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Producción Científica, 1.Most freshwater fish need to move freely through rivers to complete their lifecycles. Thus, river barriers (e.g. dams, culverts and gauging stations) may delay,hinder or even block their longitudinal movements, affecting fish conservation.The most widespread solution to allow upstream fish migration are fishways,whereas downstream migration is basically facilitated through spillways, turbinesor specific solutions such as bypass systems.2. So far, studies and scientific discussions concerning bidirectional movementsthrough fishways are scarce and focused on large dams and reservoirs, mainlywith large migratory species such as salmonids, rather than smaller facilities andlesser known species.3. This study investigated bidirectional movements through a small run-of-the-riverhydropower plant with a pool-and-orifice type fishway, using the Iberian barbel(Luciobarbus bocagei), a potamodromous cyprinid, as the target species. Passiveintegrated transponder and radio tracking data were collected over 4 years andcombined to characterize upstream and downstream movements. The studyfocused primarily on fish movements through the fishway, but also estimated themultiple associated routes of passage.4. The results show diverse fish movements with inter- and intra-annual variability,with several individuals performing bidirectional movements and even some fishreturning over the years.5. The documented movements and observations indicate that fishways can serveas an effective bidirectional migration corridor for fish, potentially enhancing theconservation efforts for potamodromous species. This study supports thedecision to use fishways as an overall mitigation tool to reduce the impact ofsmall hydropower facilities on fish., European Union’s Horizon 2020 research and innovation program. grant agreement no.727830, European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement no.101032024

The fish fauna from the Lower Iguaçu River and tributaries upstream of the Iguaçu Falls, the last free-flowing river stretch, were investigated. Twenty five sites in tributaries and the main channel were sampled between 2010 and 2016 using several kinds of fishing gear. The species were categorized according to their size, origin, and conservation status. Species richness and abundance in the main channel and tributaries were compared. In total, 87,702 specimens were recorded, comprising 76 species, 25 families, 53 genera, and eight orders. Characiformes and Siluriformes were the richest orders, representing 92% of the total specimens; Characidae, Cichlidae, Pimelodidae, and Loricariidae were the richest families. The fish fauna was composed of small and medium-sized species and included endemic (42%), autochthonous (24%), allochthonous (21%), and exotic (9%) species, as well as hybrids (4%). Significant differences in the relative numerical abundance of species were found among sites. Ancistrus mullerae and Rhamdia branneri (endemic) were indicator species for tributaries inside of Iguaçu National Park (INP), while Phalloceros harpagos (autochthonous) and Ictalurus punctatus (exotic) for tributaries outside of INP and Odontesthes bonariensis (allochthonous) for the main channel. The last dam-free stretch of the Lower Iguaçu River and tributaries upstream the Iguaçu Falls exhibits a rich endemic fish fauna, including some rare, endangered species (Steindachneridion melanodermatum, Gymnogeophagus taroba, and Psalidodon gymnogenys). These findings are essential to predict and understand the effects caused by the new Baixo Iguaçu Hydroelectric Power Plant and highlight the importance of tributaries and Iguaçu National Park for conservation of endemic species.

The seasonal pattern and the composition of downstream drift of fish eggs and larvae through the fish ladder of the Porto Primavera dam, located in the Upper Parana River, Brazil, were studied. Add...

Conservation of fish assemblages in severely impounded rivers has often focused on providing longitudinal and lateral connectivity along the main stem. Less attention has been given to tributaries, some of which remain unimpounded. This study shows that the biodiversity of ichthyoplankton in tributaries to the largest reservoir in the Parana River, Brazil, is similar to that of tributaries of the few remaining unimpounded stretches of the Parana River. Annual and seasonal variability in discharge within and among tributaries attracts and supports a diverse mix of species in each spawning season. Tributaries enrich the fish biodiversity of the entire system by providing a variety of environmental conditions, access to spawning habitat, refugia for early life stages, and by promoting ecological heterogeneity. Thus, tributaries can mitigate the adverse influence of an impounded main stem. Tributaries also support populations of endangered and threatened species. A focus on tributaries offers conservation alternatives that are more feasible given the scale and large number of impoundments constructed on the main stem. Conservation in the main stem may focus on maintaining passage through dams and access to large floodplains. Conversely, in tributaries conservation may focus on managing the quality of inflows from catchments, preserving suitable instream habitats and flows, and preserving access to smaller but more numerous floodplains.

The land use and occupation in watersheds directly influences the water resources, and the vegetation cover is a crucial factor for water maintenance. The objective of this study was to characterize the land use and occupation in nine watersheds of the Lower Iguaçu River (Andrada, Monteiro, Gonçalves Dias, Floriano, Silva Jardim, Cotejipe, Sarandi, Capanema and Santo Antônio sub-basin rivers), using the classification from satellite images. The classification area obtained high accuracy (Kappa coefficient of 99.4 to 99.9%). The Floriano River sub-basin presented the highest degree of environmental preservation, followed by Silva Jardim and Gonçalves Dias River sub-basins, fully or partially inserted in Iguaçu National Park. Monteiro and Sarandi river sub-basins showed the smallest areas of vegetation, and Capanema, Cotejipe, Andrada and Santo Antônio River sub-basins exhibited an intermediate condition. This tendency was verified by the cluster analysis. These results can serve as a baseline for planning, monitoring and management of this area, environmental modeling, conservation of water resources, biodiversity, and environmental services. El uso y la ocupación de la tierra en las cuencas hidrográficas influyen directamente en los recursos hídricos y la cubierta vegetal es un factor determinante para el mantenimiento del agua. El objetivo de este estudio fue caracterizar el uso y la ocupación del suelo en nueve cuencas del bajo Iguaçú (ríos Andrada, Monteiro, Gonçalves Dias, Floriano, Silva Jardim, Cotejipe, Sarandi, Capanema y Santo Antônio), utilizando la clasificación de uso y ocupación de la tierra a partir de imágenes de satélite. La clasificación de áreas obtuvo una buena precisión (coeficiente Kappa de 99,4 a 99,9%) y la cuenca del Floriano fue la que presentó el mayor grado de preservación ambiental, seguida por las cuencas de los ríos Silva Jardim y Gonçalves Dias, insertas total o parcialmente en el Parque Nacional de Iguaçú. Las cuencas de los ríos Monteiro y Sarandi poseen las menores áreas de vegetación y los ríos Capanema, Cotejipe, Andrada y Santo Antônio se encuentran en una condición intermedia. La misma tendencia se verificó mediante el análisis de conglomerados. Los resultados pueden servir de base para la planificación, el seguimiento y la gestión de la zona, la elaboración de modelos ambientales, la conservación de los recursos hídricos, la biodiversidad y los servicios ambientales. O uso e ocupação da terra em bacias hidrográficas influencia diretamente os recursos hídricos, sendo a cobertura vegetal um fator determinante para a conservação dos rios. O objetivo deste estudo foi caracterizar o uso e ocupação do solo em nove bacias do baixo rio Iguaçu (rios Andrada, Monteiro, Gonçalves Dias, Floriano, Silva Jardim, Cotejipe, Sarandi, Capanema e Santo Antônio), utilizando a classificação do uso e ocupação da terra a partir de imagens de satélite. A classificação da área obteve boa acurácia (coeficiente Kappa de 99,4 a 99,9%) e a bacia do Floriano foi a que apresentou o maior grau de preservação ambiental, seguida pelas bacias dos rios Silva Jardim e Gonçalves Dias, integral ou parcialmente inseridas no Parque Nacional do Iguaçu. As bacias dos rios Monteiro e Sarandi possuem as menores áreas da classe vegetação e os rios Capanema, Cotejipe, Andrada e Santo Antônio, encontram-se em uma condição intermediária. A mesma tendência foi verificada pela análise de agrupamento. Os resultados podem servir de linha de base para o planejamento, monitoramento e manejo da área, modelagem ambiental, conservação dos recursos hídricos, da biodiversidade e dos serviços ambientais.

