J-STAGE Advance published date: December 8, 2021

JAPANESE WHALE SIGHTING SURVEYS IN THE CHUKCHI SEA

HISTORICAL JAPANESE WHALE SIGHTING SURVEYS
IN THE CHUKCHI SEA
Keiko SEKIGUCHI
Iruka Lab, 3–10–15 Tamagawa, Chofu, Tokyo 182–0025, Japan
Corresponding author: keiko.the.dolphin@gmail.com

Abstract
Before the T/S Oshoro Maru surveys in 2007 and 2008, three Japanese research vessels had
conducted whale sighting surveys in the Chukchi Sea, in 1937 (R/V Kaihou Maru and YūkiMaru) and 1958 (R/V Fumi Maru No.16). However, their results are not well-known. The author found four references about these voyages and compared the results with T/S Oshoro Marudata from the 2007 and 2008 voyages. Despite the long period separating these surveys (about
20 years and then 50 years), the whale distributions in this region were somewhat similar.
Key words:

Chukchi Sea, Japanese whale sighting survey, large whale species.

Despite its biological importance, the Chukchi Sea is one of the least surveyed regions. This region is closed down for a long period by winter ice, and often covered by deep fog during summer.
However, at least three Japanese research vessels managed to conduct oceanographic and biologicalsurveys in the Chukchi Sea, including shipboard cetacean sighting surveys. R/V Kaihou Maru (theMinistry of Agriculture and Forestry, 1064 gross tonnage) and Yūki Maru (Hokuyou-Hokei Co., 350
gross tonnage) carried out surveys from the end of July to the beginning of August, 1937, and theR/V Fumi Maru No.16 (Taiyo Fisheries Co., 598 gross tonnage) survey was conducted in the summerof 1958. This author found four cruise reports in Japanese about these cruises (Nasu, 1960a, 1960b;
Yamaguchi, 1961; Tatou, 1985). The cruise report of R/V Yūki Maru has not been found, and thus its
data were extracted from Nasu (1960a) and Tatou (1985). The author had an opportunity to conductcetacean sighing surveys in the Chukchi Sea from T/S Oshoro Maru (Hokkaido University, Japan;
72.8 m length and 1,779 gross tonnage) as a part of the International Polar Year (IPY) special researchin summer 2007 and 2008. It seems that these historical cruises did not have systematically organized
track lines in the way our Oshoro Maru cruises did; however, their data are very important for describing the distribution of whales in this region in the past. In this Short Note, the author would like tocompare sighting results among those historical cruises and the T/S Oshoro Maru cruises, in order toinvestigate any change in whale occurrence in the Chukchi Sea.
R/V Kaihou Maru and Yūki Maru survey in summer 1936
The R/V Kaihou Maru entered the Chukchi Sea on 26 July, 1937 and reached the furthest northpoint (71°12′N, 174°50′W) by a Japanese vessel in 29 July. The vessel continued its survey westward
along the ice edge and then on 1st August headed back along the Russian coast line. Their survey covered the entire western part of the Chukchi Sea (Fig. 1) and Table 1 shows the summary of their cetacean sightings extracted from Yamaguchi (1961). Six species of large whales were sighted: blue whale
Balaenoptera musculus, ﬁn whale B. physalus, humpback whale Megaptera novaeangliae, right whale
Eubalaena japonica, minke whale B. acutorostrata and sperm whale Physeter macrocephalus.
On the other hand, the R/V Yūki Maru sailed along the entire coast line of the Chukchi Sea in about
the same period (26 July to 3 August, 1937) (Fig. 2, from Nasu, 1960a). The main purpose of the R/VYūki Maru voyage was the investigation of possible new whaling grounds and thus it is presumed thatthe vessel had professional observers. Unfortunately, no detailed data could be found for this Yūki
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Fig. 1. The track line and whale sighting locations of R/V Kaihou Maru in summer 1937 (the ﬁgure wasconverted from Fig. 2 in Yamaguchi, 1961). Sighting location data are from Table 1.
Table 1. Sighting summary for R/V Kaihou Maru survey in summer 1937. Data were extracted from Table 1in Tatou (1985).
Species
Sighting location

Blue
whale

66°36′N, 169°43′W

Fin
whale

Humpback
whale

Sperm
whale

Right
whale

15–1666°42′N, 169°49′W

167°20′N, 170°08′W

1170°00′N, 173°05′W

169°50′N, 179E50′W
67°05′N, 171°05′W

615–1667°00′N, 170°55′W

866°50′N, 170°35′W

about 200

66°42′N, 170°35′W

Minke
whale

11about 100

5066°38′N, 170°15′W

about 100

66°25′N, 169°52′W

2Maru survey (Table 2), but Nasu (1960b) described that “many” ﬁn whales were sighted near the coastof Siberia (66°40′N, 170°W), at least one humpback whale, and a rather unusual sighting of a rightwhale and a sperm whale.

