南海北部主要捕捞种类最适开捕规格研究

根据南海水产研究所使用elefan技术基于体长数据求得的南海北部50种主要捕捞种类的von Bertalanffy生长参数,以Beverton-Holt模型计算最适开捕年龄后用von Bertalanffy生长方程计算其相应开捕体长,再参考实际调查最小性成熟体长、临界体长、拐点体长和Froese-Binohlan经验公式计算的初次性成熟体长范围等数据确定最适开捕规格;部份分海区研究的种类先确定同一种类于各海区的最适开捕规格,再考虑不同海区的适用性确定其在南海北部的最适开捕规格。本文研究了南海北部50种主要捕捞种类的最适开捕规格,结果表明,所求得的最适开捕规格比原广东、广西、福建“水产资源繁殖保护实施细则暂行规定”的开捕规格都大;建议选择19种在以往的生产中和历次凋查研究中出现频率较高、产量较高的主要捕捞种类作为南海北部实行开捕规格保护幼鱼幼虾措施的指标种,并提出开捕规格的随机抽样检查方法。

休渔对南海北部多齿蛇鲻资源的影响

根据实施休渔前 1997～ 1999年南海北部底拖网调查资料 ,以及实施休渔后 2 0 0 0～ 2 0 0 2年2 0 0nmile专属经济区渔业资源调查 (南海区 )最新资料 ,综合分析南海北部实施休渔前后多齿蛇鲻资源的变动趋势。结果表明 ,实施休渔后 ,海南岛以东和北部湾多齿蛇鲻渔获率分别提高了 5 7.75%和 84 .38% ,并呈现出自然的季节变化 ,渔获群体一龄鱼以下比例减少 ,一龄鱼以上比例增加。并讨论了资源养护的对策。

1998年南海季风爆发时期中尺度对流系统的研究:I中尺度对流系统发生发展的大尺度条件

南海季风试验（SCSMEX）的观测表明，1998年南海北部夏季风爆发（5月16～20日）的主要特征是中尺度对流活动的突然爆发和降水迅速增加。文章通过讨论大尺度背景下中尺度对流活动及降水形成的物理条件，揭示了该时段中尺度对流系统与中尺度雨带形成的可能机制：（1）在季风爆发初期华南及南海北部地区对流层低层较高的假相当位温与对流不稳定性、低层西南风辐合和高层的辐散为该地区的中尺度对流系统的发展提供了有利的大尺度热力与动力条件；来自孟加拉湾与副热带高压西侧的西南气流为南海北部强降水区提供了大量水汽，形成了该区深厚的湿层和强水汽辐合；（2）来自东亚中高纬地区几次冷空气活动是对流活动发生的重要触发机制，其作用是使对流不稳定能量迅速释放和对流活动在大范围地区突然爆发；（3）通过对南海季风试验期间安装在东沙岛和实验3号科学考察船上的双多普勒雷达资料反演的降水量分析表明，活跃的对流在季风槽和相应的风场切变线作用下，不断地组织并形成一些中尺度对流雨带（MCSs）。1998年5月15～19日季风爆发时段内，可观测到约12次中尺度降水过程，它们的生命期为6～10h或更长；（4）南海季风槽与低层切变线的建立以及其中中尺度低涡的产生和发展是中尺度对流系统形成与维持的必要条件。

对南海北部鱼类资源现状与繁殖保护问题的探讨

渔业是国民经济的组成部份之一，水产资源是发展渔业生产的重要基础。因此，只有认真保护水产资源，保证资源的正常繁殖、成长，才能科学地持续地利用资源，确保渔业生产的不断发展。

中国南海深水油气勘探现状与挑战

近年来，随着浅水油气产量的下降、勘探开发技术的进步及深水油气田的储量规模的探明．世界范围内深水油气勘探出现热潮。中国以水深大于300m的海域称为深水区．其主要分布在南海海域和东海海域。目前．我国深水油气勘探活动集中在南海北部地区。

Spatio-temporal variations in the siphonophore community of the northern South China Sea

To understand how hydrological and biological factors affect near-to off-shore variations in the siphonophore community,we sampled zooplankton at 82 stations in the northern South China Sea during summer,winter,and spring.Forty-one species of siphonophore were collected by vertical trawling.The species richness of siphonophores increased from the nearshore to offshore regions in all three seasons of investigation,with maximum richness in summer and minimum richness in winter.The abundance of siphonophores was also higher in summer than in spring and winter,concentrated in the nearshore region in the warm season and scattered in the offshore region in the cold season.Four siphonophore groups were classified according to the frequency of occurrence:nearshore,near-offshore,offshore,and tropical pelagic.Among them,the nearshore group had higher abundance nearshore compared with the offshore.The tropical pelagic group had higher species number offshore than nearshore.Spatial and temporal fluctuations in taxonomic composition and abundance of siphonophores were due to the influence of the coastal upwelling and surface ocean currents of the South China Sea,driven by the East Asia monsoonal system.

