SC/65a/O03

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 I) – Offshore component –TAKEHARU BANDO 1), TOSHIHIRO MOGOE 1), TATSUYA ISODA 1), ATSUSHI WADA 1), MASAKATSU MORI 2),
MASAOMI TSUNEKAWA 2), KAZUU TAMAHASHI 2), RYUICHIRO MORIYAMA 2), NAOKO MIYAKAWA 3), ICHIROKADOWAKI 3), HIKARU WATANABE 4), AND TOMOYUKI OGAWA 2)
1) Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan,2) Kyodo Senpaku Co. Ltd., 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan,
3) Tokyo University of Marine Science and Technology, Faculty of Marine Science, 4-5-7, Konan, Minatoku, Tokyo, 108-8477, Japan
4) National Research Institute of Far Seas Fisheries, Fisheries Research Agency, 2-12-4 Fukuura,
Kanazawa-ku, Yokohama, Kanagawa 236-8648, Japan
Contact e-mail: bando@cetacean.jp
ABSTRACTThe eleventh cruise of the full-scale Second Phase of the Japanese Whale Research Program under Special
Permit in the Western North Pacific (JARPN II) -offshore component- was conducted in sub-areas 7, 8 and
9 of the western North Pacific. There were three main research components: whale sampling survey,
dedicated sighting survey and whale sighting and prey survey. A total of five research vessels was used:
two sighting/sampling vessels (SSVs) (whale sampling survey component), one research base vessel(Nisshin Maru, NM) (whale sampling survey component), one whale sighting and prey survey vessel(SPV) (whale sighting and prey survey component) and three dedicated sighting vessels (SVs) (dedicatedsighting survey component). The whale sampling survey was carried out from 16 May to 3 August 2012. A
total of 2,326n.miles was surveyed in a period of 69 days by the SSVs. A total of 86 common minke, 304sei, 86 Bryde’s, 218 sperm, five blue, 61 fin, 35 humpback and two right whales were sighted by the SSVs
and NM. A total of 74 common minke, 100 sei, 34 Bryde’s and three sperm whales was sampled by the
SSVs. All whales sampled were examined on board of NM. In May and June, common minke whales fed
mainly on Japanese anchovy near Shiriya-zaki, off northernmost region of Honshu, and walleye pollock offeastern Hokkaido, respectively. This indicates geographical differences of prey species in continental shelfregion of sub-area 7. Sei whales fed mainly on Japanese anchovy, mackerels and copepods from June toJuly in sub-areas 8 and 9. Bryde’s whales fed mainly on Japanese anchovy and krill in sub-areas 8 and 9 inJuly. Dominant prey species in the stomach of the sperm whales were various kinds of squids, which
inhabit in mid- and deep-waters. The dedicated sighting surveys were carried out from 17 May to 30 Junein sub-area 7, 20 August to 3 October in the area between 30°N to 40°N and 140°E to 170°E (this area
contains sub-areas 7, 8 and 9), 14 September to 1 October in sub-area 7. A total of 2,728, 5,292 and
728n.miles was surveyed during each survey by the SVs, respectively. The whale sighting and prey surveys
were carried out from 28 July to 15 August in 2012. Surveys were conducted with SSVs and NM in a partof sub-areas 8 and 9. The purpose of this survey in this year was to estimate habitat and prey preference ofBryde’s whale and habitat preference of sei whale in relation to oceanographic and ecosystem informationin those sub-areas in summer. Data obtained in this research will be used in the elucidation of the role ofwhales in the marine ecosystem through the study of whale feeding ecology in the western North Pacific.

KEYWORDS: PACIFIC OCEAN; COMMON MINKE WHALE; BRYDE’S WHALE; SEI WHALE;
SPERM WHALE; FOOD/PREY; MONITORING; SCIENTIFIC PERMIT

1INTRODUCTION
After the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN)
was completed in 1999, the second phase of Japanese Whale Research Program under Special Permit in theWestern North Pacific (JARPNII) was started in the 2000 summer season as a two-year feasibility study.
Based on the success of the feasibility study (Government of Japan, 2002a) and the increasingly strong
support from international fisheries organizations, including FAO, for research to improve multi-species
approaches to management, JARPN II started as a full-scale research program in 2002. The full-scale study
aimed i) to evaluate the feeding ecology and ecosystem studies, ii) to monitor environmental pollutants incetaceans and the marine ecosystem and iii) to elucidate the stock structure (Government of Japan, 2002b).
The full-scale JARPN II plan involves two survey components: the ‘offshore’ survey, which is covered by
the Nisshin Maru research unit and two ‘coastal’ surveys (Sanriku and Kushiro), which are covered bysmall type catcher boats. The coastal component was necessary to cover the temporal and spatial gaps,
which could not be covered by the Nisshin Maru unit (Government of Japan, 2002b).
The research area of the offshore component is set in sub-areas 7, 8 and 9, and the target species andsample sizes for the lethal component of the research were set as follows: 100 common minke whales; 100
sei whales, 50 Bryde’s whales and 10 sperm whales (Government of Japan, 2002b). The survey wascomposed of three main components: whale sampling survey, dedicated sighting survey and whale sighting
and prey surveys.
In January 2009 IWC/SC conducted the Expert Workshop to review the ongoing JARPN II Programme(IWC, 2009) for the first period (2002-2007). The results presented on the three main objectives of JARPN
II were discussed by an Experts Panel. Constructive discussions were conducted and somerecommendations were offered by the EP. Some of those recommendations were already responded by
Japanese scientists (Pastene, et al., 2010).
This paper reports the eleventh full-scale survey of the JARPN II -offshore component-, carried out in 2012.

MATERIALS AND METHODS
Whale sampling survey
Research area
Sub-areas 7, 8 and 9, excluding the EEZ zones of foreign countries, comprised the research area (Figure 1).
Research vessels
Three research vessels were used. The research base vessel Nisshin Maru (NM: 8,044GT) commanded theresearch and was the platform for biological examination of whale samples and processing of by-products.
The Yushin Maru (YS1: 720GT) and Yushin Maru No.2 (YS2: 747GT) were used as the sighting/sampling
vessels (SSVs), which conducted sighting activities, sampling of targeted whale species and various
experiments and observations.
Methods for setting cruise track line and sighting procedure
Track lines and allocation of vessels were made as in previous JARPN and JARPN II surveys (Fujise et al.,
1995, 1996, 1997, 2000, 2001, 2002, 2003; Ishikawa et al., 1997; Zenitani et al., 1999; Tamura et al., 2004,
2005, 2006, 2009a, 2009b, 2012; Bando et al., 2010; Matuoka et al., 2007; Yasunaga et al., 2011). The
zigzag-shaped track line was established on an arbitrary basis in each sub-area. Furthermore, some ‘special
monitoring surveys’ (SMS) were conducted in areas where the abundance of common minke whales,
Bryde’s and sei whales was expected to be high. Track line in the SMS was designed separately from theoriginal track line. Two SSVs were allocated to these tracks with the allocation being changed every day.
The research course for the SSVs consisted of one main track and one parallel track established 7n.miles
apart from the main course.
Sighting procedure for the whale sampling survey, dedicated sighting survey and whale sighting and preysurveys was similar to the previous surveys of JARPN and JARPN II (Fujise et al., 1995, 1996, 1997, 2000,
22001, 2002, 2003; Ishikawa et al., 1997; Zenitani et al., 1999; Tamura et al., 2004, 2005, 2006, 2007,2009a, 2009b, 2012; Bando et al., 2010; Matsuoka et al., 2008; Yasunaga et al., 2011). In the research area,
sighting was conducted mainly under closing mode. Furthermore two modalities of sighting in closing
mode were adopted, NSC and NSS modes, by taking into consideration weather and sea conditions. The
conditions to conduct surveys under NSC mode were similar to those established in Japanese sighting
surveys conducted by the National Research Institute of Far Seas Fisheries (i.e. visibility of two n.miles ormore and wind force of four or below). The NSS mode was used under bad weather conditions such as
strong wind, heavy rain or fog but the collection of whale samples was still possible. These two mode
surveys were recorded separately for future analysis. Also an ASP mode was used (closing mode survey
without sampling activities under normal sighting conditions). Closing was performed mainly on sightingsof common minke, Bryde’s, sei and sperm whales. Furthermore closing was made on sightings of otherlarge whales, such as blue, humpback, right and fin whales. In these cases, closing was done in order toconfirm species and school size and in order to conduct some experiments.
Sampling numbers and procedure of targeted whales
The target species and sample sizes in the 2012 JARPN II offshore component were set as follows: 100
common minke whales; 100 sei whales, 50 Bryde’s whales and 10 sperm whales. Most of the whales
sighted on the track line were approached for sampling. Furthermore sampling effort was applied outside
the established research hours (main time: 06:30-18:30 (12 hrs) in local time), if collection of whale
samples was considered possible. For schools consisting of two or more animals, numbering was made forall the whales in the school; to set sampling order randomly in accordance with the table of random
numbers (Kato et al., 1989). Cow and calf pairs were not targeted for sampling. Sampled whales wereimmediately transported to the research base vessel, where biological measurements and sampling werecarried out.
Experiments
The following experiments and observations were conducted by the SSVs:
1. Sighting distance and angle experiments to examine the precision of sighting data.
2. Biopsy sampling on gray, blue, fin, sei, Bryde’s, common minke, humpback, right, bowhead and sperm
whales.
3. Photographic records of natural marks on blue, humpback and right whales.
4. Observation of feeding behaviour on blue, fin, sei, Bryde’s, common minke, humpback, right andsperm whales.
5. Observation of excretion and vomiting behaviour on sei, Bryde’s, common minke and sperm whales.

