Ana T. Silva

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• PhD
• Senior Researcher at Norwegian Institute for Nature Research

The Atlantic salmon (Salmo salar) is an iconic species of significant ecological and economic importance. Their downstream migration as smolts represents a critical life-history stage that exposes them to numerous challenges, including passage through hydropower plants. Understanding and predicting fine-scale movement patterns of smolts near hydrop...

Understanding fish movement and response in relation to their environment near infrastructure and migratory barriers is crucial for developing sustainable fisheries management solutions. Intermediate-scale (time scales of minutes to days and spatial scales less than 2 km) movement models are a contemporary approach for understanding and predicting...

Hydropower is an important source of renewable energy, yet dams and other facilities can represent a real threat to migrating fish like salmon and eels, with millions killed in turbines every year. Researchers in the FishPath project aim to exploit the innate response of fish to turbulence to develop an innovative system to guide fish away from tur...

Hydropower plants commonly impede the downstream migration of Atlantic salmon (Salmo salar) kelts. Thus, understanding the effects of hydraulic conditions on kelt behaviour and passage performance at dams is crucial for developing effective mitigation measures. In this study, we investigated the influence of hydraulic conditions on kelt passage per...

Mitigation measures for downstream-migrating Atlantic salmon smolts (Salmo salar L.) are commonly insufficiently attractive to enable safe entrance and passage with no delay. Combining 2D telemetry with hydrodynamic modelling has been shown to be a good tool to better understand the influence of hydrodynamic factors on the migration route choice of...

The study presents several steps of a fish ramp geometry optimization performed with a 3D numerical model DualSPHysics, which is based on the smoothed particle hydrodynamics (SPH) method. The optimization process led to the design of a bottom ramp that is capable of providing suitable conditions for the migration of target fish species (Salmo truta...

The global population of European eel (Anguilla anguilla) is rapidly declining, and migration barriers in rivers are believed to be one of several key causes. While progress has been made in the development of bypass solutions, they are often constructed based on a limited knowledge of swimming behaviour. A bypass close to the stream bed is often r...

Sedimentation is one of the main eco-morphological and technological challenges associated with reservoirs. Sedimentation not only reduces the functional capacity of a reservoir by filling it, but also changes downstream sediment dynamics and habitat availability for the aquatic biota. Additionally, dams hinder free bi-directional fish passage, eme...

online presentation can be seen here at hour 2:42:22 :https://www.youtube.com/watch?v=-3nbNOFLCSs

Worldwide, the overwhelming number of man-made barriers in fluvial systems has been identified as one of the major causes of the reported staggering average declines of migratory fish. Fish passages, in particular close-to-nature types, which mimic the natural conditions of rivers, have been shown to help mitigate such problems. This study focuses...

Worldwide, the overwhelming number of man-made barriers in fluvial systems has been identified as one of the major causes of the reported staggering average declines of migratory fish. Fish passages have been shown to help mitigate such problems. Close-to-nature types of fish passages, such as bottom ramps, bypass channels, and fish ramps can be us...

Fish swimming performance is strongly influenced by flow hydrodynamics, but little is known about the relation between fine-scale fish movements and hydrodynamics based on in-situ investigations. In the presented study, we validated the etho-hydraulic fish swimming direction model presented in the River Mandal from Southern Norway, using similar be...

DualSPHysics is applied to model a 10-m long and 4-m wide section of a turbulent open channel flow representing a nature-like fish ramp. The geometry of the model includes a straight rectangular channel with a 5 % slope and with various bodies that mimic boulders and stones at the bottom of the channel. Various configurations of these elements are...

Dear Colleagues, Hydropower dams represent barriers for animal movement, in both upstream and downstream directions. For instance, fish can be blocked or delayed in their spawning migration and are subjected to injury or death when passing turbines, spillways, or bypasses in their downstream migration, resulting in cumulative negative impacts on t...

