Reproductive biology of Japanese gizzard shad (Nematalosa japonica) in coastal waters around Okinawa Island, Ryukyu Archipelago, southwestern Japan

作者：Uehara Masato^*; Tachihara Katsunori

来源：Ichthyological Research, 2012, 59(4): 314-322.

DOI：10.1007/s10228-012-0291-1

• Nematalosa japonica
• Clupeidae
• Reproductive cycle
• Sexual maturity
• Okinawa Island

The reproductive cycle and spawning characteristics of the Japanese gizzard shad (Nematalosa japonica) were examined histologically using specimens collected around Okinawa Island in southwestern Japan. The observed lengths at 50 % maturity were approximately 170 mm in standard length (SL) for females and 160 mm SL for males, which corresponded approximately to 3-year-old fish. The spawning season was estimated to take place from January to May, peaking from February to April, which closely coincided with the coldest water temperatures of the year. The lipidosomatic index of both sexes decreased from January onward and maintained low values until July, presumably as the fish expended energy to reproduce. Spawning intervals were estimated to occur between 1.3 and 1.8 days from February to April. Fecundity (F) for females tested using 69 ovaries was related to SL: F = 1.313 x 10(-4) x SL3.966. Histological observations and a fish market survey suggested that the species spawned in sandy muddy areas (%26lt; 20 m) based on the presence of mature individuals. The implications of our results toward conservation and management of N. japonica are discussed.

• 出版日期2012-11