Volume 76, Issue 4, 2024

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Effects of dietary cysteamine addition to a plant-based diet on growth performance, body composition, hepatosomatic histological structure and metabolism of taurine synthesis in turbot (Scophthalmus maximus L.)
(2024) Qi, Guoshan; Wang, Lu; Zhang, Yanying; Ai, Qinghui; Mai, Kangsen
This present study was conducted to illustrate the effect of dietary cysteamine on feeding, growth, biochemistry composition, hepatosomatic histological structure and metabolism of taurine synthesis in juvenile turbot (Scophthalmus maximus L.) (2.0 ± 0.01 g) fed high plant protein diets. A fishmeal-based diet (72.5% FM) was designed as the control diet (DietFM). Four isonitrogenous and isolipidic diets consist of 14.0% FM, 23.0% soybean meal and 30.0% wheat gluten meal, which were formulated to substitute FM with 0.0%, 0.05%, 0.1% and 0.15% cysteamine hydrochloride (labeled as DietPP, DietCS-0.05%, DietCS-0.1% and DietCS-0.15% respectively). Fish were stochastically allocated into fifteen 200L tanks and fed twice daily (06:30 and 18:30) to apparent satiation for 9 weeks. Feed intake (FI) in fish-fed DietCS-0.05% was conspicuously higher than that in fish-fed DietPP (p<0.05), and no notable difference was discovered among fish-fed diets with cysteamine inclusion (p>0.05). No conspicuously upward trend was found with the increase of dietary cysteamine in FBW, SGR, WGR, FER, PER, and SR when there was a downward trend in CF, VSI, and HSI (p>0.05). A remarkable increase was discovered from 0.0% to 0.05% cysteamine inclusion in ash content (p<0.05) when no noticeable difference was observed among all the cysteamine inclusion groups in moisture, protein, and lipid content (p>0.05). Only the body taurine content showed a notable increase between fish-fed DietCS-0.05% and fish-fed DPP among the indexes of body taurine, liver taurine, and serum taurine content (p<0.05), whereas no notable difference was observed in hepatosomatic L-cysteine sulfinate decarboxylase (CSD) and cysteamine dioxygenase (CDO) activities among all the cysteamine inclusion groups (p>0.05). The cellular morphology and cell veins in the liver of fish-fed diets with cysteamine inclusion were clearer than those of fish-fed DPP. The results showed that 0.05% cysteamine addition in a high plant protein diet is optimal.
GLUT2 gene from Penaeus monodon: Molecular characterization, expression and association with tolerance to low salinity stress
(2024) Li, Yundong; Zhang, Wenwen; Jiang, Song; He, Peng; Yang, Qibin; Yang, Lishi; Huang, Jianhua; Zhou, Falin
The full-length cDNA sequence of Penaeus monodon glucose transporter-2 (PmGLUT2) was cloned in this study using the RACE method. Quantitative real-time PCR was used to analyze the differential expression of PmGLUT2 during the development of P. monodon larvae in different tissues and under low salinity stress. The PmGLUT2 cDNA exhibited a total length of 2018 base pairs, with 94 base pairs located in the 5' untranslated region (UTR) and 352 base pairs in the 3' UTR. Additionally, the sequence contained 29 base poly (A) tails and 1572 base pairs within the open reading frame (ORF), capable of encoding 523 amino acids. Through a comparative analysis of the amino acid sequences of PmGLUT2 and LvGLUT2, it was determined that PmGLUT2 had 94.77% homology with Tret1 gene of Litopenaeus vannamei, and 60.54% homology with GLUT2 gene of L. vannamei. The results indicated that there was a fluctuation in PmGLUT2 expression levels from zygote to postlarva development, with initial reduction followed by an increase, although the difference was not statistically significant. According to the molting analysis, the highest expression level of PmGLUT2 was observed in the hepatopancreas during the premolt period, while the gill and gut exhibited peak expression levels during the intermolt period. PmGLUT2 was found to be most abundant in lymph tissue, followed by gill tissue, and least abundant in ootheca, according to the tissue expression analyses. Following 96 hours of acute salt stress, there was a notable inhibition in the expression of PmGLUT2 in the hepatopancreas and gills. Additionally, the expression level in the gills at 96 hours was significantly lower compared to the baseline level at 0 hours.
