Rare Asian dolphin threatened by human activities
A rare dolphin species known for assisting fishermen by driving fish into their nets may soon disappear from the great Asian river for which the animals are named. According to a recent scientific survey by the Wildlife Conservation Society (WCS) and its partners, the Irrawaddy dolphin may vanish from the Ayeyarwady River (formerly Irrawaddy) without efforts to protect these aquatic mammals from human activities along the river.
A research team with members from WCS, WDCS (the Whale and Dolphin Conservation Society), the Myanmar Departments of Fisheries and Forests, and Yangon University estimate that only a few tens of dolphins remain within the river. "The range of this dolphin has dramatically declined over the past century," said WCS researcher Brian Smith. "The decline in their range and the low numbers observed indicate that this population is critically threatened." Irawaddy dolphins, which bear a resemblance to the more familiar beluga whale, are beloved by fishermen for their habit of working cooperatively to drive fish into range of throw nets. Smith is hopeful that the dolphins popularity and value to fishermen as a living resource will facilitate a site-based conservation program that would work to eliminate threats and promote cultural traditions that would benefit the dolphins.
"Local throw-net fishermen along the river have great affection for the dolphins, so I believe there would be good local support for a site-based conservation program," said Smith. "A protected area could also preserve both the dolphins and the traditional fishing practice of cooperating with the dolphins."
During the recent 27-day survey of the entire length of the Ayeyarwady, researchers recorded only nine sightings of this rare dolphin, compared with 14 sightings from a 1998 survey along the same portion of river. The researchers failed to observe dolphins below Mandalay and the delta, leading them to believe that the upper Ayeyarwady population is separate from coastal populations. The species full range includes the coasts and rivers of southern Asia and Australasia; the most threatened populations of Irrawaddy dolphins are the freshwater lake and river populations.
The researchers also recorded numerous gill nets--dangerous to dolphins--in areas previously known to be prime dolphin habitat. The illegal activity of electric fishing, which uses high voltage to kill all organisms within its range and is conducted under the cover of night, is another threat to the dolphins. Extensive gold-mining operations pose an enormous threat to both dolphins and humans, due to the use of mercury to amalgamate the gold. Mercury can have detrimental effects on living organisms, accumulating in predators on top of the food chain.
Smith expects the International Union for the Conservation of Nature (IUCN) to list the Ayeyarwady population as critically endangered in the near future.
Stephen Sautner | EurekAlert!
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