SC/65b/SP03

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
GENTA YASUNAGA1), TAKEHARU BANDO1), NOBUYUKI ITOH2), GEN NAKAMURA3), SATOKO INOUE3), NAOKOMIYAKAWA3), ICHIRO KADOWAKI3), MEGUMI TAKAHASHI3), AIKO FUKUMOTO3), KAITA KITAMRA3), YUSUKEFURUYAMA3), NOZOMI KOBAYASHI3), MASAYOSHI OHTA3), HITOMI SATO2), SAEKO KUMAGAI2), NAGISASAKAMOTO2), HIDEHIRO KATO3)

1) Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo 104-0055, Japan
2) Association for Community-Based Whaling, 2-5-28, Hakata-eki-higashi, Hakata-ku, Fukuoka, 812-0013, Japan
3) Tokyo University of Marine Science and Technology 4-5-7 Konan, Minato-ku, Tokyo 108-0075, Japan
Contact e-mail:yasunaga@cetacean.jp

ABSTRACTThe 2013 survey of the JARPN II coastal component off Sanriku (northeastern Japan, corresponding to apart of sub-area 7), was conducted from 18 April to 3 June, using four small-type whaling catcher boats
and one echo sounder trawl survey vessel. Sampling of common minke whales was conducted in coastal
waters within 50 n. miles from Ayukawa port in the Sanriku district, and all animals collected were landed
at the JARPN II research station established for biological examination in Ayukawa. A total of 7,188.3
n.miles (709.3 hours) was surveyed and 59 schools (59 individuals) of common minke whales weresighted. A total of 34 animals were sampled. Average body length of the animals was 5.02 m (SD: 1.12,n=17) for males and 5.21 m (SD: 0.60, n=17) for females. The body length of both sexes tended to be
shorter in recent years. Dominant prey species found in the forestomach of common minke whales
collected in the Sendai Bay were juvenile Japanese sand lances, and those collected outside the Sendai Bay
were Japanese anchovies. This suggests that common minke whales in the Sendai Bay and in the outsideslope feed on different preys. Furthermore, common minke whales significantly fed juvenile sand lances in2012 and 2013, with the proportion of adult sand lance decreased in recent years. This result indicates thatfeeding habit of common minke whales in coastal waters off Sanriku changes year by year.

KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; FEEDING ECOLOGY;SCIENTIFIC PERMITS

1

INTRODUCTION
After the two-year feasibility study in 2000-2001, the full-scale survey of the Second Phase of the Japanese Whale
Research Program under Special Permit in the Western North Pacific (JARPN II) was started in 2002. The
objectives of the program are 1) Feeding ecology and ecosystem studies, involving prey consumption by cetaceans,
prey preferences of cetaceans and ecosystem modeling; 2) Monitoring environmental pollutants in cetaceans and themarine ecosystem; and 3) Stock structure of whales (Government of Japan, 2002).
The JARPN II coastal component using small-type whaling catcher boats started in 2002 to complement thetemporal and spatial gap of the offshore components using the Nisshin Maru research vessel. In the original JARPN
II plan, the coastal component was presented as a two-year feasibility study to examine the logistic aspects of themethodology (Government of Japan, 2002). The first feasibility survey was carried out in the coastal waters off
Kushiro in autumn 2002 (Kishiro et al., 2003) and the second feasibility survey was conducted in the coastal waters
off Sanriku district in spring 2003 (Yoshida et al., 2004). In each of the surveys, 50 common minke whales werecaught.
From detailed examination of the logistic aspects of the surveys, it was concluded that no substantial problem
occurred and that the coastal survey could be continued as a component of the JARPN II using same kind of vessels(small-type whaling catcher boats) and methodology (Government of Japan, 2004a, Kato et al., 2004). However, recalculation of required sample size from the survey data suggested that the size should be modified to 60 individuals
in each area/season (Tamura et al., 2004), and from the possible geographical and/or temporal variations of prey
consumption of the whales, the coastal surveys thought to be needed on a yearly bases in each local area
(Government of Japan, 2004b). The revised survey off Sanriku was carried out in spring during 2005 and 2010 year
(Yoshida et al., 2006; Goto et al., 2007; Bando et al., 2008, 2011; Yasunaga et al., 2009, 2010). On March 11 2011
the Ayukawa town, including all research facilities of JARPN II, was destroyed by a large earthquake and tsunami.
In 2011 the spring coastal survey could not be conducted in Ayukawa. Instead the spring survey in 2011 was
conducted in Kushiro. Fortunately the Ayukawa research station was reconstructed and the 2012 survey of the
JARPN II coastal component in spring could be conducted in this locality again (Yasunaga et al., 2013).
Here we report the survey carried out in coastal waters off Sanriku from 18 April to 3 June in 2013. This survey was
authorized by the Government of Japan in compliance with Article VIII of the International Convention for the
Regulation of Whaling. The Institute of Cetacean Research (ICR) planned and conducted the survey in cooperation
with the National Research Institute of Far Seas Fisheries and Tokyo University of Marine Science and Technology,
and the Association for Community-Based Whaling.

