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1.
本文介绍分层抽样方法、误差分析以及分层抽样样本量的确定方法。以松花江干流捕捞抽样调查为例,介绍小规模渔业抽样调查的样本量的确定过程。选取方正、依兰、桦川境内渔船刺网作业进行地点分层,选取依兰境内刺网、张网作业进行作业方式分层抽样,同时将分层抽样结果和相应的简单随机抽样进行误差对比分析。结果表明:简单随机抽样误差是地点分层抽样的3.4倍,是作业方式分层抽样的5.2倍,说明分层抽样误差小、精度高。在经费允许条件下,分层抽样是渔业生产统计调查的首选方法。  相似文献   

2.
利用分层抽样方法进行海洋捕捞渔业统计,能客观有效地收集相关渔业数据,并能推算出各捕捞作业类型的渔获量。本文介绍了分层抽样的设计方案,着重对如何收集捕捞渔业结构信息,如何对总捕获量、单位日渔获量、效益以及捕获鱼种统计的计算方法进行了概述,对渔业统计人员如何开展抽样调查发挥一定指导作用。  相似文献   

3.
应用Bootstrap方法,对太湖捕捞渔业抽样调查参数估计进行研究,探讨分层抽样调查在捕捞产量统计中的应用。随机抽样模拟的结果表明,有放回的Bootstrap方法适用于抽样比例较小的分层抽样调查。对于总体分布未知且样本量容量有限的情况下分层抽样调查的方差估计,重权Bootstrap方法相比其它方法具有明显的优势,适合用于渔业抽样调查工作。  相似文献   

4.
经济高效的渔业资源调查采样有利于保证调查数据的质量,提高调查效率,从而为渔业科学研究提供可靠数据。根据2016—2017年山东近海渔业资源底拖网季度调查数据,以小黄鱼、矛尾虾虎鱼、方氏云鳚和星康吉鳗作为目标鱼种,使用Kriging插值法模拟了目标鱼种在4个季节的相对资源量分布,设置简单随机抽样(SRS)、常规系统抽样(SYS_r)、等距系统抽样(SYS_h)、按水深分层随机抽样(StRS_depth)、按区域分层随机抽样(StRS_region)和综合水深和区域分层随机抽样(StRS_total)共6种备选采样设计方案,利用计算机模拟方法对Kriging插值数据进行再抽样,估计各目标鱼种资源量指数,以相对估计误差(relative estimation error, REE)和相对偏差(relative bias, RB)衡量估计结果的精准度,以准确度变化率(accuracy change rate,ACR)小于等于10%的标准确定最优调查站位数,比较不同采样设计在估计多目标鱼种资源量指数方面的表现并进行样本量优化。结果发现,3种抽样方法的估计准度不同,简单随机抽样分层随机抽样系统抽样。除系统抽样外,其余采样设计方案均为无偏估计。随调查站位数增加,系统抽样的REE表现出无规律波动趋势。分层随机抽样的REE略低于系统抽样,且随站位数增加而降低。分层随机抽样是最优抽样方法,StRS_total是最优分层方案。不同目标鱼种、季节调查所需站位数不同,StRS_total进行4季度调查的最优站位数可设为80。  相似文献   

5.
应用分层抽样技术估计北部湾底拖网渔业产量   总被引:1,自引:0,他引:1  
传统的按行政单元逐级上报的渔业产量调查方法在数据获取过程中受人为因素的干扰,而全面普查的方法受限于时间和经费,相比而言,抽样调查是一种科学合理的方法。本研究于2007年8月对北部湾底拖网产量进行了调查,以全体底拖网渔船为抽样总体,按功率段划分了抽样层次,按比例分配了抽样单元数,分别以生产渔船总数和总功率数推算总产量,并比较了这两种方法的方差。结果表明,用每kW平均产量估计总产量的变异系数为1.13%,用单船平均产量估计总产量的变异系数为14.65%。同时由于渔业抽样调查的难点在于总体船数的掌握,建议统计推断时,采用单位渔捞努力量渔获量(CPUE)推算总体渔获量。  相似文献   

6.
世界渔业产量是如何统计的   总被引:1,自引:0,他引:1  
世界渔业产量由联合国粮农组织统计.什么是渔业产量,各国规定不完全一样.我国称为水产品产量.有的国家称捕捞量,有的国家称上岸量.这些名称不但叫法不一样,而且往往包含的内容也有差别.粮农组织认为,对鱼类、甲壳类、软体动物类、杂水生动物类应用“名义渔获量”来表示.而海藻、鸟粪、鸟蛋、珍珠、贝壳、珊瑚、海绵等用“产量”表示,鲸类和海豹类使用,“捕获量”表示更为确切.但为了统计上的方便,粮农组织在一些统计表中也往往笼统地用“名义渔获量”这个名称. 粮农组织对名义渔获量的统计范围、计算方法、统计年度等都有具体规定.有些国家的规定在某些方面与其不一致时,向粮农组织提供的数字,一般应按粮农组织的规定进行调整.  相似文献   

