SC/62/O5

Cruise Report of the Second Phase of the Japanese
Whale Research Program under Special Permit in theWestern North Pacific (JARPN II) in 2009 - (Part II) Coastal component off Sanriku
GENTA YASUNAGA1), HIDEHIRO KATO2), TOSHIYA KISHIRO3), HIDEYOSHI YOSHIDA3), HAJIME ISHIKAWA1),
MUTSUO GOTO1), SHIGEO TABATA1), HIKARI MAEDA2), GEN NAKAMURA2), SATOKO INOUE2), NAOKOMIYAKAWA2), TSUTOMU T AMURA1), SAEKO KUMAGAI 1), TOSHIHIDE IWASAKI3), YU KANAJI3), HIKARUWATANABE3), HISOKA HIRUTA1), KEI YAMAZAKI2), YUTA YONEHARA2), HIROYUKI OIKAWA1), KEIICHIONODERA4)

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, Japan
3) 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 2009 survey of the JARPN II coastal component off Sanriku (northeastern Japan,
corresponding to a part of sub-area 7), was conducted from 22 April to 21 May, using four smalltype 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 for biological examination. A total of 4,756.08n.miles (464.0 hours) was surveyed
and 111 schools (112 individuals) of common minke whales were sighted. A total of 60 animals
were sampled. Average body length of the animals was 5.14m (SD: 0.61, n=27) for males and5.12m (SD: 0.80, n=33) for females. Dominant prey species found in the forestomach were adultof Japanese sand lance (Ammodytes personatus) throughout all survey period. Japanese anchovy(Engraulis japonicus) and krill (Euphausia pacifica) were observed less frequently. High densityof Japanese anchovy was observed in the middle of Sendai Bay by the quantitative echosounder,
but the main prey item of minke whale was the sand lance. This suggests possible preferences ofminke whale for this prey species.

1

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.
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), 2007 (Bando et al., 2008) and2008 (Yasunaga et al., 2009).
In the present paper, we show results of the fourth survey carried out in coastal waters off the Sanriku
district, Japan, from 22 April to 21 May in 2009. 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

2

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; Yasunaga et al.,2009). The district occupies northeastern part of the Japanese main island, Honshu (see, Fig. 1). In coastal
waters off the Sanriku district, common minke whales were taken by the past land-based coastal whaling(Miyashita and Hatanaka, 1997). The waters have been also very important fishing grounds. So, thewaters were considered to be suitable for the research area of the JARPN II, and thus the coastal surveys
were conducted 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 isincluded 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 22
April to 21 May, 2009. 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 20 April to 1 May. The distribution and abundanceof the 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
compositions of echo signs were identified by targeting mid-water trawling. Detail of the prey species
surveys are shown 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 in3

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 distanceand 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 4756.08n. miles and 464.0 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 extensively recorded in Sendai Bay during all research period.
As shown in Table 2, a total of 111 schools (112 individuals) of common minke whales were sighted.
These were 99 primary sightings (100 animals) and 12 secondary sightings (12 animals). Of 111 schoolssighted, only 1 school 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 higher during the early research period than the late period.
Sampling of common minke whales
A total of 60 common minke whales were taken for biological examination. In the sampling process,three common minke whale were 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 27 males and 33 females. Sex ratio of males to all
animals was 0.45.
Average body length was 5.14m (max=6.85, min=4.03, SD: 0.61) for males and 5.12m (max=7.72,
min=3.78, SD=0.80) 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 early period werehigher than those in the late period.
Composition of sexual maturity of animals collected is listed in Table 6. In males, 1 of 27 animals were
sexually mature (0.04%), and 1 of 33 females attained sexual maturity (0.03%). One mature female waspregnant.
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 and4frozen for laboratory analysis.
Forestomach contents found from common minke whales during the present survey are listed in Table 7.
Dominant prey species were adult Japanese sand lance (Ammodytes personatus) (83.3%, 45 from 54
animals). Japanese anchovy (Engraulis japonicus) were observed in two animals and krill (Euphausia
pacifica) were observed 7 animals in the research period.
The maximum net weight of forestomach contents was 32.7 kg, of which consisted adult of Japanesesand lance (Table 8).

DISCUSSION
The present survey was the sixth 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. Consequently, almost all of planned sample size was collected in Sendai Bay, wherewater depth is less than 100m.
The minke whales collected in the research period were extensively distributed in the Sendai Bay during
all research period (Fig. 3). And, mature male and female of whales were only one individuals,
respectively (Table 6). The results indicate the Sendai Bay was important for feeding area of immatureminke whales during the research period.
Dominant prey species found from forestomach of animals were adult of Japanese sand lance throughout
survey period (Table 7). Japanese anchovy and krill were observed during the early period.
In the coastal survey off Sanriku, adult of Japanese sand lance had mainly been observed in the stomach
contents of minke whales, whereas Japanese anchovies and krill had slightly been observed since 2007
years (Yoshida, et al. 2004; Yoshida et al., 2006; Goto et al., 2007; Bando et al., 2008; Yasunaga et al.,2009).
Likewise, the rank order of the stomach content of minke whales was Japanese sand lance (83.3%) >krill (13.0%) > Japanese anchovy (3.7%) in the present survey (Table 7). However, high density ofJapanese anchovy was observed in the middle of Sendai Bay by the quantitative echosounder (Appendix
1), this indicates that common minke whales could have food preferences to sand lance in the Sendai Bay.
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.

