饲料中不同脂肪源对黑鲷幼鱼生长和鱼体脂肪酸组成的影响

用相同比例,不同种类的脂肪源配制成４组试验饲料,对黑鲷幼鱼进行了４５ｄ的饲养试验。结果表明,以大豆油,鱼油为饲料脂肪源的试验组的幼鱼增重率较高,分别为３４．８＊１０＾－２和２９．３＊１０＾－２。花生油组和猪油组的幼鱼增重率分别为２５．４＊１０＾－２和２５．５＊１０＾－２,饲料转换系数分别为鱼油组１．０８,豆油组１．２１,花生油组１．３５和猪油组１．５９。从试验饲料和鱼体脂质的脂肪酸分析结果表明,鱼     

真鲷幼鱼的摄食与生态转换效率：一种现场研究方法在室内的应用

1997年10月在黄海水产研究所小麦岛实验基地,采用Eggers模型现场研究方法在室内对人工培育的真鲷幼鱼(26.33±5.79g)进行了摄食和生态转换效率的研究。真鲷幼鱼的日摄食量12.97gw.w./100gw.w.·d,摄食率3 119.00cal/ind·d,生态转换效率19.40%。真鲷幼鱼的摄食与温度变化显著相关,消化道内含物量与水温的相关关系符合方程DCW=0.023　4·e0.256 3Temp.(P<0.001)。从每日的03∶00始,真鲷幼鱼消化道内含物的量随时间逐渐增加,至17∶30达到最高值,表现出单一摄食高峰,显示出其代表的真鲷黄、渤海种群与东海种群之间存在摄食节律方面的显著差异。研究结果表明,Eggers模型这一现场研究方法也适于室内研究鱼类摄食,特别对于那些现场不易获得的鱼种,是研究其摄食的一种既简便又准确的方法。     

活饵料中n-3高度不饱和脂肪酸对黑鲷仔稚鱼生长和存活的影响

采用乳化油直接添加法,用n－3高度不饱和脂肪酸（n－3HUFA）含量不等的4种乳化油分别强化轮虫、卤虫活饵料,培育4组黑鲷仔鱼和稚鱼,各自历时15d,结果表明,n－3HUFA对黑鲷仔鱼和稚鱼的生长和存活均有重要影响。在该条件下,轮虫体内n－3HUFA含量为0．233％（湿重计）,卤虫体内n－3HUFA含量为4．273％（湿重计）时,仔鱼和稚鱼达到最佳生长和成活率。     

人生长激素基因在团头鲂和鲤中的整合和表达

采用显微注射方法，将带有小鼠ＭＴ－１基因启动顺序与人生长激素ｈＧＨ基因顺序重组的线状ＤＮＡ片段，注入团头鲂和鲤的受精卵，获得成活的实验鱼。经斑点、Ｓｏｕｔｈｅｒｎ杂交、Ｎｏｒｔｈｅｒｎ杂交、放射免疫和酶联等方法检测，表明外源基因在受体鱼中得到整合、转录、翻译和表达，并具促生长效应。转基因雌鱼和雄鱼有性繁殖所获得的子鱼带有外源基因，表明外源基因能通过性细胞传递给子代，并仍具促生长效应。     

东海深海底层鱼类群落及其结构的研究

本文据东海深海1981年底鱼资源调查资料,按不同站、水深带之间计算渔获物组成的相似性指数C_2,应用聚类分析方法等综合分析,结果表明:调查海区底层鱼类可区分为东海大陆架(外缘)群落、东海大陆被群落和冲绳海槽(西侧)群落等三个(主)群落。其中,东海大陆坡群落还可细分为大陆坡上部、中部和下部等三个亚群落。同时,应用种类多样性、均匀性、丰盛度和优势度指数(H~1;D、J、d和D_2),对群落结构进行分析,结果表明:H~1、D、J或d值,一般是水深浅处较小,深处较大,它们随水深的变化趋势相似;D_2值则与以上各值大致相反。作者认为除种类组成和多样性指数外,种类相似性指数也是反映生物群落结构的一个重要特征。     