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Fig. 2. The track line and sighting positions by R/V Yūki Maru in 1937 summer (from Fig. 5 in Nasu, 1960a).
Symbols explanation: sperm whale (closed circle); ﬁn whale (hatched circle); humpback whale (crossed circle);right whale (circle with a big black dot). Circles with a small dot indicate vessel position at noon.
Table 2. Sighting summary from R/V Yūki Maru during the 1937 summer cruise, based on data from Nasu,
1960a and Tatou, 1985.
Species

Total no. of animals

Approximate sighting location

Fin whale
Humpback whale
Right whale
Sperm whale“many”
1?
1?
?

66°40′N, 170°W
66°40′N, 170°W
66°30′N, 170°W
66°30′N, 170°W

R/V Fumi Maru No.16 survey in summer 1958The R/V Fumi Maru No.16 surveyed the Chukchi Sea between 16 and 20 August 1958. Fig. 3
shows the track line and Fig. 4 indicates whale sighting locations (ﬁgures from Nasu, 1960a). A totalof 86 animals were sighted. Most were gray whales Eschrichtius robustus (82 animals), but there werealso two right whales, one ﬁn whale, and one unidentiﬁed whale (Table 3; data from Nasu, 1960a).
T/S Oshoro Maru survey in summer 2007 and 2008
The T/S Oshoro Maru conducted two IPY oceanographic and biological research cruises in theChukchi Sea. In 2007, the survey started from 5 August and ended on 15 August at Nome, AK. In
2008, the cruise schedule was a month earlier, starting from Nome on 6 July and ending at Dutch Harbor, AK on 17 August. Details of course lines and oceanographic observations are available in data
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Fig. 3. The track line of R/V Fumi Maru No.16 survey in summer 1958 (from Fig. 1 in Nasu, 1960a).

books from Hokkaido University (Faculty of Fisheries Sciences, Graduate School of Fisheries Sciences, School of Fisheries Sciences, Hokkaido University 2008, 2009). Table 4 summarizes sighting
results in the Chukchi Sea and Fig. 5 shows track lines and cetacean sighting positions. A total of six
cetacean species were identiﬁed: bowhead whale Balaena mysticetus (30 animals in 2007), humpback
whale (three in 2007 and one in 2008), minke whale (three in 2007 and nine in 2008), gray whale (212in 2007 and 16 in 2008), killer whale Orcinus orca (ﬁve in 2007) and harbor porpoise Phocoena phocoena (one in 2007 and six in 2008).
These ﬁve relevant cetacean surveys were done a long time apart (about 20 years, then 50 years respectively); however, sighting locations are rather similar, the main locations being just after the Bering Strait and oﬀ Point Hope. Russian–American aerial and shipboard surveys between 1968 and 1982
also indicated gray whale aggregations just after the Bering Strait (Berzin, 1984). It seems these large
whale species utilized the Chukchi Sea region as their summer feeding area, well before the area waswidely freed from ice because of “global warming”.
Table 5 summarizes the presence/absence of large whale species sighted in the Chukchi Sea survey areas by the ﬁve cruises. Only R/V Kaihou Maru sighted six species of large whales, blue, ﬁn,humpback, right, minke and sperm whales, but not gray whales, in the Chukchi Sea surveyed area
(also see Table 1). Nasu (1960a) assumed poor sightings from R/V Fumi Maru No.16 were caused bybad visibility (dense fog) and the whale migration period. The second year (2008) of the T/S Oshoro
Maru Chukchi Sea survey also encountered very poor visibility condition and thus the total sighting
was much less than in the previous year (Table 4). Poor visibility for the R/V Fumi Maru No.16 survey
might have caused a lack of humpback whale sightings as well. Humpback whales were sighted inlarge numbers (about 120? animals in total, Table 1) by R/V Kaihou Maru, at least one animal by R/VYūki Maru (Table 2) and one school in each of the T/S Oshoro Maru 2007 and 2008 surveys (Table 4).
Although no ﬁn whales were sighted by the T/S Oshoro Maru 2007 and 2008 surveys, animals weresighted in the three surveys in 1936 and 1958 (Tables 1, 2, 3 and 5; Figs. 1, 2, and 4). Fin whales were

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Fig. 4. Whale sighting positions during the R/V Fumi Maru No.16 survey in summer 1958 (from Fig. 4 inNasu, 1960a).
Table 3. Sighting summary from R/V Fumi Maru No. 16 during the 1958 summer cruise, based on data fromNasu, 1960a and Tatou, 1985.
SpeciesFin whale
Right whale
Gray whale

