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Maritza Sepúlveda - One of the best experts on this subject based on the ideXlab platform.
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FDM - On Ignorance Regions and Spatial Aspects for South American sea lion (Otaria byronia) Operational Interaction with the Artisan Gillnet Fishery in Chile
Finite Difference Methods. Theory and Applications, 2019Co-Authors: Milan Stehlík, Maritza Sepúlveda, Jean Paul Maidana, Claudia Navarro Villarroel, Doris OlivaAbstract:The South Pacific Hake (Merluccius gayi) is the main artisan gillnet fishery in central Chile and the South American sea lion (SASL, Otaria byronia) has a strong operational interaction with this fishery. This was analyzed in paper [2] and several issues, like ignorance regions and spatial variation of such conflicts have not been studied in detail. In this paper we provide such analyses in order to complement the study. In particular, we show that construction of ignorance regions and its boundaries in the parameter space for SASL, dist, season4 and depth variables of interest could play an important role in order to characterize and possibly to eliminate the inaccuracies in the results and decisions that could be made.
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A Simulation-Based Study on Bayesian Estimators for the Skew Brownian Motion
MDPI AG, 2016Co-Authors: Manuel Barahona, Maritza Sepúlveda, Laura Rifo, Soledad TorresAbstract:In analyzing a temporal data set from a continuous variable, diffusion processes can be suitable under certain conditions, depending on the distribution of increments. We are interested in processes where a semi-permeable barrier splits the state space, producing a skewed diffusion that can have different rates on each side. In this work, the asymptotic behavior of some Bayesian inferences for this class of processes is discussed and validated through simulations. As an application, we model the location of South American sea lions (Otaria flavescens) on the coast of Calbuco, southern Chile, which can be used to understand how the foraging behavior of apex predators varies temporally and spatially
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Ovarian folliculogenesis in the southern sea lion Otaria flavescens
Acta Zoologica, 2011Co-Authors: Francisco Palma-cerda, Maria Maddalena Di Fiore, Maritza Sepúlveda, Luis Rene Duran, Franca RaucciAbstract:Palma-Cerda, F., Di Fiore, M.M., Sepulveda, M., Duran L.R. and Raucci, F. 2011. Ovarian folliculogenesis in the southern sea lion Otaria flavescens. —Acta Zoologica (Stockholm) 93: 444–452. In Otaria flavescens, folliculogenesis occurs within ovary cortex. This process attains successively higher level of organization through cell proliferation and differentiation. Here, we identified eight major follicular stages from I to VIII, plus corpus luteum and corpus albicans. Otaria folliculogenesis is divided into (1) primordial follicle recruitment; (2) pre-antral follicle development; (3) growth of antral follicle; and (4) follicle atresia. The primordial follicle is surrounded by thin and flat granulosa cells. As recruitment occurs, granulosa cells organize into cuboidal monolayer marking the transition into pre-antral phase. Pre-antral phase (from stage I to stage V) is characterized by follicular growth and theca layer formation. The typical feature of the antral phase (from stage V to pre-ovulatory Graafian follicle or stage VIII) is the formation of a fluid-filled cavity (antrum) within the follicle. In the Graafian preovulatory follicle, theca cells organize two distinguishable layers surrounding the follicle. In gravid females, the corpus luteum persists. In nongravid females, the corpus luteum transforms into corpus albicans. The corpus albicans is formed by granulosa, thecal cells, and invading blood tissue. Our results provide a detailed histological description of follicular development in O. flavescens and add new knowledge to the reproductive biology of this species.
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The predation of farmed salmon by South American sea lions (Otaria flavescens) in southern Chile
ICES Journal of Marine Science, 2009Co-Authors: Juan Vilata, Doris Oliva, Maritza SepúlvedaAbstract:Vilata, J., Oliva, D., and Sepulveda, M. 2010. The predation of farmed salmon by South American sea lions (Otaria flavescens) in southern Chile. - ICES Journal of Marine Science, 67: 475-482.The South American sea lion Otaria flavescens is abundant off southern Chile. Because Chilean salmon farming has experienced an explosive growth in the past two decades, interactions between O. flavescens and this industry have increased. Fieldwork, including in situ behavioural observations, was carried out at three salmon farms off southern Chile from May to July 2008. The aim was to analyse possible patterns in the interactions and to evaluate whether they were influenced by the endogenous circa-rhythms of the species, prey size, tidal flux, and the use of an acoustic harassment device (AHD). The results showed that the attacks by O. flavescens followed seasonal patterns, with salmon predated more in autumn and winter, and daily patterns, with more interactions at night. In addition, attacks were more frequent on larger salmon, suggesting the existence of a prey-size preference. More sea lions were sighted at the ebb and flow tide peaks, when currents are stronger, suggesting that currents linked to tidal flux might facilitate the access of the sea lions to the farmed salmon. Although the use of AHDs appeared positive at one site, there is a strong suspicion that their efficacy may be site-specific.
