SC/56/O16

Preliminary analyses of interaction between common minke
whales and fisheries off Kushiro region
TSUTOMU TAMURA1), KENJI KONISHI1), TAKASHI HAKAMADA1), KOJI MATSUOKA1), HIROTO MURASE1), TOMIOMIYASHITA2), TOSHIYA KISHIRO2), HIROSHI OHIZUMI3), HIDEHIRO KATO2), SHIGEYUKI KAWAHARA2) AND YOSHIHIROFUJISE1)
1) The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan,
2) National Research Institute of Far Seas Fisheries, 5-7-1, Shizuoka, 424-8633, Japan.
3) Tokai university, 3-20-1, Shimizuorido, Shizuoka, Shizuoka 424-8633, Japan
Contact e-mail: tamura@cetacean.jp

ABSTRACTThe stomach contents of common minke whale Balaenoptera acutorostrata sampled off Kushiro region from June to
October in a part of the 1996 JARPN–2002 JARPN II, were analyzed. The dominant prey species consisted of one krill(Euphausia pacifica), three fish (Japanese anchovy Engraulis japonicus, Pacific saury Cololabis saira and walleye
pollock Theragra chalcogramma) and one squid (Japanese common squid Todarodes pacificus). All these prey species
are targeted by local fisheries. The annual prey consumption of Japanese anchovy, Pacific saury, walleye pollock andJapanese common squid by common minke whales were estimated as 10,000–15,000 tons, 3,500–5,000 tons, 6,000–
10,000 tons and 1,600–2,500 tons, respectively. Based on these results, there is a possibility of direct competition
between common minke whale and the fisheries for these resources in this region. To evaluate this competition, more
information of accurate abundance in prey species and common minke whales, and resident period of common minke
whale off Kushiro region are needed.
KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; FISHERIES INTERACTION, SCIENTIFICPERMIT

INTRODUCTION
The common minke whale Balaenoptera acutorostrata is widely distributed in the world. In the western North Pacifictwo stocks have been recognized: one in the Sea of Japan - Yellow Sea - East China Sea (J stock) and the another in the
Sea of Okhotsk – West Pacific (O stock) (IWC, 1983). The abundance of common minke whales was estimated to be
19,209 animals with 95 % confidence interval (10,069 – 36,645) in the Sea of Okhotsk and 5,841 animals with 95 %confidence interval (2,835 – 12,032) in the Northwest Pacific during August and September in 1989 and 1990 (IWC,1992). In the western North Pacific, common minke whales are opportunistic feeders consuming a broad of prey withflexible feeding habits. According to previous reports, they consume several prey species such as pelagic schooling fishand zooplankton (Kasamatsu and Hata, 1985; Kasamatsu and Tanaka, 1992; Tamura et al., 1998).
The Japanese Whale Research Program under Special Permit in the Western North Pacific (JARPN) and JARPN II
feasibility study showed that they fed on various prey species such as Japanese anchovy Engraulis japonicus, Pacificsaury Cololabis saira, walleye pollock Theragra chalcogramma and Japanese common squid Todarodes pacificus.
Furthermore, most of common minke whales pursued single prey species aggregations and the main prey specieschanged seasonally and geographically. For example, they feed on Japanese anchovy in May/June and Pacific saury in
July/August (Tamura and Fujise, 2000a, 2002a). The estimated prey consumption by common minke whales wascomparable to that of the commercial fisheries (Tamura and Fujise, 2000b, 2002b). It was thought that there was thecompetition between the common minke whales and fisheries in the coastal area.
However, our interests of coastal matter, the Nisshin-Maru and large sighting/sampling vessels can not be operated in
the near shore area because of various restrictions and obstacles. Furthermore, these vessels can not join survey fromlate autumn to early spring for operational reason.
In order to cover the geographical and seasonal gaps of JARPN and JARPN II feasibility study, sampling of common
minke whales in the coastal area using small type whaling catcher boats was planed in 2002 (Government of Japan,
1

