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Application of Numerical Simulation for Analysis of Sinking Characteristics of Purse Seine

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Journal of Ocean University of China 2015年第1期14卷 135-142页

作者： ZHOU Cheng xu liuxiong ZHANG Xinfeng YE xuchang College of Marine Sciences Shanghai Ocean University Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Ministry of Education Shanghai Ocean University National Engineering Research Center for Oceanic Fisheries Shanghai Collaborative Innovation Center for Oceanic Fisheries

This study applies the mass-spring system to model the dynamic behavior of a submerged net panel similar to the shooting process in actual purse seine fishing operation. Modeling indicates that there is insufficient stretching with the net panel under the floatline in the prophase of the shooting process. Sinkers at different locations along the leadline descend successively after submergence, and the sinking speed decreases gradually with elapsed time until attainment of a stable state. Designs with different current speeds and sinker weights are executed to determine the dimensional shape and sinking characteristics of the net. The net rigged with greater sinker weight gains significantly greater sinking depth without water flow. Compared with the vertical spread of the net wall in static water, the middle part of the netting presents a larger displacement along the direction of current under flow condition. It follows that considerable deformation of the netting occurs with higher current speed as the sinkers affected by hydrodynamic force drift in the direction of current. The numerical model is verified by a comparison between simulated results and sea measurements. The calculated values generally coincide with the observed ones, with the former being slightly higher than the latter. This study provides an implicit algorithm which saves computational loads for enormous systems such as purse seines, and ensures the accuracy and stability of numerical solutions in a repetitious iteration process.

关键词： numerical simulation mass-point model purse seine sinking characteristics

Application of a Bayesian method to data-poor stock assessment by using Indian Ocean albacore (Thunnus alalunga) stock assessment as an example

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Acta Oceanologica Sinica 2016年第2期35卷 117-125页

作者： GUAN Wenjiang TANG Lin ZHU Jiangfeng TIAN Siquan xu liuxiong College of Marine Sciences Shanghai Ocean University Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources (Shanghai Ocean University) Ministry of Education

It is widely recognized that assessments of the status of data-poor fish stocks are challenging and that Bayesian analysis is one of the methods which can be used to improve the reliability of stock assessments in data-poor situations through borrowing strength from prior information deduced from species with good-quality data or other known information. Because there is considerable uncertainty remaining in the stock assessment of albacore tuna（Thunnus alalunga） in the Indian Ocean due to the limited and low-quality data, we investigate the advantages of a Bayesian method in data-poor stock assessment by using Indian Ocean albacore stock assessment as an example. Eight Bayesian biomass dynamics models with different prior assumptions and catch data series were developed to assess the stock. The results show（1） the rationality of choice of catch data series and assumption of parameters could be enhanced by analyzing the posterior distribution of the parameters;（2） the reliability of the stock assessment could be improved by using demographic methods to construct a prior for the intrinsic rate of increase（r）. Because we can make use of more information to improve the rationality of parameter estimation and the reliability of the stock assessment compared with traditional statistical methods by incorporating any available knowledge into the informative priors and analyzing the posterior distribution based on Bayesian framework in data-poor situations, we suggest that the Bayesian method should be an alternative method to be applied in data-poor species stock assessment, such as Indian Ocean albacore.

关键词： data-poor stock assessment Bayesian method catch data series demographic method Indian Ocean Thunnus alalunga

The Effect of Netting Solidity Ratio and Inclined Angle on the Hydrodynamic Characteristics of Knotless Polyethylene Netting

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Journal of Ocean University of China 2017年第5期16卷 814-822页

作者： TANG Hao HU Fuxiang xu liuxiong DONG Shuchuang ZHOU Cheng WANG xuefang College of Marine Sciences Shanghai Ocean University Shanghai 201306 P. R. China Faculty of Marine Science Tokyo University of Marine Science and Technology Minato Tokyo 108-8477 Japan National Engineering Research Center for Oceanic Fisheries Shanghai 201306 P. R. China Shanghai Collaborative Innovation Center for Oceanic Fisheries Shanghai 201306 P. R. China College of Fisheries Zhejiang Ocean University Zhoushan 316000 P. R. China

