Bull. Jpn. Soc. Fish. Oceanogr. 76(4), Page 205-210, 2012   Distribution, maturation and spawning of the Japanese anchovy Engraulis japonicus in the East China Sea in spring Hiroshige Tanaka1 * †, Youichi Tsukamoto1, Takeshi Sakai1 and Seiji Ohshimo1 1 Seikai National Fisheries Research Institute, Fisheries Research Agency, 1551-8 Taira, Nagasaki, Nagasaki 851-2213, Japan * Hokkaido National Fisheries Research Institute, Fisheries Research Agency, 116 Katsurakoi, Kushiro, Hokkaido 085-0802, Japan † tanakahs@affrc.go.jp Distribution and spawning ecology of the Japanese anchovy Engraulis japonicus were studied in the East China Sea (ECS) in February and March, 2009. Anchovies were collected in areas with sea surface temperature (SST) from 11.7 to 17.7°C. Among them, only large anchovies (≥98 mm body length) were collected in the southern area with SST from 15.4 to 17.7°C while both large and small ones were collected in the northern area with SST from 11.7 to 13.7°C. Gonad somatic index (GSI) of anchovies in the southern area was significantly higher than that in the northern area. Histological observations on ovaries revealed that the body length of the anchovies which were considered to be actively spawning (ovaries with yolked stage oocytes with postovulatory follicles, migratory nucleus stage or hydrated stage oocytes) exceeded 101 mm body length, being distributed in the southern area with SST from 15.4 to 17.7°C. On the other hand, large specimens distributed in the northern area were not associated with spawning. Estimation of relative batch fecundity (RBF) of the anchovies suggested that the relations between RBF and GSI, and also RBF and SST in the ECS, resembled to those reported for offshore Pacific waters. Key words: anchovy, spawning, East China Sea, batch fecundity