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Two laboratory studies evaluated small Chinook salmon (Oncorhynchus tshawytscha) (36-99 mm fork length (FL), 0.7%-26.7% tag burden) survival, tag retention, and growth (n = 539) and critical swimming speed ([U.sub.crit]; n = 241). Fish were implanted with a new active acoustic tag and compared with untagged controls at 12 and 17 [degrees]C. Across studies, no temperature differences were detected. All control fish survived. All tagged fish [greater than or equal to] 58 mm FL survived and retained their tags. Regression models predicted [greater than or equal to] 98.6% survival and retention for tagged fish [greater than or equal to] 58.6 mm FL or [greater than or equal to] 1.9 g (4.2% tag burden). No growth differences among treatments were identified. Spline regression analysis indicated [U.sub.crit] was similar for control and tagged fish that measured [greater than or equal to] 57.3 mm FL. We recommend tagging salmon [greater than or equal to] 59 mm FL or [greater than or equal to] 1.9 g ([less than or equal to] 4.2% tag burden), although the guideline should be confirmed in a field setting. Study results represent an important step towards using the new active tag in acoustic telemetry field studies that estimate short-term (30-day) survival of small salmonids. Deux etudes en laboratoire ont permis d'evaluer la survie, la retention d'etiquettes et la croissance (n = 539), ainsi que la vitesse de nage critique ([U.sub.crit]; n = 241) de petits saumons chinooks (Oncorhynchus tshawytscha, longueur a la fourche (LF) : 36-99 mm; fardeau de l'etiquette : 0,7-26,7 %). Une nouvelle etiquette acoustique active a ete implantee dans des poissons, qui ont ete compares a des temoins non etiquetes a 12 et 17 [degrees]C. Aucune difference n'a ete relevee entre les etudes en ce qui concerne la temperature. Tous les poissons temoins ont survecu. Tous les poissons etiquetes de LF [greater than or equal to] 58 mm ont survecu et conserve leur etiquette. Des modeles de regression ont predit des taux de survie et de retention de [greater than or equal to] 98,6 % pour les poissons etiquetes de LF [greater than or equal to] 58,6 mm ou de masse [greater than or equal to] 1,9 g (fardeau de l'etiquette : 4,2 %). Aucune difference sur le plan de la croissance n'a ete relevee entre les traitements. L'analyse de regression par spline fait ressortir des [U.sub.crit] semblables pour les poissons temoins et les poissons etiquetes de LF [greater than or equal to] 57,3 mm. Nous recommandons l'etiquetage de saumons de LF [greater than or equal to] 59 mm ou de masse [greater than or equal to] 1,9 g (fardeau [less than or equal to] 4,2 %), cette directive devant toutefois etre confirmee sur le terrain. Les resultats des etudes constituent un pas important vers l'utilisation de la nouvelle etiquette active dans des etudes de telemetrie acoustique de terrain qui estiment la survie a court terme (30 jours) de petits salmonides. [Traduit par la Redaction], Introduction Advancements in active acoustic telemetry technology (reduced tag size, improved power outputs, signal strength, and battery life) have allowed researchers to push the limits of acceptable size-at-tagging guidelines for [...]

Fish that undertake juvenile migration pass through habitats that vary in mortality risk. The ability to identify regions of persistently low survival would improve fishery management. We conducted a field study combined with predictive modeling of survival in downstream migrating juvenile sea lamprey using a new micro-acoustic telemetry tag designed for implantation into small, slender-bodied fishes. Detection data were collected from eight receivers placed across a coastal riverine–wetland–lake complex. Juvenile sea lamprey initiated downstream movement near nautical twilight, stopped frequently, and were more likely to move during high river discharge. Estimated survival was highest in the riverine reach, declined through the river–wetland complex, and dropped precipitously in the drowned rivermouth lake. However, the high transmission rate and resulting short battery life of the microtransmitters (as configured) likely resulted in missed detections in the lower reaches. Simulation analyses suggested survival estimation could be improved by increasing the number of tagged lamprey and staggering release locations. We offer practical recommendations for the use of this new transmitter in field studies with small anguilliform fish. [ABSTRACT FROM AUTHOR]