MATERIALS AND METHODS
Research area
The research area was set in the same way as in previous surveys off Sanriku (Yasunaga et al., 2013). The researcharea comprised coastal water within 50 n. miles from northeastern part of the Japanese main island, Honshu, (Figure21). The area was divided into Areas 1, 2 and 3 centering on the Ayukawa port (Figure 1). The research area
corresponds to the northern part of sub-area 7, established by IWC (1994).
Whale sampling
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No. 28 (hereinafter referred as
28T; 47.3GT), Koei Maru No. 8 (08K; 32.0GT), Katsu Maru No.7 (07K; 32.0GT), and Sumitomo Maru No.51(51S; 30.0GT). All the animals sampled were landed on the JARPN II research station established at the Ayukawa
port for biological examination. All common minke whales collected were examined biologically by researchers at
the research station (Table 1).

RESULTS
Searching effort
The whale sampling survey was conducted from 18 April to 3 June, 2013. Cruise tracks by the sampling vessels 28T,
08K, 07K and 51S are shown in Figure 2. The tracks covered widely the coastal waters off Sanriku. Searching
distance and time are listed in Table 2, by sampling vessel. Searching distance and time are defined as distance andtime recorded under searching activity conducted from the top barrel of the vessels. Total searching distance andtime made by the four vessels were 7,188.3 n. miles and 709.3 hours, respectively (Table 2).
Sightings
A total of 59 schools (59 individuals) of common minke whales was sighted during the searching (Table 3, Figure 3).
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) the Sendai Bay were calculated as 0.95 and 0.21, respectively (Table 4).
Forty four schools (49 individuals) of humpback whales were sighted during the searching (Table 3).
Sampling of common minke whales
A total of 34 common minke whales was sampled. No situation of struck and lost occurred. The sighting positions ofsampled animals are shown in Figure 3.
Biological examination
Sex ratio, body length and weight
Research items for the biological examination are summarized in Table 1. The sampled animals consisted of 17
males and 17 females. Sex ratio of males was 0.50. Average body length was 5.02 m (max=7.64, min=3.70) for
males and 5.21 m (max=6.14, min=3.84) for females (Table 5, see also Figure 4). The sexual maturity of animals
collected is shown in Table 6. All minke whales for both sexes sampled within the Sendai Bay (Area 1) were
sexually immature, while two minke whales for males sampled outside the bay were mature.
Prey species of common minke whale
Following the same methods used in the JARPN II feasibility survey conducted in 2001 (Fujise et al., 2002),
stomach contents were weighted to the nearest 0.1 kg, in each of the four chambers, for both cases including andexcluding liquid contents. In addition a small sample of forestomach contents was collected and frozen forlaboratory analysis.

3Forestomach contents are listed in Table 7. Juvenile Japanese sand lance (Ammodytes personatus) (54.5%, 12

from 22 animals) and adult Japanese sand lance (27.3%, 6 from 22 animals) and Japanese anchovy (Engraulisjaponicus) (9.1%, 2 from 22 animals) were observed in Area 1, and only Japanese anchovy was observed in
two animals in Areas 2 and 3 (Table 7, Figure 5). The maximum net weight of forestomach contents was 58.77 kg,
consisting of Japanese anchovy (Table 8).
Observation of marine debris
Observation of marine debris was made in the stomachs of the 34 common minke whales sampled. One plastic
piece was found in the third stomach of an individual.

