SC/61/O6

Cruise Report of the Second Phase of the Japanese
Whale Research Program under Special Permit in theWestern North Pacific (JARPN II) in 2008 - (Part II) Coastal component off Sanriku
GENTA YASUNAGA1), HIDEHIRO KATO2), TOSHIYA KISHIRO3), HIDEYOSHI YOSHIDA3), SHIGETOSHI3),NISHIWAKI1), TERUO SAITO1), SHIGEO TABATA1), RYOSUKE OKAMOTO2), HIKARI MAEDA2), GEN
NAKAMURA2), SATOKO INOUE2), SEIJI OTANI1), TOSHIHIDE IWASAKI3), YU KANAJI3), TOSHIHIRO MOGOE1),
HIROTO MURASE1), ATUSHI, WADA1), KAZUYOSHI NAKAI1), AKIRA MATSUMOTO2), AKIHIRO GOKITA2), KEI
YAMAZAKI2), HIROYUKI OIKAWA1), KEIICHI ONODERA4), KAZUNARI SHIRAISHI4) AND HIROSHINAGASHIMA4)

1) The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan.
2) Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108-0075,
Japan3) National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa-ku, Yokohama,
Kanagawa, 236-8648, Japan

4) Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi
986-2135, Japan

Contact e-mail:yasunaga@cetacean.jp
ABSTRACTThe 2008 survey of the JARPN II coastal component off Sanriku (northeastern Japan, corresponding to a part of sub-area7), was conducted from 14 April to 18 May, using four small-type whaling catcher boats and one echo sounder trawl
survey vessel. Sampling of common minke whales was conducted in coastal waters within 50n. miles from Ayukawa
port in the Sanriku district, and all animals collected were landed on the JARPN II research station established forbiological examination. A total of 5,275.9n.miles (482.0 hours) was surveyed and 94 schools (96 individuals) of common
minke whales were sighted. A total of 60 animals were sampled. Average body length of the animals was 5.67m (SD:1.06, n=23) for males and 5.91m (SD: 1.01, n=37) for females. Dominant prey species found in the forestomach were
adult and juvenile of Japanese sand lance (Ammodytes personatus) throughout all survey period. Japanese anchovy(Engraulis japonicus) and krill (Euphausia pacifica) were observed from one individual each, respectively. Juvenile of
the Japanese sand lance in the stomach of minke whales were observed for the first time in Sanriku. This result indicatesthat feeding habit of common minke whales in coastal waters off Sanriku changes year by year.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; COASTAL WATERS OF JAPAN; FOOD/PREY;ECOSYSTEM; SCIENTIFIC PERMITS.

INTRODUCTION
After the two-year feasibility study in 2000-2001, the full-scale survey of the second phase of theJapanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II) wasstarted in 2002. The objectives of the program are to evaluate the feeding ecology and ecosystem studies,
involving prey consumption by cetaceans, prey preferences of cetaceans and ecosystem studies, tomonitor environmental pollutants in cetaceans and the marine ecosystem and to elucidate the stock
structure of whales (Government of Japan, 2002a).
The JARPN (1994-1999) and the JARPN II feasibility studies (2000-2001) revealed that common minke
whales are widely distributed from offshore waters to coastal waters and feed on various prey species
such as Japanese anchovy, Pacific saury, and walleye pollock (Government of Japan, 2002b; Tamura andFujise, 2002). The coastal waters of Japan are also very important fishing ground. Thus, it was thoughtthat the coastal waters are also very important research area for the full-scale JARPN II program.
However, the Nisshin Maru research vessels can not be operated in the near shore areas, because of their
movement restrictions from shallow water depth, and many fishing gears and boats. Furthermore, thevessels can not work from late autumn to early spring because of their practical availability. In order tocover the temporal and spatial gap of the vessels, sampling of common minke whales in the coastal
waters using small-type whaling catcher boats was planned.

1

In the original JARPN II plan, the coastal component was presented as the two-year feasibility study to
examine the logistic aspects of the methodology (Government of Japan, 2002a). First feasibility survey
was carried out in the coastal waters off Kushiro in autumn 2002 (Kishiro et al., 2003) and then thesecond feasibility survey was conducted in the coastal waters off Sanriku district in spring 2003 (Yoshida,
et al., 2004). In each of the surveys, 50 common minke whales were caught. From detailed examinationof logistic aspects in the surveys, it was concluded that no substantial problem occurred and that thecoastal survey could be continued as a component of the JARPN II using same kind of vessels (smalltype whaling catcher boats) and methodology (Government of Japan, 2004a, Kato, et al., 2004). However,re-calculation of required sample size from the survey data suggested that the size should be modified to
be at least 60 individuals in each area/season (Tamura, et al., 2004), and from the possible geographicaland/or temporal variations of prey consumption of the whales, the coastal surveys thought to be neededon a yearly bases in each local area (Government of Japan, 2004b). The revised survey off Sanriku wascarried out in spring 2005 (Yoshida et al., 2006), 2006 (Goto et al., 2007) and 2007 (Bando et al., 2008).
In the present paper, we show results of the fourth survey carried out in coastal waters off the Sanriku
district, Japan, from 14 April to 18 May in 2008. This survey was authorized by the Government of Japanin compliance with Article VIII of the International Convention for the Regulation of Whaling. The
Institute of Cetacean Research (ICR) planned and conducted the survey cooperated with National
Research Institute of Far Seas Fisheries, Tokyo University of Marine Science and Technology and
Miyagi Prefecture Fisheries Technology Institute.

