J-STAGE Advance published date: November 8, 2021

KATSUMATA, HIROSE, NAKAJO, SHIBATA, MURATA, YAMAKOSHI, NAKAMURA AND KATOEVIDENCE OF WINTER MIGRATION OFHUMPBACK WHALES TO THE HACHIJO ISLAND,IZU ARCHIPELAGO OFF THE SOUTHERN COAST
OF TOKYO, JAPANTaiki KATSUMATA1, 2*, Ayumi HIROSE1, Ken NAKAJO1,
Chieri SHIBATA1, Haruna MURATA1, Tadashi YAMAKOSHI3,
Gen NAKAMURA1 and Hidehiro KATO1, 2
1

Tokyo University of Marine Science and Technology, 4–5–7 Konan, Minato-ku, Tokyo 108–8477, Japan
2
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan
3
Hachijo Town Oﬃce, 2551–2, Oogago, Hachijo Town, Tokyo, 100–1401, Japan*Corresponding author: katsumata@cetacean.jp

Abstract
In the western North Paciﬁc Ocean, humpback whales (Megaptera novaeangliae) migrate
to the Okinawa (26°13′N, 127°41′E) and Ogasawara (27°04′N, 142°13′E) islands of Japanfor breeding. The Hachijo Island (33°06′N, 139°47′E) is located in the Izu Archipelago —further north from known wintering grounds of those whales. In the 2015–16 winter, humpback
whales were sighted around the Hachijo Island in signiﬁcant numbers. This led to a monitoring project of whales around the island that was initiated from the 2016–17 winter to elucidate
their migration. Here, we report the results of monitoring over two subsequent winter seasons(2016–17 and 2017–18). A survey was conducted within 5 nautical miles of the coast of theisland using a dedicated vessel (12GT) for respectively 32 and 34 days in the ﬁrst and second
season from November to April. Humpback whales were sighted from November to March inthe ﬁrst season and from November to April in the second season, and a total of sightings ofrespectively 205 and 397 whales were recorded in the 2016–17 and 2017–18 seasons. Characteristic behaviors in the wintering grounds, such as singing and forming competitive groups,
were conﬁrmed in both seasons. Moreover, around 15% of the whales were repeatedly sighted
during the same season, and six individuals observed in the ﬁrst season were resighted in thesecond season. These results suggest that waters around the Hachijo Island are part of the winter migration grounds of humpback whales, and their migration to waters oﬀ the Hachijo area
is expected to continue in the future. Long-term monitoring focusing on the social compositionof groups is necessary, and additional photo-identiﬁcation and genetic data should be collected
to shed light on the habitat use and causes of sudden occurrence of humpback whales aroundthis island.
Key words:

Hachijo Island, humpback whale, wintering ground, Photo-ID, residency, site
ﬁdelity.

Introduction
Humpback whales (Megaptera novaeangliae) belong to the family Balaenopteridae of the suborder
Mysticeti (Fig. 1). They undergo seasonal migration, staying in highly productive feeding grounds
at high latitudes during the summer and autumn and migrating to breeding grounds at temperate low
latitudes in winter (Dawbin, 1966; Baker et al., 1986; Clapham, 2000). In the North Paciﬁc Ocean,

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HUMPBACK WHALES OFF THE HACHIJO ISLAND, TOKYOFig 1.

Humpback whale. This Photo was taken in 22 January, 2017 at Hachijo Island.

Fig. 2.

Map of Hachijo Island and two other major wintering grounds of humpback whales known in Japan.

