Variation of the ichthyofauna along the Goioerê River: an important tributary of the Piquiri-Paraná basin

The construction of reservoirs is considered an important source of impacts on the fish fauna, severely altering the structure of the assemblage. This paper aimed to describe the structure of the fish assemblage of the Goioerê River, determining its longitudinal distribution and patterns of species dominance. The evaluation of its longitudinal variation in the diversity and abundance of the fish assemblage was conducted in July and October 2004 and January and May 2005. The collections were carried out near the headwaters (Gurucaia), middle stretch (Olaria), just above the falls (Paiquerê) and downstream (Foz). Forty-four species were captured. The Gurucaia fish assemblages differed significantly from Olaria, Paiquerê and Foz. The Olaria assemblages differed significantly from the Foz. Gurucaia showed the lowest diversity and abundance of species. Astyanax aff paranae Eigenmann,1914 (78% of the total) was found to be dominant at this site. Almost the same species richness was found at Olaria and Paiquerê, although Olaria had the greatest abundance of individuals. Astyanax aff paranae, Cyphocharax modestus (Fernández-Yépez, 1948) and Astyanax altiparanae Garutti & Britski, 2000 were the top three dominants and comprised over 71% of the total number of fish caught. At Paiquerê, Astyanax altiparanae, Hypostomus aff ancistroides (Ihering, 1911) and Loricariichthys platymetopon Isbrücker & Nijssen, 1979 composed 58% of the catches. Thirty-one species were recorded at Foz, which presented the greatest richness. The most abundant species were Apareiodon affinis (Steindachner, 1879), Galeocharax knerii (Steindachner, 1879) and A.altiparanae, which contributed to 50% of the total catches in this environment.These results record the fish biodiversity and how the community is longitudinally structured in the Goioerê River, and also demonstrate how this type of evaluation is important to understanding the fish community patterns and finding solutions to problems related to the conservation and management of the basin

An overview of freshwater fish aging in South America: the science, biases and future directions - doi: 10.4025/actascibiolsci.v32i4.8664

South America harbors the largest freshwater diversity in the world (about 4,475 valid species). Aging studies of 153 species published in 92 papers were reviewed for this publication. They were categorized according to the journal where they were published, decade, number of researches per river basin, methods and structures most used to estimate age, validation methods, period and causes of the formation of the age ring and age of the fish in South America. Our results showed an increase in the studies of age and growth, especially in the Paraná river basin. Scales were the structure most used in the studies of aging. Most of the researchers did not validate age. On a continental level, there was no specific period for growth ring formation, but in general, it was related to reproductive activity and flooding period. South American freshwater fishes did not present high longevity (maximum of 15 years). The ongoing governmental support to the fishery in South America, such as in Brazil with the creation of the Ministry of Fishing and Aquaculture, will certainly enlarge the fishing industry. Thus, it is necessary to know and to evaluate the fishery stocks correctly in order to guarantee sustainable use.South America harbors the largest freshwater diversity in the world (about 4,475 valid species). Aging studies of 153 species published in 92 papers were reviewed for this publication. They were categorized according to the journal where they were published, decade, number of researches per river basin, methods and structures most used to estimate age, validation methods, period and causes of the formation of the age ring and age of the fish in South America. Our results showed an increase in the studies of age and growth, especially in the Paraná river basin. Scales were the structure most used in the studies of aging. Most of the researchers did not validate age. On a continental level, there was no specific period for growth ring formation, but in general, it was related to reproductive activity and flooding period. South American freshwater fishes did not present high longevity (maximum of 15 years). The ongoing governmental support to the fishery in South America, such as in Brazil with the creation of the Ministry of Fishing and Aquaculture, will certainly enlarge the fishing industry. Thus, it is necessary to know and to evaluate the fishery stocks correctly in order to guarantee sustainable use

An overview of freshwater fish aging in South America: the science, biases and future directions = Uma visão sobre idade de peixes de água doce na América do Sul: a ciência, tendências e o futuro

