Cruise Report of the Second Phase of the Japanese Whale
Research Program under Special Permit in the Western
North Pacific (JARPNII) in 2016 - (Part II) - Coastal
component off Sanriku
Genta Yasunaga1), Nobuyuki Ito2), Tatsuya Isoda1), Gen Nakamura3), Ayumi Hirose3), Ryotaro Hayashi3), Kouhei
Yoshii3), Yujin Kim3), Minoru Akagi3), Ken Nakajo3), Futaba Nishimura3), Yuko Asano3), Risa Ozaki3), Taiki
Katsumata3), Ryota Yamada3), Chihiro Koizumi3), Saeko Kumagai2), Hitomi Sato2), Mitsunori Sakaguchi2), Jun
Kanbayashi2) and Hidehiro Kato3)
1) The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
2) 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

Contact E-mail: Yasunaga@cetacean.jp

ABSTRACTThis paper reports the results of the coastal component (off Sanriku) of the Japanese whale research
program under special permit in the western North Pacific (JARPNII) in 2016. The survey was
carried out on the Pacific coast of Japan (the sub-area 7CS) from 9 April to 25 May 2016. The
research took place in coastal waters within 50n.miles from Ayukawa Port in Miyagi Prefecture in
the Sanriku district of Japan using four small-type whaling catcher boats as sighting and sampling
vessels. A total of 5,432.7 n.miles (560.5 hours) was surveyed. Sixteen animals were sampled from
28 schools (28 individuals) of primary sightings of common minke whales.
Density index (the number of primary sightings of schools per 100 n.miles searching) of common
minke whales within and outside of Sendai Bay were calculated as 0.45 and 0.57, respectively, andthose of humpback whales were calculated as 0.41 and 0.50, respectively. The density index ofcommon minke whales within Sendai Bay in 2016 was approximately 30% less than that before
2009, and the same as levels outside of Sendai Bay for 2009-2016, while humpback whales
gradually increased in all research areas after 2008. During the survey, a biopsy experiment was
conducted using the Larsen system for 74 hours ten minutes. One sample was collected in five trials.
Average body length of the whales was 5.75m (min.=4.74m, max.=7.90m, SD=1.21m) for males,
and 5.55m (min.=4.03m, max.=7.98m, SD=1.24m) for females. In males, two of seven individuals(29 %) were sexually mature, and in females, two of nine individuals (22 %) were sexually mature.
Regarding dominant prey species found in the forestomach, three prey species were identified in thestomach contents of 14 individuals. Adult sand lance (50.0%) and Japanese sardine (50.0%) wereobserved from those within Sendai Bay, whereas only Japanese sardine (100.0%) was observed
from those outside of Sendai Bay. Over the last decade, the distribution (individual/m³) of juvenile
Japanese sand lance within Sendai bay in January after 2013 was apparently lower than before 2012,
and was distributed in only the near shore area. The reasons for the decreasing number of sighting
and sampling of common minke whale after 2013 may be caused by increasing numbers of
humpback whales in Sendai Bay and/or decreasing recruitment of sand lance.
BACKGROUND
The full-scale survey of the JARPNII 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 conduct feeding ecology
and ecosystem studies, involving studies of prey consumption by cetaceans, prey preferences of cetaceans andecosystem modeling; ii) to monitor environmental pollutants; iii) to study stock structure. Target species werecommon minke whale (Balaenoptera acutorostrata), Bryde’s whale (B. edeni), sei whale (B. borealis) and sperm
whale (Physeter macrocephalus). The coastal survey component was firstly implemented as a two-year1feasibility study conducted in 2002 and 2003 (Government of Japan, 2004). Coastal research is conducted bysmall-type whaling catcher boats to cover the temporal and spatial gap, which could not be covered by the
Nisshin Maru. After the two years of feasibility surveys, the coastal component of JARPNII was revised to be
conducted twice a year in spring (Sanriku) and autumn (Kushiro), and target species and sample sizes of thecoastal component were set at 120 common minke whales (60 to be sampled in each season).
Following the March 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 JARPNII. This resulted in the reprioritization of the research focus as well as recalculation of sample sizes tobe pursued during the 2014-2016 JARPNII surveys with the results of the three years surveys to be duly utilized
for the establishment of a new research plan (IWC, 2015). As the result of the recalculation, the sample sizes forcommon minke whale was adjusted from 60 to 51 animals in each of the coastal components. These adjustmentsof sample sizes included the allocation of some samples to non-lethal means in order to carry out a comparative
study for verifying the feasibility of non-lethal methods with the intention of taking into account the results ofsuch study in the future research programmes (IWC, 2015).

