Search

The migration corridors in regulated rivers lead downstream fish migrants, particularly juveniles to pass through water infrastructure. Accelerating flow, experienced by fish, might trigger avoidance behaviour and then influence the downstream migration efficacy. It is essential to understand the causes of avoidance behaviour exhibited by downstream migratory fish in accelerating flow. In this study, the effect of three different accelerating flows on the downstream migration behaviour of Schizopygopsis younghusbandi (S.Y) was investigated using a constriction wedge in a circulating flume. The results showed that some fish (30%, 23%, and 39% under low, medium, and high flow conditions, respectively) repeatedly attempted to burst upstream with positive rheotaxis prior to successful passage downstream. Under the low‐, medium‐, and high‐accelerating levels, the average fish swimming speeds were 89.19, 91.28, and 111.94 cm/s, respectively; these values were close to the critical swimming speed (110.42 cm/s) of the target fish. The water velocities at the fish avoidance points were centrally distributed at approximately 73.03 cm/s. Regarding turbulence, the results exhibited that the S.Y generally responded to a discrete range of <50 cm2/s2 of turbulent kinetic energy and < 2 N/m2 of the horizontal component of the Reynolds shear stress (RSSxy). Also, the fish that exhibited avoidance behaviour were not centrally distributed in the lateral and longitudinal velocity locations, where there was an abrupt change in the gradient. This study highlighted the impact of accelerating flow on the downstream fish migration behaviour of a cyprinid. Furthermore, this study quantified the hydraulic factors that triggered this avoidance. Thus, it provided experimental support for optimizing the design of the hydraulic factors for downstream fishways. [ABSTRACT FROM AUTHOR]

Highlights • Sturgeon population declines are largely due to human activities, especially the numerous dams with no effective fishways. • Knowledge about swimming performance in complex hydraulic conditions is needed to design effectively two-way fishways. • Ecohydraulic research on fishways are restricted by biological and methodological factors, especially for large species. • Swimming performance and fatigue, and single vs multiple variable models are needed to improve sturgeon fishways. Abstract The rapid decline in sturgeon populations is largely a result of human activities, especially the proliferation of hydraulic structures and lack of fish passage systems effective for sturgeon. This review highlights: (1) the importance of sturgeon conservation; (2) the need for data on swimming performance, including capability, metabolism and kinematics; (3) the relevance and limitations of swimming performance data in designing fish passage systems; (4) the need for experiments to develop sturgeon fishways that better reflect natural conditions. A proper understanding of swimming performance is crucial for designing effective fish passage systems. Although swimming performance and fish passage have been investigated for decades, knowledge and results have been limited by biological, methodological and analytical restrictions. To continue advancing passage effectiveness, continued research is necessary on sturgeon swimming performance and its interface with complex fishway hydraulics. [ABSTRACT FROM AUTHOR]

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, engineering) and from different continents (i.e., North and South America, Europe, Africa, Australia) identified knowledge gaps and provided a roadmap for research priorities and technical developments. Once dominated by an engineering-focused approach, fishway science today involves a wide range of disciplines from fish behaviour to socioeconomics to complex modelling of passage prioritization options in river networks. River barrier impacts on fish migration and dispersal are currently better understood than historically, but basic ecological knowledge underpinning the need for effective fish passage in many regions of the world, including in biodiversity hotspots (e.g., equatorial Africa, South-East Asia), remains largely unknown. Designing efficient fishways, with minimal passage delay and post-passage impacts, requires adaptive management and continued innovation. While the use of fishways in river restoration demands a transition towards fish passage at the community scale, advances in selective fishways are also needed to manage invasive fish colonization. Because of the erroneous view in some literature and communities of practice that fish passage is largely a proven technology, improved international collaboration, information sharing, method standardization and multidisciplinary training are needed. Further development of regional expertise is needed in South America, Asia and Africa where hydropower dams are currently being planned and constructed. [ABSTRACT FROM AUTHOR]

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 still limited. We examined swimming behaviour and activity of silver redhorse (Moxostoma anisurum) during its upriver spawning migration in a vertical slot fishway. We used an accelerometer-derived instantaneous activity metric (overall dynamic body acceleration) to estimate location-specific swimming activity. Silver redhorse demonstrated progressive increases in activity during upstream fishway passage. Moreover, location-specific passage duration decreased with an increasing number of passage attempts. Turning basins and the most upstream basin were found to delay fish passage. No relationship was found between basin-specific passage duration and activity and the respective values from previous basins. The results demonstrate that successful fishway passage requires periods of high activity. The resultant energetic expenditure may affect fitness, foraging behaviour and increase susceptibility to predation, compromising population sustainability. This study highlights the need to understand the physiological mechanisms underpinning fishway passage to improve future designs and interpretation of biological evaluations. [ABSTRACT FROM AUTHOR]

