Plenary Speaker: Conciliating fish ecology and river fragmentation in South American large rivers: Are fish passages appropriate tools?

Abstract: South America, the most fluvial continent, is increasingly been impacted by river damming having dams construction expanded in last 50 years and fragmenting more than 3,000 km. At present, the upper Parana basin exhibits 130 dams higher than 10 m, but most of future planned dams will be located along the Amazon watershed. Although increasing attention and research efforts have been devoted to assess functioning of fish passage in South America, objectives and support for installation can differ among basins according to river ecological characteristics, conservation goals, fisheries demands, etc. A noticeable asymmetry still exists between salmonids and non-salmonids fish passages in terms of information, research funds availability, human resources, availability of technological tools, etc. Whereas South American passes have shown a wide efficacy range, efficiency appears to be rather low for most of large migratory species challenging managers and scientists for considering how fragmentation effects on migratory fish population can be mitigated. Clearly non-salmonid fishways need to be designed to accommodate different life history traits exhibited by neotropical fishes inhabit rivers with different hydrological and geomorphological characteristics. Questions about how principles and rules derived from salmonid passages apply and what efficiency should mean and is required in South American large rivers remain still under debate as fish adaptation to cope with river fragmentation impacts may differ among basins based on hydrological and geomorphological features and dams/reservoirs characteristics. Managers and scientists face with the need to assess the feasibility of installing fish passages within a broader context that incorporate fish conservation issues according to current and predicted ecological characteristics and socio-economic scenarios at basin scale

Biology of growth of Hoplias aff. malabaricus (Bloch, 1794) in a shallow pampean lake Argentina

The trahira Hoplias aff. malabaricus is a top predator in pampean shallow lakes and is highly appreciated by recreational anglers and artisanal fishermen. Trahira growth from Yalca shallow lake was determined by lepidological analysis and age validated by marginal increment. When growth was fitted to the von Bertalanffy model, annual classes exhibited a bimodal pattern as a result of the presence of spring and summer annual cohorts associated with a three month spawning season, each period in turn showing different growth patterns. The trahira population-age structure at Yalca shallow lake showed a truncated profile with very low numbers of large adults and few individuals older than three to four years, thus producing an unbalanced length-structure population. Growth parameters and growth performance were similar to the corresponding parameters estimated for other shallow pampean lakes of the region, but strongly diverged from the data for those populations inhabiting subtropical and tropical environments. Such differences could be accounted for by dissimilarity in metabolic rates associated with thermal differences accompanying seasonal variability among latitudes as well as by the development of adaptive physiologic and demographic responses to cope with the high thermal amplitude and hydrologic instability observed in pampean lakes.A traíra Hoplias aff. malabaricus é um predador de topo encontrado em lagoas rasas nos Pampas, muito apreciada nas pescas comerciais e esportivas. O crescimento da traíra no lago Yalca foi determinado através de análises lepidológicas, validadas a partir do incremento marginal. O crescimento foi ajustado ao modelo de von Bertalanffy, sendo que as classes de tamanho anuais apresentaram padrão bimodal devido à presença de coortes de primavera e verão, associadas à uma longa estação reprodutiva com diferentes padrões de crescimento. A estrutura etária da traíra do lago Yalca apresentou um perfil truncado, com um número pequeno de adultos de maior porte e poucos indivíduos com mais de três ou quatro anos, produzindo uma estrutura em tamanho desbalanceada. Os parâmetros e a performance de crescimento foram similares aos estimados para outros lagos rasos da região, mas fortemente divergentes de populações encontradas em ambientes tropicais e subtropicais. Tais diferenças podem estar relacionadas à diferentes taxas metabólicas associadas à variação térmica sazonal entre latitudes e ao desenvolvimento de respostas adaptativas fisiológicas e demográficas em resposta aos padrões termais altamente variáveis e instabilidade hidrológica observados nos lagos da região dos Pampas.Fil: Balboni, Leandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Colautti, Dario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Baigún, Claudio Rafael M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin

Conserving the Paraguay-Paraná Fluvial Corridor in the XXI Century: Conflicts, Threats, and Challenges

The Paraguay-Paraná river system represents a unique, free-flowing corridor that extends about 3500 km southwards from the Pantanal to the Rio de la Plata estuary, crossing four countries. The absence of fragmentation along the main channels and its still well-connected floodplains have preserved longitudinal and lateral functional and structural connectivity, defining critical ecological gradients for the biota and species life cycles. The lack of dams represents a noticeable feature that benefits migratory species supporting small-scale fisheries providing food security and the conservation of other ecosystem services with associated livelihoods. The ecological integrity of this corridor could be severely affected by the potential expansion of the Hidrovía Paraguay-Paraná for improving commercial trade, the foreseen installation of new dams in the Paraná basin, in addition to other current impacts and threats. Conservation of the corridor for societal benefits, involving the sustainable development of activities associated with the use of the fluvial territory, requires maintaining the natural ecological process that sustains livelihoods and biodiversity. This calls for innovative strategies encompassing water governance process, social and environmental information related to expected impacts, a better understanding of synergies between processes, and foremost an interdisciplinary approach to design and apply integrative and multi-scale management policies.Fil: Baigún, Claudio Rafael M.. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Minotti, Priscilla Gail. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; Argentin

Manejo de recursos pesqueros continentales: el uso de una caja de herramientas

Practical and conceptual tools are presented and discussed to optimize freshwater resources management, particularly in absence of suitable information. Such issues involve among others the ambiguous concept of sustainability, scale effect in asking right management questions, application of an holistic approach for developing those processes related to management following hierachical and articulated steps, understanding the value of information and its publications, using sinthetic indicators with diagnostic and predictive value value and developing robust sampling protocols upon stratified designs as usually is required for freshwater fisheries studies. Such tools represent a valuable alternative to ordinate the fisheries, to improve the information basis and to apply management guidelines based on using suitable assessment methods.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Impactos ecológicos y socioeconómicos de la construcción de represas sobre la ictiofauna y las pesquerías de los grandes ríos de América del Sur.

