SC/65a/O07

Cruise Report of the Second Phase of the Japanese Whale
Research Program under Special Permit in the Western
North Pacific (JARPN II) in 2012 - (Part II) - Coastal
component off Sanriku survey
GENTA YASUNAGA1), NOBUYUKI ITOH2), HIROYUKI OIKAWA1), GEN NAKAMURA3), HIKARI MAEDA3), SATOKOINOUE3), KAZUYA KITAYAMA3), ICHIRO KADOWAKI3), NOZOMI TAMAI3), NAOKO MIYAKAWA3), YUICHIROISHIKAWA3), KOZUE ISHIDA3), NOBUYUKI SUZUKI3), NOZOMI KOBAYASHI3), HITOMI SATO2), SAEKO KUMAGAI2),
NAGISA SAKAMOTO2), HIDEHIRO KATO3)

1) Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo 104-0055, Japan
2) 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
Contact e-mail:yasunaga@cetacean.jp
ABSTRACTThe 2012 survey of the JARPN II coastal component off Sanriku (northeastern Japan, corresponding to a part of
sub-area 7), was conducted from 12 April to 26 May, using four small-type whaling catcher boats and one echosounder trawl survey vessel. Sampling of common minke whales was conducted in coastal waters within 50 n. miles
from Ayukawa port in the Sanriku district, and all animals collected were landed at the JARPN II research station
established for biological examination in Ayukawa. A total of 6,488.1 n.miles (620.1 hours) was surveyed and 95
schools (97 individuals) of common minke whales were sighted. A total of 60 animals were sampled. Average bodylength of the animals was 5.10 m (SD: 0.82, n=29) for males and 5.34 m (SD: 0.97, n=31) for females. Dominant
prey species found in the forestomach of common minke whales collected in the Sendai Bay were adult and juvenile
Japanese sand lances, and those collected outside the Sendai Bay were Japanese anchovies and krill. Information onsighting distribution, biological characteristics of whales sampled and feeding habit obtained during the 2012 survey
was similar to that obtained before the 2011 earthquake and tsunami.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; FEEDING ECOLOGY; SCIENTIFICPERMITS.

INTRODUCTION
After the two-year feasibility study in 2000-2001, the full-scale survey of the Second Phase of the Japanese Whale
Research Program under Special Permit in the Western North Pacific (JARPN II) was started in 2002. The
objectives of the program are 1) Feeding ecology and ecosystem studies, involving prey consumption by cetaceans,
prey preferences of cetaceans and ecosystem modeling; 2) Monitoring environmental pollutants in cetaceans and themarine ecosystem; and 3) Stock structure of whales (Government of Japan, 2002).

1

The JARPN II coastal component using small-type whaling catcher boats started in 2002 to complement thetemporal and spatial gap of the offshore components using the Nisshin Maru research vessel. In the original JARPN
II plan, the coastal component was presented as a two-year feasibility study to examine the logistic aspects of themethodology (Government of Japan, 2002). The first feasibility survey was carried out in the coastal waters off
Kushiro in autumn 2002 (Kishiro et al., 2003) and the second 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 werecaught.
From detailed examination of the logistic aspects of the surveys, it was concluded that no substantial problem
occurred and that the coastal survey could be continued as a component of the JARPN II using same kind of vessels(small-type whaling catcher boats) and methodology (Government of Japan, 2004a, Kato et al., 2004). However, recalculation of required sample size from the survey data suggested that the size should be modified to 60 individuals
in each area/season (Tamura et al., 2004), and from the possible geographical and/or temporal variations of prey
consumption of the whales, the coastal surveys thought to be needed on a yearly basis in each local area
(Government of Japan, 2004b). The revised survey off Sanriku was carried out in spring during 2005 and 2010 year
(Yoshida et al., 2006; Goto et al., 2007; Bando et al., 2008, 2011; Yasunaga et al., 2009, 2010).
On March 11 2011 the Ayukawa town, including all research facilities of JARPN II, was destroyed by a large
earthquake and tsunami. In this year the spring coastal survey could not be conducted in Ayukawa. Instead thespring survey in 2011 was conducted in Kushiro. Fortunately the Ayukawa research station was reconstructed andthe 2012 survey of the JARPN II coastal component in spring could be conducted in this locality again.
Here we report the survey carried out in coastal waters off Sanriku from 12 April to 26 May in 2012. This survey
was authorized by the Government 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 and Tokyo University of Marine Science and Technology,
and the Association for Community-Based Whaling.