7.
渔获量不确定性对印度洋大眼金枪鱼资源评估的影响   总被引:1,自引:0,他引:1  
大眼金枪鱼(Thunnus obesus)是最具经济价值的热带金枪鱼类,其资源状况一直是区域性金枪鱼渔业管理组织关注的重点。由于多种渔业作业、捕捞船队构成复杂,印度洋大眼金枪鱼的历史渔获量统计存在一定的偏差(Bias),但国际上近些年开展资源评估时都忽略了这一偏差。本研究根据1979~2015年的年渔获量、年龄结构渔获量及相对丰度指数数据,运用年龄结构资源评估模型(ASAP)对印度洋大眼金枪鱼资源进行评估,重点考查渔获量的不确定性(观测误差和统计偏差)对资源评估结果的影响。结果显示,印度洋大眼金枪鱼当前资源总体没有过度捕捞,但2015年初显示轻微的过度捕捞,通过对比基础模型与8个灵敏度分析模型的评估结果发现,渔获量观测误差(CV)的预设对资源开发状态的判断有一定的影响。当渔获量统计偏差调整量为15%时(即历史渔获量被低估了),评估结果与基础模型基本一致;统计偏差调整量为20%时,评估结果有过度捕捞的趋势。本研究结果表明,资源评估模型中渔获量观测误差的设定和历史渔获量统计偏差均会对评估结果产生影响,后者更为明显,因此,二者均不能忽略。  相似文献   

8.
外刊信息     
<正> 1984年世界渔获量统计据联合国粮农组织统计数字表明,1984年世界渔获量将超出历年最高数字,可达8,000万吨。在统计栏里,日本居首位,渔获量为1,180多万吨。苏联排第二,比原先增长7.6%,达1,050万吨。中国的渔获量520万吨。美国渔获量增长得很快,这一年的增长率是14.5%,产量为470万吨,排列第四,智利的渔获量是440万吨。  相似文献   

9.
<正> 据联合国粮农组织发表的1995年世界渔获量统计速报,1995年世界总渔获量为11140万t,而1994年为10958万t,1993年为10218万t,再创历史新高。若与1993年的渔获量相比,1995年的增长率不像1994年增加7%那么高,而只增加1.6%。若与1950年相比,45年间世界渔获量增长了五倍以上。在1995年总渔获量中,80%是由渔获量前20名的  相似文献   

10.
总论     
箭鱼是亚洲延绳钓船队(中国台湾省、日本、朝鲜民主主义人民共和国)、马达加斯加和南非在整个印度洋开发的金枪鱼种系。70年代开始总渔获量下降,但后来稳定增长到.1982年,1983~1992年急剧增长,1993年达到高峰,约1.8万 t.渔获量的增长很可能是台湾省和斯里兰卡渔获大增的结果,斯里兰卡国内刺网渔获量的增加最可能改善统计范围,而不是捕捞措施或目标鱼种的真实变化。印度洋箭鱼资源状况目前还不清楚,专家们  相似文献   

11.
We compared the performance of two traditional sampling designs with three adaptive sampling designs using simulated data based on fishery-independent surveys for yellow perch in Lake Erie. Traditionally, the fishery-independent survey has been conducted with a stratified random sampling design based on basin and depth strata; however, adaptive sampling designs are thought to be more suitable for surveying heterogeneous populations. A simulation study was conducted to compare these designs by examining the accuracy and precision of the estimators. Initially in the simulation study, we used bias, variance of the mean, and mean squared error (MSE) of the estimators to compare simple random sampling (SRS), stratified random sampling (StRS), and adaptive two-phase sampling (ATS). ATS was the best design according to these measurements. We then compared ATS, adaptive cluster sampling (ACS), adaptive two-stage sequential sampling (ATSS), and the currently used stratified random sampling design. ATS performed better than the other two approaches and the current stratified random sampling design. We concluded that ATS is preferable for yellow perch fishery-independent surveys in Lake Erie. Simulation study is a preferred approach when we seek an appropriate sampling design or evaluate the current sampling design.  相似文献   

