SC/61/O4

Cruise Report of the second phase of the Japanese Whale
Research Program under Special Permit in the Western North
Pacific (JARPN II) in 2008 (part I) - Offshore component –TAMURA, T.1), OTANI, S. 1), ISODA, T.1), WADA, A.1), YONEZAKI, S.1), MORI, M. 2), TSUNEKAWA, M. 2), FUKUTOME, K. 2),
NAKAI, K. 1), SATOH, H.1), NOMURA, I.1), NAGATSUKA, S.3), UMATANI, M. 4), KOYANAGI, T.2), TAKAMATSU, T.2),
KAWABE, S.2), KANDABASHI, S.2) , WATANABE, H. 5), KUMAGAI, S. 1), SATO, H. 5), AND OGAWA T.2)
1) The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan,2) Kyodo Senpaku Co. Ltd., 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan,
3) Tokyo University of Marine Science and Technology, Faculty of Marine Science, 4-5-7, Konan, Minato-ku, Tokyo,108-8477, Japan
4) Obihiro University of Agriculture and Veterinary Medicine, 2-11, Inada-cho, Obihiro, Hokkaido, 080-0055, Japan,5) National Research Institute of Far Seas Fisheries, 2-12-4, Fukuura, Kanazawa, Yokohama, Kanagawa 212-0055,
Japan
Contact e-mail: tamura@cetacean.jp

ABSTRACTThe seventh cruise of the full-scale survey of the second phase of the Japanese Whale Research Program under Special
Permit in the Western North Pacific (JARPN II) -offshore component- was conducted from 6 June to 29 August 2008 in
sub-areas 7, 8 and 9 of the western North Pacific. The objectives of the JARPN II are (a) feeding ecology andecosystem studies, (b) monitoring environmental pollutants in cetaceans and the marine ecosystem and (c) elucidationof stock structure. Target species in the whale component of the programme are common minke whale Balaenoptera
acutorostrata, sei whale B. borealis, Bryde’s whale B. edeni and sperm whale Physeter macrocephalus. A total of sevenresearch vessels was used: one trawl survey vessel equipped with scientific echo sounder (TSV), two dedicated sighting
vessel (SVs), three sighting/sampling vessels (SSVs) and one research base vessel. A total of 5,147.1n.miles was
surveyed in a period of 122 days by SVs. During that period nine common minke, 140 sei, 292 Bryde’s and 291 sperm
whales were sighted by the SVs. A total of 5,757.6n.miles was surveyed in a period of 80 days by SSVs. During that
period 66 common minke, 386 sei, 234 Bryde’s and 277 sperm whales were sighted by the SSVs. A total of 59 common
minke, 100 sei, 50 Bryde’s and 2 sperm whales was sampled by the SSVs. All whales sampled were examined on board
the research base vessel. One Bryde’s whale was tracked by satellite tag in the western North Pacific during July. Datatransmission was received for three weeks (SC/61/O7). As in previous surveys common minke whales fed mainly on
Pacific saury (Cololabis saira) and Japanese anchovy (Engraulis japonicus). Bryde’s whales fed mainly on krill andJapanese anchovy. Sei whales fed mainly on copepods, krill and Japanese anchovy. Dominant preys in the stomach of
two sperm whales were various kinds of squids, which inhabit the mid- and deep-waters. These data will be used in thedevelopment of ecosystem modelling.
KEYWORDS: PACIFIC OCEAN, COMMON MINKE WHALE; BRYDE’S WHALE; SEI WHALE; SPERM
WHALE; MONITORING, FOOD/PREY; ECOSYSTEM; SATELLITE TAGGING; SCIENTIFIC PERMITSBACKGROUND
After the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN) from 1994 to
1999, the second phase of Japanese Whale Research Program under Special Permit in the Western North Pacific(JARPNII) was started in the 2000 summer season as a two-year feasibility study. Based on the success of thefeasibility study (Government of Japan, 2002a) and increasingly strong support from international fisheriesorganizations, including FAO, for research to improve multi-species approaches to management, JARPN II started as afull-scale research program in 2002.The full-scale study aimed mainly i) to evaluate the feeding ecology and ecosystem
studies, ii) to monitor environmental pollutants in cetaceans and the marine ecosystem and iii) to elucidate the stock
structure (Government of Japan, 2002b).
The full-scale JARPN II plan involved two survey components: the ‘offshore’ survey was covered by the Nisshin Maru
research unit and the two ‘coastal’ surveys (Sanriku and Kushiro) were covered by catcher boats of small type whaling.
1The coastal component was necessary to cover the temporal and spatial gaps, which could not be covered by the Nisshin
Maru unit (Government of Japan, 2002b).
The research area of offshore component was set in sub-areas 7, 8 and 9, and the target species and sample sizes in 2008
were set as follows: 100 common minke whales (in addition, 120 were to be sampled by the coastal survey); 100 sei
whales, 50 Bryde’s whales and 10 sperm whales.
In January 2009 IWC/SC conducted the Expert Workshop to review the ongoing JARPN II Programme (IWC, 2009).
The results presented on the three main objectives of JARPN II (Feeding ecology and ecosystem studies, marine
pollutants and stock structure) were discussed by the Independent Expert Panel (IEP). These results will reflect to thenext research activities of JARPN II.
In this paper, we present an outline of the seventh full-scale survey of the JARPN II -offshore component-, which was
conducted from 6 June to 29 August 2008.
MATERIALS AND METHODS
Research area
Sub-areas 7, 8 and 9, excluding the EEZ zones of foreign countries, were the research area (Fig. 1). These sub-areas
were further divided as follows:
Sub-area 7:

Five small blocks (7N, 7MI, 7MO, 7SI, 7SO) stratified for taking into account satellite information onwater temperature.

Sub-areas 8 and 9: Four small blocks were divided at latitude of 40ºN in each sub area (8N and 8S, 9N and 9S).
Research vessels
Seven research vessels were used.
The research base vessel Nisshin Maru (NM: 8,030GT) commanded the research and was the platform for biologicalexamination of whale samples and processing of by-products. The Yushin Maru (YS1: 720GT), Yushin Maru No.2
(YS2: 747GT) and Yushin Maru No.3 (YS3: 742GT) were used as the sighting/sampling vessels (SSVs), which
conducted sighting activities, sampling of targeted whale species and various experiments and observations. The
Kyoshin Maru No. 2 (KS2: 372GT) was used as dedicated sighting vessel (SV). The Kaiko-maru (KK1: 860.25GT) was
engaged the cetacean prey species survey and whale sighting survey (TSV and/or SV) using midwater trawl, Issaces
Kidd Midwater Trawl (IKMT), NORPAC net and Oceanographic observations. The Shunyo Maru (SYO: 887GT) was
engaged in trawl surveys and echo sounder surveys. This vessel also conducted the mid-water trawl net and MOCNESS
net sampling. Furthermore, this vessel conducted the oceanographic observations using CTD.
Survey components
The survey was composed of three main components: whale survey, sighting survey and the cooperative survey.
Whale survey
Vessels: Four research vessels (NM, YS1, YS2 and YS3)
Research area: Sub-areas 7, 8 and 9. In addition, a ‘special monitoring survey’ (SMS) was undertaken in some areas
where the number of common minke, Bryde’s and sei whales was expected to be abundant.
Research period
Between 6 June and 24 August
Dedicated Sighting survey
Vessels: Two research vessel (KS2, KK1)
Research area:

Sub-areas 7, 8 and 9

Research period:
KS2: Between 1 July and 29 August
KK1: Between 27 July and 31 August
Cooperative survey on the prey species and whale sampling
Vessels: Six research vessels (NM, YS1, YS2, YS3, KK1 and SYO)
Research area:2

First period (Eastern block): A part of sub areas 8 and 9 (NM, YS1, YS2, YS3, KK1)

Second period (Western block): A part of sub area 7 (NM, YS1, YS2, YS3, SYO)
Research period:First period (Eastern block): Between 1 July and 26 July (NM, YS1, YS2, YS3, KK1)