DISCUSSION
Sighting and sampling survey
The present survey was the ninth survey of the JARPN II coastal component in the spring season off Sanriku. The
feasibility survey was conducted in the coastal waters off Sanriku district in spring 2003, and the revised surveys off
Sanriku were carried out in spring during 2005 and 2012 year, except in 2011 (Survey could not be conducted in
Ayukawa in this year because a large earthquake and tsunami).
As same as the previous surveys, bad weather conditions such as low atmospheric pressures, changeable weather
condition and bigger waves often disturbed research activities. Of the total 43 day survey period (from 18 April to 3June), sampling vessels could conduct the research for 28 days or 59.6% of the predetermined days. The total
searching distance made by the four vessels in this survey was the third longest after those in the 2007 and 2010
surveys, and the number of research days in this and 2010 surveys were also longer (Table 9).
The sighting positions of common minke whales in the present survey were concentrated mainly within the Sendai
Bay (Figure 3). Whales outside the Sendai Bay were distributed on the shelf region and along the 100-200m isobathson the slop. The density index (DI) of common minke whales in Area 1 (DI=0.95) was higher than those in Areas 2
and 3 (DI=0.21), suggesting that common minke whales were concentrated in the Sendai Bay (Table 4). The DI in
Area 1 in the present survey was lower than those in 2006 (DI=1.83, Goto et al., 2007), 2007 (DI=1.91, Bando et al.,2008), 2008 (DI=1.57, Yasunaga et al., 2009), 2009 (DI=2.08, Yasunaga et al., 2010) and 2012 (DI=2.43, Yasunaga
et al., 2013). Furthermore, the DI of Areas 2 and 3 in 2013 was lower than DI in 2010 (DI=0.66, Yasunaga et al.,2011) and 2012 (DI in Area 2=0.43; DI in Area 3=0.49, Yasunaga et al., 2013). The surveys from 2006 to 2010 and2012 were conducted mainly in Area 1. In Area 1, DIs in 2010 and 2013 were lower than the others.
The reason why 60 animals could not be sampled in the period of the survey in 2010 and 2013 might be explainedby either bad weather condition, a decrease of sampling opportunities, research design, sampling efficiency anddistribution of whales. The operating ratio (actual survey days / total surbeys) in 2010 and 2013 were similar to thoseof the other surveys (Table 9). The research area was consistently conducted within 30 n.miles in Sendai Bay, Area 1,
whereas was occasionally expanded to off Sendai Bay, Areas 2 and 3 in recent years. In 2010 and 2013, sampling
efficiency ratio (number of sampled whales / number of total sighting whales) were higher than the others (Table 9).
On the other hand, numbers of sighting and density of whales in the years were lower than those in the other years(Table 9). The fishery catch of adult Japanese sand lance at Miyagi prefecture in April 2011 and 2013 were less thanthose in the other years (Table 9). The most obvious explanation is that whales could stay only a short period of time4

in Sendai Bay with few abundance of their prey.
Biological examination
The sex ratio of males of minke whales collected in the present survey (0.50) was similar to those in 2006 (0.43,
Goto et al., 2007), 2007 (0.37, Bando et al., 2008), 2008 (0.38, Yasunaga et al., 2009), 2009 (0.45, Yasunaga et al.,2010), 2010 (0.48, Yasunaga et al., 2011) and 2012 (0.48, Yasunaga et al., 2013). Frequency distribution peaks ofbody length of males of common minke whales collected in the present survey was shorter than those in the previous
surveys, while those of females was similar to those in the previous surveys (Figure 4). Furthermore, body length of
the both sexes of common minke whales tended to be shorter in recent years.
Juvenile Japanese sand lances were mainly observed in the forestomachs of whales collected from Area 1 while thatJapanese anchovy was observed in forestomachs in whales in Areas 2 and 3 (Table 7). This suggests that common
minke whales in the Sendai Bay and in the outside slope feed on different preys (Figure 5). Furthermore, minke
whales significantly fed juvenile sand lances in 2012 and 2013, with the proportion of adult sand lance decreased inrecent years (Figure 6).

