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

Brahmaputra-Megna, and Karnaphuli-Sangu river systems,
the Platanista river dolphins have declined in abundance
and in the extent of their range. These cetaceans must
compete with humans for shrinking water resources. Largescale
engineering projects that give people hope for
economic development and relief from flood and famine
pose dire threats to river cetaceans and other aquatic wildlife.
Freshwater populations of Irrawaddy dolphins are also
threatened by development projects in the Mekong river
system of Vietnam, Cambodia, and Laos, and probably also
in the Ayeyarwady (formerly Irrawaddy) River of Myanmar
and the Mahakam River of Indonesia. Freshwater cetaceans
are also threatened by the enormous pollutant loads carried
in Asian waterways (Dudgeon 1992), and by destructive
fishing activities, which result in high mortality from bycatch
and reduced availability of prey. These animals are
perhaps more vulnerable to these threats, in comparison to
marine cetaceans, because their habitat requirements often
place them in areas where human activities are most intense
(Smith and Smith 1998).
Little is known about the status of most coastal cetacean
populations in Asia. In many areas, even the most basic
information, such as what species are present, is lacking.
Particular problems relate to distinct populations (e.g.,
dwarf spinner dolphins) and poorly documented species
(e.g., pygmy Bryde’s whale). Recent projects in Vietnam
(Smith et al. 1997b; Andersen and Kinze 2000), Thailand
(Andersen and Kinze 1999), Myanmar (Smith et al. 1997a),
Indonesia (Rudolph et al. 1997), and the Philippines and
Malaysia (Dolar et al. 1997) have revealed diverse inshore
cetacean faunas, but also serious threats, including fishery
bycatch, deliberate killing, and possibly reduced prey due to
overfishing. Throughout the continent, there is an urgent
need for better information on the status of species and
populations, and for the development of local expertise to
help devise, advocate, and implement conservation programs
(Perrin et al. 1996). Information is particularly lacking
for western Asia (e.g., Iran and the Arabian peninsula),
and the absence of projects for this region represents a
significant gap that should be filled in subsequent action
plans.
Projects
1. Monitor and evaluate ongoing threats to the
Irrawaddy dolphins in the Mahakam River of
Indonesia
The Critically Endangered Irrawaddy dolphins in the
Mahakam River of East Kalimantan range in the mainstem
from about 180km to 600km upstream of the mouth, seasonally
entering several tributary rivers and lakes (Kreb
2002). The total population was estimated to number fewer
than 50 individuals based upon eight surveys of their entire
range conducted in 1999 and 2000. The dolphins were found
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primarily in deep pools located near confluences and meanders,
which are also primary fishing grounds and subject
to intensive motorized vessel traffic. Between 1997 and
1999, 16 deaths were recorded (ten from gillnet entanglement,
three probably from vessel strikes, and three
deliberate)(D. Kreb, pers. comm.). From 1997 to 1998, at
least seven dolphins were also illegally live-captured from
the river and taken to oceanaria, and plans exist to capture
more animals for a new oceanarium to be built in
Tenggarong (D. Kreb, pers. comm.). Intensive fishing with
gillnets, electricity, and poison, and the accidental introduction
of an exotic piscivorous fish, locally known as ikan
toman, may have depleted the dolphins’ prey (D. Kreb, pers.
comm.). The high density of gillnets used in Semayang and
Melintang lakes causes physical obstruction to dolphin
movements, thereby reducing available habitat. This problem,
together with sedimentation caused by devegetation of
the surrounding shorelines, has probably resulted in the
elimination of these lakes as primary habitat as reported by
Tas’an and Leatherwood (1984). Leaks from dams in the
upper reaches that retain mining wastes, including mercury
and cyanide, occurred in 1997 and resulted in a massive fish
kill (D. Kreb, pers. comm.).
An ongoing program, started in 1997 and conducted jointly
by the University of Amsterdam and the East Kalimantan
Nature Conservation Authority (Balai Konservasi Sumber
Daya Alam Kal), has involved extensive monitoring of the
Mahakam dolphins. This program should be continued and
expanded to include toxicological and genetic analyses of
tissues obtained from stranded or incidentally killed dolphins,
investigations of factors that continue to degrade
dolphin habitat, and further efforts to monitor abundance.
The involvement of local scientists is vital. Because of this
population’s Critically Endangered status, every effort
should be made to prevent any further catches (including
live-capture) and improve the quality of the riverine environment
(Chapter 6).
2. Investigate the status of cetaceans in the
Indonesian archipelago
Indonesia is a huge country, with tens of thousands of islands
and extensive, varied marine habitats (Figure 25). Indonesia’s
marine waters harbor a greater variety of species than any area
of comparable size in the world (Gray 1997). Species of
particular conservation interest in Indonesian near-shore
waters include the Irrawaddy dolphin, Indo-Pacific humpbacked
dolphin, Indo-Pacific bottlenose dolphin, finless porpoise,
and small-type (pygmy) Bryde’s whale. Relatively little
is known, however, about the abundance and distribution of
cetaceans in the region (Rudolph et al. 1997). Research has
been limited primarily to the two whaling villages of Lamalera
and Lamakera on the islands of Lembata and Solor, respectively
(Barnes 1991, 1996); the small freshwater population
of Irrawaddy dolphins in the Mahakam River (Project 1,
above); waters near Manado, at the northern tip of Sulawesi