Contributions to the reproductive biology of encrasicholina punctifer Fowler, 1938 (engraulidae) from West Sumatra, Indonesia

Abstract

Encrasicholina punctifer (Fowler, 1938) is economically by far the most important fish species in the coastal area of Padang (West Sumatra, Indonesia). In this study, the reproductive biology of E. punctifer is described for the first time with different methods. The relationship between length and weight of E. punctifer in the coastal waters of west Sumatra can be described as W=6.3×10 −6L t 3.125(r 2=0.96, n=2550) . The Encrasicholines are multiple spawners with asynchronous oocyte development. During one individual spawning season, oocyte development is a continuous process involving all stages of oocytes, clearly represented by an unimodal oocyte-size-frequency-distribution (OSFD). Before spawning a new batch can be identified by its separation from the remaining oocytes, leaving a gap in the OSFD. There are postovulatory follicles inside the ovary after ovulation. From a gonosomatic index of 5.5 the ovaries contain hydrated oocytes, indicating a pre-spawning state. A certain proportion of the population is spawning at any time. The relative fecundity was estimated to be 985 (± 359) eggs per batch and gram female body weight. The oocyte development occurs simultaneously in all areas of the ovary. First maturity is reached at 57.5 mm L t. There is no dependence between fish condition and gonad weight. The necessary energy for the gonadal growth of the anchovies is not obtained from body fat, but most likely directly from forage.