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1.
在渔业资源调查中，采样方案直接影响资源量估算的准确性，对采样方案进行优化可以提高调查数据的质量。基于2007年使用单拖网渔船在长江口——杭州湾及其邻近海域调查获得的数据，模拟出该海域三疣梭子蟹的资源数量及各季节的分布情况，作为“真值”，模拟计算不同采样方案调查获得的三疣梭子蟹资源量并与“真值”进行比较，评估不同方案的采样效果。本文利用计算机模拟了定点采样、简单随机采样、分层定点采样和分层随机采样四种采样方法，其中，定点采样和简单随机采样分别设置了9个、16个和24个采样站位，分层定点采样和分层随机采样设置了16个采样站位。三疣梭子蟹对拖网渔具的反应距离受年龄、季节和底质等条件的影响，因此，设置了1.5m，3m和5m三种反应距离。结果表明：分层采样设计优于不分层采样，简单随机采样优于定点采样。模拟结果的准确度随着采样站位数量的增加而提高，例如，定点采样方案中，9个站位时相对估算误差（REE）的最大值为163.43%，最小值为49.40%，而24个站位时REE的最大值和最小值分别是38.62%和4.15%。随着反应距离的增加，REE值和相对偏差的绝对值（RAB）逐渐降低。三疣梭子蟹的资源密集区和资源密度方差大的季节对模拟结果具有显著影响，因此，掌握该区域的资源密度情况或者进行预调查都能使采样设计方案更加合理。本研究可为底拖网渔具对三疣梭子蟹及其他物种的采样设计提供参考。 相似文献
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长江口中华鲟保护区海洋环境监测浮标站点的优化设计 总被引：1，自引：0，他引：1
长江口是众多洄游性鱼类重要的栖息场所,其复杂的环境条件影响着该水域水生生物的生长和繁殖过程。海洋环境监测浮标能够对诸多环境要素进行长期、连续、实时和大范围的监测,是现代海洋环境自动观测系统中的重要组成部分。为在长江口中华鲟自然保护区及其邻近水域组建合理有效的浮标监测网络,本研究基于海上实测调查数据,使用普通克里金法模拟了多种环境要素的空间分布,在此基础上比较了分层随机采样设计中不同分层方案和站点数量变化对监测效果的影响,结果显示:(1)盐度要素在层数为3的分层随机采样方法中采样精度更高,水温、溶解氧和化学需氧量要素在层数为2的采样设计中采样效果更好;(2)站点数越多,相对误差越集中并趋向于0,并当站点数多于30时,采样估测准确性逐渐趋于稳定;(3)各季节中,秋季盐度要素中层数为2的采样准确性更高;与其他3季以及总体相对误差结果相比,冬季化学需氧量要素的采样效果比其他3个季节要差。在今后长江口中华鲟自然保护区水域组建环境监测浮标网络时,建议采用3层的分层随机采样作为盐度监测的分层标准,且站点数量要大于50个;使用2层的分层随机采样作为其他多种水文环境要素监测的分层标准,且站点数量要大于30个。 相似文献
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渔业资源调查采样设计优化研究进展 总被引：3，自引：0，他引：3
渔业资源调查是指利用一定的采样设计,对渔业种群进行空间布点采样,以获取研究区域内鱼类时空分布以及生物学和生态学信息。但是大量的研究表明,不同的鱼类分布适合不同的采样设计,需要根据鱼类的分布特点和调查目标(种群丰度等)优化采样设计,保证数据的准确性和精度。近年来,相关的研究有很多,涉及不同采样设计的比较和应用以及影响数据质量因素的探究。作者着重介绍了定点采样、传统方法、适应性方法和基于地理统计学方法,叙述了计算机模拟及重采样技术在采样设计优化中的应用以及相对偏差、相对估计误差、设计效果和变异系数等评价采样设计性能的指标,同时对采样设计中需要注意的问题进行介绍,最后进行了总结并对未来的研究工作进行展望。 相似文献
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为解决声线跟踪精度与计算量之间的矛盾,在常梯度分层声线跟踪法的基础上,提出了一种适用于多波束测深的声线跟踪自适应分层方法,即利用Douglas-Peucker算法对原始声速剖面数据进行筛选分层。给出了不同阈值的分层结果,并对等间隔分层与自适应分层的声线跟踪结果进行了比较。实验结果表明,自适应分层法能够顾及到声速结构变化规律,有效提取声速变化节点,克服了人工选点的不足;在相同计算量情况下,自适应分层法声线跟踪精度要优于传统的等间隔分层法。本方法能够有效解决声线跟踪精度与计算量之间的矛盾,具有良好的工程应用价值。 相似文献
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在异质性潮间带湿地中通过野外采样估算大型底栖动物物种丰富度，面临的挑战是统计上精确性的要求与实际采样难度之间的矛盾。为了解决这个问题，本研究通过对采样策略整个过程的三个主要部分进行优化设计（优化采样方法、确定最少采样效力、探索最佳的采样间距），以期在中国长江河口典型的潮间带湿地中获得一个优化、有效和实用的大型底栖动物采样策略。本研究选取了横断面采样方法，并根据典型栖息地类型（潮滩、潮沟、盐沼植被）进行分层优化采样，这种类型的采样也称为横断面分层抽样。最少采样效力和最佳的采样间距由两个数学方法确定：蒙特·卡洛模拟和物种累积曲线。结果表明，根据典型栖息地类型优化的横断面分层采样，在大为减少采样效力和劳动力的情况下，还能采集样地81%物种，优化效果明显。同时，还分别确定了三类栖息地的最佳采样间隔和最小采样效力：在盐沼植被中，采样效力需要超过1.8 m2，最佳采样间隔为10 m；在潮滩中，最小采样效力2 m2，最佳采样间隔为10 m；在潮沟中，采样效力为3 m2，间隔为1 m。不同栖息地类型之间最小采样效力和最佳采样间隔的差异可能受到优势物种的迁移范围和栖息地的物理差异（例如潮汐水文、底泥、植被覆盖）的影响。本研究所采用的优化采样策略在平衡采样效力的情况下，为大型底栖动物丰富度估算提供良好的精度。此外，在河口湿地进行大型底栖动物调查之时，本研究的结论能提供采样策略参考。本研究所采用的采样策略设计注重采样的三个关键部分，具有良好的采样效果，可作为栖息地管理或生态系统评估的野外实地采样指南。 相似文献
