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Experimental and Numerical Investigations of the Hydrodynamic Characteristics, Twine Deformation, and Flow Field Around the Netting Structure Composed of Two Types of Twine Materials for Midwater Trawls
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作者 THIERRY Bruno Nyatchouba Nsangue TANG Hao +3 位作者 ACHILE Njomoue Pandong XU Liuxiong ZHOU Cheng HU Fuxiang 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第5期1215-1235,共21页
Nettings are complex flexible structures used in various fisheries.Understanding the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing gear.This stu... Nettings are complex flexible structures used in various fisheries.Understanding the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing gear.This study investigated the hydrodynamic characteristics and deformation of five nettings made of polyethylene and nylon materials in different attack angles through numeri-cal simulation and physical model experiment.The numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural models.Navier-Stokes equations were solved using the finite volume ap-proach,the flow was described using the k-ωshear stress turbulent model,and the large deflection structural dynamic equation was derived using a finite element approach to understand the netting deformation and nodal displacement.The porous media model was chosen to model the nettings in the CFD solver.Numerical data were compared with the experimental results of the physical model to validate the numerical models.Results showed that the numerical data were compatible with the experimental data with an average relative error of 2.34%,3.40%,6.50%,and 5.80%in the normal drag coefficients,parallel drag coefficients,inclined drag coefficients,and inclined lift coefficients,respectively.The hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net solidity.The drag and lift coefficients of the nylon netting were appro-ximately 17.15%and 6.72%lower than those of the polyethylene netting.A spatial development of turbulent flow occurred around the netting because of the netting wake.However,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net solidity.In addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio. 展开更多
关键词 NETTING k-ωshear stress turbulent(SST)model porous media model large deflection nonlinear structural model hydrodynamic characteristics
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Standardization of CPUE for Chilean Jack Mackerel (Trachurus murphyi) from Chinese Trawl Fleets in the High Seas of the Southeast Pacific Ocean 被引量:9
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作者 LI Gang ZOU Xiaorong +2 位作者 CHEN Xinjun ZHOU Yinqi ZHANG Min 《Journal of Ocean University of China》 SCIE CAS 2013年第3期441-451,共11页
The generalized linear model (GLM) and generalized additive model (GAM) were applied to the standardization of catch per unit effort (CPUE) for Chilean jack mackerel from Chinese factory trawl fishing fleets in ... The generalized linear model (GLM) and generalized additive model (GAM) were applied to the standardization of catch per unit effort (CPUE) for Chilean jack mackerel from Chinese factory trawl fishing fleets in the Southeast Pacific Ocean from 2001 to 2010 by removing the operational, environmental, spatial and temporal impacts. A total of 9 factors were selected to build the GLM and GAM, i.e., Year, Month, Vessel, La Nifia and E1 Nifio events (ELE), Latitude, Longitude, Sea surface temperature (SST), SST anomaly (SSTA), Nino3.4 index and an interaction term between Longitude and Latitude. The first 5 factors were significant components in the GLM, which in combination explained 27.34% of the total variance in nominal CPUE. In the stepwise GAM, all factors explained 30.78% of the total variance, with Month, Year and Vessel as the main factors influencing CPUE. The higher CPUE occurred during the period April to July at a SST range of 12-15℃ and a SSTA range of 0.2-1.0℃. The CPUE was significantly higher in normal years compared with that in La Nifia and E1 Nifio years. The abundance of Chilean jack mackerel declined during 2001 and 2010, with an increase in 2007. This work provided the relative abundance index of Chilean jack mackerel for stock as- sessment by standardizing catch and effort data of Chinese trawl fisheries and examined the influence of temporal, spatial, environ- mental and fisheries operational factors on Chilean jack mackerel CPUE. 展开更多
关键词 Chilean jack mackerel STANDARDIZATION CPUE GLM GAM
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High Individual Variability in Beak Stable Isotopes of Jumbo Squid off Peruvian Exclusive Economic Zone(EEZ) Waters in the Analysis of Migratory and Foraging Ecology 被引量:5
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作者 LIU Bilin JIN Yue +4 位作者 CHEN Xinjun LI Jianhua QIAN Weiguo LIU Na HUAN Mengyao 《Journal of Ocean University of China》 SCIE CAS CSCD 2019年第1期232-238,共7页
