The Guardian gives Walmart, Costco, and Aldi seafood shoppers something to consider while they debate de-veined or not, and individually quick-frozen options: Slaves, basically, working "for no pay for years under threat of extreme violence" may have been involved in the production of the shrimp going in your cart. The paper says its six-month investigation uncovered Thai slave ships with "20-hour shifts, regular beatings, torture and execution-style killings," and at least one human literally quartered by boats. It says these ships sell the fishmeal that the world's largest shrimp farmer, Charoen Pokphand Foods, uses at shrimp farms that subsequently supply frozen and cooked shrimp to several major retailers.
Essentially, the fishmeal industry collects vast amounts of otherwise inedible "trash" fish that's ground up in factories that sell to large shrimp farming operations. Every paragraph of The Guardian report is worth a close read, but the nutshell version, as one human-rights worker puts it, is "If you buy prawns or shrimp from Thailand, you will be buying the produce of slave labor." All of the retailers named in the investigation say they're actively fighting to end human trafficking in the region, although, in what amounts to perhaps the least reassuring part, a Charoen Pokphand Foods rep says: "We know there's issues with regard to the [raw] material that comes in [to port], but to what extent that is, we just don't have visibility."