拦鱼电栅设计中的几个电学问题

本文从鱼的行为特性和拦鱼电场特性讨论了电栅拦鱼成败的主要原因.分析了拦鱼电栅设计中电(工)学参量不同计算方法的内涵及实质、拦鱼电场位场量(电场强度矢量、电位等)的表示方法以及它们对电栅拦鱼效果的影响.     

关于计算单排分压式拦鱼电栅电学参量的数学模型

对目前用于计算单排分压式拦鱼电栅电学参量（电流，电位，电位梯度或电场强度等）的等效电路法，电磁场理论法和镜像法理论和实践上进行了对比分析研究，认为在不同环境条件下应采用相应的方法，澄清了某些有关单排分压式拦鱼电栅设计方法方面的模糊概念，同时还从脉冲在器匹配选用等方面分析了上述方法的便利性，是正确设计和使用单排分压式拦电电栅的前提，具有实用价值。     

关于电拦设计中的几个计算问题——与《电栅数模》的作者商榷

对《水利渔业》１９９４年第２期中《关于计算单排分压式拦鱼电栅电学参量的数学模型》一文中的单位、镜像法、拦鱼效果等问题提出我们的看法与作者商榷     

溢洪道拦鱼电栅拦阻效率影响因素的探讨

1966年，在浙江省杨梅岭水库建成的我国第一座生产试验性的交流电拦鱼电栅，至今已成功地使用了十余年。近年来，在其基础上，又建造了脉冲电拦鱼电栅，它耗电量很少，使用单位更乐于接受。通过这些年的实践，对影响溢洪道拦顺水鱼的拦阻效率有那些主要因素，以及如何尽可能地提高拦阻效率，有了一定的了解。这些对改善电栅的设计和使用有一定的益处，现整理出来，供有关同志参考。     

拦鱼电栅阻抗的理论计算

拦鱼电栅是由若干个栅子(指单根电极，以下类同)组成。故在进行拦鱼电栅的阻抗计算时，应充分注意到栅子与栅子之间相互作用的存在。特别是当栅子数比较多的情况下，同时考虑一栅子对另一栅子的反映阻抗的贡献，将有助于拦鱼电栅的理论计算和设计精度。当然，栅子阻抗亦可以用实验的方法直接测得，这种实测方法的采用，实质上是避开了由于栅子与栅子之间存在着相互间的影响，     

水库溢洪道单排分压式拦鱼电栅电流场的物理模型

本文考虑了拦鱼电栅全部电极间的相互影响,从理论上提出了拦鱼电栅电流场的物理模型,给出了电流、电势、电场强度、功率的计算公式,为进行计算机辅助设计提供了理论依据.文章还指出了现行溢洪道拦鱼电栅存在的问题,提出了拦鱼电栅的设计原则.     

悬挂式拦鱼电栅的结构及应用

本文联系江西省江口水库拦鱼电栅的实际,介绍了悬挂式拦鱼电栅的结构和各构件的受力情况及其作用,提出了悬挂式拦鱼电栅合理的施工程序及注意事项。     

大型水库拦鱼电栅研制成功

十年前,上海水产大学钟为国副教授等在福建首先研制成了中小型水库脉冲拦鱼电栅,这项技术,已在20多个省(区)100多座中小型水库养鱼上得到推广应用。1984年起,他们又承担了水电部下达的“六五”科技攻关课题,开展了大型脉冲发生器研制、     

分压式拦鱼电栅电场计算机模拟

本文根据分压式拦鱼电栅工作原理,建立了电栅电场强度和电位数学模型,并利用计算机技术,完成电栅电场位场量的计算和等值等位线图的绘制,是分析电栅电场的重要依提,也是拦鱼电栅设计的基础。     

DUX-1型电渔法脉冲发生器

为了探讨脉冲电在电渔法中的应用技术，我们在1976年就研制成功“DUX-1型电渔法脉冲发生器”，作为脉冲源在电渔法中试用。近几年，在几个水库拦鱼电栅中试用，都取得了较好的拦鱼效果。它具有适用范围广、耗电省、成本低、机组轻便等优点，是一种较为理想的电捕渔具。     

不同位置和朝向的鱼道进口诱鱼效果

为了探明不同进口朝向的布置方式和进口位置对诱鱼效果的影响，本研究通过建立鱼道进口概化模型，设计3种环境流速工况，以马口鱼为实验对象，针对不同朝向和不同位置鱼道进口分别进行放鱼实验。结果显示，在同一鱼道进口位置时，垂直于河道水流方向上的鱼道进口其诱鱼效果明显优于顺河道水流方向的鱼道进口；当开启与电站不同相对位置不同的进口时，其诱鱼效果受河道水流速度和进口位置的影响较为显著；在所设计实验工况中，环境流速为0.3 m/s时，鱼道进口诱鱼效果最好。研究结果将对水利工程中鱼道进口布置具有重要的参考意义并指导工程实践。     

