HUMPBACK WHALES OBSERVED WITHIN THE
CONTINENTAL SHELF WATERS OF THE
EASTERN BERING SEA
TAKAHISA NEMOTO
Ocean Research Institute, University of Tokyo, Tokyo

Humpback whales, Megaptera novaeangliae, have been protected in more than recent
10 years according to the Regulation of the International Whaling Commission.
The recent observations of humpback whales have been increasing by many sighting surveys (Ohsumi and Masaki, 1973: Herman and Antinoja, 1977: Wolmanand Jurasz, 1977: Christensen, 1977). Especially in the North Pacific, morethan three hundred humpback whales have been observed in the subtropical waters
around Hawaiian Islands (Herman and Antinoja, 1977: Wolman and Jurasz,1977), and Herman and Antinoja (1977) reported about 200-250 animals aroundHawaiian Islands in 1976 but few record has been reported from the summer feeding
ground of the North Pacific.
In the cruise of the Research Vessel Hakuho-lvfaru of the Ocean ResearchInstitute, University of Tokyo, in the Bering Sea in 1975, about 30 humpback
whales were observed in the Alaskan continental shelf off Nunivak Island. On
11 July 1975, Hakuho-Maru was cruising at the position, 58°57'N and 166°00'Win the shelf waters, where school of 5 humpback whales were seen at first at 1230 o'clock noon. Following this school, other three schools of 5 humpback whales
appeared at 12-35, and two schools of 3 humpback whales were seen successively,
while the Hakuho-Maru still cruising to the north-west direction. The position
and moving direction of humpback whales are illustrated in Fig. 1.
These humpback whales have been observed to feed on swarming of euphausiids such as Thysanoessa raschii which distribute in these area of low watertemperature and salinity (Nemoto, 1962: Fukuchi, 1977), or other swarming
fish in this shallow water. There were also many sea bird Puifinus griseus and someRissa triductyla were found around the same waters with humpback whales. Pujfinus
griseus individuals fed actively on plankton and a few Rissa triductyla were flying
about above the water.
Humpback whales have been observed and caught mainly along the shelfwaters of continental shelf and edge of islands shelf (Townsend, 1935: Nishiwaki,1966) in the North Pacific. Humpback whales also congregate around the Aleutian Islands in the summer season where they feed on swarming euphausiids andsome heavy swarms of fish such as Alaskan pollack (Nemoto, 1959). However, it
has been rather rare to be found within the continental shelf, although humpback
whales are considered to be "Ocean and marginal sea denizen" (Nemoto, 1959).
Sometimes humpback whales have been caught within the shelf waters in
Arctic Polar Sea and Davis Straight and Barents Sea of the North Atlantic. Recent
Sci. Rep. Whales Res. Inst.,

No. 30, 1978., 245-247

246

NEMOTOobservation of the humpback whales in the Atlantic shows that rather many humpback whales have been found in Barents Sea along the edge of island shelf (Christensen, 1977). He considered the increase of number of humpback whales seenin the Northeast Atlantic in recent years indicate that the abundancy of this species
is increasing in that area.
The observation of humpback whales in the North Pacific in recent years,
however, shows that they are mainly found in the shelf edge of islands in the midocean in winter time. According to Ohsumi and Masaki, some 59 humpback
whales were found in winter time of the year in 1972 and 1973 in their whale sighting and marking cruise mainly in the waters around Hawaiian Islands (Ohsumi andMasaki, 1973). Wolman and Jurasz (1977) also reported three hundred seventy
three humpback whales in Hawaiian waters, and these large number of sightingsof humpback whales are suggesting that the population of humpback whales c.re.
.
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SIBERIA
ALASKA

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Fig. 1. The position and swimming direction of humpback whales found in theHuakho-Maru cruise in 1975 in the Bering Sea.

On the other hand, sighting of humpback whales in the summer feeding
ground is not so numerous in the North Pacific. Humpback whales have beencaught in the marginal sea such as Okhotsk Sea and Yellow Sea in the former
years, but few observation was recorded in the uppermost Bristol Bay according
to the fisheries peoples. One humpback whale was reported to be entangled indeep sea cable in the Alaskan waters (Heezen, 1957 by personal communicationfrom Gilmore 1955), but precise information was not given. Considering thediving depth of humpback whales is shallower than the sperm whales, this whalemight be entangled in the shelf waters along the Alaskan continent.
The finding of summer feeding schools of humpback whales in shelf waters
Sci. Rep. Whales Res. Inst.,.No. 30, 1978.

HUMPBACK WHALES IN THE BERING SEA

247

in the North Pacific is also considered as the indication of the recovery of the number of this species too.
Herman and Antinoja (1977) find only 35% of whales have all black pectoral
fins and other whales are white pectoral fins. They consider that Hawaiian humpback whales are different population from those observed in the feeding areas nearsoutheast Alaska and even from whales near Kamtchatka in the upper western
Pacific.
Wolman and Jurasz (1977) also consider that humpback whales seen in
Hawaiian waters by their vessel census in 1976 possibly differ from those distributing
in the Southeastern Alaska. The most distinctive feature of Hawaiian humpback
is alsD white dorsal flipper. One or two humpback whales observed to jump in
the continental shelf waters of Alaskan continent in our cruise in 1975 do not havewhite dorsal flipper, however, it needs more observation on this point to separate
these two groups of humpback whales. Another marking results of humpback
whales also show that some humpback whales hit in the Eastern Alaskan Islands
were captured in the Okinawa Island (Nishiwaki, 1966). But, it is not conclusive,
because no whaling had been operated in Hawaiian waters at that time.
REFERENCESCHRISTENSEN, I., 1977. Observation of whales in the North Atlantic. Rep. int. Whal Commn, 27: 388-399.
HERMAN, L. M. and R. C. ANTINOJA, 1977. Humpback whales in the Hawaiian breeding waters: Population and pod characteristics. Sci. Rep. Whales Res. Inst., 29: 59-85.
HEEZEN, B. C., 1957. Whales entangled in deep sea cables. Deep Sea Res., 4: 105-115.
NEMOTO, T., 1959. Food of baleen whales with reference to whale movement. Sci. Rep. Whales Res. Inst.,
14: 149-290.
NEMOTo, T., 1962. Distribution of five main euphausiids in the Bering and the northern part of the North
Pacific. J. Oceanogr. Soc. Japan 20th Aniv., Vol., 615-627.
NISHIWAKI, M., 1960. Ryukuan humpback whaling in 1960. Sci. Rep. Whales Res. Inst., 15: 1-16.
N1sHIWAKI, M., 1966. Distribution and migration of the larger Cetaceans in the North Pacific as shown byJapanese whaling results. 171-191 pp. In: K. Nouris (ed.) Whales, Dophins and Porpoises. Univ. Calif.
Press.
0HSUMI, S. and Y. MASAKI, 1973. Whale sighting and whale marking in the North Pacific in winter. 25thI\'VC Document for Scientific Committee.
TOWNSEND, C. H., 1935. The distribution of certain whales as shown by logbook records of American
whaleships. :(oologica N.Y., 19 (1): 3-50.
WOLMAN, A. A. and C. M. JuRASz, 1977. Humpback whales in Hawaii: Vessel Census, 1976. Marine
Fisheries Review, 39 (7): 1-5.

Sci. Rep. Whales Res. Inst.,
No. 30, 1978.