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Olivos, Argentina

Panebianco M.V.,CONICET | Del Castillo D.L.,CONICET | Denuncio P.E.,CONICET | Denuncio P.E.,University of the Sea | And 8 more authors.
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

The ovaries of 31 franciscana dolphins (19 immature and 12 mature) by-caught in coastal waters of Argentina were examined to describe the reproductive biology. No ovarian polarity was found, both ovaries were functional and showed similar amounts of corpora. A positive trend was observed between the number of corpora and age (3–8 years old), indicating that ovulation scars are detectable for at least 4 years, and a ovulation rate of 0.39 was found for the sampled population. Age, length and weight at sexual maturity were estimated at 3.92 ± 0.09 years, 133.47 ± 11.11 cm and 32.68 ± 2.72 kg, respectively. The annual pregnancy rate was 0.36 ± 0.02 (95% CI = 0.10–0.65). The proportion of lactating and resting females found were 0.25 and 0.33 respectively. These outcomes constitute the first reproductive and life history information on franciscana dolphins from the southernmost population and are important in relation with adequate conservation management plans for this small cetacean. Copyright © Marine Biological Association of the United Kingdom 2015

Gariboldi M.C.,Maimonides University | Gariboldi M.C.,CONICET | Tunez J.I.,CONICET | Tunez J.I.,National University of Lujan | And 10 more authors.
PLoS ONE | Year: 2015

Due to anthropogenic factors, the franciscana dolphin, Pontoporia blainvillei, is the most threatened small cetacean on the Atlantic coast of South America. Four Franciscana Management Areas have been proposed: Espiritu Santo to Rio de Janeiro (FMA I), São Paulo to Santa Catarina (FMA II), Rio Grande do Sul to Uruguay (FMA III), and Argentina (FMA IV). Further genetic studies distinguished additional populations within these FMAs. We analyzed the population structure, phylogeography, and demographic history in the southernmost portion of the species range. From the analysis of mitochondrial DNA control region sequences, 5 novel haplotypes were found, totalizing 60 haplotypes for the entire distribution range. The haplotype network did not show an apparent phylogeographical signal for the southern FMAs. Two populations were identified: Monte Hermoso (MH) and Necochea (NC)+Claromecó (CL)+Río Negro (RN). The low levels of genetic variability, the relative constant size over time, and the low levels of gene flow may indicate that MH has been colonized by a few maternal lineages and became isolated from geographically close populations. The apparent increase in NC+CL+RN size would be consistent with the higher genetic variability found, since genetic diversity is generally higher in older and expanding populations. Additionally, RN may have experienced a recent split from CL and NC; current high levels of gene flow may be occurring between the latter ones. FMA IV would comprise four franciscana dolphin populations: Samborombón West+Samborombón South, Cabo San Antonio+Buenos Aires East, NC+CL+Buenos Aires Southwest+RN and MH. Results achieved in this study need to be taken into account in order to ensure the long-term survival of the species. © 2015 Gariboldi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Failla M.,Fundacion Cethus | Seijas V.A.,Proyecto Patagonia Noreste | Esposito R.,Proyecto Patagonia Noreste | Iniguez M.A.,Fundacion Cethus
Marine Biodiversity Records | Year: 2012

Studies on the biology of the franciscana dolphin (Pontoporia blainvillei) in the Río Negro Estuary (RNE), Patagonia, Argentina, were carried out from 2002 to 2011. Information about group size, group dispersion and behaviour was collected from the coast and by boat, using scanning and focal animal/group sampling methodology. Group size varied from 1 to 5 dolphins ( X = 1.69; standard deviation (SD) = 0.74; N = 121), 2 being the most frequent value (46.28%; N = 56). Group dispersion varied from 0 to 10 dolphin length (DL) ( X = 1.4; SD = 0.75; N = 51), 0 DL (54.9%; N = 28) being the most frequent value. Behaviour of travelling, feeding, milling and resting were recorded, with a higher frequency of animals travelling (36.58%; N = 45). Calves were observed in spring and summer (N = 10). 13 stranded individuals were reported and 3 of them were collected from gillnets. Data presented herein indicate year-round presence of franciscana as well as the RNE being the southernmost breeding and feeding site reported to date. The establishment of the proposed natural reserve by the Governments of Río Negro and Buenos Aires provinces and continued long-term studies are urgently recommended. © 2012 Marine Biological Association of the United Kingdom.

Reyes Reyes M.V.,University of Buenos Aires | Tossenberger V.P.,Fundacion Cethus | Iniguez M.A.,Fundacion Cethus | Hildebrand J.A.,University of California at San Diego | Melcon M.L.,University of California at San Diego
Marine Mammal Science | Year: 2016

Cetaceans produce a variety of vocalizations to communicate; however, little information exists on the acoustic behavior displayed by Commerson's dolphins (Cephalorhynchus commersonii) in the wild other than their echolocation behavior. Most available literature suggests that Commerson's dolphins do not produce any other sound type besides narrow-band high-frequency (NBHF) clicks, such that no signals are emitted below 100 kHz. We conducted acoustic recordings together with sightings to study the acoustic behavior of Commerson's dolphins in Bahia San Julian, Argentina. This is the first study that provides evidence that this species produces a variety of acoustic signals, including whistles and broad-band clicks (BBC), with frequency content well below 100 kHz. Whistles were recorded mostly in the presence of mother and calf and were associated with parental behavior. BBC may be used for communication purposes by adults. These vocalizations are within the hearing range of killer whales and so could pose a risk of predation for Commerson's dolphins. Whether this population of Commerson's dolphins produce all these types of signals while they are in the open sea out of the waters of Bahía San Julián, which are apparently safe from predation, remains unknown. © 2016 Society for Marine Mammalogy.

Melcon M.L.,Fundacion Cethus | Failla M.,Fundacion Cethus | Iniguez M.A.,Fundacion Cethus
Journal of the Acoustical Society of America | Year: 2012

Franciscana dolphins are small odontocetes hard to study in the field. In particular, little is known on their echolocation behavior in the wild. In this study we recorded 357 min and analyzed 1019 echolocation signals in the Rio Negro Estuary, Argentina. The clicks had a peak frequency at 139 kHz, and a bandwidth of 19 kHz, ranging from 130 to 149 kHz. This is the first study describing echolocation signals of franciscana dolphins in the wild, showing the presence of narrow-band high frequency signals in these dolphins. Whether they use other vocalizations to communicate or not remains uncertain. © 2012 Acoustical Society of America.

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