Observation of marine debris
Observation of marine debris was conducted from the wheelhouse of the research base vessel (NM) duringtransit from home port to the research area (16 May to 20 May) and from research area to home port (29July to 3 August). Marine debris was also investigated in the stomach contents of common minke, Bryde’s,
sei and sperm whales sampled.

Dedicated Sighting survey
A report of the dedicated sighting surveys was presented by Matsuoka et al. (2013). Here just a brief
outline is presented. Three independent surveys were conducted in this season.
Research area
First survey: sub-area 7
Second survey: between 30°N to 40°N, 140°E to 170°E
Third survey: sub-area 7
Research vessel
The YS1, YS2 and Yushin Maru No.3 (YS3: 742GT) were used as dedicated sighting vessel (SV).

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Methods for setting cruise track line and sighting procedure
An independent track line for dedicated sighting survey was designed in the research area.
Experiments
The following experiments and observations were conducted by the SVs.
1. Sighting distance and angle experiments to examine the precision of sighting data.
2. Biopsy sampling on gray, blue, fin, sei, Bryde’s, common minke, humpback, right, bowhead and sperm
whales.
3. Photographic records of natural marks on blue, humpback and right whales.
4. Observation of feeding behaviour on blue, fin, sei, Bryde’s, common minke, humpback, right andsperm whales.
5. Satellite tag tracking on large whales.

Whale sighting and prey surveys
A report of this survey is presented in the Appendix. The objective of the survey in this year was to
examine habitat and prey preference of Bryde’s whale and habitat preference of sei whale in late summer.
Research area
Research area was set in sub-areas 8 and 9.
Research vessel
The Shunyo Maru (SYO: 887GT) was used as whale sighting and prey survey vessel (SPV).
Methods for setting cruise track line and survey procedure
Survey for Bryde’s whale was conducted simultaneously at the same track line of whale sampling survey
within 6 days. Survey for sei whale was conducted independently.
Experiments
The following experiments and observations were conducted by the SPV.
1. Sighting of cetaceans from top barrel.
2. Record of oceanographic conditions by CTD.
3. Collection of data for the estimation of abundance of prey species: chlorophyll, echo sounder, midwater trawl, BONGO net and twin NORPAC net surveys.

RESULTS
Whale sampling survey
Actual survey periods, track lines and searching distances
Cruise period: Between 16 May and 3 August (80 days)
Research period: Between 21 May and 28 July (69 days)
Track line: Track line set by the two SSVs is shown in Figure 2.
Searching distance: The total searching distance for SSVs was 2,326 n.miles
Sightings of common minke, sei, Bryde’s and sperm whales4

A total of 82 schools (86 individuals) of common minke whales was sighted, consisting of 14 schools (15ind.) of primary and 68 schools (71 ind.) of secondary sightings. For sei whale, 170 schools (304 ind.) weresighted, consisting of 52 schools (83 ind.) of primary and 118 schools (221 ind.) of secondary sightings.
For Bryde’s whale, 70 schools (86 ind.) were sighted, consisting of 34 schools (45 ind.) of primary and 36
schools (41 ind.) of secondary sightings. For sperm whale, 84 schools (218 ind.) were observed, consistingof 45 schools (111 ind.) of primary and 39 schools (107 ind.) of secondary sightings (Table 1).
Sightings of other large cetacean species
Table 1 also shows the number of sightings for other large whale species made by the SSVs, including
large baleen whales such as blue (five schs./five inds.), fin (45 schs./61 inds.), humpback (29 schs./35 inds.)
and right whales (two schs./two inds.).
Sampling and biological research on common minke, Bryde’s, sei and sperm whales
A total of 74 common minke whales (male: 58 individuals, female: 16 individuals), 100 sei whales (male:44, female: 56 ind.), 34 Bryde’s whales (male: 11, female: 23 ind.) and three sperm whales (male: 1,
female: 2 ind.) were sampled. Struck and lost did not occur in this survey. Table 2 summarizes the
biological data and samples collected from whales. A total of 46 research items was covered. These items
are related to the studies conducted under the three main objectives of the JARPN II: study on feeding
ecology of whales and marine ecosystem, pollution studies and elucidation of stock structure.
Composition of sex and sexual maturity status of common minke, sei, Bryde’s and sperm whales are shownin Table 3. Statistics of body length of each whale species is shown in Table 4. Mean body length ofcommon minke whales was 6.88m and 6.26m for males and females, respectively. For sei whales, thosewere 13.26m and 14.26m, respectively. For Bryde’s whales, those were 11.61m and 12.52m, respectively.
For sperm whales, body length was 8.71m for one male and 9.84 and 11.51m for two females, respectively.

Geographical distribution of common minke, sei, Bryde’s and sperm whale samples is shown in Figure 3
based on the sighting positions.

Distribution and food habits of whales
During the research period, common minke whales fed mainly on Japanese anchovy (Engraulis japonicus)(49.2%) and walleye Pollock (Theragra chalcogramma) (36.1%) (Table 5). Almost all common minke
whales were sampled in or around continental shelf region in the northern part of sub-area 7 in May andJune. Common minke whales fed mainly on Japanese anchovy near Shiriya-zaki, off northernmost regionof Honshu and walleye pollock off eastern Hokkaido.
Sei whales were distributed widely in the offshore area. In this survey, almost all sei whales were sampled
in the sub-areas 8 and 9 and they fed mainly on copepods (55.7%), Japanese anchovy (16.5%) andmackerels (12.7%) (Table 5).

Bryde’s whales were distributed in the southern part of the research area. In this survey, almost all Bryde’s
whales were sampled in the sub-areas 8 and 9 and they fed mainly on Japanese anchovy (65.0%), followedby krill (30.0%) in July (Table 5).

Sperm whales were also distributed widely in the research area. In this survey, three sperm whales were
sampled in the sub-area 7. Main prey species were deep sea squids.
Experiments
Sighting distance and angle experiment5

A sighting distance and angle experiment was performed on 28 June 2012 by YS1 and YS2. The results ofthis experiment will be used in calculation of abundance estimates.
Photo-ID and biopsy sampling
Two right whales were photographed by the SSVs. A total of five biopsy samples were collected from one
right and four sei whales by the SSVs.
Feeding behaviour
No case of feeding was observed in the research.
Excretion and vomiting behaviour
No case of excretion or vomiting was observed in the research.
Observation of marine debris
No large debris was observed in the environment.
Small piece of plastic was observed in the stomachs of five common minke, 44 sei and ten Bryde’s whales.
Small piece of wood was observed in three minke, four sei and one Bryde’s whales. One to five pieces
were observed in each individual and sizes were less than 15cm in most cases.

Dedicated Sighting survey (see details in Matsuoka et al., 2013)
Actual research periods and searching distance
Cruise period:First survey: Between 17 May and 30 June (45 days; YS3)

Second survey : Between 20 August and 3 October (45 days; YS1, YS2)
Third survey: Between 14 September and 1 October (18 days; YS3)

Searching distance:
First survey: 2,728.3 n.miles (YS3)

Second survey : 2,482.9 n.miles (YS1); 2,808.9 n.miles (YS2)
Third survey: 727.6 n.miles (YS3)

Sightings of common minke, Bryde’s, sei and sperm whales
A total of 42 schools (51 individuals) of common minke, 35 schools (49 ind.) of Bryde’s, 11 schools (14ind.) of sei and 71 schools (168 ind.) of sperm whales was sighted during first survey. During second
survey, a total of 102 schools (134 ind.) of Bryde’s and 93 schools (251 ind.) of sperm whales was sighted.
A total of 20 schools (24 ind.) of common minke, one school (one ind.) of sei and five schools (seven ind.)of sperm whales was sighted during third survey.

Sightings of other large cetacean species
Large baleen whales such as fin (four schools/10 individuals) and humpback (32 sch./42 ind.) were sighted
during first survey. During second survey, blue (one sch./one ind.) and fin (one sch./one ind.) whales weresighted. Fin whale (five sch./six ind.) was sighted during third survey.

Experiments

6

Photo-ID and biopsy sampling
Ten humpback whales were photographed during first survey and one blue whale was photographed during
the second survey. A total of 44 biopsy samples were collected from one blue, one fin and 42 Bryde’s
whales during second survey.

Feeding behaviour
No case of feeding was observed in the research.
Satellite tag tracking
During the first survey, YS3 attempted the attachment of a satellite tag on humpback whale (oneschool/two animals), sei whale (one school/one animal) and common minke whales (two schools/four
animals), but not succeeded.

Whale sighting and prey surveys (see details in Appendix)
Actual research period and searching distance
Cruise period: Between 25 July and 21 August (28 days)
Research period: Between 28 July and 15 August (19 days)
Searching distance: 812 n.miles.

Sightings of common minke, Bryde’s, sei and sperm whales
A total of 58 schools (72 individuals) of Bryde’s, 15 schools (19 ind.) of sei and 27 schools (96 ind.) of
sperm whales was sighted as primary sighting.

Sightings of other large cetacean species
No other large whale species were observed.