Repeat spawners constitute an important component of Atlantic salmon populations, but survival of post-spawning individuals (kelts) are often compromised by anthropogenic structures such as hydropower plants (HPPs). Potential effects of HPPs include migration delays and associated increased energy depletion, which potentially results in increased o...

Fish in a Hydrodynamic world: a conservation approach. Presentation on the fish-hydrodynamics interaction and how does such knowledge can be used on fish conservation . Online presentation can be seen here : https://www.youtube.com/watch?v=kzQRdOYF4Qo

The Iberian barbel (Luciobarbus bocagei) is one of the most common cyprinids in the Iberian Peninsula, whose migratory routes are often hampered by anthropogenic barriers. Fishways might be an effective mitigation measure if they integrate designed operational characteristics that account for the biomechanical requirements of this species. Understa...

Dear Colleagues, Habitat fragmentation of watercourses, river impoundment, and construction of large reservoirs are major threats to worldwide aquatic biodiversity (Winemiller et al., 2016, Silva et al., 2018). On one hand, hydropower is a renewable source of energy and an important part of the worldwide effort to reduce emissions of climate gasse...

Anthropogenic structures in rivers are major threats for fish migration and effective mitigation is imperative given the worldwide expansion of such structures. Fish behaviour is strongly influenced by hydrodynamics, but little is known on the relation between hydraulics and fish fine scale-movement. We combined 3D Computational fluid dynamics mode...

Fish in a Hydrodynamic world: a conservation approach. Presentation on the fish-hydrodynamics interaction and how does such knowledge can be used on fish conservation . Online presentation can be seen here : https://www.youtube.com/watch?v=kzQRdOYF4Qo

There is no generic solution to establish safe passage of downstream migrating fish passed hydropower facilities and mitigation measures are species‐ and site‐specific. Development of solutions is thus often based on “trial and error” and modelling based approaches may significantly reduce cost and time to arrive at successful mitigation. Here we e...

The interaction between hydrodynamics and the upstream migration of fish has been investigated in several studies over the past few years, but there has been a relative lack of investigation into the effects of hydraulics on the downstream migration of fish. In Norway, mortality associated with downstream migration is strongly related to hydropower...

Migration of adult European eels (Anguilla anguilla) from freshwater feeding grounds to oceanic spawning grounds is an energetically demanding process and is accompanied by dramatic physiological and behavioral changes. Humans have altered the aquatic environment (e.g., dams) and made an inherently challenging migration even more difficult; human a...

The obstruction of fish migratory routes by hydroelectric facilities is worldwide one of the major threats to freshwater fishes. During downstream migration, fish may be injured or killed on the trash-racks or in the hydropower turbines. Fish-friendly trash-racks that combine both ecological and technical requirements are a solution to mitigate fis...

Global stocks of freshwater fish have been on the decline for decades, driven in part by the obstruction of their migration routes by anthropogenic barriers. To mitigate such impacts, fishways have been developed to facilitate bidirectional fish migration. These structures are affected by the hydrological variability of rivers, which can cause chan...

Much effort has been devoted to developing, constructing and refining fish passage facilities to enable target species to pass barriers on fluvial systems, and yet, fishway science, engineering and practice remain imperfect. In this review, 17 experts from different fish passage research fields (i.e., biology, ecology, physiology, ecohydraulics, en...

Swimming costs (SCs) for fish have been shown to be affected by turbulence. However, this idea has not yet been implemented in habitat models, which often represent hydraulics using water velocity averaged over time and space. In this study, we analysed the habitat selection of individual juvenile Atlantic salmon Salmo salar (L. 1758) in relation t...

The presence of small weirs, far more numerous than dams, has increased habitat fragmentation on rivers worldwide. This study aims to evaluate the upstream passage performance of a potamodromous cyprinid, the Iberian barbel (Luciobarbus bocagei), over an experimental broad-crested weir by varying key-hydraulic parameters. Fish passage success was s...