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) conducted the surveys incooperation with the National Research Institute of Far Seas Fisheries (NRIFSF), the Japan Fisheries Researchand Education Agency, Tokyo University of Marine Science and Technology and the Association forCommunity-Based Whaling.

RESEARCH METHODS
Research area
The research area was set in the coastal waters off Sanriku, within 50 n.miles from the Ayukawa port (Figure 1),
which was same as the previous surveys (Mogoe et al., 2016). This area is included in the middle part of the subarea 7CS of the revised sub areas for the implementation review for the Western North Pacific common minke
whales (IWC, 2012). The research area was further divided into 3 sectors. In order to take account of logisticalconstraints and the accident at the Fukushima nuclear power stations in 2011, the area south of the administrative
boundary between Miyagi and Fukushima Prefecture (37.54°N) has been excluded from the research area since2012.
Research vessels, land station and research period
Four small-type whaling catcher boats, Taisho Maru No. 28 (47.3 GT), Koei Maru No. 8 (32.0 GT), Katsu Maru
No. 7 (32.0 GT) and Sumitomo Maru No. 51 (30.0 GT) conducted the survey for sampling. All of the sampledwhales were landed at the Ayukawa port. Biological surveys and sampling took place at the land station. The
research period was set for 47 days, from 9 April to 25 May in 2016. The prey species surveys were conductedby the trawl-type RV Miyashio (199.0 GT) for four days; 19-20 April and 19-20 May.
Searching and sampling methods
The standard procedure of searching and sampling for the coastal survey off Sanriku were described in Kishiro