Research on Development Strategies for Leisure Fishing in Inner Mongolia from the Perspective of Industrial Integration
(2024) Li, Xue; Pang, Tiantian; Feng, Xuebin; Zhang, Jianying; Zhao, Zhuming
This study explores the current status of leisure fishing in Inner Mongolia and its implications for the development of leisure fishing abroad. As an important province in northern China, Inner Mongolia has rich natural resources and unique geographical conditions but still faces many challenges in infrastructure development and ecological protection. By analyzing Inner Mongolia's unique geographical and climatic conditions, water resource distribution, and industrial structure, the research finds that while the region possesses abundant water resources, inadequate infrastructure and weak awareness of ecological protection remain major constraints on its development. Using the SWOT analysis method, the study identifies the strengths, weaknesses, opportunities, and threats of leisure fishing in Inner Mongolia, highlighting the importance of government policy support and eco-friendly development models in enhancing industry competitiveness. Furthermore, the research proposes strategies to promote industrial chain integration, optimize industrial structure, strengthen infrastructure, implement sustainable development models, and enhance brand building and market promotion. Based on Inner Mongolia's experience, the study offers insights for developing leisure fishing abroad, recommending a focus on ecological protection and technological innovation, enhancing brand influence, and fostering international cooperation and resource sharing. This research provides a theoretical foundation and practical guidance for developing leisure fishing in Inner Mongolia and other regions, serving as a reference for the sustainable development of global leisure fishing. It emphasizes the necessity of integrated governance and ecological protection while projecting the future prospects for the synergistic development of leisure fishing in economic, environmental, and social dimensions.
Rapid and convenient detection of Weissella ceti with loop-mediated isothermal amplification
(2024) Fang, Huahua; Pan, Jiankun; Wang, Yingfei; Tao, Ye; Zheng, Chaoli; Wang, Minghao; Qian, Dandan; Sun, Yanling
Weissella ceti, a Gram‐positive lactic acid bacterium, has emerged as a novel pathogen causing Weissellosis in rainbow trout (Oncorhynchus mykiss). Until now, it has not been easy to distinguish W. ceti from other pathogens by the symptoms of the infected rainbow trout, especially at the primary stage of infection. Thus, a convenient and rapid identification method is needed to determine this pathogen. The current study demonstrated loop-mediated isothermal amplification (LAMP) superior specificity and sensitivity for W. ceti. Primers were designed targeting the hemolysin A gene, and LAMP was accomplished within 30 min at 63 ℃. The minimum concentration of LAMP for W. ceti DNA was 5.9 x 10^-6 ng/μl, which was 100 times more sensitive than traditional PCR. LAMP confirmed the high specificity for W. ceti, whereas the other six pathogens were negative reactions. Furthermore, the effectiveness of LAMP was also demonstrated in simulated clinical samples. Based on the results, LAMP was rapid and convenient for point-of-care testing to diagnose W. ceti infections.
Effects of dietary Lactobacillus rhamnosus supplementation on growth performance, antioxidant properties, and gut microbiota alterations on Chinese mitten crab, Eriocheir Sinensis
(2024) Yang, Zhenfei; Cao, Haiyue; Wang, Jianguo; Zhang, Huimin; Li, Wei; Song, Lin; Tang, Xiaofeng; Qi, Fugang; Meng, Pingping; Lin, Apeng; Feng, Zhongyu
Numerous studies have demonstrated that Lactobacillus rhamnosus exerts growth-promoting effects in animal husbandry. However, its role in the growth performance of the Chinese mitten crab remains inadequately evaluated. In this study, we aimed to investigate the potential effects of L. rhamnosus on the growth performance, intestinal function, and microenvironment of the Chinese mitten crab. Crabs with an average weight of 0.80 ± 0.12 g were divided into four groups, with the experimental groups receiving dietary supplements of L. rhamnosus at concentrations of 0% (C group), 2% (S-1 group), 5% (S-2 group), and 8% (S-3 group), each containing 10⁹ CFU/g added to the basal diet. The results indicated that the final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) of crabs in the S-1 and S-2 groups were significantly higher than those in the control group (P < 0.05). The enzymatic activity of immune-related enzymes, including alkaline phosphatase (AKP), superoxide dismutase (SOD), and catalase (CAT), increased following dietary supplementation with L. rhamnosus. Principal coordinates analysis revealed distinct microbiota compositions between the groups. The alpha diversity indices, including ACE, Chao1, Shannon, and Sobs, were enhanced after dietary supplementation, while the Simpson index showed no significant differences. Statistical analysis demonstrated that including L. rhamnosus in the diet increased the abundance of Proteobacteria and Firmicutes while reducing the abundance of Actinobacteriota in the intestines compared to the control group. Additionally, the abundance of Paracoccus and Thiothrix in the crabs' intestines was elevated. In conclusion, the dietary inclusion of L. rhamnosus improved growth performance, enhanced intestinal microflora, and bolstered non-specific immunity and antioxidant functions in the Chinese mitten crab.
