SC/58O10

SC/58/O10

Cruise report of the Second phase of the Japanese Whale Research
Program under Special Permit in the western North Pacific (JARPNII) in 2005 – Coastal component off Kushiro
TOSHIYA KISHIRO1, HIDEHIRO KATO2, HIDEYOSHI YOSHIDA1, TOMIO MIYASHITA1, TAMEO RYONO3,
SHIGEO TABATA3, KUNIHIRO YASUI3, HITOMI SATO3, YUKA MORITA3, KEI KUMAGAYA3, DAISUKETOKUDA3, KAZUYOSHI NAKAI3, NOBUFUMI FUNABASHI3, TADASHI EBISUI3, TOSHITAKA
WAKATSUKI3, MITSUNORI SAKAGUCHI3, TADASHI HOUHANA3, SHIGETOSI NISHIWAKI3

AND

1

SHIGEYUKI KAWAHARA

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

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

2

Tokyo University of Marine Science and Technology, 1-5-7, Konan, Minato-ku, Tokyo, 108-0075 Japan

3

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

ABSTRACTThe third survey of revised JARPN II coastal component was conducted from 7 September to 12 October 2005, off
Kushiro, northeast 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. 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 6,653.7 n. miles (602.3 hours) was searched
for whale sampling, 144 schools/ 145 individuals of common minke whales were sighted and 60 whales were
sampled. Average body length of sampled whales was 6.77m (SD=1.07, n=45) for males and 5.48m (SD=0.60, n=15)
for females, respectively. Dominant prey species found in the forestomach contents were Japanese anchovy Engraulisjaponicus (43.3%), Krill Euphausia pacifica (31.7%) and walleye pollock Theragra chalcogramma (18.3%). The
concurrent prey survey revealed the distribution of those prey species in the research area, and the dedicated sighting
survey sighted 20 schools/ 21 individuals of common minke whales with 827.1 n. miles searched. Sighting ratio andbody length frequency of sampled whales were similar to those in 2004 survey but composition of prey species foundin the forestomach was different and Krill was relatively dominant compared with the results of the last two years
surveys. Those results suggested the existence of the large yearly change in the feeding habit and migration ofcommon minke whales in the coastal waters off Kushiro and the variability in the effects of the whales for the local
coastal fisheries and the inshore marine ecosystem.

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

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Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

INTRODUCTION
The full-scale surveys of the second phase 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 the surveys 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 marine ecosystem, and iii) stock structure of whales (Government ofJapan, 2002).
The full-scale JARPN II involves two survey components; ‘offshore’ which is covered by the
Nisshin Maru research vessels and ‘coastal’ which is covered by small-type whaling catcher boats,and the latter one is necessary to cover the temporal and spatial gaps, which can not be covered by
the Nisshin maru research vessels (Government of Japan, 2002).
Based on the results of the two-year feasibility study conducted in 2002 and 2003 (Kishiro, et al.,2003, Yoshida, et al., 2004, Government of Japan, 2004a), the coastal survey component has beenrevised to be conducted twice a year, with 60 common minke whales being sampled in the spring
and autumn seasons, respectively (Government of Japan, 2004b). Revised survey was started in 2004
autumn season. The second (but first one of revised plan) survey was carried out during 13
September to 31 October and took 59 common minke whales in the coastal waters off Kushiro,
northeast Japan (Kishiro, et al., 2005). In 2005, at first, the survey was conducted in spring season
form 11 April to 21 May in the coastal waters off Sanriku district, and took 60 common minke
whales (Yoshida, et al., 2006). And then the present survey was conducted in autumn season off
Kushiro as the third survey in the revised JARPN II coastal component. In this paper, we presented
an outline of the survey of 2005 JARPN II coastal component conducted in the waters off Kushiro,
northeast Japan, from 7 September to 12 October 2005.
The present survey was authorized by the Government of 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 Research Agency, planned and conducted this survey entrusted
by the Institute of Cetacean Research (ICR).
Response to the discussion in the IWC/SC meeting
The revised JARPN II research plan was presented in the 56th IWC/SC annual meeting (Governmentof Japan, 2004b), and the result of the first revised survey off Kushiro in 2004 was submitted to the57th IWC/SC annual meeting (Kishiro, et al., 2005). Although some discussions were made at thosemeetings, there remained divided views in the Committee members and no critical or agreed
recommendation for the research plan was made (IWC, 2005; 2006). Thus, the 2005 surveys wereconducted following the original plan and the almost same methodology in the 2004 revised surveys.
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MATERIALS AND METHODS
The survey consisted of three research components as follows; 1) coastal whale sampling survey bysmall-type whaling catcher boats, 2) coastal prey species survey by one echo sounder-trawl survey
vessel and 3) dedicated sighting survey by one large research vessel. The dedicated sighting survey
using small-type whaling catcher boat which was tentatively introduced in 2004 was not carried out
in the 2005 survey due to the logistic reasons as mentioned in Kishiro, et al., 2005.
Research area
The research area was same to the previous surveys (Kishiro, et al., 2003; 2005), 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
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 the whale sampling vessels. The sampling survey was conducted from 7
September to 12 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 the by-products.
Prey species survey
The Kaiyo Maru No.7 (KY7; 499.0GT) conducted the echo sounder-trawling survey in wider
research area off east coast of Hokkaido, from 11 to 28 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 1 to 21 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.
Sampling survey by small-type whaling catcher boat
As same as the former surveys in 2002 and 2004 (Kishiro et al., 2003; 2005, Yoshida et al., 2004),
the research head office was placed in the research station and controlled the sampling vessels during
the survey. All catcher boats were engaged as the sampling vessels. To avoid the concentration ofsampling location, two types of the sampling (searching) measure were planed as follows.

