While the cat is long since out of the bag. It was through ports that the Chinese spread this virus to most countries. Faroe Islands, The Maldives, and the Canary Islands all got the virus early last year, as did most ports that dealt with Chinese vessels. Besides Chinese students, it was the world wide system of ports that China used to spread the virus to every corner of the globe.
That being said. I am not sure there is any use for masking the fishermen now. Nor do I believe masks were ever useful.
Problem is there could be some Karen out there that would report them to Walter Peck at the CDC and he shut the boat down or fine them. So it needs to be addressed.