On May 1, China instituted its annual moratorium on commercial fishing in the waters Beijing claims in the Yellow/Bohai Seas, East China Sea, and South China Sea above the 12th parallel (including Scarborough Shoal, the Paracel Islands, and the Gulf of Tonkin, but not the Spratly Islands or the southern reaches of the nine-dash line). The ban applies to both Chinese and foreign fishing, including in disputed waters. China has enforced a unilateral ban each year since 1995, though in previous years the start dates were different for each region, making the overall bans slightly shorter. This year the moratorium will end on August 1 in the East China Sea, August 16 in the South China Sea, and September 1 in the Bohai and Yellow Seas.

Each year the moratorium sparks anger among China’s neighbors and feeds into the cycle of tensions between regional law enforcement and fishing fleets. Sometimes-violent incidents are a year-round problem between Chinese fishermen and their neighbors from South Korea, Japan, Taiwan, and Southeast Asia, but the fishing ban introduces a unique set of dynamics. With the start of the moratorium, most of China’s small- and medium-sized commercial fishermen return to port (the larger fleets operate elsewhere around the world), but many ships also head south of the 12th parallel, leading to increased run-ins with neighboring coast guards in places like the Spratlys and off the coast of Indonesia.

The most noticeable effect of the ban each year is the spike in clashes between the Chinese Coast Guard and Vietnamese fishermen in and around the Paracels. Hanoi decries the moratorium as a violation of its claimed sovereignty over the islands and a breach of the Gulf of Tonkin fishery agreement the two countries reached in 2000. Vietnamese fishermen and local government officials have historically reported an uptick in harassment, arrests, and even kidnapping by Chinese law enforcement during the summer as Vietnamese fishermen, with the implicit support of Hanoi, flaunt the Chinese ban.

The ban has also historically been applied to Scarborough Shoal, which has been a sore spot for Manila. Beijing’s enforcement of the moratorium at Scarborough was deemed illegal by the arbitral tribunal at the Permanent Court of Arbitration last July, with the judges ruling that Chinese, Filipino, and Vietnamese fishermen are all entitled to historic fishing rights at the shoal. It is unclear whether Beijing is giving Filipino fishermen at the shoal a pass during this year’s ban as part of the “gentlemen’s agreement” Presidents Xi Jinping and Rodrigo Duterte reached in October.

The lifting of the ban in the East China Sea in August coincides with the start of prime fishing season in that area. Chinese fishermen return to disputed areas, including around the Senkaku Islands, in large numbers, sparking an uptick in run-ins with the Japanese Coast Guard. Last year, a flotilla of hundreds of Chinese fishermen entered the contiguous zone and, in many cases, the territorial sea around the Senkakus, accompanied by Chinese Coast Guard vessels who refused Japanese demands that they withdraw. This August could see a similar use of the Chinese fishing fleet for political ends.

Media has described this year’s ban as stricter than previous iterations, not only because of the longer duration of the moratorium but because China has expanded the types of fishing and support activities that fall under the ban. Reporting on its implementation has so far been sparse, though it is unclear if that is because Beijing is taking a gentler approach amid its current charm offensive or because regional states, particularly the Philippines and Vietnam, have been hesitant to report on incidents. But the historical trend suggests that the ban, and its rescinding in August, bear watching closely.

Header photo by Billy H.C. Kwok / Stringer, from Getty Images AsiaPac