Abstract:The channel connecting the Poyang Lake and the Yangtze River is an important channel for most migratory fish to complete their life cycle process, and so has an important ecological function for the conservation and diversity of fish resources in the middle and lower reaches of the Yangtze River. In this study, acoustic detection, remote sensing, and three-dimensional hydrodynamic simulation were combined to understand the spatial distribution and habitat status of fish with different body length in the channel connecting the Poyang Lake and the Yangtze River through the winter period. Firstly, the single factor habitat suitability index (HSI) curves of water depth, flow velocity, and slope of three fish groups with different body length were drawn, and then the product method was used to establish the habitat suitability model. Finally, the habitat suitability of fish in different sections of the channel connecting the Poyang Lake and the Yangtze River was compared and evaluated. The results showed that the average length of fish in the channel was 10.1 cm, and the fish were mainly distributed in Hukou, Mountain Xie, and Pingfeng area. The most suitable water depth range for fish groups with body length of 1–20 cm was 3.06–4.59 m and 9.18–12.24 m, with a flow velocity range of 0.05–0.13 m/s and slope range of 0–2.23°. The habitat suitability curves of water depth, flow velocity, and slope of fish that were sized 20–40 cm and over 40 cm were unimodal, and the most suitable range of water depth, flow velocity, and slope of the 20–40 cm fish group were 9.18–13.77 m, 0.05–0.13 m/s, and 0–2.23°, respectively. For fish with body length over 40 cm the most suitable ranges of water depth, velocity, and slope were 13.77–15.3 m, 0.10–0.13 m/s, and 0–2.23°, respectively.

Abstract:Salinity is an important parameter to characterize the physical properties of water bodies. In order to explore the ability of remote sensing data to measure the salinity of low-salt lakes, this study used remote sensing reflectance data in blue, green, red, and near-infrared bands with 10 m spatial resolution of sentinel-2 to analyze the relationship between measured surface salinity and reflectance in the Co Ngoin Lake. Based on different combinations of variables, which included the reflectance of four bands and normalized difference water index (NDWI), a linear regression model was constructed with salinity data, and the accuracy evaluated. The model was also used to invert the surface salinity of the Co Ngoin Lake. The results showed that the correlation between reflectance and salinity in the green band was higher than that in other bands. However, the near-infrared band reflectivity had the highest correlation with salinity, when the salinity was lower than 3. Among the 9 models with the combination of variables, the addition of the NDWI variable improved the accuracy of model inversion, which was higher than the accuracy of the model without the NDWI variable. The linear regression model of the three variable combinations of NDWI, near-infrared band and blue band had the highest accuracy of salinity inversion. The mean absolute error (MAE) was 0.103, and the salinity observed value and predicted value correlated well. In the combination without NDWI variable, the salinity inversion accuracy of the green band and red band was high, with MAE of 0.126. The spatial distribution of water surface salinity of the Co Ngoin Lake generally presented a spatial pattern of low salinity at the shore and estuary, and high and relatively uniform distribution within the lake. From the inversion results, the average salinity of the Co Ngoin Lake was approximately 4.14, which was very close to the measured average (4.15). The results verified the effectiveness of the multispectral remote sensing method, which has the advantages of being fast, convenient and highly accurate in predicting the water surface salinity of the Co Ngoin Lake. This study has guiding significance for low lake surface salinity inversion using high-resolution multi-spectral remote sensing data. In addition, it has significant value for the protection and sustainable use of aquatic biological resources.