Application of Bacteriophages to Treat Toxic Gas-producing Bacteria Desulfovibrio spp. in Shrimp Ponds
(2024) Van, Truong Thi Bich; Minh Thu, Tran Vo; Vo, Van-Thanh; Loan Anh, Nguyen Thi
Desulfovibrio spp. bacteria pose significant challenges in shrimp aquaculture by producing hydrogen sulfide (H2S), which depletes oxygen levels and hinders shrimp growth. The increasing prevalence of antibiotic-resistant bacteria necessitates the exploration of alternative control methods. This study investigates the potential of bacteriophages as a biological solution to inhibit Desulfovibrio spp. in shrimp ponds. Six bacteriophage strains (ST231, ST22, φMix 1, φS8, φS9, and φMix 2) were evaluated using plaque assays at three time points (3, 6, and 18 hours). Results demonstrated that most bacteriophages significantly reduced bacterial density over time, with ST22 showing the most substantial inhibition (p<0.05). Genomic analysis of bacteriophage ST22, published in the GenBank database, revealed genes related to Desulfovibrio spp., specifically Deltaproteobacteria and Desulfobacteraceae. The study also found that bacteriophage treatment led to decreased H2S and NH3 levels and increased dissolved oxygen in simulated pond environments. Morphological changes in bacterial colonies post-treatment further supported the phages' inhibitory effects. These findings suggest that bacteriophage ST22 is a promising biological alternative to antibiotics for preventing and controlling diseases caused by Desulfovibrio vulgaris in shrimp aquaculture, though further research is needed to assess long-term ecological impacts and efficacy in complex pond ecosystems.
Effects of short-time fasting and feeding frequencies within 24 hours on histology, cholecystokinin and trypsin enzyme activities of digestive organs in black bream, Megalobrama pellegrini (Tchang, 1930), juvenile
(2024) Li, Wenyu; Tang, Hongyu; Lin, Xiaogang; Ma, Feifan; Zhang, Kaicheng; Zhang, Wenqi; Li, Qin
To study the regulation and feedback mechanism of cholecystokinin and trypsin in Black bream, Megalobrama pellegrini (Tchang, 1930) 60 days after hatching under 15 days short-term fasting and different feeding frequencies within 24 hours during the same period, Black bream (wet weight 183.75 ± 61.16 mg, total length 20.74 ± 4.08 mm) developed in a recirculating aquaculture system (RAS) were selected. In the short-term fasting trial, body weight, trypsin, and cholecystokinin (CCK) of the feeding control group (FCG) were higher than those of the fasting trial group (FTG). Trypsin and CCK in FTG reached the lowest value on day 9, and CCK content reached the highest value on day 11. In the 24-hour daily rhythm experiment, juvenile fish were randomly assigned to (A) once feeding, (B) twice feeding, (C) three times feeding, and (D) fasting. CCK showed a minimum at 1:00+ in group A, a peak at night in group B\C\D, and a maximum in group C, and a single satiety stimulus can lead to increased hunger. The four treatment groups had an apparent closed-loop regulation, while the control point of the fasting group (D) shifted forward to the next day. In this study, we found only negative feedback regulation of CCK and trypsin at the end of fasting, considering whether the secretory site or anti-inflammatory response caused the increase of CCK. The damage of epithelial cells in the villi of the foregut was greater than that in the hindgut and hepatopancreas, and the detachment of epithelial cells and the striatal margin was the main damage. Different feeding frequencies in a single day did not directly affect the long-term fluctuation of CCK and trypsin diurnal rhythm. Three meals per day may be more conducive to the long-term growth of juvenile Black bream. This study aimed to provide a reference for the feeding strategy of juvenile Black bream in the RAS.
