The subject of ocean fish is surrounded by a veritable sea of confusion: doctors tell you that it's essential for your health, while social media persistently urge to avoid it, since it is presumably radioactive and full of mercury and plastic. So what should all lovers of tuna and swordfish out there do?First, let’s stress that fatty ocean fish, like tuna and salmon, is the best source of omega-3 and omega-6 fatty acids. They are necessary for the brain function and memory, they reduce the levels of bad cholesterol and help prevent heart disease (for more benefits of omega-3 and -6, see here). But there’s a downside.
On the matter of mercuryThe main argument against ocean fish is that it’s laden with mercury. Humans release lots of mercury into the environment: the main culprits are burning of coal, smelting of iron ore, and garbage incinerators. Mercury ends up in rivers and oceans, where it is ingested by plancton, which is eaten by small fish, to be gobbled up by predator fishes. And since one of its forms – methylmercury – does not break down well in salty water (more details here), the concentration of mercury in ocean fish turns out to be much higher than in freshwater fish. According to medical studies, excessive levels of mercury in humans lead to issues with cognitive function and memory; and too much mercury in the body of a pregnant woman presents high risks for the baby. Ironically, a lack of omega-3s is also bad for your cognitive functions and memory! So what should we do? The key is to reduce mercury emissions into the atmosphere – most Western countries participate in various agreements on the subject. Meanwhile, you can check the levels of mercury in various species of fish here.
The plastic problemHumans release over 8 million tons of plastic into the ocean annually. But why would fish eat plastic? As it turns out, while plastic isn’t biodegradable, sunlight does break it down into tiny pieces. And as researchers have found, this half-degraded plastic smells really good to fish, even better than the plancton they usually eat. Many species of fish and shellfish actually prefer it to real food! Does it mean we are eating plastic together with fish? Short answer is yes; however, the amounts we ingest are so small that they cannot harm us… so far. If the amounts of plastic dumped into the ocean keep rising, eventually plastic in our fish may become a health hazard.
Radioactive fish?Finally, let’s mention a social media scare that ocean fish has become radioactive after the 2011 Fukushima nuclear plant disaster. At least here you don’t have to worry: according to scientists, the amount of radioactive isotopes in ocean fish is so tiny that it cannot possibly harm you.
As you see, mercury is the only real cause for concern, but it is not a good enough reason to stop eating tuna. Rather, seek out guidelines for safe fish consumption specific to your area. As for the rest, it is up to the governments and all of us to reduce emissions – helping the fish and ourselves.