TAIPEI, Taiwan (AFP) — Thousands of Chinese fishing boats have been massing in geometric formations in the East China Sea, in coordinated actions that experts believe are part of Beijing’s preparations for a potential regional crisis or conflict.

Monitoring ship-tracking data on Christmas Day, Jason Wang could tell something “unusual” was underway as fishing boats swarmed into two parallel inverted Ls, each about 400 kilometers long.

Wang could see the roughly 2,000 fishing boats among the many thousands of vessels that ply the busy waterway through their automatic identification systems — a GPS-type signal that commercial ships use to avoid collisions.

The vessels, which were as close as 500 meters to each other, held their positions for about 30 hours in near gale-force winds and then suddenly scattered.

“Something didn’t look right to me because in nature very rarely do you see straight lines,” said Wang, chief operating officer of ingeniSPACE, which analyzes satellite imagery and ship signals data.

“We’ve seen like two, 300, up to a thousand (Chinese fishing boats congregate), but anything exceeding a thousand I thought was unusual.”

Maritime and military experts told Agence France-Presse the massing of Chinese fishing boats on 25 December, about 300 kilometers northeast of Taiwan, was on a scale they had never seen before.

Another incident detected in early January involved around 1,000 Chinese fishing vessels clustered in an uneven rectangle, about 400 kilometres long, for more than a day in the same area of the East China Sea.

Hundreds of those vessels were also detected in the 25 December event, Wang told AFP in an interview in Taipei.

Last week, around 1,200 boats massed in two parallel lines further east of the January and December events and held their positions for about 30 hours, Wang said.

China’s massive fishing fleet operates in the Yellow Sea, East China Sea and the South China Sea, competing with fishers from Japan, South Korea, Taiwan, Vietnam and the Philippines.