What is the name of the fishing boats that drag large fishing nets behind them?

Traditionally, trawlers were known as working man’s boats. They had deep hulls for icing down/storing fish and got their name from what they do: drag a trawl net to catch fish (AKA trawling).

A fishing trawler is a commercial fishing vessel designed to operate fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing nets that are pulled along the bottom of the sea or in midwater at a specified depth. A trawler may also operate two or more trawl nets simultaneously (double-rig and multi-rig).

Modern trawlers are usually decked vessels designed for robustness. Their superstructure (wheelhouse and accommodation) can be forward, midship or aft. Motorised winches, electronic navigation and sonar systems are usually installed. Fishing equipment varies in sophistication depending on the size of the vessel and the technology used.