ow fat levels and to its high Omega-3 fatty acids content. According to reports in the journal Science, however, farmed salmon may contain high levels of dioxins. PCB (polychlorinated biphenyl) levels may be up to eight times higher in farmed salmon than in wild salmon, and Omega-3 content may also be lower than in wild caught individuals. According to the British FSA (Food Standards Agency), however, the benefits of eating even farmed salmon still outweigh any risks imposed by contaminants.[citation needed] It is also noteworthy that salmon generally has among the lowest methylmercury contamination levels of all fish.
A simple rule of thumb is that the vast majority of Atlantic salmon available on the world market are farmed (greater than 99%), whereas the majority of Pacific salmon are wild-caught (greater than 80%). Farmed salmon outnumber wild salmon 85 to 1.
Salmon flesh is generally orange to red in colour, although there are some examples of white fleshed wild salmon. The natural colour of salmon results from carotenoid pigments, largely astaxanthin (E161j), in the flesh.[citation needed] Wild salmon get these carotenoids from eating krill and other tiny shellfish. Because consumers have shown a reluctance to purchase white fleshed salmon, astaxanthin, and very minutely canthaxanthin (E161g)), are added as artificial colourants to the feed of farmed salmon because prepared diets do not naturally contain these pigments. Astaxanthin is a potent antioxidant that stimulates the development of healthy fish nervous systems and that enhances the fish's fertility and growth rate. Research has revealed canthaxanthin may have negative effects on the human eye, accumulating in the retina at high levels of consumption.[citation needed] Today the concentration of carotenoids (mainly canthaxanthin and astaxanthin) exceeds 8 mg/kg of flesh and all fish producers try to reach a level that represents a value of 16 on the "Roche Color Card", a colour card used to show how pink the fish will appear at specific doses. This scale is specific for measuring the pink colour due to astaxanthin and is not for the orange hue obtained with canthaxanthin. The development of processing and storage operations, which can be detrimental on canthaxanthin flesh concentration, has led to an increased quantity of pigments added to the diet to compensate for the degrading effects of the processing. In wild fish, carotenoid levels of up to 20-25 mg are present, but levels of canthaxanthin are, in contrast, minor.
Canned salmon in the U.S. is usually wild Pacific catch, though some farmed salmon is available in canned form. Alaskan salmon is always wild catch.[citation needed] Smoked salmon is another popular preparation method, and can either be hot or cold smoked. Lox can refer either to cold smoked salmon or to salmon cured in a brine solution (also called gravlax).
Raw salmon flesh may contain Anisakis nematodes, marine parasites that cause Anisakiasis. Before the availability of refrigeration, the Japanese did not consume raw salmon. Salmon and salmon roe have only recently come into use in making sashimi (raw fish) and sushi.
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