Fish Passage Research Articles

Computational studies of hydraulic stressors for biological performance assessment in a hydropower plant with Kaplan turbine

Hydropower is currently one of the preeminent sources of renewable energy in the United States and globally. Hydropower plants also have detrimental impacts on the environment and ecology, including direct impacts to anadromous fish populations. The computational fluid dynamics (CFD) – based Biological Performance Assessment (BioPA) toolset is used for biological evaluations of fish passage through hydropower plants. The hydraulic environment of a hydropower plant was evaluated using CFD coupled with discrete element method (DEM) simulations. The predicted flow field and particle collision rate were validated against the experimental data in a water flume that has an idealized hydroturbine distributor geometry. Flow simulations were conducted to evaluate the hydraulic stressors, such as nadir pressure, fluid shear, runner collision, in a physical scale in a hydropower plant with Kaplan turbine which are responsible for injury and mortality of fish in a downstream migration. The cumulative exposure probability for the nadir pressure and collision with turbine runner was found to decrease with increased discharge rate. The lowest discharge rate shows the higher value of cumulative shear exposure probability. The maximum value of collision velocity increases with increased discharge rate. We offer the conclusions that will help in understanding various hydraulic stressors for biological assessment for environmentally sustainable hydroturbine passage.

Brown Trout Upstream Passage Performance for a Fishway with Water Drops between Pools beyond Fish Passage Design Recommendations

This work aims to assess brown trout (Salmo trutta) passage through a free-flow pool-weir-type fishway with hydrodynamic notches and extreme water drops between pools. It consists of an old-school fishway design, commonly constructed in salmon rivers of Spain during the period of 1950–1980. To assess their performance, a field test was designed with confined trial conditions during the spawning migratory season. The mean water drop between pools was 0.65 m and the total water height considered for the trial was 11.8 m. The monitoring was carried out using PIT telemetry. The initial hypothesis, considering the fishway design and assessment guidelines, classified this structure as hardly insurmountable. Results showed an ascent success of 19% with a median transit time of 29.1 min/m of ascended height. Larger fish and fishway sections with lower values of volumetric power dissipation were related to a better performance in the passage. The results suggest that in certain circumstances, such as limited construction areas where other design or management options are difficult to implement (e.g., canyons), this type of fishway may be an alternative for the upstream passage of at least a small proportion of the brown trout population, although a selection effect is expected.

What influences spatial variability in restoration costs? Econometric cost models for inference and prediction in restoration planning

Habitat restoration efforts are often conducted under limited budgets and information. Explicitly incorporating data on project costs can improve the effectiveness of restoration investments but gathering precise data for future projects is often infeasible at the planning stage. We demonstrate econometric and machine learning methods for improving the accessibility of cost information for restoration planning. Using geospatial matching methods, we combine 15 years of spatially explicit project records for over 1200 culvert fish passage barrier restoration worksites across the Pacific Northwest of the United States with data layers of hypothesized drivers of construction costs. We distinguish between two objectives in analyzing cost data: inference to identify cost drivers and prediction of future project costs. For inference, we multiple linear regression and find that the variables channel bankfull width and slope, road speed class, developed and agricultural land covers, and proximity to privately managed industrial land are associated with culvert restoration costs and may serve as strong proxies in a planning setting. For prediction, we use boosted regression trees to make out-of-sample projections of restoration costs for over 27,000 barrier culverts documented in state inventories. The distribution of these cost projections over space and across jurisdictions reveal higher, and more heterogeneous, culvert restoration costs in the Puget Sound region than in other nearby areas. Our results are directly applicable for resource managers making fish passage restoration decisions and serve as a template for the use of econometrics and machine learning to analyze costs recorded in restoration project databases in other contexts.

Numerical Simulation and Experimental Verification of Downstream Fish migration in a Bulb turbine

Downward migrating fish can be damaged when passing through turbines in the direction upstream to downstream. The overall influence on the fish population is not known yet. In recent decades, many publications with steady-state CFD calculations for the passage of fish have been published. However, transient CFD calculations show that the range in which fish pass the runner itself is not easily predictable but rather random, influenced by the current position of the runner, thus affecting the probability of survival. The pressures, which are also well represented by steady-state CFD calculations, are compared by applying “Live Fish” (typical types for the middle of Europe) as well as “Barotrauma Detections Sensors (BDS)” which were exposed to the area of the turbine intake at different heights and monitored during downstream migration.

