Protecting efficiently sea-migrating salmon smolts from entering hydropower plant turbines with inclined or oriented low bar spacing racks

Restoring the longitudinal connectivity of rivers is becoming a conservation priority in countries with high hydroelectric plant (HEP) development. Newly designed downstream passage solutions for fish are being installed in small and medium-sized HEPs in France, and an accurate evaluation of their functionality is needed. Here we addressed the efficiency of protection systems for the downstream migration of Atlantic salmon smolts at four HEPs (three 26° horizontally inclined racks and one 15° oriented to the flow rack in the bank alignment, all with 20 mm spaced bars). Between 239 and 300 hatchery-reared salmon smolts were PIT-tagged and released in 5–6 groups 100 m upstream of each studied HEP. Their passages through the HEPs were detected with radio frequency identification (RFID) antenna in the bypasses for downstream migration and the fish passes for upstream migration. On average between 82.8% and 92.3% of released smolts successfully passed the HEP through one of the two non-turbine routes. Resulting mean bypass passage efficiency ranged from 80.9 to 87.5% and all fish groups reached over 70% passage efficiency. Excepting one site, 50% of smolts passed through the bypass in less than 23 min after release, and 75% of them in less than 2 h 15 min. Combining our findings with previously estimated fish entrainment rates into the intake channel and turbine-related mortality rates, we assessed the overall fish survivals at the studied dam/HEPs which are between 98.24% and near 100%. Our results confirm recommended design criteria for inclined and oriented racks and the interest of the tested devices for the protection of downstream migrating salmon smolts

Efficiency of fish-friendly intakes, bypasses associated with low bar-spacing trashracks, for downstream migration of Atlantic salmon smolts

Lessons learned about the efficiency of fish-friendly water intakes at 4 power plants in France

Tamaño corporal, tolerancia ecológica y potencial de bioindicación de la calidad del agua de Anacroneuria spp. (Plecoptera: Perlidae) en América del Sur

El conocimiento sobre la biología y la ecología de los organismos acuáticos neotropicales es de gran importancia para evaluar reglas ecológicas generales y para establecer un sistema de protección de los recursos acuáticos. Basado principalmente sobre datos recoleccióndos en publicaciones anteriores, el presente trabajo muestra las siguientes características biológicas y ecológicas de las especies del género Anacroneuria (Klapálek 1909; Perlidae: Plecoptera): a) la gran amplitud de las condiciones ambientales de los ríos poblados por el género Anacroneuria, b) la disminución del número de especies sobre una gradiente de altitud, c) el aumento del tamaño corporal con la altitud máxima, d) el aumento del ámbito altitudinal con el tamaño corporal, e) la relación constante entre el tamaño del macho y de la hembra, y finalmente, f) el aumento del tamaño de los huevos con el tamaño de la hembra. Sugerimos que la familia Perlidae y el género Anacroneuria no debrían ser automaticamente considerados como excelentes indicadores de la calidad del agua en la zona neotropical.Body size, ecological tolerance and potential for water quality bioindication in the genus Anacroneuria (Plecoptera: Perlidae) from South America. Knowledge about the biology and ecology of neotropical aquatic taxa is crucial to establish general ecological rules and water protection systems. Based mainly on published data, the present work shows the following biological and ecological characteristics of Anacroneuria species (Klapálek 1909): a) the wide range of environmental conditions of rivers where Anacroneuria species occur, b) species number decreases along an increasing elevation gradient, c) body size increases in relation to the maximum altitude of occurrence, d) altitudinal range increases with body size, e) there is a constant relationship between male and female body size, and finally, f) larger females lay larger eggs. In temperate countries, the family Perlidae in general, and the genus Anacroneuria in particular, are viewed as excellent water quality indicators. We suggest that, considering the complexity of the group’s ecology in South America, it should not be automatically considered an excellent bioindicator in the Neotropical region. Rev. Biol. Trop. 55 (1): 67-81. Epub 2007 March. 31

Tamaño corporal, tolerancia ecológica y potencial de bioindicación de la calidad del agua de Anacroneuria spp. (Plecoptera: Perlidae) en América del Sur

