It is not surprising that these kinds of conditions exist on fishing vessels - you start to treat your fellow human animals the same way you treat other animals. "Fishing," which is really planetary-scale sea foraging, as Jeremy Jackson points out, is incredibly cruel to everyone involved. If you do not already shun seafood because of the massive amounts of mercury and other toxin pollution, maybe consider the ethical problems, and start advocating for a total ban on commercial fishing.

Watch this talk by Jeremy Jackson if you still think that seafood is somehow "ok": https://www.youtube.com/watch?v=2zMN3dTvrwY