MATERIALS AND METHODS
Research area
The research area was set in the same way as in previous surveys off Sanriku (Bando et. al, 2011). The research area
comprised coastal water within 50 n. miles from northeastern part of the Japanese main island, Honshu, (Figure 1).
The area was divided into Areas 1, 2 and 3 centering on the Ayukawa port (Figure 1). The research area corresponds
to the northern part of sub-area 7, established by IWC (1994).
Whale sampling
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No. 28 (hereinafter referred as
28T; 47.3GT), Koei Maru No. 8 (8K; 32.0GT), Katsu Maru No.7 (7K; 32.0GT), and Sumitomo Maru No.51 (51S;
30.0GT). All the animals sampled were landed on the JARPN II research station established at the Ayukawa port forbiological examination. All common minke whales collected were examined biologically by researchers at the2research station. A list of biological items to be collected is shown in Table 1.
Prey species of common minke whale
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, in each of the four chambers, for both cases including andexcluding liquid contents. In addition a small sample of forestomach contents was collected and frozen forlaboratory analysis.

RESULTS
Searching effort
The whale sampling survey was conducted from 12 April to 26 May, 2012. Cruise tracks by the sampling vessels
28T, 8K, 7K and 51S are shown in Figure 2. The tracks covered widely the coastal waters off Sanriku. Searching
distance and time are listed in Table 2, by sampling vessel. Searching distance and time are defined as distance andtime recorded under searching activity conducted from the top barrel of the vessels. Total searching distance andtime made by the three vessels were 6,488.1 n. miles and 620.1 hours, respectively (Table 2).
Sightings
A total of 95 schools (97 individuals) of common minke whales was sighted during the searching (Table 3, Figure 3).
One cow-calf pair was observed. Density index (DI, the number of primary sightings of schools per 100 n.miles
searching) of common minke whales in Areas 1, 2 and 3 were calculated as 2.43, 0.43 and 0.49, respectively (Table4). Two schools (two individuals) of fin whales, 43 schools (58 individuals) of humpback whales and 4 schools (11individuals) of killer whales were sighted during the searching (Table 3, Figure 4).
Sampling of common minke whales
A total of 60 common minke whales was sampled. Two situations of struck and lost occurred. The sighting positionsof sampled animals are shown in Figure 3.
Biological examination
Sex ratio, body length and weight
Research items for the biological examination are summarized in Table 1. The sampled animals consisted of 29
males and 31 females. Sex ratio of males was 0.48. Average body length was 5.10 m (max=7.57, min=3.92) for
males and 5.34 m (max=8.07, min=4.06) for females (Table 5). The sexual maturity of animals collected is shown in
Table 6. For males and females 6.9% and 9.7% of the animals sampled in all areas, were sexually mature,
respectively. Among the mature females, one resting, one pregnant and one pregnant & lactating cases wereobserved.
Prey species of common minke whale
Forestomach contents are listed in Table 7. Adult Japanese sand lance (Ammodytes personatus) (46.3%, 19 from 41
animals) and juvenile sand lance (41.5%, 17 from 41 animals) were observed in Area 1, and Japanese anchovy(Engraulis japonicus) and krill (Euphausia pacifica) were observed in two and five animals in Areas 2 and 3,
respectively (Table 8, Figure 5). The maximum net weight of forestomach contents was 27.6 kg, consisting of3

juvenile Japanese sand lance.
Observation of marine debris
Observation of marine debris was made in the stomachs of the 60 common minke whales sampled. One plastic
piece was found in the stomach of an individual, one fishhook in the stomach of a different individual and three
sheets of resins in the stomachs of three different individuals.

