Using otolith weight to predict the age of <Emphasis Type="Italic">Pennahia macrocephalus</Emphasis> in the mouth of the Beibu Gulf

The relation between otolith weight (OW) and the age of marine fish is studied. A total of 222 individuals of bighead white croaker, Pennahia macrocephalus were sampled seasonally in the mouth of the Beibu Gulf, the South China Sea, in 2007. Since there are no significant differences in sagittal OW between otolith in pairs (P≥0.05), the undamaged left sagittal otolith is used for age determination. The highest correlations among standard length, OW and fish ages are confirmed by linear, exponential and multinomial regression. Results show that sagittal OW overlaps only occasionally among age groups, and to individuals with similar standard length, the older and slower-growing fish has a heavier otolith because of the continued otolith material deposition. There are differences in sagittal OW among different age groups and significant positive linear relationship with age (P<0.05). The age readings can be verified by plotting the sagittal OW versus the standard length for age groups, and the individuals with similar standard length but in different ages can be separated by sagittal OW frequency analysis. Mostly, the predicted ages using the regression between sagittal OW and ages are closed to the observed ages by counting annulus on scale. It indicates that the sagittal OW analysis is a useful technique for validating the accuracy of age determination by annuli counts, especially for individuals of similar size. Furthermore, the technique is applied for Pennahia macrocephalus with discussion in this paper. Supported by the National Natural Science Foundation of China (No. 30771653) and Bureau of Fisheries, Ministry of Agriculture     

Age and Growth Characteristics of Crimson Sea Bream Paragyrops edita Tanaka in Beibu Gulf

Age and growth characteristics of crimson sea bream Paragyrops edita Tanaka in Beibu Gulf were studied through bot-tom trawling and gillnet fleets fishing from July 2006 to December 2007.A total number of 1155 individuals,ranging from 49 to 249mmin standard length was examined.The age of the fish was determined from sagittal otoliths.One year growth was made up of onetranslucent and one opaque zone.A maximum likelihood estimation procedure was used to fit the Von Bertalanffy,Logistic andGompertz growth functions to the length-at-age data.ARSS indicated that there were no significant differences in growth betweensexes in the three growth models (P>0.05),and the Von Bertalanffy growth function L<,t>=292.8{1-exp[-0.167(t 1.116)]} was se-lected as the most appropriate growth model according to Akaike's information criterion (AIC).     

Age and growth characteristics of crimson sea bream <Emphasis Type="Italic">Paragyrops edita</Emphasis> Tanaka in Beibu Gulf

Abstact  Age and growth characteristics of crimson sea bream Paragyrops edita Tanaka in Beibu Gulf were studied through bottom trawling and gillnet fleets fishing from July 2006 to December 2007. A total number of 1155 individuals, ranging from 49 to 249 mm in standard length was examined. The age of the fish was determined from sagittal otoliths. One year growth was made up of one translucent and one opaque zone. A maximum likelihood estimation procedure was used to fit the Von Bertalanffy, Logistic and Gompertz growth functions to the length-at-age data. ARSS indicated that there were no significant differences in growth between sexes in the three growth models (P>0.05), and the Von Bertalanffy growth function L _t =292.8{1−exp [−0.167(t+1.116)]} was selected as the most appropriate growth model according to Akaike’s information criterion (AIC).     

北部湾江洪扇贝养殖区的污损生物

2006年8月至2007年7月,对北部湾江洪扇贝养殖区的污损生物进行周年调查。结果表明:该海区养殖网笼的污损生物有8门20种,优势种为藤壶、钩虾、苔藓虫,其次是翡翠贻贝、牡蛎、海鞘、大型藻类和水螅。污损生物附着高峰在8、11和12月,1月的附着数量最少;藤壶附着高峰在8、11和12月,附着生物量占污损生物总量的56.0%,是养殖区污损生物防除的重点对象;钩虾附着高峰出现在8、9月,12和2月附着量也较高,其生物量占污损生物总量的18.0%;草苔虫附着高峰出现在4月,其生物量占污损生物总量的8.4%。污损生物附着量呈现由表层向底层递减的趋势。     

北部湾二长棘鲷生长、死亡及其群体组成

利用2006年7月至2008年3月北部湾渔业商业捕捞底拖网和刺网渔获物中采集的样本,对北部湾二长棘鲷的生长、死亡及其群体组成进行了初步研究。结果表明,北部湾二长棘鲷优势体长70～140 mm,占82.2%;优势体重为20～60 g,占54.29%;ARSS分析表明雌雄生长不存在显著性差异(P>0.05),繁殖期性比为1.21∶1;von Bertalanffy生长方程的主要参数分别为:L∞=292.8 mm,K=0.167,t0=-1.116;体重的生长拐点为5.463龄;总死亡系数、自然死亡系数和捕捞死亡系数分别为1.041 4、0.282 8和0.752 6,当前开发率为0.728。     

