Reproductive aspects of male franciscana dolphins (Pontoporia blainvillei) off Argentina

PANEBIANCO, M.V.; NEGRI, M. F.; CAPPOZZO, H. L.

ANIMAL REPRODUCTION SCIENCE

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2012 vol. 131 p. 41 - 48

0378-4320

As the first study to investigate reproductive aspects of male franciscana dolphin ? Pontoporiablainvillei ? in Argentine waters, the aim of this paper was to assess sexual maturityby using histological and morphometric methods. P. blainvillei was labeled as ?Vulnerable?by the IUCN in 2008. The specimens analyzed were either incidentally caught in artisanalfishing nets (n = 47) or found stranded on the beach (n = 3). Testis weight and testicularindex of maturity were reliable indicators of sexual maturity, being their values: MTW:1.14±0.60?4.49±1.94; IM: 0.03±0.01?0.09±0.03, for immature and mature specimens?respectively. It was found that the hierarchical cluster analysis (HCA) might be appropriatefor establishing sexual maturity stage, based on both the body morphometric measurementsand age. The values for age, standard length and total weight at attainment sexualmaturity were 2.92?3.54 years, 126.19?126.27 cm and 23.47?23.75 kg. Considering theextremely low relative testis weight, the reversed sexual length dimorphism, the absenceof secondary sexual characteristics, and the lack of scars from intrasexual combats in males,the hypothesis that sperm competition does not occur in the species, and male combats foraccessing female reproductive may be rare for P. blainvillei is reinforced. All these featuresfit the species within a serial monogamous mating system.© 2012 Elsevier B.V. All rights reserved.