Abstract:Understanding the spatial pattern of human fishing activities is very important for fishery resource supervision and spatial management. In order to understand the spatial distribution characteristics of squid fishing vessels in the southwest Atlantic Ocean and its relationship with the marine environment, fishing effort information was calculated based on the squid fishing vessels trajectory data in the southwest Atlantic Ocean from January to May during 2018–2019 and analyzed for variation in the center of activity. The overlay maps of the spatial distribution of environmental factors and fishing effort were plotted together with three environmental data sets of the same period: sea surface temperature (SST), sea surface height (SSH), bottom temperature (BT) and chlorophyll-a (CHL-a), to investigate the relationship between the spatial distribution of fishing effort and environmental factors. The Generalized Additive Model (GAM) was used to construct a non-linear expression of fishing effort on the marine environment, and to analyze the impact of changes in the marine environment on squid fishing vessel activity in the southwest Atlantic Ocean. The results showed that the fishing effort of the boats in the study area at first increased and then decreased from January to May, and the fishing effort was the highest in February. The center of gravity of fishing boats has obvious zonal monthly changes. From January to May, the center of gravity of fishing boats shifted from north to south as a whole. The operations of squid fishing boats are mainly distributed in areas with sea surface temperature of 8–15 ℃, sea surface height of 0.14–0.16 m, bottom temperature of 5–8 ℃ and CHL-a concentration of 0.2–0.6 mg/m3 . The GAM model shows that spatial factors and environmental factors have a significant impact on the distribution of squid fishing in the southwest Atlantic Ocean. The synergy of longitude and latitude contributed the most to the explanatory variance of fishing effort. Four environmental factors, SST, SSH, CHL-a, and BT, all have important effects on fishing effort. The effects of all variables on fishing effort are non-linear. The most closely affected range of SST is 14–15 ℃, the most closely affected range of SSH is –0.1–0.02 m, the most closely affected range of BT is 5–6 ℃, and the most closely affected range of CHL-a concentration is 0.2–0.4 mg/m³ .

Abstract:Liza haematocheila is an important economic fish in the Yellow River estuary waters. The species lays eggs which hatch as larvae in the shallow waters, or the interchange areas of salt and fresh water in the estuary every spring, and move to coastal waters to grow within changing tides. The fish migrate into the deep-water area of the Bohai sea for winter. Fish eggs and larvae are the basis of supplement and sustainable utilization of marine fish resources, and changes in their quantitative distribution are very significant to maintain the balance of marine ecosystems. At present, the researches on Liza haematocheila mainly involve such parameters as age, growth, feeding, breeding habits, etc. However, there is no report on the distribution of Liza haematocheila eggs and larvae in the coastal zone of the Yellow River estuary. In order to understand the distribution of Liza haematocheila eggs and larvae, and to investigate thoroughly the impacts of environmental factors on such distribution in the coastal waters of the Yellow River estuary, this study analyzed the spawning period, spatial distribution of fish eggs and larvae of Liza haematocheila and their relationship with environmental factors. Data were collected from a spawning grounds survey conducted during April and July of 2020 and from a set net survey during April and November of 2020. Due to no eggs and larvae being caught during some sampling events, a two-step GAM was constructed which modeled presence/absence data (PA model) and density of presence observation (density model). The results indicated that the peak spawning period of Liza haematocheila was from April to May in the coastal waters of the Yellow River estuary. The spatial distribution characteristic of fish eggs was different from larvae, with fish eggs being concentrated in the coastal waters of Laizhou Bay, and larvae distributed in Laizhou Bay and the estuary of the Yellow River. Water temperature was significantly associated with both presence and density of fish eggs and larvae. For the PA model, SST (sea surface temperature) was the second most important factor and determined more than 13% of the deviance, while the final model determined 61.50% of the variance in fish eggs and larvae presence/absence. For the density model, SST determined the largest portion of the data deviance (＞ 50.21%) and the final model determined 67.04% of the variance in density, given presence. Both occurrence and density of fish eggs and larvae were mainly in the range of 11–14 ℃ and 19–22 ℃. However, variation of temperature affected them in different ways. As water temperature increased from 11 ℃ to 14 ℃, the occurrence probability increased, but the density at first decreased and then increased. During temperature increase from 19 ℃ to 22 ℃, both showed a trend decreasing first and then increasing, but the change of density was much greater than the occurrence probability. Salinity had a significant effect on the occurrence of fish eggs and larvae, with explaining 8.01% of the deviance of the PA model; however, it had no obvious effect on density. Fish eggs and larvae of Liza haematocheila occurred in the salinity range of 24–30, with the most concentrated distribution and a fluctuating upward trend occurring between 26.5 and 29. Depth was significantly associated only with the occurrence of fish eggs and larvae, which were distributed between 1 m and 10 m. The occurrence probability decreased slowly with the increase of water depth and was most concentrated at 2–6 m. This supports the view that Liza haematocheila lay eggs in shallow water near the shore. The results of the study provided a scientific basis for the protection of spawning grounds and resource conservation. It also proved that the application of remote sensing of water temperature was feasible for fishery ecological research in estuarine and nearshore waters.

