How many are they? Estimates of demographic patterns of reproductive females of southern right whale (Eubalaena australis) in the southern coast of Brazil

Abstract

Southern right whales use the Brazilian coast as a wintering area. This population was severely depleted by whaling up until 1973. Since the 1980s, studies have shown that this species is now restricted to the southern waters of Brazil. Using photoidentification data obtained via standardized aerial surveys from Florianópolis, State of Santa Catarina (SC) (−27.797°/−48.533°) to Torres, State of Rio Grande do Sul (RS) (−29.396°/−49.763°), mark-recapture methods were used to estimate survival capture and recruitment probability, population size using the POPAN model for reproductive females. Data were collected between 2004 and 2021. The final model was selected based on the lowest Akaike Information Criterion value. Of the 396 female whales identified, 41.41% were recaptured at least once. The final POPAN model showed time dependence in all parameters. The population size was estimated to be 397 reproductive females. This is the first update on the population trends for southern right whales in Brazilian breeding grounds since 2010.