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Context: Modern fish-protection screens are being implemented globally to conserve aquatic ecosystems and protect water infrastructure. Australian governments have invested ~A$40 × 106 towards incentive programs. However, evaluation remains limited. Aims: This study aimed to review progress, summarise research, and identify future priorities for screening in Australia. Methods: The study analysed screen installations to date, estimating their benefits for native fish and agricultural water supply. Key results: In New South Wales, 36 pumped water diversions were screened from 2018 to 2024. These installations protect over 819,000 native fish annually and can deliver up to 2600 ML of cleaner water per day, servicing over 230 km2 of irrigated agriculture. By 2026, these figures are set to rise to 48 sites, 1.72 × 106 native fish year−1 and 5461 ML day−1 of water. Conclusions: Although incentive programs are generating substantial public benefits, valued at least A$177 ML−1 of water passing through a modern screen, and with benefit–cost ratios averaging 4:1, installation costs remain high and national progress has been limited. Implications: Addressing these challenges is crucial to realising the full potential benefits of screening. Action is required to identify high-priority water diversions, improve affordability, encourage industry stewardship, and pursue advancements to facilitate wider adoption. Modern fish-protection screens are implemented globally to conserve aquatic ecosystems and infrastructure. They safeguard up to 90% of fish from water diversions, with Australian governments investing ~A$40 million in incentive programs. Progress in New South Wales includes screening 36 pumps from 2018 to 2024, protecting over 819,000 native fish yearly and delivering cleaner water for agriculture. Challenges remain in cost management and national expansion, necessitating prioritisation, affordability, industry stewardship, and ongoing advancements towards widespread adoption. [ABSTRACT FROM AUTHOR]

Context. Water pumps fitted with filtering screens are effective for delivering water to floodplain environments and excluding large-bodied exotic fish; yet, the benefits to wetland fish and anurans are unknown. Aims. To quantify fish and tadpole responses to refilling wetlands with water pumps fitted with large-mesh screens following drawdown v. overland reconnections in themid-Murrumbidgee region of New South Wales. Methods. Frog and fish communities were compared between wetlands under managed inundation and overland reconnections by using PERMANOVA, and non-metric multidimensional scaling was used to evaluate community divergence between watering strategies. Classification and regression trees were used to identify thresholds in explanatory variables and predicted threshold responses in fish and tadpole abundance. Key results. Fish and tadpole communities differed in relation to watering strategies. Managed inundation resulted in a higher abundance of tadpole species and one native fish, whereas overland reconnections resulted in a high abundance of exotic fish species and fewer tadpoles. Water depth was a driver of tadpole abundance in two species, including the threatened southern bell frog (Litoria raniformis). Conclusions and implications. Using filtered pumps with large-mesh screens to deliver water to wetlands of high conservation value may be an effective strategy for reducing large-bodied exotic fish and enhancing frog and fish populations in regulated floodplain systems. [ABSTRACT FROM AUTHOR]

Summary: Globally, the extraction and diversion of water from river systems has had substantial impacts on aquatic ecosystem health and ecological processes. One such impact is the entrainment of fish at pump offtakes that can result in vast quantities of fish being permanently removed from rivers. Exclusion screens to prevent fish entrainment at pump offtakes are therefore an important management consideration. In this study, impingement and subsequent injury and mortality of a juvenile freshwater perciform, Golden Perch (Macquaria ambigua), was assessed in the laboratory using a simulated fish exclusion screen under a range of velocities and impingement durations. A 2 mm wedge‐wire screen eliminated the entrainment of 44‐day‐old Golden Perch that were exposed to approach velocities between 0.05 and 0.3 m/s. However, impingement rates of Golden Perch increased significantly with increased approach velocities and rates of injury and mortality increased with impingement duration. Results from this study indicate the primary mechanisms to reduce fish loss at pump offtakes are to design pump offtakes, fitted with fish exclusion screens, which limit approach velocities or impingement duration. Further studies are required to examine a range of species with varying swimming ability at early life‐history stages. Such data will contribute to the growing body of knowledge that supports adaptive management plans to prevent fish loss at water offtake pumps. [ABSTRACT FROM AUTHOR]

