Irrawaddy dolphin
Encyclopedia
The Irrawaddy dolphin is a euryhaline
species of oceanic dolphin
found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal
and Southeast Asia
.
in 1866 based on a specimen found in 1852, in the harbour of Visakhapatnam
on the east coast of India
. It is one of two species in its genus. It has sometimes been listed variously in a family containing just itself and in Monodontidae
and in Delphinapteridae. There is now widespread agreement to list it in the Delphinidae family.
Genetically, the Irrawaddy dolphin is closely related to the killer whale (orca). The species name brevirostris comes from the Latin
meaning short-beaked. In 2005, genetic analysis showed the Australian snubfin dolphin
found at the coast of northern Australia
forms a second species in the Orcaella genus.
Overall, the dolphins' color is grey to dark slate blue, paler underneath, with no distinctive pattern. The dorsal fin is small and rounded behind the middle of the back. The forehead is high and rounded; the beak is lacking. The flippers are broad and rounded. The species found in Borneo
, the finless porpoise
, Neophocaena phocaenoides, is similar and has no back fin; the humpback dolphin
, Sausa chinensis, is larger, has a longer beak and a larger dorsal fin.
The several common names for O. brevirostris include: English
: Irrawaddy dolphin, local Chilika dialect: baslnyya magar or bhuasuni magar (oil yielding dolphin), Oriya
: khem and khera, French
: orcelle, Spanish
: delfín del Irrawaddy, German
: Irrawadi Delphin, Burmese
: labai, Indonesia
: pesut, Malay
: lumbalumba, Khmer
: ផ្សោត ph’sout , Lao
: pha’ka and Filipino
: lampasut. In Thai
, one of its names is pla loma hua bat, because its rounded head is thought to resemble the shape of a Buddhist monk's bowl, a hua bat.
. They have a large melon
and a blunt, rounded head, and the beak is indistinct. The dorsal fin
, located about two-thirds posterior along the back, is short, blunt and triangular. The flippers are long and broad. It is lightly coloured all over, but slightly more white on the underside than the back. Adult weight exceeds 130 kg (286.6 lb) and length is 2.3 m (7.5 ft) m at full maturity. Maximum recorded length is 2.75 m (9 ft) of a male from Thailand.
. Bony fish and fish eggs, cephalopods, and crustaceans are taken as food. Observations of captive animals indicate food may be taken into the mouth by suction. Irrawaddy dolphins sometimes spit streams of water, sometimes while spyhopping, during feeding, apparently to expel water ingested during fish capture or possibly to herd fish. Some Irrawaddy dolphins kept in captivity have been trained to do spyhopping on command. The Irrawaddy dolphin is a slow swimmer, but swimming speeds of 20–25 km/hour were reported when dolphins were being chased in a boat.
It surfaces in a rolling fashion and lifts its tail fluke clear of the water only for a deep dive. Deep dive times range from 70–150 seconds to 12 minutes. When 277 group dives were timed (time of disappearance of last dolphin in group to emergence of first dolphin in the group) in Laos
, mean duration was 115.3 seconds with a range of 19 seconds to 7.18 minutes. They make only occasional low leaps and never bow-ride. Groups of fewer than six individuals are most common, but sometimes up to 15 dolphins are seen together.
Interspecific competition
has been observed when Orcaella was forced inshore and excluded by more specialised dolphins. When captive humpback dolphins (Sonsa chinensis) and Irrawaddy dolphins were held together, repotedly the Irrawaddy dolphins were frequently chased and confined to a small portion of the tank by the dominant humpbacks. In Chilika Lake, local fishers say when Irrawaddy dolphins and bottlenose dolphins meet in the outer channel, the former get frightened and are forced to return toward the lake.
Although sometimes called the Irrawaddy river dolphin, it is not a true river dolphin
, but an oceanic dolphin
that lives in brackish water
near coasts, river mouths and in estuaries. It has established subpopulations in freshwater rivers, including the Ganges and the Mekong
, as well as the Irrawaddy River
from which it takes its name. Its range extends from the Bay of Bengal
to New Guinea
and the Philippines
.
It is often seen in estuaries and bays in Borneo
Island, with sightings from Sandakan
in Sabah
, Malaysia, to most parts of Brunei
and Sarawak
, Malaysia. A specimen was collected at Mahakam River
in East Kalimantan
.
No range-wide survey has been conducted for this vulnerable species; however, the worldwide population appears to be over 7,000, with over 90% occurring in Bangladesh
. Populations outside Bangladesh and India are classified as critically endangered
. Known subpopulations of Irrawaddy dolphins are found in eight places, listed here in order of population, including conservation status
.
In Burma, in the upper reaches of the Ayeyawady River, Irrawaddy dolphins drive fish towards fishers using cast net
s in response to acoustic signals from them. In return, the dolphins are rewarded with some of the fishers' by-catch
. Historically, Irrawaddy River fishers claimed particular dolphins were associated with individual fishing villages and chased fish into their nets. An 1879 report indicated legal claims were frequently brought into native courts by fishers to recover a share of the fish from the nets of a rival fisher which the plaintiff's dolphin was claimed to have helped fill.
