The reproductive biology of the hermaphroditic goldlined seabream Rhabdosargus sarba in the central waters of the Taiwan Strait

Abstract

The reproductive biology of a commercially important sparid, the goldlined seabreamRhabdosargus sarba, was determined from examination of 802 specimens (443 females, 232 males, 68 fish of undifferentiated sex, and 59 bisexual fish) collected by fisheries operating in the central waters of the Taiwan Strait (henceforth central Taiwan Strait) from January to December 2016. Previous studies undertaken in other parts of the world have yielded conflicting information on the reproductive biology of this species. Based on macroscopic appearance, the gonadosomatic index, and histological examination of the gonad tissues, the spawning season of this species in the central Taiwan Strait was determined to be from December to March.R. sarbais an asynchronous spawner, with a mean estimated fecundity of 825,078 +/- 431,672 eggs. The sex ratio, 0.66, was significantly different from 0.5, and females predominated in most size classes and monthly samples. Size at 50% maturity was estimated to be 23.7 and 20.9 cm fork length for females and males, respectively. Ovotestes were identified in both young and adult individuals, which suggests thatR. sarbais a rudimentary hermaphrodite in the central Taiwan Strait. This finding is similar to that for conspecifics reported from Australia, but differs from those reported for other geographical regions. Monthly variation in the condition factor and in the hepatosomatic index indicated that the energy reserves of the muscles and liver may be closely linked to the spawning activity of this species.