Oil source and migration process in oblique transfer zone of Fushan Sag,northern South China Sea

The oblique transfer zone in the Fushan Sag, a syndepositional dome sandwiched between the Bailian and Huangtong sub-sags, has been the most important exploration target. The major oil observation occurs in the E_2l_1^(L+M) and the E_2l_3~U. 46 oil and rock samples reveal that the oil in the transfer zone is mostly contributed by the Bailian sub-sag, though the source rock conditions, hydrocarbon generation and expulsion histories of the Bailian and Huangtong sub-sags are similar. The E_2l_3~U oil, characterized by high maturity, Pr/Ph ratio and oleanane/C_(30)-hopane ratio, shows a close genetic affinity with the E_2l_3~b source rocks, while the E_2l_1^(L+M) oil, characterized by lower maturity, Pr/Ph ratio and oleanane/C_(30)-hopane ratio, is suggested to be derived from the E_2l_(1+2)~b source rocks. The homogenization temperatures of aqueous fluid inclusions, taking the burial history of the reservoirs into account, reflect that the oil charge mainly occurred from mid-Miocene to Pliocene in the oblique transfer zone. The oil transporting passages include connected sand bodies, unconformities and faults in the Fushan Sag. Of these, the faults are the most complicated and significant. The faults differ sharply in the west area, the east area and the oblique transfer zone, resulting in different influence on the oil migration and accumulation. During the main hydrocarbon charge stage, the faults in the west area are characterized by bad vertical sealing and spatially dense distribution. As a result, the oil generated by the Huangtong source rocks is mostly lost along the faults during the vertical migration in the west area. This can be the mechanism proposed to explain the little contribution of the Huangtong source rocks to the oil in the oblique transfer zone. Eventually, an oil migration and accumulation model is built in the oblique transfer zone, which may provide theoretical and practical guides for the oil exploration.

Preliminary Study on Seismic Anisotropy in the Crust in the Northeast of Hainan

With SAM shear-wave splitting analysis,shear-wave splitting parameters at two stations of the digital seismic network in the northeast of Hainan are obtained based on the data from the Hainan Digital Seismic Network from 2000 to 2013. The results show that the predominant polarization direction of fast share-wave represents the direction of in-situ maximum principal compressive stress. The predominant polarizations of Qixingling( QXL) seismic station are in the NEE direction,which is different from the direction of principal compressive stress of the Hainan area,but same as the strikes of faults in the NE direction,which means that the local tectonics and stress fields are complicated. The predominant polarization of Qingshanling( QSL) seismic station is in the NNE-NS direction,which indicates the tectonic significance of the strikes of NNE-trending faults.At the same time,the study confirms that the predominant polarizations of the stations located on active faults or at the junctions of several active faults are parallel to the strikes of faults which control the earthquakes used in this analysis, and the predominant polarizations are scattered,which indicates the complicated background of fault structures and stress distribution.

Spatiotemporal variations of deep-sea sediment components and their fluxes since the last glaciation in the northern South China Sea

Sediment components and their fluxes of Cores MD12-3428(water depth: 903 m), MD12-3433(water depth: 2125 m),and MD12-3434(water depth: 2995 m), obtained along a transect on the continental slope of the northern South China Sea, have been conducted to reveal the spatiotemporal variations and the controlling factors of the sediment components and of their fluxes.Results show that deep-sea sediments in the northern South China Sea are composed mainly of terrigenous(59–89%) and carbonate(6–38%) particles, with minor components of opal(1.6–9.4%) and organic matter(0.7–1.9%). Fluxes of terrigenous and carbonate particles reach up to 2.4–21.8 and 0.4–6.5 g cm–2 kyr–1, respectively, values that are one to two orders of magnitude higher than the fluxes of opal and organic matter. Temporal variations of the percentages and fluxes of deep-sea sediment components have displayed clear glacial-interglacial cyclicity since the last glaciation. Terrigenous, opal, and organic matter percentages and their fluxes increas clearly during marine isotope stage 2, while carbonate percentages and fluxes show an opposite variation pattern or are characterized by an unremarkable increase. This implies that deep-sea carbonate in the South China Sea is affected by the dilution of terrigenous inputs during the sea-level lowstand. With increasing water depth along the transect, the terrigenous percentage increases but with largely decreased fluxes. Both the percentage and flux of carbonate decrease, while the percentages and fluxes of opal and organic matter display much more complicated variational features. The spatiotemporal variations of deep-sea sediment components and of their fluxes since the last glaciation in the northern South China Sea are strongly controlled by sea-level fluctuations. Simultaneously, terrigenous supply associated with monsoonal rainfall, marine primary productivity,and the dilution effect between terrigenous and biogenic particles, also play interconnected roles in the sediment accumulation processes.