Knotless polyethylene(PE) netting has been widely used in aquaculture cages and fishing gears, especially in Japan. In this study, the hydrodynamic coefficient of six knotless PE netting panels with different solidity ratios were assessed in a flume tank under various attack angles of netting from 0?(parallel to flow) to 90?(perpendicular to flow) and current speeds from 40 cm s^(-1) to 130 cm s^(-1). It was found that the drag coefficient was related to Reynolds number, solidity ratio and attack angle of netting. The solidity ratio was positively related with drag coefficient for netting panel perpendicular to flow, whereas when setting the netting panel parallel to the flow the opposite result was obtained. For netting panels placed at an angle to the flow, the lift coefficient reached the maximum at an attack angle of 50? and then decreased as the attack angle further increased. The solidity ratio had a dual influence on drag coefficient of inclined netting panels. Compared to result in the literature, the normal drag coefficient of knotless PE netting measured in this study is larger than that of nylon netting or Dyneema netting.

关键词： panel fishing hydrodynamic Reynolds nylon polyethylene perpendicular Angle assessed aquaculture

Thermal and saline tolerance of Antarctic krill Euphausia superba under controlled in-situ aquarium conditions

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Journal of Oceanology and Limnology 2019年第3期37卷 1080-1089页

作者： ZHU Guoping LIU Zijun YANG Yang WANG Zhen YANG Wenjie xu liuxiong College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China Center for Polar Research Shanghai Ocean UniversityShanghai 201306China National Engineering Research Center for Oceanic Fisheries Shanghai 201306China Polar Marine Ecosystem Group Key Laboratory of Sustainable Exploitation of Oceanic Fisheries ResourcesMinistry of EducationShanghai Ocean UniversityShanghai 201306China

As a key species of the Southern Ocean ecosystem,the thermal and saline tolerances of Antarctic krill(Euphausia superb a Dana)are relatively unknown because of the challenging environment and complicated situations needed for observation have inhibited in-situ experiments in the ***,the thermal and saline tolerance of krill were examined under in-situ aquarium conditions with different controlled *** to the experiments,the critical lethal times of krill were 24h,2h and 0.5h under 9℃,12℃,and 15℃,respectively,and the estimated 50%lethal times were about 17.1 h and 1.7 h under 12℃and 15℃,***,the critical lethal times(the estimated 50%lethal times)of krill were approximately 14h and 0.5h(about 22.9 h and 1.7 h)of salinity under 19.7 and 15.9,*** observed critical and 50%lethal times of krill were 0.5 h and approximately 1.4 h,respectively,salinity under *** critical and 50%lethal temperatures of krill were 13℃and approximately 14.2℃,***,the critical and 50%lethal salinity was 19.6 and approximately 17.5 for the lower saline(below normal oceanic salinity[34.4])environment and 50.3 and approximately 53.2 for the higher saline(above 34.4)environment,*** upper thermal and saline preferences of krill can be considered 6℃and 26.8 to 41.2,*** results can provide potential scenarios for predicting the possible fate of this key species in the Southern Ocean.

关键词： Euphausia superba thermal tolerance saline tolerance thermal preference in-situ aquarium experiment

Modeling the Hook Depth Distribution of Pelagic Longlining in the Equatorial Area of Indian Ocean

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Journal of Ocean University of China 2012年第4期11卷 547-556页

作者： SONG Liming LI Jie GAO Panfeng ZHOU Ji xu liuxiong National Engineering Research Centre for Oceanic Fisheries ShanghaiOcean UniversityShanghai 201306P.R.China Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources of Chinese Ministry of Education College of Marine SciencesShanghai Ocean UniversityShanghai 201306P.R.China College of Marine Sciences Shanghai Ocean UniversityShanghai 201306P.R.China Lianyunggang Fishery Detachment Lianyunggang 222004P.R.China

A survey was conducted in the equatorial area of Indian Ocean for a better understanding of the dynamics of hook depth distribution of pelagic longline fishery. We determined the relationship between hook depth and vertical shear of current coefficieney, wind speed, hook position code, sine of wind angle, sine of angle of attack and weight of messenger weight. We identified the hook depth models by the analysis of covariance with a general linear model. The results showed that the wind effect on the hook depth can be ignored from October to November in the survey area; the surface current effect on the hook depth can be ignored; the equato- rial undercurrent is the key factor for the hook depth in Indian Ocean; and there is a negative correlation between the hook depth and vertical shear of current and angle of attack. It was also found that the deeper the hook was set, the higher hook depth shoaling was. The proposed model improves the accuracy of the prediction of hook depth, which can be used to estimate the vertical distribution of pelagic fish in water column.