Counter-Wind Deep Current in the Northern Beibu Gulf in Boreal Winter

The Beibu Gulf is at an important geographical location and rich in gas, oil and biological resources. The observed currents showed that the current in the upper layer was opposite to that in the lower layer in boreal winter in the northern Beibu Gulf and it was northeastward in the lower layer. This northeastward current was reproduced by a 3 D baroclinic model in this study. It's found that the counter-wind deep current(referred to as ‘CWDC' hereinafter) strengthened from September to November but weakened from December to the following February. A closed meridional circulation in vertical direction was found in the northern Beibu Gulf, including CWDC, surface southwestward current, an upwelling, and a downwelling. The temporal variation process of the meridional circulation was similar to that of CWDC, with strength and range stronger in November and December than in other four months. Similar to the variation process of CWDC, the monsoon wind changed from weak easterly wind in September to strong northeasterly wind in November and December, and it was transformed into weak southeasterly wind in February again. The sensitive experiments showed that CWDC and the meridional circulation were controlled by the monsoon wind and were adjusted by heat flux-and tide-induced mixing, respectively. According to the momentum balance equation, it can be revealed the counter-wind deep current is a compensation current which is induced by the surface elevation gradient balanced by the Coriolis force, vertical diffusion and baroclinic pressure gradient.     

Nutrients distribution and trophic status assessment in the northern Beibu Gulf,China

Using historical and 2010 field data, the distribution of nutrients in the northern Beibu Gulf of China is described. There was a decreasing trend in the concentration of nutrients from the north coast to offshore waters of the northern Beibu Gulf, reflecting the influence of inputs from land-based sources. High concentrations of dissolved inorganic nitrogen （DIN） and phosphate （PO4-P） occurred mainly at Fangchenggang Bay, Qinzhou Bay, and Lianzhou Bay. Four different methods were used to assess eutrophication. The trophic status of the Beibu Gulf was characterized using the single factor, Eutrophication index （El）, Trophic index （TRIX） and Assessment of Estuarine Trophic Status （ASSETS） methods. Based on nutrient concentrations, 73.9% of DIN and 26.7% of PO4-P samples exceeded the fourth grade Seawater Quality Standard of China. Eutrophication index values varied widely, but higher levels of eutrophication were generally found in bays and estuaries. TRIX values ranged from 2.61 to 7.27, with an average of 4.98, indicating a mesotrophic and moderately productive system. A positive correlation between TRIX and harmful algal species richness and abundance was observed. The ASSETS model evaluates eutrophication status based on a Pressure-State-Response approach, including three main indices： influencing factors, overall eutrophic condition, and future outlook. The Beibu Gulf was graded as moderate using ASSETS. The single factor and Chinese nutrient index methods were considered inadequate for the assessment of trophic status. TRIX can be used as an indicator of trophic state and ASSETS showed good potential to assess eutrophication. The results of TRIX and ASSETS depend on threshold values. To establish these values, further research is required within the northern Beibu Gulf.     

基于底拖网调查数据的渔业资源质量状况评价体系构建——以北部湾为例

【目的】构建渔业资源质量状况评价体系,评估渔业管理成效,服务海洋渔业可持续发展。【方法】以北部湾底拖网调查数据为基础,结合渔业统计数据,构建渔业资源质量状况评价指标体系。该体系分3个层次,下设7项指标。通过专家经验法和平均赋值法对指标进行赋值,得到各指标权重,建立质量状况评价等级指数,并利用该等级指数对北部湾渔业资源进行评价。【结果与结论】1992―2017年北部湾渔业资源评价指标中有6项呈下降趋势;质量状况评价等级指数波动在0.44~0.56之间。自20世纪90年代以来,北部湾渔业资源一直处于临界状态。该评价结果与北部湾渔业资源利用的实际状况基本相符,证明该方法具有合理性和可操作性,可为其他海区渔业资源质量状况评价提供借鉴。     

Feeding ecology of hairtail Trichiurus margarites and largehead hairtail Trichiurus lepturus in the Beibu Gulf, the South China Sea

We evaluated the feeding ecology of largehead hairtail (Trichiurus lepturus) and hairtail (T. margarites). We collected specimens from fishing ports in the Beibu Gulf (Gulf of Tonkin) from October 2008 to September 2009 and analyzed their gut contents. We collected 857 T. lepturus and 666 T. margarites samples. The number of stomachs examined in this study was sufficient to describe the monthly and ontogenetic diet shifts for the two species, as indicated by the trophic diversity curves. T. lepturus was a general omnivore, feeding primarily on Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis. Conversely, T. margarites preyed primarily on D. maruadsi, B. rarisquamosus, B. nectabanus, and A. chinensis. Both species exhibited distinct ontogenetic diet shifts. Although the two hairtail specie fed on similar sources in the same habitat, the diet overlap was relatively low. Our results suggest that hairtail play an important role in controlling small pelagic and benthic fish populations in the gulf. This trophic correlation shall be used for developing a marine ecosystem model for the Beibu Gulf.     

