SC/59/O7

SC/59/O7

Cruise report of the second phase of the Japanese Whale Research Program
under Special Permit in the Western North Pacific (JARPN II) in 2006
- Coastal component off Kushiro.
HIDEYOSHI YOSHIDA1, HIDEHIRO KATO2, TOSHIYA KISHIRO1, TOMIO MIYASHITA1, TOSHIHIDE IWASAKI1,
SHINGO MINAMIKAWA1, TAMEO RYONO3, SHIGEO TABATA3, YUKA MORITA3, HITOMI SATO3, RYOSUKEOKAMOTO2, YOKO TOYODA2, GEN NAKAMURA2, TADASHI EBISUI3, KAZUYOSHI NAKAI3, AKIRAMATSUMOTO2, SHIGETOSI NISHIWAKI3, AND SHIGEYUKI KAWAHARA1
1

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa-ku, Yokohama,
Kanagawa 236-8648, Japan

2

Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo 108-0075, Japan

3

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

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

ABSTRACTThe fourth survey of the JARPN II coastal component was conducted from 11 September to 31 October 2006, off Kushiro,
Hokkaido, northeastern Japan (northern part of the sub-area 7), using four small-type whaling catcher boats, one echosounder-trawl survey vessel, and one dedicated sighting survey vessel. Sampling of common minke whales was conducted incoastal waters within 50 nautical miles from the Kushiro port, and all the animals collected were landed at the JARPN II
research station for biological examination. During the survey, a total of 10399.5 nautical miles (958.0 hours) was surveyed
for whale sampling. Eighty four schools (85 individuals) of common minke whales were detected with a sei whale sighting (1animal), and 35 common minke whales were collected. Average body length of the animals collected was 6.60m (SD=1.02,
Range=4.61-8.12m, n=25) for males and 6.05m (SD=1.31, Range=4.62-8.33m, n=10) for females. In males, 13 animals were
sexually mature, but only 2 females had attained sexual maturity. One mature female was pregnant. Composition of sex andsexual maturity recorded in the present survey was almost same as that in the previous surveys off Kushiro. Japanese
anchovy (Engraulis japonicus) was only one dominant prey species found from whale forestomach and was detected
throughout the survey period. Other 4 species, Pacific saury (Cololabis saira), walleye pollock (Theragra chalcogramma),
Japanese common squid (Todarodes pacificus), and krill (Euphausia pacifica) were also detected from the stomach, but theirfrequency of occurrence was low. These results were different from those in the previous surveys, which indicates that preyspecies of common minke whales changes year by year. In the present season, migration of common minke whales into thecoastal waters off Kushiro was thought to be low. Furthermore, the prey species survey suggested that the prey environment
for the common minke whale off Kushiro was poor. These results are thought to be the result of unusually high sea surface
temperature off Kushiro during the present survey.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; COASTAL WATERS OF JAPAN; FOOD/PREY;ECOSYSTEM; SCIENTIFIC PERMITS.

BACKGROUND
After the two-year feasibility study conducted in 2000 and 2001, the full-scale survey of the second phase1

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiroof the Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN II)
began in 2002. The objectives of the program are, i) feeding ecology and ecosystem studies, involving prey
consumption by cetaceans, prey preferences of cetaceans and ecosystem modeling, ii) monitoring
environmental pollutants in cetaceans and the marine ecosystem, and iii) elucidation of stock structure ofwhales (Government of Japan, 2002a).
The JARPN (1994-1999) and the JARPN II feasibility study (2000-2001) revealed that common minke
whales are widely distributed from offshore waters into coastal waters and feed on various prey species
such as Japanese anchovy, Pacific saury, and walleye pollock (Government of Japan 2002b; Tamura andFujise 2002). The coastal waters of Japan are very important fishing grounds. Thus, it was thought that thecoastal waters are also a very important area for the full-scale JARPN II program. However, the Nisshin
Maru research vessels can not be operated in the near shore areas, because of their movement restrictions inshallow waters and the presence of fishing gear and many boats. Furthermore, the research vessels are notavailable from late autumn to early spring. In order to cover the temporal and spatial gap of these vessels,in the full-scale JARPN II, sampling of common minke whales in coastal waters using small-type whaling
catcher boats was planned (Government of Japan, 2002a).
Feasibility studies were carried out in coastal waters off Kushiro in autumn 2002 and off Sanriku in spring
2003, using small-type whaling catcher boats, in order to examine the logistic aspects of the methodology(Kishiro et al. 2003, Yoshida et al. 2004). From these surveys, it was concluded that no substantial problem
occurred and that the coastal survey could be continued as the component of the JARPN II, using the same
vessels and methodology (Government of Japan 2004b, Kato et al. 2004).
From results of the feasibility studies, the coastal component was revised to be conducted twice a year andto collect 60 common minke whales in each of spring and autumn (Government of Japan 2004a). The firstrevised survey was carried out off Kushiro in autumn 2004 and the second one followed it in autumn 2005
(Kishiro et al. 2005, 2006). This paper presents results of the fourth survey conducted off Kushiro, from 11
September to 31 October. The survey was authorized by the Government of Japan in compliance with
Article VIII of the International Convention for the Regulation of Whaling. At the request of the Institute of
Cetacean Research (ICR), the National Research Institute of Far Seas Fisheries (NRIFSF), of the Fisheries
Research Agency, took the lead in the planning and conduct of the survey.

MATERIALS AND METHODS
Response to the discussion at the IWC/SC meeting
The revised JARPN II research plan was presented at the 56th IWC/SC annual meeting (Government ofJapan 2004a).

Revised surveys were conducted in 2004 and 2005 off Kushiro and results were reported at

the IWC/SC meetings (Kishiro et al. 2005, 2006). Because no substantive comments or recommendations
to the plan were made at these meetings, the present survey was conducted under the original revised plan
(Government of Japan 2004a).

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SC/59/O7

Research area
Research area was set in the same waters where the previous JARPN II coastal surveys off Kushiro wereconducted (Kishiro et al. 2003, 2005, 2006): the research area was in coastal waters within 50 nautical
miles (mostly within 30 n. miles) from the Kushiro port, southeastern Hokkaido (Fig. 1). This area isincluded in the northern part of the sub-area 7 established by the IWC.

Research vessels and station
Whale sampling survey
Four small-type whaling catcher boats were used as sampling vessels: Taisho Maru No. 28 (hereinafterreferred as 28T; 47.3GT), Koei Maru No. 75 (75K; 46.0GT), Katsu Maru No.7 (7K; 32.0GT), andSumitomo Maru No.31 (31S; 32.0GT). The whale sampling survey was conducted in a period from 11
September to 31 October, 2006. All the common minke whales collected were landed at the JARPN II
research station established in the Kushiro port, for biological examination.

Prey species survey
The Kaiko Maru (KK1, 860.3GT), a trawler-type research vessel, conducted the prey species survey using
a quantitative echosounder (SIMRAD ER500), mid-water trawl, and the IKMT, in a wider research area set
off southeastern Hokkaido in the period from 11 to 29 September. The Kaiko maru also carried out
oceanographic observations using a CTD. Furthermore, a sighting survey was tried as a feasibility study, inwhich it was examined whether sighting information could be obtained on the vessel conducting theacoustic prey species survey. Details of the prey species survey and the sighting survey are shown inAppendix 1 and 3, respectively. Oceanographic conditions revealed from the CTD observations are notedin Appendix 2.

Dedicated sighting survey
The Kyoshin Maru No.2 (KS2; 372.0GT) carried out the dedicated sighting survey. The survey was
conducted from 2 to 27 September, following zigzag track lines predetermined in research area set off
southeastern Hokkaido. The details of the survey are shown in Appendix 3. Furthermore, relation between
sighting positions of common minke whales and the sea surface temperature is discussed in Appendix 4.

Sighting and sampling methods
Sighting and sampling methods were almost the same as those used in the coastal survey conducted off
Kushiro in 2002 (Kishiro et al. 2003). The research head office in the research station controlled thesampling vessels during the survey. In order to avoid concentration of searching effort, the office
determined the searching areas and routes of sampling vessels each day, from weather conditions, whale
distribution, and information on coastal fisheries. Searching activity was carried out during the daytime andthe vessels returned to the port every night. A researcher was on board each of the four sampling vessels,
and recorded sighting and sampling information, e.g., coordinates and time of common minke whalesightings and sampling made, weather conditions, and vessel activity. Sighting information was also

3

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

recorded for other baleen whales and the sperm whale. Searching was conducted by crews and researchers
from the top barrel and upper bridge of vessels running at about 11 knots. All common minke whales
sighted were targeted for sampling, except cow-calf pairs. When a school consisted of more than 1 animal,
an individual was selected randomly from the school and then caught. Once a vessel collected a whale, it
returned to the Kushiro port as soon as possible, to transport the animal to the research station. While
returning to the port, even if other common minke whales were sighted, the vessel did not catch theseanimals. At the port, animals taken were lifted from the vessel by a crane, using a wire net and then carried
to the station by an 11-ton freight trailer. At that time, the animals body weight was measured with a truck
scale.

Biological research for common minke whales collected
Biological examinations of animals collected were conducted at the research station. Research items ofthese examinations which are summarized in Table 4 were used for studies on feeding ecology, stock
structure, life history and pollutants. In addition, researchers of the Obihiro University of Agriculture andVeterinary Medicine collected oocytes from 6 females for in vitro fertilization research conductedcooperatively with the ICR.

RESULTS
Searching effort made by sampling vessels
Cruise tracks made by the 4 sampling vessels (28T, 75K, 7K, and 31S) during the survey are shown in
Figure 2. Cruise tracks were widely distributed in waters 30 n. miles from the Kushiro port. Searching
distance and time for each vessel are given in Table 1. Here, searching distance and time are defined as
distance and time recorded under searching activity conducted by crews from the top barrel of the vessels.
Total searching distance and time were 10,399.5 n. miles and 958.0 hours, respectively.

Common minke whale sightings made by sampling vessels
A total of 84 schools (85 individuals) of common minke whales were sighted during the survey (Table 2).
These were 79 primary sightings (80 animals/79 schools) and 5 secondary sightings (5 animals/5 schools).
Of all the 84 schools sighted, only 1 school consisted of 2 individuals. Others were of solitary animals. No
cow-calf pairs were detected. A sighting of a sei whale was obtained on 11 September. This was the firstrecord of the sei whale in the coastal surveys off Kushiro. Sighting positions of common minke whales
from the sampling vessels are shown in Figure 3, with 1 sei whale sighting. Although the searching area
was widely distributed in the waters 30 n. miles from the Kushiro port (see, Fig. 2), sightings of minke
whales occurred along 200m isobath, particularly on the continental slope in the western side of theresearch area. Temporal change in density index of common minke whales recorded by the sampling
vessels is shown in Table 3. The largest values were recorded in the middle of September (0.18 for SPUE
and 1.63 for DI). Values decreased to the late of September, increased once in the beginning of October,and decreased again toward the end of October. Similar temporal changes were recorded in the last twocoastal surveys off Kushiro conducted in 2004 and 2005.

