Ok just a thought.
Given the world problem with plastics at sea why not lead the world and advertise your game as being the first to address the issue and bring players attention to this global problem?
While ships are catching fish or crustaceans why not allow the ships to actually help the environment by collecting plastic as they go about their work?
You could put in a building that would recycle the "goods" or if that's not possible just skip to having x amount of plastic appear in your inventory.
It could end up being really good advertising and PR bringing in more players.
Ed