SC/57/O4

SC/57/O4

Cruise report of the coastal survey on common minke whales off
Kushiro, northeast Japan: the 2004 JARPN II survey (Part II) Coastal component.
TOSHIYA KISHIRO1, HIDEHIRO KATO1, HIDEYOSHI YOSHIDA1, TOMIO MIYASHITA1, TAMEO RYONO2,
SHIGEO TABATA2, RYOSUKE OKAMOTO2, KUNIHIRO YASUI2, HITOMI SATO2, YUKA MORITA2,SHIGEO SAINO2, TAKAHIRO HARA2, TADASHI EBISUI2, HISASHI KUROISHI1, SHIGETOSI NISHIWAKI2
AND SHIGEYUKI KAWAHARA

1Contact e-mail: kishiro@affrc.go.jp
1

National Research Institute of Far Seas Fisheries, 5-7-1, Shimizu-orido, Shizuoka, 424-8633, Japan

2

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

ABSTRACT
Based on the results of a two-year feasibility study conducted in 2002 and 2003, the coastal component of JARPN II
was revised to be conducted twice a year and 60 common minke whales would be sampled in spring and autumn
seasons, respectively. The first survey of revised JARPN II coastal component was conducted from 13 September to
31 October, off Kushiro, northeast Japan (northern part of the sub-area 7), using four small-type whaling catcher
boats, one echo sounder-trawl survey vessel and one dedicated sighting survey vessel. In addition, dedicated sighting
survey using one small-type whaling catcher boat was tentatively introduced. The sampling was conducted in the
coastal waters within the 50 nautical miles form the Kushiro port, and all whales sampled were landed on the land
station in the Kushiro port for biological examination. During the survey, a total of 6,923.9 n. miles (635.4 hours) was
searched for whale sampling, 151 schools/ 156 individuals of common minke whales were sighted and 59 whales
were sampled. Average body length of sampled whales was 6.87m (SD=0.80, n=47) for males and 6.00m (SD=1.09,n=12) for females, respectively. Dominant prey species found in the forestomach contents were Japanese anchovy
Engraulis japonicus (62.1%) and Pacific saury Cololabis saira (31.0%). The concurrent prey survey revealed the
distribution of those prey species in the research area, and the dedicated sighting survey sighted 17 schools/ 18
individuals of common minke whales with 809.4 n. miles searched. As compared with the results of the 2002 survey
off Kushiro, body length frequency of the whales inclined toward the large-sized male, and composition of preyspecies found in the forestomach was comparatively simple. These results revealed yearly changes in migration andfeeding habits of common minke whales in the coastal waters off Kushiro in autumn season, and suggested thosechanges might be related to yearly variation in the environmental factors such as the oceanographic conditions anddistribution of prey species. To evaluate a long term competition between whales and fisheries in local areas, and toclarify the role of the whales in the marine ecosystem, further surveys should be conducted on a yearly basis.

KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; FOOD/PREY; ECOSYSTEM; SCIENTIFICPERMITS

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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

INTRODUCTION
The full-scale surveys of the Japanese Whale Research Program under Special Permit in the western
North Pacific (JARPN II) started in 2002 (Government of Japan, 2002). The objectives of thesurveys are: i) feeding ecology and ecosystem studies, involving prey consumption by cetaceans,
prey preferences of cetaceans and ecosystem modeling, ii) monitoring environmental pollutants incetaceans and marine ecosystem, and iii) stock structure of whales (Government of Japan, 2002).
The full-scale JARPN II involves two survey components; ‘offshore’ which is covered by the
Nisshin Maru research fleet and ‘coastal’ which is covered by small-type whaling catcher boats, andthe latter one is necessary to cover the temporal and spatial gaps, which can not be covered by the
Nisshin maru research fleet (Government of Japan, 2002).
In the original JARPN II plan, the coastal component was presented as a two-year feasibility study to
examine the logistic aspects of the methodology (Government of Japan, 2002). First survey was
carried out in the coastal waters off Kushiro, northeast Japan, during 10 September to 12 October
2002 (Kishiro, et al., 2003) and second survey was conducted in the waters off Sanriku district, from
8 April to 2 May 2003 (Yoshida, et al., 2004). Both surveys took 50 common minke whales,
respectively, in the coastal waters within a 30 nautical miles radius from each survey area. Afterdetailed examination of the results of the logistic aspects of both 2002 and 2003 surveys, it was
concluded that no substantial problem occurred and the coastal survey could be continued as acomponent of the JARPN II using same kind of vessels (small-type whaling catcher boats) andmethodology (Kato, et al., 2004). However, re-calculation of required sample size using dataobtained from both surveys suggested that sample size should be modified to be at least 60
individuals in each area/season (Tamura, et al., 2004a), and taking account of 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, 2004a).
Based on these results, revised JARPN II research plan was submitted to the 56th IWC/SC annual
meeting (Government of Japan, 2004b). The coastal survey component was revised to be conducted
twice a year and 60 common minke whales would be sampled in spring and autumn seasons,respectively. The technical methodology was almost same as the former surveys, i.e. the survey
consisted of three research components as follows; 1) coastal whale sampling survey by small-typewhaling catcher boats, 2) coastal prey species survey by one echo sounder-trawl survey vessel and 3)
dedicated sighting survey by one research vessel. In addition, dedicated sighting survey using one
small-type whaling catcher boat was tentatively introduced to examine the logistic capability of theboat for acting as a sighting research vessel. The coastal survey was authorized by the Governmentof Japan in compliance with Article VIII of the international convention for the Regulation of
Whaling. The National Research Institute of Far Seas Fisheries (NRIFSF), Fisheries Research2