The disruption of river connectivity through the construction of barriers used for hydropower development and water control purposes can severely damage river ecosystems, reduce the quality of fish habitat, and prevent the upstream migration of fishes. Fishways function as a means of passage around barriers for fish migrating both upstream and downstream. In 2009, the CanFishPass project was initiated in a partnership with Fisheries and Oceans Canada and Carleton University to create a searchable database containing specific information on fishways in Canada built to enable upstream passage. In this paper we evaluate the information gathered in the CanFishPass database to identify trends concerning fishways and fish passage in Canada, yielding, we believe, the first national-scale trend analysis related to fishways anywhere in the world. Although CanFishPass may not include all fishways in Canada, our analysis identified 211 which are primarily located along the coasts and along major rivers and water bodies such as the Great Lakes. British Columbia has the largest number of fishways in Canada (62) and Prince Edward Island has the fewest (2). The most popular type of fishway is the pool and weir fishway (85), followed by vertical slot (37) and Denil type fishways (23). Fishway construction has proceeded at a steady rate since the 1970's, although there has been an increase in the number of nature-like fishways since the year 2000. The majority of fishways are installed to pass salmonids in Canada, although some fishways on warmwater systems pass large components of the fish community. Only 9 % of the fishways in Canada have been studied using methods that enable proper evaluation of biological effectiveness. We recommend that evaluations be carried out at new and existing fishways and that these evaluations enable the determination of attraction and passage efficiency. Additionally, we recommend that future fishway projects and evaluations in Canada be advised to submit details of their work to CanFishPass so that knowledge of these fishways is centralized. Similar efforts on a global scale could lead to opportunities to identify patterns in fishway design and biological effectiveness that would ultimately inform decision making and improve connectivity where deemed necessary. [ABSTRACT FROM AUTHOR]

Abstract: For centuries, humankind has constructed dams on rivers to control flooding, provide for irrigation and utilize potential energy for power, but generally dams had no or little provision for fish passage. Thus, they often blocked or impeded fish migrations. Empirical observations and “trial and error” approaches that characterized historical efforts to develop passage systems for upstream migrating fish often did not work. The first concerted efforts to develop scientifically based fishways for upstream migrant fish began in the early 1900s in Europe with field and laboratory testing of different fishway designs. These were followed by extensive efforts beginning in the 1940s in North America. Scientifically based testing of configurations for fishways for downstream migrant fish began in the 1950s. Nearly all early efforts were directed at salmonid species, with smaller efforts on shad. Recent species at risk legislation in the U.S.A., Canada, and Europe places renewed emphasis on fish passage for all migratory species, and efforts have also begun to develop successful passage strategies for migratory species in other countries worldwide. This has led to renewed efforts to develop effective passage systems and to try creative solutions using natural materials in addition to concrete or metal used in standard technical fishways. Regardless of the type of structures built, history has shown that the most effective means to develop successful installations has occurred when engineers and biologists worked together systematically to design passage structures based on the ability and willingness of fish to seek and accept the hydraulic conditions presented to them. [Copyright &y& Elsevier]

Copyright of Canadian Water Resources Journal / Revue Canadienne des Ressources Hydriques is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: The construction of pool-type fishways has greatly increased in recent years in response to widespread river fragmentation by man-made structures. However, the performance of such facilities has often been questioned, particularly for non-salmonid fish fauna, which are frequently the predominant group of species found in rivers. This study presents the main findings from field and experimental research conducted over the last 10years on pool-type fishways in Portugal. Specific goals were: (i) to catalogue and evaluate the effectiveness of pool-type fishways built at small hydropower plants (SHP); (ii) to assess passage patterns of migrant fish populations through a “highly suitable” facility; (iii) to assess fish use for submerged orifices and surface notches under different flow regimes in experimental conditions and (iv) to determine the effect of hydraulic parameters on upstream movements of fish within these fishways. More than half (n =19, 51%) of the visited fishways were considered to be unsuitable for the target potamodromous species. Seasonal movements peaked in the spring (>70%) and occurred independently of time of day. Laboratory experiments showed a significantly greater proportion of movements occurring through submerged orifices rather than surface notches. Of all the analyzed hydraulic parameters, the Reynolds shear stress was the one that most influenced fish movements within the fishways investigated. The results of this study provide new information and insights that could have important implications on the design of future fishways, particularly for larger potamodromous cyprinids. [Copyright &y& Elsevier]

