Reproduction of the angular angel shark (Squatina guggenheim): geographic differences, reproductive cycle, and sexual dimorphism

Abstract

Abstract Colonello, J. H., Lucifora, L. O., and Massa, A. M. 2007. Reproduction of the angular angel shark (Squatina guggenheim): geographic differences, reproductive cycle, and sexual dimorphism. – ICES Journal of Marine Science, 64: 131–140. The reproductive ecology of Squatina guggenheim from two coastal areas in South America is analysed. In both sexes, individuals from ER (El Rincón coastal system, the more southern area) attained a larger maximum total length (LT) and a heavier weight at a given length than those from LP (La Plata River estuary). Females from ER mature at a significantly larger LT than females from LP. These patterns could be explained by an advantage of larger body size at higher latitudes in providing more reserves for winter, because individuals from ER have a larger liver than those from LP. Spines in the outer part of the pectoral fins were observed only in adult males. Fecundity increased with female total length. Females have a 3-y reproductive cycle, consisting of 10–12 months of gestation and 2 y of oocyte maturation. The embryonic growth fits the Gompertz model. Birth is in November or December, as inferred from embryo size and the presence of neonates and young of the year. Densities of S. guggenheim in LP peaked in spring and summer along the Uruguayan coast, suggesting a seasonal movement perpendicular to the shore. The reproductive pattern found suggests a population with low productivity.