Irrawaddy dolphins are more susceptible to human conflict than most other dolphins who live further out in the ocean. Drowning in gillnet
s is the main threat to them throughout their range. The majority of reported dolphin deaths in all subpopulations is due to accidental capture and drowning in gillnets and dragnet
s, and in the Philippines, bottom-set crabnets. In Burma, electrofishing
, gold mining
and dam building are also serious and continuing threats. Though most fishers are sympathetic to the dolphins' plight, it is difficult for them to abandon their traditional livelihood.
In several Asian countries, Irrawaddy dolphins have been captured and trained to perform in public aquarium
s. Their charismatic appearance and unique behaviours, including spitting water, spyhopping and fluke-slapping, make them very popular for shows in dolphinarium
s. The commercial motivation for using this dolphin species is high because it can live in freshwater tanks and the high cost of marine aquarium
systems is avoided. The region within and near the species’ range has developed economically, and theme parks, casinos and other entertainment venues that include dolphin shows has increased. In 2002, there were more than 80 dolphinariums in at least nine Asian countries
Collateral deaths
of dolphins due to blast fishing
were once common in Vietnam
and Thailand
. In the past, the most direct threat was killing them for their oil.
The IUCN lists five of the seven subpopulations as critically endangered
, primarily due to drowning in fish nets. For example, the Malampaya population, first discovered and described in 1986, at the time consisted of 77 individuals. Due to anthropogenic activities, this number dwindled to 47 dolphins in 2007.
International efforts
International protection against hunting and trade is provided by the International Union for Conservation of Nature (IUCN) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Enforcement, though, is the responsibility of individual countries.
These dolphins are classified by the IUCN as a critically endangered species in Laos, Malaysia, Burma, Philippines, and Thailand, and a vulnerable species
in Bangladesh and India. They are thus are legally protected from hunting; however, enforcement may be poor along thousands of miles of coast line. In 2004, CITES transferred the Irrawaddy dolphin from Appendix II to Appendix I, which forbids all commercial trade in species that are threatened with extinction.
The UNEP-CMS
Action Plan for the Conservation of Freshwater Populations of Irrawaddy dolphins notes that multiple-use protected areas will play a key role for conserving freshwater populations. Protected areas in fresh water could be a particularly effective conservation tool and can facilitate management, due to the fidelity of the species to relatively circumscribed areas. The Action Plan provides details on strategies for mitigating by-catch
that includes:
The Irrawaddy dolphin is listed on both Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS
). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them, as well on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The species is also covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).
National efforts
Several national efforts are resulting in the reduction of threats to local Irrawaddy dolphin subpopulations:
Bangladesh
Portions of Irrawaddy dolphin habitat in the Sundarbans
mangrove forest of Bangladesh are included within 139699 ha (539 sq mi) of three wildlife sanctuaries, which are part of the Sunderbans World Heritage Site. The Wildlife Conservation Society
is working with the Bangladesh Ministry of Environment and Forests to create protected areas for the 6000 remaining dolphins
Cambodia
The Cambodian Department of Fisheries has drafted a Royal Decree for protection of Irrawaddy dolphins in the Mekong River, which includes the designation of eight protected areas, totaling 5721 ha (22.1 sq mi), in a 190 km (118.1 mi) segment of the river above Kratie. The establishment of community-managed deep water fish conservation zones with government support may represent the best opportunity for reducing dry-season dolphin mortality from large-meshed gillnet entanglement. Efforts to establish protected areas for dolphins are currently underway. in 2005, the The World Wildlife Fund (WWF) established the Cambodian Mekong Dolphin Conservation Project with support from government and local communities. The aim is to support the survival of the remaining population through targeted conservation activities, research and education.
India
The Irrawaddy dolphin (under the common name of snubfin dolphin, with the scientific name misspelled as Oreaella brevezastris) is included the Indian Wildlife Protection Act, Schedule I, which bans their killing, transport and sale of products. A major restoration effort to open a new mouth between Chilika lake and the Bay of Bengal in 2000 was successful in restoring the lake ecology and regulating the salinity gradient in the lake waters, which has resulted in increases in the population of Irrawaddy dolphin due to increase of prey species of fish, prawns and crabs.
Indonesia
At East Kalimantan Island, the Semayang National Park has been proposed as a Irrawaddy dolphin sanctuary. Local conservationists have also been pressing for protection of the lake and its watershed, the Berambai Forest.
Laos
Canadian conservationist Ian Baird set up the Lao Community Fisheries and Dolphin Protection Project to study the Irrawaddy dolphins in the Lao part of the Mekong. Part of this project compensated fishers for the loss of nets damaged to free entangled dolphins. This project was expanded to include Cambodia, after the majority of the dolphin population was determined to have been killed or migrated to Laos' southern neighbour. The Si Phan Don Wetlands Project has successfully encouraged river communities to set aside conservation zones and establish laws to regulate how and when fish are caught.