MATERIALS AND METHODS
Research area
Research area was set in the same waters where the previous JARPN II coastal surveys off the Sanriku
district were conducted (Yoshida et. al, 2004; 2006; Goto et al., 2007; Bando et al., 2008). The district
occupies northeastern part of the Japanese main island, Honshu (see, Fig. 1). In coastal waters off theSanriku district, common minke whales were taken by the past land-based coastal whaling (Miyashita andHatanaka, 1997). The waters have been also very important fishing grounds. So, the waters wereconsidered to be suitable for the research area of the JARPN II, and thus the coastal surveys wereconducted in this area. The present research area was also set in the same waters: within 50 nautical miles(mainly 30 n. miles) from the Ayukawa port in the Sanriku district (Fig. 1). The survey area is included in
the middle part of the sub-area 7 established by the IWC (1994).
Research vessels and station
Whale sampling survey
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No. 28 (hereinafterreferred as 28T; 47.3GT), Koei Maru No. 75 (75K; 46.0GT), Katsu Maru No.7 (7K; 32.0GT), andSumitomo Maru No.31 (31S; 32.0GT). The whale sampling survey was conducted in a period from 14
April to 18 May, 2008. All the animals sampled were landed on the JARPN II research station establishedby the Ayukawa port for biological examination.
Prey species survey
The Takuyo Maru (TAK, 120.0GT), the trawler-type research vessel, conducted the prey species survey
in research area set off northeast coast of Honshu from 9 to 25 April. The distribution and abundance ofthe prey species were investigated with the quantitative echo sounder (EK 500 and ER 60) on board TAK.
Acoustic data were acquired with operating frequency at 38, 120 and 200 kHz. Species/size compositionsof echo signs were identified by targeting mid-water trawling. Detail of the prey species surveys areshown in Appendix 1.
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. These items are related to studies on
feeding ecology, stock structure, life history and pollutions.

RESULTS
Searching effort made by sampling vessels
Cruise tracks made by sampling vessels (28T, 75K, 7K and 31S) during the present survey are shown in
Fig. 2. The sampling vessels tried to cover research areas widely within 30 n. miles from Ayukawa port.
In offshore waters, however, searching activity was low because of changeable weather condition andbigger waves for small sampling vessels. Consequently, searching effort was concentrated in Sendai Bay.
Searching distance and time made by four sampling vessels are listed in Table 1. Here, searching distance2and time are defined as distance and time recorded under searching activity conducted from top barrel ofvessels. Total searching distance and time made by the four vessels were 5275.9 n. miles and 482.0 hours,
respectively (Table 1).
Common minke whale sightings made by sampling vessels
Sighting positions of common minke whale schools made by the sampling vessels are shown in Fig. 3.
All of common minke whale sightings were recorded in middle part of Sendai Bay. As shown in Table 2,a total of 94 schools (96 individuals) of common minke whales were sighted. These were 83 primarysightings (85 animals) and 11 secondary sightings (11 animals). Of 94 schools sighted, only 2 schools
consisted of 2 individuals and others were solitary animals. Cow-calf pairs were not sighted.
Table 3 shows density index (SPUE: number of primary school sightings per one hour searching; DI:
number of primary school sightings per 100 n. miles searching) of common minke whales recorded by the
sampling vessels. Both SPUE and DI are highest during the first period through the research period.
Sampling of common minke whales
A total of 60 common minke whales were taken for biological examination. In the sampling process, one
common minke whale was struck and lost. Sighting positions of sampled individuals are shown in Fig. 3.
Sex ratio, body length and weight of animals caught
Research items of biological examination are summarized in Table 4, with number of data and samples
obtained. The collected 60 animals consisted of 23 males and 37 females. Sex ratio of males to all
animals was 0.38.
Average body length was 5.67m (max=7.78, min=4.07, SD: 1.06) for males and 5.91m (max=8.12,
min=4.13, SD=1.01) for females, respectively (Table 5). Frequency of body length of common minke
whale by sex was shown in Fig. 4. Average body lengths of both male and female in the second period
were higher than those in the first and third periods.
Composition of sexual maturity of animals collected is listed in Table 6. In males, 4 of 23 animals were
sexually mature (17.0%), and 7 of 37 females attained sexual maturity (22.2%). Six from seven mature
females were pregnant and one female was pregnant and lactating simultaneously.
Prey species of common minke whale found from forestomach
Following the same methods used in the JARPN II feasibility survey conducted in 2001 (Fujise, et al.,2002), stomach contents were weighted to the nearest 0.1 kg, by each of four chamber, in both cases ofincluding and excluding liquid contents. Then, small sample of forestomach contents was collected andfrozen for laboratory analysis.
Forestomach contents found from common minke whales during the present survey are listed in Table 7.
Dominant prey species were adult and juvenile Japanese sand lance (Ammodytes personatus) (95.8%, 47
from 49 animals). The adults, juveniles and mix of them were observed in 32, 11 and 4 animals,
respectively. Japanese anchovy (Engraulis japonicus) and krill (Euphausia pacifica) were observed ineach one animal in the research period.
The maximum net weight of forestomach contents was 77.4 kg, of which consisted adult of Japanesesand lance (Table 8). This individual was female with body length of 6.19m and body weight of 2.43 tons.
Forestomach contents weight was 3.19 % of her body weight.

