Mature Size Research Articles

The interaction of relative age with maturation and body size in female handball talent selection.

The relative age effects (RAEs) and biological maturation are two distinct factors that have been identified to affect talent identification and selection. Previous research has suggested that talent selection should include sport-specific technical tasks instead of body size and/or physical test measurements, assuming that the technical tasks are less influenced by variations in maturation. Our purpose was to examine the prevalence of RAEs and to assess biological maturity, body size, and body composition within a single talent selection program for female handball players. Team coaches' recommendations, handball-specific drills, and in-game performance were the selection criteria. Birth distribution of all U14 female handball players were analysed (N = 3198) grouped in two-year age cohort. Measurements of body size, body composition (InBody 720), and bone age were performed in all players who were selected to participate in the selection program (n = 264) (mean±sd age: 13.1±0.6 years) and in a sample of not-selected players (n = 266) (mean±sd age: 13.2±0.6 years). Players were grouped in quarter-year intervals based on their date of birth. Chi-square was used to examine quartile distributions, differences between quartiles were tested with one-way analysis of variance, whereas differences between the selected and not-selected groups were examined with independent sample t-test (Cohen d effect size). Binary logistic regression was used to determine the effects of the predictors on the selection. In terms of all registered players, there was no difference in birth distribution. RAEs appeared at the first selection stage and were evident at all following stages. Quartiles differed only between the first and the last quartiles in body size and muscle mass. Only bone age differed between consecutive quartile or semi-year groups. Body size, body composition, and maturity had a significant, but of moderate power, effect on the selection. Larger body height increased the likelihood of selection by about 12%, larger muscle mass by 12% to 25%, larger bone age by 350-400%, while larger percent body fat decreased selection chances by 7%. The sport-specific criteria could not eliminate the prevalence of the RAEs. Relative age was connected to bone age, but not convincingly to body size and muscle mass. Although bone age had the largest effect on the selection, this was not associated with larger body size or muscle mass. Early maturation increased selection chances mainly during the coaches' subjective evaluation, but not convincingly when sport-specific tasks were applied. Given that differences were mostly evident between players of more than 1.5-year variation in their chronological age, one-year age cohorts within talent selection or the rotation of the cut-off dates of the bi-annual age grouping could be a promising strategy while also including maturation status and relative age in performance evaluations.

Influence Of Metamemory Maturity On Arabic Vocabulary Size Achievement Of Pre-University Student In Selangor/ تأثير نضج ما وراء الذاكراة على تحصيل حجم المفردات العربية لدى طلبة ما قبل الجامعة في سلانجور

The research investigates the relationship between metamemory maturity and achievement of Arabic vocabulary size among STAM students in Selangor. The research sample consisted of 185 male and female students of Sijil Tinggi Agama Malaysia (STAM) in different government-assisted religious schools (SABK) in Selangor. This study uses a survey design of 271 students in Selangor. A total of 185 students were selected as respondents through the proportional strata sampling technique. The study utilized a survey design and employed descriptive and inferential analyses. Two instruments were used: a questionnaire on metamemory maturity and a test on knowledge of Arabic vocabulary size. Findings revealed a medium level of metamemory maturity (mean score: 3.79) and Arabic vocabulary size achievement (mean score: 77.7). A significant correlation (r = 0.18) was found between metamemory maturity and vocabulary size achievement. Regression analysis indicated that metamemory maturity contributes significantly (β=0.184, t=2.538, p=0.012), explaining 3.4% of the variance in Arabic vocabulary size mastery. The study suggests that metamemory maturity influences students' Arabic vocabulary size mastery.

Slight and hidden hearing loss in young rats is associated with impaired recognition memory and reduced myelination in the corpus callosum.