2

et al. (2016). In the present survey, the four sighting courses of equal intervals (15 degree) were firstly set in therange of 190˚ to 245˚ from Ayukawa port from 9 to 25 April, and were reset in the range of 90˚ to 210˚ in Area
2 from 26 April to the end of the survey. The small-type whaling catcher boats conducted the research along thecourse from the port until common minke whales were sighted, or the boats arrived at 30 n.miles from the port.
Sighting activities were carried out during the day and the vessels returned to port every night. Searching effort
was conducted within acceptable weather, visibility and sea conditions, by the crew in the top barrel and upper
bridge. On each vessel, one dedicated researcher recorded the cruise tracks, searching time on effort, sea andweather conditions, and the species and the estimated number of whales in the sighted schools. Target species
for the sighting records were all baleen whales, sperm whale and killer whale. All common minke whales sighted
were targeted for sampling, except for cow-calf pairs.
Feasibility research of non-lethal methods
The feasibility research of biopsy and faecal sampling was conducted by the four small- type whaling catcher
boats equipped with a Larsen system and a circle net with 100μm mesh size. During the biopsy experiments,
data on time spent, sea conditions, and visibility were recorded to analyze the influence of these factors on thesampling efficiency. The collected skin samples were put in polyethylene bags and stored at −20°C. Faecal
observation was conducted as much as possible for the whales encountered and chased during the whale
sampling surveys. In case of finding faeces, crews or researchers attempted to collect faecal samples using thecircle net. The sampled faeces were stored in polyethylene bottles at −20°C.
Biological research on common minke whales
For all sampled whales, biological research was conducted at the land station. Research items of this research
are summarized in Table 1. Body length and external proportions of the whale were measured in the same manner
as for the offshore component of JARPNII (Bando et al., 2016). Body weights were measured using a cranescale. Body parts and organ weights of each whale were measured by summing of body parts using an electronic
hanging scale. The maturity of the females was determined by the presence of corpus luteum or corpus albicans
in either ovary. In the case where no corpus luteum or corpus albicans was observed in both ovaries, the female
was categorized as immature. Conversely, if either corpus luteum or corpus albicans was observed in ovaries,
the female was categorized as sexually mature. The ‘mature’ male was defined preliminary based on the weightof one testis being over 290g. Stomach contents were weighed to the nearest 0.1kg for each of the four chambers
including and excluding liquid (Tamura et al., 2016).
Prey species survey
The prey species surveys with oceanography were conducted using the Miyashio. The acoustic data for preyspecies were collected using a quantitative echosounder (EK60). Oceanographic data were recorded by CTD
and EPCS. These results are summarized in the Appendix.
RESULTS
Searching effort by sampling vessels
The cruise tracks of the sampling vessels during the research periods are shown in Figure 2. The survey was
conducted on 47 days, a total of 560.5 hours and 5,432.7 n.miles of effort. Searching effort mainly covered the3area within 30 n.miles from the Ayukawa port. Table 2 shows an outline of the sighting activities. During the 47days of the survey period, the sampling vessels actually conducted searching for only 17 days (37.0 % of thepredetermined days). Out of 30 days of cancellation of the research cruise, the most frequent reason was
unsuitable weather conditions, e.g., a strong wind and fog. The ratio of days when searching was conducted inthis survey was the lowest compared to the former coastal component surveys.
The main sighting courses of small-type whaling catcher boats were changed from the sector of Area 1 to Area
2 in the middle of the research period. In the first half of the research period, the density index of common minke
whales was much lower than previous surveys in Area 1 including Sendai Bay in which most of the research
effort devoted. It is necessary to investigate the extent of distribution of common minke whales outside of Sendai
Bay (Areas 2 and 3). During the second half of the research period, research effort was devoted to the area outsideof Sendai Bay. Consequently, research effort evenly covered the research Area within 30 n.miles.
Sightings and sampling of common minke whales
A total of 28 schools (28 individuals) of common minke whales (Table 3), seven schools (seven individuals) of
like common minke whales, 26 schools (26 individuals) of humpback whales (Table 4), five schools (14individuals) of killer whales and three school (three individuals) of unknown large whales were sighted during
the research period. Density index (DI: the number of primary sightings of schools per 100 n.miles searching)of common minke whales within (Area 1) and outside (Areas 2 and 3) of Sendai Bay were calculated as 0.45
and 0.57, respectively (Table 3), and those of humpback whales were calculated as 0.41 and 0.50, respectively(Table 4). Sixteen common minke whales were sampled during the research period, and there was no struck andlost animals in the sampling process.
Feasibility research activities of non-lethal methods
Biopsy sampling was tried for three common minke whales, and one skin sample with blubber was collectedfrom one animal. For 28 animals encountered during the survey, observation of excretion and vomiting behavior
was conducted. One case of excretion was observed, but faecal sample could not be collected because it was aliquid state. No vomiting behavior was observed.
Sex ratio, body length and maturity
Body length and reproductive status of sampled whales (a total of 16 whales; seven males and nine females) aresummarized in Tables 5 and 6, respectively. Average body length of the whales was 5.75m (min.= 4.74m,
max.=7.90m, SD=1.21m) for males, and 5.55m (min.=4.03 m, max.=7.98m, SD=1.24m) for females (Table 5).
For males, two of seven individuals (29 %) were sexually mature (Table 6), and for females, two of nine
individuals (22 %) were sexually mature (Table 6).
Prey species of common minke whale found in the stomach
Table 7 shows the composition of the dominant prey species obtained from forestomach contents and weight ofstomach contents in common minke whales. Three prey species were identified in the stomach contents of 14 of
16 individuals. Adult sand lance (50.0%) and Japanese sardine (50.0%) were observed in Area 1, whereas only
Japanese sardine (100.0%) was observed in Areas 2 and 3. The weight of stomach contents including inforestomach ranged from between 2.3kg and 27.8kg, and average weight was 17.7kg for all areas.

