Any vessel encountering a fleet of vessels fishing in close proximity to one another, would be well advised to alter course and pass well clear of the entire fleet. It is nearly impossible to predict what individual fishing vessels will do next, and their crew have enough to deal with without worrying about non-fishing vessels.

	In addition to their usual lights, trawlers may display two white lights. The practical difficulty is identifying the special signals amongst the working lights. A vessel shooting nets is less of a danger than a vessel hauling nets and has no red lights.
This is not a trawler with a pilot aboard! A vessel hauling nets is more dangerous to other vessels because their attention is on their catch, not their course. So they have the red light in the extra signal.
	This vessel is not making way, so it has no side or stern lights. The two red lights can be related to the two red lights for a vessel not under command.
A purse seine vessel has a large net which is towed out in a circle, usually by a smaller craft. The net is closed at top and bottom by hauling in ropes. The net may be of considerable size! This vessel is not making way and has no side or stern lights.
	Vessels pair trawling are towing one net, they keep their distance constant with a cable between the two vessels.