Fish Screens Research Articles

Early mucosal responses in common carp (Cyprinus carpio) to the infection of Aeromonas hydrophila

Common carp (Cyprinus carpio), an economically important freshwater fish species, is worldwide farmed especially in Europe and Asia. The current high-density intensive rearing way leading to a high susceptibility to various pathogens, and Aeromonas hydrophila is one of the most frequently encountered bacteria, causing huge economic losses to the common carp industry. The mucosal barrier of fish constitutes the first line of defense against various pathogens, and some level of inter-connectivity exists among teleost mucosal tissues. However, the molecular basis for a common mucosal immune response at multiple sites or response at one site but during different timepoints following stimulation remains to be studied. In this study, we examined and systematically analyzed a total of 144 transcriptome files from three primary common carp mucosal tissues at four early timepoints following the infection of A. hydrophila. A total of 410 unigenes were significantly differentially expressed in all tested mucosal tissues. Through GO enrichment and KEGG pathway analysis, 28 key genes which might played critical roles in the common mucosal immune response of common carp during the early stage of bacterial infection were identified. Further WGCNA analysis showed that, besides the common response, three mucosal tissues exhibited tissue-specific gene regulatory network. Meanwhile, candidate hub genes in each tissue were identified, including trim3, rpl14, tln2, itpr1, and others. Our results will provide a fundamental basis for understanding the molecular mechanisms of teleost mucosal immunity, and might suggest strategies for developing novel teleost mucosal vaccines in aquaculture.

Fish Distribution Pattern and Management in the Tinau River, Palpa

For study direct observation, survey, questionnaire, interviews and discussion method are used to meet the objectives. The main objectives of the study were fish distribution pattern and fish management. The field work was performed between September 2016 to june 2017 of different five stations in Tinau river. Local fishermen were also used for the collection of fishes from sampling sites. Cast net, hook, Bhureli jal and Nets (Jhal) other locally available devices were used for the collection of fish sample. Altogether 5 orders, 9 families, 14 genera and 25 species were found in the study area. Among them 19 fish species from Station I, 16 fish Species from Station II and station III, 10 fish species from Station IV and 7 species from Station V were collected with the help of local fisherman. Fish species such as Channa punctatus, Puntius conchonius and Glyptothorax pectinopterus were found to be clumped in distribution while the rest of the fishes were uniformly distributed. Cyprinids were found to be the most common and dominant among all the species. The human impacts like construction of dam, bridges, riverbed extraction, bank erosion, illegal fishing and use of poisonous chemicals effects on the fish distribution and management directly of the Tinau river. For the management practices like implementation of strict rules and regulations, made ladder for fish passing, construction of fish barrier, plantation, control water pollution and awareness programmes should be done with the help of local people and other institutions. This study helps the local people to pay more attention towards the knowledge about indigenous or locally found fishes and proper management of the Tinau river.

Evaluation of a carbon dioxide fish barrier with OpenFOAM

Evaluation of a carbon dioxide fish barrier with OpenFOAM

Yinchenhao Decoction mitigates intestinal impairment induced by high carbohydrate diet in largemouth bass (Micropterus salmoides): insights from inflammation, apoptosis, oxidative stress, tight junctions, and microbiota homeostasis.