some wintering grounds have been reported, namely the coasts of Mexico, Revillagigedo Archipelago(Urbán and Aguayo, 1987), Hawaii (Baker and Herman, 1981), the Philippines (Acebes et al., 2007),
Ogasawara Islands (Darling and Mori, 1993), Okinawa (Nishiwaki, 1959; Kobayashi et al., 2016), andMariana Archipelago (Hill et al., 2020). The occurrence peak of humpback whales in the wintering
ground of the North Paciﬁc Ocean generally lasts from February to March (Urbán and Aguayo, 1987;
Mobley et al., 1999; Kobayashi et al., 2016). In the wintering grounds, some behaviors related to themating of humpback whales were observed. Male humpback whales sing long complex songs (Payne
and McVay, 1971; Baker and Herman, 1984), and males compete physically among multiple male
whales for mating opportunities with females (Tyack and Whitehead, 1983; Baker and Herman, 1984;
Clapham, 2000).
In November 2015, we received a report from diving companies that an unusually large numberof humpback whales appeared around the Hachijo Island (Kono E. and Yamakoshi, pers. comm.).
The Hachijo Island is located south of Tokyo in the southern part of the Izu Archipelago (33°06′N,
139°47′E), approximately 700 km north of the Ogasawara Islands, which is one of the known primary
wintering grounds of humpback whales in Japan (Fig. 2). According to Uda (1954), the waters around
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the Hachijo Island have not been previously reported as the whaling grounds of humpback whales. Furthermore, there has been no scientiﬁc monitoring of large whales in this region. Therefore, there are not
any previous formal records which mention whether humpback whales migrated to this region seasonally or not. Before this sudden migration in 2015, only ﬁve sporadic sightings of humpback whales aroundthis island were reported, including once each in April 2005 and May 2010 and thrice in March 2013
(Tokyo Metropolitan Government Park Association Hachijo Visitor Center, pers. comm.).
Therefore, on December 23, 2015, the Japan Broadcasting Corporation (NHK) and the Laboratoryof Cetacean Biology, Tokyo University of Marine Science and Technology (TUMSAT) collaborated tovisually survey the coastal area of Hachijo Island. In this preliminary survey, 37.4 nautical miles weresearched along the coast of the island and at least 10 humpback whales belonging to ﬁve social groups
were sighted in the southwest part of the island in water depths less than 200 m. Moreover, a song was
conﬁrmed and recorded.
To examine whether the migration of a signiﬁcant number of whales around the Hachijo Island is
temporary and to collect photo-identiﬁcation data for investigating the migratory connections to otherareas, a shipboard survey has been conducted around the island by the local government and TUMSAT throughout the breeding season (November to April) since 2016. The present study reports the results of monitoring over two subsequent seasons (2016–17 and 2017–18) and explores the importanceof waters around the Hachijo Island as wintering grounds of western North Paciﬁc humpback whales
based on occurrence, behavior, and photo-identiﬁcation data.

Materials and Methods
Field Survey
We conducted surveys within ﬁve nautical miles of the coast of the Hachijo Island, departing fromand arriving at the Yaene Port (33°06′N, 139°46′E). In the ﬁeld the Aki-Maru, a small dedicated research vessel of 12 GT (length, aprox. 15 m; width, 2.5 m) with a single inboard diesel-powered engine was used. Three researchers on board visually searched for whales with the naked eye from theobservation platform (3 m above sea level). The survey was conducted from 9:00 to 15:00, and thesearch speed of the vessel was set at 8–9 knots. When whales were sighted, one researcher recorded
the time and position of the vessel (latitude and longitude) using a global positioning system (Garmin
eTrex10J). When the vessel reached the estimated location at which the whales were spotted, one
researcher recorded the time, position, and sea surface temperature (SST), and two other researchersattempted to take photographs for identiﬁcation. In addition, the behavior and group size of the whales
were observed and recorded. The researchers lowered a hydrophone (OKI Whalephone II) at least
once per day to evaluate whether the whales were singing.
Photo-identiﬁcation
Humpback whales can be identiﬁed based on the pattern of pigmentation on the ventral ﬂuke andthe shape of its edge (Katona and Whitehead, 1981). When humpback whales were sighted, the vessel
immediately followed the target group, and the researchers took photographs for identiﬁcation using a
NIKON D7000 camera with a 55–300 mm lens (AF-S DX NIKKOR 55–300 mm f/4.5–5.6 GED) anda NIKON D7500 camera with a 19–300 mm lens (AF-S DX NIKKOR 18–300 mm f/3.5–5.6 GED).
Two types of surveys were conducted—one was circling around the island, and the other was staying
in the waters where sightings were expected. In both types of surveys, we attempted to take as many
photographs as possible.
After the surveys were completed in each season, the resightings were compiled to assess the residency around the island during a season. In the present study, the good-quality photographs that werein focus and clearly showing the pattern of pigmentations on the ventral ﬂuke and the shape of its

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HUMPBACK WHALES OFF THE HACHIJO ISLAND, TOKYOedge were used. We printed the photographs obtained during each season and sequentially comparedthem by visual examination to identify the individuals. Each of the three researchers performed theabove steps, and the ﬁnal identiﬁcation results were compiled as resightings. The individuals re-photographed at intervals of 1 or more days within the same season were considered resightings. Moreover,photographs were compared between the 2016–17 and 2017–18 seasons to assess whether the same
individuals migrated to areas around the Hachijo Island in the following season.