Burma
In 2005, the Department of Fisheries established a protected area for Irrawaddy dolphins in a 74 km (46 mi)-km segment of the Ayeyarwady River between Mingun
and Kyaukmyaung
. Protective measures in the area include mandatory release of entangled dolphins, prohibition of the catching or killing of dolphins and trade in whole or parts of them and the prohibition of electrofishing and gillnets more than 300 feet (91.4 m) long, or spaced less than 600 feet (182.9 m) apart. Mercury poisoning
and habitat loss from gold mining dregding operations in the river have been eliminated
Philippines
In 2000, Malampaya Sound was proclaimed a protected seascape. This is the lowest possible prioritization given to a protected area. Malampaya Sound Ecological Studies Project was initiated by the WWF. With technical support provided by the project, the municipality of Taytay
and the Malampaya park management developed fishery policies to minimize the threats to the Irrawaddy dolphin from by-catch capture. Gear studies and gear modification to conserve the dolphin species were implemented. The project was completed in 2007.
In 2007, the Coral Triangle
Initiative, a new multilateral partnership to help safeguard the marine and coastal resources of the Coral Triangle, including the Irrawaddy dolphin subpopulation in Malampaya Sound, was launched.
Thailand
In 2002, the Marine and Coastal Resources Department was assigned to protect rare aquatic animals such as dolphins, whales and turtles in Thai territorial waters. To protect the dolphins, patrol vessels ensure boats stay at least 30 m (98.4 ft) away from dolphins and there is no chasing of or running through schools of dolphins. Many fishers on the Bang Pakong River have been persuaded by authorities to stop shrimp fishing that area, and 30 to 40 fishing boats have been modified so they can offer dolphin sightseeing tours.
Malaysia
In 2008, the Department of Forestry and Sarawak Forestry Cooperative in Sarawak established a protected area for Irrawaddy dolphins in Santubong and Damai (Kuching Wetland). Furthermore, they plan to establish more beaches in Miri as protected areas for them. The protection measures in the area include prohibition of catching or killing of dolphins and trade in whole or parts of them, and prohibiting the use of gillnets. The government may also start small and medium scale research of this species at Sarawak Malaysia University
with sponsorship from Sarawak Shell.
Euryhaline
Euryhaline organisms are able to adapt to a wide range of salinities. An example of a euryhaline fish is the molly which can live in fresh, brackish, or salt water. The European shore crab is an example of a euryhaline invertebrate that can live in salt and brackish water...
species of oceanic dolphin
Oceanic dolphin
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
found in discontinuous subpopulations near sea coasts and in estuaries and rivers in parts of the Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...
and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
.
Etymology and taxonomic history
The Irrawaddy dolphin was first described by Sir Richard OwenRichard Owen
Sir Richard Owen, FRS KCB was an English biologist, comparative anatomist and palaeontologist.Owen is probably best remembered today for coining the word Dinosauria and for his outspoken opposition to Charles Darwin's theory of evolution by natural selection...
in 1866 based on a specimen found in 1852, in the harbour of Visakhapatnam
Visakhapatnam
Visakhapatnam is a major sea port on the south east coast of India. With a population of approximately 1.7 million, it is the second largest city in the state of Andhra Pradesh and the third largest city on the east coast of India after Kolkata and Chennai. According to the history, the city was...
on the east coast of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
. It is one of two species in its genus. It has sometimes been listed variously in a family containing just itself and in Monodontidae
Monodontidae
The cetacean family Monodontidae comprises two unusual whale species, the narwhal, in which the male has a long tusk, and the white beluga whale...
and in Delphinapteridae. There is now widespread agreement to list it in the Delphinidae family.
Genetically, the Irrawaddy dolphin is closely related to the killer whale (orca). The species name brevirostris comes from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
meaning short-beaked. In 2005, genetic analysis showed the Australian snubfin dolphin
Australian Snubfin Dolphin
The Australian snubfin dolphin is a dolphin found off the northern coasts of Australia. It closely resembles the Irrawaddy dolphin and was not described as a separate species until 2005. The Australian snubfin is tri-coloured, while the Irrawaddy dolphin only has two colours on its skin...
found at the coast of northern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
forms a second species in the Orcaella genus.
Overall, the dolphins' color is grey to dark slate blue, paler underneath, with no distinctive pattern. The dorsal fin is small and rounded behind the middle of the back. The forehead is high and rounded; the beak is lacking. The flippers are broad and rounded. The species found in Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
, the finless porpoise
Finless Porpoise
The finless porpoise is one of six porpoise species. In the waters around Japan, at the northern end of its range, it is known as the sunameri . A freshwater population found in the Yangtze River in China is known locally as the jiangzhu or "river pig". There is a degree of taxonomic uncertainty...
, Neophocaena phocaenoides, is similar and has no back fin; the humpback dolphin
Humpback dolphin
Humpback dolphins are members of the genus Sousa. These dolphins are characterized by the conspicuous humps and elongated dorsal fins found on the back of adult members of the species...
, Sausa chinensis, is larger, has a longer beak and a larger dorsal fin.