As a major source of energy, carbohydrates have a protein-saving effect. However, excessive consumption of carbohydrates can lead to the disruption of the intestinal barrier in fish, especially for carnivorous fish. Therefore, traditional Chinese medicine component Yinchenhao Decoction (YD), was used to detect the effect on intestinal barriers and microbial community equilibrium for largemouth bass in current research. In this research, a series of NC (normal carbohydrate diet) and HC (high carbohydrate diet) with graded YD treatments during 10 weeks feeding trial. Results suggested that 2% and 4% YD treatments significantly reduced gut inflammation and mucosal loss caused by HC. Compared with NC, HC significantly decreased the relative expression of intestinal tight junction-related genes (zo1, claudin1, claudin7, and occludin). However, with the application of YD, the expression of tight junction-related genes (zo1, claudin1, and claudin7) increased significantly (p < 0.05). Likewise, administration of YD significantly reduced elevated plasma diamine oxidase (DAO) activity caused by HC (p < 0.05). Additionally, YD significantly downregulated the mRNA expression of endoplasmic reticulum stress (ERS)-related genes (grp78, atf6, chopα, ire1, xbp1, and eifα) and pro-apoptosis genes (casp3, casp8, and bax) (p < 0.05), while upregulating the anti-apoptosis gene bcl2 (p < 0.05). Moreover, YD significantly increased the mRNA expression of antioxidant genes and the enzyme activities of CAT and GPX, while decreased MDA concentration significantly (p < 0.05). Whereas, YD markedly decreased the expression of pro-inflammatory genes (il1β, tnfα, il8, and nf-κB) and the immune enzymes activity (ACP and AKP) (p < 0.05) by up-regulating the expression of anti-inflammatory genes (ikb and il10). Notably, YD modulated the largemouth bass intestinal microbial community, enhanced the diversity and increased the abundance of probiotic microorganisms in the intestinal microbiota. In summary, YD supplementation in HC alleviated inflammation, apoptosis, oxidative stress, tight-junction injury, and microbiota disequilibrium in the intestine, which suggested that YD could be a valuable functional additive in aquaculture.

Anchor chains—A simple low‐cost device to assist passage of small‐bodied mass fish

AbstractAttention has been placed on a variety of barriers that hinder fish passage in modern times. The most prevalent fish barriers were culverts which have negatively impacted waterway connectivity and fish habitats. For small‐bodied mass fish, high barrel velocities and turbulence have reduced fish swimming performance because of their weak swimming capabilities. In the present study, physical testing was conducted under controlled flow conditions to assess the extent and magnitude of turbulence characteristics, secondary flow and low‐velocity zones in a 0.5‐m‐wide box culvert barrel. Two cases were investigated; a reference case consisting of a smooth rectangular channel and a low‐cost design solution to improve upstream fish migration consisting of a single galvanized anchor chain fitted within a smooth rectangular channel. The single anchor chain was positioned towards one corner of the channel to induce asymmetric flow, reducing overall energy losses and enhancing the existing low‐velocity zone in the adjacent channel corner. The anchor chain induced a strong turbulent flow motion away from the anchor chain, characterized by higher Reynolds stress and turbulent kinetic energy, along with a distinct channel flow asymmetry. Conversely, the low‐velocity zone, between the anchor chain and the bottom channel corner, was significantly expanded with reduced longitudinal mean velocities and turbulent scales. Whilst the anchor chain link contributed to some complex localized wake flow, the anchor chain also influenced the distributions of normal turbulent stresses (v'z2 – v'y2), which in turn influenced the location of secondary flow cells. This secondary flow redirected low momentum fluid into the low‐velocity zones, setting the conditions for the favorable upstream passage of small‐bodied mass fish species.

Setting PFAS-Based Fish Consumption Advisories for Virginia Waterways

This policy memo is intended for the Commissioner of Health at the Virginia Department of Health (VDH). The memo provides recommendations when assessing the need for per- and polyfluoroalkyl substances (PFAS)-based fish consumption advisories in Virginia waterways. High-frequency fish consumers and sensitive populations face a greater risk of negative health effects from exposure to PFAS through eating local freshwater fishes. By performing state-wide fish screening assessments for relevant PFAS, the VDH can determine if the nutritional benefits from eating fish outweigh the health risks from PFAS exposure. The following memo recommends that VDH update their PFAS fish tissue screening assessment to include PFUnA and PFDA and release final fish tissue screening recommendations for PFOA and PFOS.

Tumor necrosis factor α1 decreases mucosal immune and antioxidant response in the midgut of hybrid fish (white crucian carp ♀ × red crucian carp ♂).

