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1.
根据ｒ－选择和ｋ－选择的典型特征以及通过渐近体长（Ｌ∞）、渐近体重（Ｗ∞）、生长系数（Ｋ）、初次性成熟年龄（Ｔｍ）、最大年龄（Ｔｍａｘ）、瞬时死亡率（Ｍ）和种群繁殖力（ＰＦ）等七个生态学参数值分析，可以判断３种鲟鱼类种群为典型ｋ－选择。应用平衡产量模式计算改变瞬时捕捞死亡率（Ｆ）和渔业补充年龄（Ｔｃ）时的产量变化，同样证实３种鲟科鱼类为典型的Ｋ型种群。作为渔业管理对策是严格控制捕捞强度，以保护渔业资源。 相似文献
2.
研究了中华鲟、达氏鳇、施氏鲟、青鱼、草鱼、鲢、鳙、鲤、赤眼鳟、大眼鳜、鳜、黄尾密鲴、银鲴、花、、团头鲂、尖头塘鳢、鲫等19种淡水鱼类的生态参数（L∞、W∞、K、Tm、Tmax、M、PF）和生活史类型。3种鲟鱼类属k-选择,青鱼、草鱼、鲢、鳙偏向r-选择,其它12种鱼类属r-选择。种群繁殖力PF的数值大体上可反映出某种鱼类的生活史类型,运用Beverton－Holt平衡产量模式估算表明,只有合理控制捕捞强度和起捕年龄,既能保护资源,又能获得较好的经济效益。 相似文献
3.
19种淡水鱼类的生活史类型研究 总被引：4，自引：0，他引：4
研究了中华鲟,达氏鳇,施氏鲟,青鱼,草鱼,鲢,镛,鲤,赤眼鳟,大眼鳜,鳜,黄尾密鲴,银鲴,花Ｇｕ,鳊,团头鲂,尖头塘鳢,鲫等１９种淡水鱼类的生态参数（Ｌ∞,Ｗ∞,Ｋ,Ｔｍ,Ｔｍａｘ,Ｍ,ＰＦ）和生活史类型。３种鲟鱼类属ｋ－选择,青鱼,草鱼,鲢,镛偏向ｒ－选择。其它１２种鱼类属ｒ－选择。种群繁殖力ＰＦ的数值大体上可反映出某种鱼类的生活史类型,运用Ｂｅｒｅｒｔｏｎ－Ｈｏｌｔ平衡产量模式估算表明,只有合 相似文献
4.
高精度渔业捕捞强度数据是开展捕捞限额管理的前提与关键,也是海洋渔业资源可持续发展的重要保障。因此,本文以挖掘海洋渔业捕捞强度空间特征为出发点,选用2018年2、4、9和11月典型季节的中国籍6364艘渔船1.8亿条高时空粒度AIS数据。运用专家知识经验、空间统计及数据挖掘分析方法,以广西南岸北部湾渔场、广东沿岸和环海南岛周边海域为研究区域,对渔业捕捞强度空间特征展开了细致的挖掘与分析。结果表明：① 广东、广西两省（以下简称“两广”）沿岸海域渔业高强度捕捞主要呈现“团块”向外扩张汇聚成“条带”或“更大团块”的特征,而环海南岛周边主要呈现“团块状”特征;② 受渔业从业人员、渔业作业船舶数量、海洋渔场及海域环境影响,“两广”沿岸近海海域捕捞强度明显高于环海南岛周边海域; ③ 高强度捕捞区域主要集中于近岸30~50 km范围内,且近海捕捞强度高于远海区域,归因于研究区内中小型作业渔船占比较高,达50.9%;④ 渔业捕捞活动受农历传统春节及休渔期等政策因素的影响,春节期间的渔业捕捞强度是所选数据覆盖时间范围中最低的,并且休渔期后（9月）渔业捕捞强度明显高于休渔期前（4月）;⑤ 研究区海岸附近的大型渔港对近岸海域的高强度捕捞具有一定的辐射带动效应。本研究通过对高时空粒度的AIS数据进行处理、分析及深度挖掘,可为近岸海洋渔业捕捞强度探析提供重要数据支撑,服务于海洋渔业可持续发展。 相似文献
5.
