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

around the world. There are estimated to be some 150,000 in
the eastern tropical Pacific (Wade and Gerrodette 1993) and
about 850 in the northern Gulf of Mexico (Waring et al.
2001). Rough-toothed dolphins are notorious for stealing
bait and catch from fishing lines, making them unpopular
with many recreational and commercial fishermen.
Common bottlenose dolphin, Tursiops
truncatus
The common bottlenose dolphin occurs in all tropical and
temperate waters, including the littoral zone, inshore lagoons,
estuaries, and bays, and the offshore realm (Wells
and Scott 1999; Reynolds et al. 2000). In some areas where
the species has been studied closely, offshore animals are
distinguishable from coastal animals on the basis of morphology
and ecological markers (e.g., Mead and Potter 1995).
Moreover, the two forms in the North Atlantic have fixed
genetic differences and, therefore, eventually may be assigned
to different species (Leduc and Curry 1997; Hoelzel
et al. 1998). Coastal and island-centered populations are
especially vulnerable to hunting, incidental catch, and habitat
degradation (Curry and Smith 1997 for a review).
Acute conservation problems are known or suspected in at
least: (a) the Mediterranean and Black seas, where past
hunting, incidental catches, and environmental degradation
have caused population declines (IWC 1992); (b) Sri Lanka,
where this is one of the principal species taken by harpoon
and gillnet for fishbait and human food (Leatherwood and
Reeves 1989); (c) Peru (and possibly Chile), where both
directed (mainly the inshore form) and incidental (mainly
the offshore form) killing occurs (Read et al. 1988; Van
Waerebeek et al. 1990; K. Van Waerebeek, pers. comm.);
(d) Taiwan, where there was a recent drive and harpoon
fishery on the Penghu Islands (Hammond and Leatherwood
1984; Perrin 1988) and where exploitation for meat on the
east coast apparently continues (Wang et al. 1999); and (e)
Japan, where large numbers (e.g., nearly 3400 in 1980) have
been taken in some years in the drive and harpoon fisheries
(Miyazaki 1983) and where more than 4000 were culled for
fishery protection at Iki Island from 1977 to 1982 (Kasuya
1985). The culling off northern Kyushu has declined in
recent years, but the take in drive and hand-harpoon fisheries
along the Pacific coast has increased since the early
1980s (IWC 1992; Kishiro and Kasuya 1993). Tens of
bottlenose dolphins are killed in some years in pilot whale
drives in the Faroe Islands. On the east coast of the United
States and in the northern Gulf of Mexico, large-scale dieoffs
of bottlenose dolphins have occurred, but the causes are
not fully understood (Geraci et al. 1999).
The common bottlenose dolphin is the species most often
held in captivity; hence, problems concerning the welfare of
cetaceans in captivity often center on it. Unregulated livecapture
fisheries can contribute to the depletion of wild
populations. A regime is in place for managing live-capture
operations in the south-eastern United States (Scott 1990),
but captures in Cuba, mainland Latin America, and elsewhere
are poorly documented and often unregulated
(Chapter 5, Project 38).
Indo-Pacific bottlenose dolphin,
Tursiops aduncus
This coastal, mainly tropical and subtropical species has
only recently been accorded full species status. Much of the
literature on bottlenose dolphins (including Reeves and
Leatherwood 1994a) makes no distinction between the common
and Indo-Pacific species. The Indo-Pacific bottlenose
dolphin is known from southern Japan southward to
Australia and along the entire rim of the Indian Ocean
(including the Indo-Malay archipelago) to Cape Agulhas in
south-eastern Africa, including the Red Sea. Although not
considered to be endangered as a species, its very near-shore
distribution makes this dolphin vulnerable to environmental
degradation, direct exploitation, and fishery conflicts (Curry
and Smith 1997; Wells and Scott 1999). In the recent past,
large numbers were killed in a Taiwanese drive fishery. Although
this deliberate killing is now prohibited in Taiwan,
gillnet mortality continues to be a problem there and
throughout most of the species’ range. Large numbers of
Indo-Pacific bottlenose dolphins died in a Taiwanese
driftnet fishery in the Arafura Sea, off north-western
Australia, during the early 1980s (Harwood and Hembree
1987). In South Africa and Australia, Indo-Pacific bottlenose
dolphins also suffer considerable mortality in the
large-mesh nets set to protect bathers from sharks (cf.
Peddemors 1999). As a preferred species in captive displays,
there is substantial, and growing, demand for this dolphin
in the expanding oceanarium trade throughout southern
Asia (Wang et al. 1999).
4.6 Monodontids
White whale or Beluga,
Delphinapterus leucas
This circumpolar species was formerly abundant throughout
the Arctic and Subarctic. There may still be in the order of
150,000 white whales in total (IWC 2000a; NAMMCO
2000b), but many of the 29 stocks provisionally recognized
by the IWC Scientific Committee have been seriously reduced
by hunting. Even these depleted populations continue
to be hunted and are therefore at risk of being extirpated.
They include the belugas in Cook Inlet, Alaska (c.350
individuals); Ungava Bay, Canada (