Stable isotopes(δ^(13)C and δ^(15)N) have been widely used to track cephalopod habitat, migration and trophic structure. In this study, we analyzed the δ^(13)C and δ^(15)N values in 245 Dosidicus gigas beaks colle... Stable isotopes(δ^(13)C and δ^(15)N) have been widely used to track cephalopod habitat, migration and trophic structure. In this study, we analyzed the δ^(13)C and δ^(15)N values in 245 Dosidicus gigas beaks collected during 2009–2010 and in 2013 off Peruvian Exclusive Economic Zone(EEZ) waters. High individual variation in beak stable isotopes was shown with values ranging from-19.4‰ to-15.8‰ for δ^(13)C and from 5.0‰ to 15.1‰ for δ^(15)N. A generalized additive model(GAM) showed that latitude, mantle length and distance to shelf break significantly described the isotope variation with deviance ranging from 16.6% in δ^(13)C to 36.3% in δ^(15)N. Large variability in beak δ^(13)C values for a given size and sampling station indicated that D. gigas off the Peruvian EEZ waters migrate in different ways when they occupy a large range of habitats for their ontogeny. Low baseline δ^(15)N values suggested that spatial changes in diet trophic level may be the main determinative factor in beak δ^(15)N variation. We conclude that high variability in beak δ^(15)N values for a given set of explanatory variables indicated that D. gigas is an opportunistic predator with highly diverse dietary habitats. This study further develops our knowledge of the life history of D. gigas in such a highly dynamic region. 展开更多
关键词 isotopes variability TROPHIC level BEAK Dosidicus GIGAS Peru GAM
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Effects of Climate Variability on Habitat Range and Distribution of Chub Mackerel in the East China Sea 被引量:3
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作者 YU Wei WEN Jian +3 位作者 CHEN Xinjun LI Gang LI Yuesong ZHANG Zhong 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第6期1483-1494,共12页
Spatio-temporal distribution of chub mackerel Scomber japonicus is strongly susceptible to climate variability.In this study,a weighting-based habitat suitability index(HSI)model was established to assess the impacts ... Spatio-temporal distribution of chub mackerel Scomber japonicus is strongly susceptible to climate variability.In this study,a weighting-based habitat suitability index(HSI)model was established to assess the impacts of Pacific Decadal Oscillation(PDO)on habitat range and distribution of S.japonicus in the East China Sea(ECS)using vertical water temperature at depths of 2.5 m,25 m and 50 m.Results showed that the optimal HSI model selected from ten weighting scenarios can yield reliable predictions.Correlation analysis revealed a significant negative relationship between the PDO index and water temperature anomaly at different depths.The water temperatures at three different layers on the fishing ground of S.japonicus tended to be low in the warm PDO phase and high in the cold PDO phase,respectively.The range of suitable habitats and its spatial distribution exhibited large differences between the warm and cold PDO regimes.During a warm PDO phase,vertical water temperature became cool,and the monthly preferred water temperature at each depth for S.japonicus shifted southeastward.Consequently,habitat quality dramatically decreased,and suitable habitat ranges also reduced and moved southeastward.Conversely,in a cool PDO phase,with the warmer vertical water temperature and northwestward shift of the preferred water temperature,the suitable habitats enlarged and migrated in the same direction.Our findings indicate that the PDO produced significant impacts on habitat range and distribution of S.japonicus in the East China Sea. 展开更多
关键词 Scomber japonicus habitat pattern vertical water temperature Pacific Decadal Oscillation the East China Sea
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Relationships between daily growth of different groups of swordtip squid(Uroteuthis edulis)and environmental variables in the East China Sea 被引量:1
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作者 Nan Li Yan Wang +2 位作者 Zhou Fang Xinjun Chen Zhiping Feng 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2022年第8期52-61,共10页
