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17109
Open
Abundance of the endangered franciscana in southern Brazil
Federico Sucunza, Daniel Danilewicz, Marta Cremer, Emanuel Ferreira, Pablo Denuncio
International Whaling Commission
2020
SC/68B/ASI/06
The franciscana (Pontoporia blainvillei) is endemic to coastal waters from Brazil to Argentina. The species is regarded as one of the most threatened cetaceans in the South Atlantic Ocean due to high bycatch levels. Four management units "FMAs" were defined throughout the species' range. FMA III includes states along southern Brazil and the whole Uruguayan coast. Between 07-24 March 2014 aerial surveys were conducted to estimate density and abundance of franciscanas off the Brazilian sector of FMA III. A total of 3,853 km of on effort tracklines were surveyed and 84 franciscana groups were recorded (ntotal = 167 individuals, mean group size = 1.99, SE = 0.91, median = 2, range = 1-5). Density corrected for visibility bias and group size bias was estimated at 0.31 individuals/km2 (CV = 0.24, 95% CI = 0.19 - 0.50). This estimate corresponds to a total abundance of 9,651 individuals (CV = 0.24, 95% CI = 6,013 - 15,490) in the Brazilian region of FMA III.
