东海中北部小眼绿鳍鱼的摄食习性分析

根据2008年5月~2009年2月期间采集的渔获样品,对东海中北部小眼绿鳍鱼(Chelidonich-thys spinosus)胃含物进行分析。结果表明:小眼绿鳍鱼食物组成以磷虾类(IRI=1308.55)为主,其次依次为长尾类(IRI=563.09)、鱼类(IRI=170.59)和糠虾类(IRI=31.85);其优势饵料种类为太平洋磷虾、细巧仿对虾、细螯虾、戴氏赤虾、六丝矛尾鰕虎鱼、漂浮小井伊糠虾等。小眼绿鳍鱼终年摄食,其摄食率为83.25%,最高饱满指数达171.86‰,平均饱满指数18.84‰,这表明小眼绿鳍鱼具有较强的摄食强度。同时单因素方差检验表明,小眼绿鳍鱼的摄食强度无显著的季节变化,而有显著的体长变化。     

黄、渤海半滑舌鳎种群遗传结构的同工酶分析

采用水平淀粉凝胶电泳技术检测黄海、渤海半滑舌鳎两个群体的同工酶组织特异性并分析和研究其群体遗传结构。结果表明,半滑舌鳎的眼、鳃、肌肉、心脏、肝脏、肾脏、脾脏、鳍条、脑等9种组织和器官对18种同工酶的表达呈现明显的组织特异性。对肌肉和肝脏两种组织的PGDH、MPI、IDHP、SOD、AAT、MDH、LDH、G3PDH、PGM、LAP、ADH、SDH和ALP共13种同工酶进行了遗传学分析,共记录16个基因座位。其中,黄海群体在4个基因位点(IDHP、PGM、G3PDH、SDH)、渤海群体在5个基因位点(IDHP、PGM、MDH2、SDH、ALP)表现为多态,黄海和渤海群体的多态位点比例分别为0.2500和0.3125;两个群体的平均观测杂合度分别为0.0143、0.0104,平均预期杂合度分别为0.0140、0.0102;平均有效等位基因数则分别为1.0151和1.0108。两群体间的遗传距离为0.00012。半滑舌鳎的两个群体遗传多样性水平较低,两群体间无明显的遗传分化。     

Trophic relationships and ecosystem characteristics in a newly-impounded man-made lake in Thailand

Abstract  The trophic dynamics of a newly-impounded south east Asian reservoir, Pasak Jolasid, Thailand, monitored from its creation, were constructed using ecopath , a mass-balanced model. The trophic levels (TLs) of 36 ecological groups varied between 1.0 and 3.2. The majority of fish biomass was at the second TL, where the fishery is concentrated. Some food resources (benthic organisms and zooplankton) were not fully used, whereas phytoplankton and benthic algae were important components of the food web, which is based on phytoplankton and detritus. The implications of these findings are discussed in terms of ecological maturity of the ecosystem and possible fishery management of this multi-purpose reservoir.     

东海带鱼生殖和补充特征的变动

根据1986—2000年对东海和南黄海渔获带鱼的生物学基础调查，利用世代分析方法计算了东海带鱼的资源数量，分析了东海带鱼生殖和补充特征的变动状况，同时研究了环境与带鱼补充量变动的关系。结果表明，随着捕捞压力的增大，东海带鱼的最小成熟体长、产卵亲体的平均体长、平均体重组成进一步缩小，个体繁殖力提高而卵径变小；实行伏季休渔后，东海带鱼的补充群体数量大幅度增加，单位亲体的补充量比伏休前增加45％～60％，证明了伏季休渔的生态效益；带鱼补充群体数量与亲体数量、海中温度、伏休时间成正比。目前东海带鱼的亲体数量仍显不足，应进一步减少对带鱼的捕捞强度。     

南海北部海域多齿蛇鲻的种群分析

对南海北部海域5个多齿蛇鲻地理群体(北海、湛江、茂名、东莞、汕尾)共78个个体的线粒体控制区基因序列进行了扩增测序。在78个个体的568bp序列中共检测到48个单倍型,39个变异位点。经分子变异等级分析(AMOVA)得出5个地理群体内遗传变异度为98.82%,群体间遗传变异度仅为1.18%,各群体间成对遗传变异固定指数FST值在0.00024～0.03008;78个个体间的遗传距离在0～0.025。通过对基于序列片段构建的NJ树和基于序列单倍型利用中介网络法构建的群体间关系网的分析发现,5个群体间有明显的基因交流,遗传分化差异不大;再结合种群、种及属的界定标准,判定5个多齿蛇鲻群体归属于同一种群;而且,在经历快速增长、变异和瓶颈期之后,多齿蛇鲻种群就以小群体模式继续快速增长,形成地理群体。     

Abnormalities in the juvenile stage of sea bass (Dicentrarchus labrax L.) reared at different temperatures: types, prevalence and effect on growth

Osteological malformations are always considered an important problem in intensive aquaculture. This work studies the effect of rearing temperature on malformations in sea bass, Dicentrarchus labrax. To this end, two batches of the species were subjected to the following incubation/cultivation temperatures: 15 °C/natural and 19/19 °C, from fertilization until 190 days after hatching. The different malformations were studied in 1643 juveniles at 190 days and classified by categories. The Chi-square statistic was calculated to verify the relationship between the presence of anomalies and the application of different temperatures. The percentage of anomalies observed in individuals reared at a high temperature (19/19 °C) was 66.44%. In both temperature systems, opercular malformations were those which caused a greater delay in growth. The results found indicated that temperature played a very important role in the development of deformations, which may be of interest from the viewpoint of aquaculture.     

