brown trout vs lake trout

brown trout

noun
  • A species of nonmigratory freshwater trout, Salmo trutta, with dark spotted skin, native to Europe and Asia. 

lake trout

noun
  • A large species of trout found in lakes in North America, Salvelinus namaycush. 

  • Whiting fried in batter and served in a sandwich. 

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