DISCUSSION
The present survey was the fifth coastal survey carried out in coastal waters off Sanriku district. During
the survey period, low atmospheric pressure often disturbed the research activities. Furthermore,changeable weather condition and bigger waves obstructed searching activities of sampling vessels in
offshore waters. Nevertheless, almost all of planned sample size was collected in Sendai Bay, wherewater depth is less than 100m.
The minke whales collected in the second period (1-14 May) were distributed in the southern Sendai
Bay, while those in first (14-30 April) and third (15-18 May) period were widely distributed at the centerof the Sendai Bay (Fig. 3). And also, the maturity ratios of minke whales in both sexes collected in thesecond period were comparatively higher than those in first and third periods (Table 6). The results
indicate seasonal change of migration pattern in the minke whales in the Sendai Bay.
Dominant prey species found from forestomach of animals were adult and juvenile of Japanese sandlance throughout survey period (Table 7). Japanese anchovy and krill were observed from only one
individual, respectively.
In the 2003 coastal survey off Sanriku, adult of Japanese sand lance and krill had mainly been observedin the stomach contents of minke whales (Yoshida, et al. 2004). And also, adult of Japanese sand lance
and Japanese anchovy had mainly been observed in the 2005, 2006 and 2007 surveys (Yoshida et al.,3

2006; Goto et al., 2007; Bando et al., 2008). However, either adult or juvenile, or both of them wereobserved in those of almost all minke whales in the present season. Furthermore, juvenile of Japanesesand lance was for the first time observed in JARPN II Coastal component off Sanriku. These indicatethat feeding habit of the minke whales in coastal waters off Sanriku changes year by year.
From the present survey, we could obtain valuable information for feeding ecology of minke whales. To
evaluate more precise values on food consumption of minke whales and to obtain more information oninteraction between the whales and coastal fisheries, continuation of studies are needed.

ACKNOWLEDGMENTS
We acknowledge crewmen of research vessels, staffs of the research station in Ayukawa, and the Japan
small-type whaling association helped us. We also thank all the members of the municipal office ofIshinomaki, the Ojika fisheries cooperative association, and Miyagi prefectures office, for their kindassistance.

REFERENCES

Bando, T., Kato, H., Kishiro, T., Goto, M., Saito, T., Tabata, S., Morita, Y., Okamoto, R., Maeda, H., Inagaki, M.,
Nagatsuka, S., Ebisui, T., Nakai, K., Matsumoto, A., Gokita, A. and Kawahara, S. 2008. Cruise report of thesecond phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific(JARPN II) in 2007- Coastal component off Sanriku. Paper SC/60/O6 submitted to the 60th IWC scientificCommittee, 27pp.
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 the feasibility study of theJapanese 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 Scientific Committee, 51pp.
Goto, M., Kato, H., Zenitani, R., Yoshida, H., Saito, T., Tabata, S., Morita, Y., Sato, H., Okamoto, R., Maeda, H.,
Odagawa, A., Ebisui, T., Nakai, K., Matsumoto, A., Fujimori, S., Nishiwaki, S. and Kawahara, S. 2007. Cruise
report of the second phase of the Japanese Whale Research Program under Special Permit in the Western North
Pacific (JARPN II) in 2006- Coastal component off Sanriku. Paper SC/59/O6 submitted to the 59th IWC scientificCommittee, 34pp.
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. Report of 2000 and2001 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.
Government of Japan (Fujise, Y., Tamura, T., Kato, H. and Kawahara, S. eds.), 2004a. Some considerations of thefeasibility components of the JARPN II research plan. Paper SC/56/O2 submitted to the 56th IWC ScientificCommittee, 36pp.
Government of Japan, 2004b. Revised research plan for cetacean studies in the western North Pacific under
special permit (JARPN II). Paper SC/56/O1 submitted to the 56th IWC Scientific Committee, 14pp.
International Whaling Commission. 1994. Report of the Scientific Committee, Annex G. Report of the Working
Group on North Pacific Minke Whale management trials. Rep. int. Whal. Commn 44:120-44.
Kato, H., Kishiro, T., Yoshida, H. and Kawahara, S. 2004. Feasibility of coastal surveys in the JARPN II, from theviewpoint of logistics. Appendix 1, pp4-12. In: Government of Japan (Fujise, Y., Tamura, T., Kato, H. and
Kawahara, S. eds.), Some considerations of the feasibility components of the JARPN II research plan. Paper
SC/56/O2 submitted to the 56th IWC Scientific Committee, 36pp.
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 Scientific Committee, 26pp.
Miyashita, T. and Hatanaka, H. 1997. A note on whaling grounds for the western North Pacific minke 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., Hakamada, T., Konishi, K., Fujise, Y., Kishiro, T., Yoshida, H., Ohizumi, H. and Kato, H. 2004.
Recalculation of sample size of common minke whales in coastal areas required for estimating consumption ofvarious prey items based on results of JARPN II. Appendix 2, pp13-17. In: Government of Japan (Fujise, Y.,
Tamura, T., Kato, H. and Kawahara, S. eds.), Some considerations of the feasibility components of the JARPN II
research plan. Paper SC/56/O2 submitted to the 56th IWC Scientific Committee, 36pp. Paper SC/56/O16
submitted to the 56th IWC Scientific Committee, 36pp.
Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Ryono, T., Tabata, S., Sakakibara, M., Saino, S.,
Hara, T., Hayashi, T., Tomizawa, Y., Tamai, K., Okamoto, R., Fukuoka, M., Watanabe, H., Tsunekawa, M. and
Kawahara, S. 2004. Report of the coastal survey on common minke whales off Sanriku coast, northeast Japan:
the Japanese whale research program under special permit in the western North Pacific – Phase II (JARPN II)
in 2003 (Part II) – Coastal component. Paper SC/56/O14 submitted to the 56th IWC Scientific Committee, 31pp.
Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Saito, T., Tabata, S., Morita, Y., Sato, H., Okada, A.,
Tomizawa, Y., Saino, S., Kuroishi, H., Ebisui, T., Nakai, K., Nishiwaki, S. and Kawahara, S. 2006. Cruise reportof the second phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific(JARPN II) in 2005- Coastal component off Sanriku. Paper SC/58/O9 submitted to the 58th IWC scientificCommittee, 30pp.

