prodigal son vs spring salmon

prodigal son

noun
  • A marine fish, the cobia (Rachycentron canadum). 

  • Someone who returns home from travelling or exile or who is welcomed back after disgrace, especially having repented of former extravagant or immoral behaviour. 

spring salmon

noun
  • A chinook salmon; especially an average-sized one (less than 13.5 kg). 

How often have the words prodigal son and spring salmon occurred in a corpus of books? (source: Google Ngram Viewer )