Abstract:Sthenoteuthis oualaniensis has significant economic potential as a catchable species in the Northwest Indian Ocean. To study the spatial and temporal distribution of S. oualaniensis and its relationship with relevant environmental factors, we conducted fishing ground analyses, geostatistical interpolation, and generalized additive model analyses using sea surface temperature (SST), chlorophyll-a (Chl-a) concentration, and logbook data from January to March and August to December in 2017. Our results indicate that: (1) S. oualaniensis fishing grounds are mainly distributed around the oceanic front; (2) the centers of gravity of S. oualaniensis fishing grounds range from 13.6°N to 17.2°N and from 58.3°E to 62.2°E, with migration occurring towards the southwest from January to March, then towards the northeast from August to November, and then towards the southwest in December; (3) S. oualaniensis prefers SST between 25.5–27.0 ℃ and Chl-a concentration 0.2–0.4 mg/m; (4) the catch per unit effort (CPUE) of S. oualaniensis varies significantly during the year. Our study contributes to understanding S. oualaniensis stock distribution and can be further applied for sustainable management in the Northwest Indian Ocean.

Abstract:Fish spawning grounds are affected by changes in environmental conditions. Rapid and effective identification of fish spawning grounds is crucial for assessing aquatic resources and protecting rare aquatic animals. In this study, based on aerial images captured by drones and field surveys, we identified 77 spawning grounds of Qinghai Lake naked carp (Gymnocypris przewalskii). By constructing a sampling method suitable to rivers and improving sampling technology, we obtained 807 sets of training samples, 56 sets of verification samples, and 23 sets of test samples; of these, the test samples were not enhanced. By linking the lightweight UNet and NestedUNet models in a chain, a UNet-NestedUNet deep learning model was established, and its performance was compared with UNet and NestedUNet models with twice the number of channels. The results showed that UNet-NestedUNet model performed better on the validation set. Model validation accuracy was the highest in the 51st step of training. The training intersections over union ratio and accuracy of the model were 0.870 and 0.996, respectively, and the validation intersection over union and accuracy were 0.648 and 0.985, respectively. Considering the test results, accuracy was lower than general remote sensing image or image segmentation accuracy. However, the deep learning model effectively identified most of the spawning grounds of Qinghai Lake naked carp (79%). In the entire area, the model identified 61 out of 77 spawning grounds, and only one spawning ground in the test area was not identified. In addition, the model identified a large number of unmarked areas as spawning grounds; these may be small areas not considered during manual identification, or misjudged by the model. This discrepancy may be caused by the relatively small number of actual samples used for training and the uncertainty of the spawning ground itself. The former can be resolved by obtaining more spawning ground samples of Qinghai Lake naked carp through long-term data accumulation. For the latter, it is necessary to further refine spawning field boundaries. At present, deep learning can be used as an auxiliary means to identify spawning grounds of Qinghai Lake naked carp. With the continuous increase in the number of cumulative samples in the future, the performance of the model will further improve. Therefore, the deep learning model has prospective applications in the identification of fish spawning grounds