测定从东海区渔轮拖网渔获中取样的２９９尾绿鳍马面Ｔｕｎ的全长和体重，用其脊椎骨的第３节椎体作为观察和测定年轮的材料，测出各年龄鱼的年轮轮径及椎体半径，算出各年龄鱼的平均逆算全长，结合全长与体重之间的关系求出生长参数，分析全长、体重生长情况，再根据绿鳍马面Ｔｕｎ的自然死亡系数Ｍ＝０．２５７和１９９２年的捕捞死亡系数Ｆ＝１．３１９，用Ｂ－Ｈ模型进行资源评析，评估资源利用程度及最佳利用方案。结果表明：东海绿鳍马面Ｔｕｎ资源已过度开发，应采取降低捕捞强度、控制网目尺寸、将开捕年龄推迟为３ａ（对应全长２２４ｍｍ、体长１９０ｍｍ）等措施来保护其资源。 相似文献
6.
辽宁省位于华北地台北缘，其地质构造演化主要经历了地台基底形成（Ａｒ－Ｐｔ１）、盖层沉积（Ｐｔ２－Ｔ２）、地台活化（Ｔ３以后）三个阶段。按成矿物质来源、成矿环境、成矿作用、矿点矿化点空间分布规律及物化探异常特征，辽宁省可划分出朝阳县小塔子—北票迷力营子、义县红石砬子—刘龙台、葫芦岛市水泉、建昌县温杖子、凌源市柏杖子、阜新县地宫—建设、浑南、浑北、盖县猫岭、辽阳田家围子—凤城弟兄山及丹东市沿江等１２个金的主要矿化集中区。辽宁省今后的地质勘查工作应注意以下几点：（１）要更新找矿观念，注意寻找新类型和大型超大型矿床；（２）按区域成矿条件，选好找矿重点突破区；（３）精确地认识和了解已知矿床，坚持就矿找矿；（４）坚持“五统一”的部署原则，利用地质、地球物理及地球化学方法进行综合找矿。 相似文献
7.
康庄子组Ｒｂ－Ｓｒ测年为１５６５±１１０Ｍａ和４８９±７３Ｍａ。前者与华北地层区内相邻地层在年龄上衔接，有利于区域地层划分与对比；后者同关门山铅锌矿床两阶段铅上交点年龄相近，恰佐证关门山铅锌矿床矿化发生的时间。１７９６±７ＭａＳｍ－Ｎｂ等时线年龄，１５６５±１１０ＭａＲｂ－Ｓｒ等时线年龄和１４０２±２１１ＭａＲＬ－Ｓｒ等时线年龄在地层上是衔接的，对区域地层划分与对比具有重要意义。 相似文献
8.
牛塘界花岗岩体的时代，以往曾定为华力西期。通过研究岩体的地质特征、岩性特征、稀土配分、钻石晶体标型、同位素年龄资料，结合区域对比，认为其时代应为加里东（中）期。以往所用的Ｒｂ－Ｓｒ全岩等时线年龄２８９Ｍａ，因岩石强烈蚀变，不能作为衡量岩体结晶年龄的尺度。研究表明，锆石Ｕ－Ｔｈ－Ｐｂ四个不一致年龄中，只有￣（２０７）Ｐｂ／￣（２０６）Ｐｂ比值计算的年龄，最接近岩体的结晶年龄。牛塘界岩体锆石￣（２０７）Ｐｂ／￣（２０６）Ｐｂ年龄为４６０Ｍａ，形成于中奥陶世，时代为加里东（中）期。 相似文献
9.
东海区鲳鱼资源利用现状分析 总被引：7，自引：0，他引：7
对东海区鲳鱼近年群体组成变化及银鲳生物学特性变化来分析目前鲳鱼资源利用状况，结果表明：一方面，虽然近年鲳鱼产量大幅增加，但其平均体重、优势叉长组成及年龄组成均出现明显下降，资源状况日益恶化；另一方面，１龄鱼已占渔获的９３．６８％，目前捕捞现行点开捕年龄ｔｃ＝１和捕捞死亡系数Ｆ＝２．５１，单位补充量繁殖力相对百分比Ｐ〈１．９％，单位补充量渔获量为７０ｇ／尾，均显示已处于严重的生物学型捕捞过度，建议渔 相似文献
10.
沈阳市东南部滑石台山附近太古代花岗岩基底中零星分布的超镁铁质岩地质体，经同位素测年，Ｒｂ／Ｓｒ表面年龄４３７０Ｍａ，全岩Ｒｂ／Ｓｒ等时线年龄４６９２±１８４Ｍａ，全岩Ｐｂ／Ｐｂ等时线年龄４５３５±￣（１０８）＿（１１７）Ｍａ。因此，作者认为滑石台山、馒首山、金顶山等地的超镁铁质岩是陨落成因，陨落地质作用发生在１８─１９亿年前。 相似文献
11.