Tumor necrosis factor α1 (TNFα) is a pleiotropic cytokine involved in immune regulation and cellular homeostasis, but the crucial role of TNFα in fish gut remained unclear. The current study aimed to evaluate the immunoregulatory function of TNFα1 on gut barrier in a novel hybrid fish (WR), which was produced by crossing white crucian carp (Carassius cuvieri, ♀) with red crucian carp (Carassius auratus red var, ♂). In this study, WR-tnfα1 sequence was identified, and a high-level expression was detected in the intestine. Elevated levels of WR-tnfα1 expressions were detected in immune-related tissues and cultured fish cells on stimulation. The appearance of vacuolization and submucosal rupture was observed in TNFα1-treated midgut of WR, along with elevated levels of goblet cell atrophy, whereas no significant changes were detected in most expressions of tight-junction genes and mucin genes. In contrast, WR receiving gut perfusion with WR-TNFα1 showed a remarkable decrease in antioxidant status in midgut, whereas the expression levels of apoptotic genes and redox responsive genes increased sharply. These results suggested that TNFα1 could exhibit a detrimental effect on antioxidant defense and immune regulation in the midgut of WR.

Assessing entrainment of larval fish in the Hogback Diversion Canal, San Juan River

AbstractWater diversions worldwide may entrain or impinge fish and have population‐level impacts, but barriers like fish screens can reduce such threats. Traditional barriers are ineffective in the San Juan River, USA, due to high sediment and debris loads, so the Hogback Diversion Canal, NM, employs a novel weir wall design to reduce entrainment of sub‐adult and adult fishes. We evaluated the effectiveness of the weir wall in reducing the entrainment of larval fish using a combination of experimental and overnight trials. Larval fish densities were compared between the irrigation canal that delivers water to irrigators and subsequently entrains fish and the bypass canal that conveys water and fish back to the river. The density of hatchery‐produced larval fish collected in the irrigation canal during the experimental trial (0.74 fish/m3) was 52% of their density in the bypass canal (1.43 fish/m3), suggesting entrainment reduction. The density of wild‐produced larvae during overnight trials indicated some minor, mostly nonsignificant, differences between catch rates in irrigation and bypass canals, ontogenetic phases, and sampling dates. Though entrainment rates of wild‐produced larvae were not significantly reduced, density differences among postflexion mesolarvae and metalarvae suggest possible entrainment reduction of more developed ontogenetic phases. More intensive research is necessary to better elucidate the efficacy of the novel weir wall for reducing the entrainment of larval fish. However, our larval fish results and the results from prior large‐bodied entrainment studies suggest the novel weir wall may reduce fish entrainment in water diversions and benefit fluvial ecosystems in which traditional screens are unfeasible.

Murray cod and modern fish screens: influence of water velocity and screen design on the entrainment and impingement of larval and young-of-year fish at water offtakes

Context Entrainment and removal of fish from aquatic ecosystems can occur at water pump offtakes. Exclusion screens that reduce these impacts are recognised as an important conservation measure. Aims Evaluate the effectiveness of the Australian screen design guidelines in protecting larvae and young-of-year age class of a native fish species, Murray cod Maccullochella peelii. Methods Entrainment and impingement of postflexion larvae and young-of-year were assessed in a controlled laboratory environment. Tests were conducted under a range of approach velocities (AV) and impingement durations for two screen materials. Key results Fish screens reduced larval entrainment by ≤84%. Screens had no significant effect on reducing larval entrainment at AV ≥0.125 m s−1. Impingement of young-of-year was positively associated with AV and mortality increased with impingement duration, irrespective of screen type. Conclusions To protect early life-stage Murray cod, it is recommended that water pump offtakes be fitted with 2-mm vertical wedge-wire stainless steel screens and AV be limited to ≤0.1 m s−1. Implications This study represents the first assessment of the effectiveness of the Australian screen design guidelines in protecting larvae, providing knowledge to further refine specifications for screen design and support the recovery of native fish populations.