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

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7

Table 1. Summary of biological data and samples collected during the 2013 JARPN II coastal survey off
Sanriku.
Samples and data

Number of animals
Male
Female Total

Body length and sex
External body proportion
Photographic record and external character
Diatom film record
Body scar record
Measurements of blubber thickness (5 points)
Detailed measurements of blubber thickness (11 points)
Whole body weight
Body weight by parts
Skin tissues for DNA study
Muscle, liver, kidney, spleen, blubber, heart and ventral groove for various analysis
Urine for various analysis
Muscle, liver, kidney, and blubber for heavy metal analysis
Muscle, liver, kidney, and blubber for organochlorine analysis
Collection of blood plasma
Muscle and vertebra for lipid analysis
Mammary grand; lactation status, measurement and histological sample
Uterine horn; measurements and endometrium sample
Collection of Ovary
Photographic record of fetus
Fetal length and weight
External measurement of fetus
Muscle, liver, kidney, heart, blubber and skin tissues of fetus
Collection of fetus
Testis and epididymis; weight and histological sample
Stomach contents, convenient record
Volume and weight of stomach content in each compartment
Observation of marine debris in stomach
Collection of stomach contents for feeding study
Record of external parasites
Earplug for age determination
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 (43 points)
Measurements of flipper pigment
Collection and measurement of pelvic bone

17
17
17
17
17
17
0
17
0
17
17
5
17
17
13
0
0
0
0
0
0
17
17
17
17
6
17
17
17
17
17
17
17
2
17
17
7
10
5

8

17
17
17
17
17
17
1
17
1
17
17
5
17
17
12
1
17
17
17
0
0
0
0
0
17
17
17
11
17
17
17
17
17
17
17
1
17
17
2
13
2

34
34
34
34
34
34
1
34
1
34
34
10
34
34
25
1
17
17
17
0
0
0
0
0
17
34
34
34
17
34
34
34
34
34
34
34
3
34
34
9
23
7

Table 2. Searching days, hours and distances by four sampling vessels in the 2013 JARPN II coastal surveys off
Sanriku
Sampling vessels*
28T

08K

07K

51S

Total

Days
28
28
28
28
112
Hours
173.5
187.9
164.9
183.0
709.3
Distance(n. mile)
1,828.1
1,885.3
1,601.7
1,873.2
7,188.3*
28T: Taisho Maru No.28; 08K: Kouei Maru No.8; 07K; Katsu Maru No.7, 51S: Sumitomo Maru No.51.
Total

Table 3. List of searching effort and number of sightings made by four sampling vessels in the 2013 JARPN II coastal
surveys off Sanriku
Area
Area 1

Searching distance(n.miles)
5290.4

Areas 2 and 3

1897.9Total

7188.3SpeciesCommon minke whale
Like minke whale
Humpback whale
Common minke whale
Like minke whale
Humpback whale
Common minke whale
Like minke whale
Humpback whale

Primary
Sch.
Ind.
50
50
24
24
31
34
4
4
4
4
13
15
54
54
28
28
44
49

Table 4. Density index of common minke whales in the 2013 JARPN II coastal survey
off Sanriku
Area
SPUE*1
Area 1
0.095
Areas 2 and 3
0.022
Total
0.076
*1
: No. of primary school sightings per 1 hour searching.

DI*2
0.95
0.21
0.75

*2

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

9

Secondary
Sch.
Ind.
5
5
1
1
0
0
0
0
0
0
0
0
5
5
1
1
0
0

Total
Sch. Ind.
55
55
25
25
31
34
4
4
4
4
13
15
59
59
29
29
44
49

Table 5. Body length (m) of common minke whales collected during the 2013 JARPN II coastal survey off Sanriku
Male
Area

Female

mean

S.D.

Min.

Max.

n

mean

S.D.

Min.

