SC/66a/SP

Cruise Report of the Second Phase of the Japanese Whale
Research Program under Special Permit in the western
North Pacific (JARPNII) in 2014 - Coastal component off
Sanriku
TOSHIHIRO MOGOE1, TAKEHARU BANDO1, NOBUYUKI ITO2, GEN NAKAMURA1, HISOKA HIRUDA2, HIROYUKIOIKAWA1, TATSUYA ISODA1, SAEKO KUMAGAI2, HITOMI SATO2, NAGISA SAKAMOTO2, NAOKO MIYAGAWA3,
MEGUMI TAKAHASHI3, AIKO FUKUMOTO3, MASAYOSHI OTA3, YUSUKE FURUYAMA3, AYUMI HIROSE3, KOUICHIRO
KATO3, RYOUTARO HAYASHI3, KOUHEI YOSHII3, HIDEYOSHI YOSHIDA4, AND HIDEHIRO KATO3
1

The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
Association for Community-Based Whaling, 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
National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Yokohama, Kanagawa, 236-8648, Japan
2

ABSTRACTThis paper reported the outline of the Japanese whale research program under special permit in the western North
Pacific (JARPN II) in 2014 coastal component off Sanriku. This survey was carried out on the Pacific coast ofJapan (the sub-area 7CS) from 26 April to 11 June 2014. Research was set in coastal waters within 50n.miles fromthe Ayukawa Port in Miyagi Prefecture in the Sanriku district of Japan using four small-type whaling catcher boats
as sampling vessels, and all whales sampled were landed on the land research station in Ayukawa. During thesurvey, a total of 5745.1n.miles (571.1 hours) was surveyed, the 51 schools (51 individuals) of common minke
whales were detected and 30 animals were caught. Average body length of the sampled animals was 5.92m(SD=1.11) for males, and 5.78m (SD=1.10) for females. Dominant prey species found in the forestomach were
adult sand lance (58.6%), followed by Japanese sardine (13.8%), juvenile sand lance (10.3%), krill (10.3%), andmackerels (6.9%). Among the five prey species observed in this survey, Japanese sardine and mackerels were thefirst observation in the JARPN II off Sanriku surveys.
KEYWORDS: NORTH PACIFIC; COASTAL WATERS OF JAPAN; FOOD/PREY; ECOSYSTEM;SCIENTIFIC PERMITS; COMMON MINKE WHALEBACKGROUND
The full-scale survey of the JARPN II started in 2002, after conducting two year feasibility studies in 2000 and2001 (Government of Japan, 2002). The objectives of the full-scale research are: i) to study on feeding ecology
and ecosystem studies, involving studies of prey consumption by cetaceans, prey preferences of cetaceans andecosystem modelling; ii) to monitor environmental pollutants; iii) to study on stock structure, particularly forminke whales. Target species are common minke whale (Balaenoptera acutorostrata), Bryde’s whale(Balaenoptera edeni), sei whale (Balaenoptera borealis) and sperm whale (Physeter macrocephalus). In the full
JARPN II plan, the coastal survey component was implemented as a first two-year feasibility study to conduct in2002 and 2003 (Government of Japan, 2004). Coastal research is conducted by small type whaling catcher boats
and has features that cover the temporal and spatial gap, which could not be covered by the Nisshin Maru unit.
After the two years feasibility survey, the coastal component of JARPN II was revised to be conducted twice ayear in spring and autumn. The first revised survey was carried out at off Kushiro in autumn of 2004 (Kishiro etal., 2005). Target species of the coastal component were set at 120 common minke whales (60 common minke
whales will be sampled in each season).
The results of these coastal survey has revealed that common minke whales consume various prey species. In
the off Kushiro survey, krill (Euphausia pacifica), Japanese anchovy (Engraulis japonicus), Pacific saury(Cololabis saira), walleye pollock (Theragra chalcogramma) and Japanese flying squid (Todarodes pacificus)
were consumed by the common minke whales. On the other hand, krill (Euphausia pacifica), Japanese sand lance(Ammodytes personatus) and Japanese anchovy (Engraulis japonicus) were consumed by whales in the off Sanriku
area (Tamura et al., 2009). The findings of different prey species in different year or places suggest the plasticity
of prey preference on common minke whales in the coastal area of Japan.