Anthropogenic water management projects and facilities that alter the local and regional hydrology of riverine environments greatly influence the behavior, physiology, and survival of native fishes. To mitigate for losses of native fishes at these structures, many are outfitted with fish-exclusion screens to reduce entrainment. The effect of fish size and age on behavior near fish screens, however, is largely unknown. Therefore, we tested two size classes of juvenile green sturgeon ( Acipenser medirostris; small, early juveniles: 9.2 ± 0.2 cm fork length [FL], 6.9 ± 0.3 g; intermediate juveniles: 18.8 ± 0.2 cm FL, 36.9 ± 0.8 g) near fish-exclusion screens in a laboratory swimming flume. Although size was a significant factor influencing the way in which fish contacted the screens (i.e., proportion of body contacts, p = 2.5 × 10), it did not significantly influence the number of times fish contacted screens or the amount of time fish spent near screens. We also compared the performance of these two size classes to that of older and larger sturgeon that were tested previously (29.6 ± 0.2 cm FL, 147.1 ± 3.1 g), and documented a clear difference in the behavior of the fish that resulted in disparities in how the large fish contacted screens relative to small- or intermediate-sized juveniles ( p = 0.005, 5.4 × 10, respectively). Our results further our understanding of how ontogeny affects fish behavior near anthropogenic devices, and are informative for managers seeking to identify the most susceptible size and age class of juvenile green sturgeon to water-diversion structures to potentially develop size-specific conservation strategies. [ABSTRACT FROM AUTHOR]

We investigated the guidance efficiency of fish screens for the protection of emigrating Pacific LampreyEntosphenus tridentatusand Western River Lamprey (also known as River Lamprey)Lampetra ayresiiin a series of experimental trials. All trials were conducted at the Tracy Fish Collection Facility, located in the Sacramento–San Joaquin River Estuary at the entrance to one of the world’s largest surface water diversions. Using 1,200 lamprey macrophthalmia, we tested for the effect of screen type, time of day, and channel water velocity to guide their swimming behavior to avoid entrainment. We found overwhelming evidence for an effect of screen type on efficiency, whereby all lampreys were successfully guided to a holding tank when a vertical traveling screen was used. This was likely due to the small pore size of the screen relative to lamprey sizes. In contrast, the efficiency of louvers, a behavioral screen designed for salmonids, varied by the interaction of time of day and channel velocity. During nighttime, when lamprey typically emigrate, louver guidance efficiency ranged from 21% (95% CI, 14–30%) to 24% (95% CI, 16–34%). These results were applied to estimate the probability for salvage of lamprey macrophthalmia at the Tracy Fish Collection Facility, which includes a two-stage fish screen design. Between 1957 and 2014, we estimated that 94–96% of the lampreys that were entrained in the export flows were lost and not returned to the delta. However, the probability for fish loss was reduced in 2014 when the secondary louver was replaced with a vertical traveling screen. Our results suggest that lamprey macrophthalmia entrainment into the canals will be eliminated at the Tracy Fish Collection Facility if the primary screen is converted to vertical traveling screen. Surface water diversions may represent a substantial threat to regional metapopulations of anadromous lamprey species worldwide, and screening approaches applied to other fish species such as salmonids may not be protective of lampreys. Received June 7, 2016; accepted August 23, 2016Published online December 20, 2016 [ABSTRACT FROM AUTHOR]

Entrainment and impingement of two non-salmonid species susceptible to entrainment at irrigation diversions, silver perch, Bidyanus bidyanus (Mitchell), and golden perch, Macquaria ambigua (Richardson), were examined at an experimental intake screen in a laboratory flume under a range of velocities and light levels. The presence of an intake screen significantly reduced entrainment, in some cases reducing mortality from over 90% (unscreened) to less than 2% (when screened). Although some differences in behaviour existed between species, approach velocities (measured 8 cm in front of the screen) up to 0.4 m s−1 effectively reduced entrainment, with very little injury or mortality resulting from incidental screen contacts or impingement. Both species used visual cues to negotiate the screen face, thereby increasing their ability to avoid contact at higher velocities. In the absence of these visual cues, positive rheotactic behaviour was enhanced and fish mostly avoided approaching the screen. These results demonstrate that fish screens operated at approach velocities of up to 0.4 m s−1 have great potential for the protection of silver perch and golden perch juveniles at irrigation intakes. [ABSTRACT FROM AUTHOR]