Ricardo Bastida - One of the best experts on this subject based on the ideXlab platform.
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tecnica de marcado por decoloracion de pelo en el lobo marino Otaria flavescens descripcion y evaluacion del metodo
Mastozoología neotropical, 2013Co-Authors: Gisela Giardino, Ricardo Bastida, Agustina Mandiola, Julian Bastida, Pablo Denuncio, Mariela Dassis, Diego RodríguezAbstract:Hair bleaching marking technique in South American sea lions Otaria flavescens: Description and evaluation of method. The aim of this paper is to describe and evaluate the use of the hair discoloration method in South American sea lions, with an emphasis on its advantages and its potential use in future studies. For marking, stamp removable letters and numbers were used, connected to an extensible rod. The bleached marks obtained had a maximum duration of 347 days perfectly visible and, because of the combination of low cost and application simplicity, this technique is considered suitable for both short and long term non-invasive studies in pinnipeds. Palabras clave: Apostaderos portuarios. Identificacion individual. Pinnipedos. Marcacion.
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THE SOUTHERN SEA LION, Otaria BYRONIA OR Otaria FLAVESCENS?
Marine Mammal Science, 1993Co-Authors: Diego Rodríguez, Ricardo BastidaAbstract:: The status of the specific name of the Southern sea lion is controversial; currently two names are in use: Otaria flavescens (Shaw, 1800) and Otaria byronia (de Blainville, 1820). The former was based on a two-foot-long yellowish otariid collected in the Strait of Magellan and the latter on a skull stated to have been collected on the Tinian Island (Marianas Archipelago); unfortunately both holotypes are lost. Otaria flavescens has date priority over Otaria byronia, but its identification was uncertain. This paper focuses on analyzing the main features of Shaw's holotype (body length, ear size, and hair color), which fit with the features of a Southern sea lion pup. As this was a tangible specimen from a valid locality and has priority over other available epithets, the specific name of the Southern sea lion should be Otaria flavescens (Shaw, 1800).
Diego Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Reference Intervals of Mineral Elements in Plasma of Anesthetized Free-Ranging Adult Females of South American Sea Lion, Otaria flavescens
Biological trace element research, 2016Co-Authors: P. Polizzi, Diego Rodríguez, L. N. Chiodi Boudet, A. Ponce De León, M. Quiroga, S. Atkinson, M. GerpeAbstract:Levels of zinc (Zn), copper (Cu), potassium (K), calcium (Ca), magnesium (Mg), and phosphorus (P) in plasma of Otaria flavescens females (n = 29) were evaluated. Reference intervals were established for each element, being the first report for this species.
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The electrocardiogram of anaesthetized southern sea lion (Otaria flavescens) females.
Journal of veterinary cardiology : the official journal of the European Society of Veterinary Cardiology, 2015Co-Authors: Mariela Dassis, Diego Rodríguez, A. Ponce De León, E. Rodríguez, Eduardo F. CastroAbstract:Abstract Objectives The goal of this study was to characterize for the first time the electrocardiogram (ECG) of the southern sea lion (SSL) Otaria flavescens. Animals, materials and methods Thirteen wild SSL females were captured at Isla de Lobos (Uruguay) and anaesthetized with isoflurane. Electrocardiographic recording was performed on anaesthetized animals at ventral recumbence following standardized procedures. Results The ECG recordings showed normal sinus rhythm. Amplitude and duration of P and T waves, QRS complex, PR interval, QT interval and ST segment (STS) were determined for all animals in all leads. QT corrected was determined in lead II. P wave polarity was consistent among animals (positive in LI, LII, LIII and AVF leads and negative in AVL and AVR leads for all animals), but T wave polarity did not present any constant pattern among animals, being either positive, negative or biphasic in different leads and different animals. The PR interval (0.15 ± 0.2 s) was similar to the allometric prediction for most of mammalian species including humans. The STS were normal in 10 of the SSL but showed STS depression in three of the animals. Almost all animals had a negative electrical axis (−30° to −120°), with one exception that showed a positive electrical axis (120°). Mean eupnoeic heart rate was 104.61 ± 10.06 (range = 88–120) beats per minute. Conclusions This study was the first ECG description for this species, and provides valuable information for cardiac monitoring during anaesthesia.
