A pile of dead baby sharks was found during a raid on a house in Fraserganj, a coastal pocket near the southernmost tip of Bengal, on Thursday.
Two persons were arrested, said forest officials.
"More than 45,000 sharks were kept in 70 crates. The total weight would be around 1.4 tonnes (1,400kg). Baby sharks often end up trapped in fishing nets but such a huge haul is rare in the state," said a forest official.
Sources said an initial probe suggested that the house was a transit destination and the consignment was headed for southeast Asia.
"Based on a tip-off, a raid was conducted at 12.40am on Thursday at Baliara, Fraserganj. Seventy crates of semi-processed baby sharks were seized. Two persons, Akash Das and Ranjit Bag, were arrested," said Milan Mandal, divisional forest officer of South 24-Parganas forest division.
The two persons were produced in a Kakdwip court on Thursday. They have been sent to jail custody for seven days.
Sharks are one of the most threatened marine animals. India has around 150 recorded species of sharks.
Under the Wildlife (Protection) Act 1972, fishing and trading in sharks are punishable only for a few species.
"The baby sharks that were found are protected under the Wildlife Protection Act," said Mandal, the DFO.