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Search Results: 1 - 10 of 42547 matches for " XU Liuxiong "
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Growth and mortality rates of yellowfin tuna, Thunnus albacares (Perciformes: Scombridae), in the eastern and central Pacific Ocean
Zhu, Guoping;Xu, Liuxiong;Dai, Xiaojie;Liu, Wei;
Zoologia (Curitiba) , 2011, DOI: 10.1590/S1984-46702011000200007
Abstract: age and growth parameters were estimated for the yellowfin tuna thunnus albacares (bonnaterre, 1788). atotal of 443 individuals were sampled from china longline fisheries in the eastern and central pacific ocean from february to november 2006. the von bertalanffy growth parameters were estimated at l∞ = 175.9 cm fork length, k = 0.52 year-1, and t0 = 0.19 year. the total mortality rate (z) was estimated to be from 1.19 to 1.93 year-1, the fishing mortality (f) and the natural mortality (m) were calculated to be 0.91 year-1 and 0.65 year-1, respectively. the rate of exploitation (u) was estimated to be 0.46. this study provides estimates of growth and mortality rate for yellowfin tuna in the eastern and central pacific ocean, which may be used as biological input parameters in future stock assessments for the oceanic region. however, age analysis with other techniques, additional validation of the size composition and stock structure are also needed.
Growth and mortality rates of bigeye tuna Thunnus obesus (Perciformes: Scombridae) in the central Atlantic Ocean
Zhu,Guoping; Xu,Liuxiong; Zhou,Yingqi; Chen,Xinjun;
Revista de Biología Tropical , 2009,
Abstract: age and growth parameters were estimated for bigeye tuna thunnus obesus lowe, 1839 sampled from china longline fisheries in the central atlantic ocean from october 2002 to july 2003 and from august 2004 to march 2005. the von bertalanffy growth parameters were estimated at l8=217.9 cm fork length, k=0.23 year-1, and t0=-0.44 year. the total mortality rate (z) was estimated to be from 0.82 to 1.02, the fishing mortality (f) and the natural mortality were 0.54 year-1 and 0.39 year-1, respectively. the exploitation ratio (e) was 0.35. this study provides the detailed estimates of growth and mortality rate for bigeye tuna in the central atlantic ocean, which can be used as biological input parameters in further stock evaluations in this region. however, age analysis, additional validation of the size composition and stock structure are needed for future studies. rev. biol. trop. 57 (1-2): 79-88. epub 2009 june 30.
Growth and mortality rates of bigeye tuna Thunnus obesus (Perciformes: Scombridae) in the central Atlantic Ocean
Guoping Zhu,Liuxiong Xu,Yingqi Zhou,Xinjun Chen
Revista de Biología Tropical , 2009,
Abstract: Age and growth parameters were estimated for bigeye tuna Thunnus obesus Lowe, 1839 sampled from China longline fisheries in the central Atlantic Ocean from October 2002 to July 2003 and from August 2004 to March 2005. The von Bertalanffy growth parameters were estimated at L8=217.9 cm fork length, k=0.23 year-1, and t0=-0.44 year. The total mortality rate (Z) was estimated to be from 0.82 to 1.02, the fishing mortality (F) and the natural mortality were 0.54 year-1 and 0.39 year-1, respectively. The exploitation ratio (E) was 0.35. This study provides the detailed estimates of growth and mortality rate for bigeye tuna in the central Atlantic Ocean, which can be used as biological input parameters in further stock evaluations in this region. However, age analysis, additional validation of the size composition and stock structure are needed for future studies. Rev. Biol. Trop. 57 (1-2): 79-88. Epub 2009 June 30.
Application of Numerical Simulation for Analysis of Sinking Characteristics of Purse Seine Application of Numerical Simulation for Analysis of Sinking Characteristics of Purse Seine
ZHOU Cheng,XU Liuxiong,ZHANG Xinfeng,YE Xuchang
- , 2015,
Abstract: 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
The Large-Scale Deployment of Fish Aggregation Devices Alters Environmentally-Based Migratory Behavior of Skipjack Tuna in the Western Pacific Ocean
Xuefang Wang, Yong Chen, Samuel Truesdell, Liuxiong Xu, Jie Cao, Wenjiang Guan
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098226
Abstract: Fish aggregation devices (FADs) have been used extensively in the tuna purse seine fishery since the 1980s. This long-term modification of natural habitat has generated discussions as to whether FADs impact movement patterns of tuna species. We examined this question using data collected from the skipjack tuna (Katsuwonus pelamis) fishery. We used the longitudinal gravitational center of catch (G) to examine temporal variability in skipjack movement in the Western and Central Pacific Ocean, and related this to El Ni?o Southern Oscillation (ENSO) events. We found that in most cases G for free-swimming school sets changed with the onset of ENSO events, while G for floating-object-associated school sets remained relatively constant. This suggests that skipjack exhibit distinguishable behavioral strategies in response to ENSO events: they either react by moving long distances or they associate with floating objects. There has been no previous attempt to evaluate the interaction between FADs and the environmentally-determined movement of skipjack; this study shows evidence of an interaction, which should be considered when managing skipjack populations.