SC/57/O4

Agency, planned and conducted this survey entrusted by the Institute of Cetacean Research (ICR).
In this paper, we presented an outline of the first survey of revised JARPN II coastal component
conducted in the waters off Kushiro, northeast Japan, from 13 September to 31 October 2004.
MATERIALS AND METHODS
Research area
The research area was same as the 2002 survey (Kishiro, et al., 2003), i.e. the coastal waters off
Kushiro, within the 30 nautical miles (maximum 50 n. miles) form the Kushiro port (Fig. 1). This
area coincided with the northern part of the sub-area 7 determined by the IWC.
Research vessels and land station
Whale sampling survey and sighting survey
Four small-type whaling catcher boats (Taisho Maru No. 28 (hereafter referred as 28T; 47.3GT),
Koei Maru No.75 (75K; 46.0GT), Sumitomo Maru No.31 (31S; 32.0GT) and Katsu Maru No.7 (7K;
32.0GT) were used as sampling and/or dedicated sighting vessels. The sampling survey was
conducted from 13 September to 31 October. All whales sampled were landed on the land station(the JARPN II research station) in the Kushiro port for biological examination of the whales and theby-products.
Prey species survey
The Shunyo Maru (SYO; 887.0GT) conducted the echo sounder-trawling survey in wider researcharea off east coast of Hokkaido, from 24 to 29 September. This vessel also conducted thehydrographic observations using the conductivity-temperature-depth profiler (CTD). Detail of thesurvey is shown in Appendix 1.
Large-scale dedicated sighting survey
The Kyoshin Maru No.2 (KS2; 372.0GT) was engaged as a dedicated sighting survey vessel. Thissurvey was conducted from 9 to 27 September, following the predetermined zigzag-shaped tracklines in the identical research area, where the prey species survey was carried out. Detail of thesurvey is shown in Appendix 2.
Dedicated sighting survey by small-type whaling catcher boat
In order to examine the logistic capability of the small-type whaling catcher boats for acting as thesighting research vessels, one of four catcher boats alternatively carried out the dedicated sighting
surveys from 13 September to 4 October. The survey area was established in the coastal waters
within 50 nautical miles from the Kushiro port with small blocks (A to D) and systematicallydesigned track lines (Fig.2). The survey largely followed the guidelines of Hammond (1986) and3

Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

Hammond and Donovan (1993). Searching was carried out at 10 knots during the day and thevessels returned to the port every night. The vessel cruised along the predetermined cruise trackusing closing mode, principally closing on primary sightings to confirm species and school size.
After closing, the vessel returned to the nearest point on track line that had not been surveyed andresumed searching. Generally, searching was only conducted when the sea conditions were below
Beaufort 3 and visibility was more than 1.5 miles. Searching was carried out from the top barrel (6 to7 m above the water surface) by two persons. Similar sighting data forms to those developed forJapanese North Pacific whale sighting cruises were completed. Weather and sea conditions wererecorded each hour. The experiments to evaluate the accuracy of estimated distances and angles fromthe top barrel were carried out in the first day of the survey for each vessel.
Sampling survey by small-type whaling catcher boat
As same as the former surveys in 2002 and 2003 (Kishiro et al., 2003, Yoshida et al., 2004), theresearch head office was placed in the research station and controlled the sampling vessels during thesurvey. All catcher boats except for one which was engaged as the dedicated sighting vessel carriedout the sampling survey. To avoid the concentration of sampling location, two types of the sampling(searching) measure were tentatively introduced as follows.
Type 1 sampling
The research area was divided into four sectors based on the direction from the port (Fig. 3). The
searching area of sampling vessels was allocated to one of those sectors. The sector was selected inevery day in random turn. After all sectors were surveyed (usually, it took 4 days), type 2 sampling
was started.
Type 2 sampling
The searching area and route of the sampling vessels were determined from information on whale
distribution obtained by type 1 sampling survey and dedicated sighting survey, weather conditions
and information on fishing grounds.
In each vessel, a researcher was on boarded and recorded the cruise tracks, searching time on effort,
sea weather conditions and sighting data. Sighting was conducted from the top barrel and upper
bridge by all the crews and researcher. All common minke whales sighted were targeted for sampling,
except for the cow-calf pair. When a sighting consisted of more than one animal, first targetedanimal was selected following the random sampling digits. Sampling was made by 50 mm whaling
cannon. Once the vessel sampled the whale, she returned to the Kushiro port as soon as possible, toland the animal on the research station. At the port, the sampled whale was lift up from the vesselusing wire nets and a crane and transported to the station by a 11 tons freight trailer. At that time,
body weight of the whale was measured with the truck scale.
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Biological research for common minke whales sampled
All sampled whales were biologically examined by researchers at the research station. Research
items of the biological studies were summarized in Table 4, with the number of data and samples
obtained. These items were related to studies on feeding ecology, stock structure, life historicalbiology and pollutions.
RESULTS
Dedicated sighting survey by small-type whaling catcher boat
Searching effort and the number of sightings of common minke whales made by the dedicatedsighting vessels (small-type whaling catcher boats) are listed in Table 1. Cruise tracks and sighting
positions of common minke whales are shown in Fig. 4. In the first period from 13 to 16 September,the survey was conducted as the exercise cruises in block B with the experiments for estimation ofsighting distances and angles. Since, there was no practical problem in conducting the survey, thesecond and third periods covered all small blocks, respectively. In the second period from 17 to 23
September, common minke whales were sighted in block A and B (within 30 n.miles of the coast),
but in the third period from 24 September to 4 October, the whales were sighted in block C and D(around 50 n.miles from the coast). Total searching distance and time were 641.8 n. miles and 60.1
hours, respectively. A total of 16 schools/16 individuals of common minke whales were primarysighted and 1 school/1 individual of the whale was secondary sighted during the surveys.
Effort and sightings by the sampling vessels
The cruise tracks made by the sampling vessels (28T, 75K, 31S and 7K) during the survey are shownin Fig.5. The searching areas covered widely coastal waters within 30 nautical miles form theKushiro port. Searching distance and time are shown in Table 2. Here, we defined the searching
distance and time as that with sighting effort, i.e. the periods of the searching conducted from the top
barrel. During the research period, total searching distance and time were 6,923.9 n. miles and 635.4
hours, respectively.
Fig.6 shows the distribution of common minke whales sighted by the sampling vessels. The sighting
positions widely distributed in the inshore areas off Kushiro port to the waters in around 30 n. miles
from the port. During the survey, a total of 151schools/ 156 individuals of common minke whales
were sighted, consisting of 142 schools/ 146 individuals of primary sightings and 9 schools/ 10
individuals of secondary sightings (Table 2). These figures probably include some duplicatedsightings because sampling vessels searched almost same areas in every day. In addition,
Humpback whales (2 schools/ 2 individuals) and sperm whales (1 school/ 2 individuals) weresighted during the survey (Table 2).