4

Table 1. Searching days, hours, distances by four sampling vessels in the 2008 JARPN II coastal
surveys off Sanriku.
Sampling vessels*

Period

75K
11
75.9
818.5

07K
11
73.1
772.3

31S
11
70.5
773.3

Total

First period(14-30 April)

Days
Hours
Distances (n. mile)

28T
11
57.5
643.4

Second period(1-14 May)

Days
Hours
Distances (n. mile)

9
34.3
383.9

8
36.1
396.9

8
33.0
350.1

8
28.4
296.8

33
131.8
1441.6

Third period(15-18 May)

Days
Hours
Distances (n. mile)

3
20.4
230.5

4
20.0
218.8

3
20.1
216.1

3
12.9
141.4

13
73.2
804.0

Total

Days
Hours
Distances (n. mile)

23
112.1
1257.823131.91457.122126.21338.522111.8
1208.590482.0
5275.944277.0
3030.4*: 28T; Taisho Maru No.28, 75K; Koei Maru No.75, 07K; Katsu Maru No.7, 31S; Sumitomo
Maru No.31.
Table 2. List of cetacean species and number of sightings made by four sampling vessels in the2008 JARPN II coastal surveys off Sanriku.

PeriodSpecies

First period(14-30 April)
Second period(1-14May)
Third period(15-18 May)
Total

Common minke whale
Like minke whale
Common minke whale
Like minke whale
Common minke whale
Like minke whale
Common minke whale
Like minke whale

PrimarySch. Ind.
54
54
25
25
16
16
26
2
13
15
6
6
83
85
33
33

Table 3. Density index of common minke whales by sampling vessels
in the 2008 JARPN II coastal survey off Sanriku.
PeriodSPUE*1

DI*2

First period (14-30 April)
0.19
Second period (1-14 May)
0.08
Third period (15-18 May)
0.16
Total
0.12
*1
: No. of primary school sightings per 1 hour searching.
*2

1.78
1.11
1.62
1.61

: No. of primary school sightings per 100 n. miles searching.

5

SecondarySch. Ind.
9
9
3
3
1
1
1
1
1
1
0
0
11
11
4
4

Total
Sch. Ind.
63
63
28
28
17
17
3
3
14
16
6
6
94
96
37
37

Table 4. Summary of biological data and samples collected during the 2008 JARPN II coastal survey off Sanriku.

Number of animals
Male Female Total

Samples and data
Detailed measurements of blubber thickness (11 points)
Body length and sex
External body proportion
Photographic record and external character
Diatom film record
Body scar record
Measurements of blubber thickness (5 points)
Detailed measurements of blubber thickness (11 points)
Body weight
Body weight by parts
Skin tissues for DNA study
Muscle, liver, kidney, spleen, blubber, heart and ventral groove for various analysis
Urine for various analysis
Muscle, liver, kidney, and blubber for heavy metal analysis
Muscle, liver, kidney, and blubber for organochlorine analysis
Collection of blood plasma
Muscle and vertebra for lipid analysis
Mammary grand; lactation status, measurement and histological sample
Uterine horn; measurements and endometrium sample
Collection of Ovary
Photographic record of fetus
Fetal length and weight
External measurement of fetus
Muscle, liver, kidney, heart, blubber and skin tissues of fetus
Collection of fetus
Testis and epididymis; weight and histological sample
Stomach contents, convenient record
Volume and weight of stomach content in each compartment
Observation of marine debris in stomach
Stomach contents for feeding study
Record of external parasites
Earplug for age determination
Tympanic bulla for age determination
Eye lens for age determination
Largest baleen plate for morphologic study and age determination
Baleen plate measurements (length and breadth)
Photographic record of baleen plate series
Length of baleen series
Vertebral epiphyses sample
Number of ribs
Skull measurement (length and breadth)*: including a fetus of sex unidentified.