The potential effects of underwater anthropogenic sound and substrate vibration from offshore renewable energy development on the behavior, fitness, and health of aquatic animals is a continuing concern with increased deployments and installation of these devices. Initial focus of related studies concerned offshore wind. However, over the past decade, marine energy devices, such as a tidal turbines and wave energy converters, have begun to emerge as additional, scalable renewable energy sources. Because marine energy converters (MECs) are not as well-known as other anthropogenic sources of potential disturbance, their general function and what is known about the sounds and substrate vibrations that they produce are introduced. While most previous studies focused on MECs and marine mammals, this paper considers the potential of MECs to cause acoustic disturbances affecting nearshore and tidal fishes and invertebrates. In particular, the focus is on particle motion and substrate vibration from MECs because these effects are the most likely to be detected by these animals. Finally, an analysis of major data gaps in understanding the acoustics of MECs and their potential impacts on fishes and aquatic invertebrates and recommendations for research needed over the next several years to improve understanding of these potential impacts are provided. [ABSTRACT FROM AUTHOR]

To evaluate the efficiency of tagging juvenile European eels with implanted 12 mm passive integrated transponder (PIT) tags or Eel/Lamprey acoustic transmitters (ELATs), the authors studied tag retention, survival and growth of eels (7–25 g). Experimental eels were obtained from an eel farm, tagged and then released in a series of shallow dug‐out ponds with a surface area of c. 200 m2. Tagged and control eels were distributed evenly, with 50 tagged and 50 control eels in each of four ponds, giving a total of 200 tagged and 200 control eels mixed. After 76 days, the ponds were drained, and eels were sampled and measured. A total of 344 eels (86%) were recaptured, indicating high survival. Tag retention was 99% as only one of the recaptured PIT‐tagged eels had lost the tag and none of the ELAT tagged. The results demonstrated that tagging juvenile eels >16 cm with these small tags is indeed feasible. The growth of tagged and control fish was differentiated but generally low in length and negative in mass but did not differ between the three groups. [ABSTRACT FROM AUTHOR]

Global climate change, species invasion, and human activities such as the construction of hydraulic facilities are contributing to the worldwide degradation of fish stocks. As a pivotal environmental factor that affects fish migration and population distribution, the low‐velocity flow has not drawn enough attention despite its extensive presence in various ecoregions.To understand the behavioural profiles of fish in low‐velocity flow, we examined the motility and swimming performance of two representative cyprinids, grass carp (GC, Ctenopharyngodon idella) and silver carp (SC, Hypophthalmichthys molitrix), under the combined effect of different flow velocities and illuminance ranges.The two species were exposed to two flow velocities (0.15 and 0.25 m/s) and three illuminance ranges (100.0–0.9 lx, 300.0–2.5 lx, and 700.0–4.9 lx). A novel behavioural metric, composed of light preference, swimming speed, rheotaxis index (RI), swimming stability (SS), and the probability of moving forwards/backwards over a certain distance (PMf‐0.1 and PMb‐0.1), was developed to fully characterise the motion strategy of fish.By analysing the individual distribution in light gradient, we confirmed the scototaxis of GC and found the oscillating light preference in SC that changed from 84.41–10.18 to 6.00–2.08 lx and disappeared with increasing illuminance. The RI and SS increased at the fast flow velocity (0.25 m/s) for both species, and SC was more forward‐prone and more stable than GC. Despite the fluctuating light preference, the higher illuminances heightened the RI and SS in SC, while in GC, higher illuminances inhibited the SS and had no impact on the RI. The results of PMf‐0.1 and PMb‐0.1 indicated that a higher flow velocity could facilitate the temporary upstream swimming in both species, while illuminance could only promote the same effect in SC.Finally, our study proposed possible manoeuvres in fine‐scale spatio‐temporal scenarios such as attraction flow and non‐traditional passages and provided valuable insights into fish community dynamics, laying the groundwork for alleviating the threat from invasive species and for future fish population recovery. [ABSTRACT FROM AUTHOR]

