Contrasting the reproductive potential of Narcine entemedor and Rhinoptera steindachneri: 2 viviparous batoid species with different reproductive strategies

Abstract

Narcine entemedor and Rhinoptera steindachneri are 2 viviparous batoid species of commercial importance on the Pacific coast of Mexico. However, no adequate management plan has been set forth for either of them to ensure sustainable use. The aims of this study were to assess the reproductive potential and the potential rate of population increase (rʹ) of both species, as well contrasting their reproductive strategies, to infer how susceptible they are to fishing exploitation. Comparatively, among batoids, N. entemedor females have an early age at maturity, relatively high fecundity, and an intermediate lifespan, while R. steindachneri females have an early age at maturity, low fecundity, and a relatively short lifespan. According to our estimates, however, both species have relatively high reproductive potential, which N. entemedor exhibits by investing energy in maximizing fecundity and R. steindachneri by increasing the embryo’s body mass. Therefore, N. entemedor has better capacity to recover from relatively high overfishing (rʹ = 0.48) in comparison with R. steindachneri (rʹ = –0.18). The methodology used in this study proved to be a good option to assess the risk of overfishing in species for which there is limited data.