6

23
23
23
23
23
23
1
23
1
23
23
8
23
23
20
1
3
3
3
3
0
23
23
23
23
19
23
23
23
23
23
23
23
23
23
23
23

37
37
37
37
37
37
4
37
4
37
37
3
37
37
25
4
37
37
37
2
2
2
2
0
37
37
37
33
37
37
37
37
37
37
37
37
37
37
37

60
60
60
60
60
60
5
60
5
60
60
11
60
60
45
5
37
37
37
7*
5
5
5
2*
21
60
60
60
52
60
60
60
60
60
60
60
60
60
60
60

Table 5. Statistics of body length (m) of common minke whales collected during the 2008 JARPN II
coastal survey off Sanriku.
Male
FemalePeriodmean S.D. Min. Max. nmean S.D. Min. Max. n
First period (14-30 April)
5.38 0.79 4.07 6.66 12
5.98 0.94 4.13 7.74 25
Second period (1-14 May)

6.78

1.14

4.63

7.78

6

6.63

1.22

5.27

8.12

5

Third period (15-18 May)

5.06

0.56

4.42

5.90

5

5.13

0.72

4.32

6.15

7

Total

5.67

1.06

4.07

7.78

23

5.91

1.01

4.13

8.12

37

Table 6. Composition of sex and sexual maturity status of common minke whales collected by the2008 JARPN II coastal survey off Sanriku.
Male
PeriodIm M Uk Total

Maturity(%)
0.00

Imm. R P P&L

FemaleUk
Maturity
Total
(%)
1
25
0.24

First period
12 0
0
12
19
0 4
1
(14-30 April)
0
Second period
2 4
0
6
0.67
3
0 2
0
5
(1-14 May)
0
Third period
5 0
0
5
0.00
7
0 0
0
7
(15-18 May)
1
Total
19 4
0
23
0.17
29
0 6
1
37
Im: Immature, M: Mature, R: Resting, P: Pregnant, P&L: Pregnant and lactating, Uk: Unknown

0.40
0.00
0.22

Table 7. Prey species found in forestomach of common minke whales collected by the 2008 JARPN II coastal
survey off Sanriku.
Prey species
PeriodSamplesize

Sand lance(adult)Sand lance(juvenile)

Sand lance(adult+juvenile)

First period(14-30 April)

30
(%)

22
73.3

5
16.7

2
6.7

Second period

9

7

1

1

11.1
5
50.0
11
22.4

11.1
1
10.0
4
8.1

(1-14 May)
Third period(15-18 May)
Total

(%)
77.8
10
3
(%)
30.0
49
32
(%)
65.3
*
: removing animals with broken stomach by harpoon.

7

Japaneseanchovy

Krill
1
3.3

1
10.0
1
2.0

1
5.0
1
2.0

Table 8. Weight (kg) of forestomach content of common minke whales collected by the 2008 JARPN II
coastal survey of Sanriku.
Sand lanceadultjuvenile(adult+juvenile)

Japaneseanchovy

First period(14-30 April)
Second period(1-14 May)
Third period(15-18 May)average
11.3
9.6
range
(1.6-77.4) (2.5-33.4)
average
15.4
27.9
range
(2.2-48.5)
Average
8.2
4.1
range
(7.4-8.8) (0.4-12.7)

53.6(50.8-56.3)
36.1
13.8

6.5

Total

Average
11.9
8.8
range
(1.6-76.4) (0.4-33.4)

39.3(13.8-56.3)

6.5

8

Krill
2.6

2.6

40゜N

Ayukawa

36゜N

Sendai Bay
138゜E

142゜E

50 n.miles
100m

200m

Fig．1. Research area of the 2008 JARPNII coastal survey off Sanriku.

Fig. 2. Cruise trucks made by four sampling vessels in the 2008 JARPNII coastal
survey off Sanriku.

9

10

10

Male (n=23)
Female (n=37)

987Number of animals

6
5
4
3
2
1

9.0-

8.5-9.0

8.0-8.5

7.5-8.0

7.0-7.5

6.5-7.0

6.0-6.5

5.5-6.0

5.0-5.5

4.5-5.0

4.0-4.5-4.0

0

Body length(m)Fig．4. Frequency of body length of common minke whales taken in the 2008 JARPNII coastal survey
by sex.

11

Appendix 1
2008 coastal prey species survey of JARPN II off Sanriku
Hiroto Murase1, Keiichi Onodera2, Ichiro Kobayashi2, Hiroshi Nagashima2 and Shigeyuki Kawahara3
1

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

2

Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi 9862135, Japan

3

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

ABSTRACTA prey species survey was conducted in the coastal region off Sanriku, northeastern Japan in spring 2008 as a part of
JARPNII coastal component off Sanriku. The survey was conducted concurrently with a sampling survey ofcommon minke whales. The survey period was from 9 to 24 April. Five stratified blocks were surveyed. Zigzag
tracklines were set in the blocks. A trawler type RV, Takuyo-maru, conducted the survey. Acoustic data wererecorded continuously along tracklines by a quatitative echosounder. Samplings using a midwater trawl net wereconducted at 9 stations to identify species and size compositions of acoustic backscatterings. Vertical oceanographic
conditions were recorded at 29 stations by using a CTD. Subsurface oceanographic conditions were recorded
continuously along tracklines.
INTRODUCTION
JARPN II is designed to contribute to conservation and sustainable use of marine living resources including whalesin the western North Pacific, especially within Japan’s EEZ (Government of Japan, 2002). One of the major
objectives of JARPNII is to advance feeding ecology and ecosystem studies, involving studies of prey consumption
by cetaceans, prey preference of cetaceans and ecosystem modeling. To accomplish the goal, sampling survey ofcommon minke whales (Balaenoptera acutorostrata) and survey on biomass estimation of their prey species havebeen conducted concurrently off Sanriku, Japan since 2003 as a JARPNII coastal component. In this document, theresults of the 2008 prey species survey off Sanriku are presented.
MATERIALS AND METHODS
While the sampling survey of minke whale was conducted in the coastal waters within the 50 n.miles (mainly within
30 n.miles) from Ayukawa, Miyagi prefecture, Japan, the prey species survey was conducted in wider area at depths
between 20 m and 200 m from 37º 40’ N to 38º 40’ N off Sanriku, northeastern Japan, to elucidate the distribution
and abundance of main prey species. Seven survey blocks (A-G) have been set within the survey block since 2005
for the purpose of biomass estimation of prey species based on a stratified random sampling method using
echosoudner data (Fig 1a). Stratification of blocks was based on bottom depth (20, 40, 100, and 200m) andprefectural boundary (boundary between Miyagi and Fukushima prefecture). Because of logistical constraint, 5
blocks (B, C, E, D, E and F) were surveyed in 2008 (Fig. 1b). A zigzag track line was set to cover each block. The
waypoints of planned track lines in each block were shown in Table 1.
The prey species survey was conducted from April 9 to 24. The survey was conducted during the daytime from anhour after sunrise to an hour before sunset. Acoustic, trawl and oceanographic surveys were conducted using a-12-