Slight and hidden hearing loss in children have been linked to cognitive and social difficulties, and yet the neurobiological mechanisms behind these issues remain poorly understood. Most animal models focus on severe hearing loss, leaving the effects of hidden or slight hearing loss largely unexplored. To uncover the neural mechanisms connecting slight/hidden hearing loss to cognitive and social challenges, we induced hearing loss in young (4-week-old) Wistar rats through noise exposure. We then examined cognitive function (object recognition test) and social behavior (juvenile play behavior and social interaction). Changes in brain anatomy were assessed using cortical thickness and hippocampal size measurements, while (immuno)histochemical staining investigated neuronal circuitry maturation (myelin basic protein, parvalbumin, and perineuronal nets) and neurogenesis (doublecortin). Noise-exposed rats displayed slight high-frequency hearing loss (around 20 dB) and hidden hearing loss at other tested frequencies. This slight/hidden hearing loss was associated with impaired object recognition but did not alter social behavior. Slight/hidden hearing loss was associated with reduced myelin basic protein expression in the corpus callosum but no other alterations in cortical thickness, hippocampal size, or other markers of maturation and neurogenesis were found. These findings show that even slight/hidden hearing loss can lead to subtle brain alterations tied to cognitive deficits. This study emphasizes the need for further research to fully understand the brain changes associated with slight/hidden hearing loss and to pinpoint the mechanisms connecting these changes to behavioral deficits. This information is crucial to develop interventions to prevent the cognitive and social consequences of hearing loss. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

NF-кB promotes aggresome formation via upregulating HDAC6 and in turn maintaining Vimentin cage.

Proteasome inhibitors have been applied to anticancer therapy by accumulating toxic misfolded proteins. However, chemical inactivation of proteasome generates aggresome, a Vimentin cage-enclosed subcellular structure quarantining HDAC6-Dynein-transported misfolded proteins before the protein toxicants are degraded by autophagy. Hence, aggresome may attenuate proteasome inhibitor drugs-induced cytotoxicity. To solve the problem, it is imperative to characterize how cells assemble aggresome. By examining aggresomes in six cell lines, A549 cells were selectively studied for their bigger cell size and moderate aggresome forming activity. Aggresome grew in size upon continuous exposure of A549 cells to proteasome inhibitor MG132, and reached a mature size around 16th to 24th hour of treatment. Mechanistic studies revealed that NF-кB translocated to nucleus in MG132 treated cells, and chemical activation or knockdown of NF-кB enhanced or prohibited aggresome assembly. Further analyses showed that NF-кB upregulated HDAC6, and HDAC6 maintained Vimentin cage by interacting with Vimentin p72, a key modification of the intermediate filament contributing to aggresome formation. Remarkably, chemical inactivation of NF-кB synergized MG132-induced cell mortality. All the findings suggest that NF-кB dictates aggresome assembly via upregulating HDAC6, and NF-кB inhibitor may serve as a potential drug potentiating proteasome inhibitor medicine-induced cytotoxicity during the treatment of cancer cells.

Is my fishing gear impacting the habitat? An impact assessment in four fisheries in the Northwest Mexican Pacific

The impacts of fishing activities on habitats for commercially important species may, directly and indirectly, influence species and associated communities. These effects include those on target species, bycatch species, habitats, etc. In this study, the impact of small-scale fisheries on habitats was evaluated in four fishing communities from the Northwest Mexican Pacific. The species and size selectivity of several fishing gear were evaluated, and the spatial distribution of catches was studied to assess the impacts of fishing gear using a Consequence Spatial Analysis (CSA). Our results showed that in finfish fisheries from Guaymas and Isla Natividad, the catch of the target species represents more than 75% of the total catch and in El Rosario, the catch represents less than 50%. We assessed 42 habitat types in four communities, which were qualified with low-risk scores. The fishing gears used to target commercial species are selective to optimal sizes above their maturity size. The results contribute to improving management in data-poor fisheries by evaluating the impacts of fishing on habitats and discussing their relevance for implementation.

The Relationship Between Maturation Size and Maximum Tree Size From Tropical to Boreal Climates.

The fundamental trade-off between current and future reproduction has long been considered to result in a tendency for species that can grow large to begin reproduction at a larger size. Due to the prolonged time required to reach maturity, estimates of tree maturation size remain very rare and we lack a global view on the generality and the shape of this trade-off. Using seed production from five continents, we estimate tree maturation sizes for 486 tree species spanning tropical to boreal climates. Results show that a species' maturation size increases with maximum size, but in a non-proportional way: the largest species begin reproduction at smaller sizes than would be expected if maturation were simply proportional to maximum size. Furthermore, the decrease in relative maturation size is steepest in cold climates. These findings on maturation size drivers are key to accurately represent forests' responses to disturbance and climate change.