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Following the March 31, 2014 Judgment of the International Court of Justice (ICJ) in the case Whaling in the
Antarctic (Australia v. Japan: New Zealand intervening), the Government of Japan voluntarily reviewed the stateof JARPN II. Overall research objectives, the research area and research methodology remain the same as thosespecified in the original JARPN II research plan (SC/56/O1). This voluntary review resulted in the reprioritizationof research focus as well as recalculation of sample sizes. The survey concentrated on the study of interactions
between whales and fisheries in the coastal area and interactions among whale species in the offshore area as well
as a contribution to the management of whales. Sampling of sperm and minke whales in offshore component wassuspended because their role in the study of interactions between whales and fisheries in the coastal waters seemed
to be limited. Sei whale sample size of 100 (as in the original plan) of which 10 were studied using only non-lethal
methods. Bryde’s whale sample size of 50 (as in the original plan) of which 25 were studied using only non-lethal
methods. A larger number of Bryde’s whales were allocated to non-lethal methods because they were better studied
than sei whales through the Comprehensive Assessment and the Implementation Review. In costal component,
Minke whale sample size of 114 (57 in each of the spring and autumn season as recalculated with the latest
information) of which 12 (6 in each of the periods) were studied using only non-lethal means. A study for verifying
the feasibility of using non-lethal methods was carried out.
This paper reported the outline of the JARPN II coastal component off Sanriku survey conducted during theperiod from 26 April to 11 June 2014, using four small-type whaling catcher boats as sampling vessels in thenortheast of Japan (the sub-area 7CS).

RESEARCH METHODS
Research area
The research sector was set in the coastal waters off Sanriku, within the 50n.miles from the Ayukawa port, which
was same as the previous surveys (Yasunaga et al., 2014). This sector is included in the middle part of the subarea 7CS of the revised sub areas for the implementation review for western North Pacific common minke whales(IWC, 2012). Research area was divided into 3 sectors. Because of logistical constraint and the accident at the
Fukushima nuclear power stations, the southern boundary line of the research area was set in the administrative
boundary between Miyagi and Fukushima Prefecture (due east of 37.54°N from land).

Research vessels, land station and research period
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No.28 (47.3GT), Koei Maru
No.8 (32.0GT), Katsu Maru No.7 (32.0GT) and Sumitomo Maru No.51 (30.0GT). All of the sampled whales werelanded on the Ayukawa port, and biological survey and sampling was taken place on the land station (the JARPNII
research station) in Ayukawa. Research period was set for 47 days, from 26 April to 11 June, 2014.

Searching and sampling methods
Searching and sampling methods were similar to the past coastal survey off Sanriku (Yoshida et al., 2004). The
research head office was placed in the research station and controlled the sampling vessels during the survey. To
avoid the concentration of sampling location, the research head office arbitrarily determined the searching sector
and direction from the base-point for each sampling vessel every day. The vessels continued to cruise and searchalong the predetermined direction from the base-point until arrived at 30n.miles and then freely cruised in thewaters within the research area. Sighting activities were carried out during the day and the vessels returned to port
every night. Searching effort were conducted within acceptable research condition (weather, visibility and sea
conditions), and placed the crew on the top barrel and upper bridge. In each vessel, one dedicated researcher was
on board and recorded the cruise tracks, searching time on effort, sea weather conditions, and the species andestimated number of whales in the school when the sighting. Target species for sighting record were all baleen
whales, sperm whales and killer whales. And all common minke whales sighted were targeted for sampling, except
for the cow-calf pair. When a sighting consisted of more than one animal, first targeted animal was selectedfollowing the random sampling digits. 50mm explosive harpoon guns equipped with penthrite grenades were usedas the primary killing method. Once a 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 were also targeted
for sampling, if the situation allowed. At the port, the sampled whale was lifted up from the vessel using wire nets
and a crane and transported to the station by an 11 tons freight trailer. At that time, body weight of the whale wasmeasured with the crane scale.

