Marine Resources Assessment for the Marianas Operating ... - SPREP

AUGUST 2005 FINAL REPORT
whale sightings were very rare in the eastern North Pacific (Scarff 1986; Brownell et al. 2001). Recent
summer sightings of right whales in the eastern Bering Sea represent the first reliable consistent
observations in this area since the 1960s (Tynan et al. 2001; LeDuc 2001). Right whales were
probably never common along the west coast of North America (Scarff 1986; Brownell et al. 2001).
Historical whaling records provide virtually the only information on North Pacific right whale
distribution. During the summer, whales were found in the Gulf of Alaska, along both coasts of the
Kamchatka Peninsula, the southeastern Bering Sea, and in the Okhotsk Sea (Clapham et al. 2004).
The whales were most widely dispersed in fall and spring, with whales occurring in mid-ocean waters
and extending from the Sea of Japan to the eastern Bering Sea. In winter, right whales were found in
the Ryukyu Islands (south of Kyushu, Japan), the Bonin Islands, the Yellow Sea, and the Sea of
Japan. Historical concentrations of sightings in the Bering Sea together with the recent sightings
indicate that this region remains an important summer habitat for eastern North Pacific right whales
(Tynan et al. 2001). Scarff (1986) hypothesized those right whales that summer in the eastern North
Pacific mate, calve, and overwinter in the mid-Pacific or in the western North Pacific.
Current distribution patterns and migration routes of these whales are not known (Scarff 1986; NMFS
2002). The extent to which right whales in the eastern North Pacific engage in north-south migrations
is unknown (Scarff 1986). There is very little information on the winter distribution of right whales in
the eastern North Pacific. The location of calving grounds for the eastern North Pacific population is
unknown (Scarff 1986; NMFS 2002; Clapham et al. 2004). There are no records of newborn or very
young calves in the eastern North Pacific, which appears to reflect a true absence of coastal calving
grounds at least within historic times (Scarff 1986). Neither the west coast of North America nor the
Hawaiian Islands constituted a major calving ground for right whales within the last 200 years (Scarff
1986). No coastal calving grounds for right whales have been found in the western North Pacific
either (Scarff 1986). Mid-ocean whaling records of right whales in the winter suggest that right whales
may have wintered and calved far offshore in the Pacific (Scarff 1986, 1991; Clapham et al. 2004).
Such pelagic calving would appear to be inconsistent with the records of nearshore calving grounds
in other locales for the other right whale species.
Feeding grounds for North Pacific right whales are also poorly known. Based on historical whaling
records and some recent sightings, the principal feeding grounds were most likely in the Sea of
Okhotsk, central and eastern Bering Sea, and Gulf of Alaska. All of these feeding areas are much
further offshore than the well-studied North Atlantic habitats. The eastern Bering Sea is used for
foraging (NMFS 2002). Right whales in the eastern Pacific have been observed each summer since
1996 in the eastern Bering Sea in roughly the same location (Goddard and Rugh 1998; Moore et al.
2000; Tynan et al. 2001).
Right whales can make long-range movements. For example, radio-tagged North Atlantic right
whales make extensive movements, traveling into waters with bottom depths as great as 4,200 m
(Knowlton et al. 1992; Mate et al. 1997). One individually-identified right whale was documented to
make a two-way trans-Atlantic migration from the eastern coast of the U.S. to a location in northern
Norway (Jacobsen et al. 2004). Clapham et al. (2004) noted seasonal movements in their review of
North Pacific right whale records: a general northward migration in spring from lower latitudes (March
through May); major concentrations above 40°N in summer (May through August); sightings diminish
and occur further south in fall (September through October); few animals are recorded anywhere
during the winter (November through February).
Information Specific to the Marianas MRA Study Area—There are no confirmed records of the
North Pacific right whale in the Micronesia region; however, Reeves et al. (1999) noted the
remote possibility of encountering this species here. The highly endangered status of this species
necessitates an extremely conservative determination of its occurrence in the Marianas study
area (Jefferson personal communication). There is a low or unknown occurrence of right whales
from the coastline to seaward of the Marianas study area (Figure B-3). Sightings have been
made both in waters on and seaward of the shelf off the Hawaiian Islands (Herman et al. 1980;
Rowntree et al. 1980; Salden and Mickelsen 1999); the predicted occurrence for the Marianas
3-9