I ask since I'm on a budget and find that frozen seafood from China is markedly cheaper. I've heard China has great polluted environments. In answering, consider whether the company is owned by the U.S., China. or another country.
Chinese seafood would really scare me, because the east coast of china is really really polluted. And it would not matter who owned the company, I would be more worried about the water the fish came out of. In processing the only real big thing to occur would be freezing.
My suggestion would be to stick to Alaska (salmon), Hawaii (mahi-mahi especially), and New Zealand fish sources, wild caught only (even less than farmed, anything on the East coast of the US is usually farmed and the water is worse quality).
Salmon from Alaska runs to 4$/lb occasionally, I'm not sure where you would get fish cheaper than that. Canned from costco would perhaps be a good option (you can always rinse off salt).
If you do go the chinese fish route however - choose smaller fish. Things like Dolphins are basically inedible due to the sheer amount of mercury in them from their long ocean lives (aside from killing Dolphins being morally repugnant). But smaller, faster growing, fish will have less time to accumulate pollutants.
Short answer: Never buy frozen fish from China!
I watched a TV show where they went undercover to a fish packing factory in China, posing as importers, and filmed what happens there. I don't know how the fish was raised - that's another issue - but in the factory, the fish was bathed in a chemical called STTP that makes it retain water.
At the end of the show they took samples of frozen fish, defrosted each one and collected the water, and calculated what percentage of the product was fish. One of the samples was more than 50% water, as I recall. So, it's not even as cheap as you think it is. You are paying for STTP water. Yum.
The show grossed me out. Since then I haven't bought frozen fish - certianly won't buy it from China. Here's a blog post that gives more details http://www.greenprophet.com/2010/05/frozen-fish-in-israel/
Nearly All Chinese seafood is farmed, whether freshwater or sea. Like most seafood from the US and other countries, it is likely to be contaminated with industrial chemicals. My opinion, only an opinion, is that the chance of higher pcb levels or mercury level in Chinese fish presents a smaller health risk than does metabolic syndrome or the tumor-growing properties of grain oils such as soybean oil. In other words, Chinese fish may tend to have more heavy metals, etc. but this is a marginal risk.
for most people, clean, wild ocean seafood is out of reach, as it is usually not available in stores (I have to go to a small fishing village in Baja to get mine). Eating low on the food chain, as one commenter suggested, is probably a good idea, but who wants to eat canned pink salmon and smelts? if you are cool with that, then go to an asian market where they sell the kinds of tiny ocean fish that Americans disdain. The contaminants should be less there than in the prized, filetable species in "white people" grocery stores.
Honestly, I go out of my way not to buy ANYTHING from China especially food products.
After the paint, dog food, baby food crap- I go for nothing. China allows private homes to act like a factory in producing product- stay away.
Seafood doesn't come from China. It comes from somewhere in international waters. I probably wouldn't eat frozen freshwater fish from China--their rivers are definitively filled with crap (literally). But you're talking about fish caught in the Pacific or Atlantic, flash frozen, unloaded in China and put in a cold container cargo ship back to the US. I'd be more worried about seafood that transits via the fish market in Tokyo (which handles some absurd amount of the global seafood trade daily). And since no one usually puts on the package where the fish was caught, nor where it transited to for packaging and then shipment, you're just flailing in the dark.
Sometimes you have to go by anecdotal observation. I live in a largely Asian neighborhood and often shop at the Asian supermarket, which has a ridiculous amount of fresh and frozen seafood. The locals here buy tons of fish, which they presumably consume regularly. I don't see any overt signs of chronic heavy metal poisoning or any other kind of toxicity. So I figure the fish is probably ok. These folks have been eating this seafood for decades and look healthy. If I go to the big box white people market or to the Mexican neighborhood a few miles away, everyone who eats that food looks obese, metabolically disordered and otherwise sick (ok, not everyone, but a lot of them). So if I eat that stuff, I'll probably get sick too. If I go to the hippy market that sells raw milk and grass fed beef, everyone starts looking healthy again (even the damn grain eaters). So, don't source your fish from oh, Albertson's and don't eat Mexican food everyday, and you'll probably live a long, healthy life is the moral of my story.
Glither, that's some interesting information. Generally, to buy frozen seafood costs less than fresh for multiple reasons. The biggest is reason being that shipping and preserving the quality of fresh seafood is very costly as spoiling can start within a matter of hours. Frozen seafood, however, is usually flash-frozen upon being caught. If you don't trust the country of origin of the fish, look for brand that you know are caught off the coast of the U.S. It's still cheaper than buying fresh and you know what you're getting.
About this STTP chemical. wikipedia makes it out to be not particularly a cause for alarm health wise:
"Polyphosphates are hydrolyzed into simpler phosphates, which in moderate amounts are nutritious. For example, ATP, a related derivative of triphosphate, is essential for life. Thus, the toxicity of polyphosphates is low, as the lowest LD50 after oral administration is >1,000 mg/kg body weight. Similarly, no mutagenic or carcinogenic effects nor reproductive effects have been noted. Salts of polyphosphate anions are moderately irritating to skin and mucous membrane because they are mildly alkaline"
However, the safety sheet of this chemical says its quite harmful to the lungs. It doesn't mention if that is only for inhalation or could be true via ingestion:
Potential Acute Health Effects: Very hazardous in case of eye contact (irritant). Hazardous in case of skin contact (irritant), of ingestion, of inhalation. Slightly hazardous in case of skin contact (sensitizer, permeator). Inflammation of the eye is characterized by redness, watering, and itching.
Potential Chronic Health Effects:
CARCINOGENIC EFFECTS: Not available.
MUTAGENIC EFFECTS: Not available.
TERATOGENIC EFFECTS: Not available.
DEVELOPMENTAL TOXICITY: Not available.
The substance is toxic to lungs. Repeated or prolonged exposure to the substance can produce target organs damage.
Of course, the precautionary principle always applies.
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