Climbing success of adult Pacific lamprey on a vertical wetted wall

The ability of adult Pacific lamprey, Entosphenus tridentatus (Gairdner), to climb has enabled development of lamprey‐specific fishways. Sheer vertical climbing elements are needed for these structures when fishway installation space is limited. A 1.6‐m high aluminium wetted wall was built to test Pacific lamprey vertical climbing in relation to flow and three water delivery mechanisms: overflow, upwelling and sidewelling. Passage success and passage times were recorded for individual Pacific lamprey (n = 122). For those that interacted with the structure (n = 104), 94% successfully ascended the wall (76% on their first attempt). Average time from first interaction with the structure to exit ranged from 19.5 to 47.0 min. Success rates and passage times were not significantly affected by flow or water delivery treatments. This indicates that vertical elements can facilitate lamprey passage in the 0.13–3.59 L min^?1 cm^?1 flow range tested and may greatly expand the design alternatives in certain situations.     

Behaviour of adult Pacific lamprey in near‐field flow and fishway design experiments

Abstract An experimental fishway was used to examine adult Pacific lamprey, Lampetra tridentata (Gairdner), behaviour in a series of attraction and passage‐performance tests. Among all experiments, lamprey oriented to the fishway floor and walls and were attracted to both ambient and concentrated flow. When confronted with high‐velocity areas (vertical‐slot and submerged‐orifice weirs), many lamprey failed to pass upstream. However, lamprey were able to find and take advantage of low‐velocity refuges when they were provided. Lamprey climbed shallow‐ and steep‐angled ramps when attraction cues were sufficient and other passage routes were restricted. The combined results demonstrated the passage challenges that fishways designed and operated for salmonids present to non‐salmonid species. They also highlight the importance of evaluating trade‐offs between fishway attraction and passage efficiency. The experiments were integrated with tagging studies and development of lamprey‐specific passage structures, a research combination that provided an effective template for fishway performance evaluations.     

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.     

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.     

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.     

Factors affecting dam passage and upstream distribution of adult Pacific lamprey in the interior Columbia River basin

Low dam passage rates of adult Pacific lamprey (Entosphenus tridentatus) during upstream spawning migration have been implicated in the species' steep decline in the interior Columbia River basin. In this 2000–2010 study, we used radiotelemetry to evaluate potential predictors of lamprey passage success at McNary Dam, located ~469 river kilometres (rkm) from the Pacific Ocean. The tagged population included 276 lampreys collected at McNary Dam and 53 collected at Bonneville Dam (rkm 235) that migrated to McNary Dam. McNary Dam passage efficiency was similar for the two samples, with multiyear estimates of 0.65 and 0.75, respectively. Larger‐bodied lampreys and those with earlier migration timing were more likely to return to McNary Dam after release, to pass the dam and to be detected upstream from McNary reservoir. Far more lampreys entered the upper Columbia River than the Snake River, suggesting that environmental cues (e.g., water discharge, temperature) or conspecific cues (e.g., pheromone concentrations) affect lamprey distribution above this large confluence. Overall, results indicate that Pacific lamprey passage success at barriers depends on a combination of individual lamprey traits plus seasonal and site‐specific effects on behaviour.     

Gauging weirs impede the upstream migration of adult river lamprey Lampetra fluviatilis

Abstract The ability of individual and groups of 30 migrating adult river lamprey Lampetra fluviatilis L. to pass a Crump or flat‐v gauging weir under two discharge regimes (moderate and low) was assessed in an experimental channel. Despite repeated attempts by the lamprey, the Crump weir remained impassable during all trials. Lamprey passage over the flat‐v weir occurred only during group trials at low discharge (5.73 ± 0.19 L s^?1) and only as a single burst swimming event via the deeper water passing over the centre of the weir. Lampreys generally approached the weirs along the channel walls and particularly favoured the true right wall associated with elevated velocities during low discharge and reverse currents at moderate discharge (68.06 ± 2.41 L s^?1). Time spent immediately below the weir was lower than expected compared with further downstream. Rate of weir approach, attempts to pass (absolute number and as a proportion of the total approaches) and time spent immediately downstream of the weir were highest for the Crump weir at low discharge and the flat‐v weir at moderate discharge. The present study suggests that gauging weirs may severely impede the movements of migrating adult river lamprey under low to moderate discharges.     

