More mpreg shenanigans!
Jimmy is generally better at cooking than Jag. Jag used to be pretty terrible at it, but he learned to cook some simpler meals over the years. He catches all the fish they eat by hand. I mean tentacle.
They basically live a self-sustained life and could exist indefinitely on that island. Jag's a walking bio filter & food processor, he could stuff Jimmy's blood with pre-chewed nutrients & filtered water if he absolutely had to.
Or Jag could stash Jimmy & swim to shore any time he wants. He's a water affine creature, enjoys swims in the sea quite a lot.