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Practicability survey for collection of biopsy and faecal samples
The survey for collection of biopsy and faecal samples was conducted in this survey. These result were describedin SC/66a/SPxx.

Biological research on common minke whales
All sampled whales were biologically examined by researchers at the research station. Research items of thebiological studies are summarized in Table 3. These items are related to studies on feeding ecology, stock structure,
life history parameters and pollutions. Sexual maturity stage of female was determined by the presence of corpus
luteum and/or corpus albicans in either ovary. The male sexual maturity was determined by the weight of one sideof the testis (290g or more as mature).

RESULTS
Searching effort by sampling vessels
The cruise tracks made by the sampling vessels during the research periods are shown in Figure 1. Searchingefforts were mainly covering at least south-western part of the whole research area. Table 1 shows an outline of
the sighting activities. During the 47 days of predetermined survey periods, the sampling vessels conductedsearching for only 19 days (40% of the predetermined days). Out of 28 days of cancellation in the research cruise,
the most frequent reason was an unsuitable weather conditions, e.g., low atmospheric pressure and fog. The
research engaged ratio in this survey was the lowest through the former surveys of the coastal component. During
the survey, a total of 571.1 hours of searching was conducted and 5745.1n.miles was covered of effort.

Sightings and sampling of common minke whales
Figure 2 showed distribution of sighted and sampled common minke whales by the sampling vessels. A total of
51 schools (51 individuals) of common minke whales consisted of 50 schools (50 individuals) of primary sighting
and 1 school (1 individual) of secondly sighting, were sighted during the survey period. Density index of common
minke whales was calculated as 0.87 for DI (the number of primary sightings per 100n.miles searching effort) and0.09 for SPUE (the number of primary sighting per 1 hour searching effort). Out of 51 schools (51 individuals),
49 schools (49 individuals) were targeted for sampling and 30 individuals were sampled for biological research.
Sampling efficiency (the rate of successful sampling for targeted whales) was 0.61. In the sampling process, there
was no struck and lost animals.

Sighting of other large whales
Two species of baleen whales excluding common minke whales, and one toothed whales were identified during
the research period. Figure 3 plotted sighting position of humpback, fin and unknown large whales, and Table 2
showed the number of sightings for these 4 species including common minke whales during the survey. Humpback
whales were distributed widely along the 100m depth contour line. Five schools/ five individuals of fin whales
were confirmed in less than 20n.miles from Ayukawa port.

Sex ratio, body length and maturity of common minke whales caught
Thirty sampled whales were consisted of 16 males and 14 females (sex ratio of males was 0.53). Body length ofsampled whales was summarized in Table 4. Average body length of the whales were 5.92m (min=4.10m,
max=7.65m, SD=1.11m) for males, and 5.78m (min=4.15m, max=8.09m, SD=1.10m) for females. Immature
whales ranged from 4.10m to 7.53m (4.10-7.53m in males, 4.15-6.45m in females). Mature whales ranged from
7.07m to 8.09m (7.07-7.65m in males, 7.70-8.09m in female respectively). Table 5 summarised reproductive statusof common minke whales sampled. Two whales were pregnant and they had singleton foetuses. Body length ofeach foetus was less than 10cm (sex unknown) and 205cm (female), respectively.