South America harbors the largest freshwater diversity in the world (about 4,475 valid species). Aging studies of 153 species published in 92 papers were reviewed for this publication. They were categorized according to the journal where they were published, decade, number of researches per river basin, methods and structures most used to estimate age, validation methods, period and causes of the formation of the age ring and age of the fish in South America. Our results showed an increase in the studies of age and growth, especially in the Paraná river basin. Scales were the structure most used in the studies of aging. Most of the researchers did not validate age. On a continental level, there was no specific period for growth ring formation, but in general, it was related toreproductive activity and flooding period. South American freshwater fishes did not present high longevity (maximum of 15 years). The ongoing governmental support to the fishery in South America, such as in Brazil with the creation of the Ministry of Fishing and Aquaculture, will certainly enlarge the fishing industry. Thus, it is necessary to know and to evaluate the fishery stocks correctly in order to guarantee sustainable use.A América do Sul possui a maior diversidade de peixes de água doce domundo (cerca de 4.475 espécies válidas). Para esta publicação, foi revisada a idade de 153 espécies de 92 artigos. Eles foram categorizados de acordo com o periódico, década, número de pesquisaspor bacia hidrográfica, métodos e estruturas mais usadas para estimar a idade, métodos de validação, época e causas da formação do anel etário e idade dos peixes da América do Sul. Os resultados mostraram aumento de estudos de idade e crescimento, especialmente na bacia do rio Paraná. As escamas foram as estruturas mais usadas nos estudos considerados. A maioria dos pesquisadores não fez a validação da idade. Em nível continental não foi verificado um período específico para a formação dos anéis de crescimento, mas em geral, as marcas estiveram relacionadas com a atividade reprodutiva e ao período de cheias. Os peixes de água doce da América do Sul não têm elevada longevidade (máximo 15 anos). Na América do Sul, é esperado que a indústria pesqueira expandirá, pela criação de programas de incentivo, como a criação o Ministério da Pesca e Aquicultura no Brasil, e assim, será necessário conhecer e avaliar os estoques corretamente com o propósito de uso sustentável

Ovarian histology and fecundity in the evaluation of the reproduction of the invasive species Serrasalmus marginatus (Characidae) on a neotropical floodplain

 The construction of the Itaipu Hydroelectric Power Plant in 1982 led to the formation of a reservoir, which, in turn, leveled the waters of the Paraná River by flooding the geographic barrier Salto de Sete Quedas. This allowed the piranha Serrasalmus marginatus to invade and colonize the upper Paraná River. This study aimed to: i) confirm, through light microscopy, the reproductive phases of S. marginatus females; ii) estimate fecundity and iii) evaluate the reproduction areas of the population. A total of 764 females were collected from nine sampling sites on the upper Paraná River floodplain. Microscopic analysis of the ovaries showed the following phases: early developing subphase, developing phase, spawning capable phase, actively spawning subphase, regressing phase and regenerating phase. The frequency distribution of the oocytes shows that spawning is fractional and fecundity indeterminate. Fecundity varied from 410 to 752 oocytes (mean = 584). The continual spawning of oocytes during the long reproductive period, as well as the aggressiveness of the species as regards the defense of its offspring, guarantees more descendants in the Patos, Ventura, Fechada, Guaraná and Garças lagoons and Ivinheima and Baia rivers of the upper Paraná River floodplain.

Age, growth, mortality and yield per recruit of the dourado Salminus brasiliensis, Corumbá Reservoir, Goiás State, Brazil

In order to evaluate the fate of the migratory species dourado Salminus brasiliensis in the first years of impoundment in Corumbá Reservoir we estimated age, growth, mortality and yield per recruit. Samplings were carried out monthly in Corumbá Reservoir and its main tributaries (Goiás State) from March 1998 to February 1999 using gillnets. After one year of impoundment, age was estimated from scales and the maximum number of rings was six for males and five for females. Rings are formed annually in May and June. The asymptotic length and growth rate for males and females were 37.1 cm and 0.77 and 56.6 cm and 0.52, respectively. A dominance of juveniles was verified in the reservoir and its tributaries. The instantaneous total mortality rate (Z) was 1.59 and the annual total mortality rate (A) was 79.6%. The highest yield per recruit (1200g) and the highest average weight (1900g) were obtained in simulations with low values of fishing (F) and natural (M) mortalities. Based on the above information we describe the Corumbá Reservoir impoundment has influenced the growth of the dourado. As regards this study, we recommend that the fishing effort not be applied during the trophic upsurge period and that the monitoring of the dourado assemblage continue. Fishery programs management for this species should be carried out with subsequent monitoring involving efficient communication, realistic practices and involvement of fisher organizations

