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.

The killer whale (Orcinus orca) has a worldwide distribution and its feeding habits varies greatly among populations. In the southern Atlantic Ocean, knowledge about the distribution and diet of the species is still scarce. Herein we report the first evidence of a killer whale’s attack on a southern right whale (Eubalaena australis) in Brazilian waters and provide new records of killer whale sightings in coastal waters of the southernmost Brazilian region.

La orca (Orcinus orca) presenta una distribución global y una gran variación en los hábitos tróficos de sus poblaciones. En el Océano Atlántico Sur, el conocimiento sobre la distribución y la dieta de la especie es todavía escaso. En este trabajo, presentamos la primera evidencia de ataque de una orca a una ballena franca austral (Eubalaena australis) en aguas brasileñas y reportamos nuevos registros de avistamientos de orcas en aguas costeras de la región más austral de Brasil.

ABSTRACT Accurate estimates of group sizes through line transect sampling methods are important to correctly ascertain the abundance of animals that occur in groups. Since the average observed group size is a component of the distance sampling formula, bias in these data leads to biased abundance estimates. This study aimed to evaluate the potential errors in group size estimation during line transect ship surveys to estimate abundances of the humpback whale, Megaptera novaeangliae (Borowski 1781). In a research cruise along the Brazilian coast, an experiment to collect group size information was conducted from two different sighting platforms on the same vessel. Group sizes were recorded by primary observers at first sighting (PO1) and, in some cases, after some time (PO2). A tracker (T) was located on a higher platform to estimate the sizes of groups detected by the primary observers, but tracked one group at a time until it passed abeam. Thus, the dedicated effort to obtain multiple group counts (i.e. higher platform, more time and no responsibility for detecting new groups) was expected to provide more accurate numbers. PO2 estimates were compared with PO1 estimates, and T estimates were compared with both PO1 and PO2. Additionally, ratios between T and both PO2 (R1) and PO1 (R2), and between PO2 and PO1 (R3) were calculated. To investigate a possible improvement in abundance estimates, a correction factor (CF) was computed from the ratio of T and PO2 means. Primary observer self-correction (= 1.60, CV% = 70.3) was statistically similar to the correction for the tracker (= 1.62, CV% = 84.1). CF resulted in 1 and would not improve abundance estimates. This study supports that observers conducting line transect surveys on large whales have the potential to provide group size information that is as adequate as the correction procedure adopted.

The social structure of humpback whales in their tropical wintering grounds is very fluid. To date, no information has been published for cases in which two whales were both satellite-tagged while in association. Here, we report the movements of four humpback whale pairs tagged together off the coast of Brazil. Fieldwork and satellite tagging of humpback whales was conducted between 2003 and 2008 along the eastern coast of Brazil, between 20°S and 8°S. Movement was monitored while whales were still in their breeding ground. A switching state space model was applied to the filtered data of each humpback whale to standardize telemetry data and allow direct comparison of each individual track. GIS was used to plot model-predicted locations and to visually compare animal movements. The results confirm the short-lived nature of associations between breeding humpback whales, and shows that individuals differ widely in their movements.

Ship-based sighting surveys for cetaceans were conducted in the former whaling ground off the northeastern coast of Brazil. The cruises took place in winter and spring of 1998-2001 with the objectives of investigating current distribution and abundance of cetaceans, particularly large whale species taken during whaling. In 1998 the survey were conducted between the parallels 5°30'W and 9°S and the 200 m isobath and the meridian 033°W. A total of about 3,100 nm were surveyed between 1998 and 2001 Surveys were conducted using line transect methods from about 5-10°S, and from the coast to 33°W. A total of 151 sightings (203 individuals) of large whales were recorded on effort. The Antarctic minke whale - Balaenoptera bonaerensis (Burmeister, 1867) was the most frequently sighted species (97 groups/132 individuals; Sighting Rate [SR] = 0.031 groups/nm), being recorded only in offshore waters. Density gradually increased from August to October. Minke whales were distributed throughout the area, both to the north and the south of former whaling ground. Sighting data indicate this is the most abundant species, particularly in the area beyond the continental shelf break. Breeding behavior was observed for Antarctic minke whales, but few groups containing calves were recorded (4.3% of the groups sighted on effort). Three other large whale species were recorded in low numbers: the Bryde's whale - Balaenoptera edeni (Anderson, 1879)¹; the sei whale, B. borealis (Lesson, 1828), and the sperm, Physeter macrocephalus (Linnaeus, 1758). Sei, Bryde and sperm whales were regularly caught during whaling operations, but are rare in the area, suggesting they were depleted by whaling and have yet to recover to their pre-explotation abundance. In contrast, minke whales are abundant in this area, suggesting that either they were not substantially depleted, or that they have recovered rapidly. Blue whale, Balaenoptera musculus (Linnaeus, 1758), and fin whale, B. physalus (Linnaeus, 1758), not recorded on our surveys, have always been extremely rare in the area.