The Effect of Netting Solidity Ratio and Inclined Angle on the Hydrodynamic Characteristics of Knotless Polyethylene Netting The Effect of Netting Solidity Ratio and Inclined Angle on the Hydrodynamic Characteristics of Knotless Polyethylene Netting
TANG Hao,HU Fuxiang,XU Liuxiong,DONG Shuchuang,ZHOU Cheng,WANG Xuefang
- , 2017,
Abstract: 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
mRNA/microRNA Profile at the Metamorphic Stage of Olive Flounder (Paralichthys olivaceus)
Caixia Xie,Shanliang Xu,Linlin Yang,Zhonghe Ke,Jubin Xing,Junwei Gai,Xiaoling Gong,Liuxiong Xu,Baolong Bao
Comparative and Functional Genomics , 2011, DOI: 10.1155/2011/256038
Abstract: Flatfish is famous for the asymmetric transformation during metamorphosis. The molecular mechanism behind the asymmetric development has been speculated over a century and is still not well understood. To date, none of the metamorphosis-related genes has been identified in flatfish. As the first step to screen metamorphosis-related gene, we constructed a whole-body cDNA library and a whole-body miRNA library in this study and identified 1051 unique ESTs, 23 unique miRNAs, and 4 snoRNAs in premetamorphosing and prometamorphosing Paralichthys olivaceus. 1005 of the ESTs were novel, suggesting that there was a special gene expression profile at metamorphic stage. Four miRNAs (pol-miR-20c, pol-miR-23c, pol-miR-130d, and pol-miR-181e) were novel to P. olivaceus; they were characterized as highly preserved homologies of published miRNAs but with at least one nucleotide differed. Representative 24 mRNAs and 23 miRNAs were quantified during metamorphosis of P. olivaceus by using quantitative RT PCR or stem-loop qRT PCR. Our results showed that 20 of mRNAs might be associated with early metamorphic events, 10 of mRNAs might be related with later metamorphic events, and 16 of miRNAs might be involved in the regulation of metamorphosis. The data provided in this study would be helpful for further identifying metamorphosis-related gene in P. olivaceus.
mRNA/microRNA Profile at the Metamorphic Stage of Olive Flounder (Paralichthys olivaceus)
Caixia Xie,Shanliang Xu,Linlin Yang,Zhonghe Ke,Jubin Xing,Junwei Gai,Xiaoling Gong,Liuxiong Xu,Baolong Bao
International Journal of Genomics , 2011, DOI: 10.1155/2011/256038
Abstract: Flatfish is famous for the asymmetric transformation during metamorphosis. The molecular mechanism behind the asymmetric development has been speculated over a century and is still not well understood. To date, none of the metamorphosis-related genes has been identified in flatfish. As the first step to screen metamorphosis-related gene, we constructed a whole-body cDNA library and a whole-body miRNA library in this study and identified 1051 unique ESTs, 23 unique miRNAs, and 4 snoRNAs in premetamorphosing and prometamorphosing Paralichthys olivaceus. 1005 of the ESTs were novel, suggesting that there was a special gene expression profile at metamorphic stage. Four miRNAs (pol-miR-20c, pol-miR-23c, pol-miR-130d, and pol-miR-181e) were novel to P. olivaceus; they were characterized as highly preserved homologies of published miRNAs but with at least one nucleotide differed. Representative 24 mRNAs and 23 miRNAs were quantified during metamorphosis of P. olivaceus by using quantitative RT PCR or stem-loop qRT PCR. Our results showed that 20 of mRNAs might be associated with early metamorphic events, 10 of mRNAs might be related with later metamorphic events, and 16 of miRNAs might be involved in the regulation of metamorphosis. The data provided in this study would be helpful for further identifying metamorphosis-related gene in P. olivaceus. 1. Introduction Flatfish is famous for the asymmetric transformation during metamorphosis, especially one eye migrating to the other side. Other metamorphosis events include cranium deformation, asymmetric pigmentation, and 90-degree rotation in posture with a lifestyle transition from pelagic to benthic. The molecular mechanism of morphologic left/right asymmetry in Olive flounder, Paralichthys olivaceus, was thought to be different from that of interior organ asymmetry in vertebrate [1]. Thyroid hormone (TH) was proposed to regulate metamorphosis in flatfish [2–5]. As the nuclear receptor of TH, thyroid hormone receptor (TR) should be involved in the TH-inducing signal pathway. The spatial expression of the TR genes has been investigated in the metamorphosing Olive flounder [6]; however, it still cannot determine which metamorphosis events were regulated by TR in flatfish. In TH-TR signal pathway, the downstream genes will unavoidably be investigated in the future. To date, very few genes were investigated in metamorphosing flatfish [6–9]. Even though the cDNA libraries of various tissue types in P. olivaceus were constructed, especially immune-related tissues [10], the gene expression profile in metamorphosing P.
