Making healthy food choices when shopping in your local grocery store is never easy; the plethora of choices/products available make it difficult to navigate. Thousands of options that some can be good for you, while others not so much, despite what their labels might claim.
One of the biggest dilemmas comes at the seafood counter. Buying fish can be surprisingly complicated. Fish such as salmon and trout provide many health benefits and contain lots of omega-3 fatty acids, but the debate between health benefits and risks can go on forever. What should a shopper do? How to make the safest, healthiest, and most sustainable choice? Here are some things to consider before you buy salmon. When it comes to fresh salmon most of the things you must have in mind apply for the smoked salmon as well.
According to USDA Food Composition Database both farmed and wild salmon are an excellent source of omega-3 fatty acids, EPA and DHA. But a small fillet of wild salmon has fewer calories and half the fat content of the same amount of farmed salmon. This is because salmon farming industry intentionally fattens its fish to maximize market weight (Jacobs 2002), and as a result, a farmed salmon has 20.5% more saturated fat content.
Researchers measured the levels of industrial pollutants - PCBs and dioxins - and agricultural pesticides such as toxaphene and dieldrin. They examined a 700 fish sample, some bought in London supermarkets and some directly from Scottish farms. The highest concentrations were found in fish from Scotland and the Faroe Islands.
PCBs are synthetic chemicals that were once used in hydraulic fluids and oils and electrical capacitors and transformers. These toxins were banned in 1979, but heavy past usage has resulted in environmental contamination worldwide, especially in fish. PCBs are absorbed into the bodies of fish which means that bigger fish who eats smaller fish accumulate greater and greater concentrations of PCBs in their flesh and can reach higher levels than those in the water itself. Farmed fish are actually fed the flesh of wild-caught fish. And as it is mentioned above farmed salmon has twice the fat of wild salmon, and this fat collects even more toxins. In Ireland, Scotland, British Columbia, and Alaska studies show higher concentrations of dioxin-like PCBs in farmed salmon than in wild salmon (Easton et al. 2002, FSIA 2002a and 2002b, Axys 2003, and Jacob et al. 2002). Human cancer risks associated with consumption of farmed salmon contaminated with PCBs, toxaphene, and dieldrin are higher than cancer risks associated with consumption of similar quantities of wild salmon. As a result, risk-based consumption advice for farmed salmon is more stringent than consumption advice for wild salmon (Hites et al. 2004a).
The most potent dioxin congener, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is classified by the International Agency for Research on Cancer as a group I carcinogen (known to cause cancer in humans), a classification that was reconfirmed in 2004 (Steenland et al. 2004). The U.S. Environmental Protection Agency (EPA) has classified TCDD as “carcinogenic to humans,” and the agency has characterized complex mixtures of dioxins as likely human carcinogens (U.S. EPA 2002). TCDD increases the risk of all cancers (Crump et al. 2002), including soft-tissue sarcomas (Kang et al. 1987), lung and liver cancers (Steenland et al. 2004), and breast cancer (Warner et al. 2002)
The bottom line is that both wild and farmed salmon contain contaminants, but wild salmon has lower levels and is considered safer overall.
When it comes to farmed Salmon antibiotics is a huge issue. This was a big source of debate in the late 1990s and early 2000s, when Chilean salmon imports to Japan had higher antibiotic amounts than allowed under regulations. The concern: Too much exposure to antibiotics could lead to resistance to their effects. Antibiotic use in farmed fish is said to have been reduced, but it is unclear just how much use is still occurring.
The nemesis of the farmed Atlantic salmon, Sea lice
The Scottish salmon farming industry is facing major problems from sea lice, small marine parasites that occur naturally on many different species of fish. The problem is not new, chemicals have been extensively used, but lice are becoming increasingly resistant. Last year more than 175,000 salmons died when a lice treatment process at Scottish fish farms went disastrously wrong. The industry has admitted it has a serious problem, and is spending at least £30 m a year on measures to respond to it. Scotland has by far the highest incidence of sea lice. In a survey published last year, the share of affected sites went from 28% in 2014 to 49% in 2015. That is while the Norwegian level remained at 5% and in Irish fish farms it went form 8% to 18%. The amount of hydrogen peroxide, a chemical treatment to combat sea lice, rose by 15 times between 2011 and 2015, reaching 42 lt of bleach per tonne of fish produced.
But it is not only about the use of chemicals, salmon farms are frequently overrun by diseases and parasite outbreaks and they pollute the surrounding environment. The parasitic sea louse is particularly harmful, reaching plague proportions around salmon farms and latching on to juvenile wild salmon as they pass farm cages on their seaward migration. Sea lice feed on the mucus, tissue and blood of their host, compromising their immune system and causing secondary infection which can have fatal consequences. A staggering number of salmons escape the cages. Despite pressure from conservation groups to improve the containment, around two million escape into the Atlantic every year and up to 40% of all free-swimming salmon, in some areas of the North Atlantic, are thought to be escaped farmed fish. Escapees spread diseases and interbreed with wild stocks, diluting their genetic integrity. Simply what’s good for farmed salmon may not be for natural ecosystems.
Producing 1 kg of farmed salmon requires 3 kg of feed, generated from species of other wild fish. This is unsustainable and makes little sense when 80% of the world's fish stocks are already severely depleted. A positive solution would be to develop more sustainable methods of aquaculture, such as rearing species that feed on primary producers like shellfish and herbivorous fish. The great irony is that farmed salmon is marketed using the iconic image of a leaping wild salmon, yet each sale of farmed salmon indirectly erodes wild stocks.
But farmed salmon is still good for health. You always have the choice to buy from the smaller, sea-based farms that are not under pressure to overstock. There are a few good organic ones that claim to have addressed all the problems. People have to judge carefully the environmental and health issues. It would be wise those to limit your consumption to no more than one meal monthly.
Eating fish is generally a smart move for your health. Eating a variety of fish should limit the danger.