南海北部湾秋季蓝圆鲹与竹筴鱼的摄食生态及食物竞争

【目的】研究南海北部湾海域秋季蓝圆鲹与竹筴鱼的摄食生态特征和种间食物竞争。【方法】采用胃含物分析法,对2017年10月北部湾底拖网调查和港口随机取样收集的119尾蓝圆鲹(Decapterusmaruadsi)和198尾竹筴鱼(Trachurus japonicus)胃含物样品进行分析,通过肉眼直接观察或显微镜间接观察胃中残留的饵料,饵料种类鉴定、计数、称重等对食性做定量分析,以估算两种鱼类的营养级和生态位宽度,并利用生态位重叠研究两种鱼类的食物竞争关系。【结果与结论】蓝圆鲹的饵料种类19种(属),以桡足类和小型鱼类为主,优势饵料生物为布氏半棱鳀(Encrasicholinapunctifer);竹筴鱼的饵料种类18种(属),以小型鱼类和浮游甲壳类为主,优势饵料为中国毛虾(Acetes chinensis)。两种鱼类均为游泳动物食性,均存在摄食转换,随着叉长的增长,蓝圆鲹的饵料生物由小型浮游动物为主转变为小型鱼类为主,竹筴鱼的饵料生物由小型鱼类为主转变为以樱虾类和较大鱼类为主。蓝圆鲹和竹筴鱼的空胃率、竹筴鱼的平均胃饱满指数均随个体生长呈显著变化(P<0.05),但蓝圆鲹的平均胃饱满指数随个体生长无显著变化(P>0.05)。蓝圆鲹和竹筴鱼的营养级分别为3.63和3.40,营养生态位宽度分别为1.70和1.24,生态位重叠系数0.56,表明两种鱼类之间存在一定的食物竞争。     

Population parameters and dynamic pool models of commercial fishes in the Beibu Gulf, northern South China Sea

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.     

不确定性对北部湾二长棘鲷渔业资源评估影响的模拟研究

利用蒙特卡罗模拟方法研究了生物学参考点F0.1、Fmax和当前捕捞死亡系数(current fishing mortality rate,Fcur)估计中的不确定性对北部湾二长棘鲷渔业资源评估的影响。结果表明:二长棘鲷渔业资源状态评估受到F0.1、Fmax、Fcur估计中的不确定性和管理者选取的决策置信水平的影响,二长棘鲷渔业被确定为过度捕捞的概率随着F0.1、Fmax、Fcur估计中不确定性和置信水平的增加而下降;F0.1和Fmax估计中的不确定性主要由生长参数的不确定性引起,自然死亡系数的不确定性对F0.1和Fmax估计中的不确定性的影响是有一定限度的。相比Fmax,将F0.1作为二长棘鲷渔业的管理目标更为合适。     

Stock discrimination of spottedtail goby (Synechogobius ommaturus) in the Yellow Sea by analysis of otolith shape

Otolith shape is species specific and is an ideal marker of fish population affiliation. In this study, otolith shape of spottedtail goby Synechogobius ommaturus is used to identify stocks in different spawning locations in the Yellow Sea. The main objectives of this study are to explore the potential existence of local stocks of spottedtail goby in the Yellow Sea by analysis of otolith shape, and to investigate ambient impacts on otolith shape. Spottedtail goby was sampled in five locations in the Yellow Sea in 2007 and 2008. Otoliths are described using variables correlated to size (otolith area, perimeter, length, width, and weight) and shape (rectangularity, circularity, and 20 Fourier harmonics). Only standardized otolith variables are used so that the effect of otolith size on the shape variables could be eliminated. There is no significant difference among variables of sex, year, and side (left and right). However, the otolith shapes of the spring stocks and the autumn stocks differ significantly. Otolith shape differences are greater among locations than between years. Correct classification rate of spottedtail goby with the otolith shape at different sampling locations range from 29.7%–77.4%.     