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SC/59/O7

Sampling of common minke whales
Of all the 85 animals sighted, 35 common minke whales were collected for biological examination. In thesampling process, there were no struck and lost animals. Sighting positions of animals collected are shownin Figure 3.

Prey species survey and dedicated sighting survey
The prey species survey was conducted using the trawler-type research vessel (KK1). Distribution andabundance of prey species were investigated using the quantitative echosounder (SIMRAD ER500),
midwater trawl, and the IKMT. Oceanographic observation was also conducted using CTD. Among theepipelagic small fishes, Japanese anchovy was the most abundant and mainly distributed in the eastern partof the survey area. However, they were rarely captured in the central and western part of the survey area,
where the whale sampling survey was conducted. Furthermore, it was remarkable that catches of the Pacificsaury were extremely low in the present survey. This fact was probably caused from high sea surface
temperature, as discussed in Appendix 4. These results suggest that the prey environment for common
minke whales was poor in the coastal waters off Kushiro. During the sighting survey conducted on the preyspecies survey vessel, 1 common minke whale was detected. Further information on the prey species
survey and the sighting survey is provided in Appendix 1 and 3, respectively. The dedicated sighting survey
was carried out using the sighting survey vessel (KS2). Thirteen common minke whales were sighted. The
number of sightings recorded in the present survey was the lowest among the 4 years. This was thought tobe the result of the unusually high sea surface temperature off Kushiro, as discussed in Appendix 4. Further
results from the survey are shown in Appendix 3.

Sex ratio, body length and weight of animals caught
Research items of biological examination for the 35 animals caught are summarized in Table 4, with thenumber of data and samples obtained. The animals consisted of 25 males and 10 females. Sex ratio ofmales to all the animals collected was 0.71. This ratio was almost same as recorded in the past coastal
surveys off Kushiro. Average body length was 6.60m (range=4.61-8.12, SD=1.02) for males and 6.05m(range=4.62-8.33, SD=1.31) for females (Table 5). Average body weight was 3.77 tons (range=1.10-6.02,
SD=1.59) for males and 2.92 tons (range=1.04-7.06, SD=2.04) for females (Table 6). In males, large
animals with body length of 7m or more were collected during the survey except the last period from 21 to
31 October, in which body length of two males collected was around 5.5m (Table 5). Thirteen individualsof all the 25 males possessed body length of 7m or more (52.0%), while only two of the 8 females attained
the length of 7m or more (25.0%)(Fig. 4). The two large females were collected in the second period from21 to 30 September. Sexual maturity of animals collected is shown in Table 7 and Figure 4. In males, 13 of
the 25 animals were sexually mature (52.0%), and two of 10 females had attained sexual maturity (20.0%).
One mature female was pregnant. Lactating females were not observed. The maturity rate of males
recorded in the present survey was slightly lower than the last year’s rate (66.7%), while the rate forfemales (20.0%) was higher.

5Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Prey species of common minke whale found from forestomach
Stomach contents of the 35 animals collected were examined. Following the same methods used in the
JARPN II feasibility survey conducted in 2001 (Fujise, et al., 2002), stomach contents were weighed to thenearest 0.1 Kg, by each of four chambers. Weights were recorded both including and excluding liquid
contents. A small quantity of forestomach contents was collected and frozen for laboratory analysis. Weightof forestomach contents including liquid ranged from 3.08kg to 127.04kg. The maximum weight wasrecorded from a male with body weight of 5.46 tons. It was equivalent to 2.3% of the male’s body weight.
This animal fed on Japanese anchovies.
Forestomach contents found from the 35 minke whales are listed in Table 8. No empty stomachs wereobserved. Dominant prey species was the Japanese anchovy (Engraulis japonicus)(82.9%, observed from29 of the 35 whales). The frequency of occurrence was higher than those recorded in the previous surveys
off Kushiro. In the present survey, 4 other species were also detected: Pacific saury (Cololabis saira),
walleye pollock (Theragra chalcogramma), krill (Euphausia pacifica), and Japanese common squid(Todarodes pacificus). The frequency of occurrence of these species was very low. In the last survey
conducted off Kushiro in 2005, the dominant prey species changed with time. Krill were dominant at first,
then frequency of occurrence of Japanese anchovies increased, and later, Japanese anchovies were mostdominant (Kishiro et al. 2006). However, in the present survey, such changes in the prey species frequency
were not observed: Japanese anchovies were dominant throughout the survey.

By-products of the whales
After biological examination, all the animals were processed according to the International Convention forRegulation of Whaling, Article VIII. Total weight of products including meat and blubber was 65.3 tons.

DISCUSSION
The present survey was the fourth survey of the JARPN II coastal component off Kushiro. As in previous
years, no practical problems occurred in conducting the survey. During the present survey, however,typhoons, low atmospheric pressure, and thick fog often disturbed the research activities. Of total 51 day
survey period, sampling vessels could conduct the research only for 36 days or 70.6% of the time. This was
the lowest among the 4 years.
In the present survey, the sea surface temperature (SST) was unusually high. In Appendix 4, relation
between the SST and positions of common minke whales sighted by the dedicated sighting survey are
discussed. Average SST at sighting positions of common minke whales in the 4 surveys was 15.5 °C, whichindicates that whale distribution is related to the SST. Indeed, Figure 3 in Appendix 4 shows that most ofsightings were recorded where the SST was ≤ 16 °C. In 2006, warm waters (16°C<) spread over the waters
off Kushiro: frequency of areas with the SST ≤ 16 °C was only 3.6 % (Fig. 7 in Appendix 4). Thisfrequency has been getting lower year by year since the JARPNII coastal component off Kushiro wasstarted in 2002 and the value recorded in the present survey was lowest. In the present season, migration of6

SC/59/O7

common minke whales into the coastal waters off Kushiro was also thought to be low. We could recognizethat the density index recorded in the surveys was obviously related to frequency of areas with the SST ≤16 °C. The SST in coastal waters off Kushiro is thought to affect migration of common minke whales into
the area. Possibly, this relationship can be used as an index for estimation of the magnitude of whale
migration into these waters, although further analysis is needed.
Furthermore, the SST is thought to affect migration of the prey species of common minke whales. The
Pacific saury is known to be one of the most important prey species of common minke whales in thewestern North Pacific (Tamura and Fujise 2002). In autumn, the Pacific saury migrates down to eastern
Hokkaido and mode of the SST at positions where the Pacific saury fisheries operated was 15 °C(Watanabe et al. 2006). Figure 9 in Appendix 4 indicates that most of the Pacific saury fisheries wereconducted at waters with SST ≤ 18 °C. In September 2002, during which cold water spread over the area,
many saury fishing boats operated in coastal waters off Kushiro. However, in 2006, no boats conducted thesaury fishing off Kushiro. Appendix 1 also shows that only an individual Pacific saury was caught by the
trawl sampling in the prey species survey. The information suggests that, in 2006, the amount of migrating
saury into coastal waters off Kushiro was very small, probably resulting from the spreading warm waters.
The prey species survey also revealed relatively low abundance of Japanese anchovies in coastal waters off
Kushiro. The Japanese anchovy is also known to be the important prey species of common minke whales in
the western North Pacific (Tamura and Fujise 2002). The prey species survey indicated that amount ofanchovies distributed in coastal waters off Kushiro was small, while they were very abundant in east waters
off Kushiro (Figure 2 in Appendix 1). These results indicate that the prey environment for common minke
whales in coastal waters off Kushiro was relatively poor in 2006. It is probable that the prey-poor
environment resulted from the high SST.
Composition of common minke whales collected during the present survey was similar to that in theprevious surveys off Kushiro, i.e. sex ratio of males to the animals collected was high and more than half ofmales had attained sexual maturity. However, composition of prey species found in the stomachs wasdifferent: in the present survey, frequency of occurrence of the Japanese anchovy was highest among the 4
years. Furthermore, in the present survey, change in the prey species frequency with time was not observed,
while dominant prey species changed with time in the last survey: krill were dominant at first, thenfrequency of occurrence of Japanese anchovies increased, and at the last part of the survey, Japanese
anchovies were dominant (Kishiro et al. 2006). These results indicate that prey species of common minke
whales changes yearly, from environmental factors, e.g., oceanographic conditions and prey species
distribution. From the present survey, we could obtain valuable information on feeding habits of common
minke whales in a prey-poor environment. To evaluate food consumption of common minke whales and toobtain more information on their feeding habits and migration, further information is needed.

ACKNOWLEDGMENTS
We acknowledge Dr. Hiroshi Hatanaka (the project leader of the full-scale JARPN II survey, ICR), Dr. Seiji

7

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Ohsumi (ICR), and Messrs. Joji Morishita and Hideki Moronuki (the Fisheries Agency of Japan), for theirguidance in the survey design and support. Mr. Dan Goodman provided us useful comments andsuggestions. Crew of research vessels, staff of the research station in Kushiro, and the Japan small-typewhaling association assisted in important aspects of the survey. We also thank all the members of theKushiro fisheries cooperative association, the municipal office of Kushiro, Hokkaido government Kushiro
sub-prefectural office, and Hokkaido government office, for their kind assistance.