DISCUSSION
The spring survey of the coastal component of JARPN II was re-started in Ayukawa in 2012 after one year of noresearch activities in that locality as effect of the 2011 earthquake and tsunami. There were no practical problems in
conducting the survey in Ayukawa in 2012.
In general the weather conditions were good and better that those in previous surveys in Sanriku. This allowed thatthe research area was searched widely and that the sample size of 60 animals could be attained.
The sighting positions of common minke whales in the present survey were concentrated mainly within the Sendai
Bay (Figure 3). Whales outside the Sendai Bay were distributed on the shelf region and along the 100-200m isobathson the slop. The density index (DI) of common minke whales in Area 1 (DI=2.43) was higher than those in Areas 2(DI=0.43) and 3 (DI=0.49), suggesting that common minke whales were concentrated in the Sendai Bay. The DI in
Area 1 in the present survey was slightly higher than those in 2006 (DI=1.83, Goto et al., 2007), 2007 (DI=1.91,
Bando et al., 2008), 2008 (DI=1.57, Yasunaga et al., 2009) and 2009 (DI=2.08, Yasunaga et al., 2010). On the other
hand the DI of Areas 2 and 3 in 2012 were similar to DI in 2010 (DI=0.66, Yasunaga et al., 2011). The surveys from2006 to 2010 were conducted mainly in Area 1.
The sex ratio of males of minke whales collected in the present survey (0.48) was similar to those in 2006 (0.43,
Goto et al., 2007), 2007 (0.37, Bando et al., 2008), 2008 (0.38, Yasunaga et al., 2009), 2009 (0.45, Yasunaga et al.,2010) and 2010 (0.48, Yasunaga et al., 2011). Frequency distribution of body length of common minke whales
collected in the present survey was similar to those in 2009 and 2010 surveys, and their peaks in 2009, 2010 and2012 surveys were shorter than those in 2006, 2007 and 2008 surveys (Figure 6).
These results suggest that the pattern of migration of common minke whales into the Sendai Bay in spring 2012 wassimilar to that before the earthquake and tsunami, although more whales were observed in 2012.
Adult Japanese sand lances were mainly observed in the forestomachs of whales collected from Area 1 while thatJapanese anchovy and krill were observed in forestomachs in whales in Areas 2 and 3 (Table 8). This suggests that
common minke whales in the Sendai Bay and in the outside slope feed on different preys (Figure 5). The first
dominant prey items of the whales collected from Area 1 in the present research (adult sand lance) are in agreementwith those during 2006 and 2010 (Goto et al., 2007; Bando et al., 2008; Yasunaga et al., 2009; Yasunaga et al.,2010; Band et al., 2011) (Figure 7). The second dominant prey items of whales collected from Area 1 were juvenile
Japanese sand lance. This is the same as those in 2008 (Yasunaga et al., 2009), while those in 2009 (Yasunaga et al.,2010) and 2010 (Bando et al., 2011) were krill and those in 2006 (Goto et al., 2007) and 2007 (Bando et al., 2008)4

were Japanese anchovy (Figure 7). The second dominant prey item for common minke whales in Sendai Bay showssome yearly change.

ACKNOWLEDGMENTS
We acknowledge Luis Pastene (ICR), Tomio Miyashita (NRIFSF) and Tatsushi Matsuo (Fisheries Agency ofJapan), for their guidance in the survey design and support. Crewmen, staff of the research station in Ayukawa andthe Association for Community-Based Whaling assisted greatly during the survey. We also thank the members ofthe municipal office of Ishinomaki and Miyagi prefectural office, for their kind assistance.

REFERENCES
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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.

5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.
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.
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
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Scientific Committee, 20pp.
Yasunaga, G., Kato, H., Kishiro, T., Yoshida, H., Ishikawa, H., Goto, M., Tabata, S., Maeda, H., Nakamura, G.,
Inoue, S., Miyakawa, N., Tamura, T., Kumagai, S., Iwasaki, T., Kanaji, Y., Watanabe, H., Hiruta, H., Yamazaki,
K., Yonehara, Y., Oikawa, H. and Onodera, K. 2010. Cruise report of the second phase of the Japanese Whale
Research Program under Special Permit in the Western North Pacific (JARPN II) in 2009 - (Part II) - coastal
component off Sanriku. Paper SC/62/O5 presented to the IWC Scientific Committee, May 2010 (unpublished).
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: theJapanese 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.

