Latin American Journal of Aquatic Mammals (LAJAM)
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Finding of a skull of Pseudorca crassidens in Caleta de Los Loros, Rio Negro Province, Argentina
No full textThe false killer whale, Pseudorca crassidens, exhibits one of the widest and most continuous distributions among cetaceans. However, basic information about its biology is poorly known due to the low frequency of sightings and its offshore habits. Moreover, most of the knowledge on this species has been obtained from stranded animals. On 3 March 2012, in the proximity of a colony of South American sea lions (Otaria flavescens) located at Caleta de los Loros, Río Negro Province, Argentina (40o59’S, 64o14’W), a cetacean skull was found in the intertidal zone. The specimen was later identified as P. crassidens. The present note reports a new record of false killer whale in the continental shelf waters of Argentina and provides new data on the distribution and skull morphometrics of the species
Distribution and status of giant otter (Pteronura brasiliensis) in the Pantanal wetland, Brazil
No full textThe giant otter (Pteronura brasiliensis) is listed as vulnerable in Brazil, is included in Appendix I of CITES and is classified as endangered by the IUCN. In Brazil, few viable populations persist outside the Amazon basin and the Pantanal wetland. Furthermore, there is limited information on the distribution and abundance of the existing populations. The aim of this study was to estimate the abundance of giant otters in the Pantanal wetland and to discuss the conservation status of this population. From July 2000 to November 2011 we conducted surveys throughout the Pantanal to detect the occurrence of giant otters by the observations of active dens and latrines and the direct visualization of the otters. We also monitored giant otter population in five rivers, which allowed us to obtain information on number of individuals, group size and linear density. The species was found to occur in almost every river stretch within the Pantanal wetland, as well as in several aquatic habitat types, indicating a remarkable recovery since the over-hunting during the 1960s. The population of giant otter in the Pantanal may reach 3969 (SD = 1103) individuals, based on our estimated number of individual per kilometer of rivers and creeks (0.54 ± 0.15), over a total of about 7350km of rivers and secondary channels occurring in the Pantanal. These results indicate that the Pantanal is an important area to preserve the giant otter and its habitat, despite the many threats that the species still faces in the region, such as increased vessel traffic, pollution and siltation, as well as disruption of the hydrological characteristics due to the construction of dams and river-bed sedimentation
Editorial
No full textDuring the IX Congress of Wildlife Management, in May 2010, in Bolivia, a meeting with attending giant otter researchers was called to discuss the progress of research and conservation of Pteronura brasiliensis, which resulted in this issue
The use of premaxillary bones of six fish species in giant otter (Pteronura brasiliensis) diet analysis
No full textThe premaxillary bones of fish are considered key bones due to their highly differentiated features, allowing the identification to species level. When these bones are present in the latrines of giant otter (Pteronura brasiliensis), they can be used to identify fish species and estimate the size of prey consumed. We briefly describe the differentiable morphological characteristics of premaxillary bones,useful for the successful identification of six fish species which are important prey for giant otter in the Paraguá river (Bolivian Amazon): Hoplias malabaricus (family Erithrynidae), Serrasalmus rhombeus, Pygocentrus nattereri (family Characidae), Chaetobranchus flavescens, Satanoperca pappaterra and Astronotus crassipinnis (family Cichlidae). We also present the linear regression equations which can be used to estimate the standard length ofthese fish species based on their bone measurements. Overall, 19 latrine samples were analyzed, which contained 109 premaxillarybones of these six species. Of the bones collected, 53% allowed successful estimation of the standard length of the fish consumed. The use of premaxillary bones in diet studies has a high potential as it permits the identification and estimation of prey size for the majority of species consumed. This method is important for studying the size of the giant otter’s fish prey
Giant otter (Pteronura brasiliensis) distribution, relative abundance and conservation in northwestern Bolivia
