Along with iwashi (sardines) and saba (mackerel), aji (horse mackerel) is one of the blue-backed fish that is effective in preventing lifestyle-related diseases.  In particular, the protein content of aji is more than 20% and the fat content is low, so the taste of aji is the taste of protein.  Aji in the waters near Japan is called ma-aji, but ma-aji can be broadly divided into “coast-set aji” and “open-sea aji”.  Biologically, they are the same species, and in particular, the “coast-set aji” is also called “yellow aji”. Its back and fins are tinged with yellow.  Because the catch is small, it is caught by pole-and-line fishing and is branded as a luxury fish.  The aji  in the photo is a yellow aji called “shima aji”, and it is said that it came to be described as “island aji” because it is often caught around the seven islands of Izu.  This shima aji is extremely rare, and even today with the advancement of aquaculture technology, the catch is only about 1/50 of that of the Japanese horse mackerel.

アジはイワシやサバとともに生活習慣病の予防に効果のある青背魚の代表に挙げられます。特にアジのたんぱく質含有量は20%以上で脂肪含有量が少なく、アジの旨みはたんぱく質の旨みと言えます。日本近海のアジはマアジと呼んでいますが、マアジは「瀬付きアジ」と「外洋アジ」に大別されます。生物学的には同種で、特に「瀬付きアジ」は「黄アジ」とも呼ばれ、背部とひれが黄色味を帯び、小ぶりですが脂が乗って甘み、旨みが強いのが特徴です。漁獲量が少ないため、一本釣りで漁獲され、高級魚としてブランド化されています。写真のアジは「シマアジ」と名付けられる黄アジで、伊豆七島あたりでよく漁獲されることから、『島鯵』と表記されるようになったのだのだそうです。このシマアジは、非常に希少性の高いもので、養殖技術が発展した現在においても、その漁獲量はマアジの50分の1程度しかありません。