Acoustic emissions from current energy converters remain an environmental concern for regulators because of their potential effects on marine life and uncertainties about their effects stemming from a lack of sufficient observational data. Several recent opportunities to characterize tidal turbine sound emissions have begun to fill knowledge gaps and provide a context for future device deployments. In July 2021, a commercial-off-the-shelf hydrophone was deployed in a free-drifting configuration to measure underwater acoustic emissions and characterize a 25 kW-rated tidal turbine at the University of New Hampshire's Living Bridge Project in Portsmouth, New Hampshire. Sampling methods and analysis were performed in alignment with the recently published IEC 62600-40 Technical Specification for acoustic characterization of marine energy converters. Results from this study indicate acoustic emissions from the turbine were below ambient sound levels and therefore did not have a significant impact on the underwater noise levels of the project site. As a component of Pacific Northwest National Laboratory's Triton Field Trials (TFiT) described in this Special Issue, this effort provides a valuable use case for the IEC 62600-40 Technical Specification framework and further recommendations for cost-effective technologies and methods for measuring underwater noise at future current energy converter project sites. [ABSTRACT FROM AUTHOR]

Turbulence in a channel flow with a fully transpired wall has been investigated experimentally. Two-dimensional particle image velocimetry is used to measure the instantaneous flowfields within the channel for two different porous surfaces: a 6.35-mm honeycomb and a 3.175-mm honeycomb. The 6.35-mm honeycomb creates a larger fluctuation of the injection velocity than the 3.175-mm honeycomb by a factor of 1.7. The boundary conditions on the porous surface are very important to the internal core flow evolution and flow pattern. For a coarse porous surface (the 6.35-mm honeycomb with higher perturbation level on the transpiration surface), the mean flow differs significantly from the classical laminar solution and computational results, and much more turbulent shear stress is indicated. However, with small pore size (the 3.175-mm honeycomb, with relatively lower perturbation level on the surface), the mean velocity profiles are very close to the analytical laminar solution for a considerable downstream length, and the turbulent shear stress is much smaller than in the first case. Therefore, profound modification of the flow structure can occur due to the effect of nonideal wall boundary conditions on the porous surface.

In this paper, laccase was immobilized with the adsorption-crosslinking method in which biochar was used as the carrier and glutaraldehyde was used as the crosslinking agent. Firstly, the optimal immobilization conditions and optimal operating conditions were investigated, and then the stability of both free laccase and immobilized laccase was compared. Finally, the 2,4-dichlorophenol contaminated soil was remedied with both free laccase and immobilized laccase, and the improvement on the remediation of the contaminated soil by immobilized laccase was analysed through the ecological evaluation. The results showed that in the optimal immobilization condition, the biochar with a particle size of 30 mesh should be selected, and glutaraldehyde with a volume fraction of 4% and 20 mL of laccase solution should be added to complete the 6-hour adsorption operation and 4-hour crosslinking operation. The stability of immobilized laccase was better than that of free laccase, and the thermal deactivation kinetic equation for the free laccase was lnA = −0.7657t + 0.4344 and the thermal deactivation kinetic equation for the immobilized laccase was lnA = −0.1048t + 0.0608, respectively. The degradation ability of immobilized laccase for 2–4 dichlorophenol was better than that of free laccase. The degradation rate of 2,4-dichlorophenol was 44.4% in the free laccase group and 64.6% in the immobilized laccase group. The ecological evaluation showed that the biochar-immobilized laccase had a positive effect on the soil ecological environment in the remediation process of the soil and can improve the remediation of the contaminated soil to some extent. [ABSTRACT FROM AUTHOR]

In order to solve the problem of heavy metal-organic compound soil pollution, in this paper, we developed a highly efficient electro kinetic-laccase combined remediation (EKLCR) system. The results showed that the EKLCR system had an obvious migration effect on heavy metals (copper and cadmium) and good migration-degradation effect on phenanthrene. The migration rates of copper and cadmium were 48.3% and 40.3%, respectively. Especially, with the presence of laccase, the removal rate of phenanthrene on Cu2+-contaminated soil was higher than that of Cd2+-contaminated soil due to the significant effect of heavy metals on the enzymatic activity of laccase. The average migration-degradation rate of phenanthrene by EKLCR system was 45.4%. Finally, gas chromatography-mass spectrometry (GC/MS) was used to analyze the degradation intermediates of phenanthrene in the soil, which included 9,10-Phenanthrenequinone, phthalic acid, and 2,2-Biphenyldicarboxylic Acid. In addition, we give the possible degradation pathways of phenanthrene, 2,2-Biphenyldicarboxylic Acid is further degraded to produce phthalic acid. The products of the phthalic acid metabolic pathway are protocatechuic acid, pyruvic acid or succinic acid, the final products of these organic acids are carbon dioxide and water. [ABSTRACT FROM AUTHOR]