trawler-type RV, “Takuyo maru” (Miyagi prefecture, 120 GT). Data of distribution and abundance of the preyspecies were recorded by an EK 500 quantitative echosounder (Simrad, Norway) with operating frequency at 38,
120 and 200 kHz. The RV steamed at about 9-10 knots along the tracklines. Acoustic data were stored with an aid of
software, Echoview (Sonar Data, Austlaria). A calibration was carried out in the survey area on (April 9 2008) using
the copper sphere technique described in EK 500 manual. Vertical oceanographic observations were conducted with
CTD. Subsurface (approximately 5m water depth) temperature, salinity and chlorophyll-a were recorded every
minute (in time) along the tracklines.
Acoustic data were acquired with Echoview Ver.3 (Sonar Data Co., Ltd.). Trawl sampling was conducted to
identify the species and size compositions of targeting echo signs. The trawl net had a mouth opening of 7 m (width)by 3.5 m (height) and a 3 mm liner cod end. The depth and the height of the mouth of the net were monitored with a
net recorder. Towing speed of the trawl net was 2-4 knots. Catches of trawl were identified to the species level andweighed aboard the vessel. For the major species, a sample of 100 animals was taken, and lengths and weights were
measured. Scale and standard lengths were used to anchovy (Engraulis japonicus) and sand lance (adult and juvenile,
Ammodytes personatus), respectively. Total length from the tip of the rostrum to the end of the telson was used for
krill (Euphausia pacifica). Some frozen samples were taken for further analysis in the laboratory.
RESULTS
The planned tracklines were almost surveyed by the quantitative echosounder. A summary of the midwater trawl
operations, temperature by depth and catches was shown on Table 2. Trawl hauls were made at 9 stations. Because
no adult sand lance was sampled in this survey, length frequency data were obtained from samples from acommercial catch. CTD casts were conducted at 29 stations. Continuous monitoring of subsurface temperature
indicated that water temperature was colder than nominal years. Juvenile and adult sand lance was observed in
Blocks B, C, E and F. In contrast to previous surveys, dense schools of juvenile sand lance were observed in thoseblocks. In the past surveys, schools of juvenile sand lance were mainly observed near surface layer. Amount ofCommercial catch of juvenile sand lance during the survey period was significantly higher than 2007. Krill wereobserved near bottom in Blocks C and D. Few schools of Japanese anchovy were observed in Block F. Detailed
analysis will be conducted in the laboratory and the results will be presented in the near future.
ACKNOWLEDGEMENT

We would like to thank the captain of RV “Takuyo-Maru”, Mr. Hiroaki Kimura, and his crews who assisted us
to collect a valuable data set. This survey was supported by Fisheries Agency of Japan, Fisheries Research
Agency of Japan, Miyagi Prefecture and the Institute of Cetacean Research. We thank to these institutions fortheir support.
REFERENCES
Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacific under Special Permit(JARPN II). IWC/SC/54/O2 submitted to the 54th IWC Scientific Committee Meeting, 115pp.

-13-

Table 1. Waypoints and planed lines.
Block B
Waypoint

LatitudeLongitude

Course(degree)Distance（n.mile)

B1

38

-

21.1

N

141

-

22.0

E

257

7.1

B2

38

-

19.5

N

141

-

13.2

E

124

6.3

B3

38

-

16.0

N

141

-

19.9

E

257

15.2

B4

38

-

12.5

N

141

-

01.1

E

106

12.5

B5

38

-

09.0

N

141

-

16.3

E

256

15.2

B6

38

-

05.4

N

140

-

57.5

E

104

14.2

B7

38

-

02.0

N

141

-

15.0

E

256

14.2

B8

37

-

58.5

N

140

-

57.5

E

107

12.0

B9

37

-

55.0

N

141

-

12.1

E

251

3.0

B10

37

-

54.0

N

141

-

08.5

E

-

-

Total

99.8

Block C
Waypoint

LatitudeLongitude

Course(degree)Distance（n.mile)

C1

38

-

15.0

N

141

-

36.9

E

262

17.5

C2

38

-

12.5

N

141

-

14.9

E

102

12.4

C3

38

-

10.0

N

141

-

30.3

E

257

11.4

C4

38

-

07.5

N

141

-

16.2

E

106

8.9

C5

38

-

05.0

N

141

-

27.1

E

255

9.9

C6

38

-

02.5

N

141

-

15.0

E

107

8.8

C7

37

-

60.0

N

141

-

25.6

E

256

9.7

C8

37

-

57.5

N

141

-

13.7

E

106

9.0

C9

37

-

55.0

N

141

-

24.6

E

256

4.2

C10

37

-

54.0

N

141

-

19.5

E

-

-

Total

91.6

-14-

Block D
Waypoint

LatitudeLongitude

Course(degree)Distance（n.mile)

