Sexual development and maturity of the male brown banded bamboo shark, Chiloscyllium punctatum (Elasmobranchii : Hemiscylliidae)

Abstract

The present study aimed to assess the reproductive biology of male brown banded bamboo shark (Chiloscyllium punctatum). Morphological and histological changes in the reproductive tract and changes in gonad steroid testosterone were assessed in 110 male C. punctatum collected from Bahrakan Creek between January 2018 and March 2019. The reproductive tract in male C. punctatum consisted of a pair of testes, efferent ducts, epididymidis, ductus deferens, seminal vesicles, Leydig gland and claspers. Four sexual development stages were determined: (1) immature, no calcified claspers (2) maturing, partially calcified claspers; (3) active and resting adults. Both adult resting and active stages had calcified claspers. In this study, immature male C. punctatum without calcified claspers were found from August to October, maturing C. punctatum with partially calcified claspers were found from November to January and adult C. punctatum caught from February to April were active with calcified claspers, whereas adult fish collected from May to July and during the rest of the year (until mid-January in the following year) were in the resting stage with inactive testes. The testis had a lobular structure and the spermatocysts were arranged diametrically (i.e. along the cross-sectional width of the testis) in each lobule. Plasma testosterone concentrations were associated with histomorphological changes in the reproductive tract. Testosterone concentrations peaked in March in active males and then decreased significantly in resting males. Overall, the variations in the reproductive organs during different sexual maturity stages were consistent with their roles in the production, movement and release of spermatozoa.