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91.
Normally Chinese mitten crab Eriocheir sinensis were cultured for 2 years, 1 year is cultured from crab larvae to seeds or button sized crab in ponds, tanks or rice fields, the another year is cultured from seeds to market size in ponds, reservoirs or other waters. The present study was conducted to determine the effect of stocking density (0, 3.75, 15, 30 and 60 inds. per m2, respectively) of Chinese mitten crab larvae on rice and crab seed yields in rice-crab culture systems using land-based enclosures (4 m × 7 m, with three replicates for each stocking density) at the Panjin Guanghe Fisheries Co. Ltd, in the Liaohe Delta, China. Zoobenthos biomass, production of crab and rice paddy, and economical profit among the treatments were determined. The experiment showed that zoobenthos biomass in rice-crab culture systems was relatively variant and not significantly correlated to these stocking density. The biomass of aquatic plant declined significantly with increasing stocking density. Specific growth rates (SGR) and survival rates of the crab were significantly higher at the lower stocking density (P < 0.05); in addition, the ratio of precocious crab and total crab significantly increased with the stocking density increasing (P < 0.05); There were not significant effect of presence of crab on yields of rice straw and rice paddy (P > 0.05). Net crab yield and net profit were the highest at the 15 treatment (P < 0.05), however, the net profits among 3.75, 15 and 30 treatments did not show significant difference (P > 0.05) economically. Based on the observations above, a stocking density of 3.75 to 30 inds. per m2 was considered reasonable in rice-crab culture system. 相似文献
92.
Does the wild‐caught Chinese mitten crab megalopae perform better than the hatchery‐produced seed during the juvenile culture? 下载免费PDF全文
Xugan Wu Jie He Xiaodong Jiang Qing Liu Feng Gao Yongxu Cheng 《Aquaculture Research》2018,49(5):2042-2050
Although wild Yangtze Eriocheir sinensis juveniles (coin‐sized seed) have better culture performance than the pond‐reared juveniles during the adult crab culture stage, the culture performance of wild‐caught megalopae (WC) remains unknown. Therefore, this study was designed to compare the growth, survival rate, crab yield, feed conversion rate (FCR), precocity, final weight and size distribution between WC and hatchery‐produced megalopae (HP) during the juvenile culture stage. Wild‐caught megalopae had significantly higher body weight, weight gain rate (WGR) and specific growth rate (SGR) during 0–4 weeks but lower WGR and SGR than HP during 4–8 weeks (p < .05). Although WC had a significantly lower survival rate and yield of normal juvenile crabs than HP, total yields of normal juveniles and precocious crabs were similar. Wild‐caught megalopae had a significantly higher precocious rate and yield of precocious crabs than HP (p < .05). Regardless of sex, no significant differences were found in the gonadosomatic index (GSI), hepatosomatic index (HSI) and final weight of normal juveniles and precocious crabs between WC and HP. As for the size distribution of normal crabs, WC had a higher percentage of small female juveniles (<3 g) but a lower proportion of middle size ranges (3–5.99 g and 6–8.99 g) than HP for females (p < .05), and there was no significant difference for males. In conclusion, wild megalopae of the Yangtze E. sinensis had worse culture performance than the hatchery‐produced seeds; therefore, wild megalopae would not be recommended for commercially juvenile culture of E. sinensis. 相似文献
93.
