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鱼类生殖力的研究，由于计数卵量方法上有了很大的改进，因而已逐渐成为鱼类生态和渔业资源研究上的一个常规观测项目。
生殖力的变动，经常被用来作为判断补充与资源状况的指标之一。我国从50年代初就开展了这方面的研究。例如，在我国烟台外海鲐鱼资源的研究中曾指出，1954-1957年间，随着鲐鱼资源的逐年下降，生殖力不仅表现出明显的提高现象，而且与鲐鱼的生长有关。
本文是从所积累的大黄鱼Pseudosciaena crocea (Richardson)生殖力研究资料中，选择1959年5-6月间，同期分别在两个不同产卵场上所收集的资料，对其个体生殖力和种群生殖力的差值进行比较分析的结果。说明生活于不同水域中的种内不同种群，其生殖力调节方式也是不同的。这两个种群分属于两个地理种群，浙江近海岱衢洋春季生殖种群属于大黄鱼分布区北部的岱衢族；福建近海官井洋春季生殖种群属于大黄鱼分布区中部的闽-粤东族。此外，文中还以这两个种群为例，对表示种群生殖力的某几个方法作了比较分析。 相似文献
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辽东湾北部海域沉积物重金属环境质量和污染演化 总被引：6，自引：0，他引：6
基于取自辽东湾北部海域表层沉积物和岩心样品,利用XRF等方法对沉积物中的重金属含量进行系统的测定,结合137 Cs、210Pb年代测定,分析了研究区表层沉积物中重金属分布特征、环境质量状态以及重金属污染历史。结果表明:辽东湾表层沉积物重金属As、Cd、Cr、Cu、Pb、Zn、Hg含量高值区主要分布在葫芦岛附近海域,并且呈现由近岸向远岸递减的趋势;辽东湾海域部分站位表层沉积物已经受到重金属污染,轻度和重度污染率为34.5%,清洁率为65.5%,重度污染站位集中在葫芦岛附近海域;辽东湾沉积物中重金属污染大致出现在1975年,于1997年达到最大,随后,重金属污染开始明显减少。辽东湾沉积物中重金属分布及演化特征与沿海社会经济发展和国家环境保护政策有着密切的联系。 相似文献
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基于有限体积法的MIKE3Flow Model模型,考虑渤海沿岸15条主要河流径流输入,在对渤海盐度进行数值模拟的基础上,重点模拟了辽东湾顶部的盐度分布。模拟结果显示:辽东湾顶部盐度从4月开始在辽河口附近海域出现盐度低于27的低盐区,9月辽东湾顶部低盐区面积达到一年之中最大,面积约为2887km2。辽东湾顶部大辽河、辽河、大凌河、小凌河4条河流对该低盐区的贡献依次减小。大辽河和辽河径流对辽东湾顶部低盐区的影响表现在,不仅可以改变低盐区的出现及消退时间,也能够改变低盐区的分布范围。 相似文献
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辽东湾浮游动物多样性及其与海洋环境因子的关系 总被引：5，自引：0，他引：5
以2005年7～9月辽东湾浮游动物的调查数据为主,并结合以往的调查数据对浮游动物的种群结构、分布特征、多样性指数的变化及其与海洋环境因子的关系进行了分析。结果表明,辽东湾浮游动物个体数量主要集中在北部海区,而其生物多样性与均匀度指数却明显低于西部和东南部海区,说明该海区水体、生态环境、生物群落不如西部和东南部海区稳定、成熟。浮游动物多样性主要受透明度(rH′=0.599r0.01;rE=0.322r0.05,n=40)、水温(rH′=0.469r0.01,rE=0.432r0.01,n=40)、COD(rH′=-0.389r0.05;rE=-0.217r0.05,n=40)、W(rH′=-0.461r0.01;rE=-0.417r0.01,n=40)、物种数(rH′=0.835r0.01;rE=0.653r0.01,n=40)影响较大。 相似文献
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东海马鲛鱼(Scomberomorus Niphonius)的种群动态易受海洋环境条件的影响,在其资源评估和管理中需要考虑海洋环境条件的作用。假设马鲛鱼产卵场最适海表温度10～19℃(Suitable SST,Tsui)范围会影响种群环境容纳量(K),因此分别使用产卵季3月最适表温范围比值(Tsui-Mar)、4月最适表温范围比值(Tsui-Apr)和3、4月份最适表温范围比值的平均值(Tsui-Ave)作为剩余产量模型的环境因子,构建三种基于环境因子的剩余产量模型(environmentally dependent surplus production,EDSP),分别为Tsui-MarEDSP、Tsui-Apr-EDSP和Tsui-Ave-EDSP,利用贝叶斯估计模型参数,结果显示Tsui-Mar、Tsui-Apr、Tsui-Ave三个基于环境因子的EDSP模型偏差信息标准(deviance information criterion,DIC)值小于传统的剩余产量模型的DIC值,其中Tsui-Ave-EDSP模型DIC值最小,精度最高,估计的最大可持续产量(maximum sustainable yield,MSY)的范围为8.125×106～8.371×106 t,资源量(biomass)范围是1.429×106～1.455×106 t,从1994年到2015年,马鲛鱼的捕捞死亡率远低于目标死亡率(Ftar)和MSY水平捕捞死亡率(FMSY),种群资源量高于MSY水平资源量(BMSY)。东海马鲛鱼没有被过度捕捞或未发生过度捕捞,基于EDSP模型中的管理参考点更为保守,建议日后东海马鲛鱼的种群评估和管理应考虑产卵场环境条件。 相似文献
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舟山水域的三角藤壶Balanus trigonus Darwin对基物无明显的选择性。它主要分布在远岸盐度大于30的水域,风浪作用较小的湾(天山)处数量最大。在垂向上,以15～20m水层数量最大。种群结构因时间、地点而异。枸杞的三角藤壶在污损生物群落中占有重要地位,夏季沿岸区的生物量占污损生物生物总量的98.2％。本季,特别是7、8月份是三角藤壶防除的关键时期。本文还讨论了三角藤壶种群的生长参数和死亡率及其与环境因素的关系。 相似文献
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在渔业资源评价和渔业生产中,常用的与资源量有关的名词术语有以下几个。 资源量(abundance,一般译为丰度——编者注),在文献报告中或在讨论会上应用,是瞬时资源量(instantaneous abundance)的简称。它指的是在特定海域某时间开始时的鱼类种群数量。例如,1980年辽东湾春汛毛虾资源量,它指的是1980年春汛开捕时的资源数量。用尾数或用重量单位均可,当用 相似文献
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文章根据２００２年６—９ 月在浮山湾进行浮游动物的调查,分析了浮山湾浮游动物的种类变化。结果表明：６月,浮游动物２９ 种;７ 月,浮游动物３３ 种;８ 月,浮游动物３１种;９月,浮游动物３１种。这个海域对于浮游动物种类的容量保持稳定,浮游动物种类结构在７月发生比较大的更替变化,出现和消失的物种在每个月的变化基本保持动态平衡。同时,保持不变的浮游动物种类占有浮游动物种类总数的５１％～５８％。因此,浮山湾海域的浮游动物种类结构保持了更替的稳定,为把浮游动物作为饵料的上一级动物提供了稳定的食物来源。 相似文献
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桑沟湾是荣成市水产养殖的主要水域,养殖面积达8万亩,年养殖产量10多万吨,分别占全市养殖总面积和养殖总产量的30％左右,在荣成市养殖业中占有举足轻重的地位。但进入90年代以来,该湾的主要养殖品种——海带出现了藻体腐烂、出成率低,扇贝出现了个体小、生长周期长、出柱率低、死亡率高等一系列问题。为解决这些问题,市海洋与水产局组织科研部门对桑沟湾的养殖情况进行了全面系 相似文献
