Christos Katopodis

Developing a toolkit for fish passage, ecological flow management and fish habitat works

Fish passage, including fishways and fish screens, ecological flow management for open or ice-covered waters and fish habitat works, such as stream rehabilitation, habitat replacement, erosion and sediment management, are the subject of increased interest worldwide. Research and development in these areas, establishing a foundation of sound science and innovative engineering, has intensified, as a result of widespread recognition of the importance of sustainable and environmentally acceptable use of water resources. Scientific and engineering studies, along with technological advancements have allowed the development of a range of methods and tools for assessing the feasibility of and for providing guidance in seeking effective solutions. Methods and tools range from fairly simple to fairly sophisticated, from long-life rigid structures to adjustable ones, and solutions that are applicable at a variety of projects, scales, site conditions, fish species, aquatic biota, data sources and economic circumstances. A set of tools and methods is presented, which together form a toolkit under development. Each tool is at a different stage of advancement and the process of development is outlined. The toolkit includes analytical methods for relating fish migration timing to hydrographs, ways of attracting and guiding fish to fishways, analysis of fishway hydraulics and fish passage abilities, fish screen hydraulics and fish responses, nature-mimicking fish habitat structures, hydrodynamic and habitat simulation, and the initial stages of considering sediment and ice processes. Suggestions are made for further research and development in these interdisciplinary areas, which challenge interested researchers to focus their individual studies on fish passage, habitat and ecological issues and improve available tools.

Measurement of burst swimming performance in wild Atlantic salmon (Salmo salar L.) using digital telemetry

Swimming performance of wild Atlantic salmon (Salmo salar L.) was investigated in an experimental flume using coded radio signals. To calculate swimming speed, distance moved and time elapsed were measured with a digital spectrum processor using near real-time spectrum analysis. This device was designed to be used in a coprocessing arrangement with a receiver, thereby providing pulse position code discrimination, verification and continuous data storage. Radio-tagged adults (48.3 to 54.8 cm long) voluntarily swam against water velocities, ranging from 1.32 to 2.85 m s−1, in an 18 m long flume at a mean water temperature of 10.1±1.6°C. At water velocities of 1.32–1.55 m s−1, individuals successfully ascended the flume at swimming speeds of 1.61–2.55 m s−1, or 3.30–4.79 body lengths per second (l s−1), respectively. At high water velocities ranging from 1.92 to 2.85 m s−1, individual swimming speeds increased from 2.55 to 3.60 m s−1, or 4.94–7.27 l s−1, respectively. However, above a threshold value of 1.92 m s−1, individuals traversed shorter distances and were unable to ascend the flume. The highest swimming speed observed was 4.13 m s−1, or 8.35 l s−1. The results of this study indicate that in addition to its applicability in the determination of burst swimming speeds, digital telemetry could prove a useful tool in the design and evaluation of future fishways and culvert installations.

Pool-type fishways: two different morpho-ecological cyprinid species facing plunging and streaming flows.

Fish are particularly sensitive to connectivity loss as their ability to reach spawning grounds is seriously affected. The most common way to circumvent a barrier to longitudinal connectivity, and to mitigate its impacts, is to implement a fish passage device. However, these structures are often non-effective for species with different morphological and ecological characteristics so there is a need to determine optimum dimensioning values and hydraulic parameters. The aim of this work is to study the behaviour and performance of two species with different ecological characteristics (Iberian barbel Luciobarbus bocagei–bottom oriented, and Iberian chub Squalius pyrenaicus–water column) in a full-scale experimental pool-type fishway that offers two different flow regimes–plunging and streaming. Results showed that both species passed through the surface notch more readily during streaming flow than during plunging flow. The surface oriented species used the surface notch more readily in streaming flow, and both species were more successful in moving upstream in streaming flow than in plunging flow. Streaming flow enhances upstream movement of both species, and seems the most suitable for fishways in river systems where a wide range of fish morpho-ecological traits are found.

Behaviour and Locomotor Activity of a Migratory Catostomid during Fishway Passage

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.

Oscillating vertical plane turbulent jet in shallow water

The results of a laboratory investigation on the behaviour of plane turbulent jets discharging vertically upwards into a stagnant shallow water body have shown that for any depth H in terms of the half width b 0 of the nozzle, the jet could be in an oscillating mode if the velocity at the nozzle U 0 is greater than a critical value of [0.009(Hlb 0) + 0.357] √gH where g is the acceleration due to gravity. When the jet is oscillating, the frequency of oscillation ƒ is equal to 0.18 √g/H. An earlier study on vertical circular jets in shallow water did not find such an oscillating flow pattern.