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Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Type 1 sampling
Based on the information of the whale distribution obtained by the dedicated sighting survey and thepast sampling surveys, the research head office arbitrarily determined the searching area and route(direction from the port) for each sampling vessel in every day. Weather conditions and information
on fishing grounds of prey species were also considered.
Type 2 sampling
If the sampling positions tend to be concentrated in restricted area, the research area would be
divided into four sectors as shown in Figure 2, and the searching area of sampling vessels would beevenly allocated to those sectors. Although we planed this type of surveys, the type 2 sampling was
not conducted, since all of the research area could be covered by the type 1 sampling surveys.
In each vessel, a researcher was on board and recorded the cruise tracks, searching time on effort,
sea weather conditions and sighting data. Sighting data would be collected for all baleen whales,
sperm whales, Baird’s beaked whales, killer whales and short-finned pilot whales. The vessel
principally continued to cruise and search along the predetermined direction until arrived at 30 n.
miles from the port, and then freely cruised in the waters within the 30 n. miles (maximum 50 n.
miles) radius from the port. Searching was carried out during the day and the vessels returned to theport every night. Sighting was conducted from the top barrel and upper bridge by all the crews andresearcher with vessel speed at about 11 knots. All common minke whales sighted were targeted forsampling, except for the cow-calf pair. When a sighting consisted of more than one animal, firsttargeted animal 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, to land the animal on the research station. At the port, the sampled whale was lift up fromthe vessel using wire nets and a crane and transported to the station by an 11 tons freight trailer. At
that time, body weight of the whale was measured with the truck scale.
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 3, with the number of data and samples
obtained. These items were related to studies on feeding ecology, stock structure, life historicalbiology and pollutions. In addition, staff of the Obihiro University of Agriculture and Veterinary
Medicine collected samples of sperms (from 10 males) and oocytes (4 females) for in vitro
fertilization study, which had been conducted under the cooperative study with the ICR.
RESULTS
Effort and sightings by the sampling vessels
The cruise tracks made by the sampling vessels (28T, 75K, 31S and 7K) during the survey are shown4

SC/58O10

in Fig.3. The searching areas covered widely coastal waters within 30 nautical miles form theKushiro port. Searching distance and time are shown in Table 1. 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 6,653.7 n. miles and 602.3
hours, respectively.
Fig.4 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 144 schools/ 145 individuals of common minke whales
were sighted, consisting of 135 schools/ 136 individuals of primary sightings and 9 schools/ 9
individuals of secondary sightings (Table 1). These figures probably include some duplicatedsightings because sampling vessels searched almost same areas in every day. In addition, fin whale(1 school/ 1 individual) and some small cetaceans were sighted during the survey (Table 1).
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 2. Both SPUE and DI
decreased from the middle of September to late of September, but increased in the early of October.
During the total research periods, 0.22 schools was primary sighted per one hour searched, and 2.03
schools was primary sighted per 100 n. miles searched. These figures are nearly the half of thatrecorded in 2002 survey (Kishiro, et al., 2003), but almost same as that recorded in the last year
2004 survey (Kishiro, et al., 2005).
Sampling of common minke whales
A total of 60 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.4 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 (KY7) 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 and walleye pollack
were found in the research area but Pacific saury was relatively scarce as compared with the 2004
survey. The large-scale dedicated sighting survey using sighting vessel (KS2) were conducted in thesame research areas of the prey species survey, and sighted 20 schools/21 individuals of common
minke whales with 827.1 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
5

