SC/63/O3

Cruise report of the second phase of the Japanese Whale Research
Program under Special Permit in the Western North Pacific (JARPNII) in 2010 (Part II) - Coastal component off Sanriku.
TAKEHARU BANDO1, GENTA YASUNAGA1, NOBUYUKI ITO2, SHIGEO TABATA2, HIROYUKI OIKAWA1, GEN
NAKAMURA3, HIKARI MAEDA3, NAOKO MIYAKAWA3, RYOKO ZENITANI3, YUI ZENNYOJI3, YUTA
YONEHARA3, YUICHIRO ISHIKAWA3, KAZUKI FUKUTOME4, MASAOMI TSUNEKAWA4, MOTONORI AKI4, KEIYAMASAKI3, TAICHI TSUTSUMI3, KAZUYA KITAYAMA3, KEIICHI ONODERA5, HIDEHIRO KATO3

Contact e-mail:bando@cetacean.jp
1

Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan.
Association for Community-Based Whaling, 2-5-28, Hakata-eki-higashi, Hakata-ku, Fukuoka, 812-0013,
Japan
3
Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108-0075, Japan
4
Kyodo Senpaku Co. Ltd., 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
5
Miyagi Prefecture Fisheries Technology Institute, 97-6, Sodenohama, Watanoha, Ishinomaki, Miyagi,
986-2135, Japan
2

ABSTRACTThe seventh survey of the JARPN II coastal component off Sanriku (southern part of the sub-area 7)
was conducted from 22 April to 7 June in 2010 using 4 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 sampled werelanded on the research station established for biological examination. During the 47 days survey, atotal of 8,957.0n. miles was surveyed and 62 schools (62 individuals) of common minke whales
were sighted. A total of 45 whales were sampled. Average body length was 6.02m (SD: 1.15, n=18)
for males and 5.12m (SD: 0.99, n=27) for females. Dominant prey species found in forestomach of
the animals were Japanese sand lance (Ammodytes personatus) followed by krill (Euphausia
pacifica). Japanese anchovy (Engraulis japonicus) was observed in only one of the animals sampled.
The density of sand lance, as detected by echo sounder, was lower than in previous years, which
could have affected the distribution pattern of common minke whales.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; COASTAL WATERS OF JAPAN;
FOOD/PREY; ECOSYSTEM; SCIENTIFIC PERMITS.

INTRODUCTION
After a 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)
was started in 2002. The objectives of JARPN II are, i) feeding ecology and ecosystem studies,
involving prey consumption by cetaceans, prey preferences of cetaceans and ecosystem studies, ii)monitoring environmental pollutants in cetaceans and the marine ecosystem and iii) elucidation of
the stock structure of whales (Government of Japan, 2002). The JARPN II has both coastal andoffshore component. The coastal component involves surveys in two coastal localities, Sanriku inspring and Kushiro in fall. Annually a maximum of 60 whales is sampled in each locality.
The objective of this paper is to report the results of the seventh survey carried out in coastal waters
off the Sanriku district, Japan, from 22 April to 7 June in 2010. This survey was authorized by theGovernment of Japan in compliance with Article VIII of the International Convention for the
Regulation of Whaling. The Institute of Cetacean Research (ICR) planned and conducted the survey
in cooperation with the National Research Institute of Far Seas Fisheries, Tokyo University ofMarine Science and Technology and Miyagi Prefecture Fisheries Research and Development Center.
MATERIALS AND METHODS1