2002). These coastal surveys were conducted off Kushiro in 2002, off Sanriku in 2003.The detail of these surveys werereported in Kishiro et al. (2003) and Yoshida et al (2004).
In previous report, krill, squid, Japanese sardine Sardinops melanostictus, Japanese anchovy, Chub mackerel Scomber
japonicus, walleye pollock Theragra chalcogramma, cod, sand lance Ammodytes personatus, Pacific saury and so on
were prey species of minke whales off the Pacific coast of Hokkaido (a part of sub-area 7W) from April to October(Kasamatsu and Tanaka, 1992; Tamura and Fujise, 2000a, 2002a). Kishiro et al (2003) reported that the dominant preyspecies of common minke whales sampled off Kushiro region were krill, Japanese anchovy, Pacific saury, walleye
pollock and Japanese common squid in the coastal area of Kushiro.
In this document, the abundance of common minke whales and the consumption of targeted fisheries species consumed
by common minke whales off Kushiro region were calculated using some assumption. Then, the interaction was
evaluated by means of comparison between the prey consumption by common minke whales and fisheries catches.

MATERIALS AND METHODS
The abundance of common minke whales off Kushiro region
The study area was set off Kushiro region, which covered north of 41N and longitude from 143.15E (Erimo cape) to146E. The area covered 7,307 nml2. Three data sets were used for estimates of common minke whale distributed off
Kushiro region (Fig. 1).
1.

Data were obtained from sighting survey conducted by Syunyo Maru in September in 1991 and 1992. g(0) assumed
0.787 (Data for calculating g(0) were obtained from sighting survey in Okhotsk area in 1999 and 2000). The
estimated abundance of common minke whales off Kushiro region was 821 individuals (95% confidence interval:
284 – 2,369 individuals).

2.

Data were obtained from sighting survey conducted by Kyoshin Maru No.2 in July in 1999. g(0) assumed 0.787(Data for calculating g(0) were obtained from sighting survey in Okhotsk area in 1999 and 2000). The estimatedabundance of common minke whales off Kushiro region was 1,194 individuals (95% confidence interval: 443 –3,215 individuals).

3.

Data were obtained from sighting survey conducted by Kyoshin Maru No.2 in September in 2002. g(0) assumed
0.787 (Data for calculating g(0) were obtained from sighting survey in Okhotsk area in 1999 and 2000). The
estimated abundance of common minke whales off Kushiro region was 803 individuals (95% confidence interval:
451 – 1,428 individuals).

Sighting and sampling of common minke whales
1. JARPN 1996, 1999, JARPN II 2000, 2001 and offshore component of JARPN II in 2002
Sighting and sampling methods of common minke whales and research summary were described in Fujise et al. (1997,
2001, 2002, 2003) and Fujise (2000).
2.

Coastal component of JARPN II in 2002

Sighting and sampling methods of common minke whales and research summary were described in Kishiro et al.
(2003). Three small-type whaling catcher boat, Taisho Maru No. 28, Sumitomo Maru No. 31 and Katsu Maru No.7
were used. All common minke whales sighted excluding the cow-calf pair were targeted for sampling. When a school
size was more than one animal, sampling target was selected randomly from the school. After the target was sampled byharpoon, she moved to the Kushiro port as soon as possible, to land research station.
The sample size of common minke whales, which were used for stomach contents analyses, was listed in Table 1.
Sampling of the stomach contents
Biological research such as measurement of body proportion were conducted for all common minke whales sampled.
The stomach contents were all removed. After that the stomach contents were all removed. The contents from eachstomach were weighed to the nearest 0.1 kg, and sub-sample were removed from all individuals and frozen for later
examination. The contents were first classified to major prey groups, such as euphausiids, copepods, fish and others.
The freshness of stomach contents was categorized into four classes (1 = fresh, 2 = lightly digested, 3 = moderately
digested, 4 = heavily digested).
The sub-samples were identified to the lowest taxonomic level as much as possible. When undigested fishes were found,standard lengths and weight were measured to the nearest 1 mm and 1 g, respectively. When fishes occurred in the subsamples, the total number of each prey species was estimated by adding the number of undigested specimens and thenumber of intact skulls. The total weight of each prey species was estimated by using the average weight of fresh2

specimens. The total number and weight of each prey species were estimated by using the results from the sub-samples.
Then, the relative prey importance by weight of each prey species (RW) was calculated as follows:
RW = (Wi / Wall) × 100
Wi = the weight of contents containing prey group i
Wall = the total weight of contents analyzed.
The consumption by common minke whales
The seasonal diet composition (RW) of common minke whales was listed in Table 2. The maturity composition ofcommon minke whales was listed in Table 3.
The daily prey consumptions by both immature and mature common minke whales were calculated with theassumptions below.
a. Mean body weight（Tamura and Fujise, 2002b）: Immature male:

