Many winter species are prized for their fatty quality, in contrast to summer fish characterized by subtle flavor. Bluefin tuna acquire an intense limpidity from late autumn into winter, reaching their prime, however the scarcity and overwhelming popularity of the species make for astoundingly high prices. The gallant fighting spirit of the pole-fished tuna, its attractive deep scarlet flesh, bloody aroma and intense flavor make it emblematic of Edo-mae sushi. By December, flavorsome amberjack weighing over 10kg start to appear, but only for a short-lived season. Olive flounder (hirame) also suddenly pack on weight with a new year, and are deemed to at peak flavor, Scarce blackfin (hira-suzuki) acquire good-quality fat on their delicate flesh, for an agreeable texture. Gurnard in the period when sea temperatures are lowest have a smoothness and intense sweetness and flavor belied by their gaudy looks. Japanese halfbeak for the scarlet tip of their lower jaw, have a delicate texture and flavor. Tiger prawns, which move to deeper waters as temperatures drop, gain weight and flavor. Blood cockle, pen shell and Ezo abalone take on a lustrous sheen, and grow sleek and sweet. Gizzard shad, one of the original ingredients in Edo-mae sushi and a fish typifying the delectable appeal of nigiri-zushi, is at its succulent best from late autumn to around early winter, when sushi fans can enjoy the flavor of shad at its fat-suffused finest.