SC/56/O14

Report of the coastal survey on common minke whales off Sanriku
coast, northeast Japan: the Japanese Whale Research Program underSpecial Permit in the western North Pacific - Phase II (JARPN II) in
2003 (Part II) - Coastal component.
HIDEYOSHI YOSHIDA1, HIDEHIRO KATO1, TOSHIYA KISHIRO1, TOSHIHIDE IWASAKI1, TOMIOMIYASHITA1, TAMEO RYONO2, SHIGEO TABATA2, MIZUKI SAKAKIBARA3, SHIGEO SAINO2, TAKAHIROHARA2, TAKENOBU HAYASHI2, YASUHIRO TOMIZAWA2, KANJI TAMAI4, RYOSUKE OKAMOTO5,MASAAKI FUKUOKA2, HIKARU WATANABE2, MASAOMI TSUNEKAWA2 AND SHIGEYUKI KAWAHARA1
Contact e-mail:hideka@fra.affrc.go.jp
1

National Research Institute of Far Seas Fisheries, 5-7-1, Shimizu-orido, Shizuoka, 424-8633, Japan

2

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

3

Hokkaido University, 3-1-1, Minato-cho, Hakodate, 041-8611, Japan

4

Kagoshima University, 1-21-24 Kohrimoto, Kagoshima, 890-0065, Japan

5

Nihon University, 1866 kameino, Fujisawa, 252-8510, Japan

ABSTRACTThe second survey of the JARPN II coastal component was conducted from 8 April to 2 May 2003, off the Sanriku
coast, northeast Japan (middle part of the sub-area 7), using four small-type whaling catcher boats, one echosounder-trawl survey vessel, and one dedicated sighting survey vessel. Sampling of common minke whales was
conducted in the coastal waters within 30 nautical miles from Ayukawa port in the Sanriku, and all animals collected
were landed on the JARPN II research station established in the port for biological examination. During the survey, atotal of 3,833.6 n. miles (342.9 hours) was surveyed for whale sampling, and 184 schools (188 individuals) of thecommon minke whale were sighted and 50 animals were caught. Average body length of the animals was 6.28m(SD=0.89, n=21) for males and 6.30m (SD=1.12, n=29) for females. Dominant prey species found from the firststomach of the animals were Japanese sand lance Ammodytes personatus and Krill Euphausia pacifica. The present
survey was conducted to cover the temporal and spatial gap, in which the Nisshin-Maru and the large research vessels
can not be operated. No serious practical problem occurred during the present survey. Thus, the 2003 coastal survey
off the Sanriku was conducted successfully.

KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; FOOD/PREY; ECOSYSTEM; SCIENTIFICPERMITSINTRODUCTION
After the two-year feasibility study in 2000-2001, the full-scale survey of the Japanese Whale
Research Program under Special Permit in the western North Pacific-Phase II (JARPN II) wasstarted in 2002. The main purpose of the program is to evaluate competition between whales andfisheries, and to clarify the role of the cetaceans in the marine ecosystem of the western North
Pacific (Government of Japan, 2002a). The target species in the full-scale JARPN II are the common
minke whale Baraenoptera acutorostrata, the Bryde’s whale B. edeni, the sei whale B. borealis andthe sperm whale Physeter macrocephalus.
1

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

The JARPN (1994-1999) and the JARPN II feasibility study (2000-2001) revealed that common
minke whales are widely distributed from offshore waters to coastal waters and feed on various preyspecies such as Japanese anchovy, Pacific saury, and walleye pollock (Government of Japan, 2002b;
Tamura and Fujise, 2002). The coastal waters of Japan is also very important fishing ground. Thus, itis thought that competition between the whales and fisheries is severe in the coastal waters. However,
the Nisshin-Maru and large research vessels can not be operated in the near shore areas, because of
their movement restrictions. Furthermore, the vessels can not work in the coastal waters from lateautumn to early spring because of their practical availability. In order to cover the temporal andspatial gap of the vessels, sampling of common minke whales in the coastal waters using small-typewhaling catcher boats was introduced. This coastal survey was planned as the feasibility study in thefirst two years (2002 and 2003) in order to check the logistic feasibility and consisted of threeresearch components as follows; 1) coastal whale sampling survey by small-type whaling vessels, 2)
coastal prey species survey by one echo sounder-trawl survey vessel, and 3) dedicated sighting
survey by one research vessel. The coastal survey was authorized by the Government of Japan incompliance with Article VIII of the International Convention for the Regulation of Whaling. The
National Research Institute of Far Seas Fisheries (NRIFSF), Fisheries Research Agency, planned andconducted the survey entrusted by the Institute of Cetacean Research (ICR).
The first feasibility survey was conducted from 10 September to 12 October 2002 in coastal waters
off Kushiro, northeast Japan and finished successfully (Kishiro et al. 2003). In the present paper, weshow results of the second survey carried out in coastal waters off the Sanriku, Japan, from 8 April to
2 May 2003.

MATERIALS AND METHODS
Research area
In coastal waters off the Sanriku district (northeast part of the Pacific coast of the Japanese mainisland, Honshu), many common minke whales were taken, especially in spring, by the pastland-based coastal whaling (Miyashita and Hatanaka, 1997). The coastal waters is also very
important fishing grounds. Thus, the waters is thought to be suitable for the study area to evaluate
competition between whales and coastal fisheries. For the whale sampling survey, we established theresearch area within the 30 nautical miles from the Ayukawa port in the Sanriku (Fig. 1). The
distance, 30 n. miles, was placed after discussion, to keep freshness of whale stomach contents. The
survey area is included in the middle part of the sub-area 7 determined by the IWC.

Research vessels and station
Whale sampling survey
Four small-type whaling catcher boats, Taisho Maru No. 28 (hereinafter referred as T28; 47.3GT),
Koei Maru No. 75 (75K; 46.0GT), Katsu Maru No.7 (7K; 32.0GT), and Sumitomo Maru No.31(31S; 32.0GT) were used as sampling vessels. The sampling survey was conducted from 10 April to2

SC/56/O14

2 May, 2003. All the animals collected were landed on the JARPN II research station established in
the Ayukawa port for biological examination and by-products.

