Search Results (60)

Bighead carp (Hypophthalmichthys nobilis) is a key aquaculture species, with the head and its orbital fat being a commercially valuable product. To elucidate the molecular basis of growth variation, we performed comparative transcriptome analysis of orbital fat from extreme growth phenotypes at juvenile (6 months) and market-size (18 months) stages. In juveniles, slow growth was linked to upregulation of stress-responsive genes (sgk1, fkbp5, lipg), while fast growth correlated with higher expression of stress-buffering (crhbp) and nutrient-signaling (rbp2, mgea5) genes. At 18 months, divergent growth aligned with opposing lipid metabolic states: a pro-anabolic profile (dgat2, fads2) supported fast growth, whereas a catabolic profile (cpt1b, ppargc1a) was associated with slow growth. These results demonstrate stage-specific transcriptional reprogramming in orbital fat underlying growth variation. This study provides a molecular framework for orbital fat-mediated growth regulation and highlights potential candidate genes for molecular breeding in bighead carp. Full article

To provide a theoretical basis for sound barrier technology for fish, the effects of sound intensity and frequency on negative phonotaxis in adult bighead carp, Hypophthalmichthys nobilis, (weight 1.42–2.20 kg, body length 45.1–54.8 cm) were tested using underwater sound equipment in a pool with sound absorbing material to reduce sound reflection. There were two primary findings: (1) The cumulative times that fish remained in the high, medium and low sound intensity areas were significantly different (p < 0.001). The cumulative time decreased as sound intensity increased, demonstrating negative phonotaxis by the test fish towards high sound intensity. The cumulative time that fish remained in the high sound intensity area was less than in the control area and the difference was highly significant (p < 0.001). This strongly negative phonotaxic response can be exploited in developing sound barriers for guiding fish. Negative phonotaxis could be used to guide fish away from hazards and along migration routes, to help prevent exotic fish invasion, and to improve spawning success by preventing migration into tributaries where habitat has been severely impacted by dams or other human activities. (2) Adult H. nobilis respond differently to different frequencies of single-frequency sound. Higher-frequency sound (300–1000 Hz) produced a stronger negative phonotaxic response than lower-frequency sound (50–200 Hz), and the difference in cumulative times was highly significant (p < 0.001). Thus, high-frequency sound is more effective than low-frequency sound for producing negative phonotaxis. This research demonstrates that negative phonotaxis is affected by sound intensity and frequency. However, for a given application and target species, additional research should be carried out to determine the most effective combination of acoustic parameters. Full article

The middle reaches of the Yangtze River are a crucial breeding habitat for four major Chinese carps. The ecohydrological characteristics of their spawning grounds are crucial factors influencing spawning for these species: black carp (Mylopharyngodon piceus), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Aristichthys nobilis). To investigate the impact of ecohydrological processes within the Three Gorges Reservoir on spawning, this study focused on the spawning grounds of the four major Chinese carps in the Yichang–Yidu section of the Yangtze River. By identifying key ecohydrological indicators and leveraging hydrological and spawning monitoring data from 2013 to 2024, the response characteristics of the four major Chinese carps’ spawning to these hydrological processes were analyzed. The results showed that the key ecohydrological indicators currently stimulating spawning for the four major Chinese carps are the fish-perceived daily flow rate increase, the fish-perceived cumulative flow rate increase, and the daily flow rate increase. These three indicators are significantly positively correlated with the scale of spawning for the four major Chinese carps. The thresholds for spawning at least 20% of the annual spawning total are: a perceived daily flow increase (P_da) of 4.52–36.05%; a perceived cumulative flow increase (P_cu) of 36.15–180.23%; and a daily flow increase (Q_av) of 588–2825 m³/s. The optimal water temperature for the reproduction of the four major Chinese carps is 21–23 °C. Overall, since the Three Gorges Reservoir’s normal operation, the frequency and scale of spawning for the four major Chinese carps have been highest during periods of rising water. It is recommended that, within the corresponding thresholds, ecological operation be conducted twice a year, once in mid-June and once in early July or late June. Daily flow increases can be controlled within the range of 588–2000 m³/s. This study analyzed the correlation between eco-hydrological indicators and the stimulation of spawning of the four major Chinese carps, providing optimized flow ranges and habitat conditions for ecological operation, which is conducive to promoting the reproduction and spawning of the four major Chinese carps in the Yichang–Yidu spawning grounds in the middle reaches of the Yangtze River. Full article