BIOLOGI REPRODUKSI IKAN BALOBO (Hyporhamphus quoyi) HASIL TANGKAPAN JARING BALOBO DI PERAIRAN DESA APARA KABUPATEN KEPULAUAN ARU

Garfish is a small pelagic species that has long been used as a raw material for dry fish production from Maluku called balobo dried fish. Many species of Garfish have been exploited but the species Hyporhamphus quoyi has not much been informed. This study aims to understand the reproductive aspects of Garfish consisting of measuring the sex ratio, changes in the gonad maturity stages (GMS) and counting the size of the first size gonad maturity. Located at the waters of Apara village, Aru Archipelago Regency, this study was conducted using a balobo net from November to December 2023. The catches were identified, measured its fork length (FL cm) and dissected to examine its reproductive organ. The Chi-squire heterogeneity test was occupied to measure sex ratio at different sizes. GMS was accessed based on the morphology of testis and ovary. First size maturity was calculated using Spearman-Karber method. The target fish captured by the balobo net consists of the Hemirhamphus far and Hyporhamphus quoyi. The ratio of male and female Hyporhamphus quoyi is unbalanced (c2=8.36; df=1; P=0.0038) but the sex ratio based on the length distribution of fish is not significantly different ( c2=6.92; df=6; P =0.328). Changes in GMS during the observation period indicate the occurrence of spawning in November. Balobo fish reach gonad maturity at FL = 24.9cm for females and FL = 26.8cm for males. Since the optimum size of the fish Hyporhamphus quoyi caught by balobo net is 27cm, this net produced legal sized of fishes.

Fish with slow life-history cope better with chronic manganese exposure than fish with fast life-history.

Animals with different life-history types vary in their stress-coping styles, which can affect their fitness and survival in changing environments. We studied how chronic exposure to manganese sulfate (MnSO4), a common aquatic pollutant, affects life-history traits, physiology, and behavior of zebrafish (Danio rerio) with two life-history types: fast (previously selected for fast juvenile growth, early maturation, and small adult body size) and slow life histories (selected for slow juvenile growth, late maturation, and large adult body size). We found that MnSO4 had negative effects on growth and condition factors, but the magnitude of these effects depended on the life-history type. Individuals with fast life histories were more susceptible to MnSO4 than fish with slow life histories as they had lower growth rate, condition factor and feeding probability in high MnSO4 concentrations. Our results demonstrate that MnSO4 can impair fish performance, and life-history variation can modulate the stress-coping ability of individuals.

Some biological aspects of chacunda gizzard shad, Anodontostoma chacunda (Hamilton, 1822) from the Bay of Bengal, Bangladesh

Anodontostoma chacunda is a commercial fish species in the market and is usually consumed in fresh, smoked, and dried forms. This study investigated the population structure, length-weight relationships (LWR), condition factor (KF), size at sexual maturity (Lm), and breeding season of A. chacunda in the Bay of Bengal, Bangladesh, using the data collected from January to December 2020. A total of 1061 individuals were collected in the sampling period with the help of fishers. Total length (TL) and body weight (BW) were measured using a measuring board and an electronic balance. The TL ranged from 12.50 to 26.70 cm. The allometric coefficient (b) value was 3.34, indicating positive allometric growth in this species. The fish is in good condition, evidenced by its condition factor (KF) ranging between 0.88 and 1.73. Maturity size ranged from 15.40 to 16.80 cm (TL) based on three distinguished models. Spawning time lasts from January to May and from September to December. The peak spawning time was December of A. chacunda in the Bay of Bengal. This information could prove valuable for fisheries researchers and biologists, facilitating efforts toward the conservation and sustainable management of this species.

Reproductive Cycle, Sexual Maturity and Fecundity of Mullus barbatus (Linnaeus, 1758)

The study aims to determine the reproductive biology and 50% maturity length of red mullet fish (M. barbatus) by taking monthly samples in the Black Sea between October 2017 and September 2018. It was determined that the difference between the sexes of the samples (female: 936, male: 454) was significant and methods used to determine the reproductive period (GSI, macroscopic analysis of gonads, microscopic analysis of gonads) matched the monthly analysis results. The reproduction period of red mullet was between April and August in the Black Sea, but spawning occurred between May and August according to the histological method. Considering the oocyte structures and oocyte diameter distributions in the histological sections, it was observed that the red mullet in the Black Sea was a multiple spawner and had an indeterminable fecundity. Mean FB hydrated oocytes and mean FR hydrated eggs of red mullet during the spawning period were calculated as 4813.0±5324.0 and 124.6±124.1 g-1, respectively. The maturity sizes of females and males were 12,40 cm and 11,29 cm, respectively. As a result, for the sustainability of red mullet stocks in the Black Sea, a new management plan should be established, considering spawning periods, reproductive strategy, and maturity sizes.