Steindachneridion melanodermatum, an endemic and endangered species, is the largest catfish in the Lower Iguaçu River basin. Currently, the wild population of this species no longer exists in most of this basin, probably due to the loss of habitat by successive hydroelectric dams. This study evaluated the spatial distribution and abundance of S. melanodermatum in the last free-flowing river stretch of approximately 190 km downstream from the Salto Caxias Dam, upstream of the Iguaçu Falls, as well as some tributaries. Hydroacoustic and fishing campaigns were performed between September 2010 to December 2016 to characterize the preferred habitat. A total of 180 specimens was sampled with higher abundances in a protected area near Iguaçu Falls in the Iguaçu National Park. Twenty-four deep pools were identified with maximum depths ranging from 5 to 25 m: 21 pools were along the main channel of the Iguaçu River, and three pools were in tributaries. Deep pools are preferential habitats for this species, especially the deep pool called Poço Preto (P23) and its surroundings. Conservation strategies are required to protect these habitats and prevent S. melanodermatum from becoming extinct, such as establishing deep pools as ecological sanctuaries, intensifying the inspection of illegal fishing, and maintaining dam-free tributaries.

The population structure and reproductive biology of the surubim of Iguacu, Steindachneridion melanodermatum, a large endemic and endangered catfish from Iguacu River basin, were evaluated. In total, 182 specimens of this species were sampled from September 2010 to December 2016 in the Lower Iguacu River, including some tributaries. The determination of the cycle and reproductive period was undertaken by assessing the mean variation in the values of the gonadosomatic index (GSI) of females and males, as well as by the frequency distribution of the stages of gonadal development on the basis of macroscopic and microscopic analyses. The total length and bodyweight ranged from 21 to 102cm and from 82.8 to 15670g respectively. The reproductive period of this species was from June to September (winter and early spring), and may extend until November, with GSI peaking in August for males and September for females. The size at first maturation (L50) corresponded to 39.5cm for females and 43.9cm for males. Spawning in this species was associated with lower water temperatures, and high discharge and dissolved oxygen concentration. Our findings are crucial in assisting the development of effective measures and specific criteria for the conservation of this endangered species.

Made available in DSpace on 2020-12-12T02:17:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-09-01 Companhia Energética de São Paulo In a recent article, we described fitting electronic tags to the fish Prochilodus lineatus to document how a fishway connected aquatic habitats downstream and upstream of a major dam. Moreover, given that tagged fish remained upstream or downstream for periods extending months and years before returning to the fishway, and that observed patterns of passage were consistent with seasonal migratory cycles, and building on existing literature, we speculated that the fishway allows fish access to spawning habitats upstream and feeding habitats downstream. Our interpretation of the movement data resulted in several comments from Pelicice, Pompeu, and Agostinho (2020) and they outline various reasons by which, in their opinion, some of our conclusions may be mistaken. Their critique is threefold. First, they argue that the percentage of fish attracted into the fishway is too low to consider the fishway an effective link between the reservoir and the river downstream. We contend that without estimates of population size it is impossible to judge if 28% passage is “limited”; conceivably, the absolute number of fish passed may still be enough to maintain a viable population. Second, they assert that because receivers were located only in the fishway it is unknown if fish that used the fishway remained near the dam, or if they continued their migration. We counter with a brief literature review that documents P. lineatus migrating through reservoirs and spawning in tributaries. Third, they advocate for a broader conservation perspective and for additional research. We agree and, in the article, had already expressed this view that fishways are only a temporary fix and that we support their use only as an element of a broader environmental management package. We also agree with the need for more research but argue that procrastinating on conservation action may not be wise because we do not know if the research will be done, how long it will take, or what the cost may be of waiting. Sustainability Management Companhia Energética de São Paulo – CESP, SP-613 highway, km 78 Grupo de Pesquisa em Tecnologia em Ecohidráulica e Conservação de Recursos Pesqueiros e Hídricos – GETECH. Programa de Pós-graduação em Recursos Pesqueiros e Engenharia de Pesca Universidade Estadual do Oeste do Paraná – Unioeste Department of Hydraulics and Hydrology University of Valladolid U.S. Geological Survey Mississippi Cooperative Fish and Wildlife Research Unit Engineering College of Ilha Solteira Department of Biology and Zootechny Fish Ecology Laboratory Universidade Estadual Paulista – UNESP Engineering College of Ilha Solteira Department of Biology and Zootechny Fish Ecology Laboratory Universidade Estadual Paulista – UNESP

Brown trout uses river flow and thermal regimens as main stimuli for initiating and maintaining behavioral reactions such as migration and spawning. Therefore, anthropogenic alterations on these factors may have strong impacts on its populations. The aim of this work is to understand these consequences by assessing potamodromous brown trout movements in the past and present, and to model future responses. For this, brown trout movements in a fishway in the Marin River (Bidasoa basin, Northern Iberian Peninsula) have been monitored from 2008 to 2017. Random forest regression has been used to assess the influence of environmental variables on brown trout movements and to model the response under hypothetical climatic and hydrological scenarios. Results show that brown trout uses the fishway during the whole year, with more upstream movements during the spawning season. The model is able to predict accurately the timing and number of migrants. Its use under hypothetical climate change and flow regulation scenarios shows a delay in the migration time. Therefore, modelling using large time series can be a powerful tool to define management and conservation strategies and prepare compensation measures for future scenarios.