Fish barrier technology by pulsed direct current has broad application potential to guide fish to suitable waters. The primary objective of this investigation was to study the effects of electric pulse frequency and water velocity on fish deterrence by pulsed direct current. The test fish were adults of two common carp species, Hypophthalmichthys nobilis (bighead carp, standard length 0.460–0.545 m) and Cyprinus carpio (Eurasian carp, standard length 0.292–0.335 m). Experiments were conducted in the 20 m swimming chamber of a 50 m flume, with a pulsed electric barrier produced by vertical electrodes located in the middle of the swimming chamber. The effectiveness of the electric barrier in deterring fish from swimming upstream past the electrodes was tested. The electric pulse generator produces a square wave pulse, with a voltage of 150 V and width of 2 ms. There were four electric pulse frequency treatments (4 Hz, 6 Hz, 8 Hz, 10 Hz), and two water velocity treatments (0.2 m/s, 0.6 m/s), with 10 replicates of each treatment. There were four primary findings. (1) Of the 160 fish tested, no fish was stunned and only 4 trembled (lost the ability to swim) for more than 2 s after encountering the electric barrier. (2) At a given water velocity, the crossing probability decreased as pulse frequency increased, and the decrease was largest when the frequency increased from 8 to 10 Hz. (3) At a given electric pulse frequency, the crossing probability was higher at the high water velocity, and barrier efficiency was more sensitive to velocity at higher pulse frequencies. (4) H. nobilis, a stronger swimmer, crossed more often than C. carpio. This study can provide ideas for the management of invasive species. However, the study was conducted under controlled laboratory conditions, and field experiments should be carried out before field applications. Full article

The orbital fat of bighead carp (Hypophthalmichthys nobilis) represents a structural fat deposit located posterior to the eyes and constitutes an important edible component of the head region. Nevertheless, molecular mechanisms governing lipid accumulation during ontogenetic development remain insufficiently characterized. Here, we performed RNA-Seq on orbital fat tissues from 6-month-old (juvenile) and 18-month-old (market-size) bighead carp. A total of 1042 DEGs were identified, with 807 up-regulated and 235 down-regulated in the 6-month-old stage. Functional enrichment revealed key pathways including fatty acid metabolism, PPAR signaling, and glycolysis/gluconeogenesis. qRT-PCR validation confirmed RNA-Seq reliability. Notably, the differential expression patterns of genes such as cpt1a, cpt1b, slc27a1, fads2, and scd suggest their association with an elevated capacity for lipid synthesis in the orbital fat of 18-month-old bighead carp. This study presents the first transcriptome analysis of orbital fat development in a freshwater fish, offering insights into the genetic improvement of head meat quality traits and growth in bighead carp head. Full article

Fish diel activity can affect the catch of fishing gear, such as gill nets, thereby influencing fishery resource assessment and management. This study investigated diel catch variations of primary fish species in Gehu Lake using monofilament trammel nets from April to November of 2016. Fish sampling occurred monthly, with nets set and fish caught at four-hour intervals in each month. The results showed that significant diel effects and diel × month interaction were found on Chinese silver carp (SC) and diel × month interaction on common carp (CC). Topmouth, humpback, and Wuchang bream (WB) displayed significantly higher catch per unit effort (CPUE) during twilight or daytime than at night, and no diel × month interactions were detected. For Chinese bighead carp (BC), Mongolian redfin (MR), Japanese grenadier anchovy (JGA), and crucian carp, no diel effect and diel × month interaction were observed. The study suggested that most activities occurring in daytime and at twilight were caused by visual orientation to prey for topmouth and humpback, and by the herbivorous feeding habitat of WB. Food competition between BC and JGA may drive a pronounced temporal partitioning of their diel activity. Overnight gillnet fishing could underestimate the population sizes of herbivores, such as WB, and visually oriented predators, for example, humpback, and might not influence the estimation for BC, JGA, and crucian carp. However, its effects on the stock estimation of SC and CC would vary with months. Notably, future winter investigations into diel catch in this lake could potentially augment the conclusions of the present study. Full article