Development of Pacific lamprey fishways at a hydropower dam

Abstract Traditional fishways do not accommodate the passage needs of all migrating species. In the north‐western United States, structures designed to aid adult Pacific lamprey, Lampetra tridentata (Gairdner), passage are critically needed. The structures described here were fabricated in modular units and installed at Bonneville Dam on the Columbia River (235 km). They featured a series of aluminium ramps interspersed with rest boxes that prevented lamprey from moving back downstream. The effects of various design changes and structure operation (water volume delivered) were assessed using lamprey counts and passive integrated transponder detections. Up to 40% of the lamprey entered the structures and 90–100% of these passed through to the exit. Lowering water volume pumped to the structures had little effect on lamprey performance, but passage improved when a 3.8‐m‐long, steep (40°) ramp was replaced with two, 1.4‐m‐long, 45° ramps. Pacific lamprey ascended the 8‐ to 9‐m‐high structures and entered the dam forebay in less than 1 h. The success of these prototypes was attributed to site selection and attention to lamprey‐specific performance.     

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.     

异侧布置竖缝式鱼道紊流结构试验研究

鱼道是辅助鱼类克服障碍物,实现产卵洄游、索饵洄游和越冬洄游的通道。全球目前已建鱼道中,鱼类能够溯游通过的鱼道尚不足50%,大多数鱼道的水力设计仅考虑平均流速,忽略了鱼道内的紊流结构,探究鱼道的水力特性尤其是紊流结构,对改进其设计具有重要的指导意义。通过在大比尺水槽模型中试验研究异侧布置竖缝式鱼道的紊流结构,利用声学多普勒测速仪(ADV)实测竖缝式水池内每一点的三维瞬时流速,剖析流场的三维时均流速分布、流动特征、旋涡特性、纵向和横向紊动强度分布、不同水平面的雷诺应力分布等,考虑了两种典型流量(Q1=20.62 L/s,Q2=30.75 L/s)和3个特征水平面(h/3,h/2和2h/3),提出了三维流速分布的半理论半经验公式、流场矢量图及各点的旋度,并与自由壁面射流进行比较。结果表明,异侧布置竖缝式鱼道前半池内纵向流速具有壁面射流的特征,后半池由于受下游隔板的阻挡则偏离壁面射流规律;水池内存在顺时针方向的水平旋涡,其旋度随流量的增大而增强;前半池壁面射流区的紊动强度存在峰值区,后半池的紊动强度峰值区由水槽左侧移至右侧;壁面射流区的雷诺应力变幅较大,而在旋涡区则较小,有利于洄游鱼类在鱼道上溯和歇息。     

竖缝式鱼道桩柱结构过鱼效果探索

竖缝式鱼道作为一种协助鱼类洄游上溯从而缓解提升河流连通性 的设施得到广泛的应用,但是多数鱼道的实际过鱼效能并不理想,尤其 是鱼道的池室结构尚具有一定的提升空间。本研究通过数值模拟和对照性过鱼试验对池室内部未增加和4种方式增加桩柱的池室水流结构进行了比较分析。结果表明在鱼道主流中间增设桩柱结构,可以有效减小回流区面积,减幅达49%;并减小竖缝处紊动能,最大紊动能减小18%;增加鱼类上溯路线分布,提高了池室空间利用率更高 。分析两种结构的上溯轨迹发现,齐口裂腹鱼多选择回流区外侧上溯,避免进入回流区中心,多选择较高的水力应变与紊动能区域调整作为上溯方向 ,且上溯路线中偏好较低水力因子区域上溯,上溯偏好流速范围0.01~0.09m/s,紊动能范围0.001~0.008m2/s2,水力应变范围0.2~3.0s-1     

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.     