High-energy rechargeable lithium metal batteries have been intensively revisited in recent years. Since more researchers started to use pouch cell as the platform to study the fundamentals at relevant scales, safe testing and handling of lithium metal and highenergy lithium metal batteries have become critical. Cautions and safety procedures are needed when handling cycled pouch cells with pulverized lithium metal particles inside. From cell design, electrode preparation, cell fabrication to testing procedure, this work aims to discuss the possible root causes that may initiate cell internal short circuit and raise safety concerns. Safe transfer, disassembly and disposal of cycled Li metal pouch cells are also discussed. The insights provided in this article are applicable for the research on high-energy lithium-ion batteries as well and may inspire more safety strategies to accelerate research innovation by using large-format batteries as the testing vehicle and conduct the research safely. [ABSTRACT FROM AUTHOR]

Recently, an acoustic microtag, called the Eel–Lamprey Acoustic Tag (ELAT), was developed for use in juvenile American Eel Anguilla rostrata and Pacific Lamprey Entosphenus tridentatus. The ELAT (12.0 × 2.0 mm; 0.088 g in air) has the potential to be used to study other small‐bodied fishes. In this pilot study, juvenile Chinook Salmon Oncorhynchus tshawytscha 52–99 mm fork length (FL) were surgically implanted with an ELAT (n = 99) or remained untagged (control; n = 101). Fish were held for 30 d to evaluate survival, tag retention, and growth. Survival did not differ significantly between control (n = 98 or 97.0%) and tagged fish (n = 95 or 95.9%). Logistic regression analysis suggested that survival was influenced by initial FL and tag burden. Mortalities only occurred in tagged fish with initial FLs of ≤65 mm (FL range = 57–65 mm; tag burdens = 3.8–5.9%). However, a tagged fish with an initial FL of 62 mm or an initial tag burden of 4.1% (FL range = 58–64 mm) was predicted to have a 90% chance of survival, and the smallest fish that survived the study was 54 mm FL (1.8 g; tag burden = 4.9%). Tag retention was high (99%), with only one fish expelling an ELAT during the study. Control fish grew slightly larger than the tagged individuals, but differences in final pooled FLs and weight gains were not significant. Our results demonstrate the successful surgical implantation of the ELAT into Chinook Salmon as small as 54 mm FL (1.8 g). [ABSTRACT FROM AUTHOR]

Egg and larval fish drifting downstream are likely to encounter river infrastructure leading to mortality. Elevated fluid shear is one likely cause. To confirm this and determine tolerable strain rates resulting from fluid shear, egg and larvae of three Australian species were exposed to a high-velocity, submerged jet in a laboratory flume. Mortality was modelled over a broad range of strain rates, allowing critical thresholds to be estimated. Eggs were very susceptible to mortality at low strain rates and 100% of golden and silver perch died once strain rate exceeded 629 and 148 s–1 respectively. Larvae were less vulnerable than eggs, but mortality increased at higher strain rates and at younger ages. Most ages of larvae will be protected if strain rate does not exceed 600 s–1, although a lower guideline of less than 400 s–1 may be needed in areas where very early stage Murray cod larvae drift. Golden perch and silver perch were not susceptible to shear once maturity reached ~25 days post-hatch (nearing juvenile metamorphosis). The thresholds described here will prove useful when refining design and operational guidelines for hydropower and irrigation infrastructure to improve fish survival. Eggs and larvae of three fish species were exposed to different elevated fluid shear levels at a high-velocity jet in a laboratory flume. Eggs were very susceptible to mortality at low strain rates, whereas larvae were typically most vulnerable at higher strain rates and at younger ages. Knowing such thresholds can assist designing and operating river infrastructure to protect fish. [ABSTRACT FROM AUTHOR]