Swordtip squid(Uroteuthis edulis)is one of the important economical fishing target species in the East China Sea.Uroteuthis edulis is characterized by rapid growth,extensive migration,and long spawning period and sens... Swordtip squid(Uroteuthis edulis)is one of the important economical fishing target species in the East China Sea.Uroteuthis edulis is characterized by rapid growth,extensive migration,and long spawning period and sensitive to surrounding environment.In order to assess its stock status,it is necessary to explore its spawning season,growth patterns of different populations and their relationship with the environment in advance.In this paper,based on the samples of U.edulis collected in the East China Sea from September 2017 to March 2018,we explored the relationships between daily growth of statolith microstructure and environmental variables by gradient forest method and generalized additive model.The spawning season of U.edulis was found to be nearly one year,and two dominant season groups were found:the spring group with the peak period of April and the summer group with the peak period of August.Water temperature in the depth of 25 m(Temp_25),sea surface temperature(SST)and zonal velocity were the key environmental variables for the daily growth of April-spawning group.The most suitable environmental conditions for the growth of April-spawning group were water temperature(24-27℃)and velocity(0.1-0.3 m/s).SST,Temp_25 and mixed layer depth were the key environment variables for the daily growth of August-spawning group.The most suitable environmental conditions for the growth of Augustspawning group were water temperature(21-28℃)and water depth(0-50 m).Key environmental variables of different groups suggested that early growth was significantly affected by seasonal changes of water temperature,current velocity and prey abundance.This study explored the relationships between early growth and environmental variables and provided the scientific guidance for the management and conservation of U.edulis. 展开更多
关键词 East China Sea Uroteuthis edulis statolith microstructure environmental variables
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Growth marks in eyestalks of Portunus trituberculatus:A development of technique and evidence of molting
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作者 Bilin Liu Jian Zhang +2 位作者 Jiang Rui Zhenyu Ni Chang Shu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第4期84-91,共8页
The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting.In this study,we developed an effective method to process and observe the eyestalk microstructure of... The analysis of growth bands in the eyestalk has been increasingly used for estimating crustacean ageing and molting.In this study,we developed an effective method to process and observe the eyestalk microstructure of the swimming crab(Portunus trituberculatus).We found that dark pigmentation as a result of boiling has an influence on the observation of the eyestalk microstructure.Choosing an unboiled eyestalk,this study compared the cross section and longitudinal section,and concluded that the cross section is suitable for the observation of growth increments with 6.1%CV(coefficient of variation),and growth bands are suitable for the observation of the longitudinal section with 5.4%CV.The width of growth increments near the edge of the endocuticle is small,and the width of growth increments of the middle part of the endocuticle is large.Relationship of number of growth bands to molting time was fitted to a linear function with the slope not significantly different from 1,indicating that growth bands are formed associated with molting.Periodicity of growth increment formation was calculated as 3.7 d,however was not verified.Our results provide a new improved technique for identification of crustacean molting and growth. 展开更多
关键词 growth bands growth increments Portunus trituberculatus EYESTALK MOLTING
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Synchronous Variations in Abundance and Distribution of Ommastrephes bartramii and Dosidicus gigas in the Pacific Ocean
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作者 YU Wei CHEN Xinjun LIU Lianwei 《Journal of Ocean University of China》 SCIE CAS CSCD 2021年第3期695-705,共11页
An analysis was performed in this study to investigate synchronous fluctuations in abundance and distribution of Om-mastrephes bartramii in the Northwest Pacific Ocean and Dosidicus gigas in the Southeast Pacific Ocea... An analysis was performed in this study to investigate synchronous fluctuations in abundance and distribution of Om-mastrephes bartramii in the Northwest Pacific Ocean and Dosidicus gigas in the Southeast Pacific Ocean.The impacts of two Niño indices and regional water surface temperature on the two squids during 2006-2015 were evaluated,which possibly can explain the observed synchronicity.Catch per unit effort(CPUE)and the latitudinal gravity centers(LATG)of fishing effort were used to indi-cate squid abundance and distribution,respectively.The results indicated that both the CPUE and LATG showed highly interannual variations and synchronous fluctuation with significant negative associations between the two squid species from September to No-vember.Strong positive cross-correlations with 2-month lag was found between sea surface temperature(SST)anomaly in the Niño 3.4 and Niño 1+2 regions,which have significant linkage with the SST on the fishing ground of O.bartramii and D.gigas,respec-tively.Moreover,the proportion of favorable-SST area(PFSST)and the latitudinal location of the optimal SST for O.bartramii and D.gigas were positively correlated with the CPUE and LATG,respectively.Increased O.bartramii PFSST clearly corresponded to decreased D.gigas PFSST in phase as well as the latitudinal location of the optimal SST from September to November over 2006-2015.Our findings suggest that synchronous changes in abundance and distribution of the two squids were due to simultaneous variations in the PFSST and the latitudinal location of the optimal SST front which were affected by the SSTA changes in the Niño 3.4 and Niño 1+2 regions. 展开更多