2,500 kg

Immature female: 2,600 kg
Mature male:

4,800 kg

Mature female:

5,900 kg

These weights were obtained from JARPN and JARPNII survey data.
b. The residence time of the common minke whale off Kushiro region: 180 days (from May to October)
Off Kushiro region, common minke whales mainly distribute from May to October (Hatanaka and Miyashita, 1997).
And past commercial whaling season off Kushiro region was from May to October. Between 1994 and 1999 JARPN
surveys, common minke whales distribute off Kushiro region in June and August (Matsuoka et al, 2000). Therefore,
residence time of the common minke whale off Kushiro region was assumed to be 180 days.
c. Field metabolism

Immature male or female: 1.58×80×body weight（kg）KJ / day (Markussen et al., 1992)
Mature male or female:

1.25×80×body weight（kg）KJ / day (Nordoy et al, 1995)

The average field metabolism used in these calculations was obtained from Blix and Folkow (1995). The value of 80
kJ/kg per day is based on indirect determination of oxygen consumption from studies of the respiratory rates.
d. Average caloric value of prey species: 6,000 KJ / kg
Stomach content analyses show much variation in the diet of common minke whales in the western North Pacific(Kasamatsu and Tanaka, 1992; Tamura et al., 1998, Tamura and Fujise, 2000a, 2002a). In the North Atlantic, theenergy contents of the prey species varies from 3,720 kJ / kg when feeding on Parathemisto spp. to as high as
12,500 kJ / kg when feeding on herring (Markussen et al., 1992). In this study, the mean caloric value of krill,
Japanese anchovy, Pacific saury, walleye pollock and Japanese common squid Todarodes pacificus were calculatedusing bomb caloric meter. The mean caloric value of krill, Japanese anchovy, Pacific saury, walleye pollock andJapanese common squid were calculated to be 3,600 kJ / kg, 6,400 kJ / kg, 13,000 kJ / kg, 6,200 kJ / kg and 6,600 kJ/ kg, respectively (Tamura and Fujise, 2002b). Total prey species were assumed to be 6,000 kJ / kg by average ofabove values.
e. Assimilation efficiency:

80 ％The assimilation efficiency of the common minke whales is assumed to be 80 % (Markussen et al., 1992).
f. Reproduction cost:

20kg / day

The total reproductive cost for the female common minke whale was re-calculated to be 1.9×107 kJ (Lockyer,1981), assuming a length at birth fetus of 280 kg (Christensen, 1981). The pregnancy rate is 95 % for mature. Allenergy related to reproduction costs as obtained during the residence (feeding) time in the western North Pacific(180 days) were assumed.
The each calculated prey consumption by common minke whales from May to October is shown in Table 5.
The fisheries catches of Pacific saury, walleye pollock and Japanese common squid off Kushiro region from May
to October
Fisheries Catch data (2002) of several main ports off eastern Hokkaido from May to October ware provided from the
Fishing Information Service Centre in Japan (Table 6). The catches in 2002 of Pacific saury, walleye pollock andJapanese common squid were 105,000 tons, 23,000 tons and 1,000 tons, respectively.

3

The biomass of prey species off Kushiro region
The results of the biomass of each prey species off Kushiro region from prey survey of JARPN II in 2000 and 2001 areshown in Table 7 (Murase et al., 2002).
Interaction index between common minke whales and fisheries catch
The interaction was evaluated by means of comparison between the prey consumption by common minke whales andfisheries catches as follows:
I index = Call / F ×100
I index = Interaction index between common minke whales and fisheries
Call = Consumption by common minke whales (tons)
F = Fisheries catch (tons)