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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

The temporal change in density index (SPUE: number of schools primary sighted per one hoursearching, and DI: number of schools primary sighted per 100 n. miles searching) of common minke
whales obtained by the small-type whaling catcher boats are listed in Table 3. There was no criticaldifference in the figures between the sampling and sighting surveys, and both SPUE and DI
decreased from the middle of September to late of October. During the total research periods, 0.22
schools was primary sighted per one hour searched, and 2.05 schools was primary sighted per 100 n.
miles searched by the sampling survey. These figures are nearly the half of that recorded in theformer survey conducted in Kushiro 2002 (Kishiro, et al., 2003).
Sampling of common minke whales
A total of 59 common minke whales were sampled. In the sampling process, one individual was
harpooned but missed by the technical reason (the cases of struck and lost). Fig.6 showed sighting
positions of sampled whales. Distribution of these whales almost covered all of the areas where thesightings were made during the research period.
Prey species survey and large-scale dedicated sighting survey
The prey species survey was conducted using the echo sounder-trawling vessel (SYO) to investigate
the distribution and abundance of the prey species in the wider areas from Cape Erimo (143º15’E)

to Cape Nosappu (about 146º00’E)) and north of 41º00’N. Japanese anchovy, walleye pollack andPacific saury were found by the survey but common squid was not found. The large-scale dedicatedsighting survey using sighting vessel (KS2) were conducted in the same research areas of the preyspecies survey, and sighted 17 schools/18 individuals of common minke whales with 809.4 n.miles
searched.

Results of these surveys were described in Appendix 1 (the prey species survey),

Appendix 2 (the large-scale dedicated sighting survey) and Appendix 3 (the oceanographic
observations).
Sex ratio, body length and weight of sampled whales
The 59 sampled whales were consisted of 47 males and 12 females (sex ratio of males was 0.797).
Average body length of the whales was 6.87m (max=7.95, min=4.65, SD=0.80) for males and 6.00m(max=8.07, min=4.27, SD=1.09) for females, respectively (Table 5). Average body weight was 4.23
tons (max=6.36, min=1.18, SD=1.31) for males and 2.72 tons (max=5.64, min=0.88, SD=1.47) for
females, respectively (Table 6). In males, both the average body length and the average body weightdecreased during the seasons from the middle of September to late of October. In females, averages
were the lowest in the middle of September but sample size was small.
Composition of sex and sexual maturity of common minke whales is listed in Table 7. In males, 31
of 47 individuals were sexually mature (66.0%). On the other hand, in females, the ratio of sexuallymature individuals was only 16.7% (two of 12 individuals). Pregnant or lactating female was not6SC/57/O4

observed.
Pray species of common minke whale found in the stomach contents
Except for 1 stomach destroyed by the harpoon, we could examine 58 stomach contents of common
minke whales. Following the same methods conducted in the JARPN II feasibility surveys (Fujise, etal., 2002) stomach contents were weighted to the nearest 0.1 Kg by each four chamber in both casesof including and excluding liquid. Then, a sub-sample of forestomach contents was collected andfrozen for the later laboratory work. Major prey species found in the forestomach contents wereJapanese anchovy Engraulis japonicus (62.1%, 36 out of 58 whales) and Pacific saury Cololabis
saira (31.0%, 18 whales). Walleye pollock Theragra chalcogramma (3.4%, 2 whales) and Krill(3.4%, 2 whales) were also observed but Japanese common squid Todarodes pacificus (which was
found in the samples corrected in 2002 Kushiro survey) was not observed. The range of forestomach
contents weights was form 3.0Kg to 80.8Kg, and the maximum of % body weight was 1.6 %. This
whale fed on Pacific saury.
By-products of the whales
After biological examination, all whales sampled were processed according to the International
Convention for Regulation of Whaling, Article VIII. A total weight production including meat andblubber was 140.2 tons.
DISCUSSION
The present survey was the first survey of the revised JARPN II coastal component to take 60
common minke whales in the coastal waters of Japan. There was no practical problem in conducting
the surveys as same as the 2002 and 2003 surveys. However, we could not obtain the planed sample
size (we collected a total of 59 individuals). One of the reasons is thought to be bad weather
condition during the research period. In 2004 autumn season, we got a twice of typhoons and several
impacts from the low atmospheric pressures. Big waves and strong winds seriously prevent to
conduct the surveys with small boats (32-47.6GT) and as a result, more days were spent to thesurvey (research period was 49 days form 13 September to 31 October in 2004 as compared with 33
days from 10 September to 12 October in 2002). A typhoon also partly prevented activities of large
vessel (887GT) in the prey species survey (Appendix 1).
Another reason is thought to be related to yearly change in the timing of the migration of common
minke whales into restricted coastal area. As compared with the results of the 2002 survey off
Kushiro, sex ratio of males in the samples was higher and body length frequency of the whales
inclined toward large-sized mature males (Fig. 7). The distribution of the whales in the survey area
was relatively dispersed with low density of the sighted whales (Fig. 6 and Table 3) and theconcentrated area observed in the 2002 survey (near the continental shelf and slope in the southeast
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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

