grilse vs spawner

grilse

noun
  • A young salmon after its first return from the sea. 

spawner

noun
  • A female fish, often specifically a salmon, which is physiologically ready to spawn 

  • An object in a simulated game world that spawns further objects. 

  • A program which spawns objects or processes as needed 

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