pickerel vs walleye

pickerel

noun
  • Walleye, A species of gamefish, Sander vitreus, native to the Northern U.S. and Canada with pale, reflective eyes. 

  • A freshwater fish of the genus Esox. 

  • A wading bird, the dunlin. 

walleye

noun
  • A species of gamefish, Sander vitreus, native to the Northern U.S. and Canada with pale, reflective eyes. 

  • One or a pair of sideways-looking misaligned eyes. 

  • An unusually pale eye. 

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