Estimated capital costs of fish exclusion technologies for hydropower facilities

Hydropower is a reliable source of renewable energy, and its future expansion is likely to be in the form of either smaller new stream development (NSD) projects or powering existing non-powered dams. Thresholds for entrainment risk to fish and the requirements for fish exclusion at hydropower facilities often differ depending on the species involved, the characteristics of the facility, and the goals of stakeholders, but little quantitative information is present within the literature regarding the specific costs of fish exclusion measures. Cost data associated with protection, mitigation, and enhancement (PM&E) measures related to positive barrier screening were identified using keyword searches of an existing environmental mitigation cost data set and manual extraction from regulatory licensing documents available in the Federal Energy Regulatory Commission (FERC) eLibrary. This approach yielded a total of 50 p.m.&E mitigation measures with estimated capital construction costs pertaining to positive barrier screens and represented <10% of the 171 total FERC project dockets available in the data set. These data were highly skewed toward conventional relicensing projects, as <7% were associated with NSD projects. Results indicate highly variable costs are associated with fish screening, with flow-normalized costs one to two orders of magnitude higher for screening with the highest exclusion capability (≤0.09 in. spacing) compared with coarser screening (1–2 in.). These data provide an initial baseline for estimating exclusion costs for hydropower development and may help developers consider options for more fish-friendly generation technologies, though gaps remain relating to a lack of data, particularly for NSD projects.

Tumor necrosis factor α1 (TNFα1) administration can disrupt barrier function and attenuate redox defense in midgut of red crucian carp (Carassius auratus red var)

TNFα belongs to superfamily of tumor necrosis factor that can exert the pleiotropic effort in a large quantity of biological processes, including immune homeostasis, intracellular modulation and etiopathogenesis, but its regulatory role in mucosal immune regulation of fish is unclear. Currently, this study aimed to evaluate the immunoregulatory function of TNFα1 on gut barrier in teleost fish. In this study, TNFα1 sequences were identified from red crucian carp (RCC, Carassius auratus red var). The high-level expression of RCC-TNFα1 mRNA was detected in gill among all the isolated samples. Then, RCC-TNFα1 expression increased dramatically in immune-related tissues after A. hydrophila infection and in cultured fish cells after lipopolysaccharide (LPS) treatment. RCC-TNFα1 fusion protein was generated and purified in vitro. RCC receiving RCC-TNFα1 perfusion showed an increased levels of villi fusion and edema in injured midgut with the fuzzy appearance. In addition, The mRNA expressions of tight junction (TJ) genes, mucin genes and redox sensitive genes decreased sharply in TNFα1-treated midgut in comparison with those of the control (P < 0.05), whereas the expression levels of apoptotic genes involved in caspase signals and unfolded protein response (UPR) attained the dramatic increase. These results demonstrated that RCC-TNFα1 stimulation could impair midgut structural integrity and immune function by induction of antioxidant collapse and apoptotic activation.

Toxicity of TPhP on the gills and intestines of zebrafish from the perspectives of histopathology, oxidative stress and immune response

As an organophosphate ester (OPE), triphenyl phosphate (TPhP) has been frequently detected in aquatic environments, and its environmental risk has been widely studied. The gills and intestines are the most important part of the mucosal immune barrier in fish as the first line of defense against the invasion of harmful substances. TPhP is more abundant in the gill and intestine of fish. However, knowledge of the toxic effects and potential mechanisms of TPhP on the intestine and gill is limited. Herein, the adverse effects of TPhP (0.01, 0.1 and 1 mg/L) on the gills and intestines of zebrafish after 75 days of exposure were investigated from the perspectives of histology, oxidative stress and immune level. The histological results of exposed zebrafish showed that TPhP caused significant damage to gills and intestines. TPhP significantly increased the activities of the antioxidant enzymes catalase (CAT) and glutathione s-transferase (GST), inducing oxidative damage to lipids, proteins, and DNA. Meanwhile, the immune function of the gills and intestines was significantly influenced by TPhP, as evidenced by the upregulation of the expression of interleukin-1β (IL-1β) and interleukin-6 (IL-6), upregulation of the content of complement 3 (C3) and complement 4 (C4), and downregulation of the activity of lysozyme (LZM) and the content of immunoglobulin M (IgM). Oxidative stress and the immune response were more severe in the gills. These findings indicate that TPhP, a typical OPE, caused tissue damage in aquatic organisms by inducing oxidative stress and immune damage and has strong environmental toxicity.