The several common names for O. brevirostris include: English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...
: Irrawaddy dolphin, local Chilika dialect: baslnyya magar or bhuasuni magar (oil yielding dolphin), Oriya
Oriya language
Oriya , officially Odia from November, 2011, is an Indian language, belonging to the Indo-Aryan branch of the Indo-European language family. It is mainly spoken in the Indian states of Orissa and West Bengal...
: khem and khera, French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...
: orcelle, Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...
: delfín del Irrawaddy, German
German language
German is a West Germanic language, related to and classified alongside English and Dutch. With an estimated 90 – 98 million native speakers, German is one of the world's major languages and is the most widely-spoken first language in the European Union....
: Irrawadi Delphin, Burmese
Burmese language
The Burmese language is the official language of Burma. Although the constitution officially recognizes it as the Myanmar language, most English speakers continue to refer to the language as Burmese. Burmese is the native language of the Bamar and related sub-ethnic groups of the Bamar, as well as...
: labai, Indonesia
Indonesian language
Indonesian is the official language of Indonesia. Indonesian is a normative form of the Riau Islands dialect of Malay, an Austronesian language which has been used as a lingua franca in the Indonesian archipelago for centuries....
: pesut, Malay
Malay language
Malay is a major language of the Austronesian family. It is the official language of Malaysia , Indonesia , Brunei and Singapore...
: lumbalumba, Khmer
Khmer language
Khmer , or Cambodian, is the language of the Khmer people and the official language of Cambodia. It is the second most widely spoken Austroasiatic language , with speakers in the tens of millions. Khmer has been considerably influenced by Sanskrit and Pali, especially in the royal and religious...
: ផ្សោត ph’sout , Lao
Lao language
Lao or Laotian is a tonal language of the Tai–Kadai language family. It is the official language of Laos, and also spoken in the northeast of Thailand, where it is usually referred to as the Isan language. Being the primary language of the Lao people, Lao is also an important second language for...
: pha’ka and Filipino
Filipino language
This move has drawn much criticism from other regional groups.In 1987, a new constitution introduced many provisions for the language.Article XIV, Section 6, omits any mention of Tagalog as the basis for Filipino, and states that:...
: lampasut. In Thai
Thai language
Thai , also known as Central Thai and Siamese, is the national and official language of Thailand and the native language of the Thai people, Thailand's dominant ethnic group. Thai is a member of the Tai group of the Tai–Kadai language family. Historical linguists have been unable to definitively...
, one of its names is pla loma hua bat, because its rounded head is thought to resemble the shape of a Buddhist monk's bowl, a hua bat.
Description
Irrawaddy dolphins are similar to the beluga in appearance, though most closely related to the orcaOrca
The killer whale , commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas...
. They have a large melon
Melon (whale)
The melon is an ovoid-shaped, fatty organ found in the forehead of all toothed whales , including dolphins and porpoises and believed to be used in echolocation....
and a blunt, rounded head, and the beak is indistinct. The dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
, located about two-thirds posterior along the back, is short, blunt and triangular. The flippers are long and broad. It is lightly coloured all over, but slightly more white on the underside than the back. Adult weight exceeds 130 kg (286.6 lb) and length is 2.3 m (7.5 ft) m at full maturity. Maximum recorded length is 2.75 m (9 ft) of a male from Thailand.
Reproduction
These dolphins are thought to reach sexual maturity at seven to nine years. In the Northern Hemisphere, mating is reported from December to June. Its gestation period is 14 months; cows give birth to a single calf every two to three years. Length is about 1 m (3.3 ft) at birth. Birth weight is about 10 kg (22 lb). Weaning is after two years. Lifespan is about 30 years.Behavior
Irrawaddy dolphins communicate with clicks, creaks and buzzes at a dominant frequency of about 60 kilohertz, which is thought to be used for echolocationAnimal echolocation
Echolocation, also called biosonar, is the biological sonar used by several kinds of animals.Echolocating animals emit calls out to the environment and listen to the echoes of those calls that return from various objects near them. They use these echoes to locate and identify the objects...
. Bony fish and fish eggs, cephalopods, and crustaceans are taken as food. Observations of captive animals indicate food may be taken into the mouth by suction. Irrawaddy dolphins sometimes spit streams of water, sometimes while spyhopping, during feeding, apparently to expel water ingested during fish capture or possibly to herd fish. Some Irrawaddy dolphins kept in captivity have been trained to do spyhopping on command. The Irrawaddy dolphin is a slow swimmer, but swimming speeds of 20–25 km/hour were reported when dolphins were being chased in a boat.
It surfaces in a rolling fashion and lifts its tail fluke clear of the water only for a deep dive. Deep dive times range from 70–150 seconds to 12 minutes. When 277 group dives were timed (time of disappearance of last dolphin in group to emergence of first dolphin in the group) in Laos
Laos
Laos Lao: ສາທາລະນະລັດ ປະຊາທິປະໄຕ ປະຊາຊົນລາວ Sathalanalat Paxathipatai Paxaxon Lao, officially the Lao People's Democratic Republic, is a landlocked country in Southeast Asia, bordered by Burma and China to the northwest, Vietnam to the east, Cambodia to the south and Thailand to the west...
