SC/65a/O06

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 III) - Coastal component off Kushiro.
HIDEYOSHI YOSHIDA1, NOBUYUKI ITO2, TOSHIYA KISHIRO1, TOMIO MIYASHITA1, GENTA YASUNAGA3,
TAKAHIRO HARA2, GEN NAKAMURA4, HIKARI MAEDA4, SATOKO INOUE4, TAICHI TSUTSUMI4, KOZUEISHIDA4, NOZOMI TAMAI4, ICHIRO KADOWAKI4, SYOHEI OKA4, MEGUMI TAKAHASHI4, AIKO FUKUMOTO4,
SAEKO KUMAGAI2, HITOMI SATO2, NAGISA SAKAMOTO2, KAZUYA KITAYAMA4, NOZOMI KOBAYASHI4, AND
HIDEHIRO KATO4.
1

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa-ku, Yokohama,
Kanagawa 236-8648, Japan
2
Association for Community-Based Whaling, Hakata-Kaiseki Building 2F, Hakata-Eki-Higashi, Hakata-ku,
Fukuoka 812-0013, Japan
3
The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan.
4
Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-0075, Japan

Contact e-mail:hideka@fra.affrc.go.jp
ABSTRACTThe tenth survey of the JARPN II coastal component off Kushiro, northeast Japan (middle part of the sub-area
7CN) was conducted from 9 September to 28 October 2012, using four small-type whaling catcher boats as
sampling vessels. Searching and sampling of common minke whales was conducted in coastal waters within 50
nautical miles from Kushiro port. All the whales collected were landed at the JARPN II research station forbiological examination. During the survey, a total of 4,843.7 nautical miles (464.6 hours) was searched and the
95 schools (104 individuals) of common minke whales were encountered. Sightings of 28 schools (35animals) of humpback whales and of two schools (four individuals) of fin whales were also obtained. Fromthe 104 common minke whales, 48 animals were sampled. Average body length of males was 6.09m (SD=0.94,
Range=4.70-7.71m, n=27) and 5.92m (SD=1.32, Range=4.10-8.21m, n=21) for females. Six of the 27 males
were sexually mature and four of the 21 females attained to sexual maturity. Three females were pregnant.
Dominant prey species detected from whale forestomach was walleye pollock (Theragra chalcogramma, 45.8%),
followed by Japanese sardine (Sardinops melanostictus, 31.3%), mackerels (Scomber japonicus andaustralasicus, 6.2%), Japanese anchovy (Engraulis japonicus, 6.2%), Japanese common squid (Todarodes
pacificus, 6.2%), krill (Euphausia pacifica, 2.1%), and unidentified fishes (2.1%). The frequency of whales
feeding on Japanese anchovy was much low in the present survey, in comparison with the previous JARPN II
coastal surveys off Kushiro, where the species was found dominantly (22.0-77.1%). On the other hand, Japanesesardine and mackerels were first detected from stomach of common minke whales since the coastal survey off
Kushiro was started. Japanese sardine was the second dominant species in the present survey. This coincidedwith an increase in catch of commercial fisheries around Kushiro, where Japanese sardine and mackerels weremuch caught after an interval of around 30 years.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; COASTAL WATERS OF JAPAN; FOOD/PREY;ECOSYSTEM; SCIENTIFIC PERMITS.