Linking spatial pattern of bottom fish assemblages with water masses in the North Sea

Understanding the links between large scale spatial structuring of fish assemblages and shaping factors is essential to develop comprehensive ecosystem-based fisheries management. In this study, we investigated spatial patterns of bottom fish assemblages in the North Sea in relation to prevailing water masses in the region. We based our analysis on catch data from the German Small-Scale Bottom Trawl Survey conducted between 1987 and 2005 and used both ordination techniques and Mantel tests. Spatial variability of bottom fish assemblages was larger than inter-annual variability. Five significantly different bottom fish assemblages were associated with the following prevailing hydrographical regimes: i) the English Channel, ii) Continental Coastal, iii) central North Sea, iv) northern North Sea, and v) northern Atlantic water masses. Associations were generated by gradients in relative proportions of abundant species such as grey gurnard ( Eutrigla gurnardus ), dab ( Limanda limanda ), whiting ( Merlangius merlangus ), haddock ( Melanogrammus aeglefinus ) and Norway pout ( Trisopterus esmarki ). Taking into account large scale spatial structuring of catch data Mantel tests confirmed significant correlation between the fish assemblages and hydrographical variables. In summary, our results strongly support the hypotheses that hydrographical features such as water masses, fronts, and residual currents could shape bottom fish associations in the North Sea. Spatial demarcations of bottom fish assemblages indicated by this study can be used to support ecosystem-based fisheries management strategies.     

黄海鳀鱼鱼体能值的季节变化

根据2002年6月～2003年9月黄海中南部水域鳀鱼的调查资料,分析了产卵、索饵和越冬期鱼体能值的季节变化以及精巢和卵巢能值的变化情况。产卵期(5～7月)、索饵期(8～10月)和越冬期(11～1月)鳀鱼能值的变动情况反应了性腺发育状况。卵巢能值和精巢能值的季节变化趋势相似。幼鱼和成年鳀鱼能值的季节变化趋势相似,但各个月份幼鱼能值均比成鱼低。鱼体能值从越冬期到产卵前期变化很大,达40％～50％,这主要由脂肪含量变化引起。湿重丰满度系数比干重丰满度系数估算鱼体能值准确度差。     

2003年夏季东海区带鱼资源状况及其秋冬汛渔况的分析

根据东海区渔业资源动态监测网调查资料,对2003年伏季休渔期间的带鱼资源状况进行了分析,并展望了秋冬汛带鱼生产前景。结果表明,2003年伏季休渔前期(6月),东海区带鱼资源重量密度、资源尾数密度及发生量均比常年偏低、产卵期个体重量较常年偏大,亲鱼量属低水平年份;伏季休渔中期(7月、8月),带鱼的产卵群体比例下降,个体平均肛长偏小。同时,海区的水温较2002年偏低,不利于带鱼生长和发育。预计伏季休渔结束后,渔获状况不容乐观,秋冬汛生产前景将差于2002年。     

青岛斋堂岛海域春季双桩竖杆张网网囊网目的选择性

2014年春季,采用平行作业法,以2a=16 mm(a为目脚长度)的菱形目网囊为对照网(CN),选取30 mm菱形目网囊和20 mm、30 mm、40 mm的方形目网囊(分别以30D、20S、30S和40S表示)作为实验网囊,对青岛斋堂岛附近海域的双桩竖杆张网进行了不同网目形状的网囊和不同网目尺寸方形目网囊的选择性比较试验。以多元统计分析方法进行种间选择性分析,以Logistic曲线作为选择性模型、采用极大似然估算法进行种内选择性分析。结果显示,与对照网相比,所有实验网囊均能有效释放玉筋鱼(Ammodytes personatus)、舒氏海龙(Syngnathus schlegeli)等低值渔获以及经济鱼类的幼体。比较不同网目形状网囊的渔获数据发现,方形目网囊较菱形目网囊具有更好的选择性,其中30S网囊对玉筋鱼和舒氏海龙的释放率(以尾数计)分别比30D网囊高4.61%和16.80%,对六丝钝尾虾虎鱼(Amblychaeturichthys hexanema)和日本枪乌贼(Loigo japonica)的50%选择体长(胴长)L50分别比30D网囊大38.47%和61.29%。比较不同网目尺寸方形目网囊的渔获数据发现,当实验网为20S和30S时,六丝钝尾虾虎鱼的L50分别为6.58 cm和7.20 cm,选择范围(SR)分别为3.02 cm和0.87 cm;当实验网为20S、30S和40S时,日本枪乌贼的L50分别为2.88 cm、4.03 cm和10.49 cm,SR分别为0.74 cm、0.52 cm和2.67 cm;不同尺寸的方形目网囊对这2种渔获物的L50随着网目尺寸的增大而增大。根据实验海区各种渔获物的经济价值、低值鱼类和幼鱼的释放比例以及分拣渔获物的劳动力投入等综合分析认为,30 mm方形目网囊在保护渔业资源的同时对渔业生产不会造成显著影响,建议予以推广。