, mean duration was 115.3 seconds with a range of 19 seconds to 7.18 minutes. They make only occasional low leaps and never bow-ride. Groups of fewer than six individuals are most common, but sometimes up to 15 dolphins are seen together.
Interspecific competition
Interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
has been observed when Orcaella was forced inshore and excluded by more specialised dolphins. When captive humpback dolphins (Sonsa chinensis) and Irrawaddy dolphins were held together, repotedly the Irrawaddy dolphins were frequently chased and confined to a small portion of the tank by the dominant humpbacks. In Chilika Lake, local fishers say when Irrawaddy dolphins and bottlenose dolphins meet in the outer channel, the former get frightened and are forced to return toward the lake.
Habitat and subpopulations
River dolphin
River dolphins are the four living species of dolphin that reside in freshwater rivers and estuaries. River dolphins inhabit areas of Asia and South America. They are classed in the Platanistoidea superfamily of cetaceans. Three species live in fresh water rivers. The fourth species, the La Plata...
, but an oceanic dolphin
Oceanic dolphin
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These marine mammals are related to whales and porpoises. They are found worldwide, mostly in the shallower seas of the continental shelves...
that lives in brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
near coasts, river mouths and in estuaries. It has established subpopulations in freshwater rivers, including the Ganges and the Mekong
Mekong
The Mekong is a river that runs through China, Burma, Laos, Thailand, Cambodia and Vietnam. It is the world's 10th-longest river and the 7th-longest in Asia. Its estimated length is , and it drains an area of , discharging of water annually....
, as well as the Irrawaddy River
Ayeyarwady River
The Irrawaddy River or Ayeyarwady River is a river that flows from north to south through Burma . It is the country's largest river and most important commercial waterway. Originating from the confluence of the N'mai and Mali rivers, it flows relatively straight North-South before emptying through...
from which it takes its name. Its range extends from the Bay of Bengal
Bay of Bengal
The Bay of Bengal , the largest bay in the world, forms the northeastern part of the Indian Ocean. It resembles a triangle in shape, and is bordered mostly by the Eastern Coast of India, southern coast of Bangladesh and Sri Lanka to the west and Burma and the Andaman and Nicobar Islands to the...
to New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
and the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
.
It is often seen in estuaries and bays in Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
Island, with sightings from Sandakan
Sandakan
Sandakan is the second-largest city in Sabah, East Malaysia, on the north-eastern coast of Borneo. It is located on the east coast of the island and it is the administrative centre of Sandakan Division and was the former capital of British North Borneo...
in Sabah
Sabah
Sabah is one of 13 member states of Malaysia. It is located on the northern portion of the island of Borneo. It is the second largest state in the country after Sarawak, which it borders on its southwest. It also shares a border with the province of East Kalimantan of Indonesia in the south...
, Malaysia, to most parts of Brunei
Brunei
Brunei , officially the State of Brunei Darussalam or the Nation of Brunei, the Abode of Peace , is a sovereign state located on the north coast of the island of Borneo, in Southeast Asia...
and Sarawak
Sarawak
Sarawak is one of two Malaysian states on the island of Borneo. Known as Bumi Kenyalang , Sarawak is situated on the north-west of the island. It is the largest state in Malaysia followed by Sabah, the second largest state located to the North- East.The administrative capital is Kuching, which...
, Malaysia. A specimen was collected at Mahakam River
Mahakam River
The Mahakam River is in Indonesia. It flows 980 km from the district of Long Apari in the highlands of Borneo, to its mouth at the Makassar Strait....
in East Kalimantan
East Kalimantan
East Kalimantan is the second largest Indonesian province, located on the Kalimantan region on the east of Borneo island. The resource-rich province has two major cities, Samarinda and Balikpapan...
.
No range-wide survey has been conducted for this vulnerable species; however, the worldwide population appears to be over 7,000, with over 90% occurring in Bangladesh
Bangladesh
Bangladesh , officially the People's Republic of Bangladesh is a sovereign state located in South Asia. It is bordered by India on all sides except for a small border with Burma to the far southeast and by the Bay of Bengal to the south...
. Populations outside Bangladesh and India are classified as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
. Known subpopulations of Irrawaddy dolphins are found in eight places, listed here in order of population, including conservation status
Conservation status
The conservation status of a group of organisms indicates whether the group is still extant and how likely the group is to become extinct in the near future...
.
- Bangladesh; 5,832 (VUVulnerable speciesOn 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
) in coastal waters of the Bay of Bengal and 451 (VU) in the brackish SundarbansSundarbansThe Sundarbans [Sundarban Tour Booking-9051115228] is the largest single block of tidal halophytic mangrove forest in the world.The name Sundarban can be literally translated as "beautiful jungle" or "beautiful forest" in the Bengali language...
mangrove forest - India; 138 (VU) in the brackish water Chilka Lake
- Laos and CambodiaCambodiaCambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...