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Research area
The research area was set in the same manner as in previous JARPN II surveys off Sanriku (Yoshida
et. al, 2004; 2006; Goto et al., 2007; Bando et al., 2008; Yasunaga et al., 2009; 2010). The Sanriku
district occupies the northeastern part of the Japanese main island, Honshu (Figure 1). The researcharea coincides with important fishing grounds, and the waters off Sanriku were the whaling groundfor the past coastal commercial whaling (Miyashita and Hatanaka, 1997). The research area was set
within 50n. miles from the Ayukawa port (Figure 1). The survey area is located in the southern partof 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(hereinafter referred as 28T; 47.3GT), Koei Maru No. 75 (75K; 46.0GT), Katsu Maru No.7 (7K;
32.0GT), and Sumitomo Maru No.31 (31S; 32.0GT). All the animals sampled were landed on the
JARPN II research station established in the Ayukawa port for biological examination.
Prey species survey
The Takuyo Maru (TAK, 120.0GT), a trawler-type research vessel, conducted the prey species
survey in the area off northeast coast of Honshu from 16 April to 22 May. The distribution andabundance of the prey species were investigated using a quantitative echo sounder (EK 500 and ER
60). Acoustic data were acquired with operating frequency at 38, 120 and 200 kHz. Species/size
compositions of echo signs were identified by the samples obtained by mid-water trawling. Detailsof the prey species surveys are shown in Appendix. The research vessel TAK also carried out
oceanographic observation using CTD and EPCS.
Sighting and sampling methods
Sighting and sampling methods by whale sampling vessels were almost the same as in the past
coastal surveys conducted off Ayukawa. The research head office was placed in the research stationand operated the sampling vessels during the survey. To avoid concentration of sampling effort, theresearch area was divided into three small areas.
In each vessel a researcher was on board and recorded the cruise tracks, searching time on effort, sea
weather conditions and sighting data. Sighting data was collected for all baleen whales, sperm
whales and killer whales. Searching was carried out during the day and the vessels returned to theport every night. Sighting was conducted from the top barrel and upper bridge by all the crews andresearcher with vessel speed at about 11 knots. All common minke whales sighted were targeted forsampling, except for the cow-calf pairs. When a sighting consisted of more than one animal, firsttargeted animal was selected following the random sampling digits. Sampling was made by 50 mm
whaling cannon. Once the vessel caught a whale, it returned to the Ayukawa port to transport the
animal to the research station. While returning to the port, other common minke whales sighted werealso targeted for sampling, if the situation allowed. At the port, the sampled whale was lift up fromthe vessel using wire nets and a crane and transported to the station by freight trailer. At that time,
body weight of the whale 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 2. 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, 07K and 31S) are shown in Figure 2. The
sampling vessels tried to cover research areas widely within 30n. miles from Ayukawa port. Usually
searching activity is low in offshore waters because of changeable weather condition and bigger
waves for small sampling vessels. In the present survey a larger amount of sighting effort was put in2

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offshore waters compared to past surveys. Searching distance made by the four sampling vessels is
listed in Table 1. The total searching distance made by the four vessels was 8,957.0n. miles.
Sightings and samplings of common minke whales
Sighting positions of common minke whale schools recorded by the sampling vessels are shown in
Figure 3. Much of common minke whale sightings were made in the middle part of Sendai Bay. As
shown in Table 1, a total of 62 schools (62 individuals) of common minke whales were sighted.
These were 59 primary sightings (59 animals) and three secondary sightings (three animals). No
cow-calf pairs were sighted. Density index (DI: the number of primary sightings of schools per 100
n. miles searching) of common minke whales was calculated as 0.66. Of the 62 common minke
whales sighted, 45 individuals were sampled. No struck and lost occurred.
Sighting of other large cetaceans
A total of 62 schools (69 individuals) of humpback whales and 13 schools (38 individuals) of killer
whales were sighted (Table 1). Sighting positions of those whales were shown in Fig. 3.
Sex ratio, body length and weight of animals caught
Research items of biological examination are summarized in Table 2, including the number of dataand samples obtained. The sampled 45 animals consisted of 18 males and 27 females. Sex ratio ofmales was 0.40. Average body length was 6.02m (max=7.77, min=4.27, SD: 1.15) for males and5.12m (max=8.45, min=3.69, SD=0.99) for females (Table 3). Frequency of body length of common
minke whale by sex was shown in Figure 4. Composition of sex and sexual maturity status is listed
in Table 4. In males, six of 18 animals were sexually mature (33.0%). Only one female (in 27
females sampled) was sexually mature (3.7%).
Prey species of common minke whale
Stomach contents of all sampled animals were examined except for nine animals where the stomachs
were broken by the harpoon. Forestomach contents were listed in Table 5. The dominant preyspecies were adult sand lance (Ammodytes personatus) (75.0%, found in 27 of 36 animals) following
by krill (19.4%, found in seven 7 of 36 animals). Japanese anchovy (Engraulis japonicus) wasrecorded from only one animal.
DISCUSSION
Same as in previous surveys bad weather conditions such as low atmospheric pressure, bigger waves
and fog were common in the present survey. Nevertheless, considerable amount of research effort
was expended in offshore waters compared to previous surveys (Figure 2).
Distribution of common minke whales was concentrated to Sendai Bay, but some whales weresighted in offshore waters (Figure 3). The density index of common minke whales was 0.66, which
was the lowest among the past seven surveys. Abundance of sand lance, which was major preyspecies of common minke whales in the research area, was low in this season (Onodera personalcommunication), which might affect distribution pattern of common minke whales. Sea surface
temperature in Sendai Bay in April was lower than in usual years and this condition continued until
the end of May (Onodera personal communication), which would also affected distribution patternof common minke whales and their prey species.
Large number of humpback and killer whales was sighted in this survey. Humpback whale was veryrare and only two individuals were sighted until 2008 (Yoshida et al., 2004; 2006, Goto et al., 2007,
Bando et al., 2008, Yasunaga et al., 2009). Sighting of humpback whales suddenly increased to 34
school/35 individuals in 2009 (Yasunaga et al., 2010) and 62 school/69 individuals were sighted in
the present survey. Although these figures probably include some duplicated sightings, the numberof humpback whales is becoming similar to that of common minke whales. Increase of humpbacksighting was also reported in Kushiro region (Kishiro et al., 2010).

