Hand to stretch a little to get the pun to work

酒 /sake/ is the alcohol - both the drink known as sake, and alcoholic beverages in general.

鮭 'salmon' can be both /shake/ and /sake/.

Here, Ido has written it using kana in in first plane (and Pola's line in the second) - even though with the verb 'to drink', it's obvious that it's the drink, but still.

The first panel is literally just 'Gonna drink booze~'; had to use the phrase there to link it with the salmon later.

Thankfully, it's not too dissimilar from the original Japanese that it's a different joke or anything. Lucky that.

/explaining the joke