1Seikai National Fisheries Research Institute, Fisheries Research Agency, Nagasaki 850-0951, 2National Research Institute of Fisheries Science, Fisheries Research Agency, Yokohama, Kanagawa 236-8648, 3Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan
Sexual maturity, annual reproductive cycle, and batch fecundity of the lizardfish Saurida umeyoshii were examined in specimens collected from the East China Sea between April 1998 and April 2000. The minimum fork length (FL) at sexual maturity was 180 mm in males and 228 mm in females. Females with mature and spawning stage ovaries were collected between April and December, during which higher percentages of occurrence of such females were found between June and September. This indicates that the spawning season extends between April and December, mainly from June to September. Time course sampling showed that final oocyte maturation occurred during the daytime and subsequent ovulation occurred in the evening. The occurrences of developmental stage composition of oocytes and postovulatory follicles in mature ovaries suggested that a female could spawn every day during the active spawning season. Batch fecundity (BF) in females with mature oocytes was related to FL (mm): BF=(1.70×10−8)FL4.88 (278≤FL≤421).