6

Table 1. Summary of biological data and samples collected during the 2012 JARPN II coastal survey off
Sanriku.
Samples and data

Number of animals
Male
Female Total

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)

29
29
29
29
29
29
1
29
1
29
29
12
29
29
19
1
0
0
0
0
0
29
29
29
29
24
29
29
29
29
29
29
29
29
4
29
29

*: including a fetus of sex unidentified.

7

31
31
31
31
31
31
0
31
0
31
31
3
31
31
24
0
31
31
31
1
1
1
1
1
31
31
31
24
31
31
31
31
31
31
31
31
5
31
31

60
60
60
60
60
60
1
60
1
60
60
15
60
60
54
1
31
31
31
2*
2*
2*
2*
2*
29
60
60
60
48
60
60
60
60
60
60
60
60
9
60
60

Table 2. Searching days, hours and distances by four sampling vessels in the 2012 JARPN II coastal surveys off
Sanriku
Sampling vessels*
Area

28T

08K

07K

51S

Total

Area 1

Days
Hours
Distance(n.mile)

18
68.8
763.7

20
65.4
685.2

19
78.4
787.1

18
68.2
731.8

75
280.7
2,967.8

Area 2

Days

13

13

15

13

54

Hours
Distance(n.mile)

43.0
480.8

44.2
451.5

43.5
418.1

50.8
527.2

181.5
1,877.6

Days
Hours
Distance(n.mile)

14
42.8
482.6

15
38.8
400.2

11
36.2
356.9

12
40.0
403.0

52
157.8
1,642.7

Area 3

Total

Hours
154.6
148.4
158.1
159.0
620.1
Distance(n.mile)
1,727.1
1,536.9
1,562.1
1,662.0
6,488.1*
28T: Taisho Maru No.28; 08K: Kouei Maru No.8; 07K; Katsu Maru No.7, 51S: Sumitomo Maru No.51.

Table 3. List of cetacean species and number of sightings made by four sampling vessels in the 2012
JARPN II coastal surveys off Sanriku
Area
Area 1

Area 2

Area 3

Total

SpeciesCommon minke whale
Like minke whale
Humpback whale
Killer whale
Fin whale
Common minke whale
Like minke whale
Humpback whale
Killer whale
Fin whale
Common minke whale
Like minke whale
Humpback whale
Killer whale
Fin whale
Common minke whale
Like minke whale
Humpback whale
Killer whale
Fin whale

Primary
Sch.
Ind.
72
74
8
8
20
26
0
0
0
0
8
8
6
6
9
11
2
8
1
1
8
8
6
6
12
18
2
3
1
1
88
90
20
20
41
55
4
11
2
2

8

Secondary
Sch.
Ind.
7
7
2
2
1
1
0
0
0
0
0
0
0
0
1
2
0
0
0
0
0
0
0
0
0
0
0
0
0
0
7
7
2
2
2
3
0
0
0
0

Total
Sch.
79
10
21
0
0
8
6
10
2
1
8
6
12
2
1
95
22
43
4
2

Ind.
81
10
27
0
0
8
6
13
8
1
8
6
18
3
1
97
22
58
11
2

Table 4. Density index of common minke whales in the 2012 JARPN II coastal survey
off Sanriku
Area
SPUE*1
Area 1
0.26
Area 2
0.04
Area 3
0.05
Total
0.14
*1
: No. of primary school sightings per 1 hour searching.

DI*2
2.43
0.43
0.49
1.46

*2

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

Table 5. Body length (m) of common minke whales collected during the 2012 JARPN II coastal survey off Sanriku
Male
Area

Female

mean

S.D.

Min.

Max.

n

mean

S.D.

Min.