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 the feasibility 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 Scientific Committee, 51pp.
Government of Japan, 2002a. 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., Kawahara, S., Pastene, L.A. and Hatanaka, H. eds.), 2002b. Report of2000 and 2001 feasibility study of the Japanese Whale Research Program under Special Permit in thewestern North Pacific-Phase II (JARPN II). Paper SC/54/O17 submitted to the 54th IWC ScientificCommittee, 202pp.
Government of Japan, 2004a. Revised research plan for cetacean studies in the western North Pacific under
special permit (JARPN II). Paper SC/56/O1 submitted to the 56th IWC Scientific Committee, 14pp.
Government of Japan (Fujise, Y., Tamura, T., Kato, H. and Kawahara, S. eds.), 2004b. Some considerationsof the feasibility components of the JARPN II research plan. Paper SC/56/O2 submitted to the 56th IWC
Scientific Committee, 36pp.
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 Scientific Committee, 36pp.
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. 2003. Report of the2002 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 Scientific Committee, 26pp.
Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., Okamoto, R., Yasui, K., Sato, H.,
Morita, Y., Saino, S., Hara, T., Ebisui, T., Kuroishi, H., Nishiwaki, S., and Kawahara, S. 2005. Cruise
report of the coastal survey on common minke whales off Kushiro, northeast Japan: the 2004 JARPN II
survey (Part II) - Coastal component. Paper SC/57/O4 submitted to the 57th IWC Scientific Committee,
37pp.
Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., Yasui, K., Sato, H., Morita, Y.,
Kumagaya K., Tokuda, D., Nakai, K., Funabashi, N., Ebisui, T., Wakatsuki, T., Sakaguchi, M., Houhana,T., Nishiwaki, S., and Kawahara, S. 2006. Cruise report of the second phase of the Japanese Whale8

SC/59/O7

Research Program under Special Permit in the Western North Pacific - Coastal component off Kushiro in2005. Paper SC/58/O10 submitted to the 58th IWC Scientific Committee, 32pp.
Tamura, T. and Fujise, Y. 2002. Geographical and seasonal changes of the prey species on minke whale in
the Northwestern Pacific. ICES Journal of Marine Science, 59:516-528.
Watanabe, K., Tanaka, E., Yamada, S., and Kitakado, T. 2006. Spatial and temporal migration modeling forstock of Pacific saury Cololabis saira (Brevoort), incorporating effect of sea surface temperature.
Fisheries Science, 72:1153-1165.
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 permit in the western North Pacific– Phase II (JARPN II) in 2003 (Part II) – Coastal component. Paper SC/56/O14 submitted to the 56th
IWC Scientific Committee, 31pp.

Figure 1. Research area set for the 2006 JARPN II coastal survey off Kushiro. This area
is included in the northern part of the sub-area 7 established by the IWC.

9

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Figure 2. Cruise tracks of the sampling vessels in the 2006 JARPN II coastal survey off Kushiro,with the 200m isobath.

Figure 3. Sighting positions of common minke whales (circle) and a sei whale (triangle) made from thesampling vessels during the 2006 JARPN II coastal survey off Kushiro, with the 200m isobath.
Closed circles are sighting positions of common minke whales collected.

10SC/59/O7

9Number of animals

8

Immature male
Immature female
Mature male
Mature female

7
6
5
4
3
2
1
0

4.0

4.5

5.0

5.5

6.0

6.5

7.0

7.5

8.0

8.5

Body length （m）
Figure 4. Body length of common minke whales collected during the 2006 JARPN II coastal survey
off Kushiro.

Table 1. Searching days, hours, and distances made by the four sampling vessels in the 2006 JARPN II
coastal survey off Kushiro.
PeriodSampling vessels*1
28T
75K
7K
31S
Total
11 – 20 September
Days
10
10
10
10
40
Hours
47.7
43.0
53.3
47.8
191.8
Distances (n. miles)
543.4
469.8
557.0
520.0
2090.221 – 30 September
Days
10
10
10
10
40
Hours
52.4
45.4
50.7
46.0
194.5
Distances (n. miles)
593.9
502.5
545.5
499.3
2141.2
1 – 10 October
Days
10
10
10
10
40
Hours
42.9
35.9
45.7
41.3
165.8
Distances (n. miles)
484.5
391.5
483.6
432.6
1792.2
11 – 20 October
Days
10
10
10
10
40
Hours
44.3
46.4
50.5
44.4
185.6
Distances (n. miles)
497.7
483.4
526.8
487.8
1995.721 – 31 October
Days
11
11
11
11
44
Hours
54.1
55.4
57.2
53.6
220.3
Distances (n. miles)
599.3
587.1
617.9
575.9
2380.2
Total
Days
51
51
51
51
204
Hours
241.4
226.1
257.4
233.1
958.0
Distances (n. miles) 2718.8
2434.32730.82515.610399.5*1: 28T; Taisho Maru No. 28; 75K: Koei maru No. 75; 7K: Katsu Maru No. 7; 31S: Sumitomo maru No. 31.

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Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Table 2. List of cetacean species and number of sightings (no. schools/no. individuals) made fromfour sampling vessels in the 2006 JARPN II coastal survey off Kushiro.
SpeciesPrimary*
Secondary*
Total*
Period
Sch.
Ind.
Sch.
Ind.
Sch. Ind.
Common minke whale
34
34
3
3
37
37
11 – 20 September
Like minke whale
8
8
1
1
9
9
Sei whale
1
1
0
0
1
1
Unidentified lwhale
4
4
0
0
4
4
Common minke whale
10
11
2
2
12
13
21 – 30 September
Like minke whale
6
6
0
0
6
6
Sei whale
0
0
0
0
0
0
Unidentified lwhale
0
0
0
0
0
0
Common minke whale
14
14
0
0
14
14
1 – 10 October
Like minke whale
2
2
0
0
2
2
Sei whale
0
0
0
0
0
0
Unidentified lwhale
4
4
0
0
4
4
Common minke whale
12
12
0
0
12
12
11 – 20 October
Like minke whale
5
5
0
0
5
5
Sei whale
0
0
0
0
0
0
Unidentified lwhale
2
2
0
0
2
2
Common minke whale
9
9
0
0
9
9
21 – 31 October
Like minke whale
2
2
0
0
2
2
Sei whale
0
0
0
0
0
0
Unidentified lwhale
1
1
0
0
1
1
Common minke whale
79
80
5
5
84
85
Total
Like minke whale
23
23
1
1
24
24
Sei whale
1
1
0
0
1
1
Unidentified lwhale
11
11
0
0
11
11
*: The numbers probably include some duplicated sightings made by plural vessels.

Table 3. Density index of common minke whales made by sampling vessels in the 2006 JARPN II
coastal survey off Kushiro.
DI*2
PeriodSPUE*1
11 – 20 September
0.18
1.63
21 – 30 September
0.05
0.47
1 – 10 October
0.08
0.78
11 – 20 October
0.06
0.60
21 – 31 October
0.04
0.38
Total
0.08
0.76
*1: No. of primary school sightings per 1 hour searching.
*2; No. of primary school sightings per 100 n. miles searching.

12

SC/59/O7

Table 4. Summary of biological data and samples collected during the 2006 JARPN II coastal survey
off Kushiro.
Number of animals
Samples and data
Male
Female Total
Body length and sex
25
1035
External body proportion
25
10
35
Photographic record and external character25
10
35
Diatom film record25
1035
Body scar record
25
1035
Measurements of blubber thickness (5 points)
22
830
Detailed measurements of blubber thickness (11 points)
3
2
5
Body weight25
10
35
Body weight by parts
3
2
5
Skin tissues for DNA analysis
25
1035
Muscle, liver, kidney, spleen, blubber, heart, and ventral groove for various analysis
25
10
35
Urine for various analysis
909Muscle, liver, kidney, and blubber for heavy metal analysis
25
1035
Muscle, liver, kidney, and blubber for organochlorines analysis
25
1035
Collection of blood plasma
19
625
Muscle and vertebrae for lipid analysis
325
Mammary grand; lactation status, measurement and histological sample
1010
Uterine horn; measurements and endometrium sample
1010Collection of ovary10
10
Photographic record of foetus
011
Foetal length and weight0
1
1
External measurement of foetus
011Muscle, liver, kidney, heart, blubber, and skin tissues of foetus
011
Testis and epididymis; weight and histological sample
25
25
Stomach contents, convenient record25
1035
Volume and weight of stomach content in each compartment25
1035
Observation of marine debris in stomach
25
10
35
Stomach contents for feeding study
25
10
35
Record of external parasites
25
10
35
Earplug for age determination
25
10
35
Tympanic bulla for age determination25
10
35
Largest baleen plate for morphologic study and age determination
25
10
35
Baleen plate measurements (length and breadth)25
1035Photographic record of baleen plate series
25
1035
Length of baleen series
25
1035
Collection of eye lens25
1035
Vertebral epiphyses sample
25
1035
Number of ribs
25
10
35
Skull measurement (length and width)
24
10
34

13

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Table 5. Statistics of body length (m) of common minke whales collected during the 2006 JARPN II
coastal survey off Kushiro.
PeriodMale

Female

Mean

S.D.

Min.

Max.

n

Mean

S.D.

Min.

Max.

n

11 – 20 September

6.84

0.95

5.52

8.12

10

5.28

0.49

4.75

5.91

4

21 – 30 September

5.89

1.36

4.61

7.51

5

7.58

1.18

6.22

8.33

3

1 – 10 October

7.00

0.55

6.48

7.60

4

5.56

1.32

4.62

6.49

2

11 – 20 October

6.99

0.79

5.85

7.63

4

-

-

-

-

0

21 – 31 October

5.50

0.14

5.40

5.60

2

5.58

-

-

-

1

Total

6.60

1.02

4.61

8.12

25

6.05

1.31

4.62

8.33

10

Table 6. Statistics of body weight (tons) of common minke whales collected during the 2006 JARPN II
coastal survey off Kushiro.
PeriodMale

Female

Mean

S.D.

Min.

Max.

n

Mean

S.D.

Min.

Max.

n

11 – 20 September

4.17

1.60

1.84

6.02

10

1.73

0.55

1.32

2.56

4

21 – 30 September

2.91

20.3

1.10

5.38

5

5.29

2.20

2.82

7.06

3

1 – 10 October

4.21

0.85

3.54

5.36

4

2.11

1.51

1.04

3.18

2

11 – 20 October

4.28

1.33

2.54

5.70

4

-

-

-

-

0

21 – 31 October

1.99

0.01

1.98

2.00

2

2.22

-

-

-

1

Total

3.77

1.59

1.10

6.02

25

2.92

2.04

1.04

7.06

10

14

SC/59/O7

Table 7. Composition of sex and sexual maturity of common minke whales collected during the 2006 JARPN II
coastal survey off Kushiro.
PeriodMale

Female

Im

M

Total

Maturity(%)

Im

R

P

Total Maturity(%)

Pregnancy(%)*

11 – 20 September

4

6

10

60.0

4

0

0

4

0.0

-

21 – 30 September

3

2

5

40.0

1

1

1

3

66.7

50.0

1 – 10 October

2

2

4

50.0

2

0

0

2

0.0

-

11 – 20 October

1

3

4

75.0

-

-

-

0

-

-

21 – 31 October

2

0

2

0.0

1

0

0

1

0.0

-

Total

12

13

25

52.0

8

1

1

10

20.0

50.0

Im: Immature; M: Mature; R: Resting; P: Pregnant.
*: Apparent pregnancy rate.

