Growth and reproduction in captivity unveils remarkable life-history plasticity in the smallnose fanskate, Sympterygia bonapartii (Chondrichthyes: Rajiformes)

Abstract

We analyzed growth and reproduction of captive-born smallnose fanskates Sympterygia bonapartii. Egg cases were obtained from oviposition of two females caught in the wild and held at Temaikèn Aquarium. Following hatching, growth was analyzed in 13 females and 21 males until sexual maturity. Pattern of oviposition activity and reproductive performance were evaluated in six of the captive-reared females. Four models were fitted to growth data, among which the logistic function was the one attaining the best fit. The highest growth rate for both sexes was recorded during the first year of life, whereas growth was significantly higher in females than in males during the second year. Size at first oviposition was 61.7 ± 3.5 cm TL, similar to wild specimens. However, captive-reared females reached maturity before two years of age, i.e. much earlier than wild skates, implying a significant phenotypic plasticity in this species. The similarity in size at maturity and the difference in age at maturity between captive and wild specimens indicate that there is a decoupling of both parameters mediated through growth rates. Captive-born skates reproduced successfully and yielded viable offspring, indicating that the environment at Temaikèn Aquarium is suitable for S. bonapartii to attain its full life cycle.

Twins! Microsatellite analysis of two embryos within one egg case in oviparous elasmobranchs

“…Overall there are an increasing number of reports on the occurrence of reproductive mutations such as double-embryo egg cases and conjoined individuals. The captive species which produce twin egg cases usually display high reproductive performance and plasticity [40], although without human input, twin egg cases typically do not succeed to hatch [18]. Considering the significant stress on wild populations of sharks and rays, further research is needed to understand and identify the mechanisms producing, and consequences of, elasmobranch twins.…”

Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north‐eastern coast: Habitat use and resource partitioning

“…(2016), who estimated trophic discrimination factors (TDF) and turnover rates in the blood and muscle of the batoid Sympterygia bonapartii (Müller & Henle, 1841) through controlled feeding over a 1‐year period. Considering that fractionation can vary according to the species studied and diet consumed (Hussey et al ., 2014; Post, 2002), and since S. bonapartii is a demersal batoid similar to the Hypanus genus (Hozbor & Ana, 2015; Jañez et al ., 2018), we considered it the most appropriate TDF.…”

“…, and since S. bonapartii is a demersal batoid similar to the Hypanus genus(Hozbor & Ana, 2015;Jañez et al, 2018), we considered it the most appropriate TDF.T A B L E 8Note: Specimens collected on the coast of Pernambuco, Brazil, from 2017 to 2019. d.f., degrees of freedom; MS, mean squares; P, statistical significance of hypothesis test; SD, square root; SS, sums of squares; Var, estimated sizes of components of variation.…”