Prey species survey
The Kaiyo Maru No.7 (KY7; 499.0GT), the echo sounder-trawling survey vessel, conducted theprey species survey in wider research area off northeast coast of Honshu, from 8 to 28 April. This
area included the coastal waters off the Sanriku, where the sampling survey was carried out. Detailof the prey species survey is shown in Appendix 1. The Kaiyo maru No. 7 also conducted thehydrographic observations using the conductivity-temperature-depth profiler (CTD; SBE 19plus
SEACAT Profiler) from 10 to 24 April in the Kuroshio-Oyashio Inter-frontal Zone. Oceanographic
conditions revealed from the observations are shown in Appendix 2.

Dedicated sighting survey
The Shonan Maru (SM1; 712.0GT) was engaged as a dedicated sighting survey vessel. The sighting
survey was also conducted from 8 to 28 April, following zigzag track lines predetermined in theidentical research area, where the prey species survey was carried out. Detail of the survey is shownin Appendix 3.

Sighting and sampling methods
Sighting and sampling methods were same in the first survey conducted in Kushiro 2002 (Kishiro etal. 2003). The research head office was placed in the research station and controlled the sampling
vessels during the survey. The office determined the searching area and routes of sampling vessels
everyday, from weather conditions, whale distribution, and information on fishing grounds.
In each sampling vessel, a researcher was onboard and recorded sighting and sampling information,e.g., coordinates and time of common minke whales sighting and sampling made, weather conditions,and vessel movements. Sighting information was also recorded for other baleen whales and sperm
whales. Searching effort was conducted from the top barrel and upper bridge by all the crews and theresearcher. All common minke whales sighted were targeted for sampling, except for the cow-calfpair. When a school consisted of plural animals, sampling target was selected randomly from theschool. Sampling was carried out using 50 mm whaling cannon. Once the vessel caught a whale, shereturned to the Ayukawa port as soon as possible, to land the animal on the research station. At theport, animals taken were lift up from the vessel by the crane, using a wire net and then transported tothe station by a 11-tons freight trailer. At that time, animal body weight was measured with the truck
scale.

Biological research for common minke whales collected
All the animals collected were examined biologically by researchers at the research station. Research
items of the biological examination are summarized in Table 4, with the number of data and samples
3

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

obtained. These items are related to studies on feeding ecology, stock structure, life history andpollutions.

RESULTS
Searching effort made by sampling vessels
Cruise tracks made by the four sampling vessels (28T, 75K, 7K, and 31S) during the survey are
shown in Fig.2a. The searching areas covered widely coastal waters within 30 nautical mails form
the Ayukawa port, but most of them concentrated in the middle part of Sendai Bay. Searching
distance and time made by four sampling vessels are listed in Table 1. Here, searching distance andtime are defined as the distance and time recorded under the searching effort from the top barrel ofthe vessels. Total searching distance and time made by the four vessels were 3,833.6 n. miles and342.9 hours, respectively.

Common minke whale sightings made by sampling vessels
Sighting positions of common minke whale schools made by the sampling vessels are shown in Fig.
2b. During the survey, a total of 184 schools (188 animals) of common minke whales were sighted:
157 schools (161 animals) of primary sightings and 27 schools (27 animals) of secondary sightings(Table 2). These figures probably include some duplicated sightings made by plural vessels, because
sampling vessels searched almost same areas. In the last survey in Kushiro 2002, large cetaceans,e.g., fin whales and humpback whales, were sighted (Kishiro et al. 2003), but no sightings of otherlarge cetaceans were obtained in the present survey. Table 3 shows temporal change in density index(SPUE: number of primary school sightings per one hour searching, and DI: number of primaryschool sightings per 100 n. miles searching) of common minke whales recorded by the sampling
vessels. Both SPUE and DI increased from the first to second period of the survey, and thendecreased in the third period. During the survey, primary sightings of 0.47 schools were recorded per
one hour searching, and primary sightings of 4.20 schools were obtained per 100 n. miles searching.
These figures are nearly the same recorded in the last survey conducted in Kushiro 2002 (Kishiro etal. 2003).

Sampling of common minke whales
A total of 50 common minke whales were taken for biological research. In the sampling process,there were no harpooned-missed animals (i.e., no struck-lost animals). Sampling positions ofindividuals are shown in Fig. 2c. Animals were taken evenly from whales sighted.

Prey species survey and dedicated sighting survey
The prey species survey was conducted using the echo sounder-trawling survey vessel (KY7). The
distribution and abundance of the prey species were investigated with the mid-water trawl,
IKMT(Isaacs-Kidd Midwater Trawl), Bongo net, and quantitative echosounder (EK60). The
Japanese anchovy, sand lance, and krill were found. The dedicated sighting survey was carried out
4

SC/56/O14

using the sighting survey vessel (SM1). Four schools of common minke whales were detected.
Sightings of the fin whale, the humpback whale, the right whale, and the sperm whale were also
obtained. Results of these surveys are noted in Appendix 1 (the prey species survey), Appendix 2(the oceanographic observations), and Appendix 3 (the dedicated sighting survey).

Sex ratio, body length and weight of sampled whales
The 50 animals taken consisted of 21 males and 29 females (sex ratio of males to all animals was0.42). Average body length of animals was 6.28m (max=7.83, min=4.70, SD=0.89) for males and6.30m (max=8.02, min=4.28, SD=1.12) for females (Table 5). Average body weight was 2.92 tons
(max=5.06, min=1.32, SD=1.08) for males and 3.12 tons (max=6.15, min=0.87, SD=1.46) for
females (Table 6). In males, the average body length and the average body weight were largest at thesecond period of the survey. In females, the averages were the lowest at the third period.
Composition of sex and sexual maturity of minke whales collected is listed in Table 7. In males,
eight of 21 animals were sexually mature (38.1%) and nine of 29 females attained sexual maturity(42.0%).

All the mature females were pregnant with 3.65-27.2cm foetuses (Table 8) and lactatingor resting females were not observed.