THE CHANGE OF THE GENERAL FORM AND THE TRANSPORT OF THE WATER， LOAD AND SALT ABOUT THE NORTH－BRANCH OF THE CHANGJIANG RIVER MOUTH

陈宝冲ＴＨＥＣＨＡＮＧＥＯＦＴＨＥＧＥＮＥＲＡＬＦＯＲＭＡＮＤＴＨＥＴＲＡＮＳＰＯＲＴＯＦＴＨＥＷＡＴＥＲ，ＬＯＡＤＡＮＤＳＡＬＴＡＢＯＵＴＴＨＥＮＯＲＴＨ－ＢＲＡＮＣＨＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲＭＯＵＴＨ￥ＣｈｅｎＢａｏｃｈｏｎｇ（Ｎ...     

Observed residual currents off the Changjiang （Yangtze） Rivermouth in summertime of 1959 and 1982

Data taken in two large scale ocean observations in China in summer 1959 and 1982 were used to analyze the residual current off the Changjiang (Yangtze) River mouth. The currents at surface off the mouth in July 1959 and 1982 flow northeastward and eastward due to the river discharge, the current speed was larger in 1982 than in 1959. All the bottom currents flow landward due to baroclinic effect. The surface current was controlled by the river runoff and the Taiwan Warm Current (TWC). A return current at surface off the mouth was observed in September 1959. In general, the bottom currents were controlled by the TWC in most study area in addition to the runoff near the mouth. Although driven by 3-D model with the monthly averaged forces (river discharge, wind stress, baroclinic effect, open boundary water volume flux and tidal mixing) in August, the simulated circulations were basically consistent with the observed ones with episodic time manner.     

Forecast of impacts of sea-level rise on the low colonized islands and their surrounding waters in the Changjiang River mouth

Thethreatagainstthecoastallowlandcausedbysea-levelriseisoneofthefocusesoftheworid'sat-tention.Thebestestimatevalueofglobaltheoreticalsea-levelriseinthe2lstcenturyisO.66m(SCOR,l99l)byworldwideauthoritativeorganizationsuchasIPCC(IntergovernmentPanelofClimateChange)etal.ThecrustofChangiiangDeltaissubsiding.Theaveragesubsidencerateinthelast2OOOaisl.2mm/a(PANetal.,l985).TheislandsoftheChangiiangRivermouthareaccumulatinglowlandislandsandtheirnat-uralelevationisbelowthehightidallevelofsprin…     

略论孙中山与驻粤滇军的关系——以陈炯明叛变后为例

陈炯明叛变后,孙中山与驻粤滇军一度采取互相依赖的政策,两者经历了短暂的"蜜月"期。占领广州后,尽管二者仍有互为依赖的趋向,但矛盾逐步升级。为此,孙中山不得不采取反思以往的革命、建立党军等政策。他们的关系之所以产生如此变化,原因是驻粤滇军的军阀化倾向等因素。     

利用JCZ-1T地震计BB通道观测数据检测地球自由振荡

采用库尔勒台JCZ-1T地震计BB通道垂直向的观测数据,利用功率谱密度估计方法,在没有对观测资料进行任何改正的情况下,获取2016-03-02印尼苏门答腊岛海域7.8级和2016-04-17厄瓜多尔7.5级大地震激发的0S7～0S60基频球型自由振荡,并与PREM模型理论值进行对比分析。结果表明,实测值与理论值相吻合,除部分振型与理论值偏差较大以外,其余振型与理论值偏差均小于0.1％。印尼苏门答腊岛海域7.8级地震所检测的球型振荡能量频谱分布及振型与厄瓜多尔7.5级地震所检测的球型振荡有一定差别,前者所能检测的振型数量相对较多。     

菏泽市加强“双保工程”建设的几点做法

城乡建设用地增减挂钩试点和指标置换政策是国土资源部统筹城乡发展的一项重大创新举措,该文从菏泽市实际出发,对严格土地用途管制,严格规划计划,严控建设用地规模,严格执行国家产业政策和供地政策,落实好城乡建设用地增减挂钩试点和指标置换政策提出自己的见解。     

THE COLD AND HOT DAMAGES TO THE CITRUS IN THE THREE GORGES AREA OF THE CHANGJIANG RIVER

ＴＨＥＣＯＬＤＡＮＤＨＯＴＤＡＭＡＧＥＳＴＯＴＨＥＣＩＴＲＵＳＩＮＴＨＥＴＨＲＥＥＧＯＲＧＥＳＡＲＥＡＯＦＴＨＥＣＨＡＮＧＪＩＡＮＧＲＩＶＥＲＣｈｅｎＺｈｅｎｇｈｏｎｇ（陈正洪）；ＹａｎｇＨｏｎｇｑｉｎｇ（杨红青）；ＮｉＧｕｏｇｕ（倪国裕）（Ａｇｒｏ...