Effects of Short-Term Temperature Stress on Metabolic and Digestive Enzymes Activities of Procambarus clarkii
(2024) Jiang, Hanjun; Liu, Jiahui; Huang, Qianqian; Yang, Donghui
To investigate the effects of temperature stress on metabolic and digestive enzyme activities of Procambarus clarkii, the test species was transferred from 20°C (control group) to 10°C and 30°C, and samples were collected at 0, 3, 6, 12, 24, and 48h. The activities of pyruvate kinase (PK), hexokinase (HK) and hosphoenolpyruvate carboxykinase (PEPCK) in muscle and hepatopancreas of Procambarus clarkii was determined. The changes in α-amylase (α-AMY) and lipase (LPS) activity in intestinal and hepatopancreas were also examined. The results showed that the activities of digestive and metabolic enzymes in Procambarus clarkii were significantly affected by extreme water temperature (P<0.05). During the whole experimentation period, PK, HK, and PEPCK activities in the low-temperature group (10°C) were lower than those in the control group (20°C) (P < 0.05). Meanwhile, LPS and α-AMY activities in the low-temperature group (10°C) were also significantly lower than those in the control group (20°C) (P < 0.05). In the high-temperature group (30°C), the activities of PK, HK, and PEPCK metabolic enzymes in muscle and hepatopancreas decreased first. Then they increased, and their activity levels were significantly lower than those in the control group (P<0.05). At the same time, the activities of LPS and α-AMY digestive enzymes in the intestines and hepatopancreas were significantly lower than those in the control group(P<0.05). In summary, this study examined the impact of temperature stress on the metabolic and digestive enzyme activities in Procambarus clarkii, shedding light on its self-regulation mechanisms in response to temperature fluctuations. The findings provide a scientific foundation for understanding the species' adaptation to environmental changes.
The difference in salinity tolerance between cultured and wild sea cucumber Apostichopus japonicus Selenka based on survival, enzyme activity and transcriptome analyses
(2024) Zhao, Yuming; Su, Yanmin; Chen, Rongjie; Wang, Feng; Liu, Bo
Salinity is a critical environmental factor affecting the growth, survival, distribution, and physiological processes of the sea cucumber, Apostichopus japonicus (Selenka). In this study, we examined the survival rates, enzymatic activities, and transcriptomes of one cultured and two wild populations of the sea cucumber, A. japonicus Selenka to compare their tolerance across a range of salinities. Significant differences in survival rates were observed among the three populations when exposed to salinity levels of 45, 40, 23, 20, and 17 psu. As salinity decreased, the activities of catalase, Na+-K+-ATPase, amylase and superoxide dismutase in cultured sea cucumbers peaked at 23 psu, and declined at 20 psu. In contrast, the activities of these enzymes in wild sea cucumbers decreased at 23 psu. At 40 psu, the four enzymatic activities significantly decreased in cultured sea cucumbers but continued to increase significantly in wild populations (P < 0.05). Transcriptomic analysis based on Gene Ontology (GO) function revealed the terms “cellular process,” “membrane” and “binding” were most enriched in the biological process, cellular component, and molecular function categories, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis identified “Glycerophospholipid metabolism” and “Starch and sucrose metabolism” among the top 10 most enriched pathways. The findings of this study provide new insights into the salinity tolerance adaptation of cultured sea cucumbers.
Identification and characterization of tissue-specific genes in response to handling stress in topmouth culter (Culter alburnus) kidney, liver and muscle tissues
(2024) Chi, Meili; Cheng, Shun; Zheng, Jianbo; Liu, Shili; Jiang, Wenping; Li, Fei
Topmouth culter (Culter alburnus) is an important freshwater economic fish in China. However, external stress often triggers strong reactions, resulting in low survival rates and reduced productivity. The absence of stress-related genes has significantly limited our understanding of stress response in this fish. Therefore, 85,846,206 high-quality reads were acquired from kidney, liver and muscle cDNA libraries of topmouth culter using illumina sequencing technology in this study. Comparative analysis revealed that 3,158; 409 and 1,952 unigenes were specifically expressed in the kidney, liver and muscle transcriptome, respectively. Additionally, 83 crucial tissue-specific genes were identified within three stress-related GO terms: response to stimulus (GO:0050896), response to stress (GO:0006950) and response to hypoxia (GO:0001666). From these, 18 tissue-specific genes were further isolated. During the short-term stress experiment (two repeated handling stress, including chasing 2 min and netting out of water for 30s), significant changes were observed in the cortisol levels of both the treatment and recovery groups. Furthermore, notable changes were noted in the expression of LCP2, PTK2b and P-selectin genes in the kidney; FABP1, IGFBP1 and CYP4V2 genes in the liver; and MYH10, Myogenin 2 and Toponin C genes in the muscle of topmouth culter in the treatment and recovery groups (P < 0.05). The tissue-specific transcriptome profiles generated in this study offer valuable insights into the molecular and functional mechanisms associated with stress response in topmouth culter. We characterizated genes related to stress response in tissues such as the kidney, liver and muscle, these findings offer novel insights into stress research in fish. We can further explore the breeding of strains with enhanced stress resistance and promote the healthy development of topmouth culter industry.
