Tuna or not tuna?

In 2015, UPS banned shipments of shark fins “following consultations with the World Wildlife Fund (WWF)”, joining 31 airlines which now refuse to carry the items. Cathay Pacific will carry only shark fins from sustainable sources, although the cruelty of the shark fin trade makes it difficult to see how any source could really be acceptable. In 2014, Hong Kong imported nearly 6,000 tonnes of shark fin, although only about 12 per cent of it by air. The remaining 80 per cent comes by sea, so UPS’s decision (and a previous one by its rival DHL) will likely have only a symbolic effect.

Shark fin may be losing popularity here, but North America eats more tuna than any other fish (unlike the rest of the world where herring is the most popular). In spite of its healthy appearance, eating tuna responsibly has its own difficulties including the depletion of some tuna stocks, cruelty to other species associated with tuna fishing and dangerous levels of mercury and radiation in some fish.

In the Pacific, where some of Canada’s tuna supply is fished, radiation levels emanating from the ruined Fukushima nuclear plant are now the highest since the 2011 meltdown. Japan exports around $76 million in food to Canada, including fish. This is a particular concern given the high levels of radioactive cesium washed into the Pacific by the tsunami at Fukushima. High percentages of cesium have been found in most species of food fish tested by the Japanese government. For example, in 2012 93% of tuna and eel, 100% of carp and monkfish, and 92 % of sardines were contaminated. Fish has always had a certain amount of radiation because the Earth is radioactive and so it occurs naturally in the ocean. And, some radiation is the result of 1960s nuclear weapons testing. But the levels found now near Fukushima as worrying because they don’t seem to be dissipating naturally: cesium seems to have settled in the sea floor or in the crustaceans eaten by the tuna and other fish.

Advice about healthy, safe fish consumption can be difficult to follow: we are supposed to eat food high in Omega-3 fatty acids, like tuna, but we are also supposed to eat fish from sustainable, low-mercury sources. Mercury is a substance that is found naturally in the environment, but it also seeps into the water and soil from industrial facilities. Mercury levels tend to be higher in larger, longer-lived fish, so it’s a good idea to choose skipjack over albacore tuna, for example. If you aren’t sure, “light” tuna is better than “white” tuna if you want to avoid mercury, and, if you buy Clover Leaf tuna you can visit their website and click on “Trace My Catch” to enter your tin’s barcode and find out where it came from. However, even if you can now trace the origins of their products, Greenpeace has been highly critical of Clover Leaf because of its fishing methods. A 2013 survey by Greenpeace placed major supermarket own brands such as President’s Choice, Compliments, and Selections above Clover Leaf, which is Canada’s most popular brand. The top two brands were Wild Planet and Rain Coast, followed by Safeway own brand and Gold Seal, a company which made huge improvements in its practices between 2011 and 2013.

As well as contamination of stocks, the numbers of fish themselves is a cause for deep concern. Some species of tuna, particularly bluefin, are simply being decimated by overfishing.

In both the Atlantic and Pacific regions of Canada, the bluefin tuna fishery is heavily regulated. Every fish must have a tag so it can be tracked from boat to market. But this is not the case everywhere. By 2014, the stocks of Pacific bluefin had declined by 96 percent in the last 40 years, and Atlantic bluefin have declined by 72% in the eastern Atlantic and 82% in the western Atlantic. The World Wildlife Fund called it “too many boats chasing too few fish”. The organisation believes the fishing fleet is one third larger than it should be.

This is a particular problem in the Mediterranean where giant bluefin tuna are hunted on an industrial scale in the spring and summer when they are spawning. Spotter planes fly overhead, looking for the clouds of eggs and milt and schools of fish. They call in the boats with purse seine nets, which catch the fish and then cage some of them at sea to fatten them up for the Japanese sushi market. Having nearly exhausted the Pacific stocks, multinational ventures of Spanish and Japanese fishing interests are decimating the stocks in the Mediterranean and branching out to the adjacent waters. Eighty per cent of the world’s bluefin catch ends up as sushi in Japan.

Consumers might think eating “farmed” bluefin means protecting wild stocks, but this actually just means the fish was caught wild and then transferred to a pen in the open sea to gain weight before slaughter.

Salmon is safer to eat, but the Canadian government recently approved genetically modified salmon for human consumption, so if you want to avoid GMO, you need to check that you aren’t buying AquAdvantage fish, which are due to go on sale in spring 2017.

So, what should you eat if you like fish but don’t want that unhealthy glow?

First of all, avoid fish caught in the Pacific, looking for Atlantic, Mediterranean, or freshwater lake varieties. Sardines, tilapia, salmon, and anchovies are all safer bets, as are catfish, pollock, perch, and haddock.

Next, make sure you aren’t eating anything affected by the neurotoxins that periodically affect shellfish stocks, especially on the West Coast. Algae blooms linked to warmer ocean temperatures can enter the food chain through the clams and mussels that feed on algae, and the larger species like crab that feed on them.

Finally, consult a source like the Monterey Aquarium guide or Ocean Wise for the most recent advice on which fish to eat if you care about your health and that of our oceans.