、、。
Look, today we had seafood, so tomorrow let's go forage for mountain stuff, yeah?
Literal
Look, today [topic-は] sea [gen-の] bounty [copula-だった] [because-から] tomorrow [topic-は] mountain [gen-の] bounty [things-like-とか] [softener-さ], pick [to-get-に] go-[volitional-う] [emph-よっ].
海の幸 / 山の幸 (literally 'the sea's / mountain's bounty') are the stock idiomatic pair for 'seafood' and 'mountain-grown produce (mushrooms, wild greens, game).' The volitional 行こう marks an invitation ('let's go'). 取りに行く combines the masu-stem of a verb + に行く to mean 'go in order to V' — here 'go to gather.' とか marks one example among possibilities, and the scattered fillers さ・よっ give the line the exact wheedling tone of inviting a friend.