Study on the influence of digital inclusive finance on the development of provincial fishery economy and regional economic convergence in China
(2024) Chen, Lingsheng; Bai, Jianli; Xu, Shiwei; Cheng, Zhengrong; Chen, Jiahui; Chen, Yingjie
In recent years, the rapid development of digital inclusive finance in China has affected many aspects of social development, especially economic development, which has a good driving force. At the same time, the development of the fishery economy has been challenged by many aspects, and digital inclusive finance may inject new development momentum into the development of the fishery economy. Using the digital financial inclusion index and relevant data on the fishery economic development of 31 provinces, autonomous regions, and municipalities in China from 2013 to 2020, this paper empirically analyzes the impact of digital financial inclusion on provincial fishery economic development through the dual fixed effect panel data econometric model of controlled region and time. The main conclusions are as follows: The benchmark regression results show that digital inclusive finance can positively promote the development of the fishery economy at the significance level of 1%, and the digital development degree of digital inclusive finance also has a significant role in promoting the development of the fishery economy. After the endogeneity test of the system GMM model and a series of robustness tests, the model results are still significant. The results of the moderating effect model show that technological innovation plays a positive moderating role in the impact of digital inclusive finance on the development of the fishery economy, while the upgrading of the industrial structure plays an inhibitory role. Based on the results of the β convergence model, it can be found that there is no convergence in the level of fishery economic development among provinces. The development of digital inclusive finance will play a greater role in promoting areas with better fisheries and economic development, thus widening the development gap between regions. Finally, the paper discusses the effect of the conclusion and the improvement, which is of reference significance for the coordinated development of the fishery economy based on finance between regions.
Genetic Diversity and Structure of the Darkfin hind (Cephalopholis urodeta) in the Spratly Islands, Vietnam
(2024) Vo, Van-Thanh; Thai, Quan Ke; Le, Nguyen-Thanh-Thao; Doan, Thi-To-Nhien; Tran, Thi-Hieu; Do, Thanh Tri
The darkfin hind, Cephalopholis urodeta, is a commercially valuable reef fish species inhabiting the ecologically important Spratly Islands. Understanding this species' genetic diversity and population structure is crucial for developing effective conservation strategies, particularly given the increasing pressures on coral reef ecosystems. This study investigated the genetic diversity and population structure of C. urodeta within the Spratly archipelago using mitochondrial COI and Cyt b gene markers. We analyzed 30 individuals for COI and Cyt b, revealing high levels of haplotype diversity (Hd=0.9563±0.0226 for COI; Hd=0.9402±0.0229 for Cyt b). However, despite this high overall diversity, our analyses also revealed significant genetic structuring within the archipelago, suggesting restricted gene flow among some populations. This structuring is likely influenced by the complex oceanographic currents in the region and the spatial distance between reefs, which can limit larval dispersal. These findings highlight the need for spatially explicit conservation and management strategies for C. urodeta in the Spratly Islands. Recognizing the genetic differentiation within the archipelago and implementing management measures tailored to specific zones will be crucial for preserving genetic diversity, maintaining connectivity, and ensuring the long-term sustainability of this important resource.
Combined effects of vitamin E and temperature on the growth, biochemistry, and natural immune response of juveniles snubnose pompano (Trachinotus blochii)
(2024) Pham, Thi-Hanh; Tran, Vi-Hich; Le, Minh-Hoang
This study investigates the combined effects of Vitamin E and temperature on the growth, biochemical composition, and immune responses of juvenile snubnose pompano (Trachinotus blochii). A 70-day experiment was conducted with six treatments combining two levels of dietary Vitamin E (0 and 400 mg/kg) and three temperature levels (28°C, 31°C, and 34°C). The results revealed that both temperature and Vitamin E significantly influenced growth performance, feed utilization efficiency, protein and lipid content, and certain immune parameters (P < 0.05). Fish reared at 34°C with 400 mg/kg vitamin E demonstrated the highest growth indicators (SGR~L~, SGR~W~), protein efficiency, hepatosomatic index (HSI), and immune response, as indicated by elevated serum lysozyme levels, phagocytic activity, and white blood cells. Temperature notably affected lysozyme and respiratory burst activity, with values increasing at higher temperatures. Vitamin E supplementation improved these metrics regardless of temperature, increasing protein efficiency and reducing feed intake and feed conversion ratio (FCR). Moreover, Vitamin E enhanced immune responses, including increased white blood cell (WBC) counts and phagocytic activity. No interactive effects between Vitamin E and temperature were observed (P > 0.05). Overall, Vitamin E (400 mg/kg) positively influenced growth, biochemical composition, and immunity in snubnose pompano, particularly at elevated temperatures. The findings demonstrate that dietary vitamin E can enhance growth and immune performance, particularly under elevated temperatures, providing a basis for optimizing vitamin E use in snubnose pompano aquaculture.