Results and Discussion
Survey eﬀort and sightings
Table 1 summarizes the results of the survey eﬀort and sightings during the 2016–17 and 2017–18
seasons. The survey was conducted for respectively 32 and 34 days from November to April in the
2016–17 and 2017–18 seasons. Table 2 summarizes the monthly survey eﬀort for each season. In bothseasons, a large amount of eﬀort was devoted to February and March when the occurrences of whales
were generally expected to be high in order to obtain more Photo-ID (Urbán and Aguayo, 1987; Moriet al., 1998; Mobley et al., 1999; Kobayashi et al., 2016). The survey area and track lines during eachseason are illustrated in Fig. 3. In the 2016–17 season, we covered 986.0 nautical miles in total, andthe ﬁrst sighting of a humpback whale in the season was recorded on November 20, 2016. From thatday until March 19, 2017, 205 whales belonging to 136 social groups were sighted. In the 2017–18
season, we covered 835.6 nautical miles in total and sighted 397 whales belonging to 232 socialgroups from November 28, 2017, to April 9, 2018. The mean sighting rate in the 2017–18 season (11.7
whales per day) was approximately two times the rate in the 2016–17 season (6.4 whales per day).
Fig. 4 presents the monthly changes in sighting per unit eﬀort (SPUE; number of whales sighted perday) in both seasons. The temporal trend of occurrences in a season is one of the critical indicators toclarify the habitat use of humpback whales during the winter. In Okinawa (Kobayashi et al., 2016)
and Ogasawara (Mori et al., 1998), the period of the most frequent occurrence of whales was fromFebruary to March, with a single peak. The trend observed in eastern Australia, which is considereda migration corridor, frequently occurs in the early stages of the season; this is followed by a decline
and then an increase in number of whales at the end of the season (Burns, 2010).
Table 1. Survey period, survey eﬀort (number of days surveyed and total search distance in nautical miles),
total number of sightings, and sightings per unit eﬀort (SPUE) in each winter season.
SeasonStart survey
Finish survey(yyyy/mm/dd) (yyyy/mm/dd)

2016/172017/18

2016/11/18
2017/11/28

2017/04/24
2018/04/23

Survey eﬀort Survey eﬀort
Sightings
SPUE(days)(nautical miles) (groups/whales) (whales/days)
32
34

986.0
835.6

136/205
232/397

6.4
11.7

Table 2. The number of survey days and searching distance per month in each season. The study was
designed to increase survey eﬀorts in February and March as the frequency of humpback whale occurrence inthe wintering ground was expected to be high.
SeasonSurvey eﬀort
Unit

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

Total

2016/17

Days
Nautical miles

3
134.4

5
169.5

4
103.1

7
182.3

9
233.5

4
163.2

32
986.0

2017/18

Days
Nautical miles

2
61.5

6
137.3

5
127.3

9
214.3

8
192.1

4
103.2

34
835.6

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Fig. 3. Survey track lines in the 2016–17 (left) and 2017–18 (right) winter seasons. The survey was conductedwithin 5 nautical miles from the coast of Hachijo Island in both seasons.

Fig. 4. Monthly sightings per day from November to April in the 2016–17 and 2017–18 seasons. SPUE:
Sightings per unit of eﬀort.

In the ﬁrst season, a single peak of occurrences around the Hachijo Island was recorded in February; however, in the second season, SPUE decreased after a peak in December and then increased in
March. The Kuroshio Current path is one of the possible reasons for these diﬀerences in the temporal
trends of whale occurrence between the two seasons. The Kuroshio large meander was underway
since August 2017, and the current path around the Hachijo Island (around 140°E) signiﬁcantly differed between the ﬁrst and second seasons (Qiu, 2019). In the Southern Hemisphere Madagascar
wintering grounds in, humpback whales swim along strong currents during non-migratory oﬀshore
movements (e.g., travel between breeding sites or short-term oﬀshore travel) (Trudelle et al., 2016).
Assuming that humpback whales behave in the same manner around the Hachijo Island, they mightswim near the island or oﬀshore depending on the Kuroshio Current path. This may have also aﬀected the number of annual sightings in the survey area. However, detailed investigation to elucidate theabove is not possible with data collected for only 2 winter season surveys. In addition, the unevenness in the amount of eﬀort in each month of the season raises the possibility that the SPUE of somemonths does not adequately reﬂect the relative abundance of whales. Based on the above, the present
study results do not allow us to determine when the peak in the number of migrating whales to Hachijo Island occurs, and it is not possible to conclude whether the use of the area by humpback whales issimilar to that of Okinawa and Ogasawara. Therefore, continuous ﬁeld surveys and long-term monitoring of individuals through satellite telemetry are necessary to understand the trend of occurrence of
humpback whales around Hachijo Island. However, as humpback whales were continuously sighted
around Hachijo Island from November to March for the two consecutive seasons, it is reasonable toassume that this species uses this area for winter migration.