The two-way immunotoxicity in native fish induced by exudates of Microcystis aeruginosa: Immunostimulation and immunosuppression

Secondary metabolites of cyanobacterial blooms have caused serious risks to aquatic animals. The immune system is an important barrier for fish against pollutants in aquatic systems. The immunetoxic mechanism of the exudates of Microcystis aeruginosa (MaE) on fish was lacking due to the complex components of MaE. In this project, Sinocyclocheilus grahami was used as the model to study the immunotoxic effects of MaE and PHS (one of the main components of the MaE) in fish. The immunosuppression effects of MaE are mainly in, decreased head-kindey index, damaged tissue structure of head-kidney and downregulated NF-κB, IL-1β. PHS induce immunostimulation via, increasing spleen index, apparently increasing leucocytes, increasing the IgM and lysozyme levels in serum and skin mucus, upregulating protease in skin mucus, increasing pro-immunologic factors (IL-1β, IL-6, IL-8, IL-10, TNF-α and NF-κB), probably activating the TLRs/NF-κB, MAPK, FoxO1 and PPARγ signaling pathways. Therefore, our research identified potential data gaps that how the exudates of cyanobacteria induces immunostimulation and immunosuppression from immune organs level to skin mucus to blood cells to inflammatory factors to potential molecular initiating event of MaE and PHS. Further research is needed to obtain a deeper view of the molecular mechanisms involved in MaE and PHS immunotoxicity and its consequences in long-time exposures.

Alleviating the loss: A conical fish screen installation reduces native fish entrainment at a gravity‐fed water diversion

Abstract Each year, millions of fish are extracted from Australian waterways by the pumping and diversion of water into irrigation systems. Fish protection screens can help reduce these losses but are largely untested in Australian rivers. In this study, a large, gravity‐fed irrigation offtake on Gunbower Creek, Victoria, Australia, was investigated for fish and debris entrainment. Experiments were performed under screened and unscreened conditions across various river flows. Mark–release–recapture experiments were undertaken with fingerlings of two recreationally significant fish species, Murray cod (Maccullochella peelii) and golden perch (Macquaria ambigua), together with wild fish community assessments, to determine how effective the screen was at reducing fish entrainment into the irrigation channel. The mean percentage of recaptured fingerlings was significantly lower when the irrigation channel offtake was screened compared with unscreened. Entrainment of released fish into the irrigation channel was reduced by &gt;98%. Similarly, wild fish entrainment was significantly lower when the irrigation channel was screened. When screened, fewer wild species dominated the sampled fish community, and entrained fish were generally &lt;40 mm in length. Debris loads decreased significantly in the irrigation channel owing to the screen, indicating the economic benefits of fish screens. Implementing screens could aid in native fish conservation efforts in riverine environments.

Native fish abundance and habitat selection changes in the presence of nonnative piscivores

AbstractWe compared abundance patterns and developed resource selection models for imperilled native southwestern (USA) fishes in the presence and absence of Black Bass (Micropterus spp.) to evaluate how fishes alter their selection for habitats when sympatric with a nonnative piscivore. We collected data using snorkel surveys and in‐stream habitat sampling in Fossil Creek (AZ), upstream (native fish only) and downstream (native and nonnative fish) of a fish barrier. The abundance of all Roundtail Chub (Gila robusta), small (≤127 mm total length [TL]; vulnerable to predation) Sonora Sucker (Catostomus insignis) and Speckled Dace (Rhinichthys osculus) was significantly reduced, but the abundance of both small and large (&gt;127 mm TL; invulnerable to predation) Desert Sucker (Catostomus clarkii) was similar in sampling reaches with and without Black Bass. When sympatric with Black Bass, small Roundtail Chub increased their selection for riffles by 2.57 times and small Desert Sucker reduce their selection for pools by 6.90 times while also selecting for faster flow velocity and finer substrates in lotic mesohabitats. Large native fishes altered selection least, notwithstanding an increased selection for canopy cover in sampling reaches with Black Bass. Observed shifts in resource selection are consistent with predator avoidance strategies. Our study highlights the behavioural consequences of nonnative piscivores on native fish communities and stresses the importance of maintaining lotic mesohabitats as potential refugia for vulnerable native fishes when nonnative piscivores are present.