关键词 Ommastrephes bartramii Dosidicus gigas distribution and abundance synchronous variability environmental effects
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Revealing the Fluttering Motions of Mid-Water Trawl Codend Through Sea Trials:Case Study of Antarctic Krill Trawl Codend
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作者 LIU Wei TANG Hao +5 位作者 NYATCHOUBA NSANGUE Bruno Thierry ZHANG Feng YIN Liqiang XU Liuxiong HU Fuxiang LIU Pengfei 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第2期555-564,共10页
The dynamic coupling between the fluttering motions and hydrodynamic characteristics of codend is essential in understanding the trawl selectivity through fish response and the drag force acting on the whole trawl.Thi... The dynamic coupling between the fluttering motions and hydrodynamic characteristics of codend is essential in understanding the trawl selectivity through fish response and the drag force acting on the whole trawl.This study investigated the effect of towing speed,warp length,warp tension,and catch size on the fluttering motions of Antarctic krill trawl codend during net shooting,towing,and hauling by using sea trial data.The time-periodicity of codend oscillation was analyzed by the Morlet wavelet transform method.Results indicated that the period of codend oscillation was between 50 s and 90 s and showed an increasing trend with the warp tension but a decreased value at the towing stage.The coefficient amplitude of codend oscillation was between 0 and 4 at the net shooting and hauling stages,and between 0.2 and 0.6 at the towing stage.The amplitude of codend oscillation increased with the warp tension,towing speed,and catch size,but decreased with the increase of the warp length.In addition,the period of codend oscillation increased with the towing speed at the net shooting and hauling stages,but decreased at the towing stage.These results from codend fluttering motions can improve the understanding of fish behavior and gear shape that modify the hydrodynamic force on the codend instantaneously. 展开更多
关键词 codend fluttering motions sea trials Morlet wavelet PERIODICITY
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Assessment of prediction model of the CPUE of neon flying squid with different sources of remote sensing data
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作者 Liang Chang Yanli Yang +4 位作者 Xinjun Chen Wei Yu Yangdong Li Guiping Feng Yang Zhang 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2023年第6期33-38,共6页
Accurately building the relationship between the oceanographic environment and the distribution of neon flying squid(Ommastrephes bartramii)is very important to understand the potential habitat pattern of O.bartramii.... Accurately building the relationship between the oceanographic environment and the distribution of neon flying squid(Ommastrephes bartramii)is very important to understand the potential habitat pattern of O.bartramii.However,when building the prediction model of O.bartramii with traditional oceanographic variables(e.g.,chlorophyll a concentration(Chl a)and sea surface temperature(SST))from space-borne observations,part of the important spectrum characteristics of the oceanic surface could be masked by using the satellite data products directly.In this study,the neglected remote sensing information(i.e.,spectral remote sensing reflectance(Rrs)and brightness temperature(BT))is firstly incorporated to build the prediction model of catch per unit effort(CPUE)of O.bartramii from July to December during 2014–2018 in the Northwest Pacific Ocean.Results show that both the conventional oceanographic variables and the neglected remote sensing data are suitable for building the prediction model,whereas the overall root mean square error(RMSE)of the predicted CPUE of O.bartramii with the former is typically less accurate than that with the latter.Hence,the Rrs and BT could be a more suitable data source than the Chl a and SST to predict the distribution of O.bartramii,highlighting that the potential value of the neglected variables in understanding the habitat suitability of O.bartramii. 展开更多
关键词 Ommastrephes bartramii CPUE prediction remote sensing Rrs BT.