region from the Kushiro port) was not detected. Minke whale is well known to have segregation in
their migration as the predominance of females around the northern limit of their distribution in boththe Southern Hemisphere (Kato, et al., 1990) and off northern Japan (Wada, 1989), and coastal
waters off Kushiro is thought to be located in the migration corridor of their north-south migration.
In the case of Gary whales, it is known that females generally migrate earlier than males and adults
earlier than sexually immature whales in their coastal north-south migration (Wolman, 1985). These
implied that the differences observed in the composition of samples between the 2002 and 2004
surveys might be related to the difference of the timing of the migration of whale groups to thesurvey area, and suggested that the migration of main groups including mature females into thecoastal waters off Kushiro was scarce at the time in 2004 survey period.
Furthermore, composition of prey species found in the stomach contents was also different andapparently simple than that of the 2002 surveys (Fig.8). These changes were related to the differenceof the prey species distribution and oceanographic conditions between the years revealed by the preyspecies surveys (Appendix 1 and 3). These environmental differences possibly affect the change inmigration of common minke whales into the coastal area.
In the present survey, the dedicated sighting survey using small-type whaling catcher boats wastentatively introduced and conducted with no serious problem. However, it was difficult to continue
the survey through the research period due to the logistic reasons such as the difficulty in collecting
the whales by limited number of sampling vessels and the shortage of the boats for acting as the
sampling vessels. The sighting survey area was also restricted in small area compared with thelarge–scale dedicated sighting survey due to the capability of the boat. Thus, the dedicated sighing
survey using small boat was suspended in 4 October and all of the boats had acted as sampling
vessels from 5 October. Taking account of these situations, we recommend that large-scale dedicatedsighting survey using large vessel will be still needed in future survey even if the small-type whaling
catcher boats could be used as a dedicated sighting vessel in the restricted survey area.
Based on the results of the 2002 surveys, prey preferences of common minke whales and interaction
between common minke whales and fisheries were preliminary examined and presented to the 56th
IWC/SC annual meeting (Tamura, et al., 2004b; Kawahara, et al., 2004). However, the present
survey revealed large yearly change in migration and feeding habit of common minke whales in the
coastal waters off Kushiro in autumn season and suggested that those changes might be related to
yearly change in the environmental factors such as the oceanographic conditions and distribution of
prey species. To evaluate a long term competition between whales and fisheries in local areas, and toclarify the role of the whales in the marine ecosystem, further surveys should be conducted on a
yearly basis.

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ACKNOWLEDGMENTS
The authors are greatly indebted to Dr. Hiroshi Hatanaka, the project leader of the full-scale JARPN
II surveys, the Institute of Cetacean Research (ICR), Dr. Seiji Ohsumi (ICR) and Mr. Hideki
Moronuki, the Fisheries Agency of Japan for their guidance and implementation of the research. We
thank to all crew of the research vessels and all staff of the land station and the Japan small-typewhaling association. We also thank to the staff of the Kushiro City and the Kushiro Fisheries
Cooperative Union for their kind assistance in the implementation of the research.
REFERENCES
Fujise, Y., Tamura, T., Bando, T., Watanabe, H., Kiwada, H., Otani, S., Kanda, N., Yasunaga, G.,
Mogoe, T., Konishi, K., Inamori, M., Shigemune, H. and Tohyama, D. 2002. Cruise report of thefeasibility study of the Japanese Whale Research Program under Special Permit in the western
North Pacific-Phase II (JARPN II) in 2001. Paper SC/54/O16 submitted to the 54th IWC ScientificCommittee, 51pp.
Government of Japan, 2002. Research plan for cetacean studies in the western North Pacific under
special permit (JARPN II). Paper SC/54/O2 submitted to the 54th IWC Scientific Committee.
Government of Japan (Fujise, Y., Tamura, T., Kato, H. and Kawahara, S. eds.), 2004a. Someconsiderations of the feasibility components of the JARPN II research plan. Paper SC/56/O2
submitted to the 56th IWC Scientific Committee, 36pp.
Government of Japan, 2004b. Revised research plan for cetacean studies in the western North Pacificunder special permit (JARPN II). Paper SC/56/O1 submitted to the 56th IWC ScientificCommittee, 14pp.
Hammond, P. S. 1986. Line transect sampling of dolphin populations. Pp.251-279. In: M. M. Bryden
and R. Harrison (eds.) Research on Dolphins. Clarendon Press, Oxford. 478pp.
Hammond, P. S. and Donovan, G. P. 1993. Suggestions for draft guidelines for conducting surveys
and analyzing data. Paper SC/45/O13 submitted to the 45th IWC Scientific Committee, 18pp.
Kato, T., Kishino, H. and Fujise, Y. 1990. Some analyses on age composition and segregation ofsouthern minke whales using samples obtained from the Japanese feasibility study in 1987/88.
Rep. int. Whal. Commn 40: 249-256.
Kato, H., Kishiro, T., Yoshida, H. and Kawahara, S. 2004. Feasibility of coastal surveys in the
JARPN II, from the viewpoint of logistics. Appendix 1, pp4-12. In: Government of Japan (Fujise,Y., Tamura, T., Kato, H. and Kawahara, S. eds.), Some considerations of the feasibility
components of the JARPN II research plan. Paper SC/56/O2 submitted to the 56th IWC ScientificCommittee, 36pp.
Kawahara, S., Kishiro, T., Tamura, T., Murase, H., Kiwada, H. and Nishiwaki, S. 2004. Preliminary
estimation of prey selection of minke whales based on JARPN II coastal survey off thesoutheastern Hokkaido in September-October 2002. Paper SC/56/O18 submitted to the 56th IWC
Scientific Committee, 15pp.
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Kishiro, T., Kato, H., Ohizumi, H., Yoshida, H., Saito, T., Isoda, T., Tabata, T., Sakakibara, M., Saino,
S., Hara, T., Hayashi, T., Miyashita, T., Fukudome, K., Kiwada, H. and Kawahara, S. 2003. Reportof the 2002 JARPN II survey in the western North Pacific. Part II: Coastal component – Coastal
survey off Kushiro, northeast Japan. Paper SC/55/O8 submitted to the 55th IWC ScientificCommittee, 26pp.
Tamura, T., Hakamada, T., Konishi, K., Fujise, Y., Kishiro, T., Yoshida, H., Ohizumi, H. and Kato, H.
2004a. Recalculation of sample size of common minke whales in coastal areas required for
estimating consumption of various prey items based on results of JARPN II. Appendix 2, pp13-17.
In: Government of Japan (Fujise, Y., Tamura, T., Kato, H. and Kawahara, S. eds.), Someconsiderations of the feasibility components of the JARPN II research plan. Paper SC/56/O2
submitted to the 56th IWC Scientific Committee, 36pp. Paper SC/56/O16 submitted to the 56th
IWC Scientific Committee, 36pp.
Tamura, T., Konishi, K., Hakamada, T., Matsuoka, K., Murase, H., Miyashita, T., Kishiro, T.,
Ohizumi, H., Kato, H., Kawahara, S. and Fujise, Y. 2004b. Preliminary analyses of interaction
between common minke whales and fisheries off Kushiro region. Paper SC/56/O16 submitted to
the 56th IWC Scientific Committee, 16pp.
Wada, S. 1989. Latitudinal segregation of the Okhotsk Sea-West Pacific stock of minke whales. Rep.
int. Whal. Commn 39: 229-233.
Wolman, A. A. 1985. Gray whale Eschrichtius robustus (Lilljeborg, 1861), Pp.67-90. In: S. H.
Ridgway and R. J. Harrison (edc.), Handbook of Marine Mammals Vol.3. The Sirenians andBaleen Whales. Academic Press, London. 362pp.
Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Ryono, T., Tabata, S., Sakakibara, M.,
Saino, S., Hara, T., Hayashi, T., Tomizawa, Y., Tamai, K., Okamoto, R., Fukuoka, M., Watanabe,H., Tsunekawa, M. and Kawahara, S. 2004. Report of the coastal survey on common minke
whales off Sanriku coast, northeast Japan: the Japanese whale research program under special
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Appendx 1
Coastal prey species survey of JARPN II in 2004
SHIGEYUKI KAWAHARA1, SHIROH YONEZAKI1, MORIO ICHIHARA2, AND HIROTO MURASE3123