Table 8. Prey species found in forestomach of common minke whales collected during the 2006 JARPNII
coastal survey off Kushiro.
No.
Prey species (%)
PeriodofJapanese
Pacific
Walleye
Krill
Common Unidentified
whalesanchovysaury
pollock
squid
fish
11 – 20 September14

13 (92.9)

0 (0.0)4 (28.6)

1 (7.1)1 (7.1)1 (7.1)

21 – 30 September8

6 (75.0)0 (0.0)1 (12.5)

0 (0.0)0 (0.0)2 (25.0)

1 – 10 October

65 (83.3)

1 (16.7)

0 (0.0)0 (0.0)0 (0.0)0 (0.0)

11 – 20 October42 (50.0)

2 (50.0)0 (0.0)0 (0.0)0 (0.0)0 (0.0)21 – 31 October33 (100.0)

0 (0.0)0 (0.0)0 (0.0)0 (0.0)0 (0.0)Total

35

29 (82.9)

3 (8.6)5 (14.3)

1 (2.9)1 (2.9)3 (8.6)

15

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Appendix 1
2006 coastal prey species survey of JARPN II off Kushiro

HIKARU WATANABE1, HIROSHI KIWADA2, HIROTO MURASE2, SAEKO KUMAGAI2 AND SHIGEYUKI KAWAHARA1
1

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, Kanagawa
236-8648, Japan

2

The Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo 104-0055, Japan
Contact e-mail:kawahara@fra.affrc.go.jp

ABSTRACT
We conducted prey species survey to examine prey environment and prey preference of minke whale in cooperation with thesampling survey of the whale by small-type catcher boats off Kushiro, eastern Hokkaido, in September 2006 as a part of
JARPN II study. The distribution, abundance, and size composition of the prey were investigated with the quantitativeechosounder, midwater trawl, and IKMT by the research vessel Kaiko-Maru. Acoustic data were acquired by steaming at
about 10.5 knots during the daytime along the track lines with operating frequency at 38 and 120 kHz. Because the acoustic
data are being analyzing now, we depicted the preliminary results on distribution, abundance and size composition of preyspecies of minke whale mainly based on the data of predetermined trawl. Among the epipelagic small fishes, Japanese
anchovy was the most abundant and mainly distributed in the eastern part of the study area where sea surface watertemperature (SST) was 16-18˚C, followed by Japanese common mackerel. However, these species were rarely captured in
the central and western part of the study area where SST was 18-20˚C. It was remarkable that the catches of Pacific saury,which was mainly distributed in the area where SST was lower than 15˚C, were extremely low. This fact is probably due tohigh SST field generally higher than 16˚C of the study area. These results suggest that prey environment of the minke whalein the 0-50 m layer was good in the eastern area and poor in the central and western area off Kushiro. Catches of Japanesecommon squid were extremely low, which coincides with the information of the fisheries. Walleye pollock and forked hakewere caught at 120-150 m near Kushiro Canyon. Krill swarms were found at 100-150 m in the offshore region. In this year,
prey species survey vessel Kaiko-Maru also conducted sighting survey of whale during prey survey period, and we
confirmed that generally both surveys could be conducted concurrently by same vessel. The results of sighting survey were
described in Appendix 3.

INTRODUCTION
The objective of JARPN II is to contribute to the conservation 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 study is put on to accumulate information of prey preference and prey consumption of cetaceans
to construct ecosystem models. As it is difficult to cover the coastal area especially in spring and autumn by the
Nisshin-Maru, JARPN II has a new coastal component, i.e. the sampling survey for minke whale by small-type16

SC/59/O7

whaling catcher boats. In September 2006, the cooperative whale/prey surveys were conducted in the coastal
region off Kushiro, eastern Hokkaido, as in 2002, 2004, and 2005. This document presents the preliminary
results of the prey species survey. In addition, we had another objective in this year, that is, to examine thepossibility that prey species survey and sighting survey of whale could be conducted concurrently by one vessel.
This result is also presented in this document. Although a dedicated sighting vessel, Kyoshin-Maru No. 2, also
conducted cooperative acoustic survey and oceanographic observations with CTD, and prey survey vessel
Kaiko-Maru also conducted sighting survey concurrently with prey survey, these results are not included in thisdocument and are described in Appendix 3.

MATERIALS AND METHODS
The prey species survey covered wide area off the eastern Hokkaido, from 143º15’E (off cape Erimo) to
146º00’E (off Nemuro), and north of 41ºN to elucidate the distribution and abundance of main prey species ofminke whale (Fig. 1). In this study area, the sampling survey of minke whale was conducted in the coastal waters
mainly within the 30 nautical miles (maximum 50 nautical miles) from Kushiro (Fig. 1). As many fishing gears
were set near the shore, the waters shallower than 50 m were excluded in principle. The survey area was divided
into coastal and offshore parts. The coastal part was further divided into east, central and west parts. Zigzag tracklines were set to cover each part. The waypoints of planned track lines are shown in Table 1.
All survey was conducted in the daylight period from an hour after sunrise to an hour before sunset(generally from 06:00 to 17:00 in local time) from September 11 to 29, 2006. The distribution and abundance ofthe prey species were investigated with the quantitative echosounder (SIMRAD ER500), midwater trawl andIsaacs-Kidd midwater trawl (IKMT) by the stern trawler-type research vessel, Kaiko-Maru (860.25 GT) bymoving at about 10.5 knots on the track lines. Acoustic data were acquired with Echoview Ver.3 (Sonar Data
Co., Ltd.). Calibrations were carried out off Shiranuka near Kushiro in September 15 using the copper spheretechnique. The midwater trawl net had a mouth opening of about 30 x 30 m with a 17.5 mm liner cod end. The
sampling depth and the height of the mouth of the net were monitored with SIMRAD PI32 net monitor systemand the small-type temperature and depth recorders (TDR). Towing speed was 3-5 knots for the trawl and 2
knots for IKMT.
A total of 20 times midwater trawl survey was conducted. Of these, samplings at predetermined stations
were conducted 19 times to identify the species and size compositions of biological backscatterings detected by
the echosounder, and also to examine the distribution and abundance of squids and neustonic organisms like
Pacific saury that are difficult to detect with the echosounder. At each predetermined station, trawl net was
towed at 0-100 m or 0-30 m. A target trawling was made near Kushiro canyon to identify the species and size
compositions of backscatterings of slope water demersal fishes. 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. A part of sample was frozen at below –20˚C to measure caloric
value of the main prey species. IKMT samplings were conducted two times to identify the species and size
compositions of backscatterings of the krill. Samples were fixed in 10% buffered formalin seawater. A CTD cast
was made down to 500 m or near the bottom where depth was less than 500 m at each sampling station to17

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

measure temperature and salinity profile in the study area. Detailed methods and data of sighing survey of whale
are shown in Appendix 3 in the report.

RESULTS AND DISCUSSION
The results of trawling operations and the catches by species are shown in Table 2. The detail data ofoceanographic conditions are described in Appendix 3 in the report. While the acoustic data are being analyzing
now, the preliminary results on distribution, abundance and size composition of main prey species of minke
whale are depicted as follows mainly based on the data of predetermined trawl.
Among the small pelagic nektons that were distributed in the 0-50 m layer, Japanese anchovy (mainly
10-13 cm in scale length) was the most abundant and mainly captured from the continental shelf to the offshore
region of the eastern part of the study area (CPUE: 522 ± 738 kg / h, mean ± S.D.), where sea surface watertemperature (SST) was 16-18˚C (Fig. 2). The abundance of this species seems to be several times higher than in2005 when abundance of adult sized anchovy were very low due to recruitment failure of 2004 year class(Kawahara et al., 2005). However, this species was rarely distributed in the central and western part of the study
area where SST was 18-20˚C. Juvenile Japanese common mackerel (mainly 10-14 cm in fork length, FL) was
secondary abundant species and was mainly distributed in the area of 16-18˚C SST as was also shown inJapanese anchovy (4 ± 12 kg / h, Fig. 2). Japanese sardine (mainly 11-17 cm scale length) and Japanese common
squid (2-12 cm in dorsal mantle length) were sometimes captured, but their CPUE at each station was less than
0.5 kg / h (Table 2). In this year, CPUE data of commercial squid fishing (Hokkaido fisheries experimental
station, 2006) and bottom trawl data around continental shelf edge conducted by Hokkaido National Fisheries
Research Institute (Nishimura, unpubl. data) also indicated the low abundance of the squid off eastern Hokkaido
in summer and autumn.
The results of previous three years (in 2002, 2004, 2005) indicated that Pacific saury was one of theabundant epipelagic small fishes in this study area in autumn (Kawahara et al. 2003, 2004, 2005), however,catches of this species were extremely limited and only one individual (26.2 cm in knob length) was captured inthis year (Fig. 2). Furthermore, the fishing grounds of Pacific saury were restricted to the east of the study area
during the survey period. Considering that the SST of the habitat of Pacific saury off Kushiro was generally
lower than 15˚C in September and the SST of the most part of this study area was higher than 16˚C (Fig. 2),
these facts suggest that the southward migration of Pacific saury to the eastern Hokkaido was greatly delayed
due to an extrusion of the higher temperature water from the south.
The result of targeting trawl at the continental shelf region of Kushiro canyon, where is located in thecentral part of the survey area, indicated that backscatterings between 120-150 layer was mainly composed byadult walleye pollock (mainly 37-43 cm FL), followed by forked hake Laemonema longipes (mainly 44-48 cm
FL), which was firstly recorded in the prey species survey off Kushiro (see stn. 8 in Table 2). Krill was
distributed mainly at 100-150 m from the edge of the continental shelf to the oceanic region. Year-to-yearchange in abundance and distribution patterns of these species will be estimated in the future.
In summary, based on the predetermined trawl survey, the prey-rich environment for minke whales wasobserved in the eastern region off Kushiro in terms of abundance of Japanese anchovy although other epipelagic

18

SC/59/O7

nektons was rarely distributed in this area. In the western region off Kushiro, prey environment of the whales
seemed to be poor in terms of abundance of epipelagic nektons. The prey environment of the minke whale in the
0-50 m layer seems to largely fluctuate by year, which may be closely related to the hydrographic interaction
between the Oyashio and Kuroshio Currents. The acoustic and CTD data will be analyzed including datacollected by Kyoshin-Maru No. 2 and a comparison with data from the whaling survey will be made to estimate
the prey preference of minke whale.
We confirmed that generally acoustic survey of prey species and sighting survey of whale could be
conducted concurrently by Kaiko-Maru. However, sighting effort was naturally reduced because this survey
could not be conducted during the net sampling period. Furthermore, in case of Kaiko-Maru, both midwater
trawl and IKMT use the same winch and warp. When we exchange the both nets, about one hour is required andduring this time, we had to stop the sighting survey because this operation was needed all members of deck
workers and some of them concurrently hold the position of sighting investigators. Therefore, survey planningthat avoids frequent change of the both nets is needed in the further.

ACKNOWLEDGEMENT
A special thank is given to Captain K. Minami and crews of Kaiko-Maru for their assistance in collecting data.