12.
关于改善我国海洋渔业统计制度的建议   总被引:1,自引:0,他引:1  
可靠的渔业统计制度是渔业管理决策最重要的基础支撑,也是渔业监督管理的重要依据和手段。文章扼要地介绍了《联合国海洋法公约》等国际条约和文件对渔业统计的基本要求、有关国家和我国的渔业统计制度,指出了我国层层上报的全面渔业统计方式已不能适应当前渔业经济体制和管理需求、渔业统计指标体系不完整、难以全面反映渔业实际、统计监督和数据核实制度存在不足、渔业统计数据信息化滞后等问题。建议:(1)严格执行《渔业法》明确规定的捕捞日志制度;(2)规定渔获物只能在限定港口卸载,建立渔获物上报与统计监督制度;(3)逐步实行随船观察员制度;(4)完善立法,提供法律支撑和保障。  相似文献   

13.
An estimate of the age composition of a commercial swordfish catch and its variance was obtained using the replicate full jackknife estimator for two-phase sampling where the sampling units in the first phase are clusters (vessel-trips) and the units of the second phase are individual fishes. The jackknife variance estimator was compared with an analytical estimator of variance commonly used in fisheries studies which ignores the clustering, and assumes simple random sampling of individual fish. The application of these naïve estimators to the Chilean South Pacific swordfish fishery results in an underestimation of the variance. This is a consequence of using an inappropriate primary sampling unit of analysis in the first-phase sample where the vessel-trip unit is replaced by an individual fish unit, thus ignoring the intra-cluster correlation in age samples. The jackknife estimator of variance is an alternative useful for complex two-phase sampling designs.  相似文献   

14.
Abstract. The system for reporting fishery statistics in Indonesia, a developing country with a large marine fishery, provides an example of the problems of using fishery statistics as the basis for stock assessment and other fishery management work. The statistical system now used was first instituted in 1976. In spite of the millions of pieces of information processed by the system annually, provincial and national reports are produced on a reasonably timely basis. A field review on parts of the island of Java revealed, however, that data from the system are of limited use to the cautious analyst. Significant inaccuracies are present. A brief review of the system, its general accuracy and possible sources of inaccuracies arc given.  相似文献   

15.
程文  纪毓鹏  薛莹  张崇良  徐浩  任一平  徐宾铎 《水产学报》2022,46(12):2357-2365
鱼类体长-体重关系参数估计的准确与否影响进一步的渔业资源评估和管理。不同采样设计获得的生物学数据,对鱼类体长-体重关系参数b估计可能会有一定的影响。本文基于2013-2014年在黄河口水域调查获得的矛尾虾虎鱼(Chaemrichthys stigmatias)体长、体重数据,采用计算机模拟重抽样方法,选取相对估计误差和相对偏差两个指标,比较了不同采样设计对估计矛尾虾虎鱼体长-体重关系参数b的影响。结果表明,增加样本量可有效提高其体长-体重关系参数b的估计精度。不同季节数据对参数估计精度具有不同影响,应用多季节调查采样数据估计参数精度往往优于单季节采样。夏季数据对矛尾虾虎鱼体长-体重关系参数估计尤为重要。方案9(夏-冬季方案)在样本量达到540尾时,相对估计误差REE为2.08%,相对偏差RB的绝对值为0.71%,在相同样本量下该设计方案表现最好。在估计黄河口矛尾虾虎鱼等鱼类体长-体重关系参数时,应保证获得一定样本量的对参数估计具有较大影响的季节的生物学数据。  相似文献   

16.
The upstream migration of adult sockeye salmon (Oncorhynchus nerka) in the Horsefly River was monitored by a DIDSON imaging sonar during the dominant stock-cycle year 2005 using a systematic 20-min h−1 sampling scheme. We used a subset of these data collected between 16 and 29 September to investigate whether this sampling protocol was justified based on temporal variation in the salmon migration data. During post-processing, the 20-min sequence was split into two 10-min periods and the number of migrating salmon was counted separately. Cross- and autocorrelation analysis showed that estimates from the first and second 10-min samples were similar (r = 0.65) and variation between them (i.e., within the hour) was random, supporting the conclusion that systematic-hourly sampling is a defensible sampling design for acoustic enumeration when temporal variation in fish migration is unknown a priori. Using a simple benefit–cost model (statistical reliability of point estimates of salmon escapement–sampling effort), we recommend a minimum sampling effort of 10-min h−1 and a maximum effort of 20-min h−1 for projects using a systematic sampling scheme in which the goal is to estimate total upstream salmon escapement. An alternative sampling approach targets high-passage events such as diurnal peaks or periods when total daily upstream escapement exceeds 25 000 fish d−1, for increased sampling effort while reducing sampling effort during low-passage periods. This design will improve the statistical reliability of the resulting point estimates of upstream escapement relative to that achievable with a systematic effort with no overall change in total sampling effort over the course of the migration period.  相似文献   

