Reports of strandings and sightings of bottlenose dolphins (Tursiops truncatus) in northeastern Brazil and Brazilian oceanic islands

Abstract

This study revises and updates information on bottlenose dolphin Tursiops truncatusstrandings and sightings in northeastern Brazil. A total of 72 strandings were recorded from 1992 to 2010, and 51 sightings were recorded from 1988 to 2010 along the states from Ceará to Bahia, including Fernando de Noronha and São Pedro and São Paulo archipelagos, Rocas Atoll and Abrolhos Bank. Most strandings were recorded in the states of Pernambuco, Bahia and Rio Grande do Norte. The number of reports was higher during summer, but no statistically significant difference was found between summer and other seasons. The majority of the stranded animals were adults (70.6%). Stranded calves were not observed. Total body length ranged from 138 to 321cm: 138 to 310cm for males; and 168 to 288cm for females. The average adult body length was 281cm (SD = 0.22). For stranding events where sex was determined (n = 29), a highly statistically significant difference was found between the number of males (n = 21) and females (n = 8). A total of six animals (8.3%) showed evidence of fisheries interactions such as net marks or removal of meat, blubber and eyes. Twenty-two sightings were recorded in the northeastern region, mostly in small islands and Rocas Atoll. This finding shows that the bottlenose dolphin is mainly an oceanic species in the region. More efforts are needed to improve our understanding of the populations and conservation status of bottlenose dolphins in this region.

Biology and ecology of bottlenose dolphins (Tursiops truncatus) stranded and sighted at 25°S in the south-western Atlantic Ocean during 1989–2016

“…The maximum TLs of T . truncatus recorded in this study were 320.00 cm for a male and 279.00 cm for a female, which are similar to those noted off north-eastern Brazil (TL = 321 cm; Meirelles et al , 2017) and São Paulo (TL = 315.00 cm) (Siciliano et al , 2007), but smaller than from further south off Rio Grande do Sul (TL = 385.00 cm; Fruet et al , 2012). Such differences might be due to various effects, including fishing-gear selectivity, population variations among body size and even sexual dimorphism and ages.…”

“…Such differences might be due to various effects, including fishing-gear selectivity, population variations among body size and even sexual dimorphism and ages. With respect to the latter, and similar to that described off north-eastern Brazil (Meirelles et al , 2017), juveniles/subadults were the most frequent age class in the sample. Nevertheless, because neither the causes of death nor ages could be determined, no hypothesis addressing age-specific health deterioration or overlapping impacts due to habitat segregation can be postulated.…”

Pathology and causes of death in stranded humpback whales (Megaptera novaeangliae) from Brazil

“…This animal was infected by a new CeMV strain, Sotalia guianensis -CeMV. Additionally, evidence of bycatch and use of meat and blubber was observed in two bottlenose-dolphins ( Tursiops truncatus ) found stranded in the Abrolhos Bank seashore [ 25 ].…”

Report of the Working Group on Taxonomy and Stock Identity of bottlenose dolphins in the Southwest Atlantic Ocean

“…The total length of the male syntype of T. gephyreus from the La Plata River was 276.0cm (Lahille, 1908). Although some variation was detected among the regions (Table 1), the largest animals reported in northeastern Brazil (Meirelles et al, 2016) were smaller than those recorded along Rio Grande do Sul and Uruguay J. Wickert, unpub.…”