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Cetaceans were monitored along ca. 700 km of the southeast coast of Brazil (22°S to 25°S) from 1995 to 2014 using photo-identification. The objective of this study was to identify any presence of long-distance movements for monitored cetacean species and discuss implications. Data on long-range movements of four of the monitored species are presented after the analysis of 321,765 photographs taken for individual identification. Seven individuals from four populations of Guiana dolphins (Sotalia guianensis) considered resident to particular estuaries or bays were reported in dispersal involving movement between pairs of protected areas over long-range distances varying between 86 and 135 km. Three cataloged rough-toothed dolphins (Steno bredanensis), first seen in Guanabara Bay, Rio de Janeiro state (22°46'S) in November 2011, were sighted 240 km southwards as members of the same group in coastal waters of São Paulo state (23°46'S) in July 2014. Water depth for those sightings ranged from 16 to 52.7 m; local sightings of rough-toothed dolphins in Brazil have frequently been in shallow waters, but the species global distribution is usually associated with deeper waters. In a 27-day interval in the spring of 2012, a group of 16 orcas (Orcinus orca) travelled ca. 277 km in shallow coastal waters ranging from 20 to 30 m deep. Orcas are commonly observed between November and February in southeast Brazil, probably in search for prey. In summer months between 2012 and 2014, three Bryde's whales (Balaenoptera edeni) sighted in waters ranging from 14 to 49 m deep, moved between 218 and 327 km. Bryde's whales are usually found in local coastal waters where they spend summer months feeding on sardines. To date, these are the longest estimated movements reported to S. guianensis, S. bredanensis, O. orca and B. edeni in the Southwestern Atlantic Ocean. [ABSTRACT FROM AUTHOR]

1. The common dolphins (genus Delphinus) have one of most problematic taxonomies and complex distribution patterns of all cetaceans. Although the taxonomy and the distribution seem to have been clarified somewhat in the eastern North Pacific and Indo-Pacific Oceans, many questions remain in the Southwestern Atlantic Ocean (SWA). We review the biogeography of Delphinus in the SWA. 2. We reviewed data from strandings, incidental catches and sightings since 1922. Systematic surveys were conducted in five major areas. Twenty-one natural history collections were examined, and 135 skulls were measured. 3. A total of 184 records of common dolphins were compiled. Delphinus apparently occurs in three stocks in the SWA: one located in northern Brazil and two from southeastern Brazil (∼22°S) to central Argentina (∼42°S). Two distinct patterns in habitat use were observed by depth: in southeastern Brazil, sightings were restricted to coastal waters with water depths ranging from 18m to 70m. On the other hand, in the area that extends from southern Brazil to Central Argentina (from 28°S to 42°S), sightings were recorded in deeper waters, ranging from 71m to 1435m, with the exception of occasional coastal sightings. The cranial analyses demonstrated that both short-beaked common dolphins Delphinus delphis and long-beaked common dolphins Dephinus capensis occur in the SWA. 4. In the SWA, Delphinus seems to occur near areas of high productivity. One stock is associated with the productive waters discharged by the Amazon River and possibily with the coastal upwelling system off the coast of Venezuela, while the other stocks are associated with the Cabo Frio upwelling system and the Subtropical Convergence. Our results indicate that the current taxonomy does not adequately reflect the amount of variation within the genus in the world. [ABSTRACT FROM AUTHOR]

Baseline demographic information is essential for effective conservation and management strategies for most living species. The abundance of Guiana dolphins (Sotalia guianensis) is poorly known, yet species conservation is considered high priority in areas where human activities may induce population declines. This study estimated abundance for Guiana dolphins in the Cananeia estuary (25° 03' S, 47° 55' W) in southeastern Brazil using mark-recapture data and Pollock's Robust Design Model. Systematic boat-based photo-identification surveys were based on data collected in the summer and winter of 2015 and in the summer of 2016. A total of 55 capture gathevents allowed identification of 133 different individuals. The best model indicated a population with random temporary emigration, a time-constant survival rate, and heterogeneous time-varying capture probabilities among primary surperiods. The temporary emigration rate (γ"=γ') was 0.05 (± 0.03). Estimated population sizes were 430 (95% CI: 410 to 451) individuals in the relsummer of 2015, 384 (95% CI: 366 to 403) individuals in the winter of 2015, and 414 (95% CI: 392 to 438) individuals in the summer of 2016, indicating that environmental variables among seasons may have a mild effect on the estimated size of this surveyed population. These estimates should stand as an important baseline for future comparisons. Systematic, long-term monitor-identiing of this population is recommended, and is required to accurately assess population trends. [ABSTRACT FROM AUTHOR]