3

SC/63/O3Same as in previous surveys, immature whales dominated in the research area. In the case of females
only one mature whale was found among 27 individuals sampled. This segregation pattern was
typical of recent surveys (Yasunaga et al., 2009; 2010). This result indicates that research area isimportant feeding and migration area for immature whales. Dominant prey species of common
minke whale were Japanese sand lance followed by krill. Krill was observed especially from whales
sighted in water of more than 100m depth (Figure 5). High density of krill in these areas was also
observed by the prey species survey (Onodera personal communication), which suggests that
common minke whales feed on what is abundant in the area.
From the present survey we obtained valuable information on feeding ecology of minke whales. To
increase the precision of estimates of food consumption and to understand the variability in prey
consumption the continuation of systematic costal surveys is required.
ACKNOWLEDGMENTS
We acknowledge Shigeki Takaya, the Fisheries Agency of Japan, for his guidance andimplementation to the research. Crewmen of research vessels, staffs of the research station in
Ayukawa, and the Japan small-type whaling association contributed greatly to this survey. We also
thank all the members of the municipal office of Ishinomaki, the Ojika fisheries Cooperative
Association, and the Miyagi Prefectures office, for their kind assistance.
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 the second 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 scientific Committee, 27pp.
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 scientific Committee, 34pp.
Government of Japan, 2002. Research plan for cetacean studies in the western North Pacific under
special permit (JARPN II). Paper SC/54/O2 submitted to the 54th IWC Scientific Committee.
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.
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 Pacificminke whale. Rep .int. Whal. Commn 47:539-542.
Yasunaga, G., Kato, H., Kishiro, T., Yoshida, H., Nishiwaki, S., Saito, T., Tabata, S., Okamoto, R.,
Maeda, H., Nakamura, G., Inoue, S., Otani, S., Iwasaki, T., Kanaji, Y., Mogoe, T., Murase, H.,
Wada, A., Nakai, K., Matsumoto, A., Gokita, A., Yamazaki, K., Oikawa, H., Onodera, K.,
Shiraishi, K. and Nagashima, H. 2009. Cruise report of the second phase of the Japanese Whale
Research Program under Special Permit in the Western North Pacific (JARPN II) in 2008 Coastal component off Sanriku. Paper SC/61/O6 submitted to the 61st IWC Scientific Committee,
20pp.
Yasunaga, G., Kato, H., Kishiro, T., Yoshida, H., Ishikawa, H., Goto, M., Tabata, S., Maeda, H.,
Nakamura, G., Inoue, S., Miyashita, N., Tamura, T., Kumagai, S., Iwasaki, T., Kanaji, Watanabe,
H., Hiruta, H., Yamazaki K., Yonehara Y., Oikawa, H., Onodera, K. 2010. Cruise report of thesecond phase of the Japanese Whale Research Program under Special Permit in the Western North
Pacific (JARPN II) in 2009 - Coastal component off Sanriku. Paper SC/62/O5 submitted to the4

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62nd IWC Scientific Committee, 20pp.
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 report of 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 scientific Committee, 30pp.