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Characteristic behaviors
Humpback whale singing behavior was conﬁrmed from mid-January to late March in 2016–17
and from late November to late March in 2017–18. Singing behavior is considered to play speciﬁcroles; as such, songs serve as an acoustic display to attract females, a threat behavior during intrasexual competition, and a spacing function among males (Clapham, 2000). Furthermore, on March 5,2017, a group of four whales and another group of two whales merged to form a six-whale group. The
whales of this group swam violently. For instance, one individual hit its head on the water surface,
while another pushed other whales with its head. These behaviors were consistent with the competitive behaviors reported in the wintering grounds by Tyack and Whitehead (1983) as well as by Baker
and Herman (1984). Such competitive behaviors were observed respectively two and three times in
the 2016–17 and 2017–18 seasons. Based on the observations of singing and competitive behaviors,
humpback whales likely use the areas around the Hachijo Island as a mating ground.
Photo-identiﬁcation
A total of 203 individuals were identiﬁed during both seasons. Respectively 58 and 151 individuals were identiﬁed in the 2016–17 and 2017–18 seasons, and six individuals were identiﬁed in bothseasons. Table 3 summarizes the results of photo-identiﬁcation in the same season, and Tables 4a and4b summarize the survey dates and the dates when individuals were resighted for each season. In the
2016–17 season, 10 of the 58 individuals (17.2%) were resighted within the same season. Nine of ten
individuals were resighted once, while one individual was resighted twice, and the period between theﬁrst and the last sighting (or occupancy) ranged from 1 to 40 days (mean: 9.5 days; SD: 13.7 days).
In the 2017–18 season, 21 of the 151 individuals (13.9%) were resighted within the same season.
Thirteen of the 21individuals were resighted once, six were resighted twice, and one individual was
resighted each three and four times, respectively; and the occupancy ranged from 1 to 52 days (mean:
10.6 days; SD: 15.4 days). Thus, in both seasons, most of the individuals were not resighted andaround 15% were resighted within the same season.
The proportion of individuals resighted during a season provides basic information on the residencyof humpback whales. For instance, a high proportion indicates that individuals are likely to be resighted in a certain area and tend to stay there for a long period, whereas a low proportion indicates that individuals are less likely to be sighted in a certain area and tend to move around instead of staying. The
frequency of resighting in the Hawaiian waters (oﬀ Kauai) was 5%–14% (Cerchio, 1998), and similarvalues have also been reported in Silver Bank (9.1%) (Mattila et al., 1989), Samana Bay (15.8%)(Mattila et al., 1994), Ecuador (12.9%) (Scheidat et al., 2000), and Abrolhos Bank (13%) (Wedekin
et al., 2010). Values of approximately 10%–15% indicate that individuals do not stay in the same
area for a long period and tend to move widely within each wintering ground. This observation is also
supported by the reports using satellite telemetry of extensive local movements in Hawaii (Mate etal., 1998), Silver Bank (Kennedy et al., 2014), and Ecuador (Guzmán and Félix, 2017). In contrast,
the frequency of resighting in the feeding grounds has been reported to be as high as 77.3% in the
Gulf of Maine (Clapham et al., 1993) and as low as 2.1% along the east coast of Australia, which isbelieved to be a migration corridor (Burns, 2010). Of note, these proportions depend on the survey
Table 3. Number of individuals photo-identiﬁed and resighted in each season, and the minimum and maximum period between the ﬁrst and last sighting of the resighted individuals in the same season.
Number of
Photo-IDs
2016/172017/18

58
151

The maximum period
Number of individ- The minimum period between
between ﬁrst and last sighting
uals resighted (%) ﬁrst and last sighting (days)(days)
10 (17.2%)
21 (13.9%)

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1

40
52

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Table 4a. The survey dates and dates when individuals were resighted in the 2016–17 season. Black circle indicates the date an individual was sighted.
ID #

Month

Nov.

Dec.

Jan.

Feb.

Mar.

Apr.

Number of
Day 18 20 29 3 12 13 25 26 17 18 20 22 4 5 8 25 26 27 4 5 8 9 17 18 19 20 23 5 6 23 24 resighting

IH-004
IH-007
IH-008
IH-025
IH-029
IH-037
IH-039IH-043
IH-059IH-061

1
2
1
1
1
1
1
1
1
1

● ●
● ●
● ●

●
●
●

●
●
● ●
● ●
● ●
● ●
● ●

Table 4b. The survey dates and the dates when individuals were resighted in the 2017–18 season.
ID #Month Nov.

Dec.

● ●

IH-101●

IH-049●

IH-127
IH-159

Mar.

Apr.

2

●

1

●

2

● ●
●

1

●
● ●

2

●

1

● ●

IH-166●

IH-169●

IH-176

Feb.

Number of
Day 28 29 9 10 18 20 21 23 7 8 20 21 22 8 9 10 17 18 19 20 21 22 3 4 13 14 15 26 27 28 9 10 22 23 resightings

IH-108

IH-117

Jan.