El conocimiento sobre la biología y la ecología de los organismos acuáticos neotropicales es de gran importancia para evaluar reglas ecológicas generales y para establecer un sistema de protección de los recursos acuáticos. Basado principalmente sobre datos recoleccióndos en publicaciones anteriores, el presente trabajo muestra las siguientes características biológicas y ecológicas de las especies del género Anacroneuria (Klapálek 1909; Perlidae: Plecoptera): a) la gran amplitud de las condiciones ambientales de los ríos poblados por el género Anacroneuria, b) la disminución del número de especies sobre una gradiente de altitud, c) el aumento del tamaño corporal con la altitud máxima, d) el aumento del ámbito altitudinal con el tamaño corporal, e) la relación constante entre el tamaño del macho y de la hembra, y finalmente, f) el aumento del tamaño de los huevos con el tamaño de la hembra. Sugerimos que la familia Perlidae y el género Anacroneuria no debrían ser automaticamente considerados como excelentes indicadores de la calidad del agua en la zona neotropical

Patterns of benthic community traits in neotropical streams: relationship to mesoscale spatial variability

International audienc

Étude de l’efficacité de la restauration de la continuité écologique utilisant la différenciation génétique au sein de populations de poissons

Suite à la Loi sur l'Eau et les Milieux Aquatiques de 2006, les aménagements situés sur les cours d'eau classés en liste 2 et entravant la continuité écologique doivent être équipés ou gérés de manière à rétablir le franchissement des poissons. Compte tenu du coût de ces opérations, les maîtres d'ouvrage chargés de la mise en œuvre technique de la restauration de la continuité doivent bénéficier d'outils de diagnostic de la franchissabilité des obstacles fiables afin d'optimiser la planification des actions. Les outils de génétique des populations offrent l'opportunité de développer de tels indicateurs, mais cela nécessite des développements pour gagner en précision et en opérationnalité. En particulier, un indicateur génétique (le F-index) a récemment été développé et appliqué, mais certaines de ses limitations pourraient être levées en utilisant des données génomiques issues du séquençage nouvelle génération (SNG). Ainsi, l'objectif principal de cette note technique est de présenter le développement d'un nouvel indicateur génomique de fragmentation et de tester son efficacité dans un contexte réel de fragmentation et de restauration de la continuité écologique. Dans unpremier temps, un travail de simulations numériques a permis de développer analytiquement un F-index basé sur l'utilisation de données génomiques sous la forme de milliers de marqueurs SNP (Single Nucleotide Polymorphisms). Dans un second temps, une autre série de simulations a montré que, comme attendu, le F-index "génomique" était plus précis (moins de variabilité dans les estimations) et permettait un meilleur diagnostic que le F-index "classique" (basé sur des marqueurs "microsatellites"). Enfin, sur la base de sept cas d'étude empirique sur les rivières Cher et Sarthe, nous avons démontré : (i) que les conclusions obtenues entre le F-index génomique et le F-index classique étaient globalement cohérentes, mais que certaines situations contrastées soulevaient les limites et forces de chacune des approches, (ii) que certaines conclusions basées sur les approches moléculaires n'étaient pas cohérentes avec les dires d'experts, montrant la complémentarité des approches mais aussi la difficulté d'estimer convenablement le phénomène complexe qu'est le franchissement d'un obstacle (que ce soit d’un point de vue génétique ou physique), et (iii) que le F-index génomique, bien que prometteur, n'est pas encore opérationnel et nécessite d'homogénéiser et de rendre plus répétables les procédures de séquençage et de bio-informatiques nécessaires à l'obtention des données génomiques. Pour conclure, nous discutons des résultats obtenus au regard des difficultés rencontrées, des limites et avantages de l'approche génomique, et des futurs travaux qui pourraient améliorer la précision de l'approche génétique

Updated mortality estimation formulae for salmonids passing through Francis turbines at hydropower plants

Downstream migrating fish can be strongly affected by hydroelectric facilities. To set up adapted mitigation measures, it is important to identify these impacts (e.g. induced mortality rates). For Francis turbines, two mortality prediction formulas, developed in 1989 and updated in 2000, are currently used in France for salmonids according to turbine characteristics and fish size (Larinier and Dartiguelongue, 1989, updated by Bosc and Larinier, 2000). However, their use is limited when some parameters are unknown, such as turbine speed. Moreover, the updated version of can be criticized because of its unpublished development procedure and its unknown predictive power. The main purpose of this study is to update the existing formulae to meet the following objectives: (1) a transparent development procedure, (2) formulae simplification, (3) the use of simple (usually the best-known) turbine parameters, and (4) a maximization of the predictive power and an assessment of prediction errors. Based on data from 73 in situ mortality tests available in peer-reviewed and ‘grey’ literature, we developed two new formulae to estimate salmonid mortality rate in Francis turbines. The first one uses turbine peripheral speed, diameter and fish size (correlation between predicted and observed mortality rates r = 0.89, and root mean square error RMSE = 0.11). The second one is based on usually known parameters: turbine discharge, water head and fish size, to allow a broader applicability (r = 0.89, RMSE = 0.10). This study comforts the validity of previous formulae and provides two new ones allowing a satisfactory precision in the estimations

