As hundreds of fishing boats set sail deep into the sea on Tuesday after the end of the three-and-half-month fishing moratorium for the South China Sea, local governments in China’s southern coastal regions tightened anti-epidemic measures for fishermen, including prohibiting contact with overseas personnel and boasts, to avoid importing COVID-19.

Such strict measures were rolled out after trade with overseas fishermen was reportedly suspected of having triggered the COVID-19 outbreak in Sanya, South China’s Hainan Province earlier this month.

Many places in South China’s Guangdong Province have been cautioning fishermen about the risks of COVID-19 infection before the end of the summer fishing ban.

People on each fishing boat should have their health codes and temperature checked before going out to sea, according to a notice sent to residents in Guangdong’s Shantou, which was provided to the Global Times by a local official on Tuesday.

The notice stated that fishermen are prohibited from contact with people or boats from overseas, as well as people from medium- and high-risk areas in China. If they had contacts with any of these people, they should report to the local government.

Fanyu district in Guangzhou, capital of Guangdong, even converted a ship into a nucleic acid testing point, so that fishermen can be tested before they return to port. Those fishermen can only go ashore if their tests results are negative, according a Fanyu district government notice.

Beihai city in South China’s Guangxi Zhuang Autonomous Region, which also faced an outbreak of COVID-19 in July that stranded more than 2,000 tourists, announced on Tuesday plans to return to “normalized COVID-19 control and prevention” when cases ebb. Fishermen in Beihai need to show their green health codes (which indicate the person is safe from COVID-19 and not a close contact), along with a 48-hour valid nucleic acid test, before returning to work.

Such strict measures on fishermen came after Sanya, a tourist hub in South China’s Hainan, saw a COVID-19 outbreak earlier this month, which, some media reports suggested, might have been triggered by fishery trade with people from overseas.