Main experiments
CTD: 33 points
Midwater trawl: 11 points
Twin NORPAC net survey: 29 points
BONGO net survey: 16 points
Fluorescence survey: 16 points
Water sampling survey: 16 points at 0, 10, 30, 50, and 100 m depths

DISCUSSION
Prey species and food habits of common minke, sei, Bryde’s and sperm whales in the 2012 survey is
discussed below in the context of previous survey results.
Common minke whale
From the JARPN and JARPN II surveys from 1994 to 2011, common minke whales fed on various preyspecies such as Japanese anchovy, Pacific saury Cololabis saira, walleye pollock and Japanese common

7squid Todarodes pacificus, and the main prey species changed seasonally and geographically. For example,
they fed on Japanese anchovy in May/June and Pacific saury in July/August in offshore area (Tamura et al.,2009c).
In the 2012 survey, it was confirmed that walleye pollock is an important prey species for minke whales offeastern Hokkaido during early feeding season (May to June), which was also confirmed by the previous
coastal survey (Yasunaga et al, 2012). During the same season, Japanese anchovy was the main preyspecies off Shiriya-zaki. It is reasonable to assume that common minke whales do not have a strong
preference for a particular prey species. Changes in the prey species reflect changes in the abundance oravailability of prey species in the area.
Sei whale
From our research results of past JARPN II (2002 to 2011), they fed on Japanese anchovy and copepods
dominantly during survey season in most of years (Tamura et al., 2009c).
During the present survey, sei whales fed mainly copepods, Japanese anchovy and mackerels in offshorezone of research area. In recent surveys, mackerels were occasionally observed as prey species, whichmight indicate recovery of this resource.
Bryde’s whale
From our research results of past JARPN II (2000 to 2011), the dominant prey species of Bryde’s whale
was Japanese anchovy and krill during May to September. There was seasonal change of prey species. In
early season (May and June) the dominant prey species was krill. In late season (from July to September),the dominant prey species was Japanese anchovy in sub-areas 7 and 8. In the south eastern part of sub-area
9, oceanic lightfish were also important prey species in August.
During the present survey, Bryde’s whale fed mainly on Japanese anchovy followed by krill in July in the
sub-areas 8 and 9. These results were the same as in previous surveys.
Sperm whale
From our research results of past JARPN II (2000 to 2011), the following information was obtained: (1)sperm whales feed mainly on deep-sea squids. Some of these are reported as prey species of the sperm
whale for the first time; (2) Squids found in the sperm whale stomach are relatively fresh suggesting thatsperm whale feed on these prey during daytime; (3) At least some fish species (walleye pollock, bottom
fishes) was identified in the diet of the sperm whale (Tamura et al., 2009d). During the present survey thefood habit of sperm whale was the same as in previous surveys.
ACKNOWLEDGMENTS
The authors are greatly indebted to Tatsushi Matsuo and Takaaki Sakamoto of the Fisheries Agency ofJapan, Hidehiro Kato, Tokyo University of Marine Science and Technology, and Yoshihiro Fujise, Hiroshi
Hatanaka, Seiji Ohsumi, L.A. Pastene, Tsutomu Tamura and Shigetoshi Nishiwaki of the Institute of
Cetacean Research (ICR) for their guidance in the design and implementation of the research. We thankresearch technicians, Messrs. Tatsuo Sasaki, Teppei Hattori and Takaaki Murakami of Kyodo Senpaku
Kaisya Ltd. for their contribution. Mr. Takayuki Suetsugu of the Government of Japan, served as onboard
inspector. We thank all crew of the research vessels (NM, YS1, YS2, YS3 and SYO) and the staff of the ICR,
Kyodo-Senpaku Co. Ltd and NRFSF for their effort and collaboration.

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Pastene, L., Hatanaka, H., Fujise, Y., Kanda, N., Murase, H., Tamura, T., Mori, M., Yasunaga, G., Watanabe, H. and Miyashita, T.
2010. Response to the report to the ‘Report of the expert workshop to review JARPN II programme’. Paper SC/61/JR1 presented to
the IWC Scientific Committee, May 2009 (unpublished). 21pp.
Tamura, T., Fujise, Y., Bando, T., Yasunaga, G., Konishi, K., Kiwada, H., Isoda, T., Itoh, S. Machida, S., Tsunekawa, M., Konagai, T.,
Takamatsu, T., Ohshima, T., Honjo, K., Matsuoka, T., Zharikov, K.A., Yong, Rock AN, Tohyama, D. and Kawahara, S. 2004.
Cruise Report of the Japanese Whale Research Program under Special Permit in the western North Pacific -Phase II (JARPN II) in
2003 (part I) – Offshore component –. Paper SC/56/O13 presented to the IWC Scientific Committee, June 2004 (unpublished). 46pp.
Tamura, T., Fujise, Y., Mogoe, T., Kanda, N., Yasunaga, G., Konishi, K., Kiwada, H., Ogihara, M., Hasegawa, A., Kitajima, M,
Sugiyama, T., Sasaki, T., Mori, M., Teraoka, T., Tsunekawa, M., Fukutome, K., Zharikov, K.A , NA, Jong-Hun., Tohyama, D,
Inagake, D. and Kawahara, S. 2005. Cruise Report of the Japanese Whale Research Program under Special Permit in the western
North Pacific -Phase II (JARPN II) in 2004 (part I) – Offshore component –. Paper SC/57/O3 presented to the IWC ScientificCommittee, June 2005 (unpublished). 33pp.

9

Tamura, T., Otani, S., Kiwada, H., Mori, M., Konishi, K., Isoda, T., Wada, A., Ogihara, M., Hasegawa, A., Kumagai, S., Komatsu, W.,
Hayasaka, K., Fukutome, M., Siozaki, M., Zharikov, K.A, NA, Jong-Hun., Ogawa, T, Watanabe, H., Yonezaki, S, Inagake, D. and
Kawahara, S. 2006. Cruise report of the second phase of the Japanese Whale Research Program under Special Permit in the Western
North Pacific (JARPN II) in 2005 – Offshore component –. Paper SC/58/O8 presented to the IWC Scientific Committee, June 2006
(unpublished). 52pp.
Tamura, T., Otani, S., Isoda, T., Wada, A., Yonezaki, S., Mori, M., Tsunekawa, M., Fukutome, K., Nakai, K., Satoh, H., Nomura, I.,
Nagatsuka, S., Umatni, M., Koyanagi, T., Takamatsu, T., Kawabe, S., Kandabashi, S., Watanabe, H, Kumagai, S., Sato, H. andOgawa, T. 2009a. Cruise Report of the second phase of the Japanese Whale Research Program under Special Permit in the Western
North Pacific (JARPN II) in 2008 (part I) - Offshore component –. Paper SC/61/O4 presented to the IWC Scientific Committee,
May 2009 (unpublished). 49pp.
Tamura, T., Matsuoka, K. and Fujise, Y. 2009b. Methodology and survey procedure under the JARPN II - offshore component- withspecial emphasis on whale sampling procedures. Paper SC/J09/JR4 presented to the JARPN II review meeting, January 2009
(unpublished). 36pp.
Tamura, T., Konishi, K., Isoda, T., Okamoto, R. and Bando, T. 2009c. Prey consumption and feeding habits of common minke, sei
and Bryde’s whales in the western North Pacific. Paper SC/J09/JR16 presented to the JARPN II review meeting, January 2009
(unpublished). 36pp.
Tamura, T., Kubodera, T., Ohizumi, H., Konishi, K. And Isoda, T. 2009d. Feeding habits of sperm whales and their impact on neon
flying squid resources in the western North Pacific. Paper SC/J09/JR17 presented to the JARPN II review meeting, January 2009
(unpublished). 22pp.
Tamura, T., Mogoe, T., Nakai, K., Mori, M., Tsunekawa, M., Yoshimura I., Ishikawa, Y., Kawabe, S., Yamaguchi, F., Yamazaki, M.,
Ueta, E., Watanabe, H. and Eguchi, K. 2012. Cruise Report of the Second Phase of the Japanese Whale Research Program underSpecial Permit in the Western North Pacific (JARPN II) in 2011 (part I) – Offshore component –. Paper SC/64/O3 presented to the
IWC Scientific Committee, May 2013 (unpublished). 28pp.
Yasunaga, G., Kiwada, H., Mogoe, T., Wada, A., Nakai, K., Mori, M., Tsunekawa, M., Kasai, H., Ohshima, T., Yoshimura, I., Sato,
H., Sakamoto, N., Watanabe, H., Fujiwara, G., Tamura, T. and Ogawa, T. 2011. Cruise report of the Second Phase of the Japanese
Whale Research Program under Special Permit in the Western North Pacific (JARPN II) in 2010 (part I) - Offshore component –.
Paper SC/63/O2 presented to the IWC Scientific Committee, June 2011 (unpublished). 38pp.
Yasunaga, G., Itou, N., Wada, A., Kiwada, H., Sato, H., Maeda, H., Nakamura, G., Inoue, S., Miyakawa, N., Kitayama, K., Ishikawa,Y., Suzuki, N., Tsutsumi, T., Kadowaki, I. and Kato, H. 2012. Cruise report of the Second Phase of the Japanese Whale Research
Program under Special Permit in the Western North Pacific (JARPN II) in 2011 (part II) - Coastal component off Kushiro, springsurvey –. Paper SC/64/O4 presented to the IWC Scientific Committee, June 2012 (unpublished). 13pp.
Zenitani, R., Fujise, Y., Matsuoka, K., Tamura, T., Bando, T., Ichihashi, H., Shimokawa, T., Krasnenko, A.S., Taguchi F., Kinoshita,T., Mori, M., Watanabe, M., Ichinomiya, D., Nakamura, M., Sakai, K., Matsuzaka, K., Kamei, H. and Tohyama, D. 1999. Cruise
report of the Japanese Whale Research Program under a Special Permit in the North Pacific in 1998. Paper SC/51/RMP7 presented
to the IWC Scientific Committee, May 1999 (unpublished). 20pp.