Restoring River Connectivity in Line with European Legislation

Abstract Water Framework Directive defines the river longitudinal continuity as “undisturbed migration of aquatic organisms and sediment transport”. Electrical energy production from hydro sources is the main risk that generates hydromorphological alteration of surface waters by disconnecting the rivers. The flow reduction on the river sector from the water intake to the restitution point of the small hydropower plant is also considered as a hydromorphological alteration that can modify the natural hydrological regime. This paper presents good practices for ensuring the river longitudinal connectivity while Small Hydropower Plants are implemented. In order to restore the river longitudinal connectivity for fish migration, some types of fish passages used within the hydropower facilities from Europe are presented and discussed. The recommended solutions are important to mitigate the small hydropower plants’ negative effects on river ecosystems and it can contribute to the increase of energy power units based on renewables.

Determining the position of a fish passage facility entrance based on endemic fish swimming abilities and flow field.

Hydropower development can significantly mitigate climate change and reduce carbon emissions, but it can also have substantial negative impacts on river environments and fish biodiversity. Fish passage facilities are built to ensure sustainable hydropower development and the biodiversity of fish populations. The locations of the entrances to these facilities play a key role in their efficiency. This study presents a reliable approach that combines the swimming ability of fish and a numerical flow field simulation to determine the optimal location for a fish passage facility entrance. In this study, we used the Gujun Reservoir upstream of the Yangtze River as a case study. A field experiment was conducted, and the swimming abilities of eight endemic fish species in the upstream region of the Yangtze River were measured. Among the tested species, the fastest induced swimming speed (0.14m/s) was achieved by Glyptothorax sinense, while the slowest critical swimming speed (0.30m/s) was observed for Paracobitis potanini. We propose that the velocity near the fish passage facility entrance should be higher than the maximum induced swimming speed and lower than the minimum critical swimming speed, making the suitable range between 0.14 and 0.30m/s. On this basis, velocity fields 500m downstream of the dam of the Gujun Reservoir under 4 operating conditions with discharge flows of 5.7 m3/s, 23.3 m3/s, 32.5 m3/s, and 41.1 m3/s were calculated. The results showed that the flow field variation downstream of the dam was between 0.1 and 0.9m/s. After comparing the suitable areas for the target species, the left bank at location 2 was recommended as the optimal location for the fish passage facility entrance in the Gujun Reservoir.

Spawning migration of Labeobarbus species of Lake Tana across the Gilgel Abay River Weir, Ethiopia: The challenges to fish spawning migration and proposed management solutions

AbstractLake Tana is one of the largest freshwater bodies in East Africa, with its 18 Labeobarbus species being the world's last remaining Cyprinid species flock. Many of them feed and grow in Lake Tana and migrate to the tributaries of the lake to reproduce. The construction of irrigation structures is increasing in the tributary rivers, however, without due attention being given to the spawning migration routes and critical spawning habitats. The present study examined the impacts of the Gilgel Abay Weir on the spawning migration of these species and discusses possible interactions with other human‐related impacts and potential mitigation measures. Fish samples were taken twice monthly from July to November 2019, both below and above the weir with gillnets. No spawning migration to the upstream of the weir has occurred since its construction, with the weir being a barrier to their spawning migration route of Lake Tana fisheries. Of the 11 species caught, only Labeobarbus intermedius (a habitat generalist) was observed above the weir, with the species diversity being significantly higher below the weir (p < 0.05) than above it. The total number of species observed during the present study was also lower, compared with previous reports. The fisheries impacts may also have been exacerbated by other contributing factors such as habitat destruction, river system degradation, destructive fishing practices and weed infestation, a situation which may lead to the collapse of Lake Tana fisheries and ultimately the lake's ecology. Reversing this situation is crucial, noting the implementation of such measures as habitat restoration and improvement, replacing the weir with environmentally friendly technologies, prohibition of illegal fishing, and construction of fish ladders could definitely alleviate the observed negative impacts of the Gilgel Abay Weir on the fisheries.

Are we any closer to understanding why fish can die after severe exercise?

AbstractPost‐exercise mortality (PEM) may occur when fish exercise to exhaustion and are pushed so far beyond their physiological limits that they can no longer sustain life. Although fish exercise to overcome a variety of natural challenges, the phenomenon of PEM is most often observed as the result of interactions between fish and humans. The seminal work of Black (Can J Fish Aquat Sci, 15:573, 1958) and Wood et al. (J Fish Biol, 22:189, 1983) provided a foundation for exploring the potential causes of PEM in fish. With no “silver bullet” explaining PEM being apparent, contemporary research has continued to focus on physiological mechanisms of exhaustion in fish, including factors such as oxygen delivery, ion regulation, hormone signalling, and cardiac function. This paper provides an overview of these studies, and reviews the continuous improvement in data collection methods, tools, and experimental protocols used to examine the PEM phenomenon. These studies of exhaustion have played an important role in informing management actions for activities such as bycatch revival and fish passage. Since the contribution of Wood et al. (Journal of Fish Biology, 22(2):189–201, 1983), the combined efforts of fundamental and applied research have yielded a greater understanding of why fish die after severe exercise, yet much remains to be explored through future work.