● ●

●

4

●

1

●

1

● ●

IH-200●●

IH-201●●

1
1

IH-203●●

1

IH-207● ●●2

IH-212● ●IH-2371●

1●

IH-265● ● ●2

IH-276● ●1

IH-279● ●IH-281● ●IH-282● ● ●IH-303

1
2

●
● ●

●

3
1

eﬀort and population size. In the present study, since 80% of the resighted individuals were sighted
within three days of their ﬁrst sighting, the proportion of resighting may have been underestimateddue to 1–2 weeks interval between the survey dates. However, considering the short gap between resighting and the rare sighting of individuals, such as IH-166, for two months, possibly few individuals
remain in the vicinity of Hachijo Island for an extended period, suggesting that the residency of humpback whales around Hachijo Island is comparable to that in other wintering grounds.
Interestingly, 6 of the 58 individuals identiﬁed in the ﬁrst season returned to the waters around theHachijo Island in the subsequent season (Fig. 5). According to Calambokidis et al. (2001), few individuals migrate to diﬀerent wintering grounds every year, and each population has a speciﬁc wintering
ground.

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Fig. 5. Tail photographs of whales that were observed around the Hachijo Island in two consecutive seasons.
Dates indicate the day on which each individual was photographed in each season (all copyrights are reserved
to TUMSAT).

Calambokidis et al. (2001) assessed the site ﬁdelity for North Paciﬁc wintering grounds using the
Match index (Equation 1), which reﬂects the size of the overall population sampled and the degree ofsite ﬁdelity.
The Match index is expressed by the following:
Ii → j = [ mi / ( ai n j )] ×1,000(1)where,
ai =number of marked releases at time 1 in region i (i=1, …, R)
nj =number examined for marks at time 2 in region j
mi=marked recaptures in region j, originally marked in region i
The frequency of identiﬁcation of the same individual in diﬀerent wintering grounds during diﬀerent years was low, and the Match index was 0.015 between Mexico and Hawaii, 0.010 between Hawaii and Japan (Okinawa and Ogasawara), and 0.000 between Mexico and Japan; however, frequency
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of reidentiﬁcation of the same individual in the same wintering grounds but during diﬀerent years was
relatively high, and the Match index was 0.257 for Hawaii, 0.518 for Mexico, and 2.365 for Japan(Calambokidis et al., 2001). Around the Hachijo Island, 58 individuals were marked in the ﬁrst season(ai), 151 individuals were examined for marks in the subsequent season (nj), and 6 individuals wererecaptured (mi). Based on these counts, the Match index was 0.685, indicating that site ﬁdelity for the
Hachijo Island is similar to that reported for Hawaii and Mexico.
Considering that the residency and site ﬁdelity for the Hachijo Island were comparable to those forthe other wintering grounds, the same population likely migrates to the areas around the island annually and uses it as some parts of their wintering grounds. In other words, this area is as important as other wintering grounds for the migration of humpback whales, and migration to waters oﬀ the Hachijoarea is expected to continue in the future.
Absence of mother–calf pairs
Newborn calves (typically approximately 4 m long) were not sighted in both seasons. In Okinawa and Ogasawara, mother–calf pairs have been observed during winter (Darling and Mori, 1993;
Kobayashi et al., 2016). Generally, the SST at the wintering grounds of humpback whales is above
21.0°C (Rasmussen et al., 2007). However, according to daily measurements near the Yaene Port
(33°06′N, 139°50′E) by the Tokyo Metropolitan Islands Area Research and Development Center for
Agriculture, Forestry and Fisheries, the mean SST from November to April was 19.0°C (SD: 3.1°C;
range: 13.6–25.8°C) in the 2016–17 season and 19.9°C (SD: 1.9°C; range: 15.4–24.1°C) in the 2017–18 season. This relatively low SST may be unsuitable for nursing. However, based on a personal communication (Kato, H., Akama, N. and Kono, E., pers. comm.) a mother-calf pair was observed in thesoutheastern part of the island in March 2016, which may have been missed in our survey.
The results of the present study provide novel insights into the annual migration of humpback
whales to the waters around the Hachijo Island and their distinct breeding behavior in winter. However, we cannot conclude whether the waters around the Hachijo Island indeed serve as a breeding
ground for these whales, similar to Okinawa and Ogasawara, given the absence of newborn calves.
The objective of migration to the areas around the Hachijo Island remains debatable, and several
hypotheses have been put forth, such as these areas being part of a migration corridor or this beinga temporary migration. If the waters around the Hachijo Island are established as a breeding groundin the future, mother–calf pairs should be sighted frequently around the island. Therefore, long-termmonitoring focusing on the composition of the social groups should be conducted to reveal the habitatuse. Moreover, in humpback whales, the timing of migration to wintering ground varies depending on
the sex and reproductive status (Dawbin, 1966; Brown et al., 1995) of individuals. Therefore, the sex
and sexual maturity of whales sighted around the Hachijo Islands should be determined and comparedwith those of whales reported in other wintering grounds to clarify the habitat use of the waters aroundthis island.
Causes of sudden appearance
The abundance of humpback whales in the North Paciﬁc Ocean declined from approximately 15,000 in 1905 to 1,000 in 1965 because of catch in commercial whaling (Johnson and Wolman, 1984). Following the prohibition of commercial whaling of this species in 1966 by the International Whaling Commission, the number of humpback whales increased. More recently, theabundance of humpback whales in the North Paciﬁc Ocean was estimated to be 21,063, which isgreater than the estimates of pre-whaling abundance (Barlow et al., 2011). This explosive increase in
the number of humpback whales in the North Paciﬁc Ocean may be one of the reasons for the sudden
appearance of these whales around the Hachijo Island in winter. In fact, the expansion of the wintering
grounds of humpback whales with the recovery of their population in the Hawaiian waters has beenreported (Mobley et al., 1999). Similarly, expansion of the wintering grounds was conﬁrmed near