Irrigation modernisation is booming globally because of the increasing demand on water and food. However, irrigation infrastructures can injure fish or entrain them into irrigation water. Screening is an effective method to mitigate fish entrainment. In this study, two autonomous sensor devices, developed and manufactured at Pacific Northwest National Laboratory (Sensor Fish and its miniaturised version, Sensor Fish Mini) were deployed to evaluate the physical and fish passage conditions of a unique horizontal, flat-plate fish and debris screen (known as the Farmers Screen) that was installed in Oregon, USA. Only 1 of the 27 Sensor Fish Mini releases had a severe acceleration event, whereas 0 of the 37 Sensor Fish releases had severe events. The rates of severe events and amplitudes of accelerations at the Farmers Screen were significantly lower than those at other hydraulic structures, including a fish-friendly surface weir that recorded nearly 100% fish survival. Overall, the results indicated that the Farmers Screens can provide safe downstream passage for fish at irrigation diversions. This study also demonstrated that the Sensor Fish technology, including Sensor Fish Mini, is a suitable technology for evaluating irrigation structures and providing important information for the development of sustainable irrigation. Irrigation modernisation is booming globally because of the increasing demand on water and food. However, irrigation infrastructures can injure fish or entrain them into irrigation water. Screening is an effective method to mitigate fish entrainment. Using two sensor devices we demonstrated that a unique horizontal screen can provide safe downstream passage for fish at irrigation diversions. [ABSTRACT FROM AUTHOR]

• The first physical & biological evaluation of hydro turbines in Lower Mekong River. • Testing was conducted on an older 17.5-MW turbine and a newer 40-MW turbine. • The newer turbine had fewer occurrences of severe acceleration events. • The newer turbine had better pressure environment for fish during runner passage. • This study can be used to guide the design of new hydropower in the region. The Mekong River is one of the most biodiverse rivers on Earth. Many communities located near the river rely on fisheries for sustenance and economics. Along the Mekong River mainstem there are plans for 11 new hydropower projects, with potentially several hundred smaller projects along tributaries. To understand the hydraulic conditions at existing dams in the region, Sensor Fish were deployed at Nam Ngum Dam in Laos. The data collected by Sensor Fish can be used to predict fish injury/mortality if there is a dose-response relationship for the species of interest. The Sensor Fish were released through two units—Unit 1, an older 17.5-MW Francis turbine, and Unit 4, a newer 40-MW Francis turbine. Comparisons were made between the Sensor Fish measurements at Nam Ngum to those from four hydroelectric dams in the U.S. Between the newer and older turbine units tested at Nam Ngum, the newer Unit 4 had a higher median nadir pressure of 126 kPaA compared to 99 kPaA. With respect to both pressure and acceleration, the older Unit 1 had more severe hydraulic conditions. By understanding the physical conditions within existing hydropower projects, and the potential ecological impact those conditions could have on the local fauna, better informed decisions can be made regarding project operations. The results from this study can also be used to guide the engineering design of new hydropower turbines that will improve ecological conditions. [ABSTRACT FROM AUTHOR]

In order to understand the interaction between surface water and groundwater in Qingshuihe Basin of Chongli Area, the environmental isotopic D, 18O and 222Rn in surface water and groundwater have been analysis, the study results show that: the calculation results based on the D and 18O, the surface water in middle stream of Donggou River has been recharged by groundwater and river water upstream, the percentage of groundwater recharge is 56%; the calculation results based on the 222Rn, the average seepage rate of surface water is 27.8 m3/d/m in the upstream section, and the average recharge rate of groundwater is 17.6 m3/d/m. It is concluded that, the groundwater and surface water interaction is the main characteristics and processes of water cycle in Qingshuihe Basin, and groundwater recharge is the main sources of surface water in draught seasons. [ABSTRACT FROM AUTHOR]

The effect of the fish body on the source level and beam pattern of an acoustic fish tag signal was investigated through laboratory experiments and an analytical method. In laboratory experiments, the source level and beam pattern were measured in both a tag-only group and a tag-in-fish group. In the analytical method, both forward and backward scattering were calculated by assuming the acoustic tag was a point source and the swimbladder was an air-filled prolate spheroid. The mean source level of five tested tags decreased by ∼4 dB after implantation in fish bodies, which is important for designing fish migration studies using acoustic telemetry. [ABSTRACT FROM AUTHOR]