Many fish passes have been built across the world in recent years. This study analyses the performance of a modified type of pool and weir fishway with two access branches, using passive integrated transponder telemetry. A circum‐Mediterranean barbel, Luciobarbus bocagei (Steindachner, 1864), was chosen as the target species. Both hydraulic values (flow and volumetric energy dissipation) and biological parameters (attraction, entrance and passage success) were measured in the fishway, these being related to the environmental variables affecting upstream fish movement. Flow discharge, water temperature and atmospheric pressure were important for fish entering the fishway. There was no preference between path routes, even though the main discharge was concentrated in the turbine channel. This type of fishway design could be an alternative for the conservation of fish populations where multiple fish approach options are possible.

South American rivers have become intensely affected by the construction of hydroelectric dams that block the river&rsquo, s connectivity for migratory fish species. In order to mitigate the problems caused by dams and to reestablish connections between habitats, fishways are implemented. Fishways are structures that aid fish in overcoming obstacles and help preserve migratory, reproductive, and feeding routes. This study performed an inventory of all hydropower plants&mdash, present and future&mdash, in the Upper Paran&aacute, River, with the objective of identifying fishways unknown to scientific literature, as well as the task of mapping them. By doing so, the current situation of structural connectivity via fishways in the Upper Paran&aacute, River Basin was described. Overall, 389 dams along 209 rivers were identified, of these, only 9% (35 dams) have fishways. In addition, an alarming explosion of future medium-sized hydropower plants was observed, with an expectation of an almost 500% increase in relation to those existing. This data reveals a trend of reduction of free-flowing river stretches, which are crucial habitats for Neotropical potamodromous species, and point to a deficiency in the structural connectivity of existing hydropower dams. Furthermore, if the implementations of these expected constructions are associated with limited connectivity as a result of the absence of fishways, the management of fisheries and their resources in the Upper Paran&aacute, River may become unsustainable.

Over the past few decades, South American Rivers, including the Parana River system, have been intensely impacted by dam constructions. To mitigate adverse impacts, fish passages were incorporated into two large dams on the Parana River (Itaipu and Porto Primavera) to reestablish longitudinal connectivity, which is very important for conserving populations of migratory fish species. The aim of this study was to estimate genetic diversity, population differentiation and gene flow, using microsatellites markers and mitochondrial haplotypes (d-loop), in populations of Prochilodus lineatus, a long distance migratory species commonly found in Parana River basin drainages. Samples were obtained from six locations in the Upper and Middle Parana River: Porto Primavera Reservoir, downstream of the Porto Primavera Reservoir, four tributaries of this reservoir (Pardo, Peixe, Verde and Aguapei Rivers) and in the Iguacu River, downstream of the Itaipu dam. High genetic diversity was observed in all samples, as expected for species with large population sizes and high migration rates. However, the influence of other factors, such as secondary contacts, fish passages and restocking were also suggested. In general, evidence of spatial population structuring was not found, even though there were two large dams in the study area. This could also be attributed to the brief period that has elapsed since the dams were built, the influence of migratory and reproductive patterns and the possible contributory effects of the fish passages. Furthermore, the absence of population structuring also corroborates existing information that emphasizes the importance of unimpeded tributaries for conserving migratory fish populations in fragmented watersheds.

Migratory fish species are the highly susceptible to environmental impacts as river fragmentation by dams and loss of habitats. For the implementation of reproduction habitat rehabilitation projects, information about the biotic characteristics of the spawning grounds are necessary. In this work, information of the geomorphological, hydrological and water quality characteristics of the spawning areas of migratory fishes distributed in several orders were reviewed and compared with Brazilian species. With the information found, we conclude that these studies on the spawning grounds of migratory fishes from the north hemisphere, are quite advanced, projecting a clear image of what environment in necessary for the reproduction. However in Brazil, they are still scarce, what precludes the delineation of management projects for the conservation of those species.

The feeding selectivity of laboratory-reared larvae of Rhamdia voulezi was assessed to investigate the preferred preys in early life stages. Three experiments were conducted at different larval development stages, starting soon after the absorption of the yolk sac (on fourth day after hatching – DAH), using zooplankton from fish ponds as food. Differences were detected in the patterns of prey selection among development stages. At first, the larvae prefer small preys, such as rotifers and cladocerans. Later, when they are more developed, they prefer to feed on large preys, such as copepods. On the fourth DAH, larvae in the pre-flexion and initial flexion stage strongly selected rotifers and cladocerans (Diaphanosoma spinulosum, D. brevireme, Moina sp., M. micrura and M. minuta). At the other stages, cladocerans continued to be strongly selected. However, on the eighth DAH, larvae in flexion stage selected less strongly copepods Argyrodiaptomus azevedoi, Metacyclops mendocinus and Termocyclops decipiens. On the tenth DAH, larvae in postflexion stage selected more strongly copepods Argyrodiaptomus furcatus, Notodiaptomus cf. spinuliferus and M. mendocinus. As larvae grow, they tend to specialize in feeding of a particular prey. Prey selection of R. voulezi larvae was based both on species and zooplankton size. The size of the zooplankton ingested was related to the mouth gape size of larvae.

Made available in DSpace on 2019-10-06T16:25:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 The diet of Glanidium ribeiroi was investigated in lotic stretches downstream from a cascade of reservoirs to determine how it responds to intraspecific and environmental variations. Monthly sampling was performed from 2013 to 2016 at sites including the main channel of the Iguaçu River and tributaries in preserved basins and agricultural land. The diet of individuals in the preserved tributaries was primarily associated with allochthonous resources, whereas in the non-preserved tributaries and main channel the diets were primarily associated with autochthonous resources. Trophic niche breadth and intraspecific variability differed significantly among sampling areas and size classes. Trophic niche overlap among size classes and sampling areas was low. Positive and negative relationships between the trophic niche breadth and the standard length of individuals were also found in different sampling areas. Intraspecific and ontogenic variations were strongly and consistently associated with forest cover. Individuals responded differently to local environmental variations due to differences in landscape gradients and life cycle changes. Therefore, the effects of spatial heterogeneity on diet composition and intraspecific variations therein appear to be crucial to the success of the populations evaluated. These results may help with the implementation of conservation measures for this and other endemic species. Universidade Estadual Paulista (UNESP) Instituto de Biociências Botucatu Programa de Pós Graduação em Ciências Biológicas-Zoologia, Rua Prof. Dr Antônio Celso Wagner Zanin, 250 Universidade Estadual Do Oeste Do Paraná Programa de Pos Graduacao em Conservacao e Manejo de Recursos Naturais, Rua Universitária, 2069 Universidade Estadual Do Oeste Do Paraná Programa de Pós-graduação em Engenharia de Pesca, Rua Miraldo Pedro Zibetti, 385 Universidade Estadual Do Oeste Do Paraná Grupo de Pesquisa em Tecnologia em Ecohidraulica e Conservacao de Recursos Pesqueiros e Hidricos, Rua Miraldo Pedro Zibetti, 385 Universidade Estadual Paulista (UNESP) Instituto de Biociências Botucatu Programa de Pós Graduação em Ciências Biológicas-Zoologia, Rua Prof. Dr Antônio Celso Wagner Zanin, 250