Reproductive Biology Status Reproductive Biology Status of Moonfish (Mene maculata) in Palabuhanratu Bay during West Monsoon

The moonfish (Mene maculata) is a demersal fish with important ecological and economic value. The high use of pitcher fish as food fish has the potential to disrupt reproductive patterns, recruitment and stock availability of pitcher fish resources, for which information on reproductive biology is minimal during the west monsoon. This research aims to analyze the reproductive biology status of moonfish in Palabuhanratu Bay. The research period took place from September 2021 to February 2022 (representing the west monsoon), with a sample of 522 fish. Fish samples were taken using a simple random sampling method at Palabuhanratu Nusantara fishing port. The data was analysis to obtain the sex ratio, allometric growth pattern, spawning season, the reproductive potential, and the size at maturity. Results shown that the sex ratio was 1:0.76, which is dominated by male fish. Moonfish have a negative allometric growth pattern. The peak of spawning season during the study period was in September and October. Reproductive potential ranges from 11,988 to 21,164 eggs. The spawning pattern of moonfish is indicated as total spawner. The result of Spearman-Karber method analysis showed that the size of the first maturity of female and male moonfish (Lm50) was 143 mm and 150.5 mm TL, respectively. So, female moonfish mature gonads earlier than male fish.

Correlating male white‐tailed deer antler size with female body mass across multiple spatial scales

AbstractManagers use morphometric data collected from harvested animals as indicators of nutritional condition. Antler or horn size often are considered in ungulates, but there are problems associated with biased and limited harvest data available from male animals in many populations. Adult female body mass also may be collected, but little information exists on how male antler size scales with female body mass. We evaluated the relationship between property‐specific mature male white‐tailed deer (Odocoileus virginianus) antler size and adult female body mass from harvest data collected at 2 spatial scales. Regression predicted a 4.4‐cm increase in average mature male antler size for every 1‐kg increase in female body mass from 31 properties across the eastern United States, 2015–2023. Adult female mass explained 64% of the variation in mature antler size, and including latitude as a covariate did not improve model fit. When we considered data from 174 properties in Mississippi, USA, 1991–1994, we predicted a 4.7‐cm increase in average mature male antler size for every 1‐kg increase in adult female body mass. Including soil resource region in the Mississippi model explained 48% of the variation in mature male antler size by accounting for differences in average sizes across regions. Our results indicate average female body mass correlates with mature male antler size at multiple spatial scales. We recommend managers collect body mass and age from harvested female deer, as female mass represents a useful metric to track management progress and predict changes in antler size.

Effects of different sowing dates on biomass allocation of various organs and allometric growth of Fagopyrum esculentum.

The sowing date plays a crucial role in influencing the growth and reproduction of plants, with its specific impact on biomass allocation and allometric growth remaining unclear. Understanding these effects is essential for optimizing agricultural practices and enhancing crop productivity. To investigate the effects of sowing dates on biomass allocation and allometric growth, a field experiment was conducted with sequential sowings of Fagopyrum esculentum from April 12th to August 11th in 2018. Biomass measurements were taken across various plant organs, and corresponding allocation calculations were made. A detailed analysis of the allometric growth relationship involving organ biomass variations was performed. The study revealed that the accumulation and allocation of organ biomass in buckwheat were significantly impacted by the sowing dates. Delayed planting led to reduced vegetative growth and increased biomass allocation towards reproduction. Allometric parameters such as exponent, constant, and individual size of buckwheat were notably affected by delayed planting. Interestingly, the allometric exponents governing the relationships between reproductive vs. vegetative biomass and belowground vs. aboveground biomass exhibited varying trends across different sowing dates. Notably, late sowings resulted in significantly higher reproductive biomass compared to early and middle sowings. These findings highlight the nuanced relationship between plant size and reproductive biomass under different sowing dates, emphasizing the critical role of planting timing in shaping mature plant sizes and reproductive outcomes. The study underscores the importance of considering sowing dates in agricultural practices to optimize plant growth and productivity.