BACKGROUND
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 survey mainly aimed at i) feeding ecology
and ecosystem studies, involving prey consumption by cetaceans, prey preferences of cetaceans andecosystem modeling, ii) monitoring environmental pollutants in cetaceans and the marine ecosystem, andiii) elucidation of stock structure of whales (Government of Japan, 2002a).
The full-scale JARPN II consists of two survey components, i.e., offshore and coastal components. The
JARPN surveys (1994-1999) and the JARPN II feasibility study (2000-2001) revealed that common minke
whales are widely distributed from offshore waters into coastal waters and feed on various prey species1such as Japanese anchovy, Pacific saury, and walleye pollock (Government of Japan 2002b; Tamura andFujise 2002). Both the waters are very important fishing grounds. Thus, it is thought that the waters are also
very important area for the full-scale JARPN II program. However, the Nisshin Maru research vessels can
not be operated in near shore areas, because of their movement restrictions in shallow waters and thepresence of fishing gear and many boats. Furthermore, the research vessels are not available from autumn
to early spring. In order to cover the temporal and spatial gap of these vessels, in the full-scale JARPN II,
sampling of common minke whales in coastal waters using small-type whaling catcher boats was planned(Government of Japan, 2002a).
In the first two years of the full-scale JARPN II, feasibility studies were conducted, to examine the logistic
aspects of the methodology in the coastal component. The first feasibility study was conducted in coastal
waters off Kushiro in autumn 2002 and the second one was in coastal waters off Sanriku in spring 2003
(Kishiro et al. 2003, Yoshida et al. 2004). Since no logistic problem occurred in the studies, it was
concluded that the coastal survey could be continued as the component of the full-scale JARPN II, using
the same methodology (Government of Japan 2004b, Kato et al. 2004), while the survey was revised to be
conducted twice a year and to collect 60 common minke whales in each of spring and autumn (Governmentof Japan 2004a).
The first revised full-scale survey was carried out in coastal waters off Kushiro in autumn 2004 (Kishiro etal. 2005), then the coastal survey was conducted annually from 2005 to 2008 (Kishiro et al. 2006, 2008,
Yoshida et al. 2007, 2009). In January 2009, the JARPN II review workshop was carried out in Japan underthe IWC/SC, where the progress made in the first six years of the full-scale JARPN II (2002-2007) was
reviewed by the scientific specialists. Because there was no critical problem in the survey methodology, thecoastal components were continued from 2009 to 2011 (Kishiro et al. 2010, 2012, Yoshida et al. 2011),
under the original research plan (Government of Japan 2004a).
Here, we show results of the tenth survey conducted off Kushiro, from 9 September to 28 October 2012.
The present survey, which was authorized by the Government of Japan in compliance with Article VIII of
the International Convention for the Regulation of Whaling, was also conducted under the original researchplan (Government of Japan 2004a). The National Research Institute of Far Seas Fisheries (NRIFSF) of theFisheries Research Agency planned and conducted the survey, under cooperation of the ICR, Tokyo
University of Marine Science and Technology, and the Association for Community-Based Whaling.
MATERIALS AND METHODS
Research area
Research area was set in the same waters where the previous JARPN II coastal surveys off Kushiro wereconducted in 2002-2011 (Kishiro et al. 2003, 2005, 2006, 2008, 2010, 2012, Yoshida et al. 2007, 2009,2011): the area was in coastal waters within 50 nautical miles from Kushiro port, southeastern Hokkaido(Fig. 1). The area is included in the middle part of the sub-area 7CN, established by the IWC.
Research vessels, station, and period
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No. 28 (hereinafterreferred 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 common minke whales collected were landed at the JARPN II researchstation established in the Kushiro port, for biological examination. Research period was set for 50 days,
from 9 September to 28 October, 2010.
Searching and sampling methods
Searching and sampling methods were almost same with those for the first coastal survey off Kushiro in2002 (Kishiro et al. 2003). The research head office established in the research station controlled thesampling vessels during the survey. In order to avoid concentration of searching effort in one area,
searching areas and courses of vessels were determined from weather conditions, whale distribution, andinformation on fishing grounds of coastal fisheries. Searching was carried out in the daytime and thevessels returned to the port every night. A researcher was on board each of the vessels and recorded
sighting and sampling information, e.g., coordinates and time of common minke whale sighting andsampling made, weather conditions, and vessel activity. Sighting information was also recorded for otherbaleen whales and sperm whales. Searching was conducted by crews and researchers from the top barrel