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro(the oceanographic observations).
Sex ratio, body length and weight of sampled whales
The 60 sampled whales were consisted of 45 males and 15 females (sex ratio of males was 0.75).
Average body length of the whales was 6.77m (max=8.29, min=4.12, SD=1.07) for males and 5.48m(max=6.45, min=4.66, SD=0.60) for females, respectively (Table 4). Average body weight was 3.78
tons (max=6.26, min=0.66, SD=1.51) for males and 1.95 tons (max=3.16, min=0.98, SD=0.66) for
females, respectively (Table 5). In both males and females, the average body length and weight werethe lowest in the middle of September. Composition of sex and sexual maturity of common minke
whales is listed in Table 6. In males, 30 of 45 individuals were sexually mature (66.7%), and thisfigure was almost same as the 2004 survey (66.0%, n=47). On the other hand, all females sampledwere immature (n=15), and sexually mature females was not observed. Among them, one immature
male (body length=5.11m, body weight=1.50t, mean testis weight=76.5g) was thought to be sexually
undeveloped, because the penis could not be observed and shape of the testicles were also unique(long and narrow). Further examinations such as the detailed histological or sex chromosome
analyses will be conducted for this individual in future.
Pray species of common minke whale found in the stomach contents
We could examine 60 stomach contents of common minke whales. Following the same methods
conducted in the JARPN II feasibility surveys (Fujise, et al., 2002) and the former coastal
component surveys (Kishiro, et al., 2005) stomach contents were weighted to the nearest 0.1 Kg byeach four chamber in both cases of including and excluding liquid. Then, a sub-sample offorestomach contents was collected and frozen for the later laboratory work. Major prey species
found in the forestomach contents were Japanese anchovy Engraulis japonicus (43.3%, 26 out of 60
whales), Krill Euphausia pacifica (31.7%, 19 whales) and Walleye pollock Theragra chalcogramma(18.3%, 11 whales). Only one whale mainly fed on Pacific saury Cololabis saira (1.7 %) and two
whales fed on Japanese common squid Todarodes pacificus (3.3%). The range of forestomach
contents weights was form 0.14Kg to 131.6Kg, and the maximum of % body weight was 3.1 %. This
whale fed on small-sized Walleye pollock.
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 118 tons.
Fishing grounds of coastal fisheries during the 2005 survey period
Fig.5 shows the distribution of fishing grounds of the local coastal fisheries for Pacific saury (dip net
fisheries), Japanese anchovy (purse seine fisheries) and Japanese common squid (jigging fisheries)6

SC/58O10

around the coastal waters off Kushiro during the 2005 survey period (Japan Fisheries Information
Service Center, 2005). In early to middle of September, the fishing ground of Pacific saury was
scarce and distributed in out side of the research area (farther than 30 n. miles from the Kushiro port),and some squid jigging fisheries were operated in the near shore areas. In late of September to earlyof October, the fishing ground of Pacific saury was expanded and somewhat concentrated in the
research area off Kushiro. The fishing ground of Japanese anchovy was distributed along the coastal
waters off Sanriku district (out side of the research area) during the whole survey period.
DISCUSSION
The present survey was the third survey of the revised JARPN II coastal component to take 60
common minke whales off Japan and of which conducted in the autumn season off Kushiro, east
coast of Hokkaido. There was no practical problem in conducting the surveys as same as the former
surveys. Although bad weather conditions such as a typhoon, the low atmospheric pressures and thefog partly prevented our research activities as same as the 2004 surveys, we could obtain the planed
sample size of 60 common minke whales during the survey period of 36 days from 7 September to
12 October.
Composition of common minke whales sampled was similar to those in the 2004 survey off Kushiro,i.e. sex ratio of males in the samples was higher and body length frequency of the whales inclined
toward large-sized mature males as compared with the results of the 2002 feasibility study off
Kushiro (Fig. 6), and furthermore, mature female was not observed in the present survey. Sighting
ratio (SPUE and DI) of common minke whales by the sampling vessels was also same as that of the2004 survey (nearly the half of that in the 2002 survey) and the distribution of the whales in thesurvey area was relatively dispersed with no concentrated area (Table 2 and Fig.4). These results
suggested that the timing of the migration of common minke whales into research area was similar to
those in 2004, and the migration of main groups including mature females was also scarce at thetime in 2005 survey period, as supposed in 2004 (Kishiro, et al. 2005).
However, composition of prey species found in the stomach contents in the present survey wasapparently different and Krill was relatively dominant compared with the results of last two years
surveys (Fig.7). The amount of Pacific saury (which was one of the major prey species in 2004) was
especially small and only one whale mainly fed on this species. These differences are thought to berelated to the yearly variation in the oceanographic condition and prey species distribution. The
results of the prey species survey (Appendix 1) and the oceanographic observations (Appendix 3)
suggested that the northward extrusion of warm water mass occurred in the 2005 autumn season off
Kushiro possibly prevented migration of Pacific saury from the offshore waters to the coastal
research area during the survey period. Furthermore, the prey species survey revealed that theabundance of Japanese anchovy in the research area was also lower in 2005 compared with the7

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiroprevious surveys. The distribution of fishing grounds for those species also supported above results(Fig.5). It is supposed that those circumstances might be not favorable for lactating or pregnant
female common minke whales to visit there, since they are thought to be needed more energy costthan males or immature individuals. Under these situations, they might be migrated to more suitablewaters such as the abundant grounds of Pacific saury in offshore areas. On the other hand, somemales and immature individuals is thought to be migrated to the coastal waters off Kushiro evenwhen the abundance of the prey is low, and take the other available prey species such as Krill andWalleye pollock.
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 as mentioned above, and suggested thatthose changes might be related to yearly change in the environmental factors such as theoceanographic conditions and distribution of prey species. Results of the survey also suggested thevariability in the possible effects of the whales for the local coastal fisheries. In conclusion, the 2005
survey off Kushiro was conducted successfully and we could obtain the valuable information for the
future ecosystem modeling and multi-species managements.
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 Japanese 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 Scientific8SC/58O10