Studies on the resistance of three pathogens isolated from wild Charybdis japonica and their pathogenicity in Portunus trituberculatus
(2024) Qin, Yawei; Tan, Yanmiao; Liu, Yufeng; He, Zhongwei; Han, Tian; Yang, Tianlei; Bai, Zishuo; Wang, Jianmeng; Gong, Chunguang
The coagulation property of hemolymph is one of the characteristic indicators of the immune function of crustaceans. This article focuses on the abnormal phenomenon of wild Charybdis japonica, where the hemolymph cannot coagulate in the Qinhuangdao Sea area. The pathogens were isolated and purified, and three dominant strains, N1, N2, and Q1, were obtained. These strains were identified as Vibrio natriegens, V. fortis, and Metschnikowia bicuspidata through morphological observation, physiological and biochemical experiments, and 16S rDNA or ITS sequence analysis. Subsequently, drug sensitivity and probiotic antagonism analyses were performed. Considering the potential for cross-species transmission of crustacean pathogens, the isolated pathogens may bring potential hazards to Portunus trituberculus, an important aquaculture economic species in China. Therefore, artificial infection and histopathological analysis were conducted on P. trituberculatus. The results of drug sensitivity and antagonism assays revealed that stain V. natriegens exhibited susceptibilities towards antibiotics such as streptomycin and norfloxacin, but 10 probiotics had no antagonistic effect on it; strain V. fortis exhibited susceptibilities to antibiotics such as tetracycline and chloramphenicol, moreover, strain V. fortis showed inhibitory effects on Bacillus velezensis and B. amyloliquefaciens. Strain M. bicuspidata exhibited drug susceptibility towards polymyxin B and showed inhibitory effects on B. toyonensis, B. velezensis, and B. amyloliquefaciens. The results of artificial infection tests using V. natriegens, V. fortis, and M. bicuspidata in P. trituberculatus showed cumulative mortality rates of 100%, 75%, and 35%, respectively, after 120 hours of infection. The hemolymph of the deceased P. trituberculatus following injection with strain V. natriegens or V. fortis exhibited a light blue and did not coagulate normally. Conversely, the hemolymph of the deceased crabs following injection with strain M. bicuspidata appeared milky white and normal coagulation. Histopathology examination demonstrated that strains V. natriegens, V. fortis, and M. bicuspidata can all induce lesions in several tissues. This study is the first to isolate V. natriegens and V. fortis from crustaceans, and the infection tests on the P. trituberculatus can replicate the symptoms, such as hemolymph noncoagulation. Based on these findings, it is speculated that the pathogens capable of casing hemolymph noncoagulation syndrome in P. trituberculatus may originate from wild C. japonica. The drug resistance and probiotic antagonism test results can provide a theoretical basis for precise medication and offer insights into the development and application of probiotic preparations targeting the three pathogens.