研究灯笼鱼属仔稚鱼的发育形态与分类特征,为以后相关的海洋生态调查的仔稚鱼种类鉴定提供参考资料,以相关的灯笼鱼属仔稚鱼形态与分类特征文献为依据,对1978年4—5月和8—10月太平洋中部热带水域、1979年5—6月西太平洋热带水域,1984年4—7月、1984年12月—1985年1月和1985年4—6月东海外海黑潮流域调查采集到的灯笼鱼属鱼类的仔稚鱼样品进行分类鉴定,共鉴定了栉刺灯笼鱼、闪光灯笼鱼、粗鳞灯笼鱼、斑点灯笼鱼、金焰灯笼鱼、东方灯笼鱼、钝吻灯笼鱼和灯笼鱼Myctophum sp.等8种仔稚鱼。观察和描述了其个体发育形态,并引用发光灯笼鱼、双灯灯笼鱼、粗短灯笼鱼、短颌灯笼鱼、Myctophum sp1.和Myctophum sp2.的形态特征,构建了目前全球已了解的11种灯笼鱼以及3种未定到种的Myctophum sp.、Myctophum sp1.和Myctophum sp2.仔稚鱼的种类分类检索表。观察结果显示,灯笼鱼属仔稚鱼鱼体细长,头部呈三角形、微扁,眼非圆形,眼部脉络组织发达或有发达眼柄支撑,颊部、胸鳍和鳃盖骨边缘具黑色素,消化管末端内侧或外侧色素均匀分布,两颌生有小利牙,具脂鳍,发育过程除金焰灯笼鱼外均具有发达扇形胸鳍,这是灯笼鱼属仔稚鱼共有的形态特征。金焰灯笼鱼形态特征独特,头部非常扁平,两眼眼柄非常发达,向体外两侧伸展,消化管末端游离于体外。仔稚鱼两眼前后是否具眼柄和眼部脉络组织形状,上下颌骨末端是否具黑色素,胸鳍柄和鳍条间黑色素有无,尾柄末端、脂鳍和臀鳍后缘是否具黑色素斑分布,消化道末端色素的分布等发育形态特征是该属仔稚鱼种类鉴别和分类的主要依据。 相似文献
94.
甲壳动物攻击行为的研究进展 总被引:1,自引:0,他引:1
攻击是动物为了获得食物、空间和配偶等资源或某种利益而发生的与生俱来的行为,即使资源充足时也有可能发生激烈的打斗。这种“天生”的行为也可能与遗传因素有关。 相似文献
95.
96.
Li L Thomas RM Suzuki H De Brabander JK Wang X Harran PG 《Science (New York, N.Y.)》2004,305(5689):1471-1474
We describe the synthesis and properties of a small molecule mimic of Smac, a pro-apoptotic protein that functions by relieving inhibitor-of-apoptosis protein (IAP)-mediated suppression of caspase activity. The compound binds to X chromosome- encoded IAP (XIAP), cellular IAP 1 (cIAP-1), and cellular IAP 2 (cIAP-2) and synergizes with both tumor necrosis factor alpha (TNFalpha) and TNF-related apoptosis-inducing ligand (TRAIL) to potently induce caspase activation and apoptosis in human cancer cells. The molecule has allowed a temporal, unbiased evaluation of the roles that IAP proteins play during signaling from TRAIL and TNF receptors. The compound is also a lead structure for the development of IAP antagonists potentially useful as therapy for cancer and inflammatory diseases. 相似文献
97.
为探究学校供餐计划对人力资本积累的影响,采用文献综述方法,系统回顾和梳理学校供餐计划的国际研究进展,阐明学校供餐计划的概念和理论基础,重点分析其对人力资本积累的短期影响、长期效果以及溢出效应。在此基础上,探究学校供餐计划的方案设计和国际经验,进一步分析现阶段中国农村义务教育学生营养改善计划取得的成效和可能的不足,并提出相应完善建议。结果表明:学校供餐计划对人力资本积累具有重要影响,中国需要进一步构建项目监督和激励机制,结合其他益贫政策,发挥营养健康教育的协同作用,进而提高人力资本和促进乡村振兴。本研究的梳理总结有助于加深对学校供餐计划的认识,同时为我国有效实施营养干预项目,促进儿童人力资本积累和减少贫困代际转移提供借鉴和思考。 相似文献
98.
WANG Xiaodong 《东北农业大学学报(英文版)》2007,14(4):374-379
In order to implement the spirit of the Sixteenth National People's Congress to accelerate development of rural education, deepen reform of rural education,guarantee a well-off society,and harmonize rural and urban development,coordinating rural- urban education is the key to China's development.At present,the rural-urban coordinating education is influenced by many factors, including rural-urban income difference,rural-urban educational resources difference,rural-urban background difference,and rural- urban institutional difference.In order to realize the coordinating development of rural-urban education,we need innovation in"Hukou" institution,land institution,financial institution and rural education institution.Institution innovation would be the guarantee to the coordinating rural-urban education. 相似文献
99.
100.