Why trawlers suit anti-smuggling patrols

Why would trawlers be used for anti-smuggling operations?

They can work close inshore and blend among the fishing-type vessels that smugglers are likely to use.

Access and discretion are the main advantages of trawlers in anti-smuggling work. They can operate close to shore where larger warships may be constrained. Smuggling craft are also likely to resemble fishing or working boats, so a trawler does not stand out in the same way as a naval combatant. Constabulary missions can reward local access and visual ambiguity more than speed or heavy armament.