The Reproductive Biology of the Gizzard Shad, Nematalosa come (Richarson, 1846), in the Kaohsiung River and Its Harbor Area, Southern Taiwan

The gonadal development of the gizzard shad, Nematalosa come, is described. Gonadosomatic indices and frequency of advanced maturity stages demonstrated that spawning activity reached a peak from February to April. Histological examination of the gonads showed that spawning is asynchronous. The sex ratio was M:F = 1.2:1. Minimum fork length and body weight of males and females at sexual maturity were 12 cm and 13 cm, and 39 g and 45 g, respectively. Average batch fecundity was 89289 ± 23670. The relationships between the fecundity (F) and body weight (BW), fork length (FL) and gonad weight (GW) were log F = 3.516 + 0.673 log BW (r = 0.540), log F = 3.147 + 1.413 log FL (r = 0.433), and log F = 4.184 + 0.822 log GW (r = 0.755), respectively. There was no evidence that spawning is related to flooding but N. come may undertake an upstream spawning migration. Storm sewage discharges in the Kaohsiung River system may have an important influence on recruitment and population abundance of the shad.