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1.
Chang-Doo PARK Eui-Cheol JEONG Jong-Keun SHIN Heui-Chun AN Yasuzumi FUJIMORI 《Fisheries Science》2004,70(4):553-560
ABSTRACT: Fishing experiments were carried out in Yeongil Bay, Korea using an encircling gill net with four different mesh sizes and two different hanging ratios to measure the mesh selectivity for gizzard shad Konosirus punctatus . Twenty-six trials were conducted giving a total catch of 485 gizzard shad. The 'share each length's catch total' (SELECT) analysis with maximum likelihood method was used to fit the different functional models, the normal, lognormal, and bi-normal model, for a selectivity curve to the catch data. In addition, two cases in which the relative fishing intensity was either estimated or fixed were compared. The bi-normal model with the fixed relative fishing intensity was found to fit the data best. For the selectivity curve on the bi-normal model, the relative length (the ratio of fish length to mesh size) with the maximum efficiency was obtained as 3.70. From this, the focal fish lengths in the commercial encircling gill net, with mesh size ranging from 5.0 to 6.0 cm, were inferred to be 18.5–22.2 cm. 相似文献
2.
利用几何相似原理将传统的过滤性渔具选择性曲线转化为选择性曲面。运用选择性方程，并假设不同网目大小的渔具对相同尺寸渔获个体的渔获服从多项分布后，对过滤性渔具的网目选择性建立模型。使用极大似然估计法对模型进行拟合，同时，通过假设检验对模型进行简化。使用平行作业法试验条件下的张网渔具的黄鲫(Setipinrm taty)渔获数据进行模型拟合。结果显示，所建模型可以在没有对照网的情况下估算出各不同网目大小网囊的选择率，并同样适用于套网法试验条件下的选择性分析。模型的建立为今后进行过滤性渔具网目选择性试验方法改革提供了理论参考。通过与SELECT模型比较，认为模型使用选择性方程并区分渔获能力和捕捞努力量使得模型更具普遍性。 相似文献
3.
Iwona Psuty-Lipska Niels Madsen Bohdan Draganik Wies&#x;aw Blady 《Fisheries Research》2006,80(2-3):339-344
This paper presents the scientific basis for changes in the minimum mesh size in gill nets, from 28 to 30 mm, introduced by fishery management in Poland to limit the catch of undersized perch (those less than 17 cm total length). Experimental fishing with six different mesh sizes was performed in accordance with commercial fisheries practice. A bi-normal selection curve was fitted to the data by including the between-set variation in the model. The locations of the primary and secondary modes of the bi-normal curve on the transformed length scale (length/mesh) were estimated to be 6.95 and 7.41, respectively. The results indicated that a minimum mesh size in gill nets of 28 mm should be sufficient to ensure a low level of discards as well as protecting the interests of fishermen. 相似文献
4.
为了提高近海渔业资源养护型捕捞与管理技术,促进《全国海洋捕捞渔具目录》的实施,2014年10-11月在辽东湾进行了网目尺寸为40 mm、50 mm、60 mm的单片刺网、双重刺网和三重刺网以及生产对照网的选择性对比实验.结果显示,各种实验网的渔获种类数均在6-9种之间,优势种口虾蛄(Oratosquilla oratoria)的优势度随网目尺寸的增大而减小,但花鲈(Lateolabrax japonicas)的优势度随网目尺寸的增大而增大.同型试验网在不同网目尺寸条件下的渔获量有显著性差异,其中,60 mm试验网与40 mm同型试验网的单位捕捞努力量渔获量(CPUE)比较,单片刺网为800％,双重刺网为650％,三重刺网为500％;而异型试验网在网目尺寸相同条件下对渔获量的影响相对较小.试验网的组内渔获组成平均相似度分别为单片刺网59.24％,双重刺网62.63％,三重刺网66.51％;组间分别为71.44％、67.50％和70.58％;对组内和组间平均相似度贡献最高的种类均为口虾蛄和花鲈.随着网目尺寸的增大,各型试验网的渔获物幼鱼比例呈下降趋势. 相似文献
5.