10

Table 1. Whale species and number of sightings in the 2012 JARPN II survey (no. schools/no. individuals)
Sighting/sampling vessels (YS1 and YS2)
SpeciesCommon minke whale
Like minke whale
Sei whale
Bryde's whale
Sperm whale
Blue whale
Fin whale
Humpback whale
Right whale

PrimarySch. Ind.
14 15
0
0
52 83
34 45
45 111
1
1
13 17
14 16
0
0

SecondarySch. Ind.
68 71
7
7
118 22136 41
39 107
4
4
32 44
15 19
2
2

Total
Sch. Ind.
82 86
7
7
170 304
70 86
84 218
5
5
45 61
29 35
2
2

Table 2. Summary of biological data and samples collected during the 2012 JARPN II survey.
Com mon m inke

Research items
Body length and sex
External body proportion
Photographic record and external character
Diatom film record
Standard measurements of blubber thickness (five points)
Detailed measurements of blubber thickness (eleven points)
Body weight
Body weight by parts
Blubber tissues for DNA study
Kidney tissues for heavy metal analysis
Blubber, muscle, liver and kidney tissues for organochlorines analysis
Tissue for nutritional compornent analysis
Lung tissue for atmospheric analysis
M uscle tissues for cesium analysis
Tissues for various analysis
Tissues for virus test
M ammary gland; lactation status and measurement
Collection of ovary
Photographic record of foetus
Foetal sex (identified by visual observation)
Foetal length and weight
Foetal blubber tissues for DNA study
Testis; weight and histological sample
Collection of plasma sample
Stomach content, conventional record
Weight of stomach content in each compartment
Stomach contents for feeding study
Record of external parasites
Collection of external parasites
Record of internal parasites
Collection of internal parasites
Earplug for age determination
Tympanic bulla for age determination
M axillally teeth for age determination
Lens for age determination
Largest baleen plate for morphologic study and age determination
Vertebral epiphyses sample
Brain weight
Skull measurements (length and breadth)Pelvic bone
Foetal pelvic bone
Detailed measurements of pectoral fin for morphological study
Photographic record of pectoral and caudal fin for morphological study
Collecton of fetus for histological study
Testis tissues for morphological study
Placenta tissues for morphological study

11

F
16
16
16
16
16
0
16
0
16
0
16
1
0
4
16
16
16
3
3
3
3
16
14
14
14
16
0
16
0
16
0
0
16
16
16
0
16
16
3
16
16
0
0

M
58
58
58
58
58
1
58
1
58
0
58
4
10
7
58
58
1
1
1
1
58
58
58
58
58
58
0
58
0
58
1
0
58
58
58
1
58
58
1
58
58
0
0
-

T
74
74
74
74
74
1
74
1
74
0
74
5
10
11
74
58
16
16
4
4
4
4
58
74
72
72
72
74
0
74
0
74
1
0
74
74
74
1
74
74
4
74
74
0
0
0

Sei whale
F M
T
56 44 100
56 44 100
56 44 100
56 44 100
56 44 100
10
156 44 100
10
156 44 100
40 24 64
56 44 1002
3
5
0 10 1064
1056 44 100
- 44 4456 56
56 56
18 20 38
18 20 38
18 20 38
18 20 38
- 44 44
56 44 100
56 44 100
56 44 100
56 44 100
56 44 100
11
2
56 44 100
10
156 44 100
1
0
1
0
0
0
56 44 100
56 44 100
56 44 100
10
1
56 43 9956 44 100
18 20 38
0
0
0
0
0
0
1
1
2
- 10 1099Bryde's whale

Sperm whale

F
23
23
23
23
23
1
23
1
23
0
23
3
0
5
23
23
23
4
4
4
4
23
23
23
23
23
2
23
0
23
1
0
23
23
23
1
23
23
4
0
0
0
6

F
2
2
2
2
2
0
2
0
2
0
2
0
2
2
2
1
2
0
0
0
0
2
2
2
2
2
0
2
2
0
0
2
2
2
0
2
2
0
0
0
0
0

M
11
11
11
11
11
0
11
0
11
0
11
2
6
5
11
11
6
6
6
6
11
11
11
11
11
11
1
11
0
11
0
0
11
11
11
0
11
11
6
0
0
0
4
-

T
34
34
34
34
34
1
34
1
34
0
34
5
6
10
34
11
23
23
10
10
10
10
11
34
34
34
34
34
3
34
0
34
1
0
34
34
34
1
34
34
10
0
0
0
4
6

M
1
1
1
1
1
1
1
1
1
0
1
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
0
0
0
1
1
1
1
1
1
1
0
0
0
0
-

T
3
3
3
3
3
1
3
1
3
0
3
0
3
3
3
1
1
2
1
1
1
1
1
3
3
3
3
3
0
3
2
0
0
3
3
3
1
3
3
1
0
0
0
0
0

Table 3. Sex and sexual maturity composition of whales sampled during the 2012 JARPN II survey.
MaleSpecies

Sub
area
SA7

Common
minke

SA8
SA9
Combined
SA7

Sei

SA8
SA9
Combined
SA7

Bryde's

SA8
SA9
Combined
SA7

Sperm

SA8
SA9
Combined

FemaleMat.

Imm. Mat. Uk Total

Imm.

21
0
0
21
0
3
10
13
0
3
2
5
0
0
0
0

12
0
0
12
0
4
7
11
0
3
1
4
0
0
0
0

29
1
0
30
0
12
19
31
0
2
4
6
0
0
0
0

5
2
0
7
0
0
0
0
0
0
0
0
1
0
0
1

55
3
0
58
0
15
29
44
0
5
6
11
1
0
0
1

Ovu. Rest. Preg. Lact.
0
0
0
0
0
0
2
2
0
0
0
0
0
0
0
0

0
0
0
0
0
3
2
5
0
4
4
8
0
0
0
0

4
0
0
4
0
14
22
36
0
4
6
10
1
0
0
1

0
0
0
0
0
0
1
1
0
0
1
1
1
0
0
1

Total
Preg.
Total
Lact.
0
4
16
0
0
0
0
0
0
0
4
16
0
0
0
0
17
21
1
28
35
1
45
56
0
0
0
0
8
11
0
11
12
0
19
23
0
2
2
0
0
0
0
0
0
0
2
2

Total
71
3
0
74
0
36
64
100
0
16
18
34
3
0
0
3

Table 4. Body length (m) of whales sampled during the 2012 JARPN II survey.
SpeciesCommonminke

Sei

Bryde's

Sperm

Male

Female

Sub
area

n

mean

S.D.

min

max

n

mean

S.D.

min

max

SA7

55

6.84

0.77

5.01

8.16

16

6.26

1.24

4.73

8.48

SA8

3

7.54

0.40

7.10

7.87

0

SA9

0

Combined

58

6.88

0.77

5.01

8.16

16

6.26

1.24

4.73

8.48

SA7

0

SA8

15

13.51

0.65

12.56

15.14

21

14.41

0.84

12.76

15.98

SA9

29

13.13

1.16

9.80

14.51

35

14.17

1.23

9.91

15.72

Combined

44

13.26

1.03

9.80

15.14

56

14.26

1.10

9.91

15.98

SA7

0

SA8

5

11.37

1.87

9.35

13.38

11

12.20

1.43

8.96

13.99

SA9

6

11.81

1.45

9.08

13.06

12

12.82

0.62

11.68

13.78

Combined

11

11.61

1.58

9.08

13.38

23

12.52

1.10

8.96

13.99

SA7

1

8.71

2

10.68

1.18

9.84

11.51

SA8

0

SA9

0

Combined

1

10.68

1.18

9.84

11.51

0
0

0

0
0
8.71

2

12

Table 5. Prey species and stomach contents weight (1st. + 2nd. stomachs) in whales sampled during the2012 JARPN II survey.
N%

Range of weight
(kg)

7
1
30
1
22

11.5
1.6
49.2
1.6
36.1

12.08
16.54
1.84
62.42
8.02

- 68.96

Neocalanus spp.
Japanese anchovy
Japanese sardine
Walleye pollock

Neocalanus spp.
Japanese anchovy
SquidsMackerels
Pacific saury
Unidentified

7
44
13
1
10
3
1

8.9
55.7
16.5
1.3
12.7
3.8
1.3

9.34
11.06
35.44
128.20
26.38
19.00
24.60

- 618.29- 294.84- 708.75

6
1
13

30.0
5.0
65.0

45.14
324.6434.44- 175.78

Japanese sardine
Japanese anchovy

Dominant prey species
Common minke whale
Krill
Copepods
Fish- 209.45- 119.60

Sei whale
Krill
Copepods
Fish- 399.55- 77.94- 24.60

Bryde's whale
Krill
Fish

9
7

8

Figure 1. Research area of the JARPN II full-scale program.

13- 521.86

MinkeSei
Bryde's
Sperm
Blue
Fin
Humpback
Right

45N

35N
140E

160E

Figure 2. Track-lines and sighting positions of large whales made by the sighting/sampling vessels (SSVs).