No full textAt the end of the last century northwestern Bolivia was prioritized for further study in a national evaluation of the endangered giant otter (Pteronura brasiliensis). In this paper we present a decade of efforts to investigate and systematize data regarding the distribution and relative abundance of giant otters in this wilderness region including 435 distribution points generated from direct observations, confirmed giant otter signs, and interviews with park guards and local people from indigenous communities. We also sampled 1318.6km of river and stream along the Tuichi, Hondo, Arana, Machariapo, Upper Madidi, Enatahua and Heath rivers and their adjacent oxbow lakes in the Madidi National Park, as well as the Undumo and Tequeje rivers in the Tacana Indigenous Territory, and the lower and mid Madidi River and 42.14km of immediately adjacent oxbow lakes. Relative abundance was variable across the region ranging between 0.02 and 0.18 individual/km sampled in streams and rivers, and our data reveals a particularly important giant otter population along the Madidi River much of which remains unprotected. Our data and local reports point towards a possible population recovery within the Madidi and Pilon Lajas protected areas of the region over the last decade. In total we counted 271 animals, identifying 109 individuals through video and photographic throat pattern evidence. We argue that this previously undocumented population is of particular conservation importance due to its connectivity with the well-documented but currently threatened populations of neighboring southeastern Peru. Together northwestern Bolivia and southeastern Peru represent one of the most important conservation strongholds for this species
Detection of infection with Leptospira spp. in manatees (Trichechus inunguis) of the Peruvian Amazon
No full textThe Amazonian manatee (Trichechus inunguis) is an aquatic mammal (Family Trichechidae) that inhabits freshwater environments. It is endemic to the Amazon Basin, and occurs from Marajó Island (at the mouth of the Amazon River in Brazil) to the headwaters of the floodplain in Colombia, Peru and Ecuador. Little is known of the causes of death or the prevalence of zoonotic organisms in manatees from Peru; however, Leptospira spp. have been reported to cause mortalities in marine mammals. Here we evaluated the presence of Leptospira spp. antibodies in Amazonian manatees. To our knowledge, this is the first report of presence of antibodies against Leptospira spp. in aquatic mammals maintained in captivity in the Peruvian Amazon
Rediscovery of Pteronura brasiliensis in the Amanã Sustainable Development Reserve, Amazonas, Brazil
No full textThis research describes efforts to confirm and document the presence and distribution of giant otters in the Amanã Lake and surrounding creeks, where the species was considered locally extinct due to extensive historical culling. Fieldwork was conducted during the dry season, and consisted of surveying small creeks and shallow aquatic areas in the Amanã Lake by boat and canoe. Two teams, guided by local inhabitants, conducted the survey simultaneously. The spatial distribution of the species was recorded based on signs of presence. Only one giant otter sighting was recorded; however, a considerable number of giant otter signs was found. The study documented the reappearance of the species in the Amanã sector of Amanã Sustainable Development Reserve
Protection and monitoring of the giant otter (Pteronura brasiliensis) in Cantão State Park, Tocantins, Brazil
No full textIn 2010, the Instituto Araguaia, a local NGO, started a program to protect and monitor giant otters, and to use them as an umbrella and flagship species for the conservation of the Cantão ecosystem. As part of the program, a census was carried out to determine the giant otter population of a group of 16 lakes in the park, and this population was monitored over a 28-month period spanning three breeding seasons, between September 2010 and December 2012
South American sea lions (Otaria flavescens) and killer whales (Orcinus orca) attending chub mackerel (Scomber japonicus) commercial trawl fisheries over the Patagonian Shelf: a first report
No full textKiller whale-seal interactions have been reported for almost all pinniped species globally. However the literature on offshore interactions between killer whales and sea lions is rare for the South Atlantic, particularly in Argentine waters. Here we report for the first time the harassment of a South American sea lion (Otaria flavescens) by killer whales (Ornicus orca) while attending commercial fishing vessels in offshore national waters and describe a novel sea lion antipredator behaviour. These observations were made during an ongoing survey to assess seabird-fisheries interactions in the commercial trawl fishery off Argentina
Advances in the study of giant otter (Pteronura brasiliensis): ecology, behavior, and conservation: a review
No full textGiant otters, once targeted by the pelt trade to near extinction, are now legally protected and have made a comeback in some parts of their range. Our state of knowledge about the behavior and ecology of this apex predator has increased substantially since the first studies in the 1970s but remains incomplete. Negative anthropogenic pressures and conflicts affecting giant otters are intensifying and now take many forms, from extensive habitat loss and degradation, pollution, ecotourism with heavy impacts, to gold mining. We review the corpus of giant otter field research and findings since 1980 and discuss new findings and our shortfall of knowledge and its implications for the long-term conservation of the species