National Research Institute of Far Seas Fisheries, Orido 5-7-1, Shimizu-ku, Shizuoka 424-8633, Japan
Field Center for Northern Biosphere, Hokkaido University, Minato-cho 3-1-1, Hakodata, Hokkaido
041-8611, JapanThe Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo 104-0055, Japan

Contact e-mail:kawahara@fra.affrc.go.jp

ABSTRACTPrey species surveys were conducted in cooperation with the sampling surveys for sei and minke whales in
September 2004 as a part of JARPN II study. Offshore and coastal surveys were conducted in the western
North Pacific and off Kushiro, Hokkaido, respectively. The primary objective of the coastal survey was to
examine prey environment and prey preference of minke whale during autumn. The distribution andabundance of the prey species were investigated with the quantitative echosounder (EK60) and midwater
trawl of a trawler-type research vessel, Shunyo-maru, during the daytime. Acoustic data were acquired bysteaming at about 10 knots along the track lines with operating frequency at 38, 70 and 120 kHz. Species
and size compositions of acoustical backscatterings were identified by midwater trawl. Dense schools ofJapanese anchovy and walleye pollack were found in the acoustic survey. CPUE was low for Pacific saury
and no catches for common squid. The results coincided with the information from the fisheries and weredifferent from those in September 2002, suggesting large yearly changes in the prey environment
surrounding minke whales.

INTRODUCTION
The government of Japan submitted the Research Plan for Cetacean Studies in the Western North
Pacific under Special Permit (JARPN II) (Feasibility Study Plan for 2000 and 2001) to the 52nd
IWC/SC (Government of Japan 2000). The overall goal of JARPN II is to contribute to theconservation and sustainable use of marine living resources including whales in the western North
Pacific, especially within Japan’s EEZ (Government of Japan, 2002). The priority of this plan is to
examine feeding habits of major cetacean species and ecosystem studies, including studies on prey20

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consumption by cetaceans, prey preference (selection) of cetaceans, and ecosystem model. In
JARPN II, prey species surveys are conducted in cooperation with the whale surveys to estimate theprey selection of cetaceans. Since 2002, JARPN II has started a new coastal survey for minke whale
using small-type whaling catcher boats. In 2004, the cooperative whale/prey surveys were conductedin the offshore region of the western North Pacific and the coastal region off Kushiro, Hokkaido.
The objective of this survey was to examine prey environment in autumn for minke whales. This
document presents the preliminary results of the prey species survey in the coastal region.