Poor downstream passage at a dam creates an ecological trap for migratory fish

Ecological traps can be caused when partial restoration leads organisms to make maladaptive habitat choices. One example of this is fishways (e.g., fish ladders) that provide upstream passage at dams but are not paired with adequate downstream passage. We tested the hypothesis that attracting anadromous fishes to spawn above a dam, but blocking downstream passage of their offspring leads to an ecological trap. Using passive integrated transponder (PIT) tags, we monitored the movements of steelhead ( Oncorhynchus mykiss) at a dam and fishway on the central California coast. We found that downstream passage for juveniles and kelts was limited by four factors: migration delay, loss in the reservoir, avoidance of the downstream bypass, and water depths on the spillway. Based on the spillway-passage depth thresholds, we estimated that the ability for fish to pass downstream was limited to only half of the migration season in 55% of the past 20 years (2002–2021). Our results support the ecological trap hypothesis, which may explain why restoration using fishways has failed to produce recovery gains in this population and elsewhere.

On the use of time coefficients of proper orthogonal decomposition for describing quasi-periodic flow processes in the highly turbulent flow of a fish pass

Flow velocity measurements using particle tracking velocimetry carried out in a scale model of a vertical-slot fish pass are analysed using proper orthogonal decomposition. Based on the analysis, the oscillating main stream and related time-varying processes are identified as dominant repeating flow processes. In particular, the time coefficients of the modes are examined in detail. Firstly, the cross-correlation functions of the time coefficients are used to identify the modes best representing this process. Secondly, the time series of coefficients themselves are used to identify the temporal occurrences of the repeating process even when the occurrences are neither identical nor periodical. The presented methodology reduces the examination of the full measured velocity dataset to an analysis of a limited number of coefficient time series, which can be used to detect the occurrences of flow processes repeating at irregular time intervals, and hence to describe their temporal evolution.

A scaled Denil fishway for upstream passage of Arctic Grayling

Denil fishways have been used with varying success to help fish pass impediments to upstream passage such as low head dams or irrigation diversion structures. They have been tested for hydraulic and fish passage performance in laboratory and field settings, usually with only minor modifications to the fishway geometry or dimensions. We tested a reduced (0.6) scale prototype of the standard-sized Denil fishway to determine if the smaller fishway, which requires less water flow, would successfully pass Arctic Grayling (Thymallus arcticus). The scaling factor was informed by analyzing previously published scalable Denil fishway rating equations. A prototype was tested in an open-channel flume using 8 treatments with 3 trials per treatment and 8 fish per trial. Each treatment had a prescribed combination of headwater and tailwater depths. Overall, 93% (178/191) of the fish volitionally entered the fishway and of these 91% (162/178) passed successfully. Entrance and passage were reduced only in treatments with the highest hydraulic slopes and highest water velocities at the downstream end of the fishway (i.e. with high headwater depths and low tailwater depths). The 0.6-scaled Denil fishway is likely a good alternative to standard-sized Denil fishways to enhance upstream mobility of Arctic Grayling in small, water-limited streams.

Modeled Streamflow Response to Scenarios of Tundra Lake Water Withdrawal and Seasonal Climate Extremes, Arctic Coastal Plain, Alaska

AbstractOn the Arctic Coastal Plain (ACP) in northern Alaska (USA), permafrost and abundant surface‐water storage define watershed hydrological processes. In the last decades, the ACP landscape experienced extreme climate events and increased lake water withdrawal (LWW) for infrastructure construction, primarily ice roads and industrial operations. However, their potential (combined) effects on streamflow are relatively underexplored. Here, we applied the process‐based, spatially distributed hydrological and thermal Water Balance Simulation Model (10 m spatial resolution) to the 30 km2 Crea Creek watershed located on the ACP. The impacts of documented seasonal climate extremes and LWW were evaluated on seasonal runoff (May–August), including minimum 7‐day mean flow (MQ7), the recovery time of MQ7 to pre‐perturbation conditions, and the duration of streamflow conditions that prevents fish passage. Low‐rainfall scenarios (21% of normal, one to three summers in a row) caused a larger reduction in MQ7 (−56% to −69%) than LWW alone (−44% to −58%). Decadal‐long consecutive LWW under average climate conditions resulted in a new equilibrium in low flow and seasonal runoff after 3 years that included a disconnected stream network, a reduced watershed contributing area (54% of total watershed area), and limited fish passage of 20 days (vs. 6 days under control conditions) throughout summer. Our results highlight that, even under current average climatic conditions, LWW is not offset by same‐year snowmelt as currently assumed in land management regulations. Effective land management would therefore benefit from considering the combined impact of climate change and industrial LWWs.

