Reproductive biology of the yellow seabream (Dentex tumifrons) in the northern waters off Taiwan

Abstract

Reproductive biology of the yellow seabream (Dentex tumifrons) was described based on 1,400 specimens caught by otter trawlers in the northern waters off Taiwan and landed at Jinshan, Rueifang, and Dasi fishing ports from August 2005 to August 2006. Macroscopic appearance of the ovary, gonadosomatic index, and histological examination suggested that the yellow seabream spawns asynchronously, and spawning peaks in April and October, in the northern waters off Taiwan. Eight stages of oocyte development were determined based on histological examination, and ovarian development can be divided into immature, early maturing, late maturing and matured stages. The sex ratio of 0.704 was significantly different from 0.5 using χ2 test and decreased in compliance with the increasing of fork length in bigger specimens. The relationship between fecundity (F) and gonad weight (GW) was estimated to be F = 11.56 GW + 8.0745 (n = 25, P ＜ 0.05). Mean fecundity (± standard deviation) was estimated at 50151 ± 30379 eggs. Size of fork length (FL) at 50% maturity estimated by using the Logistic model was 154.8 mm and 168.6 mm for females and males, respectively.