¿Habla usted inglés? If there's so much as one left alive it isn't extinct.
They divide them up by what tributary of what river they spawn in and if one area for some reason is no longer usable they will say that Salmon is extinct.
They do the same thing with other animals, if they are not in a certain place then they are extinct even if they are over populating the land just a mile away.
That is how they can say an absurd number of species have "gone extinct" every year. They didn't. They just moved.