5

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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.
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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
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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.
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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.

6

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
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submitted to the 56th IWC Scientific Committee, 36pp.
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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 61th IWC
Scientific Committee, 20pp.
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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.

7

Table 1. Searching days, hours, distances by four sampling vessels in the 2009 JARPN II coastal surveys
off Sanriku.
Sampling vessels*
Period

28T

75K

07K

31S

Total

Early period（22 April-5 May）

Days
Hours
Distance(n.mile)

10
63.4
681.81

1085.4
790.221065.5
680.5710
62.2
671.1540276.52823.76

Late period（6-21 May）

Days
Hours
Distance(n.mile)7
33.4
372.88766.7
627.027
39.5
425.26747.9
507.16

28
187.5
1932.32

Total

Days
17
17
17
17
68
Hours
96.8
152.1
105
110.1
464
Distance(n.mile)
1054.69
1417.24
1178.314756.08*: 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 the 2009JARPN II coastal surveys off Sanriku.
PeriodEarly period（22 April-5
May）
Late period（6-21 May）
Total

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

Primary
Sch.
Ind.
65
66

Secondary
Sch.
Ind.
9
9

Sch.
74

Ind.
75

11

11

1

1

12

12

34

34

3

3

37

37

6
99

6
100

0
12

0
12

6
111

6
112

17

17

1

1

18

18

Table 3. Density index of common minke whales by sampling vessels in the 2009JARPN II coastal survey off Sanriku.
PeriodSPUE*1
0.24
Early period （22 April-5 May）
0.18
Late period （6-21 May）
Total
0.22
*1
: No. of primary school sightings per 1 hour searching.
*2: No. of primary school sightings per 100 n. miles searching.

8

DI*2
2.34
1.76
2.10

Total

Table 4. Summary of biological data and samples collected during the 2009 JARPN II coastal survey off Sanriku.
Samples and data

Number of animals
Male
FemaleTotal

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)
Whole 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
Collection of 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)

27
27
27
27
27
27
0
27
0
27
27
10
27
27
20
0
0
0
0
0
0
27
27
27
27
26
27
27
27
25
27
27
27
27
24
27
23

*: including a fetus of sex unidentified.

-9-

33
33
33
33
33
33
0
33
0
33
33
4
33
33
25
0
33
33
33
1
1
1
1
1
33
33
33
29
33
33
33
31
33
33
33
33
33
33
32

60
60
60
60
60
60
0
60
0
60
60
14
60
60
54
0
33
33
33
1
1
1
1
1
27
60
60
60
55
60
60
60
56
60
60
60
60
57
60
55

Table 5. Statistics of body length (m) of common minke whales collected during the 2009 JARPN II coastal survey
off Sanriku.
Male
FemalePeriodmean
S.D.
Min. Max.
n
mean
S.D.
Min.
Max.
n
Early period（22 April-5 May）
5.25
0.64
4.31 6.85 14
5.20
0.91
3.78
7.72
22
Late period（6-21 May）
5.03
0.58
4.03 5.80 13
4.96
0.52
4.20
5.95
11
Total
5.14
0.61
4.03 6.85 27
5.12
0.80
3.78
7.72
33

Table 6. Composition of sex and sexual maturity status of common minke whales collected by the 2009 JARPN II
coastal survey off Sanriku.
Male
PeriodFemaleMaturity
(%)
0.07

Uk

Total

Early period
13 1
0
14
21
0 1
0
0
（22 April-5 May）
Late period
13 0
0
13
0.00
11
0 0
0
0
（6-21 May）
Total
26 1
0
27
0.04
32
0 1
0
0
Im: Immature, M: Mature, R: Resting, P: Pregnant, P&L: Pregnant and lactating, Uk: Unknown

22

Maturity
(%)
0.05

11

0.00

33

0.03

Im

M Uk

Total

Imm.

R

P

P&L

Table 7. Prey species found in forestomach of common minke whales collected by the 2009 JARPN II coastal survey
off Sanriku.