This study evaluated the environmental conditions of two watersheds selected on the basis of similarities in land use. The environmental conditions of the watersheds were analyzed using two geoprocessing methods and in situ evaluations by applying the rapid assessment protocol (RAP). Geospatial image processing was used to analyze land use, slope, soil classification, and rainfall, while RAP was used to evaluate the connectivity and size of riparian corridors. The results revealed varied uses of land with the landscape matrix in both watersheds, composed of agriculture, pasture, and urban centers. Urban centers were defined as spots and riparian zones as corridors. The analysis of environmental fragility considering all the geospatial variables, classified both watersheds as having medium fragility. The most fragile sites were the urban centers, which had a high slope and degraded riparian zone. Onsite assessments have shown that corridors do not have the size required by legislation, they are fragmented and unstructured, and they contain exotic species. We also propose that a multi-factorial approach be used to evaluate watersheds, associating geospatial assessments and onsite analyses that consider the limitations pointed out in each protocol. This reduces sampling errors and shows the actual state of conservation in riparian zones.

This paper presents sprinting data from Iberian barbel (Luciobarbus bocagei) and northern straight-mouth nase (Pseudochondrostoma duriense), volitionally swimming against high velocity flows (1.5, 2.5 and 3 m s−1) in an open channel flume. Swimming endurance and speed greatly exceeded previously published observations with both species attaining swim speeds >20 body lengths s−1. Flow velocity was the primary variable limiting the distance both species were able to traverse. Barbel swam greater distances than nase at higher flow velocities, with longer individuals attaining greater distances than smaller ones. The results challenge established fish passage guidelines, suggesting that in some cases these species are capable of passing much higher velocities than was previously believed.

Made available in DSpace on 2019-10-06T16:02:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 This study investigated whether fish ladder transposition is a stressful event for the streaked prochilod, Prochilodus lineatus, in a dam on the Upper Paraná River, Brazil. Bodyweight, standard length and plasma concentrations of cortisol, glucose, lactate, chloride and haematocrit were measured in 48 adult fish (male and female) that were sampled downstream and upstream of the dam and on the fish ladder. The results showed that the intense physical exertion of the fish during ladder transposition demanded high metabolic requirements and activated anaerobic pathways, but was not stressful. We recommend that physiological indicators should be used for post-construing assessments, which would improve the management of migratory fish species. Universidade Estadual Do Oeste Do Paraná Programa de Pos-Graduacao em Conservacao e Manejo de Recursos Naturais, Rua Universitária 2069 Universidade Estadual Paulista UNESP Centro de Aquicultura (CAUNESP), Via de Acesso Paulo Donato Castelane Universidade Estadual Do Oeste Do Paraná Grupo de Pesquisa em Tecn. em Ecohidraulica e Conservacao de Recursos Pesqueiros e Hidricos-GETECH, Rua da Faculdade 645 Federal University of Bahia UFBA Department of Biorregulation, Avenida Reitor Miguel Calmon Universidade Estadual Paulista UNESP Centro de Aquicultura (CAUNESP), Via de Acesso Paulo Donato Castelane

When engineers and ecologists face a fishway design, many issues need to be considered, the type of fishway being the first and foremost. It is an especially complex issue in areas with species whose migratory and swimming behavior are as yet poorly known as Mediterranean barbels. The present study focuses on the fish passage of two of the most common types of technical fishways: Vertical Slot (VS), and Submerged Notch with Bottom Orifice (SNBO). Both types were studied and compared in terms of ascent ability (as the success rate and transit time) and motivation (as the proportion of attempts and attempt rate), with Iberian barbel (Luciobarbus bocagei) as the target species. Ascent ability in VS and SNBO were similar. More than 90% of fish ascended the fishways successfully and the median transit time to ascend a total water height of 2.25 m was less than 23 min. Fish length had an effect on ascent time, with the biggest ones being faster. Motivation was greater for VS, although not seeming to have a relevant influence in the passage. These results support the use of VS and SNBO in areas with Iberian barbel and provide new data of fishways performance helping ecologists and engineers with their decision making, mainly in Mediterranean areas with similar habitats and species.

Regulation of rivers by dams transforms previously lotic reaches above the dam into lentic ones and limits or prevents longitudinal connectivity, which impairs access to suitable habitats for the reproduction of many migratory fish species. Frequently, unregulated tributaries can provide important habitat heterogeneity to a regulated river and may mitigate the influence of impoundments on the mainstem river. We evaluated the importance of tributaries to spawning of migratory fish species over three spawning seasons, by comparing several abiotic conditions and larval fish distributions in four rivers that are tributaries to an impounded reach of the Upper Parana River, Brazil. Our study confirmed reproduction of at least 8 long-distance migrators, likely nine, out of a total of 19 occurring in the Upper Parana River. Total larval densities and percentage species composition differed among tributaries, but the differences were not consistent among spawning seasons and unexpectedly were not strongly related to annual differences in temperature and hydrology. We hypothesize that under present conditions, densities of larvae of migratory species may be better related to efficiency of fish passage facilities than to temperature and hydrology. Our study indicates that adult fish are finding suitable habitat for spawning in tributaries, fish eggs are developing into larvae, and larvae are finding suitable rearing space in lagoons adjacent to the tributaries. Our findings also suggest the need for establishment of protected areas in unregulated and lightly regulated tributaries to preserve essential spawning and nursery habitats. Copyright © 2014 John Wiley & Sons, Ltd.

