Numerical population estimates update for Southern Right Whales in Brazil
EDUARDO PIRES RENAULT-BRAGA, KARINA R. GROCH, PAULO CESAR SIM?ES-LOPES
Southern right whales use the Brazilian coast as a wintering area. This population was severely depleted by the whaling until 1973. Since 1980s studies have showed that the species isnow restricted to southern Brazil. Using photo-id data obtained from standardized aerial surveys from Florianópolis/SC (-27º.797/-48º.533) to Torres/RS (-29º.396/-49º.763), mark/recapture methods were used to estimate survival capture and recruitment probability, and population size using POPAN model, and population grow rate using PRADEL models. Data were collected in September from 2004-2018. The final model was selected by the lowest AIC. GOF tests were used to validate the models. It was tested differences among females (whales with a calf at least once in all dataset) and adults (males or female never spotted with calf) and the effect of time. It was identified 520 whales, 345 females and 175 adults. From the total, 40.58% of females and 3.55% of adults were recaptured at least once. The final POPAN model (AIC 1648.4025) fixed the survival in 0.99 for females and adults. Capture probability was different for females and adults having effect of time. Recruitment probability was the same form both classesand had effect of time. Population size was estimated in 569 (±38) for females and 2,626 (±737) for adults. The final PRADEL model showed that the population growth rate was the same and constant for females and adults (4.8% ±1.2%). GOFs tests did not indicated signal of response to capture (TEST2.CT: p=1) and there was no evidence of transiency (TEST3.SR: p=0.43). This is the first update of the population trends for Southern right whales in Brazilian breeding ground since 2010.