Second period (Western block): Between 18 July and 5 August (NM, YS1, YS2, YS3, SYO)
Methods for setting cruise track line
Whale survey
Track lines and allocation of vessels were made as in previous JARPN and JARPN II surveys (Fujise et al., 1995, 1996,
1997, 2000, 2001, 2002, 2003; Ishikawa et al., 1997; Zenitani et al., 1999; Tamura et al., 2004, 2005, 2006, Matuoka etal., 2007). The zigzag-shaped track line was established on an arbitrary basis in each sub-area. Furthermore, some
‘special monitoring surveys’ (SMS) were conducted in areas where the abundance of common minke whales, Bryde’s
and sei whales was expected to be high. Track line in the SMS was designed separately from the original track line.
Three SSVs were allocated to these tracks with the allocation being changed every day. The research course for the
SSVs consisted of one main track and two parallel tracks established in 7 n.miles apart from main course.
Dedicated Sighting survey
Apart from the sampling activities, an independent track line for dedicated sighting survey was designed in the research
area.
Sighting surveys
Sighting procedure both for the whale survey and dedicated sighting survey was similar to the previous surveys of
JARPN and JARPN II (Fujise et al., 1995, 1996, 1997, 2000, 2001, 2002, 2003; Ishikawa et al., 1997; Zenitani et al.,
1999; Tamura et al., 2004, 2005, 2006, 2007, Matsuoka et al., 2008). In the research area sighting was conducted
mainly under closing mode. Furthermore two modalities of sighting in closing mode were adopted, NSC and NSS modes,
by taking into consideration weather and sea conditions. The NSC and NSS modes were the same as BC and BS modesin the previous JARPN surveys, respectively. The conditions to conduct surveys under NSC mode were similar to thoseestablished in Japanese sighting surveys conducted by the National Research Institute of Far Seas Fisheries (i.e.
visibility of 2 n.miles or more and wind force of 4 or below). The NSS mode was used under bad weather conditions
such as heavy rain and fog when the collection of whale samples was still possible. This NSS mode was used only by
SSV vessels. These two mode surveys were recorded separately for future analysis. Also an ASP mode was used(closing mode survey without sampling activities under normal sighting conditions).
During the transit from homeport (HP) to research area (RA) and from RA to HP, the NSP mode was adopted (passing
mode without sampling activities under normal sighting conditions).
Closing was performed mainly on sightings of common minke, Bryde’s, sei and sperm whales. Furthermore closing was
made on sightings of large whales, such as blue, humpback, right and fin whales. In these cases, closing was done inorder to confirm species and school size and in order to conduct some experiments.
Sampling of common minke, Bryde’s, Sei and sperm whales
The target species and sample sizes in 2008 JARPN II offshore component were set as follows: 100 common minke
whales; 100 sei whales, 50 Bryde’s whales and 10 sperm whales.
Most of the target whales sighted on the trackline was approached for sampling. Furthermore sampling effort wasapplied outside the established research hours (Main time: 07:00-19:00 (12 hrs)), if collection of whale samples wasconsidered possible.
For schools consisting of two or more animals, numbering was made for all the whales in the school; to set samplingorder randomly in accordance with the table of random numbers (Kato et al., 1989). Cow and calf pairs were nottargeted for sampling.
Sampled whales were immediately transported to a research base vessel, where biological measurements and sampling
were carried out.
Experiments
The following experiments and observations were conducted by the sighting/sampling vessels (YS1, YS2 and YS3):
1. Sighting distance and angle experiments to examine the precision of sighting data.
2. Biopsy sampling on gray, blue, fin, humpback and right whales.
33. Photographic records of natural marks on blue, humpback and right whales.
4. Preliminary experiments on attachment of satellite tagging to sei and Bryde’s whales.
5. Feeding behaviour patterns of large whale species (blue, fin, sei, Bryde’s, common minke, humpback, right andsperm whales).
On board the SV (KS2, KK1), the following experiments and observations were conducted:
1. Sighting distance and angle experiment to examine the precision of sighting data.
2. Biopsy sampling on gray, blue, fin, sei, Bryde’s, minke, humpback, right and sperm whales.
3. Photographic records of natural marks on blue, humpback and right whales.
4. Feeding behaviour patterns of large whales.
On board the research base vessel (NM), the following experiments and observations were conducted:
1. Observations of marine debris in the sea were conducted from the wheelhouse (during transit cruises)
On board the prey survey vessel (SYO, KK1), the following experiments were conducted:
1. Estimate abundance of prey species of common minke and other large whale species using an echo sounder system.
2. Prey survey using echo sounder, Mid-water trawl net, MOCNESS net, IKMT net and plankton net.
3. Oceanographic observations using CTD, TDR, EPCS and OPCS.

RESULTS AND DISCUSSIONS
Searching distance
Track line covered by the three sighting/sampling vessels (SSVs) is shown in Fig. 2. The total searching distance for
SSVs was 5,757.6n.miles.
Track line covered by the dedicated sighting vessels (SVs) is shown in Fig. 3. The total searching distance was
5,147.1n.miles.
Sightings of common minke, Bryde’s, sei and sperm whales
Sighting and sampling vessels (SSVs)
A total of 64 schools (66 individuals) of common minke whales was sighted, consisting of 21 schools (21 individuals)of primary and 43 schools (45 individuals) of secondary sightings. For sei whale, 229 schools (386 individuals) weresighted, consisting of 137 schools (230 individuals) of primary sightings and 92 schools (156 individuals) of secondarysightings. For Bryde’s whale, 170 schools (234 individuals) were sighted, consisting of 134 schools (186 individuals) ofprimary sightings and 36 schools (48 individuals) of secondary sightings. For sperm whale, 141 schools (277individuals) were observed, consisting of 97 schools (162 individuals) of primary sightings and 44 schools (115
individuals) of secondary sightings (Table 1).
Fig 4. shows the distribution of common minke, sei, Bryde’s and sperm whales sighted by the SSVs in the sub-areas 7,
8 and 9. Common minke whales and sei whales were sighted mainly in offshore of sub-areas 8 and 9. But, Bryde’s
whales were sighted mainly in southern part of sub-areas 7 and 8. Sperm whales were widely distributed in sub-areas 7,
8 and 9.
Dedicated sighting vessels (SVs)
During the research cruise, 11 schools (11 individuals) of common minke whales were sighted, consisting of 9 schools(9 individuals) of primary sightings and 2 schools (2 individuals) of secondary sightings. For sei whale, 71 schools (139individuals) were sighted, consisting of 69 schools (136 individuals) of primary sightings and 2 schools (3 individuals)of secondary sightings. For Bryde’s whale, 193 schools (292 individuals) were sighted, consisting of 188 schools (285individuals) of primary sightings and 5 schools (7 individuals) of secondary sightings. For sperm whale, 134 schools(294 individuals) were sighted, consisting of 127 schools (283 individuals) of primary sightings and 7 schools (11individuals) of secondary sightings (Fig. 5, Table 1).

4Sightings of other large cetacean species
Sighting and sampling vessels (SSVs)
Table 1 also shows the number of sightings for other large whale species made by the SSVs, including large baleen
whales such as blue (15 schs./22 inds.), fin (39 schs./46 inds.), and humpback whales (17 schs./27 inds.).
Dedicated sighting vessels (SVs)
Large baleen whales such as blue (18 schs. /23 inds.), fin (51 schs./75 inds.), humpback whales (10 schs./10 inds.) andright whale (5 schs./6 inds.) were found in the sub-areas 7, 8 and 9 (Table 1).
Sampling numbers and biological research for common minke, Bryde’s, sei and sperm whales
A total of 59 common minke whales (Male: 53 individuals, Female: 6 individuals) was sampled. A total of 100 sei
whales (Male: 44 individuals, Female: 56 individuals) was sampled. A total of 50 Bryde’s whales (Male: 30 individuals,
Female: 20 individuals) were sampled. Two male sperm whales were sampled. Table 2 summarizes the biological dataand samples collected from whales. A total of 52 research items was covered. These items are related to the studies
conducted under the three main objectives of the JARPN II: study on feeding ecology of whales and marine ecosystem,
pollution studies and elucidation of stock structure.
Composition of sex and sexual maturity of common minke, sei and Bryde’s whales are shown in Table 3. Statistics ofbody length of common minke, sei, Bryde’s and sei whales is shown in Table 4. Mean body length of common minke
whales is 7.37 m and 7.96 m for males and females, respectively. For sei whales, those were 13.42 m and 13.89 m formales and females, respectively. For Bryde’s whales, those are 12.02 m and 12.55 m for males and females,
respectively. For sperm whale, the statistics of body length are shown also in Table 4. Mean body length is 11.48 m.
Geographical distribution of common minke, sei, Bryde’s and sperm whale samples are also shown in Fig. 6 based on
the sighting positions.
Distribution and food habit
During the research season (from June to August) in the offshore area, common minke whales fed mainly on Pacificsaury, and they also fed on krill (Table 5). Sei whales were distributed widely in the offshore area. From June to August,they fed mainly on copepods and Japanese anchovy (Table 5). Bryde’s whales were distributed in the southern part of
the research area. They fed mainly on Japanese anchovy and krill (Table 5). Sperm whales were also distributed widelyin the research area. They fed mainly on deep sea squids in entire area.
Experiments
Biopsy sampling trial
Table 6 shows the results of biopsy skin sampling. A total of eleven blue whales, one humpback whale, one sei whaleand four right whales was targeted for biopsy sampling by the SV s and SSVs. As a result, four blue whales, one
humpback whale, one sei whale and four right whale biopsy skin samples were collected.
Natural marks (photo ID) for blue, humpback, sei and right whales
Table 7 shows the results of the photo-ID experiments for blue whales, humpback whales, sei and right whales. A totalof eleven blue whales, one humpback whale, one sei whale and five right whales was targeted by the SVs and SSVs.
Feeding and excretion behaviour for large baleen whales
The SVs and SSVs had planned to conduct recording of the feeding and excretion behaviour of large baleen whales
using a photograph. As a result, 36 sei whales and four Bryde’s whale were observed, and took 17 photographs.
Examination of attachment of satellite tag to sei and Bryde’s whale
The SSVs had planned to try attaching satellite tags to sei and Bryde’s whales. A total of four sei and 14 Bryde’s whales
was targeted by the SSVs. As a result, one satellite tag was attached to a Bryde’s whale. The satellite tracking data wasreceived for a period of three weeks (See Appendix 1.).

ACKNOWLEDGMENTS
The authors are greatly indebted to Mr. Joji Morishita and Shigeki Takaya of the Fisheries Agency of Japan, Prof.
Hidehiro Kato, Tokyo University of Marine Science and Technology, and Dr. Hiroshi Hatanaka, Dr. Seiji Ohsumi, Dr.
Yoshihiro Fujise, Dr. L.A. Pasutene, and Mr. Shigetoshi Nishiwaki of The Institute of Cetacean Research (ICR) for
their guidance in the design and implementation of the research. We thank all crew of the research vessels (NM, YS1,
YS2, YS3, KK1, KS2 and SYO) and the staff of the ICR, Kyodo-Senpaku Co. Ltd and NRFSF staff. The present5research project (JARPN II) was funded by a subsidy from the Ministry of Agriculture, Forestry and Fisheries,
Government of Japan.

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Yatsu, A., Nishida, H., Tomosada, A., Kinoshita, T. and Wada, T. 2001. Trajectories of catch and stock abundance ofdominant small pelagic fishes and common squid with some related environmental indices around Japan. PICES Sci.
Rep. 18: 175-8.
Zenitani, R., Fujise, Y., Matsuoka, K., Tamura, T., Bando, T., Ichihashi, H., Shimokawa, T., Krasnenko, A.S., TaguchiF., Kinoshita, T., Mori, M., Watanabe, M., Ichinomiya, D., Nakamura, M., Sakai, K., Matsuzaka, K., Kamei, H. andTohyama, D. 1999. Cruise report of the Japanese Whale Research Program under a Special Permit in the North Pacificin 1998. Paper SC/51/RMP7 presented to the IWC Scientific Committee, May 1999 (unpublished). 20pp

7

Table 1. List of cetacean species and number of sightings (no. schools/no. individuals)
Sighting/sampling vessels (YS1, YS2 and YS3)

PrimarySch. Ind.