Prey species of common minke whale found in the stomach contents
Following the same methods used in the JARPN II feasibility surveys (Fujise, et al., 2002), stomach
contents were weighted to the nearest 0.1 Kg, by each of four chamber, in both cases of including
and excluding liquid contents. Then, a small sample of the first stomach contents was collected andfrozen for the laboratory observation. Major prey species found in the first stomach contents wereJapanese sand lance Ammodytes personatus (% in weight = 49.9%) and krill Euphausia pacifica(35.1%; Table 9). The Japanese anchovy Engraulis japonicus collected was only 2.0% in the total
weight. Unidentified fishes (13.0%) were also thought to be sand lances. In the first period, krill was
dominant species found from the first stomach.

However, the occurrence frequency of krill

reduced with time and, in the third period, sand lances were found most frequently. The range of
weights of the first stomach contents was from 1.3kg to 102.6kg. The maximum weight (102.6kg),
which was sand lances, was found from a male with body weight of 5040kg. The weight of stomach
contents was 2.0% of his body weight.

By-products of the whales
After biological examination, all the animals were processed according to the International
Convention for Regulation of Whaling, Article VIII. Total weight of productions including meat andblubber was 77.7 tons.

DISCUSSION
The present survey was the second survey of the JARPNII coastal component conducted in coastal
5

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

waters of Japan, using the small-type whaling catcher boats as the sampling research vessel. In the
research area, there were many fishing boats operating coastal fisheries such as the stick-held dip
netting for sand lances. Many set nets were also placed. The sampling vessels, however, could go
into the inshore areas and take samples beside the fishing boats and nets without any problems andaccidents. The prey species survey and the dedicated sighting survey were also conducted, following
the predetermined schedules and survey lines.
The dominant prey species of common minke whales found in the present survey was very different
from species obtained by the JARPN II offshore surveys (Tamura et al. 2004) and the coastal survey
off Kushiro, 2002 (Kishiro et al. 2003). The sand lance, which was dominant prey species in whale
stomachs taken in the present survey, was not collected by the other JARPN II surveys, in which thewalleye Pollock, the Japanese anchovy, the Pacific saury, and the Japanese common squid were
dominant. This result indicates that many sand lances are distributed in coastal waters off theSanriku of Japan. Indeed, the prey species survey found many sand lances in the waters (see,appendix 1) and the sand lance is one of the most important target species of coastal fisheries in thisarea. The present survey revealed that common minke whales feed many sand lances and krills in the
coastal waters on their northward way to feeding grounds. Our results imply the existence ofcompetition between minke whales and coastal fisheries in waters off the Sanriku.
The present survey was finished with no serious problem and accident. Unfortunately, a small
number of common minke whale sightings was recorded at the dedicated sighting survey, probably
from low coverage of survey lines in high density area, i.e., in the middle part of Sendai Bay. Fromthe viewpoint of the logistic feasibility, however, we concluded that the 2003 coastal survey off theSanriku coast was also conducted successfully, as the last year survey off Kushiro.

ACKNOWLEDGMENTS
We acknowledge Dr. Hiroshi Hatanaka, the project leader of the full-scale JARPN II surveys,(ICR), Dr. Seiji Ohsumi (ICR), and Mr. Joji Morishita, the Fisheries Agency of Japan, for theirguidance and implementation to the research. Crewmen of research vessels, staffs of the researchstation in Ayukawa, and the Japan small-type whaling association helped us. We also thank all themembers of the Oshika Town office, the Oshika fisheries cooperative association, and Miyagi
prefectural office for their kind assistance.

REFERENCES
Fisheries Agency of Japan, 2002. Assessments for the coastal fisheries stocks in the waters off Japan(Assessments by species and stocks). The coastal division of the Fisheries Agency of Japan andthe Fisheries Research Agency, September 2002, 927pp. (in Japanese).
Fujise, Y., Tamura, T., Bando, T., Watanabe, H., Kiwada, H., Otani, S., Kanda, N., Yasunaga, G.,
Mogoe, T., Konishi, K., Inamori, M., Shigemune, H. and Tohyama, D. 2002. Cruise report of the6

SC/56/O14

feasibility study of the Japanese Whale Research Program under Special Permit in the western
North Pacific-Phase II (JARPN II) in 2001. Paper SC/54/O16 submitted to the 54th IWC ScientificCommittee, 51pp.
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 Committee, 68pp.
Government of Japan, 2002a. 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.
Government of Japan (Fujise, Y., Kawahara, S., Pastene, L.A. and Hatanaka, H. eds.), 2002b. Reportof 2000 and 2001 feasibility study of the Japanese Whale Research Program under Special Permit
in the western North Pacific-Phase II (JARPN II). Paper SC/54/O17 submitted to the 54th IWC
Scientific Committee, 202pp.
Hatanaka, H. and Miyashita, T. 1997. On the feeding migration of the Okhotsk Sea-West Pacific
Stock of minke whales, estimates based on length composition data. Rep.int. Whal. Commn
47:557-564.
Kato, H. 1992. Body length, reproduction and stock separation of minke whales off northern Japan.
Rep.int. Whal. Commn 42:443-453.
Kishiro, T., Kato, H., Ohizumi, H., Yoshida, H., Saito, T., Isoda, T., Tabata, S., Sakakibara, M., Saino,
S., Hara., T., Hayashi, T., Miyashita, T., Fukudome, K., Kiwada, H., and Kawahara, S. 2003.
Report of the 2002 JARPN II survey in the western North Pacific. Part II: Coastal component Coastal Survey off Kushiro, northeast Japan. Paper SC/55/O8 submitted to the 55th IWC ScientificCommittee, 26pp.
Miyashita, T. and Hatanaka, H. 1997. A note on whaling grounds for the western North Pacificminke whale. Rep.int. Whal. Commn 47:539-542.
Tamura, T. and Fujise, Y. 2002. Geographical and seasonal changes of the prey species on minke
whale in the Northwestern Pacific. ICES Journal of Marine Science, 59:516-528.
Tamura, T., Fujise, Y., Bando, T., Yasunaga, G., Konishi, K., Kiwada, H., Itoh, S., Machida, S.,
Tsunekawa, M., Konagai, T., Takamatsu, T., Ohshima, T., Isoda, T., Honjo, K., Matsuoka, T.,
Zharikov, K. A., Yong Rock AN., Tohyama, D., and Kawahara, S. 2004. Cruise report of theJapanese Whale Research Program under Special Permit in the western North Pacific - Phase II(JARPN II) in 2003 (part I) - Offshore component. Paper SC/56/O13 submitted to the 56th IWC
Scientific Committee.