; 66-86 (CRCritically endangeredVersion 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
) in a 190 km (118.1 mi) freshwater stretch of the Mekong River - IndonesiaIndonesiaIndonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
; (CR), in a 420 km (261 mi) stretch of the freshwater Mahakam RiverMahakam RiverThe Mahakam River is in Indonesia. It flows 980 km from the district of Long Apari in the highlands of Borneo, to its mouth at the Makassar Strait.... - PhilippinesPhilippinesThe Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...
; about 77 (CR) in the brackish inner Malampaya Sound Researchers are studying the recent discovery of 30-40 dolphins sighted in the waters of Bago City and Pulupandan town in the province of Negros Occidental, in Western Visayas http://www.gmanews.tv/story/200345/rare-dolphins-make-negros-coastal-waters-their-home - Burma; about 58-72 (CR) in a 370 km (229.9 mi) freshwater stretch of the Ayeyarwady RiverAyeyarwady RiverThe Irrawaddy River or Ayeyarwady River is a river that flows from north to south through Burma . It is the country's largest river and most important commercial waterway. Originating from the confluence of the N'mai and Mali rivers, it flows relatively straight North-South before emptying through...
- ThailandThailandThailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
: less than 50 (CR) in the brackish Songkhla LakeSongkhla LakeThe Songkhla lake is the largest natural lake in Thailand, located on the Malay peninsula in the southern part of the country. Covering an area of 1,040 km² it borders the provinces of Songkhla and Phatthalung. Despite being called a lake, this water surface is actually a lagoon complex...
.
Interaction with humans
Irrawaddy dolphins have a seemingly mutualistic relationship of co-operative fishing with traditional fishers. Fishers in India recall when they would call out to the dolphins, to drive fish into their nets.In Burma, in the upper reaches of the Ayeyawady River, Irrawaddy dolphins drive fish towards fishers using cast net
Cast net
A cast net, also called a throw net, is a net used for fishing. It is a circular net with small weights distributed around its edge.The net is cast or thrown by hand in such a manner that it spreads out on the water and sinks. This technique is called net casting or net throwing. Fish are caught as...
s in response to acoustic signals from them. In return, the dolphins are rewarded with some of the fishers' by-catch
By-catch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
. Historically, Irrawaddy River fishers claimed particular dolphins were associated with individual fishing villages and chased fish into their nets. An 1879 report indicated legal claims were frequently brought into native courts by fishers to recover a share of the fish from the nets of a rival fisher which the plaintiff's dolphin was claimed to have helped fill.
Threats
Gillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
s is the main threat to them throughout their range. The majority of reported dolphin deaths in all subpopulations is due to accidental capture and drowning in gillnets and dragnet
Trawling
Trawling is a method of fishing that involves pulling a fishing net through the water behind one or more boats. The net that is used for trawling is called a trawl....
s, and in the Philippines, bottom-set crabnets. In Burma, electrofishing
Electrofishing
Electrofishing uses electricity to stun fish before they are caught. Electrofishing is a common scientific survey method used to sample fish populations to determine abundance, density, and species composition...
, gold mining
Gold mining
Gold mining is the removal of gold from the ground. There are several techniques and processes by which gold may be extracted from the earth.-History:...
and dam building are also serious and continuing threats. Though most fishers are sympathetic to the dolphins' plight, it is difficult for them to abandon their traditional livelihood.
In several Asian countries, Irrawaddy dolphins have been captured and trained to perform in public aquarium
Public aquarium
A public aquarium is the aquatic counterpart of a zoo, housing living aquatic species for viewing. Most public aquariums feature tanks larger than those kept by home aquarists, as well as smaller tanks. Since the first public aquariums were built in the mid-19th century, they have become popular...
s. Their charismatic appearance and unique behaviours, including spitting water, spyhopping and fluke-slapping, make them very popular for shows in dolphinarium
Dolphinarium
A dolphinarium is an aquarium for dolphins. The dolphins are usually kept in a large pool, though occasionally they may be kept in pens in the open sea, either for research or for public performances...
s. The commercial motivation for using this dolphin species is high because it can live in freshwater tanks and the high cost of marine aquarium
Marine aquarium
A marine aquarium is an aquarium that keeps marine plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only , fish only with live rock , and reef aquaria. Fish only tanks often showcase large or aggressive marine fish species and generally...
systems is avoided. The region within and near the species’ range has developed economically, and theme parks, casinos and other entertainment venues that include dolphin shows has increased. In 2002, there were more than 80 dolphinariums in at least nine Asian countries
Collateral deaths
Collateral damage
Collateral damage is damage to people or property that is unintended or incidental to the intended outcome. The phrase is prevalently used as an euphemism for civilian casualties of a military action.-Etymology:...
of dolphins due to blast fishing
Blast fishing
Blast fishing or dynamite fishing is the practice of using explosives to stun or kill schools of fish for easy collection. This often illegal practice can be extremely destructive to the surrounding ecosystem, as the explosion often destroys the underlying habitat that supports the fish...
were once common in Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
and Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
. In the past, the most direct threat was killing them for their oil.
