Land based krill aquaculture as a food base for a civilization that is destroying itself via over consumption. The logic is: Grow some simple, fast life cycle organisms that eat algae but contain enough nutrients to feed the biggest mammal on the planet. And you essentially have giant vats of them fed by algae and saline water (farming on an inland salt plain? Desalinates and all!). You grow them, drain the water, recycle through the system like a giant aquaponics system (the effluent of the krill is food for the algae), then dry or press the krill depending on what you’re trying to do.
Sell to the aquaculture industry as food, the vitamin supplement industry (krill is high in omega 3), and start experimenting with creating food supplements for humans using it. They are, after all, like tiny crustaceans.