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合理的调查采样设计可有效降低调查成本、获取高质量的调查数据。为深入理解采样频次对渔业生物物种丰富度估计的影响,本文基于2009—2010年胶州湾近岸水域逐月张网的渔业调查数据,采用计算机模拟重抽样方法,比较了简单随机抽样和两种分层随机抽样方案下不同采样频次在物种丰富度估计方面的表现。研究表明,三种采样方案下的物种丰富度的相对估计误差(REE)和相对偏差(RB)绝对值均随采样频次的增加而降低;简单随机抽样的REE值和RB值的绝对值略高于分层随机抽样;物种丰富度探测率达到90%、80%和70%时分别需要进行10、8和6次调查。对于胶州湾等温带半封闭海湾渔业生物多样性的调查,调查频次应尽可能覆盖全年以保证调查数据的代表性。 相似文献
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个别可转让配额(ITQ)制度和投入控制制度是海洋渔业资源管理的两种模式，其建构的逻辑起点和意图达成的管理目标是一致的。围绕控制捕捞努力量、恢复渔业资源、提高渔业经济效率、优化资源配置四个管理目标，通过将ITQ制度与投入控制制度依据激励相容原则进行比较后发现，ITQ制度由于具体设计方面的特殊性，内含更多的激励效应，基本能够把渔民个体追求利益最大化的动机与渔业资源的养护和可持续发展目标统一起来，激励相容度更高。与此同时，ITQ制度也存在总可捕量难以设定、配额分配的公平性、配额的过度集中与垄断、兼捕及优化渔获物的逆向选择、监管工作难度大等现实困境需要解决。针对这些困境，通过补充性的配套制度安排能够加以破解或缓解。由于ITQ制度在激励相容方面的比较优势，在条件成熟的情况下，对特定海域的特定鱼种实施ITQ制度可以作为投入控制制度的一种替代选择模式。 相似文献
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南海主要珊瑚礁水域软骨鱼类的组成与分布 总被引：1，自引：0，他引：1
利用1998年3~5月和1999年5~6月在西沙和南沙的12座珊瑚礁水域渔业资源专业调查资料以及1998年2月~1999年12月在南沙群岛水域进行的渔业资源监测调查资料,分析讨论了南海珊瑚礁水域软骨鱼类的组成与分布。专业调查结果:捕获软骨鱼类14属16种,渔获量计64尾2 844.1kg,优势种为大眼角鲨、鼬鲨、日本燕、侧条真鲨、灰六鳃鲨;监测调查表明南沙珊瑚礁水域的软骨鱼类在全年均可捕获,产量的变动主要与捕捞努力量相关。综合2种调查知:软骨鱼类在南海珊瑚礁水域总体分布范围较广,单鱼种在各个岛礁表现出一定的地域分布性;南海珊瑚礁区捕获软骨鱼类的主要作业方式为延绳钓和大型流刺网。 相似文献
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根据2019年4、5、8和10月在葫芦岛沿岸海域获取的4个航次的渔业资源调查数据，研究了葫芦岛沿岸海域渔业资源的群落结构和资源丰度的时空分布特征。结果表明：2019年调查共获得渔业资源种类42种，其中鱼类隶属于5目13科共21种，均属于硬骨鱼类，头足类4种，甲壳类17种。渔业资源优势种为矛尾虾虎鱼(Chaeturichthys stigmatias)、短吻红舌鳎(Cynoglossus joyneri)和口虾蛄(Oratosquilla oratoria)。全年渔业资源多样性指数(H′)、均匀度指数(J)和物种丰富度指数(D)平均值分别为1.96、0.62和1.01,多样性指数以10月最高，其次为5月和4月，8月最低。调查海域渔获种类组成主要为虾类和鱼类，头足类和蟹类所占比例较小。渔业资源丰度月变化明显，8月最大为27 772 g/h,其次10月为7 856 g/h, 4月和5月最小，分别为1 164 g/h和1 542 g/h。渔业资源丰度随月份不同呈现不同的空间变化，从春季到秋季，资源丰度高值呈现由北部沿岸向南部移动的特点。本研究旨在为葫芦岛近岸水域渔业资源的合理开发和保护提供科学... 相似文献
10.
针对执行水质监测任务过程中固定浮标监测站单点监测存在局限性、船载观测人员取样耗时耗力等问题,本文设计了一种搭载多点、分层自动采水取样装置的智能无人船水质监测系统,可实现目标水域的多点、分层连续水质数据测量及取样。该智能无人船具备基于快速随机树(Rapid Random Tree)算法的自主避障和快速路径规划功能,解决了现有无人船技术存在的多障碍自主路径规划难等问题。同时,本设计结合了ARM9控制芯片、M5310无线传输模块,通过可视化的显示界面和远程WEB访问的功能,大大提升了科研人员及时处理特殊情况便捷性。通过实验测试及比对分析,证明本设计具有智能高效、稳定可靠等优点,能够满足职能部门对于水质监测工作的需要。 相似文献
11.
