Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul

Osório, Brazil

Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul

Osório, Brazil
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Audibert P.,University of the Rio dos Sinos Valley | Drehmer C.J.,Federal University of Pelotas | Danilewicz D.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Danilewicz D.,State University of Santa Cruz | de Oliveira L.R.,University of the Rio dos Sinos Valley
Journal of the Marine Biological Association of the United Kingdom | Year: 2017

Age is one of the most important life history parameters required to understand the dynamics of mammalian populations. Growth Layers Groups (GLGs) are incremental units of calcified tissue in the teeth (dentine and cementum), which represent a pattern of cyclical deposition that can be counted. However, the estimation of absolute age in GLGs demands a skull with teeth, the permission to destroy part of a tooth, equipment to cut the teeth, and experienced GLGs readers. In 1954 Sivertsen proposed an alternative method using cranial suture age (CSA) to establish age categories. However, there are no studies validating the CSA in relation to GLGs. Thus, this study examined whether there is a correlation between age categories proposed by the CSA and chronological age in years from GLGs of South American fur seals (Arctocephalus australis) (N = 52) and of South American sea lions (Otaria flavescens) (N = 37). 93% of the skulls of A. australis and 83.8% of O. flavescens corresponded accurately to the age in years estimated by each cranial suture age range. These results indicated the existence of high correspondence between the CSA and the GLGs age (r: 0.491 for A. australis and r: 0.675 for O. flavescens). However, an adaptation to Sivertsen's method is recommended: using only eight sutures (excluding the premaxillary-maxillary suture for CSA analysis, due to its late fusion), and updating the intervals for cranial sutures, that correspond to 16–32 = adults, 11–15 = young and 8–10 = pups. Copyright © Marine Biological Association of the United Kingdom 2017


Machado R.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Machado R.,Federal University of Rio Grande do Sul | Ott P.H.,State University of Rio Grande do Sul | Moreno I.B.,Federal University of Rio Grande do Sul | And 5 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2015

This study describes operational interactions between coastal gillnet fishing and South American sea lions (Otaria flavescens) off the southern Brazilian coast. In total, 263 onboard surveys were carried out during three periods between 1992 and 2012 in fishing boats from two harbours on the northern coast of Rio Grande do Sul State: Passo de Torres (29°19'S; 49°43'W) and Imbé (29°58'S; 50°07'W). Interactions of South American sea lions were observed in 116 (24.0%) out of 484 fishing operations. These interactions were more frequent in fishing boats from Passo de Torres (frequency of occurrence FO = 42.8%) than those from Imbé (FO = 14.8%; P < 0.001) and during autumn and winter months. Interactions between South American sea lions and fishing activities with fixed bottom gillnets in Imbé were most frequent during period III of the study (2011/2012) (FO = 52.0%; P = 0.032). These results demonstrated that interactions are not as high as reported/complained about by the local fishermen who tend to exaggerate the impact of these interactions. © 2015 John Wiley & Sons, Ltd.


Pont A.C.,University of the Rio dos Sinos Valley | Marchini S.,University of Sao Paulo | Engel M.T.,University of the Rio dos Sinos Valley | Engel M.T.,Memorial University of Newfoundland | And 8 more authors.
Hydrobiologia | Year: 2016

We analysed the fishermen’s perceptions on the South American sea lions (Otaria flavescens) and its interactions with the local fishery close to the Wildlife Refuge of Ilha dos Lobos, a marine protected area in southern Brazil. Sea lions prey upon the same resources targeted by the fishermen. They repeatedly hunt on the nets and consequently damage them. In response, fishermen persecute sea lions. However, in conflicts with high-profile animals, the perceived damage often exceeds the actual evidence. Results from 100 interviews revealed that fishermen’s perception of damage and their attitudes were affected by age, hierarchical position in the crew, if fishing was the only source of income, and level of formal education. Greater perception of damage and more negative attitude were found among older, less educated sailor fishermen who had no other source of income besides fishing. The average fisherman had a relatively good knowledge about sea lions, but also a negative attitude towards them. We recommend actions addressing these negative attitudes through environmental education, with emphasis on adjusting exaggerated perceptions of impact and the potential of the species for wildlife tourism, as a vital step towards the conciliation of sustainable fisheries and O. flavescens conservation in the Brazilian coast. © 2015, Springer International Publishing Switzerland.


