Reproductive parameters of the Pacific angel shark Squatina californica (Selachii: Squatinidae)

Abstract

Reproductive characteristics of the Pacific angel shark, Squatina californica, were evaluated from 420 specimens obtained from the artisanal fishery in La Paz Bay, Gulf of California, Mexico. Females (99 cm, 6000 g) were larger than males (95 cm, 5000 g) in terms of both total length (L(T)) and body mass (M(T)). The overall sex ratio was significantly different from the expected 1:1, suggesting sexual segregation of mature individuals in La Paz Bay. Males had developed reproductive organs and calcified claspers from 72 cm L(T); the median size at maturity (LT50 ) was 75.6 cm. In females, only the left ovary was functional and mature ovarian follicles were present from 77 cm L(T); the estimated LT50 was 77.7 cm. For the 10 gravid females sampled, uterine fecundity was between two and 10 embryos. Mature, non-gravid females with small and large ovarian follicles appeared simultaneously with gravid females with follicles that did not exceed 1.9 cm diameter.

Population structure of the Pacific angel shark (Squatina californica) along the northwestern coast of Mexico based on the mitochondrial DNA control region

“…The regional genetic variation observed in our study could be linked to ontogenetic differences in S. californica between study areas. Length at sexual maturity (LSM) and maximum total length (MTL) are lower in individuals from the gulf area (LSM = 70.0-77.7 cm; MTL = 88-99 cm) than in individuals from the Pacific area (LSM = 99 cm; MTL = 117 cm) (Villavicencio-Garayzar 1996, Romero-Caicedo et al 2016. Morphological differences and genetic differentiation are both in agreement with the population structure of this species in the study area.…”

“…Taking into account the characteristics of S. californica, we consider that the submarine canyons constitute a natural barrier for its dispersal. Geomorphology off northwestern Mexico is complex, and there are numerous submarine canyons and great depths (at the mouth of the Gulf of California, the ocean basin drops to over 3,000 m) (Gutiérrez et al (Villavicencio-Garayzar 1996, Romero-Caicedo et al 2016. Las diferencias tanto morfológicas como genéticas concuerdan con la estructura poblacional de esta especie en el área de estudio.…”

“…The Pacific angel shark, Squatina californica Ayres 1859, is a demersal shark found off the coast of North America, from Alaska to the Gulf of California, where it is associated with soft-bottom habitats (Compagno et al 2005). It is a lecithotrophic viviparous shark that has low fecundity (10 embryos per year), with gestation lasting 10 months (Compagno et al 2005, Romero-Caicedo et al 2016). This species is frequently targeted by the artisanal elasmobranch fishery along the norwestern coast of Mexico (Villavicencio-Garayzar 1996, Ramírez-Amaro et al 2013).…”

“…El tiburón ángel del Pacífico, Squatina californica Ayres 1859, es una especie demersal que se encuentra a lo largo de la costa occidental de Norteamérica, desde Alaska hasta el golfo de California, donde se asocia con hábitats de fondos blandos (Compagno et al 2005). Es un tiburón vivíparo lecitotrófico que tiene una baja fecundidad (10 embriones por año) y un periodo de gestación que dura 10 meses (Compagno et al 2005, Romero-Caicedo et al 2016. Es una especie objetivo de la pesquería artesanal de elasmobranquios en la costa noroccidental de México (Villavicencio-Garayzar 1996, Ramírez-Amaro et al 2013.…”

Length at maturity of the Pacific angel shark (Squatina californica) in the artisanal elasmobranch fishery in the Gulf of California in Mexico

“…Biological information about the Pacific angel shark in Mexico is fragmented and limited to a few studies on trophic ecology and reproduction (Escobar-Sánchez et al, 2006Romero-Caicedo et al, 2016). Using mitochondrial DNA, Ramírez-Amaro et al (2017) reported genetic differences between specimens from the GOC and Pacific coast of the BCP, validating previous observations of life history differences between specimens from these areas (Villavicencio-Garayzar, 1996). Similarly, Márquez-Farías (2007) found maximum lengths and lengths at maturity for the population of shovelnose guitarfish (Pseudobatus productus) in the GOC that are different from those reported for the population along the Pacific coast of the BCP (Villavicencio-Garayzar, 1995).…”