为促进南海马鲛刺网渔业的可持续发展和渔业资源的合理利用,于2012年和2015年分别进行了马鲛流刺网渔获组成和选择性试验。运用相对重要性指数(IRI)评价刺网的渔获组成,并在SELECT模型(share each length catch total)的架构下,利用正态分布(Normal)和双峰分布(Bi-normal)概率方程计算刺网对康氏马鲛(Scomberomorus commersoni)的选择性;进一步结合康氏马鲛的最小可捕规格,探讨南海区马鲛流刺网的最小网目尺寸。结果表明,康氏马鲛是南海马鲛流刺网最重要的渔获种类,其2012年和2015年IRI值分别为9 472.00和14 363.02;调查试验共捕获康氏马鲛295尾,其中2012年康氏马鲛的众数叉长组为751~800 mm(占32.52%),2015年康氏马鲛的2个众数叉长组分别为501~550 mm和701~750 mm;正态分布模型估算的选择性众数相对叉长为6.961;双峰分布估算的2个众数相对叉长值分别为4.440和6.728;根据模型残差值的大小,认为双峰分布的拟合效果较好;将康氏马鲛可捕规格定为380 mm的前提下,建议南海马鲛流刺网的最小网目尺寸可暂定为120 mm。 相似文献
6.
刺网渔具选择性研究进展 总被引：8，自引：0，他引：8
刺网选择性研究是渔具选择性研究领域中的重要部分，其对于渔业管理、资源调查和评估等都是至关重要的。本文以刺网渔具的4种渔获方式为研究基点，通过对刺网渔具选择性特点的描述，介绍各种刺网渔具选择性曲线的表示方法。根据国外多年来对刺网渔具选择性研究方法的发展进程，对当前几种常用的选择性曲线间接估算方法（SELECT模型、同时估算选择性曲线和种群资源的方法以及同时估算A类和B类曲线的方法）的原理和运用现状进行详细介绍。对间接估算法中常用的假设条件（几何相似原理、相同渔获能力等）、估算方法的缺陷和相互之间的关系以及在进行刺网渔具选择性研究时所要关注的问题等进行了讨论，为今后深入开展刺网渔具选择性研究提供参考。 相似文献
7.
渔具对捕捞对象的年龄选择性对于渔业资源评估等工作是至关重要的,但相关研究较少。使用套网法对网囊网目尺寸分别为35 mm和45 mm的近海张网对黄鲫(Setipinna taty)和小黄鱼(Larimichthys polyactis)的年龄选择性进行分析。数据分析采用2种年龄选择性曲线模型:即估算网囊对个体体长选择性后根据个体生长方程换算和直接使用Logistic曲线代表年龄选择性曲线;通过对渔获体长分布和年龄分布数据的拟合,结果显示,2种年龄选择性曲线均能较好地拟合数据,网囊对黄鲫和小黄鱼的50%选择年龄t50和年龄选择范围SRt均随着网目尺寸的增加而增加,35 mm和45 mm网目尺寸的网囊对黄鲫的t50分别约为4月龄和8月龄,对小黄鱼的t50分别约为0.6龄和1.5龄,明显小于黄鲫和小黄鱼的推荐开捕年龄,反映出目前近海张网渔具网目过小,可能会对幼鱼资源产生不利的影响。 相似文献
8.
The present paper proposes a method for estimating the numerical curve of gear selectivity without the assumption of function of selectivity curve and estimating confidence intervals, using data of catch per unit effort at length for several nets of different mesh sizes obtained from fishing experiments. The paper assumes such geometric similarity as the selectivity is the same if the rate of fish length to mesh size is the same. The basic idea is due to a technique of numerical integration that uses the derivatives at various points. The natural logarithm of selectivity is expressed by an approximation equation using its cumulated derivatives. The values of derivatives at various lengths are calculated from the data. The confidence intervals are made from the bootstrap samples. The method was applied to the data of catch at length by mesh size of gill net for pink salmon Oncorhynchus gorbuscha . Data collection, modification and issues of the method are discussed. 相似文献
9.