7

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Sanriku

Sendai ◙◙Ayukawa
30 n.miles
50 n.miles

HonshuNorth Pacific◙TokyoFig. 1. Research area of the 2003 coastal surveys in the JARPN II.

8

b)
c)

survey.

9

Fig. 2. Cruise tracks (a), and sighting positions (b) and catch positions (c) of common minke whales made by sampling vessels during the 2003 coastala)SC/56/O14

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Table 1. Searching days, hours, distances made by four sampling vessels in the 2003 coastal whale
survey off Sanriku, in the JARPN II.
Sampling vessels*1
Period
28T
75K
7K
31S
Total
First period
Days
6
6
6
6
24
(10 Apr.-16 Apr.)
Hours
42.1
34.6
44.7
40.1
161.5
Distances (n. miles)
465.2
385.4
497.9
433.8
1782.3
Second period
Days
4
4
4
4
16
(17 Apr.-23 Apr.)
Hours
19.3
19.6
16.4
21.0
76.2
Distances (n. miles)
214.4
224.4
190.9
234.2
863.9
Third period
Days
6
5
5
6
22
(24 Apr.-2 May)
Hours
27.8
22.7
23.8
31.0
105.2
Distances (n. miles)
311.8
262.5
266.2
346.9
1187.4
Total
Days
16
15
15
16
62
Hours
89.1
76.8
84.9
92.1
342.9
Distances (n. miles)
991.4
872.3
955.0
1014.93833.6*1: 28T; Taisho Maru No. 28; 75K: Koei maru No. 75; 7K: Katsu Maru No. 7; 31S: Sumitomo maru No. 31.

Table 2. Cetacean species and number of sightings made by the four sampling vesels in the 2003
coastal whale survey off Sanriku, in the JARPN II.
SpeciesPrimary*
Secondary*
Total*
Period
Sch.
Ind.
Sch.
Ind.
Sch. Ind.
Common minke whale
64
66
13
13
77
79
First period
Like minke whale
9
9
1
1
10
10
(10 Apr.-16 Apr.)
Unidentified cetacean1111Common minke whale
42
44
5
5
47
49
Second Period
Like minke whale
666
6(17 Apr.-23 Apr.)
Common minke whale
51
51
9
9
60
60
Third period
Like mnke whale
777
7(24 Apr.-2 May)
Common minke whale
157
161
27
27
184
188
Total
Like minke whale
22
22
1
1
23
23
Unidentified cetacean11
11*: These figures probably include some duplicated sightings made by plural vessels.

Table 3. Density index of common minke whales in the 2003 coastal whale survey off Sanriku, in
the JARPN II.
Primary
Searching
Distance
SPUE*1
PeriodDI*2sightings
Sch.
Ind.
hours
(n. mile)
10 Apr.-16 Apr.
64
66
161.5
1782.30.40
3.59
17 Apr. -23 Apr.
42
44
76.2
863.9
0.55
4.86
24 Apr. -2 May
55
56
105.2
1187.4
0.52
4.63
Total
161
166
342.9
3833.60.47
4.20*1: No. of primary school sightings per 1 hour searching.
*2; No of primary school sightings sighted per 100 n.miles searching.

10

SC/56/O14

Table 4. Sumarry of biological data and samples collected during the 2003 coastal whale survey
off Sanriku, in the JARPN II.
Number of whales
Samples and data
Male
Female Total
Body length and sex
212950
External body proportion
21
29
50
Photographic record and external character
21
29
50
Diatom film record and sampling
21
29
50
Body scar record
21
29
50
Measurements of blubber thickness (eleven points)
21
29
50
Body weight
21
29
50
Body weight by parts
1
1
Skin tissues for DNA study
21
2950
Muscle, liver, and heart tissues for isozyme analysis
21
29
50
Muscle, liver, kidney, and blubber tissues for chemical analysis
21
29
50
Muscle, liver, blubber, vertebrae, and stomach contents for lipid analysis
11
Mammary grand; lactation status, measurement and histological sample
29
29
Uterine horn; measurements and endometrium sample
28
28Collection of Ovary28
28
Photographic record of foetus
8
Foetal length and weight8
External measurement of foetus
8Collection of foetus
9
Testis and epididymis; weight and histological sample
21
21
Stomach contents, convenient record
212950
Volume and weight of stomach content in each compartment
21
28
49
Marine debris in stomach
21
29
50
Stomach contents for feeding study
21
28
49
Record of external parasites
21
29
50
Sampling of the intestine contents
3
7
10
Earplug age determination
21
29
50
Tympanic bulla for age determination
21
29
50
Largest baleen plate for morphologic study and age determination
21
29
50
Baleen plate measurements (length and breadth)212849
Photographic record of baleen plate series
21
29
50
Length of each baleen series
21
29
50
Vertebral epiphyses sample
21
29
50
Number of vertebrae
2129
50
Number of ribs
21
29
50
Skull measurement (length and breadth)
20
28
48

11

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Table 5. Body length (m) of common minke whales collected by the 2003 coastal whale survey in
the JARPN II.
PeriodMale
FemaleMean S.D. Min. Max.
n
Mean
S.D. Min.
Max.
10 Apr. -16 Apr.
6.10 0.47 5.76
6.92
5
6.52
0.99 5.05
7.96
17 Apr. -23 Apr.
6.38 1.07 4.94
7.83
7
6.51
1.31 4.58
8.02
24 Apr. -2 May
6.30 0.99 4.70
7.35
9
5.50
0.98 4.28
6.87
Total
6.28 0.89 4.70
7.83
21
6.30
1.12 4.28
8.02

n
15
8
6
29

Table 6. Body weight (t) of common minke whales sampled by the 2003 coastal whale survey in
the JARPN II.
PeriodMale
FemaleMean S.D. Min. Max. n
Mean
S.D.
Min.
Max.
10 Apr. -16 Apr.
2.77 0.85 2.08
4.22
5
3.38
1.42
1.54
6.15
17 Apr. -23 Apr.
3.02 1.36 1.45
5.06
7
3.46
1.61
1.29
5.50
24 Apr. -2 May
2.92 1.07 1.32
4.15
9
2.01
0.86
0.87
3.31
Total
2.92 1.08 1.32
5.06 21
3.12
1.46
0.87
6.15

n
15
8
6
29

Table 7. Composition of sex and sexual maturity of common minke whales sampled by the 2003 coastal whale survey in the JARPN II.
Period

Male
Imm.