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The influence of solar activity on the Earth’s global surface temperature (GST) was quantified. The method for estimation of the Granger causality was used, with analysis of the improvement of the prediction of one process by using data from another process as compared to autoprediction. Two versions of reconstructions of the solar flux variations associated with solar activity were used, according to Hoyt et al. [1997] for 1680–1992 (data H) and according to Lean et al. [2005] for 1610–2005 (data L). In general, the estimation results for the two reconstructions are reasonably well consistent. A significant influence of solar activity on GST with a positive sign was found for two periods, from the late 19th century to the late 1930s and from the latter half of the 1940s to the early 1990s, with no inertia or time delay. In these periods, up to 8 and 25% of the variance of the GST change, respectively, can be attributed to solar activity variations. The solar influence increased in the 1980s to the early 1990s according to data H and began to decrease in the latter half of the 1980s according to data L. 相似文献
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《Marine Policy》1999,23(3):227-241
Origins and organization of New Bedford financial settlement houses are examined. Settlement houses are an important part of the extensive fishing community and have made significant historic contributions. Economic, political and social factors leading to the development of formal settlement houses in New Bedford are traced and the contemporary organization and responsibilities of settlement houses are investigated. Settlement houses and fishing routines were observed from 1986 to 1998. Interviews of the settler/owners of the five largest settlement houses in New Bedford and early settlers and fishermen from the 1930s and 1940s were conducted. Financial settlers helped bring order and increased trust to financial settlements that, prior to the 1930s, had largely been conducted in cash and based on unwritten agreements. Most contemporary and many of the earliest settlers are female and women’s contributions to the fishing industry are discussed. Emphasis is also placed on the fisher-based solution that settlement houses represent; implications for use in co-management strategies and the need to reduce the adversarial atmosphere in fisheries governance are discussed. 相似文献
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On the basis of observational data of the eastern part of the West Pacific Ocean, a diagnostic calculation of equatorial flow for this region is performed by using the authors' model equations and computing scheme and methods. For the first cruise (January 3-March 4, 1979), the results show: (i) The primary driving force of the equatorial surface flows comes from the prevailing northeasterly wind field, with an average uniform wind speed Vw = 6.3 m/s. The steady westward wind produces divergent westward flows in the surface layers, causing an upwelling near the equator. The importance of the steady wind stress in the upper layer (120 m) decreases with depth and becomes insignificant at the level of z = 75 m or z = 100 m, (ii) The equatorial undercurrent is a strong eastward and equator-ward flow, with its eastward component of undercurrent larger than its meridional component. The core of the undercurrent is at the thermocline, and its maximum velocity is 88-90 cm/s at the level of z=200 m. The deeper f 相似文献
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我国东部邻海恶劣天气的时空分布及其成因初探 总被引：2，自引：0，他引：2