Max.

n

Area 1

4.69

0.69

3.70

5.73

15

5.21

0.60

3.84

6.14

17

Areas 2 and 3

7.52

0.13

7.39

7.64

2

-

-

-

-

-

Total

5.02

1.12

3.70

7.64

17

5.21

0.60

3.84

6.14

0

Table 6. Sex and sexual maturity status of common minke whales collected by the 2013 JARPN II coastal survey
off Sanriku
Male

FemaleArea

Maturity
Im M
Total
Im. R P(%)
Area 1
15 0
15
0.0
17
0 0
Areas 2 and 3
0
2
2
100.0
0
0 0
Total
27 2
17
11.8
17
0 0
Im: Immature, M: Mature, R: Resting, P: Pregnant, P&L: Pregnant and lactating

P&L

Total

0
0
0

17
0
17

Maturity
(%)
0.0
0.0
0.0

Table 7. Prey species found in forestomach of common minke whales collected by the 2013 JARPN II coastal survey off
Sanriku (animals with broken stomach were removed)
Prey species

No. ofwhalesobserved

Area

Area 1

22

Areas 2 and 3

2

Total

24

Sand lance(adult)Sand lance(juvenile)

Japaneseanchovy

Empty

Number

6

12

2

2

Occurrence (%)

27.3

54.5

9.1

9.1

Number0

0

2

0

Occurrence (%)

0

0

100

0

Number

6

12

4

2

Occurrence (%)

25.0

50.0

16.7

8.3

10

Table 8. Weight (kg) of forestomach content of common minke whales collected by the2013 JARPN II coastal survey off Sanriku

Prey species
Area
average

Area 1

range
average

Areas 2 and 3

range
average

Total

range

Sand lance(adult)Sand lance(juvenile)

Japaneseanchovy

9.87
1.15-24.27
9.87
1.15-24.27

6.90
0.18-36.25
6.90
0.18-36.25

2.11
0.6-3.62
47.37
35.97-58.77
24.74
0.6-58.77

Table 9. The comparison among the indice related to sampling of common minke whales during from 2003 to 2013 in JARPN II surveys.
Year

Number ofsampledwhalesSearching
distance(n.miles)Operating
rate*

2003

50

3,834

0.72

Number of sightings
Primary

Total

Sch.

Ind.

Sch.

Ind.

157

161

184

188

Dnsity Index(sch./100 n.mile)

Sampling
efficiency
ratio**

Fisheries catch (t) ofadult sandlances in
Miyagi pref. in April

4.09

0.27

1,772
2,944
977
2,026
1,595
993
1,265
319
1,052
1,056
664

2004
2005

60

5,246

0.66

168

171

202

205

3.20

0.29

2006

60

6,340

0.72

116

118

139

143

1.83

0.42
0.33

2007

57

7,794

0.63

149

153

166

171

1.91

2008

60

5,276

0.69

83

85

94

96

1.57

0.63

2009

60

4,756

0.57

99

100

111

112

2.08

0.54

2010

45

8,957

0.64

59

59

62

62

0.66

0.73

2011
2012

60

6,488

0.62

88

90

95

97

1.36

0.62

2013

34

7,188

0.60

54

54

59

59

0.75

0.58

*: Actural survey days/ Total surveys**: Number of sampled whales / number of total sighting whales

11Area 3

Area 1

Area 2

Figure 1. Research area of the 2013 JARPN II coastal survey off Sanriku

Figure 2. Cruise tracks by four sampling vessels in the 2013 JARPN II coastal survey off Sanriku

12Figure 3. Sighting positions of common minke whales in the 2013 JARPN II coastal survey off Sanriku (●:sighting
and sampled; ○: only sighting)

13

8
6
4
2
0

Frecuency

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

2013
Male (n=17)
Female (n=17)

2012
Body length (m)Male (n=29)
Female (n=31)

Body length (m)Male (n=18)
Female (n=27)

2010

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

12
10
8
6
4
2
0
14
12
10
8
6
4
2
0
12
10
8
6
4
2
0

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

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

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

Body length (m)Figure 4. Frequency of body length of common minke whales sampled in the 2013 JARPNⅡ coastal survey off
Sanriku by sex

14

Figure 5. Sighting position of common minke whales sampled in the 2013 JARPNⅡ coastal survey off Sanriku bymajor prey species. (○: adult of Japanese sand lance; ●: juvenile of Japanese sand lance;▲: Japanese anchovy)

2003

2005

2006

2007

2009

2010

2012

2013

2008

Figure 6. Occurrence composition of prey items found in forestomachs of common minke whales sampled in the
JARPN II costal surveys off Sanriku during a period of 2003 and 2013.