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tecnica de marcado por decoloracion de pelo en el lobo marino Otaria flavescens descripcion y evaluacion del metodo
Mastozoología neotropical, 2013Co-Authors: Gisela Giardino, Ricardo Bastida, Agustina Mandiola, Julian Bastida, Pablo Denuncio, Mariela Dassis, Diego RodríguezAbstract:Hair bleaching marking technique in South American sea lions Otaria flavescens: Description and evaluation of method. The aim of this paper is to describe and evaluate the use of the hair discoloration method in South American sea lions, with an emphasis on its advantages and its potential use in future studies. For marking, stamp removable letters and numbers were used, connected to an extensible rod. The bleached marks obtained had a maximum duration of 347 days perfectly visible and, because of the combination of low cost and application simplicity, this technique is considered suitable for both short and long term non-invasive studies in pinnipeds. Palabras clave: Apostaderos portuarios. Identificacion individual. Pinnipedos. Marcacion.
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THE SOUTHERN SEA LION, Otaria BYRONIA OR Otaria FLAVESCENS?
Marine Mammal Science, 1993Co-Authors: Diego Rodríguez, Ricardo BastidaAbstract:: The status of the specific name of the Southern sea lion is controversial; currently two names are in use: Otaria flavescens (Shaw, 1800) and Otaria byronia (de Blainville, 1820). The former was based on a two-foot-long yellowish otariid collected in the Strait of Magellan and the latter on a skull stated to have been collected on the Tinian Island (Marianas Archipelago); unfortunately both holotypes are lost. Otaria flavescens has date priority over Otaria byronia, but its identification was uncertain. This paper focuses on analyzing the main features of Shaw's holotype (body length, ear size, and hair color), which fit with the features of a Southern sea lion pup. As this was a tangible specimen from a valid locality and has priority over other available epithets, the specific name of the Southern sea lion should be Otaria flavescens (Shaw, 1800).
Mario Georgenascimento - One of the best experts on this subject based on the ideXlab platform.
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pseudoterranova cattani sp nov ascaridoidea anisakidae a parasite of the south american sea lion Otaria byronia de blainville from chile
Revista Chilena de Historia Natural, 2000Co-Authors: Mario Georgenascimento, Ximena UrrutiaAbstract:Se describe al nematodo parasito Pseudoterranova cattani sp. nov. encontrado en el estomago del lobo marino comun Otaria byronia De Blainville, en muestras tomadas entre 1980 y 1997, a lo largo de la costa del centro-sur de Chile. Las larvas y adultos de esta especie han sido registrados en el oceano Pacifico sudoriental como Phocanema decipiens Myers. Las principales diferencias con las especies del Atlantico norte y del Pacifico noroccidental se basan en el tamano corporal y en el numero, tamano, distancia y proporciones de las papilas caudales
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micro evolutionary implications of allozymic and morphometric variations in sealworms pseudoterranova sp ascaridoidea anisakidae among sympatric hosts from the southeastern pacific ocean
International Journal for Parasitology, 1995Co-Authors: Mario Georgenascimento, A LlanosAbstract:We found significant morphometric and electrophoretic differences between sealworm larvae collected from four sympatric fish host species off the central coast of Chile. The South American sea lion, Otaria byronia, is a suitable host and most likely the only definitive host species in the study area. Morphological patterns of caudal papillae in adult males collected from sea lions and electrophoretic evidence from larvae and adults substantiate our conclusion that they belong to just one, new species yet to be described. The genetic and morphometric differences found between sealworm larvae from sympatric fish hosts may be due to selective pressures arising from the internal environment of the intermediate hosts, although they may serve only for passing sequential filters along the life cycle. The discussion deals with the roles that definitive and intermediate hosts may play in the micro-evolutionary processes of sealworms.
Enrique A. Crespo - One of the best experts on this subject based on the ideXlab platform.
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Improvement in Survivorship: The Key for Population Recovery?