本文利用1930～1979年NCDC海洋船舶观测的气象资料,分析了中国东部邻海恶劣天气的时空分布。结果表明,海区恶劣天气的分布在冬季和夏季是不同的;在东北和西南季风期间,台湾东北和西南海区也有差异。影响恶劣天气条件的分布因子非常复杂,主要是季风和极锋、天气系统、冷暖洋流及地形等因子。 相似文献
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以西沙群岛现代澄黄滨珊瑚的冬季氧同位素记录为代用指标,重建了18182000年的南海冬季风风速。重建序列显示18181954年冬季风速以每年0.009m·s-1的速率下降,而19552000年下降速率明显增强为每年0.021m·s-1,46年间风速下降达20%。整个183年中冬季风速变化具有两个完整的强弱波动特征,其中1830s和1940s为过去近两个世纪当中冬季风速最强和最弱的时期。20世纪的冬季风速变化与南海海表温度和中国陆地气温极为相似,相位相反,并揭示了1940s和1980s年代两个特征暖期。通过对冬季风速异常和ENSO暖、冷事件的统计分析,发现大多数ENSO事件发生时与冬季风减弱相对应。 相似文献
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在 １９９２～１９９３年度南极夏季期间，用肠道荧光法现场测定大磷虾（Ｅｕ－ ｐｈａｕｓｉａ ｓｕｐｅｒｂａ Ｄａｎａ）的肠道排空率和肠道内含物色素水平，并据此计算自然状况下 大磷虾的摄食率。大磷虾的肠道排空率为０．４３／ｈ。次成体（平均体重为１６８．８ｍｇ干 重）和成体（平均体重为 ２７４．３ｍｇ干重）的摄食率分别为 １８０．６±１９．２和 ４６４．４± ２８．３ｎｇ叶绿素ａ／ｈ。自然状况下大磷虾的摄食率与现场测定的 １００ｍ以上水层平均 叶绿素ａ浓度的相关性不大。 相似文献
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The results of numerical experiments with a coupled atmosphere-ocean general circulation model on the reproduction of climate changes during the 20th century and on the simulation of possible climate changes during the 21st–22nd centuries according to three IPCC scenarios of variations in the concentrations of greenhouse and other gases, as well as the results of the experiments with the doubled and quadruple concentrations of CO2, are considered. An increase in the near-surface air temperature during the 20th century and the features of the observed climate changes, such as warming in 1940–1950 and its slowing down in 1960–1970, are adequately reproduced in the model. According to the model, the air-temperature increase during the 22nd century (as compared to the end of the 20th century) varies from 2 K for the most moderate scenario to 5 K for the warmest scenario. This estimate is somewhat lower than the expected warming averaged over the data of all models presented in the third IPCC report. According to model data, in the 22nd century, under all scenarios, at the end of summer, a complete or almost complete sea-ice melting will occur in the Arctic. According to the model, by the year 2200, the sea level will vary by 20 to 45 cm as compared to the level at the end of the 20th century. 相似文献
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Natural resources of all kinds have been overexploited by user groups who cannot or will not develop rules to constrain their own exploitive efforts. One notable exception is the Maine lobster industry, where an effective set of conservation laws has been developed due, in great part, to the strong support of the industry. In the early decades of the 20th century, however, the lobster industry was marked by widespread violations of the existing conservation laws and opposition to developing more. This article explores the way that the pirate ethic gave way to the conservation ethic in the 1930s. Our explorations in evolutionary game theory suggest that this change was produced by three factors: costs and benefits of defection from the conservation ethic; numbers of people accepting the conservation ethic quality rule; and events that shocked the system from one state to another. We argue that the shock to the system in the late 1920s and 1930s was caused by massive stock failure which changed the attitudes of many fishermen about the need for conservation. People began to report violations of the law, which made law enforcement more effective and quickly led to a cascade of fishermen abandoning the pirate ethic. In the late 1930s, increasing catches, in combination with a number of other social, technical, and economic factors continued the upward spiral. 相似文献