Committee, 14pp.
International Whaling Commission. 2005. Report of the Scientific Committee. J. Cetacean Res.
Manage. 7 (suppl.):1-411.
International Whaling Commission. 2006. Report of the Scientific Committee. J. Cetacean Res.
Manage. 8 (suppl.):(in press).
Japan Fisheries Information Service Center, 2005. Information on fisheries and oceanographic
conditions around Japan. No.63-67 (in Japanese).
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.
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. Paper SC/57/O4 submitted to the 57th IWC
Scientific Committee, 37pp.
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.
Yoshida, H., Kato, H., Kishiro, T., Iwasaki, T., Miyashita, T., Saito, T., Tabata, Morita, Y., Sato, H.,
Okada, A., Tomizawa, Y., Saino, S., Kuroishi, H., Ebisui, T., Makai, K., Nishiwaki, S. and
Kawahara, S. 2006. Cruise report of the second phase of the Japanese whale research program
under special permit in the western North Pacific – Coastal component off Sanriku in 2005. Paper
SC/58/O9 submitted to the 58th IWC Scientific Committee, XXpp.

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Appendix 1
2005 coastal prey species survey of JARPN II off Kushiro
SHIGEYUKI KAWAHARA1, TOMOHIDE YAMAMOTO2, SAYAKA UMEKI2 AND HIROTO MURASE3
1

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

2

Nippon Kaiyo Co., Ltd., Tokyo Branch Office, 9-2 Sakae-cho, Kita-ku Tokyo, 101-0041, Japan

3

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

ABSTRACTA prey species survey was conducted in cooperation with the sampling survey by small-type whaling
catcher boats for minke whales off Kushiro, eastern Hokkaido, in September 2005 as a part of JARPN II
study. The objective of the prey species survey was to examine prey environment and prey preference ofminke whale off Kushiro during autumn. The distribution and abundance of the prey species were
investigated with the quantitative echosounder (ER60) and midwater trawling at predetermined stations on a
trawler-type research vessel, Kaiyo maru No. 7. Acoustic data were acquired by steaming at about 10 knots
during the daytime along the track lines with operating frequency at 38 and 120 kHz. Species and size
compositions of acoustical backscatterings were identified by targeting midwater trawl and IKMT. The
abundance of Japanese anchovy seems to be lower than previous surveys in 2002 and 2004. The catches ofPacific saury were limited due to the delay of the migration to eastern Hokkaido. Adult walleye pollock andcommon squid were caught near Kushiro Canyon. Krill swarms were not found on the continental shelf. The
results of the survey generally coincided with the information from the fisheries. In summary, the preyenvironment surrounding minke whale was not good in autumn 2005 off Kushiro and the environment
seems to change year by year.

INTRODUCTION
The overall goal 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 is put on feeding ecology and ecosystem studies,
involving studies of prey consumption by cetaceans, prey preferences (selection) of cetaceans andecosystem modelling. As it is difficult to cover the coastal area, especially in spring and autumn, by
the Nisshin Maru, the full-scale JARPN II has a new coastal component, that is, the sampling survey
for minke whale by small-type whaling catcher boats. In September 2005, the cooperative
whale/prey surveys were conducted in the coastal region off Kushiro, eastern Hokkaido, as in 200218