D1

38

-

14.9

N

141

-

48.0

E

106

1.5

D2

38

-

14.5

N

141

-

49.8

E

254

15.9

D3

38

-

10.0

N

141

-

30.4

E

106

16.0

D4

38

-

05.5

N

141

-

49.9

E

257

19.4

D5

38

-

01.0

N

141

-

26.0

E

109

13.6

D6

37

-

56.5

N

141

-

42.3

E

274

8.1

D7

37

-

54.0

N

141

-

32.0

E

-

-

Total

74.5

Block E
Waypoint

LatitudeLongitude

Course(degree)Distance（n.mile)

E1

37

-

54.0

N

141

-

02.5

E

255

2.0

E2

37

-

53.5

N

141

-

00.1

E

104

10.5

E3

37

-

51.0

N

141

-

13.0

E

253

8.7

E4

37

-

48.5

N

141

-

02.5

E

112

6.7

E5

37

-

46.0

N

141

-

10.4

E

248

6.6

E6

37

-

43.5

N

141

-

02.7

E

110

7.2

E7

37

-

41.0

N

141

-

11.2

E

247

2.6

E8

37

-

40.0

N

141

-

08.2

E

-

-

Total

44.2

Block F
Waypoint

LatitudeLongitude

Course(degree)Distance（n.mile)

F1

37

-

54.0

N

141

-

19.0

E

259

5.3

F2

37

-

53.0

N

141

-

12.4

E

103

8.7

F3

37

-

51.0

N

141

-

23.1

E

256

8.1

F4

37

-

49.0

N

141

-

13.2

E

105

7.9

F5

37

-

47.0

N

141

-

22.8

E

260

11.2

F6

37

-

45.0

N

141

-

08.9

E

101

10.0

F7

37

-

43.0

N

141

-

21.3

E

256

8.2

F8

37

-

41.0

N

141

-

11.2

E

106

3.7

F9

37

-

40.0

N

141

-

15.7

E

-

-

Total

63.1

-15-

Table 2. A summary of the trawl sampling.
Station
Date

St-1
10 Apr.

St-2
14 Apr.

St-3
14 Apr.

St-4
14 Apr.

St-5
15 Apr.

St-6
16Apr.

St-7

St-8

St-9

17 Apr.

22 Apr.

24 Apr.

10:24

14:15

17:28

13:20

14:51

14:37

17:59

14:44

36-16N38-00N

37-54N

37-54N38-00N38-12N

38-10N

37-54N38-13NLongitude141-21E

141-02E

141-09E

141-21E

141-23E

141-20E

141-31E

141-16E

141-18E

0m
10 m
20 m
30 m
40 m
50 m
75 m
100 m
Bottom(m)
Trawl sampling
depth (m)

8.90
8.82
8.79
8.51
7.91

8.20
8.17
8.03
7.36

8.50
8.48
8.34
7.58
6.48

9.10
9.02
9.01
8.24
8.01

6.45
(31m)
6

6.40
6.34
5.52
6.32
5.10
4.74
4.82
4.51
4.8
(101m)
40

7.20
6.47
5.90
5.57
5.39
5.28
5.20

7.93
(28m)
21

6.20
5.96
5.65
5.29
5.13
5.04
4.80
4.67
4.67
(90m)
70

10.70
7.14
7.12
7.10
7.67

8.00
(37m)
31

-

5.18
(52m)
25

7.31
(36m)
20

Major sampled
species

Sand lance(juv.)

Sand lance(juv.)

Sand lance(juv.)

Nil

Krill

Sand lance(juv.)Krill

Nil

Sand lance(juv.)Catches (kg)

1.9

20.0

1.2

0.0

1.4

12.0

1.0

0.0

12.0

Temp(°C) by depth

Time
Latitude

-16-

6.51
(39m)
20

(a)

Fig. 1. Survey Blocks (a) and planed tracklines in 2008 (b). Block A and G were not surveyed in 2008.

-17-

Appendix 2
Oceanographic conditions in the coastal survey of JARPN II off Sanriku,
northeastern Japan,
in April 2008
DENZO INAGAKE1, MAKOTO OKAZAKI1, KEIICHI ONODERA2, HIROTO MURASE3,
4

AND TOMIO MIYASHITA

1National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa,236-8648, Japan

2

Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi
986-2135, Japan

3

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

4

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa,236-8648, Japan

Contact e-mail: ina@affrc.go.jp
ABSTRACTA prey species survey was conducted in the coastal region off Sanriku, northeastern Japan, concurrently withthe coastal sampling survey for common minke whales during spring 2008 as a part of JARPN II study.
Oceanographic observations were conducted with CTD from 10 to 24 April 2008 by Takuyo-Maru. According
to the CTD data at 29 stations, water masses in the survey area have characteristics of the Cold water (5ºC <temperature < 10ºC at 100 m depth) near the Oyashio Front (5ºC at 100 m depth).