Mat.

Total

10 Apr. -16 Apr.

4

1

5

17 Apr. -23 Apr.

4

3

7

24 Apr. -2 May

5

4

9

Total

13

8

21

FemaleMaturityPregnancy

MaturitySex ratio

(%)*2

(%)

(%Males)

15

100.0

33.3

25.0

8

100.0

50.0

46.7

0.0

0.0

60.0

100.0

31.0

42.0

Imm.*1

Mat.

Preg.

Total

20.0

10

5

5

42.9

4

4

4

44.4

6

0

0

6

38.1

20

9

9

29

(%)

*1: Include an individual estimated from body length (6.09m) due to lack of the ovary sample.
*2: Apparent pregnancy rate.

12

SC/56/O14

Table 8. Pregnant females and their foetus sampled by the 2003 coastal whale survey in the
JARPN II.
Pregnant Female
FoetusSample No.
Catch date
Body length
Body weight
Body length
Body weight
(m)
(t)
(cm)
(g)
03NPCM001
11 April
7.84
4.31
3.65
03NPCM005
11 April
7.68
4.89
20.9
141.2
03NPCM010
14 April
7.96
6.15
10.5
23.8
03NPCM013
15 April
7.26
4.35
27.2
30.0
03NPCM020
16 April
7.65
5.46
7.9
14.1
03NPCM027
18 April
7.45
4.70
12.1
35.1
03NPCM031
19 April
7.66
4.85
11.8
71.7
03NPCM034
22 April
8.02
5.50
8.8
16.7
03NPCM035
22 April
7.14
4.24
14.0
46.4

Table 9. Stomach contents (% in weight) of common minke whales sampled by the 2003
coastal survey in the JARPN II (first stomach).
SamplePrey species (%)
PeriodSize
Sand lance
Krill
Japanese
Unidentified
anchovyfish
10 Apr. -16 Apr.
20
20.3
74.8
0.05
0.0
17 Apr. -23 Apr.
15
56.0
8.3
0.0
35.7
24 Apr. -2 May
14*
92.2
7.7
0.001
0.0
Total
49*
49.9
35.1
2.0
13.0
* An animal with broken stomach by harpoon is unlisted.

13

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

14

SC/56/O14

Appendix 1

2003 prey species survey (coastal coponent) of JARPN IISHIGEYUKI KAWAHARA1, HIKARU WATANABE1, MORIO ICHIHARA2, YO SUENAGA3 AND
MAKI KATAOKA3
1
2

National Research Institute of Far Seas Fisheries, 5-7-1, Shimizu-orido, Shizuoka, 424-8633, Japan
Field Center for Northern Biophere, Hokkaido University 3-1-1 Minato-cho Hakodata Hokkaido
041-8611 Japan

3

Nippon Kaiyo Co., Ltd., Tokyo Branch Office, 9-2 Sakae-cho, Kita-ku Tokyo, 101-0041, Japan

ABSTRACTA prey species survey was conducted concurrently with the sampling survey for minke whale bysmall-type whaling catcher boats in April 2003 as a part of coastal component of 2003 JARPN II. The
primary objective of cooperative study was to estimate the prey preference of minke whale. While thewhale sampling survey was conducted in the coastal waters within the 30 nautical miles (max 50 nautical
miles) from Ayukawa, Miyagi prefecture, the prey species survey was conducted in wider area off Pacificside of the northern Honshu, Japan to cover the distribution of main prey species. The area was divided
into inshore and offshore areas and zigzag track lines were set to cover the areas. The distribution andabundance of the prey species were investigated with the quantitative echosounder (EK60) on board astern trawler-type research vessel, Kaiyo maru No. 7 (499.0 GT) steaming at about 10 knots along the
track lines during daytime. Acoustic data were acquired with operating frequency at 38 and 120 kHz.
Species compositions of acoustical backscatterings were identified by midwater trawl, IKMT and Bongo
nets. In addition, trawl operations were made at predetermined stations. In the acoustic survey, Japanese
anchovy and krill were found in the southern inshore area. Krill and adult sand lance were found in
Sendai Bay where sampling survey for minke whales was concentrated. Sand lance was confined to thehard sea bottom. The area with hard sea bottom is limited to the southern part of Sendai Bay at depths of
30-100 m where many fishing vessels targeting to adult sand lance were operated. Only relatively strong
echoes from plankton were observed in the northern inshore area. In the offshore area, weak echoes were
found in the southern and northern parts, due to the strong effect of Kuroshio and Oyashio currents,
respectively.

INTRODUCTION
The overall goal of JARPN II is to contribute to the conservation and sustainable use of marine
living resources including whales in the western North Pacific, especially within Japan’s EEZ(Government of Japan, 2002. The priority is put on feeding ecology and ecosystem studies,
involving studies of prey consumption by cetaceans, prey preferences of cetaceans and ecosystemmodeling. As it is difficult to cover the coastal area, especially in spring and autumn, by the Nisshin
15

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Maru fleet, the full-scale JARPN II has a new coastal component, that is, the sampling survey forminke whale by small-type whaling catcher boats. As in 2002 surveys, a prey species survey was
conducted concurrently with the coastal sampling survey during spring 2003 before the offshore
surveys. In this document, the results of the 2003 prey species survey of the coastal component arepresented.