4Observation of marine debris
Marine debris was observed in the stomach of five animals. All ingested debris were pieces of plastics and/or
vinyl sheets.
DISCUSSION
Distribution and density of whales
In the present survey, common minke whales were sparsely distributed both within and outside of Sendai Bay,
whereas they had been broadly distributed and a few hot spots had been formed within Sendai Bay for the 2008
and 2012 surveys (Figure 3). The density index of common minke whales within Sendai Bay in 2016 wasapproximately under 30% of that before 2009 (Figure 4), and same levels in Areas 2 and 3 for 2009-2016 (Table
3, Figure 5). On the other hand, sighting numbers of humpback whales gradually increased in all research areas
after 2008, while there had been only a few such sightings in 2003-2007 (Table 4). Furthermore, humpback
whales have entered to the central area of Sendai Bay since 2010 (Figure 5). This was the same period of
decreasing sightings of common minke whales, suggesting that recent behavior of humpback whales may affectthe migration of common minke whales within Sendai Bay.
Composition of sexual maturity
Common minke whales sampled within and outside of Sendai Bay consisted of mostly immature whales of both
sexes. This corresponded to the previous surveys (Figure 6).
Composition of prey items
In the present survey, common minke whales fed on adult sand lance and Japanese sardine within Sendai Bay,
while they fed only on Japanese sardine outside of Sendai Bay (Figure 7). The dominant prey species outside
Sendai Bay changed from Japanese anchovy and krill to Japanese sardine after 2014 (Figures 7 and 8). In recent
years, Japanese sardine increasingly appeared in the stomach contents of sei whales sampled offshore (Bando etal., 2017) and common minke whales sampled in the Kushiro region (Yoshida et al., 2017) to replace Japanese
anchovy. On the other hand, sand lance which had been the dominant prey species within Sendai Bay wereobserved in the forestomach of less than 50% of individuals after 2012, whereas the occured in almost allindividual before 2010 (Figures 7 and 8), indicating that availability of sand lance could have decreased forcommon minke whales within Sendai Bay.
Figure 9 illustrates density distribution (individual/m³) of juvenile of Japanese sand lance within Sendai bay inJanuary (Miyagi prefecture Fisheries Technology Institute, 2016), which is a good index of recruitment ofJapanese sand lance in this area. Over the last decade, the indices after 2013 were apparently lower than before
2012, and the species was distributed in only the near shore area. The reasons for this may be disturbance causedby the 2011 Great East Japan Earthquake, because sand bottom area in the central Sendai Bay had been importantfor estivation and spawning (Kobayashi et al., 1995).
The number of sighting and sampling of common minke whale have decreased since 2013. The reasons of thismay be caused by increasing of humpback whales migrating into Sendai Bay and/or decrease of recruitment ofsand lance (e.g. by disturbance of the 2011 Great East Japan Earthquake).

5

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6

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Yamazaki, K., Yonehara, Y., Oikawa, H. and Onodera, K. 2010. Cruise report of the second phase of theJapanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II) in 2009
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and Kato, H. 2013. Cruise Report of the Second Phase of the Japanese Whale Research Program underSpecial Permit in the Western North Pacific (JARPN II) in 2012 - (Part II) - Coastal component off Sanriku
survey. Paper SC/65a/O07 presented to the IWC Scientific Committee, June 2013 (unpublished). 19pp.
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Fukumoto, A., Kitamra, K., Furuyama, Y., Kobayashi, N., Ohta, M., Sato, H., Kumagai, S., Sakamoto, N.
and Kato, H. 2014. Cruise Report of the Second Phase of the Japanese Whale Research Program underSpecial Permit in the Western North Pacific (JARPN II) in 2013 - (Part II) - Coastal component off Sanriku
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Yoshida, H., Shimetani, K., Maeda, H., Nakamura, G., Nakai, K., Inoue, S., Hirose, A., Hayashi, R., Akagi, M.,
Nakajyo, K., Nishimura, F., Asano, H., Fukami, A., Kumagai, S., Kanbayashi, J., Kuwagaki, A., Miyashita,T., Minamikawa, S., Kanaji, Y., Sasaki, H., Yamada, R., Kakinuma, A. and Kato, H. 2017. Cruise report of
the Second phase of the Japanese Whale Research Program under Special Permit in the western North
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the IWC Scientific Committee, May 2017 (unpublished). **pp.

7

Table 1. Summary of biological data and samples collected in the 2016 JARPNII coastal survey off Sanriku
Number of animals
Male Female Total

Samples and data
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
Skin tissues for DNA study of fetus
External measurement of fetus
Eye lens of fetus for age determination
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
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 flipper pigment
Measurement of skull around nasal born

8

7
7
7
7
7
7
0
7
0
7
7
3
7
7
6
0
0
0
0
0
0
0
7
7
7
7
7
7
6
7
1
7
7
7
2
7
7
5
5
3

9
9
9
9
9
9
1
9
1
9
9
3
9
9
7
1
9
9
9
2
2
2
2
2
2
9
9
9
9
9
9
9
2
9
9
9
3
9
9
6
8
5

16
16
16
16
16
16
1
16
1
16
16
6
16
16
13
1
9
9
9
2
2
2
2
2
2
7
16
16
16
16
16
15
16
3
16
16
16
5
16
16
11
13
8