Early career researchers (ECRs) play a critical role in our increasingly knowledge-based society, yet they are the most vulnerable group in the scientific community. As a relatively young, interdisciplinary science, ecohydraulics is particularly reliant on ECRs for future progress. In 2014, the Early Careers on Ecohydraulics Network (ECoENet) was c...

A fragmentação dos cursos de água devido à implementação de obras hidráulicas tem originado sérias alterações nos ecossistemas. Comparativamente com os vários estudos que têm sido realizados em relação aos impactes nas populações piscícolas dos grandes empreendimentos hidráulicos, como as barragens e os pequenos aproveitamentos hidroelétricos, os p...

O projeto FISHMOVE – Desenvolvimento de Medidas de Mitigação para Pequenas Barreiras à Migração de Peixes Dulçaquícola em Rios Portugueses, teve como principais objetivos avaliar os efeitos de pequenos obstáculos fluviais nos movimentos migratórios de espécies ciprinícolas nativas, em particular a sua capacidade de transposição através de açudes de...

While fine mesh trash racks constitute a safe barrier for downstream migrating smolts, such racks can be expensive and technically difficult to retrofit at hydropower intakes. Alternatively, a combination of attraction and repulsion measures can successfully pass fish by the intake and into safe corridors. At the Laudal hydropower plant in the rive...

The sea lamprey (Petromyzon marinus) is an invasive species in the Great Lakes system and it is deemed a major cause of the collapse of the lake trout (Salvelinus namaycush) in this system. This species is characterized as aggressively, predaceous, externally attaching and feeding on blood and fluids of several fish species. Consequently, the physi...

The presence of small man-made barriers like small weirs, far more numerous than dams, alters the river system and negatively affects fish communities, mainly by disturbing fish movements and hindering access to spawning, feeding and refuge locations. However, in contrast to the vast literature on dams, much less is known about the effects of small...

Flow characteristics associated with spillways are important to restore ecological connectivity because spillways can either constrain or offer safe routes for downstream passage of fish. We studied the hydrodynamics of flow and downstream movement behaviour of the catadromous European eel (Anguilla anguilla) and the potamodromous Iberian barbel (L...

Fishways have been developed to restore longitudinal connectivity in rivers. Despite their potential for aiding fish passage, fishways may represent a source of significant energetic expenditure for fish as they are highly turbulent environments. Nonetheless, our understanding of the physiological mechanisms underpinning fishway passage of fish is...

Fishways have been developed to restore longitudinal connectivity in rivers. Despite their potential for aiding fish passage, fishways may represent a source of significant energetic expenditure for fish as they are highly turbulent environments. Nonetheless, our understanding of the physiological mechanisms underpinning fishway passage of fish is...

The goal of this study was to assess the performance of two boulder density designs combined with two fishway discharges, in assisting upstream passage of a potamodromous cyprinid species, the Iberian barbel (Luciobarbus bocagei), in an experimental full-scale pool-type fishway. Four different configurations were tested by changing the flow (Q), ma...

Silver redhorse (Moxostoma anisurum) is a catostomid species common to many rivers of eastern North America. We examined swimming activity and behaviour of silver redhorse during their upriver spawning migration when they encountered a vertical slot fishway. Twelve redhorse were tagged with PIT tags and monitored by an extensive PIT antenna array t...

Efforts to restore river connectivity have been made in an attempt to improve the sustainability of fish stocks in rivers impacted by in-stream structures. Of particular concern is the development of efficient downstream passage systems, which minimize the risk of injury and mortality associated with turbines in hydropower stations (HPS). Spillways...

Literature related to pool-type fishways has seen a recent upsurge of interest in the placement of instream structures for improving fish passage. However, there is still no information on how different flow regimes created by boulder placement have an influence on upstream fish movements. The main goal of this study was to assess the performance o...