Introduction
The oceanographic condition in the Tohoku area, northeastern Japan, is one of the mostcomplicated areas in the world. In this area, there are a lot of fronts and water masses. The
Kuroshio flows northward along the coast of southern Japan to the southern part of the Tohoku areawith warm high-salinity water. The Oyashio flows southwestward along the Kuril Islands to thenorthern part of the Tohoku area with cold low-salinity water. The Kuroshio and the Oyashio flows
eastward from the Tohoku area, and the area between the Kuroshio and Oyashio was usually called
the Kuroshio-Oyashio Inter-frontal Zone or perturbed area. The Tsugaru warm water enters into theInter-frontal Zone through Tsugaru Strait and flows southward along the coast of Sanriku. The
warm-core ring is cut off from the Kuroshio extension into the Inter-frontal Zone. Each water mass
is mixed with others, and make a new water mass. Oceanographic condition of the coastal area off
Sanriku is the most variable in the Tohoku area, because the Kuroshio, the warm-core ring, theOyashio, the Tsugaru warm water and other water arrive here by turns.
A prey species survey was conducted onboard Takuyo-Maru (Miyagi prefecture, 120 GT) in the
coastal region off Sanriku, northeastern Japan, concurrently with the coastal sampling survey for-18-

common minke whales during spring 2008 as a part of JARPN II study. Oceanographic observations
were conducted with Conductivity Temperature Depth profiler (CTD) by Takuyo-Maru. In this paper,
we analyzed the CTD data to make clear the oceanic environment in the survey area.
Data and Methods
Hydrographic observations with CTD (SBE 19) were carried out at 29 stations from 10 to 24 April
2008 in the coastal area off Sanriku, northeast of Japan (Fig. 1). Salinity correction for CTD data
was not done using water sampling data.
Oceanic fronts and water masses are usually detected by subsurface temperature map (see Table 1),
because they are obscure in sea surface temperature distributions from summer to fall seasons andthe Oyashio water spreads into the subsurface layer. So, the oceanographic conditions in April 2008
are detected by 100m and 200m temperature maps using the monthly mean subsurface temperature
in seas around Japan from NEAR-GOOS (the North-East Asian Regional-Global Ocean Observing
System) database.
Oceanographic conditions in the survey area
Figure 3 shows the Temperature-Salinity diagrams using CTD data. Almost all water mass in thesurvey area have characteristics of the Cold water. A few stations show the Oyashio water, cold lowsalinity water (colder than 5 ºC and less than 33.5 psu).
Figure 2 shows a schematic hydrographic map in April 2008. The northern limit of the Warmwater spreading from the Kuroshio Extension moves northward from March to November. The
position of the Warm water in April 2008 was at 37º20’N on 144ºE line, which was a more southerly
position than monthly mean location in April (38º40’N). Tsugaru warm water, which is usually
restricted near the coastal area (called as coastal mode) in April, spread eastward to 141 º30’E, andjoined with a warm-core ring (around 141 º30’E, 41º30’N). The southern limit of the first Oyashio
Intrusion located around 39º10’N, 142ºE, which was a more northerly position than monthly mean
location in April (38º30’N), but the cold Oyashio water was cut from the first Oyashio Intrusion to
the survey area along the coast of Sanriku. Almost all stations in the survey area were distributed in
the Cold water (defined by 100 m temperature which is over 5ºC and less than 10ºC) nearby the
Oyashio water cut from the first Oyashio Intrusion.
Figure 4 shows temperature and salinity maps at the depth of 50 m and 100 m, observed by
Takuyo-Maru. Water of 4ºC to 6ºC and 33.4 to 33.6 psu were dominant at the depth of 100 m in Fig.
4. It means that the Cold water and the Oyashio water occupied in the onshore side area and in theoffshore side area, respectively.
Figure 5 shows vertical sections of temperature and salinity. Cold low-salinity water (less than
5ºC and 33.3 psu) was dominant at the mid shelf in Fig. 5. Temperature at surface inshore water andoffshore water are warmer than 5 ºC in each section.
All of these figures show that all stations are distributed in and around the Oyashio water, cutfrom the first Oyashio Intrusion.

-19-

Acknowledgment
A special thank is given to Crews of Takuyo-Maru for their dedication in collecting data.

REFERENCES
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., 56, 47-56 (in Japanese with English abstract).

-20-

Table 1. Extraction method from temperature map to determine the position of eachwater mass according to Kawai (1969) and Murakami (1994).
Target characteristics
Kuroshio Extension Axis
Warm-core ring
Oyashio front
Oyashio water
Cold water
Warm water

Extraction method
14 ºC isotherm at 200 m
Temperature front at 200 m
5ºC isotherm at 100 m
Area with T < 5ºC at 100 m
Area with 5ºC < T < 10ºC at 100 m
Area with T > 10ºC at 100 m and T < 14ºC at 200 m

Fig. 1. Station map observed by Takuyo-Maru in April 10 to 24, 2008.

-21-

Fig.2. Schematic hydrographic map in Tohoku area, northwestern Pacific, in April 2008
with station map observed by Takuyo-Maru.

Fig. 3. Temperature-Salinity diagrams using CTD station data observe by Takuyo-Maruin April 10 to 24, 2008. Each thin line in this figure denotes a density line of sigma-t.

-22-

Fig.4. Temperature (upper panels) and salinity (lower panels) maps at 50 m depth (leftpanels) and 100 m depth (right panels) in the Sanriku coastal area, observed by TakuyoMaru in 10 to 24 April 2008.

-23-

Fig. 5. Temperature (top), salinity (middle) and density anomaly (bottom) sections
along selected stations, observed by Takuyo-Maru in 10 to 24 April 2008-24-