The IUCN lists five of the seven subpopulations as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
, primarily due to drowning in fish nets. For example, the Malampaya population, first discovered and described in 1986, at the time consisted of 77 individuals. Due to anthropogenic activities, this number dwindled to 47 dolphins in 2007.
Conservation
Entanglement in fishnets and degradation of habitats are the primary threats to Irrawaddy dolphins. Multiple conservation efforts are being made at international and national levels to alleviate these threats.International efforts
These dolphins are classified by the IUCN as a critically endangered species in Laos, Malaysia, Burma, Philippines, and Thailand, and a vulnerable species
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
in Bangladesh and India. They are thus are legally protected from hunting; however, enforcement may be poor along thousands of miles of coast line. In 2004, CITES transferred the Irrawaddy dolphin from Appendix II to Appendix I, which forbids all commercial trade in species that are threatened with extinction.
The UNEP-CMS
Bonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
Action Plan for the Conservation of Freshwater Populations of Irrawaddy dolphins notes that multiple-use protected areas will play a key role for conserving freshwater populations. Protected areas in fresh water could be a particularly effective conservation tool and can facilitate management, due to the fidelity of the species to relatively circumscribed areas. The Action Plan provides details on strategies for mitigating by-catch
By-catch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
that includes:
- -establishing core conservation areas where gillnetting is banned or severely restricted
- -promoting net attendance rules and providing training on the safe release of entangled dolphins
- -initiating programs to compensate fishers for damage caused to their nets by entangled dolphins that are safely released
- -providing alternative or diversified employment options for gillnet fishers
- -encouraging the use of fishing gear that does not harm dolphins, by altering or establishing fee structures for fishing permits to make gillnetting more expensive while decreasing the fees for nondestructive gear
- -experimenting with acoustical deterrents and reflective nets.
The Irrawaddy dolphin is listed on both Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS
Bonn Convention
The Convention on the Conservation of Migratory Species of Wild Animals aims to conserve terrestrial, marine and avian migratory species throughout their range...
). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of their range and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them, as well on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
The species is also covered by the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region (Pacific Cetaceans MoU).
National efforts
Several national efforts are resulting in the reduction of threats to local Irrawaddy dolphin subpopulations:
Bangladesh
Sundarbans
The Sundarbans [Sundarban Tour Booking-9051115228] is the largest single block of tidal halophytic mangrove forest in the world.The name Sundarban can be literally translated as "beautiful jungle" or "beautiful forest" in the Bengali language...
mangrove forest of Bangladesh are included within 139699 ha (539 sq mi) of three wildlife sanctuaries, which are part of the Sunderbans World Heritage Site. The Wildlife Conservation Society
Wildlife Conservation Society
The Wildlife Conservation Society based at the Bronx Zoo was founded in 1895 as the New York Zoological Society and currently manages some of wild places around the world, with over 500 field conservation projects in 60 countries, and 200 scientists on staff...
is working with the Bangladesh Ministry of Environment and Forests to create protected areas for the 6000 remaining dolphins
Cambodia
The Cambodian Department of Fisheries has drafted a Royal Decree for protection of Irrawaddy dolphins in the Mekong River, which includes the designation of eight protected areas, totaling 5721 ha (22.1 sq mi), in a 190 km (118.1 mi) segment of the river above Kratie. The establishment of community-managed deep water fish conservation zones with government support may represent the best opportunity for reducing dry-season dolphin mortality from large-meshed gillnet entanglement. Efforts to establish protected areas for dolphins are currently underway. in 2005, the The World Wildlife Fund (WWF) established the Cambodian Mekong Dolphin Conservation Project with support from government and local communities. The aim is to support the survival of the remaining population through targeted conservation activities, research and education.
India
The Irrawaddy dolphin (under the common name of snubfin dolphin, with the scientific name misspelled as Oreaella brevezastris) is included the Indian Wildlife Protection Act, Schedule I, which bans their killing, transport and sale of products. A major restoration effort to open a new mouth between Chilika lake and the Bay of Bengal in 2000 was successful in restoring the lake ecology and regulating the salinity gradient in the lake waters, which has resulted in increases in the population of Irrawaddy dolphin due to increase of prey species of fish, prawns and crabs.
Indonesia
At East Kalimantan Island, the Semayang National Park has been proposed as a Irrawaddy dolphin sanctuary. Local conservationists have also been pressing for protection of the lake and its watershed, the Berambai Forest.
Laos
Canadian conservationist Ian Baird set up the Lao Community Fisheries and Dolphin Protection Project to study the Irrawaddy dolphins in the Lao part of the Mekong. Part of this project compensated fishers for the loss of nets damaged to free entangled dolphins. This project was expanded to include Cambodia, after the majority of the dolphin population was determined to have been killed or migrated to Laos' southern neighbour. The Si Phan Don Wetlands Project has successfully encouraged river communities to set aside conservation zones and establish laws to regulate how and when fish are caught.
