I eat a fair amount of tuna, and recently got to thinking that I don’t know a whole lot about it. And that’s no good. So, let’s have all the tuna knowledge we can.
What species are used for canning? how many species are there? Where does canning take place (on ship? nearest canning factory? shipped as is to wherever it’ll be sold and canned there?) Most of the cans I buy are rom Asia (Thailand, Philippines etc), is this because tuna are more abundant in those areas or is it a cost thing? How is the tuna population kept high enough to sustain the industry like it does? is tuna farmable? if not, how over-fished is tuna (as in, how close to wiping it out are we)?
As far as the canning process itself goes, is “shredded” tuna more likely to contain more than just tuna? do “dolphin-friendly” labels mean anything or is that now just part of the label design template?
crap I thought I had more. If anyone else does, please add!
(links to resources will be appreciated, I haven’t been able to find much of use myself)
‘Dolphin friendly’ tuna is typically caught on lines with hooks, as opposed to large nets which trap and harm other species such as dolphins.
On problem with eating tuna (or indeed any long-lived or predatory fish) is that the flesh can contain elevated levels of toxic heavy metals and other pollutants; I believe that for most canned tuna, the mercury and cadmium content is sufficiently high that a can a day would take you above the recommended safe level.
Fish that contain mecury: It occurs naturally in some fish and does not reflect on humans.
Recent studies (and I’ll see if I can find them), do not show a correlation between mercury and health or birth defects…although pregnant women have been advised to cut back on tuna and other species of fish in which mercury occurs naturally.
Mangetout seems to hint that mercury is a pollutant, when in fact it is not as it relates to tuna and some other fishes. It occurs naturally in many fish.
Some Dolphin safe tuna is not hook caught, but caught in nets that are approved.
Indeed, but Tuna are relatively long-lived predatory/carnivorous, with a significant amount of their diet being based on adult organisms, including filter-feeding molluscs, which tend to be accumulators of heavy metals themselves - resulting in generally higher levels of mercury in tuna than you might expect to find in shorter-lived fish that subsist on other diets.
Wait, I thought there were just some new findings about mercury in tuna, and that guidelines (at least for children) had been revised. There was some stink because the FDA didn’t advertise them, or something.
By any useful or reasonable definition, mercury is a pollutant. It is harmful (mostly for developing children and fetuses), and because of human activities is present at levels high enough to be dangerous – higher than would otherwise be found as normal background levels.
Mercury reaches fish mostly because burning coal and trash puts mercury into the air, where it falls into water bodies. It is then concentrated into top predators, such as tuna, swordfish, etc. Many fresh-water species (trout, etc.) also contain elevated levels of mercury.
How much mercury is there in tuna? Bottom line: if you’re an adult, and not going to be pregnant, you probably don’t need to worry about it. If you are a child or having one, then you probably don’t need to avoid tuna all together, but it would be smart to limit the amount you eat. There’s no scientifically defined ‘safe’ amount; it all comes down to how much risk you want to take. Me, personally, I would keep it down to one or two steaks a month at most or canned tuna no more than once a week at most. Remember swordfish and others count, too, and freshwater fish as well.
Counter to what one might think, shellfish and other filter feeders have much lower levels and are basically safe as far as mercury goes.
Look, we humans affect the environment, but we don’t have to take the mercury issue and turn the cheek. Mercury is in fish not because of bad humans pouring mercury into oceans.
Whenever the mercury in fish thing comes up, people ge the blame.
Yeah, pollutants occur naturally, but people hear pollutant and blame all of mankind.
Have humans contaminated anything with mercury? Sure! But the issue with fish is that they contain it naturally.