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Peru (Guidino et al., 2014). However, there are no data on the abundance of humpback whales in thewestern North Paciﬁc Ocean after the “Structure of Populations, Levels of Abundance, and Status of
Humpbacks” (SPLASH) study (Barlow et al., 2011). Further, the population dynamics around 2015,
when humpback whales appeared around Hachijo Island, must be clariﬁed to prove this hypothesis. Currently, the stock structure of the population migrating to the Hachijo Island remains unclear.
Therefore, the migratory connections between the Hachijo Island and other wintering grounds in the
North Paciﬁc Ocean and feeding grounds at high latitudes must be established based on photo-identiﬁcation and genetic data. To clarify the cause of the sudden appearance of humpback whales aroundthe Hachijo Island, continuous monitoring at a local scale around the island, and at a broader scale, isimperative.
Acknowledgements

The ﬁeld survey was ﬁnancially supported by the Hachijo Town Oﬃce. The authors express their deep gratitude to Hachijo Town government. We would like to thank the citizens and tourists of Hachijo Island and Hachijo Branch, Tokyo Metropolitan Islands Area Research and Development Center of Agriculture, Forestry and Fisheries for providing helpful sighting
information and the Hachijojima Tourist Information Center for summarizing the sighting information. The authors thank Y.
Yamamoto and E. Kono of Japan Broadcasting Corporation (NHK) for enabling the ﬁrst investigation on the Hachijo Island.
The authors would like to thank the Captain of the research vessel, N. Akama. The authors are also grateful to M. Yamaguchi, Y. Kim, and all other researchers of Tokyo University of Marine Science and Technology for their assistance with thepresent surveys. Finally, we would like to express our sincere thanks to the anonymous reviewers.