Minke
Sei
Bryde's
Sperm

45N

35N
140E

160E

Figure 3. Sighting positions of the sampled common minke (pink circle), sei (orange square), Bryde’s(green diamond) and sperm (brown triangle) whales. Red block shows the survey area for thecooperative prey and whale sampling survey. Blue lines were special monitoring surveys

14

APPENDIX
Cruise report of JARPN II whale sighting and prey surveys inconjunction with whale sampling survey in the offshore regionof the western North Pacific in 2012
HIKARU WATANABE1), KOUICHI SAWADA2), MAKOTO OKAZAKI3), TAKEHARU BANDO4), YOSHIAKIFUKUDA5), TAKUYA MIZUKAMI5), DENZO INAGAKE3), TSUTOMU TAMURA4), AND TOMIO MIYASHITA1)

1)National Research Institute of Far Seas Fisheries, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa-ku,

Yokohama, Kanagawa 236-8648, Japan
2)

National Research Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7 Hasaki, Kamisu, Ibaraki

314-0408, Japan
3)

National Research Institute of Fisheries Science, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa-ku,

Yokohama, Kanagawa 236-8648, Japan
4)

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

5)

Graduate School of Fisheries Science, Hokkaido University, 3-1-1 Minato, Hakodate, Hokkaido 041-8611, Japan*Contact e-mail: hikaru1@affrc.go.jp

ABSTRACT
Whale sighting and prey surveys were carried out in the transition region of the western North Pacific in
the boundary zone of sub-area 8 and 9 in late July and early August 2012. The objective of these surveys
in this year was to examine habitat selection of sei whale Balaenoptera borealis and habitat and preyselections of the Bryde’s whale B. edeni in this area in late summer in relation to oceanographic andecosystem information. Survey on Bryde’s whale was conducted with whale sampling survey at the same
area within 6 days. Sei whale was mainly found in the northern area north of 41ºN where was the main
habitat of adult Japanese anchovy Engraulis japonica and adult Japanese common mackerel Scomber
japonicus, both of which were frequently fed on by the whale according to the past data of JARPN II. In
June 2011, we conducted whale sighting and prey surveys at the same area and sei whale was mainly
found more southern area south of 39˚N, where was also the main habitat of adult Japanese anchovy andJapanese common mackerel. These facts suggest that sei whale migrate to the northward following
northward migration of these preys from early to late summer. Bryde’s whale was mainly found in thearea south of 39º30’N where was the main habitat of juvenile Japanese anchovy and Japanese sardine
Saldinops melanostictus, indicating that this species selected main distribution area of these fish preys as
their main feeding ground. Bryde’s whale was not found in our survey in June 2011, suggesting that thisspecies migrate into the study area during mid and late summer. Distribution of these whale species inrelation to primary production was also depicted.

15

KEY WORDS: SEI WHALE, BRYDE’S WHALE, HABITAT SELECTION, WHALE SIGHTING ANDECOSYSTEM SURVEYS, OFFSHORE REGION, WESTERN NORTH PACIFIC, LATE SUMMER.

INTRODUCTION

To obtain various parameter for ecosystem modeling like prey preference of the whale, The Second
Phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific(JARPN II) have conducted ‘‘whale prey species survey’’ in conjunction with whale sampling survey toestimate abundance of whale prey species in the environment in the offshore region of the western North
Pacific (Government of Japan 2002). At the IWC/JARPN II review workshop in 2009, the Expert Panelrecommended estimation of functional relationship of each whale species (relationship between
distribution density of each prey species in environment and dietary intake of each individual of the whalefor each prey species), which is a wide-use parameter for various ecosystem models as well as prey
preference (IWC 2010). The Expert Panel also recommended accumulating quantitative ecosystem
information in the subtropical, transition, and subarctic regions, respectively, to construct ecosystemmodels in each region (IWC 2010), although JARPN II modeling group built several ecosystem models tocover the whole part of sub-area 7, 8, and 9 (Kawahara 2009, Mori et al. 2009). Based on these comments,
we newly started ‘‘whale sighting and prey surveys’’ from 2010 or 2011 by the following approach.

1.

Whale prey species survey vessel conducts whale sighting survey.

2.

These surveys and whale sampling survey conduct on the same track line at the same period to obtain
the data on prey abundance in environment and stomach contents of the whale simultaneously.

3.

Whale sighting and prey species survey vessel conducts various observations of physical andbiological conditions to obtain major ecosystem information including whales in various region andmonth.

These surveys are firstly adopted in the western North Pacific and the major parameters of ecosystemmodels could be obtained directly and quantitatively from the field data. Furthermore, whale sighting andprey surveys are also essential for single species management of whales, since both extra- andinterpolation methods of estimating whale abundance could be established based on data of the habitat
selections of each whale species (Watanabe et al. 2012b).
In this document, we firstly report the habitat selection of sei (Balaenoptera borealis) and Bryde’s
whales (B. edeni), which are abundant baleen whales in the North Pacific (Fujise et al. 2004, Kasamatsu
et al. 2009), in relation to ecosystem information in the boundary zone of sub-area 8 and 9 in late summer.
This area is characterized as typical offshore region of the western North Pacific and also the most eastern16

area where small epipelagic fish and squid species, such as Japanese anchovy Engraulis japonica,
Japanese sardine Saldinops melanostictus, Japanese common mackerel Scomber japonicus, and Japanesecommon squid Todarodes pacificus, which migrate into this area from Japanese waters, are commonly
found in summer. Hence this area is suitable to study habitat and prey selections of each whale species inrelation to various prey environments and we attempt to research in this area in various seasons(Watanabe et al. 2011, 2012a, 2012b).
During cooperative survey period of whale sighting, prey species, and whale sampling in this year,
a total of 24 individuals of Bryde’s whale was captured (Bando unpubl. data). Using these data, functional
relationship and prey preference of Bryde’s whale in relation to its distribution pattern will be analyzed in
the future.

MATERIALS AND METHODS

We conducted whale sighting and prey surveys in the western North Pacific enclosed by latitude
from 36˚30’N to 45º30’N and longitude from 156ºE and 159ºE from 28 July to 15 August 2012 by the
R/V Shunyo Maru (887 GT, National Research Institute of Far Seas Fisheries, Fig. 1). Cooperate surveyof Shunyo Maru, Nisshin Maru, and two whale sampling vessels were conducted on the southern trackline from 38˚N to 39˚30’N during 28-30 July (Fig. 1). During cooperative survey period, all surveys wereconducted within 0 to 6 days. Followings were detail of whale sighting and prey survey methods for eachsurvey item. Relationship between these survey items and outputs and goals of this study are summarized
in Fig. 2.

(1) Whale sighting survey

Whale sighting survey was carried out along with acoustic survey (see below) basically in passing
mode when wind velocity was less than 10 knots and visibility was more than two nautical miles (Fig. 2).
However, abeam closing survey was also conducted within two nautical miles perpendicular to track line
in case that the species of cetaceans could not identified by passing mode (Kasamatsu et al. 2009). During
the survey, two primary observers were allocated to the top barrel. This survey was conducted during thedaylight period from one hour after sunrise to one hour before sunset and a total of 812 nautical miles was
searched. A total of 187 animals of 100 schools of large cetacean species, including Bryde’s, sei, andsperm whales was found by primary sighting (Table 1).

17(2) Survey of oceanographic conditions

A Conductivity–Temperature–Depth (CTD, Sea–Bird Co., Ltd.) profiler cast was made down to
500 m depth at each sampling station and additional stations to determine the position of the subarctic
boundary and subarctic front (Fig. 2 and Table 2).

(3) Fluorescence survey and water sampling

We conducted fluorescence survey using the fluorometer ACL-208DK (JFE advance) in the 0–150
m layer once a day during 11:00 AM to 1:00 PM in local time to obtain data on geographical distributionof primary production in the epipelagic zone of this study area (Fig. 2 and Table 3). We also conductedwater sampling by Niskin bottles in 0, 10, 30, 50, and 100 m depths at the same position where
fluorescence survey was conducted and several additional stations to estimate primary production in eachsize range of phytoplankton (< 0.7μm, 2-10μm, and > 10μm) in epipelagic zone and also to calibrate
fluorescence value obtained by fluorometer. All water samples were successively filtered by Whatman
GF/F (0.7μm) and two nuclepore filters (2 and 10μm, Table 4). These filters were frozen at -80ºC
aboard the ship for future analysis in the laboratory ashore.

(4) Twin NORPAC net sampling

We conducted twin NORPAC net samplings in the 0–150 m layer to collect data for species andsize compositions of small and meso- zooplanktons, especially copepods, in epipelagic zone (Fig. 2 andTable 5). The mouth opening of this net was 0.15 m2 and the mesh size of each net was 0.01 x 0.01 mm
and 0.33 x 0.33 mm. A flow meter was attached to each net to measure the volume of seawater filtered.
Samples were preserved in 5 % formalin–buffered seawater.

(5) BONGO net sampling

BONGO net was towed to examine species and size compositions of macro zooplanktons,
especially euphausiids like Euphausia pacifica (Fig. 2). The mouth opening and mesh size of this net
were 0.28 m2 and 1.0 x 1.0 mm, respectively. BONGO net was towed at 2 knots in the target depths
for 10 to 40 minutes (Table 6). A flow meter was attached to net mouth to measure the volume of18

seawater filtered. We selected target depths using information of DSL and patchiness in theechograms of 38, 70, and 120 kHz. Samples were preserved in 5 % formalin–buffered seawater forlater analysis.

(6) Midwater trawl sampling

The midwater trawl adopted in this study had a mouth opening of approximately 30 x 30 m with a
17.5 mm liner cod end. The sampling depths and the height of the net mouth were monitored by net
monitor system (PI 32, SIMRAD). Trawl samplings were made to identify species and size compositionsof small epipelagic fish-like acoustic backscatters in the echosounders and also aimed for collecting
distribution data on species difficult to detect by the echosounders such as squids and neustonic
organisms like Pacific saury (Fig. 2). Trawling station was predetermined at generally every 30 to 50
nautical mile apart on the track lines. At each station, a trawl net was towed at the target depth between 0
and 200 m for 30 to 60 minutes. Towing speed was 3–4 knots. All samples were identified to the lowest
taxonomic level possible and wet body weight of each species was measured. For the major species,
individual body length was measured from randomly selected 100 samples. When sample size was lessthan 100 individuals, body length was measured for all. In this year, a total of 11 times of midwater trawl
survey was conducted (see Fig. 3).