A comparative study of feeding behavior of Thunnus obesus in the west-central Indian Ocean and the western Atlantic Ocean
印度洋中西部和大西洋西部水域大眼金枪鱼的食性比较

Zhu Guoping,Xu Liuxiong,Zhou Yingqi,Jiang Wenxin,
朱国平
,许柳雄,周应祺,姜文新

生态学报 , 2007,
Abstract: 根据2004年8月至2005年3月大西洋西部水域及2003年12月份至2004年5月份在印度洋中西部水域金枪鱼延绳钓渔业所获取的大眼金枪鱼数据,对两个诃查区域内的大眼金枪鱼食性进行了研究。结果表明,印度洋中西部水域大眼金枪鱼的食物组成包括沙丁鱼、鱿鱼、乌贼等13个饵料类群,其中主要摄食鱿鱼和沙丁鱼;大西洋西部水域大眼金枪鱼主要摄食沙丁鱼、鱿鱼、虾类等13种饵料类群,主要以沙丁鱼为饵,其次为鱿鱼。印度洋中西部水域大眼金枪鱼空胃率非常高,基本上维持在60%以上;大西洋西部水域大眼金枪鱼空胃率相对较低,基本上都在30%以下。印度洋中西部水域大眼金枪鱼平均饱满指数变化不大,基本上维持在0.40~0.55之间。大西洋西部水域大眼金枪鱼平均饱满指数变化也不太大。印度洋中西部水域大眼金枪鱼各月平均饱满指数高于大西洋西部水域,且各月空胃率高于后者。印度洋中西部和大西洋西部水域大眼金枪鱼Shannon-Weiner多样性指数H’基本上都1.50~2.00之间变化。相同调查月份内,印度洋中西部水域大眼金枪鱼食物Pielou均匀度指数J’均高于大西洋西部水域。
夏季青藏高原o3低值与南亚高压东西振荡的关系
舒斯,何金海,刘毅,王永,蔡兆男,LIUXiong
气候与环境研究 , 2011, DOI: 10.3878/j.issn.1006-9585.2011.01.04
Abstract: 利用o3监测仪(ozonemonitoringinstrument,omi)卫星o3廓线资料和ncep/ncar再分析资料,研究了2006年夏季南亚高压偏西型和偏东型条件下青藏高原地区o3垂直结构和变化特征差异。结果表明,夏季南亚高压东西振荡与青藏高原o3分布存在密切的关系,在西(东)部型南亚高压条件下,夏季青藏高原地区大气、对流层和平流层o3柱总量低值中心均偏西(东),位于青藏高原西(东)部,尤其是在南亚高压最强的对流层顶附近,o3低值中心位于南亚高压中心。在西部型南亚高压条件下,低纬度地区含低浓度o3的空气不易到达高原上空,青藏高原上空的o3低值较弱。在东部型南亚高压条件下,从低纬度经中南半岛西北方向孟加拉湾带来的低纬地区低浓度o3,在青藏高原上空堆积,形成o3低值中心。因此,南亚高压东西振荡是影响青藏高原上空o3低值中心变化的重要因素之一,该研究对理解南亚高压东西振荡机制及提高我国气候预测具有一定的指导意义。
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