Abstract:The sea cucumber (Apostichopus japonicus) is an important aquaculture species in northern China. As a typical temperate species, the sea cucumber is very sensitive to high temperatures. When the ambient temperature exceeds the upper thermal tolerance limit of the species, a series of complex physiological responses can be induced, some leading to large-scale death. High temperature and marine heat waves in the summer are environmental factors that are known to damage the sea cucumber pond aquaculture. For evaluating and predicting the effect of high temperature on sea cucumber pond aquaculture and selecting suitable aquaculture areas, hourly summer temperature data (July to August) in 2011–2020 were collected, and the 99th percentile high temperature value (T₉₉) of each grid point was defined as the intensity of extreme high temperature in each year. The relationship reported in the literature between temperature and survival rate, as a physiological proxy of the sea cucumber, was calculated by using a three-parameter logistic model. Based on the calculated relationship between temperature and survival rates, the semi-lethal high temperature of the sea cucumber was found to be (31.7±0.15) ℃. Ambient temperature higher than 31.7 ℃ was defined as disaster-causing temperature. The vulnerable areas of sea cucumber pond aquaculture to high temperature were ranked based on the disaster-causing event frequency. Areas of risk in aquaculture ponds under three representative concentration pathways scenarios (RCP2.6, RCP6.0, and RCP8.5) were identified based on the predicted survival rate of sea cucumbers from 2046 to 2050. The results showed that the average temperature (1.27 ℃/10 a) and the maximum temperature (2.15 ℃/10 a) increased in the coastal areas of northern China from 2011 to 2020, and the sea cucumber pond aquaculture areas in northern China, particularly in the southwest Bohai Sea, encountered disaster-causing temperatures frequently. The total frequency of disaster-causing events has shown a clear increasing trend from 2011 to 2018, and the number of affected areas have also kept increasing, with 10% of areas for sea cucumber pond aquaculture suffering from disaster-causing temperatures in 2011, while more than 40% of the areas experienced disaster-causing temperatures in 2018. In 2019 and 2020, 20% of the pond aquaculture areas suffered from disaster-causing temperatures. High frequency of disaster-causing events mainly occurred in the southwest of Bohai Sea and in the Liaodong Bay. Under the scenarios of RCP2.6, RCP6.0, and RCP8.5, T₉₉ will continue to rise in most coastal areas in northern China where temperatures can reach 40 ℃ in some regions. Under the impacts of global warming, those previously appropriate aquaculture areas would possibly no longer be suitable for the culture of sea cucumbers, and the risk from exposure to high temperatures will increase throughout the bays of Bohai Sea. The present study implies that sea cucumber pond aquaculture in China has been sensitive to high temperatures in the past and will be even more vulnerable to much higher temperatures in the future. Therefore, in the context of global warming, there is an urgent need for heat risk assessment models on micro-scale or meso-scale for the sustainable development of aquaculture. In conclusion, the local temperature conditions need to be fully considered in the development of sea cucumber pond aquaculture, and an adaptative management plan needs to be established for coping with increasing temperatures in the future.