为了解东莞生态园湿地水域群落结构特征,探讨2种类型刺网(沉网和浮网)及不同网目网片渔获物组成的差异性,实验利用多网目(1.0、1.25、1.6、2.0、2.5、3.1、3.9、4.8、5.8、7.0、8.6和11.0 cm)单层刺网对该湿地的鱼类进行了调查。研究期间共采集到13种鱼类,相对重要性指数显示,海南似和莫桑比克罗非鱼为优势种,前者密度最高(占84.8%),后者生物量居多(40.2%)。渔获物物种组成沉浮网间差异显著,但单位努力捕捞数量(NPUE)、单位努力捕获重量(BPUE)及物种数与沉浮网间均无显著差异;海南似的NPUE在2种类型刺网间无显著差异,但莫桑比克罗非鱼和尼罗罗非鱼的NPUE浮网显著低于沉网。12个网目网片的渔获物物种聚成2类,1.0～2.0 cm网目网片渔获物聚为1类,海南似为指示种;2.5～11.0 cm片的聚为另1类,莫桑比克罗非鱼和尼罗罗非鱼为指示种。渔获物大小结构聚为2类,1.0～3.9 cm网目网片渔获物聚为1类,4.8～11.0 cm网目网片的聚为另1类。随着网目大小增加,渔获物平均体长线性递增,NPUE呈幂函数式下降。研究表明,为对内陆水域鱼类群落... 相似文献
10.
为了提高近海渔业资源养护型捕捞与管理技术,促进《全国海洋捕捞渔具目录》的实施,2014年10—11月在辽东湾以口虾蛄为目标渔获,进行了网目尺寸为40、50、60mm的单片型刺网、双重型刺网、三重型刺网以及生产对照网的选择性对比试验,为确定渤海三重型刺网管理的过渡归属提供依据。结果显示,各试验网具的主要渔获种类基本相同,渔获优势种为口虾蛄和花鲈,随着网目尺寸的增大,各型刺网的口虾蛄相对重要性指数递减,而花鲈相对重要性指数则呈递增趋势。单片型刺网、双重型刺网和三重型刺网间的口虾蛄渔获量差异显著(P=0.04,P=0.66×10-6,P=0.029),口虾蛄渔获尾数占总渔获的比例呈现出按单片型刺网、双重型刺网、三重型刺网顺序增长的趋势。相同网目尺寸条件下,未达到可捕标准的口虾蛄渔获尾数呈现出按单片型刺网、双重型刺网、三重型刺网顺序递增的趋势,但其所占比例并无明显差别;相同型的刺网,随网目尺寸的增大未达到可捕标准口虾蛄的渔获比例递减。Gamma选择性模型曲线显示,当网目尺寸大于50mm时,单片型刺网、双重型刺网、三重型刺网的口虾蛄渔获优势体长均大于可捕标准,但是三重型刺网的渔获数量明显大于单片型刺网,且在渔业资源损害方面并无明显差别,因此,在目前渤海的口虾蛄渔业中,单片型刺网难以取代三重型刺网进行作业。 相似文献
11.
12.
Hae-Hoon Park Russell B. Millar Bong-Seong Bae Heui-Chun An Young Yull Chun Jae Hyeong Yang Sang Chul Yoon 《Fisheries Research》2011,107(1-3):196-200
In 2008, Korean flounder (Glyptocephalus stelleri) was designated by the Korean Ministry for Food, Agriculture, Forestry and Fisheries as a species for restoration in the coastal waters of Korea. However, there are currently no regulations regarding the minimum landed size of flounder, or the minimum legal mesh size used by the coastal gillnet and trammel net fisheries. Selectivity experiments for gillnets and trammel nets were conducted using commercial vessels in several areas off the eastern coast of Korea between October 2006 and June 2009. The selectivity analysis required an adaption of the SELECT method because trammel net mesh sizes were altered part-way through the experiment. Gillnet and trammel net selectivity was best described using a bi-modal selection curve. The two gears were found to have different selection curves for a given mesh size. The length of maximum retention was similar for the two gears, but the selection curve of the trammel net was substantially wider than that of the gillnet. For the largest size of mesh used in the commercial fishery (8.5 cm stretched), 50% relative retention was estimated to occur at a length of 20.4 cm for the trammel net, and 22.5 cm for the gillnet. In comparison, the length of 50% maturity for this species is approximately 26 cm. As there are currently no size restrictions on landings of Korean flounder, these results suggest that use of these gears may pose a serious threat to local stocks of this species. 相似文献
13.
