India has banned hunting sharks for only their fins in a move to protect endangered species from indiscriminate hunting for parts wanted abroad.

The practice of shark 'finning', or slicing off a shark's fins and throwing it back to die slowly on the ocean floor from starvation or inability to move, has exploded worldwide due to demand from China, where shark fin soup is considered a delicacy.

India lists several of the dozens of shark species in its waters as endangered, including hammerheads, broadfins and whale sharks.

Under the Environment Ministry's new policy, announced Monday, fishermen now found with hauls including detached fins risk up to seven years in prison for hunting an endangered species since identifying species by fins alone is difficult.

Worldwide, sharks are in sharp decline, with some species' numbers now 10 per cent of what they were three decades ago. Their demise threatens the health of ocean ecosystems, experts say, as the top predators are key to keeping fish and turtle populations in check. Tens of millions are caught every year.

The growth of shark finning to feed the Chinese market has posed a major threat to the world's oldest vertebrates.

Ministry's move applauded

India is the world's second-largest shark-catching nation behind Indonesia, with the two countries accounting for 20 per cent of yearly shark catches, according to a report by the international wildlife trade monitoring agency TRAFFIC.

Most Indian fishermen catch sharks primarily for food, though they also export the bones and fins abroad. Those fins will now have to be removed once the sharks are on shore.

Last year, Indian fishermen exported $4.8m in shark fins to China, less than half the $11.3m in 2010 exports despite steady demand, according to data from India's Marine Products Export Development Authority.

"Fishermen are saying the numbers of sharks they've been able to catch has definitely come down," said C. Samyukta of Humane Society International.

Conservationists applauded the ministry's move as key to ending a cruel practice threatening to push some shark populations to the brink.

"Given the perilous status of many shark species, we urge the state governments to act quickly and work to enforce the policy," said Belinda Wright of the Wildlife Protection Society of India.