Isolation, Identification, and Molecular Evolutionary Analysis of Infectious Hematopoietic Necrosis Virus (IHNV) from Farmed Rainbow Trout in Southwest China
(2024) Li, Yankai; Li, Wenqian; Yang, Qian; He, Yang; Liu, Jiaxing; Ma, Yang; Li, Shuhan; Zhou, Yongheng; Li, Qiunan; Huang, Xiaoli; Chen, Defang; Geng, Yi; Wei, Wenyan; Ouyang, Ping
IHNV troubled the salmon breeding industry in China for years, and it often causes large-scale deaths. To study the disease characteristics of IHNV and its epidemiology in China， this study isolated and sequenced the Whole genome of an IHNV strain (IHNV-SCCD) (GenBank No： OQ801357) from farmed diseased rainbow trout in Chengdu and compared 99 IHNV strains from China by mega.11. The IHNV-SCCD strain was isolated by using EPC cells. The complete genome sequence was determined and deposited in the NCBI database. Phylogenetic analysis showed that IHNV-SCCD belongs to the typical J gene group, recently with Sichuan strains. Except for BjLL strain and LN12-17 strain, the remaining 98 strains followed a single evolutionary path. Note that IHNV in Liaoning province is the fastest evolutionary. In addition to the geographical differences, the Xinjiang strains were closely related to the Yunnan strains, and some strains from Beijing were closely related to some strains from Sichuan. There were two evolutionary branches in Gansu and Qinghai; QH17, isolated from Qinghai, was most closely related to SX1704 from Shaanxi. These results suggest that the prevalence of IHNV in China was extremely wide, and the evolution rate was fast. It is necessary to strengthen the monitoring and prevention methods.
Economic Benefits and Improvement Strategies for Clam Marine Aquaculture in China: A Comparative Analysis of Zhejiang, Tianjin, and Shandong
(2024) Chen, Yu; Xu, Shiwei; Cheng, Zhengrong; Liu, Zifei; Chen, Jiahui
In recent years, clam mariculture output in China has steadily increased. However, environmental pollution and high aquaculture intensity have led to frequent diseases and unstable economic benefits. This study analyzes field research data from clam farming in Zhejiang Province, Tianjin City, and Shandong Province, focusing on farming costs, revenue, break-even points, and net profit sensitivity. The findings reveal that (1) variable costs consistently exceeded fixed costs, particularly in seedling costs, labor, and water rental; (2) net profit and margins ranked highest in Zhejiang, followed by Tianjin and Shandong; (3) Zhejiang exhibited the lowest break-even operation rate and the largest price discrepancies; (4) sensitivity to selling prices was high across all regions, with Zhejiang showing the lowest sensitivity to variable costs. To enhance economic benefits and promote sustainable development, government authorities and industry stakeholders should focus on cultivating high-quality seeds, implementing scientific management, developing green aquaculture, and emphasizing brand development.
Effects of different feeding rates on growth performance, intestinal digestive enzyme activity, and intestinal microbial composition of red swamp crayfish (Procambarus clarkii)
(2024) Chen, Jinglong; Tian, Hongyan; Zhang, Wuxiao; Xia, Silei; Gao, Jian; Wang, Aimin; Ming, Jianhua; Zhang, Mengyue; Li, Mingyou; Zhang, Jiahong; Kou, Xiangming; Han, Guangming; Liu, Bo; Shao, Peng; Zhu, Aimin
The study aimed to investigate the effects of different feeding rates on the growth, muscle composition, intestinal digestive enzyme activities, and intestinal microbiota composition of juvenile crayfish (Procambarus clarkii). A total of 240 crayfish with an initial body weight of 8.33±0.50 g were randomly distributed into five groups, and each group had three replicates. The five groups corresponded to five different feeding rates of 2%, 4%, 6%, 8%, and 10% body weight per day (BW/day). The feeding trial lasted for six weeks. The results showed that the final body weight (FBW), weight gain rate (WGR), and specific growth rate (SGR) first increased when the feed rate increased from 2% to 6 % (P<0.05) and then showed a decreased trend with the further increase of the feeding rate, but no significant differences were observed. The feed conversion ratio (FCR) increased with a rise in feeding rate, which reached a peak at the feeding rate of 10% (P<0.05). The survival rate (SR), hepatosomatic index (HSI), and condition factor (CF) were unaffected by the feeding rates (P>0.05). The moisture, crude protein, crude fat, and ash contents of crayfish muscle remained unchanged among all feeding rate groups. Intestinal activities of lipase and amylase increase with the feeding rate (up to 6%) increasing (P<0.05). The ACE and Chao indices in the groups fed at 2% of feeding rate were significantly lower than those at a feeding rate of 10% (P<0.05). The relative abundance of Firmicutes in the groups fed at feeding rates of 4%, 6%, and 8% was higher than that in other groups (P<0.05), Citrobacter in the group fed at feeding rate of 6% was lower than that in different groups (P<0.05). The intestinal microbiota primarily functions in connection to amino acid, carbohydrate, and vitamin metabolism. Therefore, the optimum feeding rate could be 6.0% of the feeding rate of juvenile P. clarkii.