SC/58O10

and 2004. This document presents the preliminary results of the prey species survey. While a
dedicated sighting vessel, Kyoshin Maru No. 2, also conducted cooperative acoustic survey andoceanographic observations with CTD, the results are not included in the document.
MATERIALS AND METHOD
The prey species survey covered wider area off the eastern Hokkaido, east of Cape Erimo(143º15’E), west of 146º00’E and north of 41ºN to elucidate the distribution and abundance of main
prey species while the sampling survey of minke whale was conducted in the coastal waters within
the 30 nautical miles (max 50 nautical miles) from Kushiro (Fig. 1). As many gears were set near the
shore, the waters shallower than 50m were excluded in principle. The survey area was divided into
two parts; coastal and offshore parts. The coastal part was further divided into east, central and west
parts. Zigzag track lines were set to cover each part. The waypoints of planned track lines are shownin Table 1.
The prey species survey was conducted from September 11 to 28 2005. The distribution andabundance of the prey species were investigated with the quantitative echosounder (ER60),
midwater trawl and Isaacs-kidd Midwater Trawl (IKMT) on board a stern trawler-type research
vessel, Kaiyo maru No. 7 (499.0 GT) steaming at about 10 knots along the track lines. The survey
was conducted during the daytime from an hour after sunrise to an hour before sunset (generally
from 6:00 to 17:00 in local time). Acoustic data were acquired with Echoview Ver.3 (Sonar Data Co.,
Ltd.). Calibrations were carried out off Shiranuka near Kushiro (September 11 and 24 2005) using
the copper sphere technique. The mid-water trawl net used had a mouth opening of about 30x30m
and a 17.5mm liner cod end. The sampling depth and the height of the mouth of the net weremonitored with Scanmer and recorded with the small-type depth recorders (SBT). Towing speed of
the trawl net was 3-5 knots. In this study, all samples were collected during daylight period.
Two types of mid-water trawlings were made. Targeting trawlings were to identify the species andsize compositions of biological backscatterings detected by the echosounder. Another type of
trawlings was made at predetermined stations to estimate the distribution and abundance of
cephalopods and neustonic organisms that are difficult to detect with the echosounder. At
predetermined stations the midwater trawl net was towed in a stairs-like fashion at three depth layers(0-30m, 30-60m and 60-90m) shallower than 100 m (0-30m, 60-90m, and 120-150m in the case of150m). Towing duration was 30 minutes in total, 10 minutes for each layer. All samples wereidentified 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. Some frozen samples were taken for further analysis in the laboratory.
Also, IKMT was used for the biological backscatterings expected as micronekton and/or
19

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

zooplankton such as krills on the echosounder. Samples were preserved in 10 % formalin for species
identification at the laboratory. Oceanographic observation with CTD was made down to 500 m ornear the bottom at each sampling station just before or after the sampling operation and at stations
for CTD.
RESULTS AND DISCUSSION
Predetermined/targeting trawlings, IKMT and CTD observations were made 5 times, 27 times, 3times and 54 times during the survey, respectively (Fig. 2). The trawling operations and the catchesby species are shown in Table 2. The oceanographic conditions are described in Appendix 3 in thereport. 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 as follows.
While Japanese anchovy was found in the surface layer from the continental shelf to the open sea,
the abundance seems to be lower than previous surveys in 2002 and 2004 (Kawahara et al., 2003;
2005). It is known that the recruitment of 2004 year class of Japanese anchovy failed. Two modes at
10cm and 13cm in body length were observed in the size composition. Large catches of Pacificsaury were made at a few stations on the edge of the continental shelf in the east part of the survey
area and the catches consisted of large-sized fish above 30cm in knob length. The fishing grounds ofPacific saury were formed off southern Kuril Islands during the survey period. The landings also
consisted of large-sized fish. The southern migration of Pacific saury to the eastern Hokkaido wasdelayed due to an extrusion of the higher temperature water from the south. Yearlings of walleye
pollock (about 12cm in fork length) were distributed on the bottom, sometime to the mid-water layer,on the continental shelf, and adults with modes at 31 and 40cm were caught at depths around 200m
near Kushiro Canyon in the central part of the survey area. Also large common squid were caught at
depths around 200m in Kushiro Canyon (Table 3). Squid fishing season in 2005 seems to be good asmany jigging vessels were found widely along the edge of the continental shelf. Krill was distributed
from the edge of the continental shelf to the open sea. While swarms were found in the mid-layer on
the continental shelf in the previous surveys, the phenomenon was not observed in 2005 survey. In
summary, the prey environment surrounding minke whales was not good in autumn 2005 off
Kushiro and changes in distribution, abundance and size composition may occur year by year. The
results of the survey generally coincided with the information from the fisheries. The acoustic and
CTD data will be analyzed including data collected by Kyoshin-maru No. 2 and a comparison withdata from the whaling survey will be made to estimate the prey preference of minke whale.
ACKNOWLEDGEMENT
A special thank is given to Captain S. Tabata and crews of Kaiyo maru No. 7 for their dedication incollecting data.

20

SC/58O10REFERENCES
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.
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 oncommon minke whales off Kushiro, northeast Japan: the 2004 JARPN II survey (Part II) –Coastal component. SC/57/O4 submitted to the 57th IWC Scientific Committee Meeting, 37 pp.

21

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Table 1. Waypoints of planned track lines.
Area

WP
O-1
O-2
Offshore O-3
O-4
O-5
E-1
E-2
Coast E-3
East E-4
E-5
E-6
C-1
C-2
Coast
C-3
Central
C-4
C-5
W-1
W-2
Coast
W-3
West
W-4
W-5

Latitude410
42 16.441
041 59.141
042 29.343
3.0
42 22.8
42 59.7
42 12.1
42 56.2
42
7.7
42 53.842
4.0
42 44.6
41 47.7
41 47.7
42 18.5
41 26.6
41 55.041
0.0Longitude
146
0
145
30
145
0
144
30
144
0
146
0.1
145 28.5
145 45.5
145 15.2
145 15.8
145
0.2
145
0.1
144 30.5
144 45.3
143 57.4
144 12.8
144 12.8
143 29.6
143 59.0
143 19.9
143 19.9