UnID whaleTotal no. of animals

Approximate sighting location

127822150 nm oﬀ Point Hopeoﬀ Point Hope?
67°N, 170°Woﬀ Point Hope?
?

sighted oﬀ the Bering Strait and Point Hope, and even at the far north ice edge (66°36′N, 169°43′W;
Table 1; Fig. 1). Fin whales were often sighted in the Bering Sea during the T/S Oshoro Maru 10-year
cruises (a total of 399 ﬁn whales in 174 groups, Table 1 in Sekiguchi, 2015). Before the North Paciﬁcﬁn whaling ban in 1976, the ﬁn whale summer geographical distribution might have extended further
into the Chukchi Sea. Berzin and Rovnin (1966) and Tomilin (1967) also noted the occurrence of ﬁnwhales in the Chukchi summer.
Sightings of right whales by R/V Kaihou Maru, Yūki Maru and Fumi Maru No.16 were rather unusual. Tomilin (1967) reported the record at Cape Prince of Wales and the possible further north distriCetacean Popul. Stud. (CPOPS), Short noteVol. 3, 2021, 265–272

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Table 4.

Sighting summary from the T/S Oshoro Maru IPY surveys in summer 2007 and 2008.

Species20072008

Total numbers of

Total numbers ofSchool

Individuals

SchoolIndividuals

Bowhead whale
Humpback and like-humpback whale
Minke and like-minke whale
Gray and like-gray whale
Killer whale
Harbor porpoise
UnID large baleen whale
UnID large whale
UnID small whale
UnID whale
UnID dolphin
Dead whale

112
121
1
91211130
33
212
5135
222
1
10
1
6
50
32
1
2
50
10
1
9
160
62
1
2
50
1

Total

33

297

26

43Fig. 5.

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Cetacean sighting positions by the T/S Oshoro Maru in summer 2007 and 2008.

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Table 5. The summary of sighted whale species for each survey in the Chukchi Sea (present (✓) or absent (abs)).
Survey year

1937

1937

1958

2007

2008

Research vessel

Kaihou Maru

Yūki Maru

Fumi Maru

Oshoro Maru

Oshoro Maru

Bowhead/NP right whale
Blue whale
Fin whale
Humpback whale
Minke whale
Gray whale
Sperm whale

✓✓
✓
✓
✓
abs.
✓✓
abs.
✓✓
abs.
abs.
✓✓
abs.
✓abs.
abs.
✓abs.

✓abs.
abs.
✓✓✓
abs.

abs.
abs.
abs.
✓✓✓
abs.

bution, but at present no other record of right whales in the Chukchi Sea has been found. The T/S Oshoro Maru 2007 survey encountered a school of bowhead whales oﬀ Point Hope, where R/V Kaihou
Maru and Fumi Maru No.16 sighted right whales. It is possible that they might have mistaken rightwhales for bowhead whales.
Gray whales have been known to be abundant in the Chukchi Sea for years (Nikulin, 1946; Berzin
and Rovnin, 1966; Tomilin, 1967; Berzin, 1984; Sekiguchi, 2015), however, no sightings were reported from the 1937 cruises (Table 5). This might be related to the migration period of gray whales, since
their cruise period was a bit earlier than those of the R/V Fumi Maru and T/S Oshoro Maru.
The two 1937 cruises had sightings of sperm whales (Tables 1, 2, and 5). There is no oﬃcial recordof sperm whales in the Chukchi Sea, although Berzin and Rovnin (1966) wrote about sighting reportsof this species. Sperm whale sightings could be due to a misidentiﬁcation, but it is hard to believe
whaling professionals made such a mistake for sperm whales. If there is an original cruise report forthe R/V Yūki Maru voyage, it may provide the answer.
To conclude, these old Japanese whale sighting survey data are important for investigating thechange in whale distribution in the Chukchi Sea over the years. It is necessary to look for the detailed
sighting data for the R/V Yūki Maru, which are missing from this study.
Acknowledgements

The author thanks all crews of T/S Oshoro Maru and research participants during the 2007 and 2008 IPY summer cruises
for their help. Professor Seiichi Saito, Hokkaido University, invited the author on the T/S Oshoro Maru cruises. Very special
acknowledgement goes to the late Dr. Seiji Ohsumi, the Institute of Cetacean Research, who brought the R/V Yūki Maru andother Japanese voyages to the Chukchi Sea to my attention. Without his deep knowledge of the history of Japanese whale
surveys, the author would never have noticed these important works as presented in this Short Note. Dr. John W. Menzies,
South Africa Astronomical Observatory, kindly checked the English. The comments of reviewers helped to improve thismanuscript.

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Received: January 31, 2021
Accepted: April 28, 2021
Published online: December 8, 2021

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