Fixed-station sampling design was widely used in fishery-independent surveys because of its characteristics of convenient sampling station setting, but the non-probabilistic(fixed) nature made it more uncertainty of drawing inferences on population. The performance of fixed-station sampling design for multispecies survey has not been evaluated, and we are uncertain if the design could detect the temporal trends of different populations in multispecies fishery-independent survey. In this study, s... 相似文献
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《African Journal of Marine Science》2013,35(1):33-42
The South African abalone Haliotis midae resource is widely perceived as being under threat of over-exploitation as a result of increased poaching. In this paper, reservations are expressed about using catch per unit effort as the sole index of abundance when assessing this fishery, particularly because of the highly aggregatory behaviour of the species. A fishery-independent survey has been initiated and is designed to provide relative indices of abundance with CVs of about 25% in most of the zones for which Total Allowable Catchs (TACs) are set annually for this fishery. However, it will take several years before this relative index matures to a time-series long enough to provide a usable basis for management. Through a series of simple simulation models, it is shown that calibration of the survey to provide values of biomass in absolute terms would greatly enhance the value of the dataset. The models show that, if sufficient precision (CV 50% or less) could bc achieved in such a calibration exercise, the potential for management benefit is improved substantially, even when using a relatively simple management procedure to set TACs. This improvement results from an enhanced ability to detect resource declines or increases at an early stage, as well as from decreasing the time period until the survey index becomes useful. Furthermore, the paper demonstrates that basic modelling techniques could usefully indicate which forms of adaptive management experiments would improve ability to manage the resource, mainly through estimation of the level of precision that would be required from those experiments. The results of this study are particularly applicable to fishing zones for which there are insufficient other data to perform a standard stock assessment. 相似文献
14.