Prey species of common minke whale found in the stomach
The weight of stomach contents was obtained by the same methods used in the offshore component of the JARPN
II. Stomach contents were weighted to the nearest 0.1kg by each of four chambers including and excluding liquid3

SC/66a/SP(Fujise et al., 2002). The weight of stomach contents including liquid in forestomach ranged from between 0.0kg
and 47.3kg, and average weight was 13.8kg (0.54% of body weight; Figure 5). Table 6 provides the compositionof the dominant prey species obtained from forestomach contents in common minke whales. Four prey species
were confirmed in the stomach contents of 29 individuals from 30 samples, and dominant prey species was adultsand lance (58.6%), followed by Japanese sardine (13.8%), juvenile sand lance (10.3%), krill (10.3%) andmackerels (6.9%). Japanese sardine and mackerels were firstly recorded as dominant prey species of common
minke whales sampled in the JARPN II survey off Sanriku.

Observation of marine debris
Marine debris was detected from stomach of 2 matured animals. Ingested debris were two pieces of wood and apiece of plastic. No whale entanglement in fishing gear was recognized by the observation from the body surfaceof all sampled animals.

DISCUSSIONSThe JARPN II coastal component off Sanriku in the spring season of 2014 was conducted using the small-typewhaling catcher boats. This report provided the continued data of biological study in the coastal region off Sanriku.
By restoring and re-establishment of the infrastructure at the port of Ayukawa from the extensive damage causedby the great East Japan earthquake on 11 March 2011, we could use the port as a home port as before. The sampling
vessels conducted the research for 19 days (40.0%) out of 47 days of total survey period. The ratio of researchdays was the lowest in those of the off Sanriku surveys so far. On the whole, the poor weather conditions such as
heavy strong winds or poor visibility reduced sighting efforts. Although the composition and distribution of whale
species were similar to the previous survey, the low value of the DI for common minke whales was seen. Although
DI was not so large, dense distribution area of common minke whales was formed in the Sendai Bay same as thepast surveys. For the reason that all vessels have investigated the same area every day, sighting record is probably
including some duplicated sightings.
In this survey, mean body length of sampled whales was larger than that of the recent 5 years. These differenceswere considered that the difference in migration timing between mature and immature whales. A characteristic of
the biological observation in the present survey is the case that a large foetus (205.5cm in body length) found in
the coast of Sanriku. In the past survey off Sanriku, the largest body length of foetus in the previous survey was
223.0cm in body length sampled in 2005. Kato (1992) suggested difference of conception date between Sea ofJapan (J-stock) and North Pacific and Okhotsk Sea (O-stock) stocks of common minke whales. These large
foetuses collected in spring season would indicate mixing of these stocks.
Figure 4 shows the composition of prey species of common minke whales off Sanriku during the seasons 2003–
2014. Krill and anchovy changed the appearance rate, although the dominant prey species remained as sand lance.
In recent years, juvenile sand lance (less than 10cm) newly appeared as prey species of common minke whales. In
2014, Japanese sardine and mackerels were found firstly as prey species of common minke whales. Both species
were dominant prey species of common minke whales in the areas around Japan during commercial whaling period,
which were from 1960s to late 1980s (Kasamatsu and Tanaka, 1992).
This report provided the continued data of biological and ecological information of common minke whales in
the off Sanriku region.

ACKNOWLEDGEMENTS
The authors show our gratitude Luis A. Pastene, Tsutomu Tamura, Genta Yasunaga, Tomio Miyashita, Toshiya
Kishiro, Takaaki Sakamoto, Yukito Narisawa, Shinichi Tashiro, Ishinomaki City official and Miyagi prefectural
government official for their guidance and implementation of the research. We acknowledge the crew members of
the research vessels and staff of the land station. All research vessels were provided by the Japan small-typewhaling association.

REFERENCES
Government of Japan. 2002. Research plan for cetacean studies in the western North Pacific under special permit(JARPN II). Paper SC/54/O2 presented to the IWC Scientific Committee, June 2002 (unpublished). 115pp.

