Dhaka, Bangladesh: Bangladeshi conservationists introduced two rare river-dwelling crocodiles to potential mates Sunday in a last-ditch attempt to save the critically-endangered species from extinction.

A 36-year-old female gharial — a fish-eating crocodile once native to rivers across the Indian subcontinent — was brought from a zoo in northeast Bangladesh to the capital Dhaka, where it is hoped she will mate with an older male to repopulate the species. 

A separate 40-year-old male was returned to the zoo in Rajshahi where there are only females.

Gharials can only breed until the age of 50 and as the small captive population in Bangladesh ages, conservationists decided intervention was needed if the species was to have any chance of survival.

‘This is our last hope to rescue the critically-endangered gharial from total extinction,’ Sarowar Alam, who heads the International Union for Conservation of Nature's Bangladesh gharial project, told AFP.

‘We're hopeful we'll get some results, even though there are fears these adults gharials may have lost the urge to mate.’

Bangladesh, with its vast network of rivers, was once a key habitat for the gharial, a crocodile distinctive for its large body and long thin snout.

But today they are virtually extinct in Bangladesh and the few which are seen likely made their way downstream from India.

There has been no sighting of gharials in Bangladesh's two Himalayan rivers — the Ganges and Brahmaputra — in more than a decade.

The species has also all but vanished from its erstwhile habitats in Pakistan and Bhutan, with fewer than 200 existing in rivers mainly in India but also Nepal.

There are 11 captive gharials in Bangladesh, officials say, and if the breeding programme is a success it is hoped the infants can be released back into the wild.

‘This is the first time we've decided to exchange the gharials among zoos so that they can mate and breed,’ Jahidul Kabir, the government's conservator of forests, told AFP.

The Padma and Jamuna rivers, the main tributaries of the two Himalayan rivers, have been identified as potential sanctuaries for the species should it repopulate.     

Conservationists have built artificial sandbanks in the zoos for the breeding exercise. Though gharials spend most of their time in water, sandy banks are essential for building nests and basking.