17.
Strategic long‐term sampling programmes that deliver recreational catch, effort and species demographic data are required for the effective assessment and management of recreational fisheries and harvested organisms. This study used a spatially and temporally stratified observer programme to examine variation in the rates, quantities and lengths of retained and discarded catches of key species in a recreational charter fishery. Geographic region, but not season, significantly influenced catch rates of key demersal species, being driven by temporally persistent latitudinal clines in environmental conditions influencing species distributions. There was considerable trip‐to‐trip variation in catch rates that were attributed to localised differences in fishing operations, locations, environmental conditions and client preferences. Broad trends in retained and discarded catch rates were nevertheless, similar across different fishing effort standardisations (per‐trip, per‐hour, per‐client, per‐client/fished hour), demonstrating that the coarsest unit of effort could be used in fishery assessments. Discard rates of organisms were variable and driven by a combination of mandated legal lengths, individual client and operator preferences for particular species and sizes of organisms, and not due to attainment of catch quotas or high‐grading. This study has identified important fishery attributes that require consideration in assessing charter fisheries and stocks of recreational fish species.  相似文献   

18.
海洋捕捞渔业是中国海洋渔业的重要组成部分,产值核算是反映海洋捕捞渔业转型升级成效的重要方式。借助渔业统计指标数据,对2018年近海捕捞渔业和远洋渔业产品的平均单价进行了测算。结果显示:近海捕捞渔业产品平均单价为18.82元·kg^-1,广东的平均单价最低,仅为10.88元·kg^-1;远洋渔业产品平均单价为11.64元·kg^-1,河北的平均单价最低,仅为2.55元·kg^-1。通过对海洋捕捞渔业产量、产值统计方法进行梳理与案例分析,认为造成这种结果的可能原因包括:产值核算与结果公布的机构衔接不充分,产值核算过程中的产品价格种类不齐,海洋捕捞渔业专业及辅助性活动产值统计不足。提出加强统计数据发布前的沟通与协调,完善捕捞渔业产品与价格调查目录,完善海洋捕捞渔业专业及辅助性活动产值统计制度,理顺渔业二、三产业产值数据统计调查制度等建议,以期建立有效的评估方法,为评估海洋捕捞渔业绿色高质量发展成效提供参考。  相似文献   

19.
The adaptive cluster sampling method is widely applied in terrestrial systems; however, it is not suitable for fisheries surveys because of the high cost of unlimited sampling in practice. An adaptive approach is often used in fisheries surveys to allocate sampling effort, usually following a stratified random design. Development of an adaptive sampling method based on optimized sampling design (this design has been suggested by previous study for fishery-independent surveys) has been not yet carried out. An adaptive sampling method based on optimized sampling design using the criterion of minimization of the mean of the shortest distance (MMSD) in the first phase was constructed in this study and compared with five other sampling designs: simple random, stratified random, adaptive based on stratified sampling, systematic, and optimum design based on the MMSD criterion. This design performed neither the best nor the worst among the six sampling designs considered in this study, but its advantages were obvious when the sampling effort saved using this design was considered in the comparison. This method tends to be more flexible and find fish aggregations more precisely. It is based on a more objective sampling design in the first phase compared with other adaptive sampling designs based on stratified sampling designs. We suggest that this design be considered in developing fishery-independent survey programs.  相似文献   

20.
为查明采样强度对多种类渔业调查中资源量指数估计的影响,实验根据2013年8月、10月和2014年2月、5月黄河口渔业资源底拖网调查数据,选取短吻红舌鳎、方氏云鳚、矛尾虾虎鱼、枪乌贼、口虾蛄、日本蟳和小型鳀鲱鱼类为调查目标,利用计算机模拟方法,以相对估计误差(REE)、相对偏差(RB)、变异系数(CV)和准确度变化率(ACR)等为评价指标,研究了调查样本量对不同种类资源量指数估计的影响。结果显示,各种类资源量指数估计的REE、CV和ACR随断面数增加均逐渐降低并趋于稳定;除在断面数3减到1时,日本蟳、口虾蛄和方氏云鳚等个别种类RB绝对值增大外,其他RB不存在一致性的增大或减小趋势。研究表明,由于不同种类的分布存在时空差异,不同种类需要的调查断面数不同;当目标种类数量空间分布变异较小时,减少调查断面数对采样精确度影响较小,反之则需要更多调查断面数。对于多种类渔业资源调查,需要综合权衡各目标种类来确定最适调查断面数。  相似文献   

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