15

Appendix

Report of the coastal prey species survey off Sanriku in2013
Takeshi Onodera 1) 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 spring 2010 as a part of
JARPNII coastal component off Sanriku. The survey was conducted concurrently with a sampling survey ofcommon minke whales. The survey was conducted in April (16 - 24April) and May (21- 23May). Four stratified
blocks (A, B, C and D Survey Blocks) were surveyed in April and two blocks (B and C Survey Blocks) weresurveyed in May. Zigzag tracklines were set in the blocks. A trawler type RV, Takuyo-maru, conducted the survey.
Acoustic data were recorded continuously along tracklines by a quantitative echosounder. Samplings using a
midwater trawl net were conducted at 8 stations to identify species and body size compositions of acoustic
backscatterings. Vertical oceanographic conditions were recorded at 33 stations by using a CTD. Subsurface
oceanographic conditions were recorded continuously along tracklines.
INTRODUCTION
JARPN II is designed to contribute to conservation and sustainable use of marine living resources including whalesin the western North Pacific, especially within Japan’s EEZ (Government of Japan, 2002). One of the major
objectives of JARPNII is to study feeding ecology of cetaceans and ecosystem studies, involving studies of prey
consumption by cetaceans, prey preference of cetaceans and ecosystem modeling. To accomplish the goal, asampling survey of common minke whales (Balaenoptera acutorostrata) and a survey on biomass estimation of
their prey species have been conducted concurrently off Sanriku, Japan as the JARPNII coast component since 2003,
except for 2011 when the Great East Japan Earthquake affected greatly the region.
In this document the results of the prey species survey off Sanriku in 2013 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 atbottom depths between 20 m and 200 m from 37º 54’ N to 38º 40’ N off Sanriku, northeastern Japan, to elucidate the
distribution and abundance of main prey species. Seven survey blocks (A-G) have been set within the survey block
since 2005 for the purpose of biomass estimation of prey species based on a stratified random sampling method
using echo-sounder data. Four survey blocks (A-D) was set in 2013. 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, and16

200m) and political boundary (boundary between Miyagi and Fukushima prefecture). Because of logisticalconstraint and Fukushima nuclear accident, only 4 blocks (A, B, C and D ) were surveyed in April, only 2 blocks (B,C,) were surveyed in May in 2013 (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 April (16 - 24 April) and May (21 - 23 May). Same blocks and tracklines weresurveyed in April and May to see whether occurrence patterns of prey species were different between the months.
The survey was conducted during the daytime from an hour after sunrise to an hour before sunset. Acoustic, trawl
and oceanographic surveys were conducted using a trawler-type RV, “Takuyo maru” (Miyagi prefecture, 120 GT).
Data of distribution and abundance of the prey species were recorded by a quantitative echosounder, EK500 (Simrad,
Norway) with operating frequency at 38, 120 and 200 kHz. The RV steamed at 9-10 knots along the tracklines.
Acoustic data were stored with an aid of software, Echoview (Sonar Data, Australia). A calibration was carried out inthe survey area on 15 April and on 20 May using the copper sphere technique described in EK 500 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 height of themouth of the net were monitored with a net recorder. Towing speed of the trawl net was 2-4 knots. Catches of trawl
were identified to the species level and weighed aboard the vessel. For the major species, a sample of 100 animals
was taken, and lengths and weights were measured. Scale and standard lengths were used to Japanese anchovy(Engraulis japonicus) and sand lance (adult and juvenile, Ammodytes personatus), respectively. Total length fromthe tip of the rostrum to the end of the telson was used for krill (Euphausia pacifica). Some frozen samples weretaken for further analysis in the laboratory.
RESULTS
The planned tracklines were almost surveyed by the quantitative echosounder. Trawl was towed at 8 stations. A
summary of the midwater trawl samplings was shown in Table 2. CTD casts were conducted at 33 stations.
Occurrences of prey species were different between April and May. In April, backscatterings of juvenile sand lance
and krill were observed while these of adult sand lance and Japanese anchovy were rarely observed. In May, numberof backscatterings of Japanese anchovy was increased. Backscatterings of juvenile sand lance, adult sand lance andkrill were also observed in May. Detailed analysis will be conducted in the laboratory and the results will bepresented in the near future.
ACKNOWLEDGEMENT
We would like to thank the captain of RV “Takuyo-Maru”, Mr. 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 the
Association for Community-Based Whaling. 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.

