Words in English all come from other languages. The word goose is German, and did this fancy thing called strong declension to change to geese as a plural. Moose is Native American and came into English thousands of years after goose, meaning the strong declension was never applied.
In English, meats typically don't change as plurals. In English, you'd say “would you like some more salmon?” and not “would you like some more salmons?” The same concept applies to moose.