Table of Content

25 October 2023, Volume 45 Issue 5

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Research Paper

Genome analysis of pathogenic Vibrio harveyi strain TS-628

LI Chenrui, XU Rongliang, ZHANG Xiaoxu, CHEN Dongping, QIU Yuyang, CHEN Weiqin, QIN Yingxue

2023, 45(5):  415-426.  DOI: 10.14012/j.cnki.fjsc.2023.05.001

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V.harveyi is an important opportunistic pathogen of marine fish and invertebrates,which often causes serious diseases of mariculture animals and brings huge economic losses to the aquaculture industry.However,the virulence of V.harveyi isolated from different environments varies greatly.In the present study,the sequencing technology combining the second generation Illumina Hiseq platform and the third generation PacBio platform was used to sequence and analyze the genome of V.harveyi strain TS-628 isolated from the diseased Epinephelus awoara.The genome information of this strain was exploited to understand the virulence related genes of the pathogen,in order to provide data support for the subsequent research on the pathogenesis of V.harveyi and control of V.harveyi disease.The results revealed that the genome of V.harveyi strain TS-628 had two chromosomes and two plasmids.One of the plasmids was a newly discovered plasmid.The genome size of this strain was 6 151 198 bp,the GC content of the genome was 44.68%,the number of predicted genes were 5 658,the number of predicted virulence genes were 747.The 747 virulence genes were mainly related to bacterial adhesion,iron uptake and secretion systems.In addition,294 drug-resistant genes were found,reflecting that the V.harveyi strain TS-628 not only had the potential to encode multiple virulence factors,but also had the potential to resist multiple antibacterial agents.

Body mass of Seriola dumerili prediction model based on LSSA-XGBOOST improved algorithm

YU Guoyan, ZUO Renyi, YAN Jun, LUO Yingtong, ZHU Qiheng

2023, 45(5):  427-437.  DOI: 10.14012/j.cnki.fjsc.2023.05.002

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In order to build an accurate feeding model using mass judgment and obtain the body mass state of S.dumerili in real time,this study built a body mass prediction model based on LSSA-XGBOOST algorithm.Firstly,the data of body length,body width and body mass measured by the culture experiment ship were detected by extreme studentized deviate (ESD) method,and the abnormal points were removed.Secondly,the chaotic random number generator was used to complete the initial population optimization of the SSA algorithm to improve its searching ability.The optimized SSA algorithm was used to optimize three parameters of the optimal tree depth,the optimal learning rate and the optimal number of iterations of the XGBOOST model.Finally,the LSSA-XGBOOST model with body length and body width as the input and body mass data as the output was constructed.The experimental results showed that,compared with the conventional mathematical model fitting,the LSSA-XGBOOST model fitting correlation coefficient R² increased by about 10%.Compared with the traditional BP neural network and PSO particle swarm optimization BP,the error square and R² were improved by about 3%,and the mean absolute error (MAE),mean square error (MSE) as well as the root mean square error (RMSE) were significantly reduced.It could be seen that LSSA-XGBOOST model was more accurate for predicting the body mass of small samples of S.dumerili,and the construction of LSSA-XGBOOST model was greatly significant for users to grasp the growth state of S.dumerili and build accurate feeding model for mass judgment.

Correlation analysis between the nacre color and the shell color of four selected strains of mussels,Hyriopsis cumingii

LUO Yu, ZHANG Wenfu, REN Gang, CHENG Xiaoling, FANG Aiping, YE Ronghui, ZHANG Wenna, AN Xianbo, ZHANG Genfang