17

Table 1. Waypoints and planed lines
Block A
Waypoint

LatitudeLongitude

Course(degree)Distance(n.mile)

A1

38

-

15.0

N

141

-

50.5

E

308

13.0

A2

38

-

23.0

N

141

-

37.5

E

57

12.7

A3

38

-

30.0

N

141

-

51.0

E

302

13.3

A4

38

-

37.0

N

141

-

36.5

E

76

12.1

A5

38

-

40.0

N

141

-

51.5

E

-

-

Total

51.1
Distance(n.mile)9.4

Block B

B1

37

-

54.0

N

141

-

00.5

E

Course(degree)
75

B2

37

-

56.5

N

141

-

12.0

E

296

12.7

B3

38

-

02.0

N

140

-

57.5

E

72

15.8

B4

38

-

07.0

N

141

-

16.5

E

299

12.5

B5

38

-

13.0

N

141

-

02.5

E

78

14.9

B6

38

-

16.0

N

141

-

21.0

E

356

5.5

B7

38

21.5

N

141

-

20.5

E

-

-

Total

70.8

Waypoint

LatitudeLongitude

Block C
Waypoint
C1
C2
C3
C4
C5
C6
C7

Latitude
38
38
38
38
38
37
37

-

15.0
13.0
09.0
05.0
01.0
57.0
54.0

Longitude
N
N
N
N
N
N
N

141
141
141
141
141
141
141

-

32.5
33.0
17.0
27.5
15.5
25.0
12.5

E
E
E
E
E
E
E

Course(degree)
169
252
116
247
118
180
-

Distance(n.mile)
2.0
13.2
9.2
10.3
8.5
3.0
-

Total

46.2

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

LatitudeLongitude

D1

38

-

15.0

N

141

-

50.5

E

258

14.1

D2

38

-

12.0

N

141

-

33.0

E

119

16.3

D3

38

-

04.0

N

141

-

51.0

E

249

22.0

D4

37

-

56.0

N

141

-

25.0

E

99

12.8

D5

37

-

54.0

N

141

-

41.0

E

-

-

Total

65.2

18

Table 2. A summary of the trawl sampling
Station

St-1

St-2

St-3

St-4

St-5

St-6

Block
Date

B
16 Apr.

B
16 Apr.

B
18 Apr.

B
18 Apr.

C
20 Apr.

C
20 Apr.

Time

8:40

11:01

11:17

13:38

8:35

13:16

Latitude38-14N

38-10N

38-03N

37-57N

38-11N

37-58NLongitude141-15E

141-09E

141-01E

141-09E

141-28E

141-21E

Temp (°C) by depth

0m

8.9

9.0

9.2

9.9

8.3

8.7

10 m

8.4

8.1

8.3

9.7

8.0

8.4

20 m

8.2

7.6

7.9

9.6

7.6

7.8

30 m

7.7

8.2

6.6

6.6

40 m

7.0

6.8

50 m

7.0

7.0

75 m

6.8

100 m
Bottom

7.7

7.6

7.9

8.2

6.5

6.4

(m)

(37m)

(28m)

(21m)

(32m)

(70m)

(82m)

25-35

10-20

15-20

10-15

70

60

Sand lance

Sand lance

Sand lance

Sand lance

Maurolicus

Krill(juvenile)(juvenile)(juvenile)(juvenile)japonicus

Station

St-7

St-8

Block
Date

D
23 Apr.

B
21 May.

Time

13:31

11:02

Trawl sampling
depth (m)Major sampled species

Temp (°C) by depth

Latitude37-59N

38-10NLongitude141-34E

141-09E

0m

8.8

16.4

10 m

8.6

11.4

20 m

8.5

10.3

30 m

9.5

40 m

6.0

50 m

4.5

75 m

6.0

100 m

6.2

Bottom

6.0

8.5

(m)

(136m)

(27m)

20-60

20-25

Krill

Jelly fish

Trawl sampling
depth (m)Major sampled species

19Fig. 1. Survey Blocks and planed tracklines in 201320