Chief Minister V Narayanasamy told reporters yesterday that the 18 people - three crew members and 15 ornithologists from Puducherry, Chennai and Mumbai - had ventured into the sea in the mechanised vessel from the harbour here on Sunday night.
After the vessel travelled 15 nautical miles, it developed a technical snag. The people aboard contacted their friends and relatives on the shore who alerted the police.
The police then sought the services of the Coast Guard.
An inquiry found the vessel lacked basic communication equipment, Narayanasamy said, adding that the police was probing the incident.
The chief minister urged people heading to the sea in private boats to first check whether the vessels were well equipped and whether their owners had the required permission.