Table 2. Trawl operations and the catches by species
Station Year Mon. Day
02
03
04
05
07
08
10
11
12
15
17
18
20
21
22
24
25
26
27
28
31
32
35
37
38
42
44
48
50
51
53
54

2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005
2005

9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9
9

Targeting/Predetermined
11 Prede.（Surface)
12 Prede.(100m)
12 Prede.（Surface)
12 Prede.（Surface)
13 Targeting(30-50m)
13 Prede.(100m)
14 Prede.(100m)
14 Prede.（Surface)
14 Prede.（Surface)
16 Prede.(100m)
17 Prede.(100m)
17 Prede.(100m)
18 Prede.(100m)
18 Prede.（Surface)
18 Prede.（Surface)
19 Prede.（Surface)
19 Prede.(100m)
19 Prede.（Surface)
20 Targeting(40-60m)
20 Prede.（Surface)
21 Prede.(100m)
21 Prede.（Surface)
21 Targeting(0-20m)
22 Targeting(0-20m)
22 Prede.（Surface)
23 Targeting(0-40m)
23 Prede.(150m)
23 Prede.(170m)
25 Prede.(90m)
25 Prede.（Surface)
27 Prede.(170m)
27 Prede.（Surface)Time
Position
Surf. Catch Japan. Walleye Pacific Comm.
cast Lift Latitude Longitude Temp. Total(kg) anchovy pollock saury squid
16;53 17:39 42 36.8 143 59.4 16.0
0.4
0.1
0.3
8:32 9:35 42 17.2 144 05.1 15.0
0.0
12:31 13:22 41 55.7 144 11.0 16.8
0.0
0.0
0.0
16:20 17:00 41 56.8 144 00.7 16.6
0.1
0.1
11:00 11:57 42 15.3 143 29.9 18.3
4.7
0.1
4.6
14:43 15:39 41 54.7 143 43.4 16.9
0.2
0.2
7:39 8:23 42 34.6 144 09.2 15.5
16.7
16.6
0.1
10:43 11:26 42 23.0 144 22.5 17.5
25.2
25.2
14:47 15:29 42 05.9 144 42.1 18.7
0.0
0.0
11:25 12:21 41 25.2 145 10.3 18.6
0.0
7:06 8:02 42 17.2 145 30.4 18.8
0.0
0.0
12:34 13:25 41 36.1 145 46.0 19.8
0.0
0.0
6:27 7:38 42 29.9 146 00.3 18.6
0.0
0.0
9:43 10:34 42 41.9 145 48.7 15.1
0.0
12:29 13:23 42 51.9 145 39.4 14.8
201.6 201.3
0.3
7:02 7:54 42 55.3 145 31.7 14.9
98.7
98.7
10:12 11:07 42 41.9 145 37.6 15.3
2.6
2.6
15:06 15:49 42 30.3 145 40.6 18.5
0.0
0.0
8:35 9:15 42 58.1 145 13.7 15.6
0.0
0.0
0.0
10:22 11:09 42 54.5 145 15.4 15.6
0.0
0.0
0.0
8:18 9:14 42 30.4 145 09.3 16.1
0.0
0.0
10:52 11:43 42 40.3 145 05.0 14.3
8.0
0.4
7.4
0.2
14:57 15:35 42 51.8 144 52.8 16.3
174.1 174.1
6:44 7:24 42 06.6 144 44.2 18.1
0.0
10:52 11:43 42 39.0 144 34.4 17.8
0.2
0.0
0.2
6:20 6:53 42 50.8 144 06.1 16.5
83.6
83.6
12:55 14:13 42 44.6 144 09.2 15.6
846.6
587.0
259.6
14:03 15:24 42 44.9 144 25.9 15.0
1318.61317.61.0
10:00 10:58 41 26.5 143 58.4 19.0
0.0
13:59 14:42 41 37.4 143 33.4 18.2
0.0
7:45 8:50 41 37.3 143 19.6 17.2
0.0
12:23 13:04 41 17.4 143 33.2 17.6
0.0

22

SC/58O10

23

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Appendix 2
Cruise report of the dedicated sighting survey in 2005 JARPNII
coastal survey off Kushiro, northeast Japan.
SHIGETOSHI NISHIWAKI1, HIROSHI KIWADA1, MASAHIKO NAGAMINE2, SAEKO KUMAGAI1,
KOJI TAKESHITA2, 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

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 2005, as a part of coastal component of 2005 JARPN II full scale
study. The primary objective of the sighting survey was abundance estimation ofbaleen whale in the survey area. The research vessel Kyoshin-Maru No.2 was dedicatedto the sighting survey. Total searching distances were 827.1 n.miles. A total of 63
individuals of 44 schools primary sightings were made. They included 21 common
minke and 29 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
2005 as a part of coastal component of 2005 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. Near shore area of the survey block where thewater 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 coastaland offshore area was set on the line parallel to the coastline and the distance between the boundaryand coastline was 60 n.miles. The survey was conducted from 2 to 19 September 2005. Details ofitinerary were shown in Table 1. Kyoshin-maru No.2 (KS2, 372GT) engaged in the cetacean sighting24