Table 1. Searcheng days, distances and number of sightings made by the whale sampling survey.
Number of sightings
Primary
SecondarySch. Ind.
Sch. Ind.
Common minke whale
59
59
3
3
Like minke whale
33
33
1
1
Humpback whale
59
66
3
3
Killer whale
11
31
2
7

PeriodDays

Distances(n. miles) Species

22 Apr. - 7 Jun.

47

8957.05

Total
Sch. Ind.
62
62
34
34
62
69
13
38

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Table 2. Summary of biological data and samples.
Data and samples
Body length and sex
External body proportion
Photographic record and external character
Diatom film record
Body scar record
M easurements of blubber thickness (5 points)
Detailid measurements of blubber thickness (11 points)
Body weight
Body weight by parts
Skin tissues for DNA study
M uscle, liver, kidney, and blubber for heavy metal analysis
M uscle, liver, kidney, and blubber for organochlorines analysis
M uscle and blubber for byproduct analysis
M uscle, liver, kidney, spleen, blubber, heart and ventral goove for various analysis
M uscle and vertebra for lipid analysis
Urine for various analysis
M ammary grand; lactation status, measurement and histological sample
Uterine horn; measurements and endometrium sample
Collection of Ovary
Photographic record of foetus
Foetal sex (identified by visual observation)
Foetal length and weight
External measurement of foetus
M uscle, liver, kidney, heart, blubber and skin tissues of foetus
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
Stomach contents for multipurpose study
Record of external parasites
Earplug for age determination
Tympanic bulla 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
Eye lens for age determination
Collection of blood plasma
Vertebral epiphyses sample
Number of ribs
Skull measurement (length and breadth)
Brain weight6

Number of whales
Male Female Total
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
0
1
1
18
27
45
0
1
1
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
0
1
1
7
6
13
27
27
27
27
27
27
0
1
1
0
1
1
0
1
1
0
1
1
0
1
1
18
18
18
27
45
18
27
45
18
27
45
18
27
45
1
2
3
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
18
27
45
15
26
41
18
27
45
18
27
45
18
26
44
0
1
1

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Table 3. Statistics of body length (m) of common minke whales.
n

mean

Male
S.D. Min. Max.

n

mean

FemaleS.D. Min. Max.

22 Apr. - 5 May

4

6.38

1.39

4.27

7.77

10

5.25

0.66

4.37

6.53

6 May - 20 May

5

6.09

1.03

4.79

7.46

8

4.66

0.72

3.69

5.62

21 May - 7 June

9

5.81

1.04

4.35

7.57

9

5.37

1.32

3.73

8.45

Total

18

6.02

1.15

4.27

7.77

27

5.12

0.99

3.69

8.45

PeriodTable 4. Composition of sex and sexual maturity status.
Male
PeriodFemale22 Apr. - 5 May

2

2

4

Maturity(%)
50.0

6 May - 20 May

3

2

5

21 May - 7 June

7

2

Total

12

6

Imm. Mat. Total

Imm. Preg. Total

Sex ratio
Maturity(%males)
(%)
0.0
28.6

10

0

10

40.0

8

0

8

0.0

38.5

9

22.2

8

1

9

11.1

50.0

18

33.3

26

1

27

3.7

40.0

Table 5. Number of common minke whales by major prey species found in theirforestomach contents.
PeriodPrey species
Japaneseanchovy

Sand lance(adult)Krill

22 Apr. - 5 May 10 (71.4)

3 (21.4)

6 May - 20 May

7 (53.8)

Total

None

Unknown*

0 (0.0)0 (0.0)1 (7.1)14

3 (23.1)

0 (0.0)0 (0.0)3 (23.1)

13

21 May - 7 June 10 (55.6)

1 (5.6)1 (5.6)1 (5.6)5 (27.8)

18

Total

7 (15.6)

1 (2.2)1 (2.2)9 (20.0)45

27 (60.0)*Stomach was broken by harpoon

40゜N

Ayukawa

36゜N

Sendai Bay
138゜E

142゜E

50 n.miles
100m

200m

Fig．1. Research area of the 2010 JARPN II coastal survey off Sanriku.

7

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Fig. 2. Cruise trucks made by 4 sampling vessels.

Fig. 3. Sighting position of common minke (left, ●: sighted and sampled, ○: sighted only), humpback(right :▲) and killer (right :+) whales.

8SC/63/O3

Number of animals

8

Male
Female642

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

3.5-4.0

3.0-3.5

0Body length (m)Fig. 4. Body length frequency of common minke whales.

Fig. 5. Sighting position of common minke whales by major prey species (○: sand lance, ●: krill, ▲: Japanese
anchovy) found in the forestomach.

