There were about 25-50 fishing boats in Cat Ba Island, registered in September each year to go fishing in the southern waters of Bạch Long Vĩ, were allowed to anchor at the island to avoid monsoons. Most of the fish caught were transported to Cat Ba Island, a part was sold locally and a smaller part was sold to Hainan Island (China). Abalone was a valuable sea product that was bought by Chinese merchant boats and sold to Guangdong (China). However, later, there was an order that the exploited abalone could not be sold to China, but only sold in Vietnam.