SecondarySch. Ind.

Total
Sch. Ind.

Common minke whale

21

21

43

45

64

66

Like minke whale

1

1

10

10

11

11

Sei whale

137 23092156

229 386

Bryde's whale

134 18636

48

170 234

Sperm whale

97

162

44

115

141 277

Blue whale

12

18

3

4

15

22

Fin whale

28

34

11

12

39

46

Humpback whale

9

16

8

11

17

27

Species

Dedicated sighting vessel (KS2)

Primary
Sch.
Ind.

Secondary
Sch.
Ind.

Total
Sch.
Ind.

Common minke whale

8

8

2

2

10

10

Sei whale

56

116

0

0

56

116

Bryde's whale

94

141

0

0

94

141

Sperm whale

79

205

5

9

84

214

Blue Whale

12

17

0

0

12

17

Fin Whale

35

55

1

1

36

56

Humpback whale
Right whale

8
5

8
6

1
0

1
0

9
5

9
6

Species

Dedicated sighting vessel (KK1)

PrimarySch. Ind.

SecondarySch. Ind.

Total
Sch. Ind.

Common minke whale

1

1

0

0

1

1

Like minke whale

1

1

0

0

1

1

Sei whale

13

20

2

3

15

23

Bryde's whale

94

144

5

7

99

151

Sperm whale

48

78

2

2

50

80

Blue whale

5

5

1

1

6

6

Fin whale

15

19

0

0

15

19

Humpback whale

1

1

0

0

1

1

Species8

Table 2. Summary of biological data and samples obtained.
Common minke

Samples and data
Body length and sex
External body proportion
Photographic record and external character
Diatom film record
Standard measurements of blubber thickness (five points)
Detailed measurements of blubber thickness (eleven points)
Body weight
Body weight*
Body weight by parts
Blubber tissues for DNA study
Blubber, muscle, liver and kidney tissues for heavy metal analysis
Blubber, muscle, liver and kidney tissues for organochlorines analysis
Blubber, muscle tissues for by-product inspection
Blubber, muscle tissues for ingredient analysis
Lung tissue for atmospheric analysis
Tissues for lipid analysis
Tissues for various analysis
Tissues for virus test
Mammary grand; lactation status, measurement and histological sample
Collection of spermaceti sample
Collection of maternal milk sample
Uterine horn; measurement and endometrium sample
Collection of ovary
Photographic record of foetus
Foetal sex (identified by visual observation)
Foetal length and weight
External measurements of foetus
Foetal blubber tissues for DNA study
Foetal tissues for various analysis
Foetal lens for age determination
Testis and epididymis; weight and histological sample
Collection of plasma sample
Collection of whole blood sample
Whole blood samples from umbilical cord
Plasma samples from umbilical cord
Stomach content, conventional record
Volume and weight of stomach content in each compartment
Stomach contents for feeding study
Record of external parasites
Collection of external parasites
Record of internal parasites
Collection of internal parasites
Earplug for age determination
Tympanic bulla for age determination
Maxillally teeth for age determination
Lens for age determination
Largest baleen plate for morphologic study and age determination
Baleen plate measurements (length and breadth)
Length of each baleen plate series
Vertebral epiphyses sample
Number of vertebrae
Number of ribs
Brain weight
Skull measurement (length and breadth)

Bryde's whale

Sperm whale

M

F

T

M

F

T

M

F

T

M

F

T

53
53
53
53
53
8
53
8
53
53
53
53
2
2
9
53
53
3
3
3
3
3
3
3
52
53
53
53
53
50
53
0
53
0
53
53
53
53
53
52
53
0
53
8
48

6
6
6
6
6
1
6
1
6
6
6
6
0
0
1
6
5
6
6
6
6
2
2
2
2
2
2
2
6
6
0
3
6
6
6
6
1
6
0
6
6
6
6
6
5
6
0
6
1
5

59
59
59
59
59
9
59
9
59
59
59
59
2
2
10
59
58
6
6
6
6
5
5
5
5
5
5
5
52
59
59
0
3
59
59
56
59
1
59
0
59
59
59
59
59
57
59
0
59
9
53

44
44
44
44
44
5
28
16
5
44
44
44
44
2
10
6
44
44
12
12
12
12
12
12
12
44
44
44
44
44
37
44
2
44
4
44
43
44
44
43
36
44
5
44
5
32

56
56
56
56
56
10
14
42
10
56
56
56
56
3
0
11
56
36
56
1
55
56
24
24
24
24
24
24
24
56
56
27
33
56
56
40
56
2
56
5
56
56
56
56
56
56
56
11
56
11
52

100
100
100
100
100
15
42
58
15
100
100
100
100
5
10
17
100
80
56
1
55
56
36
36
36
36
36
36
36
44
100
100
27
33
100
100
77
100
4
100
9
100
99
100
100
99
92
100
16
100
16
84

30
30
30
30
30
6
30
6
30
30
30
30
3
7
7
30
30
5
5
5
5
5
5
5
30
30
30
30
30
12
30
2
30
1
30
30
30
30
29
30
30
6
30
6
22

20
20
20
20
20
2
20
2
20
20
20
20
2
0
2
20
9
20
0
20
20
4
4
4
4
4
4
4
20
20
8
9
20
20
6
20
3
20
0
20
20
20
20
19
20
20
2
20
2
20

50
50
50
50
50
8
50
8
50
50
50
50
5
7
9
50
39
20
0
20
20
9
9
9
9
9
9
9
30
50
50
8
9
50
50
18
50
5
50
1
50
50
50
50
48
50
50
8
50
8
42

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

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

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

*divided by some parts because the whale was too big to measure the whole body weight with the scale

9

Sei whale

2
2
2
2
2
2
2
2

Table 3. Compositon of sex and sexual maturity of three baleen whales collected

Common minke whale
Male

Sub-area
789FemaleCombined

Imm.

Mat.

Unknown

Total

Imm

Rest.

Preg.

Total

1
(20.0)
0(0.0)
2

4(80.0)
3(75.0)
38

0
(0.0)
1
(25.0)
4

5(100.0)4(100.0)
44

0
(0.0)
0
(0.0)
0

0
(0.0)
0
(0.0)
1

0
(0.0)
0
(0.0)
5

0
(0.0)
0
(0.0)
6

5
(100.0)4(100.0)50(4.0)(76.0)(8.0)(88.0)

(0.0)

(2.0)

(10.0)(12.0)(100.0)Combined

3

45

5

53

0

1

5

6

59

(5.1)

(76.3)(8.5)(89.8)

(0.0)

(1.7)

(8.5)

(10.2)(100.0)Sex ratio

MaturityPregnancy(% males)Male

Femalerate*)

100.0

80.0

0.0

0.0

100.0

75.0

0.0

0.0

88.0

86.4

100.0

0.0

89.8

84.9

100.0

83.3

MaturityPregnancy*) Apparent pregnancy rate

Sei whale
Sub-area

Male

FemaleCombined

Imm.

Mat.

Total

Imm

Ovu

Rest.

Preg.

Lact.

Preg&Lact

Total

7

0

0

0

0

0

0

0

0

0

0

8

5
(11.4)
5(8.9)
10(10.0)

18(40.9)
16(28.6)
34(34.0)

23(52.3)
21(37.5)
44(44.0)

6(13.6)
11(19.6)
17(17.0)

0
(0.0)
0
(0.0)
0
(0.0)

1
(2.3)
1
(1.8)
2
(2.0)

13
(29.5)
22(39.3)
35(35.0)

1
(2.3)
0
(0.0)
1
(1.0)

0
(0.0)
1
(1.8)
1
(1.0)

21
(47.7)
35(62.5)
56(56.0)Imm.

Mat.

Unknown

Total

Imm

Ovu

Rest.

Preg.

Lact.

Preg&LactTotal

4(15.4)
1(4.5)
1(50.0)
6(12.0)

10(38.5)
12(54.5)
1(50.0)
23(46.0)

1
(3.8)
0
(0.0)
0
(0.0)
1
(2.0)

15
(57.7)
13(59.1)
2(100.0)30(60.0)

1(3.8)
3(13.6)
0
(0.0)
4
(8.0)

0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)

5
(19.2)
2
(9.1)
0
(0.0)
7
(14.0)

5(19.2)
4(18.2)
0(0.0)
9(18.0)

0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)

0
(0.0)
0
(0.0)
0
(0.0)
0
(0.0)

11
(42.3)
9(40.9)
0(0.0)
20(40.0)

9
Combined

Sex ratio(% males)Male

Femalerate*)

0

-

-

-

-

44
(100.0)56(100.0)100(100.0)

52.3

78.3

71.4

86.7

37.5

76.2

68.6

95.8

44.0

77.3

69.6

92.3

*) Apparent pregnancy rate

Bryde’s whale
Sub-area
7
8
9Combined

Male

Female*) Apparent pregnancy rate

10

Combined
26(100.0)22(100.0)2(100.0)50(100.0)Sex ratio

MaturityPregnancy(% males)Male

Femalerate*)

57.7

66.7

90.9

50.0

59.1

92.3

66.7

66.7

100.0

50.0

#DIV/0!

#DIV/0!

60.0

76.7

80.0

56.3

Table 4. Statistics of body length (m) of four whale species collected

Common minke whaleMale

Sub area

Female

Mean

S.D.

Min

Max

n

Mean

S.D.

Min

Max

n

7

6.89

1.25

4.66

7.56

5

-

-

-

-

-

8

7.24

0.30

6.80

7.47

4

-

-

-

-

-

9

7.44

0.43

5.20

8.07

44

7.96

0.55

7.09

8.69

6

Combined

7.37

0.56

4.66

8.07

53

7.96

0.55

7.09

8.69

6

Mean

S.D.

Min

Max

n

Mean

S.D.

Min

Max

n

7

12.05

0.68

10.53

12.95

15

12.80

0.50

11.69

13.49

11

8

12.21

1.03

9.10

13.55

13

12.24

1.92

8.78

13.76

9

9

10.63

2.70

8.72

12.54

2

-

-

-

-

0

Combined

12.02

1.03

8.72

13.55

30

12.55

1.33

8.78

13.76

20

Sei whale

Male

Sub area

FemaleBryde’s whaleMale

Sub area

Female

Mean

S.D.