The roles of vision and the lateral-line system in fish-screen avoidance behaviors were investigated in Sacramento splittail ( Pogonichthys macrolepidotus). Fish were viewed swimming in front of water-diversion-type fish screens in a laboratory flume during the day (lit condition) and night (darkened condition, using infrared equipment). Streptomycin-sulfate treatments were used to block the fish's lateral-line systems. Lateral line neuromasts were labeled with 2-(4-(dimethylamino)styryl)-N-ethylpyridinium iodide (DASPEI) to assess the streptomycin treatment's effectiveness. Splittail contacted the screens infrequently during the day, but contacted the screens significantly more often during the night. Also, in darkened conditions, streptomycin-treated splittail contacted the screens significantly more often than did control fish. Furthermore 60 % of the streptomycin-treated fish became impinged (stuck) to the screens during night experiments, compared to 15 % of the untreated fish. These findings suggest that splittail use their lateral-line system to detect and avoid objects (screens) in the absence of vision. Splittail displayed no response to stimuli generated from a piston-driven vibrator mounted to the center of the screens. Our findings are the first to show how fish can use different sensory systems to detect and avoid fish screens in the presence or absence of light, and they should benefit fisheries and water resources managers, regarding the timing of water extractions through screened water diversions. [ABSTRACT FROM AUTHOR]

Fish screens can help prevent the entrainment or injury of fish at irrigation diversions, but only when designed appropriately. Design criteria cannot simply be transferred between sites or pump systems and need to be developed using an evidence-based approach with the needs of local species in mind. Laboratory testing is typically used to quantify fish responses at intake screens, but often limits the number of species that can studied and creates artificial conditions not directly applicable to screens in the wild. In this study a field-based approach was used to assess the appropriateness of different screen design attributes for the protection of a lowland river fish assemblage at an experimental irrigation pump. Direct netting of entrained fish was used along with sonar technology to quantify the probability of screen contact for a Murray-Darling Basin (Australia) fish species. Two approach velocities (0.1 and 0.5 m.sec−1) and different sizes of woven mesh (5, 10 and 20 mm) were evaluated. Smaller fish (<150 mm) in the assemblage were significantly more susceptible to entrainment and screen contact, especially at higher approach velocities. Mesh size appeared to have little impact on screen contact and entrainment, suggesting that approach velocity rather than mesh size is likely to be the primary consideration when developing screens. Until the effects of screen contacts on injury and survival of these species are better understood, it is recommended that approach velocities not exceed 0.1 m.sec−1 when the desire is to protect the largest range of species and size classes for lowland river fish assemblages in the Murray-Darling Basin. The field method tested proved to be a useful approach that could compliment laboratory studies to refine fish screen design and facilitate field validation. [ABSTRACT FROM AUTHOR]