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Identification of Fishing State of Purse Seine Fishing Vessels Based on Multi-Indices
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作者 XU Zhenqi WANG Jintao +3 位作者 ZHOU Cheng LEI Lin CHEN Xinjun LI Bin 《Journal of Ocean University of China》 SCIE CAS CSCD 2023年第6期1605-1612,共8页
With the popularization of vessel satellite AIS(automatic identification system)equipment and the continuous improve-ment of the AIS data’s coverage,continuity and effectiveness,AIS has become an important data sourc... With the popularization of vessel satellite AIS(automatic identification system)equipment and the continuous improve-ment of the AIS data’s coverage,continuity and effectiveness,AIS has become an important data source to study the navigation char-acteristics of vessel groups.This study established an identification model to extract the fishing state and intensity information of fishing vessels,based on the AIS data of purse seine fishing vessels,combined with the variables of vessel position,speed and course.Expert experience,spatial statistics and data mining analysis methods were applied to establish the model,and the Western and Cen-tral Pacific Ocean areas were studied.The results showed that the overall accuracy of identification of the fishing state using Support Vector Machine method is higher,and the method has a good modeling effect.The spatial distribution characteristics of the vessels’fishing intensity based on AIS data showed a significant cluster distribution pattern.The obtained high-intensity fishing area can be used as a prediction of purse seine fishing grounds in the Western and Central Pacific areas.Through the processing and research of AIS data,this study provided important scientific support for the identification of fishing state of purse seine fishing vessels.The spatial fishing intensity of fishing vessels based on AIS data can also be used for the analysis of fishery resources and fishing grounds,and further serve the sustainable development of marine fisheries. 展开更多
关键词 automatic identification system(AIS) fishing state machine learning fishing intensity
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δ13C and δ15N in Humboldt squid beaks: understanding potential geographic population connectivity and movement 被引量:1
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作者 Bilin Liu Xinjun Chen +2 位作者 Weiguo Qian Yue Jin Jianhua Li 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2019年第10期53-59,共7页
We quantified theδ^13C andδ^15N values in the lower beaks of Humboldt squid,Dosidicus gigas,collected from international waters off Costa Rica,Ecuador,Peru and Chile by Chinese squid jigging vessels during 2009,2010... We quantified theδ^13C andδ^15N values in the lower beaks of Humboldt squid,Dosidicus gigas,collected from international waters off Costa Rica,Ecuador,Peru and Chile by Chinese squid jigging vessels during 2009,2010 and 2013.There was a significant difference in the isotopic values among regions with the lowest value off Ecuador and the highest off Chile,which were interpreted as a function of trophic effects as well as baseline values.However,constant trophic level of D.gigas across its geographic range showed that spatial variation in the baseline of primary production is the main driver responsible for the observed geographic isotope variability.Inter-regional difference and intra-regional convergence of isotope values indicated squid off Costa Rica,Ecuador and Chile belong to different geographically segregated populations,which were previously proved by integrated population identifying method.In contrast,the higher variations inδ^13C andδ^15N values in a given size group suggest the squid off Peru move and forage in different places.Moreover,potential population exchange could be responsible for the overlap of the isotope values between the squid off Peru and off Chile.On the whole,the spatial difference in isotopic values of Humboldt squid beaks improves our understanding of potential geographic population connectivity and movement. 展开更多
关键词 stable isotope Dosidicus GIGAS beaks GEOGRAPHIC variability TROPHIC level the eastern PACIFIC Ocean
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Comparing different spatial interpolation methods to predict the distribution of fishes:A case study of Coilia nasus in the Changjiang River Estuary 被引量:1
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作者 Shaoyuan Pan Siquan Tian +3 位作者 Xuefang Wang Libin Dai Chunxia Gao Jianfeng Tong 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2021年第8期119-132,共14页