PeriodEarly period（22 April-5 May）
Late period（6-21 May）

No. of whales
observed

Number
Occurrence (%)
Number20
Occurrence (%)
NumberTotal
54
Occurrence (%)*: removing animals with broken stomach by harpoon.
34

-10-

Prey species
Japanese
Sand lanceanchovy
25
2
73.5
5.9
20
95.2
45
2
83.3
3.7

Krill
7
20.6
7
13.0

Table 8. Weight (kg) of forestomach content of common minke whales collected by the 2009 JARPNⅡ
coastal survey off Sanriku.

Early period（22 April -5 May）
Late period(6-21 May)
Total

averagerange
averagerange
average
range

Japanese sand lance

Japanese anchovy

Krill

10.55
(0.6-32.7)
8.21(0.54-34.28)
9.51(0.54-34.28)

10.66(8.14-13.18)

4.38(0.76-10.92)

10.66(8.14-13.18)

4.38(0.76-10.92)

Fig．1. Research area of the 2009 JARPNII coastal survey off Sanriku.

-11-Fig. 2. Cruise trucks made by four sampling vessels in the 2009 JARPNII coastal survey off Sanriku.

Fig. 3. Sighting positions of common minke whales made by sampling vessels in the 2009 JARPNⅡ coastal survey
off Sanriku (●:sighting and sampled; ○: only sighting)

-12-

12
Male (n=27)
10

Female (n=33)

Frecuency

8
6
4
2
0

Body length (m)Fig．4. Frequency of body length of common minke whales is taken in the 2009 JARPNII coastal survey by sex.

-13-

Appendix 1
Coastal prey species survey of JARPN II off Sanriku in 2009
Hiroto Murase1, Keiichi Onodera2, Kiyoshi Matsubara2 and TakafumiSuzuki2
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 986-2135, Japan
ABSTRACTA prey species survey was conducted in the coastal region off Sanriku, northeastern Japan in spring2009 as a part of JARPNII coastal component off Sanriku. The survey was conducted concurrently
with a sampling survey of common minke whales. The survey period was from 20 April to 1 May.
Five stratified blocks were surveyed. Zigzag tracklines were set in the blocks. A trawler type RV,
Takuyo-maru, conducted the survey. Acoustic data were recorded continuously along tracklines by aquantitative echosounder. Samplings using a midwater trawl net were conducted at 9 stations to
identify species and size compositions of acoustic backscatterings. Vertical oceanographic conditions
were recorded at 33 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 ofJapan, 2002). One of the major objectives of JARPNII is to evaluate feeding ecology and ecosystem
studies, involving studies of prey consumption by cetaceans, prey preference of cetaceans andecosystem modeling. To accomplish the goal, sampling survey of common minke whales(Balaenoptera acutorostrata) and survey on biomass estimation of their prey species have been
conducted concurrently off Sanriku, Japan since 2003 as a JARPNII coastal component. In thisdocument, the results of the prey species survey off Sanriku in 2009 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 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
echosoudner data (Fig 1a). Stratification of blocks was based on bottom depth (20, 40, 100, and200m) and political boundary (boundary between Miyagi and Fukushima prefecture). Because oflogistical constraint, only 5 blocks (B, C, D, E and F) was surveyed in 2009 (Fig. 1b). A zigzag track-14-

line was set to cover each block. The waypoints of planned tracklines in each block were shown in
Table 1.
The prey species survey was conducted from 20 April to 1 May. The survey was conductedduring the daytime from an hour after sunrise to an hour before sunset. Acoustic, trawl andoceanographic 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 quantitativeechosounder, 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, Austlaria). A calibration was carried out in the survey area on 14 April using
the copper 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
9 stations. A summary of the midwater trawl samplings was shown in Table 2. CTD casts wereconducted at 33 stations. Continuous monitoring of subsurface temperature indicated that watertemperature was warmer than an average year. Backscatterings of juvenile sand lance was sparsein the entire survey area probably due to warmer sea temperate. In contrast, adult sand lance wasobserved in all blocks except Block D. In addition, high density of Japanese anchovy was observedin Block B, C and F. Distributuion pattens of fishes could be related to the warm water temperature.
Krill was observed Block C and D. In Block C, krill was observed in the area where bottom depth
was deeper than 40 m. Detailed analysis will be conducted in the laboratory and the results will bepresented 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 Agencyof Japan, Miyagi Prefecture and the Institute of Cetacean Research. We thank to these
institutions for their support.
REFERENCES
Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacific-15-

under Special Permit (JARPN II). IWC/SC/54/O2 submitted to the 54th IWC ScientificCommittee Meeting, 115pp.