套网法对张网渔具选择性的影响 总被引：6，自引：2，他引：6
套网法是一种比较常用的选择性研究试验方法,但是,使用套网法会对网囊网目选择性产生一定的影响.通过使用5种不同规格的方形网目网囊分别进行试验,比较两种不同的试验方法即套网法和平行作业法对张网渔具网囊网目选择性进行研究.结果显示,使用平行作业法估算的50%选择体长比使用套网法所得的大7.8%,选择范围比套网法的估算值小24.5%,选择性因素比套网法估算值大7.4%,但差异并不显著(P＞0.05).在张网渔具最适网目试验中,如果直接使用套网法的试验结果制定最小网目,那么这一尺寸会偏大,造成部分鱼类过多释放. 相似文献
14.
为提高近海渔业资源养护型捕捞与管理技术,促进《全国海洋捕捞渔具目录》的实施,2014年9—10月在黄海进行了网目尺寸为40、50、60 mm的单片型刺网、双重型刺网和三重型刺网以及生产对照网的选择性对比试验。试验结果表明,相同网目尺寸的各型试验网的渔获种类间呈中等相似或极相似;渔获优势种为高眼鲽、细纹狮子鱼、黄、小黄鱼和白姑鱼,不同试验网的渔获优势种不同。40、50、60 mm的三重型刺网的单位捕捞努力量渔获量分别为相同网目尺寸的单片型刺网单位捕捞努力量渔获量的187%、174%和146%,对应的经济效益分别为单片型刺网经济效益的133%、112%和184%,小黄鱼幼鱼比例分别为单片型刺网的162%、342%和122%,高眼鲽幼鱼比例分别为单片型刺网的108%、277%和100%。渔获结构显示,单片型刺网对小黄鱼、鲐鱼和白姑鱼等纺锤型鱼类的选择性优于三重型刺网,而三重型刺网对高眼鲽、黄鮟鱇的选择性具有明显优势。 相似文献
15.
Anne Gro Vea Salvanes 《Fisheries Research》1991,10(3-4):265-285
The present study analyses the selectivity for cod in two trammel-nets (three-wall nets) and one gillnet (single-wall net) used during an experimental cod fishery conducted monthly from october 1985 to December 1988 in a Norwegian fjord. It is part of a cod enhancement experiment conducted in the fjord. The three nets were grouped and utilized to sample the wild cod population. In addition, the gillnet and one trammel-net were utilized to sample a tagged group of cod with a known length composition. Relative selectivity curves were estimated indirectly for the two trammel-nets by comparing the catches of each length class within the length range 18–58 cm. Absolute selectivity curves were estimated directly for the gillnet and one trammel-net for the length range 15.0–22.0 cm. These were utilized to verify the indirectly estimated curves. The trammel-net selectivity curves obtained were used to provide an estimate for the true length-frequency distribution of cod in the fjord. Finally, it was tested whether a group of the three nets may be utilized as a unit effort to provide approximate random samples from the population. 相似文献
16.
南海北部马鲛流刺网渔获组成初步分析 总被引：3，自引：0，他引：3
为了明确南海北部马鲛（Scomberomorus）流刺网的渔获组成、主要种类的生物学特征、幼鱼比例等情况,2012年4月2113～24日在海南岛东北部渔场进行了调查研究,并对主要渔获种类的刺挂部位作了初步探讨。结果表明,马鲛流刺网的主要渔获种类为康氏马鲛（S．commersoni）、白b鲔（S．guttatus）和乌鲳（Formioniger）,其相对重要性指数（IRI）分别为10969．80、5502．49和1937．34;优势体长（叉长）组分别为701～800mm、501～600mm和231～250mm。建议尽快制定主要渔获种类的最佳开捕长度,进行渔具选择性试验,制定并出台最小网目尺寸等相关管理措施,以促进马鲛刺网渔业的可持续发展。 相似文献
17.