Spatial-temporal distribution of marine fishes is strongly influenced by environmental factors.To obtain a more continuous distribution of these variables usually measured by stationary sampling designs,spatial interp... Spatial-temporal distribution of marine fishes is strongly influenced by environmental factors.To obtain a more continuous distribution of these variables usually measured by stationary sampling designs,spatial interpolation methods(SIMs)is usually used.However,different SIMs may obtain varied estimation values with significant differences,thus affecting the prediction of fish spatial distribution.In this study,different SIMs were used to obtain continuous environmental variables(water depth,water temperature,salinity,dissolved oxygen(DO),p H,chlorophyll a and chemical oxygen demand(COD))in the Changjiang River Estuary(CRE),including inverse distance weighted(IDW)interpolation,ordinary Kriging(OK)(semivariogram model:exponential(OKE),Gaussian(OKG)and spherical(OKS))and radial basis function(RBF)(regularized spline function(RS)and tension spline function(TS)).The accuracy and effect of SIMs were cross-validated,and two-stage generalized additive model(GAM)was used to predict the distribution of Coilia nasus from 2012 to 2014 in CRE.DO and COD were removed before model prediction due to their autocorrelation coefficient based on variance inflation factors analysis.Results showed that the estimated values of environmental variables obtained by the different SIMs differed(i.e.,mean values,range etc.).Cross-validation revealed that the most suitable SIMs of water depth and chlorophyll a was IDW,water temperature and salinity was RS,and p H was OKG.Further,different interpolation results affected the predicted spatial distribution of Coilia nasus in the CRE.The mean values of the predicted abundance were similar,but the differences between and among the maximum value were large.Studies showed that different SIMs can affect estimated values of the environmental variables in the CRE(especially salinity).These variations further suggest that the most applicable SIMs to each variable will also differ.Thus,it is necessary to take these potential impacts into consideration when studying the relationship between the spatial distribution of fishes and environmental changes in the CRE. 展开更多
关键词 the Changjiang River Estuary marine environmental factors spatial interpolation method Coilia nasus spatial distribution
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Comparative age and growth of Uroteuthis chinensis and Uroteuthis edulis from China Seas based on statolith 被引量:4
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作者 Yue Jin Na Li +2 位作者 Xinjun Chen Bilin Liu Jianhua Li 《Aquaculture and Fisheries》 2019年第4期166-172,共7页
To determine the age and growth of Uroteuthis chinensis and U.edulis,growth increments of the lateral dome of the statolith were used in the present study.Specimens of the two species caught in the South China Sea(SCS... To determine the age and growth of Uroteuthis chinensis and U.edulis,growth increments of the lateral dome of the statolith were used in the present study.Specimens of the two species caught in the South China Sea(SCS)and East China Sea(ECS)were used to compare the age and growth differences between sexes.In the present study,we found the two species have similar lifespans of less than 200 days.We also found that there were significant differences in the relationships between mantle length and body weight for two species and for both sexes in the same species.The back-calculated hatching date for the two species was similar,i.e.October to January for specimens caught in spring,and March to June for specimens caught in summer(U.edulis)or autumn(U.chinensis).Exponential and logistic growth curves were fitted to build the age and mantle length relationship.Both growth curves showed that U.chinensis has a larger mantle length than U.edulis at the same age.The results of the growth rates also showed that U.chinensis grows faster than U.edulis.However,there are discrepancies between previous studies and the present study on the lifespan of the two species.Also,the sample size of the present study is small especially for U.edulis.Hence,future studies should be conducted to validate the daily periodicity of growth increment in the regions of statolith(except for the lateral dome which has been validated)and the sample size should be increased for age and growth studies. 展开更多
关键词 Uroteuthis chinensis Uroteuthis edulis Age Hatching date GROWTH
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Identifying the turbulent flow developing inside and around the bottom trawl by Electromagnetic Current Velocity Meter approach in the flume tank 被引量:2
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作者 Nyatchouba Nsangue Bruno Thierry Hao Tang +4 位作者 Liu-xiong Xu Fuxiang Hu Xinxing You Micah Adekunle David Njomoue Pandong Achille 《Journal of Hydrodynamics》 SCIE EI CSCD 2021年第3期636-656,共21页
The Knowledge of turbulent flow developing inside and around the bottom trawl net is of great importance not only for improving the hydrodynamic performance of the gear but also for the selectivity via the fish respon... The Knowledge of turbulent flow developing inside and around the bottom trawl net is of great importance not only for improving the hydrodynamic performance of the gear but also for the selectivity via the fish response,such as the herding response or escape behavior.The 3-D Electromagnetic Current Velocity Meter(ECVM)measurements were performed to investigate the effect of turbulent flow on the bottom trawl net performance and to analyze the turbulence intensity and velocity ratio inside and around different parts of the trawl net.Proper orthogonal decomposition(POD)method was applied in order to extract the phase averaged mean velocity field of turbulent flow from each available ECVM instantaneous velocity.The results demonstrated the existence of turbulence flow,consisting of turbulent boundary layer flow and the turbulence due to the trawl wake developing all