MATERIALS AND METHOD
Survey area and period
The cooperative prey species survey was conducted in September 2004 with two periods; first from
September 15 to 19 in the offshore region (Sub-area 9) and second from September 24 to 29 in the
coastal region off Kushiro, Hokkaido (Sub-area 7), by Shunyo-maru (887 GT) of National ResearchInstitute of Far Seas Fisheries (Fig. 1). The itinerary of the survey was shown in Table 1. Timedifference between the whale and prey species surveys was less than about one week so that theresults were comparable. Research hour was from an hour after sunrise to an hour before sunset
while the maximum research hours were set at 13 hours. Generally, the survey started at 5:00 and
ended at 18:00 at local time.
The coastal survey area is divided into inshore and offshore sides and track lines were set to cover
the both sides (Fig. 2). The track lines were set independently from whale survey. The waypoints oftrack lines were shown in Table 2. The distribution and abundance of the prey species were
investigated with the quantitative echosounder and the midwater trawl. CTD casts were conducted
down to 500 m or near the bottom at each sampling station to measure vertical temperature andsalinity profiles in the study area.
Trawl sampling
The midwater trawl net used was 86.3 m long with a mouth opening of ca. 900 m2 and a 6.0 m cod
end with a 17.5 x 17.5 mm mesh inner. The sampling depth and the height of the mouth of the net
were monitored with the Scanmer transducers attached to the head and the bottom rope of the trawl.
Towing speed of the trawl net was 4-5 knot. In this study, all samples were collected during daylightperiod. Two types of trawl samplings, the trawlings with floats in the surface layer and the stairs-like
mid-water trawlings from the depths around 150 m, were conducted. The purpose of these samplings
was to examine the abundance and distribution pattern of squids and neustonic animals (especiallycommon squid and Pacific saury) that are difficult to detect with the echosounder. Also the samples
were used to identify the species and size of acoustical backscatterings. Surface trawlings were madewith floats at 0-30 m layer for 30-40 minutes in the area where Pacific saury seemed to be21

Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

distributed. Stairs-like trawlings were made at three layers shallower than 150 m (0-50 m, 50-100 m,
and 100-150 m). During the coastal survey, surface and stairs-like trawlings were made four and 10
times (Table 3).
All samples were identified to the lowest taxonomic level possible and wet weight of each species
was measured aboard the ship. For the major species, body length of 100 individuals was measured
to examine their size composition. A part of samples were frozen at –30°C for further analysis in thelaboratory.
Acoustic data acquisition and analyses
During the daytime, the ship steamed at around 10 knots along the track line. To record acoustic dataa quantitative echo sounder (Simrad EK60 with program version 1.4.3.64) with operating frequency
at 38, 70 and 120 kHz was used. The transducers were hull-mounted at the depth of 4.3 m from thesurface. Calibrations were carried out off the coast of Kushiro in September 23 using the copper
sphere technique described in EK 60 online help manual.
Acoustic data are being analyzed now with the aid of Sonar Data Echoview (version 3.00.74.01) at
the laboratory. In principle, backscattering on the echosounder is identified based mainly on the
result of trawl samplings. For fishes, data collected at 38 kHz are used with the threshold set at-60dB and the depth range from 10 m to 250 m. For Japanese anchovy and walleye pollack, school
shape and backscattering intensity of backscattering are also used for species identification. For
krills, data collected at 120 kHz are used with the threshold set at –80 dB. The analyzed depth range
is from 12 m to 250 m (maximum depth at 120 kHz). Backscattering is identified as krills if ∆Sv (thedifference of Sv between 38 and 120 kHz) falls between 10 and 15 dB (Miyashita et al. 1997).
Because most of krill species in the survey area have the body length similar to isada krill(Euphausia pacifica) taken in the coastal area off Tohoku, this ∆Sv value is applied to. Species
identification is based on ∆Sv. The integration is made at an interval of one nautical mile by 50 m
depth zone.

RESULTS AND DISCUSSION
Due to the time constraints caused by a typhoon, the track lines in the offshore side were not covered.
While the acoustic data and oceanographic conditions are being analyzing now, the preliminary
results are as follows.
CTD data indicated that the temperature in the coastal region off Kushiro was low due to the
Oyashio Current while the temperature was relatively higher in the northern (continental shelf) andsouthern (oceanic water) parts in the survey area. In the acoustic survey, dense schools of Japanese22

SC/57/O4

anchovy were mainly found on the eastern continental shelf. Japanese anchovy sampled were mainly
consisted of large-sized fish (11-14 cm SL). Walleye pollack (35-54 cm FL) was found along theedge of the continental shelf. Although middle-sized Pacific saury was caught at some stations in thecentral and eastern parts, the CPUE (kg/h) was low. In this fishing season the southern migration ofPacific saury was delayed due to the higher water temperature and a large warm eddy. No common
squid was caught by the mid-water trawlings during the survey. The results of the survey coincidedwith the information from the fisheries and were different from those in the first survey off Kushiroin September 2002 (Kawahara et al., 2003), suggesting large yearly changes in the prey environment
surrounding minke whales.
During the survey the acoustic data were also collected by Kyoshin-maru No. 2 that carried out the
dedicated sighting survey in the same area. The data will be analyzed together with those from
Shunyo-maru to estimate the prey preference of minke whales.

ACKNOWLEDGEMENT
A special thank is given to the crews and researchers for their dedication in collecting data. The
authors would like to thank Dr. Hiroshi Hatanaka (The Institute of Cetacean Research, Japan). Dr.
Kazushi Miyashita (Hokkaido University) provided useful comments on acoustic data analysis.
REFERENCES
Government of Japan. 2000. Research plan for cetacean studies in the western North Pacific underSpecial Permit (JARPN II) (Feasibility Study Plan for 2000 and 2001). Paper SC/52/O1
submitted to the 52nd IWC Scientific Committee Meeting.
Government of Japan. 2002. Research plan for cetacean studies in the western North Pacific underSpecial Permit (JARPN II). Paper SC/54/O2 submitted to the 54th IWC Scientific Committee
Meeting.
Kawahara, S., Kiwada, H., Suenaga, Y. and Kataoka M. 2003. 2002 prey species survey (coastal
component) of JARPN II. Appendix 1, pp 15-22. In: Kishiro, T., Kato, H., Ohizumi, H., Yoshida,
H., Saito, T., Isoda, T., Tabata, S., Sakakibara, M., Saino, S., Hara, T., Hayashi, T., Miyashita, T.,
Fukudome, K., Kiwada, H. and Kawahara, S. 2002. Report of 2002 JARPN II survey in thewestern North Pacific. Part II: Coastal component – Coastal Survey off Kushiro, northeast Japan.
Paper SC/55/O8 submitted to the 55th IWC Scientific Committee Meeting, 26 pp.
Miyashita, K., Aoki, I., Seno, K., Taki, K. and Ogishima. 1997. Acoustic identification of isada krill,
Euphausia pacifica Hansen, off the Sanriku coast, north-eastern Japan. Fish. Oceanogr. 6.
266-271.