Abstract:采用人工驯食方法改变肉食性鱼类的食性是其养殖过程中的关键环节, 但目前对鱼类食性驯化的分子遗传机制了解甚少。为了获得大口黑鲈(Micropterus salmoides)食性驯化相关基因和标记, 本研究以 1 月龄大口黑鲈“优鲈 3 号”为研究对象, 对驯化其摄食人工配合饲料后的易驯食组和不易驯食组脑和肝脏组织进行转录组测序和分析。结果表明, 共获得 51255 万条高质量 clean reads, 注释到 27930 个基因, 易驯食组和不易驯食组脑和肝脏组织中差异表达基因分别为 362 和 3389 个, 其中参与调控食性驯化的基因 64 个, 如周期蛋白(period, PERs)、视紫红质 (rhodopsin, RHO)、视黄醇脱氢酶(retinol dehydrogenase, RDHs)、角鲨烯单加氧酶(squalene monooxygenase, SQLE)、 胆汁酸输出泵(bile salt export pump, BSEP)、瘦素(leptin, LEP)等主要分布在昼夜节律、光传导、视黄醇代谢、类固醇生物合成、胆汁分泌和 PI3K-AKT 信号通路中, 这些通路在环境适应、视觉系统、消化代谢、食欲控制等生物过程中发挥重要作用。从不易驯食组和易驯食组的差异表达基因中筛选出 21465 个 SNP 标记, 进一步采用 SNaPshot 技术对其中 14 个 SNP 标记在易驯食和不易驯食群体中进行验证并与驯食性状进行关联分析, 结果显示仅 RDH12 基因中的 chr15-A+8322808G 位点与驯食性状存在显著关联性(P＜0.05), 其 AA 基因型为易驯食个体的优势基因型。本研究分别获得了与大口黑鲈驯食性状相关基因 64 个和 SNP 标记 1 个, 为分子标记辅助大口黑鲈食性驯化遗传改良提供了候选基因和标记。

Abstract:The mechanisms of high-altitude adaption in Glyptosternum maculatum, an endemic fish from the Tibet Plateau, further provides a foundation for investigation. In this paper, the mechanism of metabolic differences between the liver and exo-celiac liver of G. maculatum was studied by histological and biochemical methods and Transcriptomics. The results showed that there were no significant differences in the structure, the number of mitochondria, and the protein composition of mitochondria between the liver and exo-celiac liver. A total of 138,515 unigenes with an average length of 814 bp were obtained from the two tissues. Compared with the liver, 45 upregulated genes and 32 down-regulated genes were detected in the exo-celiac liver. Through GO analysis, DEGs such as Hmgcl, Tbxas1, Cask, Sumf1, Jak1, and Glxk, which are involved in amino acid and fatty acid metabolism, were screened out. KEGG analysis showed different expression genes enriched in butanoate and tryptophan metabolism, peroxisome, valine, leucine, lysine, and isoleucine degradation, and other metabolic pathways. Four differential expression genes were selected for qRT-PCR detection. It was found that the results of qRT-PCR were consistent with the sequencing results of the transcription group. In conclusion, there are differences between amino acid, fatty acid, and energy metabolism between the liver and exo-celiac liver of G. maculatum. The mechanisms may be related to the significant differential expression of Hmgcl, Ptk2b, Gba, and Dnm1l genes in the liver and exo-celiac liver. In this study, we screened the key genes and signaling pathways that regulate liver metabolism mechanisms in G. maculatum, which laid a theoretical foundation for revealing the different metabolic mechanisms between the liver and exo-celiac liver of G. maculatum.

Abstract:Due to their short lifespan, rapid maturation, strong coupling to lower trophic levels, and quickly replenishing resources, populations of small pelagic fishes are often excellent bio-indicators of climate-driven changes in marine systems worldwide. This was particularly evident during each of the survey periods undertaken in this study in the Laizhou Bay of Bohai Sea, where the eggs and larvae of small pelagics were the main components of the ichthyoplankton community (1982–2019). The major small pelagics taxa in the Laizhou Bay were Japanese anchovy Engraulis japonicus, dotted gizzard shad Konosirus punctatus, Japanese sardinella Sardinella zunasi, kammal thryssa Thryssa kammalensis, scaly half-fin anchovy Setipinna tenuifilis, and Japanese halfbeak Hyporhamphus sajori. Based on a pooled analysis of the historical data of almost 40 years and combined with the field survey of current fish habitat conditions, a long-term data set of