首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
大海不缺水,缺少的是人类的信心.从历史发展的眼光看,谁征服了海洋,谁就拥有一切.浩瀚的海洋上,气象变化万千,时而万里无云,风平浪静,碧波粼粼,富有诗情画意,令人陶醉.时而狂风暴雨,白浪滔天,汹涌澎湃,一泻千里.然后,在这高深莫测的海洋深处,却有数不清的鱼类,它们是千姿百态海洋生物中的一族.  相似文献   

2.
1.美国银斑的生物学特性 美国银斑又称斑点鲈,学名为黑莓鲈(Pomoxisnigromacufastus),分类上属鲈形目,日鲈科,莓鲈属.该鱼盛产于北美地区,自然分布广,东西跨越整个美国.该鱼体形侧扁,体型近似广东鲂,但鱼体短一些,体较高,头短小,口小,口上位,眼大,眼中部有一垂直黑色条纹,侧线完全明显,尾柄稍长低位,背鳍、尾鳍、胸鳍、腹鳍、臀鳍发达,背鳍鳍棘6枚,臀鳍鳍棘5枚,尾鳍呈扇形末端稍凹,头背部为橄榄色或灰绿色,两侧腹部多为银灰白色,鳞片光鲜发亮,在头部和体侧有不规则的黑斑,体色鲜艳明亮.  相似文献   

3.
<正>近年来,由于国内其他产业的不平衡发展,农村劳力外出打工,加之养猪业的投资大,风险大,受市场和疫病的影响,养殖者收入没有保障,引起生猪货源短缺,猪肉紧俏,价格上扬,给国民经济的发展形成严重影响。去年以来,国务院出台了鼓励养猪业发展的优惠政策,  相似文献   

4.
王文彬 《海鲜世界》2006,(2):16-17,19
近年来我国渔业经济总体上呈现良好态势,水产品总量持续增长,水产品市场供应充足,品种丰富,购销两旺,水产品综合价格稳中有升,并且出口市场一直保持旺销局面.但是,从整个市场走势来看,目前乃至今后比较长的一段时期内,我国水产品市场仍属于买方市场,水产品市场增收的空间依然十分狭小,国际贸易仍存在较大变数.总之,一句话,"利害两相依,竞争无穷期".如何在这样一个市场大势之下,改革创新,扬长避短,趋利避害,扭亏增效,是值得深思的问题.下面根据实际谈几点看法,仅作参考.  相似文献   

5.
澳洲淡水龙虾原产澳洲,生活在淡水中,外形酷似海中龙虾而得名.该虾体大肥厚,一般个体重100~200g,最大个体可达500g,其生长快,产量高,当年放养当年可收获,每亩(1亩=1/15公顷,下同)鲜虾产量达500kg左右,加之该虾营养丰富,风味鲜美,又耐长途运输,适于鲜虾上市,因而市场前景广阔,经济效益显著.……  相似文献   

6.
王孝忠 《畜禽业》2008,(4):87-88
<正>我市某鸡场饲养2000只蛋鸡,产蛋率达92.2%以上,于2007年12月28日,突然发病,产蛋率下降,出现死亡,到许多地方进行诊断治疗,不见效果,死亡不断增加,因而前来就诊。根据现场调查,临床症状,病理变化,实验室诊断确诊为鸡新城疫和大  相似文献   

7.
《渔业现代化》1974,(2):1-2
咱大渔岛是黄海边上的一个渔村。全大队共有1219户,5545人。解放前,广大渔民深受三座大山的压迫和剥削,渔民中流传着这样一首歌谣:“大渔岛,苦水塘,鱼行鱼霸似虎狼。吸血秤,包头粮,高利贷,阎王账,一杆秤,一支枪,一包谷,一本账,贫苦渔民遭灾秧。”在旧社会,  相似文献   

8.
熊兵  沈虎泉 《畜禽业》2013,(6):16-17
<正>百脉根为多年生豆科草本植物,主根多分布在30~60cm的土层中,侧根众多,茎根丛生,茎长60~90cm,光滑,斜生或直立,掌状三出复叶,小叶叶片倒卵形,先端宽而基部狭,叶柄短,托叶大,与叶片相似,故名五叶草。伞形花序,4~8朵小花组成,位于花梗顶端,花淡黄至深黄色。狭长而圆,聚于花梗顶端,散开,状如鸟足,每荚含种子10~15粒,种子肾形,黑色或黑绿色,千粒重1~1.2g。百脉根性喜温暖湿润气候,抗旱  相似文献   

9.
河口区海岸线长254.37公里,滩涂面积90余万亩,但近几年来,由于养殖病害严重,对虾等水产品养殖效益较低。海蜇是一种大型水母,高蛋白、低脂肪,具有很高的营养价值,而且海蜇养殖具有成本低、市场前景广、销路好、经济效益高的优点,自2004年以来,我们引进海蜇,在河口大北养殖区进行养殖,取得了良好效益,平均亩产海蜇450kg,产值在4000元以上,效益2500元以上。  相似文献   

10.
休闲渔业是指人们劳逸结合的渔业活动方式,是利用海区的自然条件,渔村的人文资源,渔业的生产设备与场所,经过规划设计,以发挥渔业于渔区的休闲旅游上的功能,增进民众对渔村与渔业之体验,提升旅游的品质,并提高渔民收益,促进渔村发展.发展休闲渔业是渔业产业结构调整和可持续发展的战略需求,是旅游经济的重要组成部份,对于保护渔业资源,营造和美化自然环境,丰富人们文化生活,都具有十分重要的意义.  相似文献   

11.
12.
The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.  相似文献   

13.
Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.  相似文献   

14.
Growth hormone (GH) and reproduction: a review   总被引:5,自引:0,他引:5  
Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.  相似文献   

15.
Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg?1 protein) than essential amino acids (425.82 ± 9.15 g kg?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.  相似文献   

16.
17.
In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.  相似文献   

18.
The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg–1 fish·h–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g–1·ml–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min–1·g–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min–1·g–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.  相似文献   

19.
Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL?1 (1.25 ng well?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.  相似文献   

20.
Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号