SC/58O10

survey. Sighting survey procedures were same as offshore component of 2005 JARPN II, but thesurvey mode was only restricted to passing mode (NSP). Natural marking record and biopsy
sampling experiments were attempted at grey, blue, humpback and right whales. These experiments
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 827.1 n.miles. A
total of 63 individuals of 44 schools were sighted in primary sightings. They included 21 common
minke and 29 sperm whales. Details of sightings were listed on Table 2. Natural marking record andbiopsy sampling experiments were not made. No large baleen whale feeding behavior was observed.
ACKNOWLEDGEMENT
Special thanks are given to the crews for their dedication in collecting data. The authors would liketo thank Dr. Hiroshi Hatanaka (The Institute of Cetacean Research).
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.
Table 1. Details of survey itinerary.
Date

Event

9/01

Depart from Kushiro Port, Hokkaido, Japan

9/02

Start sighting survey

9/19

End sighting survey

9/21

Arrive at Sendai-Shiogama Port, Miyagi, Japan

Table 2. Summary of cetacean sightings.
Primary
Species

Sch.

Ind.

Common minke whale

20

21

Sperm whale

1129

Like common minke whale

3

3

Unidentified Large cetaceans

11Unidentified cetaceans

9

9

Total

44

63

Secondary

25

Sch.

Ind.

1

1

1

1

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Fig 1. Searching effort by dedicated survey vessel “Kyoshin-Maru No.2”, in the 2005 JARPN II
coastal survey.

Fig 2. Sighting positions of Common Minke whales (○), and Sperm whales (▽) bydedicated survey vessel “Kyoshin-Maru No.2” in the 2005 JARPN II coastal survey.
26

SC/58O10

Appendix 3
Oceanographic conditions in the JARPN II survey area off Kushiro,
northeast Japan, in September 2005
DENZO INAGAKE1, SHIGEYUKI KAWAHARA1 AND KOJI MATUOKA2
Contact e-mail: ina@affrc.go.jp
1
National Research Institute of Far Seas Fisheries, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa
236-8648, Japan
2

The Institute of Cetacean Research, Toyomi-cho 4-5, Chuo-ku, Tokyo 104-0055, Japan
ABSTRACTA prey species survey was conducted in cooperation with the sampling survey by small-type whaling
catcher boats for minke whales off Kushiro in September 2005 as a part of JARPN II study. During thesurvey, Oceanographic observation with CTD was made 54 times to make clear the oceanic environment in
the survey area. The cold Oyashio water was observed at depths deeper than 50m in almost whole survey
area. The warm water over 15°C spread at the surface layer above the seasonal thermocline which lies
around the depth of 20-30 m. The western coastal area was affected by Tsugaru warm current. A warm-corering was placed around 42 ﾟ N, 147 ﾟ E.

INTRODUCTION
The oceanographic condition off the northeast Japan is the most complicated area in the world. In
this area, there are a lot of fronts and water masses. The Kuroshio, which is one of the strongest
west-boundary currents of subtropical gyre, flows northward from the offshore area of Philippine to
the waters off Japan with warm high-salinity water. The Oyashio flows southward along the Kuril
Islands to the east coast of Hokkaido and Tohoku with cold low-salinity water. The Kuroshio and the
Oyashio flows eastward from the Japan coastal area, and the area between the Kuroshio and Oyashio
east of Japan was usually called the Kuroshio-Oyashio Inter-frontal Zone or perturbed area. The
warm-core ring, which is cut off from the Kuroshio extension, usually distribute in the Inter-frontal
Zone and move northeastward to our survey area, south of Kushiro. Each water mass has its own
ecosystem, like a Kuroshio ecosystem, an Oyashio 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 off northeast Japan.
A prey species survey was conducted in cooperation with the sampling survey by small-type whaling
catcher boats for minke whales off Kushiro in September 2005 as a part of JARPN II study. In thispaper, we analyzed the CTD data to make clear the oceanic environment in the survey area as 2004
survey (Inagake et al., 2005).
27