Monitoring changes in fishery resources, such as the density and growth of fish, following large-scale fish stocking in a reservoir is important. In this study, BioSonics DT-X (201 kHz) was used to assess the seasonal changes in the density, size distribution, and biomass of fish in Duihekou Reservoir, Zhejiang province, China, in 2020. The fish density was significantly lower in spring (3.33 ind./1000 m³) than in summer (75.24 ind./1000 m³), autumn (56.22 ind./1000 m³), and winter (20.37 ind./1000 m³) (p < 0.01). No significant difference in fish density was apparent between summer and autumn. Additionally, the average target strength (TS) values in spring (−41.05 dB) were significantly higher than in summer (−44.66 dB) and autumn (−45.55 dB) (p < 0.01), but significantly higher in winter (−38.12 dB) than in the other seasons (p < 0.01); no significant difference was observed between the summer and autumn values (p > 0.01). The fish biomass in winter (14.3 g/m³) was 13 times that in spring (1.1 g/m³). These results indicate that large-scale fish stocking can effectively adapt to reservoir habitats to achieve growth. The catch composition revealed silver carp (Hypophthalmichthys molitrix) and bighead carp (Aristichthys nobilis) to be dominant species, mostly comprising young individuals. Stock enhancement plays a critical role in reshaping the fishery population structure in a reservoir. These findings enhance our understanding of fishery resource changes in reservoirs after non-classical biomanipulation and demonstrate how hydroacoustic techniques can be successfully used to quantify the density and size distribution of fish for more effective fishery management. Full article

Background: Bighead carp (Hypophthalmichthys nobilis), a vital species in China’s freshwater ecosystems and aquaculture, has experienced significant population declines due to habitat degradation and intensive farming. Methods: In this study, eight polymorphic microsatellite markers were utilized to examine the genotypes and genetic diversity of 320 individuals of bighead carp populations located in the middle Yangtze River. This included four wild populations (ZX, DTH, SS, WH) and six cultured populations (HH, XZ, CH, QC, CD, HG). Results: Wild populations exhibited significantly higher genetic diversity (mean Na = 12.25 ± 0.63, Ho = 0.802 ± 0.063) than cultured groups (mean Na = 8.85 ± 1.21, He = 0.779 ± 0.032). Low differentiation (Fst < 0.05) among wild populations indicated high connectivity with low genetic structure, whereas cultured populations CH and HG showed moderate-to-high differentiation (Fst = 0.156–0.293). Bayesian analysis (K = 7) revealed a distinct clustering of wild populations, while cultured stocks exhibited admixed genetic ancestries. Bottleneck tests confirmed recent genetic bottlenecks in three cultured populations. Conclusions: Wild bighead carp populations retain a critical genetic diversity, serving as reservoirs for conservation, while intensive aquaculture practices threaten genetic integrity through allele loss and inbreeding. Full article

Flow velocity is a critical factor in determining the suitability of fish habitats. Understanding the preference patterns of the four major Chinese carps (FMCCs) for different flow velocities is crucial for their habitat conservation and restoration. In this study, the preference of individual fish species, approximately 15 cm in length, for flow velocity was investigated at flow velocity gradients of 0.0, 0.4, 0.8, 1.2, 1.6, and 2.0 times their body length. Additionally, a deep learning algorithm based on convolutional neural networks (CNNs) was employed for fish target detection. The results showed that, at this length, black carp (Mylopharyngodon piceus) preferred fast currents when the inlet flow velocity was between 0.4 and 1.6 times their body length, while grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix), and bighead carp (Hypophthalmichthys nobilis) preferred fast currents when the inlet flow velocity of the test flume was between 0.4 and 2.0 times their body length. However, this preference for fast currents decreased as the overall flow velocity increased to a specific threshold, eventually leading to their avoidance. The highest preference for fast currents among the four species was observed at inlet flow velocities of 1.2, 0.4, 0.8, and 0.8 times their body length, respectively. The findings of this study provide important insights into habitat conservation and restoration for the FMCCs in projects focused on the construction of navigation channels and water conservancy. Full article