Understanding the effects of irrigation diversions on populations of Pacific lamprey Lampetra tridentata in the Columbia River basin is needed for their recovery. We tested the effectiveness of five common fish screen materials for excluding lamprey ammocoetes: interlock (IL), vertical bar (VB), perforated plate (PP), and 12-gauge and 14-gauge wire cloth (WC12) and (WC14). When fish (28–153 mm) were exposed for 60 min to screen panels perpendicular to an approach velocity of 12 cm/s in a recirculating flume, the percentage of ammocoetes entrained (i.e., passed through the screen) was 26% for the IL, 18% for the PP, 33% for the VB, 62% for the WC14, and 65% for the WC12 screens. For all screens, most fish were entrained within the first 15–20 min. Fish length significantly influenced entrainment, with the PP, VB, and IL screens preventing fish greater than 50–65 mm from entrainment and the WC14 and WC12 screens preventing entrainment of fish greater than 90–110 mm. Fish of all sizes repeatedly became impinged (i.e., contacting the screen for more than 1 s) on the screens, with the frequency of impingement events increasing during the first 5 min and becoming relatively stable thereafter. Impingement ranges were highest on the IL screen (36–62%), lowest on the WC14 and WC12 screens (13–31%), and intermediate on the PP and VB screens (23–54%). However, the WC14 and WC12 screens had fewer and larger fish remaining as time elapsed because so many were entrained. For all screen types, injuries were rare and minor, and no fish died after overnight posttest holding. Our results indicate that wire cloth screens should be replaced, where practical, with perforated plate, vertical bar, or interlocking bar screens to reduce lamprey entrainment at water diversions. Received October 26, 2011; accepted March 14, 2012 [ABSTRACT FROM AUTHOR]

Screens are installed at water diversion sites to reduce entrainment of fish. Recently, the Farmers Irrigation District (Oregon) developed a unique flat-plate screen (the “Farmers Screen”) that operates passively and may offer reduced installation and operating costs. To evaluate the effectiveness of this screen on fish, we conducted two separate field experiments. First, juvenile coho salmon Oncorhynchus kisutch were released over a working version of this screen under a range of inflows (0.02–0.42 m3/s) and diversion flows (0.02–0.34 m3/s) at different water depths. Mean approach velocities ranged from 0 to 5 cm/s and sweeping velocities ranged from 36 to 178 cm/s. Water depths over the screen surface ranged from 1 to 25 cm and were directly related to inflow. Passage of fish over the screen under these conditions did not severely injure them or cause delayed mortality, and no fish were observed becoming impinged on the screen surface. Second, juvenile coho salmon and steelhead O. mykiss were released at the upstream end of a 34-m flume and allowed to volitionally move downstream and pass over a 3.5-m section of the Farmers Screen to determine whether fish would refuse to pass over the screen after encountering its leading edge. For coho salmon, 75–95% of the fish passed over the screen within 5 min and 82–98% passed within 20 min, depending on hydraulic conditions. For steelhead, 47–90% of the fish passed over the screen within 5 min and 79–95% passed within 20 min. Our results indicate that when operated within its design criteria, the Farmers Screen provides safe and efficient downstream passage of juvenile salmonids under a variety of hydraulic conditions. Received November 17, 2011; accepted March 15, 2012 [ABSTRACT FROM AUTHOR]

The impact of water diversion on fish populations is a global issue. Many countries have invested substantial funding into research and implementation strategies to ensure fish are protected at diversions that take water out of rivers for agriculture and other human uses. The most common management action is the installation of fish screens, and a wide range of designs are presently available that suit a large range of diversions. The Murray-Darling Basin is the largest catchment in Australia and has been substantially developed over the past 100 years to store and divert water for that protect fish from escaping into the irrigation systems. Recent studies have determined that water diversions have substantial impacts on native fish populations, but there are presently no coordinated efforts for mitigation strategies. The purpose of this review is to highlight aspects of successful screening programmes worldwide and identify those that could be directly applied to the Murray-Darling Basin. The development of similar programmes in the United States, New Zealand and the United Kingdom has identified that sufficient information and technology exists to inform the development of fish screening programmes. There is no need to commence implementation from first principles, and substantial progress can be achieved by applying successful aspects of other programmes. By identifying existing designs, defining ecological targets, developing generalised guidelines appropriate for local conditions and engaging the community, a co-ordinated and successful fish screening programme could be directly applied to the Murray-Darling Basin. This would have substantial benefits for the long-term sustainability of native fish without compromising water supply requirements. [ABSTRACT FROM AUTHOR]