References
Acebes, J. V., Darling, J. D. and Yamaguchi, M. 2007. Status and distribution of humpback whales (Megaptera novaeangliae) in northern Luzon, Philippines. J. Cetacean Res. Manage. 9: 37–43.
Baker, C. S. and Herman, L. M. 1981. Migration and local movement of humpback whales (Megaptera novaeangliae)
through Hawaiian waters. Can. J. Zool. 59: 460–469. doi: 10.1139/z81-067.
Baker, C. S. and Herman, L. M. 1984. Aggressive behavior between humpback whales (Megaptera novaeangliae) winteringin Hawaiian waters. Can. J. Zool. 62: 1922–1937. doi: 10.1139/z84-282.
Baker, C. S., Herman, L. M., Perry, A., Lawton, W. S., Straley, J. M., Wolman, A. A., Kaufman, G. D., Winn, H. E., Hall, J.
D., Reinke, J. M. and Östman, J. 1986. Migratory movement and population structure of humpback whales (Megaptera
novaeangliae) in the central and eastern North Paciﬁc. Mar. Ecol. Prog. Ser. 31: 105–119. doi: 10.3354/meps031105.
Barlow, J., Calambokidis, J., Falcone, E. A., Baker, C. S., Burdin, M. A., Clapham, P. J., Ford, J. K. B. and Gabriele, C. M.,
Le Duc, R., Mattila, D. K., Quin II T. J., Rojas-Bracho, L., Straley, J. M., Taylor, B. L., Urbán, R. J., Wade, Weller, D.,
Witteveen, B. H. and Yamaguchi, M. 2011. Humpback whale abundance in the North Paciﬁc estimated by photographic capture-recapture with bias correction from simulation studies. Mar. Mamm. Sci. 27: 793–818. doi: 10.1111/j.17487692.2010.00444.x.
Brown, M. R., Corkeron, P. J., Hale, P. T., Schultz, K. W. and Bryden, M. M. 1995. Evidence for a sex-segregated migration in the humpback whale (Megaptera novaeangliae). Proc. R. Soc. B. Biol. Sci. 259: 229–234. doi: 10.1098/
rspb.1995.0034.
Burns, D. 2010. Population characteristics and migratory movements of humpback whales (Megaptera novaeangliae) identiﬁed on their southern migration past Ballina, eastern Australia. PhD thesis, Southern Cross University, Lismore, NSW.
248 pp.
Calambokidis, J., Steiger, G. H., Straley, J. M., Herman, L. M., Cerchio, S., Salden, D. R., Urbán, R, J., Jacobsen, J. K.,
von Ziegesar, O., Balcomb, K. C., Gabriele, C. M., Dahlheim, M. E., Uchida, S., Ellis, G., Miyamura, Y., Ladrón deGuevara, P., Yamaguchi, M., Sato, F., Mizroch, S. A., Schlender, L., Rasmussen, K., Barlow, J. and Quinn, T. J. 2001.
Movements and population structure of humpback whales in the North Paciﬁc. Mar. Mamm. Sci. 17: 769–794. doi:
10.1111/j.1748-7692.2001.tb01298.x.
Cerchio, S. 1998. Estimates of humpback whale abundance oﬀ Kauai, 1989 to 1993: evaluating biases associated with sampling the Hawaiian Islands breeding assemblage. Mar. Ecol. Prog. Ser. 175: 23–34. doi:10.3354/meps175023.
Clapham, P. J. 2000. The humpback whale: Seasonal feeding and breeding in a baleen whale. pp. 173–196. In: Mann, J.,
Tyack, P. L., Connor, R. and Whitehead, H. (eds.) Cetacean Societies: Field Studies of Dolphins and Whales. University of Chicago Press, Chicago, 433 pp.
Clapham, P. J., Baraﬀ, L. S., Carlson, C. A., Christian, M. A., Mattila, D. K., Mayo, C. A., Murphy, M. A. and Pittman, S.
1993. Seasonal occurrence and annual return of humpback whales, Megaptera novaeangliae, in the southern Gulf ofMaine. Can. J. Zool. 71: 440–443. doi: 10.1139/z93-063.
Darling, J. D. and Mori, K. 1993. Recent observations of humpback whales (Megaptera novaeangliae) in Japanese waters oﬀ