9

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Appendix
Coastal prey species survey of JARPN II off Sanriku in 2010
Hiroto Murase1 and Keiichi Onodera2
1

The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo 104-0055, Japan
Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi
986-2135, Japan

2

ABSTRACTA prey species survey was conducted in the coastal region off Sanriku, northeastern Japan inspring 2010 as a part of JARPNII coastal component off Sanriku. The survey was conductedconcurrently with a sampling survey of common minke whales. The survey was conducted in
April (16 - 27 April) and May (13 - 22 May). Four stratified blocks were surveyed. Zigzag
tracklines were set in the blocks. The Same blocks and tracklines were surveyed in April andMay to see whether occurrence patterns of prey species were different between the months. A
trawler type RV, Takuyo-maru, conducted the survey. Acoustic data were recorded continuously
along tracklines by a quantitative echosounder. Samplings using a midwater trawl net wereconducted at 12 stations to identify species and body size compositions of acoustic
backscatterings. Vertical oceanographic conditions were recorded at 44 stations by using a CTD.
Subsurface oceanographic conditions were recorded continuously along tracklines.
INTRODUCTION
JARPN II is designs to contribute to conservation and sustainable use of marine living
resources including whales in the western North Pacific, especially within Japan’s EEZ(Government of Japan, 2002). One of the major objectives of JARPNII is to study feeding ecologyof cetaceans and ecosystem studies, involving studies of prey consumption by cetaceans, prey
preference of cetaceans and ecosystem modeling. To accomplish the goal, a sampling survey ofcommon minke whales (Balaenoptera acutorostrata) and a survey on biomass estimation of
their prey species have been conducted concurrently off Sanriku, Japan since 2003 as a
JARPNII coastal component. In this document, the results of the prey species survey off
Sanriku in 2010 are presented.
MATERIALS AND METHODS
While the sampling survey of minke whales 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 bottom depths between 20 m and 200 m from 37º 40’ N to
38º 15’ 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 echosounder data (Fig 1a). Stratification of blocks was based on bottom depth (20, 40, 100,
and 200m) and political boundary (boundary between Miyagi and Fukushima prefecture).
Because of logistical constraint, only 4 blocks (B, C, E and F) were surveyed in 2010 (Fig. 1b). A
zigzag track line was set in each block. The waypoints of planned tracklines in each block wereshown in Table 1.
The survey was conducted in April (16 - 27 April) and May (13 - 22 May). Same blocks
and tracklines were surveyed in April and May to see whether occurrence patterns of preyspecies were different between the months. The survey was conducted during the daytime from10

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an hour after sunrise to an hour before sunset. Acoustic, trawl and oceanographic surveys
were conducted using a trawler-type RV, “Takuyo maru” (Miyagi prefecture, 120 GT). Data of
distribution and abundance of the prey species were recorded by a quantitative echosounder,
EK500 (Simrad, Norway) with operating frequency at 38, 120 and 200 kHz. The RV steamed at
9-10 knots along the tracklines. Acoustic data were stored with an aid of software, Echoview(Sonar Data, Australia). A calibration was carried out in the survey area on 16 April using thecopper sphere technique described in EK 500 manual. Vertical oceanographic observations wereconducted with CTD. Subsurface (approximately 5m water depth) temperature, salinity andchlorophyll-a were recorded every minute (in time) along the tracklines.
Trawl sampling was conducted to identify the species and size compositions of targetingechosigns. 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
and weighed aboard the vessel. For the major species, a sample of 100 animals was taken, andlengths and weights were measured. Scale and standard lengths were used to Japanese
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. Trawl was
towed at 12 stations. A summary of the midwater trawl samplings was shown in Table 2. CTD
casts were conducted at 44 stations. Occurrences of prey species were different between April
and May. In April, backscatterings of juvenile sand lance and krill were observed while these of
adult sand lance and Japanese anchovy were rarely observed. In May, number ofbackscatterings of adult sand lance and Japanese anchovy was increased. Backscatterings ofjuvenile sand lance and krill were also observed in May. 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 hiscrews who assisted us to collect a valuable data set. This survey was supported by
Fisheries Agency of Japan, Miyagi Prefecture and the Institute of Cetacean Research. We
thank these institutions for their support.
REFERENCES
Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacificunder Special Permit (JARPN II). IWC/SC/54/O2 submitted to the 54th IWC ScientificCommittee Meeting, 115pp.