RESULTS
The dominant prey species consisting of 1 krill (Euphausia pacifica), 3 fish (Japanese anchovy, Pacific saury, andwalleye pollock) and 1 squid (Japanese common squid) were identified in common minke whales caught off Kushiro
region based on from 1996 JARPN to 2002 JARPNII (Table 2). In early season (from may to June), Japanese anchovy
and walleye pollock were dominant prey species and composed 58.3 % and 35.2 % in wet weight (%), respectively. In
late season (from August to September), walleye pollock, Pacific saury, krill and Japanese anchovy were dominant preyspecies and composed of 26.1 %, 24.6 %, 19.9 % and 18.3 % in wet weight (%), respectively (Table 3).
The estimated daily prey consumption weights during feeding period off Kushiro region were 120 kg and 125 kg for
immature male and female, and 183 kg and 244 kg for mature male and female, respectively.
The total prey consumption by common minke whales off Kushiro region from May to October was estimated to beapproximately 24,000 – 35,000 tons. The prey consumption of economically important Pacific saury, walleye pollock
and Japanese common squid by common minke whales were estimated as 3,000 – 5,000 tons, 6,000 – 9,000 tons and1,500 – 2,000 tons, respectively (Table 5A, 5B, 5C, 5D, 5E and 5F).
The body length of Japanese anchovy (A), Pacific saury (B), walleye pollock (C) and Japanese common squid (D)ingested ranged from 100 to 156 mm, 141 to 342 mm, 177 to 530 mm, and 127 to 296 mm, respectively (Fig. 2).
The I index were 2.9 – 4.8 in Pacific saury, 26 – 39 in walleye pollock and 100< in Japanese common squid,
respectively. Sighting positions of common mink whales were overlapped to fisheries ground of Pacific saury (Fig. 3).
The biomass of Japanese anchovy and walleye pollock estimated by echo-sounder and trawling results were 150,000
tons (June in 2001) and 4,000 (June in 2001) – 27,000 tons (August in 2000), respectively (Table 7).

DISCUSSION
The present study indicates that there is some impact of predation by common minke whale on some fish resources off
Kushiro region.
Kasamatsu and Tanaka (1992) analysed the yearly change of prey species of common minke whale off Kushiro region
during 1948 to 1987. Commercial whaling was made from April to October with peaks from July to September. After
1982, two peaks were observed in July and September. The dominant prey species were krill, Japanese sand lance, chubmackerel, iwashi (Japanese sardine and/or Japanese anchovy), walleye pollock, pacific saury and Japanese common
squid. They pointed out that the yearly change of Japanese sardine in the stomach contents were similar to the annual
trend of abundance of Japanese sardine in this area. In the results of JARPN and JARPN II, the dominant prey speciesof common minke whales sampled off Kushiro region from June to October were krill, Japanese anchovy, Pacific saury,walleye pollock and Japanese common squid. This result was similar to the previous report.
The maximum stomach contents weight was 154.3 kg (2.6 % of body weight). Our daily estimated prey consumption
was from 120 kg to 244 kg (from 3.8 % to 4.8 % of body weight). Common minke whale should take on prey at several
times due to meet a demand for their energy requirement in a day. Based on diurnal change in feeding activity ofcommon minke whale in the western North Pacific, Tamura and Fujise (2000c) pointed out that common minke whales
feed on prey at several time throughout the day at the surface. Our results supported their consideration.
4

The seasonal consumption of 803-1,194 common minke whales distributed off Kushiro during May and October (180days) was approximately 24,000 – 35,000 tons. The prey consumption of economically important Pacific saury, walleye
pollock and Japanese common squid by common minke whales were calculated as 3,000 – 5,000 tons, 6,000 – 9,000
tons and 1,500 – 2,000 tons, respectively.
Based on results of the Pacific saury consumption by common minke whales and the degree of overlap between
fisheries ground of Pacific saury and sighting position of common minke whales, it is conceivable that the possibility
with direct competition between common minke whale and Pacific saury fisheries occurs. The fisheries season ofPacific saury is from August to October, and common minke whales also feed on Pacific saury in the same season. The
catch quota and season of Pacific saury off the Kushiro region is regulated by the fisheries conference in order toprotect the resources of Pacific saury and price control, however common minke whales feed on Pacific saury without
restriction. Therefore, consumption by common minke whales should be taken into account for fishery management ofPacific saury off Kushiro region.
The I index shows the possibility of direct competition between common minke whale and some fisheries. The prey
consumption of walleye pollock was amount to one-third of their estimated biomass off Kushiro region.
Furthermore, some fishermen indicate the fishing operation have interfered by common minke whales. Some minke
whales attack and feed on the school of Pacific saury when fishermen attracted fishes around boat, causing dispersion of
the schools of Pacific saury.
This preliminary analysis was based on the result of some part of JARPN and JARPN II between 1996 and 2002.
Especially, the research of coastal area was only once in 2002.
To evaluate the competition between common minke whale and some fisheries, more information of accurate
abundance in prey species and common minke whales, and the accurate resident period of common minke whale aroundthe Kushiro region are needed. It needs the long-term monitoring research in this area in future.

