Special Reports: Irrawaddy dolphins – The Mekong River’s ‘spirit’

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Last update 29/05/2012 08:00:00 AM (GMT+7)

VietNamNet Bridge – Being afraid of having no chance to see Irrawaddy dolphins – which is listed at the top of endangered species by the International Union of Conservation of Nature (IUCN), we went to their major domain. That is the 190km section of the major branch of the Mekong Delta between Cambodia’s Kratie province and Lao’s Champasak province.

Lying in wait along the border

We flew from HCM City to Pakse City in Champasak province of Laos. From Pakse, it took us around two hours to pass 150km of road by car to Ban Vuenkham, an ancient village near the Mekong River.

We hired a motorboat and drove it to the midstream, around 100m from the riverbank, to wait for Irrawaddy dolphins.

Nearly 30 minutes passed, we did not see any dolphin. The motorboat driver, named Chan Pone, told us to be patient because these dolphins usually rise to the surface to breathe and play at around 4-6pm.

Irrawaddy dolphins began appearing in the Mekong Delta several decades ago, thousands of Irrawaddy dolphins used to live peacefully in the Mekong Delta and the river’s branches in Laos, Vietnam and Cambodia.

These dolphins are very intelligent, friendly and they could understand the human voice. Those fish could save fishermen in dangerous situations. They also help fishermen by making sound to drive fish into fishing nets. Therefore, Southeast Asian fishermen set the rule to protect and sharing fish for Irrawaddy dolphins.

The lifespan of Irrawaddy dolphins is about 30 years. Their reproductive age is from the 7th to the 9th year. The pregnancy period is 14 months, with only one baby being born each time. The gap between each time is 3-4 years.

Baby dolphins are nearly one meter long but their weight is around 10 kilos only. The rate of baby fish which live until their maturity is very low.

Because of the low reproduction rate, environmental pollution, fisheries bycatch and habitat loss, the number of Irrawaddy dolphins is falling sharply, to less than 100 individuals in total; including barely the 7-8 heads in the section of river between Laos and Cambodia. This is the only place in Laos where Irrawaddy dolphins live.

For this reason, it is lucky for any visitor to see Irrawaddy dolphins, which are considered as the lucky fish.

“Look, a pair of dolphins are emerging!” one shouted. Following his fingertip, we saw two grey fins and then smooth and shining backs.

The boat driver paddled gently to take the boat nearer to the dolphins. A visitor asked the boat driver to take the boat to the river shore of Cambodia to see the fish more clearly. However, the driver refused because it was illegal.

A visitor named Quoc said ten years ago, a Lao boat driver took him to the Cambodian riverbank to watch Irrawaddy dolphins. That year, Cambodian border guards permitted visitors from Laos to land on their land to see dolphins.

A dolphin suddenly lashed his tail very strong and jumped out of the water, showing its round brow, its plump mouth and two small fins.

These dolphins were 2.3-2.5 meters long and around 200kg in weight. The boat driver said that around four years ago, a big dolphin of about 250kg had died and floated into the riverbank.

Going to the land of dolphin legend

The boat driver took us upriver for around 20 minutes to Khone Phapheng, the largest waterfall in Southeast Asia, which is called the Niagara waterfall of Asia.

The waterfall is 21m high and stretches for several kilometers long, with swift-flowing current. The waterfall has turned this area into the roughest section of the Mekong River.

Guiding us to climb up onto the rock-tops in the middle of the river to wait for seeing Irrawaddy dolphins, the boat driver told us the following legend:

One day, a beautiful princess named Sida was permitted by her father to go downstream of the Mekong River, from Laos to Cambodia, Vietnam, the East Sea and up to China to do business. When her boat approached very near to a mysterious island named Siphandone (Laos), the boat lost direction and it wandered in this area for three years. The princess lived on the boat during this time thanks to the abundant resources of fish there. After that, they found out the direction to move to the south. However, they faced the Khone Phapheng waterfall.

The princess was confused because most animals on her boat advised her to stop while only a cock told her to go forward. The princess decided to follow the cock’s advice. The boat fell into the waterfall and was swallowed. The princess turned into Nok Sida – a fish eating bird while her only male servant named Kha became an Irrawaddy dolphin.

Today, whenever Irrawaddy dolphins emerge to the surface, Nok Sida birds appear because while seeking food, dolphins drive fish to the surface for the birds.

Now, Siphandone is among famous tourist destinations in Laos thanks to its beautiful landscape, the Khone Phapheng waterfall and the existence of rare Irrawaddy dolphins.

This land is also the homeland of the former Laos President Khamtay Siphandone.

Leaving Laos, we were regretful because we no longer had the chance to go downstream to see Irrawaddy dolphins in Kratie province in Cambodia–or a group of 20 Irrawaddy dolphins that was just discovered by researchers from Vietnam’s Institute for Tropical Biology around Ba Lua archipelago in the Kien Giang Biosphere last September.

Facts and figure about Irrawaddy dolphins

The Irrawaddy dolphin exists in small isolated populations around Southeast Asia. Freshwater subpopulations occur in the river Mahakam of Kalimantan (Indonesian Borneo), the Ayeyarwady (formerly Irrawaddy) of Myanmar, and the Mekong Delta of Laos, Cambodia, and Vietnam. They are also reported in isolated brackish (saltwater and freshwater) water bodies, such as Chilka Lake in India and Songkhla Lake in Thailand. Some populations are close to extinction such as those in the Mekong River and Malampaya Sound in the Philippines. The main threats are from fisheries bycatch and habitat loss.

The species is primarily found in Southeast Asian estuaries and mangrove areas, with freshwater populations occurring in river systems.

The Mahakam river population of Irrawaddy dolphins, found in the Kalimantan province of Indonesian Borneo, is severely threatened by fisheries bycatch and habitat degradation, and may number as few as 34 animals.

Surveys conducted in 2001 estimated that the Malampaya Sound population in the Philippines consists of just 77 individuals, confined to a small area in the inner sound, and is the only known population of this species in the country.

During 2001 there were reports that as many as five animals from this population were killed incidentally in fishing operations, indicating that the Irrawaddy dolphins of Malampaya Sound are in immediate danger of extinction due to low numbers, limited range, and high mortality.

The Mekong River Irrawaddy dolphin (Orcaella brevirostris) population inhabits a 190km stretch of the Mekong River between Cambodia and Lao PDR. The latest population is estimated between 78 and 91.

The Irrawaddy dolphin is identified by a bulging forehead, a short beak, and 12-19 teeth on each side of each jaw. The pectoral fin is broadly triangular. There is a small dorsal fin, on the posterior end of the back.

When diving, this dolphin breathes at intervals of 70-150 seconds; the head appears first and then disappears, and then the back emerges, but the tail is rarely seen.

Size: Head and body length is 180-275 cm.

Color: Irrawaddy dophins are slate blue to slate gray throughout, with the under parts slightly paler.

Irrawaddy dolphins are distributed in shallow, near-shore tropical and subtropical marine waters. They are primarily found in estuaries and semi-enclosed water bodies such as bays and sounds, usually close to mangrove forests. Freshwater populations occur in river systems.

Social Structure: Here are no more than 10 animals to a group usually, and solitary individuals are rarely seen.

Diet: The species eats fish and crustaceans.

The World Wildlife Fund (WWF) has announced that Irrawaddy dolphin is among the ten species facing extinction in 2012.

Tien Phong

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