海水网箱养殖控温存在难度

正在这一次超级寒潮中,广东地区渔业生产遭受严重损失,近海海水网箱养殖也受到严重打击。对于这一现象,中山大学教授、海水网箱养殖专家黎祖福无奈表示,目前针对海水网箱养殖并没有直接有效的抗寒办法。"海水网箱养殖前期要考虑几个因素,包括海域的选择和网箱的深度。"黎祖福说,海水的水深差每5米就存在温差2~3℃,看上去这2℃不起眼,但事实上,一些不耐寒的品种,从健康状态到冻伤,就差这2~3度。     

抗寒现场之饶平篇 鮸鱼之殇

正饶平县是广东省海洋大县,全县涉海(渔)6个镇40多万人口。依托海洋资源优势,渔民筑海而居发展海水网箱养殖,饶平成为国内面积最大的海水网箱养殖基地之一。在柘林湾的海面上,拥有海水网箱8万多个,面积153.58公顷,养殖品种主要为鮸鱼、篮子鱼、鰤鱼、金鲳鱼、珍珠龙胆等。据了解,饶平当地的海水网箱养殖水深一般为5~6米。本次寒潮来袭,饶平最低气温达到了1℃,最冷1月25日中午海水的温度为10℃。尽管在寒潮来临前,县海洋与渔业局就已经     

利用大菱鲆养殖循环水养殖刺参模式介绍

目前,北方大菱鲆工厂化养殖多利用地下深井海水,水温常年恒定在13℃~18℃之间,利用大菱鲆养殖循环水养殖刺参模式,就是利用地下深井海水抽出后,先在大菱鲆养殖池中循环,然后排放到参池中进行刺参养殖,以充分利用地下水资源。由于刺参养殖水源的水温较低,成功解决了刺参渡夏的难题,同时,水源中含有丰富的鱼类残饵和粪便,可供刺参摄食,刺参整个养殖过程中基本不用添加人工饲料,降低了养殖成本。一、选址建池在大菱鲆养殖大棚附近,选择空地开挖参池,一般1000m2的养鱼大棚按照每天3个~5个水循环量计算,可以供给面积2亩~5亩的参池用水。参池单池…     

海水养殖杂交鲟对环境变化耐受性的试验研究

试验结果表明:海水养殖杂交鲟的适宜温度为5.0~22.0℃,临界上限水温为26.0℃,临界下限水温为3.0℃;耐受盐度的范围比较广泛,为1.0~38.0,适宜养殖的盐度为8.0~32.0;耐pH值的范围为4.7~9.8,适宜养殖的pH值为6.9~8.8。杂交鲟对环境变化耐受性范围较大,可以保证杂交鲟可以更好地适应其生存环境,以避免由于环境因子的激变造成海水养殖杂交鲟的大规模死亡。     

四种中草药多糖对梭鱼苗诱食效果的研究

<正>0前言梭鱼(Barracuda,Pike),又名红眼鱼、肉棍子,属于鲻形目的鲻科。其适盐、适温范围广,从35‰的高盐度海水到5‰的淡水均能存活,温度范围为0~35℃,最适生长温度为18~28℃[1]。梭鱼不仅能在海水和咸淡水中养殖,还可在淡水     

世界水产养殖生产结构特点

据最新统计分析 ,世界水产养殖生产结构呈现出以下特点 :世界水产养殖总产量的 91 3%来自亚洲(4172万吨 ) ,其次是欧洲 (2 0 3万吨 )、南美洲和加勒比海地区 (87万吨 )、北美洲 (5 5万吨 )、非洲 (40万吨 )和大洋洲 (14万吨 )。世界水产养殖产量的 5 4 9%来自海水养殖(包括半咸水养殖 ) ,4 5 1%来自淡水养殖。淡水水产养殖主要以鱼类为主 ,占 97 7% ;半咸水养殖以贝壳类和鱼类为主 ,分别为5 0 5 %、4 2 7% ,而海水养殖的主要种类是软体动物和水产植物 ,分别占海水养殖的 4 6 1%和4 4%。鲤科鱼类养殖占世界水产养殖产量的一半以上 ,海水…     

低盐度虾蟹混养高效技术初探

浙江嘉兴市毗邻杭州湾,有25万余亩的沿海低盐度养殖水域,表层海水常年盐度4~10,温度4~29℃。为了充分利用这一自然资源,我们于2002年起开始研究南美白对虾、斑节对虾、脊尾白虾与青蟹在低盐度水体中的混养技术。一、材料与方法1郾地点选择海盐县西塘桥镇东港村的沿海养殖基地中     

在咸淡水中条纹鲈生长快

加拿大渔业科学中心，将条纹鲈鱼苗分别放养在淡水和海水中养殖，淡水水温由4℃逐渐升至21℃，海水水温由1．5℃上升至14．5℃。同期放养，同期测量，发现养在淡水中的条纹鲈叉长增长了8cm，而养在海水中的同批鲈又长只增长3．5cm。养在淡水中的条纹鲈成活率为86％，而养在海水中的条纹鲈成活率为49．8％。在淡水、咸淡水、海水中养殖的条纹鲈，分别进行了3次升温试验，升温从18℃至24℃，发现养在咸淡水中的条纹护生长最快，叉长增长19cm，成活率也最高，达93％。在咸淡水中条纹鲈生长快@任维美     

国外渔业文摘

正陆基封闭式淡水养殖系统和海水网箱养殖系统的经济效益和碳足迹比较大西洋鲑的海水网箱养殖年产量正向200万吨迈进,并已证明是一种具有成本效益和能效的养殖模式。近年来,随着技术进步,在陆基封闭式(LBCC)循环水养殖系统(RAS)中将大西洋鲑鱼从鱼卵养殖至4~5 kg适销尺寸的淡水养殖技术已被证明是一种可行的生产技术。陆基养殖系统     

双斑东方鲀海水网箱养殖技术

<正>笔者在福建宁德市三都澳开展了双斑东方鲀海水网箱养殖试验,取得成功。现将养殖技术介绍如下。一、养殖海区和试验时间试验海区选择在福建省宁德市三都澳界溪海域,水质良好,水深≥7米,流速约0.5米/秒,潮流顺畅,透明度500~900毫米,盐度20~31,溶解氧≥5毫克/升,p H值7.5~8.0,海水温度10.5~29.5℃。二、网箱规格和材料试验采用浮动式木结构渔排,规格为4.8米×4.8米×4.0米,聚乙烯网衣,网衣随苗种长大,     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

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.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

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.     

Evaluation of a Fast Method Based on the Presence of Two Restriction Sites in the Mitochondrial ND5 (mt ND5) Gene for the Identification of Scomber Species

The purpose of this work was to evaluate the suitability of a method based on the presence of two restriction sites (for Hae III and Hindf I) in the mitochondrial NADH dehydrogenase subunit 5 (mt ND5) gene to identify Scomber species. The evaluation was performed on 144 reference and market samples by sequencing of the entire 505-bp fragment of the mt ND5 gene and of a 464-bp fragment of the Kocher fragment of the cytochrome b gene (mt Cytb). Sequence analysis of any of the two fragments allows the identification of each of the four Scomber species, but S. japonicus and S. colias had the same restriction sites at the ND5 amplicon and would not have been differentiated by this analysis. Similarly, loss of the Hae III site in some S. scombrus individuals would have misidentified them as not being Scomber. All the market products were correctly labeled except one acquired in Spain labeled as originating in the Atlantic and containing S. japonicus.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

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.     

Growth hormone (GH) and reproduction: a review

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.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

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.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

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).