Transboundary River Basin Overview Ganges- Brahmaputra-Meghna
Endangered Species: The Ganges River...
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Endangered Species: The Ganges River dolphin Image 1. A Ganges River dolphin jumps out of the water. Photo from: NOAA Marine Mammal Commission. The Ganges River dolphin is a freshwater species with gray-brown, smooth, hairless skin. It has a long beak with large, visible teeth. Although Ganges River dolphins spend their lives in the water, they breathe air. They generally surface every four to five minutes, but they can hold their breath for up to 10 minutes. Adult dolphins are 7 to 9 feet long and weigh 330 to 375 pounds. Females are larger than males. They give birth every two to three years to one calf. The calves are chocolate brown at birth and are weaned at about 1 year of age. Dolphins can live to be about 30 years old in the wild. Because it lives in muddy waters, the Ganges River dolphin has little need for vision. Its eyes are nonfunctional. Rather than relying on sight, the dolphins navigate and hunt by using echolocation, a kind of sonar. The dolphins make ultrasonic sounds, which bounce off their surroundings. They hear the echoes and By Gale, Cengage Learning, adapted by Newsela staff on 04.23.18 Word Count 622 Level MAX This article is available at 5 reading levels at https://newsela.com. 1
Transcript of Endangered Species: The Ganges River...
Endangered Species: The GangesRiver dolphin
Image 1. A Ganges River dolphin jumps out of the water. Photo from: NOAA Marine Mammal Commission.
The Ganges River dolphin is a freshwater species with gray-brown, smooth,hairless skin. It has a long beak with large, visible teeth. Although Ganges Riverdolphins spend their lives in the water, they breathe air. They generally surfaceevery four to five minutes, but they can hold their breath for up to 10 minutes.
Adult dolphins are 7 to 9 feet long and weigh 330 to 375 pounds. Females arelarger than males. They give birth every two to three years to one calf. The calvesare chocolate brown at birth and are weaned at about 1 year of age. Dolphins canlive to be about 30 years old in the wild.
Because it lives in muddy waters, the Ganges River dolphin has little need forvision. Its eyes are nonfunctional. Rather than relying on sight, the dolphinsnavigate and hunt by using echolocation, a kind of sonar. The dolphins makeultrasonic sounds, which bounce off their surroundings. They hear the echoes and
By Gale, Cengage Learning, adapted by Newsela staff on 04.23.18 Word Count 622 Level MAX
This article is available at 5 reading levels at https://newsela.com. 1
use that “picture” of their surroundings to navigate around obstacles and totarget prey. They eat mostly small fish and invertebrates. The dolphins feed inshallow areas at the bottom of the river by poking into the silt and mud with theirbeaks or flippers.
Ganges River dolphins migrate seasonally. During the dry season, they stay indeep pools or the main river channels. Following the monsoons, they moveupstream to tributaries.
Habitat And Population
The Ganges River dolphin is native to the Ganges-Brahmaputra-Meghna andKaranphuli-Sangu river systems of Bangladesh, Nepal and India. It is nearlyextinct in much of its range, however. It is believed that there are fewer than2,000 dolphins remaining, although this is only a guess. The number could beconsiderably lower or higher.
The greatest known number of remaining dolphins are within India, in the GangesRiver. They live between Manihari Ghat and Buxar, and also in the VikramshilaGangetic Dolphin Sanctuary.
History And Conservation
The Ganges River dolphin was firstscientifically identified in 1801. Itspopulation has seriously declined since thattime. This population decline is directlyrelated to the dolphin living in one of themost heavily populated areas in the world.
The main threat to the Ganges River dolphin is the use of dams for irrigation andelectricity. Damming their rivers prevents dolphins from migrating. It also isolatesdolphin populations.
Dolphins can often swim downstream during the wet season, but the strongdownstream currents prevent them from returning upstream during the dryseason. This puts them at risk because they have less access to food sources. Atleast 50 dams have been built in the dolphins' habitat, and more dams areplanned. The population of the Ganges River dolphin is therefore expected tocontinue to decline.
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Dolphins are also threatened by fertilizer, pesticides and industrial pollution.These pollutants kill the fish they feed on. Humans also hunt dolphins for meat oroil. Dolphins often look for fish in the same places that humans do. Many becomeentangled in fishing nets, which can result in their deaths.
Boat traffic on the Ganges River is also a threat to dolphins. The motor noiseinterferes with their echolocation, and the boats themselves often strike dolphins,killing or injuring them.
Ganges River dolphins are officially protected from hunting, but the protection isnot always enforced or effective. Still, dolphin populations have increased in theupper Ganges because of conservation efforts. Dolphins in parts of national parksor sanctuaries, such as the Kaziranga National Park in Assam, India, receive someadditional protection.
Ganges River dolphin oil is often used in the preparation of bait for other fish.Recent discoveries of possible oil substitutes may help reduce the hunting of theriver dolphins.
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