Reproductive strategy and spawning activity of sand flathead, Platycephalus bassensis.

Abstract

The aim of this study was to describe and determine the reproductive and spawning strategy of the sand flathead, Platycephalus bassensis Cuvier, 1829 based on histological analysis of ovary and testis. The presence of multiple group synchronous gamete development in both sexes within a reproductive season confirmed the hypothesis that sand flathead is a serial spawner and is reproductively active from October to March. Spawning frequency estimated from a combination of information acquired from field sampling and results from a laboratory experiment, indicated that sand flathead spawned on average once every 4-5.3 days during the spawning season. A clear pattern of diel periodicity in spawning was apparent in sand flathead with the peak of spawning activity during the day. Results of this study showed that estimating spawning periodicity from the presence, and age of postovulatory follicles is more reliable than using the presence of hydrated oocytes. This study highlights the details of reproductive biology of a serial spawner and its potential for variability, which can have implications for recruitment and adult population dynamics.