The development of flexible and stretchable sensors has been receiving increasing attention in recent years. In particular, stretchable, skin-like, wearable sensors are desirable for a variety of potential applications such as personalized health monitoring, human-machine interfaces, and environmental sensing. In this paper, we review recent advancements in the development of mechanically flexible and stretchable sensors and systems that can be used to quantitatively assess environmental parameters including light, temperature, humidity, gas, and pH. We discuss innovations in the device structure, material selection, and fabrication methods which explain the stretchability characteristics of these environmental sensors and provide a detailed and comparative study of their sensing mechanisms, sensor characteristics, mechanical performance, and limitations. Finally, we provide a summary of current challenges and an outlook on opportunities for possible future research directions for this emerging field. [ABSTRACT FROM AUTHOR]

Abstract Siphon turbines are an attractive type of small-scale hydropower turbines because they can be retrofitted into existing structures where there is already a drop in water elevation. A siphon turbine conveys water from an upper reservoir to a lower reservoir through the use of a siphon structure that goes over the top of the dam. A small, neutrally buoyant autonomous sensor package known as a Sensor Fish was deployed through a siphon turbine at the Head of the U Hydroelectric Project in Idaho, USA. Comparisons were made between the siphon turbine in this study and other low-head turbines that have been studied using Sensor Fish. The Sensor Fish measurements indicate that this siphon turbine can generate nadir (i.e., minimum) pressures during runner passage of 22.4 kPaA, which is much lower than those of other low-head turbine types that have been studied using Sensor Fish and could be potentially harmful to fish species susceptible to barotrauma injury. Severe acceleration events occurred in the wicket gate and runner regions at rates of 12% and 47% respectively. These numbers are comparable or lower than other low-head turbines that have been studied with Sensor Fish. Due to the low nadir pressures measured, stakeholders should determine the presence of any fish species-of-concern in the area that are susceptible to barotrauma, and if so, methods to avoid or reduce fish entrainment such as screening technologies or diversions should be investigated. Highlights • Sensor Fish used to characterize hydraulic conditions through a siphon turbine. • Nadir pressures measured during runner passage were very low (22.4 KPaA). • Over 50% of releases experienced at least one occurrence of high acceleration. • Data can be used to guide cleaner power production from low-head hydropower. [ABSTRACT FROM AUTHOR]

Surface bypasses are downstream migration structures that can help reduce hydropower-induced damage to migrating fish. However, no comprehensive design concept that facilitates good surface bypass performance for a wide range of sites and species is available. This is why fish-passage efficiencies at recently built bypass structures vary widely between 0% and up to 97%. We reviewed 50 surface bypass performance studies and existing guidelines for salmonids, eels and potamodromous species to identify crucial design criteria for surface bypasses employed in North America, Europe and Australia. Two-tailed Pearson correlation of bypass efficiency and bypass design criteria shows that bypass entrance area (r = 0.3300, P = 0.0036) and proportion of inflow to the bypass (r = 0.3741, P = 0.0032) are the most influential parameters on bypass efficiency. However, other parameters such as guiding structures (P = 0.2181, ordinary Student's t -test) and trash-rack spacing (r = –0.1483, P = 0.3951, Spearman correlation), although not statistically significant, have been shown to have an effect on efficiency in some studies. The use of different performance criteria and efficiency definitions for bypass evaluation hampers direct comparison of studies and, therefore, deduction of design criteria. To enable meta-analyses and improve bypass design considerations, we suggest a list of standardised performance parameters for bypasses that should be considered in future bypass-performance studies. Efficient bypasses are necessary to ensure safe downstream passage of migrating fish at hydropower plants. We reviewed literature for efficient design criteria of surface bypasses and suggest a list of parameters for bypass-performance studies. Considering this list in future bypass-performance studies can help perform meta-analyses on bypass performance and improve bypass design considerations. [ABSTRACT FROM AUTHOR]

