Atlantic pollock vs coalfish

Atlantic pollock

noun
  • European pollock, Pollachius pollachius. 

coalfish

noun
  • any of several blackish fish, especially Pollachius virens, a pollack, and Anoplopoma fimbria, sablefish. 

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