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Government of Japan. 2004. Revised research plan for cetacean studies in the western North Pacific under special
permit (JARPN II). Paper SC/56/O1 presented to the IWC Scientific Committee, July 2004 (unpublished). 14pp.
International Whaling Commission. 2012. Report of the first RMP intersessional workshop for western North
pacific common minke whales. J. Cetacetan Res. Manage. (Suppl.) 13:413-59.
Kasamatsu, F. and Tanaka, S. 1992. Annual changes in prey species of minke whales taken off Japan 1948-87.
Nippon Suisan Gakkaishi 58(4): 637-651.
Kato, H. 1992. Body length, reproduction and stock separation of minke whales off northern Japan. Rep. int. Whal.
Commn 42: 443-453.
Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., Okamoto, R., Yasui, K., Sato, H., Morita,
Y., Saino, S., Hara, T., Ebisui, T., Kuroishi, H., Nishiwaki, S., and Kawahara, S. 2005. Cruise Report of thecoastal survey on common minke whales off Kushiro, northeast Japan: the 2004 JARPN II survey (Part II) Coastal component. Paper SC/57/O4 presented to the IWC Scientific Committee, june 2005 (unpublished). 37pp.
Tamura, T., Konishi, K., Goto, M., Bando, T., Kishiro, T., Yoshida, H., Okamoto, R. and Kato, H. 2009. Prey
consumption and feeding habits of common minke whales in coastal areas off Sanriku and Kushiro. Paper
SC/J09/JR9 presented to the Expert Workshop to Review Results of JARPN II, 26-30 January 2009
(unpublished). 18pp.
Yasunaga, G., Bando, T., Itoh, N., Nakamura, G., Inoue, S., Miyakawa, N., Kadowaki, I., Takahashi, M.,
Fukumoto, A., Kitamra, K., Furuyama, Y., Kobayashi, N., Ohta, M., Sato, H., Kumagai, S., Sakamoto, N. andKato, H. 2014. Cruise Report of the Second Phase of the Japanese Whale Research Program under Special
Permit in the Western North Pacific (JARPN II) in 2013 - (Part II) - Coastal component off Sanriku survey.
Paper SC/65b/SP03 presented to the IWC Scientific Committee, June 2014 (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:
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 presented to the IWC Scientific Committee, July 2004
(unpublished). 31pp.

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Table 1
Summary of search effort (hours and distances) conducted during the 2014 JARPN II coastal component off Sanriku.
sampling vessels
Total
28T
08K
07K
51S
Days
19
19
19
19
76
Hours
151.0
135.4
145.5
139.2
571.1
Distance(n.miles)
1522.01353.21420.21449.65745.1
Density index of common minke whales was 0.87 for DI (the number of primary sighted schools per 100n. miles) and 0.09 for SPUE (thenumber of primary sighted schools per 1 hour searching).

Table 2
Summary of whale sightings conducted by sampling vessels in whole research area.
Species
First half period (26 Apr - 18 May)
common minke whale
like minke whale
fin whale
humpback whale
unknown large whale
Second half period (19 May - 11 Jun)common minke whale
like minke whale
fin whale
humpback whale
unknown large whale
Total
common minke whale
like minke whale
fin whale
humpback whale
unknown large whale

Primary
Sch.
Ind.

Secondary
Sch.
Ind.

Sch.

Ind.

33
18
2
25
1

33
18
2
29
1

1
2
0
1
0

1
2
0
2
0

34
20
2
26
1

34
20
2
31
1

17
12
3
16
2

17
12
3
19
2

0
1
0
0
0

0
1
0
0
0

17
13
3
16
2

17
13
3
19
2

50
30
5
41
3

50
30
5
48
3

1
3
0
1
0

1
3
0
2
0

51
33
5
42
3

51
33
5
50
3

6

Total

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Table 3
Summary of biological data and samples collected in the 2014 JARPN II coastal survey off Sanriku.
Samples and data
Body length and sex
External body proportion
Photographic record and external body character
Diatom film record
Body scar record
Measurements of blubber thickness (5 points)
Whole body weight
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
Mammary grand; lactation status, measurement and histological sample
Uterine horn; measurements and endometrium sample
Collection of Ovary
Photographic record of foetus
Foetal length and weight
Skin tissues for DNA study of foetus
External measurement of foetus
Muscle, liver, kidney, heart, blubber and skin tissues of foetus
Eye lens of foetus for age determination
Collection 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
Collection of stomach contents for feeding study
Record of external parasites
Earplug 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)
Skull measurement (detail)Measurement of the skull around nasal bone
Content of large intestine
Measurement and sampling of pelvic bone
External measurement of nostril
Measurement of flipper white patch*: including a foetus of sex unidentified; **: including one female foetus.

