Taxon name
Orcaella brevirostris
(Owen, 1866)
Uploaded by
National Red List Database
Taxonomic information
Scientific name
Orcaella brevirostris
(Owen, 1866)
Common name(s)
Irrawaddy Dolphin, Iraboti, Hiraboti, Shushuk, Shush, Hush, Hochchum
Assessed taxon level
Species
Higher level taxonomic groupings
Vertebrates
Mammals
Species authority
(Owen, 1866)
Taxonomic notes and synonyms listed
Dolphins of the genus Orcaella were recently split into two species, the Irrawaddy Dolphin Orcaella brevirostris and the Snub-fin Dolphin O. heinsohni (Beasley et al. 2002, 2005) as quoted in Reeves et al. 2008. Of these, Orcaella brevirostris occurs in B
Orca (Orcaella) brevirostris Owen, 1866; Orcaella brevirostris brevirostris Ellerman & Morrison-Scott, 1951; Orcaella brevirostris fluminalis Ellerman & Morrison-Scott, 1951; Orcaella fluminalis Gray, 1871; Orcella brevirostris Anderson, 1871; Orcella flu
Location and scope
Specific locality or subnational name or regional name
Bangladesh
Scope (of the Assessment)
National
Countries included within the scope of the assessment
Does the assessment cover a marine EEZ area(s)?
Not_assigned
Conservation Status
Assessed as
Near Threatened
Criteria system used
IUCN
(see Assessment details)
Assessment rationale/justification
The species is mostly found in freshwater affected coastal waters and waterways of the Sundarbans in a large range. The Extent of Occurrence and the Area of Occupancy of this species is much higher than the threshold level. The population size is 451 individuals (3.4% calves) in the Sundarbans (Smith et al. 2006) and 5,383 individuals in coastal waters in the Bay of Bengal (Smith et al. 2008). It does not fulfill any of the criteria to qualify threatened categories but based on its existing threats, it has been categorized as Near Threatened.
Assessment details
Assessors/contributors/reviewers listed
Md. Zahangir Alom
Criteria system used
IUCN
Reference for methods given
IUCN (2012) IUCN Red List Categories and Criteria: Version 3.1. Second edition. Gland, Switzerland and Cambridge, UK: IUCN. iv + 32pp; IUCN (2012) Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN. iii + 41pp.
URL (link) of redlist assessment or publication
http://iucnredlistbd.org/
Further information
Endemism (according to assessment)
Taxon distribution as listed in assessment
Reeves et al. 2008 described its distribution in warm coastal waters and rivers from the Bay of Bengal to western Sulawesi, Indonesia. It occurs in Bangladesh, Brunei Darussalam, Cambodia, India, Indonesia, Lao PDR, Malaysia, Myanmar, Philippines, Singapore, Thailand, Viet Nam (Reeves et al. 2008). Waterways of the Sundarbans mangrove forest and fresh water affected coastal waters in the Bay of Bengal.
Is there a map available in assessment?
Yes, in the publication/on website
Habitat and systems
Ecological system type
Habitat
Habitat details as listed in assessment
It generally occurrs in small group of 1-6 animals in the Sundarbans and 1-10 animals in the coastal water, and they are very social. Inconspicuous surfacing, only show part of the back. Leaps are infrequent. Average dive duration is 115.3 second. Turbid fresh and brackish waters in the waterways of the Sundarbans and freshwater affected coastal waters in the Bay of Bengal. They prefer water depth from 2.7-16.0 meter and salinity from 7.0-34.0 ppt (Smith et al. 2008).
History
Critically Endangered in Bangladesh (IUCN Bangladesh 2000).
Publication
IUCN Bangladesh. 2015. Red List of Bangladesh Volume 2: Mammals. IUCN, International Union for Conservation of Nature, Bangladesh Country Office, Dhaka, Bangladesh, pp. xvi+232
