Age and length data of 291 franciscana dolphins (Pontoporia blainvillei) incidentally captured on the coast of Rio Grande do Sul State (RS), southern Brazil, were used to fit growth curves using Gompertz and Von Bertalanffy growth models. A small sample of franciscanas (N = 35) from Buenos Aires Province (BA), Argentina, were used to see if there are apparent growth differences between the populations. Male and female franciscana samples from both areas were primarily (78–85%) <4 years of age. The Von Bertalanffy growth model with a data set that excluded animals <1 year of age provided the best fit to data. Based on this model, dolphins from the RS population reached asymptotic length at 136.0 cm and 158.4 cm, for males and females, respectively. No remarkable differences were observed in the growth trajectories of males and females between the RS and BA populations.

Milk is the only external energy source for mammals in their early stages of life. Its composition varies during lactation in baleen whales and pinnipeds, while only descriptive studies are available for odontocetes. The aim of this work was to identify the components of the milk of franciscana, Pontoporia blainvillei, from southern Brazil. Samples were manually collected from lactating females (N = 5) incidentally caught in the gill-net fishery. The amount of fat, protein, carbohydrate, mineral and trace metal content, and caloric value of the samples were estimated. Milk of the franciscana dolphin presented mean fat, protein and carbohydrate concentrations similar to those described for other coastal species. A significant increase in fat concentration was observed in winter months, with a higher energy density. Potassium was the mineral found in higher amounts. Zinc, mercury and copper were detected in low concentrations. Due to different habitat conditions along the species distribution, the presence of a highly seasonal reproductive period and inter-population genetic variability, studies on milk composition in other areas is recommended.