Smokey the Salmon

From Muppet Wiki

Smokey the Salmon takes a moment out of his anadromous lifestyle to provide Grover and his friends with a turgescent supply of litter that his lake has accumulated via an amalgamation of negligence and aggressive despoilment of nature's habitat in Sing-Along Earth Songs.

His name is a take on that of Smokey Bear (even using a variation of the familiar catchphrase: "Only you can prevent pollution"), while also serving as a play on words of the favorite seafood dish: smoked salmon.