船舶自动识别系统(Automatic Identification System, AIS)不仅是海上交通监管的有效工具,也为研究海上交通运输及其相关产业活动特征提供了一种良好的数据源。基于海上渔船AIS数据,本研究利用高斯混合模型(Gaussian Mixed Model,GMM)识别渔船捕捞活动状态,提出一种将核密度估计(Kernel Density Estimation,KDE)与热点分析(Hot Spot Analysis, HSA)相融合用于渔船捕捞活动聚集区提取的方法。结果显示：与单一KDE或HSA方法相比,二者相融合的方法将KDE的距离衰减效应与HSA统计指数相结合,在渔船捕捞活动聚集区提取中的应用效果较好、效率较高;采用该融合方法,基于2018年9—12月AIS数据,实现对渤海海峡周边海域渔船捕捞活动聚集区的提取,发现不同月份,渔船捕捞活动聚集区的分布范围和空间形态特征具有一定差异性,烟威近岸海域和渤海海峡是主要的捕捞活动聚集区,其结果可为该海域捕捞活动管理和海洋生态保护提供技术方法和决策支持。 相似文献
12.
东海中部夏季鱼类群落结构及其多样性分析 总被引：2，自引：0，他引：2
根据2008年8月东海区主要渔场重要渔业资源调查资料,分析东海中部鱼类的种类组成、区系特征、多样性等群落结构特征。结果表明:共调查捕获鱼类88种,其中暖水种59种,占67.0%;暖温种29种,占33.0%。相对重要性指数(IRI)值大于500的优势种鱼类共有5种,分别为带鱼、刺鲳、小黄鱼、六斑刺鲀和鳄齿鱼;种类丰富度指数变动范围为0.10～2.31,平均为0.88;Shannon-Wiener多样度指数变动范围为0.01～1.86,平均为0.87;种类均匀度指数变动范围为0.01～0.92,平均为0.41;东海中部夏季鱼类多样性指数与往年相比有下降的趋势。 相似文献
13.
There are 3048 species offish occurring in the China Seas (CS), of which at least 2321 species are found in the South China Sea (SCS), belonging to 35 orders, 236 families and 822 genera. The fish species diversity is analyzed in this paper based on biogeography, biostatisties, fishing methods, etc. It is found that the regional environment, especially biological factors, plays an important role in the distribution of faunas, and there are two fish faunas in the SCS, one in the north and another in the center and south. This regional division is of value for sustainable fishery production and efficient management of fishery resources. 相似文献
14.
The status of fishery stocks in the coastal waters of China is far from ideal, mainly due to climate change and the impacts
of human activities (e.g., pollution and overfishing). Thus, the restoration and protection of fishery resources have become
critical and complex. The stability and balanced structure of the fish community is a basic foundation for the protection
of fishery resources. Based on data collected from bottom trawls by the R/V Beidou in continental shelf of the East China Sea in November 2006 and February 2007, changes in the composition and diversity of
fish species and functional groups were analyzed. The research area was divided into offshore waters and inshore waters by
the two-way indicator species analysis (TWIA). The results showed that the dominant species were different between offshore
waters and inshore waters and also varied with the survey time. The most abundant family was Sciaenidae and Teraponidae in
November 2006, Sciaenidae, Engraulidae and Triglidae were most abundant in February 2007. The species belonged mainly to mobile
piscivores (G6), benthivores/piscivores (G4), benthivores (G3) and planktivores (G1), and the dominant species in November
2006 were commercial species (e.g. Larimichthys polyactis and Trichiurus japonicus), but small-sized species were dominant in February 2007 (e.g., Harpadon nehereus, Benthosema pterotum, Champsodon capensis, and Acropoma japonicum). The species diversity showed a similar trend as the functional group diversity. Stations with higher diversity were mainly
distributed in inshore waters in February 2007, whereas higher diversity was found in offshore waters in November 2006. The
highest biomass and species number were found in G6 group, followed by the G4, G5 and G1 groups. The distribution of the number
of individuals of each functional group showed the opposite trend as that of the biomass distribution. In addition, the size
spectra were mainly concentrated around 3–29 cm, and the individual number of fish species gradually decreased with the increase
in body size, but the relative biomass showed a moderate fluctuation in each size class. These changes showed that species
with faster growth rate and earlier maturity age became dominant in continental shelf of the East China Sea. So the variations
in biological characteristics of fish should be fully considered in maintaining sustainable utilization of fishery resource. 相似文献
15.