Zoological studies, 2016Co-Authors: Maria Florencia Grandi, Silvana L. Dans, Enrique A. CrespoAbstract:Maria Florencia Grandi, Silvana L. Dans, and Enrique A. Crespo (2016) In northern Patagonia, commercial harvesting of South American sea lions, Otaria flavescens, from 1920 to 1960, decimated its population abundance. Population recovery was not immediate after hunting ceased in 1962. The population was stable until 1989, and since then has grown at an annual rate of increase of 5.7%. Along with this growth there was an increase of the juvenile fraction and changes in the social composition of colonies, which could be related to changes in some population vital rates. The aim of this study was to analyze changes in the survivorship pattern of Otaria flavescens through time. The ultimate goal was to contribute to a better understanding of changes that could have operated on the ecosystem after the decline and recovery of one of the main marine top-predators in the southern South Atlantic Ocean. The comparisons of survivorship curves of males and females, obtained from the life tables of two periods with different population trends: 1981-1987 (stationary) and 2000-2008 (recovering), showed that there were differences in survivorship between sexes, where recent female age-specific survival was higher than that of males at any age. The comparison of survivorship between periods showed differences in both sexes. Both juveniles and adults, both male and female, from the recent period showed higher survival than those of the 1980's decade. This improvement in survivorship could be one of the essential factors that drove population recovery in the last decades. Here we discuss the possible hypotheses of which factors could have changed in the ecosystem to favour juvenile and adult survivorship, such as an increase in the availability of food recourses, a decrease of exogenous mortality causes, or a combination of both factors.
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Anembryonic Gestation in Wild South American Sea Lion, Otaria flavescens.
Anatomia histologia embryologia, 2015Co-Authors: Maria Florencia Grandi, Enrique A. Crespo, Silvana Laura DansAbstract:We present the first record and description of an anembryonic gestation in a wild South America sea lion, Otaria flavescens (Carnivora, Pinniped). This is the first report of an anembryonic gestation in a wild marine mammal species. This description furthers the knowledge of general aspects of the reproduction of an otariid species, which presents the particularities of delayed implantation and polygynic breeding system, and adds information on a reproductive abnormality in marine mammals.
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trophic overlap between the south american sea lion Otaria flavescens and the demersal trawl fishery in san matias gulf patagonia argentina
Latin American Journal of Aquatic Research, 2011Co-Authors: Maria Alejandra Romero, Silvana Laura Dans, Raul Gonzalez, Guillermo Svendsen, Nestor A Garcia, Enrique A. CrespoAbstract:As world fisheries began to decline and massive collapses were observed, the competition between marine mammals and fisheries became an issue of growing concern. San Matias Gulf (Patagonia, Argentina) is considered to be a fishery ecosystem independent of the Argentine Continental Shelf waters, with particular oceanographic and biological properties. As a semi-enclosed ecosystem, this gulf may generate particular scenarios for interactions between the demersal trawl fishery fleet and the population of South American sea lions Otaria flavescens . In this paper, the diet of the top predator and the composition of fishery catches were characterized in order to assess the trophic overlap between these two components. This analysis and a comparison of the sizes of prey consumed revealed a low probability of competition for similar resources between the fishing fleet and the marine mammals in the San Matias Gulf ecosystem.
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Organochlorine residues in South American sea lions, Otaria flavescens (Shaw, 1800): bioaccumulation and time trends.
Bulletin of environmental contamination and toxicology, 2010Co-Authors: Asunción Borrell, Nestor A Garcia, A. Garcia-solà, Alex Aguilar, Enrique A. CrespoAbstract:Blubber from stranded South American sea lions (Otaria flavescens) was sampled between 1991 and 2005 on the Peninsula Valdes in Argentina and analyzed for organochlorine (OC) pollutants. Mean blubber concentrations, expressed on an extractable basis, were 686 (SD = 1,060) ng g−1 for dichlorodiphenyl trichloroethane (tDDT) and 735 (SD = 787) ng g−1 for polychlorinated byphenils (PCB). The OC levels were well below those associated with adverse sublethal effects and lethality in mammals. OC concentrations showed statistically significant associations with age that were positive in males and negative in females. These trends are consistent with the majority of marine mammal populations studied. There were no trends in the levels of tDDT or PCB over time. In spite of the low levels detected, OC contamination was present consistently over the 14-year period, suggesting continuous inputs from geographic redistribution.
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Recovery of the South American sea lion (Otaria flavescens) population in northern Patagonia
Canadian Journal of Fisheries and Aquatic Sciences, 2004Co-Authors: Silvana Laura Dans, Enrique A. Crespo, Susana N. Pedraza, Mariano Koen AlonsoAbstract:The size of and trend in the South American sea lion (Otaria flavescens) population located in northern Patagonia were estimated and changes in the distribution, size, and structure of individual s...