Min

Max

n

Mean

S.D.

Min

Max

n

7

-

-

-

-

-

-

-

-

-

-

8

13.46

0.69

11.58

14.54

23

13.98

1.33

10.61

15.83

21

9

13.38

0.99

10.63

14.46

21

13.83

1.20

10.49

15.93

35

Combined

13.42

0.84

10.63

14.54

44

13.89

1.24

10.49

15.93

56

Mean

S.D.

Min

Max

n

Mean

S.D.

Min

Max

n

7

9.24

-

9.24

9.24

1

-

-

-

-

-

8

-

-

-

-

-

-

-

-

-

-

9

13.72

-

13.72

13.72

1

-

-

-

-

-

Combined

11.48

3.17

9.24

13.72

2

-

-

0.00

0.00

0

Sperm whaleMale

Sub area

Female11

Table 5. Prey species and stomach contents weight (1st. + 2nd. stomachs) found in stomach ofcommon minke, Bryde's, sei whales sampled

Common minke whale

Prey species
Krill
Copepods
FishN
Range of weigth (kg)
(Dominant)in the stomachs
5
1
36
1
3
1
3

Neocalanus spp.
Pacific saury
Japanese anchovy
Pink salmon
Oceanic lightfish
Pacific pomfret

0.86-77.40
1.02
0.48-118.20
5.66
1.72-25.88
0.92
17.56-61.72

Sei whale

N
Range of weigth (kg)
(Dominant)in the stomachs

Prey species
Copepods
Krill
Fish

Jellyfish
Squid

61
2
3
7
2
1
1
1
1
1

Neocalanus spp.
Pacific saury
Japanese anchovy
Oceanic lightfish
Chub mackerel*Japanese sardine*
Unidentified*Japanese flying squid*
Unidentified*

0.18-333.65
0.14-0.78
0.28-58.80
0.36-382.66
5.70-10.70
0.20-*: Minor prey species

Bryde’s whale

Prey species
Krill
Fish

N
Range of weigth (kg)
(Dominant)in the stomachs
7
17
2
3
7

Japanese anchovy
Oceanic lightfish
Chub mackerel *Japanese sardine**: Minor prey species

120.12-12.28
0.70-317.10
0.16-0.26-

Table 6. Summary of biopsy skin sampling for baleen whales in the 2008 JARPN II

Whalespecies

Ship

NumberTargeted

Numberofindividuals

experiments

NumberNumberEffortsamplesample

of

of

of

per

per

shootshits

samples

(hr)

trial

hit

(A)

(B)

(C)

(D)

(E)

(F)

(E)/(C)(E)/(D)Blue whale

SSVs

4

7

3

2

1

1:43

0.33

0.50

Blue whale

SVs

4

4

7

2

2

1:59

0.29

1.00

Humpback whale

SSVs

1

1

1

1

1

0:05

1.00

1.00

Right whale

SVs

4

5

9

4

4

1:59

0.44

1.00

Sei whale

SVs

1

1

1

1

1

0:15

1.00

1.00

Table 7. Summary of photo ID for baleen whales in the 2008 JARPN II

Whalespecies

Ship

NumberTargetedofindividuals

Numberofexperiments

photos

(A)

(B)

(C)

Blue whale

SSVs

2

3

2

Blue whale

SVs

4

4

2

Right whale

SSVs

1

1

1

Right whale

SVs

3

4

3

13

9N
7N

8N

7MI 7MO
8S
7SI

9S

7SO

Fig 1. Map showing the research area and strata of the JARPN II full-scale program.

45N

35N
140E

160E

Fig. 2. Track-line covered by the three sighting/sampling vessels (SSVs)
Blue lines were SMS.

14

45N

35N
140E

160E

Fig. 3. Track-line covered by the sighting vessel (SVs: KS2 and KK1)
(Blue line KS2, Red line KK1).

45N

35N
140E

160E

Fig. 4. The positions of the sightings of common minke whale (pink circle), sei (orange square),
Bryde’s (green diamond) and sperm (brown triangle) whales by the threesighting/sampling vessels (SSVs)

15

45N

35N
140E

160E

Fig. 5. The positions of the sightings of common minke whale (pink circle), sei (orange square),
Bryde’s (green diamond) and sperm (brown triangle) whales by the two dedicated sighting
vessels (SVs). Blue line KS2, Red line KK1

45N

35N
140E

160E

E- Block

W- Block

Fig. 6. The positions of the samplings of common minke whale (pink circle), sei (orange square),
Bryde’s (green diamond) and sperm (brown triangle) whales by the threesighting/sampling vessels (SSVs).
Two blocks (Western and Eastern block) show the cooperative surveys on the prey species
and whale sampling areas.

16

Appendex.1.
The information of satellite tagging of a Bryde’s whale in the western North Pacific(Tamura, T. and Nishiwaki, S)

Abstract

One Bryde’s whale tagged with an Argos transmitter (Telonics, INC. USA) was tracked in the western North Pacificfrom 24 July to 13 August. The Bryde’s whale with an estimated body length of 12.6m, was tagged on 24 July 2008, at
38-01N, 147-52E from the Yushin Maru No.2. We received their position information from the satellite for a period of
three weeks. After the satellite tag was attached, the animal moved southeast. The travelling distance was estimated tobe approximately 1,200 naut. miles in the three weeks. The detail of this result was shown in SC/61/O7.

Fig. 1. The Bryde’s whale with the satellite tag attached.

24 July

13 Aug.

Fig. 2. Track of the Bryde’s whale 24 July to 13 August 2008 in the western North Pacific.

17

Appendix 2.
Cruise report of the cetacean prey species survey of JARPN II (offshore component)
in 2008
SHIROH YONEZAKI 1, MASAOMI TSUNEKAWA 2, AND TSUTOMU TAMURA 1

1

The Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo 104-0055, Japan

2

Kyodo Senpaku Co. Ltd., 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan

ABSTRACT

A whale prey species survey was conducted concurrently with a whale sampling survey as a part of the offshore
component of JARPN II in 2008. The primary objective of the concurrent study was estimation of prey selection ofwhales. Survey block with zigzag track lines was set within the survey area of JARPN II. The survey was conductedfrom 5 to 25 July. A trawler-type survey vessel, Kaiko-Maru (860 ton, KK1), equipped with the quantitative echosounder dedicated to the prey survey. KK1 also conducted cetacean sighting survey while she steamed on the tracklines. The acoustic survey using a Simrad EK 500 echo sounder with operating frequencies at 38 and 120 kHz was
carried out to quantify prey abundance as well as to elucidate the distribution patterns. Species compositions of
acoustical backscatterings were identified using midwater trawl and plankton nets. In addition, trawls were towed at
predetermined stations independently from the acoustic survey. IKMT and Twin – NORPAC were used to collectzooplanktons. Midwater trawl, IKMT, and Twin – NORPAC were towed at 22, 2, and 23 stations, respectively.
Oceanographic observations were conducted using CTD at 25 stations. Total surveyed distance of cetacean sighting
survey was 690.17 n.miles. Primary sightings of common minke, sei and Bryde’s whales were one group / one
individual, one group / one individual, 23 groups / 24 individuals, respectively.

INTRODUCTION

The Japanese Whale Research Program under Special Permit in the North Pacific (JARPN) was conducted between
1994 and 1999. The main objective was to clarify the stock structure of common minke whale (Balaenoptera
acutorostrata) in the western North Pacific. As it proved that minke whales feed on a good deal of fisheries resources

such as Japanese anchovy (Engraulis japonicus) and Pacific saury (Cololabis saira) (Tamura and Fujise, 2002), thefeeding ecology was added in 1996 as a feasibility study. At the JARPN review meeting held in February 2000, theworkshop agreed that the sampling regime must be designed to allow for a more quantitative estimation of temporaland geographical variation in diet, and recommended that acoustic and trawl surveys should be conductedcooperatively with whale survey (IWC, 2001). In response to the recommendation, the government of Japan submitted
the Research Plan for Cetacean Studies in the Western North Pacific under Special Permit (JARPN II) (Feasibility
Study Plan for 2000 and 2001) to the 52nd IWC / SC (Government of Japan, 2002). Some outcome of the results of
JARPN feasibility study related to feeding ecology of cetacean was published in peer reviewed scientific journal(Murase et al., 2007). Based on successful results of the feasibility study, the study was expanded to full scale in 2002
(Government of Japan, 2002). Sei whale (B. borealis) was added as target cetacean species with minke, Bryde’s (B.
edeni), and sperm (Physeter macrocephalus) whales in the full-scale study.

18

The full-scale study in 2008 wasconducted in Sub-areas 8 and 9, off the coast of eastern Honshu, Japan in July. The whale survey is conducted tocollect diet data as well as other biological parameters of sei, Bryde’s, minke, and sperm whales, whereas the preysurvey was conducted to collect data on prey species of former three baleen whale species. This paper presented thecruise report of the prey species survey as a part of offshore component of JARPN II in 2008.

MATERIALS AND METHODS

The area of the cooperative whale and prey surveys was in Sub-areas 8 and 9 off the coast of eastern Honshu, Japan(Fig. 1). A zigzag track lines were set independently from whale sampling survey. Waypoints were listed in Table 1.
The research vessel, Kaiko-maru (KK1, 860 GT), departed Sendai-Shiogama port on 1 July, 2008. Prey distribution
and abundance surveys using the quantitative echo sounder, midwater trawl, Isaacs Kidd Midwater Trawl (IKMT) andTwin – NORPAC were conducted by KK1. In addition to the prey survey, KK1 conducted cetacean sighting survey.
During the daytime, KK1 steamed at about 10.5 knots along track lines to conduct cetacean sighting and acoustic
survey. Research hour was from an hour after sunrise to an hour before sunset while the maximum research hours
were set at 13 hours. Generally, the survey started at 5:00 and end at 18:00 at local time.
A quantitative echo sounder (Simrad EK 500) with operating frequencies at 38 and 120 kHz was used on board KK1 toacquire acoustic data. The transducers were hull-mounted at the depth of 4.3 m from the surface. Calibrations werecarried out at off the coast of Sendai-Shiogama before the prey species survey using the copper sphere techniquedescribed in the EK 500 manual (Simrad, 1997). Acoustic data were recorded while the KK1 steamed on the tracklines. Acoustic data were also recorded during net samplings.
The midwater trawl net was 86.3 m long with a mouth opening of ca. 900 m2 and a 6.0 m cod end with a 17.5 x 17.5mm mesh inner. The sampling depth and, the height and width of the mouth of the net were monitored with Simrad
PI32 Catch Monitoring System. Towing speed of the trawl net was 4 – 5 knots. Surface and midwater trawl was
towed at predetermined and target trawl stations. Surface trawls were conducted using the midwater trawl net with thefloats attached the bridle so that the trawl could be towed at the surface. Surface trawl was designed for collecting
mainly Pacific saury. Target trawls were conducted to identify the species and size compositions of biologicalbackscattering detected by the quantitative echo sounder.