Burma
In 2005, the Department of Fisheries established a protected area for Irrawaddy dolphins in a 74 km (46 mi)-km segment of the Ayeyarwady River between Mingun
Mingun
Mingun is a town in Sagaing Region, northwest Myanmar , located 11 km up the Ayeyarwady River on the west bank from Mandalay. Its main attraction is the ruined Mingun Pahtodawgyi.-Mingun Pahtodawgyi:...
and Kyaukmyaung
Kyaukmyaung (Sagaing)
Kyaukmyaung is a town in Sagaing Division, Myanmar. It is situated 46 miles north of Mandalay on the west bank of the River Irrawaddy, and 17 miles east of Shwebo by road...
. Protective measures in the area include mandatory release of entangled dolphins, prohibition of the catching or killing of dolphins and trade in whole or parts of them and the prohibition of electrofishing and gillnets more than 300 feet (91.4 m) long, or spaced less than 600 feet (182.9 m) apart. Mercury poisoning
Mercury poisoning
Mercury poisoning is a disease caused by exposure to mercury or its compounds. Mercury is a heavy metal occurring in several forms, all of which can produce toxic effects in high enough doses...
and habitat loss from gold mining dregding operations in the river have been eliminated
Philippines
In 2000, Malampaya Sound was proclaimed a protected seascape. This is the lowest possible prioritization given to a protected area. Malampaya Sound Ecological Studies Project was initiated by the WWF. With technical support provided by the project, the municipality of Taytay
Taytay
Taytay is the name of two municipalities in the Philippines:* Taytay, Palawan* Taytay, RizalTayTay may also refer to the country pop artist Taylor Swift....
and the Malampaya park management developed fishery policies to minimize the threats to the Irrawaddy dolphin from by-catch capture. Gear studies and gear modification to conserve the dolphin species were implemented. The project was completed in 2007.
In 2007, the Coral Triangle
Coral Triangle
The Coral Triangle is a geographical term so named as it refers to a roughly triangular area of the tropical marine waters of Indonesia, Malaysia, Papua New Guinea, Philippines, Solomon Islands and Timor-Leste that contain at least 500 species of reef-building corals in each ecoregion...
Initiative, a new multilateral partnership to help safeguard the marine and coastal resources of the Coral Triangle, including the Irrawaddy dolphin subpopulation in Malampaya Sound, was launched.
Thailand
In 2002, the Marine and Coastal Resources Department was assigned to protect rare aquatic animals such as dolphins, whales and turtles in Thai territorial waters. To protect the dolphins, patrol vessels ensure boats stay at least 30 m (98.4 ft) away from dolphins and there is no chasing of or running through schools of dolphins. Many fishers on the Bang Pakong River have been persuaded by authorities to stop shrimp fishing that area, and 30 to 40 fishing boats have been modified so they can offer dolphin sightseeing tours.
Malaysia
In 2008, the Department of Forestry and Sarawak Forestry Cooperative in Sarawak established a protected area for Irrawaddy dolphins in Santubong and Damai (Kuching Wetland). Furthermore, they plan to establish more beaches in Miri as protected areas for them. The protection measures in the area include prohibition of catching or killing of dolphins and trade in whole or parts of them, and prohibiting the use of gillnets. The government may also start small and medium scale research of this species at Sarawak Malaysia University
Universiti Malaysia Sarawak
Universiti Malaysia Sarawak or UNIMAS was officially incorporated on 24 December 1992. UNIMAS is Malaysia's eighth University, established just after the declaration of Vision 2020...
with sponsorship from Sarawak Shell.
External links
- Convention on Migratory Species page on the Irrawaddy Dolphin
- Official webpage of the Memorandum of Understanding for the Conservation of Cetaceans and Their Habitats in the Pacific Islands Region
- Some good Irrawaddy dolphin photos: -1-, -2-, -3-, -4-.
- Video of Irrawaddy dolphin behavior
- Irrawaddy dolphins spyhopping and spitting water
- WWF-US Irrawaddy page
- National geographic Gold mining, nets endanger dolphin (contains photo)
- Whale and Dolphin Conservation Society
- Transcript of briefing by Burmese marine biologist Tint Tun describes human/dolphin cooperative fishing.
- Burmese Heritage web site on Irrawaddy dolphins has photos of human/dolphin cooperative fishing.
- Irrawaddy Dolphin News
- Worldwide Bycatch of Cetaceans, National Marine Fisheries ServiceNational Marine Fisheries ServiceThe National Marine Fisheries Service is a United States federal agency. A division of the National Oceanic and Atmospheric Administration and the Department of Commerce, NMFS is responsible for the stewardship and management of the nation's living marine resources and their habitat within the...
, NOAA Tech. Memo. NMFS-OPR-36 July 2007 65 Irrawaddy Dolphin mentions - World Wide Fund for Nature (WWF) - species profile for the Irrawaddy dolphin
- Habitat of the northerly pods of Irrawaddy dolphins on The Mekong. A panoramic tour of Ramsar Site 999-the flooded forests of Northern Cambodia
- Video clips of Irrawaddy dolphins in the Mekong River - southern Laos - northern Cambodia