Baicalin suppressed necroptosis and inflammation against chlorpyrifos toxicity; involving in ER stress and oxidative stress in carp gills.

Chlorpyrifos (CPF) has caused large-scale pollution worldwide and posed a threat to non-target organisms. Baicalein (BAI) is a flavonoid extract with anti-oxidant and anti-inflammatory activities. The gills are the mucosal immune organ and the first physical barrier of fish. However, it is not clear whether BAI counteracts organophosphorus pesticide CPF exposure-caused gill damage. Therefore, we established the CPF exposure and BAI intervention models by adding 23.2 μg/L CPF in water and/or 0.15 g/kg BAI in feed for 30 days. The results showed that CPF exposure could cause gill histopathology lesions. Moreover, CPF exposure led to endoplasmic reticulum (ER) stress, caused oxidative stress and Nrf2 pathway activation, and triggered NF-κB-mediated inflammation reaction and necroptosis in carp gills. BAI adding effectively relieved the pathological changes, and lighten inflammation and necroptosis involving in the elF2α/ATF4 and ATF6 pathways through binding to GRP78 protein. Moreover, BAI could ease oxidative stress, but did not affect Nrf2 pathway in carp gills under CPF exposure. These results suggested that BAI feeding could alleviate necroptosis and inflammation against chlorpyrifos toxicity through elF2α/ATF4 and ATF6 axis. The results partially explained the poisoning effect of CPF, and showed BAI could be act as an antidote for organophosphorus pesticides.

Liver and Plasma Concentrations of Food Chemicals after Virtual Oral Doses Extrapolated Using in silico Estimated Input Pharmacokinetic Parameters to Confirm Reported Liver Toxicity in Rats.

The estimation of health risks of chemical substances was historically investigated using animal studies; however, current research focuses on reducing the number of animal experiments. The toxicity of chemicals in fish screening systems is reportedly correlated with their hydrophobicity. The inverse relationship between absorption rates (intestinal cell permeability) and virtual hepatic/plasma pharmacokinetics of diverse chemicals has been previously evaluated by modeling oral administration in rats. In the current study, internal exposures, i.e., virtual maximum plasma concentrations (Cmax) and areas under the concentration-time curves (AUC), of 56 food chemicals with reported hepatic lowest-observed-effect levels (LOELs) of ≤1000 mg/kg/day in rats were pharmacokinetically modeled using in silico estimated input pharmacokinetic parameters. After a virtual single oral dose of 1.0 mg/kg of 56 food chemicals, the output Cmax and AUC values in rat plasma generated by modeling using the corresponding in silico estimated input parameters were not significantly correlated with the reported hepatic LOEL values. However, significant inverse relationships between hepatic/plasma concentrations of selected lipophilic food chemicals (i.e., octanol-water partition coefficient logP >1) using forward dosimetry and reported LOEL values (≤300 mg/kg/day) were observed (n = 14, r = -0.52-0.66, p ≤ 0.05). This simple modeling approach, which uses no experimental pharmacokinetic data, has the potential to play a significant role in reducing the use of animals to estimate toxicokinetics or internal exposures of lipophilic food components after oral doses. Therefore, these methods are valuable for estimating hepatic toxicity by using forward dosimetry in animal toxicity experiments.