ichthyoplankton with major habitat factors in the Laizhou Bay was built. Firstly, general additive modeling and general line modeling were used to interpret the correlations between changes in ecological density number in early life history (EDN-ELH) and habitat environmental factors for each of the small pelagics taxa, and species-specific spawning habitat optima (temperature, salinity and depth) were also examined. Secondly, the decadal distribution patterns of the spawning ground or nursing area of each of the small pelagics would be plotted by using the interpolation method in Geostatistical Analyst of ArcGIS Software. Third, the time series analysis and canonical correspondence analysis would be used to examine the synchrony of variation patterns, by comparing time series data of EDN-ELH statistics of major small pelagics along with climate indices e.g., Pacific Decadal Oscillation (PDO), Multivariate ENSO Index (MEI), etc., monthly runoff of the Yellow River (MRYR) and annual fishing effort in the whole Bohai Sea from 1982 to 2019. The results conveyed that spawning activities of the small pelagics were concentrated in the water temperature increasing season. The main spawning period of the Japanese anchovy and dotted gizzard shad was slightly earlier. Other species such as the kammal thryssa, Japanese sardinella, Japanese halfbeak and scaly half-fin anchovy spawned later. Each of the small pelagics taxa examined in the Laizhou Bay adapts to a wide range of optimal temperatures and seawater salinity for spawning (eurytherm and euryhaline species). There was a species-specific spatio-temporal distribution pattern of the spawning ground or nursery area of each of the small pelagics in the Laizhou Bay, which was influenced by water diluted by the Yellow River and the offshore water. Each small pelagics taxa adapts to spawn at the low salinity estuarine and nearshore waters (except Japanese anchovy), with a general near-shore distribution trend when comparing the location of its nursery areas to the spawning ground. EDN-ELH of each small pelagics taxa was in interannual and decadal fluctuation, as was the distribution patterns of its spawning ground or nursing areas. Compared with the 1980s, EDN-ELH of Japanese anchovy, dotted gizzard shad and Japanese sardinella had decreased significantly, while EDN-ELH of kammal thryssa increased significantly, and half-fin anchovy and Japanese halfbeak remained constant. In the PDO and MEI warm phase, EDN-ELH of Japanese anchovy and Japanese halfbeak remained at a higher level. In contrast, in the PDO and MEI cold phase, EDN-ELH of kammal thryssa, scaly half-fin anchovy, Japanese sardinella and dotted gizzard shad remained at a higher level. MRYR had significant effects on the EDN-ELH of all the small pelagics except scaly half-fin anchovy. The EDN-ELH of Japanese anchovy and Japanese sardinella was significantly negatively correlated with the MRYR, while dotted gizzard shad, kammal thryssa and Japanese halfbeak was positively correlated with the MRYR. Fishing has a significant effect on EDN-ELH of Japanese anchovy and dotted gizzard shad, due to high fishing intensity applied to their spawning stock outside of the closed season before 2017. This study interpreted the recruitment variation and “bottom-up” or “top-down” factors that may affect the early life stage recruitment process. The factors fill the gaps in knowledge that currently limit our ability to understand the key mechanisms involved in responses of small pelagic fish species to environmental changes in Laizhou Bay of the Bohai Sea.