2and upper bridge of vessels running at around 10.5 knots. All common minke whales sighted were targeted
for sampling, except cow-calf pair. When a school consisted of more than 1 animal, an individual was
selected randomly from the school and then collected. Once a vessel caught a whale, it returned to theKushiro port, to transport the animal to the research station. While returning to the port, other common
minke whales encountered were also targeted for sampling, if the situation allowed. At the port, animals
were lifted from the vessel by the crane, using a wire net and then carried to the station by the 11-ton
freight trailer. At that time, body weight of animals was measured using the truck scale.
Biological research on common minke whales collected
All the whales collected were examined by biological researchers at the research station. Research items
are listed in Table 2. These data and samples were taken for studies on feeding ecology, stock structure, life
history and pollutants.
RESULTS
Searching effort made by sampling vessels
Of the 50 days period predetermined for the present survey, sampling vessels could conduct searching only
for 23 days (46.0% of the predetermined days). Other days were not suitable for survey, from bad weather
conditions, e.g., low atmospheric pressure and thick fog. The proportion of searching days in this year was
lowest in all the 10 surveys conducted off Kushiro. Cruise tracks made by the vessels are shown in Figure 2.
Searching distance and time are given in Table 1. Here, searching distance and time are defined as distanceand time recorded under searching activity conducted by crews from the top barrel of the vessels. During
the survey, a total of 4843.7 nautical miles (464.6 hours) was searched.
Sightings made by sampling vessels
All the 95 schools (104 individuals) of common minke whales were sighted during the searching (Table 1,
Fig. 2). No cow-calf pairs were encountered. Excretion and vomit of whales were not observed. Cruise
tracks were widely distributed in coastal waters of Kushiro port, whereas sightings of common minke
whales concentrated on continental slope southwest of Kushiro. Density index of common minke whales
was calculated as 1.71 for DI (the number of primary sightings of schools per 100 nautical miles searching)and 0.18 for SPUE (the number of primary sightings of schools per 1 hour searching). During the searching,
28 schools (35 animals) of humpback whales and two schools (four individuals) of fin whales were also
observed (Table 1, Fig. 3).
Sampling of common minke whales
Of the 104 common minke whales encountered, 48 animals were collected for biological examination. In
the sampling process, struck and lost was not occurred. Sighting positions of animals collected are shownin Figure 2.
Body length, sex ratio, and maturity of animals caught
Research items of biological examination for the 48 animals are summarized in Table 2, with the number ofdata and samples collected. The individuals consisted of 27 males and 21 females. Sex ratio of males to all
animals was 56.3%, which was lowest in comparison with the previous surveys in 2002-2011 (58.3-79.7%).
Average body length was 6.09m (SD=0.94, range=4.70-7.71m) for males and 5.92m (SD=1.32,
range=4.10-8.21m) for females (Table 3). In males, the most dominant length class was 6.0 m (Fig. 4). It
was 4.5 m for females, but frequency of large animals with length of 8 m or more was also high. Ratio of
sexual maturity animals was 22.2% for males (6 of 27 animals) and 19.0% for females (4 of 21). Threemature females were pregnant.
Prey species found from common minke whale forestomach
Stomach contents of the 48 animals collected were examined. Following the same methods used in the
JARPN II feasibility survey conducted in 2001 (Fujise, et al., 2002), stomach contents were weighed to thenearest 0.1 kg, by each of four chambers. Weights were recorded both including and excluding liquid
contents. A small quantity of stomach contents was collected and frozen for laboratory analysis. Weight offorestomach contents including liquid ranged from 1.5 kg to 141.4 kg. Average weight was 21.0 kg.
Forestomach contents found from the 48 whales are listed in Table 5. Empty stomach was not observed.
Dominant prey species detected from whale forestomach was walleye pollock (Theragra chalcogramma,3