Ice processes in culverts with two fish passage designs: a case study in southern Quebec

According to Department of Fisheries and Oceans Canada, culverts and other stream crossings must be designed to ensure fish passage. The effects of ice processes on these fish passage designs have never been assessed. This study is the first to document ice processes on two different types of fish passage designs (streambed simulation and baffle). The results of a 2 year field monitoring campaign showed that the culvert simulating the streambed retains a natural ice regime, i.e., both freeze-up and break-up occurred concurrently with the rest of the stream, while multiple supercooling events were recorded under a thin ice cover. As for the culvert with baffles, it was observed that the ice cover formed earlier and stayed longer in the culvert, which can create a barrier for fish transiting through them.

Evaluation of a new practical low-cost method for prioritising the remediation of fish passage barriers in resource-deficient settings

A key challenge in fishery restoration strategies is prioritising fish passage remediation efforts to achieve optimal ecological and socio-economic outcomes. Various methodologies have been developed for assessing and prioritising the mitigation of fish passage barriers, but they have been designed for developed countries where site data and/or other resources are often readily available. We evaluated a new practical, low-cost basin-scale approach — referred to as the Fish Barrier Prioritisation Support System (FBPSS) — for assessing and prioritising the remediation of fish passage barriers of all types (i.e. large dams, small irrigation structures and road crossings) in resource-deficient settings, like those typical of developing countries. The FBPSS applies a five-stage decision-support framework to prioritise barriers for remediation based on geospatial, biological and socio-economic criteria. The stages involve identifying all potential barriers within the target basin using satellite imagery; conducting GIS analysis to rank the barriers for further investigation; field-validating the highest ranked barriers to ground-truth the GIS analysis results; identifying the highest priority field-validated barriers affecting fisheries productivity; and further refining the list according to socio-economic considerations. We applied the FBPSS to the Bago catchment in Myanmar as a case study, and then validated its effectiveness by comparing the fragmentation impacts (as measured by the Dendritic Connectivity Index) of the FBPSS-prioritised large dams with those of all large dams. The FBPSS successfully identified 876 potential barriers in the Bago catchment, and then systematically assessed these barriers using its filters to produce a prioritised list of 23 barriers for cost-effectively achieving optimal fishery and community benefits. The validation analysis revealed that the high priority FBPSS-combined barriers were responsible for 97–100% of the fragmentation of the combined barriers (with all large dams included). Our findings suggest that the FBPSS could be used as a practical decision support tool, in conjunction with expert knowledge, for prioritising the mitigation of fish passage barriers in resource-deficient settings. Future research could compare the results of the FBPSS with those of an optimisation model to assess how the two approaches perform under different scenarios, and to identify key modelling features that could potentially be integrated into the FBPSS.

Modern Sustainable Fish Screens: A Study on Developing Effective Communication with Water Users

Background: Recently, there has been a shift in strategic goals relating to water management in Australia, from water development to protecting and restoring environmental assets. Thus, there is a need to develop knowledge that accounts for the new realities of developing an effective communication channel with irrigators. Combining insights from two communication theories: the hierarchy of effects model, AIDA, and the diffusion of innovation (DOI) model, this article explores developing effective communication techniques (e.g., format, style, content, and source) and tools for Australian irrigators regarding adopting new sustainable technology—a modern self-cleaning fish screen. This study investigates irrigators’ communication preferences and innovation processes to understand to sketch foundational strategies for improving communication schemes. Methods: Data were collected through semi-structured in-depth interviews. Twenty-three irrigators in the Murray-Darling Basin, Australia’s primary food bowl, participated in the study. Constructivist grounded theory (CGT) was used to design and analyse the data. Results: The study explored the communications preferences of Australian irrigators and revealed insights into their preferred format, style, content, and source and how information is gathered and evaluated in the decision-making process. The results confirmed that the information must come from trusted sources, be grounded in research, provide hands-on observations/experiences, and focus on benefits for irrigators (i.e., improving irrigation efficiency) to be impactful. Broadly, this study contributes to the discussion of policy formulation, enhancing technology adoption in a broader setting and designing efficient and effective systems for engaging with Australian irrigators. Conclusions: To increase the likelihood of adopting fish screens, it is essential to implement targeted education and information programs and communications in appropriate formats with relevant content.