O objetivo deste trabalho foi caracterizar a dieta e a morfologia do trato digestório do linguado, Catathyridium jenynsii (Günther, 1862) (Achiridae), em seus estágios iniciais de vida. Para análise do trato digestório, foi utilizado um exemplar de cada estágio larval, de pré-flexão até pós-flexão, e juvenil. Um total de 256 larvas e 16 juvenis, pertencentes a cinco classes de comprimento padrão, foi analisado quanto à dieta. Os dados foram coletados no reservatório de Itaipu, rio Paraná, Brasil, de setembro/2001 a março/2002 e setembro/2002 a fevereiro/2003. Para análise dos dados, foram aplicados os métodos de ocorrência e numérico para a determinação da frequência de ocorrência e numérica de cada item alimentar nas diferentes classes de comprimento padrão. A região anterior do trato digestório de C. jenynsii, começou a diferenciar-se em estômago partir de 4,70 mm CP (não apresentou cecos pilóricos). Desde o estágio de pré-flexão, verificou-se três dobras intestinais e várias estrias no trato digestório. A análise da dieta revelou que as larvas menores (classe 1) apresentaram uma dieta distinta, com dominância de cladóceros (especialmente Bosmina hagmanni e Bosminopsis deitersi). Para a classe 2, o copépodo Notodiaptomus sp. foi importante tanto em número quanto em ocorrência, entretanto B. hagmanni, ainda teve participação significativa na dieta. Já as larvas maiores (classes 3, 4) e juvenis (classe 5) apresentaram uma dieta similar, consumindo principalmente os copépodos (Notodiaptomus sp.). Portanto, neste estudo as larvas de C. jenynsii podem ser consideradas zooplanctívoras, já que em todos os estágios de desenvolvimento, cladóceros e copédodos dominaram a dieta. As alterações na dieta acompanharam as modificações morfológicas dos estágios iniciais de C. jenynsii. The objective of this study was to characterize the diet and digestive tract morphology of flounder, catathyridium jenynsii (günther, 1862) (achiridae), in its early stages of life. for analysis of the digestive tract, we used a specimen of each larval stage, pre-flexion to post-flexion, and juvenile. a total of 256 larvae and 16 juveniles, belonging to five classes of standard length was analyzed for diet. data were collected in the itaipu reservoir, paraná river, brazil, from september, 2001 to march, 2002, and from september, 2002 to february, 2003. the occurrence and numerical methods were applied for determining the occurrence frequency and numerical frequency of each food item in different standard length (sl) classes. the anterior digestive tract of c. jenynsii began to differentiate into the stomach at 4.70 mm sl (not presented pyloric caeca). since the stage of pre-flexion, there are three intestinal folds and a lot of grooves in the digestive tract. the dietary analysis showed that the smaller larvae (class 1) had a distinct diet, with dominance of cladocerans (mainly bosmina hagmanni and bosminopsis deitersi). for class 2, the copepod notodiaptomus sp. was important both in number and occurrence, however b. hagmanni also had significant importance in the diet. already the largest larvae (classes 3 and 4) and juveniles (class 5) showed a similar diet, consuming mainly copepods (notodiaptomus sp.). therefore, in this study, larvae of c. jenynsii can be considered zooplanktivore, since in all stages of development, copedods and cladocerans dominated the diet. changes in diet followed the morphological changes of the early stages of c. jenynsii.

The Piracema Canal is a complex 10-km fish pass system that climbs 120 m to connect the Parana River to the Itaipu Reservoir along the Brazil–Paraguay border. The canal was constructed to allow migratory fishes to reach suitable habitats for reproduction and feeding in tributaries upstream from the reservoir. The Piracema Canal attracted 17 of the 19 long-distance migratory species that have been recorded in the Parana River Basin and Paraguay–Parana Basin. However, the incidence of migratory fish decreased from downstream to upstream, with the pattern of decrease depending on species. Overall, 0.5% of the migratory fish that entered the Piracema Canal and segment 1, eventually were able to reach segment 5 and potentially Itaipu Reservoir. Ascension rate was examined relative to various physical attributes of canal segments; maximum water velocity emerged as the most influential variable affecting fish passage. Water velocity may be manipulated by controlling water discharge, and by re-engineering critical sections of the canal. Because the Itaipu Reservoir flooded a set of falls that separated two distinct biogeographical regions, facilitating fish movements through the Piracema Canal into the Itaipu Reservoir presents a management dilemma that requires deliberation in the context of the fish assemblages rather than on selected migratory species. Copyright © 2010 John Wiley & Sons, Ltd.

This study described the initial development of Pseudoplatystoma reticulatum, as well as changes in growth patterns. Morphometric and meristic variables were analyzed during embryonic, larval and juvenile periods, even as allometric growth coefficients for larvae and juveniles. Eggs showed an average diameter of 1.79 mm and broad perivitelline space (23.41%). The total length (TL) of the larvae ranged from 3.05 to 25.72 mm, and the total number of myomeres ranged from 45 to 50 (preanal = 13-16 and postanal = 30-35). Initial pigmentation is poor, concentrated at the extremities of the yolk sac. In the flexion stage, the pigmentation intensifies and forms a longitudinal stripe extending from the snout to the operculum and two longitudinal stripes on the body, one dorsal and the other ventral, that unite at the caudal peduncle. At first, there is a differential growth of the head and tail, and then there is the growth of the body, which shows changes in the ontogenetic priorities of feeding, swimming, and breathing capacities. Our results are very important for ecology, systematics, and hatchering, especially in terms of ontogenetic variation in morphology, growth, feeding, behavior, and mortality of P. reticulatum. RESUMO Este estudo descreveu o desenvolvimento inicial de Pseudoplatystoma reticulatum, bem como as mudanças nos padrões de crescimento, testando a hipótese da ocorrência de crescimento diferencial durante a ontogenia inicial da espécie. Variáveis morfométricas e merísticas foram analisadas durante os períodos embrionário, larval e juvenil, assim como os coeficientes de crescimento alométrico para larvas e juvenis. Os ovos apresentaram diâmetro médio de 1,79 mm e espaço perivitelino amplo (23,41%). O comprimento total (CT) das larvas variou de 3,05 a 125,72 mm e o número total de miômeros de 45 a 50 (pré-anal=13-16 e pós-anal=30-35). A pigmentação inicial é escassa, concentrada nas extremidades do saco vitelino. A partir do estágio de flexão a pigmentação se intensifica, formando uma faixa longitudinal que se estende do focinho ao opérculo e duas no corpo, uma dorsal e outra ventral, que se unem no pedúnculo caudal. Inicialmente há um crescimento diferenciado da cabeça e da cauda, com posterior crescimento do tronco, que demonstra mudanças nas prioridades ontogenéticas para as capacidades de alimentação, natação e respiração. Nossos resultados são de grande importância para a ecologia, sistemática e larvicultura, especialmente em termos de variação ontogenética na morfologia, crescimento, alimentação, comportamento e mortalidade P. reticulatum.

Summary A mark-recapture study was conducted in 1997-2005 to investigate movements of stocked pacu, Piaractus mesopota- micus, in the ParanaRiver Basin of Brazil, Paraguay, and Argentina. Fish raised in cages within the Itaipu Reservoir and in ponds were tagged externally (n = 2976) and released in the Itaipu Reservoir (53.2%) and bays of its major tributaries (46.8%). In total, 367 fish (12.3%) were recaptured. In all, 91% of the pacu moved away from the release site; upstream movements were more extensive than downstream movements. Pacu traveled upstream a maxi- mum of 422 km (average of 41.3 km) at a maximum rate of 26.4 km day )1 (av. 0.8). Downstream movements were limited in terms of number of individuals and distance moved. Fish released during the wet season moved farther than those released during the dry season, and feeding rather than spawning might have been the compelling reason for movement. Although fish passed downstream through dams, none of the marked fish were detected to have moved upstream through the passage facilities. Pacu showed move- ment patterns not radically different from those of other neotropical migratory species, but their migratory move- ments may not be as extensive as those of other large migratory species in the basin.