Another type of trawling was also conducted at

predetermined stations in this survey. The purpose of the predetermined trawls was to estimate the abundance anddistribution patterns of cephalopods and neustonic organisms such as Pacific saury that are difficult to detect by theecho sounder. Two different depth layers were sampled at predetermined trawl stations; 0 – 30 m (surface) and 0 –100 m (midwater). Midwater predetermined trawl was towed for 10 minutes at each depth layer, 0 – 30 m, 30 – 60 m,
and 60 – 100 m whereas surface predetermined trawl was towed for 30 minutes. All samples were identified to thespecies as much as possible and wet weight of each species was measured aboard the ship. For the major species,
lengths of 100 individuals were measured to examine their size composition. A part of samples were frozen for further
analysis in the laboratory. In addition to the trawl net, IKMT was used to identify the species and size compositions ofmacro and meso zooplanktons detected by the quantitative echo sounder. Mouth opening of the IKMT was about 3.7 x
3.1 m and mesh size of cod end was 1.9 mm. The samples were preserved in 10 % formalin for species identification
at the laboratory. A small plankton net, Twin – the North Pacific standard net (NORPAC), equipped with flow meter
was towed at most of trawl stations to estimate abundance of copepods. The mouth opening of Twin – NORPAC are
45 cm, and mesh size of that 0.33 mm and 0.15 mm, respectively. Twin – NORPAC was towed from 150 m to surface
but it was towed various depth range in some cases to identify species compositions of acoustical backscattering.
Water temperature and salinity profiles at sampling stations were recorded by Conductivity – Temperature – Depth
profiler (CTD, SBE – 19 – 01, Seabird, USA). CTD data were recorded from surface to 500 m.
19

Cetacean sighting survey was conducted by KK1 while she steamed on the track lines. Primary observers wereallocated to the top barrel (3 observers) and the upper bridge (2 observers). Sighting survey was conducted in passing
mode though abeam closing was conducted if the sightings were baleen whales but the species was uncertain. Abeamclosing was conducted on sightings at a distance of 2 n.miles perpendicular to track lines.

RESULTS AND DISCUSSION

Most of track lines were surveyed by the quantitative echo sounder. Predetermined surface and midwater trawling was
conducted at 11 and 11 stations, respectively. Target trawl were conducted at 2 stations. Positions of surface andmidwater trawling were shown in Fig. 2. Summary of the results of trawling was shown in Table 2. Pink salmon(Oncorhynchus gorbuscha) and Japanese anchovy were dominant among sampled species. IKMT was towed at two
stations (Table 3, Fig. 3). Twin – NORPAC was towed at 23 stations (Table 4, Fig. 4). CTD cast was carried out 25
stations (Table 5, Fig. 5). Surveyed distance of cetacean sighting survey was 690.17 n.miles. About 57.2 % of planned
surveyed distance was surveyed in this survey. Primary sightings of common minke, Bryde’s, and sei whales were one
group / one individual, 23 groups / 24 individuals, and one group / one individual, respectively (Table 6, Figs. 6 - 10).

REFERENCES

Government of Japan. 2002. Research plan for cetacean studies in the western North Pacific under Special Permit(JARPN II). Paper SC / 54 / O2 submitted to the 54th IWC Scientific Committee Meeting.
International Whaling Commission. 2001. Report of the workshop to review the Japanese whale research programme
under special permit for North Pacific minke whales. J. Cetacean Res. Manage. (Suppl.) 3: 377-413.
Murase, H., Tamura, T., Kiwada, H., Fujise, Y., Watanabe, H., Ohizumi, H., Yonezaki, S., Okamura, H., andKawahara, S. 2007. Prey selection of common minke and Bryde’s whales in the western North Pacific in 2000 and
2001. Fish. Ocenog. 16: 186-201.
Tamura, T., and Fujise, Y. 2002. Geographical and seasonal changes of the prey species of minke whale in the
Northwestern Pacific. ICES J. Mar. Sci. 59: 516-528.

20

Table 1. Positions of waypoints in this survey

Waypoint

LatitudeLongitude

CourseDistance (n.mile)

612

46

‐

00

N

158

‐

00

E

223

123.4

611

44

‐

30

N

156

‐

00

E

109

91.2

610

44

‐

00

N

158

‐

00

E

236

105.8

609

43

‐

00

N

156

‐

00

E

124

106.9

608

42

‐

00

N

158

‐

00

E

236

108.1

607

41

‐

00

N

156

‐

00

E

123

109.2

606

40

‐

00

N

158

‐

00

E

237

110.4

605

39

‐

00

N

156

‐

00

E

122

111.5

604

38

‐

00

N

158

‐

00

E

238

112.5

603

37

‐

00

N

156

‐

00

E

122

113.6

602

36

‐

00

N

158

‐

00

E

239

114.6

601

35

‐

00

N

156

‐

00

E
Total

1207.221

Table 2. Summary of the results of surface and midwater trawls

0245-15.3

157-00.0

P

M

9.1

0−100

30

5.75

＋

6.80

03

44-30.0

156-00.0

P

S

9.7

0−30

30

8.85

＋

＋

10.54

04

44-15.0

157-00.0

P

S

10.8

0−30

40

12.50

＋

＋

13.70

05

44-00.0

158-00.0

P

S

10.0

0−30

30

9.10

＋

＋

9.35

06

43-30.1

157-00.0

P

M

11.6

0−100

30

1.80

0.09

＋

11.70

07

43-00.0155-59.8

P

S

13.7

0−30

30

＋

0.51

08

42-30.1

157-00.2

P

M

14.8

0−100

30

＋

0.17

09

42-23.1

157-14.0

T

S

16.1

0−30

45

＋

0.21

10

42-00.0

158-00.0

P

S

15.7

0−30

30

11

41-30.1

156-59.8

P

M

17.1

0−100

30

0.01

12

41-00.1

156-00.2

P

S

18.7

0−30

40

18.90

0.02

11.49

13

40-30.0

157-00.2

P

M

18.5

0−100

30

1.50

＋

0.08

14

40-00.1

158-00.0

P

S

19.6

0−30

30

＋

15

39-30.0

157-00.1

P

M

19.8

0−100

30

16

39-12.4

157-24.7

T

S

20.7

0−30

30

7.30

17

39-00.0155-59.8

P

M

20.4

0−100

30

0.02

18

38-30.1

157-00.0

P

S

21.1

0−30

30

19

37-59.8

158-00.4

P

M

22.3

0−100

30

6.90

1.65

＋
0.02

＋

0.07

<0.001

＋
0.01

0.02

0.16

＋

＋

＋

31.46

0.08

＋

＋

2.70

0.27

0.07

＋

2.80

＋

0.56

0.05
＋

︵ kg
︶
Total
25.78

Other squids＋

Japanese flying
squid

24.85

Other fishes

30

Oceanic
lightfish

Towing duration (min)0−30

Chum saimon

Target depth (m)7.9

Pink salmon

SST (°C)S

Pacific pomfret

M / S *2

PBlue mackerel

P / T *1

158-00.0

Chub mackerel

Longitude (E)46-00.0

Japanesesardine

Latitude (N)01JapaneseanchovyST

Catch （kg）

0.07

＋

＋

8.67
＋

0.27
0.74

＋

22

＋

＋

0.52

Table 2. Continued

Catch （kg）

M

23.8

0−100

30

＋

＋

0.61

22

36-28.8

156-59.9

P

S

23.5

0−30

30

＋

＋

0.13

23

35-59.7

158-00.6

P

M

24.2

0−100

30

＋

＋

0.62

26

34-59.4

155-58.7

P

M

24.3

0−100

30

＋

＋

0.68

︵ kg
︶
Total

P

Other
squids155-59.9

Japaneseflyingsquid

37-02.2

Other
fishes21

Oceanic
lightfish

Towingduration (min)30

ChumsaimonTarget depth
(m)
0−30

Pink
salmonSST (°C)
21.5

Pacific
pomfretM / S *2
S

Blue
mackerel

P / T *1P

ChubmackerelLongitude (E)156-59.8

Japanesesardine

Latitude (N)37-30.0

Japaneseanchovy

ST
20

ﾞ
0.31

0.07

1: P = predetermined trawl, T = target trawl
2: M = midwater trawl, S = surface trawl

23

Table 3. Summary of the results of IKMT

ST

Latitude(N)

Longitude
(E)

SST
(°C)

Target depth(m)05

44-01.0

158-05.5

10.3

30-40

25

35-01.3

156-12.1

23.8

170

Table 4. Summary of the results of Twin – NORPAC

Filtered volume (m3)ST

Latitude (N)Longitude (E)SST (°C)

