Thousands of Chinese Fishing Boats Quietly Form Vast Sea Barriers

China quietly mobilized thousands of fishing boats twice in recent weeks to form massive floating barriers of at least 200 miles long, showing a new level of coordination that could give Beijing more ways to impose control in contested seas.

The two recent operations unfolded largely unnoticed. An analysis of ship-tracking data by The New York Times reveals the scale and complexity of the maneuvers for the first time.

Last week, about 1,400 Chinese vessels abruptly dropped their usual fishing activities or sailed out of their home ports and congregated in the East China Sea. By Jan. 11, they had assembled into a rectangle stretching more than 200 miles. The formation was so dense that some approaching cargo ships appeared to skirt around them or had to zigzag through, ship-tracking data showed.