REFERENCES
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 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 the western 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.
Kawahara, S., Watanabe, H., Ichihara, M., Suenaga,Y., and Kataoka, M. 2004. 2003 prey survey (coastal
component) of JARPN II. In the report of the 2003 JARPN II survey in the western North Pacific. Part II.
Coastal component-Coastal survey off Kushiro, northeast Japan. Paper SC/56/O14 submitted to the 56th IWC
Scientific Committee Meeting, Appendix 1. 15-20.
Kawahara, S., Yonezaki, S., Ichihara M. and Murase, H. 2005. Coastal prey species survey of JARPN II in 2004.
Appendix 1, pp 20-26. In: Kishiro, T., Kato, H., Yoshida, H., Miyashita, T., Ryono, T., Tabata, S., Okamoto,R., Yasui, K., Sato, H., Morita, Y., Saino, S., Hara, T., Ebisui, T. Kuroishi, H., Nishiwaki, S. and Kawahara,
S. 2005. Cruise report of the coastal survey on common minke whales off Kushiro, northeast Japan: the2004 JARPN II survey (Part II) – Coastal component. SC/57/O4 submitted to the 57th IWC ScientificCommittee Meeting, 37 pp.
Hokkaido fisheries experimental station. 2006. News of pelagic fishes around Hokkaido. Vol. 19, 2 pp.

19

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Table 1. Waypoints of planned track lines
LatitudeLogitudeArea

W-1 42 Þ11.0'N

WP

143 Þ49.0'E

Coast WestW-2 41 Þ56.0'N

143 Þ20.0'E

Coast WestW-3 41 Þ41.0'N

144 Þ07.5'E

Coast WestW-4 41 Þ26.0'N

143 Þ15.0'E

Coast WestW-5 41 Þ11.9'N

143 Þ51.5'E

Coast WestW-6 41 Þ00.0'N

143 Þ24.5'E

Coast WestC-1 42 Þ38.0'N

143 Þ49.0'E

Coast Central

C-2 41 Þ56.0'N

144 Þ04.0'E

Coast Central

C-3 42 Þ55.0'N

144 Þ19.0'E

Coast Central

C-4 42 Þ00.5'N

144 Þ34.0'E

Coast Central

C-5 42 Þ54.0'N

144 Þ49.0'E

Coast Central

C-6 42 Þ21.0'N

145 Þ00.0'E

Coast Central

E-1 42 Þ25.0'N

145 Þ00.0'E

Coast East

E-2 42 Þ59.0'N

145 Þ10.0'E

Coast East

E-3 42 Þ15.0'N

145 Þ25.0'E

Coast East

E-4 43 Þ05.0'N

145 Þ40.0'E

Coast East

E-5 42 Þ42.0'N

145 Þ55.0'E

Coast EastO-1 41 Þ45.0'N

144 Þ12.0'E

OffshoreO-2 41 Þ00.0'N

144 Þ42.0'E

OffshoreO-3 42 Þ11.0'N

145 Þ12.0E

OffshoreO-4 41 Þ00.0'N

145 Þ42.0'E

OffshoreO-5 41 Þ53.0'N

146 Þ00.0'E

Offshore

Table 2. Sampling data.
A) Midwater trawl
PredeteStn rmined/
target

Area

D/N

採集日

SST

LatitudeLongitude

Depth

Sampling
duration

(ÞC)

(ÞN)

(ÞE)

(m)

（minutes）

0-100
0-100

21
112

CPUE (kg/h）
Japanese Japanese Common Pacific Walleye Forked Other Common Other
anchovy sardine mackerel saury pollock
hake fishes squid squids
0
0
0
0
0
0
0
0
0
0.4
0
0
0
0.8
0
0.1
0.3
0

1
2

P
P

Coast West
Coast WestD
D

2006.9.12
2006.9.12

21
21.1

41-00.0 143-24.5
41-16.65 143-37.78

3

P

Coast WestD

2006.9.13

21.3

41-29.1

143-25.8

0-30

40

0

0

0

0

0

0

0

0

0

4
5

P
P

Coast West
Coast WestD
D

2006.9.13
2006.9.14

21.5
21.5

41-39.1
42-05.7

144-00.0
143-38.8

0-100
0-100

60
60

14.7
0

0
0

0
0

0
0

0
0

0
0

+
+

0
0

0
0

6

P

Coast Central D

2006.9.16

21.2

42-00.7

144-02.2

0-100

60

0.2

0

0

0

0

0

+

0

+

7
8

P
T

Coast Central D
Coast Central D

2006.9.16
2006.9.17

18.7
18.7

42-28.942-53.4

144-12.3
144-18.6

0-30
0-30

30
50

0
53.4

0
0

0
0

0
0

0
0.0

0
0.0

0
0

0
0

0
0.8

120-150

7

0

0

0

0

3120.0

238.3

0

0

0

9
10

P
P

Coast Central D
OffshoreD

2006.9.18
2006.9.19

17.7
20.8

42-18.96 144-28.87
41-07.5 144-39.8

0-100
0-100

45
60

0
+

0
0

0
0

0
0

0
0

0
0

+
0

0.1
0

+
+

11

P

Coast East

D2006.9.21

18.1

42-39.87 145-54.94

0-30

30

222.6

0

0

0

0

0

0

0

0

12

P

Coast East

D2006.9.21

14.8

42-59.3

145-45.6

0-30

15

902.4

0

0

0

0

0

0

0

0

13
14

P
P

Coast East
Coast East

D
D

2006.9.22
2006.9.22

17
17.3

42-43.56 145-33.23
42-14.1 145-24.7

0-100
0-30

60
5

0
2332.8

0
0

0
0

0
0

0
0

0
0

1.0
0

+
0

0
0

15

P

Coast East

D2006.9.23

15.2

42-38.44 145-15.43

0-30

30

145.6

0

0

0.1

0

0

0

0

0

16
17

P
P

Coast East
Coast East

D
D

2006.9.23
2006.9.24

14.8
18

42-39.3
42-24.3

145-04.3
145-00

0-30
0-100

30
45

1553.61295.6

0.2
0

0
47.4

0
0

0
0

0
0

0
0

+
0

0
0

18

P

Coast Central D

2006.9.24

15.9

42-51.1

144-48.6

0-30

30

676.6

0.3

0.4

0

0

0

0

0

0

19
20

P
P

Coast Central D
Coast Central D

2006.9.25
2006.9.26

18.2
15.9

42-30.2
42-00.7

144-42.6
144-35.0

0-30
0-100

30
45

122.0
0

0
0

0
6.6

0
0

0
0

0
0

0
0

0
0

0
0

3
3

B) IKMT
21

P

OffshoreD

2006.9.26

17.8

42-10.3

145-08.1

60
80
100

9

22

T

OffshoreD

2006.9.26

17.9

42-10.0

145-10.2

170

12

20

SC/59/O7

Fig. 1. Survey area and planned track lines of the prey species survey
in 2006 off Kushiro. Whaling was conducted mainly within 30(maximum 50) nautical miles from Kushiro.

Fig. 2. Distributions of (a) Japanese anchovy, (b) Japanese common mackerel, and (c) Pacific saurybased on the predetermined trawl samplings and distributions of isotherms at the sea surface off
Kushiro in September 2006.

21

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Appendix 2
Oceanographic conditions in the JARPN II research area off Kushiro,
northeastern Japan, in September 2006
Denzo Inagake1, Makoto Okazaki1, Koji Matsuoka2, and Shigeyuki Kawahara3
1

National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa,236-8648, Japan

2

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

3

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

Japan
Contact e-mail: ina@affrc.go.jp
ABSTRACTA prey species survey was conducted in September 2006 using Kaiko-Maru as a part of coastal component of JARPN II. The
survey covered a block where common minke whales were found. During the survey, oceanographic observation with CTD
was made to make clear the environment of their prey. Water masses in the survey area have characteristics of the

Oyashio water.

Introduction
A prey species survey was conducted in the JARPN II research area off Kushiro, northeastern Japan in
September 2006, using Kaiko-Maru in cooperation with the whale sampling survey (Fig. 1).
There are a lot of water masses and fronts in the western North Pacific. The Oyashio flows
southwestward along the Kuril Islands and turns eastward from the northeastern coast of Japan. The
Kuroshio flows northward from the tropical area to Tohoku area, east of Japan, and reaches near the
Oyashio front. Both major current, the Kuroshio and the Oyashio, form Kuroshio-Oyashio Inter-frontal
Zone. Water masses originated in the Kuroshio and the Oyashio are mixed each other in this zone and form
new water masses.
Each water mass in the western North Pacific has its own ecosystem, like a Kuroshio ecosystem, anOyashio ecosystem, warm-core ring ecosystem, etc. So, we must make clear the oceanographic condition
around whale’s prey to build up a marine ecosystem model in this area. In this paper, distribution of water
masses and fronts in the survey area will be described to make clear the environment for the prey ofcommon minke whales.

Data and Methods
Hydrographic observations with a conductivity-temperature-depth profiler (CTD; SBE 19) werecarried out from 12 to 26 September in the research area off Kushiro using Kaiko-Maru. Salinity22

SC/59/O7

compensation for CTD data was not done using water sampling data.
Oceanic fronts and water masses are usually detected by subsurface temperature map, because they are
obscure in sea surface temperature distributions from summer to fall seasons and the Oyashio water spreads
into the subsurface layer (Table 1). Axis of the Kuroshio Extension is defined by the 14°C isotherm at thedepth of 200m (Kawai , 1969). The warm water spread from Kuroshio Extension is defied by temperature
more than 10°C at the depth of 100 m. The first and the second Oyashio Intrusions are defined bytemperature less than 5°C at the depth of 100 m (Murakami, 1994). We use these indices to know the
distribution of water mass in the survey area.
The oceanographic conditions in September 2006 are detected by 100m and 200m temperature maps
using the monthly mean subsurface temperature from NEAR-GOOS database.

Oceanographic conditions in the research area
The upper panel in Figure 2 shows the Temperature-Salinity diagrams in the survey area.

There is no

typical Kuroshio water characterized by high salinity profile around 34.5psu, but Oyashio water
characterized by cold profile less than 5°C shown in Fig. 2. It is appear that water masses in the survey area
have characteristics of the Oyashio with warm surface water.
Figure 3 shows temperature and salinity maps at the depth of 100 m. All area have characteristics of thecold (less than 10°C) and low salinity (over 34 psu) water, especially the middle and eastern part of thisarea was occupied by Oyashio water, which is colder (less than 5°C) and lower salinity (less than 33.5 psu)
than the water in the western part of this area.
Figure 4 shows the vertical sections of temperature and salinity along the line shown in Figure 4. The
warm water, warmer than 15°C, lied at the surface layer upper 20 m depth, and seasonal thermocline lies
between 20 m and 100 m depth. Cold water was observed below the thermocline. All layers were occupied
by low salinity water, less than 34 psu.
Figure 5 shows the schematic hydrographic map in September 2006. The southern limit of the 1st
Oyashio Intrusion moves southward from April to November. The position of the 1st Oyashio Intrusion in
September 2006 was at 41ºN on 143º30’E line, which was a slightly northward position from monthly
mean location in September (40º20’N). Tsugaru warm water spread eastward to south of the Cape Erimo,and shows a front with the 1st Oyashio Intrusion. All stations in the survey area were distributed in the
Oyashio water defined by 100 m temperature which is colder than 5ºC.