45.8%), followed by Japanese sardine (Sardinops melanostictus, 31.3%), mackerels (Scomber japonicus
and australasicus, 6.2%), Japanese anchovy (Engraulis japonicus, 6.2%), Japanese common squid(Todarodes pacificus, 6.2%), krill (Euphausia pacifica, 2.1%), and unidentified fishes (2.1%). The
frequency of whales feeding on Japanese anchovy was much low in the present survey, in comparison withthe previous surveys in 2002-2011 (22.0-77.1%, Fig. 5). Japanese sardine and mackerels were first detectedfrom stomach of common minke whales since the JARPN II coastal component was started off Kushiro.
Japanese sardine was the second dominant species in the present survey. Figure 6 shows major prey species
found in forestomach of common minke whales by their sexual maturity stage. Of 22 animals having
walleye Pollock, all but one were sexually immature. Japanese common squid was taken only by mature
animals, while mackerels were had only by immature whales.
Observation of marine debris
Marine debris was detected from stomach of six animals. Each of three animals swallowed a small fishinghook, which uses for local octopus fishery around Hokkaido, and each of the other three had a small pieceof plastic.
DISCUSSION
In the present survey, bad weather conditions, e.g., low atmospheric pressure and thick fog, often prevented
sampling vessels from research activities. During the 50 days survey period, vessels could conduct
searching for 23 days (46.0% of the predetermined days). This proportion was lowest in all the surveys
conducted off Kushiro. Especially, in September, the proportion was 36.4% (only a third of the period). The
proportion appears to have decreased in recent years.
Diet of common minke whales taken by commercial whaling in Pacific coast of Hokkaido was studied.
From late 1960’s to 1987, mackerel and Japanese sardine were recorded as the major prey species(Kasamatsu and Tanaka, 1992). At that time, the dominant species taken by commercial fisheries aroundthe coast was also mackerel and Japanese sardine. After that, catches of the two species decreased, from adecline in their abundance. In autumn 2012, the Japanese sardine and mackerels were much caught after aninterval of around 30 years, by commercial fisheries conducted around Kushiro. The species were also
detected from stomach of common minke whales collected during the present survey: Japanese sardine andmackerels were first detected from stomach of common minke whales since the JARPN II coastal
component was started off Kushiro (Fig. 5). Japanese sardine was the second dominant species.
Composition of prey species in the whale stomach appears to reflect the species composition in the whale
feeding ground. Common minke whales are thought to be opportunistic feeder and to have the mostabundant or available prey in the ground (Kasamatsu and Hata, 1985). Records of whale stomach contents
are expected to provide information on the dominant species in their feeding ground.
Difference in feeding habit between immature and mature common minke whales collected off Kushiro
was suggested, where walleye Pollock and krill are taken by immature animals more frequently and Pacificsaury and common squid are consumed by mature whales (Kishiro et al. 2009). In the present survey, no
Pacific saury was detected. Of 22 animals having walleye Pollock, all but one were sexually immature (Fig.
6). Japanese common squid were taken only by mature animals. Immature and mature animals fed on
different prey species, even if they were collected at close distance (Fig. 7). Our results also indicate thedifference in feeding habit between immature and mature animals.
ACKNOWLEDGMENTS
We acknowledge Dr. Hiroshi Hatanaka (ICR), Dr. Seiji Ohsumi (ICR), and Messrs. Tatshushi Matsuo andKousei Takekoshi (the Fisheries Agency of Japan), for their guidance in the survey design and support.
Crew of research vessels, staff of the research station in Kushiro, and the Association for Community-Based
Whaling assisted in important aspects of the survey. We also thank the Kushiro fisheries cooperative
association, the municipal office of Kushiro, Hokkaido government Kushiro sub-prefectural office, andHokkaido government office, for their kind assistance.
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Table 1. Searching days, distances, hours, and number of cetacean sightings made during the 2012 JARPN II
coastal survey off Kushiro.
Number of sightings*
PeriodDays Distances Hours
SpeciesPrimary
Secondary
Total(n. miles)(Ind/Sch)(Ind/Sch)（Ind/Sch）
9/9 504843.7
464.6
Common minke whale
88/83
16/12
104/95
Like minke whale
18/18
3/3
21/21
10/28
Fin whale
4/2
0/0
4/2
Humpback whale
33/27
2/1
35/28
Unknown large whale
24/24
0/0
24/24
*: The number probably includes some duplicated sightings made by plural vessels.

