Mercury Risk: High
The Spanish mackerel is a sleek oceanic schooling fish that boasts a smattering of orange spots along its flanks. There are many different species of Spanish mackerel, but the term sawara is usually used for Scomberomorus niphonius, the Japanese Spanish mackerel. This fish is very popular in Japan but has only recently achieved any real following in North America. U.S. sushi bars will often offer related Scomberomorus species from the Atlantic Ocean or the Gulf of Mexico as sawara.
If your sushi restaurant offers Spanish mackerel as aji, the term is being mistranslated. Aji is specifically horse mackerel, a related but distinctly different genus of fish. The aji section in this book discusses the issues related to the horse mackerel. As for Spanish mackerel, it grows rapidly and reaches sexual maturity relatively early. These characteristics help to protect the species from fishing pressure.
There is a large Spanish mackerel fishery in the Gulf of Mexico that is well-managed and based on strong stocks. The populations are neither depleted nor currently being overfished. The majority of the domestic fleet targets Spanish mackerel with gill nets, which have little impact on the surrounding habitat. There is, however, some bycatch or unintended catch of marine mammals in the fishery, a concern which should be kept in mind when ordering this fish.
The term sawara can also refer to Scomberomorus carvalla, the king mackerel. While both this fish and its Spanish cousin may contain elevated levels of mercury, king mackerel can be a serious threat. It is a large fish that exists at the top of the food chain and has been found to contain exceptionally high quantities of mercury. Stocks are strong, and the king mackerel fishery is generally well-managed, but numerous scientific sources have concluded that king mackerel is unsafe and should be avoided, especially by small children and pregnant women.
In terms of sustainability, sawara is a good choice at the sushi bar. Both Spanish mackerel and king mackerel have strong stocks and good management in place—just be attentive to the mercury issue, especially if the sawara in question turns out to be royalty.
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