pickerel vs wels catfish

pickerel

noun
  • A freshwater fish of the genus Esox. 

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

  • A wading bird, the dunlin. 

wels catfish

noun
  • Silurus glanis, a scaleless fresh-water catfish recognizable by its broad, flat head and wide mouth. 

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