7

Male
16
16
16
16
16
16
16
16
16
16
16
16
15
16
16
16
16
15
16
15
16
1
16
16
16
6
16
16
0
15
1
0
16
16

Number of animals
Female
Total
14
30
14
30
14
30
14
30
14
30
14
30
14
30
14
30
14
30
14
30
14
30
14
30
8
23
14
14
14
14
14
14
2*
2*
1
1
1
1
2*
16
14
30
14
30
14
30
11
26
14
30
14
29
14
30
2
3
14
30
14
30
14
30
4
10
14
30
14
30
3**
3**
13**
28**
2
3
2**
2**
14**
30**
14**
30**

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Table 4
Mean body length of common minke whales sampled in 2014 JARPN II coastal component off Sanriku.
Period
Mean
5.78
6.01
5.92

First half period (26 Apr - 18 May)
Second half period (19 May - 11 Jun)
Total

SD
0.78
1.31
1.11

Male
Min
4.89
4.10
4.1

Max
7.10
7.65
7.65

N
6
10
16

Mean
5.64
7.70
5.78

SD
0.99
1.1

Female
Min
4.15
7.70
4.15

Max
8.09
7.70
8.09

N
13
1
14

Table 5
Reproductive status of common minke whales sampled in 2014 JARPN II coastal component off Sanriku.
Period

Male
Imm

Mat

First half period
51(26 Apr - 18 May)
Second half period73(19 May - 11 Jun)
Total
12
4
Imm: Immature; Mat: Mature; Preg: Pregnant

Total

Femal
Total

Imm

6

12

Mat
(Preg)
1 (1)

10

30.0

0

1 (1)

1

100.0

100.0

90.9

16

25.0

12

2 (2)

14

100

14.3

53.3

13

Pregnancy Maturity
(%)
(%)
100.0
7.7

Sex ratio(% males)Maturity
(%)
16.7

31.6

Table 6
Number of common minke whales of major prey species found in their forestomach contents sampled by the 2014 JARPN II coastal
component off Sanriku*.
PeriodNo. of whales (%)
Krill
Mackerels

Sand lanceAdult
14(48.3%)

First half period(26 Apr - 18 May)
Second half period3(10.3%)(19 May - 11 Jun)
Total
17(58.6%)*: Excluding one animal with empty stomach.

Japanese sardine

Total

Juvenile3(10.3%)0(0.0%)

1(3.4%)

0(0.0%)

18(62.1%)0(0.0%)

3(10.3%)1(3.4%)

4(13.8%)11(37.9%)3(10.3%)3(10.3%)2(6.9%)

4(13.8%)29(100.0%)

Table 7Weight of forestomach contents of common minke whales by the 2014 JARPN II coastal component off Sanriku*.
PeriodSand lance
Krill
Adult
Juvenile
First half period
Average
12.48
15.6(26 Apr - 18 May) Range(0.95 - 38.75) (12.4 – 18.60)
Second half period Average
5.05
11.46
(19 May - 11 Jun) Range(3.75 – 6.35)(2.50 – 25.14)
Total
Average
11.33
15.6
11.46
Range
(0.95 - 38.75) (12.4 – 18.60) (2.50 – 25.14)*: Excluding 1 animal with empty stomach and 5 animals with stomach broken by harpoon.

