A comprehensive reassessment of the reproductive output of the narrownose smooth-hound shark (Mustelus schmitti)

Abstract

This study estimated the reproductive output of the Mustelus schmitti shark in relation to female body size. Maturity and first maternity ogives, litter size, and follicular and embryonic growth dynamics were evaluated in relation to total length (TL) and reproductive stage in 10173 females captured throughout the year between 2002 and 2019. Length-at-first maternity was 60.7 cm TL (~3 cm higher than at maturity). Litter size increased as a power function of maternal TL. The Gompertz model described embryo growth, with an estimated mean size at birth of 24.3 cm TL. Embryos >20 cm TL (mid-to-late stages of gestation) were only observed before January. During the periparturient period (October–December), the dispersion towards smaller embryos increased as the females were smaller. While ovulated/early gravid females were observed from mid-spring to late autumn, parturition occurs from spring to mid-summer. All ovulated/early gravid females found after mid-summer were< 72 cm TL. Delayed folliculogenesis was observed in some nongravid mature females within this small size range. These results provide evidence that the litter size in M. schmitti increases as a power function of maternal TL and that some small females may produce smaller broods. These data would improve population assessments of this fishery resource.