Reproductive Biology and Growth Patterns of Pontoporia blainvillei (Artiodactyla, Pontoporiidae) From Santa Catarina State, Southern Brazil

ABSTRACT

This study evaluated reproductive parameters and growth patterns of male and female franciscana dolphins, Pontoporia blainvillei , in Santa Catarina State, southern Brazil, between Franciscana Management Area (FMA) II and III. We analyzed ovarian and testicular characteristics, counted the tooth growth layer groups, and constructed growth curves. For reproductive parameters and sexual maturity, the gonads of 112 franciscanas (58 females, 54 males) and teeth of 105 specimens (55 females, 50 males) were analyzed; and to estimate age and growth patterns, 297 individuals were analyzed (171 males, 126 females). All samples were collected from the monitoring of strandings on beaches between August 2015 and August 2020. Ovulation corpora were found in 20 females (34.5% mature) and in 38 individuals they were absent (65.5% immature). Histological analysis of the testes showed that 34 males were immature (63%) and 20 were mature (37%). Application of the Gompertz growth model identified distinct growth patterns between the sexes. While both showed an initial rapid phase, females attained a significantly larger asymptotic length (145.5 cm) than males (125.1 cm) and reached it at a later age (7 years vs. 5 years). These data will be useful in comparing reproductive parameters among FMAs.