Digitalization and Operational Efficiency in Fisheries: Evidence from China
(2024) Sun, Lanlan; Zhang, Lu; Jiang, Qingqing; Zhao, Zhuming
Fisheries contribute significantly to the global economy while playing a crucial role in environmental conservation, food security, and socio-economic development. Analyzing the operational efficiency of the fisheries industry not only enhances its economic and social benefits but strengthens the sector's capacity for sustainable growth. This study initially evaluates the operational efficiency of Chinese fishery-listed companies using the DEA-BCC model and Malmquist index, both statically and dynamically, from 2012 to 2022. It then investigates the impact of digital transformation on the operational efficiency of these companies using the Tobit regression model. The findings reveal that the mean values of comprehensive, technical, and scale efficiency for Chinese fishery-listed firms are below 1, with scale efficiency exhibiting particularly low mean values under static conditions. Additionally, during the observation period, these companies' average total factor productivity decreased by 0.1% annually compared to the base period. From a dynamic perspective, the decline in total factor productivity can primarily be attributed to reduced technical efficiency resulting from decreased scale efficiency. Ultimately, it can be reasonably concluded that the operational efficiency of listed fishing firms can be significantly enhanced by implementing digital transformation. This underscores the potential of digitalization as a critical factor in advancing the fisheries sector, facilitating modernization, and enabling intelligent upgrading across the industry.
Prediction of Shrimp Price Based on WOA-VMD-XGBoost Algorithm and SHAP Model
(2024) Wu, Zhan; Qu, Tinghong; Cha, Sina; Wang, Chunxiao; Zou, Zongfeng
This research aims to construct a WOA-VMD-XGBoost-SHAP model to predict shrimp prices and analyze the nonlinear effects of key predictors. Firstly, the whale algorithm (WOA) is used to optimize the K-value and penalty parameter of the variational mode decomposition (VMD) to adaptively decompose the original price series and reduce the data noise. In addition, the trend, period, high and low frequency, and residual terms obtained from the decomposition of the original price series are used as inputs to the XGBoost model for training and testing. Finally, K-fold cross-validation and learning curves are used to test the model performance and analyze the nonlinear effects of key influencing factors in combination with the SHAP model. The results show that the Bayesian-optimized WOA-VMD-XGBoost model has excellent predictive performance with an R2 of 0.927, which is better than other benchmark models; the fluctuation of shrimp prices is cyclical, and the cyclical term accounts for 67% of the characteristic importance. The model can provide effective technical support and decision-making references for relevant management departments and enterprises to predict the price fluctuation of aquatic products.
Effects of Thermal Shock from Coastal Nuclear Power Plant Discharges on the Survival of Four Fish Species Under Variable Temperature Rise
(2024) Sheng, Pengcheng; Cai, Jiaying; Shao, Chenshan; Yu, Yebing; Jiang, Jiacheng; Nie, Xucheng; Sha, Zhanyu; Jiang, Mei; Li, Lei
In this study, we simulated water temperature changes under variable frequency temperature rise conditions caused by coastal nuclear power plant discharges and conducted thermal shock tests on four fish species: Trachinotus ovatus, Nibea albiflora, Larimichthys crocea, and Acanthopagrus schlegelii at acclimated water temperatures of 25.0°C and 27.5°C during the summer. The effects of these temperature variations on the thermal shock response of the four fish species were analyzed. The results indicated that at 25.0°C, the mortality rate of N. albiflora exhibited an overall upward trend with increasing temperature and duration frequency, with an average mortality rate ranging from 10±3.3% to 38.9±3.3%. For L. crocea, mortality was observed only in the 8.5ºC-100% duration probability group, while other groups had a 0% mortality rate. At 27.5°C, A. schlegelii showed an average mortality rate of 10±3.3% at an 8.5ºC-100% duration probability, with all other groups showing 100% survival. The average mortality rate of T. ovatus at 8.5ºC-100% was 6.7±3.3%, with no mortality in the other treatment groups. The expression level of the hsp70 gene in the liver of N. albiflora increased with higher temperature rise amplitudes and longer frequency conversion durations. Similarly, the hsp70 gene expression in L. crocea and A. schlegelii increased with rising temperatures, though there were no significant differences among groups with varying frequency conversion times. In contrast, the hsp70 gene expression in T. ovatus remained relatively stable across temperature rise treatments, showing no significant differences with varying frequency conversion durations. The heat stress tolerance ranking among the four fish species was determined to be L. crocea \> N. albiflora \> T. ovatus \> A. schlegelii.

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