Feeding on stressed algae exerts important effects on life history traits of Daphnia magna in a multi-stressor environment

Freshwater ecosystems are increasingly exposed to anthropogenic eutrophication, including high nitrogen. In addition, climate change is leading to more intense and frequent heatwaves, which have enormous impacts on all trophic levels of the ecosystem. Any change in the lower trophic levels, e.g., the phytoplankton, also introduces stress to higher trophic levels e.g., the zooplankton crustacean Daphnia. Individual effects of heatwaves, high nitrate, and changing feed quality have been studied in daphnia, but less is known about their interactive effects. This study used a 3 × 3 × 2 factorial design in which daphnia were exposed to combinations of ecologically relevant nitrate concentrations (0, 50, or 200 mg/L) and different heatwave scenarios (no, short-moderate, or long-intense) in which individuals were either fed with microalgae (P. subcapitata and C. reinhardtii) grown at 20 °C and 50 mg/L nitrate (control feed) or the same conditions as daphnia was exposed to (experimental feed). Throughout the experiment, the interactive effects of high nitrate, heatwave, and feed on mortality, maturation, offspring, and body size were evaluated. In general, heatwaves shorten the lifespan of daphnia. Exposing daphnia to a long-intense heatwave combined with high nitrate resulted in poor performance. In the nitrate-limited condition, however, the restricted proliferation of microalgae reduced feed availability, which also had a major impact on daphnia's life history traits. Daphnia cultured in high nitrate and fed control feed performed better than when fed experimental feed, suggesting that in a high nitrate condition, the microalgae grown under the same experimental conditions was either unable to meet energy requirements or introduced extra stress for the daphnia. Most importantly, the effect of nitrate and heatwave as stressors on the availability and quality of the feed had a greater impact on daphnia than its direct impact. Interestingly, a transgenerational adaptation to nitrate was observed which may help to maintain ecological balance in the long run.

Effects of Ovule Position on Seed Maturation, Seed Mass, and Seedling Size in Eastern Redbud (Cercis canadensis)

Effects of Ovule Position on Seed Maturation, Seed Mass, and Seedling Size in Eastern Redbud (<i>Cercis canadensis</i>)

The Status of Indigenous Chicken Genetic Resources: An Analysis of Farmers’ Perspectives and Implications for Breed Conservation Priorities in Zambia

(1) Background: Indigenous chickens (Gallus domesticus) (ICs) are an essential component of agriculture and rural livelihood among 80% of small-scale farmers (SSFs) in Sub-Saharan Africa (SSA). However, in the past decade, significant losses of Indigenous Chicken Animal Genetic Resources (IC-AnGR) resulting from poultry diseases, imported exotic breeds, poor market access, and uncontrolled crossbreeding have been reported. This study aimed to investigate the status of IC-AnGR and assess the major challenges affecting the production of ICs. (2) Methods: We surveyed 358 households in eastern, central, and southern livelihood zones, comprising 81.6% males and 17.6% females. (3) Results: Our study shows that respondents owned 16,112 ICs, 3026 goats, and 5183 herds of cattle. Overall, 77.4% of chicken breeds were ICs and 22.6% were exotic. Across the three zones, 18–44% reported the introduction or adoption of exotic breeds in the past decade, with most households sourcing breeding stock from local communities and family and friends at 45% and 28.6%, respectively. Farmers gave various reasons for adopting new chicken breeds, including fast growth (21.7%), larger mature sizes (21.66%), and resistance to diseases at 15.2%. Overall, 92.5% of farmers agreed or strongly agreed that some IC breeds disappeared in the past decade and nearly 90% were concerned. Some attributed the loss to poultry diseases. (4) Conclusion: Deliberate policies to promote the sustainable use and conservation of ICs are critical in Zambia.

Class I TCP in fruit development: much more than growth.

Fruit development can be viewed as the succession of three main steps consisting of the fruit initiation, growth and ripening. These processes are orchestrated by different factors, notably the successful fertilization of flowers, the environmental conditions and the hormones whose action is coordinated by a large variety of transcription factors. Among the different transcription factor families, TEOSINTE BRANCHED 1, CYCLOIDEA, PROLIFERATING CELL FACTOR (TCP) family has received little attention in the frame of fruit biology despite its large effects on several developmental processes and its action as modulator of different hormonal pathways. In this respect, the comprehension of TCP functions in fruit development remains an incomplete puzzle that needs to be assembled. Building on the abundance of genomic and transcriptomic data, this review aims at collecting available TCP expression data to allow their integration in the light of the different functional genetic studies reported so far. This reveals that several Class I TCP genes, already known for their involvement in the cell proliferation and growth, display significant expression levels in developing fruit, although clear evidence supporting their functional significance in this process remains scarce. The extensive expression data compiled in our study provide convincing elements that shed light on the specific involvement of Class I TCP genes in fruit ripening, once these reproductive organs acquire their mature size. They also emphasize their putative role in the control of specific biological processes such as fruit metabolism and hormonal dialogue.