REFERENCES

Kawai, H. (1969):

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

Suppl. to 16, 109-115.
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).

23

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Table 1.

Extraction method from temperature map to determine the position of each water mass.

Target characteristics

Extraction method

Kuroshio Extension Axis

14°C isotherm at 200m

Warm-core ringTemperature front at 200m

Oyashio front

5°C isotherm at 100m

Oyashio water

Area with T<5°C at 100m

Cold water
Warm water

Area with 5°C<T<10°C at 100m
Area with T > 10ºC at 100m and T < 14ºC at 200m

Figure 1.

Station map observed by Kaiko-Maru in 12-26 September 2006.

24

SC/59/O7

Figure 2.

Temperature-Salinity diagrams using CTD station data observed by Kaiko-Maru in 12-26

September 2006.

Each thin line in this figure denotes a density line of sigma-t.

Figure 3. 100 m temperature (left panel) and salinity (right panel) maps observed by Kaiko-Maruin 12-26 September 2006.

25

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Figure 4.

Vertical sections of temperature (left panel) and salinity (right panel) observed by
Kaiko-Maru in 12-26 September 2006.

Figure 5.

Schematic hydrographic map in Tohoku area, northwestern Pacific, in September 2006
station map observed by Kaiko-Maru.

26

with

SC/59/O7

Appendix 3
Cruise report of the dedicated sighting survey in 2006 JARPN II coastal
component off Kushiro, northeast Japan.
SHIGETOSHI NISHIWAKI1, HIROSHI KIWADA1, SAEKO KUMAGAI1, KEISUKE KIMURA1,
KOJI TAKESHITA2, HIROYUKI KOMIYA2, HIKARU WATANABE3 AND KOJI MATSUOKA1
1

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

2

Kyodo-Senpaku Kaisha, Ltd., 4-5 Toyomi-cho, Chuo-ku Tokyo, 104-0055, Japan

3

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

Yokohama, Kanagawa 236-8648, Japan
Corresponding E-mail address: nisiwaki@cetacean.jp

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 2006, as a part of coastal
component of 2006 JARPN II full scale study. The primary objective of the sighting survey was abundance
estimation of baleen whale in the survey area. The research vessel Kyoshin-Maru No.2 (KS2) and Kaiko-Maru(KK1) were dedicated to the sighting survey. Total searching distances were 1344.3 n.miles (994.0 n.miles by
KS2 and 350.3 n.miles by KK1). A total of 70 individuals of 49 schools primary sightings were made. They
included 13 common minke and 31 sperm whales.

INTRODUCITON
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 2006 as a partof coastal component of 2006 JARPN II full scale study (Government of Japan, 2004). The primaryobjective 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 this paper. Kyoshin-Maru No.2 andKaiko-Maru also conducted quantitative echo-sounder survey, and Kaiko-Maru also prey species survey
using mid-water trawl net and oceanographic observations. Results were described in Appendix 1 and 3.

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. Near shore area of the survey block where the water depth is lessthan 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 coastal area also divided into four small areas. 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 2 to 27 September 2006. Details of27

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiroitinerary were shown in Table 1. Kyoshin-maru No.2 (KS2, 372GT) and Kaiko-Maru (KK1, 860.25GT)
engaged in the cetacean sighting survey. Sighting survey procedures were same as offshore component of2006 JARPN II, but the survey mode was only restricted to passing mode (NSP). Natural marking recordand biopsy sampling experiments were attempted at grey, blue, humpback and right whales. Theseexperiments 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 and sighting positions of large baleen whales including common minke whales(Balaenoptera acutorotrata) and Sperm whales were shown on Fig 1. Total searching distances were1344.3 n.miles (994.0 n.miles by KS2 and 350.3 n.miles by KK1). A total of 70 individuals of 49 schools
primary sightings were made. They included 13 common minke and 31 sperm whales. Details of sightings
were listed on Table 2. Natural marking record and biopsy sampling experiments were not made. No large
baleen whale feeding behavior was observed. Relation between sighting positions of common minke
whales by the dedicated sighting surveys and the sea surface temperature is discussed in Appendix 4.

ACKNOWLEDGEMENT
Special thanks are given to the crews for their dedication in collecting data. The authors would like to thankDr. Hiroshi Hatanaka (The Institute of Cetacean Research).

REFERENCES
Government of Japan, 2004. Revised research plan for cetacean studies in the western North Pacific under
special permit (JARPN II). Paper SC/56/O1 submitted to the 56th IWC Scientific Committee, 14pp.
Table 1. Details of survey itinerary.
Date

Event

9/1

Kyoshin-Maru No.2 depart from Kushiro Port, Hokkaido, Japan

9/2

Kyoshin-Maru No.2 start sighting survey

9/11

Kaiko-Maru depart from Sendai-Shiogama Port, Miyagi, Japan

9/12

Kaiko-Maru start trawl trial survey, equipment examination

9/14

Kaiko-Maru arrive at Kushiro Port.

9/15

Kaiko-Maru depart from Kushiro Port

9/15

Both vessels were conducted calibration of quantitative echosounder

9/16

Kaiko-Maru start sighting and trawl survey

9/18

Kyoshin-Maru No.2 end sighting survey

9/20

Kyoshin-Maru No.2 arrive at Sendai-Shiogama Port

9/27

Kaiko-Maru end all survey

9/29

Kaiko-Maru arrive at Sendai-Shiogama Port, Miyagi, Japan28

SC/59/O7

Table 2. Summary of cetacean sightings.
Kyoshin-Maru No.2
Primary

Kaiko-Maru

SecondaryPrimary

Secondary
Sch.

Ind.

1

1

1

1

2

2

Species

Sch.

Ind.

Sch.

Ind.

Sch.

Ind.

Common minke whale

12

12

1

1

1

1

Bryde’s whale

1

1

Sei whale

3

4

Fin whale

1

1

8

8

Sperm whale

1023

Like common minke whale

2

2

1

1

1

1

Unidentified Large cetaceans

3

10

1

4

1

1

Unidentified cetaceans

2

2

4

4

Total

33

54

16

16

3

6

Fig 1. Sighting survey effort and sighting position of common Minke whales, Sei whales, Bryde’s whales,
Fin whales and Sperm whales in the 2006 JARPN II coastal survey by dedicated survey vessels“Kyoshin-Maru No.2” and “Kaiko-Maru”.

29Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Appendix 4

High sea surface temprature caused low influx of common minke whales tothe Kushiro water in September 2006
HIROTO MURASE, HIROSHI KIWADA, KOJI MATSUOKA AND SHIGETOSHI NISHIWAKI,
The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
Contact e-mail: murase@cetacean.jp

ABSTRACT
Dedicated sighting surveys of common minke whales off Kushiro were conducted in September in 2002, 2004, 2005 and2006 as a part of coastal component of JARPNII. Satellite derived data (Aqua-MODIS) showed that SST near the Kushiro
port (Block C) where the sampling of common minke whales took place remarkably high in 2006. Average SST in 2002,
2004, 2005 and 2006 in block C were 16.0, 16.3, 17.7 and 18.0 °C, respectively. Density index (DI, the number of schools
per 100 n.miles) of common minke whales in block C in 2006 was lowest among the surveyed years. DIs in 2002, 2004, 2005
and 2006 in block C were 12.1, 5.0, 2.7 and 2.0, respectively. Average SST at the positions of sightings of common minke
whales in block C in 4 years was 15.1. Frequencies of area of SST ≤ 16 °C in block C in 2002, 2004, 2005 and 2006 were
92.5, 80.7, 22.9 and 3.8 %, respectively. Small area of appropriate SST (≤ 16 °C) for common mike whales caused their low
influx to Block C in 2006. Magnitude of influx of common minke whales to the Kushiro water due to the southboundmigration would be controlled by the aerial extent of SST ≤ 16 °C. The number of commercial Pacific saury boats in block C
in 2002, 2004, 2005 and 2006 were 403, 36, 47 and 25, respectively. Average SST at the positions of commercial Pacificsaury fishing boats in block C in 4 years was 14.7. The influx of common minke whales to the Kushiro waters was coincidedwith the influx of Pacific saury which was one of major preys of them. But it was difficult to distinguish whether timing of
migration of common minke whales was regulated by oceanographic conditions, migration of Pacific saury, or combinationof both.

KEYWORDS: DISTRIBUTION, FEEDING MIGRATION, MINKE WHALE, NORTH PACIFIC, OYASHIO, PACIFICSAURY.

INTRODUCTION
It is recognized that the distribution of common minke whales (Balaenoptera acutorostrata) off Kushiro
Hokkaido, Japan in September is related to the distribution of Pacific saury (Cololabis saira) (Tamura andFujise, 2002). Because common mike whales actively feed a variety of species off Kushiro in September, it
is considered that they are still on the course of feeding migration from north to south. The first branch of
Oyashio, the subarctic western boundary current with cold low-salinity water, is extended to Kushiro waterfrom east side as season progress from summer to autumn but the shape and the extent show year to year
variations. Fishing grounds of Pacific saury off Kushiro in September was related to the positions of the
Oyashio front (5 °C water temperature isotherm at 100m) and their positions were shifted as the positionsof Oyashio front showed yearly variations (Yasuda and Kitagawa, 1996). Schematic map of oceanographic
futures in the western North Pacific was shown in Fig. 1 (Yasuda, 2003). Sea surface temperature (SST) is
better indicator for positions of fishing ground of Pacific saury. It was reported that mode of SST at thefishing sites of Pacific saury in this region was 15 °C (Watanabe et al., 2006). Given those evidences,30

SC/59/O7

migration pass of common minke whales off Kushiro in September could follow the seasonal extent ofOyashio and/or southbound migration of Pacific saury. In this paper, we investigate the relationshipbetween the oceanographic conditions and the distribution of common minke whales off Kushiro in
September. Specifically, the aims of this paper are to report (1) whether the influx of common minke
whales to Kushiro water in September is related to SST and (2) whether the distribution pattern of common
minke whales is related to distribution patterns of the fishing sites of Pacific saury.