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

DATA AND METHODS
Hydrographic observations with a conductivity-temperature-depth profiler (CTD; SBE 19plus) werecarried out 54 times from 11 to 27 September 2005 in the survey area south of Kushiro, northeast
Japan (Fig. 1). The oceanographic conditions in September 2005 were analyzed by Tohoku National
Fisheries Research Institute (TNFRI), which used quasi-real-time data from several cooperative
organs and prefectures; those were Fisheries Research Agency, Meteorological Agency,
Hydrographic Department and Fisheries Experiment Stations, etc. TNFRI published temperaturemaps and schematic hydrographic maps using World Wide Web (http://www.myg.affrc.go.jp/
kaiyo/temp/temp.html). Oceanic fronts and water masses are usually detected by subsurface
temperature map (see Table 1), because they are obscure in sea surface temperature distributions
from summer to fall seasons and the 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 the Oyashio water and the cold water. Light blue dots show thedata in the cold water defined by 100 m temperature which is over 5 degree C and less than 10
degree C. Blue dots show the data in the Oyashio water defined by 100 m temperature which is lessthan 5 degree C with cold low-salinity water (lower part of Fig. 2) with warm surface water (leftupper part of Fig. 2). Right part of light blue dots in Fig. 2 show warm high-salinity water affectedby Kuroshio water, and other light blue dots are affected by the Oyashio water rather than the
Kuroshio water.
Figure 3 shows the schematic hydrographic map in September 2005, presented by TNFRI. It isappear that the Oyashio water was dominant in the survey area, south of Hokkaido. The southern
limit of the first Oyashio Intrusion was located around 39 ﾟ 30’N on 145 ﾟ E line, which were more
southern position from monthly mean location in September (40 ﾟ 20’N). The southern limit of thesecond Oyashio Intrusion was around 39 ﾟ 30’N, 147 ﾟ 30’E which was a little southern position froma monthly mean position in September. The Tsugaru warm water spread eastward to around 143 ﾟ E.
The warm water spread from the Kuroshio and the Tsugaru warm water appear in the middle ofsurvey area. The Kuroshio warm-core ring is nearby eastern part of the survey area around 42 ﾟ N,
147 ﾟ E.
Figure 4 shows the 100 m and 200 m depth temperature maps observed by Kaiyo maru No. 7. The
Oyashio water colder than 5 degree C at the depth of 100 m was spreading through the middle partof the survey area. The cold water, which is over 5 degree C and less than 10 degree C at 100 m
depth, was observed western part and northeastern part of this area. At 200 m depth, the cold waterless than 4 degree C is dominant in this area.
28

SC/58O10

Figure 5 shows the vertical temperature sections along 42ﾟN, 42ﾟ30’N and 43ﾟN. The cold Oyashio
water was observed in the almost whole of the survey area (deeper than 50 m depth). The warm
water over 15 degree C spread at the surface layer above the seasonal thermocline which lies aroundthe depth of 20-30 m. A thickness of the surface warm water is deepened in the western part of 43ﾟN
section, which is on the shelf along Hokkaido coast. It is suggested that the warm water affected by
the Tsugaru warm water spreads northeastward along the coast on the shelf.
All of these figure show almost offshore stations are distributed in the Oyashio area and cold area,
but western part of inshore stations was in warmer area affected by Tsugaru warm current.
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.
Inagake, D., Watanabe, H., Yonezaki, S., and Kawahara, S. 2005. Oceanographic conditions in the
Kuroshio-Oyashio Inter-frontal zone in September 2004. Appendix 3, pp 31-37. 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
Scientific Committee Meeting, 37 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).

29

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Table 1.

Extraction method from temperature map to determine the position of eachwater 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

Area with 5°C<T<10°C at 100m

Warm water

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

Subarctic Boundary

Salinity front defined by 34.0psu

Subarctic Front

Temperature front defined by 4°C

Kaiyo maru No.7 11-27 Sept. 2005

Fig. 1.

Station map observed by Kaiyo maru No. 7 in 11 to 27 September 2005.

Light blue stars

and blue circles denote CTD stations in the cold area (100 m temperature was over 5°C
and less than 10°C) and the Oyashio area (100 m temperature was less than 5°C),
respectively.

30

SC/58O10
Kaiyo maru No.7 11-27 Sept. 2005

Fig. 2.

Temperature-Salinity diagrams observed by Kaiyo maru No. 7 in 11 to 27 September 2005.
Each thin line in this figure denotes a density line of sigma-t.

Tsugaru
Warm
Water

WarmcoreRing

1st Oyashio 2nd Oyashio
Intrusion
Intrusion
Warm
Water

Kuroshio
Area

Fig. 3.

Schematic hydrographic map off the northeast Japan, northwestern Pacific, in September
2005 (presented by TNFRI).

Blue, green, yellow and red area show distributions of the

Oyashio, the cold water, the warm water spread from the Kuroshio Extension and theKuroshio Extension, respectively.

Light blue star and blue circle denote CTD stations

observed by Kaiyo maru No. 7 in the cold area and the Oyashio area, respectively.

31

Kishiro, et al.: Report of the JARPN II in 2005- Coastal component off Kushiro

Kaiyo maru No.7

Fig.4.

Kaiyo maru No.7

100 m (left panel) and 200 m (right panel) temperature map observed by Kaiyo maru No. 7
in 11 to 27 September 2005.

Fig. 5.

Vertical sections of temperature along 42 ﾟ N (left panel), 42 ﾟ 30’N (middle panel) and 43 ﾟ
N (right panel) by Kaiyo maru No. 7 in 11 to 27 September 2005

32