Target depth (m)Mesh size

Mesh size

0.35 mm0.10 mm0145-57.5

157-55.5

7.9

150

30.6

28.2

02

45-10.6

156-54.8

9.0

150

25.4

26.4

03

44-29.1

156-05.5

9.5

150

23.7

22.6

04

44-15.3

157-07.6

9.9

150

29.3

27.9

05

44-01.0

158-06.4

9.9

150

18.4

29.7

06

43-27.0

156-52.8

11.3

150

51.3

49.2

07

43-04.0155-57.1

13.8

150

36.2

33.9

08

42-36.3

156-59.3

14.3

150

29.0

24.3

10

41-56.7

158-02.8

14.1

150

27.8

19.9

11

41-35.5

157-02.3

16.1

150

23.9

16.7

12

41-02.9

156-05.3

18.8

150

28.1

19.3

13

40-32.8

156-53.8

18.4

150

28.3

18.9

14

40-00.3

158-06.0

20.0

150

38.0

28.3

15

39-33.5

157-08.6

19.8

150

32.7

24.1

17

39-05.8

156-02.1

20.6

150

33.9

23.4

18

38-34.4

156-59.1

20.9

150

21.2

31.7

19

38-05.2

158-03.7

22.1

150

41.8

34.7

20

37-28.1

156-56.4

21.8

150

65.4

51.5

21

36-54.4

156-01.5

23.7

150

57.3

49.5

22

36-32.0

156-59.6

23.3

150

32.9

27.3

23

36-02.0

157-55.9

24.9

150

24.8

22.3

24

35-30.0

157-00.0

24.0

150

26.7

24.6

26

35-01.7

156-03.5

24.1

150

42.9

39.3

24

Table 5. List s of oceanographic observation stations

ST

Latitude (N)Longitude (E)0145-54.7

02

Water temperature (°C)
0m

100 m

200 m

157-53.0

7.8

1.7

3.3

45-10.6

156-54.8

9.2

3.2

3.0

03

44-29.3

156-05.5

9.8

2.7

3.3

04

44-15.4

157-08.1

10.0

2.2

3.1

05

44-01.0

158-06.2

9.9

2.2

3.1

06

43-26.8

156-52.4

11.3

2.7

3.2

07

43-03.9

155-57.0

13.9

6.8

5.5

08

42-36.5

156-59.0

14.3

4.9

3.9

09

42-22.6

157-15.3

16.3

7.9

5.5

10

41-56.7

158-03.0

15.7

10.4

6.6

11

41-35.5

157-02.3

16.2

10.4

7.3

12

41-03.1

156-05.1

18.9

8.6

5.4

13

40-30.2

157-00.1

18.8

10.5

7.1

14

40-00.4

158-06.1

19.8

10.8

6.1

15

39-33.8

157-08.7

19.8

13.7

10.6

16

39-15.2

156-28.7

20.8

12.4

9.8

17

39-06.1

156-02.1

20.5

8.6

5.7

18

38-34.5

156-58.9

20.9

12.4

9.8

19

38-05.5

158-04.1

22.1

12.4

9.6

20

37-28.5

156-56.5

21.7

11.7

9.7

21

36-53.6

156-02.0

23.7

16.2

13.7

22

36-31.6

156-59.7

23.4

14.3

10.9

23

36-02.0

157-56.0

23.9

16.8

12.4

24

35-30.0

157-00.0

23.3

16.1

14.2

26

35-01.8

156-03.4

24.1

16.1

13.7

25

Table 6. Summary of cetacean sightings

Primary

SpeciesSecondary

SchoolIndividual

SchoolIndividual

Common minke whale

1

1

0

0

Bryde’s whale

23

24

1

2

Sei whale

1

1

2

3

Sperm whale

19

43

1

1

Like common minke whale

1

1

0

0

Unidentified large whale

5

6

6

7

51N
50N
49N
48N
47N
46N
45N
44N
43N
42N
41N
40N
39N
38N
37N
36N
35N
140E

145E

150E

155E

160E

165E

170E

Fig 1. Survey area and the planned track lines. Orange thick line and broken gray line represented thetrack lines of KK1 and whale sampling line, respectively.

26

Figure 2. Positions of trawling stations.

Figure 3. Positions of IKMT trawling.

27

Figure 4. Positions of Twin – NORPAC towing.

Figure 5. Positions of CTD stations.

Figure 6. Primary and secondary sighting

Figure 7. Primary and secondary sighting

positions of Common minke and like minke whales

position of Bryde’s whales were

were overlaid on contour map of water

overlaid on contour map of watertemperature at 100 m.

temperature at 100 m.

28

Figure 8. Primary and secondary sighting positions of sei whales
were overlaid on contour map of water temperature at 100 m.

Figure 9. Primary and secondary sighting positions

Figure 10. Primary and secondary sighting positionsof sperm whales were overlaid on contour mapof unidentified large whales were overlaid onof water temperature at 100 m.

contour map of water temperature at 100 m.

29

Appendix 3.
Preliminary result of prey species survey in the offshore component of
JARPN II in 2008 conducted by Shunyo Maru
HIKARU WATANABE1* AND SAEKO KUMAGAI2

1National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa-ku, Yokohama,
Kanagawa 236-8648, Japan
2
The Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo 104-0055, Japan*Author in correspondence, e-mail: hikaru1@affrc.go.jp

ABSTRACTPrey species survey by Shunyo Maru was conducted in July and August 2008 in the Kuroshio andtransition regions of the western North Pacific. The objective of this survey is to examine preyenvironment and prey preference of Bryde’s whale Balaenoptera edeni in cooperation with the sampling
survey of the whale by Nisshin Maru and whale catcher boats. The distribution, abundance, and size
composition of the prey species were investigated with the midwater trawl, MOCNESS, Twin NORPAC
net, and quantitative echosounder in the daylight period. Euphausiiids and Japanese anchovy Engraulisjaponicus were the most and second most abundant prey species in the most part of the study area except

for the northernmost area close to the subarctic front, where euphausiids and mackerels were abundant.
Euphausiids and Japanese anchovy were generally distributed in the 100-200 and 0-30 m layers,respectively, and there distributions greatly overlapped horizontally. Bryde’s whales were mainly
distributed in the area where these two prey species were abundantly distributed and this whale mainly
fed on Japanese anchovy, suggesting prey preference for Japanese anchovy.

KEY WORDS: Prey species survey, offshore component, shunyo maru, JARPN II, prey biomass, prey
preference, Bryde’s whale

INTRODUCTION

The government of Japan submitted the Research Plan for Cetacean Studies in the Western North Pacificunder Special Permit (JARPN II) (Feasibility Study Plan for 2000 and 2001) to the 52th IWC/SC(Government of Japan 2000). The objective of this program is (1) studying on feeding ecology ofcetaceans and ecosystem modelling, (2) monitoring environmental pollutants in cetaceans and the marine
ecosystem, and (3) elucidating stock structure of whales in the western North Pacific, especially within
Japan’s EEZ (Government of Japan, 2002). This program would contribute to the conservation andsustainable use of marine living resources including marine mammals. The priority of this plan is to
examine feeding habits of major cetacean species and ecosystem studies, including studies on prey30

consumption by cetaceans, prey preference of cetaceans, and ecosystem model. In JARPN II program,
prey species surveys have been conducted in cooperation with the whale sampling surveys to estimate theabundance of each prey species and prey preference of cetaceans. In 2008, prey species surveys wereconducted in the offshore region of the western North Pacific by the two stern trawler-type research
vessels, Shunyo Maru (887 GT, National Research Institute of Far Seas Fisheries) and Kaiko Maru (860
GT, Kaiko Senpaku Co., Ltd.). This appendix presents results of prey species survey conducted by
Shunyo Maru attempting to quantify the prey environment and prey preference of Bryde’s whale
Balaenoptera edeni during summer.

MATERIALS AND METHODS

Prey species survey was conducted from 21 July to 3 August 2008 in the Kuroshio and Kuroshio-Oyashiotransition regions between 35˚N to 41ºN, and 146ºE and 148ºE in Sub-area 7 except for Russian EEZ (Fig.
1). In this area, zigzag track lines were set and distribution and abundance of the prey species were
investigated with the midwater trawl, MOCNESS, Twin NORPAC net, and quantitative echosounder onthese lines. The waypoints of planned track lines are shown in Table 1. During the survey from 21 to 27
July, sampling survey of Bryde’s whale was also conducted on the same track lines from WP1 to WP 5
and time difference between the prey and whaling surveys was less than two days, indicating that bothsurveys were conducted concurrently in this period. All prey surveys were conducted in the daylightperiod from one hour after sunrise to one hour before sunset (generally from 05:00 to 17:00 in local time).

Midwater trawl sampling

The midwater trawl adopted in this study had a mouth opening of about 30 x 30 m with a 17.5 mm liner
cod end. The sampling depths and the height of the net mouth were monitored by net monitor system(PI32, SIMRAD). Towing speed was 3-4 knots. 21 midwater trawl surveys were conducted (Table 2). Of
these, the target trawls were made two times to identify species and size compositions of acoustic
backscatters of the fish. Target trawls were continued until targeted schools were captured through or
maximum trawling duration reaches at 60 minutes. The results of target trawls were shown in Table 2(Stations 12 and 16), indicating that the acoustic backscattering detected in this study was Japanese
anchovy Engraulis japonica. Other 19 trawls were so-called ‘predetermined trawling’ (Table 2). Those
were aimed to examine the distribution and abundance of squids and neustonic organisms like Pacificsaury, which are difficult to detect by the echosounder. This trawling was made generally every 20 to 30
nautical miles on the track lines regardless of acoustic backscatters. At each predetermined station, a trawl
net was towed at 0-100 (oblique tow) or 0-30 m for 30 to 60 minutes in principal. All samples wereidentified to the lowest taxonomic level possible and wet body weight of each species was measured
aboard the ship. For the major species, body length of each individual was measured from randomly
selected 100 individuals. When sample size was less than 100 individuals, body length was measured for31

all individuals. We also measured the total wet weight of these samples to estimate the total catch number
for each sampling.

MOCNESS sampling

We used MOCNESS to examine species and size compositions and vertical distribution patterns of mesoand macro-zooplanktons, especially euphausiids. The mouth opening and mesh size of this net were 1 m2
and 0.33 x 0.33 mm, respectively. At the eight predetermined stations, this net was towed at about 2 knots
in eight target depths (0-20m, 20-40m, 40-60m, 60-80m, 80-100m, 100-150m, 150-200m, and 200-250m)
in the daytime (Table 2). The volume of seawater filtered by each net was measured with a flow meter
mounted at the net mouth. Samples were preserved in 10 % formalin-buffered seawater at sea for further
analysis in the laboratory ashore.