Environmental DNA (eDNA) metabarcoding was utilized to compare the fish species composition, diversity, and their relationships with environmental factors in four medium-sized drinking water reservoirs (Tongjiqiao, Andi, Shafan, and Jinlan) within the Qiantang River Basin during both wet and dry seasons. A total of 44 fish species belonging to 6 orders, 15 families, and 40 genera were detected, with Cyprinidae being identified as the dominant family (68.2%). Silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) were identified as the most abundant species, representing 81.94% and 99.98% of the relative eDNA abundance, respectively. The fish communities were characterized by river-resident species (59.1%), pelagic species (43.2%), and omnivorous (43.2%) and carnivorous (43.2%) feeding habits. Significant influences of seasonal and reservoir-specific variations on physicochemical parameters, species composition, and ecological traits were observed. However, no significant differences in community diversity (Chao1, Pielou_e, Shannon, and Simpson indices) or distribution patterns were detected between wet and dry seasons. In contrast, Jinlan Reservoir was found to exhibit distinct diversity and distribution patterns compared to the other three reservoirs, which was consistent with the relative eDNA abundance of H. molitrix and H. nobilis. Through a Spearman correlation analysis, the relative abundance of H. molitrix was revealed to be negatively correlated with community diversity, while H. nobilis was shown to have positive correlations (except with Chao1). This suggests that the excessive stocking of H. molitrix may lead to reduced diversity, whereas moderate stocking of H. nobilis could promote diversity restoration. Among physicochemical factors, Chao1 richness was found to be negatively correlated with conductivity, pH, phosphate–phosphorus (PO₄-P), and the total nitrogen to total phosphorus ratio (TN/TP), while Shannon and Simpson diversity indices were negatively correlated with nitrate nitrogen (NO₃-N) concentrations. A redundancy analysis (RDA) identified NO₃-N and permanganate index (COD_Mn) as the primary physicochemical drivers of fish community structure, indicating that while physicochemical differences were found to influence species composition and diversity, their effects were considered relatively limited. These findings suggest that the overwhelming dominance of H. molitrix and H. nobilis in the reservoirs may reduce the influence of seasonal variations and cross-reservoir physicochemical disparities on fish community dynamics. Full article

Wild fish are often considered more nutritionally valuable than cultured fish. This study aimed to elucidate the relationship between the gut microbiota and meat quality through the gut–muscle axis. Therefore, cultured and wild bighead carp (Hypophthalmichthys nobilis, Richardson 1845) from the Yangtze River were investigated to compare the differences in the meat quality and gut microbiota composition. Cultured bighead carp were collected from four intensive ponds along the Yangtze River area, while wild bighead carp were obtained from three different sites in the Yangtze River. The results showed that wild bighead carp muscle had significantly higher total saturated fatty acid (∑SFA) and total ω − 3 polyunsaturated fatty acid (∑n − 3 PUFA) content and water-holding capacity and lower lipid, histidine, and total ω − 6 polyunsaturated fatty acid (∑n − 6 PUFA) content than cultured bighead carp, while the muscle texture was not significantly different between the two groups, with the exception of the resilience. Moreover, the hindgut microbiota was analyzed using 16S rRNA high-throughput sequencing. The alpha and beta diversity differences between the cultured and wild groups were significant. The LEfSe analysis revealed Mycobacterium, Longivirga, and Acetobacteroides as biomarkers in cultured bighead carp, while Clostridium_T and other Firmicutes-associated genera were predominant in wild bighead carp. Regarding the relationship between the hindgut microbiota and meat quality, Mycobacterium exhibited a positive correlation with the muscle n-6 PUFA content and a negative correlation with muscle n − 3 PUFAs, while Clostridium_T exhibited the opposite pattern. According to the ecological network, the abundance of Actinobacteria could serve as a significant indicator of variations in the abundance of Mycobacterium and Clostridium_T. Consequently, differences in meat quality, particularly in the fatty acid composition, were observed between wild and cultured bighead carp. These differences may be associated with variations in the hindgut microbiota, shedding light on the gut–muscle axis. Full article

The existing vacuum fish pump is too large and difficult to move, which is difficult to apply to small fishing vessels. However, the development of a small vacuum fish pump is not a single scaling of the existing vacuum fish pump but requires the support of relevant experiments and simulation theories. In this study, a vacuum fish pump suitable for small fishing vessels was developed. Firstly, a numerical model of the internal flow field during the vacuum fish pump’s working process was established using computational fluid dynamics (CFDs) and verified its effectiveness by physical experiments. It is found that the VOF model can well predict the variation of the volume fraction of the liquid phase in the whole calculation area with time during the suction or drainage process of the vacuum fish pump. Then, the internal flow field characteristics of the fish pump under different working conditions were simulated, and the rationality of the design of the fish pump was evaluated according to the numerical results. Finally, a separate physical experiment was carried out on grass carp, carp, crucian carp, silver carp, and bighead carp, respectively, and the capture efficiency and corresponding fish damage rate for different fish were analyzed. The experimental and numerical results show that the vacuum suction fish pump can achieve efficient and automatic suction and transport of live fish. Full article