MATERIALS AND METHOD
While the sampling survey of minke whale was conducted in the coastal waters within the 30
nautical miles (max 50 nautical miles) from Ayukawa, Miyagi prefecture, the prey species survey
was conducted in wider area off the Pacific coast of the northern Honshu, Japan to cover the
distribution of main prey species (Fig. 1). To avoid the conflict with set nets in the coastal waters,
the waters 10 miles from the coastal lines were excluded in principle. The survey area was divided
into two parts; coastal and offshore areas. A zigzag track line was set to cover each area. The preyspecies survey was conducted from April 9 to 28 consisting of two terms; the first from April 9 to 18
and the second from April 18 to 28. The distribution and abundance of the prey species were
investigated with the quantitative echosounder (EK60), midwater trawl, Isaacs-kidd Midwater Trawl(IKMT) and Bongo net on board a stern trawler-type research vessel, Kaiyo maru No. 7 (499.0 GT)
steaming at about 10 knots along the track lines. The survey was conducted during the daytime froman hour after sunrise to an hour before sunset (generally from 6:00 to 17:00). Oceanographic
observations with CTD were conducted just before or after the sampling operation. Sighting survey
was conducted on board Kyoshin Maru No. 2.
Acoustic data were acquired with Echoview Ver.3 (Sonar Data Co., Ltd.) with operating frequency at
38 and 120 kHz of the hull-mounted transducers. Calibrations were carried out off Ishinomaki,
Sendai Bay (April 18 2003) using the copper sphere technique. The mid-water trawl net used had amouth opening of about 30x30m and a 17.5mm liner cod end. The depth and the height of the mouthof the net were recorded with the small-type depth recorders. Towing speed of the trawl net was 3-5
knots. Two types of mid-water trawlings were made. Targeting trawlings were to identify the species
and size compositions of biological backscatterings detected by the echosounder. Samples wereidentified to the species level and weighed aboard the ship. For the major species, a sample of about
100 animals was taken and the lengths were measured to cm below. Some frozen samples were taken
for further analysis in the laboratory. Also, IKMT was used to the biological backscatterings
expected as micronekton and/or zooplankton such as krills on the echosounder. Bong net was also
used to sample zooplankton. Samples were preserved in 10 % formalin for species identification at
the laboratory. Another type of trawlings were made at predetermined stations to estimate theabundance and distribution of cephalopods and neustnic organisms that are difficult to detect withthe echosounder. At predetermined stations the midwater trawl net was towed in a stairs-like fashionat three depth layer; 0-30m (surface) 30-60m and 60-90m. Towing duration was 30 minutes in total,
16

SC/56/O14

10 minutes for each layer. Samples taken were processed as in the targeting trawlings.

Acoustic data are being analysed at the laboratory. The analysed depth range was from the surface to200m. Data collected at 38 kHz and 120 kHz were used mainly for fishes and krills, respectively. In
principle, backscatterings on the echosounder were identified based mainly on the results of trawl
and IKMT samplings. The school shape and backscattering intensity were also used for species
identification. Backscatterings were identified as krills if ∆Sv (the difference of Sv between 38 and
120 kHz) falls between 10 and 15 dB (Miyashita et al. 1997). The integration was made at aninterval of one nautical mile by 50 m depth zone.

RESULTS
The planned track lines were almost covered in the acoustic survey. A summary of the midwater
trawl, IKMT and Bongo net operations was shown on Table 1. The positions of midwater trawl,
IKMT and Bong net operations were shown in Fig. 2. Targeting trawlings and IKMT were made 6
and 17 times, respectively. The midwater trawl operations were made at 14 predetermined stations.
At the two stations among them, midwater trawl operations were made at night. Bong net operations
were made 4 times.

While the vast acoustical data are being analyzing now, the preliminary results

are as follows.
Large-sized Japanese anchovy were found at depths shallower than 30m in the southern inshore area
except for the Kuroshio Extension area (Fig. 3). Also krill were widely distributed in shoals in thesouthern inshore area (Fig. 3). In Sendai Bay, where most of the sampling survey for minke whales
was conducted, the echoes of krill were detected widely, and the echoes assumed as adult sand lance
were found at the surface layer and on the bottom of the sea (Fig. 4). By the targeting trawls, theschools on the hard bottom were identified as adult sand lance. The area with hard bottom is limited
to the southern part of Sendai Bay at depths of 30-100 m where many fishing vessels targeting toadult sand lance were operated. Only relatively strong echoes from plankton were observed in thenorthern inshore area. In the offshore area, weak echoes were found in the southern and northernparts, due to the strong effect of Kuroshio and Oyashio currents, respectively. The prey preference ofminke whale will be analyzed comprehensively based on the distribution and abundance of preyfrom the prey species survey and the diet composition from the whale sampling survey.

REFERENCES
Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacific underSpecial Permit (JARPN II). IWC/SC/54/O2: 115pp.
Miyashita, K., Aoki, I., Seno, K., Taki, K. and Ogishima. 1997. Acoustic identification of isada krill,
Euphausia pacifica Hansen, off the Sanriku coast, north-eastern Japan. Fish. Oceanogr. 6.
266-271.
17

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Murase, H., Tamura, T., Kiwada, H., Fujise, Y., Watanabe, H., Ohizumi, H. and Kawahara, S. 2002.
Preliminary estimation of prey preference of minke and Bryde’s whales based on JARPN II.
Appendix 5, pp 97-117. In: Fujise, Y., Kawahara, S., Pastene, L. A. and Hatanaka, H. 2002.
Report of 2000 and 2001 feasibility study of the Japanese whale research program under
special permit in the western North Pacific – phase II. Paper SC/54/O17 submitted to the54th IWC Scientific Committee Meeting, 202 pp.

18

SC/56/O14

Fig. 1. The survey area and tracklines for 2003 prey species survey(coastal component).

Fig. 2. Positions of midwater
trawl, IKMT and Bong net
operations.

19Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

38kH

120kH

Fig. 3. Japanese anchovy (left) and krill (right) on the echo diagram in the southern inshore area.

38kH

40m

Fig. 4. Sand lance (left) and anchovy (right) on the echo diagram in Sendai Bay.