Machado R.,University of the Rio dos Sinos Valley | Machado R.,Federal University of Rio Grande do Sul | Machado R.,Federal University of Santa Catarina | Ott P.H.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | And 9 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2016

This study describes operational interactions between coastal gillnet fishing and South American sea lions (Otaria flavescens) off the southern Brazilian coast. In total, 263 onboard surveys were carried out during three periods between 1992 and 2012 in fishing boats from two harbours on the northern coast of Rio Grande do Sul State: Passo de Torres (29°19'S; 49°43'W) and Imbé (29°58'S; 50°07'W). Interactions of South American sea lions were observed in 116 (24.0%) out of 484 fishing operations. These interactions were more frequent in fishing boats from Passo de Torres (frequency of occurrence FO = 42.8%) than those from Imbé (FO = 14.8%; P < 0.001) and during autumn and winter months. Interactions between South American sea lions and fishing activities with fixed bottom gillnets in Imbé were most frequent during period III of the study (2011/2012) (FO = 52.0%; P = 0.032). These results demonstrated that interactions are not as high as reported/complained about by the local fishermen who tend to exaggerate the impact of these interactions. It is suggested that reduced fish stock and increased fishing effort during recent decades is raising the frequency of encounters with South American sea lions during fishing activities off the southern Brazilian coast. Therefore, the implementation of fishery management measures that reduce fishing effort and that integrate environmental education programmes are essential to reduce conflicts between fishing activities and the sea lions in the region. © 2015 John Wiley & Sons, Ltd.


Machado R.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Machado R.,Federal University of Rio Grande do Sul | Machado R.,Federal University of Santa Catarina | de Oliveira L.R.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | And 2 more authors.
Neotropical Biology and Conservation | Year: 2015

The population of the South American sea lion, Otaria flavescens (Shaw, 1800), in Uruguay is declining at an annual rate of 1.6 to 2.0%. Although the reasons are still unknown, interactions with fishing activities have been identified as a major cause. The individuals that arrive along the coast of Brazil come from the breeding colonies off Uruguay after their breeding period. We report here the first record of incidental catch of South American sea lions in Brazilian waters by a pair trawl. On July 17th, 2008 a young male of South American sea lion was incidentally caught during a commercial pair trawl fishing trip along the southern Brazilian coast (32º57’S, 52º31’W), in a depth ranging from 15 to 20 m. Despite being punctual, this record is an evidence of a potential major threat to South American sea lions in southern Brazil and Uruguay, since trawl industrial fishing is a very important economic activity in South Brazil. © 2015 by Unisinos.


Reis E.C.,State University of Rio de Janeiro | Aires R.M.,State University of Rio de Janeiro | Moura J.F.,Grupo de Estudos de Mamiferos Marinhos da Regiao dos Lagos | Matias C.A.R.,Grupo de Estudos de Mamiferos Marinhos da Regiao dos Lagos | And 5 more authors.
Genetics and Molecular Research | Year: 2011

There have been few studies on Magellanic penguins (Spheniscus magellanicus). In 2008, these penguins washed ashore along the Brazilian coast in unusually high numbers, some reaching as far as northeast Brazil. As Magellanic penguins show little sexual dimorphism, sex determination by morphological features is not accurate. Here, we tested a molecular procedure for sexing specimens of S. magellanicus washed ashore along the coasts of Sergipe, Rio de Janeiro and Rio Grande do Sul in 2008, comparing the sex ratio between these localities. Tissue samples were collected from 135 dead, beached specimens. We carried out total genomic DNA extraction and CHD-Z/CHD-W gene amplification by PCR using P2 and P8 primers. Amplicons were separated by 12% acrylamide gel electrophoresis. We found a greater proportion of females (70%). Sex could be determined because females have two intronic regions of CHD gene of different size in the sex chromosomes, visualized as two bands on the gel (380 and 400 bp approximately), while males have only one (400 bp). Therefore, this method proved to be effective and sensitive for sex determination of S. magellanicus individuals. Data on sex ratios are useful for understanding the dynamics and ecology of Magellanic penguin populations. © FUNPEC-RP.


