New Delhi, March 22 (IANS) Animal rights activist group People for the Ethical Treatment of Animals (PETA) has written to Environment Minister Jairam Ramesh urging him to scrap plans to build a dolphinarium at the National Zoological Park here.

Dolphins, declared as India's national aquatic animal last year and found in the Ganga river, are a rare species and the environment ministry estimates only 2,000 of them are left now.

PETA critisised the National Zoological Park's proposal for a dolphinarium which is awaiting the environment ministry's clearance, saying that dolphins are highly sensitive and complex animals who can't survive in small tanks.

'Most captive dolphins die prematurely. When confined to small tanks they swim continuously in circles and the sonar waves they use to communicate with, bounce off cement walls and are useless reverberations,' said PETA's Dharmesh Solanki.

In its letter to the minister, PETA has cited a study that says that more than 80 percent of captive dolphins died before the age of 20. In the wild, dolphins can live into their 40s and 50s. Most captive dolphins live to only half the age of wild dolphins, Solanki said.

'Wild dolphins live with natural family pods and have the opportunity to play, mate, and seek as well as choose their own food. Earlier this year, scientists studying dolphins' high intelligence recommended that the animals be treated as 'nonhuman persons',' Solanki added.

'The oceans and their natural habitat must be protected and dolphins do not deserve to be jailed for life in small enclosures that, to them, are like bathtubs,' he further said.

Dolphins were once common sight in the Ganga, but they are rare today. They were found in large numbers a few years ago, but their number has come down drastically now due to fishing, poaching, sand mining and massive deforestation.