Diatoms are widely used to study past and present changes in the marine environment. Unimodal models are appropriate for exploring the relationship between environmental properties in Chinese inshore waters and fossil diatom species derived from modem surface sediments. The best-fit relationships between two multivariate datasets （diatom species and environmental variables） were identified using canonical correspondence analysis （CCA）, which is a constrained ordination technique. The absolute abundance of diatoms in the Chinese inshore waters ranged from 500 to 48 000 valves/g, and the average absolute abundance of all the 29 sites was l l 300 valves/g. 153 species and varieties of diatoms belonging to 42 genera in all were identified in the Chinese inshore waters. There were 28 dominant diatom species in all. According to the absolute abundance of the dominant species and the spatial distribution of the currents from the Chinese inshore waters, 12 diatom assemblages were distinguished from north to south, which reflected the different oceanographic conditions at the regional scale. Of the eight environmental variables considered, the most important environmental variable is winter sea surface salinity （WSS）, which was also the only environmental variable with statistical significance. Therefore, it may be used to establish a transfer functions for the Chinese inshore waters in future paleoclimate studies. 相似文献
16.
Over the past few decades, extreme changes have occurred in the characters of exploited fish populations. The majority of these changes have affected the growth traits of fish life history, which include a smaller size-at-age, an earlier age-at-maturation and among others. Currently, the causes of these life history traits changes still require systematic analyses and empirical studies. The explanations that have been cited are merely expressed in terms of fish phenotypic adaptation. It has been claimed that the original traits of fish can be recovered once the intensity of exploitation of the fish is controlled. Sustained environmental and fishing pressure will change the life history traits of most fish species, so the fish individual’s traits are still in small size-at-age and at earlier age-at-maturation in exploited fish populations. In this paper, we expressed our view of points that fishing gear has imposed selectiv-ity on fish populations and individuals as various other environmental factors have done and such changes are unrecoverable. Ac-cording to the existing tend of exploited fish individual’s life history traits, we suggested further researches in this field and provided better methods of fishery management and thereby fishery resources protection than those available early. 相似文献
17.
广西防城沿海鱼类初步调查有115种,隶属于14目63科91属。软骨鱼类有2目3科4属5种,占总数的4.3％。硬骨鱼类有12目60科87属110种,占总数的95.7％,其中鲈形目鱼类占优势,有68种。暧水性鱼类99种,占总数的86％;暧温性鱼类16种,占总数的14％,无冷温性鱼类。 相似文献
18.
Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea 总被引：3，自引：0，他引：3
Length-frequency data of eight commercial fish species in the Beibu Gulf (Golf of Tonkin), northern South China Sea, were collected during 2006-2007. Length-weight relationships and growth and mortality parameters were analyzed using FiSAT II software. Five species had isometric growth, two species had negative allometric growth, and one species had positive allometric growth. Overall, the exploitation rates of the eight species were lower in 2006-2007 than in 1997-1999: for four species (Saurida tumbil, Saurida undosquamis, Argyrosomus macrocephalus, and Nemipterus virgatus) it was lower in 2006-2007 than in 1997-1999, for two species (Parargyrops edita and Trichiurus haumela) it remained the same, and for the other two species (Trachurus japonicus and Decapterus maruadsi) it was higher in 2006-2007 than in 1997-1999. The exploitation rates might have declined because of the decline in fishing intensity caused by high crude oil prices. The optimum exploitation rate, estimated using Beverton-Holt dynamic pool models, indicated that although fishes in the Beibu Gulf could sustain high exploitation rates, the under-size fishes at first capture resulted in low yields. To increase the yield per recruitment, it is more effective to increase the size at first capture than to control fishing effort. 相似文献
19.
通过对东海区鲳鱼近年群体组成变化及银鲳生物学特性变化来分析目前鲳鱼资源利用状况,结果表明：一方面,虽然近年鲳鱼产量大幅增加,但其平均体重、优势叉长组成及年龄组成均出现明显下降,资源状况日益恶化；另一方面,1龄鱼已占渔获的93．68％,目前捕捞现行点开捕年龄tc=1和捕捞死亡系数F＝2．51,单位补充量繁殖力相对百分比P＜1．9％,单位补充量渔获量(Yw／R)为70g／尾,均显示已处于严重的生物学型捕捞过度．建议渔业管理部门大力削减作业渔船约50％,严格控制捕捞强度,逐步推迟开捕年龄至3龄以上,使鲳鱼资源真正能够永续利用。 相似文献
20.
李仲辉 《广东海洋大学学报》2001,(4)
对南海产的鲻和尖头的骨骼系统作了比较观察 ,结果表明 :两种鱼脑颅都较宽且扁 ;其鼻骨、围眶骨、翼耳骨、上耳骨 ,咽颅中的前上颌骨、上颌骨、腭骨、中翼骨、后翼骨、尾舌骨、下咽骨 ,肩带骨中的主后颞骨、后颞骨、上匙骨、匙骨 ,以及腰带骨等特征区别明显 ,其中某些特征可作为属间或种间的鉴别依据 相似文献