Table 2. Summary of research activities in off Sanriku of JARPNII during the period from 2007 to 2016
Research year
2007
2008
2009
2010
2012
2013
2014
2015
2016

Whole
Actual resarch
research days
days*

46
35
30
47
45
47
47
47
47

26
18
15
27
24
24
18
20
17

Operatingrates (%)**

56.5
52.9
51.7
58.7
54.5
52.2
39.1
43.5
37.0

Total searching effort (n.miles)
Area all7,883.8
5,239.1
4,439.5
8,957.0
6,488.1
7,188.4
5,732.7
6,302.8
5,432.7

Area 1
7,602.2
5,042.2
4,041.2
6,842.5
2,961.5
5,290.5
4,122.5
3,780.1
2,444.4

Areas 2+3
281.7
196.8
398.2
2,114.4
3,526.6
1,897.9
1,610.2
2,522.7
2,988.3

Biopsy sampling
effort (mininute)

3,646
3,272
4,450

*: Actual research day was defined as a total amount of searching distances per day in all small catcher boats more than 100 n.miles**: Acctual research days / Whale research days (%)

After Bando et al. (2008); Yasunaga et al . (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)

Table 3. Searching distances, number of sightings for common minke whales in the JARPNII coastal off Sanriku
in the period 2007-2016
Area allArea 1
total
total
distance primary secondary
distance primary secondaryDIDI(n. miles) sch. ind. sch. ind. sch. ind.
(n. miles) sch. ind. sch. ind. sch. ind.
2007
7883.8 149 153 16 17 165 170 1.89
7602.2 148 152 16 17 164 169 1.95
2008
5239.1
83
85 11 11
94 96 1.58
5042.2 83
85 11 1194
96 1.6520094439.599 100 12 12 111 112 2.23
4041.2 96
97 10 10 106 107 2.38
20108957.05959
3
362 62 0.66
6842.5 5151
3354
54 0.752012
6488.18890
7
795 97 1.36
2961.5 7274
7779
81 2.432013
7188.45454
5
559 59 0.75
5290.5 5050
5555
55 0.95
2014
5732.75050
1
151 51 0.87
4122.5 414111
42
42 0.992015
6302.831
31
2
2
33 33 0.49
3780.1 25250025
25 0.662016
5432.728
28
0
028 28 0.52
2444.4 11
1100
11
11 0.45
After Bando et al. (2008); Yasunaga et al . (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)

Areas 2+3
total
distance primary secondary(n. miles) sch. ind. sch. ind. sch. ind.
281.7
1
1
0
0
1
1
196.8
0
0
0
0
0
0
398.2
3
3
2
2
5
5
2114.48800883526.6 16
16
0
0
16
16
1897.94400441610.29900992522.76
622
882988.3 17
17
0
0
17
17

DI
0.36
0.00
0.75
0.38
0.45
0.21
0.56
0.24
0.57

Table 4. Searching distances, number of sightings for humpback whales in the JARPNII coastal off Sanriku inthe period 2007-2016
Area allArea 1
total
total
DI
distance primary secondary
distance primary secondary(n. miles) sch. ind. sch. ind. sch. ind.
(n. miles) sch. ind. sch. ind. sch. ind.
2007
7883.800
0
0
0
0 0.007602.2
0
0
0
0
0
0
2008
5239.11212
3
3
15 15 0.23
5042.2 12
12
3
3
15
15
2009
4439.52930
5
534 35 0.65
4041.2 28
29
5
5
33
34
2010
8957.05865
4462 69 0.65
6842.5 51
57
2
2
53
59
2012
6488.14155
2
343 58 0.63
2961.5 20
26
1
1
21
27
2013
7188.44449
0
0
44 49 0.61
5290.5 31
34
0
0
31
34
2014
5732.74148
1
2
42 50 0.72
4122.5 41
48
1
2
42
50
2015
6302.82222
1
1
23 23 0.35
3780.1 10
10
1
1
11
11
2016
5432.725
25
1
1
26 26 0.46
2444.4 10
10
1
1
11
11
After Bando et al. (2008); Yasunaga et al . (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)