2023, 45(5):  438-447.  DOI: 10.14012/j.cnki.fjsc.2023.05.003

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The nacre color is the main factor that determines the color of the cultivated pearls.The nacre color trait has become an important target trait of the genetic improvement of the pearl oyster,but the measurement of the nacre color is difficult,which seriously limits the efficiency of pearl mussel breeding.Using 1-year-old red,blue,golden and white strains of juvenile H.cumingii as experimental materials,the color parameters L,a and b values were obtained by the X-Rite ColorEye XTH spectrophotometer,while correlation analysis,principal components analysis,and regression analysis were performed on each color parameter to explore the correlation between nacre color and shell color.The results showed that the nacre color and the shell color of the four H.cumingii strains were significantly correlated,and the correlation between the nacre color and the shell color of the red and blue strains was relatively stronger.The L,a and b values of nacre color in red and blue strains were all significantly correlated with at least one color parameter in shell color.Among them,the a value of nacre color in red strains had the strongest correlation with the b value of shell color,with the correlation coefficient as -0.557 (P<0.01).The L value correlation between the nacre color and the shell color was the strongest in the blue strain,and the correlation coefficient was 0.533 (P<0.01).The L value of the shell color in the golden strain was significantly correlated with the a and b values of the nacre color (P<0.05),and the correlation coefficients were 0.331 and 0.335,respectively.In the white strain,only the a value had a very significant correlation between the nacre color and the shell color (P<0.01),and the correlation coefficient was 0.286.This study reveals that the nacre color is correlated with the shell color in these four H.cumingii strains of juvenile mussels,which is of great significance for guiding the early selection of nacre color of H.cumingii.

Comparison analysis and path analysis of quantitative traits of triploid Crassostrea angulata cultured in inner and outside Huangqi Bay,Fujian Province

QI Jianfei, WEI Shanshan, ZHENG Shenghua, LUO Huiyu, YAN Congyi, WU Qisheng, XU Cuiya, LIN Qi

2023, 45(5):  448-454.  DOI: 10.14012/j.cnki.fjsc.2023.05.004

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To evaluate the culture performance of triploid Crassostrea angulata cultured in inner and outside Huangqi Bay,9 month ages oysters rope-cultured were sampled randomly in Huangqi Bay,Lianjiang,Fujian Province.The shell length(X_L),shell width(X_W),and shell height(X_H),as well as the total weight(TW) and meat weight(MW) were measured for 85 individuals respectively.One-way analysis,multiple regression analysis and path analysis were used for investigating the morphological variation.One-way ANOVA showed that besides shell height,all morphological parameters of the oysters cultured outside the bay were significantly larger than those in the bay.The oysters cultured outside the bay were more round at shape and higher in meat condition.The optimum multiple regression equations were obtained though stepwise multiple regression analysis.As path analysis,the direct effects of morphological parameters on total weight were in order of shell length>shell width>shell height.Shell length had the maximum direct effect on the total weight,and was the major factor.The correlation indices (R²) of morphological parameters against the total weight was less than 0.850,indicating some other factors associating total weight,besides shell length,shell width and shell height,such as meat condition and shell weight.

A north-south relay aquaculture experiment of Strongylocentrotus intermedius

WANG Weigang

2023, 45(5):  455-461.  DOI: 10.14012/j.cnki.fjsc.2023.05.005

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In order to explore the feasibility of the north-south relay aquaculture model for S.intermedius between Fujian and Shandong Province,raft aquaculture experiments were conducted in the Qida sea area of Lianjiang,Fujian and Yandunjiao sea area of Rongcheng,Shandong from March 2021 to April 2022.Using abalone raft aquaculture facilities,regular feeding of kelp (Laminaria japonica) and asparagus (Gracilaria lemaneiformis) were carried out.After 13.5 months of breeding,the shell diameter of large-size S.intermedius had reached (61.97±2.38) mm,the body mass had reached (93.13±9.84) g,and the gonadal index had reached 17.69%±1.84%.The shell diameter of the middle-size S.intermedius had reached (58.20 ± 3.03) mm,the body mass had reached (68.43±8.88) g,and the gonadal index had reached 15.38%±1.44%.The shell diameter of the small-size S.intermedius had reached (51.39±2.41) mm,the body mass had reached (53.28±8.71) g,and the gonadal index had reached 13.45%±1.39%.The experimental results showed that according to the seasonal differences in seawater temperature between Fujian and Shandong,S.intermedius sea raft relay aquaculture could greatly improve the growth rate of sea urchins,shorten the breeding cycle,and was an efficient breeding model with good promotion value.Using the north-south relay aquaculture model;choosing large-size S.intermedius seedlings to breed could bring higher economic benefits.