20

SC/56/O14

Appendix 2

Oceanographic conditions in the Kuroshio-Oyashio Inter-frontal zone
in April 2003
Denzo Inagake*, Shigeyuki Kawahara*, Hikaru Watanabe*, Morio Ichihara**, Yo Suenaga***,Maki Kataoka*** and Hiroto Murase*****National Research Institute of Far Seas Fisheries**Field Center for Northern Biophere, Hokkaido University***Nippon Kaiyo Co., Ltd****Institute of Cetacean Research

1. Introduction
The oceanographic condition at the Tohoku area east of Japan is the most complicated area in theworld.

There are both of subtropical water (the Kuroshio water) and subarctic water (the Oyashio

water), and also, both water masses are mixed each other and form new water masses in the
Kuroshio-Oyashio Inter-frontal Zone.

Each water mass has its own ecosystem, like a Kuroshio

ecosystem, an Oyashio ecosystem, warm-core ring ecosystem, etc.

So, we must make clear theoceanographic condition around whale’s prey to build up a marine ecosystem model in the Tohoku
area.
In this paper, we analyzed the CTD data, which were observed by Dai 7 Kaiyo Maru cruise in the
JARPNII (Japan's whale Research Program in the Western North Pacific) to make clear the oceanic
environment in the research area.

2. Data and Methods
Hydrographic observations with a conductivity-temperature-depth profiler (CTD; SBE 19plus
SEACAT Profiler) were carried out from 10th to 24th April 2003 in the Kuroshio-Oyashio
Inter-frontal Zone using Dai 7 Kaiyo Maru, chartered by the Institute of Cetacean Research (Fig. 1).
The oceanographic conditions in April 2003 were analyzed by Tohoku National Fisheries
Research Institute (TNFRI), which used quasi-real-time data from several cooperative organizations
and prefectures, that was Fisheries Research Agency, Meteorological Agency, Hydrographic
Department and Fisheries Experiment Stations, etc.

TNFRI published temperature maps andschematic hydrographic maps using World Wide Web (http://www.myg.affrc.go.jp/index-j.html).
Oceanic fronts and water masses are usually detected by subsurface temperature map (sea Table 1),
because they are obscure in sea surface temperature distributions in summer seasons and the Oyashio
water spreads into the subsurface layer.

3. Oceanographic conditions in the research area
21

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Figure 2 shows the Temperature-Salinity diagrams using CTD station data.

Water masses in

the research area have characteristics of cold low-salinity water (the Oyashio water in the lower partof Fig. 2), warm high-salinity water (Kuroshio water in the right part of Fig.2) and the mixed waterof the Kuroshio water and Oyashio water.

In this figure, the Oyashio water (blue points in Fig. 2)

was the most dominant although the Kuroshio water (red points in Fig. 2) was observed only one
station.
Figure 3 shows the schematic hydrographic map in April 2003, presented by TNFRI.

The

northern limit of the Kuroshio Extension at the first crest was around 36°N (lower red area in Fig. 3),
which is nearby 1σ south of the mean location.

The northern limit of the warm water spread fromthe Kuroshio Extension shifts northward from March to November.
at 41°10’N on 147°E line.

This northward speeding is developed well caused by the Kuroshio

warm-core ring that is detected around 40°N, 145°30’E.
142°50’E.

Its position in April 2003 was

Tsugaru warm water spread eastward to

The southern limit of the first Oyashio Intrusion was located 37°30’N on 142°30’E line,

which were more southern position from monthly mean location.

The southern limit of the second

Oyashio Intrusion was around 39°N, 147°E which was a little northern position from the mean
position.

In July, it was obscure in Fig 3 but maybe existed around 39°30’N, 146°30’E, where wasin a slightly south from the mean.
Figure 4 shows the 100 m depth temperature map observed by Dai 7 kaiyo Maru. The
Kuroshio Extension, which defined by 14°C at the depth of 200 m, was observed in the southernedge of Fig. 4.

The Oyashio water colder than 5°C at the depth of 100 m was spreading in thenorthern part of the observation area. The warm water spreading from the Kuroshio area wasobserved at a few stations in the southern part of this area.

The cold water was observed at few

stations between the Oyashio water and the warm water spreading from the Kuroshio area.
Figure 5 shows the vertical temperature and salinity sections along approximately 141°E, 142°E
and 143°E, which were zigzag lines.

The warm water spread from the Kuroshio Extension was

limited in the southern part of the 141°E and 143°E section although cold Oyashio water observed in
the almost whole area, north of the warm water (north of 37°N). There was a sharp temperature
front around 5°C to 10°C isotherms.

10°C isotherm is coincident with 34psu isohaline in eachsalinity section along 141°E and 143°E.
Front)In the North Pacific Ocean, 4°C isotherm (Subarctic

is the southern limit of the Subarctic water, and 34psu (Subtropical Boundary) isohaline

indicates the north limit of the Subtropical water (Table 1).

These fronts lie closely between

subarctic water and Subtropical water in the research area but these fronts separate each other in thehigh sea of the North Pacific (see Shunyo Maru cruise report).
REFERENCES
Favorite, F., A. J. Dodimead and K.Nasu (1976): Oceanography of the Subarctic Pacific Region,
1960-71. Bull. 33, International North Pacific Fisheries Commission, 187 pp.
Kawai, H. (1969):

Statistical estimation of isotherms indicative of the Kuroshio axis, Deep-Sea

Res., 16, 109-115.
22

SC/56/O14

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).

Table 1. Extraction method from temperature map to determine the position ofeach water mass.
Target characteristics
Kuroshio Extension Axis
Warm-core ring
Oyashio front
Oyashio water
Cold water
Warm water

Extraction method
14°C isotherm at 200m (Kawai, 1969)
Temperature front at 200m
5°C isotherm at 100m
Area with T<5°C at 100m
Area with 5°C<T<10°C at 100m
Area with T>10°C at 100m and T<14°C at 200m

Tsugaru warm current

Temperature front at 100m near the Tsugaru Strait

Subarctic Boundary

Salinity front defined by 34.0psu

Subarctic Front

Temperature front defined by 4°C

23Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Fig. 1.