8

Mackerels

Japanese sardine

13.73(13.73)13.73(13.73)25.82(13.24 - 47.27)
25.82(13.24 - 47.27)

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Figure 1. Geographical location of research area and track lines of four sampling vessels in 2014 JARPN II coastal component off Sanriku.

Figure 2. Distribution of all sightings of common minke whales sighted by sampling vessels in 2014 JARPN II coastal component off Sanriku.
Closed circle: sighting and sampling school; open circle: only sighting school.

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Figure 3. Distribution of all sightings of fin, humpback and unknown large whales sighted by sampling vessels in 2014 JARPN II coastal
component off Sanriku. Closed triangle: humpback whales; open rhomb: fin whale; open square: unknown large whales. The size of theplot means school size (1 to 3).

100

Percentage

80
60
40
20
0
2003

2005

2006

Sand lance (Juvenile)
Sand lance (Adult)

2007

2008

krill
Japanese anchovy

2009

2010

2012

2013

2014

Japanese sardine
Mackerels

Figure 4. The yearly composition of dominant prey species which were found in the forestomach of common minke whales in JARPN II coastal
component off Sanriku during the seasons 2003–2014. Individuals which have broken forestomach by a harpoon or have empty forestomach
were excluded from the analysis.

10weight of forestomach contemts(% body weight)

SC/66a/SP

1.2
1.1
1.0
0.9
0.8
0.7
0.6
2003

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

survey year
Figure 5. Yearly changes in weight of forestomach contents (% of body weight) of common minke whales during the seasons 2003–2014 in
JARPN II coastal component off Sanriku. It is missing value for the great East Japan earth quake in 2011.

11

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Appendix
Report of the coastal prey species survey off Sanriku in2014
MASAKATSU INADA1, TAKEHARU BANDO2 AND TOSHIHIRO MOGOE2
1

Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi 9862135, 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 2010as a part of JARPNII coastal component off Sanriku. The survey was conducted concurrently with asampling survey of common minke whales. The survey was conducted in May (7- 14May). Four stratified
blocks (A, B, C and D Survey Blocks) were surveyed in May. Zigzag tracklines were set in the blocks. A
trawler type RV, Miyashio, conducted the survey. Acoustic data were recorded continuously along
tracklines by a quantitative echosounder. Samplings using a midwater bongo net were conducted at 5
stations to identify species and body size compositions of acoustic backscatterings. Vertical oceanographic
conditions were recorded at 19 stations by using a CTD. Subsurface oceanographic conditions wererecorded continuously along tracklines.

INTRODUCTION
JARPN II is designed 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 ecology of 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 of common minke whales (Balaenoptera acutorostrata) and asurvey 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 the Great East Japan Earthquake affected
greatly the region.
In this document the results of the prey species survey off Sanriku in 2014 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 conductedin 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 preyspecies based on a stratified random sampling method using echo-sounder data. Four survey blocks (A-D)
was set in 2014. Three blocks (E, F and G) could not conduct the survey due to logistical reason (Fig 1).
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 and Fukushima
nuclear accident, only 4 blocks (A, B, C and D) were surveyed in May (Fig. 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 May (7 - 14 May). The survey was conducted during the daytime from anhour after sunrise to an hour before sunset. Acoustic, bongo net and oceanographic surveys were conductedusing a trawler-type new RV, “Miyashio” (Miyagi prefecture, 199 GT). Data of distribution and abundance

12

SC/66a/SPof the prey species were recorded by a quantitative echosounder, EK60 (Simrad, Norway) with operating
frequency at 38, 120 and 200 kHz. The RV steamed at 9-10 knots along the tracklines. Acoustic data werestored with an aid of software, Echoview (Sonar Data, Australia). A calibration was carried out in the survey
area on 30 April using the copper sphere technique described in EK60 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.
Bongo net sampling was conducted to identify the species and size compositions of targeting echosigns.
The trawl net had a diameter of 0.7 m and a 3 mm liner cod end. Towing speed of the bongo net was 2-4
knots. Catches of bongo net 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 andstandard 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 wasused 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. Bongo net was towed at 5
stations. A summary of the midwater bongo net samplings was shown in Table 2. CTD casts were conducted
at 19 stations. In May, backscattering of adult sand lance were observed in southern Sendai bay andbackscattering of juvenile sand lance were observed in northern Sendai bay and backscattering of krill wereobserved off the coast of Sendai bay. 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 “Miyashio”, Mr. Tatsuo Kanomata, and his crews 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 Pacific under special
permit (JARPN II). Paper SC/54/O2 presented to the IWC Scientific Committee, June 2002
(unpublished). 115pp.