关键词： hook depth longline temperature-depth-recorder equatorial area the Indian Ocean

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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Journal of Ocean University of China 2021年第5期20卷 1215-1235页

作者： THIERRY Bruno Nyatchouba Nsangue TANG Hao ACHILE Njomoue Pandong xu liuxiong ZHOU Cheng HU Fuxiang College of Marine Sciences Shanghai Ocean UniversityShanghai 201306China National Engineering Research Center for Oceanic Fisheries Shanghai 201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai 201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Ministry of EducationShanghai Ocean UniversityShanghai 201306China Scientific Observing and Experimental Station of Oceanic Fishery Resources Ministry of Agriculture and Rural AffairsShanghai 201306China Laboratory E3M National High Polytechnic School of DoualaUniversity of DoualaDouala 2701Cameroon Faculty of Marine Science Tokyo University of Marine Science and TechnologyMinatoTokyo 108-8477Japan

Nettings are complex flexible structures used in various *** the hydrodynamic characteristics,de-formation,and the flow field around nettings is important to design successful fishing *** 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 *** numerical model was based on the one-way coupling between computational fluid dynamics(CFD)and large deflection nonlinear structural ***-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 *** porous media model was chosen to model the nettings in the CFD *** data were compared with the experimental results of the physical model to validate the numerical *** 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,*** hydrodynamic forces of the polyethylene and nylon nettings decreased by approxi-mately 52.56%and 66.66%,respectively,with decreasing net *** 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 ***,the flow velocity reduction downstream from the netting in the wake region in-creased with increasing attack angle and net *** addition,the deformation,stress,and strain on each netting increased with in-creasing solidity ratio.

关键词： netting k-ωshear stress turbulent(SST)model porous media model large deflection nonlinear structural model hydrodynamic characteristics

Reproductive Biology of Yellowfin Tuna T. albacares in the West-Central Indian Ocean

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Journal of Ocean University of China 2008年第3期7卷 327-332页

作者： ZHU Guoping xu liuxiong ZHOU Yingqi SONG Liming College of Marine Science and Technology Shanghai Ocean University Shanghai 200090 P. R. China The Key Laboratoy of Oceanic Fisheries Resources Exploitation of Shanghai Education Commission Shanghai 200090 P R. China

Survey of yellowfin tuna in the west-central Indian Ocean was conducted on board of Chinese longliners during 2003,2004 and 2005,which is a part of Chinese Tuna Fishery Scientific Observer Program(CTFSOP) . The reproductive biology has been investigated. A total of 1 023 samples are collected including 417 ovaries and 606 testes. Spawning activities of yellowfin tuna have been studied for both male and female from January to June. The data showed that the average monthly sex ratio is 0.59,and the minimum length at sexual maturity is 101 cm for female and 110 cm for male respectively. Length at 50% sexual maturity is esti-mated at 113.77 cm for female and 120.20 cm for male,whereas maturation rate is 0.066 cm-1 for female and 0.091 cm-1 for male. Sex ratio by length class indicates that the proportion of male is higher than female's along with size increasing;for instance,in the group of the body length longer than 145 cm,some females have their body length from 145 to 160 cm and males have their body length at 160 cm and even longer. Statistically,yellowfin tuna has a significant seasonal reproduction.

关键词： reproductive biology yellowfin tuna T. albacares west-central Indian Ocean sex ratio

A review on fishing gear in China: Selectivity and application

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Aquaculture and Fisheries 2022年第4期7卷 345-358页

作者： Zhongqiu Wang Hao Tang liuxiong xu Jian Zhang East China Sea Fisheries Research Institute Chinese Academy of Fishery AcademyShanghai200090China College of Marine Sciences Shanghai Ocean UniversityShanghai201306China National Engineering Research Center for Oceanic Fisheries Shanghai201306China Key Laboratory of Oceanic Fisheries Exploration Ministry of Agriculture and Rural AffairsShanghai201306China The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources Shanghai Ocean UniversityMinistry of EducationShanghai201306China Center for Polar Research Shanghai Ocean UniversityShanghai201306China