Max.

n

Area 1

4.90

0.59

3.92

6.33

24

5.35

1.01

4.13

8.07

27

Area 2

5.85

0.87

5.03

7.05

3

4.90

0.84

4.06

5.73

2

Area 3

6.36

1.22

5.14

7.57

2

5.59

0.33

5.26

5.92

2

Total

5.10

0.82

3.92

7.57

29

5.34

0.97

4.06

8.07

31

Table 6. Sex and sexual maturity status of common minke whales collected by the 2012 JARPN II coastal survey off
Sanriku
Male

FemaleMaturity
Im. R P P&L Uk
Total
Im M Uk Total(%)
Area 1
24 0
0
24
0.0
24
1 1
1
0
27
Area 2
2
1
0
3
33.3
2
0 0
0
0
2
Area 3
0
1
1
0
2
50.0
2
0 0
0
2
Total
27 2
0
29
6.9
28
1 1
1
0
31
Im: Immature, M: Mature, R: Resting, P: Pregnant, P&L: Pregnant and lactating, Uk: Unknown

Area

9

Maturity
(%)
11.1
0.0
0.0
9.7

Table 7. Prey species found in forestomach of common minke whales collected by the 2012 JARPN II coastal survey off
Sanriku (animals with broken stomach were removed)

Area

Prey species

No. ofwhalesobserved

Area 1

41

Area 2

5

Area 3

2

Total

48

Sand lance(adult)Sand lance(juvenile)

Japaneseanchovy

Krill

Number

19

17

5

0

Occurrence (%)

46.3

41.5

12.2

0.0

Number0

0

1

4

Occurrence (%)

0

0

20

80

Number0

0

1

1

Occurrence (%)

0

0

50

50

Number

19

17

7

5

Occurrence (%)

39.6

35.4

14.6

10.4

Table 8. Weight (kg) of forestomach content of common minke whales collected by the 2012 JARPN II coastal survey off Sanriku

Prey species
Area
average

Area 1

range
average

Area 2range
average

Area 3range
average

Total

range

Sandlance(adult)Sandlance(juvenile)

Japaneseanchovy

Krill

6.41
0.21-26.52
0.00
0.0
0.00
0.0
6.41
0.21-26.52

7.09
0.35-27.63
0.00
0.0
0.00
0.0
7.09
0.35-27.63

4.93
0.55-8.56
15.29
15.29-15.29
10.09
10.09-10.09
7.15
0.55-15.29

0.00
0.0
6.02
3.47-12.09
11.03
11.03-11.03
7.02
3.47-12.09

10

Total
6.51
0.21-27.63
7.87
3.47-15.29
10.56
10.09-11.03
6.82
0.21-27.63

40゜N

Area 3
Ayukawa

36゜N

Sendai Bay
138゜E

142゜E

Area 2

Area 1

50 n.miles
100m

200m

Figure 1. Research area of the 2012 JARPN II coastal survey off Sanriku

Figure 2. Cruise tracks by four sampling vessels in the 2012 JARPN II coastal survey off Sanriku

11Figure 3. Sighting positions of common minke whales in the 2012 JARPN II coastal survey off Sanriku (●:sighting
and sampled; ○: only sighting)Figure 4. Sighting position of humpback (〇), killer (★) and fin (▲) whales sighted in the 2012 JARPN II coastal
survey off Sanriku

12Figure 5. Sighting position of common minke whales sampled in the 2012 JARPN II coastal survey off Sanriku bymajor prey species. (○: adult of Japanese sand lance; ●: juvenile of Japanese sand lance; ★: krill; ▲: Japanese
anchovy)

13

Frecuency

12
10
8
6
4
2
0
14
12
10
8
6
4
2
0
12
10
8
6
4
2
0
12
10
8
6
4
2
0
7
6
5
4
3
2
1
0
12
10
8
6
4
2
0

2006
Male (n=26)
Female (n=34)

2007
Male (n=21)
Female (n=36)

2008
Male (n=23)
Female (n=37)

2009
Male (n=27)
Female (n=33)

2010
Male (n=18)
Female (n=27)

2012
Male (n=29)
Female (n=31)

Body length (m)Figure 6. Body length frequency of common minke whales off Sanriku for the period 2006-2012, by sex.

