Variación de la composición de la captura de peces en el río Paraná, durante el período 1941-1984

(Document contains 79 pages.)

El desarrollo de la cuenca del Plata y la prohibición al uso del "mallón" en la confluencia de los ríos Paraná y Paraguay

Document contains 30 pages.

Sobre estudios realizados en el Paraná. Sur de Córdoba y región de Uspallata.

Los resultados científicos de las excursiones de estudio realizadas a principios de 1937 han sido importantes, como así también las colecciones efectuadas, no sólo por el número de ejemplares, sino por las observaciones realizadas al obtenerlos, según el hábitat, la estación, el estado de los individuos, etc. El estudio de los materiales del Museo comparativamente con los ya catalogados permite elaborar contribuciones que se darán a conocer progresivamente o al tiempo que este informe, de caracter general, para satisfacer el deseo de la Dirección del Instituto de que sé de cuenta sobre los viajes efectuados. Se comprende que es un anticipo de una monografía científica.

Nota acerca de los nombres vernáculos de peces en el Paraná medio.

Lista complementaria del trabajo de Pozzi sobre Sistemática y distribución de los peces de agua dulce de la República Argentina, donde se incluyen sólo los nombres faltantes o los extensivos a otras especies o los que tengan distinta significación.

Parameter estimates for fishes of the upper Paraná river floodplain and Itaipu reservoir (Brazil)

Estimates of the growth (K), natural mortality (M), consumption/biomass (Q/B) rate and trophic level (TL) for 35 species in the upper Paraná river floodplain and the Itaipu reservoir (interconnected ecosystems) are presented. A compilation of these biological statistics is made for comparison purposes and some general trends are briefly discussed.

Age and growth of the estuarine dolphin (Sotalia guianensis) (Cetacea, Delphinidae) on the Paraná Coast, southern Brazil

Teeth of 71 estuarine dolphins (Sotalia guianensis) incidentally caught on the coast of Paraná State, southern Brazil, were used to estimate age. The oldest male and female dolphins were 29 and 30 years, respectively. The mean distance from the neonatal line to the end of the first growth layer group (GLG) was 622.4 ±19.1 μm (n=48). One or two accessory layers were observed between the neonatal line and the end of the first GLG. One of the accessory layers, which was not always present, was located at a mean of 248.9 ±32.6 μm (n=25) from the neonatal line, and its interpretation remains uncertain.The other layer, located at a mean of 419.6 ±44.6 μm (n=54) from the neonatal line, was always present and was first observed between 6.7 and 10.3 months of age. This accessory layer could be a record of weaning in this dolphin. Although no differences in age estimates were observed between teeth sectioned in the anterior-posterior and buccal-lingual planes, we recommend sectioning the teeth in the buccal-lingual plane in order to obtain on-center sections more easily. We also recommend not using teeth from the most anterior part of the mandibles for age estimation. The number of GLGs counted in those teeth was 50% less than the number of GLGs counted in the teeth from the median part of the mandible of the same animal. Although no significant difference (P>0.05) was found between the total lengths of adult male and female estuarine dolphins, we observed that males exhibited a second growth spurt around five years of age. This growth spurt would require that separate growth curves be calculated for the sexes. The asymptotic length (TL∞), k, and t0 obtained by the von Bertalanffy growth model were 177.3 cm, 0.66, and –1.23, respectively, for females and 159.6 cm, 2.02, and –0.38, respectively, for males up to five years, and 186.4 cm, 0.53 and –1.40, respectively, for males older than five years. The total weight (TW)/total length (TL) equations obtained for male and female estuarine dolphins were TW = 3.156 × 10−6 × TL 3.2836 (r=0.96), and TW = 8.974 × 10−5 × TL 2.6182 (r=0.95), respectively.

Bibliografía ictiológica del Delta del Paraná.

