Salmon. サケ、鮭。Oncorhyncus keta. Also known as "chum salmon."
Pacific salmon is silvery in color, the length is usually 60-70 cm, and weight about 3 kg. The fish can be found in the seas around Japan, and travels upstream of rivers for spawning in Tohoku and Hokkaido. This occurs between September and January. For food, however, the salmon from the high seas is preferred, and these are best in May and June.
Despite the Japanese predilection for sashimi, fresh salmon is not part of the traditional Japanese diet - sushi with salmon are a recent innovation. Most salmon is salted after it has been caught (shiozake) and then grilled. In this form it is a perennial breakfast favorite. It is also used in nabemono (one pot dishes eaten in winter as Ishikari-nabe), and can be steamed with sake (rice wine) as sakamushi.
The salted roe of the salmon is considered a delicacy and is marketed under the name ikura.