COMPETITIVENESS OF MAJOR EXPORTING COUNTRIES AND TURKEY IN THE WORLD FISHERY MARKET: A CONSTANT MARKET SHARE ANALYSIS

ABSTRACT

The purpose of this study is to examine whether and to what extent the shares of selected countries' fishery exports in the world markets reflect their international competitiveness. The Constant Market Share (CMS) model, which decomposes export growth into some broad components (i.e., structural effects, market effects, commodity effects and competitive effects), is applied to examine this issue. The results of decomposition analysis revealed that structural factors have been more significant in explaining the growth of exports. The growth effects, though, appeared positive for each country, the exports of open economies like Canada, the United States, Iceland and Turkey benefited more from the growth of world exports. The analysis of commodity composition and market effects suggests that countries like Canada, the United States, Iceland and Turkey were pursuing the product differentiation policy and were penetrating in those markets, which have been growing relatively faster. These countries remained committed throughout the sample period (i.e., 1980–2000) to export their diversified products in fast-growing markets. The analysis of competitiveness effects, which are derived as a residual, show that Norway, Spain, the United States, Indonesia, Thailand, Chile and China were strong fishery exporters and increased their competitiveness during the sample period.     

The in vivo incorporation and metabolism of [1-14C] linolenate (18:3n-3) in liver, brain and eyes of juveniles of rainbow trout Oncorhynchus mykiss L and gilthead sea bream Sparus aurata L.

Accumulation of docosahexaenoic acid (DHA; 22:6n-3) in brain and eyes during development has been demonstrated in fish but it is not clear whether liver or neural tissues themselves are of greater importance in the biosynthesis of DHA from dietary 18:3n-3. In the present study, we investigated the in vivo metabolism of intraperitoneally injected [1-¹⁴C]18:3n-3 in liver, brains and eyes of young juvenile fish. Metabolism was followed over a 48h time-course in order to obtain dynamic information that could aid the elucidation of the roles of the different tissues in the biosynthesis and provision of DHA from dietary 18:3n-3. The study was performed in both a freshwater fish, rainbow trout Oncorhynchus mykiss L and a marine fish, gilthead sea bream Sparus aurata L to determine the effect that low or limiting5-desaturase activity may have in this process. As expected, the results showed that although the sea bream incorporated more 18:3n-3 into its lipids, metabolism of the incorporated fatty acid by de saturation and elongation was generally greater in the trout. In liver, the percentages of radioactivity recovered in tetraene and pentaene products were greater in trout than in sea bream although there was no difference in hexaenes. In contrast, the re covery of radioactivity in DHA was significantly greater in brain in trout compared to sea bream. In both species, the percentage of radioactivity recovered in desaturated/elongated products was much lower in liver than in brains and eyes, but that percentage increased over the 48h time-course. In trout though, the highest percentages of desaturated products in brain and eye were observed after 12 and 24h, respectively. However in sea bream the highest percentages of desaturated products in the neural tissues were observed after 24-48h. Radioactivity was recovered in 24:5n-3 and 24:6n-3, intermediates in the 4-independent ("Sprecher shunt") pathway for the synthesis of DHA, in both species, especially in the brain and eyes. Overall, although the results cannot eliminate a role for liver in the biosynthesis and provision of DHA for developing neural tissues in fish, they suggest that DHA can be synthesised in fish brain and eye in vivo.     

东海绿鳍马面鲀产卵群体结构和产卵场调查

1.东海绿鳍马面鲀产卵群体自从开发利用以来,体长、年龄和体重组成出现了两次增大两次变小的过程。即1974—1976年和1981—1983年的个体较大,1977—1980年和1984年的个体较小,而1985年的个体最小。但性腺成熟系数却在提高,表明资源的密度在降低。 2.绿鳍马面鲀不同生活阶段的性比不一样,产卵期雄鱼的比例最高,越冬期居次,索饵期雌雄比例基本相等。 3.从产卵个体、仔稚鱼和产卵盛期渔获量的分布判断东海绿鳍马面鲀的产卵场在25°30′—30°00′N、122°00′—126°30′E海区,范围较广,主要产卵场在25°45′—27°00′N、122°00′—123°30′E,水深100—120米的海区。 4.东海绿鳍马面鲀的产卵期在3月底至5月下旬,4月中下旬为产卵盛期。 5.从雌鱼性腺V_A、V_B期比例的周日变化判断绿鳍马面鲀产卵的主要时间在23时至翌日11时。 6.从绿鳍马面鲀人工授精卵附着实验的结果和产卵场环境条件的对照,说明海洋里的贝砾类、海藻、海绵体和珊瑚等物体是马面鲀卵的良好附着基。