trawler vs trolling

trawler

noun
  • A fishing boat that uses a trawl net or dragnet to catch fish. 

  • A fisherman who uses a trawl net. 

trolling

noun
  • A fishing technique in which one or more baited fishing lines are dragged by a moving boat. Not to be confused with trawling, which drags a net. 

  • The act of one who trolls (in various senses). 

How often have the words trawler and trolling occurred in a corpus of books? (source: Google Ngram Viewer )