas 8 and 9. There were almost no ﬁn whale sightings in the west of 144°E in June, and west of 150°E in
July.
Humpback whale (Figure 4c)
A northward migration pattern of humpback whales was
also observed. The main distribution from 37°N to 43°N
in sub-area 7 during May to June moved to north of 45°N
during July–August in sub-areas 8 and 9.
The present results revealed that the distribution
pattern of this species changed from that reported inprevious studies. Humpback whales were not sighted inDistribution of blue, fin, humpback and North Pacific right whales in the western North Pacific based on JARPN and JARPNII surveys (1994–2014)

Figure 4a.

Monthly change of DIW of blue whales during JARPN and JARPNII from 1994 to 2014 surveys, by Lat.1°×Long.1°square.
Top left: April; Top right: May; Middle left: June; Middle right: July; Bottom left: August; Bottom right: September.

sub-areas 7 and 8 in May and June by the JSV surveys(1966–1990), however they were present in those subareas and period by the JARPN and JARPNII surveys in
1994–2014.
North Paciﬁc right whale (Figure 4d)
A northward migration pattern of this species was observed. The main distribution area was north of 42°N dur-ing July to August in sub-area 9. The distribution patternof this species was reported using historical catch and JSV
data (Omura, 1986; Miyashita and Kato, 1998; Clapham
et al., 2004). The present results conﬁrm the existenceof this species in sub-areas 7, 8 and 9 during 1994–2014,
and the distribution pattern in May–September is similar
to that reported previously.
There are two migration routes along both sides of the47

Technical Reports of the Institute of Cetacean Research (2019)

Figure 4b.

Monthly change of DIW of ﬁn whales during JARPN and JARPNII from 1994 to 2014 surveys by Lat.1°× Long.1°square. Top
left: April; Top right: May; Middle left: June; Middle right: July; Bottom left: August; Bottom right: September.

Japanese main Island, based on historical whaling data
(Omura, 1986). Several scientists have suggested that the
Kuril Islands and Kamchatka coasts are likely to be major
summer feeding regions, based on historical and recent
new information (Matsuoka et al., 2009; Brownell et al.,
2001; Clapham et al., 2004; Sekiguchi et al., 2014). A
northward migration pattern was also observed from the
Paciﬁc to the Sea of Okhotsk during the winter to summer
48

in recent analyses using Japan and Russian sighting data
(Matsuoka et al., 2018).

CONCLUSIONS
Sighting data of large whales in the western North Paciﬁc,collected systematically by JARPN and JARPNII for a long
period of time, were valuable in providing information on
the geographical and temporal pattern of distribution of

Distribution of blue, fin, humpback and North Pacific right whales in the western North Pacific based on JARPN and JARPNII surveys (1994–2014)

Figure 4c.

Monthly change of DIW of humpback whales during JARPN and JARPNII from 1994 to 2014 surveys by
Lat.1°×Long.1°square. Top left: April; Top right: May; Middle left: June; Middle right: July; Bottom left: August; Bottom
right: September.

blue, ﬁn, humpback and North Paciﬁc right whales in thisoceanic basin. The data indicate that some species havebeen expanding their distribution in recent years. The
same sighting data have been used for abundance estimates of these species, however, future studies on distribution and abundance should take into consideration theavailable information on stock structure.

ACKNOWLEDGEMENTS
We thank all cruise leaders, captains, oﬃcers, crew andresearchers involved on the JARPN and JARPNII surveys
for their eﬀort to collect sighting data.

49

Technical Reports of the Institute of Cetacean Research (2019)

Figure 4d.

Monthly change of the Density Index (number of primary sightings of whales/100 n.mile) of North Paciﬁc right whales
during JARPN and JARPN II from 1994 to 2014 surveys by Lat.1°× Long.1°square. Top left: April; Top right: May; Middle
left: June; Middle right: July; Bottom left: August; Bottom right: September.

