"I treat them as my children and do everything whenever a dolphin is trapped in shallow waters," said Mirani, once a fisherman and now among a handful of people officially assigned to protect the dolphins.

"No one can know them as meticulously as me. I was born in a boat and have been living with these fish ever since," said the lanky Mirani, his complexion darkened by years under the burning sun and his chest puffed up with pride.

"Look at my eyes," he said. "Aren't they shaped like the fish?"

Indus dolphins -- Platanista gangetica minor or "bulhan" in the local Sindhi language -- are listed as endangered by the World Conservation Union.

According to local folklore, a lactating woman once refused to give milk to a saint, who cursed her and pushed her into the Indus. The woman turned into a dolphin and the freshwater species was born.

Females are bigger than males, weighing up to 110 kilograms (243 pounds) and growing up to 2.5 metres (eight foot) long.

The brownish-pink mammals have lived alongside humans for time immemorial. Their long, pointed snouts thicken at the end, and the upper and lower teeth are visible even when the mouth is closed.

Their numbers are declining as fishermen deplete their stock of food, pollution worsens, and a network of barrages restricts their movements. Falling water levels due to declining rain and snowfall are another peril.

The Worldwide Fund For Nature Pakistan estimated in 2006 there were around 1,200 Indus dolphins left -- 900 at a sanctuary near Sukkur in the southern province of Sindh and another 300 further upstream in Punjab.

The dolphin is blind because it lacks eye lenses and so hunts for catfish and shrimp using sophisticated sonar, said Hussain Bux Bhagat, a senior official in the Sindh wildlife department.

Dolphins swam freely in the Indus until about 100 years ago when engineers under British rule started slicing up the river with irrigation projects in the dry hinterland.

The barrages pose a critical threat to the dolphins, dividing their natural habitat into five separate segments of the snaking river.

"This species used to roam across 3,500 kilometres (2,190 miles) of the Indus but are now confined to 900 kilometres (560 miles)," Bhagat said.

As a result the risk of inbreeding "could lead to infertility and then extinction," Bhagat added.

An alarming increase in pollution from untreated sewage dumps, illegal pesticides, and industrial and agricultural waste also threaten their survival.

The dolphins swim on their sides, trailing a flipper along the river bottom, and can move in water as shallow as 30 centimetres (12 inches).

But each year up to 50 dolphins get trapped in the thousands of kilometres (miles) of irrigation channels, which are closed and left to dry out.

Fishermen used to kill them but awareness campaigns have improved to the extent that they now inform wildlife officials who come to their rescue.

"People were so uneducated they used to shoot the dolphins dead until a few years ago," said Bhagat.

The trouble is that wildlife services have limited resources. Rescuers have just one van with a water tub, which they use to keep the dolphins alive for a few hours while they take them back to the river.

"We have successfully rescued 50 dolphins this season but we could do it more efficiently if we get a helicopter," Bhagat said.

Dolphins also stray into narrow channels during monsoon season when sluice gates are opened to maintain the water flow at the barrages.

Experts who did a 2006 survey for the environment ministry said the needs of Pakistan's dolphins are the same as its people -- both need a clean, reliable source of water to survive.

Mirani -- whose father worked with Swiss specialist Giorgio Pilleri who conducted pioneering research into the mammal -- said his family tradition of helping conserve the dolphins will continue.

"My son Nadir Ali is ready to assist me," he said, gesturing towards a teenager holding an oar as he steers a boat along the river.

"After me, he and his six younger brothers will try to protect dolphins," he said, before cheering loudly as a dolphin emerged to swim alongside their boat.

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