El Delta del Paraná es una región inconmensurable, mágica, llena de misterios y leyendas cuyos primeros registros históricos comienzan a partir del Siglo XVI (Athor, 2014). Liborio Justo en la introducción de “El Carapachay dice…”durante siglos, el Delta fue para la capital del país, a pesar de su vecindad, una tierra incógnita en la que jamás puso su atención, ni se preocupó en conocer ni ocupar, no obstante los beneficios que de ella recibía” agregando, ”…la primacía en la descripción del Delta del Paraná, desde el punto de vista literario, corresponde a Marcos Sastre quien, según Sarmiento fue el primer hombre culto que aplicó el raciocinio a la realidad y vio en las islas terrenos adaptables a la industria”. Este autor también comenta que, Santiago J. Albarracín (pariente de Sarmiento) dice “Apareció el Sr. Sarmiento y fue el primero de los publicistas que emprendió la propaganda de hacer poblar las islas”. Por sus características lo podríamos considerar como un “laboratorio a gran escala”, ya que en su “interior” suceden fenómenos físicos y biológicos que lo hacen único, en un área relevante de la Región Neotropical. No obstante, salvo casos puntuales, recién a partir de 1990 se han incrementado y tienen la continuidad necesaria diferentes líneas de investigación, principalmente, desde el Grupo de Investigaciones sobre Ecología de Humedales. Este fue dirigido en un principio por la ya fallecida Ana I. Malvárez y hoy se encuentra dentro del Instituto de Investigación e Ingeniería Ambiental (3iA) de la UNSAM liderado por Rubén Quintana. En este número, prosiguiendo con la política de difusión que hemos venido realizando hace más de treinta años desde el Instituto de Limnología “R. A. Ringuelet” (ILPLA) y la División Zoología Vertebrados del Museo de La Plata, aportamos una bibliografía ictiológica sobre esta particular área de nuestro territorio. Como dato histórico y curioso, podemos mencionar que el primer aporte formal en el Delta, sobre este grupo de vertebrados, surge desde la Universidad Nacional de La Plata, a través de un trabajo publicado en 1913 por el arqueólogo y etnógrafo Luis M. Torres del Museo de La Plata. Sin embargo, a pesar de nuestra experiencia en búsqueda de información, quizá pueda haber quedado algún incunable o trabajo moderno en un “agujero negro”. Si se diera esta situación, pedimos las disculpas del caso.

Ichthyological ecoregions of Argentina

The Argentine Republic is situated in the southernmost portion of the American continent, occupying over 2,785,600 km2 not including the Antarctic territory. The country ranges from subtropical areas (21º46’S) to subantarctic regions (55º03’S), extending latitudinally over about 4,000 km. It possesses significant latitudinal and altitudinal variation (33º of latitudinal range, and heights from Bajo de San Julián in Santa Cruz province at 105 m below sea level, up to Mt. Aconcagua, 6,959 m over sea level), as well as two gradients of physical variability, extending in north-south and east-west directions. Owing to these features, the country presents a wide range of climates and soil types, being one of the countries with greatest diversity of biogeographical units (Lean et al., 1990, In: Bertonatti & Corcuera, 2000). There are four main hydrographic systems: Río de la Plata basin, the Atlantic and Pacific drainages, and several endorrheic systems. Within these basins, the ichthyofaunistic assemblage is well represented, with different magnitude in accordance with the different taxonomic groupings and regions considered. From an ichthyogeographic standpoint, and according to the works of Ringuelet (1975) and Arratia et al. (1983), Argentina is included in the Brasilic and Austral Subregions. The first of these is represented by two domains: the Andean Domain, comprising the southernmost portion of Titicaca Province, and the Paranensean Domain, including part of Alto Paraná and Paranoplatensean Provinces. The Austral Subregion is represented in Argentina by the Subandean-Cuyan and Patagonian Provinces. The present survey indicates that there are about 441 fish species in Argentina, distributed throughout the country; this number represents less than 10% of the total fish species occurring in the Neotropical Region. There is a recognizable trend of faunal impoverishment, both in North-South and East-West direction, reaching its maximum expression in the provinces of Tierra del Fuego (situated at approximately 52º30’S to 55ºS, and 65ºS to 68º50’W) and San Juan (approximately 28º50’S and 67ºW to 70º45’W), which have 4 and 5 fish species respectively. In north-south direction, one of the regional indicators of this phenomenon is the Salado river basin in Buenos Aires province, which constitutes the southern distributional boundary for the majority of the paranoplatensean ichthyofauna; 12 of the families occurring in the Paraná-Plata system are absent from this pauperized paranensean ichthyofaunal assemblage. Most of the continental fish fauna of Argentina belongs to the primary division of Myers (1949), while some elements are included in the secondary division and others in an amphibiotic or ‘marine penetration’ category. This ichthyofaunistic scope encompasses a wide range of morphological, biological, ecological and ethological types (benthic and pelagic, migrating and sedentary, haematophagous or parasites, annual species, inhabitants of plains or heights, estivation-adapted, etc.) inhabiting different regions within the national territory.