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Table 1. Waypoints and planed lines.
Block B
Waypoint
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10

Latitude
38
38
38
38
38
38
38
38
37
37

-

21.2
18.0
14.0
13.5
13.1
10.0
06.0
02.0
58.0
54.0

Longitude
N
N
N
N
N
N
N
N
N
N

141
141
141
141
141
140
141
140
141
141

-

21.7
10.5
19.1
16.7
14.8
59.4
16.0
57.1
13.6
00.2

E
E
E
E
E
E
E
E
E
E

Course(degree)
250
121
255
255
256
107
255
107
249
Total

Distance(n.mile)
9.4
7.8
2.0
1.5
12.5
13.7
15.4
13.6
11.3
87.2

Course(degree)
262
252
270
258
262
262
261
102
257
106
255
107
255
106
255
Total

Distance(n.mile)
5.1
0.3
0.2
0.5
8.9
0.7
2.0
12.4
11.4
8.9
9.9
8.7
9.7
9.0
3.9
91.5

Block C
Waypoint
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
C13
C14
C15
C16

Latitude
38
38
38
38
38
38
38
38
38
38
38
38
38
37
37
37

-

15.0
14.3
14.2
14.2
14.1
12.9
12.8
12.5
10.0
07.5
05.0
02.5
00.0
57.5
55.0
54.0

Longitude
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N

141
141
141
141
141
141
141
141
141
141
141
141
141
141
141
141

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-

37.1
30.7
30.3
30.1
29.5
18.3
17.4
14.9
30.3
16.2
27.1
15.0
25.6
13.7
24.6
19.8

E
E
E
E
E
E
E
E
E
E
E
E
E
E
E
E

Block D
Waypoint
D1
D2
D3
D4
D5
D6
D7

Latitude
38
38
38
38
38
37
37

-

15.0
13.0
09.0
05.0
01.0
57.0
54.0

Longitude
N
N
N
N
N
N
N

141
141
141
141
141
141
141

-

41.5
33.1
49.0
27.1
48.0
24.5
36.3

E
E
E
E
E
E
E

Course(degree)
253
108
257
104
258
108
Total

Block E
Waypoint
E1
E2
E3
E4
E5
E6
E7

Latitude
37
37
37
37
37
37
37

-

54.0
52.5
50.0
47.5
45.0
42.5
40.0

Longitude
N
N
N
N
N
N
N

141
141
141
141
141
141
141

-

05.3
12.5
02.3
10.6
02.6
10.1
02.7

E
E
E
E
E
E
E

Block F
Waypoint
F1
F2
F3
F4
F5
F6
F7

Latitude
37
37
37
37
37
37
37

-

54.0
51.5
49.0
46.5
44.0
41.5
40.0

Longitude
N
N
N
N
N
N
N

141
141
141
141
141
141
141

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-

12.3
23.3
13.2
22.8
09.1
21.4
14.2

E
E
E
E
E
E
E

Distance(n.mile)
6.9
13.1
17.7
17.0
19.0
9.8
83.5

Course(degree)
105
253
111
249
113
247
Total

Distance(n.mile)
5.9
8.4
7.0
6.8
6.4
6.4
41.0

Course(degree)
106
253
108
257
104
255
Total

Distance(n.mile)
9.0
8.4
8.0
11.1
10.1
5.9
52.5

Table 2. A summary of the trawl sampling.
Station

St-1

St-2

St-3

St-4

St-5

St-6

St-7

St-8

St-9

Block
Date

B
20 Apr.

B
20 Apr.

B
22 Apr.

B
22 Apr.

C
24 Apr.

D
28Apr.

E

F

F

29 Apr.

30 Apr.

30 Apr.

Time

10:49

14:42

12:06

15:35

11:58

10:23

6:58

10:01

13:59

38-15N

38-06N

38-02N

37-55N38-08N

38-04N

37-51N

37-42N

37-50N

141-16E

141-14E

141-01E

141-06E

141-19E

141-29E

141-09E

141-14E

141-19E

0m

10.5

10.5

10.9

11.2

9.8

9.5

10.9

11.4

11.0

10 m

9.9

10.1

10.4

10.2

9.2

9.1

10.2

10.4

9.6

20 m

9.3

9.1

8.9

7.9

9.4

9.1

10.1

10.3

9.3

30 m

7.7

7.6

9.3

9.1

8.1

9.5

8.5

7.9

Temp (°C) by depth

LatitudeLongitude

40 m

8.3

9.0

7.4

50 m

7.5

7.6

6.9

75 m

6.8

100 m
Bottom(m)

Trawl sampling
depth (m)Major sampled species

6.6
7.7
(36m)

7.6
(33m)

8.3
(23m)

7.8
(27m)

7.7
(47m)

6.5
(106m)

7.8
(35m)

7.5
(61m)

6.9
(57m)

20-30

15-30

20

5-20

0-20

30-100

0-20

20

60

Japanese

Sand lance

Sand lance

Sand lance

Japanese

Krill

Sand lance

Sand lance

Japaneseanchovy(adult)(adult)(adult)anchovy(adult)(adult)anchovy

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(a)

Fig. 1. Survey Blocks (a) and planed tracklines in 2009 (b). Block A and G were not surveyed in2009.

20