(7) Quantitative echosounder survey

We collected acoustic data by quantitative echosounders SIMRAD EK60 with operating frequency
at 38, 70, and 120 kHz by sailing at 10 knots on the track lines (Fig. 2). Calibrations of the echosounders
were carried out in the coastal region off western Izu Peninsula (35˚02’N, 138˚51’E) on 20 and 21 August
using a standard sphere technique. A tungsten carbide sphere (38.1 mm in diameter) was used as thestandard sphere. Acoustic data will be analyzed by SonarData Echoview (Sonar Data Co., Ltd.) software.
During the cruise, communication between control PC on the bridge and the 38 kHz transceiverunit (GPT) of EK60 system broke down at 09:43 (ship mean time = Japan standard time + 1h), on 9
August. It was found later that malfunction of a communication module of the GPT had happened. Afterthe malfunction of 38 kHz, we are obliged to use 70 kHz and 120 kHz instead of the usual combination of
38 kHz and 120 kHz to classify euphausiids. And also 70 kHz instead of 38 kHz will be used to estimate
abundance of small epipelagic fish species such as Japanese anchovy, Japanese sardine, and Japanesecommon mackerel in the future.

19(8) Noise and sailing loss measurements

Generally, noise of the ship and sailing loss significantly affect to quantitative analysis on
distribution density of marine organisms based on acoustic data. Hence we measured noise and sailingloss of Shunyo Maru as follows.
Nose measurement was conducted on 13 August in various ship speeds to estimate the mostsuitable ship speed in relation to acoustic survey. Because Shunyo Maru equipped fishing and whale
sonars, and we preliminary used these sonars in this year, noise measurement was also carried out inrelation to the protrusion and retraction of these sonars. During this experiment, engine revolution was
kept at 550 rpm when two engines were used and the angle of the propeller was changed to keep the ship
speed.
Sailing loss was checked on 19 August using the reflection from sea bed on the transect line, which
was set between the positions of 34º58’N, 138º45’E and 34º55’N, 138º45’E along the coastal region off
western Izu Peninsula. The effects of protrusion and retraction of fishing and whale sonars were
investigated by measuring acoustic volume backscattering strengths (SVs) of the bottom. At first, thevessel was drifted at the northernmost, middle, and southernmost points of the transect line and wemeasured SV of the bottom echoes at these points. Then bottom echoes were measured on the transectline by moving at 10 knots from the southernmost to the northernmost points and also from thenorthernmost to the southernmost points. These measurements were conducted firstly without protrudingof fishing and whale sonars. Then similar measurement was conducted in case that fishing sonar, whale
sonar, and both sonars were protruded. In case that SV level of the bottom decreased when sonars were
protruded, we can deem the existence of attenuation of acoustic energy (i.e. sailing loss) accompanied bysurrounding air bubbles of protruded sonars.
Using these results, together with the result of trawling survey, acoustic data will be analyzed
quantitatively.

(9) Estimate of target strength of zooplanktons

In relation to obtain quantitative information on ecosystem and prey environment of each whale
species based on acoustic data, living euphausiids mainly Euphausia pacifica were sorted from twin
NORPAC or BONGO nets and its sound speed and density contrasts were measured by time of flightmethod and density bottle method, respectively, aboard the ship (Mikami et al. 2000). These experiments
are essential to obtain theoretical values of target strength (TS) of euphausiids, which are important toestimate its biomass by acoustic data (Fig. 2). To calculate TS of euphausiids, the Distorted-Wave Born

20

Approximation based deformed-cylinder model (DWBA model) will be adopted and dorsal-aspect TS asa function of the incident angle of the ensonified wave (TS-pattern) will be calculated in the future.

RESULTS AND DISCUSSION

Oceanographic conditions

In the northern North Pacific, two oceanographic fronts, subarctic front between subarctic region
and transitional domain, and subarctic boundary between transitional domain and transition zone, aredistributed (Favorite et al. 1976, Pearcy 1991). According to Kawai (1972) and Murakami (1994),
subarctic front is defined by a water temperature lower than 5˚C at 100 m. Subarctic boundary is definedby 34.0 salinity front in the epipelagic zone (Favorite et al. 1976). Our CTD data showed that watertemperature at 100 m was higher than 5˚C south of 43˚15’N and vertical salinity front of 34.0 in theepipelagic zone was found in the area between 43˚ and 43˚10’N, indicating that this study area was
located in the subarctic region north of ca. 43˚N and the transition zone to the south (Fig. 3B). Because
the position of subarctic boundary and subarctic front was almost similar, transitional domain was notclearly recognized in this study.

Distribution of sei and Bryde’s whales related to prey environment

Sei whale: This species was found in the northern transition zone and subarctic region between
41˚N and 45˚N in late July-August of this year (Fig. 3B). In this study area, sei whale was reported to bedensely distributed in the transition zone south of 39˚N in June (Watanabe et al. 2012a, Fig. 3A),
suggesting that this whale species undertake northward migration from early to late summer. Among preyspecies, Japanese anchovy and Japanese common mackerel, which are the main prey items of the whalein general (e.g. Konishi et al. 2009, Tamura et al. 2012), were abundantly distributed in the main habitatof sei whale in late July-August (Fig. 3B). According to Watanabe et al. (2012a), the main habitat of sei
whale was also found in the distribution centre of Japanese anchovy and Japanese common mackerel inJune of this study area (Fig. 3A). Because these prey species undertake northward migration from thesouthern transition zone to the northern region around subarctic front during summer (Pearcy et al. 1996,
Ichii et al. 2004), sei whale possibly migrate to the northward following northward migration of theseprey species from early to late summer. Body length of Japanese anchovy and Japanese common
mackerel shifted from 6 to 9 cm to 8 to 12 cm and from 15 to 18 cm to 18 to 21 cm, respectively, during

21June and late July-August (Fig. 3). This probably indicates a growth of 2 to 3 cm in body length over 2
months for these species because daily growth rate of these species are about 0.5 mm (Fisheries Agencyof Japan 2002). Therefore, sei whale seems to carry out northward migration with the same cohort ofJapanese anchovy and Japanese common mackerel, which probably hatched in early spring, from early tolate summer.
Bryde’s whale: This species was found in the southern transition zone between 37˚30’N and
39˚30’N in late July-August 2012 (Fig. 3B). Bryde’s whale was not distributed in the same study area inJune 2011, indicating that this species migrate into this study area from the southern transition zone
during mid to late summer (Watanabe et al. 2012a, Fig. 3A). It was remarkable that distributions ofBryde’s whale and juvenile Japanese anchovy (mainly 5 to 7 cm in body length) and Japanese sardine(mainly 6 to 8 cm in body length) almost completely overlapped in July-August 2012 (Fig. 3B). These
species probably hatched during mid and late spring because daily growth rate of this species isapproximately 0.5 mm and also thought to migrate into this study area from the southern transition zone
in late summer (Fisheries Agency of Japan 2002). This suggests that sei and Bryde’s whale feed mainly
on Japanese anchovy of different hatching seasons. According to the result of whale sampling survey inthis year, Bryde’s whale fed mainly on juvenile Japanese anchovy and Japanese sardine in this study area
during cooperative whale sighting, sampling, and prey survey period (Bando unpubl. data). These datasuggest that the distribution of these fishes greatly affect to the distribution and/or northward migration of
Bryde’s whale. Similar results are also obtained in the southern transition zone in sub-area 7 bound by
37-39˚N and 146-148˚E in late July 2008 (Watanabe et al. 2012b), suggesting that distribution pattern ofBryde’s whale in relation to prey environment obtained in this study is widely applied to the oceanic
region of sub-area 7 and 8 in the western North Pacific from mid to late summer. According to Konishi etal. (2009), Bryde’s whale feed mainly on euphausiids in this study area although this whale species rarely
migrate into there in early summer. This probably reflects feeding habits of small part of Bryde’s whale
population which migrate into this study area prier to the main part of the whale population in earlysummer.

Distribution of sei and Bryde’s whales related to primary production

In relation to chlorophyll a concentration at 20-30 m depth (CHA), which was measured by afluorometer adopted in this study, sei whale was mainly distributed in the area of around 0.8 mg m-3 CHA
in both June and late July-August (Figs. 3 and 4). This depth range is well corresponded to the habitat
depth of Japanese anchovy and Japanese common mackerel, which are mainly fed on by sei and/or
Bryde’s whales (Konishi et al. 2009, Watanabe, Bando, and Tamura unpubl. data). The main prey speciesof the whale, Japanese anchovy (5-8 cm in body length in June and > 8cm in July-August) and Japanese22common mackerel (15-18 cm in body length in June and 18-21 cm in July-August) was also mainly
distributed in this CHA area. Both Bryde’s whale and its main prey species, Japanese anchovy of 5-7 cm
in body length, were mainly distributed in the less productive southern area where CHA was around 0.45
mg m-3 in late July-August (Figs. 3 and 4). In this period, no Bryde’s whale was found in thesouthernmost region of the study area where CHA value was < 0.4 mg m-3. This area is one of the mostologotrophic region in any oceanic environment in summer (Cullen 1982), showing unfavourable feeding
condition for the whale. In June, both Bryde’s whale and CHA area of around 0.45 mg m-3 was rarely
found in this study area. This CHA area was probably located in the more southern area south of the study
area in this period, according to previous reports (e.g. Polovina et al. 2000).
These chlorophyll a concentration areas are known to undertake northward migration from spring
to summer (Polovina et al. 2000, 2001, Bograd et al. 2004; Baker et al. 2007), as was also shown in thisstudy (Figs. 3 and 4). Because northward migration patterns of sei whale and CHA area of 0.7-0.9 mg m-3
and those of Bryde’s whale and CHA area of 0.4-0.5 mg m-3 were spatio-temporally similar to each other,
distributions and seasonal south-north migrations of these whale species seems to be related to primary
production (Fig. 4). This probably indicates that distributions of these whale species is also closely related
to biological productivity, since Japanese anchovy and Japanese common mackerel are planktivorous (e.g.
Takahashi et al. 2001) and distribution of these species might be closely related to the secondary
production. To evaluate this hypothesis, analysis on geographical distribution and abundance ofzooplankton is badly needed, which is essential to progress ecosystem modelling including whales in
JARPN II area. Similar knowledge on relationship between distribution of large sized predator andprimary production are also obtained for many other species such as swordfish Xiphias gladius, albacore
Thunnus alalunga, neon flying squid Ommastrephes bartramii, and Pacific pomfret Brama japonica(Polovina et al. 2001, Seki et al. 2002, Ichii et al. 2004, Baker et al. 2007, Watanabe et al. 2004, 2006, and2009).