Fish community structure and the growth performance of Hypophthalmichthys molitrix and Aristichthys nobilis in Jinhu Reservoir,Taining County,Fujian Province

HE Meifeng, XIAO Jiulan, LIANG Zhonglian, CUI Lifeng, CHEN Mengyun

2023, 45(5):  462-472.  DOI: 10.14012/j.cnki.fjsc.2023.05.006

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In order to provide basic data for biological control of water quality,to improve of fishery potential and economic benefits,we characterized the fish community and measured growth rates of H.molitrix and A.nobilis in Jinhu Reservoir.Making use of mixed gill nets,a systematic fishery investigation was conducted in Janurary,April,July,and October of 2022,respectively.A total of 32 fish species were collected,belonging to 26 genera,8 families and 3 orders.Cypriniformes was the largest order,which accounted for 75.0%.The ecological type analysis revealed that the community was dominated by carnivorous and omnivorous fish.Four dominant fish species were identified based on the index of relative importance,which were H.molitrix,A.nobilis,Xenocypris microlepis and Culter dabryi dabryi.The growth equation of body length and body mass for H.molitrix,they were L_t=74.52×[1-e^{-0.26(t+0.35)}];W_t=6 925.48×[1-e^{-0.26(t+0.35)}]^{2.906 9},respectively,and for A.nobilis were L_t= 68.35×[1-e^{-0.19(t+0.82)}];W_t = 5 669.32×[1-e^{-0.19(t+0.82)}]^{2.973 0},respectively.The highest body mass growth rate for H.molitrix occurred during the age of 1-4,and then decreased gradually,with the growth inflexion points at the age of 3.75.And infection point for A.nobilis was 4.91.As a result,the most appropriate catching age were 4-year-old for H.molitrix and 5-year-old for A.nobilis in order to get the best effect on algal bloom control and economic benefit.The results provided important scientific evidence for rational utilization of H.molitrix and A.nobilis resources and ecological environment restoration in Jinhu Reservoir of Taining,Fujian Province,China.

Assessment of the resources of Schizothorax grahami in the headwaters of Chishui River based on the marking and recapture

CHENG Yun, ZHAO Xiaosha, TANG Yongzhong, ZHANG Youzhao

2023, 45(5):  473-479.  DOI: 10.14012/j.cnki.fjsc.2023.05.007

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In order to understand the status of fishery resources after the implementation of conservation management and stocking of the Chishui River,and to provide a data base for future fish conservation and stocking work,this study was conducted in 2016 by using three methods of fluorescent tagging,dorsal fin T-tagging,and fin clipping tagging to mark and recapture S.grahami as an indicator species,and using breeding experiments to deduce the marker loss rate.Three samples were taken in May,June and July to assess the fish resources in the source section of the Chishui River.The results showed that the instantaneous resource numbers of S.grahami in the source section of the Chishui River during the assessment period were 1.99×10⁴,2.12×10⁴ and 1.68×10⁴ individuals,respectively;the instantaneous biomass was 467.6 kg,726.1 kg and 909.3 kg,respectively.Both the clipped fin marker group and the dorsal fin T marker group suffered from fall off and loss,with the loss rate of the dorsal fin T marker increasing exponentially with the increase of breeding time.The evaluation results showed that the continuous proliferation and release had a significant effect on the stability of fish resources in the headwaters of Chishui River and was conducive to the recovery of fish resources.

Probabilistic health risk assessment of cadmium intake in aquatic products along the southern coast of Fujian Province in China

LIU Haixin, YANG Miaofeng, ZHENG Shenghua, CHEN Yufeng, WANG Lijuan, TANG Shuifen, YU Ying, LUO Fangfang

2023, 45(5):  480-489.  DOI: 10.14012/j.cnki.fjsc.2023.05.008

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Cadmium pollution in aquatic products was common.In order to investigate the cadmium pollution in aquatic products and assess the health risk,cadmium concentration in aquatic products collected from southern coast of Fujian Province in China were detected form 2017 to 2022,combined with the survey results of dietary consumption of aquatic products to assess the health risk by Monte Carlo method.The results showed that a total of 1 004 aquatic products were detected,while the average concentration of cadmium in various aquatic products decreased in the following sequence:caphalopoda≈crabs>shellfish>algae>shrimp>fish.All kinds of aquatic products except crabs met the standards.About 25.6% crabs exceeded the standards,most of them were sea crabs.The contribution of shellfish,crabs and cephalopods to the cadmium intake of total aquatic products reached 85.8%-93.5%.P50,P90,P97.5 of MOE which reflect the overall resident’s cadmium health risk were far less than the safety limit of 1.According to the assessment by age group,the P97.5 risk value of the juvenile group was 0.687,which was closed to the safety limit.Shellfish and crabs made a great contribution to the variance of the risk value MOE,and their sensitivity reached 86.2%-99.1%.In general,the health risk of cadmium intake in dietary aquatic products of coastal residents in southern Fujian was acceptable,but dietary guidance should be provided for the juvenile group.People cadmium intake in aquatic products was mainly from shellfish,crabs and cephalopods.Eating shellfish and crabs with less cadmium concentration could effectively reduce the cadmium health risk from aquatic products.

