Dolphins, Whales and Porpoises: 2002-2010 Conservation - IUCN

ecovery in the eastern and central North Pacific (Brownell
et al. 2001).
In the absence of direct hunts, the most serious continuing
threats to right whales in the Northern Hemisphere are
ship-strikes and entanglement in fishing gear. More than
half of the living right whales in the western North Atlantic
have experienced at least one ship-strike or net entanglement,
and at least a third of the deaths in this population each
year are thought to be directly linked to human activities (cf.
Kraus 1990; Kenney and Kraus 1993; IWC 2001b). Deaths
from entanglement in fishing gear have also been documented
recently in the western North Pacific (Brownell et
al. 2001).
Unlike their relatives in the Northern Hemisphere, several
populations of southern right whales (E. australis) have
shown evidence of strong recovery (Bannister 2001; Best et
al. 2001; Cooke et al. 2001). Although numbers are still
small in absolute terms, totaling only about 7000 animals
(IWC 2001b), there is reason to expect that continued protection
will allow substantial recovery of at least some of
these populations (Best 1993). A major factor delaying
recovery was the illegal and unreported killing of more than
3300 southern right whales by the Soviet Union between
1951/1952 and 1971/1972 (Tormosov et al. 1998).
4.2 Rorquals
Common minke whale, Balaenoptera
acutorostrata
Only within the last decade has the species distinction between
the common minke whale and the Antarctic minke
whale (Balaenoptera bonaerensis) become widely understood
and accepted. The present convention is to regard B.
acutorostrata as consisting of two, and possibly three, subspecies:
the North Atlantic population, B. a. acutorostrata;
the North Pacific population, B. a. scammoni (= davidsoni);
and the “dwarf” minke whale, B. a. subsp., which is found in
parts of the Southern Ocean (Rice 1998). Both the North
Atlantic and North Pacific populations are widely distributed
and relatively abundant. The dwarf form is best
known from wintering areas off eastern Australia, New
Caledonia, southern Africa, and Brazil, but it apparently
moves to high latitudes (at least 65°S) in summer.
There are thought to be approximately 120,000 minke
whales in the north-eastern North Atlantic, but this stock has
been reduced by whaling to an estimated 45–70% of its
pre-exploitation level of abundance and it continues to be
hunted commercially by Norway (c. > 600 per year). There
are an estimated 60,000 minke whales in the central North
Atlantic, with no evidence of a significant decline. The
commercial hunt for minke whales in Icelandic waters ended
in 1986 and has yet to resume, despite repeated press
reports that resumption is imminent. Greenland hunters kill
at least 150 minke whales each year under an IWC quota.
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There is no overall estimate of abundance in the western
North Atlantic, but at least a few thousand minke whales are
present along the east coast of North America.
In the western North Pacific, two minke whale stocks are
recognized by the IWC. One of them, called J-stock, inhabits
the Sea of Japan, Yellow Sea, and East China Sea
(Goto and Pastene 1997). The other, called O-stock, inhabits
the Sea of Okhotsk and Pacific waters. J-stock is thought to
have declined by more than 50% because of intensive whaling
in the past by China, Taiwan, the Republic of Korea, and
Japan. O-stock is also well below its pre-exploitation abundance
but is less depleted than J-stock. Japan continues to
hunt North Pacific minke whales, taking at least 100 per
year under a national permit for scientific research. At least
a few tens of minke whales are also taken annually as a
fishery bycatch in South Korean waters (Kim 1999) and in
set nets in Japan (Tobayama et al. 1992). A substantial
proportion of the minke whales sold in Japanese markets are
from J-stock (Dalebout et al. 2002a). It is uncertain to what
extent these come from the “scientific” hunt, fishery bycatch,
or natural strandings, but the scale of removals from
J-stock is sufficient to cause serious concern for this population’s
long-term survival (Baker et al. 2000).
The common minke whale’s classification as Near
Threatened (under the 1996 categories and criteria) was
based on the major declines in some stocks (e.g., J-stock in
the western North Pacific) which, when aggregated, could
have meant that there was an overall decline of at least 20%,
the threshold for listing species as Vulnerable under the
1996 criteria. Although the continuing threat of commercial
and “scientific” whaling is generally well known, the incidental
mortality of common minke whales in fish nets and
traps, which occurs throughout their range (e.g., Tobayama
et al. 1992; Van Waerebeek et al. 1999a), has been given
little attention. Such mortality should be taken into account
in assessments to ensure that whaling quotas are appropriately
risk-averse (e.g., IWC 1998, p.133). Also, since the
meat and blubber of “by-caught” whales has commercial
value in Japan and the Republic of Korea, there is an incentive
to set gear deliberately in places where it is likely to
catch minke whales, or to“drive” whales toward the nets.
This issue has been a major source of controversy within the
IWC’s Scientific Committee.
Relatively little is known about the conservation status of
the dwarf form. Dwarf minke whales are the objects of
attraction for a unique tour enterprise on the Northern Great
Barrier Reef, Australia, in which people observe the whales
underwater (Birtles and Arnold 2000).
Antarctic minke whale, Balaenoptera
bonaerensis
The Antarctic minke whale may be the most abundant
baleen whale species today, with a total population of
several hundred thousand. It occurs in highest densities in
the Antarctic during the summer feeding season. The winter