Test of a Screw-Style Fish Lift for Introducing Migratory Fish into a Selective Fish Passage Device

Barriers are an effective mechanism for managing invasive species, such as sea lamprey in the Laurentian Great Lakes but are detrimental because they limit the migration of desirable, native species. Fish passage technologies that selectively pass desirable species while blocking undesirable species are needed. Optical sorting tools, combined with newly developed computer learning algorithms, could be used to identify invasive species from high-resolution imagery and potentially isolate them from an assortment of the Great Lakes fishes. Many existing barriers lack fishways, and optical sorting may require fish to be dewatered for image capture. The Archimedes screw, a device originating from 234 BCE, offers the potential to continuously lift fish and water over low-head barriers or into an optical sorting device. To test the efficacy of an Archimedes screw and fish lifting to capture and pass Great Lakes fishes, we built a field-scale prototype and installed it at the Cheboygan Dam, Michigan in the USA in 2021. The fish lift safely transported 704 fish (688 of which were suckers (Catostomidae)) in 11 days. The passage of the suckers through the fish lift increased with the water temperature and attraction flow. There were no observed injuries in the transported fish or mortalities in a subset of suckers held post-transport.

When the Eel Meets Dams: Larger Dams’ Long-Term Impacts on Anguilla anguilla (L., 1758)

Diadromous fish, like the European eel Anguilla anguilla (L., 1758), are highly threatened by dams that disrupt river connectivity, consequently impeding fish movements to reach feeding and spawning habitats. In this study, variation in eel occurrence between a historical period (1940–1970) and recent data (2016–2020) was assessed throughout the Sardinian rivers’ network (more than 450 sites). Using Boosted Regression Trees (BRT) we investigated relationships between eel’s occurrence and a set of spatial and temporal environmental variables including a set of dams’ construction features for each period. An overall decrease by 65% of eel’s occurrence was noticed during the ca. 80-years period under scrutiny. Considering a subset (105 and 88 sites for the historical and the recent period, respectively) characterized by the presence of larger dams (height >15 m), eel’s occurrence dropped by 85%. Conversely, eel’s occurrence dropped only by ca. 44% in dam-free sites. During the historical period, eel’s occurrence was mostly affected by time since the initial habitat fragmentation, flow, distance to dams, connectivity, and dams’ height. In the most recent period, eel’s occurrence is mostly affected by dams’ building year, dam-to-sea distance, and, again, dams’ height. Results pinpoint that dams’ construction features and the time from their construction have significant negative effects on eel’s occurrence. Addition of future effective eel restoration practices, apart any other adverse environmental stressor, must consider dams’ removal, wherever socially sustainable or alternatively, the modification of construction features of dams (like excessive height) and the addition of fish ladders.

Restoring tribal priority fish passage through barrier removal (DOC)

Restoring tribal priority fish passage through barrier removal (DOC)

Analysis of Movements and Behavior of Bighead Carps (Hypophthalmichthys nobilis) Considering Fish Passage Energetics in an Experimental Vertical Slot Fishway.

Simple SummaryHydraulic structures have modified the natural waterways, and they have inevitably blocked fish migration routes and reduced fish habitat. To mitigate the impact on fish, fish passages have been developed as an effective way to restore riverine connectivity. The design of fish passage facilities refers to both hydrodynamics and fish behavior, and the information on the energetic expenditure of fish can be used to identify movement zones that are suitable for fish migration. Thus, this paper intended to identify fish movement behavior in response to water flow field information by means of estimating the energetic expenditure using an IBM approach. The results demonstrated that the fish required more energy in high TKE zones, and they were therefore likely to utilize the low TKE zones. This study provides a reference for optimizing the design of fish passages, and the method can be applied to assess the efficiency of fish passages and other fish bypass structures.An understanding of fish movement behavior in response to flow field variables is important for exploring the hydrodynamic strategies of fish in fish passages. In this paper, bighead carps were taken as an example. The fish movement behavior response to water flow field information by means of estimating the energetic expenditure using an IBM approach in an experimental fishway was investigated. Fish swimming velocity, drag force, and energy expenditure were analyzed in varied flow conditions related to hydraulic variables, including velocity (V), turbulent kinetic energy (TKE), and strain rate (SR). The result indicated that the fish will require more energy in high TKE zones. This study provides a reference for optimizing the design of fish passages and fisheries management. This method can be applied to assess the efficiency of fish bypass structures and conduct fish survival studies.