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Appendix 2
Cruise report of the dedicated sighting survey in 2004 JARPNII
coastal survey off Kushiro, northeast Japan.
SHIGETOSHI NISHIWAKI, HIROSHI KIWADA, MASAKATSU MORI, TAKUYA TERAOKA,
KOJI MATSUOKA
The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku Tokyo, 104-0055, Japan
Corresponding E-mail address: nisiwaki@cetacean.jpl
ABSTRACT
A cetacean sighting survey using the line transect method was conducted concurrently with the whale
sampling and the whale prey surveys off the coast of Kushiro, Hokkaido, Japan in September 2004 as a partof coastal component of 2004 JARPN II full scale study. The primary objective of the sighting survey wasabundance estimation of baleen whale in the survey area. The research vessel Kyoshin-Maru No.2 wasdedicated to the sighting survey. Total searching distances were 809.4 n.miles. A total of 53 individuals of
43 schools primary sightings were made. They included 18 common minke and 25 sperm whales.

INTRODUCITON
A cetacean sighting survey using the line transect method was conducted concurrently with thewhale sampling and the whale prey surveys off the coast of Kushiro, Hokkaido, Japan in September
2004 as a part of coastal component of 2004 JARPN II full scale study (Government of Japan, 2004).
The primary objective of this survey was to estimate baleen whale abundance in the coastal
component survey area. Preliminary results of the cetacean sighting survey are presented in thispaper.
MATERIALS AND METHODS
The cetacean sighting survey was conducted in small survey block “7N”, which were set within
Sub-area 7 as northern part from latitude 41-00N (Fig 1). Near shore area of the survey block where
the water depth is less than 50m, was not surveyed because many fisheries gears were set in there.
The survey block was further divided into the coastal and offshore area. The boundary between
coastal and offshore area was set on the line parallel to the coastline and the distance between theboundary and coastline was 60 n.miles. The survey was conducted from 10 to 27 September 2004.
Details of itinerary were shown in Table 1. Kyoshin-maru No.2 (KS2, 372GT) engaged in the
cetacean sighting survey. Sighting survey procedures were same as offshore component of 2004
JARPN II but the survey mode was only restricted to closing mode (ASP). Natural marking record
experiment was attempted at grey, blue, humpback and right whales. Natural marking experiments
27

Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

were attempted at the opportunistic basis. Visual observation of large baleen whale feeding
behaviour was attempted. If the behaviour was observed, it was recorded on camera.
RESULTS AND DISCUSSION
Surveyed tracklines were shown on Fig 1. Sighting positions of Sperm and common
minke whales (Balaenoptera acutorotrata)

were shown on Fig 2. Total searching

distances were 809.4 n.miles. A total of 53 individuals of 43 schools were sighted inprimary sightings. They included 18 common minke and 25 sperm whales. Secondary sightings
were not made. Details of sightings were listed on Table 2. Natural marking record andbiopsy sampling experiment were not made. No large baleen whale feeding behavior
was observed.

ACKNOWLEDGEMENT
Special thanks is given to the crews and researchers for their dedication in collecting data. The
authors would like to thank Dr. Hiroshi Hatanaka (The Institute of Cetacean Research). We also
express the gratitude to Hiroto Murase (The Institute of Cetacean Research) for the preparation ofEnglish manuscript of this paper.
REFERENCES
Government of Japan, 2004. Revised research plan for cetacean studies in the western North Pacificunder special permit (JARPN II). Paper SC/56/O1 submitted to the 56th IWC ScientificCommittee, 14pp.

28

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Table 1. Details of survey itinerary.
Date

Event

9/09

Depart from Kushiro Port, Hokkaido, Japan

9/10

Start sighting survey

9/27

End sighting survey

9/30

Arrive at Shiogama Port, Miyagi, Japan

Table 2. Summary of cetacean sightings.
Primary

SecondarySpecies

Sch.

Ind.

Sch.

Ind.

Common minke whale

17

18

0

0

Sperm whale

20

25

0

0

Unidentified cetaceans

6

10

0

0

Total

43

53

0

0

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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

Fig 1. Searching effort by dedicated survey vessel “Kyoshin-Maru No.2”, in the 2004 JARPN II
coastal survey.

Fig 2. Sighting positions of Common Minke whales(○), and Sperm whales(△) by dedicated survey
vessel “Kyoshin-Maru No.2” in the 2004 JARPN II coastal survey.

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Appendix 3
Oceanographic conditions in the Kuroshio-Oyashio Inter-frontal zone
in September 2004
Denzo Inagake, Hikaru Watanabe, Shiroh Yonezaki and Shigeyuki Kawahara
National Research Institute of Far Seas Fisheries, Orido 5-7-1, Shimizu-ku, Shizuoka 424-8633, Japan
Contact e-mail:ina@fra.affrc.go.jp

Introduction
The oceanographic condition at the Tohoku area east of Japan is the most complicated area in theworld. There are both of subtropical water (the Kuroshio water) and subarctic water (the Oyashio
water), and also, both water masses are mixed each other and form new water masses in the
Kuroshio-Oyashio Inter-frontal Zone. Each water mass has its own ecosystem, like a Kuroshio
ecosystem, an Oyashio ecosystem, warm-core ring ecosystem, etc.