Station map observed by DAI 7 KAIYO Maru in 10 – 27 April 2003.

Green triangles, light

blue stars and blue circles denote CTD stations in the warm area (100 m temperature wasover 10°C and 200 m temperature was less than 14°C), the cold area (100 m temperature
was over 5°C and less than 10°C) and the Oyashio area (100 m temperature was less than
5°C), respectively

24

SC/56/O14

Fig. 2.

Temperature-Salinity diagrams using CTD station data observe by DAI 7 KAIYO Maru in
10 – 27 April 2003.

Each thin line in this figure denotes a density line of sigma-t.

Red,green, light blue and blue points corresponded to the Kuroshio area, warm area, the cold
area and the Oyashio area, respectively.

25

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Fig. 3.

Schematic hydrographic map in Tohoku area, northwestern Pacific, in 2002. (Presented by
Tohoku National Research Institute.)Blue area, green area, yellow area and red area

denote the Oyashio (100 m temperature was less than 5°C), cold area (100 m temperature
was over 5°C and less than 10°C), warm water (100 m temperature was over 10°C and
200 m temperature was less than 14°C) spreading from the Kuroshio Extension and theKuroshio area (200 m temperature was over 14°C), respectively. Red diamond, green
triangles, light blue stars and blue circles denote CTD stations observed by DAI 7 KAIYO
Maru in the Kuroshio area, warm area, cold area and the Oyashio area, respectively

26

SC/56/O14

Fig.4.

100m temperature (upper left panel) and 200m temperature (lower panel) maps observed by
DAI 7 KAIYO Maru in 10 – 27 April 2003.

27

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

Fig. 5.

Temperature (upper panels) and salinity (lower panels) along approximately 141°E(leftpanels), 142°E (middle panels)

and 143°E (right panels) observed by DAI 7 KAIYO

Maru in 10 – 27 April 2003.

28

SC/56/O14

Appendix 3

Cruise report of the dedicated sighting survey in 2003 JARPNII
coastal survey off Sanriku, northeast JapanSHIGETOSHI NISHIWAKI, AND MASAOMI TSUNEKAWA

Contact e-mail: nisiwaki@cetacean.jp
The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku Tokyo, 104-0055, Japan

ABSTRACT
A cetacean sighting survey using the line transect method was conducted concurrently with the whale sampling
survey and the whale prey survey off the Sanriku coast, Japan from 8 to 28 April. The primary objective of thesighting survey was the abundance estimation of baleen whales in the survey area. Shonan-maru was dedicated to thesighting survey. Total primary searching distance was 1,086.7 n. miles and the 129 schools (534 individuals) ofprimary sightings were made.

INTRODUCITON
A cetacean sighting survey using the line transect method was conducted concurrently with thewhale sampling survey and the whale prey survey off the Sanriku coast, Japan from 8 to 28 April, asa part of coastal component of 2002 JARPN II full scale study (Government of Japan, 2002). The
primary objective of this survey was to obtain information on abundance of baleen whales in thesurvey area. Preliminary results of the cetacean sighting survey are presented in this paper.

MATERIALS AND METHODS
The cetacean sighting survey area was set within Sub-area 7 (Fig. 1). Though the sampling of whales
was conducted within the 30 n. miles from Ayukawa port in the Sanriki, sighting survey area hadlarger are extent to see the overall baleen whale distribution pattern off the coast of the Sanriku. Near
shore area of the survey block where the water depth is less than 50m was not surveyed because
many fisheries gears were set in there. The survey block was further divided into the coastal andoffshore area. Coastal area was divided into three at the two boundary lines, 37ºN and 39ºN.
Offshore area was divided into two at the boundary lines on 38ºN. The survey was conducted from 9
to 28, 2003. Shonan-maru(SM1, 712GT) engaged in the cetacean sighting survey. Sighting survey
procedures were same as offshore component of 2003 JARPN II. The right (Eubalaena japonica),
29

Yoshida, et al.: Report of the 2003 JARPN II-Part II: Coastal component

blue (Balaenoptera musculus), and humpback (Megaptera novaeangliae) whales can be approached
to obtain the Natural marking record experiments as the opportunistic basis. Large baleen whale
feeding behavior visual observation was attempted. If the behavior was observed, it was recorded onvideo tape.

RESULTS AND DISCUSSION
Tracklines surveyed are shown in Fig. 1 (right). Total primary searching distance was 1,086.7
n.miles. The 129 schools (534 individuals) of primary sightings were obtained and one secondarysighting (one animal/one school) was also made. Details of sightings are listed in Table 1. Sightingsof common minke, fin, right, and sperm whales were recorded. Sighting positions of the first three
species are noted in the Fig. 2 (right). Natural marking record experiments were conducted on a rightwhale and two humpback whales. No feeding behavior of large baleen whales was observed.

ACKNOWLEDGEMENT
Special thanks is given to the crews and researchers for their dedication in collecting data. The
authors would like to thank Dr. Hiroshi Hatanaka (The Institute of Cetacean Research). We thank
Koji Matsuoka and Hiroshi Kiwada for the preparation of the cruise. We also express the gratitude to
Hiroto Murase for the comment on the course of preparing the English manuscript of this paper.

REFERENCES
Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacific underSpecial Permit (JARPN II). IWC/SC/54/O2: 115pp.

30

SC/56/O14

Table 1. Summary of cetacean sightings made during the dedicated sighting survey in 2003 JARPNII
coastal survey.

Primary Secondary
SpeciesSch. Ind. Sch. Ind.

Common minke whale

3

3

1

1

Fin whale

1

1

0

0

Humpback whale

1

2

0

0

Right whale

1

1

0

0

Sperm whale

8

35

0

0

Unidentified large whale

1

1

0

0

Unidentified cetaceans

2

2

0

0

Fig. 1. Survey area and predetermined tracklines (left), and surveyed tracklines and sighting
positions of common minke (open circle), fin (open triangle), right (double circle) and humpback(open square) whales (right), during the dedicated sighting survey in 2003 JARPNII coastal survey.

31