Fishing vessels greater than 20m in length, when engaged in trawling, shall exhibit lights to indicate which operation they are conducting. What operations do the night and day lights indicate?

Fishing vessels that are greater than 20 meters in length and engaged in trawling must follow specific lighting requirements to indicate their fishing operations. At night, these vessels display a particular combination of lights—two green lights in a vertical line—when actively trawling. This signaling helps other mariners identify that the vessel is engaged in this specific operation, which is crucial for safety at sea, as it alerts nearby vessels of the trawling activity and the potential presence of gear in the water.

During the day, these vessels are required to show shapes, such as two cones with the apexes touching, to denote their trawling activity. The dedicated light and shape indicators are designed exclusively for trawling rather than encompassing all fishing activities, which may require different signaling. Hence, the correct answer explicitly indicates that the specific operation being performed is trawling. This importance lies in the need to clearly communicate the nature of the vessel's activity to avoid collisions and ensure safety on the water.