11

SC/63/O3
Table 1. Waypoints and planed lines.
Block B
Waypoint

LatitudeLongitude

Course(degree)Distance(n.miles)

B1

37

-

54.0

N

141

-

12.3

E

294

13.5

B2

37

-

59.5

N

140

-

56.7

E

70

15.8

B3

38

-

05.0

N

141

-

15.5

E

294

13.6

B4

38

-

10.5

N

140

-

59.7

E

71

16.7

B5

38

-

16.0

N

141

-

19.8

E

332

5.7

B6

38

-

21.0

N

141

-

16.4

E

-

-

Total

65.3

Block C
Waypoint
C1
C2
C3
C4
C5
C6
C7
C8

Latitude
38
38
38
38
38
37
37
37

-

15.0
14.5
10.5
06.5
02.5
58.5
54.5
54.0

Course Distance(degree) (n.miles)

Longitude
N
N
N
N
N
N
N
N

141
141
141
141
141
141
141
141

-

31.7
33.6
17.5
27.7
15.0
25.0
12.3
13.6

E
E
E
E
E
E
E
E

108
253
116
248
117
248
116
Total

1.6
13.3
9.0
10.8
8.8
10.8
1.1
55.4

Block E
Waypoint

LatitudeLongitude

Course(degree)Distance(n.miles)

E1

37

-

54.0

N

141

-

00.2

E

109

10.8

E2

37

-

50.5

N

141

-

13.1

E

248

9.4

E3

37

-

47.0

N

141

-

02.0

E

121

6.8

E4

37

-

43.5

N

141

-

09.4

E

237

6.4

E5

37

-

40.0

N

141

-

02.7

E

-

-

Total

33.4

Block F
Waypoint

Latitude

Course Distance(degree) (n.miles)

Longitude

F1

37

-

54.0

N

141

-

22.9

E

249

F2

37

-

51.0

N

141

-

13.0

E

114

8.6

F3

37

-

47.5

N

141

-

23.0

E

252

11.5

F4

37

-

44.0

N

141

-

09.1

E

110

10.3

F5

37

-

40.5

N

141

-

21.4

E

247

1.3

F6

37

-

40.0

N

141

-

19.9

E

-

-

Total

40.2

12

8.4

SC/63/O3
Table 2. A summary of the trawl sampling.
April
Station

St-1

St-2

St-3

St-4

St-5

St-6

Block

B

B

B

C

F

F

Date

19 Apr.

19 Apr.

20 Apr.

20 Apr.

26 Apr.

26 Apr.

Time

11:16

15:33

9:17

15:15

11:38

15:35

38-11N38-00N

37-58N38-05N

37-50N

37-40N

141-04E

140-58E

140-59E

141-24E

141-15E

141-20E

0m

8.3

8.1

8.2

8.3

7.6

6.9

10 m

7.3

7.5

7.7

7.1

7.6

6.9

20 m

7.4

7.5

Temp (°C) by depth

LatitudeLongitude

7.0

7.0

6.7

30 m

6.7

6.7

6.6

40 m

7.0

6.0

50 m

7.1

5.7

75 m

5.0

100 m
Bottom

7.2

7.2

7.3

5.8

5.9

5.0

(m)

(22m)

(24m)

(16m)

(73m)

(39m)

(88m)

Trawl sampling

10-20

10-15

10-20

50

40

30-40

Sand lance

Sand lance

Sand lance

Maurolicus

Krill

Krill

(juvenile)(juvenile)(juvenile)japonicus

St-9

St-10

St-11

St-12

St-13

St-14

depth (m)Major sampled species

May
Station
Block

B

B

C

F

F

F

Date

17 May18 May19 May21 May22 May22 May

Time

12:35

9:07

11:41

13:14

11:04

13:45

Latitude38-13N

37-59N

38-06N

37-40N

37-47N

37-54NLongitude

Temp (°C) by depth

141-11E

140-56E

141-26E

141-20E

141-22E

141-23E

0m

14.0

14.2

12.7

13.8

13.4

14.8

10 m

10.1

9.7

10.4

11.1

10.5

11.9

20 m

7.2

8.8

7.0

7.6

10.4

30 m

6.1

7.3

5.9

6.2

8.3

40 m

5.6

5.5

5.6

7.2

50 m

6.8

5.1

5.3

6.2

75 m

5.5

5.1

5.1

5.7

100 m
Bottom

6.1

7.3

5.3

5.1

5.1

5.2

(m)

(31m)

(16m)

(86m)

(87m)

(79m)

(86m)

5

10

85

80

80

80

Japanese

Sand lance

Krill

Sand lance

Krill

Sand lanceanchovy(juvenile)

Trawl sampling
depth (m)Major sampled species(adult)13(adult)SC/63/O3(a)(b)
Fig. 1. Survey Blocks (a) and planed tracklines (b) in 2010. Block A, D and G were notsurveyed in 2010.

14