– We studied the migratory behaviour of armado, Pterodoras granulosus, in the Parana River Basin of Brazil, Paraguay and Argentina, during 1997–2005. This species invaded the Upper Parana River after upstream dispersal was facilitated when Itaipu Reservoir inundated a natural barrier. Fish were tagged (N = 8051) in the mainstems of the Yacyreta and Itaipu reservoirs, bays of major tributaries, the Parana River floodplain above Itaipu Reservoir, and below dams. In all, 420 fish were recaptured of which 61% moved away from the release area. Fish moved a maximum of 215 km (mean 42), and at a maximum rate of 9.4 km·day−1 (mean 0.6). Of the 256 armados that moved away from the release site, 145 moved upstream towards unimpounded stretches of the Parana River and 111 moved downstream into the reservoir and bays of its tributaries (maximum 150 km). Based on the observed migratory movements, we suspect that most of the reproductive output originates in tributaries to the reservoirs. The ability of this species to expand its range presents a conundrum by pitting fishery management interests against conservation needs. Maintenance of the important armado fisheries depends on the ability of the species to migrate freely to use spawning and nursery areas in reservoir tributaries and floodplains. However, its ability to migrate long distances can allow this non-native species the opportunity to invade most of the Upper Parana River.

Made available in DSpace on 2019-10-06T16:02:28Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 We evaluated the effectiveness of the fish ladder at Porto Primavera Dam in the severely regulated Upper Paraná River, for two Neotropical migratory fish species. Overall, 564 fish (448 Megaleporinus obtusidens and 116 M. piavussu) were PIT-tagged, released in upstream and downstream areas (on the left and right banks), and monitored continuously for 4 years. The fish performed two-way movements through the fish ladder, ascending from the tailrace and descending from the forebay. We registered entry into the fishway of 46 M. obtusidens (10.3%) individuals and only three M. piavussu (2.6%) individuals; therefore, all analyses were focussed on M. obstusidens. Entry proportion ranged from 0 to 48.1%, depending on the release site, and was greatest for fish released downstream near the fishway entrance. Entry times ranged from 3.0 to 384.0 days, and median times were 32.9 and 25.8 days for downstream and upstream respectively. Of fish that entered the fishway, passage percentages were 80% for fish released downstream and 100% for fish released upstream, and median transit times were 0.7 and 0.9 h respectively. Results suggest that if guidance and entry conditions can be improved, this fishway design holds promise as an effective solution for providing passage in both directions. Universidade Estadual Do Oeste Do Paraná Programa de Pos-Graduacao em Conservacao e Manejo de Recursos Naturais Jardim Universitário, Rua Universitária 2069 Universidade Estadual Do Oeste Do Paraná Grupo de Pesquisa em Tecnologia em Ecohidraulica e Conservacao de Recursos Pesqueiros e Hidricos Programa de Pós-Graduação em Recursos Pesqueiros e Engenharia de Pesca, Rua da Faculdade, 645 US Geological Survey-Leetown Science Center S.O. Conte Anadromous Fish Research Center Universidade Estadual Paulista-UNESP Engineering College of Ilha Solteira Department of Biology and Zootechny Fish Ecology Laboratory Universidade Estadual Paulista-UNESP Engineering College of Ilha Solteira Department of Biology and Zootechny Fish Ecology Laboratory

This study characterized the morphological differences among migratory fish species from the Paraná River Basin. A total of 177 adult fish of Leporinus elongatus, Leporinus macrocephalus, Prochilodus lineatus, Salminus brasiliensis, Pimelodus maculatus, Pinirampus pirinampu, Pseudoplatystoma corruscans, Pterodoras granulosus, and Rhaphiodon vulpinus were sampled in the Canal da Piracema, a fish passage system at Itaipu Dam, Paraná River. The migratory species were analyzed through 22 morphometric measurements and fineness ratio to identify morphological patterns related to swimming performance. Four species groups were indicated by the Cluster analysis: I) R. vulpinus; II) P. corruscans; III) L. macrocephalus, L. elongatus, P. lineatus, P. maculatus, and S. brasiliensis - measurements of head height and anal fin length formed this group; and IV) P. granulosus and P. pirinampu - measurements of maximum body width and caudal peduncle width contributed to form this group. The morphometric variables that most contributed to the distinction were head length and mouth width for groups I and II. The species R. vulpinus and P. granulosus differed from other species, showing fineness ratios of 9.4 and 3.7, respectively. Leporinus elongatus, L. macrocephalus, P. lineatus, P. maculatus, and S. brasiliensis showed significant differences from other species, with ratios ranging from 4.57 to 5.19, indicating that these species may be better swimmers. Long-distance migratory species using the Piracema Canal to ascend upstream areas differed morphologically, morphological characteristics such as a narrow caudal peduncle and maximum body length, besides to the values of the fineness ratio, were essential to differentiate the migratory species. Este estudo caracterizou as diferenças morfológicas entre espécies de peixes migradores da bacia do rio Paraná. Um total de 117 peixes adultos das espécies Leporinus elongatus, Leporinus macrocephalus, Prochilodus lineatus, Salminus brasiliensis, Pimelodus maculatus, Pinirampus pirinampu, Pseudoplatystoma corruscans, Pterodoras granulosus e Rhaphiodon vulpinus foram capturados no Canal da Piracema, um sistema de transposição para peixes na barragem de Itaipu, rio Paraná. As espécies migradoras foram analisadas através de 22 medidas morfométricas e razão fineza para identificar padrões morfológicos relacionados à capacidade natatória. Quatro grupos de espécies foram evidenciados pela Análise de Cluster: I) R. vulpinus; II) P. corruscans; III) L. macrocephalus, L. elongatus, P. lineatus, P. maculatus e S. brasiliensis, medidas de altura de cabeça e comprimento da nadadeira anal formaram este grupo; e IV) P. granulosus e P. pirinampu - medidas de largura máxima do corpo e largura do pedúnculo caudal contribuíram para a formação deste grupo. As variáveis morfométricas que mais contribuíram para distinção dos grupos I e II foram comprimento da cabeça e largura da boca. As espécies R. vulpinus e P. granulosus diferiram das demais, apresentando razão de fineza de 9,4 e 3,7, respectivamente. Leporinus elongatus, L. macrocephalus, P. lineatus, P. maculatus, S. brasiliensis diferiram significativamente das demais espécies com valores de razão fineza que variaram entre 4,57 a 5,19, indicando que estas espécies podem apresentar melhor desempenho natatório. As espécies migradoras de longa distância que utilizam o Canal da Piracema para ascender áreas a montante diferiram morfologicamente, características morfológicas como pedúnculo caudal estreito e largura máxima do corpo, bem como os valores de razão de fineza foram determinantes na diferenciação das espécies aqui analisadas.

