If there are people being trafficked it's unlikely they would be in a container. They would be on the ship for the water trip. There is enough storage on container ships for months of food, I doubt food is the issue it's that a storm could come anytime and smash those ships together.

If containers are finished out they could be survivable but they have to be plumbed and have ac. More likely they keep prisons below, those ships are the size of small towns, some with pools, movie theaters, gyms, and large cafeterias. You can travel on container ships although I have no idea why someone would. It takes 90 days to get somewhere you can be in 24 hours. Of course now you have to be jabbed, I checked.