ACKNOWLEDGEMENTS
We would like to thank all captains, crews and researchers, who were involved in offshore component of JARPN II
between 1996 and 2003 and in coastal component of JARPN II surveys in 2002. Our sincere thank to Dr. H. Hatanaka
and Dr. Luis A. Pastene of the Institute of Cetacean Research (ICR) for their valuable suggestions and useful commentson this paper.

REFERENCES
Blix, A. S. and Folkow, L. P. 1995. Daily energy expenditure in free living minke whales. Acta Physiol. Scand., 153:616.
Christensen, I. 1981. Age, determination of minke whale, Balaenoptera acutorostrata, from laminated structures in the
tympanic bullae. Rep. int. Whal. Commn. 31:245-53.
Fujise, Y., Shimada, H., Zenitani, R., Goto, M., Tamura, T., Lindstrom, U., Uchida, A., Yoshida, H., Shimamoto, K.,
Yuzu, S., Kasai, H., Kinoshita, T., Iwata, T. and Toyama, D. 1997. Cruise report of the Japanese Whale Research
Program under a Special Permit in the North Pacific (JARPN) in 1996 with some preliminary analysis of datacollected during the 1994 – 1996 JARPN surveys. Paper SC/49/NP8 presented to the IWC Scientific Committee,
September 1997 (unpublished). 38pp.
Fujise, Y. 2000. Outline of the research activities under the Japanese Whale Research Program under a Special Permit
in the North Pacific (JARPN) from 1994 to 1999. Paper SC/F2KJ8 presented to the JARPN review meeting, February
2000 (unpublished). 30pp.
Fujise, Y., Zenitani, R., Tamura, T., Bando, T., Ohtani, S., Takeda, S., Kitajima, A., Kimura, T., Masaki, T. andTohyama, D. 2000. Cruise report of the Japanese whale research program under special permit in the North Pacific(JARPN) in 1999. Paper SC/F2K/J9 presented to the JARPN review meeting, February 2000 (unpublished). 32pp.
Fujise, Y., Pastene, L.A, Tamura, T., Bando, T., Murase, H., Kawahara, S., Watanabe, H., Ohizumi, H., Mogoe, T.,
Kiwada, H., Nemoto, K. and Narita, H. 2001. Progress Report of the Feasibility study of the Japanese whale research
program under special permit in the western North Pacific-Phase II (JARPN II) in 2000. Paper SC/53/O10 presented
to the IWC Scientific Committee, July 2001 (unpublished). 77pp.