Distribution of sei whale related to physical environments

Distribution area of sei whale was greatly changed from June to late July-August in terms oftemperature above 10 m and below 40 m in 0-200 m layer at the sighting position of this species (Fig. 5a).
However, temperature range at 20 and 30 m in the habitat of sei whale was almost similar andapproximately 12 to 16˚C between June and late July-August, suggesting that this whale species
undertake northward migration following northward migration of these isotherms at these depths during
summer. This probably caused by densely distribution of Japanese anchovy and Japanese common
mackerel preys in this temperature range at 20-30 m (Watanabe unpubl. data, see also Fig. 3). These
results also suggest that distribution of sei whale could be estimated by distribution of isotherms at

23

sub-surface layer, which is essential to estimate abundance of the whale in the area where whale sighting
survey could not be conducted.
Contrasting with temperature, salinity values in each depth layer of sighting position of sei whales
were generally smaller in June than in late July- August (Fig. 5b). This reflects that main habitat of sei
whale shifts from the southern transition zone to the area in or close to the subarctic region from June toAugust, because salinity in the epipelagic zone generally decrease from the subarctic region to the south(Favorite et al. 1976, Pearcy 1991, Roden 1991). Therefore, salinity seems to be unusable to estimate
summer distribution of this species.

Noise and sailing loss measurements

The result of nose measurement showed that noise SVs at 120 kHz were relatively low and stable
regardless of ship conditions and protrusion and retraction of the two sonars (-75 to -80 dB, Table 7). In
case of 70 kHz, however, noise SVs greatly fluctuated in several cases. When both sonars were protruded(see No. 7 and 8 in Table 7), noise SVs at 70 kHz were almost similar to each other (-79.7 vs. -80.9 dB).
However, these values were about 8 dB higher than the case that both sonars were retracted (see No. 11 inTable 7). The present result also indicated that difference in SV values at 70 kHz between the cases thatboth sonars were retracted (No. 11 in Table 7) and only fishing sonar was protruded (No. 12 in Table 7)
was small and similar to each other (-88.5 and -87.8 dB). However, noise SVs at 70 kHz were about 10
dB higher in case that only whale sonar was protruded (No. 13 in Table 7) than the case that both sonars
were retracted (No. 11 in Table 7, -78.0 vs. -88.5 dB). These results strongly suggest that acoustic survey
using 70 kHz and whale sonar survey should be conducted alternatively on Shunyo Maru.
The result of the sailing loss measurement showed that measured SVs of the bottom during sailingand drifting and during sailing with and without protrusion of the two sonars were similar to each other(Fig. 6). These facts suggest that sailing loss accompanied by protrusion of sonars could not significantly
affect to the acoustic data of 70 and 120 kHz collected by Shunyo Maru.
Because communication between control PC on the bridge and the 38 kHz transceiver unit of
EK60 system broke down during the cruise, we could not obtain these data for 38 kHz echosounder inthis study. Such data is badly needed to obtain quantitative information on ecosystem structure.

ACKNOWLEDGEMENTS

A special thank is given to Captain K. Hata, officers, and crews of R/V Shunyo Maru and Y.

24

Tanaka, N. Kasai, T. Shibata for their skilful assistance in collecting data. T. Ichikawa of National
Research Institute of Fisheries Science and O. Yamamura of Hokkaido National Fisheries ResearchInstitute kindly allowed us to use their sampling gears.

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277-283.
Bograd, SJ., Foley, DG., Schwing, FB., Wilson, C and others. 2004. On the seasonal and interannual
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Cullen, JJ. 1982. The deep chlorophyll maximum: comparing vertical profiles of chlorophyll a. Can. J.
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Fisheries Agency of Japan. 2002. Current status of fisheries resources around Japan. 175pp. (in Japanese).
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Government of Japan. 2002. Research Plan for Cetacean Studies in the Western North Pacific underSpecial Permit (JARPN II). Paper SC/54/O2 presented to the IWC Scientific Committee, May 2002
(unpublished). 115pp.
Ichii, T., Mahapatra, K., Sakai, M., Inagake, D. and Okada, Y. 2004. Differing body size between theautumn and the winter-spring cohorts of neon flying squid (Ommastrephes bartramii) related to theoceanographic regime in the North Pacific: a haypothesis. Fish. Oceanogr. 13: 295-309.
International Whaling Commission. 2010. Report of the expert workshop to review the ongoing JARPN
II program. J. Cetacean Res. Manage. 11 (Suppl. 2): 405-449.
Kasamatsu, F., Miyashita, T. and Yoshioka, M. 2009. Field guide to whales, dolphins, and porpoises in thewestern North Pacific and adjacent waters (new edition, Ohsumi S. ed). Tokyo: Tokyo University Press(in Japanese).
Kawahara, S. 2009. A minimum realistic model in the JARPN II offshore survey area. A document
presented to the IWC/JARPN II review workshop held at National research Institute of Fisheries
Science in Yokohama from 26-30 January 2009, SC/J09/JR22 (unpublished). 22pp.
Kawai, H. 1972. Hydorography of the Kuroshro and the Oyashio. In: Physical oceanography II.
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Konishi, K., Tamura, T., Isoda, T., Okamoto, R., Matsuoka, K. and Hakamada, T. 2009. Feeding strategies
and prey consumption of three baleen whale species within the Kuroshio-Current extension. J. Northw.
Atl. Fish. Sci. 42: 27-40.
Mikami, H., Mukai, T. and Iida, K. 2000. Measurement of sound speed and density rates of euphausiids toestimate their target strength by theoretical model. Nippon Suisan Gakkaishi, 66: 682-689. (in Japanesewith English abstract).
Mori, M., Watanabe, H., Hakamada, T., Tamura, T., Konishi, K., Murase, H. and Matsuoka, K. 2009.
Development of an ecosystem model of the western North Pacific. A document presented to the
IWC/JARPN II review workshop held at National research Institute of Fisheries Science in Yokohama
from 26-30 January 2009, SC/J09/JR21 (unpublished). 49pp.
Murakami, M. 1994. On long-term variations in hydrographic conditions in the Tohoku area. Bull.
Tohoku Natl. Fish. Res. Inst. 56: 47-56. (in Japanese with English abstract).
Pearcy, WG. 1991. Biology of the transition region. NOAA Tech. Rep. NMFS 105: 39-55.
Pearcy, WG., Fisher, JP., Anma, G. and Meguro, T. 1996. Species associations of epipelagic nekton of theNorth Pacific Ocean. Fish. Oceanogr. 5: 1-20.
Polovina JJ., Kobayashi, DR., Parker, DM., Seki, MP. And Balazs, GH. 2000. Turtles on the edge:
movement of loggerhead turtles (Caretta caretta) along oceanic fronts spanning longline fishinggrounds in the central North Pacific, 1997-1998. Fish. Oceanogr. 9: 71-82.
Polovina, JJ., Howell, E., Kobayashi, DR. and Seki, MP. 2001. The transition zone chlorophyll front, adynamic, global feature defining migration and forage habitat for marine resources. Prog. Oceanogr. 9:71-82.
Roden, GI. 1991 Subarctic-subtropical transition zone of the North Pacific: large-scale aspects andmesoscale structure. NOAA Tech. Rep. NMFS 105: 1-38.
Seki, MP., Polovina, JJ., Kobayashi, DR., Bidigare, RR. And Mitchum, GT. 2002. An oceanographic
characterization of swordfish (Xiphias gladius) longline fishing grounds in the springtime subtropicalNorth Pacific. Fish. Oceanogr. 11: 1-16.
Takahashi, M., Watanabe, Y., Kinoshita, T. and Watanabe, C. (2001) Growth of larval and early juvenile
Japanese anchovy, Engraulis japonicus, in the Kuroshio-Oyashio transition region. Fish. Oceanogr. 10:
235-247.
Tamura, T., Mogoe, T., Takai, K., Mori, M., Tsunekawa, M., Yoshimura, I., Ishikawa, U., Kawabe, S.,
Yamaguchi, F., Yamazaki, M., Ueta, E., Watamabe, H. and Eguchi, T. 2012. Cruise Report of the Second
Phase of the Japanese Whale Research Program under Special Permit in the Western North Pacific(JARPN II) in 2011 (part I) - Offshore component -. Paper SC/64/O3 presented to the IWC ScientificCommittee, June 2012 (unpublished). 18pp.
Watanabe, H., Kubodera, T., Masuda, S. and Kawahara, S. 2004. Feeding habits of albacore Thunnus
alalunga in the transition region of the central North Pacific. Fish. Sci. 70: 573-579.