Capítulo de libroAmérica del Sur posee un enorme potencial para el desarrollo de proyectos hidroeléctricos. Estos proyectos han fragmentado más de 3000 km de ríos, y solo en la alta Cuenca del Paraná existen más de 130 represas, de más de 10 m de altura, esperándose un fuerte incremento de estos proyectos en la cuenca Amazónica para el siglo XXI. Las represas poseen la capacidad de ejercer efectos bidireccionales sobre la hidrología, geomorfología y recursos bióticos. Aguas abajo, promueven cambios en el régimen de caudales, en ocasiones alterando la calidad del agua; aguas arriba, la formación de grandes embalses modifica las condiciones ecológicas de los ríos, la calidad del agua y, en áreas tropicales, promueve la emisión de metano, contribuyendo así al calentamiento global. Por otra parte, los embalses favorecen los cambios en la composición de la comunidad de peces y altera la calidad de las pesquerías tras la etapa de estabilización trófica, al reducirse la presencia de especies migratorias. Estos impactos no han podido ser mitigados aún mediante la instalación de pasos para peces, tal como lo demuestran los resultados observados en Yacyretá, Salto Grande y diversas represas de Brasil. El desarrollo de represas en América del Sur en el siglo XXI deberá evaluarse en función de los costos y beneficios energéticos, ambientales, sociales y económicos para cada caso, siendo necesario poner en prácticas criterios bioingenieriles y una visión ecosistémica para reducir los impactos sobre los recursos de los grandes ríos y sus principales actores asociados.Fil: Baigún, Claudio Rafael Mariano. Instituto de Investigación e Ingeniería Ambiental, UNSAM/Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Argentina. Email: [email protected]

Manejo de recursos pesqueros continentales: el uso de una caja de herramientas

Practical and conceptual tools are presented and discussed to optimize freshwater resources management, particularly in absence of suitable information. Such issues involve among others the ambiguous concept of sustainability, scale effect in asking right management questions, application of an holistic approach for developing those processes related to management following hierachical and articulated steps, understanding the value of information and its publications, using sinthetic indicators with diagnostic and predictive value value and developing robust sampling protocols upon stratified designs as usually is required for freshwater fisheries studies. Such tools represent a valuable alternative to ordinate the fisheries, to improve the information basis and to apply management guidelines based on using suitable assessment methods.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Manejo de recursos pesqueros continentales: el uso de una caja de herramientas

Practical and conceptual tools are presented and discussed to optimize freshwater resources management, particularly in absence of suitable information. Such issues involve among others the ambiguous concept of sustainability, scale effect in asking right management questions, application of an holistic approach for developing those processes related to management following hierachical and articulated steps, understanding the value of information and its publications, using sinthetic indicators with diagnostic and predictive value value and developing robust sampling protocols upon stratified designs as usually is required for freshwater fisheries studies. Such tools represent a valuable alternative to ordinate the fisheries, to improve the information basis and to apply management guidelines based on using suitable assessment methods.Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) - Instituto de Limnología "Dr. Raul A. Ringuelet" (ILPLA

Cambios en los indices biológicos de la tararira, hoplias malabaricus (bloch, 1794) en un ciclo anual en la Laguna Yalca, provincia de Buenos Aires, Argentina

Fil: Balboni, Leandro. Instituto Tecnológico de Chascomús, IIB-INTECH. Chascomús; ArgentinaFil: Colautti, Darío César. Instituto de Limnología Dr. Raúl A. Ringuelet (ILPLA). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Baigún, Claudio Rafael Mariano. Instituto Tecnológico de Chascomús, IIB-INTECH. Chascomús; Argentin

Manejo de recursos pesqueros continentales: el uso de una caja de herramientas

Practical and conceptual tools are presented and discussed to optimize freshwater resources management, particularly in absence of suitable information. Such issues involve among others the ambiguous concept of sustainability, scale effect in asking right management questions, application of an holistic approach for developing those processes related to management following hierachical and articulated steps, understanding the value of information and its publications, using sinthetic indicators with diagnostic and predictive value value and developing robust sampling protocols upon stratified designs as usually is required for freshwater fisheries studies. Such tools represent a valuable alternative to ordinate the fisheries, to improve the information basis and to apply management guidelines based on using suitable assessment methods.Practical and conceptual tools are presented and discussed to optimize freshwater resources management, particularly in absence of suitable information. Such issues involve among others the ambiguous concept of sustainability, scale effect in asking right management questions, application of an holistic approach for developing those processes related to management following hierachical and articulated steps, understanding the value of information and its publications, using sinthetic indicators with diagnostic and predictive value value and developing robust sampling protocols upon stratified designs as usually is required for freshwater fisheries studies. Such tools represent a valuable alternative to ordinate the fisheries, to improve the information basis and to apply management guidelines based on using suitable assessment methods