Abstract:为探明长江口海上风电场水域的鱼类群落结构及其影响因素, 本研究利用多元统计和冗余分析(RDA)等方法对该水域鱼类群落组成及其与环境因子的关系进行分析。春、秋季共获得鱼类 28 种, 隶属 6 目 15 科 26 属; 鲈形目鱼类占比最高(57.14%), 其中以虾虎鱼科鱼类最多(21.43%)。鱼类组成以海洋性、暖温性、底层鱼类为主。春季优势种为棘头梅童鱼 (Collichthys lucidus) 、刀鲚 (Coilia nasus) 、凤鲚 (Coilia mystus) 、拉氏狼牙虾虎鱼 (Odontamblyopus lacepedii)和鮸(Miichthys miiuy), 秋季优势种为龙头鱼(Harpadon nehereus)、凤鲚、棘头梅童鱼、 刀鲚和鮸。多样性分析和 ABC 曲线表明, 调查水域鱼类群落结构处于受干扰状态。T 检验显示, 风电场水域鱼类的丰度、生物量、丰富度指数(D)、均匀度指数(J')和多样性指数(H')均与邻近水域无显著性差异(P＞0.05)。等级聚类和非度量多维排序(NMDS)表明, 长江口海上风电场及邻近水域鱼类群落分为春季和秋季 2 个组群。相似性检验 (ANOSIM)显示 2 个组群差异极显著(R=0.726, P＜0.01), 群落结构的季节更替明显。RDA 表明鱼类群落结构受溶氧、 温度、深度和盐度的综合影响, 不同环境因子对不同生活史阶段优势种的影响作用不同。结果表明, 长江口海上风电场及邻近水域鱼类群落结构的干扰状态主要与季节和环境因素相关, 风电场对其影响有限。

Abstract:为了研究北太平洋柔鱼(Ommastrephes bartramii)不同群体胴体形态的生长变化, 运用传统的形态测量法和基于地标点的几何形态测量法对两个群体共 214 尾柔鱼的胴体形态进行了形态学分析。结果表明, 柔鱼个体形态在群体和胴长组两个因子的交互作用上存在显著性差异(P＜0.01)。主成分分析显示, 东部和西部群体柔鱼不同胴长组分区均较为明显, 部分空间位置有一定的重叠。薄板条样分析与传统形态测量结果相似, 结果表明, 相对于西部群体, 东部群体柔鱼的鳍部更大, 胴体更细长, 不同群体柔鱼形态在不同胴长组间发生变化。多元回归分析表明, 东西部群体在不同胴长组间均具有不同的生长模式。在同一胴长组内, 两个群体在 300~400 mm 阶段的生长差异最大。结论认为, 不同群体柔鱼形态、异速生长模式随着个体的生长逐渐发生改变。

Abstract:A ranavirus that caused high mortality of largemouth bass (Micropterus salmoides) in Huangpi, Hubei was isolated and identified by using cell culture and transmission electron microscopy (TEM). The clinical symptom of diseased fish showed hemorrhages and ulcers on the skin and a pale liver. The typical cytopathic effect (CPE) was observed in the cells of the mandarin fish brain (MFB) that were infected with the filtrate of diseased fish tissue homogenate, and the viral titer was approximately 10^8.36±0.15 TCID₅₀/mL. A large number of hexagonal virus particles with a diameter of approximately 150 nm aggregated in a pseudocrystalline array in infected MFB cells. The mortality of artificial infection reached 100% within 7 days post infection, and the clinical symptoms were similar to those of naturally diseased fish. A 241 bp specific positive fragment was obtained by a largemouth bass virus (LMBV) PCR assay of both naturally diseased fish and infected cells. According to the sequence of major capsid protein (MCP) gene of LMBV in GenBank, the specific primers were designed and a 1392 bp full length sequence of open reading frame (ORF) was obtained from the above samples. The amino acid sequence shared 100% identity with that of Santee Cooper frog virus, guppy virus type 6 and largemouth bass ulcer syndrome virus. Phylogenetic analysis showed that the virus had the highest homology with ranavirus which infects fish, such as mandarin fish ranavirus, Santee-Cooper ranavirus, largemouth bass ulcerative syndrome virus, guppy virus et al. MCP amino acid sequence analysis indicated that the virus belonged to genus Ranavirus of the family Iridoviridae, and the virus was designated as largemouth bass ranavirus LMBRaV-HB001. The typical CPE could also be observed in epithelioma papulosum cyprinid (EPC) cells, grass carp ovary (GCO) cells, giant salamander muscle (GSM) cells, and gibel carp brain (GiCB) cells infected with cell cultured virus, and the viral titer reached over 10^8.0 TCID₅₀/mL. In this study, LMBRaV was first isolated and identified in cultured largemouth bass in Hubei province, and the sensitive cell lines of the virus were also screened. These results will provide critical foundation for the transmission, diagnosis, prevention and control of ranavirus.