Evaluation of a fine-spaced angled rack with surface bypass in providing safe and timely downstream passage for salmon smolts and silver eels

Hydropower production can cause migration delay and fish mortality, impeding the safe and timely downstream migration of diadromous fish, such as Atlantic salmon (Salmo salar) and silver eels (Anguilla anguilla). To date, only a few field performance tests, especially for eels, have evaluated the efficiency of fine-spaced angled racks associated to a surface bypass entrance to protect fish. Here, 115 salmon smolts and 65 silver eels were radio-tracked over a 2 yr period to assess passage efficiency and passage time at a hydropower intake (50 m3.s−1) retrofitted with a 20 mm rack associated to a surface bypass (2 m3.s−1). Results showed high impediment (89.6% and 96.9% for smolts and eels, respectively), and passage efficiency for the angled rack (89.1% and 93.3%), with short passage times (median, 3 and 7.5 min). However, our results highlighted a strong influence of hydrological conditions, in enhancing fish passage, especially through the bear-trap gate. We conclude that this fish passage solution, making use of existing spillways on the study site, is highly effective for both species. Special attention must, however, be paid to bar-rack design and its cleaning system to ensure fish guidance and prevent impingement or passage through the rack, especially for salmon smolts

Protecting the downstream migration of salmon smolts from hydroelectric power plants with inclined racks and optimized bypass water discharge

The sustained development of hydropower energy in the last century has caused important ecological impacts, promoting recent advances in efficient mitigation measures to be implemented in existing and future hydropower plants. Although upstream fish migration has been largely addressed with the development of fish-pass infrastructures, downstream passage solutions are often missing or inefficient, strengthening the need for their improvement and efficiency assessment. The efficiency of horizontally inclined (26°) low bar spacing racks associated to a bypass was assessed using salmon smolts radiotelemetry along three successive hydropower plants (HPP) in the Ariège River (southern France). In average, nearly 90% of the smolts were successfully protected by the racks and rapidly guided to the bypass, within few minutes in most cases. Furthermore, we detected a significant positive influence of the bypass discharge (Qbp% expressed as the proportion of concurrent HPP discharge) on the probability of successful bypass passage, reaching 85% of successful passage with a Qbp% of only 3%, and more than 92% when the Qbp% exceeded 5%. The probability of bypass passage without hesitation (e.g. passage within the first 5 min) also increased with Qbp%, and reached 90% with 5% of Qbp%. Passage without hesitation was especially detected on the site having larger bypass entrances and transversal currents, providing better guidance into the bypass. High-efficiency results of inclined racks yielded with reduced Qbp% confirmed their relevance to mitigate some of the HPP ecological impacts, re-establishing safe downstream salmon migration with lower impact on energy production than older less efficient solutions

Bypass discharge, approach velocities and bar spacing: the three key-parameters to efficiently protect silver eels with inclined racks

International audienceHydropower energy can contribute to achieve the carbon neutrality goals, but also needs to reach environmental sustainability. Hydropower plants (HPP) constitute barriers to fish migrations that are essential for accomplishing their complete biological cycle. Fish downstream passage solutions (FDPS) have to be implemented to maximize their survival, guiding them away from the turbine intakes towards a safe passage alternative. Recent telemetry studies confirmed the efficiency of 26°inclined low bar spacing (20 mm) rack associated to surface bypasses, installed upstream HPPs, to protect downstream migrating Atlantic salmon smolts. Here we tested the efficiency of such FDPS for eel protection using radiotelemetry at four successive HPPs (with intake capacities from 28 to 45 m 3 .s À1) in the Ariège River (southern France). Between 52 and 74 eels, longer than 550 mm, entered the HPP intakes and 100% of them were protected from turbine passage. All eels crossed the HPP water intake using the surface bypasses, and the great majority in few minutes from their first presentation in front of the rack. These results showed that in such rack configuration, it is not necessary to add a specific bottom bypass, usually recommended for eels. We also showed the importance of optimal hydraulic conditions, mainly tangential (parallel to the rack) velocity and bypass discharge, to efficiently guide the eels towards the surface bypasses, reducing their passage time. Overall, our study provided key elements to water managers for designing an efficient FDPS for eels