5

Fujise, Y., Tamura, T., Bando, T., Hikaru Watanabe, Hiroshi Kiwada, 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 Japanesewhale research program under special permit in the western North Pacific – Phase II (JARPNII) in 2001. Paper
SC/54/O16 presented to the IWC Scientific Committee, May 2002 (unpublished). 51pp.
Fujise, Y., Tamura, T., Bando, T, Yasunaga, G., Konishi, K., Murase, H., Yoshida, T., Itoh, S., Ogawa, R., Oka, T.,
Sasaki, T., Fukutome, K., Isoda, T., Birukawa, N., Horii, N., Zharikov, K.A., Park, K.J., Toyama, D and Kawahara, S.
2003. Cruise report of the Japanese Whale Research Program under a Special Permit in the North Pacific –Phase II(JARPN II) in 2002 (part I) offshore component-. Paper SC/55/O7 presented to the IWC Scientific Committee, June
2003 (unpublished). 41pp.
Government of Japan, 2002. Research Plan for Cetacean Studies in the Western North Pacific under Special Permit(JARPN II). Paper SC/54/O2 presented to the IWC Scientific Committee, May 2002 (unpublished). 115pp.
Hatanaka, H. and Miyashita, T. 1997. On the feeding migration of the Okhotsk Sea – West Pacific stock of minke
whales, estimates based on length composition data. Rep. Int. Whal. Commn 47:557-67.
International Whaling Commission. 1983. Report of the Sub-Committee on minke whales. Rep. int. Whal. Commn.
33:91-122.
International Whaling Commission. 1992. Report of the Sub-Committee on North Pacific minke whale. Rep. int. Whal.
Commn. 42:156-77.
Kasamatsu, F and Hata, T. 1985. Notes on minke whales in the Okhotsk Sea -West Pacific area. Rep. int. Whal. Commn.
35:299-304.
Kasamatsu, F. and Tanaka, S. 1992. Annual changes in prey species of minke whales taken off Japan 1948-87. Nippon
Suisan Gakkaishi. 58:637-51.
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 the 2002 JARPN II survey inthe 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, 26pp.
Lockyer, C. 1981. Estimation of the energy costs of growth, maintenance and reproduction in the female minke whale,(Balaenoptera acutorostrata), from the southern hemisphere. Rep. int. Whal. Commn 31:337-43.
Markussen, N. H., Ryg, M. and Lydersen, C. 1992. Food consumption of the NE Atlantic minke whale (Balaenoptera
acutorostrata) population estimated with a simulation model. ICES J. mar. Sci. 49:317-23.
Matsuoka, K., Hakamada, T., Fujise, Y. and Miyashita, T. 2000. Distribution pattern of minke whales based on sighting
data during 1994-1999 JARPN surveys. Paper SC/F2K/J16 presented to the IWC Scientific Committee Workshop to
Review the Japanese Whale Research Programme under Special Permit for North Pacific Minke Whales (JARPN),Tokyo, 7-10 February 2000 (unpublished). 17pp.
Murase, H., Tamura, T., Kiwada, H., Fujise, Y., Watanabe, H., Ohizumi, H. and Kawahara, S. Preliminary estimation of
prey preference of minke whale and Bryde’s whales based on JARPN II. Appendux.5. pp 97-117. In: Government ofJapan (Fujise, Y., Kawahara, S., Pastene, L.A. and Hatanaka, H. eds.), Report of 2000 and 2001 feasibility study of theJapanese Whale Research Program under Special Permit in the western North Pacific-Phase II (JARPN II). Paper
SC/54/O17 submitted to the 54th IWC Scientific Committee Meeting
Nordøy, E.S., Folkow, L.P., Mårtensson, P.E. and Blix, A.S. 1995. Food requirements of Northeast Atlantic minke
whales. pp. 307-17. In: A.S. Blix, L.Walløe and Ø. Ulltang (eds.) Whales, seals, fish and man. Elsevier.
[Developments in Marine Biology] 4:720pp.
Tamura, T., Fujise, Y. and Shimazaki, K. 1998. Diet of minke whales Balaenoptera acutorostrata in the Northwesternpart of the North Pacific in summer, 1994 and 1995. Fisheries Science 64(1): 71-6.
Tamura, T. and Fujise, Y. 2000a. Geographical and seasonal changes of prey species in the western North pacific minke
whale. Paper SC/F2K/J22 presented to the JARPN review meeting, February 2000 (unpublished). 26pp.
Tamura, T. and Fujise, Y. 2000b. Daily and seasonal food consumption by the western North Pacific minke whale
Paper SC/F2KJ24 presented to the JARPN review meeting, February 2000 (unpublished). 18pp.
Tamura, T. and Fujise, Y. 2002a. Food habit of common minke whales based on JARPN II. Apendix 4, pp 47-63. In:
Government of Japan (Fujise, Y., Kawahara, S., Pastene, L.A. and Hatanaka, H. Eds.) Report of 2000 and 2001
feasibility study of the Japanese Whale Research Program under Special Permit in the western North Pacific-Phase II(JARPN II). Paper SC/54/O17 submitted to the 54th IWC Scientific Committee Meeting (Available from the IWC
Secretariat).