REFERENCES
Brownell Jr., R.L., Clapham, P.J., Miyashita, T. and Kasuya, T.
2001. Conservation status of North Paciﬁc right whales. J.
Cetacean Res. Manage. (special issue) 2: 269–286.
Clapham, P.J., Good, C., Quinn, S.E., Reeves, R.R., Scarﬀ, J.E. and
Brownell, R.L. 2004. Distribution of North Paciﬁc right whales
50(Eubalaena japonica) as shown by 19th and 20th century
whaling catch and sighting records. J. Cetacean Res. Manage.
6 (1): 1–6.
Fujise, Y. 2000. Outline of the research activities under theJapanese Whale Research Program under a special permit in
the North Paciﬁc (JARPN) from 1994 to 1999. Paper SC/F2K/J8
presented to the Workshop to Review the Japanese Whale
Research Program under Special Permit for North Paciﬁc

Distribution of blue, fin, humpback and North Pacific right whales in the western North Pacific based on JARPN and JARPNII surveys (1994–2014)

Minke Whales (JARPN), February 2000 (unpublished). 30 pp.
[Available from the IWC Secretariat].
Hakamada, T. and Matsuoka, K. 2016. The number of blue, ﬁn,humpback, and North Paciﬁc right whales in the western
North Paciﬁc in the JARPNII Oﬀshore survey area. Paper
SC/F16/JR13 presented to the JARPNII Review Meeting,February 2016 (unpublished). 14 pp. [Available from the IWC
Secretariat].
Matsuoka, K., Kiwada, H., Fujise, Y. and Miyashita, T. 2009.
Distribution of blue (Balaenoptera musculus), ﬁn (B.
physalus), humpback (Megaptera novaeangliae) and North
Paciﬁc right (Eubalaena japonica) whales in the western
North Paciﬁc based on JARPN and JARPNII sighting surveys(1994 to 2007). Paper SC/J09/JR35 presented to the JARPNII
Review Meeting, 26–30 January 2009 (unpublished). 12 pp.
[Available from the IWC Secretariat].
Matsuoka, K., Hakamada, T. and Miyashita, T. 2016. Methodology
and procedure of the dedicated sighting surveys in JARPNII—
Oﬀshore component—2016. Paper SC/F16/JR2 presented to
the JARPNII Review Meeting, 22–26 February 2016 (unpublished). 14 pp. [Available from the IWC Secretariat].
Matsuoka, K., Zharikov, K., Hakamada, T. and Miyashita, T. 2018.
Sightings of the North Paciﬁc Right whales (Eubalaena japonica)in the western North Paciﬁc (1982 to 2016). Paper SC/67A/
NH07 presented to the IWC Scientiﬁc Committee, May 2017
(unpublished). 10 pp. [Available from the IWC Secretariat].
Miyashita, T., Kato, H. and Kasuya, T. (eds). 1995. Worldwide
Map of Cetacean Distribution based on Japanese Sighting
Data (Volume 1). National Research Institute of Far Seas
Fisheries, Shimizu, Shizuoka, Japan. 140 pp.

Miyashita, T. and Kato, H. 1998. Recent data on the statusof right whales in the NW Paciﬁc Ocean. Paper SC/M98/
RW11 presented to the IWC Special Meeting of the Scientiﬁc
Committee towards a Comprehensive Assessment of Right
Whales Worldwide, 16–25 March (unpublished). 15 pp.
[Available from the IWC Secretariat].
Nishiwaki, M. 1966. Distribution and migration of the larger cetaceans in the North paciﬁc as shown by Japanese whaling results. pp. 171–191. In: K.S. Norris (ed.) Whales, dolphins, andporpoises. University of California Press, Berkely. CA. 789 pp.
Okamura, H., Matsuoka, K., Hakamada, T., Okazaki, M. andMiyashita, T. 2001. Spatial and temporal structure of thewestern North Paciﬁc minke whale distribution inferred fromJARPN sightings data. J. Cetacean Res. Manage. 3: 193–200.
Omura, H. 1986. History of right whale catches in the waters
around Japan. Rep. int. Whal. Commn (special issue) 10:
35–41.
Sekiguchi, K., Ohnishi, H., Sasaki, H., Haba, S., Iwahara, Y.,
Mizuguchi, D., Otsuki, M., Saijo, D., Nishizawa, B., Mizuno, H.,
Hoshi, N. and Kamito, T. 2014. Sightings of the western stockof North Paciﬁc right whales (Eubalaena japonica) in thefar southeast of the Kamchatka Peninsula. Marine Mammal
Science 30 (3): 1199–1209.
Tamura, T., Matsuoka, K. and Fujise, Y., 2009. Methodology
and survey procedure under the JARPNII—oﬀshore component—with special emphasis on whale sampling procedures.
Paper SC/J09/JR4 presented to the JARPNII Review Meeting,January 2009 (unpublished). 16 pp. [Available from the IWC
Secretariat].

51