In the 1980s,China’s offshore marine fishery resources declined,thus fishing gear selectivity gradually became a focus of scientific fishery *** of fishing gear selectivity mainly focus on five kinds of fishing gear:trawls,shrimp beam trawls,stow nets,gillnets,and *** net method is the main method used in the comparative study of codend selectivity of both trawls and stow *** results showed that(1)Bottom trawls,targeting Larimichthys polyactis(the Little yellow croaker)and Trichiurus haumela(the Hairtail),should have a minimum mesh size of the codend no less than 60 mm in the Yellow and East China *** the codend should use a square mesh with a minimum mesh size of 40 mm due to the variety of targeted species in the South China Sea.(2)Pair pelagic trawls,targeting pelagic species such as Engraulis japonicus(the Japanese anchovy),Pampus argenteus(the Silvery pomfret),Scomberomorus niphonius(the Spanish mackerel),as well as bottom species such as *** and ***,should have a minimum mesh size of the codend no less than 56 mm in the Yellow Sea.(3)Shrimp beam trawls should use shrimp/fish separator devices(e.g.,separator panels,vertical separator panels,and sorting grids)to improve intra-species selectivity and reduce by-catch of non-target fish.(4)Canvas stow nets,targeting *** and ***,should have a minimum mesh size of the codend no less than 55 mm.(5)Gillnets,the minimum mesh size should be determined for catching traditional economic species,but also the optimal mesh size for newly developed *** as,gillnets with mesh size of 35-38.71 mm targeting Harpodon nehereus(the Bombay duck),55 mm targeting *** and Nemipterus virgatus(the Golden threadfin bream),72 mm targeting Dentex tumifrons(the yellow sea breams)or Scomberomorus commersoni with body length of 280 mm,100 mm targeting ***,104 mm or 146 mm targeting 2-3 year or 6-7 year ***,120 mm targeting *** with body length

关键词： Trawl Mesh size Shrimp/fish separator Stow net Gillnet

Spatial variation in bigeye tuna Thunnus obesus size at sexual maturity in the eastern Pacific Ocean

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Aquaculture and Fisheries 2023年第5期8卷 572-578页

作者： Hongji Huang Cheng Zhou liuxiong xu Jiangfeng Zhu xuefang Wang Jie Cao College of Marine Sciences Shanghai Ocean University999 Huchenghuan RoadLingang New DistrictShanghai201306PR China National Engineering Research Center for Oceanic Fisheries Shanghai201306China Department of Applied Ecology Center for Marine Sciences and TechnologyNorth Carolina State UniversityMorehead CityNC28557USA

Understanding the reproductive characteristics of a species is of crucial for accurate stock assessment and management plans to ensure sustainable *** this study,the size at 50%sexual maturity(L50)parameters in different bio-ecological provinces were estimated for bigeye tuna,Thunnus obesus,sampled from the Eastern Pacific Ocean tuna fisheries-dependent survey from 2013 to *** overall sex ratio of the catch during the sampling differed significantly from 1:*** tuna exhibit sexual dimorphism in the growth of males and females,with a clear shift in predominance from female to male with increasing *** the North Pacific Sub-tropical Gyre(east)(NPST-east),North Pacific Tropical Gyre(NPTG),Pacific North Equatorial Countercurrent(PNEC),and Pacific Equatorial Divergence(PEQD),females(meals)reached sexual maturity round 102 cm(106 cm),106 cm(100 cm),125 cm(110 cm),and 113 cm(110 cm),respectively,the estimated L50 of bigeye tuna was 124.08 cm,121.97 cm,139.92 cm and 132.45 cm,*** degree of populations mixing between equatorial(PNEC and PEQD)and high-latitude regions(NPST-east and NPTG)is extremely small,but it is reasonably high between the NPST-east and NPTG or PNEC and *** parameters were significantly different,suggesting the occurrence of a spatial difference in the size-at-maturity of bigeye tuna between these bio-ecological *** findings of this study provide the key information for understanding the life history of bigeye tuna in the Eastern Pacific Ocean and will contribute to the conservation and sustainable yield of this species.

关键词： Eastern Pacific ocean Bigeye tuna Sexual maturity Mixed-effects model