Study on the residue and elimination of furacillin metabolites (semicarbazide) in the muscle of Takifugu flavidus

TANG Shuifen, QIAN Zhuozhen, LI Leibin, LIU Zhiyu, WANG Lijuan, WEI Shaohong, JIANG Linlin, YU Ying, CHEN Yufeng, LIU Haixin, CHEN Si, LUO Fangfang

2023, 45(5):  490-495.  DOI: 10.14012/j.cnki.fjsc.2023.05.009

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In order to investigate the retention and elimination of furacillin metabolites (semicarbazide,SEM) in the muscle of T.flavidus following the use of furacilin during the breeding process,the aquaculture pond was treated with 0.50 g/m³ of furacillin.Muscle samples of T.flavidus were then collected at regular intervals.The concentrations of SEM were determined using high-performance liquid chromatography-tandem mass spectrometry,and the data was analyzed by using Excel 2013.The results showed that furacillin was rapidly metabolized to SEM in T.flavidus after dosing.The levels of SEM in the muscles increased rapidly,reaching their highest value after approximately 4 days.The elimination rate of SEM was initially fast,but slowed down over time.Even after 77 days following dosing,the residual amount of SEM in the muscles was still around 2.50 μg/kg,which was above the limit of detection.This suggests that SEM has a prolonged residual time in T.flavidus after the administration of furacilin.Based on these findings,it is strongly recommended to strictly prohibit the use of nitrofurans,such as furacilin,during the breeding process of T.flavidus,in order to ensure the quality and safety of puffer fish.

Analysis and evaluation of nutritive composition of Epinephelus fuscoguttatus ♀×E.polyphekadion ♂

LIU Min, XIE Ruitao, WANG Zhuoduo, ZHANG Haitao, HE Shuqing, SUN Guangwen

2023, 45(5):  496-505.  DOI: 10.14012/j.cnki.fjsc.2023.05.010

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In this study,nutritional components in the body and muscle of a new hybrid grouper(E.fuscoguttatus ♀×E.polyphekadion ♂)were tested and analyzed with routine methods,in order to evaluate its nutritive value and offer basic date and theoretical basis for the research of its nutrition and the development of formula feed.The results showed that the ratio of flesh content was 74.31%,the contents of moisture,crude protein,crude fat,crude ash,Ca,and P of fresh body were 71.50%,20.45%,2.45%,2.88%,1.68% and 0.92%,respectively.The contents of moisture,crude protein,crude fat and crude ash of the hybrids’ fresh muscles were 74.60%,20.52%,2.48%and 1.23%,respectively.There were 18 kinds of amino acids in the muscle,including 8 essential amino acids (EAA) for human body and 4 delicious amino acids.The content of EAA was 6.89%,which accounted for 41.67% of the total amino acids.The content of tasty amino acids was 6.31%,which accounted for 38.60% of the total amino acids.The essential amino acid index (EAAI) was 78.21.The composition of EAA conforms to FAO/WHO standards.The proportion of saturated fatty acids (SFA) was 35.56%,and the proportion of polyunsaturated fatty acids (PUFA) was 36.46%.EPA and DHA accounted for 6.55% and 12.53% of the total fatty acids,respectively.10 kinds of mineral elements were detected in the muscle.The content of macro elements in muscle from high to low was K>P>Mg>Na>Ca.Among the trace elements,the content of Fe was the highest and the content of Se was the lowest.To sum up,the hybrid grouper(E.fuscoguttatus ♀×E.polyphekadion ♂)was a kind of high quality economic marine fish with good edible value and nutritive value,worthy of exploitation and utilization.