： Sand lance (Ad.)： Sand lance (Juv.)： Japanese anchovy： Krill： Empty

2006

2007

2008

2009

2010

2012

Figure 7. Composition of prey species of common minke whales off Sanriku for the period 2006-2012.

14

Appendix

Report of the coastal prey species survey off Sanriku in 2012
Mitsuhiro Saeki 1 and Genta Yasunaga2
1

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

2135, Japan
2

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

ABSTRACTA prey species survey was conducted in the coastal region off Sanriku, northeastern Japan in spring 2012 as a part of
JARPNII coastal component off Sanriku. The survey was conducted concurrently with a sampling survey ofcommon minke whales. The survey was conducted in April (16 - 21April) and May (14 - 18 May). Four stratified
blocks were surveyed in April (A, B, C and D) and two blocks (B and C) were surveyed in May. Zigzag tracklines
were set in the blocks. A trawler type RV, Takuyo-maru, was used for the survey. Acoustic data were recorded
continuously along the tracklines by a quantitative echosounder. Samplings using a midwater trawl net wereconducted at 12 stations to identify species and body size compositions. Vertical oceanographic conditions wererecorded at 35 stations by using a CTD. Subsurface oceanographic conditions were recorded continuously along the
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 study feeding ecology of cetaceans and ecosystem studies, involving studies of prey
consumption by cetaceans, prey preference of cetaceans and ecosystem modeling. To accomplish the goal, asampling survey of common minke whales (Balaenoptera acutorostrata) and a survey on biomass estimation of
their prey species have been conducted concurrently off Sanriku, Japan as the JARPNII coast component since 2003,
except for 2011 when a large earthquake and tsunami affected greatly the region.
In this document the results of the prey species survey off Sanriku in 2012 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, the prey species survey was conducted in wider area at bottom
depths between 20 m and 200 m from 37º 54’ 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 echo-sounder data (Figure 1). Stratification of blocks was based on bottom depth (20, 40, 100, and 200m) andpolitical boundary (boundary between Miyagi and Fukushima prefecture). Because of logistical constraint andFukushima nuclear accident, only 4 blocks (A, B, C and D ) were surveyed in April, and only 2 blocks (B, C,) were15

surveyed in May in 2012 (Figure 1). A zigzag track line was set in each block. The waypoints of planned tracklines
in each block were shown in Table 1.
The survey was conducted in April (16 - 21 April) and May (14 - 18 May). The same blocks and tracklines weresurveyed in April and May to see whether the distribution patterns of prey species differed between the months. The
survey was conducted during 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). Dataon 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 (Myriax Software Pty. Ltd., Austlaria). A calibration
was carried out in the survey area on 15 April and on 14 May 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.
Trawl sampling was conducted to identify the species and size compositions of targeting echosigns. 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 themouth 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, and lengths and weights were measured. Scale and standard lengths were used for Japanese anchovy(Engraulis japonicus) and sand lance (adult and juvenile, Ammodytes personatus), respectively. Total length fromthe tip of the rostrum to the end of the telson was used for krill (Euphausia pacifica). Some frozen samples weretaken 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 35 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, numberof backscatterings of Japanese anchovy was increased. Backscatterings of juvenile sand lance, adult sand lance andkrill were also observed in May. 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 tocollect a valuable data set. This survey was supported by Fisheries Agency of Japan, Miyagi Prefecture and theInstitute of Cetacean Research. We thank these institutions for their 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.

16

Table 1. Waypoints and planed lines
Block A
Waypoint

LatitudeLongitude

Course(degree)Distance(n.mile)