9

DI
0.00
0.24
0.69
0.75
0.68
0.59
0.99
0.26
0.41

Areas 2+3
total
distance primary secondary(n. miles) sch. ind. sch. ind. sch. ind.
281.7
0
0
0
0
0
0
196.8
0
0
0
0
0
0
398.2
1
1
0
0
1
1
2114.478229103526.6 21
29
1
2
22
31
1897.9 13
15
0
0
13
15
1610.20000002522.7 12
12
0
0
12
12
2988.3 15
15
0
0
15
15

DI
0.00
0.00
0.25
0.33
0.60
0.68
0.00
0.48
0.50

Table 5. Mean body, standard deviation and range of body length of common minke whales sampled in
the 2016 JARPNII costal off Sanriku
Male

Area

Female

Mean

SD

Min.

Max.

n

Mean

SD

Min.

Max.

n

Area 1

4.88

-

4.74

5.02

2

5.34

1.08

4.38

6.89

4

Areas 2+3

6.10

1.28

5.08

7.90

5

5.71

1.46

4.03

7.98

5

All areas

5.75

1.21

4.74

7.90

7

5.55

1.24

4.03

7.98

9

Table 6. Reproductive status of common minke whales sampled in the 2016 JARPNII coastal off Sanriku
Male

FemaleArea
Immature

MatureTotal

Maturity

Immature

Mature(pregnancy)

Total

Maturity

Area 1

2

0

2

0.00

3

1 (1)

4

0.25

Areas 2+3

3

2

5

0.40

4

1(1)

5

0.20

All areas

5

2

7

0.29

7

2(2)

9

0.22

Table 7. Frequency appearance and weight of fore and second stomach contents (kg) of dominant prey species
found in forestomach contents of common minke whales sampled in the 2016 JARPNII coastal off Sanrikua) Frequency of stomach contents (numbers in parentheses are percentage)
Area
Sand lance (Adult)
Area 1
2 (33.3%)
Areas 2+30
All areas
2 (12.5%)*Stomach was broken by harpoon

Japanese sardine
2 (33.3%)
10 (100%)
12 (75.0%)

Unknown*
2 (33.3%)
02 (12.5%)

Total
6
10
16

b) Weight (kg) of stomach cnotents (numbers in parentheses are range)
Area
Area 1
Areas 2+3
All areas

Sand lance (Adult)
15.4 (2.90-27.8)
15.4 (2.90-27.8)

Japanese sardine
19.0 (13.7-24.2)
18.0 (2.3-27.6)
18.1 (2.3-27.6)

10

Total
17.2 (2.9-27.8)
18.0 (2.3-27.6)
17.7 (2.3-27.8)

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 2016 JARPNII coastal survey off Sanriku

11Figure 2. Cruise tracks by four sampling vessels in the JARPNII coastal survey off Sanriku for 2007-2016
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)12

Figure 3. Sighting positions of common minke whales in the 2007-2016 JARPNII coastal surveys off Sanriku (●: sighting and sampled; ○: only
sighting)
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)13

Density Index (schools/100n.mile)

4.0〇: Area 1●: Areas 2 & 3

3.0
2.0
1.0
0.0
2006

2008

2010

2012

2014

2016

Research Year

Figure 4 Yearly changes of density index (schools /100 n.mile) of common minke whales in
Area 1 and Areas 2 and 3 in the JARPNII Sanriku component for 2007-2016
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015,
2016)

14

Figure 5. Sighting positions of humpback whales in the 2008-2016 JARPNII coastal surveys off Sanriku

15Number of sampled whales

60a) Area 1

50
40
30

: mature male: mature female: immature male
: immature female: unknown female

20
10
0

Number of sampled whales

2007 2008 2009 2010 2012 2013 2014 2015 2016
Research year60b) Areas 2 & 3

5040: mature male: mature female: immature male
: immature female

30
20
10
0
2007 2008 2009 2010 2012 2013 2014 2015 2016
Research year

Figure 6. Yearly changes of frequency of sexual maturity in sampled common minke whales
in Area 1 (upper) and Areas 2 and 3 (lower) in the JARPNII Sanriku component for 20072016
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015,2016)
Area 1100%
Occurrence composition (%)
of prey items

Occurrence composition (%)
of prey items

100%
80%
60%
40%
20%
0%

Areas 2 & 3: Sand lance (adult): Sand lance (juvenile): Mackerel: Japanese anchovy: Japanese sardine: Krill: Empty