Analysis on the antibiotic resistance of pathogens separated from Pseudosciaena crocea in Ningbo City,Zhejiang Province from 2020 to 2022

GE Mingfeng, XU Shengwei, WANG Wenqiong, FU Zhiming, SHEN Weiliang

2023, 45(5):  506-512.  DOI: 10.14012/j.cnki.fjsc.2023.05.011

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In order to master the types and antibiotic resistance trend of the main pathogen of P.crocea in Ningbo City, Zhejiang Province in recent years, the infected fishes were collected from the main breeding sites of P.crocea in Ningbo from 2020 to 2022 for isolation and identification of pathogens.In the meantime, the minimum inhibitory concentration (MIC) of antibiotics (enrofloxacin, neomycin sulfate, thiamphenicol, florfenicol, doxycycline hydrochloride, fluoroquine, sulfamethoxazole sodium, sulfamethoxazole + trimethoprim) were determined to compare the susceptibility of each pathogen to the drug.The results showed that 7 species and 58 strains of pathogens were isolated from P.crocea in recent three years.The main pathogens were Pseudomonas plecoglossicida, Vibrio harveyi and Nocardia seriolea,accounting for 74.1% of the total bacterial strains. V.harveyi and N.seriolae were isolated every year. The isolated strains were 100% sensitive to doxycycline hydrochloride.The susceptibility of all strains to this drug was distributed at MIC ≤ 4.00 mg/L and the drug resistance rate was 0%.In comparison,the drug tolerance concentration of pathogens to florfenicol and sulfonamides was relatively high, especially the MIC of sulfonamides was generally between 64.00-1 024.00 mg/L. In addition,from the annual change in drug resistance of pathogen, it could be seen the drug resistance of N.seriolae was increasing year by year. Therefore,although the pathogens were generally sensitive to doxycycline hydrochloride,neomycin sulfate and enrofloxacin,which could be used as the preferred drug for controlling most pathogens in P.crocea,the dose and course must be determined strictly according to the results of drug sensitivity test and in combination with pharmacokinetics and pharmacodynamics, in order to avoid the emergence of drug-resistant strains as much as possible.

Review

A review on factors influencing the distribution and longline CPUE of Xiphias gladius

SONG Liming, ZHANG Lingxi, BAO Minhua, SUI Hengshou, LI Bin, ZHANG Min

2023, 45(5):  513-522.  DOI: 10.14012/j.cnki.fjsc.2023.05.012

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Understanding the distribution characteristics of X.gladius can provide scientific basis for studying the habitat ecology of X.gladius,resource conservation and improving longline fishing gear.This paper highlights the results of domestic and international research on factors influencing the distribution and longline catch per unit effort (CPUE) of X.gladius,as well as the problems and proposes countermeasures to be taken for further research in the future.The results show that:1) X.gladius perform diurnal vertical movements,with a U-shaped movement pattern according to the changes of dissolved oxygen content in water layer,and generally distribute in the corresponding depth of 8.5-13.3 °C during the day and 23.6-26.2 °C during the night;2) X.gladius migrate to tropical waters for spawning and overwintering,and migrate to temperate waters for feeding; 3) X.gladius congregate in frontal areas and eddy fields;4) moonlight illumination affects the vertical movements of X.gladius,and moon phase may also be related to X.gladius spawning behavior;5) the catch rate of X.gladius in monofilament longline fishing is higher than that in polyfilament longline fishing,and the soaking time is positively correlated with the CPUE of X.gladius; 6) fluorescent rods in fishing gear can improve X.gladius CPUE,and the soaking time of fluorescent rods is positively correlated with X.gladius CPUE.The main shortcomings of the previous studies include:1) insufficient research on the relationship between climatic changes and the habitat change of X.gladius;2) less quantitative research on the effect of lunar illumination on X.gladius activity and the results are not robust;3) insufficient research on the effects of different hook types,hook offset and baits on X.gladius CPUE.The following issues are suggested for future research:1) increasing the testing experiments of TDR and CTD to study the effects of temperature,salinity,chlorophyll a and dissolved oxygen concentrations in different water layers on X.gladius distribution;2) using historical catch statistics and satellite remote sensing data to study the relationship between X.gladius distribution and marine environment in combination with changes in ocean monsoon and trade winds to find out the specific effects of climate change on X.gladius distribution;3) using illuminance meters to measure the illuminance of moonlight and quantitatively study the effects of monthly illuminance of moonlight on the vertical movements of X.gladius and their bait organisms and the spawning behavior of X.gladius; 4) further studying the effects of different hook types,hook offset and different baits on X.gladius CPUE.