Cetacean Popul. Stud. (CPOPS), Full paper
Vol. 3, 2021, 164–174

173

KATSUMATA, HIROSE, NAKAJO, SHIBATA, MURATA, YAMAKOSHI, NAKAMURA AND KATO
Ogasawara and Okinawa. Can. J. Zool. 71: 325–333. doi: 10.1139/z93-045.
Dawbin, W. H. 1966. The seasonal migratory cycle of humpback whales. pp. 145–170. In: Norris, K. S. (ed.) Whales, Dolphins, and Porpoises. University of California Press, Berkeley, 789 pp.
Guidino, C., Llapapasca, M. A., Silva, S., Alcorta, B. and Pacheco, A. S. 2014. Patterns of spatial and temporal distributionof humpback whales at the southern limit of the Southeast Paciﬁc breeding area. PLoS ONE. 9(11): e112627. doi:
10.1371/journal.pone.0112627.
Guzmán, H. M., and Félix, F. 2017. Movements and habitat use by southeast Paciﬁc humpback whales (Megaptera novaeangliae) satellite tracked at two breeding sites. Aquat. Mamm. 43: 139–155. doi: 10.1578/AM.43.2.2017.139.
Hill, M. C., Bradford, A. L., Steel, D., Baker, C. S., Ligon, A. D., Ü, A. C., Acebes, J. M. V., Filatova, O. A., Hakala, S.,
Kobayashi, N., Morimoto, Y., Okabe, H., Okamoto, R., Rivers, J., Sato, T., Titova, O. V., Uyeyama, R. K. and Oleson,
E. M. 2020. Found: a missing breeding ground for endangered western North Paciﬁc humpback whales in the Mariana
Archipelago. Endang. Species Res. 41: 91–103. doi: 10.3354/esr01010.
Johnson, J. H. and Wolman, A. A. 1984. The humpback whale, Megaptera novaeangliae. Mar. Fish. Rev. 46: 30–37.
Katona, S. K. and Whitehead, H. P. 1981. Identifying humpback whales using their natural markings. Polar Rec. 20: 439–
444. doi: 10.1017/S003224740000365X.
Kennedy, A. S., Zerbini, A. N., Vásquez, O. V., Gandilhon, N., Clapham, P. J. and Adam, O. 2014. Local and migratory
movements of humpback whales (Megaptera novaeangliae) satellite-tracked in the North Atlantic Ocean. Can. J. Zool.
92: 9–18. doi: 10.1139/cjz-2013-0161.
Kobayashi, N., Okabe, H., Kawazu, I., Higashi, N., Miyahara, H., Kato, H. and Uchida, S. 2016. Peak mating and breeding
period of the humpback whale (Megaptera novaeangliae) in Okinawa Island, Japan. Open J. Anim. Sci. 6: 169–179.
doi: 10.4236/ojas.2016.63022.
Mate, B. R., Gisiner, R. and Mobley, J. 1998. Local and migratory movements of Hawaiian humpback whales tracked by satellite telemetry. Can. J. Zool. 76: 863–868. doi: 10.1139/z98-008.
Mattila, D. K., Clapham, P. J., Katona, S. K. and Stone, G. S. 1989. Population composition of humpback whales, Megaptera
novaeangliae, on Silver Bank, 1984. Can. J. Zool. 67: 281–285. doi: doi.org/10.1139/z89-041.
Mattila, D. K., Clapham, P. J., Vásquez, O. and Bowman, R.S. 1994. Occurrence, population composition, and habitat use of
humpback whales in Samana Bay, Dominican Republic. Can. J. Zool. 72: 1898–1907. doi: 10.1139/z94-258.
Mobley, J. R., Bauer, G. B. and Herman, L. M. 1999. Changes over a ten-year interval in the distribution and relative abundance of humpback whales (Megaptera novaeangliae) wintering in Hawaiian waters. Aquat. Mamm. 25: 63–72.
Mori, K., Sato, F., Yamaguchi, M., Suganuma, H. and Ueyanagi, S. 1998. Distribution, migration and local movements of
humpback whale (Megaptera novaeangliae) in the adjacent waters of the Ogasawara (Bonin) Islands, Japan. Tokai
University Bulletin. 45: 197–213.
Nishiwaki, M. 1959. Humpback whales in Ryukyuan waters. Sci. Rep. Whales Res. Inst. 14: 49–87.
Payne, R. S. and McVay, S. 1971. Songs of humpback whales. Science. 173: 585–597. doi: 10.1126/science.173.3997.585.
Qiu, B. 2019. Kuroshio and Oyashio Currents. pp. 384–394. In: Cochran, J. K., Bokuniewicz, H. and Yager, P. (eds.) Encyclopedia of Ocean Sciences (3rd Edition). Academic Press, Amsterdam, 4306 pp.
Rasmussen, K., Palacios, D. M., Calambokidis, J., Saborío, M. T., Dalla Rosa, L. D., Secchi, E. R., Steiger, G. H., Allen, J.
M. and Stone, G. S. 2007. Southern Hemisphere humpback whales wintering oﬀ Central America: insights from watertemperature into the longest mammalian migration. Biol. Lett. 3: 302–305. doi: 10.1098/rsbl.2007.0067.
Scheidat, M., Castro, C., Denkinger, J., González, J. and Adelung, D. 2000. A breeding area for humpback whales (Megaptera novaeangliae) oﬀ Ecuador. J. Cetacean Res. Manage. 2: 165–171.
Trudelle, L., Cerchio, S., Zerbini, A. N., Geyer, Y., Mayer, F., Jung, J. L., Hervé, M. R. and Adam, O. 2016. Inﬂuence of environmental parameters on movements and habitat utilization of humpback whales in the Madagascar breeding ground.
R. Soc. Open Sci. 3(12):160616. doi: 10.1098/rsos.160616 .
Tyack, P. and Whitehead, H. 1983. Male competition in large groups of wintering humpback whales. Behaviour. 83: 132–
154. doi: 10.1163/156853982X00067.
Uda, M. 1954. Studies of the relation between the whaling grounds and the hydrographical conditions. Sci. Rep. Whales Res.
Inst. 9: 179–187.
Urbán, R. J. and Aguayo, L. A. 1987. Spatial and seasonal distribution of the humpback whale, Megaptera novaeangliae, inthe Mexican Paciﬁc. Mar. Mamm. Sci. 3: 333–344. doi: 10.1111/j.1748-7692.1987.tb00320.x.
Wedekin, L. L., Neves, M. C., Marcondes, M. C. C., Baracho, C., Rossi-Santos, M. R., Engel, M. H. and Simões-Lopes, P. C.
2010. Site ﬁdelity and movements of humpback whales (Megaptera novaeangliae) on the Brazilian breeding ground,southwestern Atlantic. Mar. Mamm. Sci. 26: 787–802. doi: 10.1111/j.1748-7692.2010.00387.x.

Received: January 26, 2021
Accepted: July 7, 2021
Published online: November 8, 2021

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