6

Tamura, T and Fujise, Y. 2002b. Daily and seasonal prey consumption by common minke whale and Bryde’s whale in
the western North Pacific. Appendix 4. pp 85-96. In: Government of Japan (Fujise, Y., Kawahara, S., Pastene, L.A.
and Hatanaka, H. eds.), Report of 2000 and 2001 feasibility study of the Japanese Whale Research Program underSpecial Permit in the western North Pacific-Phase II (JARPN II). Paper SC/54/O17 submitted to the 54th IWC
Scientific Committee Meeting (Available from the IWC Secretariat).
Yoshida, H., Kato, H., Kishiro, 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. Reportof the coastal survey on common minke whales off Sanriku coast, northeast Japan: the Japanese Whale Rsearch
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 Meeting, XXpp.

7

Table 1. Sample size of common minke whale off Kushiro region

Year

Month Number Empty

1996

Aug.

15

0

1

Sept.

15

0

0

1999

June

44*

0

0

2000

Aug.

1

0

0

Sept.

17

0

1

2001

June

10

0

0

2002

Aug.

6

0

0

Sept.

54

1

3

6 Fundus broken

Sept.
Oct.

37
13

0
0

2
0

1 Fundus broken

2002C

BrokenComment

3 Fundus broken
2 Fundus broken*3 inds. Out of research area.
Table 2. Wet weight composition (%) in the stomach contents of common minke whales off Kushiro region

Month

Year

May-June Average
Aug.-Sept. Average

N

Pollock

Krill

Anchovy

Saury

Squid

Others

All

35.2
26.1

6.5
19.9

58.3
18.3

0.0
24.6

0.1
10.7

0.0
0.3

Table 3. Sex and maturity composition of common minke whales off Kushiro region

Table 4. Estimated field metabolism and daily consumption during feeding period of common minke whales
Sex maturity

Body

Field

Daily

weightmetabolism

consumption(kg)(KJ/day)(Feeding period: kg)

Inmature male

2,500

395,000

120.1

Inmature female

2,600

410,800

125.0

Maturre male

4,800

600,000

182.5

Maturre female

5,900

737,500

244.3

8

Table 5. Estimated seasonal consumption during feeding period (from May to October) of common minke whales off
Kushiro Region
A. TotalAbundance of common minke whale

Consumption(individuals)(tons)

References

821

Best estimate

25,631 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

8,866

2,369

95％ confidence upper level

73,958

1,194Best estimate

37,275 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

13,8303,215

95％ confidence upper level

100,369803

Best estimate

25,069 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

14,0801,428

95％ confidence upper level

44,581

B. KrillAbundance of common minke whale

Consumption(individuals)(tons)

References

821

Best estimate

3,008 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

1,040

2,369

95％ confidence upper level

8,679

1,194

Best estimate

4,374 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

1,623

3,215

95％ confidence upper level

11,778803

Best estimate

2,942 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

1,652

1,428

95％ confidence upper level

5,231

C. Japanese anchovy

Abundance of common minke whale

Consumption(individuals)(tons)

821

Best estimate

References

10,926 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

3,779

2,369

95％ confidence upper level

31,526

1,194

Best estimate

15,890 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

5,895

3,215

95％ confidence upper level

42,785803

Best estimate

10,686 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

6,002

1,428

95％ confidence upper level19,0049

D. Pacific saury

Abundance of common minke whale

Consumption(individuals)(tons)

821

Best estimate

References

3,486 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

1,206

2,369

95％ confidence upper level

10,0591,194Best estimate

5,070 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

1,881

3,215

95％ confidence upper level

13,652803

Best estimate

3,410 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

1,915

1,428

95％ confidence upper level

6,064

E. Walleye pollock

Abundance of common minke whale

Consumption(individuals)(tons)

References

821

Best estimate

6,495 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

2,247

2,369

95％ confidence upper level

18,742

1,194

Best estimate

9,446 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

3,505

3,215

95％ confidence upper level

25,435803

Best estimate

6,353 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

3,568

1,428

95％ confidence upper level

11,297

F. Japanese common squid

Abundance of common minke whale

Consumption(individuals)(tons)

References

821

Best estimate

1,678 Miyashita, 1991,1992 (Sept.)284

95％ confidence lower level

580

2,369

95％ confidence upper level

4,841

1,194

Best estimate

2,440 Hakamada and Matsuoka, 1999 (July)443

95％ confidence lower level

905

3,215

95％ confidence upper level

6,570

803

Best estimate

1,641 Hakamada and Matsuoka, 2002 (Sept.)451

95％ confidence lower level

922

1,428

95％ confidence upper level

2,918

10

Table 6. Fish catches of Pacific saury, walleye pollock and Japanese common squid off Kushiro region from May to
October in 2002
・ A. Pacific saury