Twin NORPAC net sampling

We conducted Twin NORPAC net samplings in the 0-150 m layer at each trawl and MOCNESS samplingstation to estimate abundance of micro- and meso-zooplanktons in the epipelagic zone. The mesh sizes of
the net were 0.11 x 0.11 mm and 0.33 x 0.33 mm. A flow meter was attached to each net to measure thevolume of seawater filtered. Samples were preserved in 10 % formalin-buffered seawater.

Quantitative echosounder survey

We operated the quantitative echsounders, SIMRAD ER60, by moving at about 10.5 knots on the tracklines to acquire acoustic data with operating frequency at 38, 70, and 120 kHz. Calibrations were carriedout in the Kuroshio extension region off Tateyama on 19 July using copper sphere technique. Acoustic
data will be analyzed with an aid of SonarData Echoview (Sonar Data Co., Ltd.) software.

Oceanographic observation

A Conductivity-Temperature-Depth (CTD) profiler cast was made down to 500 m depth at each samplingstation to determine the position of the Kuroshio front, subarctic boundary, and subarctic front.

RESULTS and DISCUSSION

In this study, planned track lines were completely surveyed. Acoustic data, plankton samples, andoceanographic conditions are being analyzing now, the preliminary results are as follows. CTD and SST
data indicated that the southernmost region of the study area between 35˚N and 35˚30’N were located in
the Kuroshio region, the northernmost area north of 40˚N were in the transitional domain between

32subarctic boundary and subarctic front, and other region was in the transition zone south of the subarctic
boundary.
According to Tamura (unpubl. data), hot spot of Bryde’s whale was found in the southern transition
region between 35˚30’N and 36˚30’N and northern transition region between 38˚30’N and 39˚30’N,
where were located in or close to the Kuroshio front and the subarctic boundary, respectively. The resultof our prey species survey indicated that these two oceanographic front areas were prey rich environment
for the whale because juvenile and adult Japanese anchovy were abundantly distributed in the former andthe latter regions, respectively, and euphausiids were abundantly distributed in the both regions (Figs. 2, 3,
and 4). Generally, both juvenile and adult Japanese anchovy were mainly distributed at 0-50 m anddistribution centre of euphausiids were found at 100-200 m (Figs. 2 and 4). Bryde’s whale fed mainly on
juvenile and adult Japanese anchovy in the southern and northern transition region, respectively (Tamura
unpubl. data), suggesting that this whale preferred both juvenile and adult sized Japanese anchovy andavoid euphausiids. This indicates that Bryde’s whale possibly affects the fluctuations of both recruitment
success and adult biomass of Japanese anchovy. These results also suggest that Bryde’s whale prefer preyrich environment in or close to the Kuroshio front and subarctic boundary where small epipelagic fishes
are abundantly distributed in the transition zone.
In the Kuroshio region south of 35˚30’N and transition zone between 36˚30’N and 38˚30’N, bothpotential prey species like anchovy, saury, and euphausiids and Bryde’s whale were rarely distributed andstomach contents of the whale captured in these regions were almost empty (Tamura unpubl. data). In thenorthernmost part of the study area located between the subarctic boundary and subarctic front,
euphausiids were abundantly distributed in the 100-200 m depth layer but Japanese anchovy almost
disappeared and replaced by mackerel Scomber spp. (see Stations 13 and 15 in Table 2). Bryde’s whales
were frequently found in this region, but sampling survey of the whale was not conducted (Tamura
unpubl. data).

Acknowledgement

A special thank is given to Captain Y. Terada and crews of Shunyo Maru for their assistance in collecting
data.

REFERENCES

Government of Japan. 2000. Research plan for cetacean studies in the western North Pacific under special
permit (JARPN II) (Feasibility study plan for 2000 and 2001). Paper SC/52/O1 submitted to the 52th
IWC Scientific meeting.
Government of Japan. 2002. Research plan for cetacean studies in the western North Pacific underSpecial Permit (JARPN II). Paper SC/54/O2 submitted to the 54th IWC Scientific Meeting.

33

Table 1. Waypoints of planned track lines.
WP Latitude (N) Lingitude (E)135ū00.0'
148ū00.0'236ū30.0'
146ū00.0'
338ū00.0'
148ū00.0'439ū30.0'
146ū00.0'540ū25.0'147ū12.0'
6
7
8
9
10

41ū00.0'39ū30.0'38ū00.0'36ū30.0'35ū00.0'

146ū00.0'
148ū00.0'
146ū00.0'
148ū00.0'
146ū00.0'

Table 2. Sampling data of midwater trawl and MOCNESS surveys. P: predeterminedtrawl; T: targeting trawl; +: 0.01 kg < CPUE.
Midwater trawl
Sampling
CPUE (kg/h)
SST Latitude
Longitude
Sampling depth (m) duration Japanese Mackerel Other Pacific Common OtherStn P/T Year Month Day (ūC) Degree Minute N/S Degree Minute E/W Shallowest Deepest (min) anchovy
fishes pomfretsquid
squids1
P 20087
21 25.9
35
15.9
N
147
38.8
E
0
90
60
0
0
0
0
+
0
3
P 2008722 25.6
36
12.4
N
146
25.5
E
0
30
60
1.9
0.28
0.02
0
0
0
4
P 20087
22 24.1
36
45.4
N
146
20.3
E
0
90
60
0.01
0
0
0
0
0
6
P 20087
23 23.5
37
44.9
N
147
40.6
E
0
30
60
+
0
0
0
0
+
7
P 20087
24 23.9
38
4.5
N
147
54
E
0
90
60
0.02
0
0
0
0
0
8
P 20087
24 23.2
38
35.5
N
147
12.7
E
0
30
60
0.53
0
0
0
0
0
9
P 2008725 23.2
38
57.7
N
146
44.1
E
0
30
60
+
0
0
0
0
0
11 P 20087
26 20.9
39
54.3
N
146
31.5
E
0
90
60
0.01
0
0
0.08
0
0
12 T 20087
26 19.4
40
5.5
N
146
46.1
E
0
30
60
0.42
0
0
0
0
0
13 P 20087
27 17.5
40
24.5
N
147
12.7
E
0
30
60
0.12
28.0
0
0
0.18
0
15
16
17
19
20
21
23
24
25
27
28

P
T
P
P
P
P
P
P
P
P
P

2008
2008
2008
2008
2008
2008
2008
2008
2008
2008
2008

7
7
7
7
7
7
8
8
8
8
8

28
28
29
30
30
31
1
1
2
3
3

18.2
21.7
22.3
22.2
24.3
24.6
24
27.3
27.9
28.4
27.6

40
40
40
39
38
38
37
36
36
35
35

38.3
16.4
4.2
8.7
27.6
6.8
13.0
50.1
32.5
40.3
8.1

N
N
N
N
N
N
N
N
N
N
N

146
147
147
147
146
146
147
147
147
146
146

29.3
2
14.6
30.6
36
8.6
2.8
36.1
58.2
52.1
8.9

E
E
E
E
E
E
E
E
E
E
E

0
0
0
0
0
0
0
0
0
0
0

30
30
90
30
90
30
30
90
30
30
90

MOCNESSSST Latitude
Longitude
Sampling depth (m)Stn P/T Year Month Day (ūC) Degree Minute N/S Degree Minute E/W Shallowest Deepest
2
P 20087
21 26.9
35
52.5
N
146
55.3
E
0
250
5
P 20087
23 24.7
37
5.1
N
146
46.8
E
0
250
10 P 2008725 19.2
39
31.7
N
146
1.8
E
0
250
14 P 20087
27 22.8
39
56.0
N
146
33.6
E
0
250
18
22
26
29

P
P
P
P

2008
2008
2008
2008

7
7
8
8

29
31
2
4

21.8
24.5
28.3
26.7

39
37
35
35

30.1
29.3
58.8
0.0

N
N
N
N

147
146
147
146

59.8
39.6
18.4
0.0

E
E
E
E

0
0
0
0

34

250
250
250
250

60
60
60
60
60
60
60
60
60
60
60

0
0.4
0.08
0.40
+
+
0.3
0.39
0
0
2.52

565.73
0
0
0
0
0
+
+
0
0
0

0.14
0
0.39
0
0
0
0
0.09
0
0
0

0
0
0
0
0
0
0
0
0
0
0

5.52
0
0
0
0
0
0
0
0
0
0

0
0
0
0
0
0
0
+
0
+
0.02

Sub area 7

Sub area 8

Fig 1. Research area, planned track lines, and sampling positions of offshore preyspecies survey in 2008.

Fig 2. Typical acoustic backscatterings around at Station 3 in the southern transition
region close to the Kuroshio front where Bryde’s whale was densely distributed.

35

50

Size frequency (%)

40

30

20

10

0
2

3

4

5

6

7

8

9

10

11

12

13

14

Body length (cm)Fig 3. Species composition of predetermined trawl samples and size distribution ofJapanese anchovy at Station 3 located in the southern transition region where hot
spot of Bryde’s whale was found. Bryde’s whale fed mainly on juvenile ofJapanese anchovy around this station.

Japanese anchovy

Euphausiid

Fig. 4. Typical acoustic backscatterings around at Station 8 in the northern transition
region close to the subarctic boundary where Bryde’s whale was densely
distributed.
36

60

Size frequency (%)

50

40

30

20

10

0
2

3

4

5

6

7

8

9

10

11

12

13

14

Body length (cm)Fig. 5. Size distribution of Japanese anchovy at Station 8 located in the northerntransition region where hot spot of Bryde’s whale was found. All samples
collected at this station were Japanese anchovy. Bryde’s whale fed mainly on
adult sized Japanese anchovy around this station.

37

Appendix 4.
Oceanographic conditions in the survey area of offshore compoent of
JARPN II in the western North Pacific from July to August 2008

Denzo Inagake*, Makoto Okazaki*, Hikaru Watanabe**, Shiroh Yonezaki**,
Saeko Kumagai**, Hiroto Murase**, and Tomio Miyashita ****National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa,236-8648, Japan**

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa,236-8648, Japan***The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo, Tokyo, 104-0055, Japan

Contact e-mail: ina@affrc.go.jp

ABSTRACTA prey species survey was conducted in July-August 2008 using Kaiko-Maru, Kyoshin-Maru No.2 andR/V Shunyo-Maru as a part of offshore component of JARPN II. The survey covered from subarctic area
to the adjacent area of the subtropical area in the western North Pacific where common minke, Bryde’s
and sei whales were found. During the survey, oceanographic observation with CTD and XCTD wasmade to make clear the environment of the prey. The survey area was located between the Kuroshio
Extension and the Subarctic Front, The water mass was characterized by the subarctic water, subtropicalwater and mixed water.