A.J. Hobday J.W. YoungC. Moeseneder J.M. Dambacher 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):734-745
Although many species in the pelagic ocean are widespread, they are not randomly distributed. These species may have associations with particular water masses or habitats, but to best understand patterns in the ocean, these habitats must be identified. Previous efforts have produced static or seasonal climatologies, which still represent smearing over habitats. The Eastern Tuna and Billfish Longline Fishery (ETBF) targets a range of high trophic level species in oceanic waters off eastern Australia. In this study, dynamic ocean habitats in the region were identified for each month based on cluster analysis of five oceanographic variables averaged at a monthly time scale and a spatial scale of 0.5° for the period 1995-2006. A total of seven persistent habitats were identified off eastern Australia with intra and interannual variation in size and location, indicating the importance of spatial and temporal variation in the dynamics of the region. The degree to which these dynamic habitats were distinguished was tested using (i) stable isotope analysis of top fish predators caught in the region and (ii) estimates of variation in estimated abundance generated from catch data from the fishery. More precise estimates (measured as lower total CV) of isotopic values from swordfish (Xiphias gladius), yellowfin tuna (Thunnus albacares) and albacore (Thunnus alalunga) were obtained for 4 of 6 isotope comparisons using the dynamic habitat groupings, which indicate that stratifying by pelagic habitat improved precision. Dynamic habitats produced more precise abundance estimates for 7 of 8 large pelagic species examined, with an average reduction in total CV of 19% compared to when abundance was estimated based on static habitat stratification. These findings could be used to guide development of effective monitoring strategies that can distinguish patterns due to environmental variation, and in the longer term, climate change. 相似文献
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At‐sea sampling is a common approach used by fisheries scientists to assess changes in fished populations. Traditional sampling programmes focus on short intensive sampling periods by fisheries personnel, although there has been a move to increase temporal sampling frequency within a fishing season by using harvesters. To determine the suitability of these two options, we compared the precision of estimates obtained for the American lobster (Homarus americanus) fishery in the southern Gulf of St. Lawrence, Canada. The sampling variance estimation for the mean catch‐per‐unit‐effort (CPUE) was based on a three‐stage sampling design with days as the primary unit, and buoy and trap as secondary and third stage units, respectively. Using the estimated variance components to predict and compare the variance of the mean CPUE for different at‐sea sampling designs, we show that it would be more efficient to sample a few traps (at least 3) every day for the entire fishing season than the traditional at‐sea sampling of the entire fishing gear twice or three times in a season by scientific personnel. Designing a harvester‐based at‐sea sampling programme could be an efficient approach for reducing costs while gathering essential fishery data, improving dialogue between the industry and scientists, and increasing harvesters’ participation in managing the resource. 相似文献
16.
Abstract. The interrelationships between the main phytobenthic groups of Chlorophyceae, Phaeophyceae, and Rhodophyceae around Milos Island, Central Aegean Sea, were studied using standard ecological and mathematical methods. The analysis was based on seasonal sampling of 114 different macrophytobenthic species.
The employed ecological indices revealed that the sampling areas located on the north, south, and east side of Milos Island show similar annual fluctuations in abundance and species diversity. The resemblance was particularly high between all stations in October-February, between south and east stations during May, and between north and east stations during July.
Additionally, an annual cycle of group interaction with regard to species diversity and abundance exists between the Chlorophyceae, Rhodophyceae, and Phaeophyceae. The Rhodophyceae are the most abundant and dominant group throughout the year, showing percentages in the samples higher than 70% in all sampling areas. 相似文献
The employed ecological indices revealed that the sampling areas located on the north, south, and east side of Milos Island show similar annual fluctuations in abundance and species diversity. The resemblance was particularly high between all stations in October-February, between south and east stations during May, and between north and east stations during July.
Additionally, an annual cycle of group interaction with regard to species diversity and abundance exists between the Chlorophyceae, Rhodophyceae, and Phaeophyceae. The Rhodophyceae are the most abundant and dominant group throughout the year, showing percentages in the samples higher than 70% in all sampling areas. 相似文献