Optimizing biological carbon sequestration has become a primary strategy in global low-carbon-emission initiatives. Freshwater fisheries in reservoirs play an important role in aquatic biological carbon sequestration. However, a standard method for evaluating the carbon sink capacity of inland fisheries has not been developed. Therefore, this study aimed to assess and compare the carbon sequestration potential of the Qianxiahu Reservoir’s fisheries using the trophic level and mass-balance methodologies. The Ecopath model was employed to determine the trophic levels of aquatic organisms within the Qianxiahu Reservoir ecosystem, with input parameters sourced from in situ surveys and the literature on reservoirs. The model includes 21 functional groups, with trophic levels ranging from 1.000 to 3.281. The key species identified are silver carp, bighead carp, and crucian carp. The indices of Finn’s cycling index (FCI), connectivity index (CI), system omnivory index (SOI), and total primary production/total respiration (TPP/TR) for the Qianxiahu Reservoir are 11.35, 0.27, 0.196, and 1.540, respectively. These values indicate a high degree of material recycling and complex interconnections among functional groups. The fishery carbon sink potential of the Qianxiahu Reservoir, calculated using the trophic level and carbon content methods, yielded values of 261.8362 tons/km² and 66.6818 tons/km², respectively. The trophic level method showed a notable increase of 195,1544 tons/km² compared to the carbon content method, underscoring significant differences in results between the two methods. The study concludes with recommendations for research on methods to assess the carbon sink capacity of freshwater fisheries, aiming to establish a scientific framework for this evaluation. Full article

The Bighead carp (Hypophthalmichthys nobilis), a primary freshwater aquaculture species in China, faces challenges due to over-exploitation and environmental changes. We leveraged RAD-seq to perform a comprehensive population genetic analysis on 14 H. nobilis populations sampled from the Yangtze River (13 populations) and the Marseilles Reach of the Illinois River (one population). Analysis of genetic diversity showed that different parameters demonstrated varied inferences, and notably, Zhongxian (ZX2), Wanhzou (WZ2), Yangzhou hatchery (YZYZ), Yangzhou (YZ), and Taihu (TH) populations showed apparent heterozygote deficiency. Linkage disequilibrium (LD) analysis exhibited a trend of higher linkage disequilibrium in populations from the upper reaches of the Yangtze River, followed by those from the middle reaches and then those from the lower reaches. Additionally, the reconstructed polygenetic tree and PCA plot clustered all populations into 2 major subgroups, while the results of structure analysis indicated 4 ancestors. The pairwise F_ST values ranged from 0 to 0.5530. Among these, high F_ST values (0.1931–0.5530) were only observed between populations WZ2, YZ, YZYZ, and the remaining 11 populations. Furthermore, genetic bottlenecks were observed in all populations 20–30 thousand years ago. Overall, the research offers insights essential for genetic management practices for sustainable aquaculture and biodiversity conservation of bighead carp. Full article

Steroid hormones, recognized as emerging environmental contaminants, have garnered increasing attention in recent years. The present work studied the distribution characteristics in the environment, bioaccumulation in aquatic products, and the associated environmental and health risks of typical steroid hormones from commercial freshwater aquaculture farms operating under different aquaculture modes (monoculture and polyculture). Totals of 9 and 14 steroid hormones were detected in water and sediment samples, with concentrations ranging from 0.66 ± 0.17 ng/L to 40.5 ± 5.08 ng/L and from 0.36 ± 0.08 ng/g to 123 ± 19.9 ng/g, respectively. Hazard index (HI) calculations indicated that all sampling locations were identified as medium or high risk for both water and sediment matrices. Nineteen steroids were detected in at least one type of tissue, with the concentrations in the bile, plasma, muscle, liver, and gill ranging from <LOQ to 52.6 ± 4.82 ng/L, from <LOQ to 41.9 ± 4.80 ng/L, from 0.36 ± 0.07 ng/g to 321 ± 19.1 ng/g, from <LOQ to 1140 ± 107 ng/g, and from 0.36 ± 0.03 ng/g to 1450 ± 239 ng/g, respectively. Furthermore, four synthetic steroid hormones exhibited significant bioaccumulation across various tissues, such as MLA in bile and 5α-DHP in muscle, liver, and gill (BAF > 5000 L/kg). Notably, despite low estimated daily intakes (EDIs) (0.43–6.43 ng/day/person to 18.7 ng/day/person) and hazard quotients (HQs) (below 4.188 × 10⁻⁷), the high bioaccumulation factors (BAFs) underscore the necessity for stringent regulatory measures by local governments. Additionally, a comparison of EDI results across different aquaculture modes and fish species revealed that steroid hormone-related health risks to humans are influenced by both the fish species and the aquaculture mode. This study indicated that the consumption of poly-cultured fish (e.g., bighead carp) may pose a greater steroid-related health risk, compared to the consumption of mono-cultured fish. Full article