Estimation of basket trap selectivity for changeable nassa (Nassarius mutabilis) in the Adriatic Sea
Size selectivity of basket traps for changeable nassa (Nassarius mutabilis) was estimated through comparative fishing trials with traps varying in mesh size and net colour. Selectivity curves of two commercial (19 mm white twine and 19 mm black twine) and three experimental (23, 26 and 28 mm white twine) traps were estimated using SELECT method. In addition, theoretical size-selectivity curves were calculated from morphometric data using a simplified version of Sechin method.Differing from the opinion of fishermen, N. mutabilis did not show any preference for dark coloured twine. Retention curves estimated with SELECT method had a very sharp selectivity and well fitted catch data in all cases. Theoretical size-selectivity curves were very close to size-selectivity curves obtained from experimental data. The two types of curve were very similar in shape, although the theoretical ones were shifted towards larger size classes and showed a slightly steeper slope than SELECT curves. The mesh size commonly used by fishermen is not adequate for rationally exploiting the resource, as catches mainly included undersized specimens, whilst the 23 and 26 mm mesh sizes would represent a good compromise between reduced occurrence of undersized individuals and satisfactory yields of commercial product. 相似文献
18.
ABSTRACT: The size selectivity of a trammel net for herded oval squid Sepioteuthis lessoniana in Tateyama Bay, Chiba Prefecture, was estimated by comparison between the mantle length frequency distributions of oval squid caught by a trammel net and by a set net. The measured mesh sizes of the inner net of the trammel net and of the final section of the set net were 85.3 and 11.3 mm, respectively. In the trammel net fishery where oval squid are herded into the net, most of the oval squid are caught in the bag-shaped inner net. Hence, the logistic function was employed for the size selectivity curve of the trammel net. The 'share each length's catch total' (SELECT) model was implemented for the estimation of the selectivity curve. The size selectivity r ( l ) of the trammel net for the oval squid was expressed as a logistic function of the mantle length l : r ( l ) = exp(−18.57 + 0.88 l )/[1 + exp(−18.57 + 0.88 l )]. From these logistic parameter estimates, the 50% selection mantle length and selection range ( L 75 – L 25 ) were calculated as 21.07 and 2.49 cm, respectively. The selection probability of oval squid whose mantle girth was equivalent to the mesh perimeter of the inner net was 0.09. Accordingly, oval squid of a girth smaller than the mesh perimeter were likely to pass through the mesh to escape from the net. 相似文献
19.
ABSTRACT: To estimate fishing gear selectivity of clam dredges from data of paired-gear tests in the SELECT analysis process, this paper presents a statistical model of the probability of a clam coming into contact with the dredge teeth and size-selectivity of the control gear. The net-mouth available selectivity is defined as the product of the probability of a clam contacting the dredge teeth and size-selectivity induced by tooth spacing. The model based on the SELECT analysis was tested by using data generated by virtual paired-gear test in which the control dredge of the smallest tooth spacing is assumed to be size-selective. No clear difference in shell length distribution between dredges of different tooth spacings was found in the simulation when the contact probability was small. The plots of proportion of clams caught in the test dredge to the total catch number of clams were U-shaped, and the model fitted the data well. For each simulation consisting of 500 replications, the sample mean and mean square error of each parameter were obtained to evaluate the performance of estimation by comparing with the true value. Parameters were properly estimated with the model. 相似文献
20.
不断壮大的东海近海笼壶渔业对三疣梭子蟹（Portunus trituberculatus）等甲壳类资源造成了巨大的压力,实施养护幼蟹的管理措施已成为渔业管理者和生产者的共同呼声。本研究通过海上对比试验,分析了放大网目尺寸对蟹笼渔获效率的影响,运用SELECT模型估算了蟹笼对三疣梭子蟹的尺寸选择性,结合混合影响模型探讨了作业时间和可捕群体对选择性分析的影响。结果显示,对照蟹笼（网目尺寸32.0 mm）与试验蟹笼（网目尺寸分别为52.3 mm和59.7 mm）的三疣梭子蟹渔获甲宽分布存在显著性差异;SELECT模型拟合结果显示试验蟹笼与对照蟹笼的相对作业强度无显著性差异,网目尺寸分别为52.3 mm和59.7 mm的试验蟹笼对三疣梭子蟹的50%选择甲宽（CW50）分别为86.9 mm和90.9 mm,选择范围分别为15.9 mm和9.2 mm。试验蟹笼的CW50远未达到浙江省等当前的最小可捕尺寸规定,表明蟹笼渔业中仅依靠放大网目尺寸可能难以实现幼蟹的有效释放。结果分析显示,在此次试验中作业时间和可捕群体的数量对蟹笼的选择性没有显著性影响。 相似文献