障碍物对鲢幼鱼游泳动力学的影响

为了解鱼在复杂水流环境中的运动行为,提升鱼道过鱼效果,实验通过在水槽中放置障碍物,分析不同来流速度(1,3和5 BL/s)(BL/s即体长每秒)下鲢幼鱼顶流静止和顶流前进时的游泳动力学表现,提取的游泳动力学指标有摆尾频率、摆尾幅度、对地游泳速度、游泳加速度和运动步长。结果发现,半流速度1 BL/s下,与自由来流相比,鲢幼鱼在障碍物后方顶流静止时,摆尾频率降低,摆尾幅度增加;顶流前进时,摆尾频率、对地游泳速度、游泳加速度和运动步长降低,摆尾幅度增加。半流速度3 BL/s下,障碍物有助于节省鱼类运动能量的消耗。在有障碍物的水流中,顶流静止时的摆尾频率随流速的增加而增加;顶流前进时,摆尾频率、摆尾幅度和游泳加速度随流速增大而增大,而运动步长随流速增大而减小。位置偏好研究表明,当流速为3 BL/s时,鲢幼鱼明显集中在距离障碍物后方约5～30 cm处游动,停留时间占比达92.5%,可能采用了卡门步态的运动模式;当流速为1和5 BL/s时,鲢幼鱼没有表现出非常明显的位置偏好;在自由来流中,鲢常贴壁游泳,亦没有明显的位置偏好,表明障碍物和流速的结合可为鱼类提供水流藏匿场,研究结果为鱼道设计提供重要参考依据。     

Remediation of upstream passage for migrating Galaxias (Family: Galaxiidae) through a pipe culvert

Movement through streams is critical for the maintenance of diadromous fish populations. Numerous fish passage improvement techniques exist, and knowledge of their effectiveness is required to conserve target species. An existing 70‐m pipe culvert was considered a barrier to the passage success of young‐of‐year (YOY) Galaxias spp. as a result of high water velocity (0.9 m/s). Water velocity in the pipe culvert was reduced by installing a concrete weir downstream of the culvert. A lateral ridge rock‐ramp fishway was installed to provide for the passage of fish over the weir, and baffles were installed in the upstream portion of the culvert to provide refuge from higher water velocity at this location. A BACI design was used to determine whether passage success, measured using a mark–recapture technique, improved as a result of the remediation works. The probability of successful passage of YOY Galaxias spp. through the culvert increased from 0.03 to 0.41 following remediation works and was similar to levels observed at a control site (0.33). The success of the fishway and baffles at this culvert provides an important case study for managers to adopt this technique to improve fish passage on a broader scale and range of other sites.     

A quantitative assessment of fish passage efficiency

In an attempt to restore the connectivity of fragmented river habitats, a variety of passage facilities have been installed at river barriers. Despite the cost of building these structures, there has been no quantitative evaluation of their overall success at restoring fish passage. We reviewed articles from 1960 to 2011, extracted data from 65 papers on fish passage efficiency, size and species of fish, and fishway characteristics to determine the best predictors of fishway efficiency. Because data were scarce for fishes other than salmonids (order Salmoniformes), we combined data for all non‐salmonids for our analysis. On average, downstream passage efficiency was 68.5%, slightly higher than upstream passage efficiency of 41.7%, and neither differed across the geographical regions of study. Salmonids were more successful than non‐salmonids in passing upstream (61.7 vs. 21.1%) and downstream (74.6 vs. 39.6%) through fish passage facilities. Passage efficiency differed significantly between types of fishways; pool and weir, pool and slot and natural fishways had the highest efficiencies, whereas Denil and fish locks/elevators had the lowest. Upstream passage efficiency decreased significantly with fishway slope, but increased with fishway length, and water velocity. An information‐theoretic analysis indicated that the best predictors of fish passage efficiency were order of fish (i.e. salmonids > non‐salmonids), type of fishway and length of fishway. Overall, the low efficiency of passage facilities indicated that most need to be improved to sufficiently mitigate habitat fragmentation for the complete fish community across a range of environmental conditions.     

Fishway entrance modifications enhance fish attraction

Two Denil fishways on the Grand River, Ontario, were monitored annually since 1994 for activity by several dozen fish species. Fishway entrances were enlarged and repositioned approximately 2 m closer to the weir face, in areas where fish were attracted by weir discharge. These simple modifications resulted in increased attraction efficiency for pumpkinseed, Lepomis gibbosus (L.). After modifications, annual relative rate of recapture was 39% (95% confidence interval [CI]=32–46%), representing a 2.6–3-fold increase in fishway use relative to pre-modification conditions. Median daily recapture rates also increased significantly from 0% at both fishways to approximately 2%. These results suggest that fishway entrances should be located as close to a dam or weir face as possible, but velocity barriers from spillway or tailrace discharge must not compromise access.     