The majority of the fish passages built in the Neotropical region are characterised by low efficiency and high selectivity; in many cases, the benefits to fish populations are uncertain. Studies conducted in the Canal da Piracema at Itaipu dam on the Parana River indicate that the system component designated as the Discharge channel in the Bela Vista River (herein named Canal de deságue no rio Bela Vista or CABV), a 200 m long technical section, was the main barrier to the upstream migration. The aim of this study was to evaluate the degree of restriction imposed by the CABV on upstream movements of Prochilodus lineatus and Leporinus elongatus, Characiformes. Fish were tagged with passive integrated transponders (PIT tags) and released both downstream and upstream of this critical section. Individuals of both species released downstream of the CABV took much more time to reach the upper end of the system (43.6 days vs. 15.9 days), and passed in much lower proportions (18% vs. 60.8%) than those tagged upstream of this component. Although more work is needed to differentiate between fishway effects and natural variation in migratory motivation, the results clearly demonstrate passage problems at the CABV. A maioria dos sistemas para transposição de peixes implantados na região Neotropical caracteriza-se por baixa eficiência e seletividade, em muitos casos com benefícios questionáveis para as populações de peixes. Estudos conduzidos no Canal da Piracema, localizado na barragem de Itaipu, rio Paraná, apontaram como principal barreira à migração ascendente o componente do sistema denominado Canal de deságue no rio Bela Vista (CABV), uma seção de escada com 200 m de extensão. Este estudo teve por objetivo avaliar o grau de restrição imposto pelo CABV aos movimentos ascendentes de Prochilodus lineatus e Leporinus elongatus, Characiformes. Os peixes foram marcados com Passive Integrated Transponders (PIT-tags) e soltos a jusante e a montante do CABV. Indivíduos de ambas as espécies de jusante do CABV levaram muito mais tempo para atingirem a extremidade superior do sistema (43,6 dias vs. 15,9 dias) e passaram em muito menor proporção (18% vs. 60,8%) do que os marcados a montante desse componente. Embora sejam necessários outros trabalhos para a distinção entre os efeitos do sistema de transposição de peixes e a variação natural da motivação migratória, os resultados demonstram claramente que existem problemas na passagem pelo CABV

This study assessed differences in fish assemblages existing upstream and downstream two types of culverts, one on each of two different Neotropical streams. We analyzed the composition and structure of the ichthyofauna and tested for spatial patterns. Fish sampling was carried out monthly between November 2009 and October 2010 using different fishing gears. We collected 2,220 fish of 33 species; 901 in stretches of the Lopeí stream - circular culvert and 1,310 in stretches of the Pindorama stream - box culvert. Fish abundance was similar in upstream and downstream stretches of the circular culvert, whereas it was slightly higher in the upstream than downstream stretch for the box culvert. Characiformes predominated in the upstream stretch of both culverts. On the other hand, Siluriformes was abundant in the downstream stretch of the circular culvert, with similar abundance in the stretches of the box culvert. Species richness and diversity (Shannon-Weiner Index) were higher in the downstream stretch of the circular culvert, but they were similar in both stretches of the box culvert. The most abundant species were Astyanax altiparanae, A. paranae, A. fasciatus, Ancistrus sp., and Hypostomus sp. The last two species were more abundant in the downstream stretch of the circular culvert, and similar in stretches of the box culvert. Our study indicated variations in the species abundance, richness, and diversity between upstream and downstream stretches in particular of the circular culvert in the Lopeí stream, suggesting that fish movements are restrained more intensively in this culvert, especially for Siluriformes. The drop in the circular culvert outlet probably created passage barriers especially for those fish that has no ability to jump, where downstream erosion could lead to culvert perching. Studies on appropriate road crossing design or installation are fundamental whereas improvements in these structures can restore the connectivity of fish populations and communities in streams. Este estudo avaliou diferenças nas assembleias de peixes existentes a montante e a jusante dois tipos de bueiros, um em cada um de dois diferentes riachos Neotropicais. A composição e a estrutura da ictiofauna foram avaliadas e seus possíveis padrões espaciais. As amostragens para a ictiofauna foram realizadas mensalmente, entre novembro de 2009 e outubro de 2010, com diversos apetrechos de pesca. Durante o período foram coletados 2.220 indivíduos, sendo 901 peixes nos trechos do riacho Lopeí - bueiro circular e 1.310 peixes nos trechos do riacho Pindorama - bueiro quadrado, pertencentes a 33 espécies. As capturas foram similares nos trechos de montante e jusante no bueiro circular, enquanto que para o bueiro quadrado a abundância de peixes foi um pouco superior no trecho a montante em relação à jusante. Os Characiformes predominaram no trecho a montante de ambos os bueiros. Por outro lado, os Siluriformes foram abundantes no trecho a jusante do bueiro circular, com abundâncias similares entre os trechos do bueiro quadrado. A riqueza e a diversidade de espécies diferiram entre os trechos do bueiro circular (maior valor a jusante), enquanto que os valores foram similares para os trechos do bueiro quadrado. As espécies mais abundantes foram Astyanax altiparanae, A. paranae, A. fasciatus, Ancistrus sp. e Hypostomus sp., porém com diferenças constatadas na ocorrência das duas últimas espécies: estas foram mais abundantes a jusante do bueiro circular, e similares nos trechos do bueiro quadrado. As variações na abundância, riqueza e diversidade constatadas entre trechos a montante e a jusante, em particular do bueiro circular no riacho Lopeí, sugerindo que os movimentos de peixes são restritos de forma mais intensa neste bueiro, especialmente para Siluriformes. A queda de água na saída do bueiro circular provavelmente cria barreira à passagem dos peixes, especialmente para aqueles peixes que não tem capacidade de saltar, onde a erosão a jusante pode levar a empoleiramento. Estudos sobre projetos de bueiro ou instalações apropriadas são fundamentais considerando que a melhoria destas estruturas pode restaurar a conectividade de populações e comunidades de peixes em riachos.

