Title
Review of the conservation status and protected areas for Ganges River Dolphins Platanista Gangetica and Irrawaddy Dolphins Orcaella Brevirostris in the river systems of Bangladesh
Author(s)
Smith, B.D.;Ahmed, B.;Alom, Z.;Ahmad, I.U.;Mowgli, R.M.;Mansur, E.F.
Published
2010
Abstract
Little information is available on the range-wide status of
the Ganges River dolphin in Bangladesh but anecdotal
reports and personal observations suggest that the
species is still fairly widespread in most major rivers and
their tributaries. Sighting rates include 0.13 groups/km
(mean group size = 1.8) in the Jamuna River, 0.08
groups/km (mean group size = 3.8) in the Kushiyara River,
and 0.76 dolphins/km in the Karnaphuli and Sangu system
in southeast Bangladesh, with a higher encounter rate of
1.36 dolphins/km recorded in the lower Sangu. The status
of freshwater dolphins is best known in the Sundarbans
mangrove forest where a Huggins conditional likelihood
model of concurrent counts made by independent teams
generated population estimates of 225 Ganges River
dolphins (CV = 12.7%) and 451 Irrawaddy dolphins (CV =
9.6%). Fisheries interactions represent the greatest
immediate threat to freshwater dolphins in Bangladesh.
Directed hunting of Ganges River dolphins for their oil has
been reported to supply oil for medicinal purposes and as
a fish attractant. A large proportion of the dolphin
carcasses used for oil are obtained from animals that
become entangled in nylon gillnets and are then killed by
local fishermen. Riverine and estuarine waters in
Bangladesh are already experiencing the ecological
impacts of declining freshwater supplies and climate
change. The dependence of Ganges and Irrawaddy
dolphins on abundant freshwater flow makes them
particularly vulnerable to habitat loss due to upstream
water abstraction and sea-level rise. Three waterway
segments have been identified in the Sundarbans for focal
protection using a “hotspot” scoring system of encounter
rates recorded by captains of three nature tourism
vessels. A proposed protected area network including
these segments will provide a platform for understanding
the ecological effects of declining freshwater supplies and
climate change and a basis for developing adaptive
management responses that benefit both fishermen and
freshwater dolphins. The proposed network in the
Sundarbans covers only a small fraction of the total
freshwater dolphin habitat in Bangladesh. A priority area
for future consideration as a protected area is the lower
Sangu River.
Access Full Text
A full-text copy of this article may be available. Please email the WCS Library to request.
![]()
Back
PUB14764