Knowing the kinds of physical stress experienced by fish passing through hydropower turbines can help optimise technologies and improve fish passage. This paper assesses the hydraulic conditions experienced through three different low-head turbines (a very low head (VLH), Archimedes screw and horizontal Kaplan turbine), taken using an autonomous sensor. In total, 127 Sensor Fish deployments were undertaken across all three turbines, generating 82 valid datasets. Decompression was rare at the VLH and screw turbines and rarely fell more than 10 kPa below atmospheric pressure. In contrast, the Kaplan was capable of generating pressures as low as 55.5 kPa (~45 kPa below atmospheric pressure), over shorter periods of time. More severe ratios of pressure changes could, therefore, be expected for both surface- and depth-acclimated fish at the Kaplan than at the other turbines. Strike was another possible source of fish injury (detected in 69–100% of deployments), and although strike severity was highest at the Kaplan, strike was more likely to be encountered at the screw and VLH than the Kaplan turbine. Shear occurred only near the blades of the Kaplan, and not at severe levels. The results demonstrated that low-head hydropower facilities are not without their risks for downstream migrating fish. Hydraulic and physical conditions through three different low-head turbines (very low head (VLH), Archimedes screw and horizontal Kaplan) were assessed using an autonomous sensor. All turbines displayed conditions that could injure fish migrating downstream. Strike events were common at the VLH and screw turbine, and decompression, strike and shear observed at the Kaplan turbine. [ABSTRACT FROM AUTHOR]

Abstract: The current minimum size for tagging Chinook Salmon Oncorhynchus tshawytscha in the Columbia River basin with acoustic transmitters is ≥95 mm FL. Using a newly developed cylindrical microacoustic transmitter (AT; weight in air, 0.22 g), our objective was to evaluate the minimum size of Chinook Salmon for tagging. We measured Chinook Salmon survival and the retention of transmitters and viscera after their exposure to rapid decompression (n = 399) or shear forces (n = 308) that simulated dam passage. Fish (69–107 mm FL) were implanted with an AT (AT‐only) or an AT and a PIT tag (weight in air = 0.10 g; AT+PIT) through a 3‐mm incision with no sutures, or did not receive an incision or tag (untagged control fish). Tag burden averaged 2.9% (range, 1.4–6.2%) in the AT‐only group and 4.2% (range, 2.0–7.9%) in the AT+PIT group. Proportional survival and the retention of transmitters and viscera was significantly lower for AT‐only (0.70) and AT+PIT (0.54) fish than for untagged fish (0.85) after their exposure to pressure change scenarios. No transmitters were fully expelled, but 9% of AT‐only and 22% of AT+PIT salmon had protruding viscera or transmitters. Following shear exposure, the proportional survival and retention of transmitters and viscera was significantly lower for AT‐only (0.70) and AT+PIT (0.61) fish than for untagged fish (0.98). Visceral expulsion was attributed to 90% and 93% of mortal injuries in AT‐only and AT+PIT fish, respectively. In both tests the tagged fish suffered more mortal injuries and death than did untagged fish over the range of tag burdens tested, and no tag burden threshold below which tagged and untagged fish performed similarly was found. As such, a generalized linear model that included tag burden as a predictor variable provided the best fit to the survival data. Without a significant tag burden threshold, we recommend the minimum size for tagging Chinook Salmon using the transmitters and PIT tags evaluated, applied with a 3‐mm incision and no sutures, should remain at 95 mm FL. [ABSTRACT FROM AUTHOR]

Machine learning classification and regression algorithms were applied to calibrate the localization errors of a time-difference-of-arrival (TDOA)-based acoustic sensor array used for tracking salmon passage through a hydroelectric dam on the Snake River, Washington, USA. The locations of stationary and mobile acoustic tags were first tracked using the approximate maximum likelihood algorithm. Next, ensembles of classification trees successfully identified and filtered data points with large localization errors. This prefiltering step allowed the creation of a machine-learned regression model function, which decreased the median distance error by 50% for the stationary tracks and by 34% for the mobile tracks. It also extended the previous range of sub-meter localization accuracy from 100 m to 250 m horizontal distance from the dam face (the receivers). Median distance errors in the depth direction were especially decreased, falling from 0.49 m to 0.04 m in the stationary tracks and from 0.38 m to 0.07 m in the mobile tracks. These methods would have application to the calibration of error in any TDOA-based sensor network with a steady environment and array configuration. [ABSTRACT FROM AUTHOR]