Month/Location
May
June
July
AugustSeptember
October
Total

NemuroAttkeshi

Kushiro286
8,541
18,986
19,41547,228248
5,327
11,267
10,51427,3568
6,886
11,978
11,90830,780

Hiroo

Total

0
32
14
17
63

542
20,78642,24541,854105,427

4
7
11

Total
1,837
99
7
5
15,0507,461
22,523・ B. Walleye pollock

Month/Location
May
June
July
AugustSeptember
October
Total

Nemuro Attkeshi
1

1
2
3
6

Kushiro
1,836
99
7
4
15,0447,451
022,506

Hiroo

KushiroHiroo

・ C. Japanese common squid

Month/Location
May
June
July
AugustSeptember
October
Total

Nemuro24
87

111

Attkeshi

1
4
2
7

5
277
300
582

11

47
68
106
56
277

Total
0
0
71
161
387
358
977

Table 7. Estimated biomass of each prey off Kushiro region using by echo sounder (from Murase et al. 2002)
A. June (2001 JARPN II (19-24 Jun.))Prey species

Estimated biomass (103 tons)

Krill

101.9

Japanese anchovy

3.5

Walleye pollock

152.3

B. August (2000 JARPN II (5-7 Aug.))Prey species

Estimated biomass (103 tons)

Krill

349.0

Japanese anchovy

26.9

Walleye pollock

-

12

200m
Kushiro1,000m500m

Fig. 1. Research area off Kushiro region（A） Japanese anchovyz(a). 1999 JARPN (June)(b). 2000 JARPN II (August and September)

75

75
N = 110N = 87
50

%

%

50

25

25

0

0
0

50

100

0

150

50

150

mm

mm

(c). 2001 JARPN II (May and July)(d). 2002 JARPN II (August and September)
75

75

N =148N = 74
50
%

50
%

z

100

25

25

0

0

0

50

100

0

150

50

100
mm

mm

Fig. 2. Body length of distribution in the stomachs of common minke whales off Kushiro region.

13

150

z

(e). 2002 JARPN II coastal (September and October)75
N =109

%

50

25

0
0

50

100

150

mm

（B） Pacific sauryz (a). 1996 JARPN (August and September)
20(b). 2000 JARPN II (August)60

N = 917N = 19
40
%

%

15

10

20
5

0

0
100

150

200

250

300

100

350

150

200

250

300

350

mm

mm

z (c). 2002 JARPN II (August and September)(d). 2002 JARPN II coastal (September and October)
20

30

N =34

N =97

15

%

%

20

10

10

5

0

0
100

150

200

250

300

100

350

150

200

250
mm

mm

Fig. 2. Continued

14

300

350

（C） Walleye pollockz(a). 1996 JARPN (September)(b). 1999 JARPN II (June)3030

N = 199

N = 25

20

%

%

20

10

10

0

0
300

350

400

450

500

300

550

350

400

z

(c). 2000 JARPN II (August and September)

500

550

450

550

(d). 2001 JARPN II (June)3030

N = 34

N = 48

20
%

％

20

10

10

0

0
300

350

400

450

500

150

550

250

350
mm

mm

z

450
mm

mm

(e). 2002 JARPN II coastal (September and October)
30
N =34

%

20

10

0
300

350

400

450

500

550

mm

（D） Japanese common squidz(a). 2000 JARPN II (September)(b). 2002 JARPN II coastal (September and October)40

40

N =205N = 57
30

%

%

30
20

20

10

10

0

0
100

150

200

250

100

300

150

200
mm

mm

Fig. 2. Continued
15

250

300

43°N

500m
200m

1,000m

2,000m

42°N
143°E

144°E

145°E

146°E

△: Krill; ○: Japanese anchovy; ●: Pacific saury; □: Walleye pollock; ×: Japanese common squid
Fig. 3. Sighting positions and stomach contents of common minke whales sampled in JARPNII 2002.
（Fishing ground (shaded areas) of Pacific saury off Kushiro region during 18 to 24 September 2002.
The information was obtained from telex No. 1801 relating to the fishing ground supplied to the
Fishing Service Centre in Japan.）16