Vanuatu authorities have confiscated passports for 15 Fijian and 24 Chinese nationals for allegedly breaching their tourist visas.
The visitors were reportedly involved in harvesting sea cucumbers.
The agriculture department says under Vanuatu laws, it is illegal for foreigners to be employed and the penalty of the breach of visa conditions is just over 2,000 US dollars.
The fisheries department has given right to the local people in the islands affected by cyclone Pam to harvest sea cucumbers in orders to help them financially.
It says it issued 10 licenses for the harvesting season.