The temperature-size rule in the context of Dynamic Energy Budget theory

The temperature-size rule (TSR) refers to the observation that a wide variety of organisms reach smaller sizes under warmer temperatures. Although various hypotheses have been stated about the mechanisms underlying TSR, a general understanding is still lacking. In this context, it seems that Dynamic Energy Budget (DEB) theory could be useful, as it constitutes a mechanistic framework that predicts growth and development from individual energetics. However, a critical assumption of this framework is that temperature affects all physiological rates equally, which prevents it from capturing the TSR. It remains an open question if and how the DEB framework can be used to capture the TSR patterns.The model does, however, include a parameter, the food searching rate, that does not need to obey this constraint, as it is a physical rather than a physiological parameter. Here, we aimed to test whether introducing a differing temperature-dependence of food searching rate in DEB models makes it possible to capture the TSR. We parameterized the model using an extensive dataset of Daphnia life history response to temperature. The resulting model was able to capture the decrease of both size at maturity and asymptotic size observed in this dataset.Therefore, DEB models can capture the TSR without any major modification, but only requires to introduce a different function for the temperature dependence of the food searching rate. The mechanism underlying this effect essentially results from increased food limitation at high temperature, which, in combination with the particular allocation scheme of the DEB model, affects differentially growth and development.

Climate induced declines in maternal size may come at a cost to embryonic investment and larval performance in the American lobster

Many crustacean taxa mature at a smaller size in warmer thermal regimes. Over the past four decades, female lobsters American lobster (Homarus americanus) in the rapidly warming Gulf of Maine have also been reported to be maturing at significantly smaller sizes over time. Smaller females have lower fecundity, but whether they also produce lower quality eggs and larvae has been unclear. Here we examine the hypothesis that smaller females invest less energy per larva than larger females, thereby compromising post-hatch performance and survival. This study used a combination of laboratory and field studies to assess the maternal size effect on embryos and larvae. In a space-for-time comparison of lobsters from contrasting thermal regimes along the coast of New England, we also investigated how lobster collected from populations in cooler northern regions may respond to future warming. We found smaller females not only are less fecund, but their embryos are smaller and generally less well invested with lipids than those from larger females. Furthermore, stage I larvae from smaller females are smaller and have less energy reserves needed to survive starvation. Our geographic comparison also revealed that female lobsters living in the warmer thermal regime of southern New England are more fecund and produced larger eggs than females of the same size from colder regimes in the Gulf of Maine, and we cautiously interpret this novel finding as evidence of a counter-gradient adaptation that could compensate for smaller maturation size at lower latitudes, a phenomenon requiring further investigation. These results help to reveal the cascading effects warming can have on important reproductive and larval survival traits on an economically important species.

Managing water gate operation and fish passage facilities in irrigated systems of the Nam Kam River, Thailand

AbstractThe migration of fishes through the Thoranit Naruemit water gate on the Nam Kam River, a tributary of the Mekong River in Thailand, was studied to understand the hydrological factors and improve the operational regime of the fish pass at the structure. Migration of fish from the Mekong River started in May, at the onset of the rainy season. During 60 days of operation, the fish pass supported the upstream migration of 83 species and ~440,000 fish, equivalent to about 11 tonnes of fish. The fish pass supported migration of a range of fish sizes between 45 and 700 mm, and most fish were larger than the size of first maturity for the species in question. The factors influencing migration into the Nam Kam included the lunar cycle, flow in the fish pass, water level in the river and flow variability. Migration tended to increase in the 3–4‐day period before or after a full moon. Discharge and water level changes associated with rising water levels in the Mekong River synchronize with the spawning season of most Mekong fish and trigger upstream migration. Many fish migrated through the pass at discharges through sluice gates between 8 and 323 m3/s and with a flow through the fish pass between 0.95 and 3.08 m/s. Restrictions to fish migration were found and recommendations for water gate and fish pass operation are provided.