Life history, growth, and reproductive biology of four mobulid species in the Bohol Sea, Philippines

This study focuses on female life-history parameters and reproductive cycles for four mobulid rays (Mobula thurstoni, Mo. japanica, Mo. tarapacana, and Manta birostris) caught in a targeted fishery in the Philippines. We collected size and reproductive data from 1,510 specimens (30% of catch) landed in two seasons in 2015 and 2016. Sexual maturity was assessed by visual examination of 1,034 specimens, to determine size-at-maturity and size-at-pregnancy. Females of all species matured at a larger size than males. Pregnancy ogives were estimated for all species except Mo. tarapacana, and shifted to the right of female maturity ogives, suggesting that only a small percentage of the female reproduce upon reaching sexual maturity. We report an aseasonal reproductive cycle at the population level for both Mo. thurstoni and Ma. birostris due to the absence of specific ovulation cycle and the wide size ranges of embryos examined throughout the months. The development of the follicles is not alw...本研究聚焦于菲律宾定向渔业中捕获的四种蝠鲼科鳐类（mobulid rays）的雌性生活史参数与繁殖周期，涉及物种包括Mobula thurstoni、Mo. japanica、Mo. tarapacana及Manta birostris。本研究于2015年与2016年的两个渔季中，采集了1510尾（占总渔获量30%）上岸个体的体型与繁殖相关数据。通过对1034尾个体的目视检查完成性成熟评估，以确定性成熟体型与妊娠体型。所有物种的雌性个体性成熟时的体型均大于雄性。除Mo. tarapacana外，其余物种均估算了妊娠累积曲线，且该曲线均位于雌性成熟累积曲线的右侧，这表明仅有少量雌性个体在达到性成熟后即可开展繁殖。鉴于未观测到明确的排卵周期，且各月份采样的胚胎体型跨度较大，本研究证实Mo. thurstoni与Ma. birostris的种群繁殖周期无季节性。滤泡的发育并不总是...