Andriolo A.,Federal University of Juiz de fora | da Rocha J.M.,Instituto Aqualie | Zerbini A.N.,National Oceanic and Atmospheric Administration | Simoes-Lopes P.C.,Federal University of Santa Catarina | And 4 more authors.
Zoologia | Year: 2010

Ship-based sighting surveys for cetaceans were conducted in the former whaling ground off the northeastern coast of Brazil. The cruises took place in winter and spring of 1998-2001 with the objectives of investigating current distribution and abundance of cetaceans, particularly large whale species taken during whaling. In 1998 the survey were conducted between the parallels 5°30'W and 9°S and the 200 m isobath and the meridian 033°W. A total of about 3,100 nm were surveyed between 1998 and 2001 Surveys were conducted using line transect methods from about 5- 10°S, and from the coast to 33°W. A total of 151 sightings (203 individuals) of large whales were recorded on effort. The Antarctic minke whale - Balaenoptera bonaerensis (Burmeister, 1867) was the most frequently sighted species (97 groups/ 132 individuals; Sighting Rate [SR] = 0.031 groups/nm), being recorded only in offshore waters. Density gradually increased from August to October. Minke whales were distributed throughout the area, both to the north and the south of former whaling ground. Sighting data indicate this is the most abundant species, particularly in the area beyond the continental shelf break. Breeding behavior was observed for Antarctic minke whales, but few groups containing calves were recorded (4.3% of the groups sighted on effort). Three other large whale species were recorded in low numbers: the Bryde's whale - Balaenoptera edeni (Anderson, 1879), the sei whale, B. borealis (Lesson, 1828), and the sperm, Physeter macrocephalus (Linnaeus, 1758). Sei, Bryde and sperm whales were regularly caught during whaling operations, but are rare in the area, suggesting they were depleted by whaling and have yet to recover to their pre-explotation abundance. In contrast, minke whales are abundant in this area, suggesting that either they were not substantially depleted, or that they have recovered rapidly. Blue whale, Balaenoptera musculus (Linnaeus, 1758), and fin whale, B. physalus (Linnaeus, 1758), not recorded on our surveys, have always been extremely rare in the area. © 2010 Sociedade Brasileira de Zoologia. All rights reserved.


Tavares M.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Tavares M.,Federal University of Rio Grande do Sul | Moreno I.B.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Moreno I.B.,Federal University of Rio Grande do Sul | And 5 more authors.
Mammal Review | Year: 2010

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. 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. 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. 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. © 2010 The Authors. Journal compilation © 2010 Mammal Society.


Horn T.S.,Federal University of Rio Grande do Sul | Machado R.,Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul | Machado R.,Federal University of Rio Grande do Sul | Weiss C.V.C.,University of Cantabria | And 2 more authors.
Journal of Fish Biology | Year: 2016

Unusual catches of more than 4200 kg of the slender sunfish Ranzania laevis are described from the south-western Atlantic, corresponding to the largest aggregation records for the species. These unexpected records were associated with unusually warm currents in the area. Males and females were physiologically able to spawn at the moment of capture, suggesting the occurrence of reproductive aggregation in this species. © 2016 The Fisheries Society of the British Isles


PubMed | Grupo de Estudos de Mamiferos Aquaticos do Rio Grande do Sul, University of Cantabria and Federal University of Rio Grande do Sul
Type: Journal Article | Journal: Journal of fish biology | Year: 2016

Unusual catches of more than 4200 kg of the slender sunfish Ranzania laevis are described from the south-western Atlantic, corresponding to the largest aggregation records for the species. These unexpected records were associated with unusually warm currents in the area. Males and females were physiologically able to spawn at the moment of capture, suggesting the occurrence of reproductive aggregation in this species.

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