Migratory behaviour of selected fish species is described in the Parana River, Brazil-Argentina-Paraguay, to search for patterns relevant to tropical regulated river systems. In a 10 year mark-recapture study, spanning a 1425 km section of the river, 32 867 fishes composed of 18 species were released and 1083 fishes were recaptured. The fishes recaptured were at liberty an average 166 days (maximum 1548 days) and travelled an average 35 km (range 0-625 km). Cluster analysis applied to variables descriptive of movement behaviour identified four general movement patterns. Cluster 1 included species that moved long distances (mean 164 km) upstream (54%) and downstream (40%) the mainstem river and showed high incidence (27%) of passage through dams; cluster 2 also exhibited high rate of movement along the mainstem (49% upstream, 13% downstream), but moved small distances (mean 10 km); cluster 3 included the most fishes moving laterally into tributaries (45%) or not moving at all (25%), but little downstream movement (8%); fishes in cluster 4 exhibited little upstream movement (13%) and farthest downstream movements (mean 41 km). Whereas species could be numerically clustered with statistical models, a species ordination showed ample spread, suggesting that species exhibit diverse movement patterns that cannot be easily classified into just a few classes. The cluster and ordination procedures also showed that adults and juveniles of the same species exhibit similar movement patterns. Conventional concepts about Neotropical migratory fishes portray them as travelling long distances upstream. The present results broaden these concepts suggesting that migratory movements are more diverse, could be long, short or at times absent, upriver, downriver or lateral, and the diversity of movements can vary within and among species. The intense lateral migrations exhibited by a diversity of species, especially to and from large tributaries (above reservoirs) and reservoir tributaries, illustrate the importance of these habitats for the fish species life cycle. Considering that the Parana River is highly impounded, special attention should be given to the few remaining low-impact habitats as they continue to be targets of hydropower development that will probably intensify the effects on migratory fish stocks.

Este estudo teve como o objetivo avaliar a ocorrencia e distribuicao espacial e temporal de ovos e larvas de peixes, bem como, verificar a composicao e estrategias reprodutivas das especies ao longo do rio Aguapei - SP. As coletas foram realizadas mensalmente de outubro/2009 a marco/2010, atraves de arrastos horizontais na superficie da agua durante 10 minutos ao anoitecer utilizando rede de plâncton conico-cilindrica de 0,5mm de malha. Diferencas significativas na densidade media do ictioplâncton entre os locais e meses foram averiguadas atraves da Analise de Variância Unifatorial (ANOVA one-way). Um total de 1.626 ovos e 1.547 larvas foram coletados. A ANOVA aplicada nao demonstrou diferencas significativas nas densidades do ictioplâncton em relacao aos pontos amostrados. Com relacao a distribuicao temporal diferencas significativas p

Improperly installed or poorly maintained culverts can pose a serious threat to fish by disrupting their habitat and endangering spawning success. Road culverts that are not designed for fish passage frequently can become obstacles. This can be especially problematic for migratory species, but can lead to fragmentation of resident populations as well. This study evaluated 40 culverts of 29 sites within a 25-km radius from Toledo city, Paraná State, southern Brazil, with respect to their likely effects on movement of the local ichthyofauna. We collected data on the shape and length of culverts, culvert material, waterfall height, water column depth, slope, and estimated flow velocity. Culverts were categorized by level of barrier risk for upstream migration: high, medium, low, and impassable, as well as the type of barrier posed (fall height, depth, length and velocity). Most of culverts analyzed were considered potential barriers to fish movement, with 45% classified as impassible, 45% as high risk, 10% as medium risk, and no culverts as low risk. Brazilian culverts as fishways will require additional monitoring and studies to corroborate the premises proposed in the present study. Road culvert projects that are properly built and maintained will be able to simultaneously improve function of roadways and protect fish populations. Bueiros incorretamente instalados ou mal conservados podem representar uma séria ameaça para os peixes por fragmentar o seu habitat e comprometer o sucesso da desova. Bueiros em estradas que não são projetados para passagem de peixes freqüentemente tornam-se obstáculos. Isso pode ser especialmente problemático para as espécies migratórias, mas também pode levar à fragmentação das populações de peixes residentes. Este estudo avaliou 29 locais com 40 bueiros dentro de um raio de 25 km de Toledo, Estado do Paraná, sul do Brasil, com relação aos seus prováveis efeitos sobre a movimentação da ictiofauna local. Dados foram coletados sobre a forma e o comprimento dos bueiros, material utilizado, altura da queda de água, profundidade, declividade e velocidade estimada do fluxo. Os bueiros foram categorizados pelo nível de risco como barreira a migração ascendente: alto, médio, baixo e impassável, bem como o tipo de barreira imposta (altura da queda, profundidade, comprimento e velocidade). A maioria dos bueiros analisados foi considerada barreira para o movimento dos peixes, com 45% classificados como intransitáveis, 45% como alto risco, 10 % como médio risco, não havendo bueiros com baixo risco. Bueiros brasileiros como passagens para peixes necessitarão de monitoramento e estudos adicionais para corroborar as premissas propostas no presente estudo. Projetos de bueiros em estradas que estão devidamente construídos e mantidos serão capazes de simultaneamente melhorar a função das rodovias e proteger as populações de peixes.

This study investigated the external body morphology (based on morphometric data) and the swimming efficiency in fish passages (based on the ascent time in a fish ladder) of two Neotropical long-distance migratory species. The fish were collected in the fish ladder of the Porto Primavera Hydroelectric Power Plant (known as Engenheiro Sergio Motta), upper Paraná River, Brazil. The species differ in several morphometric ratios related to swimming performance. Prochilodus lineatus exhibited a higher muscle ratio and caudal fin length ratio. However, Leporinus elongatus showed higher values for the fineness ratio, a higher length from snout to pectoral fin base ratio, and a higher caudal peduncle depth factor. Although both species show good swimming performance, the characteristics listed above may enable L. elongatus to apply greater power and propulsion, allowing it to reach a high swimming speed and to exhibit greater efficiency than P. lineatus. Leporinus elongatus moves faster than P. lineatus and has a lower mean ascent time (1.39 hours) than P. lineatus (3.76 hours). Prochilodus lineatus would require a somewhat longer time to pass through the fish ladder. Este estudo investigou a relação entre a morfologia externa do corpo (baseado em dados morfométricos) e eficiência de natação em passagem para peixes (baseado no tempo de ascensão em uma escada para peixes) de duas espécies neotropicais migradoras de longas distâncias. Os peixes foram coletados na escada para peixes da Usina Hidrelétrica de Porto Primavera (conhecida como Engenheiro Sérgio Motta), alto Rio Paraná, Brasil. As espécies diferem em algumas razões morfométricas referentes ao desempenho de natação: Prochilodus lineatus apresentou valores mais elevados para razão muscular e razão do comprimento da nadadeira caudal. No entanto, Leporinus elongatus apresentou valores mais elevados para razão fineza, para razão do comprimento do focinho à base da nadadeira peitoral e para fator de largura do pedúnculo caudal. Embora ambas as espécies tenham um bom desempenho natatório, essas características podem permitir a L. elongatus aplicar uma maior potência e propulsão, permitindo atingir velocidades de natação elevadas e apresentar uma melhor eficiência em relação a P. Lineatus. Leporinus elongatus movimenta-se mais rápido, com um tempo médio de ascensão (1,39 horas) inferior ao de P. lineatus (3,76 horas), que requer um tempo um pouco maior para passar através da escada para peixes.