Effect of flow regime hydraulics on passage performance of Iberian chub (Squalius pyrenaicus) (Günther, 1868) in an experimental pool-and-weir fishway

Dams and weirs strongly affect or interrupt the longitudinal connectivity of rivers, by limiting the movements of several fish species while altering and fragmenting habitats. Fishways, especially pool-type fishways, are used to diminish this impact by enabling fish to negotiate barriers. The aim of this work is to study the behaviour of a small-sized resident cyprinid fish, the Iberian chub—Squalius pyrenaicus (Günther, 1868)—within a prototype of a pool-type fishway, equipped with both surface notches and bottom orifices, and experiencing two different flow regimes, plunging and streaming. Results show that the fish tended to be more successful in their upstream movements under streaming flow and that, for this regime, the surface notch was the preferred route for upstream movements. Flow velocity patterns corroborated the results, showing that the plunging flow regime may have driven fish downstream, while the streaming flow regime may have attracted fish upstream. The plunging flow also prevented access of this surface-oriented species to the surface notch, effectively reducing the area available for transport. Thus, the streaming flow regime can be a sound option for this and other small-sized species, as it enhances fish movements through the fishway.

Verification of a Numerical Model for the Prediction of Low Slope Vertical Slot Fishway Hydraulics

Abstract A numerical model has been developed to predict the three-dimensional flow character within low slope vertical slot fishways (VSFs). The model solves the three dimensional Reynolds averaged Navier-Stokes equations, closed with the renormalised k-ॉ turbulence formulations. The model employs the volume of fluid method to deal with the free surface. Results are presented for velocities and surface elevations utilising two fishway designs from prototype and laboratory studies. The respective data from these studies are directly compared to the numerical model predictions forming the basis of verification. The model is shown to predict critical design velocities, slot flow characteristics, flow recirculation and water surface elevations well enough to be useful in low slope VSF design.

Open-channel turbulent flow through bar racks

ABSTRACT The paper reports on an experimental study of turbulent open-channel flow near small-scale and large-scale bar rack models. The experiments were conducted for a wide range of bar depth, bar shape, bar spacing and bar inclination to the approach flow. The contours of the mean velocity near the small-scale models revealed that bar inclination produced asymmetric flow, a potential threat for vibration failure. The reconstructed fluctuating velocity fields obtained from proper orthogonal decomposition revealed strong organization of vortical structure downstream of the aligned bars compared to the inclined bars. The head loss coefficient generally increased monotonically with blockage ratio and bar inclination. Significant reduction in head losses was observed when square leading edges of rectangular bars are replaced by round leading edges, or if streamlined profile cross-section bars were used instead of rectangular bars.

Development of a National Fish Passage Database for Canada (CanFishPass): Rationale, Approach, Utility, and Potential Applicability to Other Regions

Barriers resulting from anthropogenic activities (e.g., hydropower development, irrigation, flood control, low flow augmentation) can prevent the upstream migration of fish, reducing the connectivity of river systems. As a result, great efforts have been devoted to the design and installation of engineered fishways to enable the movement of fishes across barriers. However, the literature is generally devoid of scientific papers dealing with fishway design and effectiveness, making it difficult for those developing such facilities to determine which fishway designs are most appropriate for a given system and target species. One approach for providing information to support future fishway development is through the creation of databases that contain detailed accounts of existing facilities. Described here is the development of an engineered fishway database in Canada (called CanFishPass) intended to serve as a repository for information that has previously been difficult to find. The database includes detailed geo-referenced information such as engineering details, hydraulic characteristics, and biological effectiveness of one general class of fish passage facility (i.e., engineered fishways), as well as photographs and design drawings where available. The database is searchable by species, fishway type, and ecozone, and includes a reference section comprised of both peer-reviewed and grey literature. It is anticipated that the database will serve as an important resource for future fishway development projects enabling quantitative analyses, while also serving as the first inventory of engineered fishways in Canada. Although our efforts to date have been focused on Canada, the expansion to a global inventory of fishways would enable opportunities to learn directly from facility operations in other regions.

Entrance region of circular pipes flowing partly full

This paper presents the results of an experimental study on the characteristics of flow in the entrance region of a circular pipe flowing partly full for slopes of 1, 3 and 5%. An analysis of the w...