80%
60%
40%
20%
0%

2007 2008 2009 2010 2012 2013 2014 2015 2016
Research year

2007 2008 2009 2010 2012 2013 2014 2015 2016
Research year

Figure 7. Yearly changes of occurrence composition of dominant prey items found inforestomach of common minke whales sampled in Area 1 (left) and Areas 2 and 3 (right) in
the JARPNII costal surveys off Sanriku during a period of 2007 and 2016
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015,
2016)
16

20E

20E

40E

65S

20E
65S

70S

20E

40E

20E

40E

65S

70S

20E

20E
65S

40E
65S

70S

70S

40E

70S

40E

65S

: Sand lance (adult): Sand lance (juvenile): Mackerel: Japanese anchovy: Japanese sardine: Krill

20E

40E

20E

40E
65S

70S

70S

20E

40E

20E

40E
65S

65S

2014

70S

20E

70S

65S

2013

40E

65S

2010

70S

40E

65S

2012

65S

2009

70S

70S

20E

40E

65S

2008

2007

20E

40E

65S

65S

39N

2015

70S

70S

20E

40E

2016

70S

70S

20E

40E

38N

141E

142E

Figure 8. Sighting position and dominant prey species of common minke whales sampled in the JARPNII coastal survey off Sanriku for 2007-2016
After Bando et al. (2008); Yasunaga et al. (2009-2011, 2013, 2014); Mogoe et al. (2015, 2016)17

Figure 9. Density distribution (individual/m³) of Japanese sand lance (juvenile) in Sendai bay for 2007-2016 based on data from Miyagi Prefecture
Fisheries Technology Institute (2016)18

Appendix
Coastal prey species survey of JARPN II off Sanriku in2016
Mitsuhiro Saeki1), Keiichi Onodera1) and Genta Yasunaga2)
1) Miyagi Prefecture Fisheries Technology Institute, 97-6 Sodenohama, Watanoha, Ishinomaki, Miyagi 986-2135, Japan2) 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 spring2016 as a part of JARPNII coastal component off Sanriku. The survey was conducted concurrently
with a sampling survey of common minke whales. The survey was conducted in April (19, 20 April)and May (19, 20 May). Four stratified blocks were surveyed in April (B, C Survey Blocks) and thetwo blocks (A, 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 trawl net wereconducted at 5 stations to identify species and body size compositions of acoustic backscatterings.
Vertical oceanographic conditions were recorded at 17 stations by using a CTD. Subsurface
oceanographic conditions were recorded continuously along tracklines.
INTRODUCTION
JARPN II is designs to contribute to conservation and sustainable use of marine living resources including
whales in the western North Pacific, especially within Japan’s EEZ (Government of Japan, 2002). One of the
major objectives of JARPNII is to study feeding ecology of cetaceans and ecosystem studies, involving studies
of prey consumption by cetaceans, prey preference of cetaceans and ecosystem modeling. To accomplish thegoal, a sampling survey of common minke whales (Balaenoptera acutorostrata) and a survey on biomass
estimation of their prey species have been conducted concurrently off Sanriku, Japan except for 2011 with theGreat East Japan Earthquake as a component of the JARPNII coast since 2003.
In this document, the results of the prey species survey off Sanriku in 2016 are presented.
MATERIALS AND METHODS
While the sampling survey of minke whales was conducted in the coastal waters within the 50 n.miles (mainly
within 30 n.miles) from Ayukawa, Miyagi prefecture, Japan, the prey species survey was conducted in wider
area at bottom depths between 20 m and 200 m from 37º 54’ N to 38º 40’ N off Sanriku, northeastern Japan, toelucidate 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 1). Stratification of blocks was based on bottom depth (20, 40,
100, and 200m) and political boundary (boundary between Miyagi and Fukushima prefecture). Because oflogistical constraint and Fukushima nuclear accident, only 2 blocks (B, C) were surveyed in April and 2 blocks(A, D) were surveyed in May in 2016(Fig. 1). A zigzag track line was set in each block. The waypoints ofplanned tracklines in each block were shown in Table 1.

