No abstract

Franciscana dolphin (Pontoporia blainvillei) whistles were documented for the first time during 2003-2013 in Babitonga Bay estuary, South Brazil, together with burst pulses. Recordings were made from small boats under good sea conditions, and recording equipment that allowed analysis of sounds up to 96 kHz. The recordings were made in the presence of 2-31 franciscana dolphins. During 23 h and 53 min, 90 whistles and 51 burst pulse series were recorded. Although Guiana dolphins (Sotalia guianensis) inhabit nearby waters, none were observed in the area during the recordings. The authors recorded ten types of whistles. The initial frequency varied between 1.6 and 94.6 kHz, and the final frequency varied between 0.7 and 94.5 kHz; the authors were not able to determine if dolphin whistles exceeded the 96 kHz recording limit of the authors' equipment, although that is likely, especially because some whistles showed harmonics. Whistle duration varied between 0.008 and 0.361 s. Burst pulses had initial frequencies between 69 and 82.1 kHz (77 ± 3.81). These results showed that P. blainvillei produces whistles and burst pulses, although they seem to be produced infrequently.

Resumo Encalhes de toninhas no litoral norte de Santa Catarina e informações sobre o período de nascimento.A toninha (Pontoporia blainvillei) é o pequeno cetáceo mais ameaçado do Atlântico Sul Ocidental. A captura acidental em redes de pesca é o maior problema para esta espécie ao longo de sua distribuição. As toninhas mortas encontradas nas praias são uma importante fonte de informações. O objetivo deste trabalho foi analisar os registros de carcaças de toninhas encontradas mortas no litoral norte de Santa Catarina, incluindo a Baía da Babitonga. Entre janeiro de 2001 e novembro de 2012 foram registradas 54 carcaças de toninhas. Entre os meses de agosto e outubro foram registradas 28 carcaças (52%), sendo que o número mais elevado (oito indivíduos) foi encontrado em 2011. Levando em conta que estas informações não são decorrentes de um esforço sistematizado, não podemos considerar que esta seja uma estimativa de mortalidade. O maior animal registrado foi uma fêmea, com 142 cm de comprimento. Dentre os animais recuperados, 10 (18,5%) tinham comprimento total inferior a 80 cm, sendo considerados fetos ou filhotes. Estes registros indicam que o principal período de nascimento de toninhas em Santa Catarina é de outubro a janeiro. As informações aqui apresentadas contribuem para o conhecimento desta espécie no Estado. and November 2012, 54 franciscana carcasses were recorded, with the highest number (8 individuals) in 2011. Fifty-two percent (n=28) of the carcasses were recorded between August and October. Taking into account that this information was not obtained from a systematic effort, it was not possible to consider this as an estimation of mortality. The largest animal was a female, with a total length of 142 cm. Ten recovered animals (18.5%) were smaller than 80 cm, and were considered fetuses or calves. These records indicate that the main birthing period for franciscanas in Santa Catarina is between October and January. The findings presented here contribute to our knowledge of franciscana ecology in the state of Santa Catarina.

On October 2011, a newborn franciscana dolphin with an anomalously coloration was sighted in Babitonga Bay, southern Brazil. The calf was totally white. Besides the potential mother and newborn, the group also had the presence of another adult, who always was swimming behind the pair. Both adults had the typical coloration of the species, with the back in grayish brown. The group, composed by the white franciscana calf, his pontential mother and one more adult, was reported in five occasions. The group was always in the same area where it was first recorded and showed the same position during swimming. Between first and last sighting of the white calf (113 days) the color has not changed. This is the first case of a white franciscana dolphin. This coloration has never been reported despite the high number of dead franciscanas recovered each year along the distribution of the species, resulting from accidental capture in fishing nets. This fact leads us to believe that this is a very rare characteristic for this species. We considered the possibility that this franciscana could be an albino dolphin.

Calculation of echolocation signals emission rate is necessary to estimate how many individuals are vocalizing, especially if passive acoustic density estimation methods are to be implemented. We calculated the individual emission rate of echolocation signals of franciscana dolphin. Fieldwork was between 22 and 31 January of 2014 at Babitonga Bay, Brazil. Acoustic data and group size were registered when animals were within visual range at maximum distance of 50 meters. We used a Cetacean Research™ hydrophone. The sound was digitized by Analogic/Digital IOtech, stored as wav-files and analyzed with Raven software. A band limited energy detector was set to automatically extract echolocation signals. The emission rate was calculated dividing the clicks registered for each file by the file duration and by the number of individuals in the group. We analyzed 240 min of sound of 36 groups. A total of 29,164 clicks were detected. The median individual click rate was 0.290 clicks/s (10th = 0.036 and 90th = 1.166 percentiles). The result is a general approximation of the individual echolocation signal emission rate. Sound production rates are potentially dependent on a number of factors, like season, group size, sex, or even density itself. [This study was supported by IWC/Australia, Petrobras, Fundo de Apoio à Pesquisa/UNIVILLE.]