They have two net reels aft and probably another net reel or two further forward that we cannot see. This vessel probably only tows one net at a time. You can see the chaffing bars and “pockets” at the stern quarters where the doors are normally pulled up and stored.
The odd thing about this boat is that the trawl blocks for the trawl wires are mounted so high up on the stern gantry.
The only ways to trawl without doors are a “beam trawl” or “pair trawling where two boats tow one net.
Pair trawling is another European fishing method. It has been done in North American, but not at any great scale. In fact, I haven’t heard much about it in recent years.