Resumo: A população das baleias-jubarte do estoque reprodutivo A está aumentando, e pouco se sabe sobre as rotas usadas pelas baleias que se movem a norte da maior área de reprodução do Brasil, o Banco dos Abrolhos. O objetivo deste estudo foi descrever os movimentos das baleias-jubarte em uma área de reocupação (Serra Grande, estado da Bahia, Brasil) através do monitoramento por ponto fixo para testar se os padrões de movimento mudam ao longo da temporada e entre os anos, devido à composição de grupos, estado comportamental, e distância à costa. A média da velocidade da pernada dos grupos observados foi de 6,88 (±2,92) km/h, apresentando uma correlação positiva com a distância à costa. Houve um aumento da velocidade da pernada e da distância à costa com o aumento do número de escortes nos grupos com filhotes. A linearidade média das trajetórias dos grupos foi de 0,81 (±0,19) e a taxa média de reorientação foi de 25,72 (±19,09) º/min. Observamos uma predominância das rotas com rumo para sul ao longo do estudo. No início da temporada, os grupos apresentaram movimentos mais erráticos, e os grupos se deslocando para sul apresentaram trajetórias mais lineares que grupos se movendo para norte ou para outras direções, indicando o início da migração de volta ao seu sítio alimentar. Estratégias para economizar energia e o contexto social afetam o movimento das baleias-jubarte em Serra Grande, resultando nos padrões observados de reocupação de habitat disponível e adequado a norte de Abrolhos. Desse modo, uma atenção especial deve ser dada para a gestão de atividades com o potencial para perturbar ou deslocar as baleias que usam a região para se reproduzir.

Abstract: The population of humpback whales from breeding stock A is increasing, and little is known about the routes used by humpbacks that move north of the main calving area of Brazil, the Abrolhos Bank. The aim of this study was to describe the movements of humpback whales in a reoccupation wintering area (Serra Grande, Bahia state, Brazil) based on land-based surveys to test if movement patterns change during the season and between years, due to group composition, behavioral state, and distance to the coast. The mean leg speed of the groups sighted was 6.88 (±2.92) km/h, and leg speed was positively correlated with distance to the coast. There was an increase in leg speed and distance to the coast with increasing number of escorts in the groups with calves. The mean linearity value for group trajectory was 0.81 (±0.19) and the mean reorientation rate was 25.72 (±19.09) º/min. We observed a predominance of trajectories heading south throughout the study. Groups exhibiting more erratic movements early in the season, and groups moving south showed more linear trajectories than groups moving north, indicating the beginning of their migration back to the feeding grounds. Energy conserving strategies and social context affect the movements of humpback whales in Serra Grande, resulting in the observed patterns of the reoccupation of available and suitable habitat north of Abrolhos. Thereby, special attention should be given managing activities with the potential to disturb or displace whales using the region to calve and breed.

ABSTRACT Boat engines increase the noise levels of the oceans, alter the acoustic environment of cetaceans and diminish their efficiency to echolocate. This study aims to determine if Guiana dolphins (Sotalia guianensis) are influenced by boat approaches. A land-based survey was conducted to record behavioral responses and count surfacing events of Guiana dolphins during 293 observation sessions from February to November 2014 in Pontal Bay, Ilhéus, Brazil. Ninety-eight behavioral responses to boat approaches of 93 dolphin groups were classified as negative (interruption or alteration of activity) or neutral (no response). The dolphins presented a neutral response to 90% of boats without engine approaches, 48% negative responses to inboard motorboat approaches, and 76% negative responses to outboard motor boat approach. Resting groups demonstrated 14 negatives and four neutral responses. Groups engaged in forage-feed activity presented ten negative and seven neutral responses while traveling groups exhibited 14 negative and 36 neutral responses. The average rate of surfacing events was significantly superior (P < 0.001) in the absence of boats (1.83 ± 0.90 surfacing events ind-1 min-1) than in their presence (1.34 ± 0.92 surfacing events/individual/minute). Guiana dolphins are exposed to an increasing number of anthropic perturbations and the evaluation of its behavioral responses to approaching boats is the first step to comprehend the real impact of boat encounters. Our results may contribute to the development of management strategies in estuarine areas to increase the conservation of the Guiana dolphins.