Reproduction of invasive Loricariichthys platymetopon Isbrücker & Nijssen, 1979 (Actinopterygii, Loricariidae) on the upper Paraná River floodplain

Loricariichthys platymetopon originally occurred in the Uruguay, Paraguay and lower Paraná rivers. With the formation of Itaipu Reservoir in 1982, it invaded and colonized the upper Paraná River. Using the data obtained quarterly at nine sampling sites on the upper Paraná River floodplain, the reproductive phases and the germ cells of L. platymetopon females were characterized. Variation in oocyte diameter, batch fecundity, and relative batch fecundity by standard length and total weight was also verified, as well as the reproduction sites on the upper Paraná River floodplain. The following stages were recorded: single oogonia, oogonial and oocytes cysts, initial, intermediate and final primary growth oocytes, full-grown oocytes and maturation oocytes. The reproductive phases were validated by the germ cell attributes and females were recorded in the following phases: developing, spawning-capable, regression and regeneration. Oocyte diameters varied from 100 to 4100 µm. Batch fecundity varied from 372 to 1392 oocytes.g-1 and the relative batch fecundity estimate by length was 16 to 49 oocytes.cm-1 and by weight was 3.6 to 6.4 oocytes.g-1. The reproductive patterns of L. platymetopon on the upper Paraná River floodplain showed the sites where reproductive activity is more intense (Guaraná, Garças and Fechada lagoons and the Baía River) and sites where it is less intense (Ivinheima and Paraná rivers). Thus, the biotic resistance of the Ivinheima River, due to the integrity of these environments in this area, which is part of the Environmental Protection Area of the Islands and Marshes of the Paraná River, has prevented the reproductive success of this invader.Loricariichthys platymetopon ocorria originalmente nos rios Uruguai, Paraguai e baixo Paraná. Com a formação do reservatório de Itaipu em 1982, invadiu e colonizou o alto rio Paraná. Usando os dados obtidos trimestralmente em nove pontos de amostragem na planície de inundação do alto rio Paraná, foram caracterizadas as fases reprodutivas e células germinativas das fêmeas de L. platymetopon. Além disso, foram verificados: a variação no diâmetro dos oócitos, a fecundidade dos lotes, a fecundidade relativa dos lotes por comprimento padrão e peso total e os locais de reprodução na planície de inundação do alto rio Paraná. Foram registrados os estágios: oogônia única, cistos de oogônias e oócitos, oócitos de crescimento primário inicial, intermediário e final, oócitos de crescimento completo e oócitos maduros. As fases reprodutivas foram validadas pelos atributos das células germinativas e as fêmeas foram registradas nas seguintes fases: desenvolvimento, apto à desova, regressão e regeneração. O diâmetro dos oócitos variou de 100 a 4.100 µm. A fecundidade do lote variou de 372 a 1.392 oócitos.g-1 e a estimativa da fecundidade relativa do lote por comprimento padrão foi de 16 a 49 oócitos.cm-1 e, em peso foi de 3,6 a 6,4 oócitos.g-1. Os padrões reprodutivos de L. platymetopon na planície de inundação do alto rio Paraná mostraram os locais onde a atividade reprodutiva é mais intensa (lagoas do Guaraná, das Garças e Fechada e rio Baía) e locais onde é menos intensa (rios Ivinheima e Paraná). Assim, a resistência biótica do rio Ivinheima, devido à integridade desses ambientes nessa área, que faz parte da Área de Proteção Ambiental das Ilhas e Várzeas do Rio Paraná, tem impedido o sucesso reprodutivo desta invasora