steelhead vs togue

steelhead

noun
  • The anadromous form of the rainbow trout, Oncorhynchus mykiss. 

  • The ruddy duck. 

togue

noun
  • Lake trout, Salvelinus namaycush, a freshwater char of northern North America. 

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