Abstract: Behavioural devices that attract or deflect migrating fish to preferred routes are used to enhance the efficiency of mechanical structures (e.g. screens at turbine and other intakes) or as an alternative to them when their application is deemed unviable. Fish response to stimuli (signals) encountered, and consequently the efficiency of these behavioural devices, can be highly variable. To further develop efficient behavioural screens and fish pass technology there is a need for a generic framework to (1) better understand fish response to environmental stimuli and causes of variation, and (2) quantify ability to detect stimuli and respond in a way deemed appropriate from a management perspective. This paper considers application of signal detection theory (SDT) to fish passage research, using downstream migrating juvenile salmonids as a model. Support is provided in the scientific literature for two key assumptions, that downstream migrants are able to exhibit volitional behaviour in response to stimuli encountered and that these behaviours can be interpreted by an observer to indicate the detection of a signal. Re-evaluation of available data highlights the temporal variability of decision making and elicitation of behaviour within and between individuals, and that sensitivity (d′), a measure of the ability to detect a signal (e.g. hydraulic gradient), increases with signal strength and when multimodal stimuli are presented. SDT is likely to provide a useful “first base” for understanding and quantifying fish behaviour in the development of screens and fish passes. [Copyright &y& Elsevier]

Mean and turbulent flow characteristics on the upstream and downstream sides of the screen in a flow diversion channel have important implications for operation and maintenance (e.g., sedimentation) and for assessing fish behavior related to flow turbulence. This technical note extends an earlier study on mean flow near screens to turbulence characteristics. Acoustic Doppler velocimeter was used to explore three-dimensional mean and turbulent flow characteristics on the upstream and downstream sides of vertical angled fish screens. The present study confirms the two-dimensional mean velocity observations of the previous experimental work and shows that the vertical mean velocities are less than 10% of the local magnitudes of longitudinal velocity and hence can be ignored. Horizontal components of the mean velocity on the downstream side of the screen were relatively small, but the turbulent velocity fluctuations were two to three times as intense as those measured on the upstream side. [ABSTRACT FROM AUTHOR]

Abstract: Trash (debris) racks are the main line of defense to keep submerged aquatic plants such as “Egeria” and other non-floating debris out of fish screen facilities. This study evaluates the debris capture efficiency under 16 different debris rack configurations, which include 4 bar spacings and 4 angles of inclination, under two flume velocities. For each flow regime, first the velocity fields were measured at three transects near the debris rack with no debris. While under 0.30m/s velocity the debris rack did not affect the flow field, under 0.61m/s velocity it slowed the flow velocity around the rack near the surface and increased it near the flume bottom. The debris that was collected in front of the debris racks at Tracy Fish Collection Facility, California was analyzed for its composition. The debris composition was found to change through the year, and Egeria of less than 15.24cm was about 50% of the debris loading. Six replicates of Egeria run were conducted for each combination of debris rack configuration and flow regime. In the presence of debris, velocity profiles at locations upstream from the debris rack were not significantly affected by the debris or the rack, while downstream from the debris rack velocities at the flume bottom were significantly larger than those at the top. The experimental results show that when average velocity is 0.30m/s, in general the debris capture efficiency increases as the angle of inclination decreases for bar spacing greater than 3.81cm. However, for 0.61m/s velocity, the same trend only holds for 7.62cm bar spacing, with no discernible trend for other bar spacings. Meanwhile, debris capture efficiency increases with decrease in bar spacing for all angles of inclination and all velocities. [Copyright &y& Elsevier]

