(CNN) -- Fishermen in Bangladesh beat a rare river dolphin to death because they had not seen "this kind of creature before," according to local news accounts.

The fishermen then tried to sell the body of the Ganges River dolphin as a rare fish. When they failed, the men gave up and dumped it outside a museum -- where a large crowd tried to catch a peek, the national Bangladesh Sangbad Sangstha news organization reported Tuesday.

Elisabeth Fahrni Mansur, who works with the Bangladesh Cetacean Diversity Project, told CNN that the mammal was trapped in the low waters of a tidal channel.

"It wasn't dumped in front of a museum," Mansur added. "The animal was taken to a visitor center where it will be prepared for an exhibit."

The Ganges River dolphin inhabits the murky waters of the Ganges River and can be spotted only when it surfaces to breathe. Thus, they are very rarely seen, according to the World Wildlife Fund Web site.

Unlike its marine counterpart, these fresh-water dolphins have a pudgy body and an extra-long and sharp-toothed snout. They are almost completely blind probably because of the poor visibility of the waters in the Ganges River, the WWF said.

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The World Conservation Union places the total population of the dolphins at 4,000 to 5,000. It classifies the Ganges River dolphin as an endangered species.

The air-breathing mammals sometimes die after they find themselves stranded in shallow waters, Mansur said. The construction of dams has reduced the flow of fresh water in many parts of Bangladesh.

The dolphin population is also dwindling because they sometimes get caught in a fisherman's net.

The fishermen caught the dolphin Monday in Bagerhat, a city near one of the world's largest mangrove forests.

The forests of the Sundarbans -- Bengali for "beautiful forest" -- lies at the delta of the Ganges and two other rivers on the Bay of Bengal. E-mail to a friend

CNN's Saeed Ahmed contributed to this story

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