CONICET | Buscador de Institutos y Recursos Humanos

The franciscana dolphin Pontoporia blainvillei inhabits coastal waters off South28 America where presents a markedly spatial segregation and genetic differentiation. In its 29 southernmost distribution, there is scarce reported data of its postnatal ontogenetic 30 growth and sexual dimorphism. In this sense, this study reveals that at southern Buenos 31 Aires Province, Argentina, franciscanas of 5 years and older show females 16% longer 32 and 30% heavier than males. According to the Von Bertalanffy growth model females 33 have a lower growth rate and an asymptotic length of 150.57 cm in contrast with the34 129.43 cm achieved by males. This is the first growth study of the region and a baseline 35 to assess temporal changes in the population for a comprehensive management of the 36 species in an area where suffers a long-time history of incidental captures in fisheries.