Reproductive biology and diet of the longtail butterfly rayGymnura poecilura(Shaw, 1804) along western Bay of Bengal

Abstract

The reproductive biology and diet of the longtail butterfly ray Gymnura poecilura is described based on 630 specimens (N = 377 females and 253 males). The mean disc width (WD) of females and males was 576.7 mm (range = 190–920 mm) and 416.3 mm (230–550 mm), respectively. Sexual dimorphism in size was seen, with the maximum size of males being only 60% of the maximum female size. The disc widths at 50% maturity (WD50) were estimated to be 506.5 mm (females) and 435.9 mm (males). The mean uterine fecundity was 3.3 (range = 1–8). The size at birth was between 190 and 220 mm WD. Year-round reproduction was indicated, due to the presence of mature males and gravid females throughout the year, neonates in multiple months and large variations in embryo size within months. Feeding intensity increased with body size. Fish accounted for 80.9% of the diet (Index of Relative Importance, IRI), followed by crustaceans (18.9%) and molluscs. The species was found to be a specialized feeder.

Reproductive Biology and Embryonic Diapause as a Survival Strategy for the East Asian Endemic Eagle Ray Aetobatus narutobiei

“…In the family Aetobatidae, size and age at sexual maturity were known previously for only male spotted eagle ray A. narinari (ocellated eagle ray A. ocellatus at present) from Australia (DW at 50% sexual maturity of 130.6 cm) (Schluessel et al, 2010). Size and age disparity between sexes has been reported for other stingray species such as the longtail butterfly ray Gymnura poecilura (Menon et al, 2020), whiptail stingray Dasyatis chrysonota (Ebert and Cowley, 2009), and bat ray Myliobatis californica (Martin and Cailliet, 1988b) might be typical of Myliobatiforms and related to their reproductive mode (Martin and Cailliet, 1988b;Capapé, 1993;Furumitsu et al, 2010Furumitsu et al, , 2019. For viviparous species larger females are advantageous, as the increased internal space for developing embryos enables larger young and/or higher fecundity at parturition (Furumitsu et al, 2019).…”

Reproductive biology, length‐weight relationship and diet of co‐occurring butterfly rays, Gymnura poecilura and Gymnura zonura, in Malaysian waters

“…Reproductive biology of gymnurids has been studied in varying degrees since the 19th century until recent years. Nonetheless, information on reproduction had been reported only in some Gymnura species, namely, G. poecilura (James, 1966; Muktha et al ., 2020; Raje & Zacharia, 2009), G. zonura (White & Dharmadi, 2007), Gymnura altavela (Alkusairy et al ., 2014; Paiva et al ., 2018; Taylan et al ., 2019), Gymnura marmorata (Maria et al ., 2019), G. micrura (Parsons, 2017; Raje, 2003; Wood‐Mason & Alcock, 1890; Yokota et al ., 2012; Yokota & Lessa, 2007) and Gymnura australis (Jacobsen et al ., 2009). Generally, gymnurids are viviparous, where a yolk sac initially nourishes embryos, then embryos absorb uterine milk rich in proteins and lipids produced by the mother for embryonic development until birth (Conrath, 2004).…”

“…Generally, gymnurids are viviparous, where a yolk sac initially nourishes embryos, then embryos absorb uterine milk rich in proteins and lipids produced by the mother for embryonic development until birth (Conrath, 2004). Several studies have indicated that the maximum uterine fecundity for most gymnurids is between three and nine (Daiber & Booth, 1960; Jacobsen et al ., 2009; James, 1966; Muktha et al ., 2020; White & Dharmadi, 2007; Wood‐Mason & Alcock, 1890). Furthermore, some gymnurid species, that is, G. poecilura (Muktha et al ., 2020), G. altavela (Alkusairy et al ., 2014; Parsons, 2017), G. micrura (Parsons, 2017), the mazatlan butterfly ray Gymnura crebripunctata, G. marmorata (Smith et al ., 2009) and G. australis (Jacobsen et al ., 2009) exhibit sexual dimorphism in body size where females mature at larger sizes than males.…”

“…In contrast to reproductive studies, the diet of gymnurids has received less attention, although gymnurids reportedly display a high degree of feeding specialization (Yokota et al ., 2013). Teleosts appear to be the dominant prey in most gymnurid stomach contents with an index of relative importance of more than 90% (Jacobsen & Bennett, 2009; Jargowsky et al ., 2019; Muktha et al ., 2020; Yokota et al ., 2013). The diet of G. altavela was somewhat different from that of other gymnurids, dominated by crustaceans followed by teleosts (Capapé, 1986).…”

“…The diet of G. altavela was somewhat different from that of other gymnurids, dominated by crustaceans followed by teleosts (Capapé, 1986). The only detailed diet study of G. poecilura conducted by Muktha et al ., 2020 from the western Bay of Bengal had shown different feeding strategies and behaviours based on the sizes of individual rays and their prey. Nonetheless, basic information on species occurrence of gymnurid, reproductive biology, size‐based information and diet in Malaysia remains lacking.…”