Nota sobre Auchenipterus nuchalis (Spix) (pisces: Siluroidei).

Al estudiar la ictiofauna de agua dulce, especialmente la correspondiente al Paraná inferior, he encontrado en las colecciones del Museo de La Plata un lote de 20 ejemplares de la localidad de San Pedro (provincia de Buenos Aires)pertenecientes a la especie Auchenipterus nuchalis (Spix). Su descripción e ilustración. (PDF tiene 9 paginas.)

Redescription of Hypoptopoma inexspectata (Holmberg, 1883), with notes on its anatomy (Siluriformes: Loricariidae).

Hypoptopoma inexspectata is diagnosed and redescribed based on the examination of additional material and comparison with its congeners. This poorly known hypoptopomine species is distributed in the Paraguay and Paraná river draínages. Hypoptopoma inexspectata is diagnosable based on the autapomorphy biserial arrangement of anterior snout rostral margin odontodes, laterally extended to limit between second and third infraorbital plates, with dorsally directed dorsad series separated from ventrally directed ventrad series by a narrow odontode-free area, which at the level of first and second infraorbital plates is reduced to a dividing line of the series. The species can be further distinguished by the combination (1) low number of canal-bearing lateral plates (20-22, typically 21), (2) presence of a shield of prepectoral dermal plates, (3) arrangement of abdominal plates in one paired series of 3-5 plates, (4) shorter least interorbital distance 4856% head lengh, (5) larger horizontal eye diameter 17-20% head lengh, and (6) least orbit-nare distance 812% head lengh. Intraspecific variation skull dermal bones, neuracranium and suspensorium bones, dermal plates, adipose fin is reported. (PDF has 20 pages.)

Nota acerca de una especimen del género Potamotrygon (Chondrichthyes, Potamotrygonidae).

Its deal with the study of a sample of "river ray" of the Potamotrygonidae family procured in the Colastiné river (Midle Paraná)showing an external morphology relating it closely to two species of said family: Potamotrygon falkneri Castex y Maciel, 1963 and P. menchacai Martínez Achembach, 1965.

Areas de migración y ecología de la anchoa Lycengraulis olidus (Günther) en las aguas argentinas (Pisces, fam. Engraulidae)

The purpose of the present study was to confirm the migratory habits of the anchovy, Lycengraulis olidus (Günther), between fresh and sea water environments. Anchovies were examined from three freshwater localities: Bella Vista and Rosario (Paraná river) and Punta Lara (La Plata river), and from four marine localities; Mar del Plata, Bahia Blanca, San Blas and Patagones, all in the Argentine Republic. Five meristic and nine morphometric characters were selected for study, namely: vertebrae; dorsal, pectoral and anal fin rays; gill rakers on the first gill arch; head-length; body-depth; distance between the snout and dorsal, pectoral, ventral and anal fin; eye-diameter; snout and maxilary. The food of the anchovy in fresh and sea water consists principally of fish and crustaceans including copepods, paleamonids, sergestids and larvae of Brachyura. The condition factor of the anchovy was lower in the fresh-water samples and higher in the marine samples. (PDF has 32 pages (two pages on each)