MATERIALS AND METHODS
Sighting surveys of common minke whales were conducted off Kushiro, Hokkaido Japan in 2002, 2004,
2005 and 2006 as a part of the coastal component of the Japanese Whale Research Program under Special
Permit in the western North Pacific Phase II (JARPN II). Longitudinal boundaries of the survey area wereset at 143°15’E and at 146°E while latitudinal boundaries were set at the 50 m isobath and at 41°N (Fig. 2).
Surveys were conducted in September (Table 1). The survey area was stratified into two: offshore andcoastal strata. The boundary between those strata was set at 60 n.miles isodistance from coast line of
Hokkaido. Additonal straum off Hidaka sub-prefecture (between 142°30’E and 143°15’E) was surveyed in2005 and 2006. Coastal stratum was further divided into three strata. Stratified survey blocks were Offshore(O), coastal-East (E), coastal-Central (C), coastal-West (W), and off Hidaka sub-prefecture (H). A sighting
survey vessel (SV), Kyoshin-Maru #2 (372 GT), engaged in the sighting surveys. Primary observers wereallocated to the top barrel (3 observers) and the upper bridge. (2 observers). Zigzag tracklines wereconstructed within the survey area. Sampling survey of minke whales by small –type whaling catcher boats
within 30 n.miles from the Kushiro port was conducted independently from the sighting survey. Sighting
survey was also conducted within 30 n.miles from the Kushiro port as a part of the surveys in block C.
Area within 30 n.miles from the Kushiro port was term as Kushiro block (K) as a post-stratified block inthis paper. The starting points of tracklines were selected randomly. The sighting survey was conductedduring daylight hours. The nominal steaming speed of SV on the tracklines was 10 knot. Closing mode wasapplied in 2002 and in 2004 while passing mode was applied in 2005 and in 2006. In the passing mode,
abeam closing was conducted if the species of sightings were uncertain. Because school size of common
minke whales off Kushiro is generally 1 individual, application of passing mode is adequate.
School/individual density index (DI, the numbers of schools/individuals divided per 100 n.miles) was
calculated for each survey block in each year as an indicator of the extent of the influx of common minke
whales to Kushiro water. Average SST at the time of each sighting was summarized by each block in eachyear.
The number of position of commercial Pacific saury fishing boats was summarized by each blockin each year as an indicator of presence of Pacific saury. The data were prepared by the Japan Fisheries
Information Service Center (JAFIC). Monthly data from August to October were used in this analysis.
Although sighing survey of common minke whales was conducted only in September, data in August and
September were also used to see whether seasonal changes of fishing ground of Pacific saury showed
yearly fluctuations.
SST data derived from a satellite, Moderate Resolution Imaging Spectroradiometer (MODIS)31

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off KushiroAqua, were used to depict oceanographic condition. Daytime, Level-3 Standard Mapped Images were used.
Data were firstly extracted using The SeaWiFS Data Analysis System (SeaDas 4.0) developed at the NASA
Goddard Space Flight Center, USA.
Data of sightings, positions of fishing boats and SST were overlaid using a geographic
information system (GIS) “Marine Explorer version 4” (Environment Simulation Laboratory, Japan). The
area in 1 °C SST increment was also calculated using the GIS.

RESULTS
Entire survey area
The surveyed tracklines and the sighting positions of common minke whales were overlaid on the SST
maps (Fig. 3). The fishing positions of commercial Pacific saury fishing boats in September in 2002, 2004,
2005 and 2006 were overlaid on the SST maps (Fig. 4). Those maps suggested that overall SST in thesurvey area was getting higher from 2002 to 2006. Mean SST was increased from 17.3 °C in 2002 to
19.4 °C in 2006 (Table 2). Frequency of number of sightings of common minke whales by SST (1 °C
increment) was shown in (Fig. 5). Average SST in 4 years at the positions of the sightings of common
minke whales was 15.5 (CV=12.4%, n=87) while it in 2006 was 19.1 (CV=6.0%, n=12) (Table 2).
Frequency of number of the Pacific saury fishing boats by SST (1°C increment) was shown in (Fig. 6).
Mean SST in 4 years at the fishing positions of commercial Pacific saury boats was 15.1 (CV=10.2%,
n=2646) while it in 2006 was 16.4 (CV=10.3%, n=450) (Table 2). The number of fishing boats was less in
2006. Frequency of area (n.mile2) of SST ≤ 16 °C and 16 °C < in all survey blocks in September in 2002,
2004, 2005 and 2006 was summarized in Fig. 7. Because mean SST at the sighing positions of common
minke whales was 15.5, 16 was selected as a cut point. Area of SST ≤ 16 °C was shrinking as year progress.
DI was lowest in 2006 (Table 2).

Block K and C
Overall patterns of the SST distributions, the sightings of minke whales and the positions of commercial
Pacific saury fishing boats in blocks near the Kushiro port (K and C) were similar to those in entire survey
area (Table 2 and Figs. 8 and 9). Average SST in Block C in 4 years at the positions of sightings ofcommon minke whales was 15.1 (CV=10.1%, n=60) while it in 2006 was 18.7 (CV=3.9%, n=5) (Table 2).
Mean SST in 4 years at the fishing positions of commercial Pacific saury boats was 14.7 (CV=7.4%,
n=511) while it in 2006 was 15.7 (CV=0.8 %, n=25). In 2002, 15.0 °C isotherm SST front was remained inblock K and C and it was not extended to block E (Fig. 3). In 2006, 15.0 °C isotherm SST front was notobserved in 2006. In 2004, 15.0 °C isotherm SST front was extended to block W. In 2005, 15.0 °C
isotherm SST front was remained eastern part of blocks K and C. DIs in block C decreased from 2002 to2006 as the average SST in the block increased. Because the coverage of the sighting effort in block K wasinsufficient and heterogeneous in each year, inter-year comparisons of DIs were difficult. Though SST inblock K was as in the case of the entire survey area as well as block C, DIs didn’t decreased in consistentmanner. But DIs in 2006 were lower than that in 2002. Frequency of area of SST ≤ 16 °C in blocks K and
C was decreased from 2002 to 2006.

32

SC/59/O7

Blocks other than K and C
Few sightings were made in blocks O and H where average SSTs were high regardless of years (Table 2).
DI was highest in block W in 2002 when 15.0 °C isotherm SST front was intruded in the block (Fig. 3). DI
in block E 2004 was low in comparisons with other years. In the rest of years (2002, 2005, 2006) 15.0 °C
isotherm SST front was not extended to block W. Especially in 2005 and 2006, DIs in block E were higher
than that in block C.

Oceanographic conditions and fishing boats operation in August and October
Maps of SST in August and October in 2002, 2004, 2005 and 2006 were shown in Fig. 10. Positions ofcommercial Pacific saury fishing boats were overlaid in the maps. SST in the Kushiro water was high in
August except 2002. In 2002, SST off Kushiro was already low enough to operate commercial Pacificsaury fishing boats. SST was decreased from August to September in each year but magnitude of lowering
was slow in 2002. SST continuously decreased from September to October. Average temperature in
October in 2006 was similar to the rest of years (Table 3). Abrupt shift of fishing positions of commercial
pacific saury fishing boats from Hokkaido to Sanriku was observed in 2006.

DISCUSSION
As in the case of Pacific saury, influx of common minke whales to the Kushiro water was regulated by SST.
Few common minke whales migrated to the Kushiro water when SST was higher than 15 °C. It wasreported that mode of SST at the Pacific saury fishing boat operation sites was 15 °C (Watanabe et al.,2006). Timing of migration of Pacific saury to the Kushiro water showed remarkable change as theoceanographic conditions showed yearly fluctuations (Fukushima, 1979). Migration cue to the Kushiro
water for both common minke whales and Pacific saruy was same. At this stage, it was difficult todistinguish whether timing of migration of common minke whales was regulated by oceanographic
conditions, migration of Pacific saury, or combination of both. Lower DIs of common minke whales in
September in 2006 can be explained by high SST in the Kushiro water.
Pacific saury continues southbound migration in October. Pacific saury migrates to the Sanriku
water when SST was below 20 °C (Watanabe et al., 2006). Model predictions suggested that catch ofPacific saury in the Kushiro water was highest in mid to late September and substantially decreased in
October and catch in the Sanriku water increased as the result of migration (Watanabe et al., 2006). Timingof migration from the Kushiro water to the Sanriku Water was also regulated by the oceanographic
conditions and changed year to year (Yasuda and Watanabe, 1994). In general, migration of Pacific sauryfrom the Kushiro water to the Sanriku water is continuous as in the cases in 2002 and 2005. But thepositions of commercial Pacific saury fishing boats showed abrupt shift from the Kushiro water to theSanriku water in 2006. Probably, the abrupt shift of the fishing positions could be related to the rapid
decrease of SST October 2006 though it was not detected in this analysis because monthly SST data wereused. It can be hypothesised that common minke whales continue their southbound migration as in the caseof Pacific saury. If that is the case, number of common minke whales could change given theoceanographic conditions. Because of scarcity of distribution data of common minke whales after October,33

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

it is difficult to conclude it at this stage.

ACKNOWLEDGEMENT
Authors expressed thanks to all the crews and researchers who engaged in the coastal component of
JARPNII off Kushiro. Comments from Drs. Hiroshi Hatanaka and Yoshihiro Fujise at the Institute of
Cetacean Research and Dr. Hidehiro Kato at Tokyo University of Marine Science and Technology
remarkably improved the manuscripts. We also expressed thank you to Ms. Tomoko Hasegawa for the data
management. Dr. Kazuyoshi Watanabe at the Japan Fisheries Information Service Center kindly provided
us the data of the Pacific saury fishing boats.

REFERENCES
Fukushima, S. 1979. Synoptic analysis of migration and fishing conditions saury in the northwest Pacific
Ocean Bull. Tohoku Region. Fish. Res.Lab. 41:1-70.
Tamura, T., and Y. Fujise. 2002. Geographical and seasonal changes of the prey species of minke whale in
the Northwestern Pacific. ICES J. Mar. Sci. 59:516-528.
Watanabe, K., E. Tanaka, S. Yamada, and T. Kitakado. 2006. Spatial and temporal migration modeling forstock of Pacific saury Cololabis saira (Brevoort), incorporating effect of sea surface temperature. Fish.
Sci. 72:1153-1165.
Yasuda, I. 2003. Hydrographic structure and variability in the Kuroshio-Oyashio Transition Area. J.
Oceanogr. 59:389-402.
Yasuda, I., and D. Kitagawa. 1996. Locations of early fishing grounds of saury in the north-western Pacific.
Fish. Oceanogr. 5:63-69.
Yasuda, I., and Y. Watanabe. 1994. On the relationship between the Oyashio front and saury fishinggrounds in the north-western Pacific: a forecasting method for fishing ground locations. Fish. Oceanogr.
3:172-181.