Fishway with two entrance branches: Understanding its performance for potamodromous Mediterranean barbels

Many fish passes have been built across the world in recent years. This study analyses the performance of a modified type of pool and weir fishway with two access branches, using passive integrated transponder telemetry. A circum‐Mediterranean barbel, Luciobarbus bocagei (Steindachner, 1864), was chosen as the target species. Both hydraulic values (flow and volumetric energy dissipation) and biological parameters (attraction, entrance and passage success) were measured in the fishway, these being related to the environmental variables affecting upstream fish movement. Flow discharge, water temperature and atmospheric pressure were important for fish entering the fishway. There was no preference between path routes, even though the main discharge was concentrated in the turbine channel. This type of fishway design could be an alternative for the conservation of fish populations where multiple fish approach options are possible.     

Upstream passage of fish through a vertical-slot fishway in an Australian subtropical river

The effectiveness of a vertical-slot fishway on the Burnett River barrage for facilitating migration of fish was assessed. In 100 samples taken at the top and bottom of the fishway, over 52 000 fish representing 34 species were collected at a maximum rate of 4500 fish per day. In contrast, less than 2000 fish ascended the original pool-and-weir fishway in 128, 24 h samples at the top between 1984 and 1987. Juvenile size classes dominated the abundance of many species in the present study and fish between 24 and 930 mm in length ascended the vertical-slot fishway. However, passage of small fish was restricted and for new fishways on tidal barriers a further reduction in head loss between pools is recommended. Importantly, the width of the vertical-slots was too small for effective upstream passage of large Queensland lungfish, Neoceratodus forsteri (Krefft). The greatest diversity of fish species was found during low river flows. The findings suggest that vertical-slot fishways with wide pools and low turbulence pass a diverse range of fish fauna present in subtropical coastal rivers.     

Denil fishway utilization patterns and passage of several warmwater species relative to seasonal, thermal and hydraulic dynamics

Abstract – Two different Denil fishways on the Grand River, Ontario, were used as check-points to evaluate the upstream movement of fishes past a low-head weir and to examine the proportions and inferred swimming performance of non-salmonid warmwater fishes that used each fishway type. Traps installed at fishway exits were used to collect fish during 24-hour sampling periods, over 40–51 days each year, from 1995 to 1997. Passage rates, size selectivity, water temperature, water velocity and turbidity for the periods of maximum passage for each year were examined. General species composition from trap samples shifted from catostomids to cyprinids to ictalurids to percids and centrarchids, with some overlap, as water temperatures increased from 8 °C to 25 °C in the spring and early summer. Water depths, and therefore water velocities in each fishway, were independent of river discharge due to variable accumulations of debris on upstream trash-racks. Relationships between the water velocity and the swimming and position-holding abilities of several species emerged. Turbidity was directly related to river discharge and precipitation events, and many species demonstrated maximum fishway use during periods of increased turbidity. This study 1) provided evidence of strongly directional upstream movements among several species that were previously considered non-migratory and 2) describes physical and hydraulic conditions during fishway use for 29 non-salmonid fish species.     

Effects of water velocity,turbulence and obstacle length on the swimming capabilities of adult Pacific lamprey

The swimming capabilities of adult Pacific lamprey, Entosphenus tridentatus Gairdner, were tested in an experimental vertical‐slot fishway in response to three different fishway features: water velocity (1.2, 1.8 and 2.4 m s^?1), the length of the vertical slot (0.33, 0.66, 1.00 m) and during the presence/absence of a turbulence‐intensifying structure that increased turbulence for each respective treatment. Passage success was lowest (52.7%) and attachment rates were highest (92.9%) during the most difficult passage conditions (high velocity, high turbulence, long slot length). Passage success was >83% for all other treatment combinations. Although passage of the vertical‐slot weir was not associated with fish body size, Pacific lamprey with larger dorsal distances (distance between the two dorsal fins) were more likely to pass the vertical‐slot weir. Increased attachment rates and longer attachment times during strenuous passage conditions suggest that endurance capacity may be an important factor limiting the passage of Pacific lamprey at fishway obstacles.     

Atlantic salmon, Salmo salar L., and sea trout, Salmo trutta L., passage in a regulated northern river – fishway efficiency, fish entrance and environmental factors

The number and the size of Atlantic salmon, Salmo salar L., using the Isohaara fishway was elevated by increasing the fishway discharge and by changing the type of the pass entrance. The fishway is intended to help fish bypass a hydroelectric station located close to the mouth of the large, regulated River Kemijoki, in northern Finland. Multi-sea-winter (MSW) salmon returned to the river mouth during peak flows in early June but did not use the fishway until 1 month later. Their number in the fishway was positively correlated with the tailwater level. One-sea winter (1-SW) salmon, which arrived approximately one month later, started to enter the fishway without corresponding delays. In autumn, a high tailwater level and a small drop at the fish entrance seemed to be needed for the successful passage of these small-sized salmon and sea trout, Salmo trutta L.