ABSTRACT
Abstract Genotypes of 10 microsatellite loci of 420 humpback whales from the Southwestern Atlantic Ocean population were used to estimate for the first time its contemporary effective (Ne) and census (Nc) population sizes and to test the genetic effect of commercial whaling. The results are in agreement with our previous studies that found high genetic diversity for this breeding population. Using an approximate Bayesian computation approach, the scenario of constant Ne was significantly supported over scenarios with moderate to strong size changes during the commercial whaling period. The previous generation Nc (Ne multiplied by 3.6), which should corresponds to the years between around 1980 and 1990, was estimated between ~2,600 and 6,800 whales (point estimate ~4,000), and is broadly compatible with the recent abundance surveys extrapolated to the past using a growth rate of 7.4% per annum. The long-term Nc in the constant scenario (point estimate ~15,000) was broadly compatible (considering the confidence interval) with pre-whaling catch records estimates (point estimate ~25,000). Overall, our results shown that the Southwestern Atlantic Ocean humpback whale population is genetically very diverse and resisted well to the strong population reduction during commercial whaling.
ABSTRACT
O comportamento das baleias jubarte foi observado para detectar diferenças nas probabilidades de ocorrência de determinadas categorias comportamentais observadas a partir de cruzeiros de pesquisa e de turismo. Foram analisados dados de 256 grupos observados durante os cruzeiros de pesquisa e 122 grupos em cruzeiros de turismo, nas temporadas de 2001 a 2003, no litoral norte da Bahia. A análise de rede bayesiana forneceu maiores probabilidades de ocorrência para as categorias do tipo deslocamento, socialização e agressivo, enquanto a análise comparativa não forneceu diferenças expressivas entre as duas categorias de cruzeiro. De acordo com as probabilidades de ocorrência da conduta repouso para grupos com filhote e devido a uma possível interrupção do ato de amamentação causada pelas embarcações, sugere-se uma distância mais conservativa e um menor tempo de permanência com esses grupos.
Humpback whales behavior was observed to determine the existence of differences between observations occurring from research vessels vs. whale-watching vessels. A total of 256 groups were observed from research vessels and 122 groups from whale-watching vessels during the breeding seasons from 2001 through 2003 in the northern coast of the state of Bahia, Brazil. A Bayesian network analysis yielded greatest probabilities of occurrence of the behavioral conducts traveling, socialization and aggressive. Significant behavioral differences between cruise types were not obtained through comparative analysis. Given the probability of occurrence of resting conducts in calf pods and the possibility of the interruption of suckling caused by vessels, it is suggested that a more conservative distance and shorter visits be adopted by whale-watching groups.