Table 1. Survey periods.
Year

Start

End

2002

11 Sep27 Sep2004

10 Sep27 Sep

2005

2 Sep

19 Sep

2006

1 Sep

20 Sep34

SC/59/O7

Table 2. Summary of sightings of common minke whales, SST in surveyed area and commercial Pacificsaury fishing boats in the survey area. Note that the number of commercial Pacific saury fishing boats on
the boundary lines of survey blocks were counted for both blocks thus total number of each blocks slightly
exceed the numbers in all blocks. DI is the number of school/individuals per 100 n.miles.
Common minke whalesighting survey
Year

SST in survey blocks(MODIS-Aqua)

Commercial
Pacific sauryboats

Effort(n.miles)

Sch.

Ind.

Avg.
SST
(°C)

DI
(Sch.)

DI(Ind.)

Avg.
SST
(°C)

Area
≤16ºC
( %)

Area
16ºC<
(%)

#
of
boats

Avg.
SST
(°C)

2002

681.5

38

40

14.3

5.6

5.9

17.3

55.1

44.9

1815

14.8

2004

809.4

17

18

15.4

2.1

2.2

17.4

35.8

64.2

256

14.9

2005

827.1

20

21

15.6

2.4

2.5

18.7

10.2

89.8

125

15.5

2006
Block K

994.0

12

12

19.1

1.2

1.2

19.4

3.6

96.4

450

16.4

2002

66.2

11

12

14.4

16.6

18.1

15.8

100.0

0.0

22

13.9

2004

89.9

5

6

15.6

5.6

6.7

16.2

94.2

5.8

7

15.4

2005

145.5

5

5

15.8

3.4

3.4

16.9

58.5

41.5

36

14.9

2006
Block C

85.0

4

4

19.0

4.7

4.7

18.0

8.2

91.8

0

-

2002

272.6

33

34

14.4

12.1

12.5

16.0

92.5

7.5

403

14.6

2004

238.7

12

13

15.5

5.0

5.4

16.3

80.7

19.3

36

15.0

2005

365.3

10

11

15.4

2.7

3.0

17.7

22.9

77.1

47

15.0

2006
Block E

247.4

5

5

18.7

2.0

2.0

18.5

3.8

96.2

25

15.7

All Blocks

2002

73.5

5

6

13.8

6.8

8.2

15.7

100.0

0.0

431

14.2

2004

140.6

1

1

15.1

0.7

0.7

15.2

97.6

2.4

56

15.0

2005

127.7

9

9

15.3

7.0

7.0

17.2

42.5

57.5

81

15.5

2006
Block W

145.0

5

5

18.9

3.4

3.4

17.9

24.2

75.8

324

16.5

2002

48.2

0

0

-

0.0

0.0

18.0

6.9

93.1

305

15.2

2004

164.9

3

3

14.9

1.8

1.8

17.4

34.2

65.8

59

15.6

2005

180.3

1

1

20.7

0.6

0.6

18.4

5.0

95.0

0

-

2006
Block O

161.9

1

1

20.0

0.6

0.6

19.3

0.0

100.0

4

16.7

2002

287.2

0

0

-

0.0

0.0

17.1

62.4

37.6

664

15.0

2004

265.2

1

1

17.4

0.4

0.4

17.7

9.0

91.0

105

14.5

2005

41.7

0

0

-

0.0

0.0

19.0

0.0

100.0

7

18.1

2006
Block H

285.3

0

0

-

0.0

0.0

20.1

0.0

100.0

98

16.2

2002

-

-

-

-

-

-

19.9

0.0

100.0

17

16.9

2004

-

-

-

-

-

-

20.1

0.0

100.0

0

-

2005

112.1

0

0

-

0.0

0.0

20.9

0.0

100.0

0

-

2006

154.4

1

1

21.3

0.6

0.6

20.1

0.0

100.0

0

-

35

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Table 3. Average SST in each survey block in September and October in 2002, 2004, 2005 and 2006. The
numbers of commercial Pacific saury fishing boats and the average SST at the operation sites are also
shown.
Average SST(MODIS-Aqua)
Year

Commercial Pacificsuary boats
Sep.

Oct.

Sep.
(°C)

Oct.
(°C)

#
of
boats

Avg.
SST
(°C)

#
of
boats

Avg.
SST
(°C)

2002

17.3

14.7

1815

14.8

398

12.7

2004

17.4

15.0

256

14.9

284

14.1

2005

18.7

16.2

125

15.5

171

14.7

2006
Block K

19.4

14.7

450

16.4

156

13.2

2002

15.8

12.9

22

13.9

13

12.5

2004

16.2

13.9

7

15.4

101

14.3

2005

16.9

14.4

36

14.9

15

14.3

2006
Block C

18.0

13.4

0

-

6

14.7

2002

16.0

13.2

403

14.6

67

12.7

2004

16.3

13.8

36

15.0

149

14.1

2005

17.7

14.6

47

15.0

55

14.5

2006
Block E

18.5

13.6

25

15.7

43

14.9

2002

15.7

13.1

431

14.2

206

12.5

2004

15.2

14.1

56

15.0

90

14.2

2005

17.2

14.9

81

15.5

51

14.4

2006
Block W

17.9

12.2

324

16.5

70

12.1

2002

18.0

14.5

305

15.2

50

12.5

2004

17.4

14.9

59

15.6

23

14.2

2005

18.4

15.8

0

-

45

15.2

2006
Block O

19.3

15.2

4

16.7

10

16.2

2002

17.1

14.8

664

15.0

83

13.1

2004

17.7

14.9

105

14.5

21

14.4

2005

19.0

16.8

7

18.1

19

14.6

2006
Block H

20.1

14.7

98

16.2

33

12.3

2002

19.9

18.2

17

16.9

-

-

2004

20.1

17.8

0

-

6

14.1

2005

20.9

18.4

0

-

7

15.5

2006

20.1

17.3

0

-

-

-

All Blocks

36SC/59/O7

Fig. 1. Schematic map of surface current, fontal structure and water mass in the western North Pacific. This
is Fig.1 of Yasuda (2003). EKC: East Kamchatka Current, WSAG: Western Subarctic Gyre, ESC: East
Shakalin Current, OY: Oyashio, KE: Kuroshio Extension, TC: Tsushima Warm Current, SAF: Subarctic
Front, SAB: Subarctic Boundary, KBF: Kuroshio Bifurcation Front, STF: Subtropical Mode Water,
S-CMW: Shallow Central Mode, D-CMW: Dense Central Mode Water, DSW: Dense Shelf Water,
OSMW: Okhotsk Sea Mode Water, Yellow circles: warm-core rings, Light green circles: cold-core rings.

Fig. 2. Surveyed blocks off Kushiro: Offshore (O), coastal-East (E), coastal-Central (C), coastal-West (W),off Hidaka sub-prefecture (H) and Kushiro block (K).

37

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

2002

2004

2005

2006

Fig. 3. Surveyed tracklines (black lines) and sighing positions of common minke whales (open circles) off
Kushiro in September in 2002, 2004, 2005 and 2006. Monthly mean SST derived from Aqua-MODIS isalso shown. White line represents the boundary of survey blocks.

38

SC/59/O7

2002

2004

2005

2006

Fig. 4. Fishing positions of commercial Pacific saury fishing boats (open square) in September in 2002,
2004, 2005 and 2006. Monthly mean SST derived from Aqua-MODIS is also shown. White line represents
the boundary of survey blocks.

39

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

Frequency (%)

50.0
45.0

2006

40.0

2005

35.0

2004

30.0

2002

25.0
20.0
15.0
10.0
5.0
0.0

9

10

11

12

13

14

15

16

17

18

19

20

21

2006

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

2.6

2.8

8.7

1.5

1.6

2005

0.0

0.0

0.0

0.0

0.0

3.2

16.0

2.4

0.0

0.0

0.0

1.5

0.0

2004

0.0

0.0

0.0

0.0

0.0

4.3

12.6

1.2

1.3

0.0

0.0

0.0

0.0

2002

0.0

0.0

0.0

6.4

7.9

8.6

16.0

1.2

0.0

0.0

0.0

0.0

0.0

SST ( ℃)

Fig. 5. Frequency of numbers of sightings of common minke whales by SST (1 °C increment) in all survey
blocks in September in 2002, 2004, 2005 and 2006. SST at the positions of sightings were used.

40.0

Frequency (%)

35.0
30.0

2006

25.0

2005

20.0

2004
2002

15.0
10.0
5.0
0.0

9

10

11

12

13

14

15

16

17

18

19

20

21

2006

0.0

0.0

0.0

0.0

0.2

3.2

4.6

3.3

0.6

3.7

1.5

0.0

0.0

2005

0.0

0.0

0.0

0.0

0.3

1.5

1.4

0.5

0.8

0.2

0.0

0.0

0.0

2004

0.0

0.0

0.0

0.0

0.1

6.4

2.2

0.5

0.5

0.0

0.0

0.0

0.0

2002

0.3

0.7

1.6

3.4

11.4

16.3

25.3

7.4

0.9

0.5

0.8

0.1

0.0

SST (℃)

Fig. 6. Frequency of numbers of commercial Pacific saury boats by SST (1 °C increment) in all survey
blocks in September in 2002, 2004, 2005 and 2006. SST at the positions of sightings were used.

100%

Frequency (%)

80%
60%

16 ℃＜

≦16 ℃

40%
20%
0%

2002

2004

2005

2006

16℃＜

44.9

64.2

89.8

96.4

≦16 ℃

55.1

35.8

10.2

3.6

Year

Fig. 7. Frequency of area (n.mile2) of SST ≤ 16 °C and 16 °C < in all survey blocks in September in 2002,
2004, 2005 and 2006.

40

SC/59/O7

2002

2004

2005

2006

Fig. 8. Surveyed tracklines (black lines) and sighing positions of common minke whales (open circles) in
Block C and K in September in 2002, 2004, 2005 and 2006. Monthly mean SST derived from
Aqua-MODIS is also shown. White line represents the boundary of block C while pink line represents theboundary of block K.

41

Yoshida, et al.: Report of the JARPN II in 2006 - Coastal Component off Kushiro

2002

2004

2005

2006

Fig. 9. Fishing positions of commercial Pacific saury fishing boats (open square) in September in 2002,
2004, 2005 and 2006.

Monthly mean SST derived from Aqua-MODIS is also shown. White line

represents the boundary of block C while pink line represents the boundary of block K.

42

SC/59/O7

2004

2005

2006

Oct

Sep

Aug

2002

Fig. 10. Fishing positions of commercial Pacific saury fishing boats (open square) in August, September
and October in 2002, 2004, 2005 and 2006. Monthly mean SST derived from Aqua-MODIS is also shown.
Red line represents 15.0°C SST isotherm while purple line represents 20.0°C SST isotherm.

43