inside and around the bottom trawl net.Increasing input streamwise velocity results in faster trawl movement and a significant turbulent flow.The maximum turbulence intensity inside and around trawl wing,square part,first belly,second belly,third belly,cod-end is 0.95%,1.34%,3.40%,4.10%,4.25%and 3.80%,respectively.It was found that the mean velocity field in a turbulent flow inside and around trawl net cod-end recovered on the average was~77.58%of the input streamwise velocity.It is~12.92%,~13.07%,~11.40%,~13.00%and~0.45%less than that inside and around trawl wing,square part,first belly,second belly,and third belly of the bottom trawl net,respectively.The turbulent flow behavior depends strongly on the structure oscillation,input streamwise velocity and,porosity of the net structure.It is necessary to take into account the velocity reduction inside and around a different part of the trawl net to improve the entire drag force determination,cod-end design,and further selectivity control of the fishing gear. 展开更多
关键词 HYDRODYNAMIC bottom trawl net turbulent flow Electromagnetic Current Velocity Meter(ECVM) turbulence intensity proper orthogonal decomposition(POD)
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The deformation characteristics and flow field around knotless polyethylene netting based on fluid structure interaction(FSI)one-way coupling 被引量:2
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作者 Baiqiang Zou Nyatchouba Nsangue Bruno Thierry +3 位作者 Hao Tang Liuxiong Xu Shuchuang Dong Fuxiang Hu 《Aquaculture and Fisheries》 2022年第1期89-102,共14页
Knotless polyethylene(PE)netting is widely used in fisheries because of its excellent hydrodynamic performance and low cost.Netting deformation and the surrounding flow field distribution play an important role in det... Knotless polyethylene(PE)netting is widely used in fisheries because of its excellent hydrodynamic performance and low cost.Netting deformation and the surrounding flow field distribution play an important role in determining the hydrodynamic characteristics of netting in moving water.In order to investigate the effect of solidity ratio and attack angle on drag,netting deformation,and flow field distribution through the netting,a fluid-structure interaction(FSI)model based on a one-way coupling combining the shear stress turbulent(SST)k-omega model and the large deformation nonlinear structural finite element model was evaluated.Our results showed the difference between the parallel and normal drag forces found in the present numerical model and experimental flume tank data were 9.17%and 11.58%,respectively.The mean relative error in the inclined hydrodynamic drag for different flow velocities and attack angles was 8.35%,6.69%,and 5.37%for the nettings 1,2,and 3,respectively.These results show that the present numerical simulation based on FSI one-way coupling can be used to examine hydrodynamic forces on netting.The flow simulation results show that there is a noticeable flow velocity decrease through the netting and a rather large velocity reduction region downstream from the netting for different attack angles.These results reveal the existence of turbulent flow due to the netting wake.It was found that the equivalent stress and total deformation increase as the flow velocity increases and solidity ratio decreases. 展开更多
关键词 Knotless netting Fluid structure interaction Deformation characteristics Flow field SST k-omega model
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Habitat suitability response to sea-level height changes: Implications for Ommastrephid squid conservation and management 被引量:2
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作者 Wei Yu Xinjun Chen 《Aquaculture and Fisheries》 2021年第3期309-320,共12页
Sea level rise,amplified by anthropogenic climate change,causes visible impacts on wildlife habitats in low-lying coastal areas.However,the potential consequences of sea level height(SLH)changes for pelagic fish habit... Sea level rise,amplified by anthropogenic climate change,causes visible impacts on wildlife habitats in low-lying coastal areas.However,the potential consequences of sea level height(SLH)changes for pelagic fish habitats in the open oceans are poorly understood,especially for climate-sensitive Ommastrephid squid.In this study,the impacts of SLH changes were estimated under three different SLH change scenarios(5 cm,20 cm,and 35 cm)for the western stock of winter-spring neon flying squid Ommastrephes bartramii,an ecologically-and commercially-important species in the northwest Pacific Ocean(NWPO).A habitat suitability index(HSI)modeling approach was applied to predict the habitat suitability of O.bartramii,using data from 2006 to 2014 for model construction and data from 2015 for model validation.Results showed that the decreasing catch-per-unit-effort(CPUE)of O.bartramii from 2006 to 2015 was highly correlated with the increases in sea level height(SLH).Significant positive relationships were found between the HSI values for latitudinal centers of gravity(LATGHSI)and SLH.The monthly-averaged HSI of O.bartramii was negatively correlated with the SLH,except in July and November.SLH scenarios revealed that the predicted suitable habitat(areas with HSI≥0.6)exhibited a decreasing trend with increasing SLH from August to October.In July and November,the suitable habitat initially increased in the+5 cm and+20 cm scenarios,but largely declined under the+35 cm scenario.The poor habitat(areas with HSI≤0.2)significantly increased under all SLH scenarios.A poleward shift of LATGHSI was observed under all scenarios.These findings suggest that the O.bartramii habitats in the NWPO are at risk to SLH changes and have important implications for better conservation and fishery management regarding pelagic short-lived Ommastrephid squid in global oceans. 展开更多