6

Table 2. Summary of biological data and samples collected during the 2012 JARPN II coastal survey
off Kushiro.
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 (five points)
Body weight
Skin tissues for DNA analysis
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
FoetusTestis 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)

7

27
27
27
27
27
27
27
27
27
3
27
27
23
2
27
27
27
27
24
27
26
27
27
27
27
27
27
16
27
26

21
21
21
21
21
21
21
21
21
5
21
21
21
21
21
21
1
21
21
21
18
21
21
20
21
21
21
21
21
8
21
21

48
48
48
48
48
48
48
48
48
8
48
48
44
21
21
21
3
27
48
48
48
42
48
47
47
48
48
48
48
48
24
48
47

Table 3. Statistics of body length (m) of common minke whales sampled during the 2012 JARPN II
coastal survey off Kushiro.
PeriodMale
FemaleMean S.D. Min. Max.
n
Mean S.D.
Min. Max. n
9/9 - 9/15
6.15
1.75
4.91
7.38
2
0
9/16 - 9/30

6.00

0.92

4.70

7.69

15

5.40

1.27

4.10

8.10

9

10/1 - 10/15

6.07

1.07

4.77

7.71

6

6.80

1.24

5.22

8.21

8

10/16 - 10/28

6.44

0.74

5.59

7.38

4

5.32

0.66

4.91

6.29

4

Total (9/9 - 10/28)

6.09

0.94

4.70

7.71

27

5.92

1.32

4.10

8.21

21

Table 4. Composition of sex and sexual maturity of common minke whales sampled during the 2012 JARPN II
coastal survey off Kushiro.
PeriodMale
FemaleSex ratio
Maturity
Maturity Pregnancy(% males)Im M Total
Im R P Total
(%)
(%)
(%)*
9/9 - 9/15
1
1
2
50.0
0
100.0
9/16 - 9/30

12

3

15

20.0

8

0

1

9

12.5

100.0

62.5

10/1 - 10/15

5

1

6

16.7

5

1

2

8

37.5

66.7

42.9

10/16 - 10/28

3

1

4

25.0

4

0

0

4

0.0

-

50.0

75.0

56.3

Total (9/9 - 10/28)
21
6
27
22.2
17 1
3
21
19.0
Im: Immature; M: Mature; R: Resting; P: Pregnant; *: Apparent pregnancy ratio.

Table 5. Number of common minke whales by major prey species found in forestomach, sampled during
the 2012 JARPN II coastal survey off Kushiro.
Number of whales (%)
PeriodWalleye Japanese Japanese Mackerels Common
Krill
Unidentified Total
Pollockanchovy
sardinesquid
species
9/9 - 9/15
1(50.0)0(-)
1(50.0)
0(-)
0(-)
0(-)
0(-)
2
9/16 - 9/30

11(45.8)0(-)

11(45.8)0(-)

2(8.3)

0(-)

0(-)

24

10/1 - 10/15

6(42.9)1(7.1)

3(21.4)2(14.3)1(7.1)

0(-)

1(7.1)

14

10/16 - 10/28

4(50.0)2(25.0)0(-)

1(12.5)0(-)

1(12.5)

0(-)

8

Total
(9/9 - 10/28)

22(45.8)3(6.2)

15(31.3)

3(6.2)

3(6.2)

1(2.1)

1(2.1)

48

8

Kushiro

50n. miles

Figure 2. Cruise tracks (upper) and sighting positions (lower) ofcommon minke whales made by sampling vessels during
the 2012 JARPN II coastal survey off Kushiro. Gray circles
are sighting positions of common minke whales collected.
Isobaths are 100m, 200m, and 1000m.

Figure 1. Research area set for the 2012 JARPN II coastal survey off
Kushiro. Isobaths are 100m, 200m, 1000m, and 2000m.

9Figure 3.

Sighting positions of humpback (gray triangle) and fin(white triangle) whales made by sampling vessels during
the 2012 JARPN II coastal survey off Kushiro. Isobaths are
100m, 200m, and 1000m.

Figure 4. Body length frequency of common minke whales sampled during the 2012 JARPN II
coastal survey off Kushiro, with comparison to results of the previous 2002-2011 surveys.

10

Figure 5. Composition of prey species of common minke whales sampled during the 2012 JARPN II
coastal survey off Kushiro, with comparison to results of the previous 2002-2011 surveys.

Figure 6. Sexual maturity and body length frequency of common minke whales by their prey species
found in forestomach in the 2012 JARPN II coastal survey off Kushiro.

11

Figure 7. Sighting positions of common minke whales collected during the 2012 JARPN II coastal survey off
Kushiro, shown by their maturity stage and prey species. Isobaths are 100m, 200m, and 1000m.

12