Truth is more nuanced than that. Japanese have a native word 'sake' for the native salmon that is hardly eaten nowadays. They definitely use the word sake for imported salmon too, especially if its cooked ( because thats how they usually eat the ol native salmon too) They tend to call raw salmon 'sahmon' though.
I dont know if its a folk wisdom but the following article claims that when they hear the word sake they think of that old native salmon.
Sort of like when you might call any old man 'Gramps' but when you hear 'Gramps' you think of your own grandfather?