소하연문화(小河沿文化)와 주변지역의 장속 및 사회 현상의 비교 연구

The Xiaoheyan Culture, the Xueshan Phase I Culture and the Nanbaoligaotu Type, as three adjacently distributed Neolithic archaeological cultures, share similar ages and pottery characteristics, with excavated relics focusing on tombs. Based on the collation of the burial materials, this paper makes a transverse comparison of the burial customs and related social phenomena between the Xiaoheyan Culture and the two surrounding cultures. Through comparison, we find that the commonness between the Xiaoheyan Culture and the Nanbaoligaotu Type tombs is reflected in the abstract spiritual connotation, while the commonness between the Xiaoheyan Culture and the Xueshan Phase I Culture is mainly reflected in the material existence of the appearance seen in archaeological excavation. The commonness in these two aspects is related to the worship concept tradition and spiritual and cultural strength of the special way of fishing and hunting, the interactive dissemination of culture and the movement and migration of people.

小河沿文化和周邻文化的葬俗及相关社会现象的比较研究

The Xiaoheyan Culture, the Xueshan Phase I Culture and the Nanbaoligaotu Type, as three adjacently distributed Neolithic archaeological cultures, share similar ages and pottery characteristics, with excavated relics focusing on tombs. Based on the collation of the burial materials, this paper makes a transverse comparison of the burial customs and related social phenomena between the Xiaoheyan Culture and the two surrounding cultures. Through comparison, we find that the commonness between the Xiaoheyan Culture and the Nanbaoligaotu Type tombs is reflected in the abstract spiritual connotation, while the commonness between the Xiaoheyan Culture and the Xueshan Phase I Culture is mainly reflected in the material existence of the appearance seen in archaeological excavation. The commonness in these two aspects is related to the worship concept tradition and spiritual and cultural strength of the special way of fishing and hunting, the interactive dissemination of culture and the movement and migration of people.

Rivers under pressure: Interdisciplinary feasibility analysis of sustainable hydropower

AbstractGlobal biodiversity loss is most severe in freshwaters, particularly in river ecosystems. Hydropower is one of the main culprits. While being promoted as a carbon free source of renewable energy, hydropower disrupts the flow, habitats, and biota of rivers. Environmental policies and programs seek to mitigate the damage hydropower causes. Any policy action aiming at making the utilization of our rivers more sustainable must be ecologically, economically, and legally feasible. We show that the interdisciplinary feasibility of mitigation measures divides existing facilities into three categories (i) large facilities in which biodiversity mitigation measures are needed but electricity generation and balancing the electricity grid should remain as their main focus, (ii) small facilities in which dam removal and full scale river restoration measures can be taken by assisting the facilities to seize operations, preferably just before their next big investments, and (iii) medium facilities where benefits and trade‐offs associated with alternative paths should be analyzed case‐by‐case to determine the most feasible path forward. Policy action is feasible in all three categories but in different ways: requiring fish passes in the case of large facilities, helping remove dams and restoring the rivers in the case of small facilities, and focusing cost–benefit analysis efforts on the non‐trivial group of the medium sized facilities.

Combining Fish Passage and Sediment Bypassing: A Conceptual Solution for Increased Sustainability of Dams and Reservoirs

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, emerging as a major threat to species of migratory fish. In the past decades, mitigation measures aimed at reducing such environmental and technological impacts have been developed. Sediment bypass tunnels (SBTs) have been shown to successfully help prevent reservoir sedimentation, whereas fish passages have been found to be potential solutions to facilitate bi-directional passage of fish. However, the construction of such structures, in particular of SBT, can be extremely costly. The development of design solutions that can function both for downstream sediment transport and up- and downstream fish passage should be considered as they can mitigate ecological deficiencies of reservoir operations while accounting for economic feasibility. Possibilities and challenges of combining SBT and fish passage were explored by bringing together a team of interdisciplinary specialists on hydraulics, sediment transport and continuity, bypassing, hydraulic structures, hydropower engineering, aquatic biology, and fish passage in a two-day workshop. Here, we present potential solutions identified during the workshop for integrating SBT and fish passage.