The reproductive biology of the hermaphroditic goldlined seabream Rhabdosargus sarba in the central waters of the Taiwan
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ORIGINAL ARTICLE Biology
The reproductive biology of the hermaphroditic goldlined seabream Rhabdosargus sarba in the central waters of the Taiwan Strait Shyh‑Bin Wang1,3 · Tse‑Lin Hsu2 · Shoou‑Jeng Joung2 Received: 16 April 2020 / Accepted: 7 July 2020 © Japanese Society of Fisheries Science 2020
Abstract The reproductive biology of a commercially important sparid, the goldlined seabream Rhabdosargus 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. sarba is 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 that R. sarba is 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. Keywords Rudimentary hermaphrodite · Histology · Spawning season · Fecundity
Introduction The goldlined seabream Rhabdosargus sarba (Forsskål 1775) is widely distributed in the Indo-West Pacific, the Red Sea, and East African, Japanese, South Asian, and Australian waters (Smith and Heemstra 1986; Yeung and Chan 1987; Van der Elst 1988; El-Agamy 1989; Kailola et al. 1993; Leu 1994). The species is also found along the northern and western coasts of Taiwan (Shao KT Taiwan * Shyh‑Bin Wang [email protected] 1
Institute of Marine Affairs and Resource Management, National Taiwan Ocean University, Keelung City 20224, Taiwan
2
Department of Environmental Biology and Fisheries Science, National Taiwan Ocean University, Keelung City 20224, Taiwan
3
Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung City 20224, Taiwan
Fish Database Web: https://fishdb.sinica.edu.tw/” accessed 21 March 2018), where it is of economic importance for various coastal fisheries. The annual catch of seabream species, including R. sarba, from the waters around Penghu in the center of the Taiwan Strait (henceforth “central Taiwan Strait”) declined dramatically from 3825 to
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