Introduction

A prey species survey was conducted in the offshore area of the western North Pacific in July-August
2008 using Kaiko-Maru, and R/V Shunyo-Maru (Fig. 1) in cooperation with the sampling survey by
Nisshin-Maru. Common minke, Bryde’s and sei whales were found in the survey blocks.

38

There are a lot of water masses and fronts in the western North Pacific. The Oyashio flows
southwestward along the Kuril Islands and turns eastward from the northern coast of Japan. The
Kuroshio flows northward from the tropical area to Tohoku area east of Japan, and reaches near the
Oyashio front. The Kuroshio turns eastward from the northern coast of Japan, and the strong eastward
flow is called the Kuroshio Extension. Both major current, the Kuroshio Extension and the Oyashio,
form Kuroshio-Oyashio Inter-frontal Zone. Water masses originated in the Kuroshio and the Oyashio are
mixed each other in this zone and form new water masses. In the high sea of the North Pacific Ocean,
there are Subarctic Front (temperature front defined by 4 ºC) and the Subarctic Boundary (salinity front
defined by 34.0psu) with a weak eastward flow. The Subarctic Front is south limit of the subarctic waterand the Subarctic Boundary is north limit of the tropical water.
The area between these fronts is called the Transition Domain (Favorite et al. 1976). Each water massin the western North Pacific has its own ecosystem, like a Kuroshio ecosystem, an Oyashio ecosystem,
warm-core ring ecosystem, etc. So, we must make clear the oceanographic condition around whale’s
prey to build up a marine ecosystem model in this area. In this paper, distributions of water masses andfronts in the survey area will be described to make clear the environment of the prey of sei, Bryde’s andcommon minke whales.

Methods

Hydrographic observations with a conductivity-temperature-depth profiler (CTD) and expendable
CTD (XCTD) were carried out in the survey area from July to August 2008 (Table 1 and Fig. 1). Three
research vessels, Kaiko-Maru, Kyoshin-Maru No.2 and Shunyo-Maru conducted the hydrographic
observations. Salinity correction for CTD data was not done using water sampling data. Locations ofoceanic fronts and water masses are usually detected based on subsurface temperature map (see Table 2),
because they are obscure in sea surface temperature distributions from summer to fall and the Oyashio
water spreads into the subsurface layer. The oceanographic conditions in July-August 2008 are detectedby 100m and 200m temperature maps using our observation data by three vessels as well as NEARGOOS (the North-East Asian Regional-Global Ocean Observing System) database. We use following
indices to know the distribution of water mass in the survey area. The Kuroshio Extension is defined by
the 14 ºC isotherm at the depth of 200m (Kawai, 1969). The warm water spread from Kuroshio
Extension is defied by temperature more than 10 ºC at the depth of 100 m. The first and the second
Oyashio Intrusions are defined by temperature lass than 5 ºC at the depth of 100 m (Murakami, 1994).
Subarctic front and the Subarctic Boundary is defined by 4 ºC temperature front and 34.0psu salinity front,
respectively (Favorite et al. 1976).

Oceanographic conditions in the survey area

Fig. 2 shows the Temperature-Salinity diagrams in the survey area. There is typical Kuroshio water
characterized by high salinity profile around 34.5 psu, especially in warm upper layer (over 10 ºC).

39

Oyashio water (colder than 5 ºC) and Subarctic waters characterized by cold profile less than 4 ºC isshown in lower part of Fig. 2. The mixed water is distributed between both of the Oyashio and theKuroshio waters.
Figure 3 shows a schematic hydrographic map with isotherms of 100 m temperature in July-August
2008. The cold water less than 5 ºC at 100 m depth was distributed in a northern part of the survey area.
The Subarctic Front (defined by 4 ºC isotherm) was observed from 41ﾟN, 150ﾟE to 43ﾟ-30’ N, 165ﾟE in
Fig. 3. In 100 m salinity map (lower panel in Fig. 4), a salinity front around 34.0 psu is shown along 40ﾟ
N line in the western part of the survey area, and it meandered around 42ﾟN line in the middle and easternpart of this area. The warmest temperature at the 200 m depth is observed at south western part of thisarea, and 14 ºC isotherm, which is an index of the Kuroshio Extension, is observed along 35ﾟN line
(upper panel in Fig. 4).
Figure 5 shows temperature, salinity and density anomaly sections between 146ﾟE-148ﾟE. The
Subarctic Water (colder than 4 ºC) and 4 ºC isotherm (index of the subarctic front) is observed around40ﾟ30’N. The salinity front around 34 psu (index of the subarctic boundary) is shown around 40ﾟN
nearby the subarctic front. The Kuroshio Extension is appeared around 35ﾟ30’N (westward flow) and36ﾟ45’N (eastward flow) according to meandering of the current in this section.
Figure 6 shows the vertical sections of temperature, salinity and density anomaly along the cruise
track of Kaiko-Maru along 157ﾟE. The Subarctic Water colder than 4 ºC is observed in the northern area,
north of 42ﾟ30’N, where the 4 ºC isotherm observes vertically from 50 m depth to 400 m depth. It
indicates that there is the subarctic front around 42ﾟ30’N in this section. A surface low salinity water lessthan 33.5psu is also observed in the northern area, north of 43ﾟN. The isohaline of 34 psu, which is theindex of the subarctic boundary, is shown at a surface layer around 42ﾟN, a little southern area of thesubarctic front (middle panel in Fig. 6). In this section, isotherms between 5 ºC and 10 ºC are running
vertically and show an existence of a temperature front around 42ﾟN. As there is high-salinity water over
34.7 psu is observed around 35ﾟ30’N, isotherms around 35ﾟ30’N are running vertically and 14 ºC
isotherm cross at the depth of 200 m around 35ﾟ30’N, the Kuroshio Extension flows at 35ﾟ30’N in thissection.
Figure 7 shows temperature, salinity and density anomaly sections between 165ﾟE-170ﾟE, easternpart of our survey area. The Subarctic Water is observed in the northern area, north of 42ﾟ30’N where is
4 ºC isotherm (index of the subarctic front) running vertically from 50 m to 500 m depth. The highsalinity water greater than 34 psu is shown at a surface layer in the southern area, south of 41ﾟ30’N, andthe isohaline of 34 psu (index of the subarctic boundary) was observed around 41ﾟ30’N with a typicalsalinity front (33 to 34.4 psu). The Kuroshio Extension is not appeared in this section.
These figures show that the survey area is located between the Kuroshio Extension and the Subarctic
Front.

40

REFERENCES

Favorite, F., A. J. Dodimead and K. Nasu (1976): Oceanography of the subarctic Pacific region, 1960-71.
Bull. International North Pacific Fisheries Commission, 33, 187 pp.
Kawai, H. (1969): Statistical estimation of isotherms indicative of the Kuroshio axis, Deep-Sea Res.,
Suppl. to 16, 109-115.
Murakami, M. (1994): On long-term variations in hydrographic conditions in the Tohoku area, Bull.
Tohoku Natl. Fish. Res. Inst., No. 56, 47-56 (in Japanese with English abstract).

41

Table 1. Observation summary.

Ship

Instrument

Date

Number ofstations

Kaiko-Maru

CTD: SBE 19

5 July to 29 August

50

XCTD: TSK MK-130

Kyoshin-Maru No.2

CTD: SBE 19

7 July to 29 August

35

Shunyo-Maru

CTD: BE 9plus

21 July to 4 August

29

Table 2. Extraction method from temperature map to determine the position of eachwater mass.

Target characteristics

Extraction method

Kuroshio Extension Axis 14 ºC isotherm at 200 m
Warm-core ringTemperature front at 200 m

Oyashio front

5 ºC isotherm at 100 m

Oyashio water

Area with T<5 ºC at 100 m

Cold water

Area with 5 ºC <T< 10 ºC at 100 m

Warm water

Area with T> 10 ºC at 100 m and T< 14 ºC at 200 m

Subarctic Boundary

Salinity front defined by 34.0 psu

Subarctic Front

Temperature front defined by 4 ºC

42

Fig. 1. Station map observed by Kaiko-Maru in 5th July to 29th August 2008 (upper
panel), Kyoshin-Maru No.2 in 7th July to 29th August 2008 (middle panel) and
R/V Shunyo-Maru 21st July to 4th August 2008 (lower panel).

43

Fig. 2. Temperature-Salinity diagrams using CTD and XCTD station data observed by
Kaiko-Maru (left upper panel), Kyoshin-Maru No.2 (left lower panel) and R/VShunyo-Maru (right upper panel). Each thin line in this figure denotes a density
line of sigma-t.

44

Fig. 3. Schematic hydrographic map in the western North Pacific in July-August 2008 with station
map observed by Kaiko-Maru, Kyoshin-Maru No.2, R/V Shunyo-Maru and reported to
GTSPP.

45

Fig.4. Temperature at 200 m depth (upper panel) and salinity map at 100 m depth (lower panel),observed by Kaiko-Maru, Kyoshin-Maru No.2 and R/V Shunyo-Maru in July 5 to August29.

46

Fig. 5. Vertical sections of temperature (upper panel), salinity (middle panel) and density anomaly(lower panel) observed by R/V Shunyo-Maru in August 5 to 13 (western part of our surveyarea).

47

Fig. 6. Vertical sections of temperature (upper panel), salinity (middle panel) and density anomaly(lower panel) observed by Kaiko-Maru along 157 ﾟ E (middle part of our survey area).

48

Fig. 7. Vertical sections of temperature (upper panel), salinity (middle panel) and density anomaly(lower panel) observed by Kyoshin-Maru No.2 in July 13 to 24 between 149 ﾟ E-151 ﾟ E(eastern part of our survey area).

49