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Table 1. Waypoints and planed lines
Block A
Waypoint

LatitudeLongitude

Course(degree)Distance(n.mile)

A1

38

-

15.0

N

141

-

50.5

E

298

10.7

A2

38

-

20.0

N

141

-

38.0

E

53

9.9

A3

38

-

26.0

N

141

-

48.0

E

318

9.4

A4

38

-

33.0

N

141

-

40.0

E

50

10.8

A5

38

-

40.0

N

141

-

50.5

E

-

-

Total

40.7

Course(degree)Distance(n.mile)Block B
Waypoint

LatitudeLongitude

B1

37

-

54.0

N

141

-

00.0

E

66

10.8

B2

37

-

58.5

N

141

-

12.5

E

304

9.9

B3

38

-

04.0

N

141

-

02.0

E

69

11.4

B4

38

-

08.0

N

141

-

15.5

E

295

10.5

B5

38

-

12.5

N

141

-

03.5

E

79

13.6

B6

38

-

15.0

N

141

-

20.5

E

326

7.8

B7

38

-

21.5

N

141

-

15.0

E

-

-

Total

64.0

Course(degree)Distance(n.mile)Block C
Waypoint

LatitudeLongitude

C1

38

-

15.0

N

141

-

25.0

E

122

3.7

C2

38

-

13.0

N

141

-

29.0

E

259

8.0

C3

38

-

11.5

N

141

-

19.0

E

130

9.3

C4

38

-

05.5

N

141

-

28.0

E

247

10.3

C5

38

-

01.5

N

141

-

16.0

E

131

5.3

C6

37

-

58.0

N

141

-

21.0

E

230

6.2

C7

37

-

54.0

N

141

-

15.0

E

-

-

Total

42.7

Course(degree)Distance(n.mile)Block D
Waypoint

LatitudeLongitude

D1

38

-

15.0

N

141

-

51.5

E

232

13.9

D2

38

-

06.5

N

141

-

37.5

E

102

9.3

D3

38

-

04.5

N

141

-

49.0

E

245

17.8

D4

37

-

57.0

N

141

-

28.5

E

108

9.6

D5

37

-

54.0

N

141

-

40.0

E

-

-

Total

50.6

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Table 2. A summary of the Bongo net sampling
St-1

St-2

St-3

St-4

St-5

Block

B

B

D

A

C

Date

7 May.

8 May.

11 May.

12 May.

14 May.

Time

10:34

12:08

13:32

8:48

9:39

Latitude38-12N

38-04N

37-58N

38-21N38-09NLongitude141-07E

141-02E

141-30E

141-40E

141-24E

0m

13.4

13.9

12.9

8.2

13.7

10m

12.9

12.8

12.6

6.6

13.5

20m

11.0

9.9

13.2

4.6

12.7

30m

9.4

3.8

10.7

40m

8.1

4.4

9.6

50m

7.3

6.2

8.2

75m

3.8

6.6

100m

3.6

6.7

Temp (°C) by depth

StationBottom

8.2

8.4

3.8

6.3

6.3

(m)

(25m)

(25m)

(128m)(138m)(70m)

Jellyfish

Krill

Copepod

Copepod

Trawl sampling

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depth (m)Sand lance
Major sampled species(juvenile)

Copepod15

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Fig. 1. Survey Blocks and planed tracklines in 201416