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Watanabe, H., Kubodera, T. and Kawahara, S. 2006. Summer feeding habits of the Pacific pomfret Bramajaponica in the transitional and subarctic waters of the central North Pacific. J. Fih. Biol. 68: 1436-1450.
Watanabe, H., Kubodera, T. and Yokawa, K. 2009. Feeding ecology of the swordfish Xiphias gladius in
the subtropical region and transition zone of the western North Pacific. Mar. Ecol. Prog. Ser. 396:
111-122.
Watanabe, H., Fujiwara, G., Sawada, K., Matsuura, T., Fukuda, Y., Okazaki, M., Inagake, D., Yasunaga, G.,
Kiwada, H., Yoshida, H. and Miyashita, T. 2011. Cruise report of whale sighting and whale prey species
surveys in the offshore region of the western North Pacific in 2010. Appendix 1 of Paper SC/63/O2
presented to the IWC Scientific Committee, June 2011 (unpublished). 16pp.
Watanabe, H., Inagake, D., Okazaki, M., Tamura, T., Sawada, K., Matsuura, T., Fukuda, Y. and Miyashita,
T. 2012a. Cruise report of JARPN II whale prey species survey in conjunction with whale sampling
survey in the offshore region of the western North Pacific in 2011. Appendix 1 of Paper SC/64/O3
presented to the IWC Scientific Committee, June 2012 (unpublished). 10pp.
Watanabe, H., Okazaki, M., Tamura, T., Konishi, K., Inagake, D., Bando, T., Kiwada, H. and Miyashita, T.
2012b. Habitat and prey selection of common minke, sei, and Bryde’s whales in mesoscale during
summer in the subarctic and transition regions of the western North Pacific. Fish. Sci. 78: 557-567.

Fig. 1. Research track line of whale sighting and prey surveys conducted in late July-August 2012. Boldline indicates the area where cooperative whale sighting, sampling, and prey surveys were conducted.
Cooperative survey was conducted for Bryde’s whale.

27

Fig. 2. Survey and measurement items of whale sighting and prey surveys in relation to expected outputs and goals of these surveys. Relationship between thesesurveys and whale sampling survey was also depicted.

28

Fig. 3. Vertical temperature and salinity profiles, sighting positions of sei and Bryde’s whales,
geographical distributions of each small epipelagic fish species, and geographical distribution ofchlorophyll a at 20-30 m depth along track line in early summer 2011 (last year’s survey) (A) and latesummer 2012 (this year’s survey) (B). Surveys in these two years were conducted in the samegeographical areas between 156˚E and 159˚E. ▼: Sampling position of Bryde’s whale in 2012 during
cooperate whale sighting, sampling, and prey survey period (Bando unpubl. data).

29

Fig. 4. Distribution and south-north migration pattern of sei and Bryde’s whales and their prey species inrelation to primary production and oceanographic fronts in early (June) and late summers (lateJuly-August) in the boundary zone of sub-area 8 and 9. A thick arrow indicates range of the main habitatof each predator and prey species in relation to latitude.

Fig. 5. Temperature and salinity ranges of each depth layer in epipelagic zone at the position where sei
whale was sighted in June 2011 (last year’s survey) and late July-August 2012 (this year’s survey).

30

Fig. 6. Acoustic volume backscattering strength (SV) in the bottom at 70 (left) and 120 kHz (right).
Diamonds, triangles, and squares indicate 5 minutes integration values during drift period of the vessel at
the northernmost, middle, and southernmost points of the transect, respectively. Each symbol denotes
measured SV with protrusion of fishing and/or whale sonar and without protrusion. SP: the protrusion offishing sonar; W: the protrusion of whale sonar; W+SP: the protrusion of both sonars. ‘N→S’ indicates asailing from northern to southern area on the transect. ‘S→N’ indicates a sailing from southern tonorthern area on the transect.

Table 1. Results of sighting survey for large cetaceans in late July-August 2012.

Species
Bryde's whale
Sei whale
Sperm whale
Total

Schools Inds
58 72
15 19
27 96
100 187

Table 2. Date and positions of CTD cast station in 2012.
Latitude (N)Logitude (E)Latitude (N)Logitude (E)Stn Month Day Degree Minute Degree Minute Stn Month Day Degree Minute Degree Minute
1
7 28
38
7
156
15
21
8
7
41
31
157
0
2
7 28
38
19
156
37
23
8
8
42
2
158
3
3
7 28
38
37
157
16
24
8
8
42
16
158
25
4
7 29
39
4
158
7
25
8
9
42
42
158
38
5
7 29
39
17
158
25
27
8
9
42
55
158
10
6
7 30
39
27
158
49
28
8 10
43
14
157
54
7
7 30
39
44
158
31
30
8 11
43
33
156
55
8
7 31
37
55
156
18
31
8 11
43
49
156
39
9
7 31
37
42
156
39
32
8 12
45
41
159
2
10
8
1
37
9
157
43
33
8 12
45
18
158
32
11
8
1
37
11
157
54
35
8 13
45
16
158
11
12
8
2
36
43
158
34
37
8 14
44
44
157
29
13
8
2
37
11
157
48
38
8 14
44
30
156
60
14
8
3
40
10
157
42
39
8 15
44
29
156
43
16
8
4
40
27
156
52
40
8 15
43
58
156
5
17
8
5
41
1
156
2
41
8 19
35
2
138
51
18
8
5
41
17
156
34

31

Table 3. Research data of fluorescence survey in 2012.
Latitude (N)Logitude (E)Stn Month Day Degree Minute Degree Minute
2
7 28
38
19
156
37
4
7 29
39
4
158
7
6
7 30
39
27
158
49
8
7 31
37
55
156
18
10
8
1
37
9
157
43
14
8
3
40
10
157
42
15
8
3
40
12
157
46
21
8
7
41
31
157
0
23
8
8
42
2
158
4
25
8
9
42
42
158
37
28
8 10
43
14
157
55
30
8 11
43
33
156
55
32
8 12
45
41
159
2
35
8 13
45
16
158
11
37
8 14
44
44
157
29
39
8 15
44
29
156
43

Table 4. Volume of water filtered (ml) in each depth layer of each station in late July-August 2012.
Locality of each station was described in Tables 2 and 5.
Depth St No.
24(m)
0 196 195
10 207 205
30 165 240
50 195 170
100 205 250

6
205
227
260
210
260

8
210
155
200
190
190

10
220
215
220
235
230

12
225
-

14
210
205
195
180
235

17
235
-

21
225
250
240
240
230

23
240
220
240
255
250

25
200
255
225
220
195

28
250
255
250
245
230

30
215
250
245
220
250

32
215
225
240
235
245

35
250
240
245
260
240

Table 5. Sampling data of twin NORPAC net in 2012.
Latitude (N)Logitude (E)Latitude (N)Logitude (E)Stn Month Day Degree Minute Degree Minute Stn Month Day Degree Minute Degree Minute
1
7 28
38
7
156
14
21
8
7
41
31
157
0
2
7 28
38
19
156
37
23
8
8
42
2
158
4
3
7 28
38
37
157
16
24
8
8
42
16
158
25
4
7 29
39
4
158
8
25
8
9
42
42
158
37
5
7 29
39
17
158
25
27
8
9
42
55
158
10
6
7 30
39
27
158
49
28
8 10
43
14
157
55
7
7 30
39
43
158
31
30
8 11
43
33
156
56
8
7 31
37
55
156
18
32
8 12
45
41
159
2
9
7 31
37
43
156
40
33
8 12
45
18
158
33
10
8
1
37
10
157
43
35
8 13
45
16
158
11
12
8
2
36
43
158
33
37
8 14
44
43
157
29
14
8
3
40
10
157
42
38
8 14
44
31
157
0
16
8
4
40
27
156
52
39
8 15
44
29
156
43
17
8
5
41
1
156
2
40
8 15
43
58
156
5
18
8
5
41
17
156
34

32

37
250
260
260
255
250

39
220
230
245
240
245

Table 6. Sampling data of BONGO net in 2012.
Latitude (N)Logitude (E)Sampling Sampling
Stn Month Day Degree Minute Degree Minute depth (m) duration (min)
9
7 31
37
40
156
40
80
35
11
8
1
37
1
157
60
200
30
11
8
1
37
4
157
58
30
30
11
8
1
37
6
157
57
440
30
13
8
2
37
5
157
48
80
39
13
8
2
37
8
157
47
50
30
15
8
3
40
9
157
43
240
30
15
8
3
40
12
157
46
30
30
17
8
5
41
1
156
2
230
40
19
8
6
41
21
156
35
120
30
31
8 11
43
46
156
37
170
30
33
8 12
45
15
158
30
220
30
36
8 13
45
6
158
13
220
40
37
8 14
44
44
157
29
20
10
37
8 14
44
44
157
29
30
10
37
8 14
44
45
157
29
0-190
-

Table 7. Average values of measuring acoustic volume backscattering strength (SV) in the 300-350 m
depth in the various conditions of engine, sonars (protrusion or retraction), and relative wind direction.
R.P.M.: Rotation per minutes; One: one engine was used; Two: two engines were used; P: protruded; N:
non-protruded. All surveys were conducted in the daylight period.
No. Engine Ship speed Engine Propellar angle Whale Fishing Sonar Wind Avg. SV (dB) in 300-350 m depth(kt)
R.P.M.
(deg)
sonar
Sp-70
dir.
70 kHz120 kHz1
Two Clutch out 550
P
P
Side
-88.8
-75.9
2
Two Clutch in
550
P
P
Side
-88.7
-75.7
3
Two
8
550
16.7
P
P
Side
-83.9
-78.1
4
Two
8
550
16.7
P
P
Side
-84.6
-77.7
5
Two
9
550
18.2
P
P
Side
-82.7
-78.3
6
Two
9
550
18.2
P
P
Side
-81.9
-78.8
7
Two
10
550
21.5
P
P
Side
-79.7
-79.3
8
Two
10
550
21.5
P
P
Side
-80.9
-79.2
9
Two
11
550
23.6
P
P
Side
-78.8
-79.0
10 Two
11
550
23.3
P
P
Side
-78.2
-78.7
11 Two
10
550
18.4
N
N
Side
-88.5
-76.1
12 Two
10
550
19.2
N
P
Side
-87.8
-76.3
13 Two
10
550
20.7
P
N
Side
-78.0
-77.2
14 Two
10
550
17.1
N
N
Follow-88.2-76.1
15 One
8
650
12.3
N
N
Side
-83.6
-77.6
16 One
8
650
12.3
N
N
Side
-82.6
-77.7

33