厄尔尼诺-南方涛动现象(EL Ni o Southern Oscillation)是引起全球气候变化的最强烈的海-气相互作用现象,对世界渔业生产具有重要影响。本研究利用1982~2001年Ni o 3.4区海表温度与中西太平洋(20°N^20°S、120°E^150°...厄尔尼诺-南方涛动现象(EL Ni o Southern Oscillation)是引起全球气候变化的最强烈的海-气相互作用现象,对世界渔业生产具有重要影响。本研究利用1982~2001年Ni o 3.4区海表温度与中西太平洋(20°N^20°S、120°E^150°W)鲣鱼围网单位捕捞努力量渔获量经度重心的关系,就厄尔尼诺-南方涛动现象对中西太平洋鲣鱼围网渔场变动的影响进行分析研究。结果表明,厄尔尼诺-南方涛动现象对中西太平洋鲣鱼围网渔场的空间分布有显著影响,厄尔尼诺发生时,鲣鱼围网单位捕捞努力量渔获量经度重心随着暖池的东扩而东移,拉尼娜发生时则随着暖池向西收缩而西移。同时,Ni o 3.4区海表温度与鲣鱼围网单位捕捞努力量渔获量经度重心有显著相关关系(Pearson相关系数r=0.186,P<0.01),因此,可将Ni o 3.4区海表温度作为预报、预测中西太平洋鲣鱼围网渔场位置的一个重要指标。展开更多
The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation...The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation to reconstruct daily subsurface oceanic environmental information according to fishery dates and locations.The relationship between subsurface information and matching yellowfin tuna(YFT)in the western and central Pacific Ocean(WCPO)was examined using catch data from January 1,2008 to August 31,2017.The seawater temperature and salinity results showed differences of less than±0.5°C and±0.01 compared with the truth observations respectively.Statistical analysis revealed that the most suitable temperature for YFT fishery was 28–29°C at the near-surface.The most suitable salinity range for YFT fishery was 34.5–36.0 at depths shallower than 300 m.The suitable upper and lower bounds on the depths of the thermocline were 90–100 m and 300–350 m,respectively.The thermocline characteristics were prominent,with a mean temperature gradient exceeding 0.08°C/m.These results indicate that the profiles constructed by gradient-dependent optimal interpolation were more accurate than those of the nearest profiles adopted.展开更多
Length composition analysis can provide insights into the dynamics of a fish population.Accurate quantification of the size structure of a population is critical to understand the status of a fishery and how the popul...Length composition analysis can provide insights into the dynamics of a fish population.Accurate quantification of the size structure of a population is critical to understand the status of a fishery and how the population responds to environmental stressors.A scientific observer program is a reliable way to provide such accurate information.However,100%observer coverage is usually impossible for most fisheries because of logistic and financial constraints.Thus,there is a need to evaluate observer program performance,identify suitable sample sizes,and optimize the allocation of observation efforts.The objective of this study is to evaluate the effects of sample size on the quality of length composition data and identify an optimal coverage rate and observation ratio to improve the observation efficiency using an onboard observer data set from China's tuna longline fishery in the western and central Pacific Ocean.We found that the required sample size varies with fish species,indices used to describe length composition,the acceptable accuracy of the estimates,and the allocation methods of sampling effort.Ignoring other information requirements,1000 individuals would be sufficient for most species to reliably quantify length compositions,and a smaller sample size could generate reliable estimates of mean length.A coverage rate of 20%would be sufficient for most species,but a lower coverage rate(5%or 10%)could also be effective to meet with the accuracy and precision requirement in estimating length compositions.A nonrandom effort allocation among fishing baskets within a set could cause the length composition to be overestimated or underestimated for some species.The differences in effective sample sizes among species should be included in the consideration for a rational allocation of observation effort among species when there are different species management priorities.展开更多
文摘厄尔尼诺-南方涛动现象(EL Ni o Southern Oscillation)是引起全球气候变化的最强烈的海-气相互作用现象,对世界渔业生产具有重要影响。本研究利用1982~2001年Ni o 3.4区海表温度与中西太平洋(20°N^20°S、120°E^150°W)鲣鱼围网单位捕捞努力量渔获量经度重心的关系,就厄尔尼诺-南方涛动现象对中西太平洋鲣鱼围网渔场变动的影响进行分析研究。结果表明,厄尔尼诺-南方涛动现象对中西太平洋鲣鱼围网渔场的空间分布有显著影响,厄尔尼诺发生时,鲣鱼围网单位捕捞努力量渔获量经度重心随着暖池的东扩而东移,拉尼娜发生时则随着暖池向西收缩而西移。同时,Ni o 3.4区海表温度与鲣鱼围网单位捕捞努力量渔获量经度重心有显著相关关系(Pearson相关系数r=0.186,P<0.01),因此,可将Ni o 3.4区海表温度作为预报、预测中西太平洋鲣鱼围网渔场位置的一个重要指标。
基金The National Natural Science Foundation of China under contract No.4210060098the Foundation of Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources under contract No.A1-2006-21-200201.
文摘The current lack of high-precision information on subsurface seawater is a constraint in fishery research.Based on Argo temperature and salinity profiles,this study applied the gradient-dependent optimal interpolation to reconstruct daily subsurface oceanic environmental information according to fishery dates and locations.The relationship between subsurface information and matching yellowfin tuna(YFT)in the western and central Pacific Ocean(WCPO)was examined using catch data from January 1,2008 to August 31,2017.The seawater temperature and salinity results showed differences of less than±0.5°C and±0.01 compared with the truth observations respectively.Statistical analysis revealed that the most suitable temperature for YFT fishery was 28–29°C at the near-surface.The most suitable salinity range for YFT fishery was 34.5–36.0 at depths shallower than 300 m.The suitable upper and lower bounds on the depths of the thermocline were 90–100 m and 300–350 m,respectively.The thermocline characteristics were prominent,with a mean temperature gradient exceeding 0.08°C/m.These results indicate that the profiles constructed by gradient-dependent optimal interpolation were more accurate than those of the nearest profiles adopted.
基金The work was supported by the scientific observer program of the distant-water fishery of the Agriculture Ministry of China(08–25).
文摘Length composition analysis can provide insights into the dynamics of a fish population.Accurate quantification of the size structure of a population is critical to understand the status of a fishery and how the population responds to environmental stressors.A scientific observer program is a reliable way to provide such accurate information.However,100%observer coverage is usually impossible for most fisheries because of logistic and financial constraints.Thus,there is a need to evaluate observer program performance,identify suitable sample sizes,and optimize the allocation of observation efforts.The objective of this study is to evaluate the effects of sample size on the quality of length composition data and identify an optimal coverage rate and observation ratio to improve the observation efficiency using an onboard observer data set from China's tuna longline fishery in the western and central Pacific Ocean.We found that the required sample size varies with fish species,indices used to describe length composition,the acceptable accuracy of the estimates,and the allocation methods of sampling effort.Ignoring other information requirements,1000 individuals would be sufficient for most species to reliably quantify length compositions,and a smaller sample size could generate reliable estimates of mean length.A coverage rate of 20%would be sufficient for most species,but a lower coverage rate(5%or 10%)could also be effective to meet with the accuracy and precision requirement in estimating length compositions.A nonrandom effort allocation among fishing baskets within a set could cause the length composition to be overestimated or underestimated for some species.The differences in effective sample sizes among species should be included in the consideration for a rational allocation of observation effort among species when there are different species management priorities.