关键词 Sea level height change Conservation and management Habitat variability Ommastrephes bartramii Ommastrephid squid
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Inter-individual variation in trophic history of Dosidicus gigas,as indicated by stable isotopes in eye lenses 被引量:2
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作者 Wei Xu Xinjun Chen +4 位作者 Bilin Liu Yong Chen Mengyao Huan Na Liu Jingyuan Lina 《Aquaculture and Fisheries》 2019年第6期261-267,共7页
Isotopic signatures have been extensively used to reconstruct marine organism trophic habitat over their lifetime.In this study,sequential stable isotopic values ofδ13C andδ15N in eye lenses were measured to invest... Isotopic signatures have been extensively used to reconstruct marine organism trophic habitat over their lifetime.In this study,sequential stable isotopic values ofδ13C andδ15N in eye lenses were measured to investigate the trophic history of Dosidicus gigas during ontogeny.A total of 281 segments from 33 lenses were examined withδ13C ranging from−20.17‰to−16.11‰andδ15N ranging from 5.15‰to 18.74‰.Sequential increasing but variableδ13C andδ15N values in eye lenses indicated that the prey used in the model had a wide range of values,it became able to consume prey from higher trophic levels,perhaps to maximize feeding success.High inter-individual differences in the range and considerable inter-individual variation in the trend of the isotopic values of the sequential segments from the nuclear to the periphery were considered to be the result of the effects of food and the best feeding strategy.These inter-individual isotopic differences in the life history of D.gigas confirmed the high degree of plasticity of feeding for this squid and its high potential to adapt to environmental change.Inter-individual differences ofδ15N values in the growth of D.gigas were more likely to be caused by differences in the baseline values of isotopes.According to the population discrimination model ofδ15N value changes during ontogeny,the D.gigas off Peru fit the model of“generalist population-generalist individuals”. 展开更多
关键词 Dosidicus gigas Stable isotope Eye lenses Trophic habitat
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Estimating blue marlin(Makaira nigricans)sustainable yield in the Indian Ocean using a data-poor approach 被引量:1
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作者 Yuwei Fan Zhe Geng +2 位作者 Jiangfeng Zhu Xiaojie Dai Kindong Richard 《Aquaculture and Fisheries》 2019年第3期122-127,共6页
Blue marlin(Makaira nigricans)is a common bycatch species in the global tuna longline fishery.In this study,we applied a common data-poor approach,i.e.,depletion-corrected average catch(DCAC)to assess stock status of ... Blue marlin(Makaira nigricans)is a common bycatch species in the global tuna longline fishery.In this study,we applied a common data-poor approach,i.e.,depletion-corrected average catch(DCAC)to assess stock status of the Indian Ocean blue marlin.Sustainable yield(Ysust),one reference point in this case,was estimated,and its uncertainty was integrated by using Monte Carlo simulation.The results revealed the estimate of Ysust by DCAC was lower than MSY of 11,926 t by BSP-SS and is also lower than the provisional reference point of 11,704 t by the management proposal.DCAC is reliable for blue marlin in driving precautionary management quantity based on the CPUE of Japan(1980–2015).This study also implies that DCAC could be applied to other billfish stocks and uncertainty be estimated for sustainable yield.However,data-poor methods could be adjusted with precautionary approaches. 展开更多
关键词 Blue marlin Data-poor approach Stock assessment Indian Ocean
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A Prototypic Jun Like Gene in Amphioxus Branchiostoma japonicum Expressed in Female Gonad
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作者 Qianghua Xu Jun Tan Liangbiao Chen 《Journal of Genetics and Genomics》 SCIE CAS CSCD 2012年第11期607-611,共5页
Transcription factors are a group of regulatory proteins that bJind to specific DNA sequence in the promoter region of the target genes to regulate gene expression at transcriptional level (Baeuerle, 1991; Jackson, 1... Transcription factors are a group of regulatory proteins that bJind to specific DNA sequence in the promoter region of the target genes to regulate gene expression at transcriptional level (Baeuerle, 1991; Jackson, 1992). Transcription factor activator protein-1 (AP-1) is one of the transcription factors initially identified from mammals. The mammalian AP-1 complex contains multiple members of Jun, Fos, ATF which form homo- or heterodimers to perform the regulatory function (Halazonetis et al., 1988; Angel and Karin, 1991; Karin et al., 1997; Jochum et al.. 2001: Veselv et al.. 2009: Shaulian. 2010). 展开更多
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