Spanish mackerel vs jack mackerel

Spanish mackerel

noun
  • Any member of a tribe of mackerel (Scomberomorini) 

jack mackerel

noun
  • Any of various edible fish, especially of genus Trachurus, but also genera Caranx, Acanthocybium and Euthynnus. 

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