Efficiency of a dual density studded fish pass designed to mitigate for impeded upstream passage of juvenile European eels (Anguilla anguilla) at a model Crump weir

This study demonstrated that juvenile (glass) eels used a specific substrate (eel tiles) to circumvent a model Crump weir under an experimental setting. Upstream passage efficiency was 0 and 67% for the unmodified (no studded eel tiles on the downstream face; control) and modified (with studded eel tiles on the downstream face; treatment) set‐ups, respectively, and was greater for a small (59%) compared to large (41%) stud configuration. Eels were active and motivated to ascend the weir during both control and treatment set‐ups. Approach and attempt rates were elevated during the first few minutes of the treatment compared to control trials. Eels were edge‐oriented under both set‐ups and ascended the weir through the tiles during single burst swimming events (reaching estimated speeds of 68.5 cm·s⁻¹). Eel tiles may provide a cost‐effective solution for mitigating impacts of anthropogenic barriers to juvenile eel migration. Further research is required to determine passage efficiencies under higher flows, for a greater size range of eel, and for other migratory anguilliform fish (e.g. lamprey, Lampretra spp. and Petromyzon marinus L.). The performance of eel tiles should be validated through robust field studies.     

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.     

双侧竖缝式鱼道水力特性研究

研究分析不同水池长宽比条件下双侧竖缝式鱼道的水池流场结构及其水力学指标,为双侧竖缝式鱼道布置参数的优化选择提供技术依据。基于单侧竖缝式鱼道体型参数的研究成果,选取导板长度与水池宽度之比为0.25、竖缝宽度与水池宽度之比为0.15、导向角度为45°作为研究的基本体型;鱼道来流边界设置为压力进口,上游水深设置为2 m,出流边界设置为压力出口,下游水深设置为2 m;模型顶部设置为压力进口,进口压强为1.01×105Pa,边墙设置为固壁边界。采用三维数值模拟的方法研究分析了水池长宽比分别为4∶8、5∶8、5.5∶8、5.75∶8、6∶8、6.5∶8、7∶8、8∶8、9∶8的条件下双侧竖缝式鱼道的水池流场结构及其水力学指标。在不同水池长宽比条件下,鱼道常规水池内存在3种典型流场结构,其主流轨迹线、主流流速沿程衰减规律以及回流区分布等水力学指标均有不同,典型长宽比取值区间分别为4∶8~5.5∶8、5.75∶8~6.5∶8及7∶8~9∶8;对比发现,长宽比在5.75∶8~6.5∶8区间范围时,主流区宽度相对较大,水池空间利用较为充分,沿程流速衰减情况也较好,回流区主要分布于主流两侧且大小适中。初步认为长宽比5.75∶8~6.5∶8的水池流场结构较为合理。     

Fish and lamprey passage in a combined Denil and vertical slot fishway

A fishway (fish pass), consisting of vertical slot and Denil sections, was constructed at the lowest dam on the River Kemijoki, northern Finland, in 1993. The river was one of the best salmon rivers in Europe until 1949, when the dam and the hydropower plant were completed close to the river mouth. From 1993 to 1995, nearly 1000 adult salmonids passed through the fishway despite heavy fishing below the dam. Of environmental variables measured, water temperature, headwater level, and discharge through the power plant in relation to season changes explained most of the variation in Baltic salmon, Salmo salar L., numbers. They had a minor effect on trout, Salmo trutta L. Migratory whitefish, Coregonus lavaretus (L.), entered the fishway but were not observed in its uppermost pool. River lamprey, Lampetra fluviatilis (L.), passed through the vertical slot section of the fishway after plastic bristles were fastened into the bottom of the slots.     

Role of large‐ and fine‐scale variables in predicting catch rates of larval Pacific lamprey in the Willamette Basin,Oregon

Pacific lamprey Entosphenus tridentatus is an anadromous fish native to the Pacific Northwest of the USA. That has declined substantially over the last 40 years. Effective conservation of this species will require an understanding of the habitat requirements for each life history stage. Because its life cycle contains extended freshwater rearing (3–8 years), the larval stage may be a critical factor limiting abundance of Pacific lamprey. The objective of our study was to estimate the influence of barriers and habitat characteristics on the catch‐per‐unit‐effort (CPUE) of larval Pacific lamprey in the Willamette River Basin, Oregon, USA. We sampled lampreys at multiple locations in wadeable streams throughout the basin in 2011–13 and used an information theoretic approach to examine the relative influence of fine‐ and large‐scale predictors of CPUE. Pacific lamprey was observed across the basin, but its relative abundance appeared to be limited by the presence of natural and artificial barriers in some sub‐basins. Lower velocity habitats such as off‐channel areas and pools contained higher densities of larval lamprey; mean Pacific lamprey CPUE in off‐channel habitats was 4 and 32 times greater than in pools and riffles respectively. Restoration and conservation strategies that improve fish passage, enhance natural hydrologic and depositional processes and increase habitat heterogeneity will likely benefit larval Pacific lamprey.     