Irrigation canals entrain anadromous and potamodromous salmonids of all life stages during their annual migrations. Fish screens may reduce or eliminate entrainment, but few studies exist on their benefits and these studies have evaluated effects on anadromous populations only. The benefits of fish screens for nonanadromous salmonids are largely unknown. Postspawn adult and downstream-migrating juvenile westslope cutthroat trout Oncorhynchus clarkii lewisi are potentially entrained into irrigation canals on Skalkaho Creek, Montana. We quantified entrainment rates into the canals using telemetry and driftnetting before (2003) and after (2004) installation of fish screens on three canals. No radio-tagged adults were entrained in 2003, but most adults were residents and therefore did not migrate past the canals. In 2004, 79% of the radio-tagged adult migratory fish were entrained at either screened or unscreened canals, but all those entrained in screened canals were successfully bypassed back to Skalkaho Creek. The uppermost (Highline) canal entrained about 71% of age-0 westslope cutthroat trout moving downstream in 2003. Without the screen, 38% of age-0 fish would have been entrained in the canal during 2004. In total, 6,034 age-0 westslope cutthroat trout were bypassed by all three screens. Most age-0 westslope cutthroat trout entrained at screened canals were successfully bypassed, whereas those entrained at unscreened canals were lost to the population. Fish screens were an effective management tool that reduced or eliminated entrainment at Skalkaho Creek and may be useful elsewhere to curtail entrainment of migratory inland salmonids. [ABSTRACT FROM AUTHOR]

This paper presents a simple method to predict flow diversion by vertical angled screens in open channels. The performance of this method has been compared with the experimental results from a recent laboratory study of vertical angled screens. This method is then used to predict the effect of screen porosity, variation of porosity along the length of the screen, and several other factors on the flow division. The results of this investigation would be useful in the design of vertical angled screens for fish protection at water intakes from rivers for irrigation, and other industrial uses. [ABSTRACT FROM AUTHOR]

This paper presents the results of a laboratory study of the structure of flow in a diversion structure with a vertical angled wedge-wire fish screen. This screen had a 10 × 25 mm mesh and was tested at three angles of 10.4, 17.5, and 26.8°, to the direction of the approaching flow, for two mean velocities of 0.5 and 0.8 m/s, with a depth of flow of about 0.75 m. In this water and fish diversion (channel or) structure, it was found that the depth of flow at any section is approximately constant with a drop at the screen on the side of the canal and decreased towards the bypass located at the downstream end. The distribution of the velocity component it in the direction of the approaching flow as well as the perpendicular component w and the resultant velocity V was uniform in the vertical direction. The depth averaged mean velocity &Vmacr; for different verticals at any section in the diversion structure increased with the longitudinal distance x and was correlated with the relative width, bs/b (in the diversion structure) for all five experiments. Correlations have been found for the depth averaged transport velocity &u'macr; and the impinging velocity on the screen &w'macr; in terms of the approach velocity U. A general relation has also been developed for the attack angle of the flow on the screen. The downstream part of the screen carried more flow into the canal compared to the upstream part as a result of the uniform mesh size used in this study. The results of this hydraulic study should be useful, particularly for freshwater adult fish, in designing screens in irrigation canals and for micro-hydro sites that use diversion canals. [ABSTRACT FROM AUTHOR]

Identifies the attraction of domestic chicks to video images. Examination of mammalian behaviors; Regulation of chicken behavior in response to neutral video images; Production of Fish screensaver image by filming from a computer monitor.

The article focuses on the comments about the experiment called "Screen Size and Differential Faunal Recovery: A Hawaiian Example." It is stated that the experiment had serious errors in the interpretation of subsistence strategies that resulted from inadequate recovery procedures and experimental data. The author asserts that the use of large screens fraction can recover the faunal remains in the fish samples, while small screen fraction provides a more representative sample of fishes. The differences in sample size are very important for identifying the fish at the Nualolo Kai in Kauai Island, Hawaii.

The article focuses on the experiment of Elizabeth A. Gordon entitled "Screen Size and Differential Faunal Recovery: A Hawaiian Example." The experiment showed that the archaeologists are failed to recover and to identify faunal materials using screen fraction. The author emphasizes that the screens can recover the calls only for minor revisions in the interpretation of early and late prehistoric faunal assemblages in the Pacific Islands. Gordon asserts that homogenous small screen fraction can detect the non-fish vertebrate samples as generalized predators, while heterogeneous large screen fraction can identify the fish as specialized predators.

A correction to the articles "Reducing the perversion of diversion: applying world-standard fish screening practices to the Murray-Darling Basin" and "The Seedling Ratio Method for determining ungulate impacts on forest understoreys: Utility in an Australian ecosystem" that was published in 2012 issue is presented.