Flow characteristics near and over spillways are important for ecological, as well as design, aspects. Spillways may either interfere with fish movements or offer a safe route for downstream passage. Hydrodynamics and movement behaviour of the European eel and Iberian barbel are investigated for standard WES ogee spillways with upstream face inclin...

Although coarse fish species are frequently the predominant taxa found in rivers, they are often neglected in fish passage studies. Detailed knowledge on the impact of hydraulics on the movements and swimming performance of these species is very limited. In this study, offset and straight orifices in a pool-type fishway prototype were tested in ter...

Several authors state that heterogeneity on the bottom of fishways (logs, boulders or stones) may potentiate fish passage. The aim of this work is to study the behavior and performance of the Iberian barbel (luciobarbus bocagei) in a full-scale experimental pool-type fishway with different bottom substrata arrangements. Water velocity and Reynold's...

The restoration of fish passage has been focused on anadromous fish species, whilst studies accommodating passage of coarse species have often been considered incidental, yet frequently these are the predominant group of species encountered in rivers. In addition, fishway designs depend greatly on the interplay between hydraulics and biomechanics,...

The introduction of habitat structures in river channels has become one of the most common ways to minimize the habitat losses derived from dam and weir construction. As a result, fishways related literature has seen a recent upsurge of interest in this kind of structures for improving fish passage. Despite their increasing utilization in nature-li...

Trends in fish passage studies are increasingly moving towards a holistic approach in considering the movements of a wide range of fish species and other aquatic fauna. In this context, it is important to consider not only salmonids and other game species, but also coarse species such as cyprinids. Moreover, knowledge of their behaviour when confro...

Portuguese rivers are particularly regulated by dams and weirs that, by deterring fish migration, contribute to species and habitat loss. Fishways can minimize part of the negative impacts associated with these obstructions but their efficiency must be guaranteed by adjusting the design of the facilities to the potential users. In this study we use...

This study analyses the impact of different hydraulic conditions on the Iberian barbel’s upstream movements in a pool-type fishway. Developed in an experiment pool-type fishway prototype and including fish of different sizes, this study investigates: i) the efficiency of passage through submerged orifices or notches; ii) the effect of velocity, tur...

O conhecimento e compreensão dos padrões comportamentais do barbo ibérico, Barbus bocagei, durante a utilização de uma escada para peixes são escassos. Neste trabalho foi estudado o comportamento desta espécie em resposta a diferentes condições hidráulicas num protótipo experimental, à escala real, de uma passagem para peixes (PPP) por bacias suces...

RESUMO O conhecimento e compreensão dos padrões comportamentais do barbo ibérico, Barbus bocagei, durante a utilização de uma escada para peixes são escassos. Neste trabalho foi estudado o comportamento desta espécie em resposta a diferentes condições hidráulicas num protótipo experimental, à escala real, de uma passagem para peixes (PPP) por bacia...

The knowledge of the behaviour of cyprinid fish species that can be found in most Portuguese rivers, such as barbel (Barbus sp.) and nase (Chondrostoma sp.), when overtaking obstacles is scarce. The main goal of this study is to monitor their behaviour through a pool-type fishway installed on the National Laboratory for Civil Engineering (LNEC), Li...

The knowledge of the behaviour of cyprinid fish species that can be found in most Portuguese rivers, such as barbel (Barbus sp.) and nase (Chondrostoma sp.), when overtaking obstacles is scarce. The main goal of this study is to monitor their behaviour through a pool-type fishway installed on the National Laboratory for Civil Engineering (LNEC), Li...

RESUMO O presente trabalho tem como objectivo o desenvolvimento de uma unidade de demonstração (UD) de uma passagem para peixes por bacias sucessivas adaptada a espécies ciprinícolas existentes em Portugal, nomeadamente barbos (Barbus sp) e bogas (Chondostroma sp.). Estas espécies encontram-se presentes na quase totalidade dos rios Portugueses, mas...