19

The survey was conducted in April (19, 20 April) and May (19, 20 May). The survey was conducted during thedaytime from an hour after sunrise to an hour before sunset. Acoustic, trawl and oceanographic surveys wereconducted using a trawler-type RV, “MIYASHIO” (Miyagi prefecture, 199 GT). Data of distribution andabundance of 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
were stored with an aid of software, Echoview (Sonar Data, Australia). A calibration was carried out in thesurvey area on 19 April and on 13 May using the copper sphere technique described in EK 60 manual. Verticaloceanographic 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 heightof 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,
about 40 grams krill was taken. But juvenile sand lance and adult sand lance weren't probably taken
for an escape.
RESULTS
The planned tracklines were almost surveyed by the quantitative echosounder. Trawl was towed at 5 stations. A
summary of the midwater trawl samplings was shown in Table 2. CTD casts were conducted at 17 stations.
In April, backscatterings of juvenile sand lance and adult sand lance were observed in Sendai Bay. In May,
backscatterings of krill were observed off the coast of Sendai Bay. Detailed analysis will be conducted in thelaboratory 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 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.

20

Table 1. Waypoints and planed lines.
Block A
Waypoint

LatitudeLongitude

CourseDistance(degree)(n.mile)

A1

38

-

40.0

N

141

-

52.0

E

247

13.7

A2

38

-

34.5

N

141

-

36.0

E

115

13.0

A3

38

-

29.0

N

141

-

51.0

E

239

11.5

A4

38

-

23.0

N

141

-

38.5

E

130

12.4

A5

38

-

15.0

N

141

-

51.0

E

-

-

Total

50.5

Block B
Waypoint

LatitudeLongitude

CourseDistance(degree)(n.mile)

B1

38

-

20.0

N

141

-

18.0

E

223

8.1

B2

38

-

14.0

N

141

-

11.0

E

291

3.8

B3

38

-

11.0

N

141

-

14.0

E

243

9.8

B4

38

-

06.5

N

141

-

03.0

E

115

10.5

B5

38

-

02.0

N

141

-

15.0

E

244

11.4

B6

37

-

57.0

N

141

-

02.0

E

109

9.2

B7

37

54.0

N

141

-

13.0

E

-

-

Total

52.8

Block C
Waypoint

LatitudeLongitude

CourseDistance(degree)(n.mile)

C1

37

-

54.0

N

141

-

25.0

E

295

9.6

C2

37

-

58.0

N

141

-

14.0

E

67

10.3

C3

38

-

02.0

N

141

-

26.0

E

297

8.8

C4

38

-

06.0

N

141

-

16.0

E

71

12.5

C5

38

-

10.0

N

141

-

31.0

E

290

10.1

C6

38

-

13.5

N

141

-

19.0

E

65

3.5

C7

38

-

15.0

N

141

-

23.0

E

-

-

Total

54.7

CourseDistance(degree)(n.mile)Block D
Waypoint

LatitudeLongitude

D1

37

-

54.0

N

141

-

41.0

E

297

13.3

D2

38

-

00.0

N

141

-

26.0

E

72

19.5

D3

38

-

06.0

N

141

-

49.5

E

293

15.0

D4

38

-

12.0

N

141

-

32.0

E

78

14.9

D5

38

-

15.0

N

141

-

50.5

E

-

-

Total

62.6

21

SC/67a/SPx
Table 2. A summary of the trawl sampling.

Temp (°C) by depth

Station

St-1

St-2

St-3

St-4

St-5

Block

B

C

D

D

A

Date

20 Apr.

20 Apr.

19 May19 May20 May

Time

06:24

09:11

10:17

15:32

7:39

Latitude37-57N

37-53N38-08N

37-58N

38-30NLongitude141-02E

141-26E

141-42E

141-31E

141-48E

0m

10.3

9.9

12.1

12.2

12.5

10 m

10.14

9.77

11.55

11.81

20 m

10.15

9.61

10.90

11.10

10.92

30 m

9.66

9.73

10.52

10.16

40 m

9.75

9.62

10.20

10.08

50 m

9.79

9.53

9.94

10.05

75 m

8.43

9.41

9.57

9.47

100 m

8.27

9.37

9.18

9.18

11.56

Bottom

9.67

8.28

9.27

9.12

7.97

(m)

(21)

(104)

(154)

(136)

(179)

Trawl sampling

10-20

40-50

50-130

25-65

25-35

Cod

Copepoda

krill

krill

Nothing

depth (m)Major sampled species(juvenile)
Jellyfish

krill

22

SC/67a/SPx

Fig. 1. Survey Blocks and planed tracklines in 201623