A1

38

-

15.0

N

141

-

50.5

E

295

11.7

A2

38

-

20.0

N

141

-

37.0

E

58

13.0

B3

38

-

27.0

N

141

-

51.0

E

301

13.7

B4

38

-

34.0

N

141

-

36.0

E

237

13.9

B5

38

-

40.0

N

141

-

52.0

E

-

-

Total

52.3

Block B

B1

37

-

54.0

N

141

-

13.0

E

Course(degree)
291

B2

37

-

58.5

N

140

-

58.0

E

68

14.9

B3

38

-

04.0

N

141

-

15.5

E

294

13.8

Waypoint

LatitudeLongitude

Distance(n.mile)
12.7

B4

38

-

09.5

N

140

-

59.5

E

71

17.0

B5

38

-

15.0

N

141

-

20.0

E

327

6.5

B6

38

-

20.5

N

141

-

15.5

E

76

4.1

B7

38

21.5

N

141

-

20.5

E

-

-

Total

68.9

Block C
Waypoint
C1
C2
C3
C4
C5
C6
C7

Latitude
38
38
38
38
37
37
37

-

15.0
11.0
07.0
03.0
59.0
55.0
54.0

Course Distance(degree) (n.mile)
257
17.4
112
10.6
250
11.4
115
9.6
250
11.4
96
9.9
-

Longitude
N
N
N
N
N
N
N

141
141
141
141
141
141
141

-

37.5
16.0
28.5
15.0
26.0
12.5
25.0

E
E
E
E
E
E
E

Total

70.2

Block D

D1

38

-

15.0

N

141

-

50.5

Course(degree)
E
262

D2

38

-

13.0

N

141

-

33.5

E

121

15.6

D3

37

-

05.0

N

141

-

50.5

E

248

21.6

D4

37

-

57.0

N

141

-

25.0

E

103

13.3

D5

37

-

54.0

N

141

-

41.0

E

-

-

Total

63.7

Waypoint

LatitudeLongitude

17

Distance(n.mile)13.5

Table 2. A summary of the trawl sampling
Station

St-1

St-2

St-3

St-4

St-5

St-6

Block
Date

B
16 Apr.

B
16 Apr.

B
17 Apr.

C
17 Apr.

C
18 Apr.

C
18 Apr.

Time

7:58

11:57

13:30

16:42

8:55

10:20

Latitude38-21N38-08N

37-59N

37-54N

38-03N

38-06NLongitude141-16E

141-06E

141-00E

141-21E

141-16E

141-25E

0m

7.8

7.6

7.9

8.4

7.4

8.2

10 m

7.0

7.1

6.8

7.7

6.9

6.9

6.9

7.1

6.3

30 m

6.7

6.5

40 m

6.5

6.2

50 m

6.5

5.8

Temp (°C) by depth

20 m

6.9

75 m

6.2

5.7

100 m
Bottom

6.3

6.1

6.6

6.3

5.9

5.8

(m)

(16m)

(25m)

(19m)

(74m)

(39m)

(87m)

Trawl sampling

10-20

10-20

10-15

40-60

20-40

40-60

Sand lance

Sand lance

Sand lance

Maurolicus

Sand lance

Krill(juvenile)(juvenile)(juvenile)japonicus(adult)Station

St-7

St-8

St-9

St-10

St-11

St-12

Block
Date

D
20 Apr.

D
20 Apr.

B
14 MayB
15 MayB
17 MayC
18 May

Time

11:18

14:42

13:58

12:51

11:33

9:05

Latitude38-14N

37-57N

38-19N

38-11N

38-02N38-09N

depth (m)Major sampled species

Longitude

Temp (°C) by depth

141-44E

141-26E

141-16E

141-07E

141-10E

141-22E

0m

7.2

8.1

13.5

14.2

13.6

13.6

10 m

6.7

7.3

8.5

11.2

ND

11.5

20 m

6.2

6.0

6.9

7.2

ND

10.4

30 m

5.6

6.3

11.5

40 m

5.9

6.1

10.6

50 m

5.9

6.3

8.2

75 m

5.4

5.6

100 m

5.0

5.5

Bottom

5.0

5.5

6.9

7.0

ND

7.2

(m)

(146m)(105m)

(25m)

(25m)

(25m)

(58m)

Trawl sampling

10-20

40-65

20-25

20-30

15-20

20

Jelly fish

Krill

Sand lance

Sand lance

JapaneseJapanese(juvenile)(juvenile)anchovyanchovy

depth (m)Major sampled species

18Fig. 1. Survey Blocks and planed tracklines in 201219