So, we must make clear theoceanographic condition around whale’s prey to build up a marine ecosystem model in the Tohoku
area.
In this paper, we analyzed the CTD data, which were observed by R/V Shunyo Maru cruise in apart of JARPN II (Japan's whale Research Program in the Western North Pacific) study to makeclear the oceanic environment in the research area.
Data and Methods
Hydrographic observations with a conductivity-temperature-depth profiler (CTD; SBE 911plus)
were carried out from 23rd to 29th September 2004 in the Kuroshio-Oyashio Inter-frontal Zone (Fig.
1).
The oceanographic conditions in September 2004 were analyzed by Tohoku National Fisheries
Research Institute (TNFRI), which used quasi-real-time data from several cooperative organs andprefectures, those were Fisheries Research Agency, Meteorological Agency, Hydrographic
Department and Fisheries Experiment Stations, etc. TNFRI published temperature maps andschematic hydrographic maps using World Wide Web (http://www.myg.affrc.go.jp/index-j.html).
Oceanic fronts and water masses are usually detected by subsurface temperature map (sea Table 1),
because they are obscure in sea surface temperature distributions from summer to fall seasons andthe Oyashio water spreads into the subsurface layer.
Oceanographic conditions in the research area
Figure 2 shows the Temperature-Salinity diagrams using CTD station data. Water masses in the
research area have characteristics of cold low-salinity water (the Oyashio water in the lower part of
Fig. 2) with warm surface water (left upper part of Fig. 2), warm high-salinity water (Kuroshio water
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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

in the right upper part of Fig.2) and the mixed water of the Kuroshio water and Oyashio water. In
this figure, the Oyashio water was the most dominant although the Kuroshio water was observed
only one station.
Figure 3 shows the schematic hydrographic map in September 2004, presented by TNFRI.
The northern limit of the warm water spread from the Kuroshio Extension moves northward fromMarch to November.

Its position in September 2004 was north of 42°N on 147°E line. This

northward spreading is developed well caused by the Kuroshio warm-core ring that is detectedaround 41°30’N, 145°E. Tsugaru warm water spreaded eastward to around 143°E. The southern
limit of the first Oyashio Intrusion was located 39°30’N on 143°30’E line, which were more
southern position from monthly mean location in September (40°20’N). The southern limit of thesecond Oyashio Intrusion was around 39°50’N, 147°E which was a little southern position from amonthly mean position in September. Almost all stations were distributed in the Oyashio area.
Figure 4 shows the 100 m depth temperature map observed by R/V Shunyo Maru. The Oyashio
water colder than 5°C at the depth of 100 m was spreading to the south-eastern part of theobservation area. The warm water was observed at a few stations in the coastal area of Hokkaido.
The cold water was observed at few stations between the Oyashio water and the warm water along
the Hokkaido coast.
All of these figure show almost of all stations are distributed in and around the Oyashio area.

REFERENCES

Favorite, F., A. J. Dodimead and K.Nasu (1976): Oceanography of the Subarctic Pacific Region,
1960-71. Bull. 33, International North Pacific Fisheries Commission, 187 pp.
Kawai, H. (1969):

Statistical estimation of isotherms indicative of the Kuroshio axis, Deep-Sea

Res., 16, 109-115.
Murakami, M. (1994): On long-term variations in hydrographic conditions in the Tohoku area, Bull.
Tohoku Natl. Fish. Res. Inst., No. 56, 47-56 (in Japanese with English abstract).

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Table 1. Extraction method from temperature map to determine theposition of each water mass.
Target characteristics
Extraction method
Kuroshio Extension Axis
14℃ isotherm at 200m (Kawai, 1969)
Warm-core ringTemperature front at 200m
Oyashio front
5 ℃ isotherm at 100m
Oyashio water
Area with T<5 ℃ at 100m
Cold water
Area with 5℃<T<10 ℃ at 100m
Warm water
Area with T>10 ℃ at 100m and T<14 ℃
at 200m
Tsugaru warm current

Temperature front at 100m near the
Tsugaru Strait

Subarctic Boundary

Salinity front defined by 34.0psu

Subarctic Front

Temperature front defined by 4℃

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Kishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

Fig. 1.

Station map observed by R/V Shunyo Maru in 23 – 29 September 2004.

Green

triangles, light blue stars and blue circles denote CTD stations in the warm
area (100 m temperature was over 10℃ and 200 m temperature was less than
14℃), the cold area (100 m temperature was over 5℃ and less than 10℃) andthe Oyashio area (100 m temperature was less than 5℃), respectively.

34

Fig. 2.

figure denotes a density line of sigma-t.

35

Temperature-Salinity diagrams using CTD station data observe by R/V Shunyo Maru in 15 – 29 September 2004.

SC/57/O4

Each thin line in thisKishiro, et al.: Report of the 2004 JARPN II-Part II: Coastal component

Fig. 3.

Schematic hydrographic map in Tohoku area, northwestern Pacific, in
September 2004 (presented by Tohoku National Research Institute) withstation map observed by R/V Shunyo Maru.

Blue, yellow and red area show

distributions of the Oyashio, the warm water spread from the Kuroshio
Extension and the Kuroshio Extension, respectively.

Green triangle, light

blue star and blue circle denote CTD stations observed from Shunyo Maru in
the warm area, cold area and the Oyashio area, respectively.

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Fig.4.

100m temperature map observed by R/V Shunyo Maru in 23 – 29 September
2004.

37