Optimising Denil fishways for passage of small and large fishes

Abstract  An 8-m long experimental fishway was trialled at three different slopes [8.3% (1:12), 14.3% (1:7) and 20% (1:5)] to examine the potential of the single-plane Denil fishway for the passage of small- and large-bodied native fishes in Australia. Fish between 45 and 630 mm ascended the fishway. The lowest slope enabled the full size range of bony herring Nematalosa erebi (Günther), from 45 to 350 mm fork length, to ascend the fishway successfully as well as a higher numerical proportion; 88% at the 8.3% slope compared with 31% at the 20% slope (fish numbers per trial = 33–3936). These results dispel the notion that Denil fishways are inherently poor for small fishes. Manipulating the design parameters of slope, length, width and possibly depth-over-breadth ratio enables Denil fishways to pass a wide size range of fish, which may greatly extend their present application and enable them to make a greater contribution to the rehabilitation of diverse fish communities.     

Cumulative impacts of habitat fragmentation and the environmental factors affecting upstream migration in the threatened sea lamprey,Petromyzon marinus

1. River ecosystems are often fragmented by artificial structures, such as weirs. For anadromous species, these structures can impede access to upstream spawning sites and ultimately lead to severe population declines.
2. This study focused on the freshwater spawning migration of the sea lamprey, Petromyzon marinus, an anadromous species threatened by habitat fragmentation across its native range. To quantify the cumulative impacts of multiple weirs on upstream-migrating adults, and to explore the environmental factors affecting migratory movements, passive acoustic telemetry was applied to 56 individuals during their spawning migration in the heavily fragmented River Severn basin, UK.
3. While 89% of tagged sea lamprey passed the first weir upstream of the release site on the main river, only 4% passed the fifth weir. For 85% of migrants, the upstream extent of migration was immediately downstream of a weir. Individuals that passed weirs upstream of the release site (n = 50) took 21.6 ± 2.8 days to reach their most upstream location, experiencing cumulative passage times at weirs of 15.7 ± 2.8 days; these delays constituted a median of 84% of total upstream movement times.
4. Multistate models showed that the weir passage rates of sea lamprey in tidal and non-tidal areas increased significantly when downstream river level and discharge were elevated. Upstream-to-downstream changes in direction were frequent downstream of weirs, but rare in unobstructed river sections.
5. The results provided evidence for a cumulative effect of multiple weirs on sea lamprey movements, substantially delaying upstream migrants and limiting their spawning to atypical habitat. The results also demonstrated the crucial roles of high tides and elevated discharge events in enabling weir passage. Although the Severn Estuary features conservation designations for sea lamprey, this study reveals that barriers are inhibiting their upstream migration, a problem that should be addressed to assist sea lamprey conservation.

     

Use of a vertical-slot fishway by galaxiids in Western Australia

Abstract –  The Goodga River Fishway is the first vertical-slot fishway in Western Australia and was opened in April 2003 with the aim of increasing the habitat available to two galaxiids; the trout minnow ( Galaxias truttaceus ), a highly restricted freshwater fish species in Western Australia, and the widespread common jollytail ( Galaxias maculatus ). The fishway was designed to function during low flows to coincide with the upstream spawning migration of G. truttaceus . Prior to the opening of the fishway, no fish were found above the Goodga River gauging station (weir), which is approximately 2 km upstream of the river's entrance to Moates Lake. Fish migrations were monitored in each season between April 2003 and February 2005. Galaxias truttaceus utilised the fishway in all sampling periods. Adult fish migrated up the fishway prior to spawning, while large numbers of new recruits (small juveniles) negotiated the fishway during November 2003 and 2004. More G. truttaceus and G. maculatus were captured on the fishway during daylight hours compared with the night; however, larger G. truttaceus were more commonly captured at night whereas G. maculatus on the fishway were larger during the day. The fact that fishway utilisation by G. maculatus was consistent during all samples and new recruits migrated during periods of low flow demonstrates the importance of understanding the migration patterns of the target species when designing fishways.