Turbulent flows are investigated in the bypass of a bar rack system to understand the effects of weirs placed at the bypass entrance on hydraulic conditions used to guide fish moving downstream. Three test cases were studied: (a) no weir (reference case), (b) arc-shaped weir and (c) triangular weir. A stereo particle image velocimetry system was employed to acquire the three velocity components in the mid-plane of the bypass and examine various statistics including mean velocities, Reynolds stresses, turbulent kinetic energy as well as turbulence eddies and swirling strength. The weirs deflect the flow away from the channel bed due to the blockage effect and increase the bypass velocity significantly, though remains under the suggested critical value of 1 m s−1 when the approach velocity was 0.38 m s−1. In the wake region of the triangular weir, a distinct recirculation bubble forms which may negatively affect fish migration. There is an increase in the level of Reynolds stresses and turbulent kinetic energy in the upstream vicinity of the weirs and the shear layers issuing from their tips. It is shown that the topology of the turbulence eddies is greatly modified by the weirs which can more readily assist fish guidance toward the bypass. Also, the swirling strength of the turbulence eddies behind the triangular weir is more pronounced compared to the arc-shaped weir. For the reference case, the swirling strength of the eddies is the weakest. • Effects of weirs at bypass entrance of bar rack systems on fish guidance effectiveness and swimming behavior are studied. • Key variables including velocities, spatial acceleration, Reynolds stresses, TKE as well as turbulence eddies are examined. • Mean velocities, spatial acceleration, Reynolds stresses and TKE enhanced significantly with the insertion of weirs. • Turbulence eddies are modified substantially around the weirs which helps fish pass downstream more readily. [ABSTRACT FROM AUTHOR]

This paper presents an overall assessment of the hydraulics of a vertical slot fishway, the Vianney-Legendre vertical slot fishway on the Richelieu River in Quebec, Canada, which has been shown to be successful for passing a variety of fish species, including lake sturgeon. The fishway has a number of features that combine for a unique design. This includes two turning pools, shorter and narrower than recommended regular pools, and a low overall gradient. Detailed field measurements of the water levels and velocity patterns were obtained and a computational fluid dynamics modeling study was conducted. The model study evaluates the performance of various regular pool geometries based on fishway hydrodynamics. Low overall fishway gradient was shown to result in a fishway hydraulically suitable to fish passage, overcoming non-optimal pool dimensions. The relationship between discharge and corresponding average water depth in the pools, under both uniform and non-uniform flow conditions, using the discharge coefficient enabled us to simulate the distribution of water levels in a vertical slot fishway. Two distinct flow patterns were observed in a regular pool depending on the shape ratios between the pool's length and width. This study also assessed the spatial variation of velocity magnitude in the vertical plane to reveal regions of upwelling, downwelling, and the formation of eddies and dead flow zones that have potential importance for fish migration. [ABSTRACT FROM AUTHOR]

Experiments were performed in a novel pool & weir fishway to study the relationship between hydrodynamic and physiological parameters using rainbow trout (Oncorhynchus mykiss; mean TL = 15 cm). Fish were tested randomly using three fishway slopes (4, 7 and 10%) and three spacing ratios of W shaped weirs. Effect on fish hematology, immunology and stress were examined. Results showed that changing fishway hydraulic conditions altered fish stress levels. Increasing fishway slope and decreasing weir spacing, resulted in increased number of red blood cells and hematocrit, and decreased white blood cell count and serum lysosomes. In addition, levels of the most important stress indicator, cortisol, were elevated significantly compared to the control group, as slope, and consequently turbulence levels increased. Results showed that maximum turbulent kinetic energy (TKE) for a 10% fishway slope was increased to 0.22 m2/s2 while for a 4% slope and larger weir spacing was reduced to 0.05 m2/s2 which is the best condition for fish to rest in the pools created between the weirs. Observations on turbulence metrics showed that a weir spacing ratio of 6 offered the lowest gradients of energy changes. Furthermore, increasing the spacing ratio from 2 to 6 reduced cortisol levels and generally improved the physiological status of fish in the fishway. Considering turbulence levels at different depths of flow, the study concluded that physiological conditions for the passage of rainbow trout were best for a spacing ratio of 6 and a fishway slope of 4%. The evaluation of physiological metrics proved to be a vital and reliable process to integrate with hydrodynamics so fishway designs may be optimized to avoid stressing fish, and to enhance survival opportunities for migrating populations. • Physiological and hydrodynamic assessment of a novel fishway. • Slope, weir spacing, and flow turbulence affect fish passage. • Fish stress is associated with limits to turbulent flow metrics and key fishway design parameters. • Developed a physiological basis for improving fish migration solutions. [ABSTRACT FROM AUTHOR]